CN107868635B - Adhesive composition and adhesive film - Google Patents

Adhesive composition and adhesive film Download PDF

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Publication number
CN107868635B
CN107868635B CN201710846909.2A CN201710846909A CN107868635B CN 107868635 B CN107868635 B CN 107868635B CN 201710846909 A CN201710846909 A CN 201710846909A CN 107868635 B CN107868635 B CN 107868635B
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adhesive
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adhesive layer
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CN107868635A (en
Inventor
长仓毅
长谷川良
吉田弘幸
菱沼昌世
铃木史惠
大津贺健太郎
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Fujimori Kogyo Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C09J133/10—Homopolymers or copolymers of methacrylic acid esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/08—Macromolecular additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C09J133/062—Copolymers with monomers not covered by C09J133/06
    • C09J133/066—Copolymers with monomers not covered by C09J133/06 containing -OH groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C09J133/08—Homopolymers or copolymers of acrylic acid esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
    • C09J2301/12—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers
    • C09J2301/122—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers the adhesive layer being present only on one side of the carrier, e.g. single-sided adhesive tape
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2467/00—Presence of polyester
    • C09J2467/006—Presence of polyester in the substrate

Abstract

The invention provides an adhesive composition and an adhesive film, wherein the adhesive composition does not generate white turbidity and has excellent white turbidity prevention performance even if the adhesive composition is placed in a thick adhesive layer and is placed in a high-temperature and high-humidity atmosphere for a long time. The adhesive composition comprises an acrylic polymer formed by a copolymer obtained by copolymerizing at least one or more (meth) acrylate monomers having C1-18 carbon atoms and having a weight average molecular weight of 20-200 ten thousand and an acid value of 5.0 or less with respect to 100 parts by weight of the total (A) alkyl group, and at least one or more (B) hydroxyl group-containing copolymerizable monomer at a ratio of 0.1-10 parts by weight; r1COO‑(R3‑O)n‑CO‑R2At least one of the (C) diester compounds represented by (A), R1、R2Represents an alkyl group having 4 to 17 carbon atoms, R3An alkylene group having 2 to 5 carbon atoms, wherein n represents an integer of 3 to 25; (D) an isocyanate compound and (E) an antioxidant.

Description

Adhesive composition and adhesive film
Technical Field
The invention provides an adhesive composition and an adhesive film, wherein the adhesive composition does not generate white turbidity and has excellent white turbidity prevention performance even if the adhesive composition is coated with a thick adhesive layer and is placed in a high-temperature and high-humidity atmosphere for a long time.
Background
In recent years, various displays such as liquid crystal panels and organic electroluminescence panels have various optical films and protective plates attached to the front surface of the displays. A touch panel that can perform functional operations of the display by a touch of a finger on a screen, an antireflection film for preventing external light from being reflected on the surface of the touch panel, and the like are attached to the front surface of the display, for example. By using these films as optical films for displays, the operating functions of displays are improved and the image quality of images is improved.
In a mobile phone in which a liquid crystal panel is used as a display, a protective plate for absorbing impact is attached to the front surface of the liquid crystal panel with an air layer interposed therebetween in order to prevent cracking of the liquid crystal panel. Recently, however, in order to achieve weight reduction, thickness reduction, and improvement in visibility, a protective plate is directly bonded to a liquid crystal panel of a mobile phone using an adhesive layer without providing an air layer on the front surface of the liquid crystal panel.
The optical film and the protective plate are bonded to the front surface of the display using an adhesive layer. However, when various optical films are bonded to a display using an adhesive layer, bubbles are involved, and fine bubbles are generated in the adhesive layer.
In the performance test of the display device performed before shipment, the durability test under the high-temperature and high-humidity environmental conditions performed using the oven must be passed. However, when an optical film is bonded using an adhesive layer whose cloudiness prevention performance is not improved, there is a problem that cloudiness occurs in the adhesive layer after being taken out from an oven, and the commercial value of a display is damaged.
As described above, in order to solve the problem that fine bubbles are generated in the adhesive layer when the optical film is bonded to the display using the adhesive tape; or when a durability test is performed on a display under an environmental condition of high temperature and high humidity using an oven, or when the display is taken out of the oven, there has been a problem that cloudiness occurs in an adhesive layer, and various efforts have been made.
For example, patent document 1 discloses an adhesive optical film using an adhesive layer that improves the repair performance when a depression is generated on the surface of the adhesive layer and prevents the inclusion of air bubbles. Specifically disclosed is an adhesive agent layer which is composed of a polymer and a crosslinked product of a composition, wherein the polymer contains an alkyl (meth) acrylate having an alkyl group and 7-18 carbon atoms and a hydroxyl group-containing monomer in a weight ratio of 100: 0.01-5, and the composition contains a compound having 2 or more functional groups that react with hydroxyl groups. It is described that: the optical film was bonded to glass using the adhesive layer (thickness: 20 μm), and then left for 5 minutes in an atmosphere of 50 ℃x0.05 MPa, and the presence or absence of fine bubbles was checked by a method of visually checking the presence or absence of fine bubbles in the adhesive layer, thereby preventing the occurrence of fine bubbles.
Further, patent document 2 discloses a resin composition for absorbing impact necessary for protecting an image display device or the like, the resin composition containing an acrylic derivative, an acrylic derivative polymer, and a high molecular weight crosslinking agent. The transparent conductive film is useful for preventing cracks, stress, and impact in an image display panel, and has excellent transparency.
It is described that: the resin sheet formed by a frame having a depth of 0.5mm was placed in a high temperature and high humidity test chamber at 60 ℃ and 90% RH for 50 hours to perform a moisture absorption test, and the results were confirmed by a method of evaluation by visual observation.
Further, patent document 3 discloses an adhesive layer for an electronic display having excellent moist heat resistance. Specifically, an adhesive composition for electronic displays comprising a copolymer and/or a mixture of an alkyl (meth) acrylate monomer and a carboxyl group-containing monomer is used. An adhesive composition for electronic displays, characterized by further comprising a monomer having an alkyleneoxy group and a (meth) acrylate monomer having a hydroxyl group.
