TWI512075B - Composition of photohardenable transparent adhesive sheet - Google Patents

Description

Photocurable transparent adhesive sheet composition

The present invention relates to a transparent conductive film for transparent use of a composition for a photocurable transparent adhesive sheet, a photocurable transparent adhesive sheet obtained by curing a composition for a photocurable transparent adhesive sheet, and a transparent conductive film. The transparent adhesive film fixing transparent adhesive sheet obtained by curing the composition for adhesive sheet, the transparent conductive film fixing transparent adhesive sheet, and the transparent adhesive film for transparent conductive film fixing are adhered to the conductive layer of the transparent conductive film. Laminated body.

In recent years, touch panels have been installed in the fields of mobile phones and game machines. The touch panel is a transparent substrate or a glass having a transparent conductive film such as ITO (indium tin oxide) on the surface layer, and a transparent protective sheet for protecting the same, and an optical member for a display device such as a liquid crystal display is bonded to the transparent adhesive sheet for optics. Laminated body.

In the touch panel, there are mainly a touch panel of a resistive film type which is detected by pressure at the time of input, and a touch panel of an electrostatic capacity type which is an electrostatic detecting input from a human body when input. In the electrostatic capacitance type touch panel, the conductive layer of the transparent conductive film is fixed to the surface of the adhesive layer of the adhesive sheet. Therefore, when the conductive layer of the transparent conductive film is in contact with the adhesive layer, the oxidation reaction of the metal occurs due to the acid component contained in the adhesive, resulting in a problem that the conductive function is lowered. Therefore, the adhesive sheet for fixing the transparent conductive film requires high metal corrosion resistance.

An adhesive sheet containing a metal anticorrosive agent is proposed as an adhesive sheet having metal corrosion resistance (for example, Patent Document 1). In addition, an adhesive sheet having a specific amount of a nitrogen atom-containing component in the acid component of the adhesive layer to reduce the corrosivity of the transparent conductive film is proposed (for example, Patent Document 2).

However, the adhesive sheet containing a metal anticorrosive agent has a problem that the metal anticorrosive agent is discolored in durability test, and optical characteristics are lowered. Further, the adhesive sheet containing a specific amount of the nitrogen atom-containing component has a problem that the resistance of the ITO cannot be sufficiently suppressed due to the acid component contained in the adhesive layer.

On the other hand, a touch panel or the like includes a step having a step such as a printing step, and a touch panel or the like having a member for applying a frame-shaped printing portion is used for a mobile phone or the like. In such a use, the adhesive sheet is required to have a property of adhering and fixing the member while burying the printing step, that is, an excellent step absorption is required. If the transparent adhesive sheet cannot absorb the step, the floating (bubble or void) of the transparent adhesive sheet is generated around the end of the printed layer, and the light reflection loss due to the floating (bubble or void) causes the visibility of the liquid crystal display to decrease. After that.

In order to obtain excellent step absorbability, the transparent adhesive sheet is advantageous in that it is soft and has high adhesive strength. However, for the reasons described above, it is required to have no acid component and high adhesiveness. In response to this requirement, it is disclosed that an adhesive composition comprising a specific molecular weight propylene-based polymer having an acid-free component and an alkoxyalkyl acrylate as a main monomer and a crosslinking agent can have good adhesion and A metal-corrosive transparent adhesive sheet (for example, Patent Document 3).

However, the stability of the composition after the addition of the polymer-added crosslinking agent is insufficient, and it is necessary to dilute the solvent when coating the polymer, so that it is very difficult to produce an adhesive sheet having a thickness of 100 μm or more.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-45315

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-144002

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-079203

The object to be solved by the present invention is to provide a transparent adhesive sheet obtained by hardening directly bonding to a conductive layer of a transparent conductive film without causing corrosion of the conductive layer, and excellent adhesion, transparency, and press formability of the adhesive layer, and absorption of a step difference A composition for a one-liquid type photocurable transparent adhesive sheet excellent in properties. Further, the transparent adhesive sheet is provided.

The inventors of the present invention have diligently studied the results based on the above-mentioned problems of the photocurable transparent adhesive sheet for a touch panel, and found that a (meth)acryl-based polyolefin urethane acrylate having a high molecular weight and a specific amount is introduced. The photohardenable composition of a compound, a hydroxyl group-containing (meth) acrylate, a carboxyl group-containing monomer, a photopolymerizable monomer having a content of less than a specific amount, and a photocurable transparent adhesive sheet of a photopolymerization initiator The transparency of the photocurable transparent adhesive sheet obtained by curing the composition with the composition is excellent in transparency, adhesiveness, metal corrosion resistance of the transparent conductive film, and poor absorption of the step, and the present invention has been completed based on the findings.

The present invention is the following (1) to (7).

(1) A composition for a photocurable transparent adhesive sheet comprising (A) a (meth)acryl-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000, and (B) having a hydroxyl group (methyl) a composition for a photocurable transparent adhesive sheet comprising an acrylate, (C) a photopolymerizable monomer other than a hydroxyl group (meth) acrylate, and (D) a photopolymerization initiator; A) The (meth) propylene-based polyolefin compound having a weight average molecular weight of 10,000 to 300,000 is obtained by reacting a polyolefin polyol with a polyfunctional isocyanate compound, and then by using 50- to the relatively remaining hydroxyl group or isocyanate group. 80 mol% of a compound having a (meth)acryl group, a urethane (meth) acrylate compound obtained by introducing a (meth) propylene group into the molecule, and (C) a (meth) acrylate having a hydroxyl group The carboxyl group-containing monomer contained in the photopolymerizable monomer other than the ester is 0.1% by mass or less based on the total amount of the photopolymerizable monomer other than the (meth) acrylate having a hydroxyl group.

