JPH0755513B2 - Compound injection molding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a composite molded article of a thermosetting resin and a thermoplastic resin, and more specifically, a thermosetting resin on the surface of the thermoplastic resin molded article. The present invention relates to a composite injection molding method for easily making a composite molded article in which a cured layer of a resin is firmly bonded by injection molding.

[Conventional technology]

Conventionally, thermoplastic resins have been widely used in various fields due to their good moldability, but due to lack of surface hardness, heat resistance, flame resistance, chemical resistance, abrasion resistance, etc. It was an obstacle to expansion. On the other hand, the thermosetting resin is superior to the thermoplastic resin in the above properties, but is poor in moldability and shapeability. It is desirable to obtain a molded product that takes advantage of each other's advantages by integrally integrating these two resins.

As a composite molded product of a thermosetting resin and a thermoplastic resin, a film of diallyl phthalate resin (hereinafter abbreviated as DAP) is used in order to improve the surface decoration and scratch resistance of the thermoplastic resin furniture. , A part of the thermoplastic resin molded product pasted with an adhesive or a high heat resistant thermoplastic resin, for example, an uncured thermosetting resin on the surface of a molded product of glass fiber reinforced polyamide resin, etc. There is known a so-called bake-coated molded article which is applied and cured by heating. Japanese Patent Laid-Open No. 53-123463 discloses a molding method thereof, and Japanese Patent Publication No. 43-2577 discloses a similar technique although the object constitution of the invention is slightly different.

[Problems to be solved by the invention]

However, except for a few cases such as the use of the special high heat resistant thermoplastic resin described above, there are some methods of applying and baking a thermosetting resin to a normal thermoplastic resin molded article, In many cases, the thermoplastic resin described above is softened and deformed by heat and cannot attain its purpose. In addition, the laborious process called painting is also a difficulty in production.

With the thermosetting resin plate laminating method as described above, only a molded product having a simple shape in which the thermosetting resin layer is stuck only on the flat surface of the molded product can be obtained, and the thermosetting resin layer is formed on the surface. It is not possible to obtain a composite molded article having a complicated shape having a three-dimensional curved surface that is firmly connected.

Therefore, an object of the present invention is to easily produce, by injection molding, a complex shaped composite molded article in which the surface of an ordinary thermoplastic resin having a normal degree of heat resistance is firmly covered and bonded with a thermosetting resin layer. Is to provide a method.

However, it has been found that the specific manufacturing method is a difficult task.

One problem is the adhesiveness between the thermosetting resin and the thermoplastic resin. Even if the cured thermoplastic resin is placed in a mold and the thermoplastic resin is injection-molded as in the case of painting with molding, both resins have different properties from each other originally, so there is no affinity for each other. It is impossible to prevent the resin from peeling from the contact surface. Further, even if the adhesive on the contact surface is devised, it is not a simple matter to provide a practically sufficient adhesion strength.

The adhesion between the laminated thermosetting resin layer and the base thermoplastic resin is
The laminated layer on the surface of the molded product is cross-cut into 100 square sections of 1 mm square, a cellotape peeling test is performed, and the adhesion is evaluated by the number of peeled squares.

If the thermosetting resin is set in the mold, the thermoplastic resin is pressed into the mold, and the resin temperature and the resin pressure are used to make a close contact, it may seem like a close contact depending on the combination of the resins. , When the above cellophane tape peeling test is performed,
Peel 100 squares out of 100 squares. That is, the result is 100/100 exfoliation.

Moreover, even if an attempt is made to cure the thermosetting resin by using the resin temperature at the time of injection molding of the thermoplastic resin, when it is executed, the uncured thermosetting is performed at the normal thermoplastic resin injection temperature and time. It is difficult to completely cure the thermosetting resin, leaving an uncured portion, and it is difficult to give the surface of the composite molded article the performance originally possessed by the thermosetting resin.

Further, it is conceivable to heat the mold after the injection of the thermoplastic resin to complete the curing of the thermosetting resin, but in the cooling water hole of the mold of the injection molding machine, cooling with a heating medium such as steam and cooling. The thermosetting resin is completely cured by switching between water and the cartridge heater, and
It takes a minimum of 20 to 30 minutes cycle to heat and cool a mass of iron such as an injection mold in order to obtain a desired molded product by cooling and solidifying a thermoplastic resin. Even if it is used, it is not industrially useful because of its poor productivity and expensive molds.