As a moisture absorption test, a laminate which was bonded to a glass plate via an adhesive layer (thickness: 200 μm) laminated on a resin film was left at 60 ℃ and 90% RH for 120 hours, then left at room temperature (25 ℃) for 30 minutes, and then the haze value was measured to determine the transparency of the laminate. According to the adhesive composition, even after being placed under high temperature and high humidity, foaming is little, and high transparency can be maintained.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2003-262729
Patent document 2: japanese patent laid-open No. 2008-248221
Patent document 3: japanese patent laid-open No. 2008-001739
Disclosure of Invention
Technical problem to be solved by the invention
Conventionally, in order to solve the problem that a thick-coated optical adhesive layer is clouded after being left standing in a high-temperature and high-humidity atmosphere, measures have been taken to increase the content of a hydrophilic monomer, such as increasing the content of a hydroxyl group-containing comonomer in an acrylic polymer contained in an adhesive composition and increasing the content of an alkoxy group-containing monomer. However, if the amount of the hydrophilic monomer in the acrylic polymer is excessively increased, new problems occur such as a decrease in durability and adhesive force of the adhesive agent layer, and an adverse effect on the performance of the actual adhesive agent layer.
The invention aims to provide an adhesive composition and an adhesive film, wherein the adhesive composition does not generate white turbidity and has excellent white turbidity prevention performance even if the adhesive composition is thickly coated with an adhesive layer and is placed in a high-temperature and high-humidity atmosphere for a long time.
Means for solving the problems
The present inventors have intensively studied to solve the above-mentioned problems, and as a result, they have found that an adhesive layer in which a large number of hydrophilic groups are dispersed can be formed by adding a diester (diester) compound to an acrylic adhesive composition, and that a phenomenon in which the adhesive layer is clouded after the adhesive layer is left in an atmosphere of high temperature and high humidity can be suppressed, and have completed the present invention.
That is, the pressure-sensitive adhesive composition of the present invention avoids a significant increase in the content of the hydroxyl group-containing copolymerizable monomer contained in the acrylic polymer, and instead contains a diester compound having a non-copolymerizable structure and a polyalkylene oxide (polyalkylene oxide) structure as a hydrophilic group. The technical idea of the invention is that the following adhesive composition is obtained in this way: the adhesive composition prevents the reduction of durability and adhesive force of an adhesive layer formed by crosslinking the adhesive composition, and even if the adhesive layer is placed in an atmosphere with high temperature and high humidity for a long time, the adhesive layer does not generate white turbidity and has excellent white turbidity prevention performance.
Further, yellowing (b) of the adhesive layer due to oxidation is suppressed＊Value increased), the adhesive composition of the invention of the present application contains an antioxidant.
In order to solve the above-mentioned problems, the present invention provides an adhesive composition comprising an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is formed from a copolymer having a weight average molecular weight of 20 to 200 ten thousand and an acid value of 5.0 or less, the copolymer is obtained by copolymerizing at least one or more of (B) a hydroxyl group-containing copolymerizable monomer and at least one or more of (a) a (C) diester compound represented by the following formula (1), at least one or more of (C) alkyl group-containing (meth) acrylate monomers having C1 to 18 carbon atoms in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the total of (a) alkyl group-containing (meth) acrylate monomers, and the adhesive composition further comprises, The crosslinking agent is (D) an isocyanate compound and the antioxidant is (E) at least one compound selected from the group consisting of phenol antioxidants and phosphite antioxidants.
R1COO-(R3-O)n-CO-R2 (1)
Wherein R is1And R2Each represents an alkyl group having 4 to 17 carbon atoms; r3Represents an alkylene group having 2 to 5 carbon atoms; n represents an integer of 3 to 25, and the antioxidant (E) is contained in a proportion of 0.01 to 1.0 part by weight relative to 100 parts by weight of the acrylic polymer.
Further, it is preferable that: the weight average molecular weight of the (C) diester compound is 300-1200, and the (C) diester compound is contained in a proportion of 0.1-20 parts by weight relative to 100 parts by weight of the acrylic polymer.
Further, it is preferable that: in a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition and having a coating thickness of 175 [ mu ] m, the haze value of the pressure-sensitive adhesive layer is 1.0% or less, the haze value of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is left at a temperature of 85 ℃ and 85% RH for 240 hours and then taken out to a room temperature environment is more than 0.0% and 4.0% or less, and b＊The value is greater than 0.0 and 0.5 or less.
Preferably: the copolymerizable monomer containing a hydroxyl group (B) is at least one selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-methylol (meth) acrylamide and N-hydroxyethyl (meth) acrylamide.
Preferably: the group of copolymerizable monomers contains, as a carboxyl group-containing copolymerizable monomer, at least one or more selected from the group of compounds consisting of: (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxyethylmaleic acid, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid.
Preferably: the adhesive composition further contains an ionic compound having a melting point of 25 ℃ or higher and being solid at a temperature of 25 ℃ as an antioxidantAn electrostatic agent, wherein the ionic compound is selected from pyridine as a cationic component
Figure BDA0001412101030000051
Imidazole
Figure BDA0001412101030000052
Sulfonium, phosphonium, pyrrolidines
Figure BDA0001412101030000053
Guanidine (guanidine)
Figure BDA0001412101030000054
(guanidium), ammonium, isourea
Figure BDA0001412101030000055
(isouronium), thiourea
Figure BDA0001412101030000056
(thiouronium), piperidine
Figure BDA0001412101030000057
(piperadinium), pyrazoles
Figure BDA0001412101030000058
An ionic compound of one of the cation groups consisting of (pyrazolium), wherein the antistatic agent is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic polymer, and the surface resistivity of an adhesive layer formed by crosslinking the adhesive composition is 1.0X 10+11Omega/□ or less.
