JP5484104B2 - Adhesive composition and adhesive sheet - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive composition. More specifically, the present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet excellent in transparency and step following ability.

In recent years, plastic films have been laminated to provide high functionality in the fields of mobile terminals such as mobile phones, touch panels that serve as input parts for personal computers, home appliances, etc., image display devices using liquid crystal or PDP, and other optical films. It is done to demonstrate. In the laminated film, films having various properties are laminated through an adhesive, but the adhesive composition used for each layer is also required to have various functions corresponding to the enhancement of the functionality of the laminated film. .

For touch panel applications, the adhesive composition is a double-sided tape for bonding a transparent plastic substrate such as polycarbonate and a conductive polyethylene terephthalate film (hereinafter referred to as PET film) or for bonding a conductive PET film and a hard coat film. Used in form.

For example, JP-A-2005-255877 (Patent Document 1) and JP-A-2005-15524 (Patent Document 2) disclose a pressure-sensitive adhesive composition obtained by blending an acrylic polymer having a specific structure and an oligomer, and the pressure-sensitive adhesive. A double-sided tape having a composition layer formed on both sides of a transparent substrate is disclosed. The pressure-sensitive adhesive composition layer is used for touch panels, and can suppress foaming and swelling of the pressure-sensitive adhesive due to gas generated from a polycarbonate plate even when used at high temperatures.

Such a pressure-sensitive adhesive composition obtained by blending an acrylic polymer and an oligomer is also used for applications such as bonding of optical members such as polarizing plates. For example, JP-A-2001-335767 (Patent Document 3). ) Discloses an adhesive composition having excellent adhesion to an adherend and excellent stress relaxation properties.

JP 2005-255877 A Japanese Patent Laid-Open No. 2005-15524 JP 2001-335767 A

However, in a mode that requires a layer configuration in which a pressure-sensitive adhesive layer is provided with a printed layer sandwiched in a touch panel application, a mode in which a configuration in which a pressure-sensitive adhesive layer is provided on a reflective surface having a complicated uneven shape in an optical application is required, etc. The composition has inadequate followability to the level difference, resulting in inconvenience that voids are generated in the concavo-convex portion and the end face of the printed layer.
In addition, there is a demand for thickening the pressure-sensitive adhesive layer, and there has also been a demand for a pressure-sensitive adhesive composition that can form a thick film of 50 μm or more without any trouble.

An object of the present invention is a pressure-sensitive adhesive composition that has sufficient durability and adhesiveness when used for an optical member such as a display device or a touch panel, and has no blistering or foaming. It is to provide a pressure-sensitive adhesive composition having followability to a step and good coatability.

As a result of diligent investigations to achieve the above object, the present inventors have found that a specific (meth) acrylic copolymer, a specific (meth) acrylic copolymer oligomer, and a crosslinking agent are mixed. The present inventors have found that the adhesive composition is a pressure-sensitive adhesive composition having well-balanced necessary physical properties such as durability, adhesiveness, step following ability, and transparency.

That is, the present invention
It contains a C2-C6 (meth) acrylic acid alkyl ester monomer of an alkyl group and a carboxyl group-containing monomer as a copolymerization component, and has a weight average molecular weight (Mw) of 500,000 to less than 900,000 and a glass transition temperature ( Tg) An acrylic copolymer (A) of −60 ° C. to −40 ° C., a carboxyl group-containing monomer as a copolymerization component, a weight average molecular weight (Mw) of 3000 or more and less than 10,000, and a glass transition temperature (Tg) of 10 A pressure-sensitive adhesive composition obtained by mixing an acrylic copolymer oligomer (B) at a temperature of from 110 ° C. to 110 ° C. and a crosslinking agent (C) having a functional group capable of reacting with the pressure-sensitive adhesive composition in the molecule. A pressure-sensitive adhesive composition in which the mixing ratio of the copolymer (A) and the acrylic copolymer oligomer (B) is 100/20 to 100/60 (weight ratio) is provided.

In the pressure-sensitive adhesive composition, the acrylic copolymer (A) is a monomer containing a carboxyl group with respect to 100 parts by weight of an alkyl group (meth) acrylic acid alkyl ester monomer having 2 to 6 carbon atoms. It is preferably an acrylic copolymer containing 1 to 10 parts by weight as a copolymer component, and the oligomer (B) is a carboxyl group based on 100 parts by weight of an acrylic monomer containing 50% by weight or more of t-butyl methacrylate. It is preferable that it is an acryl-type copolymer oligomer which contains 1-10 weight part of monomers containing as a copolymerization component, and a crosslinking agent (C) has 2 functional groups in a molecule | numerator which can react with an adhesive composition. It is preferable that the crosslinking agent has ˜5, and it is preferable that all the monomers containing a carboxyl group are acrylic acid.

The present invention also provides a double-sided pressure-sensitive adhesive tape and optical laminated sheet having a pressure-sensitive adhesive layer comprising a crosslinked product of the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition of the present invention is a mixture of an acrylic copolymer (A) having a specific composition, a specific acrylic copolymer oligomer (B) and a specific cross-linking agent (C).

[Acrylic polymer (A)]
The acrylic copolymer (A) has a copolymer component derived from an alkyl ester having 2 to 6 carbon atoms and an acrylate ester as a main copolymer component (for example, the acrylic copolymer (A)). And a total of 50% by weight or more) and a carboxyl group-containing monomer as a copolymerization component.

Specifically, the acrylic copolymer (A) that is particularly preferably used in the present invention includes the following monomers (a-1) and (a-2) as essential components:
(A-1) the following general formula (1),
H2C = C (R2) COOR1 (1)
(Wherein R1 represents a linear or branched alkyl group having 2 to 6 carbon atoms, and R2 represents a hydrogen atom or a methyl group)
(Meth) acrylic acid ester represented by (hereinafter, sometimes referred to as (meth) acrylic acid ester or simply monomer (a-1)), and

(A-2) A monomer having a carboxyl group in the molecule [hereinafter sometimes referred to as a carboxyl group-containing monomer (a-2)] is copolymerized, and these monomers are further used as necessary. Along with (a-1) and (a-2), the following monomer (a-3),

(A-3) Copolymerizable with the monomers (a-1) and (a-2), and a comonomer other than the monomers (a-1) and (a-2) [hereinafter, It is preferably a copolymer obtained by copolymerizing a monomer or a monomer (a-3).

