JP5415115B2 - Adhesive composition for temporary surface protection, adhesive obtained thereby, adhesive sheet, and method of using the adhesive sheet - Google Patents

Description

  The present invention is suitable for protecting plastic products and metal products used for metal plates, glass plates, synthetic resin plates, laminated steel plates, etc. for labels and sheets, tapes, building materials, packaging materials, and electronics. The present invention relates to a pressure-sensitive adhesive composition for temporary surface protection excellent in moderate pressure-sensitive adhesive strength and peelability, a pressure-sensitive adhesive obtained thereby, a pressure-sensitive adhesive sheet, and a method of using the pressure-sensitive adhesive sheet.

  The adhesive sheet for temporary surface protection is a sheet premised on peeling, and in particular, a metal plate such as a stainless steel plate, an aluminum plate or a color steel plate, an optical member such as a glass plate or a polarizing film, or a resin plate such as a plastic plate. It is used for the purpose of preventing the surface of the adherend from being contaminated or scratched during transportation, storage, processing or the like.

  In general, acrylic pressure-sensitive adhesives are often used as temporary surface protecting pressure-sensitive adhesives for protecting plastic plates and metal products from the viewpoint of weather resistance and transparency. As an acrylic pressure-sensitive adhesive, a pressure-sensitive adhesive composition obtained by copolymerizing a (meth) acrylic acid alkyl ester monomer and a monomer containing a functional group such as a carboxyl group, a hydroxyl group, or an epoxy group is used as a polyisocyanate compound. , A melamine resin, an epoxy resin, and a cross-linked material using a cross-linking agent such as a metal chelate compound are used. In these acrylic pressure-sensitive adhesives, it is common to increase the cohesive force by using a large amount of a cross-linking agent in order to improve the peelability after adhesion and to eliminate contamination on the adherend surface after peeling. .

  However, in the case of an acrylic pressure-sensitive adhesive, when the degree of cross-linking is simply increased to lower the pressure-sensitive adhesive force, an increase in the pressure-sensitive adhesive force with time after attaching becomes a problem. In order to suppress this increase in adhesive strength over time, there is a means to lower the degree of crosslinking and improve the wettability at the initial stage of application, but if the degree of crosslinking is lowered, the adhesive strength increases and the peelability decreases. There was a defect in physical properties.

  Various studies have been made to improve these problems. For example, in a method of producing a pressure-sensitive adhesive composition by solution polymerization, a monomer mixture having a copolymerizable functional group-containing monomer content of up to 40% by weight is polymerized to a polymerization rate of 20% by weight or more, A production method in which a polymerizable functional group monomer is polymerized by dividing it into two or more times has been proposed (see Patent Document 1). On the other hand, for the purpose of modifying the polymer itself, not the production method, an acrylic monomer, N, N-disubstituted (meth) acrylamide, a carboxyl group-containing monomer or anhydride thereof, and these An acrylic pressure-sensitive adhesive having a specific gel fraction and a copolymer obtained by copolymerizing a copolymerizable monomer at a specific blending ratio as a main component has also been proposed (see Patent Document 2). .

  However, the techniques disclosed in the above patent documents are still not satisfactory in terms of suppression of the increase in adhesive force with time and peelability (contamination resistance to the adherend), and further improvements are desired.

  In addition, since the acrylic pressure-sensitive adhesive uses a so-called general cross-linking agent, in order to promote the cross-linking reaction such as heating (drying / aging) or leaving it in order to obtain the necessary pressure-sensitive adhesive properties after coating. A certain period of curing is required. When such curing is performed for a long time, workability and productivity are hindered, and problems such as an increase in inventory amount and a delay in delivery date occur at the manufacturing site. Shortening of the curing period is also being investigated by adding a catalyst, but it is still not sufficient, and since the added catalyst affects the stain resistance of the adherend, an acrylic adhesive is used for temporary surface protection. It is not appropriate if you do. Therefore, shortening the curing period remains an important solution.

  On the other hand, a pressure-sensitive adhesive made of an active energy ray-curable pressure-sensitive adhesive composition is also disclosed as an acrylic pressure-sensitive adhesive (see Patent Document 3). According to this pressure-sensitive adhesive composition, the curing period can be shortened by a curing reaction by irradiation with active energy rays. However, this adhesive is used for strong adhesion and does not have an appropriate adhesive force (slight adhesion) for temporary surface protection, and cannot be used as a temporary surface protection adhesive. .

JP-A-5-132657 Japanese Patent Laid-Open No. 8-143843 JP 2007-217674 A

  The present invention has been made in view of such circumstances, can significantly reduce the curing period, after irradiation with active energy rays, has an appropriate adhesive force, and less adhesive change over time, An object of the present invention is to provide an active energy ray-curable pressure-sensitive adhesive composition for protecting a temporary surface without contamination of an adherend after peeling, a pressure-sensitive adhesive obtained thereby, a pressure-sensitive adhesive sheet, and a method of using the pressure-sensitive adhesive sheet. .

In order to achieve the above object, the present invention provides an acrylic resin (A), an ethylenically unsaturated compound (B) having one ethylenically unsaturated group, and an ethylenically unsaturated group having two or more ethylenically unsaturated groups. An active energy ray-curable adhesive composition for temporary surface protection containing a saturated compound (C) and a photopolymerization initiator (D), wherein the acrylic resin (A) has a weight average molecular weight of 850,000 or more. A temporary resin for protecting a temporary surface, wherein the content of (C) is 6 parts by weight or more with respect to a total of 100 parts by weight of (A) and (B). The composition is the first gist.

  Moreover, let the 2nd summary the adhesive for temporary surface protection obtained by irradiating an active energy ray to the said adhesive composition for temporary surface protection.

  Furthermore, let the 3rd summary the adhesive sheet for temporary surface protection which has a layer which consists of a base material and the said adhesive agent for temporary surface protection.

  A fourth aspect of the present invention is a method for using the temporary surface protecting pressure-sensitive adhesive sheet, in which the temporary surface protecting pressure-sensitive adhesive sheet is attached to the surface of the adherend, the surface of the adherend is protected, and then the pressure-sensitive adhesive sheet is peeled off.

  Until now, the present inventors have repeated a series of studies on the pressure-sensitive adhesive composition, and have also studied the pressure-sensitive adhesive composition as shown in Patent Document 3 above. However, since the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition shown in Patent Document 3 exhibits good pressure-sensitive adhesiveness (strong pressure-sensitive adhesiveness), the technique is diverted to temporary surface protection applications based on peeling. It was difficult to do. In such a situation, the present inventors have shortened the curing period, have a suitable adhesive force, have little change in the adhesive force over time, and do not contaminate the adherend after peeling. In order to obtain a pressure-sensitive adhesive composition, various studies were conducted on various component materials and blending amounts constituting the pressure-sensitive adhesive. And further research was carried out based on the idea of shortening the curing period by not using a general crosslinking agent. As a result, although examination was performed also from a viewpoint different from the adhesive composition showing strong adhesiveness, the constituent components of the adhesive composition shown in Patent Document 3 correspond to (C) according to the present invention. It has been found that the above object can be achieved for the first time by setting the content of the component to a total of 100 parts by weight of the components corresponding to (A) and (B) according to the present invention more than before. The invention has been reached.

  Here, in the present invention, “for temporary surface protection” is not necessarily limited to one time, but includes repeatedly applying and peeling a plurality of times.

As described above, the pressure-sensitive adhesive composition for temporary surface protection of the present invention comprises a specific acrylic resin (A), an ethylenically unsaturated compound (B) having one ethylenically unsaturated group, and an ethylenically unsaturated group. An active energy ray-curable pressure-sensitive adhesive composition for temporary surface protection containing an ethylenically unsaturated compound (C) having two or more and a photopolymerization initiator (D), the content of (C) above However, it is 6 parts by weight or more with respect to the total of 100 parts by weight of the above (A) and (B). Therefore, the pressure-sensitive adhesive composition for temporary surface protection according to the present invention does not have a so-called general cross-linking agent, so that the curing period can be greatly shortened, and an appropriate adhesive strength can be obtained after irradiation with active energy rays. And the adhesive strength is less changed with time, and the adherend after peeling is not contaminated.

In addition, when the weight average molecular weight of the specific acrylic resin (A) is 850,000 or more, the resulting adhesive is more excellent in peelability after adhesion.

  Furthermore, when the ionic compound (E) is used, antistatic performance can be imparted in addition to the above effects.

Furthermore, when the glass transition temperature (Tg) of the specific acrylic resin (A) is within a range of −70 to 20 ° C., the adhesiveness of the obtained adhesive is further increased, and an appropriate adhesive strength is obtained. It will come out even more.

  When the pressure-sensitive adhesive composition for temporary surface protection does not contain a solvent, not only the drying process can be shortened in the production of the pressure-sensitive adhesive but also the global environment is taken into consideration.

  Further, the temporary surface protecting adhesive of the present invention is obtained by irradiating the temporary surface protecting adhesive composition with active energy rays, and has an appropriate adhesive force, and has an adhesive strength. There is little change over time, and there is no contamination of the adherend after peeling, and it becomes highly practical as an adhesive for temporary surface protection.

  Furthermore, when the gel fraction of the temporary surface protecting adhesive is 80 to 100%, the peelability after adhesion is further improved.

  And the adhesive sheet which has the layer which consists of a base material and the said adhesive has moderate adhesive force similarly to the said adhesive, and there is little change with time of an adhesive force, and it adheres to the adherend after peeling. Therefore, it becomes highly practical as an adhesive sheet for temporary surface protection.

  Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

The pressure-sensitive adhesive composition for temporary surface protection of the present invention comprises a specific acrylic resin (A) (hereinafter sometimes simply referred to as “acrylic resin”) , an ethylenically unsaturated group having one ethylenically unsaturated group . It consists of an active energy ray-curable resin composition containing a compound (B), an ethylenically unsaturated compound (C) having two or more ethylenically unsaturated groups, and a photopolymerization initiator (D). First, each component material which comprises this active energy ray curable resin composition is demonstrated.

<< Acrylic resin (A) >>
The acrylic resin (A) used in the present invention is a polymer obtained by copolymerizing a (meth) acrylic acid ester monomer (a1) and, if necessary, another copolymerizable monomer (a2). .

  In the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

  Examples of the (meth) acrylic acid ester monomer (a1) include, for example, aliphatic (meth) acrylic acid ester monomers such as (meth) acrylic acid alkyl esters, and aromatic (meth) acrylic acid phenyl esters ( And (meth) acrylic acid ester monomers.

  About the said (meth) acrylic-acid alkylester, it is preferable that carbon number of an alkyl group is 1-12 normally, especially 1-8, Furthermore, it is preferable that it is 2-8, Specifically, methyl (meth) acrylate , Ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, etc. can give. Examples of (meth) acrylic acid phenyl ester include benzyl (meth) acrylate and phenoxyethyl (meth) acrylate.

  Other (meth) acrylic acid ester monomers include tetrahydrofurfuryl (meth) acrylate and the like. These can be used alone or in combination of two or more.

  Among the above (meth) acrylic acid ester monomers (a1), n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable in terms of copolymerizability, adhesive properties, ease of handling, and availability of raw materials. N-butyl (meth) acrylate is preferably used from the viewpoint of excellent antistatic performance.

  Examples of the other copolymerizable monomer (a2) include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an oxyalkylene group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, a nitrogen-containing monomer, a glycidyl group-containing monomer, and a phosphate group. -Containing monomers, functional group-containing monomers such as sulfonic acid group-containing monomers, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene , Vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium Chloride, allyl trimethyl ammonium chloride, are exemplified monomers such as dimethylallyl vinyl ketone, one selected from these or two or more may be used. Preferably, acrylonitrile or a hydroxyl group-containing monomer, particularly 2-hydroxyethyl methacrylate is used.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl (meth) acrylate and other (meth) acrylic acid hydroxyalkyl esters, caprolactone-modified 2-hydroxyethyl (meth) acrylate, etc. Monomers containing primary hydroxyl groups such as caprolactone-modified monomers, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 2-hydroxy-3 -Secondary hydroxyl group-containing monomers such as phenoxypropyl (meth) acrylate; tertiary hydroxyl group-containing monomers such as 2,2-dimethyl-2-hydroxyethyl (meth) acrylate.

  Also, polyethylene glycol derivatives such as diethylene glycol (meth) acrylate and polyethylene glycol mono (meth) acrylate, polypropylene glycol derivatives such as polypropylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol-mono (meth) acrylate, poly (ethylene glycol) An oxyalkylene-modified hydroxyl group-containing monomer such as -tetramethylene glycol) mono (meth) acrylate or poly (propylene glycol-tetramethylene glycol) mono (meth) acrylate may be used.

  Examples of the carboxyl group-containing monomer include Michael addition of acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide N-glycolic acid, cinnamic acid, and (meth) acrylic acid. (Eg, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2- (meth) acryloyloxyethyl dicarboxylic acid monoester (eg, 2-acryloyloxyethyl) Succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahi Rofutaru acid monoester, 2-methacryloyloxyethyl hexahydrophthalic acid mono ester) and the like. Such a carboxyl group-containing monomer may be used as an acid, or may be used in the form of a salt neutralized with an alkali.

  When the carboxyl group-containing monomer is used, after copolymerization and polymerization, the carboxyl group derived from the carboxyl group-containing monomer is neutralized with a neutralizing agent to obtain a partially neutralized product or a completely neutralized product. It is preferable to do.

Examples of the neutralizing agent include ammonia, alkaline ammonium salts and primary amines such as monoethylamine and monoethanolamine; secondary amines such as diethylamine and diethanolamine; triethylamine, triethanolamine, N, N, N′-trimethylethylenediamine Tertiary amines such as N-methyldiethanolamine and N, N-diethylhydroxylamine; amino compounds having a plurality of nitrogen atoms in one molecule such as diamine and polyethyleneimine; amine compounds such as cyclic amino compounds such as pyridine; Examples thereof include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide.
Among these neutralizing agents, alkali metal hydroxides are preferable from the viewpoint of antistatic ability after neutralization, and potassium hydroxide is particularly preferably used because of compatibility with acrylic resins.

  Examples of the oxyalkylene group-containing monomer include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, and 2-butoxy. Diethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol -Polypropylene glycol mono (meth) acrylate, Lauroxy polyethylene glycol mono (meth) acrylate, Aliphatic (meth) acrylic acid esters such as loxypolyethyleneglycol mono (meth) acrylate, 2-phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, phenoxypolyethyleneglycol-polypropyleneglycol- (meth) acrylate And acrylic acid esters of aromatic (meth) acrylates such as nonylphenol ethylene oxide adduct (meth) acrylate.

  Examples of the amide group-containing monomer include acrylamide, methacrylamide, N- (n-butoxyalkyl) acrylamide, N- (n-butoxyalkyl) methacrylamide, N, N-dimethyl (meth) acrylamide, N, N- Examples include diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, acrylamide-3-methylbutylmethylamine, dimethylaminoalkylacrylamide, dimethylaminoalkylmethacrylamide and the like.

  Examples of the amino group-containing monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and a quaternized product thereof.

  Examples of the nitrogen-containing monomer include acryloylmorpholine.

  Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate and allyl glycidyl ether.

  Examples of the phosphoric acid group-containing monomer include 2- (meth) acryloyloxyethyl acid phosphate, bis (2- (meth) acryloyloxyethyl) acid phosphate, and the like.

  Examples of the sulfonic acid group-containing monomer include olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid, and salts thereof. .

  Thus, the acrylic resin (A) according to the present invention is obtained by copolymerizing the above (meth) acrylic acid ester monomer (a1) and, if necessary, other copolymerizable monomer (a2). can get. As a specific copolymer component ratio constituting the acrylic resin (A), the (meth) acrylic acid ester monomer (a1) is 75 to 100% by weight, particularly 80 to 93%, based on the entire copolymer component. It is preferable that it is weight%, Furthermore, it is 85-90 weight%. When the amount of the (meth) acrylic acid ester monomer (a1) is too small, the molecular weight does not increase and the viscosity tends to be low.

The weight average molecular weight of the obtained the acrylic resin (A) (Mw) is in 8 50,000 or more, more preferably 1,000,000 or more, particularly preferably 1.2 million or more. This is because if the weight average molecular weight of the acrylic resin (A) is too small, the cohesive force of the adhesive obtained by irradiation with active energy rays tends to be insufficient.

  On the other hand, the upper limit of the weight average molecular weight (Mw) of the acrylic resin (A) is preferably 3 million or less, particularly 2.5 million or less, and more preferably 2 million or less. This is because if the weight average molecular weight of the acrylic resin (A) is too large, a uniformly compatible pressure-sensitive adhesive composition tends to be difficult to obtain.

  In the present invention, the degree of dispersion (Mw / Mn) of the acrylic resin (A) is preferably 7 or less, particularly 5 or less, and further preferably 4 or less. This is because if the degree of dispersion (Mw / Mn) of the acrylic resin (A) is too large, there is a tendency that the shake due to the active energy ray irradiation conditions of cohesive force and adhesive properties increases. The lower limit of the degree of dispersion (Mw / Mn) is usually 2. In addition, said Mn means a number average molecular weight.

The above acrylic resin (A), Ru is produced by suspension Nigoomo legal. The above suspension polymerization can be obtained a large polymer degree of polymerization, and because also the isolation of the produced polymer is easy, which need use as a method for producing a satisfying acrylic resin (A). Then, the acrylic resin (A), the Ru dry resin der obtained by suspension polymerization.

  In the polymerization, a dispersion stabilizer such as polyvinyl alcohol and a polymerization initiator such as azobisisobutyronitrile can be added as necessary.

  In general, the acrylic resin used in the pressure-sensitive adhesive composition is often produced by solvent-based polymerization using an organic solvent at the time of production. When such a solvent-based polymerized acrylic resin is used in the pressure-sensitive adhesive composition, it is necessary to dry the pressure-sensitive adhesive solution at a high temperature, so a lot of energy is required, and the organic solvent is easily flammable. In addition to causing air pollution, large-scale solvent recovery devices and safety devices are required. However, when the acrylic resin (A) of dry resin obtained by the suspension polymerization is used, the pressure-sensitive adhesive composition can be produced without containing such an organic solvent.

  In the present invention, the glass transition temperature (Tg) of the acrylic resin (A) is preferably in the range of −70 to 20 ° C., particularly −60 to 0 ° C., more preferably −55 to −10. It is preferably within the range of ° C. This is because if the glass transition temperature (Tg) of the acrylic resin (A) is too low, the tendency to be inferior in cohesive force is seen, and conversely, if it is too high, the pressure-sensitive adhesive tends to become brittle.

