JP2002363318A - Method for producing silicone rubber molded article - Google Patents

Abstract

(57) [Summary] After irradiating a surface of a silicone rubber molded body with an electron beam so that an absorbed dose becomes 100 kGy or more,
A method for producing a silicone rubber molded article, comprising providing one or more of a coloring layer, a transparent layer and an adhesive layer. According to the present invention, by irradiating a silicone rubber molded product with an electron beam, a silicone rubber molded product having improved wettability and adhesion of the colored layer, the transparent layer, and the adhesive layer can be obtained. Due to poor adhesion of the groove or groove, poor coating,
This is an effective method for preventing light leakage and electromagnetic wave leakage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicone rubber molded article having a colored layer, a transparent layer or an adhesive layer, and more particularly to a keyboard, a tablet input device and an electronic component of various electronic devices. The present invention relates to a method for producing a silicone rubber molded article that is useful for a composite with a cover member for a push button switch displaying information or the like, a metal material, a plastic member, and a ceramic member.

[0002]

2. Description of the Related Art Conventionally, when a silicone rubber molded article having a colored layer is produced, an unvulcanized rubber is inserted into a mold, heated and pressurized to vulcanize, and then removed from the mold. A method of printing letters, numbers, symbols, signs, and the like indicating the functions, roles, and the like of the molded body at predetermined positions using a technique such as screen printing is adopted. In addition, Japanese Unexamined Patent Publication
Japanese Patent Application Laid-Open No. 1-110582 discloses that a cover member for a rubber push button switch, which is an example of a silicone rubber molded body with a colored layer, is formed by integrally molding a code printed on a transfer plate with the cover member in a mold. A method of making is disclosed. Further, Japanese Patent Application Laid-Open No. 3-43918 discloses a method in which a character or the like is transferred by using a thermoplastic resin sheet on which a character or the like is printed and transferring the character or the like by heating and pressing in an unvulcanized rubber and a mold. A method for producing a silicone rubber molded article is disclosed. In addition, Japanese Patent Application Laid-Open No. H10-315393
Japanese Patent Application Laid-Open Publication No. H11-157, discloses a method of forming a colored layer using a transfer sheet after subjecting a silicone rubber molded body to a physical surface treatment.

[0003] Conventionally, methods for physical surface treatment of a silicone rubber molded body for improving adhesiveness include corona discharge treatment, low-temperature plasma treatment, plasma polymerization treatment, flame treatment, ultraviolet treatment, electron beam treatment, ion beam treatment, and ion beam treatment. Injection treatment and the like are known, but low-temperature plasma treatment, plasma polymerization treatment, and ion implantation treatment are difficult to perform continuously, and corona discharge treatment and ultraviolet treatment have a problem in persistence of the effect of improving adhesion. Electron beam treatment was not sufficient in the effect of improving adhesion by ordinary irradiation.

[0004]

That is, silicone rubber has a unique hydrophobicity and surface energy due to the stability of silicon-oxygen bond and side chains such as methyl group having high rotational freedom, and thus has different materials. There are a number of problems with surface treatment methods that add affinity to

[0005] For example, the biggest problem of the plasma treatment and ultraviolet irradiation treatment currently employed is the loss of hydrophilicity due to aging. Expires in seconds to minutes depending on processing conditions. As a cause of this, the formed hard oxide film
This phenomenon is described as a phenomenon of getting inside the soft silicone rubber. In addition, the formation of an oxide film due to the partial destruction of stable silicone rubber is presumed to be the progress of partial oxidation of terminal molecular chains and unsaturated bonds that exist at a relative probability. It was necessary to sufficiently manage the processing conditions, temperature, humidity, and standing time after surface treatment.

[0006] Surface treatment of silicone rubber having a large number of three-dimensional shapes without smoothness is very difficult. In particular, in a molded article having a wall surface or a deep groove of a molded article having an adjacent height, straight plasma or ultraviolet light does not reach a shaded portion. For this reason, the work is bent uniformly, and a device that is exposed to plasma or ultraviolet rays is implemented. However, it is impossible to completely perform surface treatment of a molded product having a complicated shape by the conventional method.

