KR102071340B1 - Adhesive composition and adhesive film - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film having excellent anti-clouding performance, even when the pressure-sensitive adhesive layer is thickly applied, which does not become cloudy even when left in a high temperature and high humidity atmosphere for a long time. (A) 0.1-10 weight part of at least 1 sort (s) or more of the copolymerizable monomer containing a hydroxyl group (B) with respect to 100 weight part of at least 1 sort (s) or more of the (meth) acrylic acid ester monomers of C1-C18 alkyl group. The acrylic polymer composed of a copolymer having a weight average molecular weight copolymerized at a ratio of 200,000 to 2 million and having an acid value of 5.0 or less, and R ¹ COO- (R ³ -O) _n -CO-R ² (wherein R ¹ and R ² are An alkyl group having 4 to 17 carbon atoms, R ³ is an alkylene group having 2 to 5 carbon atoms, n represents an integer of 3 to 25), at least one or more of the (C) diester compounds, (D) an isocyanate compound, (E) It contains antioxidant.

Description

Adhesive composition and adhesive film {ADHESIVE COMPOSITION AND ADHESIVE FILM}

The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive film excellent in anti-cloudiness, which are not clouded even when the pressure-sensitive adhesive layer is thickly coated, even if left to stand for a long time in an atmosphere of high temperature and high humidity.

In recent years, in various displays, such as a liquid crystal panel and an organic electroluminescent panel, various optical films and a protective plate are affixed on the front surface of a display. On the front surface of a display, the touch panel which can perform a function operation of a display by touch of a finger with respect to a screen, and the anti-reflective film etc. for preventing external light from shining on the surface of a touch panel, for example are stuck. By using these films as an optical film for a display, the improvement of the operation function of a display, and the image state of an image are aimed at.

Moreover, in the mobile telephone in which a liquid crystal panel is used as a display display, the protective plate for shock absorption is mounted in the front surface of a liquid crystal panel through the air layer for the crack prevention of a liquid crystal panel. However, in recent years, in order to reduce weight, improve thickness, and improve visibility, bonding a thin protective plate directly using an adhesive layer is performed, without forming an air layer in the front surface of the liquid crystal panel of a mobile telephone.

Said optical film and protective plate are bonded together on the front surface of a display using an adhesive layer. However, when bonding various optical films to a display using an adhesive layer, air bubbles were mixed and there existed a problem that a micro bubble generate | occur | produced in an adhesive layer.

Moreover, in the performance test of the display performed before shipment of a display display apparatus, it is necessary to pass the endurance test under the environmental conditions in the high temperature and high humidity performed using oven. However, when the optical film was bonded together using the adhesive layer which did not improve the anti-cloudiness performance, after taking out from the oven, the adhesive layer became cloudy and the product value of the display was impaired.

Thus, when an optical film is bonded to a display using an adhesive tape, when a bubble is generated in an adhesive layer, when the durability test is carried out under environmental conditions of high temperature and high humidity using an oven using the display, and In order to solve the problem that turbidity arises in an adhesive layer after taking out from an oven, various attempts have been made conventionally.

For example, Patent Document 1 discloses a pressure-sensitive adhesive optical film using a pressure-sensitive adhesive layer that improves the repair performance when a dent occurs on the surface of the pressure-sensitive adhesive layer and prevents bubbles from mixing. Specifically, the weight ratio of the alkyl (meth) acrylate having 7 to 18 carbon atoms of the alkyl group and the hydroxyl group-containing monomer is 100: 0.01 to 5 and contains a compound having two or more functional groups reacting with the hydroxyl group. It is an adhesive layer formed by the crosslinked material of a composition. After bonding an optical film to glass using this adhesive layer (thickness 20 micrometers), it is left to stand for 5 minutes in 50 degreeC * 0.05 MPa atmosphere, and by the method of visually confirming the presence or absence of the micro bubble generation in an adhesive layer. Although the presence or absence of bubbles is examined, it is described that the generation of micro bubbles can be prevented.

In addition, Patent Document 2 discloses a resin composition containing an acrylic acid derivative, an acrylic acid derivative polymer, and a high molecular weight crosslinking agent for shock absorption required for protection of an image display device or the like. It is useful for preventing cracks in an image display panel or relieving stress and impact, and is said to be excellent in transparency.

As a moisture absorption test, it carried out by putting the resin sheet shape | molded in the frame of depth 0.5mm in 50 degreeC and the high temperature and high humidity test tank of 90% RH for 50 hours, and confirmed by the method of evaluating by visual observation, and when it is this resin composition, foaming is few. Excellent transparency is described.

In addition, Patent Document 3 discloses an adhesive layer for an electronic display having excellent heat and heat resistance. Specifically, the adhesive composition for electronic displays containing the copolymer and / or mixture of a (meth) acrylic-acid alkylester monomer and a carboxyl group-containing monomer is used. Moreover, it is an adhesive composition for electronic displays containing the monomer which has an alkyleneoxy group, and the hydroxyl group containing (meth) acrylic acid ester monomer.

As a hygroscopic test, the laminated body bonded to the glass plate via the adhesive layer (200 micrometers in thickness) laminated | stacked on the resin film was left to stand in 60 degreeC and 90% RH environment for 120 hours, and then left for 30 minutes at normal temperature (25 degreeC). After that, the haze value is measured to determine the transparency of the laminate. According to this adhesive composition, even after leaving under high temperature and high humidity, foaming is small and high transparency can be maintained.