In the present invention, the weight average molecular weight means a weight average molecular weight in terms of standard polystyrene molecular weight. Specifically, high-performance liquid chromatography (manufactured by Waters, Japan, “Waters 2695 (main body)” and “Waters 2414 (detection)). Column): Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / piece, filler material: styrene-divinyl It is measured by using three series of benzene copolymer and filler particle size: 10 μm. Similarly, the number average molecular weight is measured using the above measuring apparatus.

  In the present invention, the glass transition temperature is calculated from the Fox equation.

<< Ethylenically unsaturated compound (B) having one ethylenically unsaturated group >>
The ethylenically unsaturated compound (B) having one ethylenically unsaturated group used in the present invention (hereinafter sometimes abbreviated as “monofunctional ethylenically unsaturated compound (B)”), together with the above (A), It is used as a monomer constituting the temporary surface protecting resin composition. The monofunctional ethylenically unsaturated compound (B) is liquid at room temperature (25 ° C. ± 10 ° C.) consisting of (meth) acrylic acid alkyl ester (b1) and, if necessary, other copolymerizable monomer (b2). It is a solid monomer.

  Examples of the (meth) acrylic acid alkyl ester (b1) include (meth) acrylic acid alkyl esters usually having 1 to 30 carbon atoms in the alkyl group, and specifically include ethyl (meth) acrylate, n-propyl ( (Meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, 2-ethylhexyl (meth) Examples thereof include acrylate, nonyl (meth) acrylate, n-decyl (meth) acrylate, and iso-decyl (meth) acrylate. Among them, (meth) acrylic acid alkyl esters having preferably 2 to 20 carbon atoms, particularly preferably 4 to 18 carbon atoms, and more preferably 4 to 10 carbon atoms are preferable. Among these, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-butyl (meth) acrylate are particularly preferably used. One or more of these (meth) acrylic acid alkyl esters (b1) are used.

  Other copolymerizable monomers (b2) include, for example, (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide-N-glycolic acid, cinnamic acid, (meth) Michael adduct of acrylic acid (eg, acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, methacrylic acid tetramer, etc.), 2- (meth) acryloyloxyethyl dicarboxylic acid monoester (eg, 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahi Carboxyl group-containing unsaturated monomers such as lophthalic acid monoester, 2-methacryloyloxyethyl hexahydrophthalic acid monoester); 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl ( (Meth) acrylates such as (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate Caprolactone-modified monomers such as hydroxyalkyl acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol Primary hydroxyl group-containing monomers such as meth) acrylamide and N-hydroxyethyl (meth) acrylamide; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate Secondary hydroxyl group-containing monomers such as 2-chloro-2-hydroxypropyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate; 2,2-dimethyl-2-hydroxyethyl (meth) acrylate and the like Tertiary hydroxyl group-containing monomers; glycidyl group-containing unsaturated monomers such as glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate; t-butylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylacrylate Amino group-containing monomers such as minoethyl (meth) acrylate; 2- (acetoacetoxy) ethyl (meth) acrylate, acetoacetyl group-containing monomers such as allyl acetoacetate; 2-methoxyethyl (meth) acrylate, 3-methoxyethyl (meta ) Alkoxy (poly) alkylene glycol mono (meth) acrylates such as acrylate and methoxydiethylene glycol (meth) acrylate; Allyl compounds such as N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinylketone; N-vinyl Vinyl-based monomers such as pyrrolidone, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, vinyl acetate, styrene; (meth) acrylates other than (b1) Acid alkyl ester monomer, etc. can be mentioned, one selected from these or two or more may be used. Among these, (meth) acrylic acid is preferably used.

  Thus, the monofunctional ethylenically unsaturated compound (B) according to the present invention comprises the above (meth) acrylic acid alkyl ester (b1) and, if necessary, further another copolymerizable monomer (b2). . As a specific blending ratio, the blending amount of the (meth) acrylic acid alkyl ester (b1) is 75 to 100% by weight, particularly 80 to 93% by weight, based on the whole monofunctional ethylenically unsaturated compound (B). Further, it is preferably 85 to 90% by weight. When the amount of the (meth) acrylic acid alkyl ester (b1) is too small, the molecular weight does not increase and the viscosity tends to be low.

  In particular, in applications where moderate tackiness is required, other copolymerizability is included in 100 parts by weight (hereinafter abbreviated as “part”) of the acrylic resin (A) and the monofunctional ethylenically unsaturated compound (B). It is preferable that the monomer (b2) contains 1 to 20 parts, particularly 3 to 10 parts. The other copolymerizable monomer (b2) is preferably a carboxyl group-containing unsaturated monomer, particularly preferably acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide- N-glycolic acid and cinnamic acid are preferable, and acrylic acid and methacrylic acid are more preferable.

  Furthermore, in the above-mentioned monofunctional ethylenically unsaturated compound (B), in applications where antistatic performance is required for the pressure-sensitive adhesive, an oxyalkylene chain-containing monomer (b3) is used or a large amount of hydroxyl-containing monomer (b4) is used. By using the antistatic performance, it is possible to impart antistatic performance.

  As said oxyalkylene chain containing monomer (b3), the monofunctional monomer containing the oxyalkylene chain represented by following General formula (1) is mention | raise | lifted, for example.

  X in the general formula (1) is an alkylene group, and an alkylene group having 1 to 10 carbon atoms, particularly 2 to 8 carbon atoms is preferable, and an ethylene group, a propylene group, or a tetramethylene group is particularly preferable. In the case where n is a polyoxyalkylene chain moiety having 2 or more, a homopolymer of the same oxyalkylene chain may be used, or different oxyalkylene chains may be copolymerized randomly or in a block form.

  N in the general formula (1) is an integer of 1 or more, preferably 1 to 100, particularly preferably 5 to 50. If the value of n is too small, the antistatic ability tends to be insufficient, and if it is too large, the durability tends to be insufficient.

  A in the general formula (1) is a (meth) acryloyl group or an alkenyl group. As the alkenyl group, those having 2 to 6 carbon atoms, for example, a vinyl group or an allyl group are usually used. Among these, a methacryloyl group, an acryloyl group, and an allyl group are preferable, and a methacryloyl group and an acryloyl group are particularly preferable.

  B in the general formula (1) is a hydrogen atom, an alkyl group, a phenyl group, or an acyl group. As the alkyl group, those having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms are usually used. Among these, a hydrogen atom, a methyl group, and an ethyl group are preferable.

As specific examples of the monofunctional monomer containing the oxyalkylene chain,
[A: In the case of (meth) acryloyl group]
For example, polyethylene glycol derivatives such as polyethylene glycol mono (meth) acrylate, polypropylene glycol derivatives such as polypropylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol-mono (meth) acrylate, poly (ethylene glycol-tetramethylene glycol) mono Examples include (meth) acrylate, poly (propylene glycol-tetramethylene glycol) mono (meth) acrylate, alkoxy polyethylene glycol (meth) acrylate such as methoxypolyethylene glycol mono (meth) acrylate and ethoxypolyethylene glycol mono (meth) acrylate. .

[A: In the case of an alkenyl group]
Examples thereof include polyethylene glycol derivatives such as polyethylene glycol monoallyl ether, polypropylene glycol derivatives such as polypropylene glycol monoallyl ether, and polyethylene glycol-polypropylene glycol-monoallyl ether.
These may be used alone or in combination of two or more.

  Among these, the polyethylene glycol derivative is preferably an alkoxylated product of polyethylene glycol, more preferably methoxypolyethylene glycol monoacrylate, and the ethylene oxide addition mole number n is 5 to 500, particularly 5 to 100, more preferably 6 to 30 is preferable in terms of the balance between antistatic ability and durability. If the ethylene oxide addition mole number n is too small, the antistatic ability tends to be inferior, and if it is too large, the durability tends to deteriorate. Furthermore, A is preferably a (meth) acryloyl group from the viewpoint of excellent curability.

  Moreover, as a weight average molecular weight of the monofunctional monomer containing the oxyalkylene chain shown by the said General formula (1), 100-20000 are preferable normally, Especially 200-10000, Furthermore, 400-2000 are preferable. When the weight average molecular weight is too small, the antistatic ability tends to be inferior. When the weight average molecular weight is too large, the crystallinity becomes high and the handling tends to be difficult. The weight average molecular weight is measured in the same manner as described above.

  The content of the oxyalkylene chain-containing monomer (b3) is such that the oxyalkylene chain-containing monomer (b3) is 100 parts in total for the acrylic tree (A) and the monofunctional ethylenically unsaturated compound (B). In general, it may be 5 to 40 parts, preferably 10 to 35 parts, particularly preferably 15 to 30 parts. If the content is too large, the compatibility tends to decrease, and if it is too small, the antistatic performance tends to be inferior. There is.

  As the hydroxyl group-containing monomer (b4), the same hydroxyl group-containing monomers as exemplified in the other copolymerizable monomer (b2) can be used, and the content of the hydroxyl group-containing monomer (b4) is as follows. The hydroxyl group-containing monomer (b4) is usually 5 to 50 parts, preferably 10 to 40 parts, particularly preferably with respect to 100 parts in total of the acrylic resin (A) and the monofunctional ethylenically unsaturated compound (B). May be 15 to 30 parts. If the content is too large, the compatibility tends to decrease, and if it is too small, the antistatic performance tends to be inferior.

  Among the hydroxyl group-containing monomers (b4), a primary hydroxyl group-containing monomer is preferable from the viewpoint of a large degree of freedom of hydroxyl groups, particularly acrylic acid hydroxyalkyl ester is preferable, and 2-hydroxyethyl acrylate is used. It is particularly preferable in that it has few impurities such as (meth) acrylate and is easy to produce.

