JP2002240086A - In-mold coated injection molded item - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-mold coated injection molded item capable of preventing quality deterioration of an injection molded item due to a bad phenomenon such as a material loss and the like and keeping smoothness of a designed surface. SOLUTION: A side molding base 2 is made of a resin and a boss 2b as a thick portion is formed around the center of its reverse surface. The resin to be used has a forming shrinkage ratio in the range of 4/1,000 to 30/1,000 and a linear expansion coefficient in the range of 4×10-5 to 20×10-5/ deg.C and is preferably a crystalline resin such as PP(polypropylene). The side molding base 2 is molded by means of an in-mold injection molding method. After the side molding base 2 is injection-molded, a coating liquid is filled in a space between a cavity surface 7 of an upper mold and the surface of the side molding base 2. Thereafter, the molds are closed again before the coating liquid is completely cured whereby the coating agent on the side molding base 2 is let to contact the cavity surface 7 under a pressure to make the surface of the coated portion 3 of the side molding smooth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-mold paint injection-molded product molded by an in-mold paint injection molding method, and more particularly to an in-mold paint injection molded product suitable as a resin product to be attached to an automobile. Things.

[0002]

2. Description of the Related Art Currently, many exterior resin products are attached to vehicles, and one of the exterior resin products is one of them.
For example, there is a side mall. Generally, a side molding is used for the purpose of protecting and decorating a vehicle body, and is attached to a side surface of a body of a vehicle.

Conventionally, a long side molding has been manufactured by an injection molding method or an extrusion molding method using a mold.
If the cross-sectional shape of the side molding is constant, it can be formed by an extrusion molding method. However, resin products having a non-constant cross-sectional shape of a vehicle exterior resin product are formed by an injection molding method. Generally, a coating process such as painting is performed on an injection molded product. Then, after the side molding substrate is removed from the mold, a paint is applied to the surface of the side molding substrate by a spray gun, and the side molding is completed. In addition, in the side molding, in the cross-sectional shape in the width direction, a solid side molding that is entirely filled with resin, a side molding that is hollowed out for weight reduction, and a side molding that is hollowed out. There is a side molding or the like provided with a thick portion such as a boss to improve the strength.

However, in a side molding provided with a thick portion such as a boss or the like, after the resin is injected into a mold, the reinforcing material provided on the side molding substrate is formed in a process of cooling and hardening the side molding substrate. On the upper surface of a thick portion such as a boss, sinking of a depression phenomenon occurs on the surface of the side molding base material due to molding shrinkage.

FIG. 4 is a schematic diagram showing an enlarged view of the surface of the side molding base material 51 where paint has been applied to the surface of the side molding base material 51 on which sink marks have been generated by the spray gun. As described above, when the coating section of the side molding 50 is enlarged, in the coating by the spray gun, the sink mark 51a is formed by the coating portion 52.
Has even affected the surface. Furthermore, it is 5 by paint
1a was emphasized, and the appearance quality was deteriorated. This is because, when the paint is coated on the sink mark 51a generated by the molding shrinkage, the paint coating portion 52a corresponding to the upper portion of the sink mark 51a looks dark and is emphasized due to irregular reflection of light.

[0006] As described above, even when a coating solution is applied by a spray gun or the like to a molded article substrate on which sink marks or the like have been generated, irregularities are formed on a painted portion of an injection molded article, and the molded article is applied as an exterior resin product. It was difficult to do. Further, since the coating with a spray gun or the like is performed after the molded article base material is removed from the mold, there is a problem that the number of steps increases.

As a method for coating a resin molded article substrate, there is an in-mold coating method in which coating is performed in a cavity of a mold. However, even in the in-mold coating method, sink marks may be formed on the design surface of the injection molded product. As a method of preventing sink marks by this in-mold coating method, for example, JP-A-5-30
No. 1251 is disclosed. In this method, PC (polycarbonate) and PET (polyethylene terephthalate) which become FRP materials as molding resin materials are used.
Alloy containing 10% glass fiber. After the molding resin is molded in the mold, paint is injected between the mold inner surface and the molding resin, and after the paint is cured, the molded product is taken out to prevent sink marks on the design surface of the molded product. Have been.

