KR20210111234A - Adhesive composition, and adhesive film, surface-protective film using the same - Google Patents

Abstract

Provided is an adhesive composition that has an excellent balance of an adhesive force at a low peeling speed and a high peeling speed and can achieve both excellent antistatic performance and stain resistance and an adhesive film and a surface protective film using the same. An acrylic polymer, which is obtained by copolymerizing (A) 100 parts by weight of the total of at least two or more alkyl (meth)acrylates having an alkyl group having 1 to 10 carbon atoms; (B) 1.0-6.0 parts by weight of a hydroxyl group-containing copolymerizable monomer; and (C) 0.01-0.6 parts by weight of a carboxyl group-containing copolymerizable monomer; and has an acid value of 0.1-1.0 and a weight average molecular weight of more than 300,000 and 1,000,000 or less, contains 50 parts by weight or more of 2-ethylhexyl acrylate and 5-40 parts by weight of the total of one or more monofunctional methacrylate monomers that forms a homopolymer having a Tg of 0℃ or higher.

Description

An adhesive composition, an adhesive film using the same, and a surface protection film TECHNICAL FIELD

The present invention relates to a pressure-sensitive adhesive composition that can be suitably used for surface protection films such as a surface protection film for polarizing plates, an adhesive film using the same, and a surface protection film. More specifically, it relates to a pressure-sensitive adhesive composition capable of achieving both antistatic performance and stain resistance performance while having a well-balanced adhesive force in a low-speed peeling rate and a high-speed peeling rate, an adhesive film using the same, and a surface protection film .

Conventionally, in the manufacturing process of optical members, such as a polarizing plate which is a member which comprises a liquid crystal display, a surface protection film is pasted for temporary protection of the optical member surface. Such a surface protection film is used only in the process of manufacturing an optical member, and peels and removes from an optical member at the time of incorporating an optical member into a liquid crystal display. Since the surface protection film for protecting the surface of such an optical member is used only in the manufacturing process of an optical member, it is also generally called a process film.

Thus, the surface protection film used in the process of manufacturing an optical member has the structure in which the adhesive layer was formed in the single side|surface of the polyethylene terephthalate (PET) resin film which has optical transparency. Moreover, in order to protect the adhesive layer, the release film by which the release process was carried out is pasted together by the surface of the adhesive layer of a surface protection film until it is bonded to an optical member.

And optical members, such as a polarizing plate, receive the product inspection accompanying optical evaluation, such as the display ability of a liquid crystal display board, hue, contrast, and foreign material mixing in the state to which the surface protection film was pasted up. For this reason, the required performance for the surface protection film is that no air bubbles or foreign substances are mixed in the pressure-sensitive adhesive layer, and it is possible to reduce the adhesion of low molecular weight components of the pressure-sensitive adhesive composition to the surface of the adherend, that is, stain resistance performance. It is required to have

In addition, when peeling the surface protection film from an optical member such as a polarizing plate, there is a concern that peeling electrification caused by static electricity generated when the pressure-sensitive adhesive layer is peeled off from an adherend causes a failure of the electric control circuit of the liquid crystal display. For this reason, it is calculated|required by the adhesive layer of a surface protection film to have the outstanding antistatic performance.

In addition, in recent years, as a polarizer protective layer (also called a protective film) of a polarizing plate, acrylic resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), When peeling off the surface protection film of a polarizing plate, such as a polyester resin, a cyclic olefin type polymer, and a polycarbonate, adoption of the material which tends to generate|occur|produce peeling electric charge is expanding. For this reason, the thing excellent in the antistatic performance calculated|required of the adhesive layer for surface protection films of a polarizing plate compared with the past is required.

Moreover, when finally peeling a surface protection film from optical members, such as a polarizing plate, what can peel quickly is required. It is calculated|required that there are few changes in adhesive force even if a peeling speed fluctuates so that what is called a high-speed peeling may also peel quickly.

As such, in recent years, with respect to the pressure-sensitive adhesive layer constituting the surface protection film, (1) having a balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate, (2) having a stain resistance performance, (3) excellent charging What has prevention performance, etc. are calculated|required from the point of the ease of use in using a surface protection film.

However, although each of these (1)-(3) can satisfy each individual requested|required performance with respect to the requested|required performance with respect to the adhesive layer which comprises a surface protection film, (1) calculated|required by the adhesive layer of a surface protection film It was a very difficult subject to simultaneously satisfy all the required performance of -(3).

In order to solve this problem, for example, (1) having a balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate, (2) having a stain resistance performance, and (3) having an excellent antistatic performance For each, the following proposals are known.

(1) With respect to those having a balance of adhesive strength in the low-speed peeling rate and the high-speed peeling rate, a copolymer of (meth)acrylic acid alkylester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound as a main component, and this as a crosslinking agent It is known to apply the acrylic adhesive layer formed by crosslinking process. However, in such a pressure-sensitive adhesive layer, when adhered for a long period of time, there is a problem that the pressure-sensitive adhesive adheres to the adherend side, and the synergism of the adhesive force to the adherend is large over time. In order to avoid this, a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms and a copolymerizable compound having an alcoholic hydroxyl group is used, and the gel fraction obtained by crosslinking it with a crosslinking agent is 60% or more, and a pressure-sensitive adhesive layer and the same A surface protection member provided with an adhesive layer is known (Patent Document 1).

However, in the adhesive layer of patent document 1, there existed a problem that the adhesive force with respect to a to-be-adhered body rose with time-dependent change, and there existed a problem that it could not completely solve.

Moreover, it is known that a small amount of a copolymer of a (meth)acrylic acid alkylester and a carboxyl group-containing copolymerizable compound is blended in the same copolymer as above, and an adhesive layer obtained by crosslinking this with a crosslinking agent is formed. However, since these pressure-sensitive adhesive layers have low surface tension, when used to protect the surface of a plastic plate with a smooth surface, there is a problem in that peeling phenomena such as lifting occurs due to heating during processing or storage, and high-speed peeling speed in the manual operation area. There was also a problem that the re-peelability was poor due to the high adhesion.

In order to solve these problems, a) 100 parts by weight of (meth)acrylic acid alkyl ester mainly containing (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms, b) 1 to 15 weight part of carboxyl group-containing copolymerizable compound and c) a copolymer of a monomer mixture obtained by adding 3 to 100 parts by weight of a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms, and a crosslinking agent equivalent to or more equivalent to the carboxyl group of the component b). It has been proposed (Patent Document 2).

In the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition described in Patent Document 2, peeling phenomena such as lifting does not occur at the time of processing or storage, and the synergism with time of adhesive strength is small, so that the re-peelability is excellent, and long-term storage, especially at high temperature It is said that even if it is stored for a long time in an atmosphere, it can be peeled again with a small force, and a residue does not generate|occur|produce on the to-be-adhered body at that time, and also when high-speed peeling is performed, it is said that re-peelability is possible with a small force.

However, in the adhesive layer which crosslinked the adhesive composition of patent document 2, all the gel fractions of the adhesive layers in Examples 1-3 are 90 %, the adhesive force in a low-speed peeling rate tends to become excessive, and it is small from an adhesive layer. Polymerized monomers or oligomers are easily eluted. In addition, there is no description regarding antistatic performance and stain resistance performance in Patent Document 2, and when a material that is prone to peeling and charging is used as an adherend, it is difficult to improve the pressure-sensitive adhesive layer having excellent antistatic performance and stain resistance performance. There was a problem.

Further, (2) for those having stain resistance performance, 0 parts by mass or more and less than 0.5 parts by mass of a carboxyl group-containing monomer, 0.6 to 9 parts by mass of a hydroxyl group-containing (meth)acrylic monomer, and 99.4 to 90.5 parts by mass of a (meth)acrylic acid ester monomer. 100 parts by mass of a (meth)acrylic copolymer having a weight average molecular weight of 100,000 or more and less than 1,000,000; And a pressure-sensitive adhesive composition containing 0.1 to 5 parts by mass of a carbodiimide-based crosslinking agent is disclosed (Patent Document 3).