  As the hydroxyl group-containing monomer (b4) used in the present invention, if the content ratio of di (meth) acrylate as an impurity is large, it causes thickening and gelation during pressure-sensitive adhesive polymerization. It is also preferable to use an acrylate having a content ratio of 0.5% by weight or less.

  As the content of the hydroxyl group-containing monomer (b4), the hydroxyl group-containing monomer (b4) is usually 5 to 100 parts in total for the acrylic resin (A) and the monofunctional ethylenically unsaturated compound (B). 50 parts, preferably 10 to 40 parts, particularly preferably 15 to 30 parts, and if the content is too large, the compatibility tends to decrease, and if it is too small, the antistatic performance tends to be difficult to improve. .

  In the present invention, as the monofunctional ethylenically unsaturated compound (B), the glass transition temperature (Tg) when only the monofunctional ethylenically unsaturated compound (B) is copolymerized is within the range of −90 to 0 ° C. It is preferable to use those that are in the range of −80 to −10 ° C., more preferably −70 to −20 ° C. This is because if the glass transition temperature (Tg) is too low, the tendency to be inferior in cohesive force is seen, and conversely, if it is too high, sufficient adhesive strength tends to be not obtained.

  As a compounding ratio of the acrylic resin (A) and the monofunctional ethylenically unsaturated compound (B), the acrylic resin (A): monofunctional ethylenically unsaturated compound (B) is 5:95 to 50:50 ( (Weight ratio), in particular 7:93 to 45:55 (weight ratio), more preferably 10:90 to 40:60 (weight ratio). If the blending ratio of the acrylic resin (A) is too small, the viscosity is too low and tends to be a hindrance to coating. Conversely, if too large, the viscosity tends to be a hindrance to coating. This is because of However, the blending amount may be determined in consideration of viscosity and coating suitability without being limited to the above.

  Moreover, in this invention, the difference of the glass transition temperature (Tg) of acrylic resin (A) and the glass transition temperature (Tg) at the time of superposing | polymerizing only a monofunctional ethylenically unsaturated compound (B) is 10 degreeC. As described above, in particular, 20 ° C. or higher, more preferably 30 ° C. or higher, is preferable from the viewpoint of reducing the adhesive property fluctuation. This is because if the difference in the glass transition temperature (Tg) is too small, there is a tendency that the variation in adhesiveness tends to increase.

<< Ethylenically unsaturated compound (C) having two or more ethylenically unsaturated groups >>
As the ethylenically unsaturated compound (C) having two or more ethylenically unsaturated groups used in the present invention (hereinafter sometimes abbreviated as “polyfunctional ethylenically unsaturated compound (C)”), the above (A) Along with (B), it is used as a monomer constituting the temporary surface protecting pressure-sensitive adhesive composition. Like (B), it is a liquid or solid monomer.

  Examples of the polyfunctional ethylenically unsaturated compound (C) include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and propylene glycol. Di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide modified bisphenol A type di (meth) Acrylate, propylene oxide modified bisphenol A type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate , Pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, diglycidyl phthalate di (meth) acrylate, hydroxypivalic acid modified neopentyl glycol Bifunctional (meth) acrylic monomers such as di (meth) acrylate; trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl Terupori (meth) acrylate such as trifunctional or more (meth) acrylic monomer, and the like. In addition to the above, polyfunctional (meth) acrylate compounds such as urethane (meth) acrylate compounds and epoxy (meth) acrylate compounds can also be used. Among these, a tri- or higher functional (meth) acrylic monomer is preferable, and trimethylolpropane tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate are particularly preferable. Moreover, these can be used individually or in combination of 2 or more types.

  The content of the polyfunctional ethylenically unsaturated compound (C) is 6 parts or more with respect to a total of 100 parts of the acrylic resin (A) and the monofunctional ethylenically unsaturated compound (B). There is the biggest feature of. And it is preferably 7 to 30 parts, particularly preferably 8 to 20 parts, and further preferably 10 to 15 parts. In the present invention, by using the component (C) more than before, it has an appropriate adhesive force after irradiation with an active energy ray and has little change with time in the adhesive force. The effect that there is no contamination is exhibited for the first time. If the content of the component (C) is too small, the cohesive force is insufficient. In addition, when there is too much content, there exists a tendency for adhesive force to become low too much.

<< Photopolymerization initiator (D) >>
The photopolymerization initiator (D) used in the present invention is not particularly limited as long as it generates radicals by the action of active energy rays such as light, and is an intramolecular self-cleavage photopolymerization initiator or hydrogen abstraction. A type of photoinitiator is used.

  Examples of the intramolecular self-cleaving photopolymerization initiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one 1- (4-Isopropylenephenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2 -Hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzoin, Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether , Benzoin isobutyl ether, benzyldimethyl ketal, α-acyloxime ester, acylphosphine oxide, methylphenylglyoxylate, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 4-benzoyl -4'-methyldiphenyl sulfide and the like. Among them, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl phenyl ketone are preferable.

  Examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 3,3′-dimethyl-4-methoxybenzophenone, 2,4,4 6-trimethylbenzophenone, 4-methylbenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, camphorquinone, dibenzosuberone, 2-ethylanthra Examples include quinone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, benzyl, 9,10-phenanthrenequinone, among which benzophenone, methylbenzophenone, 2,4,6- Trimethylbenzofu Non is preferred. These photopolymerization initiators (D) are used alone or in combination of two or more.

  Further, by using a triazine-based photopolymerization initiator in addition to the above-mentioned photopolymerization initiator, it is possible to reduce the integrated light amount necessary for obtaining good adhesive properties after curing.

  Examples of the triazine photopolymerization initiator include 2,4,6-trisubstituted-s-triazines represented by the following general formula (a).

  Examples of the alkyl group include an alkyl group having 1 to 10 carbon atoms, specifically, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an n-hexyl group, and the like. It is done. Examples of the substituted alkyl group include a C 1-10 alkyl group substituted with a halogen atom, specifically, a trichloromethyl group, a tribromomethyl group, an α, α, β-trichloroethyl group, and the like. It is done.

  Examples of the aryl group and substituted aryl group include those having 6 to 20 carbon atoms, specifically, phenyl group, p-methoxyphenyl group, p-methylthiophenyl group, p-chlorophenyl group, 4-biphenylyl. Group, naphthyl group, 4-methoxy-1-naphthyl group and the like.

  Moreover, as said alkenyl group, C2-C12 things, such as a vinyl group, an allyl group, 2-phenylethenyl group, are mention | raise | lifted, for example. Furthermore, as said alkoxy group, C1-C10 things, such as a methoxy group, an ethoxy group, a butoxy group, are mention | raise | lifted, for example.

  The monohalogen-substituted methyl group, dihalogen-substituted methyl group or trihalogen-substituted methyl group includes chloromethyl group, bromomethyl group, iodomethyl group, dichloromethyl group, dibromomethyl group, diiodomethyl group, trichloromethyl group, tribromomethyl. Group and triiodomethyl group. Of these, a trichloromethyl group substituted with a chlorine atom is preferred.

  Such 2,4,6-trisubstituted-s-triazines represented by the general formula (a) are, for example, Journal of American Chemical Society 72, 3257-3528 (1950), Journal of American Chemical It can be synthesized according to the methods described in Society, Vol. 74, pages 5633-5636 (1952) and Juatus Lieblgs Annalen der Chemie, Vol. 577, pages 77-95 (1952).

Specific examples of the 2,4,6-trisubstituted-s-triazine represented by the general formula (a) include 2,4,6-tris (trichloromethyl) -s-triazine, 2,4, 6-tris (tribromomethyl) -s-triazine, 2,4-bis (trichloromethyl) -6-methyl-s-triazine, 2,4-bis (tribromomethyl) -6-methyl-s-triazine, 2,4-bis (trichloromethyl) -6- (p-tolyl) -s-triazine, 2,4-bis (trichloromethyl) -6-n-propyl-s-triazine, 2- (α, α, β -Trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine 2,4,6-tri 2,4,6-trisubstituted-s-triazine photoinitiators having only aliphatic substituents such as (bromomethyl) -s-triazine and 2,4,6-tris (chloromethyl) -s-triazine ,
2,4-bis (trichloromethyl) -6-phenyl-s-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenyl) -s-triazine, 2,4-bis (trichloromethyl) -6- (p-methylthiophenyl) -s-triazine, 2,4-bis (trichloromethyl) -6- (p-chlorophenyl) -s-triazine, 2,4-bis (trichloromethyl) -6- (2 ', 4'-dichlorophenyl) -s-triazine, 2- (p-bromophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2,4-bis (tribromomethyl) -6-phenyl- s-triazine, 2,4-bis (trichloromethyl) -6-styryl-s-triazine, 2,4-bis (trichloromethyl) -6- [2- (p-methoxyphenyl) ester Nyl] -s-triazine, 2,4-bis (trichloromethyl) -6- [2- (o-methoxyphenyl) ethenyl] -s-triazine, 2- [2- (p-butoxyphenyl) ethenyl]- Bis (trichloromethyl) -s-triazine, 2- [2- (3,4-dimethoxyphenyl) ethenyl] -2,4-bis (trichloromethyl) -s-triazine, 2- [2- (3,4, 5-trimethoxyphenyl) ethenyl] -2,4-bis (trichloromethyl) -s-triazine, 2- (1-naphthyl) -2,4-bis (trichloromethyl) -s-triazine, 2- (4- Biphenylyl) -2,4-bis (trichloromethyl) -s-triazine, 2- (4'-methoxy-1'-naphthyl) -2,4-bis (trichloromethyl) -s-triazine, 2,4- Bis (trichloromethyl) -6- (p-methoxynaphthyl) -s-triazine, 2,4-bis (trichloromethyl) -6- (piperonyl) -s-triazine, 2,4-bis (trichloromethyl) -6 2,4,6-trisubstituted-s-triazine photopolymerization initiator having an aromatic substituent such as-(p-methoxystyryl) -s-triazine,
Etc.
These may be used alone or in combination of two or more.