The (meth) acrylic acid ester (a-1) of the above general formula (1) is a (meth) acrylic acid ester having a linear or branched alkyl group having 2 to 6 carbon atoms. Esters may be used alone or in combination of two or more. Ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) An acrylate etc. are mentioned, Among these, n-butyl (meth) acrylate is preferable. These (meth) acrylic acid esters may be used alone or in combination of two or more.

The copolymerization amount of the acrylic ester (a-1) is based on a total of 100% by weight of the monomer components (a-1) to (a-3) constituting the acrylic acid copolymer (A). In general, it should be in the range of 50 to 99% by weight, preferably 70 to 99% by weight. If the copolymerization amount of the acrylic ester (a-1) is not less than the lower limit value, it is preferable because the balance of adhesion, durability and followability to the step surface is good.

Specific examples of the carboxylxyl group-containing monomer (a-2) include, for example, a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, or an anhydride group-containing monomer thereof. it can. Of these, the use of acrylic acid is particularly preferred because of its compatibility with the acrylic ester (a-1) and compatibility with the acrylic copolymer oligomer (B).

The amount of copolymerization of the carboxyl group-containing monomer (a-2) is generally 1 to 10% by weight based on the total of 100% by weight of the monomer components (a-1) to (a-3). Preferably it is 2 to 6 weight%. If the copolymerization amount of the monomer (a-2) is less than or equal to the upper limit value, it is preferable because the followability to uneven surfaces and step surfaces is high. It is preferable because it is high.

In the present invention, specific examples of the comonomer (a-3) used as necessary together with the monomers (a-1) and (a-2) include those other than (a-1). (Meth) acrylic acid esters of, for example, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, tridecyl (meth) Acrylate, stearyl (meth) acrylate, oleyl (meth) acrylate, etc. (preferably methyl acrylate); methacrylic acid ester, etc. (preferably methyl methacrylate); saturated fatty acid vinyl ester, for example, vinyl formate, vinyl acetate, vinyl propionate , "Vinyl versatate" (trade name), etc. , For example, styrene, alpha-methyl styrene, vinyl toluene and the like; and vinyl cyanide monomer such as acrylonitrile, methacrylonitrile and the like; and the like.

Examples of the comonomer (a-3) include dimethyl malate, di-n-butyl malate, di-2-ethylhexyl malate, di-n-octyl malate, dimethyl fumarate, and di-n-butyl. It is also possible to use maleic acid or fumaric acid diesters such as fumarate, di-2-ethylhexyl fumarate, di-n-octyl fumarate;

Furthermore, the comonomer (a-3) is a monomer having at least one functional group in addition to one radical polymerizable unsaturated group in the molecule, if necessary, A monomer other than the monomer (a-2) (hereinafter sometimes referred to as a functional comonomer) can also be copolymerized.

Examples of such a functional comonomer include a functional group such as an amide group or a substituted amide group, an amino group or a substituted amino group, a hydroxyl group, a lower alkoxyl group, an epoxy group, a mercapto group, or a silicon-containing group. Monomers that have two or more radically polymerizable unsaturated groups in the molecule can be used as long as they do not affect the balance of adhesion, durability, and followability to step surfaces. it can.

Specific examples of these functional comonomers include acrylamide, methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, Nn-butoxymethyl acrylamide, Ni-butoxymethyl acrylamide, N Amide group or substituted amide group-containing monomers such as N, N-dimethylacrylamide and N-methylacrylamide; for example, aminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N- Amino group or substituted amino group-containing monomers such as dimethylaminoethyl methacrylate and N, N-diethylaminoethyl methacrylate;

For example, hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, methallyl alcohol, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate For example, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-n-butoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-n-butoxyethoxyethyl acrylate, 2-methoxyethyl Methacrylate, 2-ethoxyethyl methacrylate, 2-n-butoxyethyl methacrylate, 2-methoxyethoxyethyl methacrylate Acrylate, 2-ethoxyethoxy ethyl methacrylate, 2-n-butoxyethoxy ethyl methacrylate, methoxy polyethylene glycol monoacrylate, lower alkoxyl group-containing monomers such as methoxy polyethylene glycol monomethacrylate;

For example, epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, glycidyl methallyl ether; mercapto group-containing monomers such as allyl mercaptan;

For example, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltri-i-propoxysilane, vinyltri-n-butoxysilane, vinyltris (2-methoxyethoxy) silane , Vinyltris (2-hydroxymethoxyethoxy) silane, vinyltriacetoxysilane, vinyldiethoxysilanol, vinylethoxysiladiol, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, allyltrimethoxysilane, allyltri Ethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropyltris (2-meth Monomers having silicon-containing groups such as (ciethoxy) silane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3-acryloxypropyldimethylmethoxysilane, 2-acrylamidoethyltriethoxysilane; And the like.

The copolymerization amount of these comonomers (a-3) is generally 0 to 30% by weight, preferably based on 100% by weight of the monomer components (a-1) to (a-3). It should be in the range of 0 to 20% by weight, more preferably 1 to 10% by weight. If the copolymerization amount of the monomer (a-3) is less than or equal to the upper limit value, it is preferable because the balance of adhesion, durability, and followability to a step surface is good.

Furthermore, as the comonomer (a-3), a monomer having two or more radically polymerizable unsaturated groups in the molecule can be copolymerized as necessary. Examples of such comonomer (a-3) include divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, ethylene glycol di (meth) acrylate, 1,2-propylene glycol di (meth). ) Acrylate, 1,3-propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylol Propane tri (meth) acrylate, allyl (meth) acrylate, and the like are included. The amount of the monomer having two or more radically polymerizable unsaturated groups in the molecule can be used within a range that does not impair the excellent effects of the present invention, such as 0.5% by weight or less. it can.

The acrylic copolymer (A) used in the present invention needs to have a weight average molecular weight (Mw) in the range of 500,000 to less than 900,000, preferably in the range of 600,000 to less than 800,000. There should be. If the weight average molecular weight (Mw) is too low, such as less than the lower limit, bubbles are generated due to insufficient cohesive force and the like, which is not preferable. On the other hand, if it exceeds the upper limit value and is too high, it is not preferable because the followability to uneven surfaces and step surfaces is low.

The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic copolymer (A) suitably used in the present invention is generally 20 or less, preferably in the range of 5-15. There should be. If the value of Mw / Mn is less than or equal to the upper limit value, it is preferable because inconvenience associated with insufficient cohesive force is unlikely to occur.