The pressure-sensitive adhesive composition described in Patent Document 3 is characterized in that a carbodiimide-based crosslinking agent is used as a crosslinking agent for a (meth)acrylic copolymer having a specific composition. Thereby, the adhesive layer which has a crosslinked structure which can follow the shrinkage|contraction by the pressure and temperature at the time of an autoclave process can be provided. For this reason, the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition described in Patent Document 3 can suppress and prevent foaming even under high-temperature and high-pressure conditions (at the time of autoclave treatment), and has excellent stain-resistance performance and is also excellent in transparency. .

However, in the pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition described in Patent Document 3 is crosslinked, the stain resistance performance is improved, but by having a balance of adhesive strength in the low-speed peeling rate and the high-speed peeling rate, the excellent adhesive performance and the antistatic performance are compatible. This cannot be realized and remains as a further challenge.

Moreover, (3) About what has the outstanding antistatic performance, the method of kneading antistatic agent with a base film as a method for providing antistatic property to a surface protection film, etc. are known. Examples of the antistatic agent include (a) quaternary ammonium salts, pyridinium salts, and various cationic antistatic agents having a cationic group such as a primary to tertiary amino group, (b) a sulfonate group, a sulfate group, a phosphate ester. Anionic antistatic agents having an anionic group such as a base or a phosphonate group, (c) amphoteric antistatic agents such as amino acids and aminosulfate esters, (d) nonionic antistatic agents such as aminoalcohols, glycerols, and polyethylene glycols Antistatic agent, (e) High molecular weight antistatic agent, etc. which made the above antistatic agent high are disclosed (patent document 4).

However, in the surface protection film described in Patent Document 4, although there is a description regarding the provision of antistatic performance related to dust adhesion to an adherend, there is no description of a solution for achieving both excellent adhesion performance and stain resistance performance. However, it remains as a further problem to be solved.

Moreover, in recent years, making a base film contain an antistatic agent, or making it contain in an adhesive layer directly, without apply|coating to the surface of a base film is proposed. For example, an antistatic pressure-sensitive adhesive composition is disclosed in which a salt having an anion having a fluoro group and a sulfonyl group is dispersed in a dissolved state in a polyether ester plasticizer containing a polyether group in the main chain. (Patent Document 5).

In the pressure-sensitive adhesive composition described in Patent Document 5, as a plasticizer, an ester formed of a mono or dicarboxylic acid having a saturated or unsaturated acyclic hydrocarbon group and an alcohol having an acyclic hydrocarbon group having 1 to 20 carbon atoms, or the unsaturated acyclic hydrocarbon It is disclosed to use a plasticizer consisting of an ester in which the unsaturated groups in the group have been epoxidized. The mono- or dicarboxylic acid having such a saturated or unsaturated acyclic hydrocarbon group has a carbon number close to the carbon number of the acrylic monomer constituting the acrylic copolymer used in the pressure-sensitive adhesive layer, thereby improving compatibility with the antistatic pressure-sensitive adhesive composition, Bleed-out is suppressed because it is preferably retained in the plasticizer acrylic antistatic pressure-sensitive adhesive composition.

However, in the pressure-sensitive adhesive layer in which the antistatic pressure-sensitive adhesive composition described in Patent Document 5 is crosslinked, there is a disclosure of an improved technology for antistatic performance and bleed-out, but excellent adhesion performance by having a balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate There is no description of what is obtained, and the subject of obtaining the adhesive layer which has the outstanding adhesive performance remains.

Japanese Laid-Open Patent Publication No. 63-225677 Japanese Laid-Open Patent Publication No. 11-256111 Japanese Patent Laid-Open No. 2011-122054 Japanese Patent Laid-Open No. 11-070629 Japanese Laid-Open Patent Publication No. 2014-118469

As described above, as the required performance for the pressure-sensitive adhesive layer constituting the surface protection film, (1) having a balance of adhesive strength in low-speed peeling rate and high-speed peeling rate, (2) having stain resistance performance, (3) A prior art for solving the problem of simultaneously achieving excellent antistatic performance has not been identified.

In addition, the relationship between the antistatic performance of the pressure-sensitive adhesive layer formed using the conventional pressure-sensitive adhesive composition having antistatic performance and the surface protection film using the same and the stain resistance performance on the adherend is a trade-off relationship, maintaining the antistatic performance It was difficult to improve the contamination-resistance performance with the same.

In addition, in recent years, the type of adherend material to which the surface protection film is bonded increases, and the surface-treated state of the adherend is also varied. (1) It is becoming increasingly difficult to have a balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate, and (2) to have stain-resistance performance.

The present invention has been made in view of the above circumstances, has a balanced adhesive force in a low-speed peeling rate and a high-speed peeling rate, and is capable of achieving both antistatic performance and stain resistance performance, and an adhesive film using the same , to provide a surface protection film.

The inventors of the present invention review the type of compound copolymerized with the acrylic polymer of the pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a crosslinking agent as a pressure-sensitive adhesive composition for use in a surface protection film for a polarizing plate, and in particular, (1) low-speed In a peeling rate and a high-speed peeling rate, it worked hard about the subject which aims at coexistence of having balance of adhesive force, and having (2) stain-resistant performance earnestly worked on improvement.

As a result, (A) of the C1-C10 alkyl (meth)acrylates in the alkyl group, the glass transition temperature (Tg) of 2-ethylhexyl acrylate and the homopolymer is 0 ° C. or higher monofunctional methacrylate monomer It discovered that the subject of said (1) and (2) could be solved simultaneously by prescribing|regulating the content rate of in a specific range, and also completed this invention by setting it as the adhesive composition containing an antistatic agent.

In order to solve the above problems, the present invention is a pressure-sensitive adhesive composition comprising a first acrylic polymer, a crosslinking agent, and an ionic compound, wherein the first acrylic polymer is (A) an alkyl group having C1-C10 carbon atoms (meth ) 100 parts by weight of the total of at least two or more acrylates, (B) 1.0 to 6.0 parts by weight of the total of at least one copolymerizable monomer containing a hydroxyl group, and (C) a copolymerizable monomer containing a carboxyl group. It is an acrylic polymer consisting of a copolymer having an acid value of 0.1 to 1.0 and a weight average molecular weight of more than 300,000 and not more than 1 million by copolymerizing 0.01 to 0.6 parts by weight of at least one or more in total, wherein (A) the alkyl group has C1 to C10 carbon atoms. Among the total of 100 parts by weight of at least two or more of the alkyl (meth) acrylate, 50 parts by weight or more of 2-ethylhexyl acrylate and the sum of one or more monofunctional methacrylate monomers having a Tg of 0° C. or more of the homopolymer The pressure-sensitive adhesive composition, which is contained in a proportion of 5 to 40 parts by weight, comprises a trifunctional or higher isocyanate compound as the crosslinking agent, a crosslinking retarder, and a crosslinking catalyst other than a tin compound as a crosslinking catalyst. do.

After the surface protection film obtained by laminating the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition to a thickness of 15 µm on one side of a polyester film having a thickness of 38 µm is pasted on the polarizing plate surface, when peeling the surface protection film from the polarizing plate, It is preferable that the adhesive force in a low-speed peeling rate of 0.3 m/min is 0.01-0.1 N/25 mm, and the adhesive force in a high-speed peeling rate of 30 m/min is 1.0 N/25 mm or less.

The monofunctional methacrylate monomer having a Tg of 0° C. or higher of the homopolymer is n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, n-propyl methacrylate, It is preferable that it is 1 or more types selected from the compound group which consists of isopropyl methacrylate, ethyl methacrylate, and methyl methacrylate.

The pressure-sensitive adhesive composition further comprises a second acrylic polymer, wherein the second acrylic polymer is (a) at least one of (meth)acrylic acid ester monomers having C1-C18 carbon atoms in the alkyl group, and (b) It is a copolymer obtained by copolymerizing at least one type of copolymerizable monomer containing a hydroxyl group and at least one type of (c) polyalkylene glycol chain containing mono(meth)acrylic acid ester monomer, wherein the pressure-sensitive adhesive composition is (A) It is preferable to contain the said 2nd acrylic polymer in the ratio of 0.1-5.0 weight part with respect to a total of 100 weight part of at least 2 or more types of C1-C10 alkyl (meth)acrylate of an alkyl group.

The pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer used in a surface protection film for a polarizing plate, and the polarizer protection layer of the polarizing plate is one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film, and , It is preferable that the surface treatment applied to the surface of the polarizer protective layer of the polarizing plate is one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment.

The ionic compound is an ionic compound having a melting point of 25 to 80° C., the cation of the ionic compound is pyridinium, and the pressure-sensitive adhesive composition contains 0.01 to 0.01 to the ionic compound with respect to 100 parts by weight of the first acrylic polymer. It is preferable to contain it as an essential component in the ratio of 10 weight part.

The surface resistivity of the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition is 1.0 × 10 ⁺¹² Ω/□ or less,

The peeling electrification voltage of the pressure-sensitive adhesive layer with respect to the low-refractive-index layer formed using the composition for forming a low-refractive-index layer containing a fluorine compound is in the range of +0.3 to -0.3 kV,

The surface substrate is one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film, and the surface treatment applied to the surface of the surface substrate is untreated, AG treatment, LR treatment, AR treatment, AG- After bonding to a polarizing plate which is one type selected from the group consisting of LR treatment and AG-AR treatment, leaving it to stand for 2 days under an atmosphere of temperature 60°C and humidity 90%RH, taking it out, and peeling off after 1 day has passed. desirable.

(B) the hydroxyl group-containing copolymerizable monomer is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) at least one selected from the group consisting of acrylamide,

(C) the copolymerizable monomer containing a carboxyl group is (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- ( Meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxypoly It is preferable that it is at least 1 sort(s) or more selected from the compound group which consists of caprolactone mono(meth)acrylate and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid.

The crosslinking retardant is a ketoenol tautomer compound, and the crosslinking retardant is contained in a ratio of 0.1 to 300 parts by weight based on 100 parts by weight of the first acrylic polymer, wherein the crosslinking catalyst is an aluminum chelate compound, titanium It is at least one metal chelate compound selected from the group consisting of a chelate compound and an iron chelate compound, and the crosslinking catalyst is contained in a ratio of 0.001 to 0.5 parts by weight based on 100 parts by weight of the first acrylic polymer, and the crosslinking delay It is preferable that the ratio by weight of the first/above crosslinking catalyst is 80 to 1000.

It is preferable that the said adhesive composition contains the polyether-modified siloxane compound whose HLB value is 6-12 and the weight average molecular weight 10000 or less with respect to 100 weight part of said 1st acrylic polymer in the ratio of 0.01-0.5 weight part.

The second acrylic polymer is (a) with respect to a total of 100 parts by weight of at least one or more of the (meth)acrylic acid ester monomer having a C1-C18 alkyl group, (b) at least one or more copolymerizable monomers containing a hydroxyl group. A public having a weight average molecular weight of more than 300,000 and not more than 800,000 by copolymerizing 1 to 30 parts by weight of the total of 2.0 to 12.0 parts by weight and (c) at least one type of polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer A value of at least one or more total parts by weight of the copolymerizable monomer containing the hydroxyl group (B) contained in the first acrylic polymer relative to 100 parts by weight of the total of the first acrylic polymer (B-1); The ratio of the value (b-1) of at least one total weight part of the copolymerizable monomer containing a hydroxyl group (b) contained in the second acrylic polymer to a total of 100 parts by weight of the second acrylic polymer (b-1) It is preferable that 1)/(B-1) exists in the range of 1.0-2.0.

The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer has an average repeating number of alkylene oxide constituting the polyalkylene glycol chain from 3 to 14, and in the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer The diester content is 0.2% or less, and the polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer is polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (meth) acrylate, and ethoxy polyalkyl. It is preferable to contain at least one selected from the group consisting of renglycol (meth)acrylate in an amount of 1 to 50 parts by weight based on 100 parts by weight of the second acrylic polymer.

In addition, the present invention provides a pressure-sensitive adhesive film, characterized in that the pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is crosslinked is laminated on one side of the resin film.

In addition, the present invention provides a surface protection film using the adhesive film.

In addition, the present invention provides a surface protection film for a polarizing plate using the adhesive film.

In addition, the present invention provides an optical film having a pressure-sensitive adhesive layer formed on at least one side of the optical film, in which the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition is laminated.

In addition, the present invention provides an adhesive film having an antistatic treatment and an antifouling treatment on the opposite side to the side on which the pressure-sensitive adhesive layer is formed on one side of the resin film.

In the pressure-sensitive adhesive composition according to the present invention, the first acrylic polymer contains (A) 50 parts by weight of 2-ethylhexyl acrylate in a total of 100 parts by weight of at least two or more kinds of alkyl (meth)acrylates having C1-C10 alkyl groups. The total of 1 or more parts and the monofunctional methacrylate monomer whose Tg of a homopolymer is 0 degreeC or more is contained in the ratio of 5-40 weight part. Thereby, also in the surface protection film for polarizing plate which uses PMMA as a base material especially, (1) having a balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate, and (2) having a stain resistance performance can be compatible. .

On the other hand, in the pressure-sensitive adhesive composition according to the present invention, the incorporation of at least one monofunctional methacrylate monomer having a Tg of the homopolymer of 0 ° C. or higher is (1) the balance of the adhesive force in the low-speed peeling rate and the high-speed peeling rate. It is not clear why it contributes to making it compatible with what has and has (2) contamination-resistance performance. A possible reason is that, despite not having a polar functional group such as a carboxyl group or an amide group, or a long-chain alkyl group exceeding C10, a polymer having a high Tg is obtained, so that the adhesion performance in the crosslinked state is greatly improved. What can be improved, and the affinity of methyl methacrylate which is a main component of a PMMA type film improves, etc. are estimated as the reason.

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

The pressure-sensitive adhesive composition of the present embodiment is a pressure-sensitive adhesive composition comprising an acrylic polymer, a crosslinking agent, and an ionic compound, wherein the acrylic polymer is

(A) 100 parts by weight of the total of at least two kinds of alkyl (meth)acrylates having C1-C10 carbon atoms in the alkyl group;

(B) 1.0 to 6.0 parts by weight of the total of at least one copolymerizable monomer containing a hydroxyl group;

(C) 0.01 to 0.6 parts by weight of at least one total of at least one copolymerizable monomer containing a carboxyl group

It is an acrylic polymer composed of a copolymer having an acid value of 0.1 to 1.0 and a weight average molecular weight of more than 300,000 and not more than 1 million,

(A) In a total of 100 parts by weight of at least two or more kinds of alkyl (meth)acrylates having C1-C10 carbon atoms in the alkyl group, 50 parts by weight or more of 2-ethylhexyl acrylate and Tg of the homopolymer is 0°C or more It is made by containing the sum of one or more types of monofunctional methacrylate monomers in a ratio of 5 to 40 parts by weight,

It is characterized in that the pressure-sensitive adhesive composition contains a trifunctional or higher isocyanate compound as the crosslinking agent, a crosslinking retarder, and a crosslinking catalyst other than a tin compound as a crosslinking catalyst.

The acrylic polymer used for the adhesive composition of this embodiment is a main polymer of an adhesive composition, and when distinguishing from the 2nd acrylic polymer mentioned later, it may be called a 1st acrylic polymer. The first acrylic polymer is an acrylic polymer having a glass transition temperature (Tg) of 0° C. or less. The first acrylic polymer is preferably (A) a copolymer containing, as a main component, an alkyl (meth)acrylate having C1-C10 alkyl groups.

(A) C1-C10 alkyl (meth) acrylate in the alkyl group includes methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (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 Acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. are mentioned. The alkyl group of these alkyl (meth)acrylates may be either acyclic (linear, branched) or cyclic (monocyclic, polycyclic).

The first acrylic polymer contains 50 parts by weight or more of 2-ethylhexyl acrylate among 100 parts by weight of (A) and at least one monofunctional methacrylate monomer having a Tg of the homopolymer of 0° C. or more. It is preferable to contain it in the ratio of 5-40 weight part.