  Of these, it is preferable to use a 2,4,6-trisubstituted-s-triazine-based photopolymerization initiator having an aromatic substituent as the triazine-based photopolymerization initiator. It is particularly preferable to use 2,4-bis (trichloromethyl) -6- (p-methoxyphenyl) -s-triazine from the viewpoint of little compatibility.

  Further, if necessary, triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethyl as an auxiliary of the photopolymerization initiator (D) Benzoic acid, ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone 2,4-diisopropylthioxanthone can also be used in combination.

  Although content of a photoinitiator (D) is not specifically limited, 0.1-20 parts with respect to a total of 100 parts of acrylic resin (A) and a monofunctional ethylenically unsaturated compound (B), Especially It is preferably 0.5 to 15 parts, more preferably 1.0 to 10 parts. If the content of the component (D) is too small, there is a tendency that the polymerization by irradiation with active energy rays such as ultraviolet rays tends to be uneven, and conversely, if it is too much, no further effect is obtained and it is wasted. Because.

  When the triazine photopolymerization initiator is used alone as the photopolymerization initiator (D), the total amount of acrylic resin (A) and monofunctional ethylenically unsaturated compound (B) is 100 parts in total. It is preferable to contain 0.01 to 0.5 part of a triazine photopolymerization initiator, more preferably 0.05 to 0.45 part, still more preferably 0.1 to 0.4 part, and particularly preferably 0. 15 to 0.35 parts.

  Furthermore, an ionic compound (E) can be mix | blended with the adhesive composition of this invention with said (A)-(D) for the purpose of provision of antistatic performance.

<< Ionic compound (E) >>
The ionic compound (E) may be any compound having ionicity, for example, an alkali metal salt, an alkaline earth metal salt, a quaternary ammonium salt, an aliphatic sulfonate, a higher acid salt of an organic acid or an inorganic acid. Alcohol sulfate ester, higher alcohol alkylene oxide adduct sulfate ester salt, higher alcohol phosphate ester salt, higher alcohol alcohol alkylene oxide adduct phosphate ester salt, alkylbetaine compound, alkylimidazoline compound, alkylalanine compound, polyvinylbenzyl cation Examples thereof include polyacrylic acid type cationic compounds. Among these, alkali metal salts, alkaline earth metal salts, and quaternary ammonium salts are preferably used, and alkali metal salts are particularly preferably used.

Examples of the alkali metal salt include a cation selected from Li ⁺ , Na ⁺ and K ⁺ and Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ and CF ₃ SO _{3. ^{-, (CF 3 sO 2)}} 2 N -, (CF 3 sO 2) 3 C - metal salt composed of anions selected from is suitably used. Among these, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (CF ₃ ) are excellent in ion conductivity and excellent in antistatic function. Lithium salts such as SO ₂ ) ₃ C are preferably used.

  Examples of the alkaline earth metal salt include calcium salt, magnesium salt and halides thereof.

  Examples of the quaternary ammonium salt include quaternary ammonium such as tetraalkyl ammonium sulfonic acid, alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, trialkyl benzyl ammonium salt, alkyl pyridinium salt, and (poly) oxyalkylene trialkyl ammonium salt. A salt is preferably used.

  These ionic compounds (E) may be used alone or in combination of two or more.

  Furthermore, an ionic liquid can be used as the ionic compound (E). The ionic liquid in this invention represents the ionic substance which consists of a cation component and an anion component which hold | maintain a liquid at the fixed temperature of the range of 0-150 degreeC.

  The cation component is not particularly limited, and a cation used in a general ionic liquid is used. Examples of such cations include, for example, cations of heterocyclic compounds, particularly cations of 1 to 5 membered heterocyclic compounds containing 1 to 5 heteroatoms, particularly nitrogen atoms as heteroatoms. Examples thereof include cations of 1 to 5 membered heterocyclic compounds containing 1 to 5 heteroatoms, and among them, imidazolium cation, pyrrolidinium cation, piperidinium cation, pyridinium cation and the like are preferable. It is also preferable to use a chain-like quaternary ammonium cation or quaternary phosphonium cation. Among these, imidazolium cation, pyridinium cation, quaternary ammonium cation, and quaternary phosphonium cation are preferable, and imidazolium cation is particularly preferable in terms of low viscosity.

On the other hand, the anion component is not particularly limited. For example, Cl ⁻ , Br ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , _{^{CH 3 COO -, CF 3 COO}} -, CH 3 SO 3 - CF 3 SO 3 -, (CF 3 SO 2) 2 N -, (CF 3 SO 2) 3 C -, AsF 6 -, SbF 6 -, NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF _{3 SO 2) (CF 3 CO} ) N - it is possible to use an anion commonly used in ionic liquids and the like.

  Further, as the ionic liquid used in the present invention, an ionic liquid containing a polymerizable unsaturated group can also be used. For example, 1- (2- (meth) acryloyloxyethyl) -3-octylimidazolium bromide (Meth) acrylic imidazolium cation systems such as halogen salts of (meth) acryloyloxyethyl-3-alkylimidazolium such as 1- (2- (meth) acryloyloxyethyl) -3-octylimidazolium chloride Compounds, vinylimidazolium cation compounds such as 1-butyl-3-vinylimidazolium tetrafluoroborate (1B3VIBF4), 1-butyl-3-vinylimidazolium trifluoromethanesulfonimide (1B3VITFSI), and halogen ions as anionic components An ionic liquid consisting ofWhen these ionic liquids having a polymerizable unsaturated group are used, they are involved in the polymerization by irradiation with active energy rays, which is preferable without causing bleed out.

  The content of the ionic compound (E) is preferably 0.01 to 5 parts with respect to a total of 100 parts of the acrylic resin (A) and the monofunctional ethylenically unsaturated compound (B). Preferably it is 0.05-3 parts, Most preferably, it is 0.1-1.5 parts. If the content of the ionic compound (E) is too small, the effect of imparting antistatic performance tends to be difficult to obtain, and if the content of the ionic compound (E) is too large, the adhesive physical properties may decrease. , Tend to cause glue residue.

  In addition, the pressure-sensitive adhesive composition of the present invention is one that is crosslinked by irradiating active energy rays instead of the conventional method of crosslinking an acrylic resin using a general crosslinking agent. In order to enhance the adhesion, the cross-linking agent may be blended in a small amount compared to the conventional case, that is, in an amount range that does not extend the aging time, but it is usually preferable to use without using the cross-linking agent.

  Examples of the crosslinking agent include isocyanate-based, epoxy-based, metal salts, metal alkoxides, aldehyde-based compounds, non-amino resin-based amino compounds, urea-based, metal chelate-based, melamine-based, and aziridin-based crosslinkers. You can give the agent.

  Further, in the present invention, other pressure-sensitive adhesives, urethane resins, rosins, rosin esters, hydrogenated rosin esters, phenol resins, aromatic modified terpene resins, aliphatic petroleum resins, alicyclic rings, as long as the effects of the present invention are not impaired. It is possible to add tackifiers such as group petroleum resins, styrene resins and xylene resins, known additives, and compounds that cause coloration or discoloration upon irradiation with ultraviolet rays or radiation.

  By using the said component material, the active energy ray-curable composition which is an adhesive composition for temporary surface protection of this invention is obtained.

<< Temporary Surface Protection Adhesive Composition, Method for Producing Adhesive and Adhesive Sheet >>
The pressure-sensitive adhesive composition for temporary surface protection of the present invention, that is, the active energy ray-curable composition, comprises the acrylic resin (A), monofunctional ethylenically unsaturated compound (B), polyfunctional ethylenically unsaturated compound ( It can be obtained by mixing other components such as C), a photopolymerization initiator (D), and an ionic compound (E) blended as necessary.

  The active energy ray-curable composition is usually composed of the acrylic resin (A), polyfunctional ethylenically unsaturated compound (C), photopolymerization initiator (D) in the monofunctional ethylenically unsaturated compound (B). In addition, it is preferable that other components such as the ionic compound (E) to be blended as necessary are dissolved or uniformly dispersed. This active energy ray-curable composition comprises an acrylic resin (A), a monofunctional ethylenically unsaturated compound (B), a polyfunctional ethylenically unsaturated compound (C), a photopolymerization initiator (D), and further necessary. The ionic compound (E) and other components blended accordingly can be prepared by heating and mixing at room temperature (25 ° C. ± 10 ° C.) or in some cases from room temperature to 60 ° C. More preferably, each component except the photopolymerization initiator (D) is premixed in advance at room temperature or in a heated state (0.5 to 30 hours), and then mixed with the photopolymerization initiator (D). The active energy ray-curable composition is prepared.