The present invention has been made in view of the above circumstances, and provides a method for producing a silicone rubber molded article capable of obtaining a silicone rubber molded article having improved wettability and adhesion of a colored layer, a transparent layer or an adhesive layer. The purpose is to provide.

[0008]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that a colored layer is formed by spray coating, flow coater, dipping, screen printing, transfer printing or the like. When forming a transparent layer and an adhesive layer, etc., we focus on the fact that the surface of the vulcanized silicone rubber molded body may be chemically changed in advance. For this purpose, the silicone rubber molded body absorbs electron beams. It is effective to provide a colored layer, a transparent layer or an adhesive layer after irradiation so that the dose is 100 kGy or more, and that the treatment effect when the treatment is applied to the silicone rubber molded article is 2 days or more. The present inventors have found that they are effective for the surface treatment of the wall forming portion and the groove forming portion of the gap of the silicone rubber molded article.

Therefore, according to the present invention, after irradiating the surface of the silicone rubber molded body with an electron beam so that the absorbed dose becomes 100 kGy or more, any one or more of the colored layer, the transparent layer and the adhesive layer is applied. A method for producing a silicone rubber molded article, and irradiating a surface of a wall forming portion or a groove forming portion of a gap of a three-dimensional silicone rubber molded article with an electron beam so that an absorbed dose becomes 100 kGy or more. And a coating or hard coating treatment to provide one or more of a colored layer, a transparent layer, and an adhesive layer.

In this case, the silicone rubber molded article is irradiated with an electron beam so that the absorbed dose becomes 100 kGy or more, and then provided with an adhesive layer made of a resin which is cured by irradiation with visible light, ultraviolet light or electron beam. By further providing a colored layer and / or a transparent layer, the adhesiveness is further improved. In this case, the colored layer and / or the transparent layer are provided between the silicone rubber molded article and the colored layer and / or the transparent layer. It is effective to provide an adhesive layer having a lower Young's modulus.

In the present invention, the electron beam can be irradiated under atmospheric pressure. In addition, electron beams are scattered by thin metal foil such as titanium, which is called a window, which separates a vacuum electron beam generator from an irradiator of atmospheric pressure, and nitrogen and oxygen atoms in the atmosphere. And arrive at the deep groove to enable surface treatment.

Hereinafter, the present invention will be described in more detail.
In the present invention, first, an absorbed dose of 100 kG is applied to a vulcanized silicone rubber molded product using an electron beam irradiation device.
The electron beam is irradiated so as to be y or more. If the absorbed dose of the electron beam is less than 100 kGy, the adhesion between the silicone rubber molded article and the colored layer and / or the transparent layer is insufficient, and no modification effect is observed. On the other hand, if it exceeds 3,000 kGy, the surface of the silicone rubber molded article becomes hard, so that a desirable electron beam absorption dose is 400 to 3,000 kGy.

In this case, as a result of analyzing the surface of the silicone rubber molded body, organic groups bonded to silicon atoms such as methyl groups are uniformly reduced on the surface 10 ° where electrons have reached, oxygen is increased, and an oxide film is formed. Turned out to be. The aging of this oxide film hardly changed even with the lapse of time.
A surface treatment activity of 000 times and 500 times or more of the plasma method was observed. The cause is presumed to be that a stable oxide film was formed by selectively attacking organic groups bonded to silicon atoms, such as side-chain methyl groups, in which high-energy electrons were uniformly dispersed on the silicone rubber surface. Is done.

Here, the silicone rubber molded article may be a known one, and a cured and vulcanized silicone rubber composition of various curing systems can be used. For example, a hydrogen atom (SiH) bonded to a silicon atom as a crosslinking agent is added to an organopolysiloxane having two or more alkenyl groups such as a vinyl group in one molecule (dimethylpolysiloxane, dimethylsiloxane-methylvinylsiloxane copolymer, etc.). Base)
Reaction-curable Silicone Rubber Composition Using Organohydrogenpolysiloxane Having Two or More in a Molecule and Platinum Catalyst or Organic Peroxide-Curable Silicone Rubber Using Organic Peroxide as Crosslinking Agent Composition,
The α, ω-dihydroxy or dialkoxyorganopolysiloxane is appropriately blended with a hydrolyzable silane, a redox catalyst such as cobalt naphthenate and dimethylaniline, and a crosslinking agent such as sulfur, sulfur homologues, metal oxides, and isocyanate. Molded and cured room temperature curable silicone rubber compositions and the like are used. The silicone rubber composition further includes butadiene rubber, isoprene rubber,
Various rubbers and fillers such as ethylene propylene rubber, perfluoropropylene-vinylidene fluoride rubber, chloroprene rubber, urethane rubber, etc., coloring agents, heat-resistant agents, weathering agents, flame-retardant agents, fungicides, conductive agents, etc. May be added.