In addition, 2-ethylhexyl acrylate is preferably contained in a proportion of 50 parts by weight or more, more preferably in a proportion of 60 parts by weight or more, in a proportion of 70 parts by weight or more in a total of 100 parts by weight of the above (A). It is particularly preferable to contain

In addition, (A) among alkyl (meth)acrylates having C1-C10 alkyl groups, the monofunctional methacrylate monomers having a Tg of 0°C or higher include n-butyl methacrylate, isobutyl methacrylate, and s-butyl Methacrylate, t-butyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, ethyl methacrylate, methyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl and at least one selected from the group consisting of methacrylate, isohexyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate and dicyclopentamethacrylate. Among monofunctional methacrylate monomers having a Tg of 0° C. or higher, a methacrylate monomer having an alkyl group having C1-C6 carbon atoms is preferable, a methacrylate monomer having an alkyl group having C1-C4 carbon atoms is more preferable, and n-butyl From the group consisting of methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, ethyl methacrylate, methyl methacrylate It is especially preferable that it is 1 or more types selected.

In addition, it is preferable to contain the total of one or more types of monofunctional methacrylate monomers whose Tg is 0 degreeC or more in the ratio of 5-40 weight part among 100 weight part of total of said (A), 8-40 weight part It is more preferable to contain, and it is especially preferable to contain in the ratio of 10-35 weight part. On the other hand, in the following description, when Tg is simply referred to as a monomer, it may refer to Tg of a homopolymer.

Examples of the copolymerizable monomer containing (B) a hydroxyl group used in the first acrylic polymer include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 4-hydroxybutyl (meth) Compound group consisting of acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. It is preferable that at least one selected from among.

It is preferable that the first acrylic polymer contains a total of at least one type of copolymerizable monomer containing a hydroxyl group (B) in a ratio of 1.0 to 6.0 parts by weight with respect to 100 parts by weight of the total of (A), 2.0 It is more preferable to contain it in the ratio of -6.0 weight part, and it is especially preferable to contain it in the ratio of 2.5 to 5.5 weight part.

As a copolymerizable monomer containing (C) a carboxyl group used in the first acrylic polymer, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2- (meth)acryloyloxy Ethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acrylo It is preferable that it is at least 1 sort(s) selected from the compound group which consists of yloxyethyl maleic acid, carboxy polycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, etc.

It is preferable that the first acrylic polymer contains 0.01 to 0.6 parts by weight of the total of (C) at least one type of copolymerizable monomer containing a carboxyl group with respect to 100 parts by weight of the total of (A), 0.01 to 0.6 parts by weight, 0.01 It is more preferable to contain it in the ratio of -0.5 weight part, and it is especially preferable to contain it in the ratio of 0.01-0.4 weight part.

The manufacturing method of the said 1st acrylic polymer is not specifically limited, A well-known polymerization method can be used suitably, such as a solution polymerization method and an emulsion polymerization method. The first acrylic polymer preferably has a weight average molecular weight of greater than 300,000 and less than or equal to 1,000,000. In addition, it is preferable that the acid value of the first acrylic polymer is 0.1 to 1.0. Thereby, stain resistance performance can be improved. Here, "acid value" is one of the index|index showing content of an acid, and it represents with mg number of potassium hydroxide required in order to neutralize 1 g of polymers containing a carboxyl group.

The pressure-sensitive adhesive composition according to the present embodiment contains (G) an antistatic agent. It is preferable that the (G) antistatic agent of this embodiment is an ionic compound with a melting|fusing point of 25-80 degreeC. The ionic compound is preferably a solid at room temperature. The normal temperature is, for example, a temperature of less than 25°C, and specifically, it is preferable that the ionic compound is a solid at 23°C. It is preferable that the pressure-sensitive adhesive composition according to the present embodiment contains the ionic compound as an essential component in a ratio of 0.01 to 10 parts by weight with respect to 100 parts by weight of the first acrylic polymer.

Examples of the anion of the ionic compound include inorganic anions such as hexafluorophosphate (PF ₆ ^- ), thiocyanate (SCN ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ), carboxylate ( RCOO ^- ), sulfonate (RSO ₃ ^- ), alkoxide or phenoxide salt (RO ^- ), organic imide salt (R ₂ N ^- ), methide salt (R ₃ C ^- ), organic borate salt (R ₄ B) ^- ), such as organic anions, etc. are mentioned. R contained in each chemical formula of an organic anion is an organic group which may have fluorine substitution. Examples of the organic group include at least one or more of an alkyl group, an alkoxy group, an aromatic group (aryl group, aralkyl group, etc.), an aliphatic or aromatic carbonyl group, and an aliphatic or aromatic sulfonyl group. In the organic group contained in the anion, part or all of hydrogen atoms may be substituted with one or more halogen atoms such as fluorine atoms.

The cations of the ionic compound include pyridinium, imidazolium, phosphonium, sulfonium, pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, piperidinium, pyrazolium, methylium, mor 1 type selected from the group which consists of polynium is mentioned. It is preferable that the cation of the said ionic compound is pyridinium. In the organic group contained in the cation, part or all of hydrogen atoms may be substituted with one or more halogen atoms such as fluorine atoms.

When the anion and/or cation of the ionic compound contains an organic group such as an alkyl group, an ionic compound having a melting point of 25 to 80°C can be obtained by selecting the chain length of the alkyl group, the position and number of substituents, and the like.

Specific examples of the ionic compound include, for example, 1-octylpyridinium hexafluorophosphate, 1-nonylpyridinium hexafluorophosphate, 2-methyl-1-dodecylpyridinium hexafluorophosphate, and 3-methyl-1 -Dodecylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1-octylpyri Dinium hexafluorophosphate, 1-nonylpyridinium 2-iodobenzenesulfonate, 4,5-diiodo-1-butyl-3-methylimidazolium hexafluorophosphate, 2-methyl-1-dodecylpyridinium 2- Iodinebenzenesulfonate, 4,5-diiodo-1-butyl-3-methylimidazolium 3-iodobenzenesulfonate, 1-octyl-2-methylpyridinium trifluoromethanesulfonate salt, 1,2, 3-trimethylimidazolium pentafluoroethanesulfonate salt, 1-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate salt, 1-hexyl-4-methylpyridinium pentafluoroethanesulfonate salt , 1-octyl-3-methylpyridinium trifluoromethanesulfonate salt, n-octylpyridinium trifluoromethanesulfonate salt, 1-propyl-3-methylpyridinium nonafluorobutanesulfonate salt, 3- Methyl-1-octylpyridinium nonafluorobutanesulfonate salt, methyltrioctylammonium tris(pentafluorobenzenesulfonyl)methide salt, 1-ethyl-3-methylimidazolium tetrakispentafluorophenylborate salt , 1-butyl-1-methylpiperidinium bis(pentafluorobenzenesulfonyl)imide salt and the like.

The pressure-sensitive adhesive composition according to the present embodiment further contains (D) a trifunctional or more than trifunctional isocyanate compound as a crosslinking agent. The trifunctional or more functional isocyanate compound includes, for example, a buret-modified product or isocyanurate-modified product of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate. , an adduct body with polyols having trivalence or higher, such as trimethylolpropane and glycerin, etc. are mentioned. (D) As the ratio of the trifunctional or higher isocyanate compound as the crosslinking agent, for example, it is preferably contained in a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the first acrylic polymer, and is contained in a ratio of 0.1 to 6 parts by weight. It is more preferable to

The pressure-sensitive adhesive composition according to the present embodiment may contain (E) a crosslinking retarder. (E) Crosslinking retarders include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, acetylacetone, and 2,4-hexanedione and β-diketones such as benzoylacetone. These are ketoenol tautomer compounds, and in the pressure-sensitive adhesive composition using a polyisocyanate compound as a crosslinking agent, (D) blocks the isocyanate group which the crosslinking agent has, thereby suppressing excessive viscosity increase or gelation of the pressure-sensitive adhesive composition after mixing of the crosslinking agent, and the pressure-sensitive adhesive It can prolong the pot life of the composition. (E) The crosslinking retardant is particularly preferably at least one selected from the group consisting of acetylacetone and ethyl acetoacetate. It is preferable to contain the (E) crosslinking retarder in the ratio of 0.1-300 weight part with respect to 100 weight part of said 1st acrylic polymers.