In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of an acrylic copolymer are the values measured by the following method.

Method for measuring average molecular weight (Mw and Mn):
It measures according to following (1)-(3).
(1) An acrylic copolymer solution is applied to release paper and dried at 100 ° C. for 2 minutes to obtain a film-like acrylic copolymer.
(2) The film-like acrylic copolymer obtained in the above (1) is dissolved in tetrahydrofuran so as to have a solid content of 0.2%.
(3) The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic copolymer are measured using gel permeation chromatography (GPC) under the following conditions.

(conditions)
GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
Column: 4 TSK-GEL GMHXL Mobile phase solvent used: Tetrahydrofuran flow rate: 0.6 ml / min
Column temperature: 40 ° C

The acrylic copolymer (A) used in the present invention is also required to have a glass transition temperature (TgA) of −40 ° C. or lower, preferably −50 ° C. or lower. If TgA exceeds this temperature and is too high, the adhesive strength to the support substrate becomes too high, so that the reworkability is lowered, which is not preferable.

In addition, the glass transition temperature (Tg) of the acrylic copolymer in this specification means the molar average glass transition temperature calculated | required by the following calculations.

Calculation of glass transition temperature (Tg):
Here, Tg1, Tg2,..., And Tgn are the glass transition temperatures of the respective homopolymers of component 1, component 2,..., And component n, and are converted into absolute temperatures (° K). calculate. m1, m2,... and mn are mole fractions of the respective components.

The “glass transition temperature (Tg) of the homopolymer” referred to herein includes L.P. E. The glass transition temperatures of the monomers described in Nielsen, translated by Nojiharu Onoki, “Mechanical properties of polymers”, pages 11 to 35, are applied.

[Acrylic copolymer oligomer (B)]

The pressure-sensitive adhesive composition for a touch panel of the present invention comprises an acrylic copolymer oligomer (B) together with the acrylic copolymer (A) described above.

The acrylic copolymer oligomer (B) is similar to the acrylic copolymer (A) in that the repeating unit derived from an acrylic ester and a methacrylic ester is the main component, for example, an acrylic copolymer oligomer. Based on (B), it contains a total of 50% by weight or more, including the following monomers (b-1) and (b-2) as copolymerization components, and its glass transition temperature: (TgB) is in the range of 10 to 110 ° C.

Specifically, the acrylic copolymer oligomer (B) particularly preferably used in the present invention includes the following monomers (b-1) and (b-2) as essential components:
(B-1) The following general formula (1),
H2C = C (R2) COOR1 (1)
(Wherein R1 represents a linear or branched alkyl group having 2 to 6 carbon atoms, and R2 represents a hydrogen atom or a methyl group)
(Meth) acrylic acid ester represented by (hereinafter, sometimes referred to as (meth) acrylic acid ester or simply monomer (b-1)), and

(B-2) A monomer having a carboxyl group in the molecule [hereinafter sometimes referred to as a carboxyl group-containing monomer (b-2)] is included as a copolymerization component.

The glass transition temperature (TgB) of the acrylic copolymer oligomer which is the component (B) of the present invention is
It is necessary to be in the range of 10 to 110 ° C, and preferably in the range of 50 to 90 ° C. If TgB is not more than the upper limit temperature, it is preferable because durability at a high temperature is high. On the other hand, if it is not less than the lower limit temperature, it is preferable because adhesiveness is high.

The monomer (b-1), which is an essential monomer constituting the acrylic copolymer oligomer (B), is specifically a single monomer in the acrylic copolymer (A) that is the component (A). Although what is used with a monomer (a-1) can be used, from a viewpoint of adhesiveness, durability, and transparency, t-butyl methacrylate (tBMA), i-butyl methacrylate (iBMA), n- The use of butyl methacrylate (nBMA) is preferred, and the use of t-butyl methacrylate (tBMA) is most preferred from the viewpoint of adhesion and durability at high temperatures.

The amount of the monomer (b-1) used depends on the type of the monomer (b-1) itself and the type of the monomer (b-2) described later, and the glass transition temperature range and SP. Although it can be appropriately selected so as to satisfy the value, it is generally based on a total of 100% by weight of the monomers (b-1) and (b-2) constituting the acrylic copolymer oligomer (B). And 50 to 99% by weight, more preferably 70 to 90% by weight. If the amount used is greater than or equal to the lower limit, the adhesiveness, durability at high temperatures, and compatibility with the acrylic copolymer (A) are preferably high, while if the amount used is less than or equal to the upper limit, the uneven surface・ Following step surface, wettability to adherend, and high compatibility with acrylic copolymer (A), which is preferable.

The amount of the monomer (b-2) used can be appropriately selected depending on the type of the monomer (b-2) and the type of the monomer (b-1). 1 to 10% by weight based on the total of 100% by weight of the monomers (b-1) and (b-2) constituting the acrylic copolymer oligomer (B), and further 3 to 8% by weight. Preferably there is. If the amount used is greater than or equal to the lower limit value, it is preferable because the adhesiveness is high. On the other hand, if it is equal to or less than the upper limit value, transparency (HAZE) after the durability test is high, and the decrease in cohesive force is small.
Specific examples of the carboxylxyl group-containing monomer (b-2) include, for example, a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, or an anhydride group-containing monomer thereof. it can. Of these, the use of acrylic acid is particularly preferred because of its compatibility with the acrylic ester (b-1) and compatibility with the acrylic copolymer (A).

The acrylic copolymer oligomer (B) used in the present invention is required to have a weight average molecular weight (Mw) measured in accordance with the above “Method for Measuring Weight Average Molecular Weight” in the range of 3000 to 10,000, preferably Is preferably in the range of 4000-6000. If the molecular weight is equal to or higher than the lower limit value, it is preferable because the adhesiveness is high, and a decrease in reworkability and cohesive force due to low molecular components is small. It is preferable because of its good properties and high wettability to the adherend.

The difference ΔSP (= SPB−SPA) between the solubility parameter (SPB) of the acrylic copolymer oligomer (B) used in the present invention and the solubility parameter (SPA) of the acrylic copolymer (A) is 1.0 or less, more preferably 0.5 or less. If the difference ΔSP in the solubility parameter is less than or equal to the upper limit value, the compatibility between the acrylic copolymer (A) and the acrylic copolymer oligomer (B) is not lowered, so that transparency can be maintained, which is preferable.