Preferably: the isocyanate compound (D) is at least one trifunctional isocyanate compound selected from the group consisting of an isocyanurate compound of a hexamethylene diisocyanate compound, an isocyanurate compound of an isophorone diisocyanate compound, an adduct compound of a hexamethylene diisocyanate compound, an adduct compound of an isophorone diisocyanate compound, a biuret compound of a hexamethylene diisocyanate compound, a biuret compound of an isophorone diisocyanate compound, an isocyanurate compound of a toluene diisocyanate compound, an isocyanurate compound of a xylylene diisocyanate compound, an isocyanurate compound of a hydrogenated xylylene diisocyanate compound, an adduct compound of a toluene diisocyanate compound, an adduct compound of a xylylene diisocyanate compound, and an adduct compound of a hydrogenated xylylene diisocyanate compound, the isocyanate compound (D) is contained in a proportion of 0.01-5 parts by weight relative to 100 parts by weight of the acrylic polymer.
The present invention also provides an adhesive film, wherein an adhesive layer obtained by crosslinking the adhesive composition is laminated on one surface of a resin film.
In addition, the present invention provides an adhesive film, wherein the adhesive layer for attaching a polarizer and an In-cell panel (In-cell panel) has a thickness of 5 to 25 μm.
The invention also provides an adhesive film, wherein the thickness of the polaroid and the adhesive layer of the panel, one surface of which is used for adhering the protective film is the C OP film, is 5-25 mu m.
In addition, the invention provides an optical film for a touch panel, wherein the thickness of the adhesive layer used by the adhesive film is 25-250 μm.
The present invention also provides an optical film with an adhesive, wherein an adhesive layer obtained by crosslinking the adhesive composition is laminated on at least one side of the optical film.
Effects of the invention
According to the present invention, it is possible to provide an adhesive composition which does not cause cloudiness even when left standing for a long time in a high-temperature and high-humidity atmosphere even when an adhesive layer is thickly coated, and which is excellent in cloudiness prevention performance, and an adhesive film.
Further, since the adhesive layer using the adhesive composition of the present invention contains an antioxidant, the adhesive layer can be inhibited from being oxidized and yellowing (b)＊The value increases).
Detailed Description
The present invention will be described below based on preferred embodiments.
The adhesive composition of the present invention comprises an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is formed by a copolymer with a weight average molecular weight of 20 to 200 ten thousand and an acid value of 5.0 or less, the copolymer is obtained by copolymerizing at least one or more of (B) a hydroxyl group-containing copolymerizable monomer as a copolymerizable monomer group and at least one or more of (meth) acrylate monomers with a carbon number of C1 to 18 as an alkyl group (A) at a ratio of 0.1 to 10 parts by weight relative to 100 parts by weight of at least one or more of (meth) acrylate monomers with a carbon number of C1 to 18 as an alkyl group (A), and the adhesive composition further comprises at least one or more of (C) diester compounds represented by the following formula (1), (D) an isocyanate compound as the crosslinking agent, and (E) an antioxidant selected from the group consisting of a phenol antioxidant and a phosphite antioxidant At least one compound of the antioxidant group of (1).
R1COO-(R3-O)n-CO-R2 (1)
Wherein R is1And R2Each represents an alkyl group having 4 to 17 carbon atoms; r3Represents an alkylene group having 2 to 5 carbon atoms; n represents an integer of 3 to 25, and the antioxidant (E) is contained in a proportion of 0.01 to 1.0 part by weight relative to 100 parts by weight of the acrylic polymer.
The adhesive composition of the present invention contains an acrylic polymer as an adhesive polymer. The acrylic polymer is particularly preferably a copolymer mainly composed of at least one (meth) acrylate monomer (A) having an alkyl group and having carbon atoms of C1-18.
Examples of the (meth) acrylate monomer having an alkyl group having C1 to 18 carbon atoms (a) include 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) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl (meth) acrylate. The alkyl group of the alkyl (meth) acrylate monomer may be any of a linear, branched, and cyclic alkyl group, and may have an aromatic group.
The number of carbon atoms of the alkyl group (aralkyl group) having an aromatic group is calculated by adding the number of carbon atoms of the aromatic group. For example, in the case of benzyl (meth) acrylate, the number of carbon atoms in the alkyl group is the same as the number of carbon atoms in the benzyl group, and this is C7.
Examples of the copolymerizable monomer having a hydroxyl group (B) include hydroxyl group-containing (meth) acrylates and hydroxyl group-containing (meth) acrylamides. Specific examples thereof include preferably at least one compound selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide and the like.
Preferably, at least one or more of the (B) hydroxyl group-containing copolymerizable monomer and at least one or more of the (meth) acrylate monomer having an alkyl group with a carbon number of C1 to 18 are copolymerized in a proportion of 0.1 to 10 parts by weight, more preferably in a proportion of 0.2 to 9.5 parts by weight, particularly preferably in a proportion of 0.6 to 9.0 parts by weight, and most preferably in a proportion of 1.2 to 8.5 parts by weight, relative to 100 parts by weight of the total of at least one or more of the (meth) acrylate monomers having an alkyl group with a carbon number of C1 to 18.
The copolymerizable monomer group may further contain a carboxyl group. Specific examples of the carboxyl group-containing copolymerizable monomer include at least one member selected from the group consisting of (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxyethylmaleic acid, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid and the like.
The content of the carboxyl group-containing copolymerizable monomer is preferably adjusted depending on the acid value of the acrylic polymer. The acrylic polymer may be a copolymer obtained by copolymerizing a copolymerizable monomer having a carboxyl group, or may be a copolymer obtained by not copolymerizing a copolymerizable monomer having 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.
The adhesive polymer is composed of a monomer such as (A) a (meth) acrylate monomer having an alkyl group with carbon atoms of 1-18 and (B) a hydroxyl group-containing copolymerizable monomer as a main component of the adhesive. The method for producing the acrylic polymer is not particularly limited, and an appropriate polymerization method such as solution polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization can be used. The average molecular weight of the acrylic polymer is preferably in the range of 20 to 200 ten thousand.
