JP4880417B2 - Surface protection method for workpieces - Google Patents

Description

The present invention provides a protective film for cutting workpieces when processing various members, a protective film from cutting scraps, and the like for protecting unnecessary portions of coating and printing when coating or printing on the workpiece with ink or the like. A surface protective film for temporary fixing (hereinafter, simply referred to as “protective film”), and a suitable surface protective curable composition and an adhesive made of the surface protective curable composition were used. The present invention relates to a method for protecting a surface of a workpiece.

For processing metal plates, molds, aluminum sashes, plastic plates, semiconductor wafers, circuit boards, ceramics, optical parts such as glass and quartz, electronic and electronic parts such as sensors, especially precision processing such as cutting, grinding and polishing By covering the functional surfaces such as the processed surface, circuit and sensor part of the work piece, it is possible to prevent damage from cutting water, scratches and contamination from cutting waste, etc. A surface fixing material for temporary fixing to protect is widely used. In addition, as a surface protective material, the pressure sensitive adhesive sheet which gave the adhesive process on base materials, such as a film and a sheet | seat, is mainly used.

Also, in the plating process used on circuit boards such as printed wiring boards, pressure sensitive adhesive sheets were cut into any shape as a protective material to prevent contamination by the plating solution in areas where plating is unnecessary on the circuit. Things are used as masking material.

In addition to electronic and electrical parts, various industrial products such as nameplates, various nameplates such as logos, instrument scales, decorations, etc. are painted and variously printed by various printing methods. Even when there is an unnecessary part for printing, a pressure-sensitive adhesive sheet is applied to the part, followed by painting and printing.

However, when the pressure-sensitive adhesive sheet is used as a protective film when processing a workpiece, the pasting work becomes more complicated and the pasting position is slightly smaller with the recent miniaturization and miniaturization of parts. There is a defect that causes a defect in the product yield and design properties due to misalignment, and if the part has irregularities, the sheet cannot follow the irregularities, causing peeling during processing and contaminating the workpiece. There is a case. In addition, if it is intended to use a material obtained by cutting a pressure-sensitive adhesive sheet in accordance with the shape of the workpiece, there is a disadvantage in terms of cost, for example, an expensive mold is required to produce the cut product.

In order to solve these disadvantages, a UV curable composition that is removed with a specific organic solvent or aqueous alkali solution is applied to the surface of the workpiece by screen printing and cured by UV curing. However, since an alkaline aqueous solution or an organic solvent is used, the cleaning process is complicated and there is a problem in the working environment, and the surface of the workpiece is When there are fine irregularities, the organic solvent cannot sufficiently penetrate, and the protective film cannot be completely removed, causing a problem in appearance of the workpiece.
JP 59-051962 A Japanese Patent Laid-Open No. 01-234477 Japanese Patent Laid-Open No. 03-139573

Cutting metal members, molds, aluminum sashes, plastic plates, semiconductor wafers, circuit boards, ceramics, optical parts such as glass and quartz, electronic parts such as sensors, electrical parts, etc. Protective film to protect from scratches and contamination caused by water ingress and cutting waste, protective film to prevent contamination by plating solution used on circuit boards such as printed wiring boards, and various industries, not limited to electronic and electrical parts product, for example name plates, nameplates such as logos, instrument scale, ornaments such as for painting, suitable temporary protective film to the masking during printing processing, workability curable composition of excellent surface protection Is desired. In addition, when the protective film is peeled off from the workpiece after processing, there is a demand for a surface protection method that has no adhesive residue and is excellent in terms of environment and workability.

As a result of various investigations to solve these problems, the present inventors have found that a curable composition containing a specific (meth) acrylic monomer is suitable for a surface protective film when processing a workpiece. Furthermore, it is possible to apply a screen printing method to a material having a specific viscosity, and in addition, when using a protective film made of the curable composition, scratches and dirt in processing of a workpiece are processed. It has been found that a method for protecting a surface of a workpiece having characteristics that can be prevented from occurring and has no remaining surface protection peeling, has been achieved.

