JP4330485B2 - Injection foam molding method - Google Patents

Description

  The present invention relates to an injection foam molding method and a foam molded article obtained by the injection foam molding method. More specifically, the present invention can effectively prevent jetting (also referred to as snake flow) from occurring in the molten thermoplastic resin injected into the cavity of the mold assembly, The present invention relates to an injection foam molding method for molding a foam molded product having excellent appearance characteristics, and a foam molded product obtained by the injection foam molding method.

  As a method for obtaining a solid molded product made of a thermoplastic resin, there is an injection molding method for obtaining a molded product by cooling and solidifying a molten thermoplastic resin injected into a cavity of a mold. For example, a roller made of a thermoplastic resin is used in various industrial fields such as a field of office equipment such as a paper feeding roller in a copying machine or a facsimile machine. These rollers are not only required to have high mass productivity, but also are lightweight, free from sink marks and warpage, have high surface smoothness, no uneven thickness, and the center axis of rotation coincides with the center of gravity line. And high circularity are strongly required. If the roller does not satisfy these requirements, for example, the paper cannot be fed smoothly and straightly.

  Thus, when a molded product is required to be lightweight, free from sink marks or warpage, an injection foam molding method can be cited as one of methods for molding the molded product.

  Conventionally, foamed molded articles made of a thermoplastic resin are molded using a chemical foaming agent or a physical foaming agent. In a foam molding method using a chemical foaming agent, a thermoplastic resin as a raw material is usually mixed with a low molecular weight organic foaming agent that decomposes at the molding temperature to generate gas, and the mixture is decomposed into an organic foaming agent. By heating above the temperature, the thermoplastic resin is melted and gas is generated by the decomposition of the foaming agent, thereby forming a foam molded product. On the other hand, in a molding method using a physical blowing agent, under pressure, a low-boiling organic compound such as butane, pentane, or dichlorodifluoromethane is supplied to a molten thermoplastic resin, and after kneading, the kneaded product is discharged to a low pressure region. Thus, a foam molded product is formed. Conventionally, as a general injection foam molding method, a method in which an amount of foamable melt molding material that is insufficient to fill the cavity is injected into the cavity and foamed is employed.

  However, in the molding method using these chemical foaming agents or physical foaming agents, it is difficult to achieve miniaturization of the foamed cells and high density and uniform dispersion of the foamed cells. For this reason, foam molded articles obtained by molding methods using these chemical foaming agents or physical foaming agents have problems such as relatively low mechanical strength.

  Accordingly, in order to achieve finer foam cells and higher density and uniform dispersion of the foam cells, Japanese Patent Application Laid-Open No. 10-230528 and Japanese Patent No. 2625576 disclose a foam molding method using a supercritical fluid as a foaming agent. Has been. In these foam molding methods, a supercritical inert gas as a supercritical fluid is sufficiently uniformly dissolved in a molten resin, and this is injected while applying pressure into a mold cavity, and then the pressure in the cavity is reduced. By foaming by rapidly decreasing, a foamed molded product is obtained.

  In the foam molding method using these supercritical fluids as foaming agents, the supercritical fluid can be used for its excellent solubility close to liquid and excellent diffusibility close to gas. It is possible to impregnate the molten resin in a short time. Therefore, it becomes possible to make a foam cell diameter fine and to prevent the strength reduction of a foam molded product.

  On the other hand, in the conventional injection molding method, if there is a large difference between the sectional area of the cavity in the plane perpendicular to the flow of the molten thermoplastic resin in the cavity and the sectional area of the molten resin injection part (gate part), When a molten thermoplastic resin is injected into the jet, jetting occurs, and the appearance and function of the molded product are significantly impaired, and the commercial value of the molded product may be reduced. For molded products, better physical properties (high strength, high impact resistance, high fatigue resistance, high creep resistance, high heat resistance, high warm water resistance, high oil resistance, high chemical resistance, etc.) are required. When used, it is necessary to use a synthetic resin having a high viscosity when melted, such as a high molecular weight type synthetic resin, a crosslinked type synthetic resin, or a synthetic resin alloy. However, when such a synthetic resin is used, there is a problem that jetting tends to occur and it is difficult to obtain a desired molded product having an excellent appearance.

JP-A-10-230528 Japanese Patent No. 2625576 JP-A-8-323818 JP 10-180790 A

  By the way, in the foam molding method using the conventional supercritical fluid disclosed in Japanese Patent Application Laid-Open No. 10-230528 and Japanese Patent No. 2625576, because foam cells (bubbles) exist on the surface of the foam molded product, It is difficult to obtain a foam-molded product having an excellent appearance. That is, the surface smoothness of the molded product is inferior due to foaming marks. In addition, while it is possible to suppress the occurrence of local sink marks and warping, the molded product may have a problem that the strength of the entire foamed molded product is sacrificed, or when rough foaming occurs in the surface layer of the molded product. There are problems such as a decrease in strength of the steel and a problem that the molding cycle becomes long.

  Conventional measures to prevent jetting are to increase the cross-sectional area of the molten resin injection part (gate part), slow down the injection speed of the molten thermoplastic resin, raise the temperature of the molten thermoplastic resin, and melt A method for selecting a resin grade having a low viscosity can be mentioned. However, when the cross-sectional area of the molten resin injection part is increased, the post-treatment of the part corresponding to the molten resin injection part of the molded product is costly. Further, when the injection speed of the molten thermoplastic resin is slowed down, the molding cycle becomes long, and the manufacturing cost of the molded product increases. When the temperature of the molten thermoplastic resin is raised, the thermal stability of the molten thermoplastic resin is impaired, and the appearance of the molded product is deteriorated due to gas generation from the molten thermoplastic resin or a decrease in the molecular weight of the thermoplastic resin. Cause problems. The method of selecting a resin grade with a low melt viscosity is to use a high molecular weight type synthetic resin or a cross-linked type synthetic resin when more excellent physical properties such as high impact resistance and high fatigue resistance are required for molded products. It is not an essential solution because it is necessary to use a synthetic resin having a high viscosity at the time of melting, such as or a synthetic resin alloy.

  As another measure for preventing the occurrence of jetting, a method of arranging a plug in a cavity is known from, for example, Japanese Patent Application Laid-Open Nos. 8-323818 and 10-180790. Although the techniques disclosed in these patent publications are extremely effective as measures for preventing jetting, it is necessary to sufficiently cope with the demand for further weight reduction of molded products having no hollow portion. I can't. Even when a stopper is used, sink marks may occur in the thick part of the molded product, and uneven thickness may occur.

  Accordingly, an object of the present invention is that jetting occurs in the molten thermoplastic resin injected into the cavity of the mold assembly in a short and stable molding cycle without being affected by the thermoplastic resin used. Can effectively prevent the occurrence of local sink marks and warpage, has excellent appearance characteristics, high strength, and has a lightweight solid structure. An object of the present invention is to provide an injection foam molding method for molding a foam molded product, and a foam molded product obtained by such an injection foam molding method.

Hereinafter, description will be made of injection foaming method and foaming molded article of the present invention, the pressure P _R, the pressure P _E, the pressure P _1, the pressure P _2, the pressure P _3, the pressure P _4, the volume V _F of the cavity, The cavity volume V _B is defined as follows.

P _R : Pressure of molten thermoplastic resin in cavity P _{R, MIN} : Minimum pressure of molten thermoplastic resin in cavity P _{R, MAX} : Maximum pressure of molten thermoplastic resin in cavity P _E : Heat of fusion in cavity Pressure P _{1 at} which the plastic resin starts foaming: Pressure (back pressure) exerted by the resin plasticizing / melting means on the molten thermoplastic resin in the cavity during or after the injection of the molten thermoplastic resin into the cavity
P ₂ : Pressure (drag) exerted by the plug body moving means on the plug body during or after the injection of the molten thermoplastic resin into the cavity
P ₃ : In the process of cooling and solidifying the thermoplastic resin in the cavity, the pressure that the resin plasticizing / melting means exerts on the thermoplastic resin in the cavity P ₄ : In the process of cooling and solidifying the thermoplastic resin in the cavity, Pressure (drag) exerted on plug body by plug body moving means
V _F : The plug body is positioned at the forward end in the cavity by the plug body moving means in the step (A) described later. The volume of the cavity at this time (more specifically, the plug body and the fixed mold) Volume of the space formed by the cavity surface that is the surface constituting the cavity of the mold part and the movable mold part)
V _B : Volume of the cavity when the plug body is located at the backward end (more specifically, formed by the plug body and the cavity surface that is a surface constituting the cavity of the fixed mold portion and the movable mold portion) Volume of space)

  Furthermore, prior to the description of the injection foam molding method according to the first aspect of the present invention including the preferred form and the injection foam molding method according to the second aspect of the present invention including the preferred form, the description will be simplified. Therefore, various methods are defined as follows.

[Pressure control / foaming suppression method]
In the injection or during injection completion of molten thermoplastic resin into the cavity, the molten thermoplastic resin in the cavity, the pressure P _R is exerted by the plug body and the resin plasticizing and melting means. Here, at the time of injection of molten thermoplastic resin into the cavity, during injection or at the time of injection completion, in order to suppress foaming of the molten thermoplastic resin in the cavity in the entire area of the cavity,
P _{R, MIN} = MIN (P ₁ , P ₂ )> P _E
It is necessary to set the pressure state. On the other hand, in order to suppress the foaming of the molten thermoplastic resin in the cavity in a partial region of the cavity,
P _{R, MAX} = MAX (P ₁ , P ₂ )> P _E
It is necessary to set the pressure state. A method of performing pressure control based on the resin plasticizing / melting means and the plug moving means so as to achieve such a pressure state is referred to as [pressure control / foaming suppression method] for convenience. Note that the _{MIN (P 1, P 2)} , in the case of P ₁ ≦ P ₂ takes the value of P _{R, MIN} = P _1, in the case of P _1> P ₂ is P _{R, MIN} = It means taking the value of P _2. Also, the _{MAX (P 1, P 2)} , in the case of P ₁ ≦ P ₂ is, P _R, a value of _MAX = P _2, in the case of P _1> P ₂ is, P _{R, MAX} = It means taking the value of P _1. Furthermore, P _{R, MIN} and P _R, are collectively and _MAX, may be expressed as P _R.

[Method of suppressing foaming at the initial stage of injection]
In the initial stage of injection of the molten thermoplastic resin into the cavity, P _R > P _E (more specifically, P _{R, MIN} > P _E , or P _{R, MAX} > P _E , In order to achieve the same, the value of the volume V _F of the cavity in the step (A) described later is substantially 0 (more specifically, V _F = 0, or for example, 0 ≦ V _F ≦ The plug body is positioned in the cavity by the plug body moving means so as to be 0.05 V _B ). Then, in the step (D) described later, if the movement of the plug body from the forward end to the backward end is started simultaneously with the start of injection or immediately after the start of injection, the molten thermoplastic resin enters the cavity. At the start of injection, the pressure of the molten thermoplastic resin injected into the cavity can be prevented from suddenly dropping, and the molten thermoplastic resin in the cavity foams from the start of injection into the cavity thereafter. This can be reliably suppressed. That is, the state of the P _R> P _E in the step (E) can be reliably achieved. Incidentally, V _F is the mold structure, a finite volume, it is possible to a larger value the value of V _F by including a portion where the surface appearance quality is not required in a portion corresponding to V _F .

  In the case of executing the [foaming suppression method in the initial stage of injection], when the stopper is disposed at the forward end, the stopper is preferably located close to (in the vicinity of) the molten resin injection portion. Here, the fact that the plug body is located in the vicinity of the molten resin injection part depends on the shape of the foam molded product or the like, but normally the plug that faces the molten resin injection part when the plug body is positioned at the forward end. It means that the body part is 0 mm to 50 mm away from the molten resin injection part. When the plug is positioned at the forward end, the plug is in contact with the cavity surface (the surface constituting the cavity of the fixed mold part and the movable mold part), and the plug is positioned so as to block the molten resin injection part. Also good. When the plug body is positioned at the forward end, if the plug body is too far from the molten resin injection part, the space formed by the cavity surface and the plug body becomes too large, and the molten thermoplastic resin injected into the cavity However, there is a case where jetting cannot be effectively prevented from occurring because the molten thermoplastic resin is not prevented from straightly abutting against the plug body.

[Foaming method in the initial stage of injection (1)]
In the initial stage of injection of the molten thermoplastic resin into the cavity, P _R <P _E (more specifically, P _{R, MIN} <P _E <P _{R, MAX} or P _{R, MAX} <P _E And the same applies to the following) by the plug body moving means so that the value of the volume V _F of the cavity in step (A) described later becomes 0 <V _F <V _B. The plug is placed in the cavity. Then, in the step (D) described later, the movement of the plug body from the forward end to the reverse end is started after the start of injection, and the molten resin filled in the cavity and the plug body do not contact or contact each other. When the plug body resistance is low, when the molten thermoplastic resin starts to be injected into the cavity, the pressure of the molten thermoplastic resin injected into the cavity suddenly drops, and as a result, injection of the molten thermoplastic resin into the cavity starts. From time to time, in the initial stage of injection, the molten thermoplastic resin in the cavity foams in a part of the cavity (when P _{R, MIN} <P _E <P _{R, MAX} ), or foams over the entire area of the cavity. (in the case of _{P R, MAX <P E)} .

[Foaming method in the initial stage of injection (2)]
Alternatively, in the initial stage of the injection of the molten thermoplastic resin into the cavity, in order to _satisfy the condition of P _R <PE, the value of the cavity volume V _F in step (A) described later is 0 ≦ V _F The plug body is positioned in the cavity by the plug body moving means so that <V _B. Then, in the step (D) described later, the movement of the plug body from the forward end to the reverse end is started before the injection starts, and the molten resin filled in the cavity and the plug body do not contact or contact each other. However, when the plug body drag is low, the pressure of the molten thermoplastic resin injected into the cavity suddenly drops when injection of the molten thermoplastic resin into the cavity starts. In the initial stage, the molten thermoplastic resin in the cavity foams in a part of the cavity (when P _{R, MIN} <P _E <P _{R, MAX} ), or foams over the entire area of the cavity (P _R, in the case of _MAX <P _E).

[Foaming method in the initial stage of injection (3)]
Alternatively, the injection early stages of the molten thermoplastic resin into the cavity, in order to the state of P _R <P _E, the value of the volume V _F of the cavity in the step (A) to be described later is substantially 0 As described above, the plug body is positioned in the cavity by the plug body moving means. And in the step (D) described later, when starting the movement of the plug body from the forward end to the reverse end simultaneously with the start of injection of the molten thermoplastic resin, the pressure P ₁ and the pressure P ₂ are:
P _{R, MIN} = MIN (P ₁ , P ₂ ) <P _E
Or again, or
P _{R, MAX} = MAX (P ₁ , P ₂ ) <P _E
If the pressure control is performed based on the resin plasticizing / melting means and the plug moving means so as to be in the state, the molten thermoplastic resin in the cavity from the start of injection into the cavity to the initial stage of the injection becomes a part of the cavity. Foaming occurs in the part (when P _{R, MIN} <P _E <P _{R, MAX} ), or foams over the entire area of the cavity (when P _{R, MAX} <P _E ).

  In the following description, [foaming method (1) in the initial injection stage], [foaming method (2) in the initial injection stage] and [foaming process (3) in the initial injection stage] are collectively referred to as [initial injection stage]. It may be referred to as “foaming method in stage”. That is, the [foaming method in the initial stage of injection (1)], [foaming method in the initial stage of injection (2)] or [foaming method in the initial stage of injection (3)] Sometimes expressed as execution.

[Foaming method during injection or until completion (1)]
From the start of injection of molten thermoplastic resin into the cavity from the injection or during injection of up to completion of the injection, in order to the state of P _R <P _E is [foaming process in injection early stages (1) described above or [Foaming method (2) in the initial stage of injection] is executed, and then the pressure P ₁ and the pressure P ₂ are
P _{R, MIN} = MIN (P ₁ , P ₂ ) <P _E
Or again, or
P _{R, MAX} = MAX (P ₁ , P ₂ ) <P _E
The pressure control may be performed based on the resin plasticizing / melting means and the plug moving means so as to be in the state described above, or the [foaming method (3) in the initial injection stage] may be continued.

[Foaming method during injection or until completion (2)]
Injected in the molten thermoplastic resin into the cavity, or from during injection to the exit completion, to the state of P _R <P _E, the pressure P _1, the pressure P _2,
P _R = P ₁ −P ₂ <P _E
The pressure may be controlled based on the resin plasticizing / melting means and the plug moving means so as to be in this state.

[Foaming method during cooling and solidification]
To the P _R <P _E in the step of cooling and solidifying the thermoplastic resin in the cavity,
(1) Two kinds of positive methods such as reducing pressure P ₃ based on control of resin plasticizing / melting means (2) reducing pressure (drag) P ₄ based on control of plug moving means not only,
(3) With the cooling and solidification of the molten thermoplastic resin in the molten resin flow path and / or the molten resin injection part, the transmission of the pressure P ₃ is hindered. (4) For cooling and solidifying the molten thermoplastic resin in the cavity. Along with this, two types of passive methods in which the volume of the thermoplastic resin in the cavity contracts can be mentioned. These four methods are collectively referred to as “foaming method during cooling / solidification” for convenience, and each method is referred to as [foaming method during cooling / solidification (1)], [foaming method during cooling / solidification ( 2)], [foaming method during cooling / solidification (3)], and [foaming method during cooling / solidification (4)]. As the [foaming method during cooling / solidification], any one of these four foaming methods during cooling / solidification may be employed, or any combination of a plurality of methods may be employed.

  In the combination of [foaming method during cooling / solidification (1)] and [foaming method during cooling / solidification (4)], in the step of cooling / solidifying the thermoplastic resin in the cavity, The pressure applied to the molten thermoplastic resin in the cavity is set below the pressure at which the gas in the molten thermoplastic resin in the cavity can foam, and the volume inside the cavity due to the cooling and solidification of the thermoplastic resin in the cavity is reduced. The gas may be foamed based on the pressure drop in the thermoplastic resin, and in order to ensure the gas foaming, the application of pressure to the molten thermoplastic resin in the cavity is stopped, and the thermoplastic resin in the cavity is stopped. It can also be set as the structure which foams gas based on the pressure fall in the thermoplastic resin in a cavity resulting from the volume reduction accompanying cooling and solidification.

As a more specific method of [Method of foaming during cooling / solidification (1)]
(1-A) Based on the control of the resin plasticizing / melting means, not only the configuration for stopping the operation (pressure holding operation) of applying pressure to the molten thermoplastic resin in the cavity,
(1-B) A configuration in which the molten resin injection portion is mechanically closed to stop applying pressure to the molten thermoplastic resin in the cavity (for example, the molten resin injection portion is a valve gate, for example, and molten resin injection is performed. The specific means for mechanically closing the part is a shut-off pin)
(1-C) Configuration that stops applying pressure to the molten thermoplastic resin in the cavity by mechanically closing the molten resin flow path (for example, based on a combination of a valve gate and a shut-off pin)
(1-D) Configuration to stop applying pressure to the molten thermoplastic resin in the cavity by mechanically closing the resin plasticizing / melting means (based on, for example, a shut-off valve)
Any one of, or be an arbitrary combination of the structure of these (1-A) ~ (1 -D), the molten thermoplastic resin in the cavity in a state of P _R <P _E Therefore, it is preferable from the viewpoint that foaming surely occurs in the cavity.

  As a specific example of [the foaming method (3) at the time of cooling and solidification], that is, as a specific method of solidifying the molten thermoplastic resin in the molten resin injection portion, for example, completion of injection of the molten thermoplastic resin into the cavity Thereafter, a part of the heating means arranged in the mold assembly (the part of the heating means arranged in the vicinity of the molten resin injection part) is deactivated, so that the molten thermoplastic resin present in the molten resin injection part The method of lowering | hanging the temperature of and solidifying can be mentioned. Also, by reducing the cross-sectional area of part or all of the molten resin flow path, the time required for cooling and solidifying the molten thermoplastic resin present in the molten resin injection part compared to the molten thermoplastic resin in the cavity The method of shortening can be mentioned.

[Method of suppressing foaming during cooling and solidification]
In the step of cooling and solidifying the thermoplastic resin in the cavity, in order to achieve P _R> P _E is
(1) The pressure P ₃ is increased based on the control of the resin plasticizing / melting means. (2) The pressure (drag) P ₄ is increased based on the control of the plug moving means. . These two methods are collectively referred to as “foaming suppression method during cooling / solidification” for convenience, and the respective methods are referred to as “foaming suppression method (1) during cooling / solidification” and “foaming during cooling / solidification”. It calls the suppression method (2)]. As the [foaming suppression method during cooling / solidification], [foaming suppression method during cooling / solidification (1)] or [foaming suppression method during cooling / solidification (2)] may be employed, A combination of the foam suppression method (1) during cooling / solidification and the foam suppression method (2) during cooling / solidification may be employed.

Here, in the operation (pressure holding operation) for increasing the pressure P ₃ , the resin plasticization / melting means passes through the molten thermoplastic resin existing in the molten resin flow path and the molten resin injection portion to enter the cavity. Pressure is applied to the thermoplastic resin. In the pressure holding operation, the pressure applied to the thermoplastic resin in the cavity depends on the mold temperature during injection (temperature of the cavity surface when the molten thermoplastic resin is injected into the cavity), the type and temperature of the thermoplastic resin, and the pressure used. Although it varies depending on the type of gas and cannot be determined uniquely, it is preferably 5 × 10 ⁶ Pa or more, more preferably 1.5 × 10 ⁷ Pa or more. In addition, the duration of holding pressure varies depending on the mold temperature during injection, the type and temperature of the thermoplastic resin, the type of gas used, the thickness of the foamed molded product, and the desired weight reduction rate. Although it cannot be determined, it is preferably 0.2 seconds or longer, more preferably 1.0 seconds or longer, preferably 15 seconds or shorter, more preferably 10 seconds or shorter.