The adhesive composition which concerns on this embodiment may contain crosslinking catalysts other than a tin compound as a (F) crosslinking catalyst. (F) The crosslinking catalyst should just be a substance which functions as a catalyst with respect to reaction (crosslinking reaction) of an acrylic polymer and a crosslinking agent, when making a polyisocyanate compound into a crosslinking agent. (F) As a crosslinking catalyst, a metal chelate compound is preferable. A metal chelate compound is a compound in which one or more polydentate ligands L are bonded to a central metal atom M. The metal chelate compound may or may not have one or more monodentate ligands X bonding to the metal atom M. Specific examples of the metal chelate compound include tris(2,4-pentanedionate)iron(III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum tris Acetylacetonate, zirconium tetrakisacetylacetonate, tris(2,4-hexanedionate)iron(III), bis(2,4-hexanedionate)zinc, tris(2,4-hexanedionate)titanium, Tris(2,4-hexanedionate)aluminum, tetrakis(2,4-hexanedionate)zirconium, etc. are mentioned.

(F) The crosslinking catalyst is preferably at least one metal chelate compound selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound. It is preferable to contain the (F) crosslinking catalyst in the ratio of 0.001-0.5 weight part with respect to 100 weight part of said 1st acrylic polymers.

Since the (E) crosslinking retarder has the effect of suppressing crosslinking as opposed to the (F) crosslinking catalyst, it is preferable to appropriately set the ratio of the (E) crosslinking retarder to the (F) crosslinking catalyst. In order to lengthen the pot life of an adhesive composition and to improve storage stability, it is preferable that the weight part ratio of (E)/(F) is 80-1000, It is more preferable that it is 80-700, It is 80-300 Especially preferred. Here, the weight part ratio of (E)/(F) is the value of the quotient obtained by dividing the weight part of (E) by the weight part of (F).

The pressure-sensitive adhesive composition according to the present embodiment may contain (H) a polyether-modified siloxane compound as an optional component. (H) The polyether-modified siloxane compound is a siloxane compound having a polyether group, and in addition to the usual siloxane unit [-SiR ¹ ₂ -O-], a siloxane unit having a polyether group [-SiR ¹ (R ² O(R ³ O)) ) _n R ⁴ )-O-]. Here, R ¹ is one or more alkyl or aryl groups, R ² and R ³ are one or two or more alkylene groups, R ⁴ is one or more alkyl or acyl groups (terminal groups) indicates. Examples of the polyether group include polyoxyalkylene groups such as polyoxyethylene group [(C ₂ H ₄ O) _n ] and polyoxypropylene group [(C ₃ H ₆ O) _n ]. In the siloxane unit having a polyether group, the terminal of the polyether group may be an OH group (R ⁴ =H in the above formula).

(H) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 6 to 12. In addition, with respect to 100 parts by weight of the first acrylic polymer, (H) polyether-modified siloxane compound is preferably contained in a ratio of 0.01 to 0.5 parts by weight, more preferably 0.02 to 0.35 parts by weight, It is especially preferable to contain in the ratio of 0.02-0.25 weight part. The HLB value is, for example, a hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) prescribed in JIS K3211 (Terminology of Surfactant) or the like.

The polyether-modified siloxane compound can be obtained by, for example, grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a silicon hydride group by hydrosilylation reaction. Specifically, dimethylsiloxane/methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxyethylene) siloxane/methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxypropylene) siloxane polymer, etc. can be heard

(H) By mix|blending a polyether modified siloxane compound with an adhesive composition, the adhesive force of an adhesive layer and rework performance can be improved. (H) It is preferable that the weight average molecular weight of a polyether modified siloxane compound is 10000 or less. From the viewpoint of compatibility with the acrylic polymer, the lower the HLB value and the lower the molecular weight, the better the compatibility. However, in the case of a polyether-modified siloxane compound having a low molecular weight, the HLB value is relatively high and the compatibility with the polymer is slightly low, but excellent antistatic properties this is obtained

The pressure-sensitive adhesive composition according to the present embodiment may contain the second acrylic polymer as an optional component. Since the pressure-sensitive adhesive composition further contains a second acrylic polymer obtained by copolymerizing a polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer, compatibility between the ionic compound and the acrylic polymer is improved, antistatic performance and stain resistance performance can be further improved. As the second acrylic polymer, (a) at least one type of (meth)acrylic acid ester monomer having an alkyl group having C1-C18 carbon atoms, (b) at least one type of copolymerizable monomer containing a hydroxyl group, and (c) and a copolymer obtained by copolymerizing at least one type of polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer.

(a) C1-C18 (meth)acrylic acid ester monomers used in the second acrylic polymer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (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, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate , hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. The alkyl group of (a) may be either acyclic (linear, branched) or cyclic (monocyclic, polycyclic).

The (a) C1-C18 (meth)acrylic acid ester monomer of the alkyl group used in the second acrylic polymer is used in the first acrylic polymer (A) The alkyl group has C1-C10 alkyl (meth)acryl It is also possible to select the same compound or ratio as the rate.

Or (a) may contain the compound different from (A). Moreover, even as a compound with the same monomer, the ratio in (a) may differ from the ratio in (A). For example, the copolymer in which the alkyl methacrylate is not copolymerized may be sufficient as the said 2nd acrylic polymer. Further, the second acrylic polymer may be a copolymer in which a (meth)acrylic acid ester monomer having an alkyl group having C11 to C18 carbon atoms is not copolymerized, or the second acrylic polymer may be a (meth)acrylic acid having an alkyl group having C11 to C18 carbon atoms. You may contain an ester monomer.

Examples of the copolymerizable monomer containing (b) a hydroxyl group used in the second acrylic polymer include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 4-hydroxybutyl (meth). Compound group consisting of acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. It is preferable that at least one selected from among.

The second acrylic polymer is (a) with respect to a total of 100 parts by weight of at least one or more of the (meth)acrylic acid ester monomer having a C1-C18 alkyl group, (b) at least one copolymerizable monomer containing a hydroxyl group. It is preferable to contain the above sum in the ratio of 2.0-12.0 weight part, It is more preferable to contain in the ratio of 3.0-12.0 weight part, It is especially preferable to contain in the ratio of 4.0-12.0 weight part.

It is also possible to select the same compound or ratio that the copolymerizable monomer containing a hydroxyl group (b) used in the second acrylic polymer is the same as the copolymerizable monomer containing a hydroxyl group (B) used in the first acrylic polymer. Or (b) may also contain the compound different from (B). Moreover, even if a monomer is the same compound, the ratio in (b) may differ from the ratio in (B).

The second acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment contains (c) a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer. In the adhesive composition of this embodiment, the 2nd acrylic polymer containing this (c) polyalkylene glycol chain containing mono(meth)acrylic acid ester monomer is functioning as an antistatic adjuvant.

On the other hand, the first acrylic polymer may be a copolymer in which a polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer is not copolymerized, or the same polyalkylene glycol chain-containing mono (meth) acrylic acid ester as the second acrylic polymer. It is also possible to copolymerize the monomers.

The second acrylic polymer is contained in a ratio of 0.1 to 5.0 parts by weight with respect to 100 parts by weight in total of at least two or more kinds of alkyl (meth)acrylate having C1-C10 carbon atoms of the (A) alkyl group used in the first acrylic polymer. It is preferable to contain it in the ratio of 0.1-3.5 weight part, More preferably, it is especially preferable to contain it in the ratio of 0.1-2.5 weight part.

(c) The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer may be a compound in which one hydroxyl group among a plurality of hydroxyl groups of polyalkylene glycol is esterified as a (meth)acrylic acid ester. Since the (meth)acrylic acid ester group becomes a polymerizable group, it can copolymerize with a 2nd acrylic polymer. Polyalkylene glycol mono(meth)acrylate in which another hydroxyl group is OH as it is may be sufficient, and the alkoxy polyalkylene glycol mono(meth)acrylate etc. in which the other hydroxyl group was converted into alkyl ether may be sufficient. On the other hand, polyalkylene glycol mono(meth)acrylate is not classified as (B) or (b) even if it contains a hydroxyl group at the point corresponding to (c).