The adhesive composition of the present invention contains (C) a diester compound in order to reduce cloudiness of the adhesive layer in a high-temperature and high-humidity atmosphere. (C) The diester compound preferably has hydrophilicity by having a polyalkylene oxide structure. Such (C) diester compound is a polyalkylene glycol derivative (polyether compound), and the hydroxyl groups at both ends of the polyalkylene glycol are di-esterified by an esterification reaction with a saturated fatty acid. Therefore, the acrylic polymer is not reacted with the (D) isocyanate compound and is excellent in compatibility with the acrylic polymer. (C) The content of the diester compound is not particularly limited, and the diester compound (C) is preferably contained in an amount of 0.1 to 20 parts by weight, more preferably 0.2 to 16 parts by weight, particularly preferably 0.6 to 14 parts by weight, and most preferably 1.1 to 12 parts by weight, based on 100 parts by weight of the acrylic polymer.
The (C) diester compound is preferably a compound represented by the following formula (1).
R1COO-(R3-O)n-CO-R2 (1)
Wherein R is1And R2Each represents an alkyl group having 4 to 17 carbon atoms; r3Represents an alkylene group having 2 to 5 carbon atoms; n represents an integer of 3 to 25.
R1And R2They may be the same alkyl group as each other or different alkyl groups. As R1Or R2As the alkyl group, n-butyl valerate may be mentioned]Isobutyl [ 3-methylbutyrate ester]1-methylpropyl [ 2-methylbutyrate ester]Sec-butyl [ 2-ethylpropionate]Pentyl [ hexanoic acid ester]2-methylbutyl [ 2-methylpentanoate ester]1-ethylpropyl [ 2-ethylbutyrate ]]Hexyl [ heptanoate ]]1-methylpentyl [ 2-methylhexanoate]2-methylpentyl [ 3-methylhexanoate]4-methylpentyl [ 5-methylhexanoate]2-ethylbutyl [ 2-ethylpentanoate ]]Heptyl [ octanoate ]]1-ethylpentyl [ 2-ethylhexanoate]2, 3-dimethylpentyl [3, 4-dimethylhexanoate ester]2, 4-dimethylpentyl [3, 5-dimethylhexanoate ester]3, 4-dimethylpentyl [4, 5-dimethylhexanoate ester]Nonyl decanoate]Undecyl [ laurate ]]Tridecyl [ myristate ]]Pentadecyl [ palmitate ]]Heptadecyl [ stearate]And the like. Wherein, the [ alpha ], [ beta ] -a]The name represented in parentheses of (1) is represented by R1COO group or R2The name of the ester represented by COO group.
R1、R2All saturated hydrocarbon groups are easily distributed equally in the adhesive composition because they do not copolymerize with the acrylic polymer.
As R3As the alkylene group, an ethylene group (-CH) may be mentioned2CH2-), 1, 2-propylene (-CH)2CH(CH3) -) trimethylene group (-CH2CH2CH2-) butylene (-CH)2CH2CH(CH3) -) tetramethylene group (-CH2CH2CH2CH2-), prenyl (isoprene group) (-CH2C(CH3)＝CHCH2-) pentadiene pentylene (-CH2CH2CH2CH(CH3) -) pentamethylene (-CH2CH2CH2CH2CH2-) and the like. R3May be a saturated alkylene group or an unsaturated alkylene group, preferably R3Is a saturated alkylene group. At R3In the case of unsaturated alkylene radicals, at-O-R3In the-O-structure, a 2-butenylene group (-CH) in which an unsaturated carbon atom is not bonded to an oxygen atom is preferable2CH＝CHCH2-) or isoprenyl (-CH2C(CH3)＝CHCH2-)。
n is alkyleneoxy (R)3-O) is an integer of 3 to 25. When the value of n is large, hydrophilicity increases, and it is preferable for improving the white turbidity preventing performance under the high-temperature and high-humidity environmental conditions. However, if the value of n is too large, the adhesive agent layer may be clouded more by absorbing moisture or the like in the atmosphere even without passing through an environment of high temperature and high humidity. Therefore, n is preferably 25 or less.
(C) The diester compound may be R3Mixtures of identical, n-different polyalkylene glycol diesters. N R's in the same molecule3May be the same as or different from each other. When the diester compound (C) is a mixture, n of each component (total component or main component) is preferably an integer in the range of 3 to 25, or n is preferably a number in the range of 3 to 25 on average. In the case where n is an average value, the value of n may be a non-integer. The average value of n may be a calculated value of an average molecular weight based on a number average molecular weight, a weight average molecular weight, or the like. (C) The weight average molecular weight of the diester compound is preferably 300 to 1200.
The diester compound (C) of the present invention is preferably an ester of a polyalkylene glycol and a saturated fatty acid, and is preferably a diester compound obtained by esterification of hydroxyl groups at both ends of the polyalkylene glycol with a saturated fatty acid having 5 to 18 carbon atoms (the carbon atoms of the alkyl group excluding the carboxyl group being 4 to 17). Specific examples of the diester compound (C) include polyethylene glycol di-2-ethylpropionate, polyethylene glycol di-2-ethylbutyrate, polyethylene glycol di-2-ethylhexanoate, polyethylene glycol dicaprylate, polyethylene glycol di-2-methylpentanoate, polyethylene glycol di-2-methylbutyrate, polyethylene glycol di-3-methylbutyrate, polyethylene glycol di-2-methylhexanoate, polyethylene glycol di-2-ethylpentanoate, an ester of polyethylene glycol and 2-ethylpropionic acid-2-ethylhexanoic acid, an ester of polyethylene glycol and 2-methylhexanoic acid-2-ethylpentanoic acid, an ester of polyethylene glycol and 3-methylhexanoic acid-5-methylhexanoic acid, an ester of polyethylene glycol and 2-methylhexanoic acid-2-ethylhexanoic acid, Esters of polyethylene glycol with 3, 5-dimethylhexanoic acid 4, 5-dimethylhexanoic acid 3, 4-dimethylhexanoic acid, polyethylene glycol distearate, polypropylene glycol di-2-ethylpropionate, polypropylene glycol di-2-ethylbutyrate, polypropylene glycol di-2-ethylhexanoate, polypropylene glycol dioctanoate, polypropylene glycol di-2-methylvalerate, polypropylene glycol di-2-methylbutyrate, polypropylene glycol di-3-methylbutyrate, polypropylene glycol di-2-methylhexanoate, polypropylene glycol di-2-ethylvalerate, polypropylene glycol