JP2018086740A - Production method of resin molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a resin molded article having a high insulator function without foam molding even using a molding device made of a resin of high molding freedom.SOLUTION: A production method of a resin molded article includes following steps: (a) an arranging step for arranging a pressing material on a cavity surface of a die (4) having a recess so as to cover the recess, (b) an injection step for injecting a resin toward the pressing material from a gate of a die (5) facing the die (4) having the recess to form the cavity, and (c) a compression flow step for subjecting the injected resin to compression flow by closing the die (4) and die (5) at the same time of the injection step or after beginning of injection.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a resin molded product.

  Conventionally, a sheet-like insulator (compressed material) that functions as a sound absorbing material is attached to the inner surface of the engine hood that covers the upper side of the engine room of an automobile, thereby absorbing the sound generated from the engine. Yes. As a method of attaching an insulator to the engine hood of such an automobile, as shown in FIG. 3, a clip 14 or a double-sided tape is used for the hood inner panel 12 in which the insulator 13 is installed on the hood outer panel 11. Since clip parts costs and mounting man-hours are incurred, studies have been made to reduce them. For example, there are proposals disclosed in Patent Documents 1 and 2 below.

Although the attachment method of patent document 1 was shown in FIG. 4, it is a proposal which makes it possible to insert the insulator 13 partially using the cut-and-raised shape of the hood inner panel 12.
Japanese Patent Application Laid-Open No. 2004-228561 has shown the attachment method in FIG. 5, but is a proposal that enables simple assembly by a slide operation using the cut-and-raised shape of the hood inner panel 12 and the insulator 13.
By using these structures, it is said that assembly man-hours and clip points can be reduced.

  On the other hand, the demand for weight reduction of automobile parts is extremely high due to the demand for improvement in fuel consumption due to environmental problems in the tendency to increase weight due to the increase in parts resulting from higher functionality. For this reason, resinization of structural parts such as panels attracts attention, and resinization is applied to door parts, hood parts, cover parts, and the like. By converting to resin as disclosed in Patent Document 3, it is possible to expect commercialization in the future that takes advantage of the high degree of freedom of molding instead of iron parts manufactured in the press process.

Japanese Patent Laid-Open No. 10-119824 JP 2013-1299 A JP-A-6-315946 JP 2011-195080 A Japanese Patent No. 585833

  However, in the commercialization based on the metal panel disclosed in Patent Documents 1 and 2 described above, there is a limit to weight reduction. For example, in an insulator mounting structure, workability is improved and the number of clips is reduced. There is a problem that the clip is completely lost and the entire circumference of the insulator cannot be pressed.

  Moreover, in what was disclosed by patent document 3 which is a proposal of a resin-molding molded object, although the conventional insulator needed shaping and trimming according to the attachment shape, by providing a foaming layer inside a molded object, Integration of a molded body and an insulator characterized by adding the performance of the insulator has been proposed.

  However, in the integration of the molded body as disclosed in Patent Document 3, the insulator becomes a foam layer surrounded by a skin layer, the degree of freedom in thickness is limited, and a high insulator function is expected. It becomes cost.

  The technology for integrating glass fiber bodies for higher functionality has been widely adopted as disclosed in Patent Document 4, but most of them used thermosetting resins and adhesives to ensure adhesion. It was due to compression molding. Conventionally, in integration with a thermoplastic resin, there has been no choice but to rely on mechanical fastening due to problems such as resin impregnation and adhesion, but the present invention improves it.

  An object of this invention is to provide the manufacturing method of the resin molded product which has a high insulator function, without performing foam molding, using the resin-made molded object with a high shaping | molding freedom degree.