Japanese Unexamined Patent Publication No. 2003-262729 Japanese Unexamined Patent Publication No. 2008-248221 Japanese Unexamined Patent Publication No. 2008-001739

Conventionally, in order to solve the problem that the optically applied adhesive layer thickly coated after being left in an atmosphere of high temperature and high humidity increases the content of the copolymerization monomer containing a hydroxyl group of the acrylic polymer included in the adhesive composition, alkoxy Corresponding to increasing the content of hydrophilic monomers such as increasing the content of group-containing monomers has been made. By the way, when the quantity of the hydrophilic monomer in an acryl-type polymer is increased too much, new problems, such as adversely affecting the performance of an actual adhesive layer, such as durability of an adhesive layer and adhesive force fall, have arisen.

This invention makes it a subject to provide the adhesive composition and adhesive film which are excellent in the cloudiness | prevention prevention property which does not become cloudy even if the adhesive layer is thickly apply | coated, even if it is left in a high temperature and high humidity atmosphere for a long time.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said subject, by adding a diester compound to an acryl-type adhesive composition, the present inventors can form the adhesive layer in the state which disperse | distributed many hydrophilic groups, and makes an adhesive layer into the atmosphere of high temperature and high humidity. After leaving to stand, it was found that the phenomenon in which the pressure-sensitive adhesive layer was cloudy could be suppressed, and the present invention was completed.

That is, in the adhesive composition which concerns on this invention, instead of avoiding large increase in the content rate of the copolymerizable monomer containing the hydroxyl group contained in an acryl-type polymer, it has non-copolymerization property and is a polyalkylene oxide which is a hydrophilic group. The diester compound which has a structure is contained. This invention prevents the fall of the durability and adhesive force of the adhesive layer which bridge | crosslinked the said adhesive composition by this, and the adhesive excellent in the anti-cloudiness performance which does not become cloudy even if it left for a long time in the atmosphere of high temperature and high humidity. It is technical idea to obtain a composition.

In addition, the adhesive composition which concerns on this invention contains antioxidant in order to suppress that an adhesive layer is oxidized and yellowing (increase of b ^* value).

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention is an adhesive composition containing an acrylic polymer and a crosslinking agent, Comprising: The said acrylic polymer is 100 weight in total of at least 1 sort (s) or more of the (meth) acrylic acid ester monomer whose C1-C18 carbon number of (A) alkyl group. As a monomer group which can be copolymerized with respect to a part, the copolymer whose weight average molecular weight which copolymerized at least 1 or more types of copolymerizable monomers containing (B) hydroxyl group in the ratio of 0.1-10 weight part is 200,000-2 million acid value is 5.0 or less. It is an acrylic polymer which consists of a, and the said adhesive composition is further a following formula (1)

R ¹ COO- (R ³ -O) _n -CO-R ² (1)

(C) diester compound represented by (wherein R ¹ and R ² each represent an alkyl group having 4 to 17 carbon atoms, R ³ represents an alkylene group having 2 to 5 carbon atoms, and n represents an integer of 3 to 25). At least 1 sort (s) or more, and (D) isocyanate compound as said crosslinking agent, and (E) At least 1 sort (s) of compound chosen from antioxidant group which consists of phenolic antioxidant and phosphite antioxidant as antioxidant And 100 weight part of said acrylic polymers, The said (E) antioxidant is contained in the ratio of 0.01-1.0 weight part, The adhesive composition characterized by the above-mentioned is provided.

Moreover, it is preferable that the weight average molecular weights of the said (C) diester compound are 300-1,200, and contain the said (C) diester compound in the ratio of 0.1-20 weight part with respect to 100 weight part of said acrylic polymer.

Moreover, in the adhesive layer whose coating thickness formed by crosslinking the said adhesive composition is 175 micrometers, the haze value of the said adhesive layer was 1.0% or less, and the said adhesive layer was left to stand for 240 hours in 85 degreeC and 85% RH atmosphere. Then, it is preferable that the haze value of the said adhesive layer at the time of taking out to room temperature environment is more than 0.0% and 4.0% or less, and b ^* value is more than 0.0 and 0.5 or less.

The copolymerizable monomer containing the said (B) hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl It is preferable that it is at least 1 sort (s) or more selected from the compound group which consists of (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide. .

As a copolymerizable monomer which contains a carboxyl group in the said copolymerizable monomer group, (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid And at least one selected from the group consisting of carboxypolycaprolactone mono (meth) acrylates and 2- (meth) acryloyloxyethyl tetrahydrophthalic acid.

The pressure-sensitive adhesive composition further comprises an ionic compound which is solid at a temperature of 25 ° C. having a melting point of 25 ° C. or higher as an antistatic agent, and the ionic compound has a cationic component of pyridinium, imidazolium, sulfonium, and phosphonium. , An ionic compound selected from the group of cations consisting of pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, piperidinium, and pyrazollium, and the charge is based on 100 parts by weight of the acrylic polymer. It is preferable to contain the inhibitor in the ratio of 0.01-5 weight part, and the surface resistivity of the adhesive layer which crosslinked the said adhesive composition is 1.0 * 10 + ^{11 (} ohm) / square or less.

The isocyanate compound (D) is isocyanurate of hexamethylene diisocyanate compound, isocyanurate of isophorone diisocyanate compound, adduct of hexamethylene diisocyanate compound, adduct of isophorone diisocyanate compound , Burette body of hexamethylene diisocyanate compound, burette body of isophorone diisocyanate compound, isocyanurate body of tolylene diisocyanate compound, isocyanurate body of xylene diisocyanate compound, isocyanur of hydrogenated xylylene diisocyanate compound At least one trifunctional isocyanate compound selected from the group consisting of late bodies, adducts of tolylene diisocyanate compounds, adducts of xylylene diisocyanate compounds, and adducts of hydrogenated xylylene diisocyanate compounds. It is preferable to contain the said (D) isocyanate compound in the ratio of 0.01-5 weight part with respect to 100 weight part of reamers.

Moreover, this invention laminated | stacked the adhesive layer which bridge | crosslinked the said adhesive composition on one surface of a resin film, The adhesive film characterized by the above-mentioned.

