JP2002103390A - Nozzle for injection of pressurized fluid, molding method of molded article of thermoplastic resin and molding method of molded article of thermosetting resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle for injection of a pressurized fluid which can surely inject the pressurized fluid into a thermoplastic resin injected in a cavity and enables backward movement of a nozzle for injection of pressurized gas without any problem. SOLUTION: The nozzle 10 for injection of the pressurized fluid is devised for injecting the pressurized fluid into a molten resin injected in the cavity provided in a mold, and the nozzle is provided with a cooling means 20 for cooling the fore end portion 12 coming into contact with the molten resin injected in the cavity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for injection of a pressurized fluid, which is used in an injection molding apparatus for injection molding a beautiful molded product having a hollow portion and having no appearance of sink marks and warpage.
The present invention relates to a method for molding a molded article made of a thermoplastic resin using such a nozzle for injecting pressurized fluid, and a method for molding a molded article made of a thermosetting resin using the nozzle for injecting pressurized fluid.

[0002]

2. Description of the Related Art In molding a molten thermoplastic resin based on an injection molding method, the molten thermoplastic resin is injected into a cavity provided in a mold in order to obtain a beautiful molded product having no sink mark or warpage. Then, pressurized gas is injected into the molten thermoplastic resin in the cavity to form a hollow part in the thermoplastic resin, and the thermoplastic gas is released outside the system before the mold is opened. Japanese Patent Application Laid-open No. Sho 64-64
No. 14012 discloses this. Further, this patent publication also discloses a pressurized gas injection nozzle having a center hole for injecting a pressurized gas and having a check valve disposed at an outlet end of the center hole. Pressurized gas is injected into the molten thermoplastic within the cavity through the central hole. By arranging the check valve, the thermoplastic resin can be prevented from flowing back to the pressurized gas injection nozzle,
It is possible to prevent the pressurized gas in the hollow portion from flowing back to the pressurized gas injection nozzle.

A method of injecting a pressurized gas into a molten thermoplastic resin in a cavity by heating a nozzle tip portion including a check valve portion of a nozzle for pressurized gas injection by a heating device is disclosed in Japanese Patent Laid-Open Publication No. Hei 4 (Kokai). No. 31015. Japanese Patent Application Laid-Open No. 4-31016 discloses a method in which a nozzle tip of a nozzle for pressurized gas injection is covered with a molten resin injected into a cavity, and the nozzle tip is heated by heat of the molten resin.

Generally, when a pressurized gas is injected into a molten thermoplastic resin injected into a cavity, the tip of the nozzle for injection of the pressurized gas is heated to a temperature equal to or higher than the mold temperature. The holding facilitates the injection of the pressurized gas into the molten thermoplastic resin. Specifically, the temperature of the nozzle tip of the nozzle for pressurized gas injection varies depending on the thermoplastic resin used. In the case of polycarbonate resin, when the mold temperature is 80 ° C., 260 ° C. to 320 ° C. C. In the case of a polyacetal resin, when the mold temperature is 60 ° C., the temperature is 160 ° C. to 240 ° C. That is, the temperature at the nozzle tip is
The temperature is controlled to be higher than the mold temperature.

[0005] In injection molding of a thermoplastic resin, the thermoplastic resin is heated, melted and kneaded by a plasticizing device provided in the injection molding machine, injected into a cavity provided in a mold, and heated to the mold. Is moved to cool and solidify the molten thermoplastic resin to shape it. That is, as the thermoplastic resin cools, the viscosity of the thermoplastic resin increases and solidifies.

Accordingly, in order to easily and surely inject the pressurized gas into the molten thermoplastic resin injected into the cavity, the temperature of the nozzle tip of the pressurized gas injection nozzle must be controlled by changing the temperature of the nozzle. It is necessary to keep the temperature above the softening point temperature (T _MP ) of the thermoplastic resin near the tip.

[0007]

However, when the temperature of the nozzle tip of the nozzle for pressurized gas injection is kept at such a temperature, for example, a hollow formed inside the thermoplastic resin in the cavity is formed. When the pressurized gas injection nozzle is retracted to release the pressurized gas in the air to the atmosphere or to open the mold, the thermoplastic resin near the nozzle tip is used for pressurized gas injection. There is a problem that the nozzle is deformed with the retreat.

[0008] Such a problem occurs remarkably when the mold temperature is high and the softening point temperature of the thermoplastic resin is low. In order to solve such a problem, when injecting the pressurized gas, the temperature at the nozzle tip is set to a relatively high temperature, and before the nozzle for pressurized gas injection is retracted, the temperature at the nozzle tip is lowered, There is known a method of solidifying a thermoplastic resin in the vicinity of a portion to prevent deformation. Specifically, by stopping the heating of the nozzle tip, the heat from the nozzle tip is quickly transferred to the mold, and the temperature of the nozzle tip is reduced.

Therefore, this method can be applied only when there is a large difference between the mold temperature and the temperature of the nozzle tip at the time of pressurized gas injection. On the other hand, when the difference between the mold temperature and the temperature at the nozzle tip at the time of gas injection is small, or when the softening point temperature of the thermoplastic resin is low, the pressurization accompanying the retreat of the pressurized gas injection nozzle is performed in this method. It is difficult to prevent deformation of the thermoplastic resin near the gas injection nozzle.

In the injection molding of a thermosetting resin, the thermosetting resin is preheated by a heating device of an injection molding machine,
The resin is injected into a cavity provided in the mold, heat is transferred from the mold to the molten thermosetting resin, and heated to react and cure the thermosetting resin. Therefore, in order to easily and reliably inject the pressurized gas into the thermosetting resin injected into the cavity, the reaction and curing of the thermosetting resin during the injection of the pressurized gas are suppressed. There is a need.