The present invention has the following gist.
1. After providing a protective film formed by curing the surface-protecting curable composition containing the following (A), (B), (C) and (E) on the surface of the workpiece, and processing the workpiece, A method for protecting a surface of a workpiece, wherein the protective film is immersed in warm water of 30 ° C. or higher and 90 ° C. or lower and peeled off from the workpiece.
(A) polyisoprene having one or more (meth) acryloyl groups at the terminal or side chain of the molecule and having a molecular weight of 500 or more,
(B) (meth) acrylates other than (A),
(C) Photopolymerization initiator (E) Polymerization inhibitor
2 . In the curable composition for surface protection, 20 to 90 parts by mass of (A) in 100 parts by mass of the total amount of the components (A) and (B), and 100 parts by mass of the total amount of the components (A) and (B) ( 2. The workpiece according to 1 , wherein 0.1 to 20 parts by mass of (C) is contained with respect to 10 to 80 parts by mass of B) and 100 parts by mass of (A) and (B) in total. Surface protection method.
3 . The method for protecting a surface of a workpiece according to any one of 1 to 2 , wherein the curable composition for surface protection contains (D) an inorganic filler.
4 . (D) The method for protecting a surface of a workpiece according to 3 , wherein the inorganic filler is silica.
5 . 1 wherein the viscosity of the curable composition for surface protection is 5000 mPa · s or more.
Surface protecting method of the workpiece according to any one of 1 to 4.
6 . The method for protecting a surface of a workpiece according to any one of 1 to 5 , wherein the curable composition for surface protection contains a resin containing a cyclopentadiene skeleton.
7 . The method for protecting a surface of a workpiece according to any one of 1 to 6 , wherein the curable composition for surface protection contains a polar organic solvent.
8 . The method for protecting a surface of a workpiece according to any one of 1 to 7 , wherein a protective film is provided on the surface of the workpiece, by screen printing.

The curable composition for surface protection of the present invention has photocurability because of its composition, is cured by visible light or ultraviolet light, and in a preferred embodiment, has a viscosity to which a screen printing method can be applied. Significant effects are obtained in terms of labor saving, energy saving, and work shortening. In addition, the curable composition for surface protection according to the present invention can provide a protective film that is not affected by cutting water used at the time of processing. In addition, when the protective film is peeled off from the workpiece after processing, there is no adhesive residue, and the film is easily peeled off, so that the workability is excellent. Furthermore, in the method for protecting the surface of the workpiece using the curable composition for surface protection of the present invention, the protective film obtained from the curable composition for surface protection of the present invention is warm water of 30 ° C. or higher, particularly 90 ° C. Since it has the property of reducing the adhesive strength by contacting the following hot water and reducing the bonding force between the members or between the member and the jig, there is a feature that the member can be easily recovered, compared to the conventionally known technology, A remarkable effect is obtained that it is not necessary to use an organic solvent that is expensive, strongly ignitable, or generates a gas harmful to the human body.

The (meth) acrylate having at least one (meth) acryloyl group at the terminal or side chain of the molecule (A) used in the present invention and having a molecular weight of 500 or more includes 1,2-polybutadiene-terminated urethane (meta ) Acrylate (for example, “TE-2000”, “TEA-1000” manufactured by Nippon Soda Co., Ltd.), the hydrogenated product (for example, “TEAI-1000” manufactured by Nippon Soda Co., Ltd.), 1,4-polybutadiene-terminated urethane (meth) Acrylate (for example, “BAC-45” manufactured by Osaka Organic Chemical Co., Ltd.), polyisoprene terminated (meth) acrylate, polyester urethane (meth) acrylate, polyether urethane (meth) acrylate, polyester (meth) acrylate, bis A type Epoxy (meth) acrylate (for example, “Biscoat # 540” manufactured by Osaka Organic Chemical Co., Ltd., Showa Examples thereof include (meth) acrylates in which one or more (meth) acroylated oligomers / polymers having a molecular weight of 500 or more such as “Biscoat VR-77” manufactured by Kobunshi Co., Ltd. are formed at the terminal or side chain. The molecular weight of the (meth) acrylate is selected to be 500 or more for the reason of securing a viscosity that can be screen-printed. Although there is no need to technically determine the upper limit, the curable composition for surface protection is preferably liquid from the viewpoint of workability, and is 100,000 or less for reasons of solubility in other (meth) acrylate monomers. Are preferred.