  The active energy ray-curable composition is a liquid composition having viscosity. Therefore, the active energy ray-curable composition of the present invention can be applied to a substrate as it is. In some cases, it may be diluted with an organic solvent, but it is preferable not to contain an organic solvent from the viewpoint of workability of adhesive production and compatibility with the global environment. If the acrylic resin (A) of dry resin obtained by suspension polymerization or the like is used, the active energy ray-curable composition can be produced without containing an organic solvent.

  Furthermore, the said active energy ray curable composition becomes an active energy ray irradiation polymer by irradiating an active energy ray, and has the adhesive performance as a temporary surface protection adhesive.

  When irradiating active energy rays, as active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, neutron rays, etc. can be used. However, curing by ultraviolet irradiation is advantageous from the viewpoint of curing speed, availability of an irradiation device, price, and the like.

  For ultraviolet irradiation, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, or the like that emits light in a wavelength range of 150 to 450 nm can be used.

In the present invention, the exposure dose of the actinic energy ray is preferably at 500 mJ / cm ² or more, further 1000 mJ / cm ² or more, and particularly preferably at 1500 mJ / cm ² or more. If the amount of irradiation is too small, there is a tendency that variation in crosslinking by irradiation with active energy rays tends to occur. The upper limit of the irradiation dose is usually 10,000 mJ / cm ² . If the irradiation amount is too large, it is not preferable because of the device and cost.
When a triazine photopolymerization initiator is used as the photopolymerization initiator (D), the irradiation amount of active energy rays is usually 1000 mJ / cm ² or less (more preferably 800 mJ / cm ² or less) and sufficient crosslinking is performed. Is preferable.

  The temporary surface protecting pressure-sensitive adhesive which is an active energy ray irradiated polymer after being crosslinked by irradiation with active energy rays preferably has a gel fraction of 80 to 100% by weight, particularly 85 to 100% by weight, Further, it is preferably 90 to 100% by weight. This is because if the gel fraction is too small, the peelability of the pressure-sensitive adhesive tends to be reduced due to insufficient cohesive force.

  In addition, the said gel fraction becomes a standard of a crosslinking degree, and is computed with the following method. That is, an adhesive sheet (not provided with a separator) obtained as described below is wrapped in a 200 mesh SUS wire mesh, immersed in toluene at 23 ° C. for 24 hours, and the insoluble adhesive component remaining in the wire mesh The weight percentage is taken as the gel fraction. At this time, the weight of the substrate is subtracted.

  Here, in adjusting the gel fraction of such an adhesive to the above range, adjusting the irradiation amount and irradiation intensity of the active energy ray, the photopolymerization initiator is of a kind of self-cleavage type and hydrogen abstraction type. The use of two different types of photopolymerization initiators and the combined use of two types of photopolymerization initiators can be achieved by adjusting the ratio of each type and adjusting the amount of the photopolymerization initiator.

  It should be noted that the irradiation amount and irradiation intensity of the active energy ray, the composition ratio of the photopolymerization initiator, and the addition amount need to be balanced because the gel fraction varies depending on the respective interactions.

  In the present invention, as described above, the active energy ray-curable composition is used to have adhesive performance as a temporary surface protecting adhesive by irradiating active energy rays, specifically, For example, after applying or impregnating the active energy ray-curable composition to a substrate, the active energy ray is irradiated to produce an adhesive sheet having an adhesive layer formed on the substrate. It is bonded to the kimono.

  In the present invention, “sheet” is not particularly distinguished from “film”, and is described as meaning including film.

  The material of the base material is not particularly limited as long as it is a material forming a sheet. For example, aluminum, copper, iron metal foil, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer Polyester resins such as coalescence, polyolefin resins such as polyethylene, polypropylene, polymethylpentene, polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene, polyamides such as nylon 6, nylon 6,6, and poly Cellulose such as vinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, vinyl polymers such as polyvinyl alcohol and vinylon, cellulose triacetate, cellophane, etc. Resin, polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate and other acrylic resins, polystyrene, polycarbonate, polyarylate, polyimide and other synthetic resin sheets, fine paper, glassine paper, etc. Examples thereof include a single layer or a multilayer such as paper, glass fiber, natural fiber, and synthetic fiber.

  Among these, in consideration of price, a sheet of polyethylene terephthalate, polyethylene, polypropylene, or the like is preferably used.

  In addition, in order to improve the anchoring property of the pressure-sensitive adhesive layer to the base material, the surface of the base material is treated to improve known easy tackiness such as corona discharge treatment, plasma treatment, primer coating, degreasing treatment, and surface roughening treatment. In addition, an antistatic layer may be provided for antistatic.

  Although the thickness of the said base material is not specifically limited, Generally it is 500 micrometers or less, Preferably it is 5-300 micrometers, More preferably, the thickness of about 10-200 micrometers can be illustrated.

  The thickness of the pressure-sensitive adhesive layer formed on the substrate is not particularly limited, but is generally 1 to 100 μm, preferably about 2 to 50 μm. If the thickness of the pressure-sensitive adhesive layer is too thick, the adhesive of the temporary surface protecting pressure-sensitive adhesive sheet tends to remain on the surface of the adherend when it is peeled off. This is because the adhesive strength to the adherend tends to decrease and peeling tends to occur, making it difficult to perform the function as the surface protective pressure-sensitive adhesive sheet.

  The initial adhesive strength of the pressure-sensitive adhesive sheet using the temporary surface-protecting pressure-sensitive adhesive of the present invention is usually preferably 0.05 to 1.0 (N / 25 mm), and particularly 0.06 to 0.7 (N / 25 mm), more preferably 0.07 to 0.5 (N / 25 mm).

  The initial adhesive strength is calculated as follows. First, the obtained pressure-sensitive adhesive sheet was cut into 25 mm × 100 mm, and this was then applied to a stainless steel plate (SUS304BA plate) as an adherend using a 2 kg rubber roller in an atmosphere of 23 ° C. and 50% relative humidity. A test piece is produced by pressure bonding by reciprocating. After leaving this test piece for 30 minutes under the same atmosphere, a 180 degree peel test is performed at a peel speed of 0.3 m / min, and the measured adhesive strength (N / 25 mm) is applied to the initial adhesive strength.

  Moreover, it is preferable that the time-dependent adhesive force of the adhesive sheet using the adhesive for temporary surface protection of this invention is 0.05-1.0 (N / 25mm) normally, Especially 0.06-0.7. (N / 25 mm), more preferably 0.07 to 0.5 (N / 25 mm).

  The adhesive strength with time is calculated as follows. A test piece prepared by the same method as the initial adhesive strength is left for 5 days in an atmosphere of 70 ° C. and 50% relative humidity. Thereafter, a 180 ° peel test is performed at 23 ° C. and a relative humidity of 50% at a peel rate of 0.3 m / min, and the measured adhesive strength (N / 25 mm) is defined as the temporal adhesive strength.

  The high-speed peel adhesive strength of the pressure-sensitive adhesive sheet using the temporary surface protecting adhesive of the present invention is usually preferably 7 times or less, particularly 5 times or less, more preferably 4 times or less of the initial pressure-sensitive adhesive force. Is preferred. Moreover, it is preferable that a high-speed peeling adhesive force is 0.05-3.0 (N / 25mm) normally, especially 0.06-1.0 (N / 25mm), Furthermore, 0.07-0. 5 (N / 25 mm) is preferable. This is because if the adhesive strength is too large, there is a tendency to become a hindrance when peeling after the end of the protection purpose.

  The high-speed peel adhesive strength is calculated as follows. A test piece prepared by the same method as the initial adhesive strength was left for 30 minutes in an atmosphere of 23 ° C. and 50% relative humidity. Thereafter, in the same atmosphere, a 180 ° peel test is performed at a high speed of 30 m / min, and the measured adhesive strength (N / 25 mm) is defined as the high speed peel adhesive strength.

  A separator can be laminated on the surface of the pressure-sensitive adhesive sheet for the purpose of protecting the pressure-sensitive adhesive layer from contamination until the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive for temporary surface protection of the present invention is bonded to an adherend. As the separator, those obtained by releasing the synthetic resin sheet, paper, cloth, nonwoven fabric and the like exemplified in the base material can be used.

  As described above, the pressure-sensitive adhesive sheet using the temporary surface protecting pressure-sensitive adhesive of the present invention is obtained by applying or impregnating a base material with an active energy ray-curable composition and irradiating the active energy ray. When the active energy ray-curable composition is in the form of a solution, a direct coating method in which the solution-like active energy ray-curable composition is directly applied to a substrate, or a solution-like active energy ray-curable composition After being coated on the separator, the substrate is laminated on the substrate by a transfer coating method in which the substrate is bonded to the substrate.

  In the direct coating method, an active energy ray-curable composition is applied to a base material, and after heating and drying as necessary, a separator is bonded. The coating is performed by a conventional method such as roll coating, die coating, gravure coating, comma coating, or screen printing.

  On the other hand, in the transfer coating method, the substrate is bonded after the active energy ray-curable composition is applied. About the coating method, the method similar to direct coating can be used.

  The pressure-sensitive adhesive sheet using the temporary surface-protecting pressure-sensitive adhesive of the present invention is applied to the surface of the adherend, and then the temporary surface-protective pressure-sensitive adhesive of the present invention even if the adherend or the pressure-sensitive adhesive sheet is exposed to high temperature. Can be peeled off from the adherend.