Moreover, this invention provides the adhesive film whose thickness of the said adhesive layer used for bonding of a polarizing plate and an in-cell panel is 5-25 micrometers.

Moreover, this invention provides the adhesive film whose thickness of the said adhesive layer used for bonding of the polarizing plate and panel which one side of a protective film is a COP film is 5-25 micrometers.

Moreover, this invention provides the optical film for touch panels whose thickness of the said adhesive layer in which said adhesive film was used is 25-250 micrometers.

Moreover, this invention provides the optical film with an adhesive in which the adhesive layer which bridge | crosslinked the said adhesive composition was laminated | stacked on at least one surface of an optical film.

According to this invention, even if the adhesive layer is thickly apply | coated, the adhesive composition and adhesive film which are excellent in the cloudiness prevention performance which do not become cloudy even if it is left to stand for a long time in the atmosphere of high temperature and high humidity can be provided.

Moreover, since the adhesive layer using the adhesive composition which concerns on this invention contains antioxidant, it is suppressed that the adhesive layer is oxidized and yellowing (increase of b ^* value).

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on preferable embodiment.

The adhesive composition which concerns on this invention is an adhesive composition containing an acrylic polymer and a crosslinking agent, Comprising: The said acrylic polymer is 100 weight part of at least 1 sort (s) or more of the (meth) acrylic acid ester monomers of C1-C18 of the (A) alkyl group. As an copolymerizable monomer group, (B) The acrylic type which consists of a copolymer whose weight average molecular weight which copolymerized at least 1 or more types of copolymerizable monomers containing a hydroxyl group in the ratio of 0.1-10 weight part is 5.0 or less 200,000-2 million. It is a polymer, The said adhesive composition is further a following formula (1)

R ¹ COO- (R ³ -O) _n -CO-R ² (1)

(C) diester compound represented by (wherein R ¹ and R ² each represent an alkyl group having 4 to 17 carbon atoms, R ³ represents an alkylene group having 2 to 5 carbon atoms, and n represents an integer of 3 to 25). At least 1 sort (s) or more, and (D) isocyanate compound as said crosslinking agent, and (E) At least 1 sort (s) of compound chosen from antioxidant group which consists of phenolic antioxidant and phosphite antioxidant as antioxidant It is characterized by containing the said (E) antioxidant in the ratio of 0.01-1.0 weight part with respect to 100 weight part of said acrylic polymer.

The pressure-sensitive adhesive composition according to the present invention contains an acrylic polymer as the pressure-sensitive adhesive polymer. Especially as an acryl-type polymer, the copolymer which has at least 1 sort (s) or more of the (meth) acrylic acid ester monomer whose carbon number of (A) alkyl group is C1-C18 is preferable.

(A) As a (meth) acrylic acid ester monomer whose C1-C18 carbon number of an alkyl group is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (Meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acryl Laten, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (Meth) acrylate etc. are mentioned. The alkyl group of the alkyl (meth) acrylate monomer may be linear, branched or cyclic, or may have an aromatic group.

The carbon number of the alkyl group (aralkyl group) which has an aromatic group is computed by adding the carbon number of an aromatic group. For example, in the case of benzyl (meth) acrylate, carbon number of an alkyl group shall be C7 like carbon number of a benzyl group.

(B) As a monomer which can be copolymerized containing a hydroxyl group, hydroxyl-containing (meth) acrylic acid ester, hydroxyl-containing (meth) acrylamide, etc. are mentioned. As these specific examples, 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , At least one or more selected from the group of compounds consisting of N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide and the like is preferable.

(A) 0.1-10 weight part of at least 1 sort (s) or more of the copolymerizable monomer containing a hydroxyl group (B) with respect to 100 weight part of at least 1 sort (s) or more of the (meth) acrylic acid ester monomers of C1-C18 alkyl group. It is preferable to copolymerize in a ratio, It is more preferable to copolymerize in the ratio of 0.2-9.5 weight part, It is especially preferable to copolymerize in the ratio of 0.6-9.0 weight part, It is most preferable to copolymerize in the ratio of 1.2-8.5 weight part.

In the monomer group which can be copolymerized, the monomer which can further copolymerize containing a carboxyl group can also be used together. As a specific example of the copolymerizable monomer containing a carboxyl group, (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- ( Meta) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypoly At least 1 sort (s) chosen from the compound group which consists of caprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyl tetrahydrophthalic acid, etc. are mentioned.

It is preferable to adjust content of the copolymerizable monomer containing a carboxyl group according to the acid value of an acryl-type polymer. The acrylic polymer may be a copolymer obtained by copolymerizing a copolymerizable monomer containing a carboxyl group, or may be a copolymer which does not copolymerize a copolymerizable monomer containing a carboxyl group. The acid value of the acrylic polymer is preferably 5.0 or less, more preferably 3.0 or less, and most preferably 2.0 or less.

Monomers, such as the (meth) acrylic acid ester monomer whose C1-C18 alkyl group of the said (A) alkyl group and the copolymerizable monomer containing the (B) hydroxyl group, comprise an adhesive polymer which becomes a subject of an adhesive as an acrylic polymer. The manufacturing method of an acryl-type polymer is not specifically limited, A suitable polymerization method, such as solution polymerization, block polymerization, suspension polymerization, emulsion polymerization, can be used. As an average molecular weight of an acryl-type polymer, the inside of the range of 200,000-2 million of a weight average molecular weight is preferable.

