JP2001170964A - In-mold coating molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin, such as nylon or ABS resin, in an in-mold coating molding of an olefin resin such as polypropylene or polyethylene which could not adhere a coating film with a conventional paint. Provided is an in-mold coating molding method for forming a coating film that is tightly adhered simultaneously with molding in a mold using a conventional paint developed for resins and thermosetting resins. SOLUTION: Lamination molding is performed using a skin material having excellent adhesion to a paint to be used, and a molded product in which a skin material is bonded to a product surface is molded in a molding die. Following this state, the product surface of the bonded molded product is coated with a paint film by injecting paint between the product surface of the bonded molded product and the mold cavity surface of the molding die,
After the coating is cured in a mold, the molded product is taken out.
By doing so, a molded article in which a coating film having strong adhesion is integrally formed on the product surface can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called in-mold coating forming method (in-mold coating method) for forming a coating film on a product surface of an injection-molded article in a mold. The present invention relates to an in-mold coating molding method capable of eliminating a limitation on types of molding materials that can be used as a synthetic resin and using an optimal synthetic resin molding material for a purpose of using a molded product.

[0002]

2. Description of the Related Art In a conventional method for molding a coating in a mold, a synthetic resin molding material is injection-molded, and then a paint is injected into the mold, thereby coating the product surface of the injection-molded synthetic resin molded product. A molded product in which a coating is integrally formed on the product surface is obtained in a mold by coating with a coating of the product. In order to improve the quality of the molded product surface and reduce the number of coating steps, the appearance and surface It is used in the automotive industry, which has a high demand for quality, for manufacturing outer plates and exterior parts.

[0003]

However, the paint used for the molding of the thermoplastic resin in the mold is required to have a curing property that cures at a lower temperature than the paint for the thermosetting resin. In general, it is difficult to develop a paint that has the appearance and adhesion of the coating film. Some of the thermoplastic resins, such as nylon resin and ABS resin, that have already been developed as the paint used in the coating method in the mold. Paints for thermosetting resins or paints for thermosetting resins. For this reason, at present, the types of synthetic resins applicable to the in-mold coating molding method are limited to some thermoplastic resins such as nylon resins and ABS resins or thermosetting resins. Further, in the future, it is considered that it is extremely technically difficult to develop a paint having sufficient adhesion to an olefin resin such as a polypropylene resin or a polyethylene resin in terms of the structure of the resin. The present invention is in the development situation of the paint as described above, the object of the present invention is to eliminate the limitation of the type of molding material that can be used as a synthetic resin for the base material in the in-mold coating molding. Olefinic resins such as polypropylene resin and polyethylene resin that could not be adhered, nylon resin, AB
It is an object of the present invention to provide an in-mold coating forming method capable of forming a coating film having strong adhesion to a product surface simultaneously with molding in a mold using a paint developed for S resin or thermosetting resin. The purpose is.

[0004]

According to a first aspect of the present invention, there is provided a mold for obtaining a molded article having a coating film integrally formed on a product surface in the mold. In the coating molding method, after performing lamination molding using a skin material having excellent adhesion to a paint and a synthetic resin molding material as a base material, the surface of the skin material on the side opposite to the base material and the metal opposed thereto are formed. A paint is injected between the mold cavity surfaces to cover the surface of the skin material on the side opposite to the base material with the coating of the paint, and the coating is cured in a mold so that the coating is integrally formed on the product surface. The formed molded article was obtained.

In the second invention mainly based on the first invention, a synthetic resin molding material as a base material is a polypropylene resin or a polyethylene resin. Further, in the third invention mainly based on the first and second inventions, the base material side surface of the skin material has a detailed structure that can be welded to the base material by an anchor effect, and A skin material having a detailed structure in which the surface of the material opposite to the base material can be adhered to the coating film by an anchor effect was used.

[0006] In a fourth invention mainly comprising the first and second inventions, the skin material has a multilayer structure, and the material of the base material side surface layer of the multilayer structure skin material has an affinity for the base material. The surface material is a synthetic resin having high affinity and the material of the surface layer on the side opposite to the base material of the multilayer structure skin material is made of a synthetic resin having high affinity for the coating film. Further, in the fifth invention mainly based on the fourth invention, the skin material has a detailed structure in which the surface of the base material side of the multilayer structure skin material can be adhered to the base material by the anchor effect.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 relate to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of an in-mold coating forming apparatus,
FIG. 2 is a cross-sectional view of a molded product obtained by molding shown in Example 1, and FIG. 3 is a cross-sectional view of a molded product obtained by molding shown in Example 2.