Regarding (A), it is at least one selected from the group consisting of polybutadiene, polyisoprene, and the former two hydrogenated products when the cured product of the surface-protecting curable composition is immersed in warm water. This is preferable because the property of the cured body to peel from the kimono (hereinafter simply referred to as “peelability”) is promoted.

In the present invention, (A) the addition amount of (meth) acrylate having one or more (meth) acryloyl groups at the end or side chain of the molecule and having a molecular weight of 500 or more is the ratio of (A) and (B). 20-90 mass parts is preferable in the total amount of 100 mass parts. If it is 20 parts by mass or more, the releasability is sufficient, and a viscosity capable of screen printing can be secured. Moreover, if it is 90 mass parts or less, a viscosity raise will be produced and workability | operativity will not fall.

(A) The (meth) acrylate having one or more (meth) acryloyl groups at the end or side chain of the molecule and having a molecular weight of 500 or more is preferably hydrophobic. In the case of water solubility, it is not preferable because the cured product of the surface-protecting curable composition may swell or partially dissolve during cutting, which may cause positional displacement and inferior processing accuracy. However, the cured product of the curable composition for surface protection may be used as long as it is not greatly swollen or partially dissolved by water.

As (meth) acrylates other than (B) (A) used in the present invention, as monofunctional (meth) acrylate monomers, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) ) Acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopenta Nyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, methoxylated cyclodecatriene (meth) acrylate 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxy-3- Phenoxypropyl (meth) acrylate, glycidyl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, ethoxycarbonylmethyl (meth) acrylate, phenol ethylene oxide modified acrylate, Nord (ethylene oxide 2 mol modified) acrylate, phenol (ethylene oxide 4 mol modified) acrylate, paracumylphenol ethylene oxide modified acrylate, nonylphenol ethylene oxide modified acrylate, nonylphenol (ethylene oxide 4 mol modified) acrylate, nonylphenol (ethylene oxide 8 mol) Modified) acrylate, nonylphenol (propylene oxide 2.5 mol modified) acrylate, 2-ethylhexyl carbitol acrylate, ethylene oxide modified phthalic acid (meth) acrylate, ethylene oxide modified succinic acid (meth) acrylate, trifluoroethyl (meth) acrylate , Acrylic acid, methacrylic acid, maleic acid, fumaric acid, ω-carboxy-polycaprola Ton mono (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, (meth) acrylic acid dimer, β- (meth) acryloyloxyethyl hydrogen succinate, n- (meth) acryloyloxyalkyl hexahydrophthalimide, etc. Can be mentioned.

Furthermore, as a bifunctional (meth) acrylate monomer, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexadiol di (meth) acrylate, 1,9- Nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, 2-ethyl-2-butyl-propanediol (meth) acrylate, neopentyl glycol modified trimethylolpropane di (Meth) acrylate, stearic acid modified pentaerythritol diacrylate, polypropylene glycol di (meth) acrylate, 2,2-bis (4- (meth) acryloxydiethoxyphenyl) propane, 2,2-bis (4- ( (Meta) acryloxypro Xylphenyl) propane, 2,2-bis (4- (meth) acryloxytetraethoxyphenyl) propane, and the like. Examples of the trifunctional (meth) acrylate monomer include tomethylolpropane tri (meth) acrylate, tris [(meta ) Acryloylethyl] isocyanurate, etc., and the tetrafunctional or higher (meth) acrylate monomers include dimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate. , Dipentaerystol penta (meth) acrylate, dipentaerystol hexa (meth) acrylate, etc.