(2) The composition for a photocurable transparent adhesive sheet according to the above aspect, wherein the total amount of the composition for the photocurable transparent adhesive sheet contains (A) a weight average molecular weight of 10,000 to 300,000. 10 to 50% by mass of the (meth)acryl-based polyolefin compound, (B) 1 to 30% by mass of the (meth) acrylate having a hydroxyl group, and (C) photopolymerization other than the (meth) acrylate having a hydroxyl group The monomer is 20 to 88% by mass, and (D) the photopolymerization initiator is 0.2 to 5% by mass.

(3) A composition for a photocurable transparent adhesive sheet according to (1), wherein (C) the photopolymerizable monomer other than the (meth) acrylate having a hydroxyl group does not contain a carboxyl group-containing monomer .

(B) A composition for a photocurable transparent adhesive sheet according to any one of (1), wherein (B) a (meth) acrylate having a hydroxyl group, and (C) having a hydroxyl group (A) The theoretical glass transition temperature of the polymer composed of the photopolymerizable monomer other than the acrylate is from 0 ° C to 50 ° C.

(5) A composition for a transparent adhesive film for fixing a transparent conductive film, which is characterized by being used for curing a photocurable transparent adhesive obtained by curing a composition for a photocurable transparent adhesive sheet according to any one of (1) to (4) The sheet is attached to the transparent conductive film.

(6) A transparent adhesive sheet for fixing a transparent conductive film, which is obtained by curing the composition for a transparent adhesive film for transparent conductive film according to (5) above.

(7) A laminate in which the transparent adhesive sheet for fixing a transparent conductive film according to the above (6) is adhered to a conductive layer of the transparent conductive film.

The composition for a photocurable transparent adhesive sheet of the present invention, which comprises a high molecular weight (meth) propylene-based polyolefin compound having an adjusted (meth) propylene group content, and has a step absorbability and moisture permeability resistance. It is excellent in the content of the carboxyl group in the composition, and the content of the carboxyl group is not more than a specific amount, thereby suppressing the corrosion of the conductive layer of the transparent conductive film by the acid component, and further obtaining a high cohesive force due to the (meth) acrylate having a hydroxyl group in the composition. Adhesion to the substrate.

[Best Mode for Carrying Out the Invention]

Hereinafter, the present invention will be described in detail.

(Composition for photocurable transparent adhesive sheet)

The composition for a photocurable transparent adhesive sheet of the present invention contains (A) a (meth)acryl-based polyolefin compound having a weight average molecular weight of 10,000 to 300,000, and (B) a (meth) acrylate having a hydroxyl group. (C) A photopolymerizable monomer having a hydroxyl group (meth) acrylate and (D) a photopolymerization initiator.

((A) (meth) propylene-based polyolefin compound)

(A) The (meth) propylene-based polyolefin compound may be one having a polyolefin skeleton and further introducing a (meth) propylene group. (A) A polyolefin skeleton which can be used for the (meth)acryl-based polyolefin compound, and examples thereof include polyethylene, polypropylene, ethylene/propylene copolymer, butadiene, isoprene, hydrogenated polybutadiene, A skeleton of hydrogenated polyisoprene, cycloolefin or the like. From the viewpoint of light resistance, transparency (non-crystalline), and workability (liquid), it is preferred to use a hydrogenated polybutadiene or a hydrogenated polyisoprene skeleton. Further, the (meth)acrylyl group means CH ₂ =CH-CO- or CH ₂ =C(CH ₃ )-CO-.

(A) a (meth) propylene-based polyolefin compound of the present invention, wherein (meth) propylene group is introduced into a molecule by subjecting a (meth) acrylate having a hydroxyl group or an isocyanate group to a ureidolation reaction The (meth)acryl-based polyolefin compound obtained is preferred from the viewpoint of adhesion and toughness. (A) A method for synthesizing a (meth)acryl-based polyolefin compound, for example, the following two-stage reaction.

The two-stage reaction as the first example is as follows. First, a polyfunctional isocyanate compound having two or more isocyanate groups in one molecule (hereinafter, also referred to as "polyfunctional isocyanate compound") is reacted at a ratio of an isocyanate group equivalent ratio to a hydroxyl group equivalent to a polyolefin polyol. A urethane prepolymer having an isocyanate group. At this time, the molecular weight can be adjusted by adjusting the hydroxyl equivalent of the polyolefin polyol and the isocyanate group equivalent ratio of the polyfunctional isocyanate compound. The larger the ratio of the hydroxyl equivalent of the isocyanate group, the larger the molecular weight of the obtained polyurethane compound, the smaller the ratio of the hydroxyl equivalent of the isocyanate group equivalent, and the smaller the molecular weight of the obtained polyurethane compound. . Next, in terms of the (meth) acrylate having a hydroxyl group in the obtained urethane prepolymer, a hydroxyalkyl (meth) acrylate or a (meth) acrylate unit alcohol derived from various polyols (remaining The next hydroxyl group is subjected to (meth)acrylation of various polyols to convert the remaining isocyanate groups into (meth)acrylyl groups to obtain (A) (meth)acrylate-containing polyolefins. Compound. Specific examples of the hydroxyalkyl (meth) acrylate, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,3-butanediol (meth) acrylate, 1,4-butanediol (meth) acrylate, 1,6-hexanediol (meth) acrylate, 3-methylpentane diol (meth)acrylate or the like may be used singly or in combination of two or more kinds. Among them, 2-hydroxyethyl acrylate is preferred from the viewpoints of reactivity with isocyanate groups and photocurability. At this time, the amount of the (meth)acryl group-containing group can be adjusted by reacting the alkyl alcohol with the isocyanate group. The saturated alcohol which can be used is not particularly limited, and one or two or more kinds of linear, branched or alicyclic alkyl alcohols can be used.