Therefore, the present inventors succeeded in efficiently heating and cooling the mold by high-frequency induction heating only on the shaping surface of the mold, and shortening the heating and cooling cycle. Is in an uncured state in the mold of the injection molding machine, the molten thermoplastic resin is injected and filled, and then the mold is heated by high frequency induction heating to complete the curing of the thermoplastic resin. Then, by cooling the mold and releasing the composite molded product from the mold, a composite molded product in which the resin and the resin are firmly bonded at the contact surface can be manufactured, and the present invention has been completed.

[Means for solving problems]

That is, the present invention is a method of allowing a uncured thermosetting resin to exist at a desired position in a mold of an injection molding machine and performing composite molding with a thermoplastic resin, by injecting a molten thermoplastic resin into the mold. By applying high frequency induction heating to the mold shaping surface,
The present invention relates to a composite injection molding method characterized by cooling and releasing after completion of curing of a thermosetting resin.

When the uncured thermosetting resin is compounded with the thermoplastic resin in the mold as in the present invention, the reason is not clear, but the uncured thermosetting resin is finely deformed during the compounding, and the adhesive area is increased.
Due to the reason that part of the uncured thermosetting resin and part of its solvent migrate to the thermoplastic resin and improve the affinity of the contact surface, the thermosetting resin and the thermoplastic resin are a composite Turned into
It is considered that a composite molded article having good contact surface adhesion can be obtained.

The present invention will be specifically described below.

In the production of the composite molded article of the present invention, first, an uncured thermosetting resin is placed at a desired position of a shaping part of a mold of an injection molding machine, that is, a so-called cavity part, a core part, that is, Is coated with a thermosetting resin solution at a desired position, or a sheet-shaped prepolymer composition of a thermosetting resin is attached,
Next, if necessary, the mold is rapidly heated to bring the thermosetting resin solution and the composition into a viscous state. Then, the thermoplastic resin is injected into the mold, and both resins are brought into contact with each other to integrate them. After that, the mold is heated again to completely cure the thermosetting resin. Then, cooling water is passed through the mold to cool and solidify the thermoplastic resin, and the mold is released to obtain a desired molded product.

The viscous state of the thermosetting resin mentioned above means that the monomer or prepolymer of the thermosetting resin and a mixture of the two, or those obtained by dissolving or diluting them in a solvent, a catalyst or a release agent, and if necessary Applied with a reinforcing agent such as glass fiber, viscosity modifier, etc. in the mold or pasted as a sheet, and when thermoplastic resin is injected, due to the flow resistance of the thermosetting resin, a coating film or a pasting sheet Refers to a viscosity that does not cause unevenness or significant uneven thickness, and if the viscosity can be adjusted to an appropriate value by properly adjusting the coating film thickness and the resin solution composition, that method may be used. However, as a more simple method for adjusting the viscosity, a thermosetting resin solution attached to a mold or the sheet-shaped prepolymer composition prior to injecting a thermoplastic resin is preheated and the solvent is volatilized, It is an effective method to adjust the thermosetting resin to a viscous state by slightly polymerizing it.

The thermosetting resin referred to in the present invention is a general term for resins that crosslink and cure when heated to a sufficiently high temperature.
Cross-linking includes those that are naturally carried out, including those containing a curing agent or catalyst for cross-linking, even resins that are usually referred to as thermoplastic resins, and those that cross-link with a peroxide catalyst, Included in the present invention.

Examples of thermosetting resins suitable for the present invention include DAP resins, unsaturated polyester resins, epoxy resins, thermosetting polyurenes, etc., and these resins are catalysts and thickeners, glass fibers, if necessary. It may contain a reinforcing agent such as mica and calcium carbonate, an extender and a non-woven fabric of various fibers such as glass mat, Japanese paper, vinylon and polyester for enhancing the reinforcing effect and the shape retaining effect in the mold. Further, a film of a thermoplastic resin such as polystyrene or ABS resin containing a crosslinking agent such as divinylbenzene can also be used.

The thermoplastic resin of the present invention, polyethylene, olefin resins such as polypropylene, polystyrene, styrene-acrylonitrile copolymer, ABS resin, styrene-
Styrene resin such as maleic anhydride copolymer, polyvinyl chloride, vinyl chloride resin such as vinyl chloride-vinyl acetate copolymer (EVA), polyethylene terephthalate, polyester resin such as polybutylene terephthalate, polycarbonate resin, So-called super engineering resins such as polyamide resins, polyphenylene ether resins, polyoxymethylene resins, polymethylmethacrylate resins, polyetherimide resins, polyphenylene sulfide resins, fibrin derivative resins such as cellulose acetate, and blends thereof. And the like, which may include fillers such as glass fiber, iron powder, talc and calcium carbonate, and ordinary resin additives such as plasticizers.