  There are no particular limitations on the type of adherend that can be used for the temporary surface protecting adhesive of the present invention. For example, aluminum, copper, iron metal foil, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate Polyester resins such as isophthalate copolymers, polyolefin resins such as polyethylene, polypropylene, and polymethylpentene, polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene, nylon 6, nylon 6, 6, etc. Polyamides, polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon, cellulose triacetate, cellophane, etc. Cellulose-based resins, polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, acrylic resins such as polybutyl acrylate, polystyrene, polycarbonate, polyarylate, synthetic resin sheet or plate such as polyimide and the like.

  As described above, the temporary surface protecting adhesive of the present invention is used for metal plates, glass plates, synthetic resin plates, laminated steel plates, etc. for labels / sheets, tapes, building materials, packaging materials, and electronics. It can be suitably used as an adhesive for temporary surface protection.

  And the adhesive sheet using the adhesive for temporary surface protection can be temporarily protected by adhering to the adherend surface, and after the protection purpose is finished, The pressure-sensitive adhesive sheet is peeled off from the adherend.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

[Production Example 1] Preparation of acrylic resin 300 parts of water was placed in a glass four-necked round bottom flask equipped with a stirrer, 0.7 parts of polyvinyl alcohol was dissolved as a dispersion stabilizer, and 300 rpm with a stirring blade. While stirring, a monomer mixture consisting of 87.8 parts of n-butyl acrylate, 7.2 parts of acrylonitrile, 5 parts of 2-hydroxyethyl methacrylate and N, N′-azobisisobutyronitrile 0 as a polymerization initiator .9 parts were added all at once to prepare a suspension.

  The suspension was allowed to react with stirring for 4 hours while the temperature in the reaction system was raised to 68 ° C. while stirring was continued. Then, it cooled to room temperature (about 25 degreeC). Next, the reaction product was separated into solid and liquid, sufficiently washed with water, and then dried at 70 ° C. for 12 hours using a dryer to obtain a block acrylic resin. The resulting acrylic resin had a weight average molecular weight (Mw) of 1.3 million, a dispersity (Mw / Mn) of 4.6, and a glass transition temperature of −47 ° C.

  Using the acrylic resin obtained in Production Example 1, each active energy ray-curable composition and pressure-sensitive adhesive sheet were produced according to the following Examples and Comparative Examples.

[Example 1]
14.6 parts of acrylic resin (A) obtained in Production Example 1, 39.4 parts of 2-ethylhexyl acrylate (2EHA) as monofunctional ethylenically unsaturated compound (B), n-butyl acrylate (n-BA) 39.4 parts, 6.6 parts of acrylic acid (AAc), and 10 parts of dipentaerythritol hexaacrylate (DPHA) as a polyfunctional ethylenically unsaturated compound (C) are placed in a container equipped with a stirrer and mixed with stirring for 24 hours. And dissolved. To this solution, 1 part of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name: “Darocur 1173”; manufactured by Ciba Specialty Chemicals) was mixed as a photopolymerization initiator (D). Thus, an active energy ray-curable composition was obtained.

The active energy ray-curable composition obtained above was applied on a polyethylene terephthalate (PET) substrate having a thickness of 38 μm so as to have a thickness of 25 μm. Furthermore, the coated surface was coated so that the release-treated surface was in contact with the coated surface, using a PET substrate that had been subjected to a release treatment. Thereafter, ultraviolet light was irradiated from a high-pressure mercury lamp adjusted to an irradiation intensity of 200 mW / cm ² so that the integrated light amount was 2400 mJ / cm ^2, and photopolymerized to obtain an adhesive sheet.

[Example 2]
The same as Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 10 parts of trimethylolpropane triacrylate (TMPTA). Thus, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

Example 3
The active energy ray curability was the same as in Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 7 parts. A composition and an adhesive sheet were obtained.

Example 4
The same as Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 7 parts of trimethylolpropane triacrylate (TMPTA). Thus, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

Example 5
Active energy ray curable in the same manner as in Example 1, except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 6 parts. A composition and an adhesive sheet were obtained.

Example 6
10.0 parts of acrylic resin (A) obtained by Production Example 1, 83.4 parts of n-butyl acrylate (n-BA) as monofunctional ethylenically unsaturated compound (B), and 6.6 acrylic acid (AAc). 6 parts, 7 parts of pentaerythritol triacrylate (PETA) as a polyfunctional ethylenically unsaturated compound (C) was placed in a container equipped with a stirrer, and stirred and mixed for 24 hours to dissolve. To this solution, 1 part of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name: “Darocur 1173”; manufactured by Ciba Specialty Chemicals) was mixed as a photopolymerization initiator (D). Thus, an active energy ray-curable composition was obtained.

The active energy ray-curable composition obtained above was applied on a polyethylene terephthalate (PET) substrate having a thickness of 38 μm so as to have a thickness of 25 μm. Furthermore, the coated surface was coated so that the release-treated surface was in contact with the coated surface, using a PET substrate that had been subjected to a release treatment. Thereafter, ultraviolet light was irradiated from a high-pressure mercury lamp adjusted to an irradiation intensity of 200 mW / cm ² so that the integrated light amount was 2400 mJ / cm ^2, and photopolymerized to obtain an adhesive sheet.

Example 7
In Example 6, the integrated light quantity of ultraviolet irradiation was set to 800 mJ / cm ² . Other than that was carried out similarly to Example 6, and obtained the active energy ray hardening-type resin composition and the adhesive sheet.

Example 8
Instead of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name: “Darocur 1173”; manufactured by Ciba Specialty Chemicals), which is the photopolymerization initiator (C) of Example 7. In the same manner as in Example 7, except that 0.3 part of 2,4-bis (trichloromethyl) -6- (p-methoxyphenyl) -s-triazine (manufactured by Nippon Sebel Hegner, Triazine A) was used. An active energy ray-curable resin composition and an adhesive sheet were produced.

[Comparative Example 1]
Active energy ray curable in the same manner as in Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 3 parts. A composition and an adhesive sheet were obtained.

[Comparative Example 2]
Active energy ray in the same manner as in Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), in Example 1 was changed to 0.3 parts. A curable composition and an adhesive sheet were obtained.

[Comparative Example 3]
The same as Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 3 parts of trimethylolpropane triacrylate (TMPTA). Thus, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

[Comparative Example 4]
Example 1 except that 10 parts of dipentaerythritol hexaacrylate (DPHA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 1 was changed to 0.3 part of trimethylolpropane triacrylate (TMPTA). In the same manner as above, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

  Table 1 below shows the blending ratios of the above component materials used in Examples and Comparative Examples.

  About the adhesive sheet obtained by said Example and comparative example, while performing an adhesive characteristic evaluation by the following method, the gel fraction of the adhesive layer was measured, and the result was combined in Table 2 of the postscript. Show.

<Evaluation test of adhesive sheet>
(1) Initial adhesive strength After the obtained adhesive sheet was cut into 25 mm × 100 mm, this was applied to a stainless steel plate (SUS304BA plate) as an adherend in a 2 kg rubber roller in an atmosphere of 23 ° C. and 50% relative humidity. A test piece was prepared by pressure bonding by reciprocating twice. After leaving this test piece for 30 minutes under the same atmosphere, a 180 ° peel test was performed at a peel rate of 0.3 m / min, and the initial adhesive strength (N / 25 mm) was measured. The initial adhesive strength was evaluated according to the following criteria. In addition, evaluation (double-circle) and (circle) are made into the pass level of the adhesive force for temporary surface protection.
A fine adhesive strength of 0.5 (N / 25 mm) or less.
○: Slight adhesive force exceeding 0.5 (N / 25 mm) and 1 (N / 25 mm) or less.
Δ: Adhesive force exceeding 1 (N / 25 mm) and 3 (N / 25 mm) or less.
X: Adhesive force exceeding 3 (N / 25 mm).

(2) Adhesive strength over time A test piece was prepared in the same manner as the test piece prepared by the above initial adhesive force measurement, and this test piece was left in an atmosphere of 70 ° C. and 50% relative humidity for 5 days. Thereafter, a 180 ° peel test was conducted at 23 ° C. and a relative humidity of 50% at a peel rate of 0.3 m / min, and the adhesive strength with time (N / 25 mm) was measured. Evaluation of adhesive strength with time was performed according to the following criteria. In addition, evaluation (double-circle) and (circle) are made into the pass level of the adhesive force for temporary surface protection.
A fine adhesive strength of 0.5 (N / 25 mm) or less.
○: Slight adhesive force exceeding 0.5 (N / 25 mm) and 1 (N / 25 mm) or less.
Δ: Adhesive force exceeding 1 (N / 25 mm) and 3 (N / 25 mm) or less.
X: Adhesive force exceeding 3 (N / 25 mm).
-Since the initial adhesive force has an adhesive force exceeding 3 (N / 25 mm), no measurement was performed.

(3) High-speed peel adhesive strength A test piece was prepared by the same method as the test piece prepared by the above initial adhesive force measurement, and this test piece was left for 30 minutes in an atmosphere of 23 ° C. and 50% relative humidity. Thereafter, under the same atmosphere, a 180 degree peel test was performed at a high speed of 30 m / min, and the high speed peel adhesive strength (N / 25 mm) was measured. Evaluation of high-speed peeling adhesive force was performed according to the following criteria. In addition, evaluation (circle) is set as the pass level of the adhesive force for temporary surface protection.
○ ・ ・ ・ High-speed peel adhesive strength is 7 times or less of initial adhesive strength.
Δ: High-speed peel adhesive strength exceeds 7 times the initial adhesive strength and less than 10 times.
X: The high-speed peel adhesive strength is 10 times or more the initial adhesive strength.
-Since the initial adhesive force has an adhesive force exceeding 3 (N / 25 mm), no measurement was performed.

