JP2010234647A - Method for manufacturing in-mold coated article and die used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an in-mold coated article, which is free from problems including an appearance defect due to built-up air or insufficient hardening of a thermosetting coating layer. <P>SOLUTION: A die for forming an in-mold coated article is used wherein a suction port is disposed in the molding cavity forming portion of a rear surface forming die. A molded article is projected out from the rear surface forming die, whereby a communicating space portion is formed between the molded article and the rear surface forming die, so that coating cavity communicates with the suction port. After air is sucked through the suction port, a thermosetting coating material is injected to the coating cavity to form a thermosetting coating layer on the surface of the molded article. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an in-mold coated product used as a front panel or case, button, automobile instrument panel, button, or the like of AV equipment or home appliances.

As a conventional method for manufacturing an in-mold coated product, an in-mold coated product forming mold including a surface forming mold 101, a coating film forming mold 102, and a back surface forming mold 103 is used. Japanese Patent Application Laid-Open No. H10-228707 discloses a technique for forming the above.
(1) When the molding cavity 104 is formed by the front surface forming mold 101 and the back surface forming mold 103, the molded product 108 is injection-molded by filling a molding resin (see FIG. 3A).
(2) With the back surface forming mold 103 holding the molded product 108, the mold facing the back surface forming mold 103 is switched from the surface forming mold 101 to the coating film forming mold 102, and a gap is formed on the surface of the molded product 108. The coating cavity 105 is formed by (see FIG. 3B),
(3) A decorative thermosetting paint made of a liquid thermosetting composition is injected into the coating cavity 105, and a thermosetting paint layer 109 is formed on the surface of the molded article 108 to form the in-mold coated article 110. It forms (refer FIG.3 (c)).

Japanese Patent No. 3998660

  However, in the conventional method for producing an in-mold coated product, an air pocket in the mold is generated when the thermosetting paint is injected into the coating cavity, thereby causing an appearance defect of the in-mold coated product 110 or a thermosetting paint layer. In some cases, 109 was insufficiently cured (due to oxygen inhibition in the radical polymerization reaction).

  In general, when forming a resin molded product, an air vent is formed on the mold parting surface in order to prevent air accumulation, and the air in the cavity is evacuated when filling the molding resin. The method of discharging can be taken. However, if a mold parting surface is formed to fill the thermosetting paint when forming an in-mold coated product, the thermosetting paint has a very low viscosity of several tens of cps. Since the paint leaks out from the vacant part when it is filled and hardens, and as a result, burrs are generated on the outer periphery of the in-mold coated product 110, it is not possible to adopt a method of forming an vacancy on the mold parting surface. .

  The present invention relates to a method for producing an in-mold coated product and a gold used for the same so as not to cause a problem of poor appearance due to air accumulation at the time of forming a thermosetting coating layer and insufficient curing of the thermosetting coating layer. The purpose is to provide a mold.

  In order to achieve the above object, the present invention has the following features.

The in-mold coated product forming mold of the present invention comprises a surface forming mold, a coating film forming mold, and a back surface forming mold,
A molded product can be formed with a molding cavity formed by a back surface forming mold and a surface forming mold,
A thermosetting paint layer can be formed on the surface of the molded product in the coating cavity formed by the back surface forming mold and the coating film forming mold that hold the molded product.
The suction port is arranged on the molding cavity forming surface of the back surface forming mold.

Moreover, the manufacturing method of the in-mold coated product of the present invention uses the in-mold coated product forming mold of the above invention,
When the molding cavity is formed by the front surface mold and the back surface mold, the molded product is injection-molded by filling the molding resin,
In the state where the back surface forming mold holds the molded product, the mold facing the back surface forming die is switched from the surface forming die to the coating film forming die, and a coating cavity is formed by a gap on the surface of the molded product.
The molded product is protruded from the back surface forming mold to form a communication space between the molded product and the back surface forming mold, thereby communicating between the coating cavity and the suction port,
A thermosetting paint layer is formed on the surface of the molded product by injecting a thermosetting paint into the coating cavity after air suction from the suction port.