The solubility parameter (SP value) here is an index representing the tendency of solubility of a substance. The SP value is measured or calculated by various methods, and is described in detail, for example, in “SP Value Basics / Applications and Calculation Methods” by Hideki Yamamoto: (2005).

The SP value of the polymer was calculated by the Fedor estimation method of the following formula calculated based on the cohesive energy density E and the molar molecular volume V.
SP = [ΣEcoh / ΣV] 1/2

Regarding the SP value of the copolymer, the solubility parameter was obtained by adding each SP value of the constituent monomers to each of the constituent mole fractions.

In the pressure-sensitive adhesive composition of the present invention, the acrylic copolymer oligomer (B) described above is 20 to 60 parts by weight, preferably 30 to 100 parts by weight of the acrylic copolymer (A). It contains 40 parts by weight. If the amount of the component (B) used is less than the upper limit value, it is preferable because there is little decrease in cohesive force and compatibility. On the other hand, if the lower limit value is greater than this value, followability to uneven surfaces and step surfaces is preferable. It is preferable because of its high adhesiveness and heat resistance.

The acrylic copolymer (A) and the acrylic copolymer oligomer (B) used in the present invention are not particularly limited to the polymerization method, and include solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, and the like. In the production of the pressure-sensitive adhesive composition of the present invention using a mixture of copolymers obtained by polymerization, the treatment process is relatively simple and can be carried out in a short time. It is preferable to polymerize by polymerization.

In solution polymerization, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent used as needed are generally charged in a polymerization tank, and stirred in a nitrogen stream or at the reflux temperature of the organic solvent. The reaction is performed by heating for several hours. In this case, at least a part of the organic solvent, the monomer, the polymerization initiator and / or the chain transfer agent may be sequentially added.

Examples of the organic solvent for polymerization include aromatics such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha. Hydrocarbons; for example, aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil; , Ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate and the like; for example, acetone, methyl ethyl ketone, methyl-i- Keto such as butyl ketone, isophorone, cyclohexanone, methylcyclohexanone Kind;

For example, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, i -Alcohols such as propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol; These organic solvents can be used alone or in admixture of two or more.

Among these organic solvents for polymerization, when the acrylic copolymer (A) is polymerized, it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction, for example, esters and ketones. In view of the solubility of the acrylic copolymer (A) and the ease of the polymerization reaction, use of ethyl acetate, methyl ethyl ketone, acetone, or the like is preferable. Moreover, when manufacturing an acrylic copolymer oligomer (B), it is preferable to use the organic solvent which is easy to produce chain transfer, for example, ketones and aromatic hydrocarbons. In particular, toluene, methyl ethyl ketone, and the like are preferable from the viewpoint of ease of polymerization reaction.

As said polymerization initiator, it is possible to use the organic peroxide, an azo compound, etc. which can be used by normal solution polymerization.

Examples of such organic peroxides include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonate, di-2- Ethylhexylperoxydicarbonate, t-butylperoxybivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-amylperoxycyclohexyl) ) Propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, 2,2-bis ( 4,4-di-t-butylperoxycyclohexyl) butane, , 2-bis (4,4-di-t-octylperoxycyclohexyl) butane, and examples of the azo compound include 2,2′-azobis-i-butylnitrile and 2,2′-azobis-2. , 4-dimethylvaleronitrile, 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, and the like.

Among these organic peroxides, when the acrylic copolymer (A) is polymerized, it is preferable to use a polymerization initiator that does not cause a graft reaction during the polymerization reaction, and particularly preferably an azobis type. The amount used is usually 0.01 to 2 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the total amount of monomers. In the case of producing the acrylic copolymer oligomer (B), although it varies depending on the reaction temperature, a polymerization initiator having a low 10-hour half-life temperature is preferable, for example, a 10-hour half-life temperature is preferably 80 ° C. or less, preferably Is more preferably a polymerization initiator at 70 ° C. or lower. The amount of use is usually 0.1 to 15 parts by weight, preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the total amount of monomers.

Further, in the production of the acrylic copolymer (A) used in the present invention, it is normal not to use a chain transfer agent, but it is used as necessary within the range that does not impair the purpose and effect of the present invention. It is possible to do. On the other hand, when producing the acrylic copolymer oligomer (B), the polymerization is often carried out in the presence of a chain transfer agent.

Examples of such chain transfer agents include cyanoacetic acid; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; α-methylstyrene, anthracene, Aromatic compounds such as phenanthrene, fluorene, 9-phenylfluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone, 2 Benzoquinone derivatives such as 1,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane;

Halogenated hydrocarbons such as carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, 3-chloro-1-propene; Aldehydes such as chloral and furaldehyde: alkyl mercaptans having 1 to 18 carbon atoms; aromatic mercaptans such as thiophenol and toluene mercaptan; mercaptoacetic acids and alkyl esters having 1 to 10 carbon atoms of mercaptoacetic acid; 12 hydroxyalkyl mercaptans; terpenes such as binene and terpinolene;

When producing the acrylic copolymer (A) used in the present invention, it is preferable not to use a chain transfer agent, and when producing the acrylic copolymer oligomer (B), the above chain is used. Of the transfer agents, preferably, mercaptans and halogenated hydrocarbons can be used in an amount of 0.005 to 10.0 parts by weight based on 100 parts by weight of the total amount of monomers.

The polymerization temperature is generally in the range of about 30 to 180 ° C., preferably 50 to 150 ° C., but when the acrylic copolymer (A) is produced, it is preferably 50 to 90 ° C., more preferably 50 It is -80 degreeC, When manufacturing an acrylic copolymer oligomer (B), Preferably it is 70-110 degreeC, More preferably, it is 80-100 degreeC.

When an unreacted monomer is contained in a polymer obtained by a solution polymerization method or the like, it can be purified by a reprecipitation method using methanol or the like in order to remove the monomer.

The pressure-sensitive adhesive composition for a polarizing film of the present invention reacts with the acrylic copolymer (A) as an essential component to crosslink with the acrylic copolymer (A) and the acrylic copolymer oligomer (B). It comprises a crosslinking agent (C) having two or more, preferably 2 to 5, functional groups capable of forming a structure.