The present invention relates to the following.
(1) A method for producing a resin molded product produced by the following steps.
(A) An arrangement step in which a compression material is arranged on the cavity surface of the mold (a) having a recess so as to cover the recess.
(B) An injection step of injecting resin toward the compression material from the gate of the mold (b) that forms a cavity in a pair with the mold (a) having the recess.
(C) A compression flow process in which the mold (A) and the mold (B) are clamped at the same time as the injection process or after resin injection is started, and the injected resin is compressed and flowed.
(2) A process for producing a resin molded product according to item (1), wherein a part of the compression material is compressed and fixed with a piece protruding from the mold (b).
(3) In the item (2), the piece compresses from the center rather than the entire outer periphery of the compressed material, and at least the entire outer periphery of the compressed material is fixed to the injected resin. Method.
(4) The method for producing a resin molded product according to any one of items (1) to (3), wherein the compression material is a fiber woven fabric or a fiber nonwoven fabric.
(5) The method for producing a resin molded product according to any one of items (1) to (4), wherein the resin is a thermoplastic resin.
(6) In any one of items (1) to (5), the recess has a width and a depth both of 0.5 mm or more, and the relationship between the width and the depth of the recess is (width / depth) ≦ 1. The manufacturing method of the resin molded product which is 0.

According to the present invention, the compression material arranged on the cavity surface allows the injected resin to penetrate the compression material itself and reach the recess on the back surface side, so that the resin is fixed as compared with the compression material arranged on the plane. It is easy to make it easy to mold.
In addition, when compressing a part of the compression material using a piece, by converting a conventional steel or aluminum hood panel component into a resin and integrating a molded body such as a hood inner panel or an engine cover with an insulator, It is not necessary to shape or trim the insulator in accordance with the mounting shape, the use of the clip at the time of mounting can be eliminated, and the man-hours can be reduced and the manufacturing cost can be kept low without impairing the function.

It is process drawing which shows the manufacturing method of the resin molded product of this invention, (a) is an arrangement | positioning process, (b) is an injection process, (c) and (d) are compression flow processes, (e) shows mold opening. It is sectional drawing of the metal mold | die which shows another Example of this invention. It is a schematic exploded view which shows the conventional insulator installation method. It is a principal part perspective view which shows the conventional insulator attachment structure. It is a principal part perspective view which shows the other conventional insulator attachment structure.

Embodiments of the present invention will be described below.
(Mold)
The mold described in this specification is a pair of a mold (A) having a recess and a mold (B) having a gate, and a cavity is formed by the mold (A) and the mold (B). Form.
The material of the mold is not particularly limited as long as it can withstand the pressure and temperature to be used, and a material used for a general mold can be used.
For example, carbon steel and prehardened steel such as S45C, S50C, and S55C containing 0.45% by mass to 0.55% by mass of carbon can be used, and when quenching, SKD material or SCM material is used. Special steel can also be used.
Since the mold has a compression flow process after resin injection, a so-called "quick structure" is preferable. A parting structure with a movable piece may be used as long as a structure in which the injection resin does not flow out of the cavity is obtained.

A recessed part is provided in a metal mold | die (I), and is covered with the compression material mentioned later.
The recess is provided because the resin is difficult to impregnate the compression material by simply placing the compression material on a simple plane. In the case of a flat surface (there is no recess), the compression material is compressed by the resin pressure, the gap in the compression material is reduced and impregnation is difficult, and the resin is solidified by cooling from the mold.
On the other hand, when the recess is provided, a resin pressure escape field is generated, the compression of the compression material is locally reduced, and the cooling of the resin is also locally reduced. As a result, the resin easily penetrates the compressed material, and the resin can easily flow into the recess.
The shape of the recess is not particularly limited, and can be various shapes. Moreover, although the resin cured part formed by the recessed part can be removed later, it can be left as it is and used as a functional part such as a rib.
The size of the recess is not limited in the same manner as the shape, but is preferably a shape that can prevent the compression material from entering and can easily enter the resin. Specifically, the relationship between width and depth is (width /Depth)≦1.0, and both width and depth are preferably 0.5 mm or more.

