JPH04201212A - Manufacture of molded form - Google Patents

Abstract

PURPOSE:To realize a molded form having high surface hardness and characteristics higher than coatability 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 mainly comprising an acrylic resin having weight average molecular weight of 50000-1000000 and Tg of 0-100 deg.C and formed in a solid shape at normal temperature, a crosslinking agent capable of reacting with the resin, a compound having a reactive vinyl group and a photopolymerization initiator is laminated on a sheet base material. The photo-setting sheet 1 is laid in the recess 41 of a movable mold 4 in such a way that a photo-setting resin layer 1a is positioned on the movable mold 4 side, and a hot plate 2 is moved and the sheet 1 is softened and cut. Air is jetted against the sheet 1 side and air is sucked from a suction port 42 to hold the sheet 1 onto the inner surface of the movable mold 4, the hot plate 2 is shifted and the movable mold 4 and a stationary mold 5 are mold-clamped, and a molding resin is injected into a cavity from an injection molding machine 7, thus acquiring a coated substance, on a surface of which the sheet 1 is formed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to automotive parts, building materials, etc. that require excellent appearance and surface hardness (scratch resistance) and excellent weather resistance to withstand outdoor use. The present invention relates to a method for manufacturing molded products that can be used as

(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, 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.

(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.

(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 0-10
An acrylic resin having a reactive functional group that is solid at room temperature at 0°C, a crosslinking agent capable of reacting with the reactive functional group of the acrylic resin, a resin containing a compound having a reactive vinyl group, and a photopolymerization initiator. A photocurable sheet formed by laminating a photocurable resin layer formed from a composition and a notebook base material is attached to the inner surface of a mold so that the photocurable resin layer is located on the mold side. In this method, a molding resin is injected into a mold to form a coating covered with a photocurable sheet, and then the coating is irradiated with light to cure the photocurable sheet. This achieves the above objective.

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 0 to 100.
℃ and is solid at room temperature, a photocurable resin composition whose main components are a crosslinking agent that can react with the acrylic resin, a compound having a reactive vinyl group, and a photopolymerization initiator. It is formed by laminating a curable resin layer on top of the base layer. As the sheet base material, materials with good adhesion to the molding resin are preferably used as described below, such as ABS (acrylonitrile-butadiene-styrene copolymer), vinyl chloride resin, polyolefins such as polystyrene, polypropylene, etc. Examples include F-1 resin sheets.

The above-mentioned acrylic resin has reactive functional groups such as hydroxyl group, carboxyl group, and amine group, and those having two or more of these reactive functional groups are particularly preferable. Such acrylic resins are preferably manufactured from monomers such as (meth)acrylic acid esters and styrene derivative monomers. When the acrylic resin has a hydroxyl group as a reactive functional group, the monomers constituting the acrylic resin include, for example, 2-hydroboxydiethyl (meth)
Acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc., and when the acrylic resin has an amine group,
Monomers include 2-aminoethyl (meth)acrylate, 3-aminopropyl (meth)acrylate, 4-aminobutyl (meth)acrylate, etc., and when the acrylic resin has a carboxyl group, the monomer (meth)acrylate There are acids etc. In addition, when weather resistance is taken into account, it is desirable that the polymer units are mainly composed of methacrylates such as methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), and the like.

The above-mentioned cross-linking agent may be one that can react with the reactive functional group of the acrylic resin (e.g., isocyanate-based cross-linking agent,
Examples include melamine crosslinking agents and epoxy crosslinking agents.

In particular, when considering weather resistance (yellowing, etc.), incyanate crosslinking agents other than epoxy type and melamine crosslinking agents that use amines as catalysts are desirable. Isocyanate-based crosslinking agents include aliphatic ones, such as bis(incyanurate-modified) cyclohexane, dicyclohexylmethane diisocyanate, trimethylolpropane adducts thereof, incyanurate-modified products, and urethane-modified products. Among the melamine-based crosslinking agents, trimethylolmelamine,
There is an etherified melamine resin made by reacting melamine, etc. with an alcohol such as propyl alcohol or methyl alcohol.