The (meth) acrylates other than (B) and (A) used in the present invention are more preferably hydrophobic as in the case of the component (A). When water-soluble, the curable composition for surface protection in cutting water during processing. The protective film made of swells is not preferable because it may be displaced or peeled off, and may be infiltrated with cutting water or damaged or contaminated with cutting waste, resulting in poor processing accuracy. Even if it is hydrophilic, it can be used as long as the protective film made of the curable composition for surface protection is not greatly swollen or partially dissolved by water.

The addition amount of (meth) acrylate other than (B) (A) used in the present invention is preferably 10 to 80 parts by mass in 100 parts by mass of the total amount of components (A) and (B). If it is less than 10 parts by mass, the initial adhesiveness may be lowered, and if it exceeds 80 parts by mass, the peelability may be lowered.

In addition, the composition of the components (A) and (B) includes (meth) acryloyloxyethyl acid phosphate, dibutyl 2- (meth) acryloyloxyethyl acid phosphate, dioctyl 2- (meth) acryloyloxyethyl phosphate. , Diphenyl 2- (meth) acryloyloxyethyl phosphate, (meth) acryloyloxyethyl polyethylene glycol acid phosphate, etc. The property can be further improved.

The (C) photopolymerization initiator used in the present invention is blended to accelerate photocuring of the curable composition for surface protection by sensitizing with actinic light of visible light or ultraviolet light, and is publicly known. These various photopolymerization initiators can be used. Specifically, benzophenone and derivatives thereof, benzyl and derivatives thereof, enthraquinone and derivatives thereof, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzoin derivatives such as benzyl dimethyl ketal, diethoxyacetophenone, Acetophenone derivatives such as 4-t-butyltrichloroacetophenone, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, diphenyl disulfide, thioxanthone and derivatives thereof, camphorquinone, 7,7-dimethyl-2,3-dioxobicyclo [2.2.1] Heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxobicyclo [2.2.1] heptane-1-carboxy-2 Bromoethyl ester, 7,7-dimethyl-2,3-dioxobicyclo [2.2.1] heptane-1-carboxy-2-methyl ester, 7,7-dimethyl-2,3-dioxobicyclo [2 2.1] Camphorquinone derivatives such as heptane-1-carboxylic acid chloride, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethyl Α-aminoalkylphenone derivatives such as amino-1- (4-morpholinophenyl) -butanone-1, benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoyldiethoxyphosphine oxide, 2, 4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, 2 Acylphosphine oxide derivatives such as 4,6-trimethylbenzoyl dichloride ethoxyphenyl phosphine oxide. A photoinitiator can be used 1 type or in combination of 2 or more types.

As for the addition amount of (C) photoinitiator used by this invention, 0.1-20 mass parts is preferable with respect to a total of 100 mass parts of (A) and (B). More preferably, 3-20 mass parts is preferable. If it is 0.1 part by mass or more, the effect of promoting curing can be obtained, and if it is 20 parts by mass or less, a sufficient curing rate can be obtained. More preferably, by adding 3 parts by mass or more of component (C), curing can be performed without depending on the amount of light irradiation, and the degree of cross-linking of the cured product of the curable composition for surface protection increases, resulting in misalignment during cutting. The point which does not raise | generate etc. and peelability improve.

Surface curability can be improved by using a resin containing a cyclopentadiene skeleton in combination with the curable composition for surface protection of the present invention. The resin containing a cyclopentadiene skeleton is a petroleum resin produced using cyclopentadiene extracted from a C5 fraction as a main raw material. Specific examples include “Quinton 1700”, “Quinton 1500”, and “Quinton 1325” manufactured by ZEON Corporation.

Furthermore, by using a polar organic solvent together with the surface protective curable composition of the present invention, it is possible to reliably develop a phenomenon in which the protective film comes into contact with warm water and easily swells to lower the adhesive strength.