In the prior art, it is possible to lower the temperature of the nozzle tip of the pressurized gas injection nozzle by heat transfer. However, by performing temperature control such as raising and lowering the temperature of the nozzle tip of the pressurized gas injection nozzle, the pressurized gas is reliably injected into the thermoplastic resin or thermosetting resin injected into the cavity. Further, a technique for retracting the pressurized gas injection nozzle without any problem has not been known as far as the present inventors have examined.

Accordingly, a first object of the present invention is to ensure that a pressurized fluid can be injected into a thermoplastic resin injected into a cavity, and that a pressurized gas injection nozzle can be provided without any problem. A pressurized fluid injection nozzle that can be retracted and reliably prevent deformation of the thermoplastic resin near the pressurized fluid injection nozzle accompanying the retreat of the pressurized fluid injection nozzle, and the pressurized fluid injection nozzle used. An object of the present invention is to provide a method for molding a molded article made of a thermoplastic resin.

[0013] A second object of the present invention is to ensure that a pressurized fluid can be injected into a thermosetting resin injected into a cavity. It is an object of the present invention to provide a pressurized fluid injection nozzle that can be retracted without any trouble, and a method of molding a molded article made of a thermosetting resin using the pressurized fluid injection nozzle.

[0014]

According to a first aspect of the present invention, there is provided a pressurized fluid injection nozzle for pressurizing molten resin injected into a cavity provided in a mold. A nozzle for pressurized fluid injection for injecting a fluid, wherein a cooling means for cooling a tip portion in contact with the molten resin injected into the cavity is provided.

In the pressurized fluid injection nozzle according to the present invention, the cooling means may be constituted by a pipe provided in the pressurized fluid injection nozzle and a cooling medium flowing in the pipe. The pipe is preferably disposed at or near the tip of the pressurized fluid injection nozzle,
The position is not limited to such a position as long as the temperature of the tip portion of the nozzle for pressurized fluid injection can be reliably controlled. In this case, it is preferable that the temperature of the cooling medium constituting the cooling means is controlled to a desired temperature by a temperature adjusting device provided outside. Examples of the cooling medium include a liquid or gas, specifically, water, pressurized water, oil, pressurized air, and pressurized nitrogen gas. The cooling medium may be appropriately selected based on the mold temperature and the required temperature of the pressurized fluid injection nozzle. The cooling medium may be always flowing in the pipe, or may be intermittently flowing. When the cooling medium is constantly supplied, the temperature of the tip portion of the pressurized fluid injection nozzle can be controlled by controlling the temperature and the flow rate of the cooling medium. On the other hand, when the cooling medium is intermittently supplied, the temperature of the cooling medium and the time for which the cooling medium is intermittently supplied may be controlled to control the temperature of the tip of the nozzle for pressurized fluid injection. it can. It is preferable that the temperature control is performed by feedback control based on a temperature measuring means provided in the pressurized fluid injection nozzle, but the temperature control is not limited to this.

Alternatively, in the pressurized fluid injection nozzle according to the present invention, the thermal conductivity of the material constituting the portion of the pressurized fluid injection nozzle that comes into contact with the mold may be such that the metal that is in contact with the pressurized fluid injection nozzle has Preferably, it is lower than the thermal conductivity of the material constituting the mold part. With such a configuration, the temperature of the pressurized fluid injection nozzle can be more reliably controlled. Specifically, as a combination of (material forming part of pressurized fluid injection nozzle in contact with mold) / (material forming part of mold in contact with pressurized fluid injection nozzle), (Bakelite : Thermal conductivity = 0.233 / carbon steel [0.5% carbon]: thermal conductivity = 53.5), (zirconia ceramics: thermal conductivity = 2.5 / carbon steel [0.
5% carbon]: thermal conductivity = 53.5), (titanium alloy: thermal conductivity = 29.3 / carbon steel [0.5% carbon]: thermal conductivity = 53.5). . The unit of the thermal conductivity is W / mk.

At the tip of the pressurized fluid injection nozzle, there is provided a backflow preventing means for preventing the molten resin from flowing into the pressurized fluid injection nozzle, specifically, for example, a check valve. Is desirable.

The resin in the nozzle for injecting pressurized fluid of the present invention may be a thermoplastic resin.

In order to achieve the above second object, it is preferable that the nozzle for pressurized fluid injection of the present invention including various forms is further provided with a heating means. In this case, a thermosetting resin can be used as the resin.

The heating means may be constituted by a pipe which constitutes the cooling means, which is provided in the nozzle for injecting the pressurized fluid, another pipe dedicated to the heating means, and a heat medium flowing through the pipe. it can. In this case, it is preferable that the temperature of the heat medium constituting the heating means is controlled to a desired temperature by a temperature adjusting device provided outside. And
In this case, the heat medium is preferably a liquid or gas, specifically, pressurized air, pressurized nitrogen gas, heated oil, or water. Alternatively, apart from the cooling means, a heating means such as a heater may be provided outside or inside the pressurized gas injection nozzle.