The polyalkylene glycol constituting the polyalkylene glycol chain may be a glycol compound having one or more alkylene groups, for example, polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-polypropylene. Glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol- polybutylene glycol, polyethylene glycol- polypropylene glycol- polybutylene glycol, etc. are mentioned.

(c) The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer preferably has an average repeating number of 3 to 14 alkylene oxides constituting the polyalkylene glycol chain. "Average number of repetitions of alkylene oxide" means (c) that the alkylene oxide unit repeats in the "polyalkylene glycol chain" part contained in the molecular structure of the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer. is the average number.

Moreover, it is preferable that the diester content in (c) polyalkylene glycol chain containing mono(meth)acrylic acid ester monomer is 0.2 % or less. The "diester fraction in the monomer" is the content (weight%) of the polyalkylene glycol di(meth)acrylic acid ester contained in the (c) polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer.

(c) polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomers include polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (meth) acrylate, ethoxy polyalkylene glycol (meth) At least one selected from the group consisting of acrylates is preferable.

The second acrylic polymer is (a) with respect to a total of 100 parts by weight of at least one or more of the (meth)acrylic acid ester monomer having a C1-C18 alkyl group, (c) polyalkylene glycol chain-containing mono (meth)acrylic acid It is preferable to contain the ester monomer in the ratio of 1-30 weight part, It is more preferable to contain it in the ratio of 2-30 weight part, It is especially preferable to contain it in the ratio of 5-25 weight part.

The manufacturing method of the said 2nd acrylic polymer is not specifically limited, Well-known polymerization methods, such as a solution polymerization method and an emulsion polymerization method, can be used suitably. The second acrylic polymer is preferably a copolymer having a weight average molecular weight of more than 300,000 and not more than 800,000. The weight average molecular weight of the second acrylic polymer may be about the same as the weight average molecular weight of the first acrylic polymer, or may be larger or smaller than the weight average molecular weight of the first acrylic polymer.

The second acrylic polymer may have a functional group capable of reacting with the (D) crosslinking agent. The second acrylic polymer may be a copolymer in which a copolymerizable monomer containing a carboxyl group is not copolymerized, or it is also possible to copolymerize a copolymerizable monomer containing the same carboxyl group as the first acrylic polymer. (D) The crosslinking agent may be involved in the crosslinking of the first acrylic polymer and the second acrylic polymer.

The value (B-1) of at least one total weight part of the copolymerizable monomer containing a hydroxyl group (B) contained in the first acrylic polymer with respect to a total of 100 parts by weight of the first acrylic polymer, and the second acrylic polymer Ratio (b-1)/(B-1) of the value (b-1) of at least one total weight part of at least one copolymerizable monomer containing a hydroxyl group (b) contained in the second acrylic polymer to a total of 100 parts by weight of ) is preferably in the range of 1.0 to 2.0.

The pressure-sensitive adhesive composition of the present embodiment is not limited to the above additives, and well-known additives such as surfactants, curing accelerators, plasticizers, fillers, curing retarders, processing aids, antioxidants and antioxidants may be appropriately blended. These can be used individually or in combination of 2 or more types.

The adhesive composition of this embodiment is preferable as an adhesive composition for forming the adhesive layer used for the surface protection film for polarizing plates. The pressure-sensitive adhesive layer of the surface protection film may be bonded to the polarizer protective layer of the polarizing plate. Here, the polarizer protective layer of the polarizing plate may be at least one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film. Here, TAC is an abbreviation of triacetyl cellulose, PMMA is polymethyl methacrylate, and PET is an abbreviation of polyethylene terephthalate.

Further, the surface treatment applied to the surface of the polarizer protective layer of the polarizing plate may be at least one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment. Here, AG is anti-glare, LR is low reflection, and AR is anti-reflection.

The pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of the present embodiment ^{preferably has a surface resistivity of 1.0 × 10 +12} Ω/□ or less, more preferably 5.0 × 10 ⁺¹¹ Ω/□ or less, and 1.0 × 10 ⁺¹¹ Ω/□ or less. It is especially preferable that it is the following. When the surface resistivity is large, the performance of dissipating static electricity generated when the pressure-sensitive adhesive layer is peeled from the adherend is poor. For this reason, by making the surface resistivity sufficiently small, the peeling electrification voltage generated accompanying static electricity generated when the pressure-sensitive adhesive layer is peeled from the adherend is reduced, and it is possible to suppress the influence on the adherend.

The pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of the present embodiment has a peeling electrification voltage of the pressure-sensitive adhesive layer with respect to the low-refractive-index layer formed using the composition for forming a low-refractive-index layer containing a fluorine compound is in the range of +0.3 to -0.3 kV. desirable. The fluorine compound used in the composition for forming a low refractive index layer includes a fluorine-containing copolymer that is one or two or more polymers such as fluorinated olefins, fluorinated vinyl ethers, and fluorinated alkyl (meth) acrylates, fluorinated alkyl group-containing silane compounds, etc. condensates of In addition to the fluorinated monomer, the fluorine-containing copolymer may be copolymerized with non-fluorinated monomers, such as olefins, vinyl ethers, and (meth)acrylate. The low-refractive-index layer may be combined with a high-refractive-index layer or the like to constitute an antireflection layer.

When measuring the peel electrification voltage with respect to the low-refractive-index layer, as a base material for forming a low-refractive-index layer on the surface, a PMMA base material and a TAC base material are mentioned. Moreover, it is preferable that the peeling electrification voltage with respect to the plane layer in which the surface of the PMMA base material and the TAC base material is not treated with the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of the present embodiment is in the range of +0.3 to -0.3 kV.

After the pressure-sensitive adhesive layer is bonded to an adherend such as a polarizing plate, it is left for 2 days (48 hr) in an atmosphere of a temperature of 60° C. and a humidity of 90% RH, taken out from the atmosphere, and peeled off after 1 day has passed. No contamination it is preferable Examples of the adherend include a polarizing plate in which a protective layer is laminated on a polarizer and the surface of the protective layer is treated with a composition containing a fluorine compound to have a low reflection surface. The composition containing the fluorine compound used for low-reflection surface treatment may be the same as the resin composition for low-refractive-index layer formation containing the above-mentioned fluorine compound, and may differ. As a protective layer and surface treatment, the surface treatment given to the above-mentioned polarizer protective layer and its surface is mentioned.

After a surface protection film formed by laminating a pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of the present embodiment to a thickness of 15 μm on one side of a polyester film having a thickness of 38 μm is pasted on the surface of a polarizing plate, the surface protection film is removed from the polarizing plate When peeling, it is preferable that the adhesive force at a low-speed peeling speed 0.3 m/min is 0.01-0.1 N/25 mm, and it is preferable that the adhesive force at a high-speed peeling speed 30 m/min is 1.0 N/25 mm or less, and a high-speed peeling speed 30 m/min. It is more preferable that the adhesive force in is 0.2-1.0N/25mm. Thereby, the performance with little change in adhesive force also with peeling speed is acquired, and it becomes possible to peel quickly also by high-speed peeling. Moreover, even when peeling a surface protection film once for re-attaching, it is easy to peel from a to-be-adhered body without requiring excessive force.

It is preferable that it is 95-100 %, and, as for the gel fraction of the adhesive layer formed by bridge|crosslinking the adhesive composition of this embodiment, it is more preferable that it is 97-100 %. As described above, when the gel fraction of the pressure-sensitive adhesive layer is high, the adhesive force at a low peeling rate is not excessive, and the elution of unpolymerized monomers or oligomers from the copolymer is reduced, and the reworkability and durability at high temperature and high humidity are improved. and contamination of the adherend can be suppressed.

The adhesive film of this embodiment forms the adhesive layer formed by bridge|crosslinking the adhesive composition of this embodiment on the single side|surface or both surfaces of a resin film. In addition, the surface protection film of this embodiment is a surface protection film formed by forming the adhesive layer formed by bridge|crosslinking the adhesive composition of this embodiment in single side|surface of a resin film. The adhesive composition of this embodiment is equipped with the outstanding antistatic performance, it is excellent in the balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate, and has stain-resistance performance. For this reason, it can use suitably as a use of the surface protection film of a polarizing plate.