with 2-ethylpropionic acid 2-ethylhexanoic acid, polypropylene glycol with 2-methylhexanoic acid 2-ethylpentanoic acid, polypropylene glycol with 3-methylhexanoic acid 5-methylhexanoic acid, Esters of polypropylene glycol with 2-methylhexanoic acid 2-ethylhexanoic acid, esters of polypropylene glycol with 3, 5-dimethylhexanoic acid 4, 5-dimethylhexanoic acid 3, 4-dimethylhexanoic acid, polypropylene glycol distearate, polyisoprene glycol di-2-ethylpropionate, polyisoprene glycol di-2-ethylbutyrate, polyisoprene glycol di-2-ethylhexanoate, polyisoprene glycol dicaprylate, polyisoprene glycol di-2-methylvalerate, polyisoprene glycol di-2-methylbutyrate, polyisoprene glycol di-3-methylbutyrate, polyisoprene glycol di-2-methylhexanoate, polyisoprene glycol di-2-ethylvalerate, esters of polyisoprene glycol with 2-ethylpropionic acid 2-ethylhexanoic acid, esters of polypropylene glycol with 3, 5-dimethylhexanoic acid 3, 4-dimethylhexanoic acid, polypropylene glycol distearate, polyisoprene glycol di-2-ethylpropionate, polyisoprene glycol di-2-ethylbutyrate, polyisoprene glycol di-2-ethylvalerate, polyisoprene glycol di-2-ethylhexanoic acid, Esters of polyisoprene glycol with 2-methylhexanoic acid 2-ethylpentanoic acid, esters of polyisoprene glycol with 3-methylhexanoic acid 5-methylhexanoic acid, esters of polyisoprene glycol with 2-methylhexanoic acid 2-ethylhexanoic acid, esters of polyisoprene glycol with 3, 5-dimethylhexanoic acid 4, 5-dimethylhexanoic acid 3, 4-dimethylhexanoic acid, polyisoprene glycol distearate, and the like.
The adhesive composition of the present invention contains a crosslinking agent in order to crosslink the acrylic polymer at the time of forming the adhesive layer. Examples of the crosslinking agent include bifunctional or higher isocyanate compounds. The content of the crosslinking agent is not particularly limited, and the (D) isocyanate compound is preferably contained in an amount of 0.01 to 5 parts by weight, more preferably 0.02 to 3 parts by weight, based on 100 parts by weight of the acrylic polymer.
The isocyanate compound (D) is preferably selected from the group consisting of an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, an adduct of a hexamethylene diisocyanate compound, an adduct of an isophorone diisocyanate compound, a biuret of a hexamethylene diisocyanate compound, and a biuret of an isophorone diisocyanate compound, one or more trifunctional isocyanate compounds selected from the group consisting of isocyanurates of tolylene diisocyanate compounds, isocyanurates of xylylene diisocyanate compounds, isocyanurates of hydrogenated xylylene diisocyanate compounds, adducts of tolylene diisocyanate compounds, adducts of xylylene diisocyanate compounds and adducts of hydrogenated xylylene diisocyanate compounds.
The adhesive composition of the present invention contains, as the antioxidant (E), at least one compound selected from the group of antioxidants consisting of phenol antioxidants and phosphite antioxidants. (E) The content of the antioxidant is not particularly limited, and the antioxidant (E) is preferably contained in an amount of 0.01 to 1.0 part by weight, more preferably 0.02 to 1.0 part by weight, particularly preferably 0.02 to 0.8 part by weight, and most preferably 0.04 to 0.7 part by weight, based on 100 parts by weight of the acrylic polymer. By adding (E) an antioxidant to the adhesive composition of the present invention, the generation of yellowing due to oxidation of the adhesive layer can be suppressed (b)＊The value increases).
Examples of the phenolic antioxidant include 2, 6-di-t-butyl-4-hydroxytoluene, t-butyl p-hydroxyanisole, vitamin E (tocopherols), 2-thiodiethylene bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], pentaerythritol tetrakis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], 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' -hexamethylenebis (3, 5-di-t-butyl-4-hydroxybenzylamine), 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -1,3, 5-triazine-2, 4, 6-trione, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, and the like. Among the phenolic antioxidants, preferred are hindered phenolic antioxidants having tertiary butyl groups as large as an alkyl group in the same volume at both ortho-positions of the hydroxyl group.
Examples of the phosphite antioxidant include triphenyl phosphite, tricresyl phosphite, tris (nonylphenyl) phosphite, tris (2, 4-di-t-butylphenyl) phosphite, phenyldiisodecyl phosphite, diphenylisodecyl phosphite, trialkyl phosphite, distearyl pentaerythritol diphosphite, bis (2, 4-di-t-butylphenyl) pentaerythritol diphosphite, and bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite.
The adhesive composition of the present invention may also contain an antistatic agent in order to impart antistatic properties against peeling static electricity and the like. The content of the antistatic agent is not particularly limited, and the antistatic agent is preferably contained in a proportion of 0.01 to 5 parts by weight relative to 100 parts by weight of the acrylic polymer. In the case where it is not necessary to impart antistatic properties, the adhesive composition of the present invention may not contain an antistatic agent.
Examples of the antistatic agent include ionic compounds having a melting point of 25 ℃ or higher and being solid at a temperature of 25 ℃. The ionic compound has an inorganic or organic cation and an inorganic or organic anion. As the cation of the ionic compound, it is preferably selected from the group consisting of pyridine
Figure BDA0001412101030000121
Imidazole
Figure BDA0001412101030000122
Sulfonium, phosphonium, pyrrolidines
Figure BDA0001412101030000123
Guanidine (guanidine)
Figure BDA0001412101030000124
Ammonium, isourea
Figure BDA0001412101030000125
Thiourea
Figure BDA0001412101030000126
Piperidine derivatives
Figure BDA0001412101030000127
Pyrazoles
Figure BDA0001412101030000128
Etc. of a cationic group. These cations may have 1 or 2 or more substituents such as alkyl groups.