In the nozzle for injecting pressurized fluid according to the present invention, the pressurized fluid injected into the molten resin preferably comprises a pressurized gas, specifically, nitrogen gas, carbon dioxide gas, air And a gaseous substance at normal temperature such as helium gas, and among them, an inert gas such as nitrogen gas and helium gas is preferable. It is more preferable that the pressurized fluid to be injected is an inert pressurized fluid that does not cause burning due to adiabatic compression in the hollow portion of the molded product. When nitrogen gas is used, the pressurized fluid has a purity of 90% or more. It is desirable to use

In order to achieve the first object, the method for molding a molded article made of a thermoplastic resin according to the present invention comprises the steps of: injecting a molten thermoplastic resin into a cavity provided in a mold; Using a pressurized fluid injection nozzle provided with cooling means for cooling, injecting pressurized fluid from the tip of the pressurized fluid injection nozzle into the molten thermoplastic resin in the cavity, Cools thermoplastic resin
After solidification, the nozzle for pressurized fluid injection is retracted,
A method of molding a molded article made of a thermoplastic resin having a hollow portion, wherein a temperature of a tip portion of the pressure fluid injection nozzle in contact with the thermoplastic resin when the pressure fluid injection nozzle is retracted. By the operation of the cooling means,
The temperature is equal to or lower than the softening point temperature of the thermoplastic resin.

In the method for molding a molded article made of a thermoplastic resin, the temperature of the tip of the nozzle for injecting the pressurized fluid which is in contact with the thermoplastic resin when the nozzle for injecting the pressurized fluid is retracted is set to T (゜ C ), The softening point temperature of the thermoplastic resin is T
_MP (゜ C), T _RT (゜ C) and room temperature T
Is T _RT ≦ T ≦ (T _MP +10), preferably (T _MP −
30) ≦ T ≦ (T _MP− 10).

The nozzle for injecting pressurized fluid used in the method for molding a molded article made of the thermoplastic resin of the present invention is the nozzle for injecting pressurized fluid of the present invention. If desired, a heating means may be further provided.

In order to achieve the second object, the method for molding a molded article made of a thermosetting resin according to the present invention comprises the steps of: injecting a molten thermosetting resin into a cavity provided in a mold; A pressurized fluid injection nozzle provided with cooling / heating means for cooling and heating a portion is used, and a pressurized fluid is injected from the tip of the pressurized fluid injection nozzle into the molten thermosetting resin in the cavity. After the thermosetting resin in the cavity is cured and the pressurized fluid injection nozzle is retracted, a molded article made of the thermosetting resin in which the hollow portion is formed is formed. Before injecting the molten thermosetting resin into the cavity, the temperature of the tip portion of the pressurized fluid injection nozzle in contact with the molten thermosetting resin is set to a temperature lower than the reaction start temperature of the thermosetting resin by the cooling / heating means. And the molten hardening inside the cavity After injecting the pressurized fluid into the thermosetting resin, the temperature of the tip of the pressurized fluid injection nozzle in contact with the molten thermosetting resin is set to a temperature equal to or higher than the reaction start temperature of the thermosetting resin by the cooling / heating means. It is characterized by doing.

In the method of molding a molded article made of a thermosetting resin according to the present invention, the reaction start temperature of the thermosetting resin is set to T _CT
(゜ C), before injecting the molten thermosetting resin into the cavity, the temperature of the tip of the pressurized fluid injection nozzle in contact with the molten thermosetting resin is set to T ₁ (） C), and the molten thermosetting in the cavity is performed. The temperature of the tip of the pressurized fluid injection nozzle in contact with the molten thermosetting resin after the pressurized fluid is injected into the inside of the thermosetting resin is T ₂ (゜ C), and the decomposition temperature of the thermosetting resin is T _d (゜ C), when the room temperature is T _RT (゜ C), the temperature T ₁ is T
_RT ≦ T ₁ ≦ T _CT , preferably (T _CT −30) ≦ T ₁ ≦ (T
Satisfied _CT -10), the temperature T _{2 are, T CT ≦ T 2 ≦ T} d, preferably it is desirable to satisfy _{T CT ≦ T 2 ≦ (T} CT +30).

The pressurized fluid injection nozzle used in the method of molding a molded article made of the thermosetting resin of the present invention is the pressurized fluid injection nozzle of the present invention provided with a heating means.

The tip of the nozzle for injecting pressurized fluid may be located substantially on the surface of the mold constituting the cavity, or may be located within the cavity. In the former case, the tip of the nozzle for pressurized fluid injection is located outside the cavity. On the other hand, in the latter case, the tip of the pressurized fluid injection nozzle is located in the cavity.

The start of pressurized fluid injection from the tip of the pressurized fluid injection nozzle into the molten thermoplastic resin or the molten thermosetting resin in the cavity is determined by the time when the molten thermoplastic resin or the molten heat is injected into the cavity. It may be during injection of the curable resin, at the same time as the completion of the injection, or after the completion of the injection.

The amount of the molten thermoplastic resin or the molten thermosetting resin to be injected into the cavity may be an amount sufficient to completely fill the cavity or an amount sufficient to incompletely fill the cavity. There may be.