[0008]

However, in this publication, PC and PET alloy materials (molding shrinkage ratio is 3/100
0, the coefficient of linear expansion is 3.5 × 10 ^-5 / ° C.), and only those containing glass fibers are described. When molded with another resin material, sink marks may be formed. is there.
In particular, in the case of large sink marks, it was difficult to cover the sink marks by the in-mold coating method to prevent the influence on the coated portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to prevent a deterioration in the design quality of an injection-molded product due to a defective phenomenon such as sink marks and to secure the gloss of the design surface. An object of the present invention is to provide an in-mold coating injection molded product.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a molded article substrate provided with a thick part is coated in a mold cavity in a mold cavity. A molded injection molded product, wherein the resin used for the molded product substrate of the in-mold painted injection molded product has a molding shrinkage of 4/1000.
３０30/1000, and the glossiness measured by the JISZ8741 specular glossiness measuring method of the coated portion applied to the molded article base material is 60 ° or more. ADVANTAGE OF THE INVENTION According to this invention, the magnitude | size of the sink formed in a molded article base material can be predicted, and the influence on the design surface of an injection molded article is reduced by being formed small enough to be coatable with a coating agent. Also, the luster is secured. Therefore, quality deterioration of the design surface of the injection molded product is prevented.

According to a second aspect of the present invention, in the first aspect, the glossiness is 80 ° or more.
According to the present invention, luster is further secured. In the invention described in claim 3, in the invention described in claim 1 or claim 2, the linear expansion coefficient of the resin is 4 × 10 ^{−5 to} 20.
× 10 ^-5 / ° C. According to the present invention, since the size of the sink is predicted, it is easy to adjust the opening amount for injecting the coating solution, the injection amount of the coating solution, and the film thickness of the injection molded product.

According to a fourth aspect of the invention, in the first aspect of the invention, the resin is a crystalline resin. According to the present invention, the deterioration of the design surface of the injection molded product can be prevented even with the crystalline resin.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is embodied in a side molding will be described below with reference to FIGS.

As shown in FIG. 2, a side molding 1 as an in-mold coating injection molded product is formed by a side molding base 2 as a molded product base and a coating portion 3 applied to the surface thereof. I have. In addition, the glossiness of the coating part 3 measured by the JISZ8741 specular glossiness measuring method is 60 ° or more, preferably 80 ° or more. The side molding base material 2 is formed of resin, has a concave portion 2a on the back surface, and has a boss 2b as a thick portion near the center.
As the resin used for the side molding base material 2, the molding shrinkage of the resin is in the range of 4/1000 to 30/1000,
A resin having a coefficient of linear expansion of 4 × 10 ^{−5 to} 20 × 10 ⁻⁵ / ° C. is used. As the resin, a crystalline resin is preferable, but an amorphous resin may be used. For example, crystalline resins include PE (polyethylene), PP (polypropylene), PA (nylon) and the like, and amorphous resins include PC (polycarbonate), PMMA (polymethyl methacrylate), ABS resin, and TPE (polyethylene). Thermoplastic elastomer), modified PPO (polyphenylene oxide)
Etc.

Examples of the reactive coating solution include urethane acrylate oligomer, epoxy acrylate oligomer, styrene, zinc stearate, titanium oxide, carbon black, 8% cobalt octoate, t
A mixture of -butylperoxybenzoate and the like is used, and is colored with various pigments. In addition, a metal flake-like fine powder of aluminum, copper, or the like may be mixed with the above coating solution as a brightening agent and used for metallic coating. Further, as another brightener, an aluminum silicate mineral may be mixed with the above coating agent solution and used for mica coating.

As shown in FIGS. 1 (a) to 1 (c), an injection molding apparatus used for manufacturing the side molding 1 has a mold 4
The fixed upper die 5 and the movable lower die 6 are provided so as to face each other. The mold 4 is configured such that the lower mold 6 is moved upward from the state where the lower mold 6 of the movable mold is opened, and clamped.

The upper mold 5 has a recess 5a, and the lower mold 6
Is formed with a recess 6a for forming the boss 2b of the side molding base material 2. A space including the concave portion 5a and the concave portion 6a sandwiched between the upper die 5 and the lower die 6 becomes a cavity 7 for forming the side molding 1. A gate 8 and a paint gate 9 communicating with the cavity 7 are formed in the mold 4. The mold 4 has a discharge hole (not shown) for discharging air in the cavity 7.