Examples of the anion of the ionic compound include a compound selected from the group consisting of hexafluorophosphates (PF)6 -) Thiocyanate (SCN)-) Organic sulfonate (RSO)3 -) Perchlorate (ClO)4 -) Tetrafluoroborate (BF)4 -) Bis (fluorosulfonyl) imide salt [ (FSO)2)2N-]Bis (trifluoromethanesulfonyl) imide salt [ (CF)3SO2)2N-]Bis (pentafluoroethanesulfonyl) imide salt [ (C)2F5SO2)2N-]Etc. of one of the anion groups.
In the case where the adhesive composition contains an antistatic agent, the surface resistivity of the adhesive layer obtained by crosslinking the adhesive composition is preferably 1.0 × 10+11Omega/□ or less.
The pressure-sensitive adhesive composition of the present invention may further contain known additives such as a silane coupling agent, a surfactant, a curing accelerator, a plasticizer, a filler, a curing retarder, a processing aid, and an antioxidant as other components. These additives may be used singly or in combination of 2 or more.
According to the adhesive composition of the present invention, not only excellent transparency can be obtained when the thickness of the adhesive layer is thick coated, but also the white turbidity preventing performance when the adhesive layer is left under an atmosphere of high temperature and high humidity can be improved. In crosslinking the adhesive compositionIn the adhesive layer formed by the above method, the coating thickness is 175 μm, and the haze value of the adhesive layer is preferably 1.0% or less. Further, it is preferable that: a haze value of the adhesive layer of more than 0.0% and 4.0% or less when the adhesive layer having a coating thickness of 175 μm is left at 85 ℃ and 85% RH for 240 hours and then taken out to a room temperature environment, and b＊The value is greater than 0.0 and 0.5 or less. Here, b＊A value of L＊a＊b＊B in the color system＊Value, if b＊A positive value of greater yellow, a stronger yellow, and b＊The value is larger in the negative direction, the blue color becomes stronger. B is＊The value is preferably greater than 0.0. In addition, according to the adhesive composition having excellent transparency even when the thickness of the adhesive layer is thick, when the thickness of the adhesive layer is thin, the adhesive composition has more excellent transparency than when the thickness is thick.
In the adhesive film of the present invention, an adhesive layer formed from the adhesive composition of the present invention may be laminated on one surface of a resin film. The adhesive film of the present invention can be used for various applications such as touch panels, electronic paper, organic electroluminescence, optical members, and surface protection. The thickness of the adhesive layer is not particularly limited, and is, for example, 5 to 2000 μm. If the thickness of the adhesive agent layer is too thin, the impact absorption performance is deteriorated, and if the thickness of the adhesive agent layer is too thick, the cost is disadvantageously increased. In particular, in the case of an adhesive film for a touch panel, when the thickness of the adhesive agent layer is thick at 175 μm or more, the effect of the present invention is high, and therefore, it is preferable. The thickness of the adhesive layer used for bonding members (for example, bonding a polarizing plate and a panel) is preferably 5 to 25 μm. The thickness of the adhesive layer used in the optical film for a touch panel is preferably 25 to 250 μm.
As the resin film to be a base material of the adhesive agent layer and the release film (separator) to protect the surface of the adhesive agent layer, a resin film such as a polyester film or the like can be used. When the application of the adhesive film is an optical surface protection film such as a surface protection film for a polarizing plate, the resin film and the adhesive layer preferably have sufficient transparency. In addition, the adhesive film can also be used for attaching a polarizer to an In-cell panel. In addition, the adhesive film can also be used for bonding a polarizing plate, one surface of which is a COP (cyclic olefin polymer) film, to a panel.
Further, the adhesive composition of the present invention can be used for a laminated film in which various films are laminated via the adhesive layer. Examples of such films include films for touch panels, films for electronic paper, films for organic electroluminescence, and films for optics.
The adhesive composition of the present invention can also be used for an optical film with an adhesive, in which the adhesive layer is laminated on at least one surface of the optical film.
As the base film, optical films such as a polarizer film, a retardation plate film, a lens film, a polarizer film for use as a retardation plate, and a polarizer film for use as a lens film can be used.
The optical film with an adhesive is an optical film with an adhesive in which an adhesive layer is laminated on one surface or both surfaces of the optical film, and is used for bonding to a glass plate or the like of an image display device. These optical films with an adhesive are bonded to a glass substrate or the like via an adhesive layer, and can be incorporated into an image display device or the like. The adhesive layer in the optical film with an adhesive used for a polarizing plate with an adhesive or the like preferably has sufficient transparency.
Examples
The present invention will be specifically described below with reference to examples.
< preparation of acrylic Polymer >
[ example 1]
Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen gas introduction tube, and the air in the reaction apparatus was replaced with nitrogen gas. Then, 90 parts by weight of butyl acrylate, 10 parts by weight of methyl methacrylate, and 8.0 parts by weight of 8-hydroxyoctyl acrylate were added to the reaction apparatus, along with 100 parts by weight of a solvent (ethyl acetate). Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and reacted at 65 ℃ for 8 hours to obtain an acrylic polymer solution of example 1 having a weight average molecular weight of 80 ten thousand.
Examples 2 to 5 and comparative examples 1 to 4
Acrylic polymer solutions of examples 2 to 5 and comparative examples 1 to 4 were obtained in the same manner as the acrylic polymer solution used in example 1 above, except that the monomer compositions were as shown in (A), (B) and (F) of Table 1. Here, (F) represents a copolymerizable monomer having a carboxyl group. The weight average molecular weight of the acrylic polymer is in the range of 20 to 200 ten thousand.
< production of adhesive composition and adhesive film >
[ example 1]
To the acrylic polymer solution of example 1, polypropylene glycol distearate (molecular weight 800) was added in a proportion of 5 parts by weight, Coronate (registered trademark) L in a proportion of 0.3 parts by weight, and IRGANOX (registered trademark) 1010 in a proportion of 0.1 parts by weight, and the mixture was stirred and mixed to obtain an adhesive composition of example 1.
This adhesive composition was applied to a release film formed of a silicone resin-coated polyethylene terephthalate (PET) film, and then dried at 90 ℃ to remove the solvent, thereby obtaining an adhesive sheet having an adhesive layer thickness of 175 μm.
