JPH04201213A - Manufacture of molded form - Google Patents

Abstract

PURPOSE:To improve characteristics such as surface hardness, weather resistance, chemical resistance, 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 formed of a photo-setting resin composition, 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 a photopolymerization initiator and to which a gloss control agent is added, is laminated on a sheet base material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to materials for motor wheels, which require excellent appearance, surface hardness (scratch resistance), and excellent weather resistance to withstand outdoor use. This invention relates to a method for manufacturing molded products that can be used as building materials, etc.

(Prior art) 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 inner surface of the mold, and a method of decorating the surface of the plastic product at the same time as molding. A method has been proposed in which a functionalized or printed sheet is affixed to the inner surface of a mold and the sheet is affixed to the surface of a 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, injection molding of a molding resin is carried out. A method of manufacturing a molded article whose surface is coated with

(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.

(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 manufacturing molded products that have properties that exceed conventional coating performance, such as paint and chemical resistance. Still another object of the present invention is to provide a method for manufacturing a molded article that can reduce surface gloss while maintaining the properties of the molded article.

(Means for Solving the Problems) The method for producing a molded article of the present invention has a weight average molecular weight of 50,
000-1,000,000, glass transition point 40-1
A photocurable resin layer formed of a resin composition containing an acrylic resin having a temperature of 00°C, a compound having a reactive vinyl group, a photopolymerization initiator, and a gloss control agent, and a sheet base material are laminated. A curable 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 covering body covered with the photocurable sheet. The photocurable sheet is then cured by irradiating the coating with light, thereby achieving the above object.

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 40-10.
0''C and is solid at room temperature, the light is formed from a photocurable resin composition that is mainly composed of an acrylic resin, a compound having a reactive vinyl group, a photopolymerization initiator, and a gloss control agent added. It is formed by laminating a curable 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, ABS (acrylonitrile- butadiene-styrene copolymer), vinyl chloride resins, polyolefins such as polystyrene and polypropylene, and fluorine resins.

The acrylic resin is preferably methyl methacrylate (MMA) in which most of the polymerized units have good M weatherability.
, ethyl methacrylate (HMA), butyl methacrylate (BMA), and other methacrylate polymers with a Tg of 40 to 100°C are used, and in order to increase the adhesion between the resin layer and the sheet base material, It is also possible to include monomers with functional groups, such as 2-ethyl hebutyl methacrylate (2-HEMA), 4- and droxybutyl methacrylate (4-HBMA), and the like.

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 cyclohexyl diacrylate, dipentaesothritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol-modified trimethylolpropane diacrylate, ditrimethylolpropane tetraacrylate , trimethylolpropane triacrylate modified products, aliphatic urethane acrylates, etc., which have a molecular weight of 200-600, a number of double bonds of 2-6, and contain a Schiff sil ring or the like in their structure are more desirable.

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 above-mentioned photopolymerization initiator, in consideration of yellowing during curing and deterioration during weathering, initiators that do not contain an amine 7 group in the molecule, such as 7cetophenone type and benzophenone type, are preferable. For example, when forming a transparent film, 1-(
4-dodecylphenyl)-2-hydroxy-2, methylpropan-1-one, l-hydroxylchlorohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4- isopropylphenyl)-2-hydroxy-2-methyl-propane-1-
On 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 of the molded product, n-
A curing inhibitor that inhibits oxygen polymerization such as methyljetanolamine may be added.

The amount of the compound having a reactive vinyl group (Nanatsumer) 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.

The above gloss control agent mainly contains 5i02 with a particle size of 4 μm.
The following materials with low cohesiveness are preferably used, including fine particles of silica, silica gel, zeolite, alumina silicate, quartz, diatomaceous earth, natural silicates, and the like. The amount of the gloss control agent added may be about 5-30% by weight, depending on the grade.

The method for producing a photocurable sheet is to sufficiently dissolve the photocurable resin composition in an organic solvent, etc., coat it on a sheet base material by a casting method such as a stirrer, a knife coater, a comma coater, or a reverse coater, and then remove the solvent. There is a method of drying and creating. Also, P.E.
S When coating the above resin liquid onto a sheet base material made of polyolefin such as PP, in order to increase the adhesion between the sheet base material and the photocurable resin layer, Activate the surface of the sheet base material in advance by corona discharge etc. ) is preferable. 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, the sheet 1 is arranged so that its photocurable resin layer 1a is located on the movable mold 4 side and the sheet base material 1b is located on the molding resin side. Next, the hot platen 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 out air from the air blowing port 21 of the heating plate 2 toward the sheet 1 and simultaneously sucking the 7-toe 1 from 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 covering body with the sheet 1 formed on the surface.

The temperature of the hot platen 2 depends on the sheet base material, the type of resin, and the mold, but is preferably about 100-200°C. Further, 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. In addition, 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 sort used in the present invention is
It is formed from a resin composition containing an acrylic resin, a compound having a reactive vinyl group, a photopolymerization initiator, and a gloss control agent. 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 molding resin, and the weight average molecular weight of the resin blended into the photocurable resin composition is 50. 000-1. Ooo, ooo,
By using an acrylic resin with a glass transition point of 40 to ioo"c, it is possible to form a hard film with excellent weather resistance. Furthermore, since the resin layer contains a gloss control agent, , it is possible to arbitrarily control the gloss of the surface of the molded product without reducing the properties of the molded resin.