The gate is provided at least in the mold (b), and may be provided in both the mold (b) and the mold (b) as necessary.
Note that the number of gates provided in the mold (b) is not necessarily one, and a plurality of gates may be provided.

(Compressed material)
The compression material described in this specification is not particularly limited as long as it can absorb sound after molding. When compression is performed with a piece to be described later, The resin is not particularly limited as long as the injected resin does not enter the portion compressed in step (b). Specifically, any material that can be sufficiently deformed and densified at a pressure of about 1 MPa and prevented from entering the resin may be used.

Examples of the material of the compression material include an aggregate of inorganic fibers such as glass fibers, resin fibers such as Kevlar fibers, and natural fibers such as cellulose, and a woven or non-woven fabric processed into a mat shape, a sheet shape, or a cloth.
These have the characteristics of being sufficiently deformed and densified by compression, and are restored when the pressure is removed. The restoration described here only needs to return to a state in which the function as an insulator can be sufficiently exhibited, and does not mean to completely return to the state before compression.

  Since the compressive material has different pressure strength depending on the material, it is necessary to select a material or to optimize the compression force of the die piece according to the purpose. On the other hand, the influence of heat differs depending on the material, and inorganic fibers have high heat resistance and high degree of freedom of application, but in the case of resin fibers or natural fibers, etc., optimization of molding conditions considering heat resistance is possible. is necessary. For example, in the case of a resin fiber, it is necessary to select a fiber having higher heat resistance with respect to the melting point of the molding resin. These fiber woven fabrics, mat-like or non-woven fabrics, for example, have better sound absorption characteristics in the low-frequency region to the high-frequency region as shown in Patent Document 5, compared to foams, and provide soundproofing and heat insulation. Therefore, automobiles and the like have a track record of use and are more preferable.

(Arrangement of compressed material)
The arrangement of the compression material does not need to be particularly fixed in the case of the vertical type (the compression material is laid in the horizontal direction). In the case of the horizontal type (where the compression material is erected), it is necessary to fix it to the mold, and this can be done using pins or the like provided on the movable or fixed side mold.

(Compression with a piece)
If there is a part where you do not want to fix the resin to the compression material, use a piece. The piece described in the present specification protrudes from the mold (b) and compresses a part of the compression material, and this compression prevents the resin from adhering.
Note that the portion compressed by the piece is a portion where the above-described recess is not formed.

  The portion to be compressed by the piece is preferably from the center rather than the entire circumference of the outer periphery of the compressed material, and in this way, the entire outer periphery of the compressed material can be fixed to the injected resin. It is possible to firmly integrate the compression material and the resin.

  When compressing and fixing the compression material, the compression material is partially compressed in the mold. The compression method uses the above-mentioned piece. Although the pressure depends on the reaction force of the compression material, it may be of any structure that can pressurize about 0.1 MPa, and can be moved back in the mold-clamping compression process, which is a subsequent process. Is preferred.

Specifically, a structure as shown in FIG. 1 can be considered, and a mechanical structure such as a spring 3 can be selected for adjusting the pressure. In order to improve the insulator performance and reduce the weight, the piece 7 shown in FIG. 1 has a large area and is heavy, so that only the outer peripheral part of the piece 7 is maintained as it is and the contents are hollowed out. Also good.
Furthermore, resin penetration into the compression material may be prevented by using a plurality of divided pieces.

(resin)
The resin described in the present specification means a thermosetting resin or a thermoplastic resin, and it is preferable to use a thermoplastic resin from the viewpoint of easy molding.
As the thermoplastic resin, PP (polypropylene), PET (polyethylene terephthalate), PA (polyamide), PC (polycarbonate), ABS (acrylonitrile butadiene styrene) and the like can be used.

The resin to be injected may be a resin alone, or a resin mixed with fibers.
The fibers to be mixed are preferably the same as the fibers forming the compression material described above, but may be different fibers, specifically, inorganic fibers such as glass fibers and carbon fibers, and Kevlar fibers. There are natural fibers such as resin fibers and cellulose.
The fibers to be mixed may be one type or a mixture of a plurality of types.