As the thermoplastic resin in the present invention, all of the commonly used thermoplastic resins can be used. Specifically, examples of the amorphous thermoplastic resin include styrene resins such as polystyrene resin, ABS resin, AES resin and AS resin; methacrylic resin; polycarbonate resin; modified PPE resin; and polyarylate resin. Examples of the crystalline thermoplastic resin include polyolefin resins such as polyethylene resin and polypropylene resin; polyamide 6, polyamide 66, and polyamide M.
Polyamide resins such as XD6; polyoxymethylene (polyacetal) resins; polyethylene terephthalate (P
ET) resin, polybutylene ethylene terephthalate (P
Polyester resins such as BT) resin; polyphenylene sulfide resin; polysulfone resin; polyether sulfone resin; polyetherimide resin; and polyamideimide resin. Further, a thermoplastic resin made of a polymer alloy material can be used. Here, the polymer alloy material is made of a blend of at least two kinds of thermoplastic resins, or a block copolymer or a graft copolymer in which at least two kinds of thermoplastic resins are chemically bonded. Here, a polystyrene resin as a thermoplastic resin constituting a polymer alloy material in which at least two kinds of thermoplastic resins are blended,
Styrene resins such as ABS resin, AES resin and AS resin, polyolefin resins such as polyethylene resin and polypropylene resin, methacrylic resin, polycarbonate resin, polyamide 6, polyamide 66, polyamide MX
Polyamide resin such as D6, modified PPE resin, polyester resin such as polybutylene terephthalate resin and polyethylene terephthalate resin, polyoxymethylene resin,
Examples include polysulfone resin, polyimide resin, polyphenylene sulfide resin, polyarylate resin, polyether sulfone resin, polyether ketone resin, polyether ether ketone resin, polyester carbonate resin, liquid crystal polymer, and elastomer. As a polymer alloy material obtained by blending two kinds of thermoplastic resins, a polymer alloy material of a polycarbonate resin and an ABS resin can be exemplified. Incidentally, such a combination of resins is referred to as polycarbonate resin / ABS resin. The same applies to the following. Further, as a polymer alloy material in which at least two kinds of thermoplastic resins are blended, polycarbonate resin / PET resin, polycarbonate resin / PBT resin, polycarbonate resin /
Polyamide resin, polycarbonate resin / PBT resin / PET resin, modified PPE resin / HIPS resin, modified P
PE resin / polyamide resin, modified PPE resin / PBT
Resin / PET resin, modified PPE resin / polyamide MXD
6 resin, polyoxymethylene resin / polyurethane resin,
Examples thereof include PBT resin / PET resin and polycarbonate resin / liquid crystal polymer. Also, at least 2
HIPS resin, ABS resin, AES resin, as a polymer alloy material composed of a block copolymer or a graft copolymer in which various kinds of thermoplastic resins are chemically bonded.
AAS resin can be exemplified.

In addition, stabilizers, ultraviolet absorbers, release agents, dyes and pigments can be added to the various thermoplastic resins described above, and glass beads, mica, kaolin,
An inorganic filler such as calcium carbonate or an organic filler can also be added. Further, those obtained by adding inorganic fibers to the various thermoplastic resins described above can also be used. As inorganic fiber, glass fiber, carbon fiber,
Examples include at least one material selected from the group consisting of wollastonite, aluminum borate whisker fiber, potassium titanate whisker fiber, basic magnesium sulfate whisker fiber, calcium silicate whisker fiber, and calcium sulfate whisker fiber.
The number of inorganic fibers contained in the thermoplastic resin is not limited to one, and two or more kinds of inorganic fibers may be contained in the thermoplastic resin.

As the thermosetting resin in the present invention, any resin can be used as long as it is a resin conventionally used in injection molding. That is, for example, phenol resin, urea resin, melamine resin, xylene resin, xylene / formaldehyde resin, diallyl phthalate resin, furan resin, ketone / formaldehyde resin, urea resin, aniline resin, alkyd resin, unsaturated polyester resin, epoxy resin Examples include the thermosetting resins.

In the method for molding a pressurized fluid injection nozzle or a molded article made of a thermoplastic resin according to the present invention, a cooling means for cooling a tip portion in contact with the molten resin injected into the cavity is provided. Therefore, when the pressurized gas injection nozzle is retracted, the tip of the pressurized gas injection nozzle can be set at a temperature equal to or lower than the softening point temperature T _MP of the thermoplastic resin. As a result, it is possible to reliably prevent the thermoplastic resin in the vicinity of the distal end of the pressurized gas injection nozzle from being deformed, and to reliably release the pressurized gas in the hollow portion to the atmosphere, for example. If desired, if a heating means is further provided, the temperature of the tip portion of the nozzle for injecting the pressurized gas when the molten thermoplastic resin is injected into the cavity is surely adjusted to the softening point temperature T of the thermoplastic resin. _The pressure can be set to _MP or more, and the pressurized fluid can be reliably injected into the thermoplastic resin injected into the cavity.

The pressurized fluid injection nozzle of the present invention is further provided with a heating means, and the pressurized fluid injection nozzle of the present invention is provided with a pressurized fluid injection method. Since the cooling / heating means is provided in the injection nozzle, it is possible to reliably control the reaction of the thermosetting resin in the vicinity of the tip portion of the pressurized fluid injection nozzle. That is,
Before injecting the molten thermosetting resin into the cavity, pressurized fluid injection nozzle part in contact with the molten thermosetting resin,
By setting the reaction start temperature _TCT of the thermosetting resin to be _lower than TCT, it is possible to suppress the reaction and curing of the molten thermosetting resin near the tip of the pressurized fluid injection nozzle immediately after being injected into the cavity. Thus, the pressurized fluid can be reliably injected into the molten thermosetting resin in the cavity. On the other hand, after injecting the pressurized fluid into the molten thermosetting resin in the cavity, the portion of the pressurized fluid injecting nozzle in contact with the molten thermosetting resin is moved to the thermosetting resin reaction start temperature T.
_By setting it to _CT or more, the reaction and curing of the molten thermosetting resin in the vicinity of the tip of the nozzle for pressurized fluid injection can be promoted, and the nozzle for pressurized gas injection can be reliably retracted. As a result, for example, the pressurized fluid in the hollow portion formed inside the thermosetting resin in the cavity can be reliably released to the atmosphere.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