The polar organic solvent preferably has a boiling point of 50 ° C. or higher and 130 ° C. or lower. When a polar organic solvent having a boiling point within the above range is selected, it is preferable because a phenomenon that the cured composition comes into contact with warm water and the adhesive strength decreases can be more reliably exhibited. Examples of such a polar organic solvent include alcohols, ketones, esters, and the like. Of these, alcohols are preferably selected according to the results of investigations by the inventors.

Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, 2-ethylbutyl alcohol and the like. Further, among the alcohols, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol having a boiling point of 120 ° C. or less are preferred, and among these, methanol, ethanol More preferred are isopropanol and n-butanol.

As for the addition amount of a polar organic solvent, 0.5-30 mass parts is preferable with respect to 100 mass parts of total amounts of (A) and (B). If it is 0.5 parts by mass or more, releasability can be ensured, and if it is 30 parts by mass or less, the initial adhesiveness is not lowered, and the cured product of the curable composition for surface protection is peeled into a film. .

The curable composition for surface protection of the present invention can use a small amount of a polymerization inhibitor for improving the storage stability. For example, polymerization inhibitors include methylhydroquinone, hydroquinone, 2,2-methylene-bis (4-methyl-6-tertiarybutylphenol), catechol, hydroquinone monomethyl ether, monotertiarybutylhydroquinone, 2,5-ditertiarybutyl. Hydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-ditertiarybutyl-p-benzoquinone, picric acid, citric acid, phenothiazine, tertiary butylcatechol, 2-butyl-4-hydroxyanisole and Examples include 2,6-ditertiary butyl-p-cresol.

The amount of these polymerization inhibitors used is preferably 0.001 to 3 parts by mass and more preferably 0.01 to 2 parts by mass with respect to 100 parts by mass of the total amount of (A) and (B). If it is 0.001 part by mass or more, sufficient storage stability can be obtained, and if it is 3 parts by mass or less, the adhesiveness is not easily lowered or uncured.

Examples of the inorganic filler (D) in the present invention include spherical alumina, crushed alumina, magnesium oxide, beryllium oxide, titanium oxide and other oxides, boron nitride, silicon nitride, aluminum nitride and other nitrides, silicon carbide, etc. Carbides, hydrated metals such as aluminum hydroxide and magnesium hydroxide, metal fillers such as copper, silver, iron, aluminum and nickel, metal alloy fillers such as titanium, carbon-based fillers such as diamond and carbon, There are silica, quartz glass, fused silica, spherical silica, fumed silica and the like, silica sand, forastonite, clay, talc, calcium carbonate, glass beads, shirasu balloon, etc., and these inorganic fillers are one kind or Two or more types can be used. Among these inorganic fillers, silica is particularly preferable in consideration of the photocurability of the surface-protecting curable composition, and more preferably dry method silica is more preferable in consideration of screen printability. is there.

Dry silica is crystalline silica powder, fused silica powder, spherical silica powder, fumed silica, or other silica powder, commonly known as white carbon. For example, silicon tetrachloride is heated at a high temperature around 1000 ° C. in the presence of hydrogen and oxygen. The silica is produced by pyrolysis of the silica, and the silica internal structure is stable, so that the silanol group is exposed on the particle surface. Further, in the present invention, surface treatment obtained by treating and hydrophobizing silanol groups present on the silica surface with organosilicon halides or alcohols for surface modification and dispersibility improvement in dry process silica. Silica that has been used may be used. Examples of such dry silica include “Aerosil 130”, “Aerosil 200”, “Aerosil 300”, “Aerosil 380”, “Aerosil R972” (all manufactured by Nippon Aerosil), “Cab-O-Sil”. (Manufactured by GL Cabot Corp.), “DC Fine Slica” (manufactured by Dow Corning), “Fransil 251” (manufactured by Farnsol), and the like. In this case, it is generally used for the purpose of increasing the structural viscosity of the liquid itself so that the liquid does not spill, and by adding these dry silicas, it can be easily adjusted to a viscosity that can be achieved by screen printing.