(Injection process)
In the injection process, resin is injected and supplied into at least the cavity. When the resin is caused to flow into the concave portion provided in the mold (a) only by the injection process, it is necessary to apply a resin pressure in the inflow direction and maintain the low viscosity state of the resin. In normal injection molding, until the filling of the cavity is completed, pressure in the concave shape direction cannot be expected and filling is difficult, but the compression body is compressed by pressurization from the opposing mold just above the gate. This is possible if the injection filling is performed.

(Compression flow process)
In the compression flow process, the resin is filled in the cavity. At this time, the resin pressure is likely to work in the direction perpendicular to the surface, facilitating penetration of the resin into the recess. In order for the resin pressure by the compression flow process to work effectively, it is necessary to maintain the resin at a low viscosity, and it is effective to perform the compression flow process immediately after the resin injection in the injection process or simultaneously with the injection process. Therefore, specifically, it is preferable to use an injection compression molding machine.
In addition, the position of the recessed part of a metal mold | die (a) should just be a position where the resin pressure at the time of compression filling is sufficient, and is not limited to a gate just upper part.

  In the portion not compressed by the compression material piece, the resin and the compression material come into contact with each other and are fixed. Further, after cooling the resin, the mold is opened and the molded body is taken out. At this time, the compressed material is released from partial compression and restored. Thereby, the function as an insulator can be exhibited except for the fixing portion. Thus, the molding process for the molded body is completed.

(Production method of resin molded products)
A method for producing a resin molded product will be described with reference to the drawings.
In the arranging step, as shown in FIG. 1A, the compression material 2 is arranged so as to cover the concave portion 8 with respect to the mold (A) 4 having the concave portion 8.
In FIG. 1, the central portion (excluding the peripheral portion) of the compression material 2 is compressed by the force of the spring 3 using the piece 7 of the die (b) 5.

Next, in the injection process, as shown in FIG. 1B, the molding resin 1 is injected from a plurality of injection gates 6 provided in the mold (b) 5.
Further, at the same time as the injection of the molding resin 1 is started, as shown in FIG. 2C, the mold (A) 4 is moved downward in the drawing, and the compression flow of the injected molding resin 1 is performed. I do.
In the case where only the injection process is performed, the compression body 2 is compressed by the force of the spring 3 using the piece 7 of the opposing mold (A) 4 immediately above the injection gate 6 as shown in FIG. This can be handled by injection filling.
FIG. 1 (c) shows an intermediate stage of the mold-clamping compression flow process, and in the final stage, as shown in FIG. 1 (d), the mold (A) 4 and the mold (B) 5 Will be in contact. Then, after the cooling of the molded resin 1 is completed, the mold is opened, and as shown in FIG. 1E, the compression material 2 is restored by releasing the pressure, and the resin molded product can be taken out.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto.
Example 1
As the molding die, a prototype die was used, the molding machine was a vertical 1,000 t press machine manufactured by Amino Co., Ltd., and the injection machine was a product manufactured by Nippon Steel Corporation.
GFPP (containing 30% by mass of glass-reinforced polypropylene glass) is used as the molding resin, and glass cloth (glass fiber diameter of 17 μm, number of fibers of 2,000, basis weight of 960 g / m ² , thickness of 1.0 mm, plain weave) is used as the compression material. A molded product was produced using a size of 500 mm × 500 mm.

(Example 2)
As the compression material, a glass mat (glass fiber diameter 12 μm, number of fibers 100, thickness 0.5 mm, basis weight 300 g / m ² ) was used, and a molded product was produced in the same manner as in Example 1.