In the present invention, a colored layer, a transparent layer or an adhesive layer is formed after irradiating the surface of the silicone rubber molded body with an electron beam so as to have an absorbed dose of 100 kGy or more.

In this case, the colored layer, the transparent layer or the adhesive layer, in particular, the colored layer and the transparent layer comprise: (A) a number average molecular weight of at least two ethylenically unsaturated groups in one molecule of from 800 to 10,000. (B) Urethane acrylate having a number average molecular weight of 200 to 800 and having at least two ethylenically unsaturated groups in one molecule 10 to 200 parts by weight (C) Reactive diluent 10 to 1 2,000 parts by weight (D) Photopolymerization initiator 0 to 30 parts by weight (E) Pigment 0 to 100 parts by weight It is preferable that the composition be a cured film of an ultraviolet or electron beam curable composition. The composition can be obtained by applying the composition to a silicone rubber molded article to a thickness of 0.01 to 0.1 mm, irradiating with ultraviolet rays or an electron beam, and curing the composition. In order to cure the composition, for example, it is sufficient to irradiate ultraviolet rays of 50 mJ / cm ² or more in the case of ultraviolet irradiation, and to apply a voltage of 50 to 50 in the case of electron beam irradiation.
An electron beam obtained by accelerating electrons at 300 kV may be irradiated so as to have an absorbed dose of 10 to 100 kGy. A colored layer colored with a pigment is preferable because the electron beam can be uniformly cured to the inside.

Hereinafter, the colored layer and the transparent layer will be described in more detail. (A) at least 2 components per molecule
The number average molecular weight of the polyether polyurethane having one ethylenically unsaturated group is from 800 to 10,000, especially 1,
000-5,000. When the number average molecular weight is less than 800, the obtained cured film does not elongate, and the
If it is larger than 00, the hardness and Young's modulus are lowered, and the effect of preventing damage is reduced. The polyether polyurethane having at least two ethylenically unsaturated groups in one molecule is obtained, for example, by reacting a diol having an oxyalkylene group having 2 to 10 carbon atoms with a diisocyanate and a compound having an ethylenically unsaturated group. Is obtained by

Here, specific examples of the diol having an oxyalkylene group having 2 to 10 carbon atoms include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 2-methyltetrahydrofuran glycol, 3-methyltetrahydrofuran glycol, and polyheptamethylene. Glycol, polyhexamethylene glycol, polydecamethylene glycol, polyalkylene oxide adduct of bisphenol A diol, and the like. Polypropylene glycol, polytetramethylene glycol, 2-methyltetrahydrofuran glycol, 3-methyltetrahydrofuran glycol, Methyltetrahydrofuran glycol is preferred. As the polyalkylene oxide, not only the homopolymer but also a random or block copolymer thereof can be used.

Examples of the diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, and p-isocyanate. Phenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-
Trimethylhexamethylene diisocyanate and the like can be mentioned, and among them, hexamethylene diisocyanate, isophorone diisocyanate and the like are more preferable because yellowing hardly occurs. These diisocyanates may be used alone or in combination of two or more.

Further, examples of the compound having an ethylenically unsaturated group include (meth) acrylic compounds having a hydroxyl group, an acid halide group, and an epoxy group. Examples of the (meth) acrylic compound having a hydroxyl group include 2-hydroxyethyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate.
Examples include hydroxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, glycerin di (meth) acrylate and the like, and adducts of glycidyl group-containing compounds such as alkyl glycidyl ether and glycidyl (meth) acrylate with (meth) acrylic acid. Can be

Examples of the (meth) acrylic compound having an acid halide group include (meth) acrylic chloride and (meth) acrylic bromide.

Examples of the (meth) acrylic compound having an epoxy group include glycidyl esters of (meth) acrylic acid.