The crosslinking agent (C) is not particularly limited as long as it reacts with the acrylic copolymer (A) to form a crosslinked structure, and is not limited to polyisocyanate compounds, polyepoxy compounds, polyaziridine compounds. Melamine formaldehyde condensate, metal salt, metal chelate compound and the like. Among these crosslinking agents, use of a polyisocyanate compound, a polyaziridine compound and / or a polyepoxy compound is possible from the viewpoints of adhesion to a polarizing film, stability after blending with an acrylic copolymer (A), and the like. preferable. These crosslinking agents (C) can be used alone or in combination of two or more.

Examples of the polyisocyanate compound include aromatic polyisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate; for example, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenation of the aromatic polyisocyanate compound. Polyisocyanate compounds derived from various polyisocyanates such as aliphatic or alicyclic polyisocyanates such as products; dimers or trimers of these polyisocyanates, or adducts of these polyisocyanates and polyols such as trimethylolpropane Can be mentioned.

Among these polyisocyanate compounds, hexamethylene diisocyanate or xylylene dimer or trimer, or adducts of hexamethylene diisocyanate or xylylene diisocyanate and a polyol such as trimethylolpropane, etc. Polyisocyanate compounds derived from isocyanate are preferred.

These polyisocyanate compounds are, for example, “Coronate HX”, “Coronate HL-S”, “Coronate 2234” (manufactured by Nippon Polyurethane Co., Ltd.), “Desmodur N3400” (manufactured by Sumitomo Bayer Urethane Co., Ltd.), “ "Duranate E-405-80T", "Duranate TSE-100" (manufactured by Asahi Kasei Kogyo Co., Ltd.), "Takenate D-110N", "Takenate D-120N", "Takenate M-631N" [Mitsui Takeda Chemical Co., Ltd. A product commercially available under a trade name such as “made by]” can be preferably used.

As the polyaziridine compound, a reaction product of a polyisocyanate compound and ethyleneimine can be used, and as the polyisocyanate compound, those exemplified above can be used. Also known is a compound obtained by adding ethyleneimine to a polyvalent ester of a polyol such as trimethylolpropane or pentaerythritol and an α, β-unsaturated carboxylic acid such as (meth) acrylic acid. (C) can be used.

Examples of such polyaziridine compounds include N, N′-hexamethylenebis (1-aziridinecarboxamide), methylenebis [N- (1-aziridinylcarbonyl) -4-aniline], tetramethylolmethanetris ( β-aziridinylpropionate), trimethylolpropane tris (β-aziridinylpropionate) and the like. Among these, for example, “TAZO”, “TAZM” [manufactured by Mutual Yakuhin Co., Ltd.] , "Chemitite PZ-33" (manufactured by Nippon Shokubai Co., Ltd.), etc., can be suitably used.

Examples of the polyepoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl. Ether, 1,6-hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcin diglycidyl ether, 2,2 -Dibromoneopentyl glycol diglycy Ether, trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate, tris (glycidoxyethyl) isocyanurate, 1 , 3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine and the like.

Among these polyepoxy compounds, polyepoxy compounds containing three or more epoxy groups are preferable, and among them, tris (glycidyl) isocyanurate, tris (glycidoxyethyl) isocyanurate, 1,3-bis (N, N-glycidyl) More preferred is the use of a polyepoxy compound such as aminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, The use of N, N, N ′, N′-tetraglycidyl-m-xylylenediamine is particularly preferred.

As these polyepoxy compounds, for example, those commercially available under trade names such as “TETRAD-C” and “TETRAD-X” (manufactured by Mitsubishi Gas Chemical Co., Inc.) can be suitably used.

The amount of these crosslinking agents (C) used is usually in the range of 0.001 to 10 parts by weight, preferably 0.005 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer (A). . If the amount of the cross-linking agent (C) used is too small and less than the lower limit value, bubbles associated with insufficient cohesive force and the like are likely to occur, and the contamination of the adherend surface is reduced. If the amount is too much, it is not preferable because the followability to uneven surfaces and step surfaces and the wettability to the adherend are reduced due to excessive cohesion.

In particular, when the polyisocyanate compound is used as the crosslinking agent (C), the amount used is 0.15 to 3 parts by weight as an active ingredient of the polyisocyanate compound based on 100 parts by weight of the acrylic copolymer (A). Is preferably in the range of 0.5 to 2 parts by weight. The amount of the polyaziridine compound used is 0.001 to 0.1 parts by weight, particularly 0.001 as an active ingredient of the polyaziridine compound, based on 100 parts by weight of the acrylic copolymer (A). It is preferable to be in the range of ˜0.05 parts by weight. Further, the amount used when using the polyepoxy compound is 0.005 to 0.3 parts by weight, particularly 0.01 to 0.3 parts by weight as an active ingredient of the polyepoxy compound based on 100 parts by weight of the acrylic copolymer (A). The range is preferably 0.2 parts by weight. Depending on the type of the reactive functional group of the cross-linking agent (C), the preferred use amount for the reactive functional group of the acrylic copolymer is determined.

Moreover, as above-mentioned, a crosslinking agent (C) can be used in combination of 2 or more types, You may combine the said polyisocyanate compound and a polyaziridine compound or a polyisocyanate compound and a polyepoxy compound. In that case, the polyisocyanate compound, the polyaziridine compound, and the polyepoxy compound can be appropriately selected within the above-mentioned usage amount ranges, but preferably, the polyisocyanate compound: polyaziridine compound are all in an active ingredient weight ratio. = 1 to 500: 1, particularly 10 to 300: 1, or polyisocyanate compound: polyepoxy compound = 1 to 300: 1, particularly 10 to 100: 1.

In addition to the acrylic copolymer (A), acrylic copolymer oligomer (B), and cross-linking agent (C) described above, the pressure-sensitive adhesive composition of the present invention includes a pressure-sensitive adhesive composition as necessary. It is preferable that the blending ratio is a range that does not increase the haze value, for example, a weathering stabilizer, tackifier, plasticizer, softener, dye, pigment, inorganic filler, etc. Can be appropriately blended within a range satisfying the above.

The pressure-sensitive adhesive composition of the present invention has a gel content of 30 after the crosslinked structure is formed between the acrylic copolymer (A), the acrylic copolymer oligomer (B), and the crosslinking agent (C). It is necessary to be -70% by weight, and 40-60% by weight is particularly preferable. If the gel content is equal to or higher than the lower limit, bubbles associated with insufficient cohesive force are unlikely to occur, and reworkability is high, and if it is equal to or lower than the upper limit, followability to uneven surfaces and step surfaces is high. preferable. The gel content is measured by the following method.