The curable composition for surface protection of the present invention is a range of elastomers such as acrylic rubber, urethane rubber, acrylonitrile-butadiene-styrene rubber, solvents, fillers, reinforcements, etc. that are generally used within a range that does not impair the object of the present invention. Additives such as materials, plasticizers, thickeners, dyes, pigments, flame retardants, silane coupling agents and surfactants may be used.

As a viscosity of the curable composition for surface protection of this invention, 5000 mPa * s or more is preferable. When it is 5000 mPa · s or more, there is no liquid dripping in the screen printing method, and a good protective film can be obtained. More preferably, if it is 10,000 mPa · s or more, a better protective film can be obtained in the screen printing method. The upper limit of the viscosity is appropriately selected according to the usage of the curable composition, but is preferably 20000 mPa · s or less in the case of screen printing, and 100000 mPa · s in the case of brush coating or the like. The following is preferable.

In the surface protection method of the present invention, a protective film made of the above-mentioned curable composition for surface protection is provided on the surface of the workpiece, and after processing the workpiece, the protective film is peeled off from the workpiece. This is a method for protecting a surface of a workpiece. This protects against the occurrence of scratches and contamination of the workpiece due to the ingress of cutting water and cutting debris that occur during processing of optical parts such as ceramics, glass and quartz, electronic and electrical parts such as sensors, and printed wiring boards It can function as a suitable protective film for masking at the time of coating and printing such as nameplates, logos and other nameplates, instrument scales, decorations, etc.

Furthermore, the surface protection method of the present invention is applicable to any coating method such as brush coating, various coating methods, screen printing method, dumbo printing method, spray method, potting method, dipping method, etc., when a protective film is provided on the surface of the workpiece. Among them, it is more preferable to use the screen printing method. The screen printing method is a kind of stencil printing that uses silk, nylon, tetron, etc., and stainless steel wire screens, and can print on relief plates, flat plates, intaglio plates, and curved surfaces. It's being used. By using the screen printing method, it becomes possible to apply the above-mentioned curable composition for surface protection without shifting even a fine portion, which is preferable in terms of workability.

In the present invention, when the protective film is peeled off from the workpiece, it is possible to achieve peelability in a short time by using moderately heated hot water of 90 ° C. or less, which is preferable from the viewpoint of productivity. Regarding the temperature of the warm water, when using warm water of 30 ° C. to 80 ° C., preferably 40 to 80 ° C., the protective film made of the curable composition is slightly swollen or softened in a short time. The workpiece can be easily separated. The method for contacting the protective film with the warm water is not particularly limited, and the workpiece or the protective film portion provided with the protective film may be immersed in the warm water.

In the present invention, the material of the workpiece is not particularly limited. Examples of such materials include metal members such as aluminum, iron, SUS, and nickel, glass members, ceramic members such as alumina and aluminum nitride, plastic members, and wafers such as silicon and sapphire. The method of protecting the surface of the workpiece of the present invention includes processing of glass lenses, plastic lenses, optical parts such as glass and quartz, optical disks, metal plates, molds, aluminum sashes, plastic plates, semiconductor wafers, circuit boards, It can be applied to the processing of electronic and electrical parts such as ceramics and sensors. In particular, protection of already processed surfaces of optical glass such as lenses and prisms that must be protected from scratches and contamination of cutting water, cutting chips, etc., protection of workpieces such as sensor parts and circuit boards with uneven surfaces Prevention of contamination by plating solution used on circuit boards such as printed wiring boards, nameplates applied to various industrial products, not just electronic and electrical parts, various nameplates such as logos, instrument scales, decorations, painting, printing, etc. Useful for masking time.