  In the above invention, the communication space may be formed by protruding the molded product from the back surface forming mold by 0.01 to 0.03 mm.

  In the method for producing an in-mold coated product of the present invention, the communication cavity formed on the back side of the molded product communicates between the coating cavity and the suction port, and after the air is sucked from the suction port, the thermosetting paint is applied to the coating cavity. inject. Therefore, since the inside of the coating cavity can be made close to a vacuum state, air accumulation does not occur when the thermosetting paint layer is formed, and thus an in-mold coated product having excellent design properties and sufficient surface hardness can be obtained.

It is sectional drawing which shows the process of forming an in-mold coated article with the manufacturing method of the in-mold coated article of this invention. It is the schematic of the coating material injection machine used for the manufacturing method of the in-mold coating product of this invention. It is sectional drawing which shows the process of forming the in-mold coated goods with the manufacturing method of the conventional in-mold coated goods.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  The mold used in the method for producing an in-mold coated product of the present invention includes a surface forming mold 1, a coating film forming mold 2, and a back surface forming mold 3, and the back surface forming mold 3 and the surface forming mold 1. The molded product 22 can be formed by the molding cavity 12 formed by the above, and the surface of the molded product 22 is heated by the coating cavity 13 formed by the back surface forming mold 3 holding the molded product 22 and the coating film forming mold 2. The curable paint layer 21 can be formed, and the suction port 4 is arranged on the molding cavity forming surface of the back surface forming mold 3 (see FIG. 1).

  The back surface forming mold 3 is used to form the back surface shape of the molded product 22. The surface forming mold 1 is used for forming the surface shape of the molded product 22. In order to form the in-mold coated product 23, first, the molded product 22 is formed by filling the molding cavity 12 formed by the back surface forming die 3 and the front surface forming die 1 with a molding resin (FIG. 1A). )reference). Here, the size of the suction port 4 arranged on the molding cavity forming surface is set such that a molding resin having a high viscosity does not enter.

  The coating film forming mold 2 is designed so that its outer shape is larger than that of the surface forming mold 1 and a portion that does not contact the molded product 22 can be formed. This non-contact portion corresponds to the coating cavity 13. After forming the molded product 22, the mold facing the back surface forming mold 3 is switched from the surface forming mold 1 to the coating film forming mold 2 while the back surface forming mold 3 holds the molded product 22. A coating cavity 13 with a gap is formed on the surface. Then, by operating the ejector pin 31, the molded product 22 is protruded from the back surface forming mold 3 by a minute amount, and the communication space portion 14 is formed between the molded product 22 and the back surface forming mold 3. Communication with the suction port 4 is established (see FIG. 1B).

  Subsequently, air is sucked from the suction port 4 to close the inside of the coating cavity 13 to a vacuum state. In this state, a decorating thermosetting paint made of a liquid thermosetting composition is injected into the coating cavity 13 from a paint injecting machine 41 to be described later, and the thermosetting paint layer 21 is formed on the surface of the molded product 22 ( (Refer FIG.1 (c)).

  Here, the minute amount of the molded product 22 protruding from the back surface forming mold 3 in order to form the communication space portion 14 is preferably 0.01 to 0.03 mm. If it is less than 0.01 mm, the thickness of the communication space portion 14 becomes thin, and the air inside the coating cavity 13 may not be sufficiently sucked, which may cause air accumulation. Moreover, if it exceeds 0.03 mm, the thickness of the communication space part 14 will become thick, and there exists a possibility that a thermosetting coating material may flow into the suction port 4 and may block the suction port 4, and an air pool may arise. When the protrusion amount is set within this range, the thermosetting paint can be filled in the coating cavity 13 having a thickness of about 0.1 mm, while the entire coating cavity 13 is quickly filled, but the communication is a space thinner than the coating cavity 13. In the space portion 14, it can be heated quickly so that the viscosity is increased and does not reach the suction port 4.

