JP5888839B2 - Acrylic pressure-sensitive adhesive manufacturing method, pressure-sensitive adhesive sheet manufacturing method - Google Patents

Description

The present invention relates to a method for producing an acrylic pressure-sensitive adhesive, and a method of manufacturing the pressure-sensitive adhesive sheet, and more particularly excellent in wettability, a method of manufacturing an acrylic pressure-sensitive adhesive is easily bonded to an adherend, it The present invention relates to a method for producing the pressure-sensitive adhesive sheet used.

  Various displays such as word processors, computers, mobile phones, and televisions; optical components such as polarizing plates and laminates equivalent to them; polyethylene, polyester, polypropylene, etc. on the surface of electronic substrates and the like, usually for the purpose of surface protection and functionality A transparent protective sheet (base sheet) such as a surface protective pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive is laminated is laminated.

  The pressure-sensitive adhesive constituting such a surface protective pressure-sensitive adhesive sheet is required to have high wettability or affixed so that air does not remain between the adherend and the pressure-sensitive adhesive sheet when bonded to an adherend such as a display. In order to correct the position of the adherend or to remove the adhesive from the surface of the adherend when it is removed and removed, the surface of the adherend is required to have high contamination resistance. It was.

  Silicone pressure-sensitive adhesives have been widely used as the pressure-sensitive adhesive used for the surface protecting pressure-sensitive adhesive sheet. However, silicone pressure-sensitive adhesives are difficult to handle in terms of production and are very expensive. In addition, acrylic adhesives obtained by copolymerizing acrylic monomers and silicone macromers have also been developed, but acrylic adhesives obtained by copolymerizing silicone macromers are prone to gelation when many silicone macromers are copolymerized. In addition, there is a problem that the compatibility with the acrylic monomer is poor and turbidity occurs. For this reason, development of a non-silicone surface protective adhesive sheet has been demanded.

  For example, in Patent Document 1, a monomer component containing a (meth) acrylic acid alkylene oxide adduct as a main component and further containing a (meth) acrylic monomer or other polymerizable monomer as needed is (co) polymerized. An acrylic pressure-sensitive adhesive comprising an acrylic copolymer and a crosslinking agent has been proposed.

  Moreover, in patent document 2, the adhesive for temporary surface protection formed by carrying out cross-linking polymerization of acrylic resin and an ionic compound, and the unsaturated group containing compound (UV hardening monomer) containing an oxyalkylene chain structure by active energy ray irradiation. Has been proposed.

Japanese Patent Laid-Open No. 2005-200540 JP 2010-31255 A

  However, in the technique disclosed in Patent Document 1, since an acrylic copolymer composed of a copolymer component containing a large amount of (meth) acrylic acid alkylene oxide adduct is used, the wettability and removability are limited to some extent. Although it is expected to exert its effect, the monomer containing an alkylene oxide structure usually contains many diester components as impurities that are difficult to remove during production. There is a manufacturing problem that it is difficult to increase the reaction rate of the monomer and it is very difficult to increase the molecular weight, and even if the manufacturing problem can be solved, Acrylic copolymers based on monomers containing an alkylene oxide structure are soft and have a low elastic modulus. Is in poor condition, there is a problem that such squeeze-out of the glue pulling or glue is likely to occur during processing.

  Furthermore, in a normal solution polymerization, a certain amount of unreacted monomer is present in the acrylic copolymer, and the monomer containing an alkylene oxide structure has a high boiling point and is difficult to volatilize even in the drying process. There is also a problem that the monomer remaining in the bleed is likely to contaminate the adherend, and in order to solve such a problem of adherend contamination, a method of highly crosslinking the acrylic copolymer may be considered, In that case, the fluidity of the acrylic copolymer is lowered, resulting in a problem of insufficient wettability.

  On the other hand, in the technique disclosed in Patent Document 2, it is described that the adhesive used for temporary surface protection is excellent in antistatic property, stain resistance, releasability, wettability, and the like. Since it mainly uses ethylenically unsaturated monomers having 2 or more unsaturated groups, the cross-linking density and elastic modulus of the pressure-sensitive adhesive layer after UV irradiation are very high compared to general pressure-sensitive adhesives. There is a problem that the tack of the adhesive drops and the tackiness when sticking the adhesive to the adherend is poor, and also regarding the sticking property with the adherend, in the step of sticking using a machine etc. Although sufficient bonding wettability is exhibited, there is a problem that when the bonding is performed manually, since the wettability is insufficient, bubbles tend to bite and are difficult to bond.

Therefore, in the present invention, under such a background, it is an acrylic pressure-sensitive adhesive having high wettability, and even when used as a pressure-sensitive adhesive layer of a surface protective pressure-sensitive adhesive sheet, it can be bonded without air remaining. An object of the present invention is to provide a method for producing an acrylic pressure-sensitive adhesive and a method for producing a pressure-sensitive adhesive sheet that are excellent in stain resistance to an adherend during peeling.

  However, as a result of intensive studies in view of such circumstances, the present inventor, instead of an acrylic resin composition comprising an acrylic resin obtained by copolymerizing a copolymer component containing an oxyalkylene group-containing monomer, It can be obtained by using a functional ethylenically unsaturated monomer and a monofunctional ethylenically unsaturated monomer containing an oxyalkylene group in combination with an acrylic resin, and further reducing the blending amount of the polyfunctional ethylenically unsaturated monomer. By using an acrylic resin composition, an acrylic pressure-sensitive adhesive obtained by polymerizing the monomer component and curing the resin composition by a curing process by irradiation with active energy rays or the like has high wettability, and thus an adherend. The present invention has been completed by finding that it has excellent adhesion to the substrate and is excellent in stain resistance to the adherend during peeling.