In order to achieve the above object, an injection foam molding method according to the first aspect of the present invention comprises:
A resin plasticizing / melting means for plasticizing / melting a thermoplastic resin, and a mold assembly,
The mold assembly includes a fixed mold part, a movable mold part, a plug body, and plug body moving means for moving the plug body,
The mold assembly includes a cavity formed by clamping a fixed mold part and a movable mold part, a molten resin injection part opened in the cavity, and a molten resin injection part and resin plasticizing / melting means, A molten resin flow path connecting
The plug body is an injection foam molding method using an injection molding apparatus that can move in the cavity substantially parallel to the flow axis direction of the molten thermoplastic resin injected from the molten resin injection section by the operation of the plug body moving means. There,
(A) Before the injection of the molten thermoplastic resin into the cavity, the plug body is positioned at the forward end in the cavity by the plug body moving means,
(B) After plasticizing and melting the thermoplastic resin by resin plasticizing and melting means, dissolving the gas in the molten thermoplastic resin, and weighing the molten thermoplastic resin,
(C) It is weighed from the resin plasticizing / melting means into the cavity formed by clamping the fixed mold part and the movable mold part via the molten resin flow path and the molten resin injection part. Injecting molten thermoplastic resin
(D) Before the injection of the molten thermoplastic resin into the cavity, simultaneously with the start of the injection, or after the start of the injection, from the advance end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity Start the movement of the plug toward the reverse end,
(E) During the injection of the molten thermoplastic resin, the plug body is continuously moved toward the rearward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity,
(F) The injection of the molten thermoplastic resin is completed, and at the same time, the plug body is positioned at the reverse end by the molten thermoplastic resin injected into the plug body moving means and / or the cavity,
(G) Cool and solidify the thermoplastic resin in the cavity, then
(H) Open the fixed mold part and the movable mold part and take out the foam molded product.
Comprising each step,
In the step (H), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Wherein in the step (F), by the state of P _R> P _E, it suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), by the state of P _R <P _E, and wherein the foaming molten thermoplastic resin in the cavity.

In injection foam molding method according to the first aspect of the present invention, the state of P _R> P _E in the step (F) can be achieved by the execution of the pressure control and foam suppression method. The same applies to the method 1A, the method 1a, the method 1B, the method 1b, the method 1C, the method 1c, the method 1D, and the method 1d described below. The state of P _R <P _E in the step (G) can be achieved by the execution of the foaming process during cooling and solidification. The same applies to the method 1A and the method 1a described below.

In the injection foaming process according to the first aspect of the present invention, in the step (E), by the state of P _R> P _E, suppressing structure foaming molten thermoplastic resin in the cavity (See case [1-1] in FIG. 1). Such a configuration is referred to as the method 1A for convenience.

State of P _R> P _E in the step (E) of the method of the 1A can be achieved by the execution of the pressure control and the foam control method] and [the foam control method in an injection early stage. In the step (E), P values of _R (more specifically, the value of P _{R, MIN} Alternatively P _{R, MAX,} the same applies hereinafter) may be constant, varied May be. Also, usually, the value of P _R in the final stage of the process (E), the value of P _R in step (F) is the same value. The above description can be similarly applied to the 1B method, the 1C method, the 1D method, and the 1G method described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention, in the step (E), by _changing the state of P _R <P _{E to} the state of P _R > P _E , It can be set as the structure which suppresses foaming of this molten thermoplastic resin (refer case [2-1] of FIG. 2 or case [3-1] of FIG. 3). Such a configuration is referred to as the method 1a for convenience.

From the state of P _R <P _E to P _R > P _E in step (E) of the method 1a, the [foaming method in the initial stage of injection] is executed, followed by the [pressure control / foaming suppression method]. Can be achieved by executing. In the step (E), the value of P _R changes, in the state of P _R> P _E, the value of P _R may be a constant or may be changed. Also, usually, the value of P _R in the final stage of the process (E), the value of P _R in step (F) is the same value. Further, in the step (E) is in the state of P _R <P _E. The above description can be similarly applied to the method 1b, the method 1c, the method 1d, and the method 1g described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. To obtain a structure in which a foam layer is laminated,
It can be configured (see case [1-2] in FIG. 1). Note that such a configuration is referred to as a method 1B for convenience.

The repetition of the state of P _R > P _{E and} the state of P _R <P _E in the step (G) of the method 1B is [foaming suppression method (1) during cooling / solidification] and / or [cooling / solidification]. This can be achieved by performing a combination of the method of suppressing foaming at time (2)] and the method of foaming at cooling / solidification (1) and / or the method of foaming at cooling / solidification (2). The above description can be similarly applied to the method 1b, the method 1G, and the method 1g described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. To obtain a structure in which a foam layer is laminated,
It can be configured (see case [2-2] in FIG. 2 or case [3-2] in FIG. 3). Such a configuration is referred to as the method 1b for convenience.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
It can be configured (see case [1-3] in FIG. 1). In addition, such a structure is called the 1C method for convenience.

State of P _R> P _E immediately after the start of the step (G) of the method of the 1C is [foam control method at the time of cooling and solidifying (1)] and / or [the foam control method at the time of cooling and solidification (2) it can be achieved by the execution of, the state of the subsequent P _R <P _E can be achieved by the execution of the foaming process during cooling and solidification. The above description can be similarly applied to the method 1c and the method 1E described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
It can be configured (see case [2-3] in FIG. 2 or case [3-3] in FIG. 3). Such a configuration is referred to as the method 1c for convenience.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [1-4] in FIG. 1). Such a configuration is referred to as a 1D method for convenience.

State of P _R> P _E immediately after the start of the step (G) of the 1D method, [foam control method at the time of cooling and solidifying (1)] and / or [the foam control method at the time of cooling and solidification (2) The subsequent repetition of the state of P _R <P _{E and} the state of P _R > P _E can be achieved by [foaming method during cooling / solidification (1)] and / or [cooling / It can be achieved by executing a combination of the foaming method (2) during solidification and the [foaming suppression method (1) during cooling / solidification] and / or [foaming suppression method (2) during cooling / solidification]. it can. The above description can be similarly applied to the 1d method and the 1F method described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [2-4] in FIG. 2 or case [3-4] in FIG. 3). Such a configuration is referred to as a 1d method for convenience.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
Wherein in the step (E), the state of P _R <P _E,
In the step (F), instead of setting P _R > P _E , P _R <P _E is set,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
(See case [1-5] in FIG. 1, case [2-5] in FIG. 2 or case [3-5] in FIG. 3). In addition, such a structure is called the 1E method for convenience. In the first E method, the state of P _R > P _E may be set simultaneously with the start of the step (G), or immediately after the start of the step (G), the state of P _R <P _E is set. it may be used as the state of the P _R> P _E.

State of P _R <P _E in the step (E) of the method of the 1E, and the state of P _R <P _E in the step (F) is the execution of the foaming process to the exit in or complete (1)] Can be achieved. Further, in the state of P _R <P _E in the step (E), there may be included a portion in a state of P _R > P _E. The above description can be similarly applied to the first F method described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention,
Wherein in the step (E), the state of P _R <P _E,
In the step (F), instead of setting P _R > P _E , P _R <P _E is set,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [1-6] in FIG. 1, case [2-6] in FIG. 2 or case [3-6] in FIG. 3). In addition, such a structure is called the 1st F method for convenience. This even in the 1F method, may be used as the state of the P _R> P _E simultaneously start and step (G), immediately after the start of the step (G) is a state of the P _R <P _E, then it may be used as the state of the P _R> P _E.

Alternatively, the first In the injection foaming process according to the embodiment of the present invention, in the step (E), the state of P _R> P _E, then, over the step (G), P _R < repeating the states of the state and P _R> P _E of P _E, it can be a non-foamed layer in the depth direction of the molded foam and the foam layer is configured to obtain a laminated structure (in FIG. 1 case [ 1-7]). In addition, such a structure is called the 1G method for convenience.

In the first G method, the state of P _R > P _E is set before the step (E), and the state of P _R <P _E is set after the step (E), the steps (F) and (G). and repeating the state of the P _R> P _E. The state of P _R > P _E in the latter stage of step (E) and in step (F) is achieved by executing [pressure control / foaming suppression method] and [foaming method during injection or until completion (2)]. be able to. The above description can be similarly applied to the method 1g described below.

Alternatively, in the injection foam molding method according to the first aspect of the present invention, in the step (E), after changing from P _R <P _E to P _R > P _E , G) Repeating the state of P _R <P _{E and} the state of P _R > P _E to obtain a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product. (See case [2-7] in FIG. 2 or case [3-7] in FIG. 3). Such a configuration is referred to as the 1g method for convenience.

In the method 1g, the state of P _R <P _E is changed to the state of P _R > P _E before the step (E), and the step (F) and the step (G) are performed after the step (E). , P _R <P _E and P _R > P _E are repeated.

The injection foam molding method according to the second aspect of the present invention for achieving the above object is as follows:
A resin plasticizing / melting means for plasticizing / melting a thermoplastic resin, and a mold assembly,
The mold assembly includes a fixed mold part, a movable mold part, a plug body, and plug body moving means for moving the plug body,
The mold assembly includes a cavity formed by clamping a fixed mold part and a movable mold part, a molten resin injection part opened in the cavity, and a molten resin injection part and resin plasticizing / melting means, A molten resin flow path connecting
The plug body is an injection foam molding method using an injection molding apparatus that can move in the cavity substantially parallel to the flow axis direction of the molten thermoplastic resin injected from the molten resin injection section by the operation of the plug body moving means. There,
(A) Before the injection of the molten thermoplastic resin into the cavity, the plug body is positioned at the forward end in the cavity by the plug body moving means,
(B) After plasticizing and melting the thermoplastic resin by resin plasticizing and melting means, dissolving the gas in the molten thermoplastic resin, and weighing the molten thermoplastic resin,
(C) It is weighed from the resin plasticizing / melting means into the cavity formed by clamping the fixed mold part and the movable mold part via the molten resin flow path and the molten resin injection part. Injecting molten thermoplastic resin
(D) Before the injection of the molten thermoplastic resin into the cavity, simultaneously with the start of the injection, or after the start of the injection, from the advance end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity Start the movement of the plug toward the reverse end,
(E) During the injection of the molten thermoplastic resin, the plug body is continuously moved toward the rearward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity,
(F) completing the injection of the molten thermoplastic resin;
(G) Thereafter, the plug body is further moved toward the reverse end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity,
(H) The plug body is positioned at the rear end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, and then
(I) Cool and solidify the thermoplastic resin in the cavity, then
(J) Open the fixed mold part and the movable mold part and take out the foam molded product.
Comprising each step,
When the pressure of the molten thermoplastic resin in the cavity P _R, the pressure of the molten thermoplastic resin in the cavity starts foaming was P _E,
In the step (H), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (I), by the state of P _R <P _E, and wherein the foaming molten thermoplastic resin in the cavity.

In injection foam molding method according to the second aspect of the present invention, the state of P _R> P _E in the step (H) may be accomplished by the execution of the pressure control and foam suppression method. The above description also applies to the method 2A, method 2a, method 2B, method 2b, method 2C, method 2c, method 2D, method 2D, and method 2d described below. The same can be applied. The state of P _R <P _E in the step (I) can be achieved by the execution of the foaming process during cooling and solidification. The above description can be similarly applied to the method 2A and the method 2a described below.

In the injection foaming process according to the second aspect of the present invention, the step (E), in the step (F) and step (G), by the state of P _R> P _E, in the cavity It can be set as the structure which suppresses foaming of a molten thermoplastic resin (refer case [4-1] of FIG. 4). Such a configuration is referred to as the method 2A for convenience.

The state of P _R > P _E in step (E) of the method 2A can be achieved by executing [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] in step (E). . The above description is similarly applied to the 2B method, 2C method, 2D method, 2E method, 2F method, 2J method, and 2K method described below. Can do.

Moreover, the state of P _R > P _E in the step (F) of the second A method can be achieved by executing the [pressure control / foaming suppression method] in the step (F). The above description is based on the method 2a, method 2B, method 2b, method 2C, method 2c, method 2D, method 2d, method 2d, method 2E, The same applies to the method 2e, the method 2F, the method 2f, the method 2K, and the method 2k.

Furthermore, the state of P _R > P _E in the step (G) of the method 2A can be achieved by executing the [pressure control / foaming suppression method] in the step (G). The above description applies to the method 2a, method 2B, method 2b, method 2C, method 2c, method 2D, method 2d described below as well. Can do.

In the step (E), to the value of P _R may be a constant or may be changed. Typically, the value of P _R in the value of P _R and step (F) in the final stage of the process (E) is the same value. In the step (G), to the value of P _R may be constant, but may be changed, usually, than the value of P _R in step (F), the value of P _R in step (G) is Low. Furthermore, usually, the value of P _R in the value of P _R and step (H) in the final stage of the process (G) is the same value.

Alternatively, in the injection foam molding method according to the second aspect of the present invention, in the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and the step (F) In the step (G), by setting P _R > P _E , it is possible to suppress the foaming of the molten thermoplastic resin in the cavity (case [5-1] in FIG. 5 or FIG. 6). Case [6-1]). Such a configuration is referred to as the method 2a for convenience.

From the state of P _R <P _{E to} the state of P _R > P _E in step (E) of the method 2a, the execution of [foaming method in the initial stage of injection] is followed by [pressure control / foaming suppression method] Can be achieved by executing. Further, in the state of P _R <P _E in the step (E), there may be included a portion in a state of P _R > P _E. The above description applies in the same way to the method 2b, method 2c, method 2d, method 2e, method 2f, method 2j, method 2k, and method 2k described below. Can do.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (I), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. To obtain a structure in which a foam layer is laminated,
It can be configured (see case [4-2] in FIG. 4). In addition, such a structure is called the 2B method for convenience.

The repetition of the state of P _R > P _{E and} the state of P _R <P _E in step (I) of the method 2B is [foaming suppression method (1) during cooling / solidification] and / or [cooling / solidification]. This can be achieved by performing a combination of the method of suppressing foaming at time (2)] and the method of foaming at cooling / solidification (1) and / or the method of foaming at cooling / solidification (2). The above description can be similarly applied to the method 2b, the method 2J, the method 2j, the method 2K, and the method 2k described below.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity Suppresses foaming of molten thermoplastic resin,
In the step (I), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. To obtain a structure in which a foam layer is laminated,
It can be configured (see case [5-2] in FIG. 5 or case [6-2] in FIG. 6). Such a configuration is referred to as the method 2b for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
It can be configured (see case [4-3] in FIG. 4). In addition, such a structure is called the 2C method for convenience.

State of P _R> P _E immediately after the start of the step (I) of the method of the 2C is [foam control method at the time of cooling and solidifying (1)] and / or [the foam control method at the time of cooling and solidification (2) can be achieved by the execution of, the state of the subsequent P _R <P _E can be achieved by the execution of the foaming process during cooling and solidification. The above description can be similarly applied to the method 2c, the method 2E, the method 2e, and the method 2G described below.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity Suppresses foaming of molten thermoplastic resin,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
It can be configured (see case [5-3] in FIG. 5 or case [6-3] in FIG. 6). Such a configuration is referred to as a method 2c for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [4-4] in FIG. 4). Such a configuration is referred to as a 2D method for convenience.

State of P _R> P _E immediately after the start of the step (I) of the 2D method, [foam control method at the time of cooling and solidifying (1)] and / or [the foam control method at the time of cooling and solidification (2) The subsequent repetition of the state of P _R <P _{E and} the state of P _R > P _E can be achieved by the following [Foaming method (1) during cooling / solidification] and / or [Cooling / It can be achieved by performing a combination of the foaming method (2) during solidification and the [foaming suppression method (1) during cooling / solidification] and / or [foaming suppression method (2) during cooling / solidification]. it can. The above description can be similarly applied to the 2d method, the 2F method, the 2f method, and the 2H method described below.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity Suppresses foaming of molten thermoplastic resin,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [5-4] in FIG. 5 or case [6-4] in FIG. 6). Such a configuration is referred to as a second method for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E) and the step (F), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
It can be configured (see case [4-5] in FIG. 4). Such a configuration is referred to as a second E method for convenience.

In step (G) and step (H) of the second method _E , the state of P _R <PE can be achieved by executing [foaming method (2) during injection or until completion]. Here, in the step (G), the state of P _R <P _E is set, but at the start of the step (G), the state of P _R <P _E may be set, or immediately after the start of the step (G). P _R > P _E , and then P _R <P _E. Moreover, in the state of P _R <P _E in the step (G) and the step (H), a portion where the state of P _R > P _E is included may be included. The above description can be similarly applied to the 2e method, 2F method, 2f method, 2G method, and 2H method described below.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and in the step (F), the state of P _R > P _E is set, whereby the melt thermoplasticity in the cavity is obtained. Suppresses foaming of resin,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
It can be configured (see case [5-5] in FIG. 5 or case [6-5] in FIG. 6). Such a configuration is referred to as a 2e method for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E) and the step (F), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [4-6] in FIG. 4). In addition, such a structure is called the 2nd F method for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and in the step (F), the state of P _R > P _E is set, whereby the melt thermoplasticity in the cavity is obtained. Suppresses foaming of resin,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
It can be configured (see case [5-6] in FIG. 5 or case [6-6] in FIG. 6). Such a configuration is referred to as a second f method for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
Wherein step (E), in the step (F) and step (G), and the state of P _R <P _E,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E By foaming the molten thermoplastic resin in the cavity by making the state of
(See case [4-7] in FIG. 4, case [5-7] in FIG. 5 or case [6-7] in FIG. 6). In addition, such a structure is called the 2G method for convenience. In the second G method, the state of P _R > P _E may be set simultaneously with the start of the step (I), or immediately after the start of the step (I), the state of P _R <P _E is set. it may be used as the state of the P _R> P _E.

State of P _R <P _E in the step (E) of the 2G method can be achieved by the execution of the foaming process in injection early stage. The state of P _R <P _E in the step (F) can be achieved by the execution of the foaming process to the exit in or complete (2)]. The step (E), step (F), <In the state of the P _E, P _R> P _R in the step (G) which may contain a portion in the state of P _E. The above description can be similarly applied to the second H method described below.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
Wherein step (E), in the step (F) and step (G), and the state of P _R <P _E,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E state and repeating the state of the P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure,
(See case [4-8] in FIG. 4, case [5-8] in FIG. 5 or case [6-8] in FIG. 6). Such a configuration is referred to as a 2H method for convenience. Even in the second H method, the state of P _R > P _E may be set simultaneously with the start of the step (I), or immediately after the start of the step (I), the state of P _R <P _E is set. it may be used as the state of the P _R> P _E.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
Thereafter, through the step (I), a state in which P _R <P _E and P _R > P _E are repeated, and a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product. obtain,
It can be configured (see case [4-9] in FIG. 4). Such a configuration is referred to as a second J method for convenience.

In the method of the 2J, in the preceding step (E) the state of the P _R> P _E, the subsequent step (E), in the step (F), step (G) and the step (I) is, P _R repeating the state of <state of P _E and P _R> P _E. Alternatively, in the method of the 2J, in the step (E) the state of the P _R> P _E, in the step (F), step (G) and the step (I), the state of P _R <P _E repeating the state of the P _R> P _E.

Here, the repetition of the state of P _R <P _{E and} the state of P _R > P _E in the latter stage of step (E) and in step (F) is performed by [pressure control / foaming suppression method] and [during injection or It can be achieved by carrying out the foaming method (2)] until completion. The above description can be similarly applied to the 2j method described below. Further, the repetition of the state of P _R <P _{E and} the state of P _R > P _E in the step (G) is performed by [pressure control / foaming suppression method] and [foaming method during injection or until completion (2). ] Can be achieved. The above description can be similarly applied to the 2j method, the 2K method, and the 2k method described below.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Thereafter, through the step (I), a state in which P _R <P _E and P _R > P _E are repeated, and a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product. obtain,
It can be configured (see case [5-9] in FIG. 5 or case [6-9] in FIG. 6). Such a configuration is referred to as a 2j method for convenience.

In the method 2j, the state of P _R <P _E is changed to the state of P _R > P _E before the step (E), and the step (F), step (G) and step after the step (E) are performed. In (I), the state of P _R <P _{E and} the state of P _R > P _E are repeated. Alternatively, in the method 2j, the state of P _R <P _E is changed to the state of P _R > P _{E in} the step (E), and in the step (F), the step (G) and the step (I), The state of P _R <P _{E and} the state of P _R > P _E are repeated.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E) and the step (F), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), from the state of P _R > P _E , the state of P _R <P _{E and} the state of P _R > P _E are repeated,
Furthermore, in the step (I), repeating the states of P _R <a P _E state and P _R> P _E, the depth direction of the foamed molded article unfoamed layer and foam layer are laminated obtain,
It can be configured (see case [4-10] in FIG. 4). Such a configuration is referred to as a 2K method for convenience.

Alternatively, in the injection foam molding method according to the second aspect of the present invention,
In the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and in the step (F), the state of P _R > P _E is set, whereby the thermoplastic resin in the cavity Suppresses foaming of
In the step (G), from the state of P _R > P _E , the state of P _R <P _{E and} the state of P _R > P _E are repeated,
Furthermore, in the step (I), repeating the states of P _R <a P _E state and P _R> P _E, the depth direction of the foamed molded article unfoamed layer and foam layer are laminated obtain,
It can be configured (see case [5-10] in FIG. 5 or case [6-10] in FIG. 6). Such a configuration is referred to as a 2k method for convenience.

  The characteristic parts of the methods 1A to 2k described above are summarized in Tables 1 and 2 below.

  The foam-molded article according to the first aspect of the present invention for achieving the above object is the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above. A foam molded article made of a thermoplastic resin molded by the method, wherein no bubbles are present up to a depth of at least 20 μm from the surface, preferably at a depth of at least 55 μm from the surface. Features.

  Alternatively, the foam-molded article according to the second aspect of the present invention for achieving the above object is an injection according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above. The thermoplastic resin foam molded article molded by the foam molding method satisfies the following formula (1), preferably the following formula (1 ′), more preferably the following formula (1 ″). It is characterized by.

0.001 × (1-ρ ₀ / ρ ₁ ) <V ₁ / V ₀ <1.2 × (1-ρ ₀ / ρ ₁ ) (1)
0.003 × (1-ρ ₀ / ρ ₁ ) <V ₁ / V ₀ <1.0 × (1-ρ ₀ / ρ ₁ ) (1 ′)
0.005 × (1−ρ ₀ / ρ ₁ ) <V ₁ / V ₀ <0.8 × (1−ρ ₀ / ρ ₁ ) (1 ″)

here,
V ₀ : Volume of foam molded product V ₁ : Total volume of bubbles existing in foam molded product ρ ₀ : Density of molten thermoplastic resin (density of molten thermoplastic resin before gas dissolution)
ρ ₁ : Density of the thermoplastic resin used (not the density of the foam molded product)
It is.

  In the foam-molded article according to the second aspect of the present invention, it is preferable that no bubbles are present up to a depth of at least 20 μm from the surface, desirably up to a depth of at least 55 μm from the surface. . In the foam-molded article according to the second aspect of the present invention including such a preferable form, or the foam-molded article according to the first aspect of the present invention, the size of the existing bubbles is 10 μm or less. Is desirable. That is, it is desirable that there is no foam layer on the surface of the foam molded article, and there is a foam portion at a depth of 20 μm from the surface or deeper than that.

  Examples of the foam molded article according to the first or second aspect of the present invention include foam molded articles such as a solid rod shape, a solid “T” shape, and a solid cross shape. “Solid” is a term that opposes “hollow”. The cross-sectional shape of the foam-molded product when the foam-molded product is cut in a direction substantially perpendicular to the flow axis direction of the molten thermoplastic resin can be any shape such as a circle, an ellipse, a rectangle, or a polygon. Specific examples of the foam-molded product include, but are not limited to, a paper feed roller, a paper discharge roller, a color reference roller, a step roller, a transport roller, and the like.

