JP2001252947A - Mold and method for molding resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for molding resin provided with a pressure medium injection nozzle capable of easily controlling the opening diameter, shape and volume of each of a plurality of independent blind cavities, and capable of easily molding a resin molded object having lightweight properties, rigidity, heat insulating properties and sound absorbing and insulating characteristics, free from a sink and warpage and excellent in appearance quality, and to provide a resin molding method using this mold. SOLUTION: The mold for molding a resin has the pressure medium injection nozzles 5 for forming blind cavities a fixed mold 2 and a movable mold 1 both of which prescribe a cavity 4. The nozzles 5 and a raw material injection port 6 are provided to the surface forming wall 2a of the fixed mold 2. The movable mold 1 has a rear surface forming wall part 1a and is displaceable in a pressure medium injection direction. The nozzles 5 have pressure medium jet orifices and the part or whole coming into contact with a raw material resin of the nozzles 5 comprises a resin. When the resin is molded, a pressure medium is injected from the nozzles 5 during the flowable period of the molten resin to form blind cavities having opening parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding die and a resin molding method using the same, and more particularly, to a method for easily forming a starting point of a pressure medium and promoting formation of a blind cavity. The present invention relates to a resin molding die capable of controlling the shape and volume of a blind cavity and a resin molding method using the same. The resin molded article molded by using the resin molding die of the present invention has high rigidity and light weight, and also has functions of sound absorption and sound insulation, absorption of external energy, heat insulation, and the like. It is suitably used for interior materials and the like.

[0002]

2. Description of the Related Art Hitherto, a method of laminating a honeycomb-shaped molded body and a flat plate and a method of erecting a reinforcing rib have been used for molding a resin molded body having a cavity, having high rigidity and light weight. I have. However, in the method of laminating a honeycomb formed body and a flat plate, the laminating step of manufacturing the honeycomb formed body requires a lot of time, and the stacked layers are easily peeled from each other and have poor reliability. There was a problem that it was difficult to partially improve the rigidity of the molded body. In addition, the method of erecting the reinforcing ribs has problems such as complicated mold processing and a step of closing the opening surface, and has a rigidity without requiring a post-process such as lamination in a short process. In addition, there has been a demand for a lightweight resin molded body.

In order to solve these problems, a method has been proposed in which a pressure medium is injected to form a cavity in a resin molded body at a time during heat molding in which the raw material resin has fluidity. However, since this method is intended to prevent the sink on the surface of the molded body or to increase the reinforcement by controlling the shape and volume of the cavity, the position of the cavity is limited by the shape of the mold, and is arbitrary. It was difficult to form an independent cavity at the site. In addition, there is a problem in that the rib thickness, shape, volume, and the like cannot be controlled even if the formed cavities communicate with each other or form independent cavities.

For example, in Japanese Patent Publication No. 57-14968, after filling a molten resin less than the cavity volume of an injection mold, a pressurized gas is injected from the same port to fill the cavity and form a blind cavity. A method has been proposed. However, since the pressure medium injection port is the same as the resin injection port, there is a problem that the size, volume, and existence density of the formed blind cavity cannot be easily controlled.

Japanese Patent Application Laid-Open No. Hei 6-134828 proposes a method of molding a blind cavity by injecting a pressure medium during injection molding as a method using a rib structure. Because of the intended nozzle structure, it is not possible to form a large number of independent blind cavities by controlling the shape in the thin part of the resin. Also, since the check valve is provided in the pressure medium injection part (nozzle), the nozzle shape Is limited, a predetermined blind cavity cannot be formed in the molded body, and further, since a check valve is provided at the nozzle tip, the nozzle tip becomes large, so that a large number of nozzles cannot be set per unit area, and the blind cavity body There is a problem that it is difficult to change the arrangement density and to control the light weight and rigidity.

Further, in Japanese Patent Application Laid-Open No. Hei 6-155556, in addition to the problem that occurs in the method disclosed in Japanese Patent Application Laid-Open No. Hei 6-134828, since the heating device is provided at the nozzle tip, And the number of nozzles per unit area is limited.

Furthermore, in JP-A-8-276452, since the same nozzle is used as both a resin cylinder nozzle and a pressure medium injection nozzle, the shape of the pressure medium injection nozzle cannot be changed to control the blind cavity shape. There was a problem.