The two-stage reaction of the second example is as follows. First, a polyolefin polyol and a polyfunctional isocyanate compound are reacted in a ratio of a hydroxyl group equivalent ratio to an isocyanate group equivalent to synthesize a hydroxyl group-containing polyurethane compound having a chain length extension. At this time, the molecular weight can be adjusted by adjusting the ratio of the hydroxyl equivalent of the polyolefin polyol to the isocyanate group equivalent of the polyfunctional isocyanate compound. The larger the ratio of the hydroxyl equivalent of the isocyanate group, the smaller the molecular weight of the obtained polyurethane compound, the smaller the ratio of the hydroxyl equivalent of the isocyanate group equivalent, and the molecular weight of the obtained polyurethane compound. The bigger it gets. Next, (A) a (meth) acrylate-containing polyolefin compound is obtained by reacting the obtained polyurethane compound with an isocyanate group-containing (meth) acrylate. At this time, the content of the (meth)acryl group can be adjusted by adjusting the amount of the isocyanate group-containing (meth) acrylate which reacts with respect to the remaining hydroxyl group. The isocyanate group-containing (meth) acrylate may be synthesized by using a commercially available compound or by reacting a hydroxyalkyl (meth) acrylate or a (meth) acrylate unit alcohol derived from various polyols with a diisocyanate compound. An isocyanate group-containing (meth) acrylate having an isocyanate group and a (meth) propylene group at the other end. It contains an isocyanate group (meth) acrylate, such as 2-isocyanate ethyl (meth) acrylate, 1, 1-bis (propylene methoxymethyl) ethyl isocyanate, and the like. Among them, 2-isocyanate ethyl acrylate is preferred from the viewpoints of reactivity with a hydroxyl group and photocurability.

The two-stage reaction of the above two examples is a reaction of a hydroxyl group with an isocyanate group, and a general amino acid such as dibutyltin dilaurate or dibutyltin diethyl benzoate is used in the presence of an isocyanate-based inactive organic solvent. The esterification catalyst is usually carried out at 30 to 100 ° C for about 1 to 5 hours. The amount of the urethane-based catalyst used is usually 50 to 500 ppm based on the total mass of the reaction raw materials supplied.

The polyfunctional isocyanate compound used in the present invention may, for example, be toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate or tetramethyl xylene. Diisocyanate, isophorone diisocyanate, and diisocyanate compounds such as these hydrides. Among them, isophorone diisocyanate is preferred from the viewpoint of light resistance and reactivity control difficulty. The compound having two or more isocyanate groups in one molecule may be used singly or in combination of two or more kinds. The amount of the polyfunctional isocyanate compound to be used in the reaction at a ratio of the isocyanate group equivalent to the hydroxyl group equivalent is preferably from 1.8 to 2.2 mol, more preferably from 1.9 to 2.1 mol, based on the polyolefin polyol. 1.95 ~ 2.05 Moore is better. When the amount of the polyfunctional isocyanate compound used is less than 1.8 moles, the molecular weight of the (A) (meth)-containing (meth)acryl-based polyolefin compound becomes too high and the operation becomes difficult, and the polyfunctional isocyanate compound is used in an amount of 2.2 mol. In many cases, the molecular weight of the (A) (meth)-containing (meth) propylene-based polyolefin compound is too low, and the strength of the sufficient adhesion sheet is not obtained. The amount of the polyfunctional isocyanate compound to be used in the case where the hydroxyl equivalent is more than the isocyanate group equivalent is more preferably 0.4 to 0.6 mol, more preferably 0.45 to 0.55 mol, based on the polyolefin polyol. 0.48 ~ 0.52 Moore is better. When the amount of the polyfunctional isocyanate compound used is less than 0.4 mol, the molecular weight of the (A) (meth)-containing (meth) propylene-based polyolefin compound is too low, and the strength of the adhesive sheet is not sufficiently obtained, and the polyfunctional isocyanate compound is likely to be obtained. When the amount of use of the (A) (meth)acryl-containing polyolefin compound is more than 0.6 mol, the molecular weight is too high and it becomes difficult to handle.

(A) a urethane (meth) acrylate compound containing a (meth) propylene-based polyolefin compound having a weight average molecular weight of 10,000 to 300,000 according to the present invention, which comprises a polyolefin polyol and a polyfunctional isocyanate The compound reaction is polymerized, and then 50 to 80 mol% of a (meth)acryl group is introduced relative to the remaining hydroxyl group or isocyanate group. More preferably, the remaining hydroxyl group or the isocyanate group is introduced with 55 to 75 mol% of a (meth)acryl group, and more preferably 60 to 70 mol% of a (meth)acryl group. When the ratio of the (meth)acryl group to be introduced is less than 50 mol%, there is a possibility that the (meth)acryl group-introduced polyolefin polyol may be introduced, and the adhesion may be lowered. When it is larger than 80 mol%, the obtained adhesive sheet may be less likely to become too hard.