That is, the gist of the present invention is that an acrylic resin (A), an oxyalkylene group-containing unsaturated compound (B) containing one ethylenically unsaturated group, and an ethylenically unsaturated group containing two or more ethylenically unsaturated groups. Ethylene of ethylenically unsaturated compound (C) with respect to the total amount of ethylenically unsaturated groups of unsaturated compound (B) containing oxyalkylene group and ethylenically unsaturated compound (C) comprising saturated compound (C) The present invention relates to a method for producing an acrylic pressure-sensitive adhesive, wherein the acrylic resin composition [I] having a content (mol%) of the unsaturated unsaturated group of 60 mol% or less is cured.
Furthermore, it is related with the manufacturing method of the adhesive sheet obtained using this acrylic adhesive composition.

Since the acrylic pressure-sensitive adhesive of the present invention is excellent in wettability, it can be bonded to an adherend without air remaining, and is excellent in stain resistance to the adherend during peeling.
In addition, since the acrylic pressure-sensitive adhesive of the present invention can be cured by irradiation with active energy rays, the gel fraction can be quickly increased as compared with curing with only a crosslinking agent. Immediately after the work, the adhesive layer is appropriately cured by irradiation with active energy rays, so that the pressure-sensitive adhesive layer hardly protrudes when the pressure-sensitive adhesive sheet is wound around a roll, and can be easily processed.

  Furthermore, since a monomer containing an alkylene oxide structure containing a diester component as an impurity is used as a curable monomer upon irradiation with active energy rays, the monomer is copolymerized when an acrylic resin is produced by solution polymerization. Problems such as gelation that occur when used as a monomer are unlikely to occur, and a desired acrylic resin can be used in accordance with the application and process.

The present invention will be described in detail below, but these show examples of desirable embodiments.
In the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

First, the acrylic resin composition [I] of the present invention will be described.
The acrylic resin composition [I] of the present invention includes an acrylic resin (A), an oxyalkylene group-containing unsaturated compound (B) containing one ethylenically unsaturated group, and two or more ethylenically unsaturated groups. It contains an ethylenically unsaturated compound (C), a crosslinking agent (E), and a solvent.

Acrylic resin (A) used in the present invention are those obtained by copolymerizing a copolymerization component (meth) as a main component an acrylic acid alkyl ester monomer (a1), government functional group-containing monomer (a2) In addition, another copolymerizable monomer (a3) can be used as a copolymerization component. The acrylic resin (A) in the present invention uses the functional group-containing monomer (a2) as a copolymerization component, which becomes a cross-linking point of the acrylic resin (A), and the base resin or adherend. Furthermore the increasing the adhesion.

  As such a (meth) acrylic acid alkyl ester monomer (a1), the alkyl group usually has 1 to 20, particularly 1 to 12, more preferably 1 to 8, particularly 4 to 8 carbon atoms. 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) ac Rate, and the like. These can be used alone or in combination of two or more.

  Among such (meth) acrylic acid alkyl ester monomers (a1), n-butyl (meth) acrylate and 2-ethylhexyl (meth) are preferable in terms of copolymerizability, adhesive properties, ease of handling, and availability of raw materials. Acrylate is preferably used.

The functional group-containing monomer (a2), for example, hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomer, acetoacetyl group-containing monomer, isocyanate group-containing monomer is glycidyl group-containing monomers is Ru and the like, these Among them, hydroxyl group-containing monomer, carboxyl group-containing monomer need use in that it is efficient crosslinking reaction.

  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 (meta ) Acrylic acid hydroxyalkyl esters such as acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate and other caprolactone-modified monomers, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate and other oxyalkylene-modified monomers, and other 2-acrylic Primary hydroxyl group-containing monomers such as leuoxyethyl 2-hydroxyethylphthalic acid and N-methylol (meth) acrylamide; 2-hydroxypropyl (meth) acrylate Secondary hydroxyl group-containing monomers such as 2-hydroxybutyl (meth) acrylate and 3-chloro-2-hydroxypropyl (meth) acrylate; tertiary hydroxyl group-containing monomers such as 2,2-dimethyl 2-hydroxyethyl (meth) acrylate Can be mentioned.

  Among the hydroxyl group-containing monomers, a primary hydroxyl group-containing monomer is preferable in terms of excellent reactivity with a crosslinking agent. Furthermore, it is particularly preferable to use 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate because they have few impurities such as di (meth) acrylate and are easy to produce.

  In addition, as a hydroxyl-containing monomer used by this invention, it is also preferable to use a thing with the content rate of di (meth) acrylate which is an impurity 0.5% or less, and also 0.2% or less, especially 0 It is preferable to use 1% or less, specifically 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, and cinnamic acid. Among them, (meth) acrylic acid is preferably used.

  Examples of the amino group-containing monomer include t-butylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and the like.

  Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

  Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, allyl glycidyl (meth) acrylate, and the like.
These functional group-containing monomers (a2) may be used alone or in combination of two or more.

  Other copolymerizable monomers (a3) include, for example, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, and itacone. Examples thereof include monomers such as acid dialkyl esters, fumaric acid dialkyl esters, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, and dimethylallylvinylketone.

  Further, as other copolymerizable monomer (a3), phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, ethoxylated o-phenylphenyl ( Aromatic ring-containing monomers such as (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and styrene may be used.

  As a content ratio of the monomer component in the copolymer component, the (meth) acrylic acid alkyl ester monomer (a1) is preferably 30 to 100% by weight, particularly preferably 60 to 99% by weight, and further preferably 80 to 80%. The functional group-containing monomer (a2) is preferably 0 to 30% by weight, particularly preferably 0.1 to 15% by weight, and further preferably 0.5 to 10% by weight. The polymerization monomer (a3) is preferably 0 to 30% by weight, particularly preferably 1 to 20% by weight, and further preferably 2 to 10% by weight.

When the amount of the (meth) acrylic acid alkyl ester monomer (a1) is too small, for example, when used as an adhesive, the adhesive strength tends to be lowered.
When the amount of the functional group-containing monomer (a2) is too small, when a crosslinking agent is used, the crosslink density tends to decrease the stain resistance of the adherend, and when too large, the viscosity increases. The stability of the resin tends to decrease.
When there are too many other copolymerizable monomers (a3), the effects of the present invention tend to be difficult to obtain.