As shown in FIG. 1, an in-mold coating forming apparatus 100 according to an embodiment of the present invention uses a general-purpose toggle-type injection molding machine. It is composed of a control device 30 and a mold 50.
The mold clamping device 10 includes a fixed platen 11 and a movable platen 12 on which a mold 50 is mounted. The movable platen 12 guided by the tie rods 14 and moved forward and backward by the mold clamping cylinder 13 advances and retreats with respect to the fixed platen 11. Thus, the mold 50 is configured to be opened and closed.

In the injection device 20, a screw 21 having a spiral flight portion is rotatably driven by a hydraulic motor 23 along the inner peripheral surface of a cylindrical barrel 22, and is disposed to be able to move forward and backward. The resin pellets supplied into the hopper 25 with the rotation of the screw 21
1, the resin pellets are heated by a heater (not shown) attached to the outer peripheral surface of the barrel 22 and kneaded by the rotation of the screw to melt the resin pellets. Screw 21
When the amount of the molten resin sent to the front of the screw 21 reaches a predetermined amount, the rotation of the hydraulic motor 23 is stopped, and the injection cylinder 24 is driven to advance the screw 21. The melted resin stored in the mold cavity 5 of the mold 50 passes through the nozzle 26.
3.

The mold 50 is provided with a fixed mold 51 attached to the fixed platen 11 and a movable mold 52 attached to the movable plate 12. A paint injecting machine 55 for injecting into the inside is provided. In addition, a skin material supply device for setting the skin material in the mold cavity 53 and a product removal device for removing a molded product are arranged around the mold 50.
In FIG. 1, illustration of the supply device and the product take-out device is omitted.

Next, the configuration of the control device 30 will be described. As shown in FIG. 1, an output signal from the molding device control unit 31 is sent to the mold clamping control unit 33 and the injection control unit 38 so that the operations of the mold clamping device 10 and the injection device 20 are linked. . The mold clamping control unit 33 includes a mold opening amount sensor 17,
Receiving each detection signal from the mold clamping force sensor 18 and the paint pressure sensor 54 and checking the operation state of the mold clamping device 10, receiving an output signal from the input condition setting unit 32,
Each operation control signal corresponding to the operation timing, the mold opening amount, and the mold clamping force is sent to the mold clamping servo valve 15. Similarly, the injection control unit 38 is configured to send an operation control signal to the injection servo valve 27 while checking the operation state of the injection device 20. On the other hand, the injector control unit 35 receives the output signal from the input condition setting unit 32,
Each operation control signal corresponding to the injection amount, the injection speed, the injection timing, and the injection pressure is sent to the paint injector 55.

The operation of the in-mold coating forming apparatus 100 configured as described above when performing in-mold coating forming will be described. After the skin material is set in the mold cavity 53 by a skin material supply device (not shown) while the movable mold 12 is held at the mold opening limit position, the operation control signal is sent from the mold clamping control unit 33 to the mold clamping servo valve 15. Is transmitted, and the movable mold 12 is advanced from the mold opening limit position by the mold clamping cylinder 13 to touch the fixed mold 11 while performing feedback control according to the mold closing speed pattern set in the input condition setting unit 32.

Subsequently, an operation control signal is transmitted from the mold clamping control unit 33 to the mold clamping servo valve 15, and feedback control is performed in accordance with the mold clamping force pattern set in the input condition setting unit 32 while the mold clamping cylinder 13 is being operated. To further advance the movable mold 12 to extend the tie rod 14,
A predetermined mold clamping force is applied to the mold 50. At a predetermined operation timing, while controlling the injection servo valve 27 with an operation control signal transmitted from the injection control unit 38,
When the screw 21 is advanced by the injection cylinder 24,
The molten resin stored in front of the screw 21 is injected and filled into the mold cavity 53 via the nozzle 26. The molten resin injected and filled in the mold cavity 53 is integrated with the skin material set in the mold cavity 53 and cooled in the mold 50 to form a bonded injection molded product.

Next, an operation control signal is transmitted from the mold clamping control unit 33 to the mold clamping servo valve 15 to
The movable mold 12 is moved backward to provide a gap corresponding to the mold opening set in the input condition setting unit 32 between the surface of the bonded injection molded product and the surface of the mold cavity 53, and then the input condition setting unit In accordance with the injection amount, the injection speed, the injection timing, and the injection pressure of the paint injecting machine 55 set to 32, the paint injecting machine 55 is controlled by the operation control signal transmitted from the injecting machine control unit 35 to paint the mold cavity 53. Inject into.

Subsequently, an operation control signal is transmitted from the mold clamping control unit 33 to the mold clamping servo valve 15 so that the mold clamping cylinder 1
The movable mold 12 is advanced again by 3 and feedback control is performed in accordance with the mold opening amount pattern and the mold clamping force pattern set in the input condition setting unit 32. By doing so, the injected paint is allowed to spread over the entire surface of the bonded injection molded article, and at the same time, optimum molding conditions are provided for the appearance and adhesion strength of the coating film.

Thereafter, an operation control signal is transmitted from the mold clamping control unit 33 to the mold clamping servo valve 15 to perform feedback control according to the operation timing and the mold opening speed pattern set in the input condition setting unit 32, and the mold is controlled. The movable mold 12 is retracted to the mold opening limit position by the tightening cylinder 13,
The integrally molded product is removed from the mold 50, and a series of molding cycles is completed.

Example 1 Polypropylene film layer /
Using a three-layer skin sheet consisting of an adhesive layer and an ABS resin film layer, the product side of the molded product is A before molding.
What was preformed into a substantially die shape so as to become a BS resin film was used as a skin material. Height 300m
m, width 210mm, depth 50mm, thickness 2.7mm using a mold with a shear edge structure that can obtain a box-shaped product,
The mold temperature is set at 85 ° C, the barrel temperature is set at 200 ° C,
The preformed skin material was placed in a mold cavity, and a mold clamping force of 200 tons was applied thereto. Then, lamination injection molding was performed using a polypropylene resin (J706MA manufactured by Grand Polymer: MFR = 15). After 30 seconds from the completion of the injection, the mold is opened by 0.5 mm, and after 5 seconds from the stop of the mold, 10 CC of a normal temperature paint (paint having adhesiveness to the ABS resin) having a composition shown in Table 1 is injected at an injection pressure of 1 MPa. After 2 seconds from the injection, the mold was closed, and a mold clamping force of 20 tons was continuously applied for 2 minutes. After the curing of the paint was completed, the mold was opened to take out a molded article with a coating film. At this time, it was confirmed that no paint was attached to the surface of the mold cavity.

The cross section of the obtained molded article is as shown in FIG. 2, and a polypropylene film layer S1a, an adhesive layer S1b and an ABS resin film layer S
The skin material S1 made of 1c is laminated, and the skin material S1 is further laminated.
Is coated with a coating layer P. Then, it was confirmed that the polypropylene film layer S1a was in good contact with the base material layer C, and the coating layer P was in good contact with the ABS resin film layer S1c. Further, the adhesive strength of the coating layer P was measured according to JIS K-5400 (General Test Method for Paints).
It was evaluated by a mm-thick cross-cut cellophane tape test, and it was confirmed that the adhesiveness was good.

[Example 2] Using the same mold, molding resin material and paint as in Example 1, the basis weight of polyethylene terephthalate fiber was applied to both front and back surfaces, 120 g /
a polyethylene terephthalate nonwoven m ² is used as the skin material, to obtain a molded article with a coating film subjected to molding under the same conditions as in Example 1. At this time, it was confirmed that no paint was attached to the surface of the mold cavity.

The cross section of the obtained molded product is as shown in FIG. 3, in which a skin material (non-woven fabric) S2 is laminated on the base material layer C, and a coating film is formed on the skin material (non-woven fabric) S2. The layer P is laminated. The basis weight fiber portions of the front and back surfaces of the skin material (nonwoven fabric) S2 are taken in and impregnated in the base material layer C and the coating film layer P, and the base material layer C and the skin material (nonwoven fabric) S2 In addition, it was confirmed that the skin material (nonwoven fabric) S2 and the coating layer P adhered well by the anchor effect of the basis weight fiber portion. Furthermore, the adhesive strength of the coating film adhered to the surface of the molded article was evaluated by a 1 mm cross-cut cellophane tape test,
It was confirmed that the adhesive state was good.

Comparative Example 1 Using the same mold as in Example 1, under the same temperature conditions and paint injection conditions, with a mold clamping force of 200 tons applied to the mold, a polypropylene resin (J706MA made by Grand Polymer: MFR = 15), the mold was opened 0.5 mm 30 seconds after the completion of the injection, and 10 CC of the same paint as in Example 1 was injected 5 seconds after the mold was stopped.
Two seconds after the injection, the mold was closed, a mold clamping force of 20 tons was continuously applied for 2 minutes, and after the coating material was completely cured, the mold was opened and the molded product was taken out. Most of the paint remained on the inner surface of the mold, and the coating film slightly adhered to the molded product was not adhered, and easily peeled off with a touch of a hand.

[0022]

[Table 1]

As described above, according to the in-mold coating molding method of the present invention, it is possible to adhere a coating film to an ABS resin, but to paint a coating film that cannot adhere to a polypropylene resin. When used, a polypropylene resin molded article in which a coating film is integrally formed in a good adhesion state can be obtained. Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and can be variously implemented without departing from the gist of the present invention. For example, in Example 1 described above, a preformed three-layered skin sheet composed of a polypropylene film layer / adhesive layer / ABS resin film layer was used as a skin material. Various multilayer structure skin sheets having different sheets and materials can be used as the skin material.
Similarly, in Example 2 described above, as a skin material having a detailed structure that can be adhered by an anchor effect, a basis weight of polyethylene terephthalate fiber on both front and back surfaces was 120 g.
/ M ² , a nonwoven fabric made of polyethylene terephthalate was used. In addition, a nonwoven fabric having a different basis weight, a nonwoven fabric having a different material, and various resin sheets having a large number of protrusions on the surface can be used. Further, in the above embodiment, a coating material having adhesiveness to the ABS resin was used, but a coating material for a nylon resin or a coating material for a thermosetting resin can also be used. Various resin materials can be applied.

[0024]

As described above, the present invention exerts the following excellent effects. (1) By using a skin material having excellent adhesion to a paint, a coating film can be formed in a good adhesion state in, for example, an olefin-based resin in-mold coating, which could not be adhered to a coating film conventionally. An integrally formed article can be obtained. Therefore, a synthetic resin molding material that is optimal for the type and purpose of the molded article can be used as the base resin. (2) A conventional paint for coating in a mold developed for a nylon resin, an ABS resin or a thermosetting resin can be used. (3) Synthetic resin material used as a base material from skin materials of different materials, skin materials of different detailed structures of surface layers, and skin materials of a multilayer structure in which materials and detailed structures of surface layers are variously combined. The most suitable skin material can be selected and used according to the type of the paint, the type of the paint, the type of the molded article, the purpose of use, and the like.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an in-mold coating forming apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a molded product obtained by molding shown in Example 1 of the present invention.

FIG. 3 is a sectional view of a molded product obtained by molding shown in Example 2 of the present invention.

[Explanation of symbols]

 Reference Signs List 10 mold clamping device 11 fixed plate 12 movable plate 13 mold clamping cylinder 14 tie rod 15 mold clamping servo valve 16 stroke sensor 17 mold opening sensor 18 mold clamping force sensor 20 injection device 21 screw 22 barrel 23 hydraulic motor 24 injection cylinder 25 hopper Reference Signs 26 Nozzle 27 Injection servo valve 30 Control device 31 Molding device control unit 32 Input condition setting unit 33 Mold clamping control unit 35 Injector control unit 38 Injection control unit 50 Mold 51 Fixed mold 52 Movable mold 53 Mold cavity 55 Paint injection machine 100 In-mold coating molding apparatus C Base layer P Coating layer S1 Skin material S1a Polypropylene film layer S1b Adhesive layer S1c ABS resin film layer S2 Skin material (nonwoven fabric)

Claims (5)

[Claims] An in-mold coating molding method for obtaining, in a mold, a molded product in which a coating film is integrally formed on a product surface, comprising: a skin material having excellent adhesion to a paint; and a synthetic resin serving as a base material. After performing lamination molding using a molding material, a coating material is injected between the surface of the skin material opposite to the base material and the surface of the mold cavity opposed thereto, and the surface of the skin material opposite to the base material is sealed. An in-mold coating molding method, characterized in that a coated product is integrally formed on a product surface by coating with a coating of a paint and curing the coating in a mold. 2. The method according to claim 1, wherein the synthetic resin molding material as the base material is a polypropylene resin or a polyethylene resin. 3. The base material side surface of the skin material has a detailed structure that can be welded to the base material by an anchor effect, and the surface of the skin material opposite to the base material has an anchor effect on a coating film. 3. The method according to claim 1 or 2, wherein the method has a detailed structure that can be adhered by the method. 4. The skin material has a multi-layer structure, the material of the surface layer on the substrate side of the multi-layer structure skin material is a synthetic resin having a high affinity for the base material, and the material of the multi-layer structure skin material is opposite to that of the multi-layer structure skin material. The method according to claim 1 or 2, wherein the material of the substrate-side surface layer is a synthetic resin having a high affinity for the coating film. 5. The method according to claim 4, wherein the surface of the multilayer structure skin material on the side of the base material has a detailed structure that can be adhered to the base material by an anchor effect.