The adhesive composition which concerns on this invention contains the (C) diester compound in order to reduce the cloudiness of the adhesive layer in atmosphere of high temperature and high humidity. The diester compound (C) preferably has hydrophilicity by having a polyalkylene oxide structure. Such a (C) diester compound is a polyalkylene glycol derivative (polyether compound), and the hydroxyl groups at both ends of the polyalkylene glycol are diesterized by an esterification reaction with a saturated fatty acid. For this reason, it does not react with (D) isocyanate compound and it is excellent also in compatibility with an acryl-type polymer. Although content of (C) diester compound is not specifically limited, It is preferable to contain the (C) diester compound in the ratio of 0.1-20 weight part with respect to 100 weight part of acrylic polymer, and it is the ratio of 0.2-16 weight part It is more preferable to contain it, It is especially preferable to contain in the ratio of 0.6-14 weight part, It is most preferable to contain in the ratio of 1.1-12 weight part.

As a (C) diester compound, following formula (1)

R ¹ COO- (R ³ -O) _n -CO-R ² (1)

Preferred are compounds represented by (wherein R ¹ and R ² each represent an alkyl group having 4 to 17 carbon atoms, R ³ represents an alkylene group having 2 to 5 carbon atoms, and n represents an integer of 3 to 25).

R ¹ and R ² may be the same alkyl group or different alkyl groups. Examples of the alkyl group represented by R ¹ or R ² include n-butyl group [pentanoate], isobutyl group [3-methylbutanoate], 1-methylpropyl group [2-methylbutanoate], and s-butyl Group [2-ethylpropanoate], pentyl group [hexanoate], 2-methylbutyl group [2-methylpentanoate], 1-ethylpropyl group [2-ethylbutyrate], hexyl group [heptanoate ], 1-methylpentyl group [2-methylhexanoate], 2-methylpentyl group [3-methylhexanoate], 4-methylpentyl group [5-methylhexanoate], 2-ethylbutyl group [ 2-ethylpentanoate], heptyl group [octanoate], 1-ethylpentyl group [2-ethylhexanoate], 2,3-dimethylpentyl group [3,4-dimethylhexanoate], 2, 4-dimethylpentyl group [3,5-dimethylhexanoate], 3,4-dimethylpentyl group [4,5-dimethylhexanoate], nonyl group [decanoate], undecyl group [laurate], tree Decyl group [myristate], pentadecyl group [palmitate], heptadecyl group [stearate], etc. are mentioned. The. Here, the name shown in parentheses of [] represents the name of the ester represented by a R ¹ COO group or a R ² COO group.

Since R ¹ and R ² are both saturated hydrocarbon groups and do not copolymerize with an acrylic polymer, they are easily distributed evenly in the pressure-sensitive adhesive composition.

Examples of the alkylene group represented by R ³ include an ethylene group (-CH ₂ CH _2- ), a propylene group (-CH ₂ CH (CH ₃ )-), a trimethylene group (-CH ₂ CH ₂ CH _2- ), and a butylene group (-CH ₂ CH ₂ CH (CH ₃ )-), tetramethylene group (-CH ₂ CH ₂ CH ₂ CH _2- ), isoprene group (-CH ₂ C (CH ₃ ) = CHCH _2- ), pentylene group ( _{-CH 2 CH 2 CH 2 CH (} CH 3) -), pentamethylene group _{(-CH 2 CH 2 CH 2 CH} 2 CH 2 -) and the like. Although R <^3> may be a saturated alkylene group or unsaturated alkylene group, it is preferable that R <^3> is a saturated alkylene group. When R ³ is an unsaturated alkylene group, in the -OR ³ -O- structure, a 2-butenylene group (-CH ₂ CH = CHCH _2- ) or an isoprene group (-CH ₂ ) in which an unsaturated carbon atom does not bond to an oxygen atom. It is preferable that C (CH ₃ ) = CHCH _2- ).

n is a repeating number of an alkyleneoxy group (R ³ -O), and is an integer of 3-25. When the value of n is large, hydrophilicity is increased and it is preferable in the improvement of the cloudiness prevention performance under environmental conditions at high temperature and high humidity. However, when the value of n is too big | large, there exists a possibility that the cloudiness of an adhesive layer may increase rather than absorbing moisture in air | atmosphere, even if it does not pass through the environmental conditions at high temperature and high humidity. For this reason, it is preferable that n is 25 or less.

(C) The diester compound may be a mixture of polyalkylene glycol diesters having the same R ³ and different n. In the same molecule, n R ^{3 's} may be the same as or different from each other. (C) When diester compound is a mixture, it is preferable that n of each component (whole component or main component) is an integer within the range of 3-25, or the average value of n is a number within the range of 3-25. When n is an average value, the value of n may be non-integer. The average value of n may be a calculated value based on average molecular weight, such as a number average molecular weight and a weight average molecular weight. It is preferable that the weight average molecular weight of (C) diester compound is 300-1,200.