A resin film, such as a polyester film, etc. can be used as a release film (separator) which protects the base film of an adhesive layer or an adhesive surface.

Antistatic treatment and antifouling treatment may be given to the surface opposite to the side in which the said adhesive layer of the resin film single side was formed. As antistatic treatment, application|coating, containing, etc. of an antistatic agent are mentioned. Examples of the antifouling treatment include treatment with silicone-based and fluorine-based mold release agents, coating agents, silica fine particles, and the like. The release film may be subjected to a release treatment with a silicone-based, fluorine-based, or long-chain alkyl-based mold release agent, etc.

Moreover, the optical film with an adhesive layer can be obtained by laminating|stacking the adhesive layer which bridge|crosslinked the adhesive composition of this embodiment on at least one surface of an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an anti-glare (anti-glare) film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness improving film. As an apparatus to which an optical member is applied, a liquid crystal panel, an organic electroluminescent panel, a touch panel, etc. are mentioned.

In the case of a surface protection film for optics, such as a surface protection film for polarizing plates, and an adhesive film, it is preferable that a base film and an adhesive layer have sufficient transparency.

Example

Hereinafter, the present invention will be specifically described with reference to Examples.

<Production of the first acrylic polymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen gas. Then, 70 parts by weight of 2-ethylhexyl acrylate, 30 parts by weight of n-butyl methacrylate, 5.5 parts by weight of 8-hydroxyoctyl acrylate, and 0.2 parts by weight of acrylic acid and a solvent (ethyl acetate) were added to the reactor. did. Then, 0.1 weight part of azobisisobutyronitrile as a polymerization initiator was dripped over 2 hours, it was made to react at 65 degreeC for 6 hours, and the 1st acrylic polymer used in Example 1 was obtained.

[Examples 2 to 6 and Comparative Examples 1 to 4]

Examples 2 to 6 and comparison were performed in the same manner as in the first acrylic polymer solution used in Example 1, except that the monomer composition was as described in Table 1 (A), (B) and (C), respectively. The 1st acrylic polymer solution used in Examples 1-4 was obtained.

On the other hand, the first acrylic polymer used in Examples 1 to 6 and Comparative Examples 1 to 4 was a copolymer having a weight average molecular weight of more than 300,000 and not more than 1 million.

<Preparation of adhesive composition and surface protection film>

[Example 1]

With respect to the first acrylic polymer solution of Example 1 prepared as described above, 2.0 parts by weight of a crosslinking agent (Coronate HX), 9 parts by weight of acetylacetone, 0.1 parts by weight of a crosslinking catalyst (Titanium trisacetylacetonate), an antistatic agent (3 -Methyl-1-octylpyridinium nonafluorobutanesulfonate salt) 0.9 parts by weight, polyether-modified siloxane compound (HLB=7) 0.05 parts by weight, 2-ethylhexyl acrylate, 8-hydroxyoctyl acrylate and methyl A weight average molecular weight (Mw) of oxypolyethylene glycol acrylate (n=8) copolymerized in a weight ratio of 100:8:15 was added and stirred and mixed with 0.2 parts by weight of a copolymer having a weight average molecular weight (Mw) of 600,000 to obtain the pressure-sensitive adhesive composition of Example 1. After apply|coating this adhesive composition on the mold release film (silicone resin-coated PET film), the solvent was removed by drying at 90 degreeC, and the 20-micrometer-thick adhesive layer was obtained. Then, by transferring the adhesive layer with the release film on the opposite side to the antistatic and antifouling side of the base film (PET film with antistatic and antifouling treatment on one side), "base film / adhesive layer / release The surface protection film of Example 1 which has the laminated constitution of "film" was obtained.

[Examples 2 to 6 and Comparative Examples 1 to 4]

Examples 2 to 6 and Comparative Example 1 were carried out in the same manner as in the surface protection film of Example 1, except that the composition of the additive was as described in (D) to (H) and (J) of Tables 1 and 2, respectively. The surface protection film of - 4 was obtained.

On the other hand, the surface protection films of Examples 1-6 and Comparative Examples 1-4 WHEREIN: All the gel fractions of an adhesive layer were in the range of 95 to 100%.

In Tables 1-2, the weight part of each component was calculated|required as 100 weight part of the sum total of the C1-C10 C1-C10 alkyl (meth)acrylate of (A) alkyl group.

In addition, in Tables 1 and 2, in each column of (B) to (H) and (J), 100 parts by weight of the acrylic polymer was used, and the content ratio (parts by weight) of each component was shown in parentheses ( ).

In addition, the compound name of the abbreviation of each component of (A)-(H) used in Tables 1-2 is shown in Table 3. On the other hand, Coronate (registered trademark) HX, Coronate HL, and Coronate L are trade names of Toso Corporation, and Takenate (registered trademark) D-140N, D-127N, and D-110N are trade names of Mitsui Chemicals Corporation.

(G) Among the antistatic agents, G-1 to G-4 have a melting point of 25°C or more and 80°C or less, and are ionic compounds that are solid at room temperature. G-5 is an ionic compound that has a melting point greater than 80° C. and is a solid at room temperature. In addition, (H) the weight average molecular weight of H-1 to H-6 in the polyether-modified siloxane compound is 10000 or less.

Table 4 shows the composition and molecular weight (Mw) of the monomers constituting the second acrylic polymer shown in the column (J) of Table 2. In addition, the compound name of the abbreviation of each component used for Table 4 is shown in Table 5. In Table 4, the weight part of each component made the sum total of (a) 100 weight part, and was calculated|required. In addition, in each column of (b)-(c), the content ratio (weight part) calculated|required by making the total of the 2nd acrylic polymer 100 weight part was shown with the numerical value in parentheses ( ).

(c) Among the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomers, I-1 to I-3 are monomers having a diester content of 0.2 wt% or less, and I-4 is a monomer having a diester content of 0.8 wt%. The value of n represents the average number of repetitions of an alkylene oxide.

<Test method and evaluation>

After aging the surface protection films in Examples 1-6 and Comparative Examples 1-4 in the atmosphere of a temperature of 23 degreeC and a humidity of 50%RH for 7 days, respectively, the following test methods evaluated.

<Test method of adhesion>

After peeling the release film and exposing the pressure-sensitive adhesive layer, the surface protection film was bonded to the surface of the polarizing plate through the pressure-sensitive adhesive layer, left for 1 day, autoclaved at 50° C., 5 atmospheres, 20 minutes, and further 12 hours at room temperature What was left to stand was made into the measurement sample of adhesive force. The obtained measurement sample was peeled at a low speed (0.3 m/min) or high speed (30 m/min) using a tensile tester in a 180 degree direction, and the measured peeling strength was made into adhesive force.

Here, the polarizer protective layer of the polarizing plate is polymethyl methacrylate (PMMA) having an AG-LR treated layer.

<Test method of surface resistivity>

After aging the surface protection film, the release film was peeled off before bonding to a polarizing plate to expose the pressure-sensitive adhesive layer, and the surface resistivity of the pressure-sensitive adhesive layer was measured using a resistivity meter Hirestar UP-HT450 (manufactured by Mitsubishi Chemical Analytech). .

<Test method of peeling electrification voltage>

The surface protection film in which the release film was peeled and the adhesive layer was exposed was bonded together to the polarizing plate which has the low-refractive-index layer formed using the composition for low-refractive-index layer formation containing a fluorine compound on the to-be-adhered surface. When the surface protection film is peeled 180° at a tensile speed of 30 m/min, the voltage (charged voltage) generated by the charging of the adherend is measured using high-precision electrostatic sensors SK-035 and SK-200 (manufactured by Keyence Co., Ltd.) And the maximum value of the measured value was made into peeling electrification voltage.

<Test method for stain resistance>

The polarizing plate which gave the low reflection (LR) surface treatment on the single side|surface of a glass plate was bonded together through the adhesive layer (double-sided adhesive tape) using the bonding machine. Then, the surface protection film was bonded together on the surface of the said polarizing plate using the bonding machine. After bonding to an adherend, it was left to stand for 2 days (48 hr) in an atmosphere of a temperature of 60°C and a humidity of 90% RH, and after taking out from the atmosphere, the surface protection film was peeled off and the surface of the polarizing plate was contaminated after 1 day had elapsed. The condition was visually observed. As for the judgment criterion of stain resistance performance, the case where there is no stain|pollution|contamination with respect to the surface of the said polarizing plate was evaluated as "○", the case where there was some stain|pollution|contamination by "Δ", and the case where there was stain|pollution|contamination was evaluated as "x".