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, dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol-modified trimethylolpropane diacrylate, ditrimethylolpropane tetraacrylate, Examples include modified trimethylolpropane triacrylates and aliphatic urethane acrylates, and those having a molecular weight of 200 to 600, a number of double bonds of 2 to 6, and a structure containing a cyclohexyl ring or the like are particularly preferred. 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 containing no amino group in the molecule, such as acetophenone and benzophenone, are preferred. For example, when forming a transparent film, 1-
(4-Dodecylphenyl)-2-hydroquine-2methylpropan-1-one, 1-hydro-semi-dicyclohexyl phenylketone, 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.

In addition, when forming a colored film, it is hidden by the film thickness and pigment concentration, and the curing of the resin layer by light irradiation is insufficient.
50 nm), such as acyl phosphone oxide, benzoin isobutyl ether,
Thioxanthone, benzyl, camphor beef non-alcohol and the like are preferred.

In addition, in order to improve the surface hardening properties of the sheet, an oxygen polymerization inhibitor such as n-methyljetanolamine may be added.

The amount of the compound (monomer) having a reactive vinyl group added is 30-100 parts by weight per 100 parts by weight of the acrylic resin.
Parts by weight are preferred. The amount of curing agent (combined photopolymerization initiator and crosslinking agent) added is preferably 3% by weight or less in terms of monomer molar ratio, since the amount remaining after curing affects weather resistance.
In particular, amine-based photopolymerization initiators that are associated with yellowing during curing are 0. The content is preferably 5% by weight or less. In particular, regarding the amount of crosslinking agent added, when using an isocyanate crosslinking agent, the functional group values (OH value, N82 value, C
Total of 0OH value; N82 value is N added during polymerization (2)
The amount of groups is calculated in the same way as the OH value, or it is determined by reacting NH2 groups with nitrous acid and converting them to OH groups.COO
The H value is calculated in the same way as the OH value by calculating the amount of C0OH groups added during polymerization, or is the value obtained by titrating C0OH with KOH. ), NGO has functional group value: NC0=L: 0
．． An amount of 8-1.2 is preferable. Furthermore, when using a melamine-based crosslinking agent or an epoxy/based crosslinking agent, it is difficult to obtain a fixed value for the functionalization of the acrylic resin, so it is best to determine it through preliminary experiments.

The photocurable resin composition can contain colorants such as various pigments or dyes. Generally known colorants are used, and the amount added may be determined by taking into consideration the relationship between the hidden film thickness of the coating film and the coating film thickness of the molded product. However, when the resin layer is colored, it is necessary to select the type of photopolymerization initiator because it depends on the absorption wavelength or color of the photopolymerization initiator. For example, when creating a yellow resin layer, the photopolymerization initiator contained in the resin composition is 470
Camphor beef non-alcohol that has absorption in the nm range is good.

As a method for producing a photocurable sheet, the photocurable resin composition described above is sufficiently dissolved and stirred in an organic solvent, etc., and coated on a sheet base material by a casting method such as a knife tool, a funter, or a reverse coater, and then the solvent is removed. There is a method of drying and creating it. 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 sheet base material surface in advance by corona discharge etc. (The process of performing this corona discharge is as follows:
Immediately after activation, adhesion is highest, so it is preferable to apply a little before coating. ) is preferred. The thickness of the sheet base material used here varies depending on injection conditions and solvent resistance, but in the case of ABS sheets, it is preferably about 200-500 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 heating plate 2 having an air outlet 21 and a heater 2'2, 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. The heating platen 2 is configured to be movable between a position near the recess 4L 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. By heating the heating plate 2, the crosslinking agent contained in the sheet 1 and part or all of the acrylic resin react with each other. Next, air is blown out from the air outlet 21 of the heating plate 2 toward the sheet 1 side, and at the same time, the air is blown out from the air outlet 21 of the movable mold 4.
By suctioning the sheet 1 from 2, the sheet 1 is attached to the inner surface of the movable mold 4. Next, the hot platen 2 is attached to the movable mold 4
At the same time, the movable mold 4 is moved to the fixed mold 5 side and clamped, and in this state, molding resin is injected from the injection molding machine 7 between the fixed mold 5 and the movable mold 4. The material is injected and filled into a cavity formed in the mold to form a covering body with the sheet 1 formed on the surface.