For the purpose of increasing the molecular weight, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate A compound having two or more ethylenically unsaturated groups such as divinylbenzene can also be used in combination.

  The acrylic resin (A) is produced by polymerizing the monomer components (a1) to (a3) described above. In this polymerization, conventional methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization are used. It can be performed by a known method. For example, a polymerization monomer such as a (meth) acrylic acid alkyl ester monomer (a1), a functional group-containing monomer (a2), another copolymerizable monomer (a3), or a polymerization initiator is mixed or dropped in an organic solvent. Polymerization is carried out at reflux or at 50 to 90 ° C. for 2 to 20 hours.

  Examples of the organic solvent used for the polymerization include aromatic hydrocarbons such as toluene and xylene, esters such as methyl acetate, ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, acetone, Examples include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  As the polymerization initiator used for such radical copolymerization, azo-based polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, which are usual radical polymerization initiators, benzoyl peroxide, lauroyl peroxide, Specific examples thereof include peroxide polymerization initiators such as -t-butyl peroxide and cumene hydroperoxide.

The weight average molecular weight of the acrylic resin (A), the a 800000-3000000, preferably 800,000 to 2,500,000, particularly preferably 800,000 to 2,000,000, particularly preferably from 80 to 1,800,000. If the weight average molecular weight is too small, the peelability and stain resistance of the adherend tend to be reduced. If the weight average molecular weight is too large, a large amount of dilution solvent is required, which tends to be undesirable in terms of coating properties and cost. .

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 10 or less, more preferably 7 or less, and particularly preferably 4 or less. preferable. When the degree of dispersion is too high, a large amount of low molecular components are contained, and the contamination resistance to the adherend tends to be lowered. The lower limit of the degree of dispersion is usually 2 from the viewpoint of production limit.

  Further, the glass transition temperature of the acrylic resin (A) is preferably −20 ° C. or less, particularly preferably −100 to −20 ° C., particularly preferably −90 to −30 ° C., and further preferably −80. When the glass transition temperature is too high, the wettability tends to decrease.

In addition, said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and it is a column in high performance liquid chromatography (The Japan Waters company "Waters 2695 (main body)" and "Waters 2414 (detector)"). : 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-divinylbenzene copolymer, filler The particle diameter is measured by using three series of 10 μm), and the same method can be used for the number average molecular weight. The degree of dispersion is determined from the weight average molecular weight and the number average molecular weight. The glass transition temperature is calculated from the following Fox equation.



Tg: Glass transition temperature of copolymer (K)
Tga: Glass transition temperature of monomer A homopolymer (K) Wa: Weight fraction of monomer A Tgb: Glass transition temperature of homopolymer of monomer B (K) Wb: Weight fraction of monomer B Tgn: Homogeneity of monomer N Glass transition temperature of polymer (K) Wn: weight fraction of monomer N (Wa + Wb +... + Wn = 1)

  As an oxyalkylene group-containing unsaturated compound (B) containing one ethylenically unsaturated group used in the present invention (hereinafter sometimes referred to as “oxyalkylene group-containing monofunctional compound (B)”). Although it is not particularly limited as long as it contains one ethylenically unsaturated group and an oxyalkylene group, it is represented by the following general formula (1) in terms of cost and availability. A compound is preferably used.

(In the formula, X is an alkylene group, n is an integer of 1 or more, A is a (meth) acryloyl group or alkenyl group, B is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or an acyl group.)

X in the general formula (1) is an alkylene group, among which an alkylene group having 1 to 10 carbon atoms is preferable, and in particular, an alkylene group having 1 to 4 carbon atoms such as an ethylene group, a propylene group, or a tetramethylene group. Is preferred.
In the case where n is a polyoxyalkylene group moiety having 2 or more, a homopolymer of the same oxyalkylene group may be used, or different oxyalkylene groups may be copolymerized randomly or in a block form.

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 any one of a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, and an acyl group.
Among these, a hydrogen atom, an alkyl group, and an aryl group are preferable, a hydrogen atom, an alkyl group, and a phenyl group are particularly preferable, and compatibility with an acrylic resin, price, and availability are more preferable. In this respect, an alkyl group is preferable, and a methyl group is particularly preferable.

  The alkyl group preferably has a relatively short carbon number, specifically 1 to 15 carbon atoms, particularly preferably 1 to 10 carbon atoms, further preferably 1 to 6 carbon atoms, specifically a methyl group or an ethyl group. Group and propyl group are preferable, and methyl group is particularly preferable. If the number of carbon atoms is too long, the compatibility with the acrylic resin tends to decrease.

  As the aryl group, those having 6 to 20 carbon atoms, preferably 6 to 15 carbon atoms are usually used, and specific examples include phenyl group, tolyl group, xylyl group, biphenyl group, naphthyl group and the like. Among these, a phenyl group is preferable.

  As the aralkyl group, those having 7 to 20 carbon atoms, preferably 7 to 15 carbon atoms are usually used, and specific examples include a benzyl group.

  As the acyl group, those having 2 to 10 carbon atoms, preferably 2 to 5 carbon atoms are usually used, and specific examples include an acetyl group.

  The alkyl group, aryl group, aralkyl group, and acyl group may have a substituent. As the substituent, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, Examples thereof include a hydroxyl group, an alkoxy group, an amino group, a sulfanyl group, an aryl group, and a heteroaryl group. In addition, when this substituent has a carbon atom, this carbon atom shall not be included in the carbon number prescribed | regulated in the description about each substituent of said B.

  N in the general formula (1) is an integer of 1 or more, preferably 1 to 500, particularly preferably 2 to 100, and more preferably 3 to 50. When there is too much value of n, there exists a tendency for compatibility with an acrylic resin to fall.

  Specific examples of the oxyalkylene group-containing monofunctional compound (B) include the following compounds.