The molecular weight of the (meth)-containing (meth)acryl-based polyolefin compound is preferably from 10,000 to 300,000 by weight average molecular weight, preferably from 20,000 to 200,000, more preferably from 50,000 to 100,000. The adjustment of the molecular weight can be carried out by adjusting the amount of the polyolefin polyol and the polyfunctional isocyanate compound. The weight average molecular weight is less than 10,000, and the cohesive force of the obtained adhesive sheet is lowered, and the strength of the adhesive sheet is insufficient. In addition, when the molecular weight is more than 300,000, the viscosity of the composition for a photocurable transparent adhesive sheet is too high, and handling becomes difficult and workability is remarkably deteriorated. In addition, the value of the weight average molecular weight in the present invention is measured by a colloidal permeation chromatography (Shodex GPC-101, manufactured by Showa Denko Co., Ltd.) at room temperature under the following conditions, and is calculated in terms of polystyrene.

Pipe column: LF-804 made by Showa Denko

Column temperature: 40 ° C

Sample: 0.2% by mass tetrahydrofuran solution of copolymer

Flow rate: 1ml/min

Dissolution: tetrahydrofuran

(A) The content of the (meth) propylene-based polyolefin compound is preferably from 10 to 50% by mass, more preferably from 15 to 45% by mass, even more preferably from 20 to 40% by mass, more preferably from 10 to 50% by mass of the photocurable transparent adhesive sheet composition. . When the amount is less than 10% by mass, the obtained adhesive sheet becomes brittle and is not preferable. When the amount is more than 50% by mass, the adhesion of the obtained adhesive sheet may be lowered, which is not preferable.

((B) (meth) acrylate having a hydroxyl group)

(B) The (meth) acrylate having a hydroxyl group is preferably one having no carboxyl group, for example, a hydroxyalkyl (meth) acrylate having an alkyl group having 2 to 7 carbon atoms, and the like, for example, 2-hydroxyethyl group (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butyl The diol (meth) acrylate, 1,6-hexane diol (meth) acrylate, 3-methylpentane diol (meth) acrylate, etc. may be used individually or in combination of 2 or more types. Among them, 2-hydroxyethyl acrylate is preferred from the viewpoint of the adhesion of the obtained adhesive sheet. (B) The content of the (meth) acrylate having a hydroxyl group is preferably from 1 to 30% by mass, preferably from 5 to 25% by mass, more preferably from 10 to 20% by weight of the composition for photocurable transparent adhesive sheet. quality%. When the amount is less than 1% by mass, the adhesion of the obtained adhesive sheet to the substrate becomes insufficient. Moreover, when it is more than 30% by mass, the water resistance of the adhesive sheet is deteriorated.

((C) Photopolymerizable monomer other than (meth) acrylate having a hydroxyl group)

(C) A photopolymerizable monomer other than a (meth) acrylate having a hydroxyl group (hereinafter, also referred to as "photopolymerizable monomer of (C)") is a photopolymerizable monomer and means a hydroxyl group ( Other than the methyl acrylate, a monomer having no carboxyl group (chemical formula: -COOH) is preferred. The monomer is not particularly limited, and a monofunctional or polyfunctional photopolymerizable monomer having a vinyl group or a (meth)acryl group may be used alone or in combination of two or more kinds. The photopolymerizable monomer of (C) of the present invention may, for example, be methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate or n-butyl (A). Acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n- Alkyl (meth) acrylate such as hexyl (meth) acrylate, stearyl methacrylate (meth) acrylate, lauryl (meth) acrylate, thirteen (meth) acrylate, etc., cyclohexyl (meth) acrylate, norbornene (meth) acrylate, isobornyl (meth) acrylate, norbornene (meth) acrylate, dicyclopentenyl (meth) acrylate, Dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, tricyclodecane dimethylol A cyclic alkyl (meth) acrylate such as di(meth)acrylate. For example, ethoxyethyl (meth) acrylate, methoxy ethyl (meth) acrylate, butoxy ethyl (meth) acrylate, 2-methoxy ethoxyethyl ( Alkoxyalkyl (meth) acrylate such as methyl acrylate or 2-ethoxyethoxyethyl (meth) acrylate, methoxy diethylene glycol (meth) acrylate, Alkoxy (poly)alkyl glycol (meth) acrylate such as ethoxy diethylene glycol (meth) acrylate or methoxy dipropylene glycol (meth) acrylate, octafluoropentyl (methyl) Fluorinated alkyl (meth) acrylate such as acrylate, N,N-dimethylaminoethyl (meth) acrylate, N,N-diethylaminoethyl (meth) acrylate Dialkylaminoalkyl (meth) acrylate such as ester, polyethylene glycol di(meth) acrylate, diethylene glycol di(meth) acrylate, neopentyl glycol di(methyl) Acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, 1,3-double (hydroxyl) -5,5-dimethylhydantoin di(meth)acrylate, α,ω-di(methyl) Alkenyl bis diethylene glycol phthalate, trimethylolpropane tri(meth) acrylate, ethylene glycol di(meth) acrylate, tetraethylene glycol di(meth) acrylate, poly Ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipropyleneoxyethyl phosphate Polyfunctional (meth) acrylate such as dipentaerythritol trihydroxy (meth) acrylate or pentaerythritol tetra (meth) acrylate, acrylamide and dimethyl methacrylate, diethyl acrylamide, An epoxy group-containing (meth) acrylate such as a acrylamide derivative such as (meth)acrylinylmorpholine or a propylene oxide (meth) acrylate. The photopolymerizable monomer of the invention (C) is an alkyl group from the viewpoint of compatibility with the (A) (meth)acryl-containing polyolefin compound, adhesion of the adhesive sheet, strength, light resistance, and heat resistance. (Meth) acrylate or a cyclic alkyl (meth) acrylate is preferred. The monofunctional or polyfunctional functional group referred to herein means a (meth) propylene group. The content of the photopolymerizable monomer (C) is preferably from 20 to 88% by mass, preferably from 20 to 70% by mass, based on the composition for photocurable transparent adhesive sheet. More preferably, it is 40 to 69% by mass. When the amount is less than 20% by mass, the obtained adhesive sheet is insufficient in adhesion to the substrate. Moreover, when it is more than 88% by mass, the adhesive strength of the adhesive sheet is lowered, and the adhesive strength is not preferable.