In Table 6, the evaluation result about the surface protection film in Examples 1-6 and Comparative Examples 1-4 is shown. "Surface resistivity" was marked according to the method (where, m is an arbitrary real number, n is a positive integer) of the "m × 10 ^{+ n"} in "mE + n".

The column of "Pollution resistance performance" shows the material (TAC, PMMA, PET) and surface treatment (untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment) of the polarizer protective layer of the polarizing plate used in the test. Plain of "surface treatment" means untreated.

The surface protection films of Examples 1 to 6 had an adhesive force of 0.01 to 0.1 N/25 mm at a low peel rate of 0.3 m/min to a polarizing plate as an adherend, and an adhesive force of 1.0 N/25 mm at a high peel rate of 30 m/min. It was excellent in the adhesive performance by having the balance of adhesive force in the following points and a low-speed peeling rate and a high-speed peeling rate.

In addition, in the surface protection films of Examples 1 to 6, the surface resistivity of the pressure-sensitive adhesive layer is 1.0 × 10 ⁺¹² Ω/□ or less, and the pressure-sensitive adhesive layer for the low refractive index layer formed using a composition for forming a low refractive index layer containing a fluorine compound. The peeling electrification voltage was in the range of +0.3 to -0.3 kV, and the antistatic performance was excellent.

In addition, the surface protection films of Examples 1 to 6 were attached to an adherend, left to stand for 48 hours in an atmosphere of a temperature of 60° C. and a humidity of 90% RH, and taken out from the atmosphere, even after 1 day had elapsed. Contamination to various polarizing plates as an adherend There was no contamination, and the stain resistance performance was also excellent.

That is, according to the evaluation result shown in Table 6, it was demonstrated that the surface protection films of Examples 1-6 can solve the subject of this invention.

In the surface protection film of Comparative Example 1 (Tg of the monofunctional methacrylate monomer copolymerized with the first acrylic polymer is less than 0°C), the stain resistance performance was poor with respect to an adherend other than TAC.

In addition, in the surface protection film of Comparative Example 2 (the hydroxyl group-containing monomer copolymerized with the first acrylic polymer was excessive), the adhesive force at a low peeling rate was large, and the stain resistance performance was poor with respect to PMMA.

In addition, in the surface protection film of Comparative Example 3 (the first acrylic polymer does not contain a methacrylate monomer having a Tg of 0° C. or higher, the ratio of the carboxyl group-containing monomer is also excessive, and the melting point of the antistatic agent exceeds 80° C.), high-speed The adhesive force at the peeling rate was large, the peeling electrification voltage was high, and the stain resistance performance was poor.

In addition, the surface protection film of Comparative Example 4 (In Tables 1 and 2, the component (B) of Example 3, except that the component (A) of Comparative Example 4 did not contain a methacrylate monomer having a Tg of 0°C or higher. In to (H) and (the same as in (J)), compared with the surface protection film of Example 3, the adhesive force at a high-speed peeling rate was large, the peeling electrification voltage was high, and the stain resistance performance with respect to PMMA was inferior.

From the performance comparison of the surface protection film of Comparative Example 4 and the surface protection film of Example 3, in the pressure-sensitive adhesive composition according to the present invention, the Tg of the homopolymer is 0 ° C. or higher, containing at least one monofunctional methacrylate monomer It became clear that the thing contributed to having the balance of adhesive force in (1) a low-speed peeling rate and a high-speed peeling rate, and (2) having a contamination-resistance performance compatible.

Moreover, in the surface protection film of Comparative Examples 1-4 in this way, the subject of this invention could not be solved.

Claims (10)

A pressure-sensitive adhesive composition comprising a first acrylic polymer, an antistatic auxiliary agent, a crosslinking agent, and an ionic compound,
The first acrylic polymer
(A) 100 parts by weight of the total of at least two kinds of alkyl (meth)acrylates having C1-C10 carbon atoms in the alkyl group;
(B) 1.0 to 6.0 parts by weight of the total of at least one copolymerizable monomer containing a hydroxyl group;
(C) 0.01 to 0.6 parts by weight of at least one total of at least one copolymerizable monomer containing a carboxyl group
It is an acrylic polymer composed of a copolymer having an acid value of 0.1 to 1.0 and a weight average molecular weight of more than 300,000 and not more than 1 million,
(A) In a total of 100 parts by weight of at least two or more kinds of alkyl (meth)acrylates having C1-C10 carbon atoms in the alkyl group, 50 parts by weight or more of 2-ethylhexyl acrylate and Tg of the homopolymer is 0°C or more It is made by containing the sum of one or more types of monofunctional methacrylate monomers in a ratio of 5 to 40 parts by weight,
The pressure-sensitive adhesive composition contains a second acrylic polymer, which is a copolymer comprising at least one type of polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer as a copolymer component as the antistatic auxiliary agent,
The pressure-sensitive adhesive composition comprises a trifunctional or higher isocyanate compound as the crosslinking agent, a crosslinking retarder, and a crosslinking catalyst other than a tin compound as a crosslinking catalyst. The method of claim 1,
The second acrylic polymer is
(a) at least one or more kinds of (meth)acrylic acid ester monomers having C1-C18 carbon atoms in the alkyl group;
(b) at least one or more copolymerizable monomers containing a hydroxyl group;
(c) A pressure-sensitive adhesive composition comprising a copolymer obtained by copolymerizing at least one type of mono (meth)acrylic acid ester monomer containing a polyalkylene glycol chain. 3. The method according to claim 1 or 2,
The pressure-sensitive adhesive composition contains the antistatic auxiliary agent in a ratio of 0.1 to 5.0 parts by weight with respect to a total of 100 parts by weight of at least two or more kinds of alkyl (meth)acrylates having C1 to C10 carbon atoms in the (A) alkyl group. A pressure-sensitive adhesive composition. 3. The method according to claim 1 or 2,
The second acrylic polymer is
(a) with respect to a total of 100 parts by weight of at least one or more kinds of (meth)acrylic acid ester monomers having C1-C18 carbon atoms in the alkyl group,
(b) 2.0 to 12.0 parts by weight of the total of at least one copolymerizable monomer containing a hydroxyl group;
(c) Polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer copolymerized with 1 to 30 parts by weight in total of 1 to 30 parts by weight of the weight average molecular weight is a copolymer of more than 300,000 and 800,000 or less A pressure-sensitive adhesive composition. 3. The method of claim 2,
The value (B-1) of at least one total weight part of the copolymerizable monomer containing the hydroxyl group (B) contained in the first acrylic polymer with respect to 100 parts by weight of the total of the first acrylic polymer (B-1), and the second Ratio (b-1)/ (B-1) exists in the range of 1.0-2.0, The adhesive composition characterized by the above-mentioned. 3. The method according to claim 1 or 2,
The pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer used in a surface protection film for a polarizing plate,
The polarizer protective layer of the polarizing plate is one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film, and the surface treatment applied to the surface of the polarizer protective layer of the polarizing plate is untreated, AG treatment, LR A pressure-sensitive adhesive composition comprising one selected from the group consisting of treatment, AR treatment, AG-LR treatment, and AG-AR treatment. 3. The method according to claim 1 or 2,
The ionic compound is an ionic compound having a melting point of 25 to 80 °C,
The cation of the ionic compound is pyridinium,
The pressure-sensitive adhesive composition is characterized in that it contains the ionic compound as an essential component in a ratio of 0.01 to 10 parts by weight with respect to 100 parts by weight of the first acrylic polymer. An adhesive film in which an adhesive layer obtained by crosslinking the adhesive composition of claim 1 or 2 is laminated on one side of a resin film. A surface protection film for a polarizing plate using the adhesive film of claim 8. An optical film with a pressure-sensitive adhesive layer formed by laminating a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of claim 1 or 2 on at least one surface of the optical film.