[A: In the case of (meth) acryloyl group]
When B in the general formula (1) is a hydrogen atom and n = 1, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) Primary grades of acrylic acid hydroxyalkyl esters such as acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate Hydroxyl group-containing monomer; secondary hydroxyl group-containing monomer such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate; 2,2-dimethyl-2- Hydroxyethyl (meth) Examples include tertiary hydroxyl group-containing monomers such as acrylate, and when n is 2 or more, for example, polyethylene glycol derivatives such as polyethylene glycol mono (meth) acrylate, polypropylene glycol derivatives such as polypropylene glycol mono (meth) acrylate, Examples thereof include polyethylene glycol-polypropylene glycol-mono (meth) acrylate, poly (ethylene glycol-tetramethylene glycol) mono (meth) acrylate, poly (propylene glycol-tetramethylene glycol) mono (meth) acrylate, and the like.

  When B in the general formula (1) is an alkyl group, for example, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxy Ethyl (meth) acrylate, 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (Meth) acrylate, Octoxy polyethylene glycol-polypropylene glycol-mono (meth) acrylate, Lauroxy polyethylene glycol mono (meth) acrylate Stearoxypolyethylene polyethylene glycol mono (meth) acrylate aliphatic of (meth) acrylic acid ester.

  When B in the general formula (1) is an aryl group, examples thereof include phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and ethylene oxide-modified nonylphenol (meth) acrylate.

  When B in the general formula (1) is an aralkyl group, examples thereof include benzyloxyethyl (meth) acrylate and benzyloxydiethylene glycol (meth) acrylate.

  When B in the general formula (1) is an acyl group, examples thereof include acetoacetoxypolyethylene glycol monoacrylate.

[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, polyethylene glycol-polypropylene glycol-monoallyl ether, and the like.

Among these, those which are polyethylene glycol derivatives are preferable, and the number of moles of added ethylene oxide n is preferably 1 to 500, particularly preferably 2 to 100, and more preferably 3 to 50.
If the number of moles of added ethylene oxide n is too small, the wettability tends to decrease, and if it is too large, the compatibility with the acrylic resin tends to decrease.

  Moreover, as a weight average molecular weight of an oxyalkylene group containing monofunctional compound (B), 130-4000 are preferable normally, Especially 250-2000, Furthermore, 400-1000 are preferable. If the weight average molecular weight is too small, it tends to volatilize in the drying step, and if it is too large, it tends to crystallize or the compatibility with the acrylic resin tends to decrease.

  The content of the oxyalkylene group-containing monofunctional compound (B) is preferably 1 to 100 parts by weight, particularly preferably 3 to 70 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). Furthermore, 5 to 50 parts by weight are preferable. When the content is too large, the compatibility, moisture resistance, and substrate adhesion tend to be lowered, and when the content is too small, the wettability tends to be lowered.

  One molecule of the ethylenically unsaturated compound (C) containing two or more ethylenically unsaturated groups used in the present invention (hereinafter sometimes abbreviated as “polyfunctional unsaturated compound (C)”). Any ethylenically unsaturated monomer containing two or more ethylenically unsaturated groups may be used. For example, a bifunctional monomer, a trifunctional or higher monomer, a urethane (meth) acrylate compound, an epoxy (meth) acrylate A compound based on polyester or a polyester (meth) acrylate can be used. Among these, it is preferable to use an ethylenically unsaturated monomer and a urethane (meth) acrylate-based compound from the viewpoint of excellent curing rate and ultimate physical properties.

  The bifunctional monomer may be any monomer containing two ethylenically unsaturated groups. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, 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 1,6-hexanediol ethylene oxide modified 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 di (meth) acrylate, isocyanuric acid ethylene oxide-modified diacrylate, 2- (meth) acryloyloxyethyl acid phosphate diester It is done.

  The tri- or higher functional monomer may be any monomer containing three or more ethylenically unsaturated groups. For example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, Glycerin polyglycidyl ether poly (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate, ethylene oxide modified dipentaerythritol (Meth) acrylate, ethylene oxide modified dipentaerythritol hexa (meth) acrylate, ethylene oxide modified pentaerythritol tri (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, succinic acid modified pentaerythritol tri (meth) acrylate Etc.

  The urethane (meth) acrylate compound is a (meth) acrylate compound having a urethane bond in the molecule, a (meth) acrylic compound containing a hydroxyl group and a polyvalent isocyanate compound (if necessary, a polyol What is necessary is just to use what is obtained by making it react by a well-known general method, and what is necessary is just to use the thing of 300-4000 normally as the weight average molecular weight.

  The polyfunctional unsaturated compound (C) content is preferably 0.1 to 20 parts by weight, particularly 0.5 to 15 parts by weight with respect to 100 parts by weight of the acrylic resin (A). 1 to 10 parts by weight is more preferable. If the content is too large, the pressure-sensitive adhesive tends to be hard and the wettability tends to decrease. If the content is too small, the low molecular components increase and the contamination resistance to the adherend tends to decrease.

  In the present invention, the polyfunctionality relative to the total amount of the ethylenically unsaturated groups of the oxyalkylene group-containing monofunctional compound (B) and the polyfunctional unsaturated compound (C) in terms of ensuring the fluidity of the pressure-sensitive adhesive. The content (mol%) of the ethylenically unsaturated group of the polymerizable unsaturated compound (C) is required to be 60 mol% or less, preferably 5 to 55 mol%, particularly preferably 10 to 45 mol%, still more preferably. 20 to 35 mol%.

The content ratio of the ethylenically unsaturated group of the polyfunctional unsaturated compound (C) with respect to the total amount of the ethylenically unsaturated group of the oxyalkylene group-containing monofunctional compound (B) and the polyfunctional unsaturated compound (C) is If it is too large, the wettability of the pressure-sensitive adhesive tends to decrease, which is not preferable.
In addition, content of the ethylenically unsaturated group of the polyfunctional unsaturated compound (C) with respect to the total amount of the ethylenically unsaturated group of the oxyalkylene group-containing monofunctional compound (B) and the polyfunctional unsaturated compound (C) When the ratio is too small, the contamination resistance to the adherend tends to decrease.