Then, the adhesive sheet was transferred onto a polyethylene terephthalate (PET) film to obtain an adhesive film of example 1 having a laminated structure of "PET film/adhesive layer/release film (silicone resin-coated PET film)".
Examples 2 to 5 and comparative examples 1 to 4
Adhesive compositions and adhesive films of examples 2 to 5 and comparative examples 1 to 4 were obtained in the same manner as the adhesive composition and adhesive film of example 1 described above, except that the additives were as described in (C), (D), (E), and (X) of table 1, respectively. Here, (X) represents an ionic compound.
In table 1, the blending ratio of each component is represented by a value in parts by weight obtained by setting the total of (a) and (B) to 100 parts by weight, which is enclosed by a bracket.
In addition, the compound names of the abbreviations used in table 1 for the respective components are shown in table 2. In the group (D) in Table 2, HDI means hexamethylene diisocyanate, and TDI means toluene diisocyanate.
Further, Coronate (registered trademark) L, Coronate HX, and Coronate HL are trade names of T OSOH CORPORATION. Takenate (registered trademark) D-110N is a trade name of Mitsui Chemicals, Inc. IRGANOX (registered trademark) 1010 and irgafos (registered trademark) 168 are trade names of BASF corporation.
[ Table 1]
Figure BDA0001412101030000161
[ Table 2]
Figure BDA0001412101030000171
< test method and evaluation >
The adhesive films of examples 1 to 5 and comparative examples 1 to 4 were cured at 23 ℃ and 50% RH for 7 days, and then the release film (silicone resin-coated PET film) was peeled off, and the adhesive film with the adhesive layer exposed was used as a sample for measuring the total light transmittance and the surface resistivity.
Furthermore, the adhesive films of examples 1 to 5 and comparative examples 1 to 4 were cured at 23 ℃ under an atmosphere of 50% RH for 7 days, and then samples in a state where both surfaces of the adhesive layer were covered with a release film (a silicone resin-coated PET film) were used as the haze value and b＊Value of the test sample.
One surface of the adhesive layer of an adhesive film produced in the same manner, in which the thickness of the adhesive layer was 25 μm, was bonded to a polarizing plate, one surface of the protective layer was a COP film, by transfer. Then, the opposite surface of the adhesive layer was bonded to the surface of an alkali-free glass plate (thickness: 0.7mm), left to stand for 1 day, and then subjected to autoclave treatment at 50 ℃ and 5 atm for 20 minutes, and the sample was left to stand at room temperature for 12 hours to measure the adhesive strength and durability.
< method for measuring Total light transmittance >
The total light transmittance of the adhesive layer was measured using a Haze Meter (manufacturer: NI PPON DENSHOKU INDUSTRIES Co., LTD, type: Haze Meter, NDH2000) according to JIS K7105 for the obtained measurement sample of the total light transmittance.
< haze value before and after Wet Heat treatment and b＊Method for measuring value
For the haze values and b obtained above＊The Haze value and b of the sample for measurement of the value were measured with respect to the adhesive layer by a Haze Meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.; type: Haze Meter, NDH2000)＊The values were determined. The haze value and b before the wet heat treatment were determined＊The value is obtained.
Further, the haze value and b are calculated＊Value measurement samples were left at 85 ℃ and 85% RH for 240 hours, and then taken out to room temperature environment to measure the haze value and b of the adhesive layer＊The values were determined. Using the measured value as a haze value after a wet heat treatment and b＊The value is obtained.
In the above-described measurement samples, the haze value and b were obtained as samples in which both surfaces of the adhesive layer were covered with a release film (a PE T film coated with a silicone resin)＊The haze value of the release film itself and b＊The values were all confirmed to be small to an insignificant degree.
< method for measuring adhesive force >
The sample for measurement of the adhesive force obtained above (a sample obtained by bonding a 25mm wide adhesive film to the surface of an alkali-free glass plate) was peeled off in the 180 ° direction at a tensile speed of 0.3m/min by a tensile tester, and the peel strength obtained by the measurement was taken as the adhesive force (N/25 mm).
< method for evaluating durability >
The durability measurement sample obtained above was left to stand in an atmosphere of 80 ℃ (dry) for 250 hours, and then taken out to room temperature to visually confirm whether or not peeling from the adherend, foaming, or the like occurred. The evaluation criteria were: the case where no peeling or bubbling was observed was evaluated as "o", the case where a small amount of peeling or bubbling was observed was evaluated as "Δ", and the case where peeling or bubbling was clearly observed was evaluated as "x".
< method for measuring surface resistivity >
The surface resistivity of the adhesive layer (Ω/□) was measured with a resistivity meter HIRESTA UP-HT450 (manufactured by Mitsubishi Chemical analytical co., Ltd) for the measurement sample of the surface resistivity obtained above.
The measurement results and evaluation results are shown in table 3. In addition, the surface resistivity was determined by making "m × 10+n"m" is represented by "mE + n" (where m is an arbitrary real number and n is a positive integer).
[ Table 3]
Figure BDA0001412101030000191
And (3) moist heat treatment: the mixture was left at 85 ℃ and 85% RH for 240 hours.
The adhesive films of examples 1 to 5 had not only transparency (total light transmittance of 90% or more and haze value of 1.0% or less) when the adhesive layer was thick coated (175 μm), but also white-turbidity preventing performance (haze value after wet heat treatment of more than 0.0% and 4.0% or less, and b＊A value of more than 0.0 and 0.5 or less), the white turbidity preventing performance can be improved. Further, even when left in a high temperature atmosphere for a long time, the sheet does not peel off or foam, and has durability.
Haze value and b after Heat and humidity treatment for the adhesive film of comparative example 1＊The value is increased and the anti-clouding property is problematic. This is considered to be because the adhesive composition of comparative example 1 does not contain (C) a diester compound and (E) an antioxidant.