Example 1
(A) “UC-203” (methacryloyl-modified polyisoprene, manufactured by Kuraray Co., Ltd.) as a (meth) acrylate having one or more (meth) acryloyl groups at the terminal or side chain of the molecule and having a molecular weight of 500 or more. (Abbreviated as “UC-203”) 80 parts by mass, (B) (C) other than (A) dicyclopentenyloxyethyl methacrylate (Rohm & Haas “QM-657”, hereinafter abbreviated as “QM”) .) 20 parts by mass, (C) 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (“IRGACURE907” manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator, (Hereinafter abbreviated as “I-907”) (D) “Aerosil R972” (produced by Nippon Aerosil Co., Ltd.) 2 which is a dry process silica as an inorganic filler. Then, 0.1 part by mass of 2,2-methylene-bis (4-methyl-6-tertiarybutylphenol) (hereinafter abbreviated as “MDP”) was added as a polymerization inhibitor to prepare a curable composition for surface protection. . Using the obtained surface protective curable composition, the tensile shear bond strength was measured and the peel test was performed by the following evaluation methods. The results are shown in Table 1.

(Evaluation methods)
Viscosity : Using a B-type viscometer, the viscosity of the prepared curable composition for surface protection was measured under the condition of a temperature of 23 ° C.
Surface curability : A surface-protective curable composition prepared on heat-resistant Pyrex (registered trademark) glass was applied to a coating thickness of about 70 μm by a screen printing method, and 365 nm by a curing device manufactured by Eye Graphics using a metal halide lamp. Curing was performed under the condition of an integrated light quantity of 2000 mJ / cm ² at the wavelength of. Immediately thereafter, the surface curability was evaluated by touch with the following criteria.
○: Good without tack △: Slightly tacky ×: Sticky and contaminated fingertip
Peelability (1) : In the same manner as described above, a surface-protective curable composition was applied onto heat-resistant Pyrex (registered trademark) glass, and an integrated amount of light having a wavelength of 365 nm was applied by a curing device manufactured by Igraphics Corporation using a metal halide lamp. A peel test body was formed by curing under the condition of 2000 mJ / cm ² to form a protective film. The obtained specimen was immersed in warm water (80 ° C.), and the time for the protective film to peel from the heat-resistant Pyrex (registered trademark) glass was measured.
Peelability (2) : Except that polycarbonate was used as the adherend, a peel test specimen having a protective film formed in the same manner as the peelability (1) was prepared. Similarly, the time required for the protective film to peel from the polycarbonate was measured for the obtained specimen.

(Examples 2 to 19)
A curable composition for surface protection was prepared in the same manner as in Example 1 except that the raw materials of the types shown in Tables 1 and 2 were used in the compositions shown in Tables 1 and 2. About the obtained curable composition, the measurement of the tensile shear bond strength and the peeling test were performed similarly to Example 1. The results are shown in Tables 1 and 2.

(Materials used)
(A) (Meth) acrylate TE-2000: 1,2-polybutadiene terminated urethane methacrylate (manufactured by Nippon Soda Co., Ltd. ) having one or more (meth) acryloyl groups at the terminal or side chain of the molecule and having a molecular weight of 500 or more . "TE-2000", molecular weight 2000)
UV7000B: urethane acrylate (manufactured by Nippon Synthetic Chemical Co., Ltd. "purple light UV-7000B", molecular weight 3500)
UV3000B: Polyester urethane acrylate ("Nippon Gosei Kagaku""purple light UV-3000B", molecular weight 18000)
(B) (Meth) acrylates other than (A) M-101A: Phenolethylene oxide 2 mol modified acrylate (“Aronix M-101A” manufactured by Toagosei Co., Ltd.)
M-140: 2- (1,2-cyclohexacarboximide) ethyl acrylate (“Aronix M-140” manufactured by Toagosei Co., Ltd.)
IBXA: Isobornyl acrylate (“Light acrylate IB-XA” manufactured by Kyoeisha Chemical Co., Ltd.)
R-684: dicyclotentanyl diacrylate (“KAYARAD R-684” manufactured by Nippon Kayaku Co., Ltd.)
Other ingredients ACMO: Acroyl morpholine ("ACMO" manufactured by Kojin Co., Ltd.)
Quinton 1700: cyclopentadiene resin ("Quinton 1700" manufactured by Nippon Zeon)
IPA: isopropyl alcohol