Measurement of gel content of pressure-sensitive adhesive composition:
It measures according to following (1)-(7).
(1) A pressure-sensitive adhesive composition solution is applied onto release paper, air-dried at room temperature for 30 minutes, and then dried at 100 ° C. for 5 minutes to form a film-like pressure-sensitive adhesive layer.
(2) The pressure sensitive adhesive layer is cured at 23 ° C. and relative humidity 65% for 10 days.
(3) About 1 g of the film-like pressure-sensitive adhesive layer is applied to a precisely weighed glass rod (diameter 5 mm × 30 mm) and dried in a desiccator for 1 hour. Thereafter, the weight is accurately measured with a precision balance to prepare a sample.
(4) Put the sample obtained in (3) into a cylindrical filter paper (No. 84).
(5) About 100 ml of solvent (ethyl acetate) is put into a 200 ml round bottom flask accurately weighed by a Soxhlet extractor, and Soxhlet extraction is carried out for 4 hours.
(6) After cooling, the solvent (ethyl acetate) in the round bottom flask is volatilized by a rotary evaporator, and then the round bottom flask containing the above extract is dried at 100 ° C. for 3 hours and in a desiccator for 1 hour. Thereafter, the weight is accurately measured with a precision balance.
(7) Calculate the gel content by the following formula.
Gel content (% by weight) = 100 − [(A−B) / (C−D)] × 100
However, A is the weight (g) of the round bottom flask after extraction, B is the weight (g) of the round bottom flask, C is the weight (g) of the sample, and D is the weight (g) of the glass rod.

This invention also provides the double-sided adhesive tape which has an adhesive layer which consists of a crosslinked body of the said adhesive composition layer. The double-sided pressure-sensitive adhesive tape of the present invention can be produced by applying a pressure-sensitive adhesive solution comprising a crosslinked product of the pressure-sensitive adhesive composition onto a release paper and drying it.

The double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer composed of a crosslinked product of the pressure-sensitive adhesive composition layer of the present invention includes a type with a base material having a pressure-sensitive adhesive layer on both sides of a transparent base material and a type without a base material.
This type of double-sided pressure-sensitive adhesive tape with a base material is applied with a pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer on one side of a transparent base material and dried, and the other side of the pressure-sensitive adhesive layer is formed on the other side. A method of applying an adhesive for drying. The transparent adhesive layer formed on the release liner can be produced by a method of transferring to a transparent substrate.

Although the thickness of a transparent base material is not specifically limited, From the point of durability, it is good in the range of about 5-100 micrometers, for example.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably in the range of, for example, about 50 to 175 μm from the viewpoint of followability to uneven surfaces and step surfaces.

The double-sided pressure-sensitive adhesive tape needs to be transparent. For example, the total light transmittance (JIS K 7361) in the visible light wavelength region is 85% or more, preferably 90% or more.

Moreover, the haze (JIS K 7136) of the double-sided pressure-sensitive adhesive tape is 1.0% or less, preferably 0.5% or less.

Application of the pressure-sensitive adhesive composition to the substrate or release sheet can be carried out by a usual method such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater or the like.

The crosslinked product of the pressure-sensitive adhesive composition of the present invention can also be used for optical laminated sheets such as a sheet-like optical member having a pressure-sensitive adhesive layer because of its transparency, durability, and step following ability.
The laminated sheet is a sheet in which a layer (adhesive layer) composed of a crosslinked product of the above-mentioned pressure-sensitive adhesive composition is provided on at least one side of a base sheet. Examples of the base sheet include glassine paper, coated paper, Paper substrates such as cast-coated paper, laminated papers laminated with a thermoplastic resin such as polyethylene on these paper substrates, or polyester films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polymethylpentene, etc. Examples thereof include plastic films such as polyolefin films, polycarbonate films, and cellulose acetate films, and laminated sheets containing these films.

Although there is no restriction | limiting in particular as thickness of a base material sheet, Usually, it is about 20-150 micrometers, A suitable thing is selected according to the use. In this case, a release sheet is provided on the pressure-sensitive adhesive layer as necessary.

The optical laminated sheet of the present invention is not particularly limited, but includes, for example, a polarizing plate, a phase difference plate, an antireflection plate, a viewing angle widening film, etc. Among these, a structural surface having a step in particular. It is suitable for a sheet that needs to be laminated.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples. Various characteristics in each example were evaluated according to the following methods.

(1) Preparation of test film Cast coating is performed on a release surface of a polyethylene terephthalate film (thickness: 100 μm) that has been subjected to release treatment on one side so that the thickness after drying is about 50 μm. The film was dried by heating at 100 ° C. for 2 minutes, and a polyethylene terephthalate film (thickness: 38 μm) having a release treatment (heavy peeling) on the other side was pressure-bonded through a pressure nip roll and bonded together. Thereafter, curing was carried out for 7 days under conditions of 23 ° C. and 50% relative humidity to obtain a double-sided pressure-sensitive adhesive film without a base material having a pressure-sensitive adhesive layer on both sides.

(2) Before the adhesive strength measurement, one of the sample films prepared according to the item (1) is peeled off, and a polyethylene terephthalate film (thickness: 100 μm) [trade name: A4100; manufactured by Toyobo Co., Ltd.] -After crimping and bonding through a sheet, cut into 25 mm x 150 mm, and this film piece is crimped to a glass plate with a thickness of 2 mm using a table laminating machine to obtain a test sample. The sample is allowed to stand under conditions of 23 ° C. and 50% RH for 24 hours, and then the adhesive force at 180 ° peeling (peeling speed: 300 mm / min) is measured. The evaluation criteria are as follows.
○: Adhesive force 30 N / 25 mm or more Δ: Adhesive force 25 N / 25 mm or more and less than 30 N / 25 mm x: Adhesive force 25 N / 25 mm or less

(3) HAZE
A test sample is prepared in the same manner as in the previous section (2) except that a cut film piece of 80 mm × 150 mm (long side) is used, and this film piece is formed on a glass plate having a thickness of 2 mm using a table laminator. Crimp to make a test sample. The sample was allowed to stand for 24 hours under conditions of 23 ° C. and 50% RH, and then left for 1 month under conditions of 100 ° C. and 60 ° C. and 95% RH, manufactured by Tokyo Denshoku Industries Co., Ltd .: Haze The HAZE of the sample was measured using a meter. (HAZE is a value obtained by subtracting the value of the glass plate alone.) Evaluation criteria are as follows.
○: HAZE less than 0.5 Δ: HAZE 0.5 or more and less than 1.0 ×: HAZE 1.0 or more