Note that the temperature of the hot platen 2 is preferably about 100-200°C, although it depends on the sheet base material, the type of resin, and the mold. Also,
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 FIG. 3, 13 is a reflective plate such as an aluminum plate. The irradiation dose is usually 500-1. 000mJ, especially when the resin layer is colored, 5.000-10,000mJ
is preferred. The 7-t 1 on the surface of the coating 9 is cured by ultraviolet irradiation to form a hard film. The surface hardness of the molded product thus obtained is H8 or higher on a pencil hardness scale, depending on the composition of the sheet used, etc., and has good weather resistance and chemical resistance.

(Function) The photocurable resin layer of the photocurable sheet used in the present invention is
It is formed from a resin composition containing an acrylic resin, a crosslinking agent capable of reacting with the acrylic resin, a compound having a reactive vinyl group, and a photopolymerization initiator. 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 resulting coating is irradiated with light (300-500 nm) to form a sheet on the surface. A molded article with a cured film formed thereon can be obtained.

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 weight of 50,000 to 1°ooo, ooo and a glass transition point of 0 to 100°C. By using acrylic resin, it is possible to form a coating that is hard and has excellent weather resistance.

Furthermore, since the resin composition of the present invention contains an acrylic resin having a reactive functional group and a crosslinking agent that can react with the acrylic resin, they react and crosslink and harden, especially when heated. become. Therefore, since the cured resin layer has good releasability from the inner surface of the mold, the covering can be easily taken out from the mold, and a molded article with a harder coating can be obtained.

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

Dog 1” mouth.

100 parts of acrylic polyol (manufactured by E1 Hon Shokubai Kagaku Co., Ltd., Alotane 183.7H=40°C, 0H=80) and titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., Tybake CR-90) 4
00 parts and acrylic monomer (manufactured by Nippon Kayaku Co., Ltd., Karaya Sod DPCA-20, M = 807, number of double bonds 6) 3
0 parts, 2.5 parts of photopolymerization initiator (manufactured by Merck Japan Co., Ltd., Runlin TPO1M=348) (this additive has a 3% molar ratio to the above monomer), and n-methyljetanolamine (Japanese). Manufactured by Hikari Junyaku Co., Ltd., M=121) 0.2
(this additive has a molar ratio of 0.5% to the above monomer) and incyanate (Sumitomo Bayer Urethane Co., Ltd.)
(This crosslinking agent has an isocyanate group of 1.0 ratio to the hydroxyl group of the above-mentioned reactive acrylic resin) was dissolved in 500 parts of ethyl acetate and mixed. This mixture was applied to ABS net (manufactured by Royal Resin Co., Ltd., film thickness 500 μm) using an applicator, dried at 80°C for 30 minutes, and a colored layer of 70 μm was applied.
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° C. for 30 seconds, it was vacuum-formed into a 10100×100×10 plate-shaped mold, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board was irradiated with 5,000 mJ of ultraviolet light using a UV irradiation device to cure the sheet.

100 parts of diacrylic polyol (manufactured by Nippon Shokubai Kagaku Co., Ltd., Alotane 183.7H=40°C, 0H=80) and a red organic pigment (manufactured by Toyo Ink Co., Ltd., Lionogen Red YS)
K) 100 parts and acrylic monomer (manufactured by Nippon Kayaku Co., Ltd.,
Karayad DPCA-20, M=807, number of double bonds 6
), 2.5 parts of a photopolymerization initiator (manufactured by Merck Japan Co., Ltd., Lucirin TPO, M=348) (the additive has a molar ratio of 3.0% to the above monomer), and n-methyl Jetanolamine (manufactured by Wako Pure Chemical Industries, Ltd., M = 121
) 0.2 part (this additive is 0.5% based on the above monomer)
molar ratio) and incyanate (manufactured by Sumitomo Bayer Urethane Co., Ltd., Sumidur N3200, NGO = 23.
0) 26 parts (the Kono crosslinking agent has 1.0 equivalent of isocyanate groups relative to the hydroxyl groups of the above-mentioned reactive acrylic resin)
It was dissolved in 500 parts of ethyl acetate and mixed. 1 This mixture was applied to an ABS sheet (manufactured by Royal Resin Co., Ltd., film thickness: sooμm) using an applicator, and then dried at 80'C for 30 minutes to form a photocurable sheet with a transparent layer of 50μm and a base material of 500μm. It was 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 1100×100×loa, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board was irradiated with 5,000+J of ultraviolet light using a UV irradiation device to cure the sheet.