  In the injection foam molding method according to the first aspect or the second aspect of the present invention, the stopper is moved by the stopper moving means, by the molten thermoplastic resin injected into the cavity, or It is performed by both the plug body moving means and the molten thermoplastic resin injected into the cavity, and which form is determined depends on the injection conditions of the molten thermoplastic resin into the cavity, the operating conditions of the plug body moving means, etc. Depends on.

In the injection foam molding method according to the first aspect of the present invention including the various preferred forms described above, the injection amount V _i of the molten thermoplastic resin in the gas-dissolved state is equal to V _B. Meanwhile, it preferred In the injection foaming process according to the second aspect of the present invention including the above various forms, injection amount V _i of molten thermoplastic resin in the gas dissolving state, but are not limited to ,
0.8V _B ≦ V _i <V _B
Preferably,
0.85V _B ≦ V _i ≦ 0.93V _B
It is desirable to satisfy

  In the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above, the mold assembly further includes a fixed mold part constituting a cavity, and Temperature control means for controlling the respective temperatures of the cavity surfaces of the movable mold part, and by the temperature control means, the cavity surface of the fixed mold part during the period from the start to the completion of injection of the molten thermoplastic resin into the cavity, and The temperature of the cavity surface of the fixed mold part and the cavity surface of the movable mold part during cooling and solidification of the thermoplastic resin in the cavity is lower than the temperature of the cavity surface of the movable mold part. be able to. By setting it as such a structure, when suppressing that a molten thermoplastic resin foams during the injection | pouring of the molten thermoplastic resin in the cavity, it can suppress reliably that a molten thermoplastic resin foams. In addition, it is possible to ensure the execution of the [foaming method (4) during cooling and solidification]. Examples of the temperature control means include an electric heater and a heat medium (temperature-controlled oil or water).

In this case, the thermoplastic resin can be an amorphous thermoplastic resin. Further, in this case, the cavity surface of the fixed mold portion during the period from the start to the end of injection of the molten thermoplastic resin into the cavity. and the temperature of the cavity surface of the movable mold member, a temperature higher than the glass transition temperature T _g of the thermoplastic resin used; cavity surface and movable fixed mold part during the thermoplastic resin in the cavity is cooled and solidified the temperature of the cavity surface of the mold part may be configured to be less than the glass transition temperature T _g of the thermoplastic resin used. By adopting such a configuration, when the molten thermoplastic resin is prevented from foaming during the injection of the molten thermoplastic resin into the cavity, the molten thermoplastic resin can be more reliably suppressed from foaming. In addition, the execution of [Foaming method (4) during cooling / solidification] can be further ensured.

Alternatively, in this case, the thermoplastic resin can be a crystalline thermoplastic resin, and further, in this case, the cavity surface of the fixed mold portion during the period from the start to the completion of the injection of the molten thermoplastic resin into the cavity. The temperature of the cavity surface of the movable mold part is set to the melting point _Tm or more of the thermoplastic resin used; the cavity surface of the fixed mold part and the movable mold while the thermoplastic resin in the cavity is cooled and solidified The temperature of the cavity surface of the portion can be set to be equal to or lower than the crystallization start temperature T _c of the thermoplastic resin to be used. By adopting such a configuration, when the molten thermoplastic resin is prevented from foaming during the injection of the molten thermoplastic resin into the cavity, the molten thermoplastic resin can be more reliably suppressed from foaming. In addition, the execution of [Foaming method (4) during cooling / solidification] can be further ensured.

Alternatively, the thermoplastic resin may be a mixture composed of an amorphous thermoplastic resin and a crystalline thermoplastic resin. Here, whether or not the thermoplastic resin is an amorphous thermoplastic resin is generally determined by whether or not a clear melting point (a temperature indicating a rapid endotherm) is confirmed by a differential scanning calorimetry (DSC) method. Is done. A resin that does not have a clear melting point is an amorphous thermoplastic resin. On the other hand, a resin having a clear melting point is a crystalline thermoplastic resin. In the amorphous thermoplastic resin, solidifying and softening of the thermoplastic resin is produced by longitudinal glass transition temperature T _g. On the other hand, in a crystalline thermoplastic resin, it melts at a melting point _Tm or higher, and crystals are generated and developed at a crystallization start temperature _Tc or lower, resulting in solidification of the thermoplastic resin.

  Polycrystalline resins such as polyethylene resins and polypropylene resins as crystalline thermoplastic resins; Polyamide resins such as polyamide 6, polyamide 66 and polyamide MXD6; Polyoxymethylene (polyacetal, POM) resin; Polyethylene terephthalate (PET) resin, Poly Examples thereof include polyester resins such as butylene terephthalate (PBT) resin; polyphenylene sulfide resins.

  Amorphous thermoplastic resins include polystyrene resins, ABS resins, AES resins, AS resins such as styrene resins; methacrylic resins; polycarbonate resins (including linear polycarbonate resins and polycarbonate resins having branches in the main chain). A modified polyphenylene ether (PPE) resin; a polysulfone resin; a polyethersulfone resin; a polyarylate resin; a polyetherimide resin; a polyamideimide resin;

  Furthermore, a thermoplastic resin made of a polymer alloy material can be used. Here, the polymer alloy material is composed of a blend of at least two types of thermoplastic resins, or a block copolymer or graft copolymer in which at least two types of thermoplastic resins are chemically bonded. A polymer alloy material is widely used as a high-functional material that can have the unique performance of each of the individual thermoplastic resins. As a thermoplastic resin constituting a polymer alloy material in which at least two kinds of thermoplastic resins are blended, styrene resins such as polystyrene resin, ABS resin, AES resin, and AS resin; polyolefin resins such as polyethylene resin and polypropylene resin; methacrylic resin Polycarbonate resin; polyamide resin such as polyamide 6, polyamide 66, polyamide MXD6; modified PPE resin; polyester resin such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyoxymethylene resin; polysulfone resin; polyimide resin; Polyarylate resin; Polyether sulfone resin; Polyether ketone resin; Polyether ether ketone resin; Polyester carbonate resin Can. As a polymer alloy material obtained by blending two types of thermoplastic resins, a polymer alloy material of a polycarbonate resin and an ABS resin can be exemplified. Such a combination of resins is expressed as polycarbonate resin / ABS resin. The same applies to the following. Furthermore, as a polymer alloy material blended with at least two kinds of thermoplastic resins, polycarbonate resin / PET resin, polycarbonate resin / PBT resin, polycarbonate resin / polyamide resin, polycarbonate resin / PBT resin / PET resin, modified PPE resin / HIPS Examples thereof include resin, modified PPE resin / polyamide resin, modified PPE resin / PBT resin / PET resin, modified PPE resin / polyamide MXD6 resin, polyoxymethylene resin / polyurethane resin, and PBT resin / PET resin.

  In addition, an additive, a filler, and a reinforcing agent can also be added to the various thermoplastic resins described above.

  Additives: Plasticizers; Stabilizers; Antioxidants: Ultraviolet absorbers; Ultraviolet stabilizers such as organic nickel compounds such as nickel bis (octylphenyl) sulfide, hindered amine compounds; Antistatic agents; Flame retardants; Vinadin, Priben Antifungal agents such as Thor and Thiabendazole; Lubricants such as liquid paraffin, polyethylene wax and fatty acid amide; Organic foaming agents such as ADCA; Transparent coloring agents; Various colorants such as organic pigments and inorganic pigments; Crosslinking agents; Acrylic graft polymers, Mention may be made of impact resistance enhancers such as MBS.

  Plasticizers such as diethyl phthalate, di-n-butyl phthalate, 2-ethylhexyl phthalate, diisononyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate; triethyl phosphate, tributyl phosphate, phosphoric acid Phosphate esters such as tricresyl, triphenyl phosphate; fatty acid base esters such as butyl oleate, dibutyl adipate, adipic acid-n-hexyne, di-2-ethylhexyl adipate; alcohol esters such as diethylene glycol dibenzoate Oxyacid esters such as acetyltriethyl citrate and dibutyl maleate; trimellitic plasticizer; polyester plasticizer; epoxy plasticizer; chlorinated paraffinic plasticizer.

  As stabilizers, organotin stabilizers such as di-n-octyltin compounds, di-n-butyltin compounds, and dimethyltin compounds; lead compound systems such as tribasic lead sulfate, dibasic lead phosphite, and lead silicate Stabilizers; metal soap-based stabilizers such as cadmium soap, lead soap, zinc soap; trisnonyl phosphate; trisnonylphenyl phosphate;

  Antioxidants such as phenolic antioxidants such as dibutylcresol and butylhydroxyanisole; bisphenolic antioxidants such as methylenebis (methylbutylphenol) and thiobis (methylbutylphenol); tris (methylhydroxybutylphenyl) butane and tocophenol And polyphosphoric antioxidants; organic sulfur compounds such as dimyristylthiodipropionate; and organic phosphorus compounds such as tris (mono / dinonylphenyl) phosphite.

  As UV absorbers, salicylic acid UV absorbers such as phenyl salicylate and butylphenyl salicylate; benzophenone UV absorbers such as dihydroxybenzophenone; benzotriazole UV absorbers such as (hydroxymethylphenyl) benzotriazole; ethylhexylcyanodiacrylate Examples include cyanoacrylate-based ultraviolet absorbers such as phenonyl.

  Antistatic agents such as poly (oxyethylene) alkylamines, poly (oxyethylene) alkylphenyl ethers, and other nonionic surfactant antistatic agents; alkylsulfonates, alkylbenzenesulfonates, alkylphosphates, etc. Examples include ionic surfactant-based antistatic agents; cationic surfactant-based antistatic agents such as quaternary ammonium chloride; amphoteric surfactants; and conductive resins.

  As flame retardants, halogen flame retardants such as tetrabromobisphenol A, polybromobiphenol, bis (hydroxydibromophenyl) propane, chlorinated paraffin; phosphorus flame retardants such as ammonium phosphate and tricresyl phosphate; antimony trioxide; red phosphorus ; Tin oxide etc. can be mentioned.

  As fillers and reinforcing agents, inorganic materials: stainless steel fibers, high-strength amorphous metal fibers, stainless steel foils, steel foils, copper foils and other metal materials; high-molecular polyethylene fibers, high-strength polyarate fibers, para-type all Examples include organic materials such as aromatic polyamide fibers, aramid fibers, PEEK fibers, PEI fibers, PPS fibers, fluororesin fibers, phenol resin fibers, vinylon fibers, polyacetal fibers, and powder materials.

  As inorganic fillers and reinforcing agents, glass materials such as glass fibers, long glass fibers, and quartz glass fibers; carbon materials such as PAN carbon fibers, pitch carbon fibers, and graphite whiskers; silicon carbide fibers, silicon carbide Silicon carbide materials such as continuous fibers, silicon carbide whiskers, silicon carbide whisker sheets; boron materials such as boron fibers; Si—Ti—C—O materials such as Si—Ti—C—O fibers; potassium titanate fibers, titanium Examples thereof include potassium titanate materials such as potassium acid whisker and potassium titanate conductive whisker; silicon nitride materials such as silicon nitride whisker and silicon nitride whisker sheet; and calcium sulfate materials such as calcium sulfate whisker.

  As powder filler and reinforcing agent, mica flake, mica powder, shirasu balloon, silica fine powder, talc powder, aluminum hydroxide powder, magnesium hydroxide powder, magnesium silicate powder, calcium sulfate fine powder, spherical hollow glass powder, metallization Powder, high purity synthetic silica fine powder, tungsten disulfide powder, tungsten carbide powder, zirconia fine powder, zirconia fine powder, partially stabilized zirconia powder, alumina-zirconia composite powder, composite metal powder, iron powder, aluminum powder, molybdenum metal Examples thereof include powder, tungsten powder, aluminum nitride powder, nylon fine particle powder, silicone resin fine powder, spinel powder, amorphous alloy powder, aluminum flake, and glass flake.

In the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above, the cavity surfaces of the fixed mold part and the movable mold part are limited. without being, it is preferable that the thermal conductivity and a nested ^{13 (W · m -1 · K} -1) or less ^{(15Kcal · m -1 · hr -1} · deg -1). Further, the nesting is preferably made of a ceramic material, and broadly, ceramics selected from the group consisting of zirconia-based materials, partially stabilized zirconia, alumina-based materials, K ₂ O—TiO ₂ , or soda. It is desirable to make from a glass selected from the group consisting of glass, quartz glass, heat resistant glass and crystallized glass. More specifically, as specific materials constituting the nesting, ZrO ₂ , ZrO ₂ —CaO, ZrO ₂ —Y ₂ O ₃ , ZrO ₂ —MgO, ZrO ₂ —SiO ₂ , ZrO ₂ —CeO ₂ , K ₂ O—TiO ₂ , Al ₂ O ₃ , Al ₂ O ₃ —TiC, Ti ₃ N ₂ , 3Al ₂ O ₃ -2SiO ₂ , MgO—SiO ₂ , 2MgO—SiO ₂ , MgO—Al ₂ O ₃ —SiO ₂ And ceramics selected from the group consisting of titania or glass selected from the group consisting of quartz glass and crystallized glass, among which nesting is achieved from zirconia (ZrO ₂ ) including partially stabilized zirconia. It is preferable that it is produced. In addition, the partial stabilizer in partially stabilized zirconia includes calcia (calcium oxide, CaO), yttria (yttrium oxide, Y ₂ O ₃ ), magnesia (magnesium oxide, MgO), silica (silicon oxide, SiO ₂ ), and ceria. It is preferably made of at least one material selected from the group consisting of (cerium oxide, CeO ₂ ). The proportion of the partial stabilizer contained in zirconia is 3 to 15 mol%, preferably 6 to 10 mol%, preferably 1 to 8 mol% for yttria when the partial stabilizer is calcia. Mol%, preferably 2 to 5 mol%, magnesia 4 to 15 mol%, preferably 8 to 10 mol%, ceria 3 to 18 mol%, preferably 6 It is desirable to be from mol% to 12 mol%.

  When the cavity surfaces of the fixed mold part and the movable mold part are configured as described above, it is possible to prevent the molten thermoplastic resin from foaming during the injection of the molten thermoplastic resin into the cavity. It can suppress more reliably that a thermoplastic resin foams.

  In the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above, when the gas is dissolved in the molten thermoplastic resin in the step (B) The gas can be configured to be in a supercritical state or a subcritical state. In general, when the state of the system depends on a certain parameter and the state changes discontinuously above and below the certain value, the condition represented by that value is called criticality. The condition where the parameter value is below the critical value is called subcritical, and the condition above the parameter value is called supercritical. In this case, examples of the gas include carbon dioxide gas, nitrogen gas, or a mixed gas of carbon dioxide gas and nitrogen gas. In addition, the critical temperature (maximum temperature that can be vaporized) and the critical pressure (pressure at that time) of carbon dioxide gas and nitrogen gas are as shown in Table 3 below.

[Table 3]
Critical temperature Critical pressure Carbon dioxide gas 31.1 ° C 7.38 × 10 ⁶ Pa
Nitrogen gas -147 ° C 3.42 × 10 ⁶ Pa

In the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above, when the molten thermoplastic resin is measured in the step (B), the heat of fusion The pressure of the plastic resin is desirably high as long as the metering operation and gas dissolution are not hindered. Specifically, the pressure is preferably 5 × 10 ⁶ Pa or more. If it is less than 5 × 10 ⁶ Pa, the molten thermoplastic resin that is in a gas-dissolved state in the resin plasticizing / melting means foams, and the metering operation may be hindered. The pressure (back pressure) P ₁ applied to the molten thermoplastic resin injected into the cavity can be applied by a resin plasticizing / melting means.

  In the step (B), gas is dissolved in the molten thermoplastic resin, and the molten thermoplastic resin is measured. Specifically, after the gas is dissolved in the molten thermoplastic resin, the gas is in a gas-dissolved state. The molten thermoplastic resin may be weighed, or after the molten thermoplastic resin is weighed, the gas may be dissolved in the measured molten thermoplastic resin, or the gas is melted at a constant flow rate. You may measure, dissolving in a thermoplastic resin.

  In the step (B), the resin plasticizing / melting means is composed of an in-line screw type injection molding machine, plasticizing and melting the thermoplastic resin, dissolving gas in the molten thermoplastic resin, and The molten thermoplastic resin may be weighed. Alternatively, it is composed of a plunger type injection molding machine, the resin plasticizing / melting means is composed of a heating cylinder and a reservoir, the thermoplastic resin is plasticized / melted in advance in the heating cylinder, and the molten thermoplastic resin is stored in the reservoir. The gas may be dissolved in the molten thermoplastic resin in the reservoir, and the molten thermoplastic resin may be measured. Note that the amount of gas dissolved cannot be uniquely determined because it depends on the type of thermoplastic resin, the type of gas, the pressure, and the temperature.

  In the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above, the plug body moving means is made of a liquid such as hydraulic oil or a gas such as air. It can consist of the fluid cylinder used. However, the plug body moving means is not limited to this, and is composed of a fluid drive motor and an electric servo motor using a liquid such as hydraulic oil or a gas such as air, and directly moves (slides) the plug body. It is also possible to combine these fluid cylinders, fluid drive motors, electric servo motors, etc. with screw mechanisms such as ball screws, cam mechanisms, rack and pinion mechanisms, etc., or from various springs It can also be configured. In the case where the plug body moving means is constituted by the striations, the drag force of the plug body against the pressure of the injection molten thermoplastic resin increases as the striations shrink. Therefore, when a uniform drag is required, it is preferable that the stopper moving means is composed of a fluid cylinder, a rack and pinion mechanism, or the like. Further, in a mold assembly that does not include the plug body moving means, it is only necessary to generate a resistance against the pressure of the molten thermoplastic resin injected into the cavity due to its own weight.

  Usually, the flow direction of the molten thermoplastic resin injected from the molten resin injection part is the same flow direction in all the portions of the minute molten thermoplastic resin when the portion of the minute molten thermoplastic resin is observed. There is some variation in the flow direction. However, when observed as the whole molten thermoplastic resin, it can be said that the flow direction of the molten thermoplastic resin injected from the molten resin injection portion is a fixed direction. The plug body can be moved in the cavity substantially parallel to the flow axis direction of the molten thermoplastic resin injected from the molten resin injection portion by the operation of the plug moving means. The term “movable in the cavity” means to be able to move in the cavity in parallel with the flow direction of the molten thermoplastic resin injected from the molten resin injection portion when observed as the entire molten thermoplastic resin. Means.

The value of the drag force P ₂ of the plug against the pressure (back pressure) P ₁ to the molten thermoplastic resin injected into the cavity is the resin material used, the melt viscosity of the thermoplastic resin, the injection of the molten thermoplastic resin Since it depends on the pressure, the injection speed of the molten thermoplastic resin, etc., it cannot be determined uniquely. However, as explained above, when the [pressure control / foaming suppression method] is adopted,
P _R = P ₁ −P ₂ > P _E
And adopt [foaming method in the initial stage of injection (3)], [foaming method during or until injection (1)], and [foaming method during or until injection (2)]. In that case,
P _R = P ₁ −P ₂ <P _E
To be satisfied.

Since the plug is moved during the injection of the molten thermoplastic resin, it is necessary to control the movement of the plug so that a part of the plug surely forms a part of the cavity. For example, when a fluid cylinder is used, the movement speed of the plug can be easily controlled by controlling the operation of the fluid cylinder. The same applies when other mechanisms are used. However, in the injection foam molding method according to the first aspect or the second aspect of the present invention including the various preferred embodiments described above, in the step (D), the plug body is 5 × 10 ⁶ Pa. If the plug body is placed at the forward end by the plug body moving means so that the plug body starts moving from the forward end to the backward end when the above pressure is applied, Pressure control / foaming suppression method] can be achieved more reliably.

  It is desirable that the contact surface of the plug that contacts the molten thermoplastic resin has a smooth finish. When the surface roughness of the contact surface is rough, the contact surface of the plug body is difficult to release from the thermoplastic resin, and the smooth movement of the plug body is difficult, and a desired foamed molded product may not be obtained.

The shape of the plug may be determined as appropriate based on the characteristics of the thermoplastic resin used, the shape of the desired foamed molded product, and the like, and cannot be uniquely determined. The plug body may be any shape that can move within the cavity. From the viewpoint of preventing jetting and flow marks from occurring on the surface of the foam molded article, it is preferable that the cross-sectional shape perpendicular to the moving direction of the plug body is substantially similar to the cross-sectional shape of the cavity in this direction. The gap between the plug body surface and the cavity surface in the movement direction of the plug body is required to be a gap where the plug body does not contact the cavity surface when the plug body is moved. Although it is preferable that the molten thermoplastic resin does not enter the gap, in some cases, the molten thermoplastic resin may enter the gap. As an example, assuming that the outer diameter of the plug body is R ₁ and the inner diameter of the cavity portion where the plug body moves is R ₂ , 0.05 mm ≦ (R ₂ −R ₁ ) ≦ 0.6 mm, preferably 0 .05 mm ≦ (R ₂ −R ₁ ) ≦ 0.5 mm, more preferably 0.1 mm ≦ (R ₂ −R ₁ ) ≦ 0.4 mm is satisfied, but it is limited to these values. It is not a thing.

  In the injection foam molding method according to the first aspect or the second aspect of the present invention, the number of plugs may be one or two or more, and a plurality of plugs are provided. In this case, the timing at which each plug body starts to move (slide), the timing at which each plug body reaches the reverse end position, and the plug body moving speed may be the same or different. What is necessary is just to determine suitably depending on the characteristic, molding conditions, etc. of a thermoplastic resin.

  The fixed mold part, the movable mold part, and the plug can be made of a metal material such as carbon steel, stainless steel, aluminum alloy, or copper alloy. The structure of the molten resin injection part can be any known type of molten resin injection part (gate structure), for example, a direct gate structure, a side gate structure, a jump gate structure, a pinpoint gate structure, a tunnel gate. Examples include a structure, a ring gate structure, a fan gate structure, a disk gate structure, a flash gate structure, a tab gate structure, and a film gate structure. Examples of the structure of the molten resin flow path in the fixed mold part include a combination of a sprue and a cold runner, or a hot runner. That is, a sprue portion or a runner portion may be provided as a molten resin flow path in the fixed mold portion, and a molten resin injection portion may be disposed between the runner portion and the cavity. The molten thermoplastic resin may be directly injected into the cavity via a runner, a valve gate, or the like. In these cases, the hot runner, the valve gate, or the like is also included in the molten resin injection portion.