(Comparative Examples 1-5)
A curable composition was prepared in the same manner as in Example 1 except that the raw materials of the type shown in Table 3 were used in the composition shown in Table 3. The viscosity of the obtained curable composition was measured in the same manner as in Example 1. Although the test piece for surface curability and a peeling test was produced by the screen printing method like Example 1, all of Comparative Examples 1-5 had low viscosity, and screen printing was not able to be performed. Therefore, a curable composition was applied onto heat-resistant Pyrex (registered trademark) glass or polycarbonate as an adherend by brush coating, and surface curability and a peel test were performed. The results are shown in Table 3.

(Materials used)
(B) (Meth) acrylate BZ other than (A) : benzyl methacrylate (“Eye ester BZ” manufactured by Kyoeisha Chemical Co., Ltd.)
IBX: isobornyl methacrylate (“Light Ester IB-X” manufactured by Kyoeisha Chemical Co., Ltd.)
2-HEMA: 2-hydroxyethyl methacrylate MTEGMA: methoxytetraethylene glycol monomethacrylate (“NK ester M-90G” manufactured by Shin-Nakamura Chemical Co., Ltd.)

As a result, all of the curable compositions for surface protection of Examples 1 to 19 can be screen-printed to ensure surface curability, and the obtained protective films were all film-like and easily peeled off. . The protective film consisting of the curable composition of Comparative Examples 1 and 5 did not peel off from the adherend of either glass or polycarbonate. Moreover, the protective film which consists of a curable composition of the comparative examples 2 and 4 melt | dissolved simultaneously with contact with warm water. Moreover, the protective film which consists of a curable composition of the comparative example 3 partially remained after the peeling test (glue paste).

The present invention protects the processed surfaces of optical glass such as lenses and prisms, protects workpieces such as sensor parts and circuit boards with uneven surfaces, and prevents contamination by plating solutions used on circuit boards such as printed wiring boards. It is useful for masking during coating and printing, such as nameplates, logos, and other nameplates applied to various industrial products, as well as protective coatings, electronic and electrical parts.

Claims (8)

After providing a protective film formed by curing the surface-protecting curable composition containing the following (A), (B), (C) and (E) on the surface of the workpiece, and processing the workpiece, A method for protecting a surface of a workpiece, wherein the protective film is immersed in warm water of 30 ° C. or higher and 90 ° C. or lower and peeled off from the workpiece.
(A) polyisoprene having one or more (meth) acryloyl groups at the terminal or side chain of the molecule and having a molecular weight of 500 or more,
(B) (meth) acrylates other than (A),
(C) Photopolymerization initiator (E) Polymerization inhibitor In the curable composition for surface protection, 20 to 90 parts by mass of (A) in 100 parts by mass of the total amount of the components (A) and (B), and 100 parts by mass of the total amount of the components (A) and (B) ( The work piece according to claim 1 , wherein 0.1 to 20 parts by mass of (C) is contained with respect to 10 parts by mass of 80) and 100 parts by mass of (A) and (B) in total. A method for protecting the surface of a member. The curable composition for surface protection contains (D) an inorganic filler, The surface protection method of the to-be-processed member of any one of Claim 1 thru | or 2 characterized by the above-mentioned. (D) The method for protecting a surface of a workpiece according to claim 3 , wherein the inorganic filler is silica. The method for protecting a surface of a workpiece according to any one of claims 1 to 4 , wherein the viscosity of the curable composition for surface protection is 5000 mPa · s or more. The method for protecting a surface of a workpiece according to any one of claims 1 to 5 , wherein the curable composition for surface protection contains a resin containing a cyclopentadiene skeleton. The method for protecting a surface of a workpiece according to any one of claims 1 to 6 , wherein the curable composition for surface protection contains a polar organic solvent. The method for protecting a surface of a workpiece according to any one of claims 1 to 7 , wherein a protective film is provided on the surface of the workpiece, by screen printing.