Example 1 FIG. 1A is a schematic side view of the tip of the nozzle for injecting pressurized fluid of Example 1, and FIG. 1B is a schematic front view. FIG. 1C shows a schematic partial cross-sectional view of FIG. In FIG. 1 (C), illustration of piping is omitted. The pressurized fluid injection nozzle 10 is a pressurized fluid injection nozzle 10 for injecting a pressurized fluid into a molten resin injected into a cavity provided in a mold, and is injected into the cavity. Cooling means is provided for cooling the tip portion 11 in contact with the molten resin. The cooling means is, specifically, the tip portion 1
1, a pipe 20 spirally wound around the outer circumference of the end portion 11 and brazed to the outer circumference of the distal end portion 11, and a cooling medium made of oil flowing through the pipe 20. The cooling medium passes through the pipe 20 from the pipe inlet 20A and is discharged out of the system from the pipe outlet 20B. The discharged cooling medium is
A desired temperature is controlled by a temperature control device (not shown) installed outside.

As shown in a schematic partial cross-sectional view of FIG. 1C, a center hole 14 is provided at the tip 12 of the pressurized fluid injection nozzle 10, and a downstream end of the center hole 14 is provided. Are pressurized fluid discharge holes 13. At the upstream end of the center hole 14, a projection 15 is provided. Upstream of the convex portion 15,
A check valve is further provided. The check valve includes a check valve casing 16 and a metal ball 17 disposed in the check valve casing 16. Reference numeral 18 denotes a pressurized fluid flow path provided upstream of the check valve casing section 16 and flows through the pressurized fluid flow path 18 from the left hand direction to the right hand direction in FIG. And the pressurized fluid flows.
The pressurized fluid channel 18 is connected to a pressurized fluid source (not shown) via a pressurized fluid pipe 52. The pressurized fluid that has reached the check valve via the pressurized fluid flow path 18 moves the ball 17 in the right-hand direction in FIG. 1C, and discharges the check valve, the center hole 14, and the pressurized fluid. Discharged through the hole 13. When the molten resin flows back through the center hole 14 and reaches the check valve during injection of the molten resin, the ball 17 is urged by the molten resin in the left-hand direction in FIG. It is pressed against the left wall of the part 16. as a result,
The check valve is closed, and the check valve can prevent the backflow of the molten resin or the like.

FIG. 2 schematically shows a state in which the nozzle for pressurized fluid injection is provided in a mold attached to an injection molding apparatus. As shown in FIG. 2, the mold includes a movable mold section 42 and a fixed mold section 46. The pressurized fluid injection nozzle 10 can be arranged, for example, in the movable mold part 42. The pressurized fluid injection nozzle 10 is
Reciprocation (movement in the vertical direction in FIG. 2) by the moving means 50 composed of a piston, a cylinder, and the like attached to the robot
Can be made to. One end of the pressurized fluid pipe 52 is attached to the pressurized fluid channel 18 of the gas injection nozzle 10, and the other end is attached to a pressurized fluid source (not shown). still,
Reference numeral 40 is an injection cylinder of the injection molding apparatus, reference numeral 48 is a cavity provided in a mold, and reference numeral 60 is a molten resin.

FIGS. 3A and 3B are a side view and a front view, respectively, of a part of a modified example of the pressurized fluid injection nozzle of the first embodiment. The nozzle for pressurized fluid injection shown in FIG.
Is different from the nozzle for pressurized fluid injection shown in (1) in that the cooling pipe is brazed to a sleeve 21 attached to the distal end portion 11 so that the pipe 20 can be removed from the distal end portion 11. On the point.

FIGS. 4A and 4B also show a schematic cross-sectional view and a front view of a part of a modified example of the pressurized fluid injection nozzle of the first embodiment. The nozzle for pressurized fluid injection shown in FIG. 4 differs from the nozzle for pressurized fluid injection shown in FIG. 1 in that a sleeve made of a heat insulating member 22 is provided so as to surround the pipe 20. is there. Such a heat insulating member 2
By disposing 2, the heat transfer from the mold to the pressurized fluid injection nozzle 10 can be suppressed. That is,
In the pressurized fluid injection nozzle shown in FIG. 4, a material constituting the portion of the pressurized fluid injection nozzle that comes into contact with the mold (here, a material constituting the heat insulating member 22, specifically, The thermal conductivity (2.5 W / m · K) of the zirconia ceramic is determined by the material (specifically, for example,
Thermal conductivity (53.5 W / m) of carbon steel [0.5% carbon]
・ Lower than K).

FIG. 5 also shows a schematic side view of a part of a modified example of the pressurized fluid injection nozzle of the first embodiment. The nozzle for pressurized fluid injection shown in FIG. 5 is different from the nozzle for pressurized fluid injection shown in FIG. 1 in that the pipe 20 is arranged substantially parallel to the axis of the distal end portion.

FIG. 6 also shows a schematic side view of a part of a modification of the pressurized fluid injection nozzle of the first embodiment. The nozzle for pressurized fluid injection shown in FIG. 6 is different from the nozzle for pressurized fluid injection shown in FIG.
0 is provided. In FIG. 6, illustration of the pipe inlet 20A and the pipe outlet 20B is omitted.

In the pressurized fluid injection nozzle shown in FIGS. 1 to 6, the temperature at the tip of the pressurized fluid injection nozzle is controlled in order to control the flow rate or intermittent flow of the cooling medium. Although a temperature sensor is provided as a means for measuring the temperature, the illustration of the temperature sensor is omitted. Also, as shown in FIG. 6, an electric heater can be provided in the pressurized fluid injection nozzle 10 shown in FIGS.

Example 2 Example 2 relates to a method for molding a molded article made of the thermoplastic resin of the present invention. In Example 2, the pressurized fluid injection nozzle 10 shown in FIG. 6 was used.