An example of an injection molding die used in the present invention is shown in FIG.
FIG. 1 shows an example of a sleep rate type mold, in which a fixed side mold plate 5 is provided with a cavity plate 1 for forming a cavity, and if necessary, a release film A and a thermosetting resin prepolymer sheet B are provided. When using it, install pin 11 to fix it. The pin 11 is not necessary when the release film is not necessary or when the thermosetting resin or the like is directly applied to the mold. The movable side mold plate 6 is also provided with the core plate 2 that similarly forms a core. In order to heat the cavity plate and the core plate, a coil 3 formed by spirally winding a copper tube is arranged on the back surface of each plate, and a high frequency current is passed through the coil to heat the cavity plate and the core plate by high frequency induction. . Providing cooling water holes in the cavity plate and core plate is effective in shortening the molding cycle.
In addition, the sealing layer 4 may be provided by a non-magnetic material such as copper or brass in a portion of the mother die portion such as the fixed-side mold plate 5 or the movable-side mold plate 6 that does not require heating, which does not require high frequency induction heating. It is effective in shortening the molding cycle.

It is convenient to use a high frequency power source of about 1 to 1000 KHz.

The release film is a synthetic resin film, for example, polyolefin such as polyethylene and polypropylene, polycarbonate, polyamide, polyvinyl fluoride, polyester,
Film such as polyimide (for example, Kapton brand name) 0.
It is convenient to use a diameter of 01 to 1.0 mm. Further, a mold releasing agent such as silicone or epoxidized soybean oil may be applied to the mold without using the mold releasing film.

〔Example〕

 Next, examples will be shown.

Example 1 A lens of a fog lamp for automobiles having a substantially rectangular and dish-shaped cross section of 8 cm × 10 cm as shown in FIG. 1 was molded. The main structure of the mold is as shown in FIG. 1 and described above. A polyimide film was used as the release film A in FIG. 1, and a DAP resin was used as the thermosetting resin. The composition of DAP resin is 94 parts of DAP prepolymer (2 to 20 mer), DAP
6 parts of monomer and 3 parts of benzoyl peroxide are dissolved in 100 parts of acetone.
After applying it to a thickness of 03 mm and air-drying it for 1 hour at room temperature, fix the film on the pin 11 of the mold, close the mold, and use AS resin (acrylonitrile-styrene copolymer) as the thermoplastic resin. It was injected into the mold at a temperature of 240 ° C. Then, a high-frequency current of 7KHz, 20KW is intermittently applied to the coil 3 at intervals of 15 seconds, the temperature of the cavity plate and the core plate is kept at 150 ° C for 2 minutes, the DAP resin is completely cured, and then the mold is formed. After cooling water was passed through to cool and solidify the composite resin, it was released from the mold, and the release film was peeled off to obtain an intended composite molded article.

In this case, it is sufficient to heat only the cavity plate 1 to cure the DAP resin, but in order to prevent warping of the molded product, the core plate 2 is also heated to almost the same temperature, and the cavity plate and the core plate are heated. It is effective to perform the cooling at the same time.

As a result of observing the cross section of this composite molded product with a microscope, the gate part is slightly thin at 0.008 mm, but the others are about 0.010 to 0.
It was confirmed that a 012 mm DAP resin layer was laminated.

In addition, the result of cross-cut cellophane tape peeling test for the adhesiveness of the DAP resin was 0/100, and it did not peel at all, and sufficient adhesiveness was obtained. The surface hardness of the DAP resin layer is 3-4H in pencil hardness.
The surface hardness F to H of the AS resin portion is remarkably improved. Compared with conventional fog lamps and lenses that use glass, the lens of the composite resin molded product of this embodiment is lighter in weight, has better impact resistance due to flying stones, and above all, has more freedom in design, improved productivity, etc. The benefits are immeasurable.

Example 2 An automobile headlamp lens having a size slightly larger than that of Example 1 but having a similar shape was produced. A DAP-impregnated sheet was used as the thermosetting resin. The DAP was a vinylon non-woven fabric containing 80 parts of DAP prepolymer, 3 parts of DAP monomer, 5 parts of benzoyl peroxide, 20 parts of unsaturated polyester and 10 parts of acetone.
What was melt-impregnated to 0 part was used. As the thermoplastic resin, a glutaric anhydride copolymer heat-resistant acrylic-styrene resin having a heat distortion temperature (HDT) of 115 ° C. (the method for producing this resin is described in detail in JP-A-60-120707).