As a technique capable of solving such a conventional problem, the inventors of the present invention have disclosed an unpublished Japanese Patent Application No. Hei 11-115, filed at the time of filing the present application.
No. 119250, Japanese Patent Application No. 11-116256, Japanese Patent Application No. 11-190888 and Japanese Patent Application No. 11-224426, using a specific cavity capable of changing the internal volume, and separately setting the resin inlet and the gas inlet independently. By setting the cavity receiving layer, etc., the shape, arrangement, volume, number and opening area of the cavities can be controlled for each cavity, and it is possible to reduce the weight and control the rigidity. We have already proposed a molding die and a molding method that hardly cause warpage.

[0009]

However, the inventors of the present invention have further studied the technology related to the above application and found that there is room for improvement as described below. That is, when forming the blind cavity in the resin molded body, during or after filling of the molten raw material resin, or during or after displacement of the mold, if the raw material resin is strongly adhered to the pressure medium injection nozzle, the raw material from the nozzle It has been found that dents, which serve as starting points for the pressure medium injected into the resin, are unlikely to occur, and that it is difficult to form a blind cavity by controlling the shape and volume.

The present invention has been made in view of such findings, and an object of the present invention is to provide a pressure medium injection nozzle capable of easily controlling the opening diameter, shape and volume of a plurality of independent blind cavities. A resin molding die installed, which is lightweight, has rigidity, heat insulating properties and sound absorbing / sound insulating properties, and is easy to mold a resin molded body having excellent appearance quality without sink marks and warpage; and An object of the present invention is to provide a resin molding method using the same.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, at least a predetermined portion of a pressure medium injection nozzle installed in a resin molding die in contact with a raw material resin is made of resin. It has been found that the above objects can be achieved by coating or forming, and the present invention has been completed.

That is, the resin molding die of the present invention is provided with a pressure medium injection nozzle provided with an opening in the surface of the resin molded body and forming a plurality of independent blind cavities extending in the back direction. A mold having a fixed mold and a movable mold that define a cavity, wherein the fixed mold has a wall that forms a surface of the resin molded body, and the surface forming wall has The pressure medium injection nozzle and the raw material resin injection port are provided,
The movable mold has a back surface forming wall portion facing the front surface forming wall portion, and is displaceable in substantially the same direction as the pressure medium injection direction through the pressure medium injection nozzle. Has a pressure medium ejection port, and a portion in contact with the raw material resin filled in the cavity is coated with a resin, or is entirely formed of this resin.

In a preferred embodiment of the resin molding die of the present invention, the resin covering or constituting the pressure medium injection nozzle covers or constitutes the periphery of the pressure medium ejection port. I do.

Further, a preferred embodiment of the resin molding die of the present invention is a resin molding die provided with the above-mentioned pressure medium injection nozzle having the above-mentioned pressure medium injection port on a side surface, wherein the pressure extending in the axial direction of the nozzle is provided. It has a medium main passage and a branch that intersects the main passage, and the tip of the branch located on the outer peripheral surface of the pressure medium injection nozzle has the pressure medium ejection port, and the cavity side from the pressure medium ejection port is the resin. Characterized by being covered or constituted by

Further, a method of molding a resin molded article of the present invention is a resin molding method using the above resin molding die,
During or after the filling of the molten resin into the cavity, or during or after the displacement of the movable mold, the pressure medium is injected into the pressure medium injection nozzle while the molten resin is fluid. From the melted resin to form a blind cavity having an opening in the obtained resin molded product.

[0016]

In the resin molding die of the present invention, the portion of the pressure medium injection nozzle which is in contact with the raw material resin is coated or formed with the resin. Therefore, when molding a resin molded body using this mold, the raw material resin is appropriately brought into close contact with the tip of the nozzle, and when the pressure medium is injected, this raw material resin is quickly dissociated from the nozzle, and a desired blind cavity is formed. Can be easily formed. Further, in a preferred embodiment of the resin molding die of the present invention, the periphery of the pressure medium ejection port of the pressure medium injection nozzle is covered or configured with the above resin. Therefore, when molding the resin molded body, the opening diameter of the blind cavity to be formed can be controlled by appropriately changing the coating amount of the resin and the like.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a resin molding die according to the present invention will be described in detail with reference to the drawings. As mentioned above,
The resin molding die of the present invention is a die provided with a pressure medium injection nozzle for forming a plurality of independent blind cavities extending in the back surface direction having an opening on the surface of the resin molded body, The nozzle has a pressure medium ejection port, and at least a portion in contact with the raw material resin in the cavity is covered or configured with a resin.