Then, the temperature of the mold was adjusted to 120 ° C. by a pressurized water mold temperature controller. At the start of the injection molding, cooling oil as a cooling medium is not circulated in the pipe 20, and the temperature of the distal end portion 11 of the nozzle 10 for pressurized fluid injection is raised to 280 ° C. by the heating means constituted by the electric heater 30. Adjusted.

Then, a polycarbonate resin (Mitsubishi Engineering Plastics Co., Ltd., trade name: Iupilon S3000R), which is a thermoplastic resin, is melted and kneaded at 280 ° C. using a thermoplastic resin injection molding machine, and then an injection pressure of 7 is applied. 0.8 × 10 ⁷ Pa (800 kgf / cm ² -G)
An amount sufficient to fill the cavity 48 with about 80% was injected into the cavity 48 (see the schematic diagram of FIG. 7). still,
The softening point temperature T _MP of the polycarbonate resin used is 16
0 ゜ C. 7 to 9, the pipe 20 and the electric heater 30 are conceptually shown. Also, reference number 4
Reference numeral 4 denotes a gas injection section 44 provided in the movable mold section 42, and opens toward a cavity 48 formed in the mold. When the pressurized fluid injection nozzle 10 is moved in the right-hand direction in FIG. 7 by the moving means 50, the tip 12 of the pressurized fluid injection nozzle 10 comes into close contact with the gas injection section 44 and is injected into the cavity 48 of the mold. Molten resin 60
It can be prevented from flowing out of the gap between the movable mold part 2 and the movable mold part 42 to the outside.

After 3 seconds from the start of injection, the injection operation is completed.
Then, after a lapse of 0.2 seconds, the pressurized fluid injection nozzle 10
To pressurized fluid (compressed nitrogen gas, pressure 3 × 10 ⁶
Pa) was injected into the molten thermoplastic resin 60 in the cavity 48 (see the schematic diagram of FIG. 8). Thereby, the hollow portion 62 is formed inside the molten thermoplastic resin in the cavity 48. After the injection of the pressurized fluid is completed, the pressure of the pressurized fluid inside the thermoplastic resin 60 in the cavity 48 is maintained for 30 seconds. did. 10 seconds before releasing the pressurized fluid in the hollow portion 62 to the atmosphere, the operation of the heating means is stopped, and
The cooling oil of ゜ C was circulated in the pipe 20 to cool the distal end portion 11 of the pressurized fluid injection nozzle 10. According to actual measurements,
The temperature of the tip portion 11 became approximately 45 ° C. Tip 1
After the cooling of 1, the pressurized fluid injection nozzle 10 is moved to the moving means 50.
To release the pressurized fluid in the hollow portion 62 to the atmosphere (see the schematic diagram of FIG. 9).

When the pressurized fluid injection nozzle 10 is retracted by the moving means 50 after the cooling of the distal end portion 11, the thermoplastic resin near the distal end portion 11 of the pressurized fluid injection nozzle is sufficiently solidified, No deformation occurred in the molded product.

(Comparative Example 1) The temperature of a mold was adjusted to 120 ° C by a pressurized water mold temperature controller. At the start of injection molding,
The temperature of the distal end portion 11 of the pressurized fluid injection nozzle 10 was adjusted to 280 ° C. by a heating means including an electric heater 30 without circulating cooling oil as a cooling medium in the pipe 20.

Using the same thermoplastic resin as in Example 2, injection molding was performed under the same injection molding conditions as in Example 2. However, release the pressurized fluid in the hollow part to the atmosphere.
Before 0 seconds, only the operation of the heating means was stopped, and the cooling oil was not circulated in the pipe 20. According to actual measurement, the temperature of the tip portion 11 of the nozzle 10 for pressurized fluid injection is about 18
It was 0 ° C. Thereafter, the pressurized fluid injection nozzle 10 was moved backward by the moving means 50, and the pressurized fluid in the hollow portion was released to the atmosphere.

The pressurized fluid injection nozzle 10 is moved by the moving means 50.
When retracted, the thermoplastic resin near the distal end portion 11 of the nozzle for pressurized fluid injection is not sufficiently solidified, the molded product is deformed, and the release of the pressurized fluid to the atmosphere is poor. Was.

Example 3 Example 3 relates to a method for molding a molded article made of the thermosetting resin of the present invention. In Example 3, the pressurized fluid injection nozzle 10 shown in FIG. 6 was used.

Using a cartridge heater, the mold
The temperature was adjusted to 80 ° C. Then, cooling oil whose temperature was controlled at 30 ° C. was circulated in the pipe 20. The temperature (T ₁ ) of the distal end portion 11 of the pressurized fluid injection nozzle 10 was about 70 ° C. in actual measurement.

Then, a phenol resin (Fudolite, a product of Fudo Co., Ltd.), which is a thermosetting resin, is preheated to 90 ° C. by a thermosetting resin injection molding machine, and the temperature is adjusted to 180 ° C. Injection pressure 1.18 × 10 ⁸ Pa (1200 kgf / cm ² -G) in the cavity 48 of the mold
Was injected into the cavity 48 so as to fill the cavity 48 with about 80%. The reaction start temperature T _CT of the phenol resin used was 150 ° C.