In the present invention, the carboxyl group-containing monomer such as acrylic acid or methacrylic acid contained in the photopolymerizable monomer (C) is 0.1% by mass or less and 0.05% by mass based on the total amount of the photopolymerizable monomer of (C). The following is better. The photopolymerizable monomer of (C) is more preferably free of a carboxyl group-containing monomer. When the total amount of the carboxyl group-containing monomer relative to (C) of the photopolymerizable monomer is more than 0.1% by mass, corrosion inhibition of the conductive layer of the transparent conductive film becomes difficult.

The theoretical glass transition temperature of the polymer composed of (B) a hydroxyl group-containing (meth) acrylate and (C) photopolymerizable monomer of the present invention is 0 to 50 ° C from the viewpoint of strength and adhesion of the adhesive sheet. It is better, 5 to 45 ° C is better, and 10 to 40 ° C is better. When the temperature is lower than 0 ° C, the obtained adhesive sheet is too soft due to the influence of the (A) (meth)acryl-containing polyolefin compound, and the adhesion of the adhesive sheet is lowered. Moreover, when it is higher than 50 ° C, the obtained adhesive sheet becomes too hard, and it is not preferable to obtain sufficient adhesiveness. Here, the theoretical glass transition temperature (Tg) is based on the Tg of each monomer alone polymer (homopolymer) constituting the monomer raw material and the mass fraction (copolymerization ratio) of the monomer, and can be expressed by the following FOX formula ( 1) Calculated.

[Number 1]

1/Tg=W ₁ /T ₁ +W ₂ /T ₂ +‧‧‧W _n /T _n (1)

In the formula (1), W ₁ and W ₂ ‧‧‧W _n are the mass fractions of the respective monomers (= (combination amount of each monomer / total mass of the monomers)), T ₁ , T ₂ ‧‧‧T _n It is the glass transition temperature (absolute temperature) of the homopolymer of each monomer. The Tg of the homopolymer is the value described in the "Adhesive Handbook" of the company's Nikkan Kogyo Shimbun, or the "Polymer Handbook" by Wiley-Interscience. Regarding the Tg of the homopolymer of the monomer not described in the above-mentioned conventional data, the value obtained by the following method was used. That is, a homopolymer solution obtained by solution polymerization of a subject monomer was cast-dried on a release liner to prepare a test sample. For the test sample, a differential scanning calorimeter (DSC) was used to measure the temperature from -80 ° C to 280 ° C at a temperature increase rate of 10 ° C / min, and the differential scanning calorimetry was performed using the endothermic onset temperature of glass transition. It is the Tg of the homopolymer.

((D) Photopolymerization initiator)

In the present invention, the (D) photopolymerization initiator may, for example, be a carbonyl photopolymerization initiator, a sulfide photopolymerization initiator, an oxime photopolymerization initiator, an azo photopolymerization initiator, or a sulfonate. A ruthenium chloride photopolymerization initiator, a thioxanthone photopolymerization initiator, a peroxide photopolymerization initiator, and the like.

The carbonyl photopolymerization initiator may, for example, be benzophenone, benzyl ester, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2, 2 -dimethoxy-2-phenylacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, p,p'-dichloro Benzophenone, p,p'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal , 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methyl Propane-1-one, methylbenzamide, 2,2-diethoxyacetophenone, 4-N,N'-dimethylacetophenone, 2-methyl-1-[ 4-(methylthio)phenyl]-2-morpholinylpropan-1-one or the like.

Examples of the sulfide-based photopolymerization initiator include diphenyl disulfide, dibenzyl disulfide, tetraethyl thiuram disulfide, and tetramethylammonium monosulfide. The oxime photopolymerization initiator may, for example, be benzofluorene or ruthenium. The azo photopolymerization initiator may, for example, be azobisisobutyronitrile, 2,2'-azobispropane or hydrazine. The thioxanthone-based photopolymerization initiator may, for example, be thioxanthone, 2-chlorothioxanthone or 2-methylthioxanthone. The peroxide photopolymerization initiator may, for example, be benzoyl peroxide or di-t-butyl peroxide. Among these (D) photopolymerization initiators, 2-methyl-1-[4-(methylthio)phenyl] is used from the viewpoint of solubility of the composition for the photocurable transparent adhesive sheet obtained. Preferably, -2-morpholinopropan-1-one is preferred. These (D) photopolymerization initiators may be used singly or in combination of two or more kinds.