Here, an example of the resin molding die of the present invention will be described. 1 and 2 are cross-sectional views showing an example of the resin molding die. 1 shows a state before the material resin is injected, and FIG. 2 shows a state in which the material resin is injected into the cavity and a pressure medium (such as gas) is injected to form a blind cavity. .

In FIGS. 1 and 2, this resin molding die is an example of a backside forming die 1 which is an example of a movable die, and an example of a fixed die which can be displaced in a direction substantially the same as the injection direction of the pressure medium. And a surface forming wall 2a which constitutes a convex portion of the surface forming mold 2 is defined by a concave portion of the rear surface forming mold 1 and a convex portion of the surface forming mold 2. Cavity 4
A pressure medium injection nozzle 5 for injecting a pressure medium into the nozzle and a resin injection port 6 for injecting a raw material resin into the cavity 4 are separately provided. In addition, the back surface forming mold 1 has a back surface forming wall portion 2a facing the front surface forming wall portion 2a. Further, the nozzle 5 is connected to a gas cylinder 7 (pressure medium), a pressure adjusting valve 8, a control valve 9 via a gas chamber 3 (pressure medium chamber).
And a pressure medium supply system constituted by the heating device 10. Furthermore, the resin injection port 6 penetrates the center of the surface forming mold 2 and is connected to a raw material resin supply system (not shown) outside the mold. In order to control the shape and volume of the blind cavity 11, the diameter of the nozzle 5 and the pressure medium main passage 13 extending in the axial direction of the nozzle, the installation position of the nozzle 5 (concave, flush,
Or protruding shape) and the tip shape of the nozzle 5 are appropriately changed.
The resin molded body can be molded using a mold that can be combined, and it is particularly desirable to use a mold that can use an injection molding method or an injection compression molding method.

The resin constituting the portion (rib-equivalent portion) other than the blind cavity 11 in the resin molded body 12, that is, the raw material resin constituting the resin molded body, may be any resin which has fluidity during heat molding. Any of a thermoplastic resin and a thermosetting resin can be used. In particular, it is preferable to use a thermoplastic resin which can easily adjust the viscosity of the resin by heating and can easily set the formation time of a blind cavity having an opening.

When a thermoplastic resin is used, the time for forming a blind cavity can be easily set. Therefore, a thermoplastic resin generally used in general injection molding, injection compression molding, compression molding, extrusion molding, stamping molding and the like is used. Yes, specifically, olefinic resins such as polyethylene and polypropylene,
Acrylic resins such as acrylonitrile, polystyrene resins such as ABS and polystyrene, polyamide resins, saturated polyester resins such as polycarbonate, PBT, PET, polyacetal, polyether sulfone, polysulfone, polyphenylene oxide, polyphenylene sulfide, polyether imide, and fragrance Group polyesters and vinyl resins, or polymer alloys thereof.

On the other hand, when a thermosetting resin is used, the curability can be adjusted by selecting the type of catalyst, the amount of catalyst, the heating temperature, and the like. These thermoplastic resins and thermosetting resins include talc, glass beads, silicon oxide, coloring pigments, metal powder, calcium carbonate, glass fibers, polyamide fibers, carbon fibers, light stabilizers, lubricants, antistatic agents. ,
Various additives such as a filler such as an antioxidant and a fiber reinforcing agent can be appropriately added.

Here, the blind cavity 11 means a cavity in the resin molded body 12 that does not penetrate between the front surface and the back surface. In addition, the blind cavities are not in contact with each other, and each form an independent space. Further, the blind cavity 11 typically extends and expands from the surface on which the opening is present to the rear surface opposite thereto, and is typically a circle, an ellipsoid, a eggplant, or a naked bulb. It has the shape of a hole in a mold. In the present specification, the surface of the blind cavity 11 having an opening is referred to as a “front surface”. However, there is no essential difference, and for convenience of explanation, the “front surface” and the “back surface” It goes without saying that even if they are interchanged with each other, they are included in the scope of the present invention.

The diameters of the pressure medium injection nozzle 5, the pressure medium injection port 15 and the pressure medium main passage 13, the protrusion of the pressure medium injection nozzle, the shape and arrangement of the pressure medium chamber 3, the tip of the pressure medium injection nozzle, and the gas Change pressure, gas volume, etc. as appropriate
By combining them, the shape and volume of the blind cavity 11 can be controlled, and the shape of the blind cavity can be made circular, elliptical, polygonal, or the like. Furthermore, if the nozzle diameter and the resin coating (configuration) position of the nozzle are appropriately selected, a blind cavity having a desired volume and an opening can be formed.