The (C) diester compound according to the present invention is an ester of a polyalkylene glycol and a saturated fatty acid, and a saturated fatty acid having a hydroxyl group at both ends of the polyalkylene glycol having 5 to 18 carbon atoms (with an alkyl group other than a carboxyl group having 4 to 17 carbon atoms). It is preferable that it is diesterized by esterification with. Moreover, as a specific example of (C) diester compound, for example, polyethyleneglycol-di-2-ethylpropanoate, polyethyleneglycol-di-2-ethylbutyrate, polyethyleneglycol di-2-ethylhexanoate , Polyethyleneglycol-di-octanoate, polyethyleneglycol-di-2-methylpentanoate, polyethyleneglycol-di-2-methylbutanoate, polyethyleneglycol-di-3-methylbutanoate, polyethyleneglycol-di 2-methylhexanoate, polyethylene glycol-di-2-ethylpentanoate, ester of polyethylene glycol and 2-ethylpropanoic acid, 2-ethylhexanoic acid, polyethylene glycol and 2-methylhexanoic acid, 2-ethylphene Esters of carbonic acid, esters of polyethylene glycol and 3-methylhexanoic acid, 5-methylhexanoic acid, esters of polyethylene glycol and 2-methylhexanoic acid, 2-ethylhexanoic acid, polyethylene glycol and 3,5-dimethylhexanoic acid , 5-dimethylhexanoic acid Acid esters, polyethylene glycol-di-stearate, polypropylene glycol-di-2-ethylpropanoate, polypropylene glycol-di-2-ethylbutyrate, polypropylene glycol-di-2-ethylhexanoate, poly Propylene glycol-di-octanoate, polypropylene glycol-di-2-methylpentanoate, polypropylene glycol-di-2-methylbutanoate, polypropylene glycol-di-3-methylbutanoate, polypropylene Glycol-di-2-methylhexanoate, polypropylene glycol-di-2-ethylpentanoate, ester of polypropylene glycol and 2-ethylpropanoic acid and 2-ethylhexanoic acid, polypropylene glycol and 2-methylhexane Ester of acid, 2-ethylpentanoic acid, ester of polypropylene glycol and 3-methylhexanoic acid, 5-methylhexanoic acid, ester of polypropylene glycol, 2-methylhexanoic acid, 2-ethylhexanoic acid, polypropylene glycol, 3,5-dimethylhexane 4,5-dimethylhexanoic acid, esters of 3,4-dimethylhexanoic acid, polypropylene glycol-di-stearate, polyisopreneglycol-di-2-ethylpropanoate, polyisopreneglycol-di-2-ethyl Butyrate, Polyisopreneglycol-di-2-ethylhexanoate, Polyisopreneglycol-di-octanoate, Polyisoprenglycol-di-2-methylpentanoate, Polyisoprenglycol-di-2-methylbutanoate , Polyisopreneglycol-di-3-methylbutanoate, polyisopreneglycol-di-2-methylhexanoate, polyisoprenglycol-di-2-ethylpentanoate, polyisopreneglycol and 2-ethylpropanoic acid Ester of 2-ethylhexanoic acid, ester of polyisopreneglycol and 2-methylhexanoic acid and 2-ethylpentanoic acid, ester of polyisopreneglycol and 3-methylhexanoic acid and 5-methylhexanoic acid, polyisopreneglycol and 2- Methylhexanoic acid, ester of 2-ethylhexanoic acid, poly Ester of isoprene glycol, 3,5-dimethylhexanoic acid, 4,5-dimethylhexanoic acid, 3,4-dimethylhexanoic acid, and polyisoprene glycol-di-stearate.

The pressure-sensitive adhesive composition according to the present invention includes a crosslinking agent for crosslinking the acrylic polymer when forming the pressure-sensitive adhesive layer. As a crosslinking agent, a bifunctional or more isocyanate compound is mentioned. Although content of a crosslinking agent is not specifically limited, It is preferable to contain (D) isocyanate compound in the ratio of 0.01-5 weight part with respect to 100 weight part of acrylic polymer, and it is more preferable to contain it in the ratio of 0.02-3 weight part. Do.

(D) As an isocyanate compound, the isocyanurate of the hexamethylene diisocyanate compound, the isocyanurate of the isophorone diisocyanate compound, the adduct of the hexamethylene diisocyanate compound, the adduct of the isophorone diisocyanate compound Sieve, biuret body of hexamethylene diisocyanate compound, biuret body of isophorone diisocyanate compound, isocyanurate body of tolylene diisocyanate compound, isocyanurate body of xylylene diisocyanate compound, isocyanate of hydrogenated xylene diisocyanate compound At least one trifunctional isocyanate compound selected from an anurate body, an adduct of a tolylene diisocyanate compound, an adduct of a xylene diisocyanate compound and an adduct of a hydrogenated xylene diisocyanate compound is preferable.

The pressure-sensitive adhesive composition according to the present invention contains (E) at least one compound selected from the group of antioxidants consisting of phenolic antioxidants and phosphite antioxidants. Although content of (E) antioxidant is not specifically limited, It is preferable to contain (E) antioxidant in the ratio of 0.01-1.0 weight part with respect to 100 weight part of acrylic polymer, and it contains it in the ratio of 0.02-1.0 weight part. It is more preferable to carry out, It is especially preferable to contain in the ratio of 0.02-0.8 weight part, It is most preferable to contain in the ratio of 0.04-0.7 weight part. By adding (E) antioxidant to the adhesive composition which concerns on this invention, it can suppress that an adhesive layer is oxidized and yellowing (increase of b ^* value).

As a phenolic antioxidant, 2, 6- di-t- butyl- 4-hydroxy toluene, t-butyl- p-hydroxy anisole, vitamin E (tocopherols), 2, 2- thio- diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) prop Cypionate], Octadecyl [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-t-butyl-4 -Hydroxybenzyl) -2,4,6-trimethylbenzene, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxybenzenepropanamide), 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6-trione, 1,3,5-trimethyl-2,4,6- Tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate and the like. Among the phenolic antioxidants, hindered phenolic antioxidants having a bulky alkyl group such as t-butyl group on both sides of the hydroxyl group are preferable.

Examples of the phosphite-based antioxidants include triphenyl phosphite, tricresyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, phenyl diisodecyl phosphite, Diphenylisodecylphosphite, trialkylphosphite, distearylpentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritoldiphosphite, bis2,6-di-t-butyl-4 -Methylphenyl) pentaerythritol diphosphite etc. are mentioned.

The adhesive composition which concerns on this invention may contain an antistatic agent, in order to provide antistatic property with respect to peeling charging. Although content of an antistatic agent is not specifically limited, It is preferable to contain an antistatic agent in the ratio of 0.01-5 weight part with respect to 100 weight part of acrylic polymer. When it is not necessary to provide antistatic property, the adhesive composition which concerns on this invention does not need to contain an antistatic agent.