The polyether polyurethane having two ethylenically unsaturated groups in one molecule can be prepared, for example, by subjecting the above diol and diisocyanate to OH / NCO = 0.
After reacting at 5 to 2.0 (molar ratio), it can be further produced by reacting a compound having an ethylenically unsaturated group.

(B) at least 2 components per molecule
The urethane acrylate having two ethylenically unsaturated groups is for improving the hardness of the film, and has a number average molecular weight of 200 to 800, preferably 300 to 60.
0. If the number average molecular weight is more than 800, the hardness and Young's modulus of the cured film become low, and if it is less than 200, it is difficult to synthesize.

Component (A) has a number average molecular weight of 800 to 1 having at least two ethylenically unsaturated groups in one molecule.
The urethane acrylate having a number average molecular weight of 200 to 800 and having at least two ethylenically unsaturated groups in one molecule of the component (B) is preferably 10 to 200 parts by weight, based on 100 parts by weight of the 0000 polyether polyurethane. Is used in a proportion of 50 to 100 parts by weight. When the amount is less than 10 parts by weight, the hardness of the obtained film, the Young's modulus is low, and the effect of preventing damage is reduced. When the amount exceeds 200 parts by weight, the elongation is reduced, and the flexibility and the followability to the base material are lost. If used for a long period of time, it may peel off from the substrate or cracks may occur.

The urethane acrylate having at least two ethylenically unsaturated groups in one molecule can be obtained, for example, by reacting a diisocyanate and a compound having an ethylenically unsaturated group. As the compound having a group, the same compounds as those used in the component (A) can be used.

The components (A) and (B) may be separately synthesized and mixed, or may be synthesized at once.

The reactive diluent (C) is used for the purpose of reducing the viscosity of the coating material. (A) The reactive diluent is 10 to 1,000 parts by weight based on 100 parts by weight of the component.
Although 0 parts by weight can be used, 100 to 300 parts by weight is desirable. If the amount of the reactive diluent is less than 10 parts by weight, the effect of lowering the viscosity is small, and if it is more than 1,000 parts by weight, the properties of the cured film are impaired. As the preferred reactive diluent, the following monofunctional, bifunctional, and polyfunctional compounds can be used.

(Monofunctional compound) Examples of the N-vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylacetamide, N-vinylformamide, and the like. Examples of compounds having a structure in which (meth) acrylic acid is bonded by an amidation reaction or an esterification reaction include methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate, and nonylphenoxypolyethylene glycol (meth). ) Acrylate, nonylphenoxy polypropylene glycol (meth) acrylate, 3-
Chloro-2-hydroxypropyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, butoxypolyethylene glycol (meth) acrylate,
Alkyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, cumylphenol (meth)
Acrylate, cumylphenoxy polyethylene glycol (meth) acrylate, cumylphenoxy polypropylene glycol (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dicyclopentadiene (meth)
Acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, 3-acryloyloxyglycerin mono (meth) acrylate-
2-hydroxybutyl (meth) acrylate, 2-hydroxy-1- (meth) acryloxy-3- (meth) acryloxypropane, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polyε-caprolactone mono (Meth) acrylate, dialkylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, mono [2- (meth) acryloyloxyethyl] acid phosphate, trichloroethyl (meth) acrylate, 2,2,3,3-tetra Fluoropropyl (meth) acrylate, 2,2,3,4,4,4-hexafluorobutyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopen Sulfonyloxy alkyl (meth) acrylate, tricyclodecanyl (meth) acrylate, tricyclodecanyl (meth) acrylate, isobornyl (meth) acrylate, morpholine (meth) acrylate. Above all, isobornyl (meth) acrylate is
As a reactive diluent of the components (A) and (B), it is particularly preferable because it has excellent viscosity lowering ability, and the obtained cured film has advantages of high Young's modulus, high hardness and little decrease in elongation.