Further, if the blind cavity 11 of the obtained resin molded body 12 is utilized as a resonator, a sound absorbing / insulating effect can be exhibited. Further, by controlling the thickness of the raw material resin wall between the blind cavities, in other words, the thickness of the rib-equivalent portion, a function of absorbing external impact energy can be provided, and the rigidity of the resin molded body can be improved. Furthermore, the opening 11 of the blind cavity
If a is formed in a desired size, the cavity (air layer) of the blind cavity 12 can be used as a heat insulating space.

Next, the pressure medium injection nozzle has a pressure medium injection port, and a portion in contact with the raw material resin filled in the cavity is covered with the resin, or is entirely formed of this resin. For example, a nozzle in which the resin nozzle portion 16 is the entirety of the pressure medium injection nozzle 5 (FIGS.
5) A nozzle having a resin nozzle portion 16 only at the nozzle tip (FIG. 15), or a resin coating layer 17 at the nozzle tip.
(FIGS. 6 to 14).

The pressure medium injection nozzle 5 has a pressure medium main passage 13, and the pressure medium main passage 13 is provided at the tip or side surface.
May be provided. It is desirable that the pressure medium main passage 13 has a heating device and can heat the pressure medium to a desired temperature. The pressure medium ejection port 15 is disposed, for example, at the tip (FIGS. 5 and 8).
And FIGS. 10 to 15) and can be arranged on the side surface (FIGS. 3, 4, 6, 7, and 9). In particular, when the pressure medium injection nozzle 5 has a pressure medium discharge port 15 on the side surface, the pressure medium main passage 1 extending in the axial direction of the nozzle 5
3 and a branch 14 intersecting with the pressure medium 3, and the tip of the branch located on the outer peripheral surface of the nozzle 5
It is preferable that the cavity 4 side from the pressure medium jet port 15 is coated or configured with the above resin. For example, nozzles as shown in FIGS. 6, 7, and 9 can be exemplified. In addition, the nozzle from the ejection port 15 to the cavity 4 side may be the above resin. Further, the branch path 14 intersecting with the pressure medium main path 13 is not limited to the case where it is orthogonal as in the present embodiment, but may be branched into a Y-shape.

Here, it is desirable that the resin that covers or configures the pressure medium injection nozzle 5 has a lower thermal conductivity than the mold surface (surface forming wall 2a). At this time, the temperature of the raw material resin 12 that is in contact with the nozzle 5 during molding of the resin molded body 12 is slowed down, and the formation of the solidified film is more likely to be delayed than the raw material resin 12 that is in contact with the surface forming wall portion 2a. That is, on the surface of the raw material resin 12, the surface forming wall portion 2a
A solidified film is preferentially generated from a portion in contact with the nozzle, and a solidified film (thin film) is easily formed at a portion in contact with the nozzle later. As a result, when the pressure medium is injected with an appropriate injection pressure, the solidified film (thin film) at the contact portion with the nozzle is easily broken, and the pressure medium can be injected into the molten resin.

As the resin, a resin having lower adhesiveness to the raw material resin 12 than the surface forming wall portion 2a and having heat resistance can be used, and it is preferable to use a fluorine resin and / or a silicone resin. . If the pressure medium injection nozzle is coated or configured with a resin having a large contact angle with the raw material resin, such as a fluorine-based resin or a silicone-based resin, the pressure medium injection nozzle 5 and the raw material resin 1 in contact therewith
The raw material resin 12 is easily intimately dissociated by the injection of the pressure medium, and when the raw material resin 12 is dissociated, a gap is formed between the material resin 12 and the tip of the nozzle. Cavities 11
Easy to promote the formation of

It is desirable to use an alloy having a higher thermal conductivity than the surface forming mold 2 as a nozzle component other than the resin, typically, copper-zinc (Cu-Zn).
A system alloy or the like can be used. Further, even when the pressure medium injection nozzle 5 is entirely made of the above alloy, the solidified film is preferentially generated in the raw material resin near the nozzle by utilizing the difference in thermal conductivity between the nozzle and the surface forming mold. The raw material resin on the mold side is solidified with a delay, and the solidified film on the surface of the raw material resin is shrunk. By utilizing the dissociation of the raw material resin (solidified film) from the pressure medium injection nozzle, a blind cavity is formed. can do. However, depending on the molding conditions such as the temperature and type of the raw resin, the tip shape of the nozzle, the surface finish, etc.
The dissociation of the solidified film tends to vary, and it is difficult to form a desired blind cavity.