In addition, for the adhesive film of comparative example 2, b after the wet heat treatment＊The value is increased, and the anti-clouding property is problematic, and when the film is left to stand in a high-temperature atmosphere for a long time, peeling and foaming are observed, and the durability is problematic. This is considered to be because, in the adhesive composition of comparative example 2,although the increase in haze value after wet heat treatment can be suppressed by copolymerizing (B) a hydroxyl group-containing copolymerizable monomer in a large amount with the acrylic polymer, the decrease in durability is caused, and B is caused by not containing (E) an antioxidant＊The value is increased.
In addition, the tacky film of comparative example 3 had a large haze value before the wet heat treatment and also a large haze value after the wet heat treatment. This is considered to be because the adhesive composition of comparative example 3 had an excessively large n value of the diester compound (C) and had an excessively large amount of antioxidant (E).
In addition, in the adhesive film of comparative example 4, although the (C) diester compound having an excessively large n value was excessively added, the adhesive film also had a property of preventing white turbidity with small white turbidity after the wet heat treatment (haze value after the wet heat treatment was more than 0.0% and 4.0% or less, and b was＊A value of more than 0.0 and 0.5 or less), but causes a decrease in durability and a decrease in adhesive force of the adhesive agent layer.

Claims (10)

1. An adhesive composition comprising an acrylic polymer, a crosslinking agent and an antistatic agent,
the acrylic polymer is formed by a copolymer with a weight-average molecular weight of 20-200 ten thousand and an acid value of 5.0 or less, wherein the copolymer is formed by copolymerizing at least one or more of (B) hydroxyl-containing copolymerizable monomer as a copolymerizable monomer group and at least one or more of (A) alkyl (meth) acrylate monomer with a carbon number of C1-18 in a proportion of 1.2-8.5 parts by weight relative to 100 parts by weight of (A) alkyl (meth) acrylate monomer with at least one or more of (C1-18) alkyl (meth) acrylate monomer with a total weight,
the adhesive composition further contains at least one or more diester compounds represented by the following formula (1), (D) an isocyanate compound as the crosslinking agent, and (E) one or more compounds selected from the group consisting of phenol antioxidants and phosphite antioxidants as the antioxidants,
R1COO-(R3-O)n-CO-R2 (1)
wherein R is1And R2Each represents an alkyl group having 4 to 17 carbon atoms; r3Represents an alkylene group having 2 to 5 carbon atoms; n represents an integer of 3 to 25,
the antistatic agent is an ionic compound having a melting point of 25 ℃ or higher and being solid at a temperature of 25 ℃, the anionic component of the ionic compound is one selected from the group consisting of a bis (fluorosulfonyl) imide salt, a bis (trifluoromethanesulfonyl) imide salt and a bis (pentafluoroethanesulfonyl) imide salt,
the (C) diester compound is contained in an amount of 1.1 to 12 parts by weight, the (D) isocyanate compound is contained in an amount of 0.02 to 3 parts by weight, the (E) antioxidant is contained in an amount of 0.04 to 0.7 part by weight, and the antistatic agent is contained in an amount of 0.01 to 5 parts by weight, based on 100 parts by weight of the acrylic polymer,
the weight average molecular weight of the (C) diester compound is 300-1200,
in a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition and having a coating thickness of 175 [ mu ] m, the haze value of the pressure-sensitive adhesive layer is 1.0% or less, the haze value of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is left at a temperature of 85 ℃ and 85% RH for 240 hours and then taken out to a room temperature environment is more than 0.0% and 4.0% or less, and b＊The value is greater than 0.0 and 0.5 or less.
2. The adhesive composition according to claim 1, wherein the (B) hydroxyl group-containing copolymerizable monomer is at least one member selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-methylol (meth) acrylamide and N-hydroxyethyl (meth) acrylamide.
3. The adhesive composition according to claim 1 or 2, wherein the copolymerizable monomer group contains at least one or more selected from the group consisting of: (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxyethylmaleic acid, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid.
4. Adhesive composition according to claim 1 or 2,
the ionic compound is selected from pyridine as cation component
Figure FDA0003366797360000021
Imidazole
Figure FDA0003366797360000022
Sulfonium, phosphonium, pyrrolidines
Figure FDA0003366797360000023
Guanidine (guanidine)
Figure FDA0003366797360000024
Ammonium, isourea
Figure FDA0003366797360000025
Thiourea
Figure FDA0003366797360000026
Piperidine derivatives
Figure FDA0003366797360000027
Pyrazoles
Figure FDA0003366797360000028
Ionic compound of one of the constituent cationic groups，
The surface resistivity of the adhesive layer obtained by crosslinking the adhesive composition is 1.0 x 10+11Omega/□ or less.
5. Adhesive composition according to claim 1 or 2, the isocyanate compound (D) is at least one trifunctional isocyanate compound selected from the group consisting of an isocyanurate compound of a hexamethylene diisocyanate compound, an isocyanurate compound of an isophorone diisocyanate compound, an adduct compound of a hexamethylene diisocyanate compound, an adduct compound of an isophorone diisocyanate compound, a biuret compound of a hexamethylene diisocyanate compound, a biuret compound of an isophorone diisocyanate compound, an isocyanurate compound of a toluene diisocyanate compound, an isocyanurate compound of a xylylene diisocyanate compound, an isocyanurate compound of a hydrogenated xylylene diisocyanate compound, an adduct compound of a toluene diisocyanate compound, an adduct compound of a xylylene diisocyanate compound, and an adduct compound of a hydrogenated xylylene diisocyanate compound.
6. An adhesive film, characterized in that an adhesive layer obtained by crosslinking the adhesive composition according to any one of claims 1 to 5 is laminated on one surface of a resin film.
7. An adhesive film, wherein the thickness of the adhesive layer used for bonding a polarizer and an In-cell panel to each other is 5 to 25 μm.
8. An adhesive film, wherein the thickness of the adhesive layer of the polarizing plate and the panel, which is used for the adhesive film according to claim 6 and one surface of which is a COP film, is 5 to 25 μm.
9. An optical film for a touch panel, wherein the adhesive layer used in the adhesive film according to claim 6 has a thickness of 25 to 250 μm.
10. An optical film with an adhesive, wherein an adhesive layer obtained by crosslinking the adhesive composition according to any one of claims 1 to 5 is laminated on at least one surface of the optical film.
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