As an antistatic agent, the ionic compound which is solid at 25 degreeC whose melting | fusing point is 25 degreeC or more is mentioned. The said ionic compound has an inorganic or organic cation and an inorganic or organic anion. As a cation of the ionic compound, a cation consisting of pyridinium, imidazolium, sulfonium, phosphonium, pyrrolidinium, guanidinium, ammonium, isuroronium, thiuronium, piperidinium, pyrazolium and the like One selected from the group is preferred. These cations may have 1 or 2 or more substituents, such as an alkyl group.

Wherein the anion of the ionic compound include hexafluoride phosphate (PF ₆ ^-), thiocyanate (SCN ^-), organic acid salts (RSO ₃ ^-), perchlorate (ClO ₄ ^-), ₄ fluoride borate (BF ₄ ^- ), bis (sulfonyl fluorophenyl) already deuyeom ^{_{[(FSO 2) 2 N -}} ], methanesulfonyl as bis (trifluoromethyl) already deuyeom _{[(CF 3 SO 2) 2} N -], bis (pentafluoroethane sulfonyl) already deuyeom _{[(C 2 F 5 SO 2} ) 2 N -] may be mentioned one selected from the group consisting of anion and the like.

When an adhesive composition contains an antistatic agent, it is preferable that the surface resistivity of the adhesive layer which bridge | crosslinked the said adhesive composition is ^{1.0x10 + 11} ohms / square or less.

The adhesive composition which concerns on this invention can further mix suitably well-known additives, such as a silane coupling agent, surfactant, a hardening accelerator, a plasticizer, a filler, a hardening retarder, a processing aid, an antioxidant, as another component. These additives can be used individually or in combination of 2 or more types.

According to the adhesive composition of this invention, as well as the outstanding transparency at the time of apply | coating the thickness of an adhesive layer thickly, it becomes possible to improve the cloudiness prevention performance at the time of putting in the atmosphere of high temperature and high humidity. In the adhesive layer whose coating thickness formed by crosslinking the said adhesive composition is 175 micrometers, it is preferable that the haze value of an adhesive layer is 1.0% or less. Moreover, after leaving the said adhesive layer whose coating thickness is 175 micrometers in the atmosphere of temperature 85 degreeC and 85% RH for 240 hours, the haze value of the said adhesive layer at the time of taking out in room temperature environment is more than 0.0% and 4.0% or less, Moreover, it is preferable that b ^* value is more than 0.0 and 0.5 or less. Here, b ^* values and L ^* a ^* b ^* color system b ^* values according to the, b ^* value is large, the amount of yellow light is stronger, the b ^* value is large, it becomes a bluish steel negatively. It is preferable that the said b ^* value is more than 0.0. Moreover, even if it apply | coats the thickness of an adhesive layer thickly, according to the adhesive composition which has the outstanding transparency, even when the thickness of an adhesive layer is thin, it has the transparency which was excellent beyond when applying thickly.

The adhesive film of this invention can laminate the adhesive layer which consists of an adhesive composition of this invention on one surface of a resin film. The adhesive film of this invention can be used for various uses, such as for a touch panel, an electronic paper, an organic EL, an optical member, and a surface protection. Although the thickness of an adhesive layer is not specifically limited, For example, it is 5-2,000 micrometers. When the thickness of the pressure-sensitive adhesive layer is too thin, the impact absorption performance deteriorates. However, when the thickness of the pressure-sensitive adhesive layer is too thick, it is disadvantageous in that the cost increases. In particular, in the case of the adhesive film for touch panels, since the thickness of an adhesive layer is 175 micrometers or more thick application | coating, since the effect of this invention is high, it is preferable. It is preferable that the thickness of the adhesive layer used for bonding between members (for example, bonding of a polarizing plate and a panel) is 5-25 micrometers. It is preferable that the thickness of the adhesive layer used for the optical film for touch panels is 25-250 micrometers.

As a resin film used as a base material of an adhesive layer, and the peeling film (separator) which protects the surface of an adhesive layer, resin films, such as a polyester film, etc. can be used. When the use of an adhesive film is a surface protection film for optics, such as a surface protection film for polarizing plates, it is preferable that a resin film and an adhesive layer have sufficient transparency. Moreover, the said adhesive film can also be used for bonding of a polarizing plate and an in-cell panel. Moreover, the said adhesive film can also be used for bonding of the polarizing plate and panel which one side of a protective film is a COP (cycloolefin polymer) film.

Moreover, the adhesive composition of this invention can be used for the laminated | multilayer film which laminated | stacked various films through the said adhesive layer. As such a film, a film for touch panels, a film for electronic paper, a film for organic EL, a film for optics, etc. are mentioned.

Moreover, the adhesive composition of this invention can also be used for the optical film with an adhesive in which the said adhesive layer is laminated | stacked on at least one surface of an optical film.

In the optical film with an adhesive, optical films, such as a polarizing plate film, a retardation film, a lens film, the polarizing plate film for both retardation plates, and the polarizing plate film for both lens films, can be used as a base film.

The optical film with an adhesive is formed by laminating an adhesive layer on one side or both sides of an optical film, and can be used for bonding with the glass plate etc. of an image display apparatus. These optical films with an adhesive are bonded together with a glass substrate etc. via an adhesive layer, and can be contained in an image display apparatus etc. It is preferable that the adhesive layer used for optical films with an adhesive, such as a polarizing plate with an adhesive, has sufficient transparency.

Example

Hereinafter, an Example is given and this invention is demonstrated concretely.