Therefore, the portion of the pressure medium injection nozzle 5 which is in contact with the raw material resin 12 is coated with a resin having a large contact angle with the raw material resin 12 and a suitable adhesiveness, or is formed entirely of this resin. Therefore, if a solidified film is generated even in a very small amount, the pressure medium to be injected dissociates the solidified film from the nozzle, and a void serving as a starting point of the formation of a blind cavity can be formed. It is.

When the pressure medium injection nozzle 5 is coated with the above resin, the resin coating thickness (resin coating layer 17) is preferably 500 μm or less. It is effective to use the above-mentioned alloy having high thermal conductivity as the nozzle body (a component other than the coating resin) because the thermal conduction performance is utilized to easily form the blind cavity 11. 500 μm
When the pressure medium is exceeded, it is difficult to utilize the high thermal conductivity of the nozzle body, and the surface of the raw resin existing near the nozzle tip does not solidify and remains fluid. Problems such as an increase in the diameter more than necessary and an excessive pressure medium being injected to connect the blind cavities occur, and it becomes easy to control the diameter and volume of the opening of the blind cavity.

Further, the pressure medium injection nozzle 5 in which the periphery of the pressure medium ejection port 15 is coated or formed with the above resin can be used. For example, nozzles as shown in FIGS. In particular, FIGS.
As shown in FIG. 3, when the entire portion of the cavity (the projecting portion of the nozzle) in contact with the molten resin 12 is a nozzle covered with resin, the molten raw material resin 12 is
The gap generated by dissociation from the tip of the opening becomes large, and is suitable for forming a blind cavity having a large diameter and volume of the opening 11a. Further, as shown in FIG. 14, when the nozzle around the ejection port 15 is smaller than the diameter of the nozzle insertion hole 5a, the generated void (dent) becomes small, and the opening 1
It is suitable for forming a blind cavity 11 having a small diameter of 1a.

Further, depending on the volume of the blind cavity 11 to be formed, the opening 11a, the thickness of the resin molded body 12, and the like,
The installation position of the pressure medium injection nozzle 5 can be changed. For example, the position (FIG. 3, FIGS. 6 to 8) retracted from the surface forming wall portion 2 a is flush with the surface forming wall portion 2 a (the same plane). Positions (FIGS. 4, 9 to 11) and positions protruding into the cavity 4 (FIGS. 5, 12 to 15).

When the nozzle 5 is disposed at a position retracted from the surface forming wall 2a, the raw resin 12 flowing into the nozzle insertion hole 5a (recess) of the surface forming mold 2a comes into contact with the surface forming wall 2a. The solidified film (thin film) is formed after being cooled later than the raw material resin 12, and the blind cavity 11 having an opening diameter smaller than the nozzle outer diameter can be formed. When the nozzle 5 is arranged flush with the surface forming wall 2a, a blind cavity 11 having an opening diameter substantially similar to the nozzle outer diameter can be formed. Further, when the nozzle 5 is arranged at a position protruding into the cavity 4, the volume of the blind cavity 11 to be formed tends to be smaller than that of the retreat type and the flush type.

The resin at the tip of the pressure medium injection nozzle 5 (the portion in contact with the raw material resin) is desirably roughened. For example, an alloy or the like is roughened as a nozzle body.
The surface can be roughened using a known resin coating method such as a method of impregnating the roughened portion with a resin or a method of heating and fusing a resin film to a heated nozzle body. In this case, the adhesion with the raw material resin can be adjusted more appropriately.

Furthermore, the arrangement interval and the existence ratio of the pressure medium injection nozzles 5 (pressure medium outlets 15) may be partially biased so that the blind cavity openings 11a are evenly arranged on the surface of the resin molding 12. It is also possible to distribute unevenly according to desired partial rigidity and lightness, for example, by densely distributing a part of the surface. The thickness of the resin surrounded by the blind cavities 11, ie, the resin corresponding to the reinforcing ribs (the resin thickness between adjacent blind cavities) can be controlled by adjusting the position and density of the blind cavities. This makes it possible to adjust sink marks, warpage, and variations in rigidity of the obtained resin molded body.