(4) Initial gel fraction After the obtained pressure-sensitive adhesive sheet was cut into 50 mm × 50 mm, the pressure-sensitive adhesive layer side of this pressure-sensitive adhesive sheet was avoided from the central portion in the longitudinal direction of a 60 × 100 mm SUS mesh sheet (200 mesh). Then, the test piece was attached to the mesh sheet, and then the mesh sheet was folded from the center to wrap the adhesive sheet. The test piece is immersed in a sealed container containing 180 g of toluene at 23 ° C. for 24 hours, and the weight percentage of the insoluble adhesive component remaining in the mesh sheet is defined as the gel fraction. At this time, the weight of the substrate is subtracted.

  From the above results, in all Examples, both the initial adhesive strength and the temporal adhesive strength showed a slight adhesive strength, and good results were obtained as the temporary surface protecting adhesive strength. Moreover, also in the high-speed peel adhesive strength, the increase in the adhesive strength was about twice that of the initial adhesive strength, resulting in a good high-speed peel adhesive strength. Therefore, it can be seen that in all Examples, the adhesive strength is moderate and the change in adhesive strength with time is small. When the above results are examined in more detail, there is not much difference between the initial adhesive strength and the temporal adhesive strength, and the gel fraction reaches about 90% by weight in the initial stage. This indicates that the physical properties of the pressure-sensitive adhesive are sufficiently stable at the initial adhesive force, and it can be seen that the curing period is almost unnecessary. And when the surface of each adherend after the peel test of the initial adhesive strength, the temporal adhesive strength and the high-speed peel adhesive strength was observed, in all the examples, no contamination of the adherend to the adherend was confirmed. . Furthermore, in Example 8 using a triazine photopolymerization initiator as the photopolymerization initiator (D), both initial adhesive strength and temporal adhesive strength showed a slight adhesive strength even with ultraviolet irradiation with a small integrated light amount. Good results were obtained as the adhesive force for temporary surface protection.

  On the other hand, Comparative Examples 2 and 4 that deviate significantly from the content of the polyfunctional ethylenically unsaturated compound (C) defined by the present invention already showed a high adhesive strength at the initial stage, and apparently for temporary surface protection. It can be seen that it cannot be used. In addition, Comparative Examples 1 and 3 that do not reach the content of the polyfunctional ethylenically unsaturated compound (C) defined in the present invention slightly show results of good initial tackiness, but are extremely inferior to high-speed peel tackiness. It became. After the end of the protection purpose, it is understood that such a pressure-sensitive adhesive sheet that is remarkably inferior in the high-speed peelability cannot be used for the temporary surface protection application because high-speed peeling is the actual situation of the temporary surface protection use.

《Granting antistatic performance》
Example 9
In addition to changing 7 parts of trimethylolpropane triacrylate (TMPTA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 4 to 7 parts of pentaerythritol triacrylate (PETA), Sankonol PETA-30R [pentaerythritol triacrylate / Li salt compound = C ₁₄ H ₁₈ O ₇ / Li (CF ₃ SO ₂ ) ₂ N = 70/30 (manufactured by Sanko Chemical Co., Ltd.), which is an ionic compound (E) wt%)]. Otherwise in the same manner as in Example 4, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

Example 10
In addition to changing 7 parts of trimethylolpropane triacrylate (TMPTA), which is the polyfunctional ethylenically unsaturated compound (C), of Example 4 to 7 parts of pentaerythritol triacrylate (PETA), Sankonol PETA-20T manufactured by Sanko Chemical Co., Ltd. [pentaerythritol triacrylate / Li salt compound = C ₁₄ H ₁₈ O ₇ / CF ₃ SO ₃ Li = 80/20 (wt%)], which is an ionic compound (E) 1 part was blended. Otherwise in the same manner as in Example 4, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

Example 11
10 parts of acrylic resin (A) obtained in Production Example 1, 43.4 parts of n-butyl acrylate (n-BA) as monofunctional ethylenically unsaturated compound (B), 6.6 acrylic acid (AAc) 40 parts of a polyethylene glycol derivative represented by the following structural formula (2) (manufactured by NOF Corporation, AME-400), 7 parts of dipentaerythritol hexaacrylate (DPHA) as a polyfunctional ethylenically unsaturated compound (C) Was placed in a container equipped with a stirrer and stirred and mixed for 24 hours to dissolve. To this solution, 1 part of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name: “Darocur 1173”; manufactured by Ciba Specialty Chemicals) was mixed as a photopolymerization initiator (D). Thus, an active energy ray-curable composition was obtained.

  Using the active energy ray-curable composition obtained above, a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Example 12
In addition to the compounding component materials in Example 8, Sanconol PETA-30R manufactured by Sanko Chemical Co., Ltd. [pentaerythritol triacrylate / Li salt compound = C ₁₄ H ₁₈ O ₇ / Li (CF) is used as the ionic compound (E). ₃ SO ₂ ) ₂ N = 70/30 (wt%)] was blended. Otherwise in the same manner as in Example 8, an active energy ray-curable composition and a pressure-sensitive adhesive sheet were obtained.

  The blending component materials and blending ratios in Examples 9 to 12 are shown in Table 3 below.

  About the adhesive sheet obtained in the said Example, while evaluating the adhesive characteristic according to the method similar to the above, the gel fraction of the adhesive layer was measured like the above. Furthermore, the surface resistivity in each adhesive sheet was measured according to the following method. The results are also shown in Table 4 below.

[Surface resistance value]
The pressure-sensitive adhesive sheet from which the release-treated PET has been peeled off is left for 3 hours under conditions of a temperature of 23 ° C. and a relative humidity of 50%, and after humidity control, the surface resistance value is measured using Hirestar UP (Mitsubishi Chemical Corporation). Was measured. The smaller the measured value, the higher the antistatic performance.

  From the above results, in Examples 9 to 12, both the initial adhesive strength and the temporal adhesive strength showed a slight adhesive strength as in the previous examples, and good results were obtained as the temporary surface protecting adhesive strength. In addition, with respect to Examples 9 and 10, also in the high-speed peel adhesive strength, the increase in the adhesive strength is in the range of about 1.2 to 1.5 times the initial adhesive strength, resulting in good high-speed peel adhesive strength. It was. Therefore, in Examples 9-12, it turns out that it has moderate adhesive force and there is little change with time of adhesive force. Moreover, the gel fraction has reached at least about 90% by weight in the initial stage. This indicates that the physical properties of the pressure-sensitive adhesive are sufficiently stable at the initial adhesive force, and it can be seen that the curing period is almost unnecessary. And when the surface of each adherend after the peel test of the initial adhesive strength, the temporal adhesive strength and the high-speed peel adhesive strength was observed, in all the examples, no contamination of the adherend to the adherend was confirmed. . Further, in Examples 9 to 12, in addition to such excellent adhesive properties, it can be seen that all of them have small surface resistivity and excellent antistatic performance. In Example 12 using a triazine-based photopolymerization initiator as the photopolymerization initiator (D), as in Example 8 above, the initial adhesive force and the time-dependent adhesion even with UV irradiation with a small integrated light amount. Both strengths showed slight adhesion, and good results were obtained as adhesion for temporary surface protection.

  The present invention can greatly shorten the curing period, has an appropriate adhesive force after irradiation with active energy rays, has little change over time in adhesive force, and does not contaminate the adherend after peeling. The present invention provides a temporary surface protecting pressure-sensitive adhesive composition, a pressure-sensitive adhesive obtained thereby, a pressure-sensitive adhesive sheet, and a method for using the pressure-sensitive adhesive sheet, and for labels and sheets, for tapes, for building materials, for packaging materials, and for electronics. It is very useful as an adhesive for temporary surface protection used for metal plates, glass plates, synthetic resin plates, laminated steel plates and the like.

Claims (8)

An acrylic resin (A), an ethylenically unsaturated compound (B) having one ethylenically unsaturated group, an ethylenically unsaturated compound (C) having two or more ethylenically unsaturated groups, and a photopolymerization initiator ( D) an active energy ray-curable pressure-sensitive adhesive composition for temporary surface protection, wherein the acrylic resin (A) is a dry resin obtained by suspension polymerization having a weight average molecular weight of 850,000 or more. The temporary surface protecting pressure-sensitive adhesive composition, wherein the content of (C) is 6 parts by weight or more based on 100 parts by weight of the total of (A) and (B). The glass transition temperature of the acrylic resin (A) (Tg) is, according to claim 1 Symbol placement of the temporary surface protective pressure-sensitive adhesive composition is in the range of -70~20 ℃. The pressure-sensitive adhesive composition for temporary surface protection according to claim 1 or 2 , which does not contain a solvent. Furthermore, the adhesive composition for temporary surface protection as described in any one of Claims 1-3 containing an ionic compound (E). A temporary surface protecting adhesive, which is obtained by irradiating active energy rays to the temporary surface protecting adhesive composition according to any one of claims 1 to 4 . The pressure-sensitive adhesive for temporary surface protection according to claim 5 , wherein the gel fraction is 80 to 100%. A substrate, the temporary surface protective pressure sensitive adhesive sheet comprising a layer made from a temporary surface protective pressure sensitive adhesive agent according to claim 5 or 6. A method for using a temporary surface protecting adhesive sheet, comprising: attaching the temporary surface protecting adhesive sheet according to claim 7 to an adherend surface, protecting the adherend surface, and then peeling the adhesive sheet.