The injection operation was stopped 6.0 seconds after the start of injection, and at the same time, 7.8 × 1
The compressed nitrogen gas ^{0 6 Pa (80kgf / cm 2} -G) and injected into the molten thermoplastic resin in the cavity 48.
Then, immediately, the circulation of the cooling oil in the pipe 20 was stopped, and the heater 30 was simultaneously operated. Then, the temperature T ₂ of the tip portion 11 of the pressurized fluid injection nozzle 10 is 1
After the temperature reached 80 ° C., the temperature was maintained for 20 seconds. After that, the operation of the heater 30 was stopped, and after 10 seconds, the pressurized fluid injection nozzle 10 was moved backward by the moving means 50 to release the pressurized fluid in the hollow portion to the atmosphere.

A hollow part penetrating through the thick part is formed in the obtained molded product, and the pressurized fluid is reliably injected into the molten thermosetting resin in the cavity. The nozzle 10 has fulfilled its function sufficiently.

Comparative Example 2 Injection molding was performed under the same conditions as in Example 3 using the same mold as in Example 3 and using a pressurized fluid injection nozzle without cooling means. As a result, the temperature of the tip of the pressurized fluid injection nozzle was also 180 ° C., which was the same as the mold temperature before the start of the injection of the thermosetting resin. Therefore, an attempt was made to inject the pressurized fluid from the pressurized fluid injection nozzle into the molten thermosetting resin injected into the cavity. Pressurized fluid could not be injected from the tip.

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. The structure of the nozzle for pressurized fluid injection described in the embodiment,
The structure of the mold, the resin used, and the injection molding conditions are examples, and can be changed as appropriate. In the embodiment, the nozzle for pressurized fluid injection whose tip is generally located on the surface of the mold constituting the cavity is used, but instead, the nozzle for pressurized fluid injection whose tip is located in the cavity is used. You may. In this case, since the distal end portion of the nozzle for pressurized fluid injection is located in the cavity, it is desirable that the pipe 20 has a structure that does not contact the molten resin in the cavity.

[0060]

In the method for molding a pressurized fluid injection nozzle or a molded article made of a thermoplastic resin according to the present invention, when the pressurized gas injection nozzle is retracted, the tip of the pressurized gas injection nozzle is moved backward. Since the temperature of the portion can be set to a temperature equal to or lower than the softening point temperature of the thermoplastic resin, the thermoplastic resin in the vicinity of the tip of the nozzle for pressurized gas injection can be reliably prevented from being deformed. The gas can be reliably released to the atmosphere.

By providing the pressurized fluid injection nozzle of the present invention with heating means, the molten thermosetting resin injected into the cavity near the tip of the pressurized fluid injection nozzle can be cured. It can be easily suppressed and controlled.

Further, in the method of molding a molded article made of a thermosetting resin according to the present invention, it is possible to surely suppress and control the reaction of the thermosetting resin near the tip of the nozzle for pressurized fluid injection. Thus, the pressurized fluid can be reliably injected into the molten thermosetting resin in the cavity. On the other hand, after injecting the pressurized fluid into the melted thermosetting resin in the cavity, the portion of the nozzle for pressurized fluid injection that is in contact with the melted thermosetting resin is set to a temperature equal to or higher than the thermosetting resin reaction start temperature. By doing so, the reaction and curing of the molten thermosetting resin in the vicinity of the tip of the nozzle for injecting pressurized fluid can be promoted, and the nozzle for injecting pressurized gas can be reliably retracted.
As a result, for example, the pressurized fluid in the hollow portion formed inside the thermosetting resin in the cavity can be reliably released to the atmosphere.

As a result, regardless of whether a thermoplastic resin or a thermosetting resin is used, a molded article having a hollow portion and a beautiful appearance without sink marks and warpage. Can be reliably injection molded.

[Brief description of the drawings]

FIG. 1 is a schematic side view, a schematic front view, and a schematic partial cross-sectional view of a distal end portion of a pressurized fluid injection nozzle according to a first embodiment.

FIG. 2 is a diagram schematically illustrating a state in which a nozzle for pressurized fluid injection is provided in a mold attached to an injection molding apparatus.

FIG. 3 is a schematic side view and a schematic front view of a distal end portion in a modified example of the pressurized fluid injection nozzle according to the first embodiment.

FIG. 4 is a schematic side view and a schematic front view of a distal end portion in another modified example of the pressurized fluid injection nozzle according to the first embodiment.

FIGS. 5A and 5B are a schematic side view and a schematic front view of a distal end portion of still another modified example of the pressurized fluid injection nozzle according to the first embodiment. FIGS.

FIG. 6 is a schematic side view and a schematic front view of a distal end portion in still another modified example of the pressurized fluid injection nozzle according to the first embodiment.

FIG. 7 is a schematic partial cross-sectional view showing a state of a distal end portion of a pressurized fluid injection nozzle when a molten thermoplastic resin is injected into a cavity in Example 2.

FIG. 8 is a schematic partial cross-sectional view showing a state of a distal end portion of a pressurized fluid injection nozzle when a pressurized fluid is injected into a molten thermoplastic resin in a cavity in Example 2.

FIG. 9 is a view schematically showing a state in which the pressurized fluid injection nozzle is moved backward by the moving means to release the pressurized fluid in the hollow portion to the atmosphere in the second embodiment.