Further, the pressure medium injected into the raw resin 12 from the pressure medium injection nozzle 5 is preferably in a gaseous state at normal temperature and normal pressure, for example, such as air, carbon dioxide, nitrogen or argon. A non-flammable material that maintains a gaseous state at room temperature (normal temperature) can be used. In particular, it is desirable to use air, carbon dioxide, or nitrogen which is easy to supply and inexpensive.

Although the pressure medium injection nozzle 5 is not provided with a check valve for the raw material resin 12, the nozzles (FIGS. 3, 4, 6, 7, and 9) for ejecting the pressure medium from the side surfaces of the nozzle are:
By adjusting the gap between the nozzle and the surface forming mold 1 into which the nozzle is inserted, the inner diameter of the pressure medium main passage 13, the pressure medium branch 14, and the diameter of the pressure medium outlet 15, the backflow of the raw resin 12 is prevented. be able to. Further, in the nozzle 5 (FIGS. 5, 8, 10 to 15) for ejecting the pressure medium from the tip,
By adjusting the diameter of the pressure medium outlet 15 and the inner diameters of the pressure medium main passage 13 and the pressure medium branch 14, the backflow of the raw material resin can be prevented. The above adjustment is appropriately performed in consideration of the type and shape of the raw material resin of the resin molded body, the molding conditions, and the like.

Next, the resin molding method of the present invention will be described with reference to an example of a method of molding a resin molded body using the resin molding die of the present example. First, the resin molding die is closed, and the material resin 12 is injected and filled into the cavity 4. Next, during or after the filling of the raw material resin 12, or during or after the displacement of the back surface forming mold 2, while the raw material resin 12 has fluidity, the pressure is applied through the pressure medium chamber 3. A heated pressure medium is injected from the medium injection nozzle 5 to form a blind cavity 11. At this time, the pressure medium flows from the front surface forming wall portion 2a to the rear surface forming die 1 (movable die).
A predetermined amount and a predetermined pressure can be injected in the direction of the concave wall 1a, and the resin molded body 12 having the blind cavity 11 and the opening 11a on the surface can be formed. The backside forming mold 1 is displaced in the injection direction during injection of the pressure medium, and promotes formation of the blind cavity 11. A pressure medium is injected and a desired blind cavity 11 is formed in the raw material resin 12.
Is applied, the raw material resin 12 is solidified (cooled) and released from the mold, whereby the resin molded body 12 is obtained.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings by way of examples and comparative examples, but the present invention is not limited to these examples.

By the following resin molding die and molding method,
Resin molded articles shown in Examples and Comparative Examples were obtained. (1) Resin molding die and molding method Using an injection molding machine with a clamping pressure of 110 t, a pressure medium can be injected from a surface forming die and the volume in the cavity is 10
A mold that can be displaced to 0x100x3 to 10 (t) mm,
A polystyrene resin (M121, manufactured by Sumitomo Chemical) was injection molded at a resin temperature of 210 ° C. FIGS. 1 and 2 schematically show the resin molding die before the injection molding and after the formation of the blind cavity. The mold is provided with a pressure medium injection nozzle 5 as shown in FIG. The pressure medium is temporarily stored between the control valves of FIG. 1 and is heated to 120 ° C. by the heating device 10, the control valve 9 receiving a signal during or after filling the resin into the cavity 4 opens, and the pressure medium chamber is opened. Flow to 3. Each pressure medium injection nozzle 5 is connected to the pressure medium chamber 3, and at the same time, the same pressure medium is supplied to the raw resin 12 in the cavity. After cooling and release, a resin molded body containing a blind cavity is obtained. The pressure medium is air (heated compressed air), supplied at 1 MPa, and the mold is heated to 50 ° C.

The pressure medium injection nozzle is made of a Cu-Zn based alloy, and the resin coating (resin contacting part) is roughened to obtain a fluorine-based resin (trade name: NEOFLON PFA, AP).
-210, manufactured by Daikin Industries, Ltd. and melt-coated, or a silicone-based resin (trade name: KMC-10, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied and heat-cured before use. Nine pressure medium injection nozzles with an outer diameter of 6 mm are used and are arranged at equal intervals. The positions of the nozzles are 1 mm for the protrusion in the cavity, the same plane as the mold (same surface), or 1 mm from the mold (recessed). )). The number of the nozzles was two when provided on the side surface and one when provided at the tip, and the diameter of the nozzle was 200 to 300 μm. The volume inside the cavity after the expansion was set to 100 × 100 × 8 (t) mm.