Large m Acrylic polyol (manufactured by Nippon Shokubai Kagaku Co., Ltd., 70ri7
183.7H=40℃, 0H=80), 100 parts of carbon black (Mitsubishi Kasei Corporation, MA-100), and acrylic monomer (Nippon Kayaku Co., Ltd., Karayad D)
PCA-20.
PO1M=348) 2.5 parts (this additive has a 3% molar ratio to the above monomer) and n-methyljetanolamine (manufactured by Wako Pure Chemical Industries, Ltd., M=121) 0.2 parts (
This additive has a molar ratio of 0.5% to the above monomer) and 29 parts of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate EH, NC○ = 21) (this crosslinking agent is added to the hydroxyl group of the above reactive acrylic resin). (having 1.0 equivalent of incyanate group) was dissolved in 500 parts of ethyl acetate and mixed.

This mixture was made of ABS sheet (manufactured by Royal Resin Co., Ltd., film thickness 5).
00μm) using an applicator, and then heated to 80'C.
Dry for 30 minutes to form a colored layer of 50 μm + base material of 500 μm.
A photocurable sheet was 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 10100×100×10 plate-shaped mold, and ABS resin was injected to obtain an ABS plate. The surface of this ABS board is irradiated with ultraviolet rays for 5. The sheet was cured by OOOmJ irradiation.

Hiju vinyl chloride resin sheet (manufactured by Uzukumizu Kagaku Kogyo Co., Ltd., Tack Paint White 50μ) was coated with Aku-A nor-based adhesive (Soken Kagaku Co., Ltd.).
Co., Ltd., SK Dyne 1310) 30μ [iL, this is A
It was attached to a BS sheet (manufactured by Royal Resin Co., Ltd., film thickness 500 μm).

The sheet obtained in this way is molded using an injection molding machine.
After heating at 50° C. for 30 seconds, it was vacuum-formed into a 10100×LOOX Lo plate-shaped mold, and ABS resin was injected to obtain an ABS plate.

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 is expressed by color difference ΔE and gloss retention rate (%) after 300 hours using an accelerated exposure tester (Isosuper UV tester). Acid resistance is 0. I
This is a 24-hour spo-nod test (20'C) of N sulfuric acid.

Alkali resistance is 0. 24-hour spot test (20°C) of IN sodium hydroxide. Hot water resistance is 40
This is a 10 day immersion test at °C.

(Effects of the Invention) According to the present invention, general-purpose resins can be used as molding resins, and molded products with excellent surface hardness and weather resistance can be manufactured, which can be used as automobile parts, building materials, etc. It can be suitably used. Furthermore, compared to the case where the surface of a molded product is painted, the number of steps can be omitted and productivity is improved.

4. No. B Figure 1(a) is a schematic diagram showing an example of the apparatus used in the method for producing 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 an A schematic diagram showing the process of irradiating the coated body with ultraviolet rays, and Figure 3 is an explanatory diagram thereof.

DESCRIPTION OF SYMBOLS 1... Photocurable sheet, 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. Acrylic resin having a glass transition point of 0 to 100°C and having a reactive functional group that is solid at room temperature, a crosslinking agent that can react with the reactive functional group of the acrylic resin, a compound having a reactive vinyl group, and light A photocurable sheet formed by laminating a photocurable resin layer formed from a resin composition containing a polymerization initiator and a sheet base material is placed on the inner surface of a mold. The photocurable sheet is formed by injection molding resin into the mold to form a coating covered with the photocurable sheet, and then the coating is irradiated with light to form the photocurable sheet. A method for manufacturing molded products that is cured.