[Explanation of symbols]

10 ... Pressurized fluid injection nozzle, 11 ... Tip, 12 ... Tip, 13 ... Pressurized fluid discharge hole, 14
... Center hole, 15 ... Convex part, 16 ... Check valve casing part, 17 ... Ball, 18 ... Pressurized fluid flow path, 20 ... Piping, 20A ... Piping Entrance, 20B
... pipe outlet, 21 ... sleeve, 22 ... heat insulating member, 30 ... heating means, 40 ... injection cylinder, 42 ... movable mold part, 44 ... gas injection Department,
46 ... fixed mold part, 48 ... cavity, 50
..Movement means, 52 ... pipe for pressurized fluid, 60 ...
Molten resin, 62 hollow part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Imaizumi 5-6-2, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Center of Mitsubishi Engineering-Plastics Corporation (72) Inventor Kazuaki Ochiai 5 Higashi-Yawata, Hiratsuka-shi, Kanagawa 6-6-2 F-term in Mitsubishi Engineering-Plastics Corporation Technical Center 4F033 AA00 BA03 CA04 DA01 EA01 HA02 HA05 LA13 NA01 4F202 AA03 AA13 AA36 AG07 AJ12 AK02 AM34 AM35 AR06 CA11 CD27 CK06 CK17 CN05 4F206 AA03AA AG07 AJ12 AK02 AM34 AM35 AR067 JA05 JL02 JN14 JN27 JQ81

Claims (14)

[Claims] 1. A pressurized fluid injection nozzle for injecting a pressurized fluid into a molten resin injected into a cavity provided in a mold, the nozzle being in contact with the molten resin injected into the cavity. A nozzle for pressurized fluid injection, wherein a cooling means for cooling a tip portion is provided. 2. The pressurized fluid injection device according to claim 1, wherein the cooling means comprises a pipe disposed on the nozzle for pressurized fluid injection, and a cooling medium flowing in the pipe. Nozzle. 3. The nozzle for pressurized fluid injection according to claim 2, wherein the cooling medium constituting the cooling means is controlled to a desired temperature by a temperature controller installed outside. 4. The pressurized fluid injection nozzle according to claim 2, wherein the cooling medium is a liquid or a gas. 5. The thermal conductivity of the material forming the portion of the pressurized fluid injection nozzle that comes into contact with the mold is based on the thermal conductivity of the material forming the portion of the mold that comes into contact with the pressurized fluid injection nozzle. The nozzle for pressurized fluid injection according to claim 1, wherein the pressure is also low. 6. A backflow preventing means for preventing a molten resin from flowing into the pressurized fluid injection nozzle is provided at a tip of the pressurized fluid injection nozzle.
5. The nozzle for pressurized fluid injection according to 4. 7. The nozzle according to claim 1, wherein the resin is made of a thermoplastic resin. 8. The pressurized fluid injection nozzle according to claim 1, further comprising a heating means. 9. The nozzle according to claim 8, wherein the resin is a thermosetting resin. 10. The pressurized fluid injection nozzle according to claim 1, wherein the pressurized fluid injected into the molten resin comprises a pressurized gas. 11. After the molten thermoplastic resin is injected into a cavity provided in a mold, a pressurized fluid injection nozzle provided with a cooling means for cooling a tip portion is used to melt the molten resin in the cavity. A pressurized fluid is injected from the tip of the pressurized fluid injection nozzle into the thermoplastic resin, and the thermoplastic resin in the cavity is cooled and solidified, and then the pressurized fluid injection nozzle is retracted. A method for molding a molded article made of a thermoplastic resin having a portion formed therein, comprising: controlling a temperature of a tip portion of the pressurized fluid injection nozzle in contact with the thermoplastic resin when the pressurized fluid injection nozzle is retracted. A method for forming a molded article made of a thermoplastic resin, wherein the temperature is generally set to a temperature equal to or lower than a softening point temperature of the plastic resin by an operation of a cooling means. 12. When the nozzle for injecting pressurized fluid is retracted, the temperature of the tip of the nozzle for injecting pressurized fluid which is in contact with the thermoplastic resin is T (゜ C), and the softening point temperature of the thermoplastic resin is T (゜ C). _The temperature T satisfies T _RT ≦ T ≦ (T _MP +10), where _MP (ΔC) and room temperature are T _RT (ΔC). Molding method for molded articles. 13. A pressurized fluid injection nozzle provided with cooling / heating means for cooling and heating a tip portion after injecting a molten thermosetting resin into a cavity provided in a mold. Injecting pressurized fluid from the tip of the pressurized fluid injection nozzle into the molten thermosetting resin in the cavity,
After curing the thermosetting resin in the cavity, the pressurized fluid injection nozzle is retracted, thereby forming a molded article made of the thermosetting resin having a hollow portion formed therein. Before injecting the molten thermosetting resin into the cavity, the temperature of the tip of the pressurized fluid injection nozzle that is in contact with the molten thermosetting resin is set to be lower than the reaction start temperature of the thermosetting resin by cooling / heating means. After injecting the pressurized fluid into the molten thermosetting resin, the temperature of the tip of the nozzle for injecting the pressurized fluid that is in contact with the molten thermosetting resin is adjusted by the cooling / heating means to react the thermosetting resin. A method for molding a molded article made of a thermosetting resin, wherein the molding temperature is not lower than a starting temperature. 14. A thermosetting resin having a reaction start temperature of T _CT (° C.), and a tip portion of a pressurized fluid injection nozzle in contact with the molten thermosetting resin before injecting the molten thermosetting resin into the cavity. Is T ₁ (゜ C), and the temperature of the tip of the pressurized fluid injection nozzle in contact with the molten thermosetting resin after the pressurized fluid is injected into the molten thermosetting resin in the cavity is When T ₂ (2C), the decomposition temperature of the thermosetting resin is T _d (゜ C), and the room temperature is T _RT (゜ C), the temperature T ₁ is T T
_{14. The} method for molding a molded article made of a thermosetting resin according to claim 13, wherein _RT ≦ T ₁ ≦ T _CT is satisfied, and the temperature T ₂ satisfies T _CT ≦ T ₂ ≦ T _d .