(Example 1) The cavity thickness before filling the resin with the resin molding die was set to 3 mm, the rear surface forming die 2 was displaced at a filling rate of 98%, and air was injected. The cavity thickness after displacement of the backside forming mold 1 was set to 8 mm. The main body of the pressure medium injection nozzle is made of fluororesin,
It has the cross-sectional shape shown in FIG. 3, and the nozzle was disposed at a position retracted from the mold surface. Table 1 shows the evaluation results of the obtained resin molded bodies.

(Examples 2 and 3) The same operation as in Example 1 was repeated except that the shape and the arrangement position of the pressure medium injection nozzle were changed to obtain a resin molded body. Table 1 shows the evaluation results of the resin molded products.

(Examples 4 to 7) A pressure medium injection nozzle having a tip portion coated with a fluorine resin is used.
The same operation as in Example 1 was repeated, except that the tip shape and the coating site were changed, to obtain a resin molded body. Table 1 shows the evaluation results of the resin molded products.

(Example 8) A pressure medium injection nozzle composed of a resin nozzle coating portion (tip portion) and a Cu-Zn alloy body was used, except that it was projected into the cavity.
The same operation as in Example 1 was repeated to obtain a resin molded body.
Table 1 shows the evaluation results of the resin molded products.

(Examples 9 to 12) The same operation as in Example 1 was repeated except that the coating resin for the nozzle body or the tip portion was changed to a silicone resin, and the nozzle shape and arrangement position were changed, to obtain a resin molded body. Was. Table 1 shows the evaluation results of the resin molded products.

(Comparative Examples 1 to 3) The nozzle body was made of Cu-Zn
The same operation as in Example 1 was repeated, except that the resin was not coated and the nozzle position was changed, to obtain a resin molded body. Table 2 shows the evaluation results of the resin molded products.

(Comparative Examples 4 and 5) The same operation as in Comparative Example 1 was repeated except that the thickness of the coating resin layer of the nozzle was changed.
A resin molding was obtained. Table 2 shows the evaluation results of the resin molded products.

(2) Evaluation method The following evaluations were performed on the resin molded bodies obtained in the examples and comparative examples. The evaluation results are shown in Tables 1 and 2, respectively.

Blind Cavity Formation Ratio The average of the number of blind cavities formed / the number of nozzles n (n = 9) was determined.

Presence or absence of sink marks and warpage The surface appearance of the resin molded product was visually observed to determine the presence of sink marks and warpage.

The presence / absence of connection between the blind cavities The blind cavities were visually observed to determine the presence / absence of connection between the blind cavities.

Opening Diameter Ratio The average of the opening diameter of the blind cavity / the outer diameter (insertion diameter) of the mold nozzle was determined, and it was determined whether or not it was 0.8 to 1.2.

[0056]

[Table 1]

[0057]

[Table 2]

As shown in Table 1, the resin moldings (Examples 1 to 12) obtained by the resin molding die and the molding method which are within the preferable range of the present invention have blind blinds corresponding to the number of nozzles. It is evident that it has cavities, no sink marks, an opening diameter ratio in the desired range, and no connection between blind cavities. On the other hand, as shown in Table 2, the resin molded articles (Comparative Examples 1 to 5) obtained by the resin molding die and the molding method which are out of the scope of the present invention are the same as those of Comparative Example 1 to 3 except for the raw material resin of the nozzle. Because the part in contact with is not covered or configured with the predetermined resin,
It can be seen that a blind cavity cannot be formed, that the blind cavity does not have a desired opening diameter, and that sink marks are easily generated. Further, in Comparative Examples 4 and 5, the thickness of the coated predetermined resin was too large, so that it was difficult to form a blind cavity,
It can be seen that sink marks and warpage occur, do not have a desired opening diameter, and the blind cavities are easily connected to each other.

Although the present invention has been described in detail with reference to preferred examples and comparative examples, the present invention is not limited to these examples, and various modifications can be made within the scope of the present invention. . For example, in the resin molded body, the openings of the blind cavities can be provided not only on the front surface but also on both the back surface and the front and back surfaces. Further, regarding the fixed mold and the movable mold, the fixed side and the movable side can be replaced with each other, and further, both can be displaced.

