JP7159399B2 - Adhesive composition and surface protective film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface protective film used in the manufacturing process of liquid crystal displays. More specifically, surface protection used to protect the surfaces of optical members such as polarizing plates and retardation plates by attaching them to the surfaces of optical members such as polarizing plates and retardation plates that make up liquid crystal displays. The present invention relates to an adhesive composition for films and a surface protection film using the same.

2. Description of the Related Art Conventionally, in the manufacturing process of optical members such as polarizing plates and retardation plates, which are members constituting liquid crystal displays, surface protective films are adhered to temporarily protect the surfaces of the optical members. Such a surface protective film is used only in the process of manufacturing the optical member, and is peeled off and removed from the optical member when the optical member is incorporated into the liquid crystal display. Such a surface protective film for protecting the surface of an optical member is generally called a process film because it is used only in the manufacturing process.

The surface protective film used in the process of manufacturing the optical member is an optically transparent polyethylene terephthalate (PET) resin film having an adhesive layer formed on one side thereof. A peel-treated release film for protecting the pressure-sensitive adhesive layer is laminated on the pressure-sensitive adhesive layer.
In addition, optical members such as polarizing plates and retardation plates are subjected to product inspection with optical evaluation such as display ability, hue, contrast, foreign matter contamination, etc. As a required performance for the surface protective film, it is required that the pressure-sensitive adhesive layer is free of air bubbles and foreign substances.
In recent years, when peeling off the surface protective film from optical members such as polarizing plates and retardation plates, the static electricity generated when the adhesive layer is peeled off by the adherend causes peeling electrification, which is caused by the electrical control of liquid crystal displays. There is a concern that it may affect the failure of the circuit, and excellent antistatic performance is required for the pressure-sensitive adhesive layer.
In addition, when a surface protective film is attached to an optical member such as a polarizing plate or a retardation plate, the surface protective film may be peeled off and then re-applied for various reasons. In addition, it is required to be easily peeled off from the optical member of the adherend (reworkability).
Moreover, when the surface protective film is finally peeled off from the optical members such as the polarizing plate and the retardation plate, it is required to be able to be quickly peeled off. It is required that the adhesive force does not change much with the peeling speed so that the adhesive can be quickly peeled even by so-called high-speed peeling.

As described above, in recent years, the required performance for the adhesive layer constituting the surface protective film is (1) balancing the adhesive strength at low peeling speed and high peeling speed, and (2) adhesive residue. (3) excellent antistatic performance, and (4) rework performance are required from the viewpoint of ease of use in using surface protective films.
However, although each of these (1) to (4), which are the required performances for the adhesive layer constituting the surface protective film, can be satisfied, the adhesive layer of the surface protective film is required. It was a very difficult task to simultaneously satisfy all of the required performances (1) to (4).

For example, the following proposals are known for (1) balancing adhesive strength at low and high peeling speeds and (2) preventing the occurrence of adhesive residue. .

An acrylic pressure-sensitive adhesive comprising, as a main component, a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group of 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound, and cross-linked with a cross-linking agent. In the case of the layer, there is a problem that the pressure-sensitive adhesive is transferred to the adherend when adhered for a long period of time, and the adhesive force to the adherend greatly increases with 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 this is crosslinked with a crosslinking agent. One having a treated pressure-sensitive adhesive layer is known (Patent Document 1).
Also, the same copolymer as above is mixed with a small amount of a copolymer of a (meth)acrylic acid alkyl ester and a carboxyl group-containing copolymerizable compound, and a pressure-sensitive adhesive layer is provided by cross-linking this with a cross-linking agent. etc., have been proposed. However, when these materials are used to protect the surface of plastic plates with low surface tension and smooth surfaces, they cause problems such as floating and peeling due to heating during processing and storage. There is also a problem of poor re-peelability at the time of peeling.

In order to solve these problems, a) 100 parts by weight of a (meth)acrylic acid alkyl ester mainly composed of a (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms, and b) a carboxyl group-containing 1 to 15 parts by weight of a copolymerizable compound and c) 3 to 100 parts by weight of a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms are added to the copolymer of the monomer mixture, the above b ) has been proposed a pressure-sensitive adhesive composition containing a cross-linking agent in an equivalent amount or more to the carboxyl groups of the component (Patent Document 2).
The pressure-sensitive adhesive composition described in Patent Document 2 does not cause a peeling phenomenon such as lifting during processing or storage, and furthermore, the increase in adhesive strength over time is small and removability is excellent. It can be re-peeled with a small force even after long-term storage, especially long-term storage in a high-temperature atmosphere, and no adhesive residue is left on the adherend.