(D) The content of the photopolymerization initiator is preferably from 0.2 to 5% by mass in the photocurable transparent adhesive sheet composition from the viewpoint of photocurability and strength and adhesion balance of the obtained adhesive sheet. Preferably, it is 0.5 to 3% by mass. When the content of the photopolymerization initiator is less than 0.2% by mass, the photocuring tends to be insufficient. When the content is more than 5% by mass, the adhesiveness of the obtained adhesive sheet tends to be lowered.

The composition for a photocurable transparent adhesive sheet of the present invention preferably contains 10 to 50% by mass of the component (A) and 1 to 30% of the component (B) with respect to the total amount of the composition for the photocurable transparent adhesive sheet. %, (C) component is 20 to 88% by mass, and (D) component is 0.2 to 5% by mass. More preferably, the total amount of the composition for the photocurable transparent adhesive sheet is 15 to 45% by mass of the component (A), 5 to 25% by mass of the component (B), and 20 to 70% by mass of the component (C), and The component (D) is 0.2 to 5% by mass. More preferably, the total amount of the composition for the photocurable transparent adhesive sheet is 20 to 40% by mass of the component (A), 10 to 20% by mass of the component (B), and 40 to 69% by mass of the component (C). And (D) component is 0.5 to 3 mass%.

In the composition for a photocurable transparent adhesive sheet of the present invention, if necessary, in order to improve the adhesion of the obtained adhesive sheet, a tackifier resin can be added without lowering the transparency. Examples of the tackifier resin include a rosin-based resin such as an esterified product of rosin or rosin; a terpene-based resin such as a diterpene polymer or an α-pinene-phenol copolymer; or an aliphatic system (C5-based) or aroma. Petroleum resin such as family (C9 series); other, styrene resin, phenol resin, toluene resin, and the like. From the viewpoint of light resistance, it is preferred to add an esterified product of hydrogenated rosin or uneven rosin having less unsaturated double bonds or an aliphatic or aromatic petroleum resin or a high Tg propylene-based resin to the adhesive sheet. The addition amount of the tackifier resin is added to 100 parts by mass of the composition for photocurable transparent adhesive sheet (100 parts by mass relative to the components (A), (B), (C) and (D)) ～10 parts by mass is preferred.

Further, in the composition for a photocurable transparent adhesive sheet of the present invention, various additives may be contained as long as necessary, without impairing the range of transparency. The additive may, for example, be a plasticizer, a surface lubricant, a leveling agent, a softener, an antioxidant, an aging preventive agent, a light stabilizer, a UV absorber, a polymerization inhibiting agent, a light stabilizer such as a benzotriazole system, or a phosphoric acid. Ester and other flame retardants, antistatic agents such as surfactants.

Further, in the composition for a photocurable transparent adhesive sheet of the present invention, an organic solvent can be used as a solution for the purpose of adjusting the viscosity at the time of coating. The organic solvent to be used may, for example, be methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, n-propanol or isopropanol. These organic solvents may be used singly or in combination of two or more.

(Composition for transparent adhesive film for transparent conductive film fixing)

The composition for an adhesive sheet for fixing a transparent conductive film of the present invention is a composition for an adhesive sheet for fixing a transparent conductive film which is composed of a composition for a photocurable transparent adhesive sheet.

The transparent conductive film used for the composition for an adhesive sheet for fixing a transparent conductive film of the present invention may have a conductive layer on at least one surface layer, and may be, for example, a surface layer of a transparent substrate, and a conductive material is deposited by evaporation. Or a transparent conductive film provided by coating. The conductive material to be vapor-deposited or coated in the conductive layer of the transparent conductive film is not particularly limited, and specifically, for example, indium tin oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, gallium oxide, or titanium oxide. Among them, indium tin oxide having excellent transparency and conductivity is preferably used. In the transparent conductive film, the substrate to be vapor-deposited or coated with a conductive material is not particularly limited, and examples thereof include glass and a resin film.

(Transparent adhesive film for transparent conductive film fixing)

The transparent adhesive sheet for fixing a transparent conductive film of the present invention is a transparent adhesive film for fixing a transparent conductive film which is obtained by curing a composition for a transparent adhesive film for fixing a transparent conductive film, and is suitable for being adhered to a conductive layer of a transparent conductive film. And it is a corrosive person who does not easily produce a conductive layer. Therefore, a laminate in which a transparent adhesive sheet for fixing a transparent conductive film is adhered to a conductive layer of a transparent conductive film can be suitably used as a touch panel. Moreover, the transparent adhesive sheet for fixing a transparent conductive film of the present invention may be a double-sided adhesive sheet having a substrate or a substrate without an adhesive layer. Further, the adhesive layer may be composed of a single layer or a plurality of laminates. Among them, from the viewpoint of ensuring transparency or shape followability, it is preferable to use a double-sided adhesive sheet composed of only an adhesive layer without a substrate.

The transparent adhesive sheet for fixing a transparent conductive film of the present invention can be coated with a composition for a transparent adhesive film for fixing a transparent conductive film by a release film of a PET film, and the composition can be cured by irradiating ultraviolet rays with an ultraviolet irradiation device or the like. get. The thickness of the adhesive sheet for fixing a transparent conductive film is preferably 5 to 500 μm, more preferably 10 to 300 μm. When the thickness of the adhesive sheet for fixing a transparent conductive film is thinner than 5 μm, the adhesion of the adhesive sheet becomes difficult, and the film thickness control tends to be difficult to be thicker than 500 μm.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the invention is not limited to the examples.