(Bifunctional Compound) As the bifunctional compound, specifically, di (meth) acrylate of 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, Ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) ) Acrylate, 1,6-hexanediol di (meth) acrylate, glycol di (meth) acrylate, neopentylglycerin di (meth) acrylate, bisphenol A
Di (meth) acrylate of ethylene oxide adduct of bisphenol A, di (meth) acrylate of propylene oxide adduct of bisphenol A, di (meth) acrylate of 2,2′-di (hydroxyethoxyphenyl) propane,
Tricyclodecane dimethylol di (meth) acrylate, dicyclopentadiene di (meth) acrylate, pentane di (meth) acrylate, di (meth) acrylic acid adduct of 2,2-bis (glycidyloxyphenyl) propane, and the like. Can be

(Polyfunctional compound) Examples of the polyfunctional compound include trimethylolpropane tri (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol hexa. (Meth) acrylate, tris (acryloxymethyl)
Examples include isocyanurate, tris (acryloxyethyl) isocyanurate, tris (acryloxypropyl) isocyanurate, triallyl trimellitic acid, triallyl isocyanurate and the like.

The type of the reactive diluent used is not particularly limited as long as it does not significantly reduce the properties of the cured film.

The reactive diluent containing a nitrogen atom is (A)
In addition to the effect of lowering the viscosity of the component polyether polyurethane, it has the effect of promoting reactivity when irradiated with ultraviolet rays or electron beams. Specific examples of the nitrogen atom-containing reactive diluent include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylacetamide, N-vinylformamide, N, N′-divinylethyleneurea, and the like. One or more of them can be used in combination.

Further, a known photopolymerization initiator can be used as the component (D) in order to improve the curability by ultraviolet rays. As a specific photopolymerization initiator, for example, 1
-Hydroxycyclohexyl phenyl ketone, 2,2-
Dimethoxy-2-phenylacetophenone, phenylacetophenone diethyl ketal, alkoxyacetophenone, benzylmethyl ketal, benzophenone and 3,3-dimethyl-4-methoxybenzophenone, 4,
Benzophenone derivatives such as 4-dimethoxybenzophenone and 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl)
Ketones, benzyl derivatives such as benzyl and benzyl methyl ketal, benzoin derivatives such as benzoyl and benzoin butyl methyl ketal, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 2,4-diethylthioxanthone and 2,4-dichloro Thioxanthone derivatives such as thioxanthone, fluorene, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, 2-benzyl-2
Phosphines such as -dimethylamino-1- (morpholinophenyl) -butanone-1,2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide Oxide derivatives are mentioned.

The photopolymerization initiator of the component (D) can be used in an amount of 0 to 30 parts by weight based on 100 parts by weight of the component (A). In the case of electron beam curing, a photopolymerization initiator is not necessarily required,
In the case of ultraviolet curing, the photopolymerization initiator of the component (D) is 1 to 3
0 parts by weight are required.

The pigment of the component (E) can be used in an amount of 0 to 100 parts by weight with respect to 100 parts by weight of the component (A), if necessary. In addition, the second layer may be a transparent layer to which no pigment is added. As the pigment that can be used in the present invention, for example, yellow is fast yellow, disazo yellow, flavantron yellow, etc., red is naphthol red, cyanicidine red, strontium red, etc.
Blue is phthalocyanine blue, alkali blue, cyanicidine blue, etc., green is phthalocyanine green, naphthol green, malachite green, etc., purple is quinacdrine violet, dioxazine violet, naphthol violet, etc., black is carbon black, aniline black, etc. Can be exemplified by titanium dioxide and the like.

If necessary, a sensitizer, an antioxidant, an ultraviolet absorber, an organic solvent, a plasticizer, a surfactant, a silane coupling agent, an organic Alternatively, additives such as inorganic particles can be added within a range that does not impair the purpose of the present invention.

In order to further strengthen the adhesion between the silicone rubber molded article and the colored layer and / or the transparent layer, an adhesive layer is provided between the silicone rubber molded article irradiated with the electron beam and the colored layer and / or the transparent layer. Can be provided.

Since the adhesive layer is formed on a flexible silicone rubber molded article, when a stress is applied to the colored layer and / or the transparent layer, the adhesive layer is distorted and cracks or peels off. Therefore, it is necessary to have flexibility, and it is desirable that the coloring layer and / or the transparent layer have a Young's modulus lower than that of the transparent layer. The Young's modulus of the adhesive layer is １ ／ of the Young's modulus of the colored layer and / or the transparent layer.
The following is more desirable.