In the injection foam molding method according to the first aspect or the second aspect of the present invention, one or a plurality of foam molded products can be obtained. The amount of the molten thermoplastic resin injected into the cavity (the measured value V _i of the molten thermoplastic resin) may be an amount sufficient to produce a foam molded product. When the injection of the molten thermoplastic resin is completed, the amount of the molten thermoplastic resin remaining in the resin plasticizing / melting means (specifically, for example, at the end of the injection / holding process, for example, in the injection cylinder) It is desirable that the amount of cushion remains), but is not limited thereto. The measured value of the molten thermoplastic resin depends on the temperature and pressure at the time of plasticizing and melting the thermoplastic resin, but does not exceed the volume V _B of the cavity. In addition, when the pressure of the molten thermoplastic resin when measuring the molten thermoplastic resin in the gas dissolved state is higher than the pressure of the molten thermoplastic resin at the time of injection and the pressure during holding, the measured gas dissolved state Even when the volume V _i of the thermoplastic resin is less than the volume V _B of the cavity, it is possible to completely fill the cavity with the molten thermoplastic resin. Even in such a case, for example, by performing a [pressure control / foaming suppression method] as desired, foaming of the gas in the molten thermoplastic resin in the cavity is suppressed, or in the cavity. The gas foamed in the injected molten thermoplastic resin can be redissolved in the molten thermoplastic resin in the cavity.

Before the measured molten thermoplastic resin is injected into the cavity, the cavity may be filled with a pressurized fluid in advance. By adopting such a configuration, when a molten thermoplastic resin in a gas-dissolved state is injected into the cavity, the occurrence of a phenomenon such that the molten thermoplastic resin is in a reduced pressure state and foaming occurs in the cavity is ensured. Can be avoided. Here, examples of the pressurized fluid filling the cavity include carbon dioxide gas, nitrogen gas, or a mixed gas of carbon dioxide gas and nitrogen gas. Further, the pressure of the pressurized fluid filled in the cavity may be less than the injection pressure of the molten thermoplastic resin into the cavity. For example, the pressure of the pressure that can suppress the foaming of the gas in the molten thermoplastic resin in the cavity. The lower limit is desirably set, and more specifically, 1 × 10 ⁷ Pa or less is desirable. Since the cavity cannot be a completely sealed space, most of the pressurized fluid is discharged to the outside from the parting surface and the protruding portion when the molten thermoplastic resin in a gas-dissolved state is injected into the cavity. A part of the pressurized fluid dissolves in the molten thermoplastic resin injected into the cavity.

  In the injection foam molding method according to the first aspect or the second aspect of the present invention, even if the fixed mold part and the movable mold part are opened and the foamed molded product is taken out, the foamed local product is locally foamed. It is preferable to cool and solidify the thermoplastic resin in the cavity until no blistering occurs in the foamed molded product. The cooling time until this swelling does not occur is the mold temperature during injection, mold temperature during cooling (temperature of the cavity surface when the thermoplastic resin injected into the cavity is cooled in the cavity), heat It varies depending on the type and temperature of the plastic resin, the type of gas used, the thickness of the foamed molded product, and the desired weight reduction rate, and cannot be uniquely determined, but is preferably 5 seconds or more, more preferably 20 It is desirable to set it to 2 seconds or more.

  In the injection foam molding method according to the first aspect or the second aspect of the present invention, even if the molten thermoplastic resin foams in the cavity in any step, in the subsequent step, The gas foamed in the molten thermoplastic resin is redissolved once in the molten thermoplastic resin. That is, when molten thermoplastic resin in a gas-melted state is injected into the cavity and the molten thermoplastic resin foams in the cavity, by applying pressure to the molten thermoplastic resin in the cavity, Foaming of gas in the plastic resin is suppressed. Therefore, it is possible to reliably suppress the generation of foam cells (bubbles) on the surface of the foam molded product.

  Usually, in the step of cooling and solidifying the thermoplastic resin in the cavity, the cooling and solidification of the molten thermoplastic resin in the cavity starts from the portion of the molten thermoplastic resin near the cavity surface. And, if the cooling and solidification of the molten thermoplastic resin part is started before the foaming starts in the molten thermoplastic resin part, the injection foam molding according to the first aspect or the second aspect of the present invention. In the foam-molded product obtained by the method or the foam-molded product of the present invention, foam cells (bubbles) are not formed on the surface, and a foam-molded product having an excellent appearance can be obtained. In addition, local sink marks and warpage can be suppressed. Further, in a foam molded product having a thin part and a thick part, the foamed state is different between the thin part and the thick part. Therefore, it is possible to reliably prevent the occurrence of a phenomenon that the strength of the thin portion is reduced. The pressure drop due to cooling and solidification of the thermoplastic resin in the cavity is significant in the thick part, and as a result, foaming occurs more in the thick part than in the thin part, so that the thick part is reliably reduced in weight. Can do.

  In the present invention, the plug body is held at its forward end by the plug body moving means before the molten thermoplastic resin is injected. By holding the plug body at the forward end in this way, the molten thermoplastic resin injected into the cavity hits the plug body and prevents the molten thermoplastic resin from going straight, resulting in the occurrence of jetting. Therefore, it is possible to obtain a foam-molded article having excellent appearance characteristics.

  In the conventional mold assembly, when the molten resin injection part is provided in the mold part corresponding to the upper part of the cavity, when the molten thermoplastic resin is injected into the cavity, the molten thermoplastic resin Jetting is likely to occur because of the influence of gravity. In the present invention, when the molten thermoplastic resin is injected into the cavity by using the plug body, the molten thermoplastic resin in the cavity is hardly affected by gravity, and the molten resin injection portion in the mold assembly Can be arranged at an arbitrary position, and the degree of freedom in designing the mold assembly can be made extremely high.

Moreover, when the molten thermoplastic resin is injected into the cavity, the volume of the cavity is smaller than the volume V _{B of the} cavity that is finally required to form the foamed molded product. Therefore, even if a thermoplastic resin having a high viscosity at the time of melting is used, in the injection foam molding method according to the first aspect or the second aspect of the present invention, the stopper is finally moved backward. By locating at the end, the cavity shape required for molding the foam molded product can be obtained, so that the desired foam molded product can be easily and reliably formed. Moreover, by moving the plug body, the flow of the molten thermoplastic resin in the cavity can be controlled by gradually increasing the volume of the cavity, so that it can be easily and reliably molded into a foam molded product. it can.

  When molding a foamed molded product having a branched structure with different diameters and cross-sectional shapes, by controlling the timing of the start and completion of the movement of the plug body and the movement speed of the plug body to form each of the branch portions, The filling balance of the molten thermoplastic resin filled in each part can be easily achieved. Therefore, the appearance quality of the obtained foamed molded product is also improved. And since it is possible to form a foam molded product having a complicated structure by integral molding, an increase in the manufacturing cost of the foam molded product can be suppressed, processes such as adhesion and welding can be omitted, and productivity can be reduced. Improvements can be made. In addition, by controlling the travel distance of the plug body, foam molded articles having various lengths can be obtained based on one mold assembly. There is also an advantage that no weld is generated.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

Example 1 relates to the injection foam molding method according to the first aspect of the present invention, and more specifically to the method 1A (see case [1-1] in FIG. 1). That is, during the injection of the molten thermoplastic resin, while the plug body is continuously moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, the melt into the cavity the injection completion of thermoplastic resin, and suppressing the foaming of molten thermoplastic resin in the cavity by the state of P _R> P _E, in the step of cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E state.

  Typical cross section of mold assembly 30 (in a state after the fixed mold part and the movable mold part are clamped) suitable for use in Example 1 or Examples 2 to 21 described later FIG. 7 and FIG. 8 show injections that are resin plasticizing / melting means for plasticizing / melting a thermoplastic resin suitable for use in Example 1 or Examples 2 to 21 described later. FIG. 9 shows a schematic diagram in which a part of the working cylinder 10 is cut away. FIG. 7 shows a state where the plug body is located at the backward end, and FIG. 8 shows a state where the plug body is located at the forward end.

  The injection molding apparatus in the embodiment includes an injection cylinder 10 that is a resin plasticizing / melting means for plasticizing / melting a thermoplastic resin, and a mold assembly 30. The screw 12 disposed in the injection cylinder 10 is not limited, but is an in-line screw type in which the thermoplastic resin is plasticized and melted and also has a plunger action. Specifically, the injection cylinder 10 includes a heating cylinder 11 and a screw 12. The screw 12 is rotated by a hydraulic motor 15 via a reduction gear 14. The heating cylinder 11 is provided with a gas introduction unit 20, and gas can be introduced into the heating cylinder 11 from a gas source (not shown) through a pipe (not shown) and the gas introduction unit 20. In FIG. 9, reference numeral 16 is a hopper, reference numeral 17 is an injection ram, reference numeral 18 is an injection hydraulic cylinder, reference numeral 19 is an injection device forward / backward cylinder, reference numerals 19A and 19B are hydraulic piping, reference numeral 19C is a pressure gauge.

As shown in FIGS. 7 and 8, the mold assembly 30 includes a fixed mold part 31 and a movable mold part 32 made of steel, and the fixed mold part 31 and the movable mold part 32 are molded. A cavity 35 formed by fastening, a molten resin injection part 34 opened to the cavity 35, and a molten resin flow path connecting the molten resin injection part 34 and the injection cylinder 10 which is a resin plasticizing / melting means 33. Specifically, the molten resin injection part 34 has a side gate structure. Moreover, the molten resin flow path 33 is specifically composed of a combination of a sprue and a cold runner. The fixed mold part 31 is attached to a fixed mold part mounting plate (fixed platen) (not shown) provided in the injection molding apparatus. On the other hand, the movable mold part 32 is attached to a movable mold part mounting plate (movable platen) (not shown) provided in the injection molding apparatus. The movable mold part mounting plate (movable platen) can be translated on a tie bar (not shown) by operation of a hydraulic piston (not shown) in a clamping cylinder (not shown). The fixed mold part 31 and the movable mold part 32 are clamped (see FIGS. 7 and 8) or opened by the operation of the hydraulic piston. The shape of the cavity 35 was set to a shape capable of forming a cylindrical foam molded product having a diameter of 10 mm and a length of 200 mm. Further, at least a part of the cavity surfaces of the fixed mold part 31 and the movable mold part 32 constituting the cavity 35 [almost all in the embodiment] has a thermal conductivity of 13 (W · m ⁻¹ · K). ^-1 ) The following nesting 36, specifically a ceramic material, more specifically nesting 36 made of zirconia (thermal conductivity: 4.2 W · m ⁻¹ · K ⁻¹ ) is disposed. .

  The mold assembly includes at least one plug body 41 disposed in the cavity 35 and movable in a direction substantially parallel to the flow axis direction of the molten thermoplastic resin, and a plug body for moving the plug body 41. Moving means 42 is provided. The plug body 41 can move in the cavity 35 substantially in parallel with the flow axis direction of the molten thermoplastic resin injected from the molten resin injection portion 34 by the operation of the plug moving means 42. The plug body 41 has a cylindrical shape with a diameter of 9.9 mm and a length of 20 mm, and is made of a steel material. The contact surface 41A (see FIG. 7) of the plug body 41 with the molten thermoplastic resin is subjected to a mirror finish with a center line average roughness of 0.1S or less after hard chrome plating. The plug body 41 at the forward end is located close to the molten resin injection portion 34 and opposed to the molten resin injection portion 34. The plug body 41 and the plug body moving means 42 are connected by a connecting rod 43 that is movable by the operation of the plug body moving means 42. The plug moving means 42 is composed of, for example, a fluid cylinder that is operated by a hydraulic pressure having a piston diameter φ of 30 mm. The illustration of various devices for controlling the operation of the plug moving means 42 is omitted. The moving distance of the plug body 41 is 200 mm.

Hereinafter, although the foam molding method of Example 1 is demonstrated, Nippon Steel, Ltd. J85-EL-III-MuCel was used as an injection molding apparatus. Further, as the thermoplastic resin, a polycarbonate resin (trade name: Iupilon S2000 black) which is an amorphous thermoplastic resin manufactured by Mitsubishi Engineering Plastics Co., Ltd. was used. The polycarbonate resin has a glass transition temperature _Tg of 145 ° C. The molding conditions were as shown in Table 4 below. In Examples 2 to 21, J85-EL-III-MuCel manufactured by Nippon Steel Works, Ltd. was used as the injection molding apparatus. In Examples 3 to 21, Iupilon S2000 black was used as the thermoplastic resin.

[Table 4]
Resin temperature: 280 ° C
Gas used: Nitrogen gas dissolution condition: Approximate dissolution amount at 15 MPa for 2 seconds: About 0.1% by weight in the molten thermoplastic resin
Mold temperature during injection: 80 ° C (on the cavity surface)
Injection rate: 40 cm ³ / sec Injection time: 0.4 sec Resin metering back pressure: 2 MPa
Pressure P _{R, MIN} : 7MPa
Pressure PR _{, MAX} : 9MPa
Pressure P _E : 3.4 MPa
Pressure (back pressure) P ₁ : 9 MPa
Pressure (drag) P ₂ : 7 MPa
Pressure P ₃ : 2.5 MPa
Holding time: 20 seconds Pressure (drag) P ₄ : 2.5 MPa
Mold temperature during cooling: 80 ° C
Cooling / solidification time: 120 seconds

  Hereinafter, the injection foam molding method of Example 1 will be described with reference to FIGS. 8 and 10 to 12 which are schematic cross-sectional views of the mold assembly. 10 to 12, illustration of the resin plasticizing / melting means is omitted.

[Step-100]
First, step (A) in the injection foam molding method according to the first aspect of the present invention is executed. That is, the plug body 41 is positioned at the forward end in the cavity 35 by the plug body moving means 42 before the injection of the molten thermoplastic resin into the cavity is started (see FIG. 8). Specifically, the plug body 41 is moved by the plug body moving means 42 so that the value of the volume V _F of the cavity 35 is substantially 0 (more specifically, for example, 0 ≦ V _F ≦ 0.05 V _B ). Located in the cavity 35.

[Step-110]
And the process (B) in the injection foam molding method which concerns on the 1st aspect of this invention is performed. That is, the thermoplastic resin was plasticized / melted by the resin plasticizing / melting means, the gas was dissolved in the molten thermoplastic resin, and the molten thermoplastic resin was measured. In Example 1, after melt | dissolving gas in molten thermoplastic resin, the molten thermoplastic resin in a gas-dissolved state was measured. Specifically, the thermoplastic resin introduced between the heating cylinder 11 and the screw 12 from the hopper 16 is heated, plasticized, and melted by the heating cylinder 11 and the screw 12, and further introduced from the gas introduction unit 20. After the dissolved gas is dissolved in the molten thermoplastic resin in the heating cylinder 11, the molten thermoplastic resin in a gas-dissolved state is weighed, and the distal end portion (nozzle head portion 13) of the heating cylinder 11 and the distal end portion of the screw 12 are measured. In the gap 13A formed between the two. When the molten thermoplastic resin in a gas-dissolved state was weighed, the pressure of the molten thermoplastic resin (resin metering back pressure) was set to 5 × 10 ⁶ Pa or more. Further, when the gas is dissolved in the molten thermoplastic resin, the gas is in a supercritical state. Table 4 shows the resin temperature (temperature of the plasticized / molten resin), gas dissolution conditions, approximate gas dissolution amount, and resin metering back pressure.

[Step-120]
Next, step (C) in the injection foam molding method according to the first aspect of the present invention is executed. That is, in the cavity 35 formed by clamping the fixed mold part 31 and the movable mold part 32 from the resin plasticizing / melting means via the molten resin flow path 33 and the molten resin injection part 34. Then, the measured molten thermoplastic resin 50 was injected (see FIG. 10). Specifically, an injection ram 17 is attached to the rear end of the screw 12 constituting the injection cylinder 10 which is a resin plasticizing / melting means, and pressure is applied to the injection ram 17 by an injection hydraulic cylinder 18. It is done. By applying pressure to the injection ram 17 by the hydraulic cylinder 18 for injection, the screw 12 is pushed forward, and pressure is applied to the molten thermoplastic resin. As a result, the molten thermoplastic resin in the gas dissolved state stored in the gap 13A is Then, it is extruded from the nozzle head portion 13 at a high speed, and injected from the molten resin injection portion 34 to the cavity 35 via the molten resin flow path 33. The mold temperature, injection rate, and injection time during injection were as shown in Table 4. The injection amount (V _i ) of the molten thermoplastic resin in the gas-dissolved state was set to an amount sufficient to completely fill the cavity 35 with the unexpanded (in the gas-dissolved) molten thermoplastic resin. That is, V _i = V _B. Further, even when the injection is completed, the amount of molten thermoplastic resin remaining in the gap 13A as a cushion amount is slightly left.

[Step-130]
And the process (D) in the injection foam molding method which concerns on the 1st aspect of this invention is performed. That is, simultaneously with the start of injection of the molten thermoplastic resin 50 into the cavity 35, the movement of the plug body 41 from the forward end to the reverse end is started. A pressure (drag) P _{2 of} 7 MPa is exerted on the plug body 41 by the plug body moving means 42. On the other hand, the pressure (back pressure) P ₁ exerted on the molten thermoplastic resin in the cavity 35 by the resin plasticizing / melting means is 9 MPa. Therefore, the movement of the plug body 41 from the forward end to the reverse end is started by the plug body moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. Here, when the injection of the molten thermoplastic resin 50 into the cavity 35 is started, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 does not drop rapidly, so that the injection into the cavity 35 is started. Therefore, foaming of the molten thermoplastic resin 50 in the cavity 35 can be reliably suppressed thereafter. Furthermore, during the movement of the plug 41, the [pressure control / foaming suppression method] is executed. That is, the condition P _R > P _E (see Table 4) is satisfied. Thereby, foaming of the molten thermoplastic resin 50 in the cavity 35 can be suppressed.

[Step-140]
Furthermore, the step (E) in the injection foam molding method according to the first aspect of the present invention is executed. That is, this state is continued. In other words, during the injection of the molten thermoplastic resin 50 into the cavity 35, the plug body 41 is continuously moved toward the backward end by the plug body moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35 (FIG. 11). Thus, by setting P _R > P _E (see Table 4), foaming of the molten thermoplastic resin 50 in the cavity 35 can be suppressed.

[Step-150]
Next, step (F) in the injection foam molding method according to the first aspect of the present invention is executed. That is, after 0.4 seconds have elapsed from the start of injection of the molten thermoplastic resin 50 into the cavity 35, the injection of the molten thermoplastic resin 50 is completed, and is also injected into the plug moving means 42 and the cavity 35. The plug body 41 was positioned at the backward end by the molten thermoplastic resin 50 (see FIG. 12). Even at this time, the condition P _R > P _E (see Table 4) is satisfied. Thereby, foaming of the molten thermoplastic resin 50 in the cavity 35 can be suppressed.

[Step-160]
Thereafter, step (G) in the injection foam molding method according to the first aspect of the present invention is executed. That is, the thermoplastic resin in the cavity 35 was cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 was completed. During cooling, the mold temperature was maintained at the mold temperature during cooling shown in Table 4. In this step, by the state of P _R <P _E, it was foamed molten thermoplastic resin in the cavity 35. Specifically, [Foaming method during cooling / solidification (1)] and [Foaming method during cooling / solidification (2)] were performed. That is, simultaneously with the completion of the injection of the molten thermoplastic resin 50 into the cavity 35, the pressure P ₃ (see Table 4) exerted on the thermoplastic resin in the cavity by the resin plasticizing / melting means is reduced, and the plug is moved. The pressure (drag) P ₄ (see Table 4) exerted on the plug body 41 by the means 42 was decreased.

[Step-170]
Thereafter, step (H) in the injection foam molding method according to the first aspect of the present invention is executed. That is, the fixed mold part 31 and the movable mold part 32 were opened, and the foam molded product was taken out.

  On the surface of the obtained foamed molded article having a columnar shape, no defects, foam marks or sink marks due to jetting were observed, and the surface had an excellent appearance. The same applies to Example 2, Example 3, Example 5, Example 7, Example 10, Example 11, Example 12, Example 14, Example 16, and Example 18 described below. The result was obtained.

When the volume of the foam molded product is V ₀ , the total volume of bubbles present in the foam molded product is V ₁ , the density of the molten thermoplastic resin is ρ ₀ , and the density of the thermoplastic resin used is ρ ₁ , V ₀ , V ₁ , ρ ₀ , ρ ₁ are as shown in Table 5 below, and these values satisfied Expression (1). Moreover, when the obtained foamed molded product was cut and cross-sectional observation was performed and the foamed state was examined, a location at least 20 μm deep from the surface of the foamed molded product (specifically, the average from the surface of the foamed molded product) Thus, it was confirmed that no bubbles were present up to a depth of 55 μm.

[Table 5]
V ₁ / V _0: 0.003
ρ ₀ : 1.34 g / cm ³
ρ ₁ : 1.43 g / cm ³

  As Comparative Example 1, as shown in FIG. 7, a foamed molded product was molded in the same manner as in Example 1 except that the plug body 41 was disposed at the backward end. As a result, defects due to jetting and foam marks were generated on the surface of the obtained foamed molded product.

The second embodiment is a modification of the first embodiment. In Example 1, a polycarbonate resin, which is an amorphous thermoplastic resin, was used as the thermoplastic resin. On the other hand, in Example 2, a polyacetal resin (manufactured by Mitsubishi Engineering Plastics Co., Ltd., Iupital F20-03), which is a crystalline thermoplastic resin, was used as the thermoplastic resin. The crystalline thermoplastic resin has a melting point _Tm of 165 ° C.

  Except for this point, the injection foam molding method in the second embodiment can be the same as the injection foam molding method in the first embodiment. The injection molding apparatus used in the second embodiment is the same as the injection molding used in the first embodiment. Since it can be the same as that of the apparatus, a detailed description thereof will be omitted. The molding conditions in Example 2 are shown in Table 6.

[Table 6]
Resin temperature: 190 ° C
Use gas: Nitrogen gas dissolution condition: Approximate dissolution amount at 10 MPa for 10 seconds: About 5% by weight in the molten thermoplastic resin
Mold temperature during injection: 60 ° C (on the cavity surface)
Injection rate: 40 cm ³ / sec Injection time: 0.4 sec Resin metering back pressure: 1 MPa
Pressure P _{R, MIN} : 7MPa
Pressure PR _{, MAX} : 9MPa
Pressure P _E : 3.4 MPa
Pressure (back pressure) P ₁ : 9 MPa
Pressure (drag) P ₂ : 7 MPa
Pressure P ₃ : 2.5 MPa
Holding time: 10 seconds Pressure (drag) P ₄ : 2.5 MPa
Mold temperature during cooling: 60 ° C
Cooling / solidification time: 120 seconds

  As Comparative Example 2, as shown in FIG. 7, a foamed molded product was molded in the same manner as in Example 2 except that the plug body 41 was disposed at the reverse end in advance. As a result, defects due to jetting and foam marks were generated on the surface of the obtained foamed molded product.

The third embodiment is also a modification of the first embodiment and relates to the method 1a (see the case [2-1] in FIG. 2 and the case [3-1] in FIG. 3). That is, in the third embodiment, in a step similar to [Step-140] of Example 1, by <from the state of P _E P _R> P _R state of P _E, the molten thermoplastic resin in the cavity Suppresses foaming. Hereinafter, the method 1a in the case [2-1] of FIG. 2 of Example 3 will be described based on [Step-300A] to [Step-330A], and then [Step-300B] to [Step-320B]. The method 1a in case [3-1] of FIG. 3 will be described based on FIG.