In the present invention, the acrylic resin composition [I] containing the acrylic resin (A), the oxyalkylene group-containing monofunctional compound (B), and the polyfunctional unsaturated compound (C) as essential components is provided. The present invention provides an acrylic pressure-sensitive adhesive that is dried and then cured by irradiation with active energy rays and / or heating .

  About such a curing method, curing by active energy rays and / or heat (active energy ray irradiation and / or heating) is preferable from the viewpoint of cost, curing speed, work efficiency, and availability of an irradiation apparatus, The oxyalkylene group-containing monofunctional compound (B) and the polyfunctional unsaturated compound (C) are polymerized (polymerized) by active energy rays and / or heat and cured.

  When curing with the active energy ray and / or heat, the acrylic resin composition [I] further contains a polymerization initiator (D) at the time of irradiation with the active energy ray and / or upon heating. This is preferable in that the reaction can be stabilized.

Moreover, in this invention, in addition to said (A)-(C) component or (D) component as a method of hardening | curing said acrylic resin composition [I], the crosslinking agent (E) was further contained. are those, acrylic resin composition [I], a method to perform the curing by cross-linking agent, adhesive strength and holding power, preferable from the viewpoint of controlling the physical properties of tack or the like. Incidentally, A acrylic resin (A) is all SANYO having at least one functional group selected from hydroxyl and carboxyl groups, and a crosslinking agent this functional group curing is carried out by reacting.

In the present invention, it is possible to control physical properties such as adhesive strength, holding power, and tack by combining the curing with the active energy ray and / or heat (irradiation with active energy ray and / or heating) and the curing with a crosslinking agent. This is preferable in terms of resistance to contamination on the adherend.

  As the polymerization initiator (D), for example, various polymerization initiators such as a photopolymerization initiator (d1) and a thermal polymerization initiator (d2) can be used. It is preferable to use d1) in that it can be cured by irradiation with active energy rays such as ultraviolet rays for a very short time.

  When the photopolymerization initiator (d1) is used, the acrylic resin composition [I] is cured by irradiation with active energy rays, and when the thermal polymerization initiator (d2) is used, the acrylic resin composition is heated by heating. The product [I] is cured, but it is also preferable to use both in combination as necessary.

  Examples of the photopolymerization initiator (d1) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4- Acetophenones such as morpholinophenyl) butanone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl Ben such as ether Ins; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium Benzophenones such as chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy -3 Thioxanthones such as 4-dimethyl-9H-thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl- And acyl phosphine oxides such as pentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; In addition, as for these photoinitiators (d1), only 1 type may be used independently and 2 or more types may be used together.

  These auxiliary agents include triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid. Ethyl, 4-dimethylaminobenzoic acid (n-butoxy) ethyl, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone Etc. can be used in combination.

  Among these, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1- It is preferable to use phenylpropan-1-one.

  Examples of the thermal polymerization initiator (d2) include methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetyl acetate peroxide, 1,1-bis (t-hexyl peroxide). ) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1, 1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 1,1- Bis (t-butylperoxy) butane, 2,2-bis (4 -Di-t-butylperoxycyclohexyl) propane, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroper Oxide, t-butyl hydroperoxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-Butyl cumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexa Noyl peroxide, octanoyl per Oxide, lauroyl peroxide, stearoyl peroxide, succinic acid peroxide, m-toluoyl benzoyl peroxide, benzoyl peroxide, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butyl) (Cyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-s-butyl peroxydicarbonate, Di (3-methyl-3-methoxybutyl) peroxydicarbonate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-te Lamethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxy Pivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylper) Oxy) hexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t- Hexyl peroxyisopropyl monocarbonate, t-butyl peroxyisobutyrate t-butyl peroxymalate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2 -Ethylhexyl monocarbonate, t-butyl peroxyacetate, t-butyl peroxy-m-toluylbenzoate, t-butyl peroxybenzoate, bis (t-butylperoxy) isophthalate, 2,5-dimethyl-2,5 -Bis (m-toluylperoxy) hexane, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyallyl monocarbonate, t-butyltrimethylsilylper Oxide, 3,3 ', 4,4'-tetra Organic peroxide initiators such as (t-butylperoxycarbonyl) benzophenone and 2,3-dimethyl-2,3-diphenylbutane; 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1- [(1-cyano-1-methylethyl) azo] formamide, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′- Azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis (2-methyl- N-phenylpropionamidine) dihydrochloride, 2,2'-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] Hydride chloride, 2,2'-azobis [N- (4-hydrophenyl) -2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride 2,2'-azobis [2-methyl-N- (2-propenyl) propionamidine] dihydrochloride, 2,2'-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl) Lopan] dihydrochloride, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (5-hydroxy-3 , 4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane] dihydrochloride 2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] ] Propionamide], 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide], 2,2'-azobis [2-me Til-N- (2-hydroxyethyl) propionamide], 2,2'-azobis (2-methylpropionamide), 2,2'-azobis (2,4,4-trimethylpentane), 2,2'- Azobis (2-methylpropane), dimethyl-2,2-azobis (2-methylpropionate), 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis [2- (hydroxymethyl ) Propionitrile] and the like; and the like. In addition, only 1 type may be used independently for these thermal polymerization initiators, and 2 or more types may be used together.

  About content of the said polymerization initiator (D), 0.01-10 weight part with respect to 100 weight part of said acrylic resin (A), Especially 0.1-7 weight part, Furthermore, 0.5 It is preferably ˜5 parts by weight. If the content of the polymerization initiator (D) is too small, the curability tends to be poor and the physical properties tend to become unstable, and if it is too much, no further effect can be obtained. Moreover, it is preferable that it is 0.01-100 weight part with respect to a total of 100 weight part of a monofunctional aromatic compound (B) and a polyfunctional unsaturated compound (C), More preferably, it is 0.1-100 weight part. 20 parts by weight, particularly preferably 1 to 12 parts by weight.