(4) Holding power In the same manner as in the previous section (2), a test sample was prepared, and this film piece was adhered to a stainless steel plate (# 360 polishing) with a 25 mm × 25 mm adhesive area using a table laminating machine. A pressure-sensitive adhesive sheet was pressure-bonded to obtain a test sample. The sample was allowed to stand under conditions of 23 ° C. and 50% RH for 24 hours, and then a 1 kg static load was applied in an 80 ° C. atmosphere, and the distance of the test sample from the stainless plate after 24 hours was measured. The evaluation criteria are as follows.
○: Deviation of less than 0.5 mm Δ: Deviation of 0.5 mm or more and less than 1.5 mm x: Deviation of 1.5 mm or more

(5) Durability
A test sample is prepared in the same manner as in the previous section (2) except that a cut film piece of 80 mm × 150 mm (long side) is used, and this film piece is formed on a glass plate having a thickness of 2 mm using a table laminator. Crimp to make a test sample. The sample is allowed to stand for 24 hours under conditions of 23 ° C. and 50% RH, and then left for one month under conditions of 100 ° C., and the generation of bubbles is evaluated by visual observation. The evaluation criteria are as follows.
○: Bubbles are not generated.
Δ: Slight generation of bubbles is observed.
X: Generation | occurrence | production of many bubbles is recognized.

(6) Sample film prepared in accordance with the item (1) before step difference, cut into 20 mm x 150 mm, the cut adhesive layer is rolled into a rod shape, pulled at a speed of 0.1 m / min in an atmosphere of 40 ° C, stress -Strain curve was measured. In addition, Young's modulus was calculated from the measured stress-strain curve, and used as an alternative characteristic of step following ability. The evaluation criteria are as follows.
○: less than Young's modulus of 4.0N / cm ² △: Young's modulus of 4.0N / cm ² more than 6.0N / cm ² less than ×: Young's modulus of 6.0N / cm ² or more

Production of acrylic copolymer (A) 1
Acrylic copolymer production example 1
Production Example 1
A reactor equipped with a stirrer, reflux condenser, sequential dropping device, thermometer, 25% by weight of a monomer mixture consisting of 98 parts by weight of n-butyl acrylate (BA) and 2 parts by weight of acrylic acid (AA), acetic acid 42 parts by weight of ethyl and 0.0125 part by weight of a polymerization initiator azobisisobutyronitrile (AIBN) were added and heated, and polymerization was carried out at reflux temperature for about 20 minutes. Next, 75% by weight of the remaining amount of the monomer mixture under a reflux temperature condition and a polymerization initiator solution consisting of 12.0 parts by weight of ethyl acetate and 0.0625 parts by weight of AIBN were successively added dropwise over about 130 minutes, and further 90 minutes. Thereafter, 12.0 parts by weight of ethyl acetate and 0.24 parts by weight of AIBN were successively added dropwise over about 40 minutes, and the polymerization reaction was further carried out for 120 minutes. After completion of the reaction, the mixture was diluted with methyl ethyl ketone and t-butyl alcohol to obtain an acrylic copolymer solution (A-1) having a solid content of about 40% and a viscosity of about 11000 mPa · s.

The obtained acrylic copolymer has a glass transition point (TgA) of 53.1 ° C., a solubility parameter (SPA) of 20.3, a weight average molecular weight (Mw) of about 780,000, a weight average molecular weight (Mn) and a number. It had an average molecular weight ratio (Mw / Mn) of 9.93.

Acrylic copolymer production example 2
In Production Example 1, 98 parts by weight of n-butyl acrylate (BA) was changed to 68 parts by weight of n-butyl acrylate (BA) and 30 parts by weight of t-butyl acrylate (tBA). A solution of an acrylic copolymer (A-2) was obtained.

Acrylic copolymer production example 3
In Production Example 1, acrylic copolymer (A-3) solutions were obtained in the same manner as in Production Example 1 except that n-butyl acrylate (BA) was changed to 2-ethylhexyl acrylate.

Acrylic copolymer production example 4
In the production example 1, 98 parts by weight of n-butyl acrylate (BA) was changed to 80 parts by weight of n-butyl acrylate (BA) and 18 parts by weight of methyl acrylate (MA). A solution of copolymer (A-4) was obtained.

Acrylic copolymer production example 5
Manufacturing Example 1 except that the polymerization initiator solution consisting of 12.0 parts by weight of ethyl acetate and 0.0625 parts by weight of AIBN was changed to the polymerization initiator solution consisting of 36.0 parts by weight of ethyl acetate and 0.125 parts by weight of AIBN. In the same manner as in Example 1, acrylic copolymer (A-5) solutions were obtained. Table 1 shows the viscosity of the resulting acrylic copolymer solutions (A-1) to (A-5) and the TgA, SPA, Mw, and Mw / Mn values of the copolymer.

Production of acrylic oligomer (B) Production example 6 of acrylic oligomer
Add 26.1 parts by weight of toluene, 26.1 parts by weight of methyl ethyl ketone, and 8.7 parts by weight of α-methylene styrene dimer as a chain transfer agent to a reactor equipped with a stirrer, reflux condenser, sequential dropping device, and thermometer. The polymerization was carried out at the reflux temperature for about 20 minutes. Next, t-butyl methacrylate (tBMA): 63 parts by weight, acrylic acid (AA): 3.5 parts by weight, ethyl acrylate (EA): 9.1 parts by weight, n-butyl as a monomer component under reflux temperature conditions Acrylate (BA): about 180 parts of a polymerization initiator solution composed of 11.3 parts by weight of toluene, 29.0 parts by weight of toluene, 29.0 parts by weight of methyl ethyl ketone, and 2.9 parts by weight of azobisisobutyronitrile (AIBN). The solution was successively added dropwise over a period of 120 minutes and further subjected to a polymerization reaction for 120 minutes to obtain an oligomer solution (B-1) having a solid concentration of 40% by weight. The oligomer in the oligomer solution (B-1) has a weight average molecular weight (Mw) of 4587, a ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) of 2.01, and a glass transition temperature (TgB) of 53.3. The solubility parameter (SPB) was 19.8.