[Step-300A]
First, in Example 3, the [foaming method (1) in the initial stage of injection] is executed in the same process as [Step-100] in Example 1. That is, the plug body 41 is positioned in the cavity 35 by the plug body moving means 42 so that the value of the volume V _F of the cavity 35 is 0 <V _F <V _B (for example, V _F = 0.8 V _B ). Keep it.

[Step-310A]
And the process similar to [process-110]-[process-120] of Example 1 is performed.

[Step-320A]
Next, the [foaming method (1) in the initial injection stage] is executed. That is, the injection of the molten thermoplastic resin 50 into the cavity 35 having the volume V _F (= 0.8 V _B ) is started in the same manner as in [Step-130] of the first embodiment. When the injection of the molten thermoplastic resin 50 into the cavity 35 starts, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 suddenly decreases, and as a result, the injection of the molten thermoplastic resin 50 into the cavity 35 starts. In the initial stage of injection, the molten thermoplastic resin 50 in the cavity 35 is foamed. After the molten thermoplastic resin fills the cavity 35 having a volume of V _F (= 0.8 V _B ), the movement of the plug body 41 from the forward end toward the reverse end starts. That is, the plug body 41 is subjected to a pressure (drag) P _{2 of} 7 MPa by the plug body moving means 42. At this time, the pressure (back pressure) P ₁ exerted on the molten thermoplastic resin in the cavity 35 by the resin plasticizing / melting means is 9 MPa. Therefore, the plug body 41 starts to move from the forward end to the reverse end by the plug moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. Then, during the movement of the plug body 41, the [pressure control / foaming suppression method] is executed. That is, the condition P _R > P _E (see Table 4) is satisfied. As a result, the gas is re-dissolved in the molten thermoplastic resin 50 in the cavity 35, and subsequent foaming in the molten thermoplastic resin 50 can be suppressed.

[Step-330A]
And the process similar to [process-140]-[process-170] of Example 1 is performed continuously.

[Step-300B]
First, the same steps as [Step-100] to [Step-120] of Example 1 are performed.

[Step-310B]
Then, the [foaming method (2) in the initial injection stage] is executed. That is, the injection of the molten thermoplastic resin 50 into the cavity 35 is started in the same manner as in [Step-130] of the first embodiment. However, unlike [Step-130] of the first embodiment, the plug body 41 is moved by the plug body moving means 42 from the forward end to the reverse end before the injection of the molten thermoplastic resin 50 into the cavity 35 starts. Let it begin. The volume V ′ _F of the cavity 35 at the start of injection of the molten thermoplastic resin 50 into the cavity 35 may be set to 0.8 V _B , for example. As a result, when the injection of the molten thermoplastic resin 50 into the cavity 35 is started, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 rapidly decreases, so that the molten thermoplastic resin 50 into the cavity 35 is reduced. The molten thermoplastic resin 50 in the cavity 35 is foamed from the start of injection to the initial stage of injection.

After the cavity 35 formed by the contact surface 41A of the moving plug body 41 with the molten thermoplastic resin and the cavity surfaces of the fixed mold part 31 and the movable mold part 32 is filled with the molten thermoplastic resin. In addition, the movement of the plug body 41 from the forward end toward the reverse end continues. That is, the plug body 41 is subjected to a pressure (drag) P _{2 of} 7 MPa by the plug body moving means 42. At this time, the pressure (back pressure) P ₁ exerted on the molten thermoplastic resin in the cavity 35 by the resin plasticizing / melting means is 9 MPa. Therefore, the movement of the plug 41 from the forward end to the reverse end is continued by the plug moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. While the stopper 41 is moving, the [pressure control / foaming suppression method] is executed. That is, the condition P _R > P _E (see Table 4) is satisfied. As a result, the gas is re-dissolved in the molten thermoplastic resin 50 in the cavity 35, and subsequent foaming in the molten thermoplastic resin 50 can be suppressed.

[Step-320B]
And the process similar to [process-140]-[process-170] of Example 1 is performed continuously.

  The fourth embodiment is also a modification of the first embodiment, and includes the method 1B (see case [1-2] in FIG. 1) and the method 1b (in case [2-2] in FIG. 2 and FIG. 3). Case [3-2]).

That is, during injection of the molten thermoplastic resin, while the plug body 41 continues to be moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R > P _E In the process of suppressing foaming of the molten thermoplastic resin in the cavity and cooling and solidifying the thermoplastic resin in the cavity, instead of setting P _R <P _E , P _R > P _E state and repeating the state of the P _R <P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure (method of the 1B).

Alternatively, during the injection of the molten thermoplastic resin, while the plug body 41 continues to be moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P by the state of the _E state of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, in the step of cooling and solidifying the thermoplastic resin in the cavity, the state of P _R <P _E Instead, the state of P _R > P _{E and} the state of P _R <P _E are repeated to obtain a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product (first b). Method).

  Hereinafter, first, the method 1B will be described based on [Step-400A] to [Step-420A], and then, the method 1b will be described based on [Step-400B] to [Step-410B].

[Step-400A]
First, steps similar to [Step-100] to [Step-120] in Example 1 are executed, and further, in steps similar to [Step-130] to [Step-150] in Example 1, P _By setting _R > P _E (see Table 4), foaming of the molten thermoplastic resin in the cavity is suppressed.

[Step-410A]
Then, as in [Step-160] of Example 1, the thermoplastic resin in the cavity 35 is cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. However, <unlike [Step-160] of Example 1, the state of the P _E, in this step, P _R> P _R repeating the states of the state of the P _E and P _R <P _E, foam molded article A structure in which an unfoamed layer and a foamed layer are laminated in the depth direction is obtained.

  Specifically, [Method of inhibiting foaming during cooling / solidification (1)] and [Method of inhibiting foaming during cooling / solidification (2)], [Method of foaming during cooling / solidification (1)] and [Cooling / solidification] The combination with the foaming method (2) during solidification is executed.

That is, from the completion of injection into the cavity 35 of the molten thermoplastic resin 50, 5 seconds, the state of P _R> P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are values shown in Table 7. Then, the next 5 seconds, the state of P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are values shown in Table 8. Furthermore, this operation is repeated 6 times. Thereafter, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure exerted by the plug body moving means 42 on the plug body 41 until 120 seconds elapse after the completion of the injection of the molten thermoplastic resin 50 into the cavity 35 ( Drag) P ₄ is a value shown in Table 8.

[Table 7]
Pressure P ₃ : 10 MPa
Pressure (drag) P ₄ : 10 MPa

[Table 8]
Pressure P ₃ : 1 MPa
Pressure (drag) P ₄ : 1 MPa

[Step-420A]
Next, the same step as [Step-170] in Example 1 is performed.

[Step-400B]
First, the same steps as [Step-300A] to [Step-320A] of Example 3 are executed, and further, the same steps as [Step-140] to [Step-150] of Example 1 are executed.

  Alternatively, first, the same steps as [Step-300B] to [Step-310B] of Example 3 are executed, and further, the same steps as [Step-140] to [Step-150] of Example 1 are performed. Execute.

[Step-410B]
Next, in a step similar to [Step-160] in Example 1, the same step as [Step-410A] is performed, and then the same step as [Step-170] in Example 1 is performed.

  On the surface of the obtained foamed molded article having a columnar shape, no defects, foam marks or sink marks due to jetting were observed, and the surface had an excellent appearance. When the foamed molded product was cut along a plane perpendicular to the axial direction and the cut surface was observed, an unfoamed layer (average thickness 0.5 mm) and a foamed layer (average thickness 0. 5 mm) were observed in the depth direction of the foamed molded product. 5 mm), 5 layers each of which was able to obtain a laminated annual ring-like structure. In addition, it was confirmed that no bubbles existed at a depth of at least 20 μm from the surface of the foam molded product (specifically, a depth of 55 μm on average from the surface of the foam molded product). . In addition, the same results are obtained in Example 6, Example 8, Example 9, Example 13, Example 15, Example 17, Example 19, Example 20, Example 20, and Example 21 described below. I was able to.

When the volume of the foam molded product is V ₀ , the total volume of bubbles present in the foam molded product is V ₁ , the density of the molten thermoplastic resin is ρ ₀ , and the density of the thermoplastic resin used is ρ ₁ , V ₀ , V ₁ , ρ ₀ , ρ ₁ are as shown in Table 9 below, and these values satisfied Expression (1).

[Table 9]
V ₁ / V _0: 0.003
ρ ₀ : 1.34 g / cm ³
ρ ₁ : 1.43 g / cm ³

  The fifth embodiment is also a modification of the first embodiment. The method 1C (see case [1-3] in FIG. 1) and the method 1c (case [2-3] in FIG. 2 and FIG. 3) Case [3-3]).

That is, while continuing to move towards the backward end of the plug body by a molten thermoplastic injection in resin injected molten thermoplastic resin to the plug body moving means and / or cavity, the state of P _R> P _E In the process of suppressing the foaming of the molten thermoplastic resin in the cavity and cooling and solidifying the thermoplastic resin in the cavity, instead of setting P _R <P _E , P _R > P _E It suppresses foaming of molten thermoplastic resin in the cavity by a state, then foaming the molten thermoplastic resin in the cavity by the state of P _R <P _E (method of the 1C).

Alternatively, during the injection of the molten thermoplastic resin, while the plug body continues to move toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P _E by the state and condition of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, in the step of cooling and solidifying the thermoplastic resin in the cavity, and the state of the P _R <P _E Instead, foaming of the molten thermoplastic resin in the cavity is suppressed by setting P _R > P _E , and then the molten thermoplastic resin in the cavity is foamed by setting P _R <P _E. (Method 1c).

  Hereinafter, first, the method 1C will be described based on [Step-500A] to [Step-520A], and then, the method 1c will be described based on [Step-500B] to [Step-510B].

[Step-500A]
First, steps similar to [Step-100] to [Step-120] in Example 1 are executed, and further, in steps similar to [Step-130] to [Step-150] in Example 1, P _By setting _R > P _E (see Table 4), foaming of the molten thermoplastic resin in the cavity is suppressed.

[Step-510A]
Then, as in [Step-160] of Example 1, the thermoplastic resin in the cavity 35 is cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. However, unlike [Step-160] in Example 1 in which P _R <P _E , the foamed thermoplastic resin in the cavity is prevented from foaming by setting P _R > P _E in this step. and, then, foaming the molten thermoplastic resin in the cavity by the state of P _R <P _E.

  Specifically, after executing [Method of suppressing foaming during cooling / solidification (1)] and [Method of suppressing foaming during cooling / solidification (2)], [Method of foaming during cooling / solidification] ([Cooling / solidification] 4 of foaming method during solidification (1), foaming method during cooling / solidification (2), foaming method during cooling / solidification (3), and foaming method during cooling / solidification (4). Any one of the foaming methods at the time of cooling and solidification may be adopted, or a combination of arbitrary plural methods may be adopted).

That is, from the completion of injection into the cavity 35 of the molten thermoplastic resin 50, 10 seconds, the state of P _R> P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to the values shown in Table 7. After that, the state of the P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 8. The pressure P ₃ exerted by the resin plasticizing / melting means and the pressure exerted by the plug moving means 42 on the plug 41 until 120 seconds elapse after completion of the injection of the molten thermoplastic resin 50 into the cavity 35 ( Drag) P ₄ is held at the value shown in Table 8.

[Step-520A]
Next, the same step as [Step-170] in Example 1 is performed.

[Step-500B]
First, the same steps as [Step-300A] to [Step-320A] of Example 3 are executed, and further, the same steps as [Step-140] to [Step-150] of Example 1 are executed. Alternatively, first, the same steps as [Step-300B] to [Step-310B] of Example 3 are executed, and further, the same steps as [Step-140] to [Step-150] of Example 1 are performed. Execute.

[Step-510B]
Next, in a step similar to [Step-160] in Example 1, the same step as [Step-510A] is performed, and then the same step as [Step-170] in Example 1 is performed.

  The sixth embodiment is also a modification of the first embodiment. The first method (see case [1-4] in FIG. 1) and the first method (case [2-4] in FIG. 2 and FIG. 3) are used. Case [3-4]).

That is, while continuing to move towards the backward end of the plug body by a molten thermoplastic injection in resin injected molten thermoplastic resin to the plug body moving means and / or cavity, the state of P _R> P _E Thus, in the process of suppressing the foaming of the molten thermoplastic resin in the cavity and cooling and solidifying the thermoplastic resin in the cavity, instead of setting P _R <P _E , P _R > P _E By suppressing the foaming of the molten thermoplastic resin in the cavity, the state of P _R <P _{E and} the state of P _R > P _E are repeated, and the unfoamed layer is formed in the depth direction of the foam molded product. And a foamed layer are obtained (1D method).

Alternatively, during the injection of the molten thermoplastic resin, while the plug body is continuously moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P _E by the state and condition of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, in the step of cooling and solidifying the thermoplastic resin in the cavity, and the state of the P _R <P _E instead of, inhibiting the foaming of molten thermoplastic resin in the cavity by the state of P _R> P _E, then repeating the state of the P _R <a P _E state and P _R> P _E, foam A structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the molded product is obtained (method 1d).

  Hereinafter, first, the 1D method will be described based on [Step-600A] to [Step-620A], and then, the 1d method will be described based on [Step-600B] to [Step-610B].

[Step-600A]
First, steps similar to [Step-100] to [Step-120] in Example 1 are executed, and further, in steps similar to [Step-130] to [Step-150] in Example 1, P _By setting _R > P _E (see Table 4), foaming of the molten thermoplastic resin in the cavity is suppressed.

[Step-610A]
Then, in the same manner as in [Step -510A] Example 5, P _R> by the state of P _E (specifically, the completion of injection into the cavity 35 of the molten thermoplastic resin 50, 5 sec The pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted on the plug 41 by the plug moving means 42 are set to the values shown in Table 7), and the molten thermoplastic resin in the cavity Suppresses foaming. Thereafter, in the same manner as in [Step-410A] in Example 4, the state of P _R <P _{E and} the state of P _R > P _E are repeated, and the unfoamed layer and the foamed layer are formed in the depth direction of the foam molded product. To obtain a laminated structure. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to the values shown in Table 8 for the next 5 seconds. The pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted on the plug body 41 by the plug body moving means 42 are the values shown in Table 7. Then, this operation is repeated five times. Thereafter, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure exerted by the plug body moving means 42 on the plug body 41 until 120 seconds elapse after the completion of the injection of the molten thermoplastic resin 50 into the cavity 35 ( Drag) P ₄ is a value shown in Table 8.

[Step-620A]
Next, the same step as [Step-170] in Example 1 is performed.

[Step-600B]
First, the same steps as [Step-300A] to [Step-320A] of Example 3 are executed, and further, the same steps as [Step-140] to [Step-150] of Example 1 are executed. Alternatively, first, the same steps as [Step-300B] to [Step-310B] of Example 3 are executed, and further, the same steps as [Step-140] to [Step-150] of Example 1 are performed. Execute.

[Step-610B]
Next, in the same step as [Step-160] in Example 1, after performing the same step as [Step-610A], the same step as [Step-170] in Example 1 is performed.

  Example 7 is also a modification of Example 1 and relates to the 1E method (see case [1-5] in FIG. 1, case [2-5] in FIG. 2 and case [3-5] in FIG. 3)). .

That is, while continuing to move towards the backward end of the plug body by a molten thermoplastic injection in resin injected molten thermoplastic resin to the plug body moving means and / or cavity, the state of P _R <P _E and then, to complete the injection of the molten thermoplastic resin, in addition, when allowed position stopper to the reverse end by the injected molten thermoplastic resin to the plug body moving means and / or cavity, the P _R> P _E Instead of setting the state, P _R <P _E is set, and in the process of cooling and solidifying the thermoplastic resin in the cavity, P _R > P _E is set instead of P _R <P _E. It suppresses foaming of molten thermoplastic resin in the cavity by, then foaming the molten thermoplastic resin in the cavity by the state of P _R <P _E.

In Example 7, immediately after the start of the process of cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E is set, and then P _R > P _E is set. or as the state of the P _R> P _E simultaneously start the process.

  Hereinafter, the 1E method will be described based on [Step-700] to [Step-730].

[Step-700]
First, the same steps as [Step-300A] to [Step-320A] of the third embodiment are performed. Alternatively, the same steps as [Step-300B] to [Step-310B] of the third embodiment are executed.

Alternatively, the [foaming method (3) in the initial injection stage] is executed. That is, the injection early stage of molten thermoplastic resin into the cavity 35, to the state of P _R <P _E, in a step similar to [Step-100] of Example 1, the volume of the cavity 35 The plug body 41 is positioned in the cavity 35 by the plug body moving means 42 so that the value of V _F becomes substantially zero. In the same step as [Step-130] of the first embodiment, the movement of the plug body 41 from the forward end to the reverse end is started simultaneously with the start of injection of the molten thermoplastic resin 50 into the cavity 35. If the [foaming method (3) in the initial stage of injection] is executed, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 is suddenly reduced. In the stage, the molten thermoplastic resin 50 in the cavity 35 is foamed. Specifically, the pressure P ₁ and the pressure P ₂ are values shown in Table 10.

[Table 10]
Pressure P ₁ : 3 MPa
Pressure (drag) P ₂ : 2 MPa

[Step-710]
Thereafter, in the same steps as [Step-140] and [Step-150] of Example 1, the execution of [Foaming method (2) during injection or until completion] is continued. That is, during the injection of the molten thermoplastic resin 50 into the cavity 35, the plug body 41 continues to move toward the backward end by the plug body moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. Thus, by holding the state of the P _R <P _E, it encourages foaming molten thermoplastic resin 50 in the cavity 35. Specifically, the pressure P ₁ and the pressure P ₂ are values shown in Table 10.

[Step-720]
Next, in the same step as [Step-160] in Example 1, P _R < _PE is maintained for 5 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 8. Then, 5 seconds, the state of P _R> P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to the values shown in Table 7. Then, the state of P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 8. And, furthermore, between the completion of injection into the cavity 35 of the molten thermoplastic resin 50 until the lapse of 120 seconds, to hold the state of the P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are maintained at the values shown in Table 8.

[Step-730]
Next, the same step as [Step-170] in Example 1 is performed.

  The eighth embodiment is also a modification of the first embodiment and relates to the first F method (see the case [1-6] in FIG. 1, the case [2-6] in FIG. 2 and the case [3-6] in FIG. 3)). .

That is, while continuing to move towards the backward end of the plug body 41 by the molten thermoplastic injection in resin injected molten thermoplastic resin to the plug body moving means and / or the cavity, P _R <the P _E P _R > P _E when the injection of the molten thermoplastic resin is completed and the plug is moved to the rear end by the plug moving means and / or the molten thermoplastic resin injected into the cavity. Instead of making the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed, and then the state of P _R <P _{E and} the state of P _R > P _E are changed. Repeatedly, a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product is obtained.

In Example 8, immediately after the start of the process of cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E , and then P _R > P _E , or as the state of the P _R> P _E simultaneously start the process.

  Hereinafter, the first F method will be described based on [Step-800] to [Step-820].

[Step-800]
First, the same steps as [Step-700] to [Step-710] of Example 7 are performed.

[Step-810]
Next, in the same step as [Step-160] in Example 1, P _R < _PE is maintained for 5 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 8. Then, 5 seconds, the state of P _R> P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to the values shown in Table 7. Then, this operation is repeated five times. Thereafter, during the period from completion of injection into the cavity 35 of the molten thermoplastic resin 50 until the lapse of 120 seconds, to hold the state of the P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 8.

[Step-820]
Next, the same step as [Step-170] in Example 1 is performed.

  The ninth embodiment is also a modification of the first embodiment. The first G method (see the case [1-7] in FIG. 1) and the first g method (the case [2-7] in FIG. 2 and FIG. 3) are used. Case [3-7]).

That is, while continuing to move towards the backward end of the plug body by a molten thermoplastic injection in resin injected molten thermoplastic resin to the plug body moving means and / or cavity, the state of P _R> P _E In the process of suppressing foaming of the molten thermoplastic resin in the cavity and then cooling and solidifying the thermoplastic resin in the cavity, the state of P _R <P _{E and} the state of P _R > P _E To obtain a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product (method 1G).

Alternatively, during the injection of the molten thermoplastic resin, while the plug body is continuously moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P _E After changing from the state of P _R > P _E to the process of cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E and P _R > P _E are repeated, and foam molding is performed. A structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the product is obtained (method 1g).

  Hereinafter, the 1G method will be described first based on [Step-900A] to [Step-930A], and then the 1g method will be described based on [Step-900B] to [Step-910B].

[Step-900A]
First, the same steps as [Step-100] to [Step-120] in Example 1 are executed. Further, in the same steps as [Step-130] to [Step-140] in Example 1, P _By setting _R > P _E (see Table 4), foaming of the molten thermoplastic resin in the cavity is suppressed. That is, the [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] are executed.

[Step-910A]
Next, in the same process as [Step-150] in Example 1 from the continuation of the same process as [Step-140] in Example 1, [Pressure control / foaming suppression method] and [During injection or completion] The foaming method (2)] (see Table 10 for conditions) is executed. As a result, the repetition of the state of P _R <P _{E and} the state of P _R > P _E can be achieved.

[Step-920A]
Thereafter, the same process as [Process-410A] in Example 4 is performed, so that the repetition of the state of P _R <P _{E and} the state of P _R > P _E can be obtained.

[Step-930A]
Next, the same step as [Step-170] in Example 1 is performed.

[Step-900B]
First, the same steps as [Step-300A] to [Step-320A] of the third embodiment are performed. Alternatively, first, steps similar to [Step-300B] to [Step-310B] of the third embodiment are executed. Further, in the same step as [Step-140] in Example 1, by setting P _R > P _E (see Table 4), foaming of the molten thermoplastic resin in the cavity is suppressed. That is, the [pressure control / foaming suppression method] is executed.

[Step-910B]
Then, [Step-910A] to [Step-930A] are executed.

Example 10 relates to the injection foam molding method according to the second aspect of the present invention, and more specifically to the method 2A (see case [4-1] in FIG. 4). That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. When the injection of the thermoplastic resin is completed, the plug body continues to move toward the reverse end by the plug moving means and / or the molten thermoplastic resin injected into the cavity, and the plug body moves to the reverse end. In the process of suppressing foaming of the molten thermoplastic resin in the cavity by setting the state of P _R > P _E at the time of positioning, the state of P _R <P _E in the process of cooling and solidifying the thermoplastic resin in the cavity And

Hereinafter, the foam molding method of Example 10 will be described. The molding conditions are as shown in Table 11 below. In the following description, the pressure P _{R_F} refers to pressure P _R of the molten thermoplastic resin in the cavity in the step (F) in the injection foam molding method according to the second aspect of the present invention, the pressure P _{R_h} is means the pressure P _R of the molten thermoplastic resin in the cavity in the step (H) in the injection foam molding method according to the second aspect of the present invention.