<Production of Acrylic Polymer>

Example 1

Nitrogen gas was introduce | transduced into the reaction apparatus provided with the stirrer, the thermometer, the reflux cooler, and the nitrogen inlet tube, and the air in the reaction apparatus was replaced with nitrogen gas. Thereafter, 100 parts by weight of a solvent (ethyl acetate) was added to the reaction apparatus together with 90 parts by weight of butyl acrylate, 10 parts by weight of methyl methacrylate, and 8.0 parts by weight of 8-hydroxyoctyl acrylate. Then, 0.1 weight part of azobisisobutyronitrile was dripped over 2 hours as a polymerization initiator, it was made to react at 65 degreeC for 8 hours, and the acrylic polymer solution of Example 1 of the weight average molecular weight 800,000 was obtained.

[Examples 2 to 5 and Comparative Examples 1 to 4]

Examples 2-5 and a comparative example were carried out similarly to the acryl-type polymer solution used for Example 1 except having set the composition of a monomer as Table 1 (A), (B), (F), respectively. An acrylic polymer solution of 1 to 4 was obtained. Here, (F) represents the monomer which can be copolymerized containing a carboxyl group. The weight average molecular weights of the acrylic polymer were all in the range of 200,000-2 million.

<Production of Adhesive Composition and Adhesive Film>

Example 1

For the acrylic polymer solution of Example 1, 5 parts by weight of polypropylene glycol-di-stearate (molecular weight 800), 0.3 part by weight of Coronate (registered trademark) L, and 0.1 part by weight of Irganox (registered trademark) 1010 It added at the negative ratio and stirred and mixed, and obtained the adhesive composition of Example 1.

After apply | coating this adhesive composition on the peeling film which consists of a silicone resin-coated polyethylene terephthalate (PET) film, the solvent was removed by drying at 90 degreeC and the adhesive sheet whose thickness of an adhesive layer was 175 micrometers was obtained.

Then, the adhesive sheet was transferred to the polyethylene terephthalate (PET) film, and the adhesive film of Example 1 which has a laminated structure of "PET film / adhesive layer / peeling film (PVC film coated with silicone resin)" was obtained.

[Examples 2 to 5 and Comparative Examples 1 to 4]

Except having performed an additive as respectively described in Table (C), (D), (E), (X) of Table 1, it carried out similarly to the adhesive composition and adhesive film of Example 1, and Examples 2-5. And the pressure-sensitive adhesive compositions and pressure-sensitive adhesive films of Comparative Examples 1 to 4 were obtained. Here, (X) represents an ionic compound.

In Table 1, the compounding ratio of each component shows the numerical value of the weight part which calculated | required the total of (A) and (B) as 100 weight part in parentheses.

In addition, the compound name of the abbreviation code of each component used in Table 1 is shown in Table 2. In addition, in group (D) of Table 2, HDI means hexamethylene diisocyanate and TDI means tolylene diisocyanate.

In addition, Coronate (registered trademark) L, Coronate HX, and Coronate HL are brand names of Toso Corporation. Takeate (registered trademark) D-110N is a trade name of Mitsui Chemicals Corporation. Irganox® 1010 and Irgafos® 168 are trade names of BASF Corporation.

<Test method and evaluation>

After aging the adhesive films of Examples 1-5 and Comparative Examples 1-4 in 23 degreeC and 50% RH for 7 days, the peeling film (silicone resin-coated PET film) was peeled off and the adhesive layer was expressed. It was set as the measurement sample of transmittance | permeability and surface resistivity.

Moreover, after aging the adhesive films of Examples 1-5 and Comparative Examples 1-4 in 23 degreeC and 50% RH atmosphere for 7 days, the both sides of an adhesive layer were covered with the peeling film (silicone resin-coated PET film). The sample of was taken as the measurement sample of a haze value and b ^* value.

Moreover, one side of the adhesive layer of the adhesive film which produced the thickness of an adhesive layer similarly to 25 micrometers was bonded by transfer to the polarizing plate whose one side of a protective layer is a COP film. Thereafter, the opposite side of the pressure-sensitive adhesive layer was bonded to the surface of an alkali-free glass plate (thickness 0.7 mm), and left to stand for 1 day, followed by autoclave treatment at 50 ° C., 5 atmospheres for 20 minutes, and left at room temperature for another 12 hours. The sample in the state was used as the measurement sample of adhesive force and durability.

<Measurement method of total light transmittance>

About the measurement sample of the total light transmittance obtained above, the total light transmittance of the adhesive layer was measured based on JISK7105 using the haze meter (Manufacturer: Nippon Denshoku Co., Ltd., Model: Haze Meter, NDH2000).

<Measuring method of haze value and b ^* value before and after wet heat processing>

, Haze meter for the measurement sample in the haze value, and b ^* values obtained in the above using the (:: manufactured by Nippon Denshoku Co., Ltd., form producer Haze Meter, NDH2000), followed by measuring the haze value, and b ^* values of the pressure-sensitive adhesive layer. Let this be the haze value and b ^* value before wet heat processing.

In addition, the measurement sample of a haze value and b ^* value was left to stand in a temperature of 85 degreeC and 85% RH for 240 hours, and then it was taken out to room temperature environment, and the haze value and b ^* value of the adhesive layer were measured. Let this be the haze value and b ^* value after wet heat processing.

Further, in the above measurement sample, a release film (a silicone resin coat a PET film) with but a sample of the state covered on both sides of the pressure-sensitive adhesive layer in the measurement sample of the haze value and b ^* value, haze value of the separation film itself, and b ^* The values were all small enough to be ignored.

<Measuring method of adhesive force>

The measurement sample of the adhesive force obtained above (with a 25 mm width adhesive film bonded to the surface of an alkali free glass plate) peels at a tensile speed of 0.3 m / min using a tensile tester in 180 degree direction, and measured peeling Strength was made into adhesive force (N / 25mm).