As shown in FIG. 1A, a resin injection device 2
The resin from 0 can be injected into the cavity 7 through the gate 8. When the lower mold 6 is moved downward in the figure, the coating gate 9 is configured to communicate with the cavity 7.
Is injected into the cavity 7 through the coating gate 9. Gate 8
The coating gate 9 is formed not in the same plane but in a shifted position in the longitudinal direction of the mold 4 (the direction perpendicular to the plane of FIG. 1).

Next, a method of manufacturing the side molding 1 will be described. First, the mold 4 is opened and a release material is applied to the inner wall surface of the cavity 7. Next, as shown in FIG.
The mold 4 is clamped so that the upper mold 5 and the lower mold 6 are closed.

Next, a resin is injected into the cavity 7 from the resin injection device 20 through the gate 8, and the side molding base material 2 having the same shape as the cavity 7 is injection-molded. As shown in FIG. 1 (b), after curing of the side molding base material 2, the mold 4 forms a space between the upper mold 5 and the lower mold 6 for injecting a coating solution, and The mold 6 is moved downward, and is slightly opened. This allows
A space is provided between the surface of the cavity 7 of the upper die 5 and the surface of the side molding base material 2. FIG. 1B shows the upper mold 5
In order to make it easy to see how the lower mold 6 and
The gap between the side molding base material 2 and the surface of the cavity 7 is shown large. FIG. 1B shows a cross section at a location different from FIG. 1A.

When the lower die 6 is moved downward, the coating gate 9 can be communicated with the cavity 7, and the coating material injection device 21 passes through the coating gate 9 to connect the surface of the cavity 7 to the side molding base material 2. The space provided between the surface and the surface is filled with the coating solution. At this time, cavity 7
The air inside is discharged to the outside of the cavity 7 through the discharge hole.

As shown in FIG. 1C, after filling the coating solution and before the coating is completely cured, the side molding substrate 2
The lower mold 6 is again moved upward so as to narrow the gap between the lower mold 6 and the cavity 7. At this time, the coating agent on the surface of the side molding base material 2 is pressed against the surface of the cavity 7, and the surface of the coating portion 3 of the side molding 1 is smoothed. Then, after the coating portion 3 is completely cured, the mold 4 is opened, and the side molding 1 is taken out.

As shown in FIG. 3, the side molding 1 is smoothed by transferring the surface of the cavity 7 to the coating portion 3 even when the sink 2c is formed on the surface of the side molding base 2 by molding shrinkage. As a result, the side molding 1 having the excellent design properties (color tone, gloss, etc.) of the painted portion 3 is formed.

In the manufacturing process of the side molding 1,
When the resin used for the side molding base material 2 has a large molding shrinkage when the resin is cooled and hardened after the resin is completely injected into the cavity 7, the sink marks 2c are formed on the design surface side of the thick portion such as the boss 2b. It may be done. However, the molding shrinkage of the resin used for the side molding base material 2 is 4/1000 to 3
By being within the range of 0/1000, the size of the sink mark 2c formed on the side molding base material 2 is formed to a size that can be covered with the coating agent, so that the side molding 1
The effect on the design surface is reduced. Further, by predicting the size of the sink mark 2c, the mold opening amount for injecting the coating solution, the injection amount of the coating solution, and the film thickness of the injection molded product are adjusted.

This embodiment has the following effects. (1) Since the molding shrinkage ratio of the resin used for the side molding base material 2 is within the range of 4/1000 to 30/1000, the resin can be coated with a coating agent to have a sink mark 2c.
Is formed small, it is possible to prevent the quality of the design surface of the side molding 1 from deteriorating.

(2) Since the molding shrinkage of the resin used for the side molding base material 2 is within the range of 4/1000 to 30/1000, the size of the sink mark 2c and the molding shrinkage cause the upper mold 5 to shrink. The space provided between the surface of the cavity 7 and the surface of the side molding base material 2 can be predicted, and the adjustment of the mold opening amount and the coating agent injection amount required for injecting the coating agent solution can be simplified. it can.

(3) When the gloss of the painted portion 3 of the side molding base material 2 is 60 ° or more, the gloss of the painted portion 3 can be secured, and the design surface of the side molding 1 can be prevented from lowering. (4) After filling the coating solution, the mold is re-clamped before the coating is completely cured, and the inner surface shape of the cavity 7 is transferred to the coating portion 3 of the side molding 1, so that the design of the side molding 1 Surface quality can be improved. That is,
Even when the sink 2c is formed on the side molding base 2 by the boss 2b, the design surface of the side molding 1 can be smoothed.