<(meth)acryl-containing polyolefin compound (A-1)>

In a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, isophorone diisocyanate 2 mol and hydroxyl terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl group 25 mgKOH/g) 1 mol, and reacted at 60 ° C for 4 hours to obtain an isocyanate group-terminated hydrogenated polybutadiene. 2-hydroxyethyl acrylate 1.4 mol (70 mol% relative to the residual isocyanate group) and 0.6 mol of isobutanol were added thereto, and the reaction was carried out for 2 hours after the temperature was raised to 70 ° C, and the disappearance of the isocyanate group was confirmed by IR measurement. The reaction was completed to obtain a (meth)acryl-containing polyolefin compound (A-1) (weight average molecular weight: 50,000).

<(meth)acryl-containing polyolefin compound (A-2)>

In a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, isophorone diisocyanate 1 mol and hydroxyl terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl group 25 mgKOH/g) 2 mol, and reacted at 60 ° C, and when the residual isocyanate group was 0.1% or less, 1.4 mol of 2-isocyanate ethyl acrylate was added (relative residual hydroxyl group was 70 mol%) The reaction was carried out for 2 hours until the temperature was raised to 70 ° C. After the disappearance of the isocyanate group by IR measurement, the reaction was completed to obtain a (meth)acryl-containing polyolefin compound (A-2) (weight average molecular weight: 50,000).

<(meth)acryl-containing polyolefin compound (A-3)>

In a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, isophorone diisocyanate 2 mol and hydroxyl terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl group 25 mgKOH/g) 1 mol, and reacted at 60 ° C for 4 hours to obtain an isocyanate group-terminated hydrogenated polybutadiene. 2-hydroxyethyl acrylate 2.0 mol (100 mol% relative residual isocyanate group) was added thereto, and the reaction was carried out for 2 hours until the temperature was raised to 70 ° C. After the disappearance of the isocyanate group was confirmed by IR measurement, the reaction was completed to obtain a (Meth)propylene-based polyolefin compound (A-3) (weight average molecular weight: 50,000).

<(meth)acryl-based polyolefin compound (A-4)>

In a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, isophorone diisocyanate 2 mol and hydroxyl terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl value 25 mgKOH/g) 1 mole. The reaction was carried out at 60 ° C for 4 hours to obtain an isocyanate-terminated hydrogenated polybutadiene. 2-hydroxyethyl acrylate 0.4 mol (20 mol% relative to the residual isocyanate group) and 1.6 mol of isobutanol were added thereto, and the reaction was carried out for 2 hours after the temperature was raised to 70 ° C, and the disappearance of the isocyanate group was confirmed by IR measurement. The reaction was completed to obtain a (meth)acryl-containing polyolefin compound (A-4) (weight average molecular weight: 50,000).

<(meth)acryl-containing polyolefin compound (A-5)>

In a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, 2-isocyanate ethyl acrylate 1.4 mol and hydroxyl terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name) : GI-1000, hydroxyl group 75 mgKOH/g) 1 mol, and reacted at 60 ° C for 4 hours, and after confirming the disappearance of the isocyanate group by IR measurement, the reaction was completed to obtain a (meth) propylene-based polyolefin compound (A- 5) (weight average molecular weight 5,000).

<(meth)acryl-containing polyolefin compound (A-6)>

In a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a cooling tube with a drying tube, isophorone diisocyanate 1.5 mol and hydroxyl terminated hydrogenated polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: GI-3000, hydroxyl group 25 mgKOH/g) 1 mol, and reacted at 60 ° C for 4 hours to obtain an isocyanate group-terminated hydrogenated polybutadiene. 2-hydroxyethyl acrylate 0.8 mol (80 mol% relative to the residual isocyanate group) and 0.2 mol of isobutanol were added thereto, and the reaction was carried out until the temperature was raised to 70 ° C. However, the polymer was polymerized and colloidal during the reaction. .

Examples 1 to 6 and Comparative Examples 1 to 4

The compositions shown in Table 1 were each blended, and mixed at room temperature using a disperser to prepare a composition for a uniform photocurable transparent adhesive sheet. The composition of the photocurable transparent adhesive sheet to be prepared was applied to a release PET film (100 mm × 100 mm × 100 μm) so as to have a film thickness of 200 μm, and the upper surface was coated with a release film of 25 μm thick. After that, an ultraviolet irradiation device (UV irradiation device 4kw×1, output: 160 W/cm, metal halide lamp manufactured by Nippon Battery Co., Ltd.) was used, and the irradiation distance was 12 cm, the lamp moving speed was 20 m/min, and the irradiation amount was about 500 mJ/cm ² . The condition was irradiated with ultraviolet rays and then hardened to obtain an adhesive sheet having a film thickness of about 200 μm held on the release film.

(calculation of theoretical glass transition temperature)

In the examples and comparative examples, the theoretical glass transition temperature of the polymer composed of (B) a hydroxyl group-containing (meth) acrylate and (C) photopolymerizable monomer was calculated by the above formula (1). The results are shown in Table 1.