[Table 11]
Resin temperature: 280 ° C
Gas used: Nitrogen gas dissolution condition: Approximate dissolution amount at 15 MPa for 2 seconds: About 0.1% by weight in the molten thermoplastic resin
Mold temperature during injection: 80 ° C (on the cavity surface)
Injection rate: 40 cm ³ / sec Injection time: 0.4 sec Resin metering back pressure: 2 MPa
Pressure P _{R, MIN} : 7MPa
Pressure PR _{, MAX} : 9MPa
Pressure P _E : 3.4 MPa
Pressure (back pressure) P ₁ : 9 MPa
Pressure (drag) P ₂ : 7 MPa
Pressure P ₃ : 2.5 MPa
Holding time: 20 seconds Pressure (drag) P ₄ : 2.5 MPa
Mold temperature during cooling: 80 ° C
Cooling / solidification time: 120 seconds

  Hereinafter, the injection foam molding method of Example 10 will be described.

[Step-1000]
First, step (A) in the injection foam molding method according to the second aspect of the present invention is executed. Specifically, the same process as [Process-100] of Example 1 is performed.

[Step-1010]
And the process (B) in the injection foam molding method which concerns on the 2nd aspect of this invention is performed. Specifically, the same process as [Process-110] of Example 1 is performed. However, when the gas is dissolved in the molten thermoplastic resin, the gas is in a supercritical state. Table 11 shows the values of the resin temperature (the temperature of the plasticized and melted resin), the gas dissolution conditions, the approximate gas dissolution amount, and the resin metering back pressure.

[Step-1020]
Next, step (C) in the injection foam molding method according to the second aspect of the present invention is executed. Specifically, the same process as [Process-120] in Example 1 is performed. However, the mold temperature, injection rate, and injection time during injection were as shown in Table 11. Further, the injection amount (V _i ) of the molten thermoplastic resin in the gas-dissolved state is an amount that is insufficient to completely fill the cavity 35 with the unexpanded (gas-dissolved) molten thermoplastic resin. . Further, even when the injection is completed, the amount of molten thermoplastic resin remaining in the gap 13A as a cushion amount is slightly left.

[Step-1030]
And the process (D) in the injection foam molding method which concerns on the 2nd aspect of this invention is performed. Specifically, the same process as [Process-130] of Example 1 is performed. At this time, the condition P _R > P _E is satisfied.

[Step-1040]
Furthermore, the step (E) in the injection foam molding method according to the second aspect of the present invention is executed. That is, this state is continued. Specifically, the same step as [Step-140] of the first embodiment is performed. Even at this time, the condition P _R > P _E is satisfied.

[Step-1050]
Next, step (F) in the injection foam molding method according to the second aspect of the present invention is executed. That is, the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. Specifically, the injection of the molten thermoplastic resin was completed after 0.4 seconds from the start of injection of the molten thermoplastic resin 50 into the cavity 35. The injection amount V _i and the volume V _{B of the} cavity 35 have a relationship of V _i = V _B. Even at this time, the condition P _R (P _{R_F} )> P _E is satisfied.

[Step-1060]
Next, step (G) in the injection foam molding method according to the second aspect of the present invention is executed. That is, after that, the plug body 41 was further moved toward the backward end by the plug body moving means 42 and / or the molten thermoplastic resin 50 injected into the cavity 35. Even at this time, the condition P _R > P _E is satisfied.

[Step-1070]
Thereafter, step (H) in the injection foam molding method according to the second aspect of the present invention is executed. That is, the plug body 41 is positioned at the backward end by the molten body thermoplastic resin 50 injected into the plug body moving means 42 and / or the cavity 35. Specifically, after the elapse of 0.4 seconds from the start of injection of the molten thermoplastic resin 50 into the cavity 35, the plug body 41 is moved backward by the plug body moving means 42 and the molten thermoplastic resin 50 injected into the cavity. It was positioned at. Even at this time, the condition P _R (P _{R — H} )> P _E is satisfied. Thereby, foaming of the molten thermoplastic resin 50 in the cavity 35 can be suppressed.

[Step-1080]
Thereafter, step (I) in the injection foam molding method according to the second aspect of the present invention is executed. That is, the thermoplastic resin in the cavity 35 was cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 was completed. During cooling, the mold temperature was kept at the mold temperature during cooling shown in Table 11. In this step, by the state of P _R <P _E, it was foamed molten thermoplastic resin in the cavity 35. Specifically, [Foaming method during cooling / solidification (1)] and [Foaming method during cooling / solidification (2)] were performed. That is, simultaneously with the completion of the injection of the molten thermoplastic resin 50 into the cavity 35, the pressure P ₃ (see Table 11) exerted on the thermoplastic resin in the cavity by the resin plasticizing / melting means is reduced, and the plug is moved. The pressure (drag) P ₄ (see Table 11) exerted on the plug body 41 by the means 42 was decreased.

[Step-1090]
Thereafter, step (J) in the injection foam molding method according to the second aspect of the present invention is executed. That is, the fixed mold part 31 and the movable mold part 32 were opened, and the foam molded product was taken out.

When the volume of the foam molded product is V ₀ , the total volume of bubbles present in the foam molded product is V ₁ , the density of the molten thermoplastic resin is ρ ₀ , and the density of the thermoplastic resin used is ρ ₁ , V ₀ , V ₁ , ρ ₀ , ρ ₁ are as shown in Table 12 below, and these values satisfied Expression (1). Moreover, when the obtained foamed molded product was cut and cross-sectional observation was performed and the foamed state was examined, a location at least 20 μm deep from the surface of the foamed molded product (specifically, the average from the surface of the foamed molded product) Thus, it was confirmed that no bubbles were present up to a depth of 55 μm.

[Table 12]
V ₁ / V _0: 0.003
ρ ₀ : 1.34 g / cm ³
ρ ₁ : 1.43 g / cm ³

  The eleventh embodiment is a modification of the tenth embodiment. In Example 10, a polycarbonate resin, which is an amorphous thermoplastic resin, was used as the thermoplastic resin. On the other hand, in Example 11, the polyacetal resin which is the same crystalline thermoplastic resin as Example 2 was used as a thermoplastic resin.

  Except this point, the injection foam molding method in Example 11 can be the same as the injection foam molding method in Example 10, and the injection molding apparatus used in Example 11 is also the injection molding used in Example 10. Since it can be the same as that of the apparatus, a detailed description thereof will be omitted. The molding conditions in Example 11 are shown in Table 13.

[Table 13]
Resin temperature: 190 ° C
Use gas: Nitrogen gas dissolution condition: Approximate dissolution amount at 10 MPa for 10 seconds: About 5% by weight in the molten thermoplastic resin
Mold temperature during injection: 60 ° C (on the cavity surface)
Injection rate: 40 cm ³ / second Injection time: 0.4 seconds Resin metering back pressure: 1 MPa
Pressure P _{R, MIN} : 7MPa
Pressure PR _{, MAX} : 9MPa
Pressure P _E : 3.4 MPa
Pressure (back pressure) P ₁ : 9 MPa
Pressure (drag) P ₂ : 7 MPa
Pressure P ₃ : 2.5 MPa
Holding time: 10 seconds Pressure (drag) P ₄ : 2.5 MPa
Mold temperature during cooling: 60 ° C
Cooling / solidification time: 120 seconds

  The twelfth embodiment is also a modification of the tenth embodiment and relates to the method 2a (see the case [5-1] in FIG. 5 and the case [6-1] in FIG. 6).

That is, in Example 12, that is, while the molten thermoplastic resin is being injected, the plug body is continuously moved toward the backward end by the plug moving means and / or the molten thermoplastic resin injected into the cavity. Meanwhile, foaming of the molten thermoplastic resin in the cavity is suppressed by changing the state of P _R <P _{E to} the state of P _R > P _E. Hereinafter, the method 2a in the case [5-1] of FIG. 5 of Example 12 will be described based on [Step-1200A] to [Step-1230A], and then [Step-1200B] to [Step-1220B]. The method 2a in case [6-1] of FIG. 6 is demonstrated based on FIG.

[Step-1200A]
First, in Example 12, the [foaming method (1) in the initial stage of injection] is executed in the same process as [Process-1000] in Example 10. That is, the plug body 41 is positioned in the cavity 35 by the plug body moving means 42 so that the value of the volume V _F of the cavity 35 is 0 <V _F <V _B (for example, V _F = 0.8 V _B ). Keep it.

[Step-1210A]
And the process similar to [process-1010]-[process-1020] of Example 10 is performed.

[Step-1220A]
Next, the [foaming method (1) in the initial injection stage] is executed. That is, the injection of the molten thermoplastic resin 50 into the cavity 35 having a volume of V _F (= 0.8 V _B ) is started in the same manner as in [Step-1030] of Example 10. When the injection of the molten thermoplastic resin 50 into the cavity 35 starts, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 suddenly decreases, and as a result, the injection of the molten thermoplastic resin 50 into the cavity 35 starts. In the initial stage of injection, the molten thermoplastic resin 50 in the cavity 35 is foamed. After the molten thermoplastic resin fills the cavity 35 having a volume of V _F (= 0.8 V _B ), the movement of the plug body 41 from the forward end toward the reverse end starts. That is, the plug body 41 is subjected to a pressure (drag) P _{2 of} 7 MPa by the plug body moving means 42. At this time, the pressure (back pressure) P ₁ exerted on the molten thermoplastic resin in the cavity 35 by the resin plasticizing / melting means is 9 MPa. Therefore, the plug body 41 starts to move from the forward end to the reverse end by the plug moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. Then, during the movement of the plug body 41, the [pressure control / foaming suppression method] is executed. That is, the condition P _R > P _E (see Table 11) is satisfied. As a result, the gas is re-dissolved in the molten thermoplastic resin 50 in the cavity 35, and subsequent foaming in the molten thermoplastic resin 50 can be suppressed.

[Step-1230A]
And the process similar to [process-1040]-[process-1090] of Example 10 is performed continuously.

[Step-1200B]
First, the same steps as [Step-1000] to [Step-1020] of Example 10 are performed.

[Step-1210B]
Then, the [foaming method (2) in the initial injection stage] is executed. That is, the injection of the molten thermoplastic resin 50 into the cavity 35 is started in the same manner as in [Step-1030] of Example 10. However, unlike [Step-1030] of Example 10, the plug body 41 is moved by the plug body moving means 42 from the forward end to the reverse end before the injection of the molten thermoplastic resin 50 into the cavity 35 starts. Let it begin. The volume V ′ _F of the cavity 35 at the start of injection of the molten thermoplastic resin 50 into the cavity 35 may be set to 0.8 V _B , for example. As a result, when the injection of the molten thermoplastic resin 50 into the cavity 35 is started, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 rapidly decreases, so that the molten thermoplastic resin 50 into the cavity 35 is reduced. The molten thermoplastic resin 50 in the cavity 35 is foamed from the start of injection to the initial stage of injection.

After the cavity 35 formed by the contact surface 41A of the moving plug body 41 with the molten thermoplastic resin and the cavity surfaces of the fixed mold part 31 and the movable mold part 32 is filled with the molten thermoplastic resin. In addition, the movement of the plug body 41 from the forward end toward the reverse end continues. That is, the plug body 41 is subjected to a pressure (drag) P _{2 of} 7 MPa by the plug body moving means 42. At this time, the pressure (back pressure) P ₁ exerted on the molten thermoplastic resin in the cavity 35 by the resin plasticizing / melting means is 9 MPa. Therefore, the movement of the plug 41 from the forward end to the reverse end is continued by the plug moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. While the stopper 41 is moving, the [pressure control / foaming suppression method] is executed. That is, the condition P _R > P _E is satisfied. As a result, the gas is re-dissolved in the molten thermoplastic resin 50 in the cavity 35, and subsequent foaming in the molten thermoplastic resin 50 can be suppressed.

[Step-1220B]
And the process similar to [process-1040]-[process-1090] of Example 10 is performed continuously.

  The thirteenth embodiment is also a modification of the tenth embodiment, and includes the method 2B (see case [4-2] in FIG. 4) and the method 2b (case [5-2] in FIG. 5 and FIG. 6). Case [6-2]).

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. When the injection of the thermoplastic resin is completed, the plug body continues to move toward the reverse end by the plug moving means and / or the molten thermoplastic resin injected into the cavity, and the plug body moves to the reverse end. In the process of suppressing foaming of the molten thermoplastic resin in the cavity by setting the state of P _R > P _E at the time of positioning, the state of P _R <P _E in the process of cooling and solidifying the thermoplastic resin in the cavity Instead, the state of P _R > P _{E and} the state of P _R <P _E are repeated to obtain a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product (second 2B). Method).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P by the state of the _E state of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, the injection completion of molten thermoplastic resin into the cavity, the plug body moving means and / or cavities while continuing to move towards the further backward end of the plug body by the injected molten thermoplastic resin within, as well as, at the time the plug body is positioned in the backward end, by the state of P _R> P _E In the process of suppressing the foaming of the molten thermoplastic resin in the cavity and cooling and solidifying the thermoplastic resin in the cavity, instead of setting the state of P _R <P _E , the state of P _R > P _E and P _R < and the state of the P _E Again, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure (method of the 2b).

  Hereinafter, first, the method 2B will be described based on [Step-1300A] to [Step-1320A], and then the method 2b will be described based on [Step-1300B] to [Step-1310B].

[Step-1300A]
First, steps similar to [Step-1000] to [Step-1020] of Example 10 are performed, and further, in steps similar to [Step-1030] to [Step-1070] of Example 10, P by the state of _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity.

[Step-1310A]
Then, as in [Step-1080] of Example 10, the thermoplastic resin in the cavity 35 is cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. However, <unlike [Step -1080] Example 10, state of the P _E, in this step, P _R> P _R repeating the states of the state of the P _E and P _R <P _E, foam molded article A structure in which an unfoamed layer and a foamed layer are laminated in the depth direction is obtained.

  Specifically, [Method of inhibiting foaming during cooling / solidification (1)] and [Method of inhibiting foaming during cooling / solidification (2)], [Method of foaming during cooling / solidification (1)] and [Cooling / solidification] The combination with the foaming method (2) during solidification is executed.

That is, P _R > P _E is set for 5 seconds from the time when the plug body 41 is positioned at the forward end. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are values shown in Table 14. Then, the next 5 seconds, the state of P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are values shown in Table 15. Furthermore, this operation is repeated 6 times. Thereafter, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure exerted by the plug body moving means 42 on the plug body 41 until 120 seconds elapse after the completion of the injection of the molten thermoplastic resin 50 into the cavity 35 ( Drag) P ₄ is a value shown in Table 15.

[Table 14]
Pressure P ₃ : 10 MPa
Pressure (drag) P ₄ : 10 MPa

[Table 15]
Pressure P ₃ : 1 MPa
Pressure (drag) P ₄ : 1 MPa

[Step-1320A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-1300B]
First, steps similar to [Step-1200A] to [Step-1220A] of Example 12 are executed, and further, steps similar to [Step-1040] to [Step-1070] of Example 10 are executed.

  Alternatively, first, steps similar to [Step-1200B] to [Step-1210B] in Example 12 are executed, and further, steps similar to [Step-1040] to [Step-1070] in Example 10 are performed. Execute.

[Step-1310B]
Next, in a step similar to [Step-1080] in Example 10, the same step as [Step-1310A] is performed, and then the same step as [Step-1090] in Example 10 is performed.

When the volume of the foam molded product is V ₀ , the total volume of bubbles present in the foam molded product is V ₁ , the density of the molten thermoplastic resin is ρ ₀ , and the density of the thermoplastic resin used is ρ ₁ , V ₀ , V ₁ , ρ ₀ , ρ ₁ are as shown in Table 16 below, and these values satisfied Expression (1).

[Table 16]
V ₁ / V _0: 0.003
ρ ₀ : 1.34 g / cm ³
ρ ₁ : 1.43 g / cm ³

  The embodiment 14 is also a modification of the embodiment 10, and the method 2C (see case [4-3] in FIG. 4) and the method 2c (case [5-3] in FIG. 5 and FIG. 6). Case [6-3]).

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. When the injection of the thermoplastic resin is completed, the plug body continues to move toward the reverse end by the plug moving means and / or the molten thermoplastic resin injected into the cavity, and the plug body moves to the reverse end. In the process of suppressing foaming of the molten thermoplastic resin in the cavity by setting the state of P _R > P _E at the time of positioning, the state of P _R <P _E in the process of cooling and solidifying the thermoplastic resin in the cavity instead of a, P _R> suppressing foaming of molten thermoplastic resin in the cavity by the state of P _E, then the melting heat in the cavity by the state of P _R <P _E Foaming a plastic resin (a method of the 2C).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P by the state of the _E state of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, the injection completion of molten thermoplastic resin into the cavity, the plug body moving means and / or cavities while continuing to move towards the further backward end of the plug body by the injected molten thermoplastic resin within, as well as, at the time the plug body is positioned in the backward end, by the state of P _R> P _E By suppressing the foaming of the molten thermoplastic resin in the cavity and cooling / solidifying the thermoplastic resin in the cavity, instead of setting P _R <P _E , P _R > P _E Ki The foaming of the molten thermoplastic resin in the cavity is suppressed, and then the molten thermoplastic resin in the cavity is foamed by setting P _R <P _E (method 2c).

  Hereinafter, first, the method 2C will be described based on [Step-1400A] to [Step-1420A], and then the method 2c will be described based on [Step-1400B] to [Step-1410B].

[Step-1400A]
First, steps similar to [Step-1000] to [Step-1020] of Example 10 are performed, and further, in steps similar to [Step-1030] to [Step-1070] of Example 10, P by the state of _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity.

[Step-1410A]
Then, as in [Step-1080] of Example 10, the thermoplastic resin in the cavity 35 is cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. However, unlike [Step-1080] of Example 10 in which P _R <P _E is set, in this step, P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity. and, then, foaming the molten thermoplastic resin in the cavity by the state of P _R <P _E.

  Specifically, after executing [Method of suppressing foaming during cooling / solidification (1)] and [Method of suppressing foaming during cooling / solidification (2)], [Method of foaming during cooling / solidification] ([Cooling / solidification] 4 of foaming method during solidification (1), foaming method during cooling / solidification (2), foaming method during cooling / solidification (3), and foaming method during cooling / solidification (4). Any one of the foaming methods at the time of cooling and solidification may be adopted, or a combination of arbitrary plural methods may be adopted).

That is, P _R > P _E is set for 5 seconds from the time when the plug body 41 is positioned at the forward end. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 14. After that, the state of the P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 15. The pressure P ₃ exerted by the resin plasticizing / melting means and the pressure exerted by the plug moving means 42 on the plug 41 until 120 seconds elapse after completion of the injection of the molten thermoplastic resin 50 into the cavity 35 ( Drag) P ₄ is held at the value shown in Table 15.

[Step-1420A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-1400B]
First, steps similar to [Step-1200A] to [Step-1220A] of Example 12 are executed, and further, steps similar to [Step-1040] to [Step-1070] of Example 10 are executed.

  Alternatively, first, steps similar to [Step-1200B] to [Step-1210B] in Example 12 are executed, and further, steps similar to [Step-1040] to [Step-1070] in Example 10 are performed. Execute.

[Step-1410B]
Next, in the same step as [Step-1080] in Example 10, the same step as [Step-1410A] is executed, and then the same step as [Step-1090] in Example 10 is executed.

  The fifteenth embodiment is also a modification of the tenth embodiment, and the 2D method (see the case [4-4] in FIG. 4) and the second d method (the case [5-4] in FIG. 5 and FIG. 6). Case [6-4]).

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. When the injection of the thermoplastic resin is completed, the plug body continues to move toward the reverse end by the plug moving means and / or the molten thermoplastic resin injected into the cavity, and the plug body moves to the reverse end. At the time of positioning, in the step of suppressing foaming of the molten thermoplastic resin in the cavity by setting P _R > P _E , and then cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E instead of the state, P _R repeating the state of the <state of P _E and P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure (the 2D method).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P by the state of the _E state of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, the injection completion of molten thermoplastic resin into the cavity, the plug body moving means and / or cavities while continuing to move towards the further backward end of the plug body by the injected molten thermoplastic resin within, as well as, at the time the plug body is positioned in the backward end, by the state of P _R> P _E suppresses foaming of molten thermoplastic resin in the cavity, then, in the step of cooling and solidifying the thermoplastic resin in the cavity, instead of the state of P _R <P _E, P _R <a P _E state and P _R> P _E Repeating the state, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure (method of the 2d).

  Hereinafter, first, the method 2C will be described based on [Step-1500A] to [Step-1520A], and then the method 2c will be described based on [Step-1500B] to [Step-1510B].

[Step-1500A]
First, steps similar to [Step-1000] to [Step-1020] of Example 10 are performed, and further, in steps similar to [Step-1030] to [Step-1070] of Example 10, P by the state of _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity.

[Step-1510A]
Then, similarly to [Step -1410A] Example 14, the (specifically by the state of P _R> P _E, from the time the stopper 41 is positioned in its backward end, 5 seconds, the resin Foaming of the molten thermoplastic resin in the cavity by setting the pressure P ₃ exerted by the plasticizing / melting means and the pressure (drag) P ₄ exerted on the plug 41 by the plug moving means 42 to the values shown in Table 14) Suppress. Thereafter, in the same manner as in [Step-1310A] of Example 13, the state of P _R <P _{E and} the state of P _R > P _E are repeated, and an unfoamed layer and a foamed layer are formed in the depth direction of the foam molded product. To obtain a laminated structure. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to the values shown in Table 15 for the next 5 seconds. The pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted on the plug 41 by the plug moving means 42 are values shown in Table 14. Then, this operation is repeated 6 times. Thereafter, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure exerted by the plug body moving means 42 on the plug body 41 until 120 seconds elapse after the completion of the injection of the molten thermoplastic resin 50 into the cavity 35 ( Drag) P ₄ is a value shown in Table 15.

[Step-1520A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-1500B]
First, steps similar to [Step-1200A] to [Step-1220A] of Example 12 are executed, and further, steps similar to [Step-1040] to [Step-1070] of Example 10 are executed.

  Alternatively, first, steps similar to [Step-1200B] to [Step-1210B] in Example 12 are executed, and further, steps similar to [Step-1040] to [Step-1070] in Example 10 are performed. Execute.

[Step-1510B]
Next, in a step similar to [Step-1080] in Example 10, the same step as [Step-1510A] is performed, and then the same step as [Step-1090] in Example 10 is performed.

  The embodiment 16 is also a modification of the embodiment 10, and the 2E method (see the case [4-5] in FIG. 4) and the 2e method (the case [5-5] in FIG. 5 and FIG. 6). Case [6-5]).