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

1 dish per animal, 100 parts of acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Barahet GIF-8, Tg = 80"C) and acrylic monomer (manufactured by 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., Irugaki x7-184, M=
204) 0.2 parts (this additive is
0. 5% molar ratio) and 0.1 part of n-methyljetanolamine (manufactured by Wako Pure Chemical Industries, Ltd., M = 121) (the additive has a 0.5% molar ratio to the above monomer).
and gloss control agent (manufactured by Nippon Silikani Gyo Co., Ltd., N1psil)
E200, particle size 2.5μ) 3 parts ethyl acetate 300
and mixed. This mixture was applied to ABS tape (manufactured by Sanpo Jushi Co., Ltd., film thickness: 500 μm) using an applicator, dried at 80°C for 30 minutes, and a transparent layer of 50 μm was coated.
A photocurable sheet with a base material of 500 μm was prepared.

The thus obtained sheet was molded into an injection molding machine using a hot platen for 15 minutes.
After heating at 0℃ for 30 seconds, vacuum forming into a plate-shaped mold of 1100xlOOx10+a, and injecting ABS resin.
Got the board. The surface of this ABS board is exposed to ultraviolet light for 1. The sheet was cured by OOOmJ irradiation.

L plate craftsmanship and acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Barape, ToGI
P-8, Tg=80°C) 100 parts and acrylic monomer (
Manufactured by Nippon Kayaku Co., Ltd., Karayad DPCA-20, M=8
07, double bond number 6) and 30 parts of photopolymerization initiator (manufactured by Nippon Ciba Geigy Co., Ltd., Irugaki x7 184, M = 204
)0.2 part (this additive is 0.5 part based on the above monomer)
% 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-mentioned 7-mer). ) and gloss control agent (manufactured by Nihon Rika Kogyo Co., Ltd., N1ps i l
E 200s particle size 2.5μ) 8 parts ethyl acetate 30
0 parts and mixed. This mixture was applied to an ABS sheet (manufactured by Sanpo Jushi Co., Ltd., film thickness 500 μm) using an applicator, and then dried at 80"C for 30 minutes to form a transparent layer 5.
A photocurable sheet with a thickness of 0 μm and a base material of 500 μm 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, it was vacuum-formed into a plate-shaped mold of 100×1OO×10+m, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board is exposed to ultraviolet light for 1. The sort was cured by OOOmJ irradiation.

Cold 11-1 Acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Parabenodo GI
P-8, Tg=80°C) 100 parts and acrylic monomer (
Manufactured by Nippon Kayaku Co., Ltd., Karayad DPCA-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) and 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 gloss Control agent (manufactured by Nippon Silkani Industry Co., Ltd., N1psil E20
0, particle size 2.5μ) was dissolved in 300 parts of ethyl acetate and mixed. This mixture was applied to an ABS sheet (manufactured by Nijo Resin Co., Ltd., film thickness 500 μm) using an applicator, and then dried at 80°C for 30 minutes to form a photocurable sheet with a transparent layer of 50 μm and a base material of 500 μm. Created.

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 100×100×10 mm, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board was irradiated with ultraviolet rays using a UV irradiation device, and the sheet was cured by irradiating OOOmJ.

Soft acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd., Barabet 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
) 12 parts of O (this additive is 0.5 parts based on the above monomer)
% 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 to the above monomer) in acetic acid. It was dissolved in 300 parts of ethyl and mixed. This mixture was applied to an ABS sheet (manufactured by Nijo Resin Co., Ltd., film thickness 500 μm) using an applicator, and then dried at 80°C for 30 minutes to form a photocurable sheet with a transparent layer of 50 μm and a base material of 500 μm. Created.

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, it was vacuum-formed into a plate-shaped mold of 10,100×1OO×10, 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. This is a 24-hour spot test (20°C) of IN sulfuric acid. Alkali resistance is 0. IN
This is a 24-hour spot test (20°C) for sodium hydroxide. Hot water resistance is a 10 day immersion test at 40°C. Gloss is determined based on specular gloss J in accordance with JIS K7105 R Plastic Optical Characteristics Test Method.
Measurement was performed using a digital variable angle gloss meter using 60 parts specular reflection.

(Hereinafter referred to as a margin) (Effects of the Invention) According to the present invention, a general-purpose resin can be used as a molding resin, and a molded product having excellent surface hardness and weather resistance can be manufactured. Furthermore, the surface gloss can be controlled arbitrarily without reducing the physical properties of the molded article. Therefore, it can be suitably used for automobile parts, building materials, etc. Furthermore, compared to the case where the surface of a molded article is painted, the number of steps can be omitted and productivity is improved.

4. Simple explanation a Figure 1 is a schematic diagram showing an example of the apparatus used in the method for manufacturing a molded product according to the present invention (a), and Figure 1 (b) is an enlarged sectional view of the main part. FIG. 2 is a schematic diagram showing the process of irradiating the coated body with ultraviolet rays, and FIG. 3 is an explanatory diagram thereof.

DESCRIPTION OF SYMBOLS 1... Photocurable sort, 2... Heat plate, 3... Sheet cutting device, 4... Movable mold, 5... Fixed mold, 9
... Covering body, 12 ... Ultraviolet irradiation lamp.

that's all

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 gloss control agent, and a sheet. A photocurable sheet laminated with a 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 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.