Although the composition of the adhesive layer is related to the composition of the colored layer and the transparent layer, when the colored layer or the transparent layer is mainly composed of urethane acrylate, it is preferable to select the urethane acrylate type. For example, the above (A) to
What used the (D) component in the said amount can be used. In this case, the adhesive layer is compared to the colored layer and the transparent layer,
It is desirable that the component (A) has a large number average molecular weight and the component (B) has a small content.

In order to further strengthen the adhesion between the silicone rubber molded article and the adhesive layer, a silane coupling agent can be added to the adhesive layer. When an amino-based silane compound is used as the silane coupling agent, the environmental resistance to high temperature and high humidity is good. Specific examples of the amino-based silane compound include n-β- (aminoethyl) γ-aminomethyldimethoxysilane, n-β- (aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ -Aminopropyltriethoxysilane and the like. The silane coupling agent may be added in an amount of 0.1 to 5.0 parts by weight, preferably 1.0 to 3.0 parts by weight, based on 100 parts by weight of the resin of the adhesive layer.
When the amount is less than 0.1 part by weight, the adhesive force with the silicone rubber molded article cannot be obtained, and when the amount exceeds 5.0 parts by weight, when an amino-based silane compound is used, the color is changed to yellow due to heat treatment or the like. This is because it is not preferable.

The thickness of the adhesive layer is preferably from 0.01 to 20 μm, particularly preferably from 0.1 to 10 μm. 0.01 μm
If it is less than 20 μm, the adhesiveness is insufficient, and if an amino-based silane compound is added, if it exceeds 20 μm, the yellowness becomes strong, which may cause an undesirable appearance.

As a method of applying the above-mentioned adhesive layer, colored layer, and transparent layer on the silicone rubber molded article irradiated with the electron beam, a method capable of forming a layer having a uniform thickness may be selected. Known methods such as spray coating, dipping coating and the like can be used.

[0044]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, in the following examples, a part shows a weight part.

[Example 1] An electron beam irradiator "Light Beam-L" (trade name, manufactured by Iwasaki Electric Co., Ltd., trade name) was applied to a vulcanized silicone rubber molded body at an accelerating voltage of 100 kV.
The electron beam was irradiated while changing the absorbed dose to 400 kGy and 800 kGy.

Table 1 shows the results obtained by measuring the proportion of atoms on the surface of the silicone rubber molded product by ESCA. It was confirmed that those irradiated with an electron beam had a reduced number of carbon atoms as compared with those not irradiated, and had undergone a chemical change.

[0047]

[Table 1]

On the other hand, 13.2 parts (0.0132 mol) of tetramethylene glycol having a molecular weight of 2,000 and 26.4 parts (0.0132 mol) of polypropylene glycol having a molecular weight of 1,000 were added to toluene diisocyanate.
8.5 parts (0.164 mol) were reacted, and 31.8 parts (0.27 mol) of hydroxyethyl acrylate were reacted in a conventional manner to obtain 55 parts of polyether urethane acrylate having a number average molecular weight of 2,080 and 55 parts of molecular weight. A mixture of 406 urethane acrylates (45 parts) was obtained. Further, 50 parts of isobornyl acrylate, 50 parts of N-vinylcaprolactam, and 5 parts of cyanine-based blue pigment are added as reactive diluents, and the mixture is stirred until uniform to prepare an electron beam-curable urethane acrylate-based blue ink. did. Its viscosity at 25 ° C. was 225 mPa · s. Next, two days after irradiating the silicone rubber molded body with an electron beam, the above-mentioned ink was applied to the electronically treated surface by spray coating so as to have a film thickness of about 30 μm. -L "(trade name, manufactured by Iwasaki Electric Co., Ltd.)
Was used to irradiate an electron beam at an acceleration voltage of 100 kV and an absorbed dose of 30 kGy to form a colored layer. The wettability and adhesion of the colored layer were examined. Table 2 shows the results.

The wettability was visually inspected for the repellency of the ink, and the adhesion to the silicone rubber was examined by a crosscut cellotape (registered trademark) peel test to determine the adhesiveness. Adhesion rate 1
00/100 indicates 100% adhesion.