  After completion of the suction, the ejector pin 31 is operated in the opposite direction to return the molded product 22 to the back surface forming mold 3 side (see FIG. 1D). Since the molded product 22 is once released from the back surface forming mold 3, a slight gap remains between the molded product 22 and the back surface forming mold 3, but the thermosetting paint in this gap is immediately heated. Harden. Further, since the thermosetting paint in the gap portion is formed in close contact with the back surface of the molded product 22, the appearance is not affected, and post-treatment such as deburring is unnecessary.

  When the thermosetting paint layer 21 is completely cured, no air is trapped in the thermosetting paint layer 21 in the coating cavity 13, so that an in-mold coated product 23 having excellent design and sufficient surface hardness can be obtained. it can.

  Hereinafter, materials and apparatuses other than the in-mold coated product forming mold used for forming the in-mold coated product 23 will be described.

  As a material for the thermosetting paint, for example, an oligomer such as a urethane acrylate oligomer having at least two (meth) acrylate groups, an epoxy acrylate oligomer, or a resin thereof, which uses an organic peroxide as an initiator for the curing reaction, or 20 to 70% by weight of unsaturated polyester resin, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic acid, acetic acid The main component is a vehicle component composed of 80 to 30% by weight of a copolymerizable ethylenically unsaturated monomer such as vinyl, tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, and styrene. ,aluminum Fee, pearl pigment, one made of release agent and light stabilizers, etc. may be used.

  The paint injection machine 41 applies pressure to the upper part of the paint tank 43, and an accurate amount of thermosetting paint for one shot is sent from the paint tank 43 to the paint injection unit 42 having the structure of metering / injection / valve. It has a structure (see FIG. 2).

  As the position setting of the coating material injection unit 42, it may be provided inside the coating film forming mold 2. Alternatively, a thermosetting paint injection port provided in the coating film forming mold 2 may be provided on the mating surface with the back surface forming mold 3 so that the paint injection unit 42 and the resin injection unit of the resin injection machine are vertical. Good. In this case, the back surface forming mold 3 holding the molded product 22 and the coating film forming mold 2 are closed, and the coating cavity 13 for coating the molded product 22 with a thermosetting paint is applied to the molded product 22. In the stage formed between the film forming mold 2 and the coating material injection unit 42 moves forward and directly touches the coating film forming mold 2, and the paint gate is provided with the thermosetting paint on the coating film forming mold 2. Through the coating cavity 13.

  The molding resin is not particularly limited, such as a normal thermoplastic injection molding resin or engineering plastic, or a thermosetting molding resin material, but is preferably one that is easy to mold and has good adhesion to the thermosetting paint. Specific examples include acrylonitrile butadiene styrene resin (ABS resin), polyamide resin, polyethylene resin, polyester resin, polypropylene resin, polybutylene terephthalate resin, and polycarbonate resin.

  The molding resin is filled into the molding cavity 12 by a resin injection machine. An injection molding machine can be used as the resin injection machine.

  The in-mold coated product forming mold of the present invention includes a plurality of back surface forming molds 3 and can be arranged on a movable plate or an injection molding machine for two-color molding in which a rotating plate attached to the movable plate rotates (not shown). ) As a mold arrangement in the injection molding machine, the front surface forming mold 1 and the coating film forming mold 2 are fixed to a stationary platen, and the back surface forming mold 3 is attached to the movable platen of the injection molding machine or a rotating plate on the movable platen. Fix it. Alternatively, the back surface forming mold 3 may be fixed to a stationary platen, and the front surface forming die 1 and the coating film forming die 2 may be fixed to a movable plate of an injection molding machine or a rotating plate attached to the movable platen. When installed in this way, while the molded product 22 is formed by a certain back surface forming mold 3 and the front surface forming die 1, thermosetting is performed by the back surface forming mold 3 and the coating film forming die 2 holding another molded product 22. The in-mold coated product 23 can be manufactured at the same time as forming the conductive paint layer 21, that is, forming the molded product 22.