[0060]

As described above, according to the present invention, at least a predetermined portion of the pressure medium injection nozzle provided in the resin molding die, which is in contact with the raw material resin, is covered or formed with the resin. Independent blind cavity opening diameter,
A mold equipped with a pressure medium injection nozzle that can easily control the shape and volume.
It is possible to provide a resin molding die which has a sound insulation property, is free from sink marks, warpage, and the like, and is easy to mold a resin molded body having excellent appearance quality, and a resin molding method using the same.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of a resin molding die of the present invention (before raw material resin is injected).

FIG. 2 is a side sectional view showing a state in which a blind cavity is formed in the resin molded body with the resin molding die shown in FIG.

FIG. 3 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is recessed.

FIG. 4 is a side sectional view showing an example of a resin molding die in which pressure medium injection nozzles are installed flush with each other.

FIG. 5 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is provided in a protruding shape.

FIG. 6 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is recessed.

FIG. 7 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is recessed.

FIG. 8 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is recessed.

FIG. 9 is a side sectional view showing an example of a resin molding die in which pressure medium injection nozzles are installed flush with each other.

FIG. 10 is a side cross-sectional view showing an example of a resin molding die in which pressure medium injection nozzles are installed flush with each other.

FIG. 11 is a side cross-sectional view showing an example of a resin molding die in which pressure medium injection nozzles are installed flush with each other.

FIG. 12 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is provided in a protruding shape.

FIG. 13 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is provided in a protruding shape.

FIG. 14 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is provided in a protruding shape.

FIG. 15 is a side sectional view showing an example of a resin molding die in which a pressure medium injection nozzle is provided in a protruding shape.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 back surface forming die 1a back surface forming wall portion 2 surface forming mold 2a surface forming wall portion 3 pressure medium chamber (gas chamber) 4 cavity 5 pressure medium injection nozzle 5a nozzle insertion hole 6 resin injection port 7 pressure medium (gas cylinder) 8 Pressure control valve 9 Control valve 10 Heating device 11 Blind cavity 11a Blind cavity opening 12 Resin molding (raw material resin) 13 Pressure medium main passage 14 Pressure medium branch 15 Pressure medium jet 16 Resin nozzle portion 17 Resin coating layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Uesugi 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Masaaki Suzuki 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor F Term (reference) 4F202 AG06 AH26 AH47 AH48 CA11 CB01 4F206 AG06 AH26 AH47 AH48 JA07 JM05 JN27 JQ81

Claims (6)

[Claims] 1. A resin molding die provided with a pressure medium injection nozzle for forming a plurality of independent blind cavities extending in a rear direction and having an opening on a surface of a resin molded product, wherein the cavity is defined. The stationary mold has a wall forming the surface of the resin molded article, and the surface forming wall has the pressure medium injection nozzle and the raw material resin. An inlet is provided, the movable mold has a back surface forming wall portion facing the front surface forming wall portion, and is displaceable in substantially the same direction as the pressure medium injection direction through the pressure medium injection nozzle, The resin characterized in that the pressure medium injection nozzle has a pressure medium ejection port, and a portion in contact with the raw material resin filled in the cavity is coated with resin, or is entirely formed of this resin. Molding mold. 2. The resin molding die according to claim 1, wherein the resin covering or constituting the pressure medium injection nozzle covers or constitutes the periphery of the pressure medium ejection port. 3. A resin molding die provided with the pressure medium injection nozzle having the pressure medium ejection port on a side face, the resin molding die having a pressure medium main passage extending in the axial direction of the nozzle and a branch passage intersecting the main passage. The tip end of the branch located on the outer peripheral surface of the pressure medium injection nozzle has the pressure medium ejection port, and the cavity side from the pressure medium ejection port is coated or configured with the resin. Claim 1 or 2
The resin molding die described in the above. 4. The resin according to claim 1, wherein the resin covering or constituting the pressure medium injection nozzle is a fluororesin and / or a silicone resin.
The resin molding dies described in the two items. 5. The resin molding die according to claim 1, wherein the pressure medium injection nozzle is coated with the resin in a thickness of 500 μm or less. 6. A resin molding method using the resin molding die according to any one of claims 1 to 5, wherein the movable resin is filled during or after filling of the cavity with a molten resin. During or after the displacement of the mold, and while the molten resin has fluidity, a pressure medium is injected from the pressure medium injection nozzle into the molten resin, and an opening is formed in the obtained resin molded body. A resin molding method characterized by forming a blind cavity having: