JPH04201214A - Manufacture of molded form - Google Patents

Abstract

PURPOSE:To improve characteristics such as surface hardness, weather resistance, chemical resistance, conductivity, etc., by injection-molding a molding resin in a mold and irradiating a coated substance coated with a photo-setting sheet with light. CONSTITUTION:In a photo-setting sheet, a photo-setting resin layer, which mainly comprises an acrylic resin having weight average molecular weight of 50000-1000000 and Tg of 40-100 deg.C and being solid at normal temperature, a compound having a reactive vinyl group and an optical initiator and to which conductive fillers are added, is laminated on a sheet base material. The resin is injected into a mold under the state, in which such a photo-setting sheet is mounted onto the inner surface of the mold, and the surface of a coated substance acquired is irradiated with light, thus obtaining a molded form, on a surface of which the cured film of the sheet is formed. The rigid film also having excellent weather resistance can be formed by using the acrylic resin, and the surface of the molded form has conductivity because the conductive fillers are contained in the resin layer.

Description

Detailed Description of the Invention (Industrial Field of Application)
11 Ta! ! Regarding molded products with excellent properties (shielding, antistatic, etc.),
The present invention relates to a method for manufacturing molded products that can be used as housing songs for office automation products, automobile parts, building materials, etc. that require excellent weather resistance to withstand outdoor use.

(Prior technology) As a method of decorating the surface of plastic products at the same time as molding, there is a method of attaching a pattern to the surface of the mold in advance, a method of attaching a transfer film to the inside of the mold, and molding the pattern etc. of the film at the same time as molding. There have been proposed methods such as a method of transferring the function onto the outer surface of the product, a method of attaching a functionalized or printed sheet to the inner surface of the mold, and attaching the sheet to the surface of the molded product at the same time as molding.

Regarding the latter, for example, Japanese Patent Application Laid-open No. 60-250925 and Japanese Patent Publication No. 59-36841 disclose that after molding a weather resistance sheet or a printed sheet on the inner surface of a mold, the sheet is made by injection molding with a molding resin. A method of manufacturing a molded article with a coated surface has been proposed.

(Problems to be Solved by the Invention) In the conventional technology, decoration and functionality are imparted using thermoplastic sheets or printing transfer, so the surface hardness of the obtained molded product is insufficient. Ta. For example, when imparting weather resistance to a molded product, a highly weather resistant sheet made of polyvinylidene fluoride (PVDF) can be used, but since these sheets are thermoplastic, there is a problem in that sufficient surface hardness cannot be obtained. be.

On the other hand, when trying to obtain a molded article with high hardness, it is necessary to use a sheet that has been crosslinked in advance and has high hardness, and therefore cannot be applied to a three-dimensional molded article.

In addition, these synthetic resin molded products generally have a problem in that dust and the like tend to adhere to them because they are easily charged.

(Purpose of the Invention) The present invention was made to solve the above problems, and its purpose is to not only enable the use of general-purpose molding resins, but also to provide high surface hardness and weather resistance. The object of the present invention is to provide a method for producing molded products that exhibit properties that exceed those of conventional coatings, such as chemical resistance, electrical conductivity, etc.

(Means for Solving the Problems) The method for producing a molded article of the present invention has a weight average molecular weight of so,
ooo~1,000,000, glass transition point 40~1
A photocurable resin layer formed of a resin composition containing an acrylic resin, a compound having a reactive vinyl group, a photopolymerization initiator, and a conductive filler at 00°C, and a sheet base material are laminated. A photocurable sheet is attached to the inner surface of a mold so that the photocurable resin layer is located on the mold side, and a molding resin is injection molded into the mold to form a coating coated with the photocurable sheet. The above object is achieved by forming a coated body and then irradiating the coated body with light to cure the photocurable sheet.

The photocurable sheet used in the present invention has a weight average molecular weight of 50,000 to 1,000,000 and a Tg of 40 to 10.
A photocurable resin composition made of a photocurable resin composition whose main components are an acrylic resin that is solid at room temperature (0°C), a compound having a reactive vinyl group, and a photoinitiator, and to which a conductive filler is added. It is formed by laminating a synthetic resin layer on a sheet base material. The sheet base material is preferably one that has good adhesion to the injection molding resin, as described below.For example,
Examples include polyolefins such as ABS (acrylonitrile-butadiene-styrene copolymer), vinyl chloride resins, polystyrene, and polypropylene, and fiber resins.

Preferably, most of the polymerized units of the acrylic resin are methyl methacrylate (MMA), ethyl methacrylate (HMA), and butyl methacrylate (MMA), which have good weather resistance.
A polymer made of methacrylate such as BMA) with a Tg of 40 to 1°C is used, and in order to improve the adhesion between the resin layer and the sheet substrate, a monomer having a functional group, such as 2 -Ethyl hequinyl methacrylate (
2-HEMA), 4-hydroquine butyl methacrylate (4-HBMA), and the like can also be included as constituents.

Regarding the above-mentioned compound having a reactive vinyl group, in consideration of weather resistance, it is desirable that the compound is aliphatic and has a small number of double bonds per molecular weight. Furthermore, in consideration of curability, it is desirable to have a large number of double bonds per molecular weight. For example, allylated/chlorohequinyl diacrylate, dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, methquinated cyclohequinyl diacrylate, neopentyl glycol-modified trimethylolpropane diacrylate, ditrimethylolpropane tetraacrylate, It is more desirable to use modified trimethylolpropane triacrylate, aliphatic urethane acrylate, etc., with a molecule FF of 1200-600, a double bond number of 2-6, and a cyclohexyl ring in the structure. Further, in order to improve adhesion and flexibility, a long-chain monomer containing a hydroxyl group having only one double bond, such as caprolactone-modified 2-HEA, may be added.

Regarding the photopolymerization initiator, in consideration of yellowing during curing and deterioration during weather resistance, initiators that do not contain amino groups in the molecule, such as acetophenone and benzophenone, are preferable. For example, when forming a transparent film, 1-(
4-dodenulfenyl)-2-hydroquine-2methylpropan-1-one, ■-Hydroxy/hydroquinyl phenylketone, 2-hydroquine-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl)-2-hydroquine-2-methyl-propan-1-one is preferred. Depending on the molding method, the temperature may temporarily exceed the boiling point of the initiator, so care must be taken. In order to improve the surface hardening properties of the molded article, an oxygen polymerization inhibiting hardening inhibitor such as n-methyljetanolamine may be added.

The amount of the compound (monomer) having a reactive vinyl group added is preferably 30 to 100 parts by weight per 100 parts by weight of the acrylic resin. The amount of photopolymerization initiator added is preferably 3% by weight or less in terms of monomer molar ratio, as the amount remaining after curing affects weather resistance.In particular, amine-based photopolymerization initiators, which are associated with yellowing during curing, should be 0%. ．． The content is preferably 5% by weight or less.

Examples of the conductive filler include metal powders such as silver powder and copper powder, carbon black, graphite, and silver plating fine particles. For metal powder, the particle size is 20μ or less and the amount added is about 10-30% by weight, and for carbon powder, the particle size is 50nm or less and the amount added is about 20-4.0% by weight, and it is 10'-10''Ω・C.
A conductivity of m is obtained. Regarding the amount of these conductive fillers added, preliminary experiments are required because the conductivity may vary considerably depending on the particle size, surface area, chemical treatment of the surface, etc. of the particles. For example, when porous carbon black is used, conductivity of about 10 2 -10 3 Ω·cm can be obtained by adding about 10% by weight due to its increased surface area.

The method for producing the photocurable 7-sheet is to sufficiently dissolve the photocurable resin composition in an organic solvent or the like and coat it on a sheet base material by a casting method such as a stirring spool, a knife coater, a comma coater, or a reverse coater. There is a method of creating it by drying it to remove the solvent. Also, P.E.
When coating the resin liquid on a sheet base material made of polyolefin such as PP, etc., in order to increase the adhesion between the sheet base material and the photocurable resin layer, Activate the surface of the base material in advance by corona discharge, etc. (The process of performing this corona discharge is as follows:
It is preferable to apply it immediately after activation or slightly before coating because it has high adhesion. ) is preferred. The thickness of the sheet base material used here varies depending on injection conditions and solvent resistance, but in the case of an ABS sheet, it is preferably about 200 to 500 μm.

Next, a method for manufacturing a molded article using the photocurable sheet manufactured in this way will be explained. The method can be carried out using an apparatus such as that shown in FIG. This device consists of a movable mold 4 having a molding recess 41 and a suction port 42.
, a sheet cutting device 3 , a hot platen 2 having an air outlet 21 and a heater 22 , a fixed mold 5 , and an injection molding machine 7 . A roll 8 is arranged around the movable mold 4 for placing the photocurable sheet 1 in the recess 41 of the movable mold 4 and moving it sequentially. Above hot plate 2
is configured to be movable between a position near the recess 41 of the movable mold 4 and a position away from the movable mold 4.

In order to manufacture a molded product using this device, please refer to Figure 1 (a).
), (b), first, the photocurable sheet 1 is placed in the recess 41 of the movable mold 4. Here, sheet 1
is arranged so that the photocurable resin layer 1a is located on the whole mold 4 side and the sorting base material 1b is located on the molding resin side. hot plate 2
is moved to the movable mold 4 side to soften the sheet 1, and the sheet 1 is cut into a predetermined size by the cutting device 3. Next, the sheet 1 is attached to the inner surface of the movable mold 4 by blowing air out to the sheet 1 side through the air outlet 21 of the heating platen 2 and at the same time suctioning the sheet 1 through the suction port 42 of the movable mold 4.

Next, the hot platen 2 is moved to the side of the movable mold 4, and the movable mold 4 is moved to the fixed mold 5 side to clamp the mold, and in this state, the molding resin is transferred from the injection molding machine 7 to the fixed mold. A cavity formed between the mold 5 and the movable mold 4 is injected and filled to form a coating having the sheet 1 formed on the surface.

The temperature of the heating platen 2 depends on the sheet base material, the type of resin, and the mold, but is preferably about 100-200'C. In addition, the injection conditions may be normal molding conditions.

Next, after opening the movable mold 4, the covering body 9 is taken out,
As shown in FIG. 2, the coating 9 is placed on a conveyor 10, and the surface of the coating 9 is irradiated with ultraviolet rays from an ultraviolet irradiation lamp 12 through a cold filter 11. Note that in Figure 3, 13 is a reflective plate such as an aluminum plate. The irradiation amount is usually preferably about 500-1,000+J. The sheet 1 on the surface of the coating 9 is cured by ultraviolet irradiation to form a hard film.

The surface hardness of the thus obtained molded product is H8 or higher in terms of pencil hardness, although it depends on the composition of the sheet used, and the molded product has good weather resistance and chemical resistance.

(Function) The photocurable resin layer of the photocurable sheet used in the present invention is
It is made of a resin composition containing an acrylic resin, a compound having a reactive vinyl group, a photopolymerization initiator, and a conductive filler. Therefore, when this resin layer is irradiated with light, the photopolymerization initiator generates radicals, which react with the vinyl groups of the compound (monomer) having a reactive vinyl group, resulting in chain polymerization. The monomer is crosslinked and cured.

Then, with such a photocurable sheet attached to the inner surface of the mold, resin is injected into the mold, and the surface of the obtained coating is irradiated with light (300 to 500 parts m). It is possible to obtain a molded product on which a cured sheet film is formed.

Therefore, a general-purpose resin can be used as the injection molding resin, and the resin blended into the photocurable resin composition has a weight average molecular I of so, ooo to 1°ooo, ooo, and a glass transition point of 40 to 100. By using an acrylic resin having a temperature of 10°C, it is possible to form a hard film with excellent weather resistance.

Furthermore, since the resin layer contains a conductive filler, the surface of the molded article becomes conductive.

(Examples) The present invention will be specifically described below based on Examples. In addition, "part" means "part by weight."

L Gosou upper acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Barapey) GI
P8, Tg=80°C) 100 parts and acrylic monomer (Nippon Kayaku Co., Ltd., Karayanod DPCA-20, M=80
7. Number of double bonds 6) 30 parts and photopolymerization initiator (manufactured by Nippon Ciba Geigy Co., Ltd., Irugaki, 7-184, M=204)
0.2 part (this additive is 0.5% based on the above monomer)
molar ratio), 0.1 part of n-methyljetanolamine (manufactured by Wako Pure Chemical Industries, Ltd., M = 121) (the additive has a molar ratio of 0.5% to the above monomer), and acetylene black. (average particle size 40 nm) 40 parts ethyl acetate 30 parts
0 parts and mixed.

This mixture was applied to an ABS sheet (manufactured by Sanpo Jushi Co., Ltd., film thickness 5).
00 μm) using an applicator, and dried at 80°C for 30 minutes to form a transparent layer of 50 μm + 7-t base material of 500 μm.
A photocurable sheet of ALm was created. The thus obtained sheet was heated in an injection molding device at 150° C. for 30 seconds using a hot platen, vacuum-formed into a plate-shaped mold of 100×100×10II11, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board is exposed to ultraviolet light for 1. OOOm
The sheet was cured by J irradiation.

Tsuya [ Acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Parapet GI
P-8, Tg=80°C) 100 parts and acrylic monomer (Nippon Kayaku Co., Ltd., Karaya, DoDP CA-20, M
= 807, number of double bonds 6) and 30 parts of photopolymerization initiator (manufactured by Ehon Ciba Geigy Co., Ltd., Irgacure 184, M = 2
04) 0.2 parts (this additive is 0.2 parts based on the above monomers)
．． 5% molar ratio) and 0.1 part of n-methyljetanolamine (manufactured by Wako Pure Chemical Industries, Ltd., M = 121) (this additive has a 0.5% molar ratio with respect to the above monomer). 10 parts of porous carbon black (average particle size: 30 nm) was dissolved in 300 parts of ethyl acetate and mixed.

This mixture was applied to an ABS sheet (manufactured by Sanpo Jushi Co., Ltd., film thickness 5).
00 μm) using an applicator, and dried at 80°C for 30 minutes to form a transparent layer of 50 μm + base sheet of 500 μm.
A 7-μm photocurable sheet was prepared.

The thus obtained sheet was molded into an injection molding machine using a hot platen for 15 minutes.
After heating at 0° C. for 30 seconds, vacuum molding was performed into a plate-shaped mold of 100×1OO×10 mm, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board was irradiated with I, OOOmJ of ultraviolet rays using a UV irradiation device to cure the sheet.

Acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Parapet GI
P-8, Tg=80°C) 100 parts and acrylic monomer (
Manufactured by Nippon Kayaku Co., Ltd., Karaya, DoDPCA-20, M=8
07, double bond number 6) and 30 parts of photopolymerization initiator (manufactured by Nippon Ciba Geigy Co., Ltd., Irgacure 184, M=204
)0.2 part (this additive is 0.5 part based on the above monomer)
% molar ratio), 0.1 part of n-methyljetanolamine (manufactured by Wako Pure Chemical Industries, Ltd., M = 121) (this additive has a 0.5% molar ratio to the above monomer), and silver powder (
(average particle size: 20 μm) was dissolved in 300 parts of ethyl acetate and mixed. Add this mixture to ABS notebook (Sanpo Jushi Co., Ltd.)
After coating with an applicator to a film thickness of 500 μm, it was dried at 80° C. for 30 minutes to prepare a photocurable sheet with a transparent layer of 50 μm and a base material of 500 μm. The sheet thus obtained was molded using an injection molding machine at 150°C and 30°C using a heating plate.
After heating for seconds, the product was vacuum-formed into a 10100×100×1O+ plate-shaped mold, and ABS resin was injected to obtain an ABS plate.

The surface of this ABS board is exposed to 1,000 UV rays using a UV irradiation device.
The sheet was cured by irradiating with 0 mJ.

Lining 5 acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Barapet GI
P-8, Tg=80'C) 100 parts and acrylic monomer (Nippon Kayaku Co., Ltd., Karayad DPCA-20, M=
807, number of double bonds 6) and 30 parts of photopolymerization initiator (manufactured by Nippon Ciba Geigy Co., Ltd., Irgacure 184, M = 20
4) 0.2 parts (this additive is added in an amount of 0.2 parts based on the above monomers)
5% molar ratio) and n-methyljetanolamine (
0.1 part of Wako Pure Chemical Industries, Ltd. (M=121) (this additive has a molar ratio of 0.5% to the above monomer) was dissolved in 300 parts of ethyl acetate and mixed. Add this mixture to ABS
After coating Sort (manufactured by Sanpo Jushi Co., Ltd., film thickness 500 μm) using an applicator, it was dried at 80°C for 30 minutes to create a photocurable layer with a transparent layer of 50 μm and a base material of 500 μm. . The sort obtained in this way was heated in an injection molding machine at 150°C for 30 seconds using a heating plate, and then 10100xlOOX
The mold was vacuum-formed into 10 plate-shaped molds, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board is exposed to ultraviolet light for 1. The sheet was cured by OOOmj irradiation.

Next, Table 1 shows evaluations of hardness, weather resistance, chemical resistance, and surface resistance of the ABS plates obtained in Examples 1 to 3 and Comparative Examples.

In Table 1, weather resistance was expressed as color difference ΔE after 300 hours using an accelerated exposure tester (Isosuper UV tester). Acid resistance is 0. 24-hour spot test (2 (1'c)) of IN sulfuric acid. Alkali resistance is 0.
24-hour spot test of IN sodium hydroxide (20°C
). The hot water resistance is a 10 day immersion test at 40°C.

(Effects of the Invention) According to the present invention, a general-purpose resin can be used as a molding resin, and a molded article having excellent surface hardness and weather resistance can be manufactured. In addition, since the surface of the molded product is conductive, there is no adhesion of dust, and it can shield electromagnetic waves, making it suitable for use in automobile parts, building materials, and the like. In addition, compared to painting the surface of a molded product, the number of steps can be omitted and productivity is improved. Simple Theory B Figure 1(a) is a schematic diagram showing an example of the apparatus used in the method for manufacturing a molded article of the present invention, Figure 1(b) is an enlarged cross-sectional view of the main part thereof, and Figure 2 is a diagram showing the covering body. FIG. 3 is a schematic diagram showing the process of irradiating ultraviolet rays to the substrate, and FIG. 3 is an explanatory diagram thereof.

Claims (1)

[Claims] 1. Weight average molecular weight is 50,000 to 1,000,00
0. A photocurable resin layer formed of a resin composition containing an acrylic resin having a glass transition point of 40 to 100°C, a compound having a reactive vinyl group, a photopolymerization initiator, and a conductive filler; A photocurable sheet formed by laminating a sheet base material is attached to the inner surface of a mold so that the photocurable resin layer is located on the mold side, and a molding resin is injection molded into the mold and the photocurable sheet is laminated with a sheet base material. A method for manufacturing a molded article, which comprises forming a coated body covered with a curable sheet, and then irradiating the coated body with light to cure the photocurable sheet.