  In the active energy ray irradiation, far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays and other electromagnetic waves, X rays, γ rays and other electromagnetic waves, as well as electron beams, proton rays, neutron rays, etc. can be used. Curing by ultraviolet irradiation is advantageous from the standpoint of availability of the device and price. In addition, when performing electron beam irradiation, it can harden | cure without using the said photoinitiator (d1).

As a light source for the ultraviolet irradiation, a high pressure mercury lamp, an electrodeless lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, or the like is used. In the case of the high-pressure mercury lamp, for example, it is performed under conditions of 5 to 3000 mJ / cm ² , preferably 10 to 1000 mJ / cm ² . Moreover, in the case of the said electrodeless lamp, it is performed on the conditions of 2-1500 mJ / cm < ² >, for example, Preferably 5-500 mJ / cm < ² >. The irradiation time varies depending on the type of the light source, the distance between the light source and the coating surface, the coating thickness, and other conditions, but may be usually from several seconds to several tens of seconds, and in some cases, may be a fraction of a second. On the other hand, in the case of the electron beam irradiation, for example, an electron beam having an energy in the range of 50 to 1000 Kev is used, and the irradiation amount is preferably 2 to 50 Mrad.

  Moreover, when using a thermal-polymerization initiator (d2) as said polymerization initiator (D), a polymerization reaction is started and advanced by heating. The treatment temperature and treatment time at the time of curing by heating vary depending on the type of the thermal polymerization initiator (d2) to be used, and are usually calculated from the half-life of the initiator, but the treatment temperature is usually The temperature is preferably 70 ° C to 170 ° C, and the treatment time is usually preferably 0.2 to 20 minutes, and particularly preferably 0.5 to 10 minutes.

  Examples of the crosslinking agent (E) include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, amine crosslinking agents, and metal chelate crosslinking agents. Among these, an isocyanate-based crosslinking agent is preferably used from the viewpoint of improving the adhesion to the substrate and the reactivity with the base polymer.

  Examples of the isocyanate crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and hexamethylene. Diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and polyisocyanate compounds thereof And adducts of a polyol compound such as trimethylolpropane, and burettes and isocyanurates of these polyisocyanate compounds.

  Examples of the epoxy crosslinking agent include bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. , Trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether and the like.

  Examples of the aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4. '-Bis (1-aziridinecarboxamide), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide) and the like can be mentioned.

  Examples of the melamine-based crosslinking agent include hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexaptoxymethyl melamine, hexapentyloxymethyl melamine, hexahexyloxymethyl melamine, and melamine resin. .

  Examples of the aldehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

  Examples of the amine-based crosslinking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resin, polyamide, and the like.

  Examples of the metal chelate-based crosslinking agent include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium, and zirconium. Can be mentioned.

  Moreover, these crosslinking agents (E) may be used independently and may use 2 or more types together.

  Usually, the content of the crosslinking agent (E) is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the acrylic resin (A). Particularly preferred is 0.1 to 5 parts by weight. If the amount of the crosslinking agent (E) is too small, the cohesive force is insufficient and the removability tends to be lowered, and if too large, the flexibility is lowered and the wettability tends to be lowered.

In addition, the acrylic resin composition [I] has a silane coupling agent, an antistatic agent, other acrylic pressure-sensitive adhesives, other pressure-sensitive adhesives, urethane resins, rosins, Rosin ester, hydrogenated rosin ester, phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, tackifier, colorant, filler, aging Conventionally known additives such as inhibitors, ultraviolet absorbers and functional dyes, and compounds that cause coloration or discoloration upon irradiation with ultraviolet rays or radiation can be blended.
In addition to the above additives, a small amount of impurities contained in the raw materials for producing the constituent components of the acrylic resin composition [I] may be contained.

  Examples of the silane coupling agent include an epoxy group-containing silane coupling agent, a (meth) acryloyl group-containing silane coupling agent, a mercapto group-containing silane coupling agent, a hydroxyl group-containing silane coupling agent, and a carboxyl group-containing silane coupling. Agents, amino group-containing silane coupling agents, amide group-containing silane coupling agents, isocyanate group-containing silane coupling agents, and the like.

  Examples of the antistatic agent include cationic antistatic agents of quaternary ammonium salts such as imidazolium salts and tetraalkylammonium sulfonates, aliphatic sulfonates, higher alcohol sulfates, and higher alcohol alkylene oxide additions. Anion-type antistatic agents such as sulfuric acid ester salts, higher alcohol phosphate salts, higher alcohol alcohol alkylene oxide adduct phosphate salts, potassium bis (fluorosulfonyl) imide, lithium bis (trifluorosulfonyl) imide and lithium chloride And alkali metal salts such as alkaline earth metal salts, higher alcohol alkylene oxide adducts, and polyalkylene glycol fatty acid esters.

  Thus, in the present invention, the acrylic resin composition [I] is obtained, and further, an acrylic pressure-sensitive adhesive obtained by curing the acrylic resin composition [I] is obtained. Hereinafter, the pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive will be described.

  The acrylic pressure-sensitive adhesive of the present invention is a masking / surface protecting adhesive, a double-sided tape adhesive, a medical adhesive, an optical member adhesive, a general label adhesive, a toy seal adhesive, and a decorative seal. Although it can be used for adhesives, uneven follow-up adhesives, etc., it can be effectively used as a surface protective adhesive sheet for touch panels, mobile phones, portable game machines and the like.

  The “sheet” in the present invention includes a film and a tape.