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. the injection completion of thermoplastic resin, and, while continuing to move towards the further backward end of the plug body by the injected molten thermoplastic resin to the plug body moving means and / or cavity, the P _R> P _E In this state, foaming of the molten thermoplastic resin in the cavity is suppressed, and the plug body is further moved toward the reverse end by the subsequent plug body moving means and / or the molten thermoplastic resin injected into the cavity. during and are, as well, at the time the plug body is positioned in the backward end, and the state of P _R <P _E instead of the state of P _R> P _E, then, it is cooled and solidified thermoplastic resin in the cavity In that process, <instead of the state of P _E, P _R> P _R suppressing foaming of molten thermoplastic resin in the cavity by the state of P _E, then the state of P _R <P _E By doing so, the molten thermoplastic resin in the cavity is foamed (method 2E).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P _{By changing} the state of _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed, the injection of the molten thermoplastic resin into the cavity is completed, and the plug moving means and / or or suppressing foaming of molten thermoplastic resin in the cavity between, by the state of P _R> P _E which continues to move towards the further backward end of the plug body by the injected molten thermoplastic resin into the cavity Then, while the plug body continues to move toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, and at the time when the plug body is located at the backward end. There are, as the state of the P _R <P _E instead of the state of P _R> P _E, then, in the step of cooling and solidifying the thermoplastic resin in the cavity, instead of the state of P _R <P _E, By setting P _R > P _E , foaming of the molten thermoplastic resin in the cavity is suppressed, and thereafter, by setting P _R <P _E , the molten thermoplastic resin in the cavity is foamed (second e the method of).

In Example 16, P _R <P _{E in} the middle of continuing to move the plug body further toward the reverse end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity. Although the state, instead, may be a state of P _R <P _E immediately completion of injection of the molten thermoplastic resin.

  Hereinafter, first, the 2E method will be described based on [Step-1600A] to [Step-1630A], and then the 2e method will be described based on [Step-1600B] to [Step-1610B].

[Step-1600A]
First, steps similar to [Step-1000] to [Step-1020] of Example 10 are performed, and further, in steps similar to [Step-1030] to [Step-1060] of Example 10, P by the state of _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity. That is, the [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] are executed.

[Step-1610A]
Thereafter, in the latter stage of the step similar to [Step-1060] of Example 10 and the same step as [Step-1070], the [foaming method (2) during injection or until completion] is executed. That is, the plug body 41 is continuously moved toward the reverse end by the plug moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35, and is positioned at the reverse end. Thus, by holding the state of the P _R <P _E, it encourages foaming molten thermoplastic resin 50 in the cavity 35. Specifically, the pressure P ₁ and the pressure P ₂ are values shown in Table 17 below.

[Table 17]
Pressure P ₁ : 1 MPa
Pressure (drag) P ₂ : 1 MPa

[Step-1620A]
Next, as in [Step-1080] of Example 10, the thermoplastic resin in the cavity 35 is cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. However, unlike [Step-1080] of Example 10 in which P _R <P _E is set, in this step, P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity. and, then, foaming the molten thermoplastic resin in the cavity by the state of P _R <P _E.

  Specifically, the same process as [Process-1410A] of Example 14 is performed.

[Step-1630A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-1600B]
First, the same steps as [Step-1200A] to [Step-1220A] of Example 12 are executed, or first, the same steps as [Step-1200B] to [Step-1210B] of Example 12 are performed. Execute. Further, the same steps as [Step-1040] to [Step-1060] of Example 10 are performed. In the same steps as [Step-1040] to [Step-1060], P _R > by the state of P _E, it suppresses foaming of molten thermoplastic resin in the cavity. That is, the [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] are executed.

[Step-1610B]
Next, steps similar to [Step-1610A] to [Step-1630A] are performed.

  The embodiment 17 is also a modification of the embodiment 10, and the second F method (refer to the case [4-6] in FIG. 4) and the second f method (the cases [5-6] in FIG. 5 and FIG. 6). Case [6-6]).

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. the injection completion of thermoplastic resin, and, while continuing to move towards the further backward end of the plug body by the injected molten thermoplastic resin to the plug body moving means and / or cavity, the P _R> P _E In this state, foaming of the molten thermoplastic resin in the cavity is suppressed, and the plug body is further moved toward the reverse end by the subsequent plug body moving means and / or the molten thermoplastic resin injected into the cavity. during and are, as well, at the time the plug body is positioned in the backward end, and the state of P _R <P _E instead of the state of P _R> P _E, then, it is cooled and solidified thermoplastic resin within the cavity In that process, <instead of the state of P _E, P _R> P _R suppressing foaming of molten thermoplastic resin in the cavity by the state of P _E, then the state of P _R <P _E repeating the state of the P _R> P _E, in the depth direction of the foamed molded article unfoamed layer and foam layer to obtain a laminated structure (method of the 2F).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P _{By changing} the state of _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed, the injection of the molten thermoplastic resin into the cavity is completed, and the plug moving means and / or or suppressing foaming of molten thermoplastic resin in the cavity between, by the state of P _R> P _E which continues to move towards the further backward end of the plug body by the injected molten thermoplastic resin into the cavity Then, while the plug body continues to move toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, and at the time when the plug body is located at the backward end. There are, as the state of the P _R <P _E instead of the state of P _R> P _E, then, in the step of cooling and solidifying the thermoplastic resin in the cavity, instead of the state of P _R <P _E, By setting P _R > P _E , foaming of the molten thermoplastic resin in the cavity is suppressed, and then P _R <P _E and P _R > P _E are repeated, and the depth of the foam molded product is increased. A structure in which an unfoamed layer and a foamed layer are laminated in the vertical direction is obtained (method 2f).

In Example 17, P _R <P _{E in} the middle of continuing to move the plug body further toward the reverse end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity. Although the state, instead, may be a state of P _R <P _E immediately completion of injection of the molten thermoplastic resin.

  Hereinafter, first, the 2E method will be described based on [Step-1700A] to [Step-1720A], and then the 2e method will be described based on [Step-1700B] to [Step-1710B].

[Step-1700A]
First, the same steps as [Step-1600A] to [Step-1610A] of Example 17 are executed.

[Step-1710A]
Next, as in [Step-1080] of Example 10, the thermoplastic resin in the cavity 35 is cooled and solidified for 120 seconds after the injection of the molten thermoplastic resin 50 into the cavity 35 is completed. However, unlike the P _R <[Step -1080] Example 10, state of the P _E, in this step, a step similar to [Step -1310A] of Example 13.

[Step-1720A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-1700B]
First, the same steps as [Step-1200A] to [Step-1220A] of Example 12 are executed, or first, the same steps as [Step-1200B] to [Step-1210B] of Example 12 are performed. Execute. Further, the same steps as [Step-1040] to [Step-1060] of Example 10 are performed. In the same steps as [Step-1040] to [Step-1060], P _R > by the state of P _E, it suppresses foaming of molten thermoplastic resin in the cavity. That is, the [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] are executed.

[Step-1710B]
Next, the same steps as [Step-1710A] to [Step-1720A] are performed.

  Example 18 is also a modification of Example 10 and relates to the 2G method (see case [4-7] in FIG. 4, case [5-7] in FIG. 5 and case [6-7] in FIG. 6). .

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. When the injection of the thermoplastic resin is completed, the plug body continues to move toward the reverse end by the plug moving means and / or the molten thermoplastic resin injected into the cavity, and the plug body moves to the reverse end. At the time of positioning, instead of setting P _R > P _E , instead of setting P _R <P _E , and in the process of cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E to, to suppress the foaming of molten thermoplastic resin in the cavity by the state of P _R> P _E, then foaming the molten thermoplastic resin in the cavity by the state of P _R <P _E.

In Example 18, the state of P _R <P _E is set immediately after the start of the process of cooling and solidifying the thermoplastic resin in the cavity, and then the state of P _R > P _E is set. or as the state of the P _R> P _E simultaneously start the process.

  Hereinafter, the 2G method will be described based on [Step-1800] to [Step-1830].

[Step-1800]
First, the same steps as [Step-1200A] to [Step-1220A] in Example 12 are performed. Alternatively, the same steps as [Step-1200B] to [Step-1210B] of the twelfth embodiment are executed.

Alternatively, the [foaming method (3) in the initial injection stage] is executed. That is, the injection early stage of molten thermoplastic resin into the cavity 35, to the state of P _R <P _E, in a step similar to [Step -1000] Example 10, the volume of the cavity 35 The plug body 41 is positioned in the cavity 35 by the plug body moving means 42 so that the value of V _F becomes substantially zero. In the same step as [Step-1030] of Example 10, when the plug body 41 starts to move from the forward end to the reverse end simultaneously with the start of injection of the molten thermoplastic resin 50 into the cavity 35. If the [foaming method (3) in the initial stage of injection] is executed, the pressure of the molten thermoplastic resin 50 injected into the cavity 35 is suddenly reduced. In the stage, the molten thermoplastic resin 50 in the cavity 35 is foamed. Specifically, the pressure P ₁ and the pressure P ₂ are values shown in Table 17.

[Step-1810]
Thereafter, in the same steps as [Step-1040] to [Step-1070] of Example 10, the execution of [foaming method (2) during injection or until completion] is continued. That is, during the injection of the molten thermoplastic resin 50 into the cavity 35, the plug body 41 continues to move toward the backward end by the plug body moving means 42 and the molten thermoplastic resin 50 injected into the cavity 35. Thus, by holding the state of the P _R <P _E, it encourages foaming molten thermoplastic resin 50 in the cavity 35. Specifically, the pressure P ₁ and the pressure P ₂ are values shown in Table 17.

[Step-1820]
Then, in a step similar to [Step -1080] Example 10, from the time the stopper 41 is positioned in its backward end, 5 seconds, the state of P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 15. Then, 5 seconds, the state of P _R> P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 14. Then, the state of P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 15. And, furthermore, between the completion of injection into the cavity 35 of the molten thermoplastic resin 50 until the lapse of 120 seconds, to hold the state of the P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted on the plug body 41 by the plug body moving means 42 are maintained at the values shown in Table 15.

[Step-1830]
Next, a step similar to [Step-1090] of Example 10 is performed.

  Example 19 is also a modification of Example 10 and relates to the 2H method (see case [4-8] in FIG. 4, case [5-8] in FIG. 5 and case [6-8] in FIG. 6). .

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. When the injection of the thermoplastic resin is completed, the plug body continues to move toward the reverse end by the plug moving means and / or the molten thermoplastic resin injected into the cavity, and the plug body moves to the reverse end. in the position point in time, instead of the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity by the state of P _R> P _E, then the thermoplastic resin in the cavity in the step of cooling and solidifying, instead of the state of P _R <P _E, repeating the states of P _R <P _E state and P _R> P _E, and a non-foamed layer in the depth direction of the foam molded article Structure with laminated foam layer Get.

In Example 19, immediately after the start of the process of cooling and solidifying the thermoplastic resin in the cavity, P _R <P _E is set, and then P _R > P _E is set. or as the state of the P _R> P _E simultaneously start the process.

  Hereinafter, the 2H method will be described based on [Step-1900] to [Step-1920].

[Step-1900]
First, the same steps as [Step-1800] to [Step-1810] of Example 18 are executed.

[Step-1910]
Then, in a step similar to [Step -1080] Example 10, from the time the stopper 41 is positioned in its backward end, 5 seconds, the state of P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 15. Then, 5 seconds, the state of P _R> P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 14. Then, this operation is repeated 6 times. Thereafter, during the period from completion of injection into the cavity 35 of the molten thermoplastic resin 50 until the lapse of 120 seconds, to hold the state of the P _R <P _E. Specifically, the pressure P ₃ exerted by the resin plasticizing / melting means and the pressure (drag) P ₄ exerted by the plug moving means 42 on the plug 41 are set to values shown in Table 15.

[Step-1920]
Next, a step similar to [Step-1090] of Example 10 is performed.

  The 20th embodiment is also a modification of the 10th embodiment, and the 2J method (see the case [4-9] in FIG. 4) and the 2j method (the case [5-9] in FIG. 5 and FIG. 6). Case [6-9]).

That is, the molten thermoplastic resin is melted into the cavity while the molten thermoplastic resin is being injected and the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end. the injection completion of thermoplastic resins, by the state of P _R> P _E, it suppresses foaming of molten thermoplastic resin in the cavity, then, over a step of cooling and solidifying the thermoplastic resin in the cavity, By repeating the state of P _R <P _{E and} the state of P _R > P _E , a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product is obtained (second J method).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P by the state of the _E state of the P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity, then, over a step of cooling and solidifying the thermoplastic resin in the cavity, P _R <P repeating the state of the _E state and P _R> P _E, the unfoamed layers in the depth direction of the molded foam and the foam layer to obtain a laminated structure (method of the 2j).

In Example 20, the state of P _R <P _{E and} the state of P _R > P _E are repeated in the middle of the injection of the molten thermoplastic resin, but instead, the injection of the molten thermoplastic resin is completed. From the time point, the state of P _R <P _{E and} the state of P _R > P _E may be repeated.

  Hereinafter, first, the 2G method will be described based on [Step-2000A] to [Step-2030A], and then the 2g method will be described based on [Step-2000B] to [Step-2010B].

[Step-2000A]
First, the same steps as [Step-1000] to [Step-1020] of Example 10 are executed, and further, P in the same steps as [Step-1030] to [Step-1040] of Example 10 is performed. by the state of _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity. That is, the [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] are executed.

[Step-2010A]
Next, in the same process as [Step-1070] of Example 10 from the continuation of the same process as [Step-1040] of Example 10, [Pressure control / foaming suppression method] (see Table 11 for conditions), And [foaming method during injection or until completion (2)] (refer to Table 17 for conditions). As a result, the repetition of the state of P _R <P _{E and} the state of P _R > P _E can be achieved.

[Step-2020A]
Thereafter, by executing the same step as [Step-1310A] of Example 13, it is possible to obtain a repetition of the state of P _R <P _{E and} the state of P _R > P _E.

[Step-2030A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-2000B]
First, the same steps as [Step-1200A] to [Step-1220A] in Example 12 are performed. Alternatively, first, steps similar to [Step-1200B] to [Step-1210B] of the twelfth embodiment are executed. And, furthermore, in a step similar to [Step -1040] Example 10, by the state of P _R> P _E, it suppresses foaming of molten thermoplastic resin in the cavity. That is, the [pressure control / foaming suppression method] is executed.

[Step-2010B]
Then, [Step-2010A] to [Step-2030A] are executed.

  The embodiment 21 is also a modification of the embodiment 10, and the 2K method (see the case [4-10] in FIG. 4) and the 2k method (the cases [5-10] in FIG. 5 and FIG. 6). Case [6-10]).

That is, while the molten thermoplastic resin is being injected, the plug moving means and / or the molten thermoplastic resin injected into the cavity continues to move toward the backward end, and into the cavity. at the completion of injection of the molten thermoplastic resin, P _R> by the state of P _E, suppresses foaming of molten thermoplastic resin in the cavity, the plug body after the completion of injection of the molten thermoplastic resin into the cavity during which continues to move towards the further backward end of the plug body by the movement means and / or injected molten thermoplastic resin into the cavity, from the state of P _R> P _E, the state of P _R <P _E Repeating the state of P _R > P _E and then cooling and solidifying the thermoplastic resin in the cavity, repeating the state of P _R <P _{E and} the state of P _R > P _E , And unfoamed layer in the depth direction And a foam layer obtaining a laminated structure (method of the 2K).

Alternatively, while the molten thermoplastic resin is being injected, while the plug body is being moved toward the backward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, P _R <P _{By changing} the state of _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed, and then, during the injection of the molten thermoplastic resin, the plug moving means and / or in the cavity the stopper by injected molten thermoplastic resin while continuing to move toward the backward end, and, upon completion of injection of the molten thermoplastic resin into the cavity, by the state of P _R> P _E in The foaming of the molten thermoplastic resin in the cavity is suppressed, and the plug body is moved by the plug moving means after the injection of the molten thermoplastic resin into the cavity and / or the molten thermoplastic resin injected into the cavity. In between which it continues to move toward the rearward end, from the state of P _R> P _E, repeating the states of P _R <P _E state and P _R> P _E, then the thermoplastic resin in the cavity In the process of cooling and solidifying the resin, the state of P _R <P _{E and} the state of P _R > P _E are repeated to obtain a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foam molded product. (2k method).

In Example 21, the plug body moving means after completion of injection of the molten thermoplastic resin into the cavity and / or the plug body is further directed toward the backward end by the molten thermoplastic resin injected into the cavity. While the movement is continued, the state of P _R <P _{E and} the state of P _R > P _E are repeated, but instead, the state of P _R <P _{E and} the state of P _R from the point when the injection of the molten thermoplastic resin is completed. > it may be repeated and the state of the P _E.

  Hereinafter, first, the 2G method will be described based on [Step-2100A] to [Step-2130A], and then the 2g method will be described based on [Step-2100B] to [Step-2110B].

[Step-2100A]
First, steps similar to [Step-1000] to [Step-1020] of Example 10 are performed, and further, in steps similar to [Step-1030] to [Step-1060] of Example 10, P by the state of _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity. That is, the [pressure control / foaming suppression method] and [foaming suppression method in the initial stage of injection] are executed.

[Step-2110A]
Next, in the same process as [Step-1070] of Example 10 from the continuation of the same process as [Step-1060] of Example 10, [Pressure control / foaming suppression method] (see Table 11 for conditions), And [foaming method during injection or until completion (2)] (refer to Table 17 for conditions). As a result, the repetition of the state of P _R <P _{E and} the state of P _R > P _E can be achieved.

[Step-2120A]
Thereafter, by executing the same step as [Step-1310A] of Example 13, it is possible to obtain a repetition of the state of P _R <P _{E and} the state of P _R > P _E.

[Step-2130A]
Next, a step similar to [Step-1090] of Example 10 is performed.

[Step-2100B]
First, the same steps as [Step-1200A] to [Step-1220A] in Example 12 are performed. Alternatively, first, steps similar to [Step-1200B] to [Step-1210B] of the twelfth embodiment are executed. And, furthermore, inhibit in a step similar to [Step -1040] ~ [Step -1060] Example 10, by the state of P _R> P _E, the foamed molten thermoplastic resin in the cavity . That is, the [pressure control / foaming suppression method] is executed.

[Step-2110B]
Then, [Step-2110A] to [Step-2130A] are executed.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these. The mold assembly, resin plasticizing / melting means, configuration of injection molding apparatus, structure, various conditions in the injection foam molding method, the type of thermoplastic resin used, etc. are examples, and may be changed as appropriate. it can. For example, the number and positions of the molten resin injection portions in the mold assembly are examples and can be changed as appropriate. The plug can be moved by the plug moving means or by the pressure of the injection molten thermoplastic resin. In the embodiment, one molded product is obtained, but a large number of molded products can be obtained.

In the case of molding a foam molded product that does not have any problem even if foam cells (bubbles) exist on the surface, for example, the case [1-8] in FIG. 1, the case [2-8] in FIG. 2, and the case in FIG. As shown in 3-8], in the injection foam molding method according to the first aspect of the present invention, in the step (E), P _R <P _E is set, and also in the step (F). , instead of the state of P _R> P _E, it can be brought to a state of P _R <P _E. Alternatively, for example, as shown in case [1-9] in FIG. 1, case [2-9] in FIG. 2, and case [3-9] in FIG. 3, the injection foam according to the first aspect of the present invention. in the molding method, in the step (E), the state of P _R> P _E, then, over the step (G), may be employed a condition of P _R <P _E Alternatively, In the step (E), after changing from the state of P _R <P _{E to} the state of P _R > P _E , the state of P _R <P _E can be obtained in the step (G).

Alternatively, for example, as shown in case [4-11] in FIG. 4, case [5-11] in FIG. 5 and case [6-11] in FIG. 6, the injection foaming according to the second aspect of the present invention. in the molding method, the step (E), in the step (F) and step (G), can be brought to a state of P _R <P _E. Alternatively, for example, case [4-12] in FIG. 4, case [4-13] in FIG. 4, case [5-12] in FIG. 5, case [5-13] in FIG. 5, case [5-13] in FIG. 6-12] and the case [6-13] of FIG. 6, in the injection foam molding method according to the second aspect of the present invention, in the step (E), P _R > P _E by state, suppressing the foaming of molten thermoplastic resin in the cavity, then, over the step (I), may be employed a condition of P _R <P _E, in the step (E), By changing the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed. Then, the process proceeds to the step (I), and the state of P _R <P _E It can also be.

  When there is no risk of jetting when the molten thermoplastic resin is injected into the cavity, a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product (laminated annual rings) For example, before the injection of the molten thermoplastic resin into the cavity is started, the plug body is positioned at the backward end in the cavity by the plug body moving means. The steps (B) to (H) of the injection foam molding method according to the first aspect or the steps (B) to (J) of the injection foam molding method according to the first aspect of the present invention may be executed. In these cases, in the step of cooling and solidifying the thermoplastic resin in the cavity, [foaming suppression method during cooling / solidification (1)] and / or [foaming suppression method during cooling / solidification ( 2)] and [foaming method during cooling / solidification (1)] and / or [foaming method during cooling / solidification (2)].

[Modification of plasticizing / melting means]
FIG. 13 shows a modification of the resin plasticizing / melting means for plasticizing / melting the thermoplastic resin in the injection molding apparatus. This resin plasticizing / melting means includes a heating cylinder 61 and a reservoir 70. Then, the thermoplastic resin is plasticized and melted in advance in the heating cylinder 61, the molten thermoplastic resin is transferred to the reservoir 70, the gas is dissolved in the molten thermoplastic resin in the reservoir 70, and the molten thermoplastic resin Weigh. The mold assembly can be the same as the mold assembly described in the first embodiment, for example.

  A screw 62 is disposed in the heating cylinder 61. The screw 62 is rotated by a hydraulic motor 65 via a reduction gear 64. In FIG. 13, reference numeral 66 is a hopper, reference numeral 67 is an extrusion ram, reference numeral 68 is a hydraulic cylinder for extrusion, reference numeral 69 is a cylinder for advancing and retreating the injection device, and reference numerals 69A and 69B are hydraulic pipes. Number 69C is a pressure gauge.

  When this resin plasticizing / melting means is used, in the same step as [Step-110] in Example 1, first, the thermoplastic resin is plasticized / melted by the heating cylinder 61. Specifically, the thermoplastic resin put into the screw 62 from the hopper 66 is heated, plasticized, and melted by the heating cylinder 61 and the screw 62. Then, by applying pressure to the extrusion ram 67 by the extrusion hydraulic cylinder 68, the screw 62 is pushed forward and pressure is applied to the molten thermoplastic resin. As a result, the molten thermoplastic resin stored in the gap 63A is stored in the reservoir 70. It is transferred to. By controlling the volume of the reservoir 70 by the injection hydraulic cylinder 71, the molten thermoplastic resin can be measured in the reservoir 70. Further, the reservoir 70 is provided with a gas introduction part 72, and a gas can be introduced into the reservoir 70 from a gas source (not shown) through a pipe (not shown) and the gas introduction part 72. Furthermore, an injection hydraulic cylinder 71 (hydraulic piping, pressure gauge, and the like are not shown) is disposed at the rear end of the reservoir 70, and is stored in the reservoir 70 by the operation of the injection hydraulic cylinder 71. The molten thermoplastic resin in a gas-dissolved state can be extruded at a high speed and injected from the molten resin injection portion 34 to the cavity 35 via the molten resin flow path 33.