  An in-mold coated article 23 was manufactured using an in-mold coated article forming mold including a surface forming mold 1, a coating film forming mold 2, and two back surface forming molds 3. As the coating film forming mold 2, a coating film injection unit 42 having a paint injection port was used. A back surface forming mold 3 having a suction port 4 on the forming cavity forming surface was used. For the production of the in-mold coated product 23, an injection molding machine for two-color molding in which a rotating plate attached to a movable plate rotates was used.

  A molded cavity 12 formed by closing the back surface forming mold 3 facing the surface forming mold 1 with respect to the surface forming mold 1 is filled with a heat-melted solid heat-resistant ABS resin, and cooled and solidified to form a molded product. 22 was formed (see FIG. 1A). Next, the turntable of the injection molding machine is rotated, and the mold facing the back surface forming mold 3 is switched from the surface forming mold 1 to the coating film forming mold 2 while the back surface forming mold 3 holds the molded product 22. Then, the back surface forming mold 3 and the coating film forming mold 2 were closed to form a coating cavity 13 for coating the molded product 22 with a thermosetting paint. Then, the molded product 22 is protruded from the back surface forming mold 3 by the ejector pins 31 to form a communication space portion 14 between the molded product 22 and the back surface forming mold 3, thereby forming a space between the coating cavity 13 and the suction port 4. It was made to communicate (refer FIG.1 (b)). After air suction from the suction port, a thermosetting paint (Praglas 8000 manufactured by Dainippon Paint Co., Ltd.) is injected into the coating cavity 13 to form a thermosetting paint layer 21 (see FIG. 1C). Then, the thermosetting paint layer 21 was cured to form an in-mold coated product 23 (see FIG. 1 (d)).

  Since the thermosetting paint was injected into the coating cavity 13 after making the inside of the coating cavity 13 close to a vacuum state by air suction from the suction port 4 via the communication space portion 14, the thermosetting paint layer 21 was formed. Since no air accumulation occurred, the obtained in-mold coated product 23 was excellent in design and provided with sufficient surface hardness.

DESCRIPTION OF SYMBOLS 1 Surface forming die 2 Coating film forming die 3 Back surface forming die 4 Suction port 12 Molding cavity 13 Coating cavity 14 Communication space part 21 Thermosetting coating layer 22 Molded product 23 In-mold coating product 31 Ejector pin 41 Paint injection machine 42 Paint Injecting Unit 43 Paint Tank 101 Surface Forming Mold 102 Coating Film Forming Mold 103 Back Surface Forming Mold 104 Molding Cavity 105 Coating Cavity 108 Molded Product 109 Thermosetting Paint Layer 110 In-mold Painted Product

Claims (3)

Provided with a surface forming mold, a coating film forming mold and a back surface forming mold,
A molded product can be formed with a molding cavity formed by a back surface forming mold and a surface forming mold,
A thermosetting paint layer can be formed on the surface of the molded product in the coating cavity formed by the back surface forming mold and the coating film forming mold that hold the molded product.
A mold for forming an in-mold coating product, wherein a suction port is arranged on a molding cavity forming surface of a back surface forming mold. Using the in-mold coated product forming mold according to claim 1,
When the molding cavity is formed by the front surface mold and the back surface mold, the molded product is injection-molded by filling the molding resin,
In the state where the back surface forming mold holds the molded product, the mold facing the back surface forming die is switched from the surface forming die to the coating film forming die, and a coating cavity is formed by a gap on the surface of the molded product.
The molded product is protruded from the back surface forming mold to form a communication space between the molded product and the back surface forming mold, thereby communicating between the coating cavity and the suction port,
A method for producing an in-mold coated product, comprising: injecting a thermosetting paint into a coating cavity after air suction from a suction port to form a thermosetting paint layer on the surface of the molded product. The manufacturing method of the in-mold coating product of Claim 2 which protrudes 0.01-0.03mm from a back surface formation metal mold | die, and forms a communicating space part.

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