First, release polyimide film and 0.05 mm thick DAP-impregnated sheet are fixed in the cavity with stacking pin 11, and the mold is closed.
The heat-resistant acrylic-styrene type resin is 250 ℃
It was injected into the mold. Therefore, the polyimide film and the DAP-impregnated sheet are shaped into a cavity by this resin filling. Next, a high-frequency current was passed through the coil, the cavity plate and core plate were held at 150 ° C for 2 minutes to completely cure the DAP resin, and then cooled and released to obtain the desired composite resin headlamp lens. .

The headlamp lens was a composite resin hedlamp lens having a uniform DAP resin layer with a thickness of 0.15 mm with almost no uneven thickness.

According to the result of the adhesive cellophane peeling test, this lens did not peel at all, and had a surface hardness of 3 to 4H, which was sufficiently practical.

Further, since the molded product of the present invention was compounded with DAP, the practical heat distortion temperature was 5 to 10 as compared with the case where DAP was not compounded.
It was also found to be improved by ° C.

Example 3 An approximately circular cosmetic compact case having a rounded shape with a diameter of about 10 cm was prepared. The compact is unsaturated on the paper printed with various patterns for the purpose of giving decorativeness and surface hardness so that it is hard to be scratched even if it is rubbed with metal parts such as brooches and earrings in the handbag during use. Using a resin impregnated with a polyester resin, the impregnated paper was stuck to the central portion of the surface of about 9 cm to form a laminated composite, and an ABS resin was used as a base resin.

A fine vacuum hole was provided in the core of the die, and the center direct gate was used to embed the coil in substantially the same manner as in Example 1.

A usual mold release agent was sprayed on the mold, and the unsaturated polyester resin-impregnated paper was vacuum-sucked and attached to the core plate mold.
The unsaturated polyester resin is an isophthalic acid type unsaturated polyester resin used in ordinary BMC and the like, to which a small amount of styrene mono-, zinc stearate, and a peroxide catalyst are added.

After mounting this impregnated paper on the mold, ABS resin
It is injected into the mold at ℃, then a high-frequency current is passed through the coil, the mold is held at 160 ℃ for 90 seconds, the unsaturated polyester resin is cured, then the mold is cooled and released. A compact case having a surface hardness that is excellent in decorativeness was obtained.

The hardness of the surface of the carp compact case is 3H in pencil hardness, which is significantly superior to the hardness B of the base ABS resin.
The cross-cut / cellophane tape peeling test result was 0/100, and the adhesion strength was good.

〔The invention's effect〕

According to the method of the present invention, a combination that cannot be compounded by the conventional method due to the relationship between the curing temperature condition of the thermosetting resin and the heat distortion temperature of the thermoplastic resin can be compounded and completely cured. A composite molded article in which the thermosetting resin and the thermoplastic resin are firmly bonded to each other is obtained. As a result, it is possible to obtain a molded article having excellent surface hardness, heat resistance, flame resistance, chemical resistance, abrasion resistance, weather resistance and the like, which are not conceivable only with a thermoplastic resin.

Further, according to the method of the present invention, a composite molded article having a complicated surface shape can be easily obtained. Also, only on the surface of a part of the molded product,
Those having the above-mentioned various properties are easily obtained and are economical.

Also, if only the shaping surface of the mold is subjected to high frequency induction heating,
The cooling cycle is short, the temperature is easily controlled, and the degree of curing of the thermosetting resin on the composite surface is also easily controlled.

[Brief description of drawings]

FIG. 1 is an example of a schematic conceptual view of a cross-sectional view of a composite injection molding die used in the present invention. A: Release film B: Uncured thermosetting resin 1 ... Cavity plate 2 ... Core plate 3 ... Coil 4 ... High-frequency sealing layer 5 ... Fixed-side template 6 ... Movable-side template 7 ... Mounting plate

Claims (2)

[Claims] 1. A method of composite molding with a thermoplastic resin by allowing an uncured thermosetting resin to exist at a desired position in a mold of an injection molding machine, injecting a molten thermoplastic resin into the mold, A composite injection molding method, characterized in that the molding surface is cooled and released after the thermosetting resin is completely cured by high-frequency induction heating the molding surface. 2. An uncured thermosetting resin existing in a mold is applied in a liquid state on the shaping surface of the mold or attached in a sheet state, and is also applied by injection of a thermoplastic resin during application or attachment. The method according to claim 1, wherein the injection filling of the molten thermoplastic resin is performed in a semi-cured state in which the curing is advanced to such an extent that the shape is retained.