Acrylic oligomer (B) Production Example 7
In Production Example 1, the monomer components were changed to t-butyl methacrylate (tBMA): 75.2 parts by weight, acrylic acid (AA): 3.5 parts by weight, and ethyl acrylate (EA): 8.7 parts by weight. Except for this, a solution of an acrylic copolymer (B-2) was obtained in the same manner as in Production Example 1.

Acrylic oligomer (B) Production Example 8
In Production Example 1, the monomer components were changed to n-butyl methacrylate (nBMA): 52.5 parts by weight, acrylic acid (AA): 3.5 parts by weight, and ethyl acrylate (EA): 31.5 parts by weight. Except for the above, a solution of an acrylic copolymer (B-3) was obtained in the same manner as in Production Example 1.

Acrylic oligomer (B) Production Example 9
In the same manner as in Production Example 1, except that the monomer components were changed to t-butyl methacrylate (tBMA): 78.8 parts by weight and acrylic acid (AA): 8.8 parts by weight, the acrylic copolymer A solution of the polymer (B-4) was obtained.

Acrylic oligomer (B) Production Example 10
In Production Example 1, the monomer components were changed to cyclohexyl methacrylate (CHMA): 75.2 parts by weight, acrylic acid (AA): 3.5 parts by weight, and ethyl acrylate (EA): 8.7 parts by weight. In the same manner as in Production Example 1, an acrylic copolymer (B-5) solution was obtained.

Acrylic oligomer (B) Production Example 11
In Production Example 1, an acrylic resin was prepared in the same manner as in Production Example 1 except that the chain transfer agent was changed to 8.7 parts by weight of n-dodecyl mercaptan and the amount of azobisisobutyronitrile (AIBN) to 0.29 parts by weight. A solution of the copolymer (B-6) was obtained.

Acrylic oligomer (B) Production Example 12
A solution of the acrylic copolymer (B-7) was obtained in the same manner as in Production Example 1 except that the chain transfer agent was changed to 17.4 parts by weight of α-methylenestyrene dimer in Production Example 1. Table 1 shows the viscosity of the obtained acrylic oligomers (B-1) to (B-7) and the values of TgB, SPB, Mw, and Mw / Mn of the copolymer.

Example 1
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-1): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 47.2%.
This pressure-sensitive adhesive solution was cast and applied on a release treatment surface of a polyethylene terephthalate film (thickness: 100 μm) on one side so that the thickness after drying was about 50 μm, After heat drying at 100 ° C. for 2 minutes, a polyethylene terephthalate film (thickness: 38 μm) having a release treatment (heavy peeling) on the other side was pressed through a pressure nip roll and bonded together. Curing was carried out for 7 days under conditions of 23 ° C. and 50% relative humidity to obtain a double-sided pressure-sensitive adhesive film having no adhesive layer on both sides.

Example 2
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-2): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 49.5%.

Example 3
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-1): 60 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 33.2%.

Example 4
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-1): 20 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 55.4%.

Example 5
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-1): 20 parts by weight (solid content), trade name “Sumijour N75” (Sumitomo Bayer) as a crosslinking agent Urethane Co., Ltd .; HMDI crosslinking agent): 0.375 parts by weight (solid content) was mixed to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 52.0%.

Comparative Example 1
Acrylic polymer solution (A-2): 100 parts by weight (solid content), oligomer solution (B-1): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 45.2%.

Comparative Example 2
Acrylic polymer solution (A-3): 100 parts by weight (solid content), oligomer solution (B-1): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 41.9%.

Comparative Example 3
Acrylic polymer solution (A-4): 100 parts by weight (solid content), oligomer solution (B-1): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 65.3%.

Comparative Example 4
Acrylic polymer solution (A-5): 100 parts by weight (solid content), oligomer solution (B-1): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 19.9%.

Comparative Example 5
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-1): 10 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 58.5%.

Comparative Example 6
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-1): 70 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 28.8%.

Comparative Example 7
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-3): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 44.4%.

Comparative Example 8
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-4): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 22.3%.

Comparative Example 9
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-5): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 47.6%.

Comparative Example 10
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-6): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 48.3%.

Comparative Example 11
Acrylic polymer solution (A-1): 100 parts by weight (solid content), oligomer solution (B-7): 40 parts by weight (solid content), trade name “TETRAD-C” (Mitsubishi Gas) Chemical Co., Ltd .; tetrafunctional epoxy crosslinking agent): mixed at a ratio of 0.05 part by weight (solid content) to prepare an adhesive composition solution. The gel content of the pressure-sensitive adhesive composition solution was 41.8%.

Claims (6)

A pressure-sensitive adhesive composition comprising the following (A), (B) and (C),
(A) a C2-C6 (meth) acrylic acid alkyl ester monomer having an alkyl group and a carboxyl group-containing monomer as a copolymerization component, a weight average molecular weight (Mw) of 500,000 to less than 900,000, glass Acrylic copolymer (A) having a transition temperature (Tg) of -60 ° C to -40 ° C.
(B) 1 to 10 parts by weight of a monomer containing a carboxyl group as a copolymer component with respect to 100 parts by weight of an acrylic monomer containing 50% by weight or more of t-butyl methacrylate, and a weight average molecular weight (Mw) An acrylic copolymer oligomer (B) having a glass transition temperature (Tg) of 10 ° C. to 110 ° C. of 3000 or more and less than 10,000.
(C) A crosslinking agent (C) having a functional group capable of reacting with the pressure-sensitive adhesive composition in the molecule.
Acrylic copolymer (A) and the mixing ratio of 100 / 20-100 / 60 (weight ratio) der Ru viscosity Chakuzai composition with the acrylic copolymer oligomer (B). The acrylic copolymer (A) is a copolymer of 1 to 10 parts by weight of a monomer containing a carboxyl group with respect to 100 parts by weight of an alkyl group (meth) acrylic acid alkyl ester monomer having 2 to 6 carbon atoms. The pressure-sensitive adhesive composition according to claim 1, which is an acrylic copolymer contained as a polymerization component. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the cross-linking agent (C) is a cross-linking agent having 2 to 5 functional groups capable of reacting with the pressure-sensitive adhesive composition in the molecule. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein all the monomers containing a carboxyl group are acrylic acid. The double-sided adhesive tape which has an adhesive layer which consists of a crosslinked body of the adhesive composition in any one of Claims 1-4 . The laminated sheet for optics which has an adhesive layer which consists of a crosslinked body of the adhesive composition in any one of Claims 1-4 .