Example 2 A transparent coating material was prepared by removing the cyanine-based blue pigment from the urethane acrylate-based blue ink used in Example 1. Its viscosity is 25
It was 130 mPa · s at ° C. A silicone rubber molded article was coated in the same manner as in Example 1 except that a transparent coating material was used instead of the blue ink, and a transparent layer was formed by electron beam irradiation. The wettability and adhesiveness of the transparent layer were examined.
Table 2 shows the results.

[Example 3] In the same manner as in Example 1, a silicone rubber molded body irradiated with an electron beam was subjected to a screen printing method to form a translucent UV-curable resin comprising urethane acrylate, epoxy acrylate, photopolymerization initiator and the like. A mixture of 2 parts of silane coupling agent "KBM603" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts of printing ink "Sericol UV FIL Medium" (trade name, manufactured by Teikoku Printing Ink Mfg. Co., Ltd.) is blended. The adhesive layer was applied to a thickness of about 10 μm, and was cured by irradiating an ultraviolet ray having an irradiation energy of 1,000 mJ / cm ² using a metal halide lamp. The electron beam-curable urethane acrylate-based blue ink used in Example 1 was applied on the adhesive layer by spray coating so as to have a film thickness of about 30 μm, and cured in the same manner as in Example 1 to wet the adhesive layer and the colored layer. Properties and adhesion were examined.
Table 2 shows the results.

Comparative Example 1 The wettability and adhesion of the colored layer were examined in the same manner as in Example 1 except that the silicone rubber molded article was not irradiated with an electron beam. Table 2 shows the results.

[Comparative Example 2] The wettability and adhesiveness of the adhesive layer and the colored layer were examined in the same manner as in Example 3 except that the silicone rubber molded article was not irradiated with an electron beam. Table 2 shows the results.

[0054]

[Table 2] * Wettability of colored layer to adhesive layer

[0055]

According to the present invention, by irradiating the silicone rubber molded product with an electron beam, a silicone rubber molded product having improved wettability and adhesion of the colored layer, the transparent layer and the adhesive layer can be obtained. It is an effective method for preventing light leakage and electromagnetic wave leakage due to poor adhesion of the side surfaces and grooves and poor coating.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Konishi 2-3-1-1, Isobe, Annaka-shi, Gunma Shin-Etsu Kagaku Kogyo Co., Ltd.Precision Functional Materials Laboratory (72) Inventor Kinji Kuroiwa Yoshino-cho, Saitama-shi, Saitama 1-406-1 Shin-Etsu Polymer Co., Ltd. (72) Inventor Takato Kobayashi 300-F Tohara, Motohara, Kamikawa-cho, Kodama-gun, Saitama F-5 Term in Shin-Etsu Polymer Co., Ltd. 4F006 AA42 AB37 BA01 BA02 CA08 EA03

Claims (5)

[Claims] 1. After irradiating the surface of the silicone rubber molded body with an electron beam so that the absorbed dose becomes 100 kGy or more,
A method for producing a silicone rubber molded article, comprising providing one or more of a coloring layer, a transparent layer and an adhesive layer. 2. A method of coating or hard-coating after irradiating the surface of the wall forming portion or groove forming portion of the gap of the three-dimensional silicone rubber molded body with an electron beam so that the absorbed dose becomes 100 kGy or more. Providing a colored layer, a transparent layer, and an adhesive layer, or one or more layers. 3. The colored layer, the transparent layer or the adhesive layer comprises: (A) 100 parts by weight of a polyether polyurethane having a number average molecular weight of 800 to 10,000 and having at least two ethylenically unsaturated groups in one molecule. B) Urethane acrylate having a number average molecular weight of 200 to 800 having at least two ethylenically unsaturated groups in one molecule 10 to 200 parts by weight (C) Reactive diluent 10 to 1,000 parts by weight (D) Light The silicone rubber molded product according to claim 1 or 2, which is a cured film of an ultraviolet or electron beam curable composition containing 0 to 30 parts by weight of a polymerization initiator (E) 0 to 100 parts by weight of a pigment. Production method. 4. An adhesive layer having a Young's modulus lower than that of the colored layer and / or the transparent layer between the silicone rubber molded article and the colored layer and / or the transparent layer.
Or a method for producing a silicone rubber molded article according to item 3. 5. The method for producing a silicone rubber molded product according to claim 1, wherein the adhesive layer contains a silane coupling agent.