  There is no restriction | limiting in particular as a base material which provides acrylic resin composition [I], For example, polyester-type resins, such as a polyethylene naphthalate, a polyethylene terephthalate, a boribylene terephthalate, a polyethylene terephthalate / isophthalate copolymer; Polyethylene, polypropylene Polyolefin resins such as polymethylpentene; Polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene; Polyamides such as nylon 6, nylon 6, 6; Polyvinyl chloride, polyvinyl chloride / vinyl acetate Polymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; polymethyl methacrylate Acrylic resin such as polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate, etc .; polystyrene; polycarbonate; polyarylate; synthetic resin film or sheet such as polyimide, aluminum, copper, iron metal foil, fine paper, glassine paper And woven fabrics and nonwoven fabrics made of paper, glass fibers, natural fibers, synthetic fibers and the like. These base materials can be used as a single layer body or a multilayer body in which two or more kinds are laminated.

  Among these base materials, a synthetic resin film or sheet such as polyethylene terephthalate, polyethylene, or polypropylene is preferably used in consideration of price.

  In addition, in order to increase the anchoring property of the adhesive to the base material, the surface of the base material is treated to improve easy adhesion properties such as corona discharge treatment, plasma treatment, primer coating, degreasing treatment, and surface roughening treatment. Or an antistatic layer may be provided for further antistatic.

  Although the thickness of the said base material is not specifically limited, Generally it is 500 micrometers or less, Preferably it is 1-300 micrometers, More preferably, it is 5-200 micrometers, Especially preferably, the thickness of about 10-100 micrometers can be illustrated.

  The thickness of the acrylic resin composition [I] provided on the substrate is generally 1 to 200 μm, preferably 2 to 100 μm, more preferably 3 to 50 μm, and particularly preferably about 5 to 30 μm after drying. It can be illustrated. If the thickness is too thick, the adhesive tends to remain on the surface of the adherend when the pressure-sensitive adhesive sheet is peeled off from the adherend, and if it is too thin, the adhesive force to the adherend will be reduced and the pressure-sensitive adhesive sheet will be covered. After being bonded to the adherend, there is a tendency for the adherend and the pressure-sensitive adhesive sheet to be exposed to a high temperature or to be peeled off due to physical action.

  A separator can be laminated on the surface of the pressure-sensitive adhesive for the purpose of protecting the pressure-sensitive adhesive from contamination until the pressure-sensitive adhesive sheet is bonded to the adherend. As a separator, what carried out mold release processing of base materials, such as the synthetic resin film or sheet | seat illustrated above, paper, cloth, and a nonwoven fabric, can be used.

  When the acrylic resin composition [I] is provided on the substrate, it is usually applied as a solution of the acrylic resin composition [I], particularly to a viscosity suitable for application with a solvent, and then applied to the substrate. And drying is performed. Examples of the coating method include a direct coating method in which the solution-like acrylic resin composition [I] is directly applied to the substrate, or a substrate after the solution-like acrylic resin composition [I] is applied to the separator. Transfer coating method and the like.

  In the direct coating method, the acrylic resin composition [I] is applied to a base material, heated and dried, then irradiated with active energy rays, and then a separator is attached, or the acrylic resin composition is applied to the base material. Examples include a method of applying [I] and drying by heating, pasting a separator, and then irradiating with active energy rays. Coating is performed by methods such as roll coating, die coating, gravure coating, comma coating, and screen printing.

  On the other hand, in the transfer coating method, the acrylic resin composition [I] is applied to the separator, heated and dried, then irradiated with active energy rays, and then the base material is bonded, or the acrylic resin composition is applied to the separator. Examples include a method of applying the product [I], drying by heating, pasting the substrates together, and then irradiating with active energy rays. About the coating method, the method similar to direct coating can be used.

  There are no particular restrictions on the type of adherend to which the surface-protective pressure-sensitive adhesive sheet is applied. For example, metal foil, synthetic resin film or sheet, metal foil, paper, woven fabric, and non-woven fabric exemplified in the above substrate. In addition, a glass plate, a synthetic resin plate, and a metal plate are mentioned.

  About the gel fraction of the adhesive layer of the adhesive sheet obtained by the said method, it is preferable that it is 50 to 100%, Most preferably, it is 85 to 100%. When the gel fraction is too low, the amount of low molecular components increases, and the contamination resistance to the adherend tends to decrease.

  The initial adhesive strength of such an adhesive sheet is appropriately determined according to the material of the adherend. For example, when sticking to a SUS304BA board, it is preferable to have an adhesive strength of 0.01 N / 25 mm to 50 N / 25 mm, and when used for temporary protection (surface protection, masking) An adhesive force of 01 N / 25 mm to 5 N / 25 mm is preferable, and an adhesive force of 0.02 N / 25 mm to 1 N / 25 mm is particularly preferable.

  The 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 ° peel test is performed at a peel rate of 0.3 m / min, and the measured adhesive strength (N / 25 mm) is taken as the initial adhesive strength.

  Moreover, the high-speed peeling adhesive force of this adhesive sheet should just normally be 6 times or less of an initial stage adhesive force, It is preferable that it is especially 4 times or less, Furthermore, it is preferable that it is 2 times or less. For such high-speed peel adhesion, a test piece prepared by the same method as the initial adhesion 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.

  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.

First, various acrylic resins were prepared as follows. In addition, regarding the measurement of the weight average molecular weight of acrylic resin, dispersion degree, and glass transition temperature, it measured according to the above-mentioned method.
In addition, regarding the measurement of a viscosity, it measured according to the 4.5.3 rotational viscometer method of JISK5400 (1990).

[Preparation of Acrylic Resin (A)] (See Table 1)
[Acrylic resin (A-1)]
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 99.0 parts of butyl acrylate (a1), 1.0 part of 2-hydroxyethyl acrylate (a2), and ethyl acetate 68 Part, acetone 52 parts, and after heating to reflux, 0.012 part of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, reacted at reflux temperature for 3 hours, diluted with ethyl acetate, and acrylic Resin (A-1) solution (weight average molecular weight (Mw) 1.15 million, dispersity (Mw / Mn) 2.8, glass transition temperature -55 ° C., solid content 20.8%, viscosity 4,000 mPa · s (25 ° C)).