(5) After filling the coating solution, the mold is re-clamped before the coating is completely cured, so that the coating portion 3 of the side molding 1 is pressed against the cavity 7 surface.
It is possible to improve the coating force of the coating agent as compared with the coating with a spray gun.

(6) By performing injection molding, it is possible to cope with a resin product having a complicated shape. In addition, variation in dimensions can be suppressed as compared with extrusion molding. The embodiment is not limited to the above, and may be changed as follows, for example.

In the above embodiment, the boss 2b is described as a thick portion, but the thick portion may be a rib or a clip seat. Even in the case of such a configuration, even when sink marks occur on the design surface side of the base material corresponding to the ribs and clip seats, the base material can be covered with the coating agent, and the quality of the design surface can be prevented from deteriorating.

In the above-described embodiment, the gate 8 into which the resin is injected and the coating gate 9 into which the coating solution is injected are different from each other. 7 may be filled. In the case of such a configuration, by setting the injection point at one location, it is possible to reduce a defect phenomenon, for example, a burr formed on the injection molded product.

In the above embodiment, injection molding is used, but two or more monomers are mixed in a head and simultaneously injected into a mold to complete a polymerization reaction in the mold to obtain a product. You may change to reaction injection molding. Also in this case, the side molding base material 2 formed by reaction injection molding is used.
Then, a coating solution can be applied.

The injection molded product molded according to the above embodiment may be formed of another member, for example, an instrument panel or a bumper, instead of the side molding. In this case, since injection molding can cope with a complicated shape, an instrument panel, a bumper, and the like can be easily manufactured.

The coating solution may be implemented by appropriately changing the components thereof. In this case, a suitable color, a suitable coating thickness, and the like can be adjusted. Next, technical ideas that can be grasped from the above embodiment will be described below.

(1) A method for producing an in-mold coated injection molded product in which coating is performed in a cavity of a mold on a molded product substrate provided with a thick portion, wherein the in-mold coated injection molded product is molded. Molding shrinkage of the resin used for the product base is 4 / 1000-
At 30/1000, a space is formed by molding shrinkage of the molded article base material, and in addition to the space, a coating solution is injected into a space formed by opening the mold slightly after curing the molded article base material, A method for producing an in-mold coated injection-molded article, wherein the mold is re-clamped before the coating solution after filling the solution is completely cured.

(2) In the invention according to any one of the first to third aspects, the injection molding is a reaction injection molding.

[0037]

As described above in detail, according to the first to third aspects of the present invention, it is possible to prevent the quality of the design surface of an injection molded product from being deteriorated due to a defective phenomenon such as sink marks and to improve the design surface. Gloss can be secured.

[Brief description of the drawings]

1A is a schematic cross-sectional view of an injection mold, FIG. 1B is a schematic cross-sectional view showing the operation of injection molding, and FIG. 1C is a schematic cross-sectional view of the same after re-clamping.

FIG. 2 is a perspective view of a side molding.

FIG. 3 is a partial schematic sectional view of a side molding.

FIG. 4 is a partial schematic cross-sectional view of a side molding formed by a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Side molding as an in-mold coating injection molded product, 2 ... Side molding base material as a molded product base material, 2a ... Boss as a thick part, 4 ... Die, 7 ... Cavity.

Continued on the front page (72) Inventor Hiromi Hyuga 1 Ochiai Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Inc. F term (reference) 4F206 AA04 AA11 AA42 AD11 AF14 AG03 AH23 JA07 JB23 JF01 JN31

Claims (4)

[Claims] An in-mold coating injection-molded product in which coating is performed in a cavity of a mold on a molded product substrate provided with a thick portion, wherein the molded product substrate of the in-mold coating injection molded product is provided. The molding shrinkage of the resin used is 4/1000 to 30/1000, and the JISZ874 of the painted portion applied to the molded product base material
(1) An in-mold coating injection-molded product, wherein the glossiness measured by the specular glossiness measurement method is 60 ° or more. 2. The injection molded article according to claim 1, wherein the glossiness is 80 ° or more. 3. The resin has a coefficient of linear expansion of 4 × 10 ^-5 to 2
The in-mold coated injection molded product according to claim 1 or 2, wherein the temperature is 0 × 10 ^-5 / ° C. 4. The in-mold coating injection-molded article according to claim 1, wherein said resin is a crystalline resin.