  Thereafter, a foamed molded article may be molded substantially based on the same steps as [Step-110] to [Step-170] in Example 1. The resin metering back pressure corresponds to the pressure applied to the molten thermoplastic resin in the gas dissolved state stored in the reservoir 70 by the injection hydraulic cylinder 71. Further, by applying pressure to the molten thermoplastic resin in the reservoir 70 by the injection hydraulic cylinder 71, the pressure is applied to the inside of the cavity 35 via the molten thermoplastic resin in the molten resin flow path 33 and the molten resin injection portion 34. By being transmitted to the molten thermoplastic resin, pressure is applied to the molten thermoplastic resin in the cavity 35, gas foaming in the molten thermoplastic resin in the cavity 35 is suppressed, or the melt injected into the cavity 35. The gas foamed in the thermoplastic resin can be redissolved in the molten thermoplastic resin in the cavity 35. Furthermore, by stopping the pressure holding operation (that is, by stopping the pressure applied to the molten thermoplastic resin in the reservoir 70 by the injection hydraulic cylinder 71), the pressure is applied to the molten thermoplastic resin in the cavity 35. Can be stopped.

Regarding [Foaming method (3) at the time of cooling and solidification] In the same step as [Step-160] in Example 1, the molten thermoplastic resin in the cavity 35 is solidified by solidification of the molten thermoplastic resin in the molten resin injection portion 34. For example, a method described below may be adopted in order to stop applying pressure.

  That is, as a specific method for solidifying the molten thermoplastic resin in the molten resin injection portion 34, for example, after completion of injection of the molten thermoplastic resin into the cavity 35 and after a predetermined time has elapsed from the start of injection A part of the heating means (specifically a heater, not shown in FIGS. 7 and 8) disposed in the fixed mold part 31 and the movable mold part 32 (in the vicinity of the molten resin injection part) The arranged heater) is inactivated. As a result, the temperature of the molten thermoplastic resin present in the molten resin injection part 34 can be lowered and solidified.

Regarding [Foaming method (1) during cooling and solidification] In the same step as [Step-160] in Example 1, the molten thermoplastic resin in the cavity 35 is mechanically closed by closing the molten resin injection portion 34. The pressure can be stopped. For example, the molten resin flow path in the fixed mold part 31 is a hot runner 80, the molten resin injection part 34 is a valve gate 83, and a specific means for mechanically closing the molten resin injection part 34 is a shut-off pin 84. To do. A schematic diagram of the molten resin flow path (hot runner 80), the valve gate 83, and the shut-off pin 84 is shown in FIG. In FIG. 14, reference numeral 81 is a runner manifold, reference numeral 82 is a heater, and reference numeral 85 is a hydraulic cylinder. The movement of the hydraulic cylinder 85 causes the shut-off pin 84 to open and close the valve gate 83 that is the molten resin injection portion 34. In this example, for example, after the injection of the molten thermoplastic resin into the cavity 35 is completed and a predetermined time has elapsed from the start of the injection, the shut-off pin 84 is operated to thereby operate the molten resin injection portion. The valve gate 83 which is 34 is mechanically closed.

  Alternatively, in the same step as [Step-160] in Example 1, the molten resin flow path 33 is mechanically closed to stop applying pressure to the molten thermoplastic resin in the cavity 35. it can. For example, the molten resin flow path in the fixed mold portion 31 is a hot runner 90, and the means for mechanically closing the molten resin flow path (hot runner 90) is a combination of the valve gate 93 and the shut-off pin 94. A schematic diagram of the molten resin flow path (hot runner 90), the valve gate 93 and the shut-off pin 94 is shown in FIG. In FIG. 15, reference numeral 91 is a runner manifold, reference numeral 92 is a heater, and reference numeral 95 is a hydraulic cylinder. The shutoff pin 94 opens and closes the valve gate 93 by the movement of the hydraulic cylinder 95. In this example, for example, after completion of injection of the molten thermoplastic resin into the cavity 35 and after a predetermined time has elapsed from the start of injection, the valve gate 93 is closed by operating the shut-off pin 94. Thus, the molten resin flow path (hot runner 90) can be mechanically closed. As described above, the molten resin injection portion 34 may be a combination of the valve gate 83 and the shut-off pin 84, so that the thermoplastic resin in the cavity is cooled and solidified. This is preferable from the viewpoint of not solidifying the molten thermoplastic resin.

  Alternatively, in the same step as [Step-160] in Example 1, the application of pressure to the molten thermoplastic resin in the cavity 35 is stopped by mechanically closing the resin plasticizing / melting means. You can also. As schematically shown in FIG. 16, a means for mechanically closing the resin plasticizing / melting means is a shut-off valve 100 disposed in the nozzle head portion 13. The shut-off valve 100 is positioned at the forward end and the reverse end by the hydraulic cylinder 101. When the shut-off valve 100 is positioned at the forward end (see FIG. 16), the resin plasticizing / melting means is closed, and the shut-off valve 100 is closed. When 100 is positioned at the reverse end, the resin plasticizing / melting means is in an open state. In this example, for example, after completion of the injection of the molten thermoplastic resin into the cavity 35 and after a predetermined time has elapsed from the start of injection, the shutoff valve 100 is operated by the operation of the hydraulic cylinder 101. Thus, the resin plasticizing / melting means can be mechanically closed. When the resin plasticizing / melting means is composed of the heating cylinder 61 and the reservoir 70, a shut-off valve may be disposed at the tip of the reservoir 70.

In the embodiment, the cavity 35 when injecting the molten thermoplastic resin in a gas-dissolved state into the cavity is an atmospheric atmosphere, but before injecting the measured molten thermoplastic resin into the cavity 35, Alternatively, the cavity 35 may be filled with a pressurized fluid. Here, nitrogen gas with a pressure of 5 × 10 ⁶ Pa can be exemplified as the pressurized fluid filled in the cavity 35. Since the cavity 35 cannot be a completely sealed space, most of the pressurized fluid is discharged from the parting surface and the protruding portion to the outside when the molten thermoplastic resin in the gas dissolved state is injected into the cavity 35. A part of the pressurized fluid is dissolved in the molten thermoplastic resin injected into the cavity 35.

  17 to 19 are schematic sectional views showing modifications of the mold assembly.

  In the mold assembly shown in FIG. 17, the plug body moving means 42 in the mold assembly similar to the mold assembly shown in FIGS. 7 and 8 is composed of a spring (spring).

  Further, in the mold assembly shown in FIG. 18, the stopper moving means is constituted by a rack and pinion mechanism 112 including a rack 110 and a pinion gear 111. The gear portions of the rack 110 and the pinion gear 111 are not shown. One end of the rack 110 is attached to the connecting rod 43. The pinion gear 111 is rotated by a motor (not shown), whereby the connecting rod 43 and the plug body 41 to which the rack 110 is attached move. With such a mold structure, a curved pipe having an arc shape can be produced. In FIG. 18, the resin plasticizing / melting means is not shown.

  Designs and functional parts can be shaped on the surface of the foam molded product. In the mold assembly shown in FIG. 19, by providing the recess 35 </ b> A on the mold surface of the cavity 35, a spiral thread portion can be formed on the outer surface of the foam molded product. In such a case, the outer diameter of the plug body 41 is made smaller than the diameter of the valley portion of the screw part formed in the foam molded product, and the length of the plug body 41 is made longer than the entire length of the screw part, It is preferable that the moving distance 41 is longer than the entire length of the screw portion.

  20 to 22 are schematic sectional views showing other specific examples of the mold assembly. 20 to 22, illustration of the resin plasticizing / melting means is omitted. The shape of the cavity 35 is designed so that a portion extended from the foam molded product is formed in the foam molded product, and the molten resin injection portion 34 is arranged in the portion of the cavity corresponding to the extended portion.

  The mold assembly shown in FIG. 20A is provided with two plug bodies 41A and 41B and plug body moving means 42A and 42B. The mold assembly shown in FIG. 20B is provided with one plug body 41 and plug body moving means 42. Further, the mold assembly shown in FIGS. 21 and 22 includes three plug bodies 41A, 41B, 41C and plug body moving means 42A, 42B, 42C. The plug body and the plug body moving means are connected by connecting rods 43, 43A, 43B, and 43C that can be moved by the operation of the plug body moving means. The plug moving means is composed of, for example, a hydraulic cylinder that is hydraulically operated.

  By using the mold assembly shown in FIGS. 20A and 20B and FIG. 21, a T-shaped foam molded product can be formed. On the other hand, by using the mold assembly shown in FIG. 22, a cross-shaped foam-molded product can be molded.

FIG. 1 is a chart for explaining an injection foam molding method according to the first embodiment of the present invention. FIG. 2 is a chart for explaining the injection foam molding method according to the first aspect of the present invention. FIG. 3 is a chart for explaining the injection foam molding method according to the first aspect of the present invention. FIG. 4 is a chart for explaining an injection foam molding method according to the second aspect of the present invention. FIG. 5 is a chart for explaining the injection foam molding method according to the second aspect of the present invention. FIG. 6 is a chart for explaining the injection foam molding method according to the second aspect of the present invention. FIG. 7 is a schematic cross-sectional view of a mold assembly suitable for use in the embodiment, and shows a state in which the stopper is located at the backward end. FIG. 8 is a schematic cross-sectional view of a mold assembly suitable for use in the embodiment, showing a state in which the stopper is located at the forward end. FIG. 9 is a schematic view in which a part of an injection cylinder, which is a resin plasticizing / melting means for plasticizing / melting a thermoplastic resin suitable for use in the embodiment, is cut out. FIG. 10 is a schematic cross-sectional view of a mold assembly and the like for explaining the injection foam molding method of the first embodiment. FIG. 11 is a schematic cross-sectional view of a mold assembly and the like for explaining the injection foam molding method of Example 1 following FIG. FIG. 12 is a schematic cross-sectional view of a mold assembly and the like for explaining the injection foam molding method of Example 1 following FIG. FIG. 13 is a schematic diagram of a heating cylinder and a reservoir, which is a modified example of a resin plasticizing / melting means for plasticizing / melting a thermoplastic resin. FIG. 14 is a schematic partial cross-sectional view of the periphery of the molten resin injection part including a shut-off pin, which is a specific means for mechanically closing the molten resin injection part. FIG. 15 is a schematic diagram of a molten resin flow path, a valve gate, and a shut-off pin. FIG. 16 is a schematic diagram of a shut-off valve disposed in a nozzle head portion which is a means for mechanically closing the resin plasticizing / melting means. FIG. 17 is a schematic cross-sectional view of a mold assembly in the case where the plug body moving means is formed from a ridge. FIG. 18 is a schematic cross-sectional view of a mold assembly in the case where the plug body moving means is constituted by a rack and pinion mechanism. FIG. 19 is a schematic cross-sectional view of a mold assembly for forming a helical thread portion on the outer surface of a foam molded product. 20A and 20B are schematic cross-sectional views of a mold assembly for molding a foam molded article having a T-shaped branch structure. FIG. 21 is a schematic cross-sectional view of a mold assembly for molding a foam molded article having a T-shaped branch structure. FIG. 22 is a schematic cross-sectional view of a mold assembly for molding a foam molded article having a cross-shaped branch structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Resin plasticizing / melting means (injection cylinder), 11 ... Heating cylinder, 12 ... Screw, 13 ... Nozzle head part, 13A ... Air gap, 14 ... Reduction gear, DESCRIPTION OF SYMBOLS 15 ... Hydraulic motor, 16 ... Hopper, 17 ... Injection ram, 18 ... Hydraulic cylinder for injection, 19 ... Cylinder for advance / retreat of injection device, 19A, 19B ... Hydraulic piping, 19C ... Pressure gauge, 20 ... Gas introduction part, 30 ... Mold assembly, 31 ... Fixed mold part, 32 ... Movable mold part, 33 ... Molten resin flow path, 34 ... Molten resin injection part, 35 ... Cavity, 36 ... Nest, 41, 41A, 41B, 41C ... Plug body, 42, 42A, 42B, 42C ... Plug body moving means, 43 , 43A, 43B, 43C ... connecting rod, 50 ... Molten thermoplastic resin, 61 ... heating cylinder, 62 ... screw, 63A ... gap, 64 ... reduction gear, 65 ... hydraulic motor, 66 ... hopper, 67 ... for extrusion Ram, 68 ... hydraulic cylinder for extrusion, 69 ... cylinder for forward and backward injection, 69A, 69B ... hydraulic piping, 69C ... pressure gauge, 70 ... reservoir, 71 ... for injection Hydraulic cylinder, 72 ... Gas introduction part, 80, 90 ... Hot runner, 81, 91 ... Runner manifold, 82, 92 ... Heater, 83, 93 ... Valve gate, 84, 94 ... Shut-off pins, 85, 95 ... Hydraulic cylinders, 100 ... Shut-off valves, 101 ... Hydraulic cylinders, 110 ... Racks, 111 ... Pinion gears, 11 ... rack-and-pinion mechanism

Claims (32)

A resin plasticizing / melting means for plasticizing / melting a thermoplastic resin, and a mold assembly,
The mold assembly includes a fixed mold part, a movable mold part, a plug body, and plug body moving means for moving the plug body,
The mold assembly includes a cavity formed by clamping a fixed mold part and a movable mold part, a molten resin injection part opened in the cavity, and a molten resin injection part and resin plasticizing / melting means, A molten resin flow path connecting
The plug body is an injection foam molding method using an injection molding apparatus that can move in the cavity substantially parallel to the flow axis direction of the molten thermoplastic resin injected from the molten resin injection section by the operation of the plug body moving means. There,
(A) Before the injection of the molten thermoplastic resin into the cavity, the plug body is positioned at the forward end in the cavity by the plug body moving means,
(B) After plasticizing and melting the thermoplastic resin by resin plasticizing and melting means, dissolving the gas in the molten thermoplastic resin, and weighing the molten thermoplastic resin,
(C) It is weighed from the resin plasticizing / melting means into the cavity formed by clamping the fixed mold part and the movable mold part via the molten resin flow path and the molten resin injection part. Injecting molten thermoplastic resin
(D) Before the injection of the molten thermoplastic resin into the cavity, simultaneously with the start of the injection, or after the start of the injection, from the advance end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity Start the movement of the plug toward the reverse end,
(E) During the injection of the molten thermoplastic resin, the plug body is continuously moved toward the rearward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity,
(F) The injection of the molten thermoplastic resin is completed, and at the same time, the plug body is positioned at the reverse end by the molten thermoplastic resin injected into the plug body moving means and / or the cavity,
(G) Cool and solidify the thermoplastic resin in the cavity, then
(H) Open the fixed mold part and the movable mold part and take out the foam molded product.
Comprising each step,
When the pressure of the molten thermoplastic resin in the cavity P _R, the pressure of the molten thermoplastic resin in the cavity starts foaming was P _E,
Wherein in the step (F), by the state of P _R> P _E, it suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), the molten thermoplastic resin in the cavity is foamed by setting P _R <PE so as to _satisfy the condition of P _R <PE. Wherein in the step (E), by the state of P _R> P _E, injection foam molding method according to claim 1, characterized in that to suppress the foaming of molten thermoplastic resin in the cavity. In the step (E), P _R by the state of <state from P _R of P _E> P _E, according to claim 1, characterized in that to suppress the foaming of molten thermoplastic resin in the cavity Injection foam molding method. Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. The injection foam molding method according to claim 1, wherein a structure in which a foam layer is laminated is obtained. In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. The injection foam molding method according to claim 1, wherein a structure in which a foam layer is laminated is obtained. Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E 2. The injection foam molding method according to claim 1, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E 2. The injection foam molding method according to claim 1, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 1 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 1 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. Wherein in the step (E), the state of P _R <P _E,
In the step (F), instead of setting P _R > P _E , P _R <P _E is set,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E 2. The injection foam molding method according to claim 1, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. Wherein in the step (E), the state of P _R <P _E,
In the step (F), instead of setting P _R > P _E , P _R <P _E is set,
In the step (G), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 1 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. In the step (E), the state of P _R > P _E is set, and then the state of P _R <P _{E and} the state of P _R > P _E are repeated in the step (G), and the depth of the foam molded product is increased. The injection foam molding method according to claim 1, wherein a structure in which an unfoamed layer and a foamed layer are laminated in a vertical direction is obtained. In the step (E), after <from the state of P _E P _R> P _R state of P _E, over the step (G), and the state of the P _R <a P _E state and P _R> P _E The injection foam molding method according to claim 1, wherein a structure in which an unfoamed layer and a foamed layer are laminated in a depth direction of the foam molded product is repeated. A resin plasticizing / melting means for plasticizing / melting a thermoplastic resin, and a mold assembly,
The mold assembly includes a fixed mold part, a movable mold part, a plug body, and plug body moving means for moving the plug body,
The mold assembly includes a cavity formed by clamping a fixed mold part and a movable mold part, a molten resin injection part opened in the cavity, and a molten resin injection part and resin plasticizing / melting means, A molten resin flow path connecting
The plug body is an injection foam molding method using an injection molding apparatus that can move in the cavity substantially parallel to the flow axis direction of the molten thermoplastic resin injected from the molten resin injection section by the operation of the plug body moving means. There,
(A) Before the injection of the molten thermoplastic resin into the cavity, the plug body is positioned at the forward end in the cavity by the plug body moving means,
(B) After plasticizing and melting the thermoplastic resin by resin plasticizing and melting means, dissolving the gas in the molten thermoplastic resin, and weighing the molten thermoplastic resin,
(C) It is weighed from the resin plasticizing / melting means into the cavity formed by clamping the fixed mold part and the movable mold part via the molten resin flow path and the molten resin injection part. Injecting molten thermoplastic resin
(D) Before the injection of the molten thermoplastic resin into the cavity, simultaneously with the start of the injection, or after the start of the injection, from the advance end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity Start the movement of the plug toward the reverse end,
(E) During the injection of the molten thermoplastic resin, the plug body is continuously moved toward the rearward end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity,
(F) completing the injection of the molten thermoplastic resin;
(G) Thereafter, the plug body is further moved toward the reverse end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity,
(H) The plug body is positioned at the rear end by the plug body moving means and / or the molten thermoplastic resin injected into the cavity, and then
(I) Cool and solidify the thermoplastic resin in the cavity, then
(J) Open the fixed mold part and the movable mold part and take out the foam molded product.
Comprising each step,
When the pressure of the molten thermoplastic resin in the cavity P _R, the pressure of the molten thermoplastic resin in the cavity starts foaming was P _E,
In the step (H), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Wherein in the step (I), by the state of P _R <P _E, foam injection molding method characterized by foaming the molten thermoplastic resin in the cavity. Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, in claim 14, characterized in that to suppress the foaming of molten thermoplastic resin in the cavity The injection foam molding method described. In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity The injection foam molding method according to claim 14, wherein foaming of the molten thermoplastic resin is suppressed. Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (I), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. The injection foam molding method according to claim 14, wherein a structure in which a foam layer is laminated is obtained. In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity Suppresses foaming of molten thermoplastic resin,
In the step (I), in place of P _R <P _E, a state of P _R > P _{E and} a state of P _R <P _E are repeated, and an unfoamed layer is formed in the depth direction of the foam molded product. The injection foam molding method according to claim 14, wherein a structure in which a foam layer is laminated is obtained. Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E The injection foam molding method according to claim 14, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity Suppresses foaming of molten thermoplastic resin,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E The injection foam molding method according to claim 14, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. Wherein step (E), in the step (F) and step (G), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 14 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. In the step (E), and <from the state of P _E P _R> P _R state of P _E, in the step (F) and step (G), by the state of P _R> P _E, the cavity Suppresses foaming of molten thermoplastic resin,
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 14 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. In the step (E) and the step (F), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E The injection foam molding method according to claim 14, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. In the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and in the step (F), the state of P _R > P _E is set, whereby the melt thermoplasticity in the cavity is obtained. Suppresses foaming of resin,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E The injection foam molding method according to claim 14, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. In the step (E) and the step (F), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 14 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. In the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and in the step (F), the state of P _R > P _E is set, whereby the melt thermoplasticity in the cavity is obtained. Suppresses foaming of resin,
Wherein in the step (G), by the state of P _R <P _E, by foaming molten thermoplastic resin in the cavity,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 14 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. Wherein step (E), in the step (F) and step (G), and the state of P _R <P _E,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E The injection foam molding method according to claim 14, wherein the molten thermoplastic resin in the cavity is foamed by setting the state as follows. Wherein step (E), in the step (F) and step (G), and the state of P _R <P _E,
In the step (H), instead of setting P _R > P _E , set P _R <P _E.
In the step (I), instead of setting P _R <P _E , P _R > P _E is set to suppress foaming of the molten thermoplastic resin in the cavity, and then P _R <P _E repeating the states of the state and the P _R> P _E, injection foam molding according to claim 14 where the unfoamed layer in the depth direction of the molded foam and the foam layer is characterized by obtaining the laminated structure Method. Wherein in the step (E), by the state of P _R> P _E, suppresses foaming of molten thermoplastic resin in the cavity,
Thereafter, through the step (I), the state of P _R <P _{E and} the state of P _R > P _E is repeated, and a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product. The injection foam molding method according to claim 14, which is obtained. In the step (E), from the state of P _R <P _{E to} the state of P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
Thereafter, through the step (I), the state of P _R <P _{E and} the state of P _R > P _E is repeated, and a structure in which an unfoamed layer and a foamed layer are laminated in the depth direction of the foamed molded product. The injection foam molding method according to claim 14, which is obtained. In the step (E) and the step (F), by setting P _R > P _E , the foaming of the molten thermoplastic resin in the cavity is suppressed,
In the step (G), from the state of P _R > P _E , the state of P _R <P _{E and} the state of P _R > P _E are repeated,
Furthermore, in the step (I), repeating the states of P _R <a P _E state and P _R> P _E, the depth direction of the foamed molded article unfoamed layer and foam layer are laminated The injection foam molding method according to claim 14, which is obtained. In the step (E), the state of P _R <P _E is changed to the state of P _R > P _E , and in the step (F), the state of P _R > P _E is set, whereby the thermoplastic resin in the cavity Suppresses foaming of
In the step (G), from the state of P _R > P _E , the state of P _R <P _{E and} the state of P _R > P _E are repeated,
Furthermore, in the step (I), repeating the states of P _R <a P _E state and P _R> P _E, the depth direction of the foamed molded article unfoamed layer and foam layer are laminated The injection foam molding method according to claim 14, which is obtained.

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