[Oxyalkylene group-containing unsaturated compound (B)]
The following were prepared as the oxyalkylene group-containing unsaturated compound (B-1).
Methoxypolyethylene glycol monoacrylate (manufactured by NOF Corporation, trade name “AME400”: molecular weight 451)

[Polyfunctional unsaturated compound (C)]
The following were prepared as the polyfunctional unsaturated compound (C-1).
Isocyanuric acid EO-modified triacrylate (product name “Aronix M-315” manufactured by Toa Gosei Co., Ltd .: molecular weight 423)

[Polymerization initiator (D)]
The following were prepared as the photopolymerization initiator (D-1).
A mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone in a mass ratio of 1: 1 (Ciba Specialty Chemicals, “Irgacure 500”)

Cross-linking agent (E-1)
55% ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethane Co., Ltd., Coronate L-55E)

[Examples 1 to 5, Comparative Example 1]
A resin composition to be a pressure-sensitive adhesive forming material for optical members is prepared by blending each of the blended components prepared and prepared as described above in the ratio shown in Table 2 below, and this is diluted with ethyl acetate. (Viscosity [500 to 10,000 mPa · s (25 ° C.)]) An acrylic resin composition solution was prepared.

The acrylic resin composition solution obtained above was applied to a polyethylene terephthalate (PET) film (thickness 38 μm) so that the thickness after drying was 25 μm, dried at 100 ° C. for 3 minutes, and an adhesive. A composition layer was formed. A polyester-based release sheet was bonded to the obtained pressure-sensitive adhesive composition layer, and the peak illuminance was 80 W / cm ² and the integrated exposure amount was 480 mJ / in with a high-pressure mercury lamp (“ECS-301G1” manufactured by Eye Graphics Co., Ltd.). UV irradiation was performed at cm ² (240 mJ / cm ² × 2 passes), and the film was aged at 40 ° C. for 10 days to obtain a PET film with an adhesive layer.

  Using the PET film with the pressure-sensitive adhesive layer thus obtained, the wettability and the bonding property were evaluated according to the methods shown below. These results are also shown in Table 2 below.

[Wettability]
After the obtained PET film with the pressure-sensitive adhesive layer is cut to 10 × 10 cm, the release sheet is peeled off, the PET film is allowed to stand on a glass plate, and then only the center is finger pressed to visually observe the speed at which the pressure-sensitive adhesive layer spreads. It was evaluated with.
(Evaluation)
○: Wet spread is very fast △: Wet spread is fast ×: Wet spread is slow

[Adhesion]
After the obtained PET film with the pressure-sensitive adhesive layer was cut to 10 × 10 cm, the release sheet was peeled off, the PET film was allowed to stand on a glass plate, and then only the center was finger pressed to evaluate how air escapes.
(Evaluation)
○: The pressure-sensitive adhesive spreads to the edge of the film with almost no air bubbles.
Δ: Some air bubbles are expected, but the adhesive spreads to the edge of the film.
X: It is easy to bite bubbles and the adhesive is likely to stop halfway.

Note) · The numerical value in () in the table in (A) to (E) is the weight part.

  Content ratio (mol%) of ethylenically unsaturated group of ethylenically unsaturated compound (C) to total amount of ethylenically unsaturated group of unsaturated compound (B) and ethylenically unsaturated compound (C) The pressure-sensitive adhesive layers of Examples 1 to 5 made of an acrylic resin composition having an amount of 60 mol% or less have excellent wettability and thus have excellent adhesion to an adherend, whereas It can be seen that the pressure-sensitive adhesive layer of Example 1 has low wettability and poor bonding properties because the crosslink density is too high and the mobility of the polymer molecules is low.

  The acrylic pressure-sensitive adhesive of the present invention has high wettability, excellent adhesion to the adherend, and stain resistance to the adherend. It can be usefully used as a pressure-sensitive adhesive for members, a pressure-sensitive adhesive for general labels, a pressure-sensitive adhesive for toys, a pressure-sensitive adhesive for decorative seals, and an uneven-tracking pressure-sensitive adhesive. It can be usefully used as a protective adhesive.

Claims (4)

Acrylic resin (A), oxyalkylene group-containing unsaturated compound (B) containing one ethylenically unsaturated group, ethylenically unsaturated compound (C) containing two or more ethylenically unsaturated groups, and a crosslinking agent (E) and a solvent, and the acrylic resin (A) is obtained by copolymerizing a (meth) acrylic acid alkyl ester monomer (a1) and a functional group-containing monomer (a2). (A2) contains at least one monomer selected from a hydroxyl group-containing monomer and a carboxyl group-containing monomer, and has a weight average molecular weight of 800,000 to 3,000,000, an oxyalkylene group-containing unsaturated compound (B) and an ethylenically unsaturated group. The content ratio (mol%) of the ethylenically unsaturated group of the ethylenically unsaturated compound (C) to the total amount of the ethylenically unsaturated group of the compound (C) is 60. ol% or less is acrylic resin composition [I] is, after being dried, the manufacturing method of the acrylic pressure-sensitive adhesive characterized by comprising been cured by active energy ray irradiation and / or heating. The production of an acrylic pressure-sensitive adhesive according to claim 1, wherein the oxyalkylene group-containing unsaturated compound (B) containing one ethylenically unsaturated group is a compound represented by the following general formula (1). Way .
Wherein X is an alkylene group, n is an integer of 1 or more, A is a (meth) acryloyl group or alkenyl group, B is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or an acyl group. is there.) The method for producing an acrylic pressure-sensitive adhesive according to claim 1 or 2, wherein the acrylic resin composition [I] contains a polymerization initiator (D). Method for producing a pressure-sensitive adhesive sheet characterized by containing an adhesive layer comprising an acrylic adhesive obtained by the production method of the acrylic pressure-sensitive adhesive according to any one of claims 1 to 3.