(Measurement of resistance value of indium tin oxide film)

The adhesive sheet obtained above was cut into a size of 50 mm × 50 mm, and a 25 μm-thick release PET film was peeled off and attached to an indium tin oxide film surface of a 100 mm × 100 mm indium tin oxide vapor-deposited PET film. "LORESTAGP" manufactured by Mitsubishi Chemical Corporation was used at both ends of the bonded adhesive sheet, and the initial resistance value (R ₁ ) was measured. The indium tin oxide vapor-deposited PET film adhered to the adhesive sheet was allowed to stand under the conditions of 60 ° C and 90% RH for 500 hours, and left at 23 ° C and 50% RH for 1 hour, and then the same resistance value as that at the initial stage was measured (R). ₂ ). The rate of increase in the resistance value of the indium tin oxide film was calculated by the following formula (2).

[Number 2]

Resistance increase rate of indium tin oxide film (%) = ((R ₂ -R ₁ )/R ₁ )×100 (2)

The evaluation of the increase rate of the resistance value was performed using the following criteria. The results are shown in Table 1.

○; resistance value rise rate is less than 5%

△; resistance value rise rate 5 ~ less than 10%

×; resistance value increase rate of 10% or more

(Adhesive strength measurement of adhesive sheets)

The adhesive sheet obtained above was cut into a size of 25×100 mm, and the 100 μm thick release PET film in the release PET film existing on both sides of the adhesive sheet was peeled off, and the adhesive surface (measurement surface) was used in the test plate at 2 kg. A rubber roller (width: about 50 mm) was attached one by one to make a sample for measurement. The test plate uses a glass plate. The obtained sample for measurement was allowed to stand in an environment of 23° C. and a humidity of 50% for 24 hours, and subjected to a tensile test at a peeling speed of 300 mm/min in a 180° direction in accordance with JIS Z0237, and the adhesion of the adhesive sheet to the glass plate was measured ( N/25mm). The obtained measured value was used as the adhesive force. The results are shown in Table 1.

(total light transmittance measurement)

The adhesive sheet obtained above was cut into a size of 30 mm × 30 mm, and the peeled PET film of 25 μm thick in the release PET film existing on both sides of the adhesive sheet was peeled off, and the sample to be bonded to the glass plate was used as a sample for measurement. The measurement sample was measured using the "HR-100 model" manufactured by Murakami Color Technology Research Co., Ltd., and the total light transmittance (%) was measured. The results are shown in Table 1.

(step difference absorption)

A PET film (thickness: 25 μm) was attached to the adhesive sheet obtained above to prepare a step tape having a total thickness of 225 μm. The step tape is adhered in a frame shape along the edges of the four sides of the main surface of the rectangular glass plate to form a glass plate having a step. The glass plate with the step difference is adhered to the surface of the step tape surface, and the adhesive sheet is attached to visually observe the floating of the adhesive layer of the step portion.

The step absorbability evaluation was carried out using the following criteria. The results are shown in Table 1.

○; the floating state of the non-adhesive layer with the step difference is qualified

×; there is a floating state is unqualified

From the results of Table 1, it is understood that the composition for a photocurable transparent adhesive sheet of the present invention obtained in the examples is superior in resistance increase rate, total light transmittance, adhesion, and step absorbability to the comparative example.

[Industrial use]

The composition for a photocurable transparent adhesive sheet of the present invention is excellent in transparency, metal corrosion resistance, step absorption, and adhesion, and can be used as an adhesive sheet for fixing a transparent conductive film, and is particularly suitable for electrostatic capacitance type touch. The fixing of the transparent conductive film used for the panel.

Claims (6)

A composition for a photocurable transparent adhesive sheet comprising (A) a (meth)acryl-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000, 10 to 50% by mass, and (B) having a hydroxyl group ( 1 to 30% by mass of the methyl acrylate, (C) 20 to 88% by mass of the photopolymerizable monomer other than the (meth) acrylate having a hydroxyl group, and (D) 0.2 to 5% by mass of the photopolymerization initiator A composition for a photocurable transparent adhesive sheet characterized in that (A) a (meth)acryl-containing polyolefin compound having a weight average molecular weight of 10,000 to 300,000 is a polyolefin polyol and a polyfunctional isocyanate compound a reaction, followed by a reaction of a compound having a (meth)acryl group with 50 to 80 mol% of a relatively residual hydroxyl group or an isocyanate group to introduce a (meth)acryl group into the molecule ( a (meth) acrylate compound, (C) a carboxyl group-containing monomer contained in a photopolymerizable monomer other than a hydroxyl group (meth) acrylate, and (C) a photopolymerization other than a (meth) acrylate having a hydroxyl group The total amount of the monomer is 0.1% by mass or less. The photocurable transparent adhesive sheet composition according to claim 1, wherein the (C) photopolymerizable monomer other than the (meth) acrylate having a hydroxyl group does not contain a carboxyl group-containing monomer. The photocurable transparent adhesive sheet composition according to claim 1, wherein (B) a (meth) acrylate having a hydroxyl group and (C) a photopolymerizable property other than a (meth) acrylate having a hydroxyl group The theoretical glass transition temperature of the polymer composed of the monomers is from 0 ° C to 50 ° C. A composition for a transparent adhesive film for fixing a transparent conductive film, The photocurable transparent adhesive sheet obtained by curing the composition for a photocurable transparent adhesive sheet according to any one of claims 1 to 3 is bonded to a transparent conductive film. A transparent adhesive film for fixing a transparent conductive film, which is obtained by curing a composition for a transparent conductive film for fixing a transparent conductive film according to claim 4. A laminate characterized in that the transparent adhesive film for fixing a transparent conductive film according to claim 5 is adhered to a conductive layer of the transparent conductive film.