<Evaluation method of the durability>

The measurement sample of the durability obtained above was left to stand at room temperature in 250 degreeC (Dry) atmosphere for 250 hours, and it was taken out at room temperature, and it confirmed visually whether peeling from an adherend, foaming generation, etc. were observed. Evaluation criteria evaluated "(circle)" and the case where peeling and foaming were confirmed "(circle)" and the case where peeling and foaming was confirmed clearly "x" when the peeling and foaming were not confirmed at all.

<Measurement Method of Surface Resistivity>

About the measurement sample of the surface resistivity obtained above, the surface resistivity ((ohm) / square) of an adhesive layer was measured using the resistivity meter Hirestar UP-HT450 (made by Mitsubishi Chemical Analyst).

Table 3 shows the measurement results and evaluation results. Here, the surface resistivity was described by the method of making "m * 10 ^{+ n} " into "mE + n" (m is arbitrary real value and n is a positive integer).

As for the adhesive films of Examples 1-5, the transparency (when the light transmittance | permeability is 90% or more and haze value 1.0% or less) at the time of application | coating (175 micrometers) of an adhesive layer thickly, as well as the cloudiness prevention performance (The whiteness is small even after wet heat processing) The haze value after wet heat processing was more than 0.0% and 4.0% or less, and b ^* value was more than 0.0 and 0.5 or less), and the cloudiness prevention performance could be improved. Moreover, even if it was left to stand in a high temperature atmosphere for a long time, it did not peel and foamed and had durability.

In the adhesive film of the comparative example 1, the haze value and b ^* value after a wet heat process increased, and there existed a problem in the cloudiness prevention performance. This is considered to be because the adhesive composition of the comparative example 1 did not contain the (C) diester compound and (E) antioxidant.

Further, the pressure-sensitive adhesive film of Comparative Example 2 had a b ^* value after wet heat treatment, and not only had a problem in anti-clouding performance, but also had a problem in durability due to peeling and foaming when left in a high temperature atmosphere for a long time. In the pressure-sensitive adhesive composition of Comparative Example 2, by copolymerizing a large number of copolymerizable monomers containing a hydroxyl group (B) in the acrylic polymer, the increase in haze value after wet heat treatment was suppressed, but the durability was lowered, and (E It is thought that this is because an increase in b ^* value was caused because no antioxidant was contained.

In addition, the adhesive film of Comparative Example 3 had a large haze value before the moist heat treatment and a large haze value after the moist heat treatment. This is considered to be because in the adhesive composition of the comparative example 3, the n value of (C) diester compound is too big and (E) antioxidant is added too much.

Moreover, the adhesive film of the comparative example 4 is because it added excessively the compound whose n value of the (C) diester compound is too large, or the cloudiness prevention performance (the haze value after wet heat processing exceeds 0.0% 4.0 after 4.0) of wet heat processing 4.0 % Or less, and b ^* value was more than 0.0 and 0.5 or less), but the fall of durability and the fall of the adhesive force of an adhesive layer were caused.

Claims (7)

As an adhesive composition containing an acrylic polymer and a crosslinking agent,
Of the copolymerizable monomers containing (B) a hydroxyl group, the acrylic polymer is a copolymerizable monomer group for 100 parts by weight of a total of at least one or more of the (meth) acrylic acid ester monomers having C1 to C18 alkyl groups. It is an acrylic polymer which consists of a copolymer whose weight average molecular weight which copolymerized at least 1 or more types by the ratio of 0.1-10 weight part is 5.0 or less of 200,000-2 million,
The pressure-sensitive adhesive composition further, the following formula (1)
R ¹ COO- (R ³ -O) _n -CO-R ² (1)
(C) diester compound represented by (wherein R ¹ and R ² each represent an alkyl group having 4 to 17 carbon atoms, R ³ represents an alkylene group having 2 to 5 carbon atoms, and n represents an integer of 3 to 25). At least 1 sort (s), and it contains the (D) isocyanate compound as said crosslinking agent, and (E) 1 or more types of compounds chosen from the group of antioxidant which consists of phenolic antioxidant and phosphite antioxidant as antioxidant. ,
To 100 parts by weight of the acrylic polymer, the (E) antioxidant is contained in a ratio of 0.01 to 1.0 parts by weight,
In the pressure-sensitive adhesive layer having a coating thickness of 175 μm formed by crosslinking the pressure-sensitive adhesive composition, the haze value of the pressure-sensitive adhesive layer is 1.0% or less, and the pressure-sensitive adhesive layer is allowed to stand for 240 hours in an atmosphere of a temperature of 85 ° C. and 85% RH. The haze value of the said adhesive layer at the time of taking out in room temperature environment is more than 0.0%, and is 4.0% or less, and the b ^* value in L ^* a ^* b ^* colorimeter is more than 0.0 and 0.5 or less, The adhesive composition characterized by the above-mentioned. The method of claim 1,
The weight average molecular weight of the said (C) diester compound is 300-1,200, and contains the said (C) diester compound in 0.1-20 weight part with respect to 100 weight part of said acryl-type polymers, The adhesive composition characterized by the above-mentioned. . The adhesive film which laminated | stacked the adhesive composition of Claim 1 or 2 on one surface of the resin film was laminated | stacked, The adhesive film characterized by the above-mentioned. The adhesive film whose thickness of the said adhesive layer used for bonding of the polarizing plate and in-cell panel in which the adhesive film of Claim 3 was used is 5-25 micrometers. The adhesive film which is 5-25 micrometers in thickness of the said adhesive layer used for bonding of the polarizing plate and panel which one side of the protective film which used the adhesive film of Claim 3 to which is a COP film. The optical film for touch panels whose thickness of the said adhesive layer in which the adhesive film of Claim 3 was used is 25-250 micrometers. The optical film with an adhesive in which the adhesive layer which bridge | crosslinked the adhesive composition of Claim 1 or 2 is laminated | stacked on at least one surface of an optical film.