  The mold includes a recess (a) having a recess having a width of 3 mm, a depth of 3 mm, and a length of 3 mm, and a piece portion (b) capable of a compression operation supported by a spring within a diameter of 200 mm. Is prepared. After holding the mold and placing the compression material so as to cover the recess, (placement step) GFPP (glass reinforced polypropylene) is injected (injection step), and immediately after injection, the mold is compressed and filled with resin. (Compression flow process). The compression stroke was 5 mm.

(Comparative Example 1)
The mold is flat (no recess), the compression material is the glass cloth described in Example 1, the compression material is placed on the flat surface of the cavity, the mold is closed, and the molding resin is injected (injection process) Only produced.

(Comparative Example 2)
The mold is flat (no recesses), the compression material is the glass mat described in Example 2, the compression material is placed on the flat surface of the cavity, the mold is closed, and the molding resin is injected (injection process) Only produced.

Example 3
The mold has a recess having a width of 20 mm, a depth of 10 mm, and a length of 10 mm, and the compression material is a mold after the compression material is disposed so as to cover the recess using the glass cloth described in Example 1. After closing, the mold resin was injected (injection process) and immediately after the injection, the mold was compressed and filled (resin flow process). The compression stroke was 5 mm.

Example 4
The mold described in Example 3 is used, and the compression material is the glass mat described in Example 2. After the compression material is arranged so as to cover the recess, the mold is closed and the molding resin is injected. (Injection process) Immediately after injection, the mold was compressed and filled with resin (compression flow process). The compression stroke was 5 mm.

(Through-fixed state of compressed body)
The produced molded product was visually observed, and the penetration fixed state of the compression material was evaluated as follows. The results are shown in Table 1.
“◎”: Compressed material is penetrated and fixed “O”: Compressed material is partially penetrated and fixed “×”: Compressed material is not penetrated and fixed

As is clear from Table 1, in Examples 1 to 4 using a mold provided with a recess, the through-fixed state of the compression material is good. Penetration does not go well, and the fixing state is bad.
Further, when Examples 1 and 2 are compared with Examples 3 and 4, the width and depth of the recess are both 0.5 mm or more, and the relationship between the width and depth of the recess is (width / depth). In Examples 1 and 2 where .ltoreq.1.0, the portion of the compressed material on the concave side penetrates and is fixed through the resin, and in Examples 3 and 4, it is partially through and fixed. That is, it is particularly preferable in molding that the concave portion has both a width and a depth of 0.5 mm or more and the relationship between the width and the depth of the concave portion is (width / depth) ≦ 1.0. I understand.

1. Molding resin, 2. 2. compression material; Spring, 4. Mold (I), 5. Mold (b), 6. 6. injection gate, Piece, 8 Recess, 11. Hood outer panel, 12. Hood inner panel, 13. Insulator, 14. Clip

Claims (6)

The manufacturing method of the resin molded product manufactured by the following processes.
(A) An arrangement step in which a compression material is arranged on the cavity surface of the mold (a) having a recess so as to cover the recess.
(B) An injection step of injecting resin toward the compression material from the gate of the mold (b) that forms a cavity in a pair with the mold (a) having the recess.
(C) A compression flow process in which the mold (A) and the mold (B) are clamped at the same time as the injection process or after the resin injection is started, and the injected resin is compressed and flowed.   2. The process for producing a resin molded product according to claim 1, wherein a part of the compression material is compression-fixed by a piece protruding from the mold (b).   3. The method of manufacturing a resin molded product according to claim 2, wherein the piece compresses from the center rather than the entire outer periphery of the compressed material, and at least the entire outer periphery of the compressed material is fixed to the injected resin.   4. The method for producing a resin molded product according to claim 1, wherein the compression material is a fiber woven fabric or a fiber nonwoven fabric.   The method for producing a resin molded product according to claim 1, wherein the resin is a thermoplastic resin.   6. The resin molding as defined in claim 1, wherein the recess has a width and a depth of 0.5 mm or more, and the relationship between the width and depth of the recess is (width / depth) ≦ 1.0. Product manufacturing method.

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