As for (3) excellent antistatic performance, a method of kneading an antistatic agent into a base film is disclosed as a method for imparting antistatic properties to a surface protective film. Antistatic agents include, for example, (a) quaternary ammonium salts, pyridinium salts, various cationic antistatic agents having cationic groups such as primary to tertiary amino groups, (b) sulfonic acid groups, sulfuric acid Anionic antistatic agents having anionic groups such as ester bases, phosphate ester bases and phosphonate bases, (c) amphoteric antistatic agents such as amino acid-based and amino sulfate ester-based agents, (d) amino alcohol-based and glycerin-based , a nonionic antistatic agent such as polyethylene glycol, and (e) a polymeric antistatic agent obtained by increasing the molecular weight of the above antistatic agent (Patent Document 3).
In recent years, it has been proposed to incorporate such an antistatic agent into the base film, or directly into the pressure-sensitive adhesive layer instead of applying it to the surface of the base film.

In addition, (4) with regard to rework performance, for example, an adhesive made by blending a curing agent of an isocyanate compound and a specific silicate oligomer in an acrylic resin in an amount of 0.0001 to 10 parts by weight with respect to 100 parts by weight of the acrylic resin. An agent composition has been proposed (Patent Document 4).
In Patent Document 4, an acrylic acid alkyl ester having an alkyl group having about 2 to 12 carbon atoms or a methacrylic acid alkyl ester having an alkyl group having about 4 to 12 carbon atoms is used as a main monomer component. can contain other functional group-containing monomer components. In general, it is preferable to contain 50% by weight or more of the main monomer, and the content of the functional group-containing monomer component is 0.001 to 50% by weight, preferably 0.001 to 25% by weight, more preferably It states that it is desired to be 0.01 to 25% by weight. Such a pressure-sensitive adhesive composition described in Patent Document 4 shows little change over time in cohesive strength and adhesive strength even under high temperature or high temperature and high humidity conditions, and exhibits excellent adhesive strength to curved surfaces. It is said to have reworkability.
In general, if the pressure-sensitive adhesive layer has a soft property, adhesive residue tends to occur, and reworkability tends to deteriorate. That is, when it is pasted by mistake, it is difficult to peel off and re-sticking is likely to be difficult. For this reason, it is considered necessary to crosslink the main agent with a monomer having a functional group such as a carboxyl group to give the pressure-sensitive adhesive layer a certain degree of hardness in order to impart reworkability.

JP-A-63-225677 JP-A-11-256111 JP-A-11-070629 JP-A-8-199130

In the prior art, the required performance for the pressure-sensitive adhesive layer constituting the surface protective film is to balance the adhesive strength at low peeling speed and high peeling speed, excellent antistatic performance, rework performance, etc. It has been sought, but even if it is possible to satisfy the individual performance requirements, it has not been possible to satisfy all the performance requirements for the pressure-sensitive adhesive layer of the surface protection film.

The present invention has been made in view of the above circumstances, has excellent antistatic performance, has an excellent balance of adhesive strength at low peeling speed and high peeling speed, and furthermore has durability performance and rework. An object of the present invention is to provide a pressure-sensitive adhesive composition and a surface protective film which are also excellent in performance.

In order to solve the above problems, the present invention provides (A) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C4 to C18, and (B) a hydroxyl group-containing copolymer as a group of copolymerizable monomers. (C) a copolymerizable monomer containing a carboxyl group; (D) a polyalkylene glycol mono(meth)acrylic acid ester monomer; and (E) a nitrogen-containing vinyl monomer or an alkoxy group containing no hydroxyl groups. (F) a bifunctional or higher isocyanate compound; (G) a cross-linking catalyst; and (H) a ketoenol tautomer. (I) an ionic compound having a melting point of 25 to 50° C. as an antistatic agent and/or an acryloyl group-containing ionic compound; and (J) a polyether-modified siloxane compound, (D) polyalkylene glycol mono(meth)acrylic acid ester monomer has an average number of repeating alkylene oxides constituting a polyalkylene glycol chain of 3 to 14, and a diester content in the monomer is 0.3% or less, A polyalkylene glycol mono(meth)acrylic acid ester monomer having a water content of 0.1% or less and a haze value of 2% or less in a 20% aqueous solution with water solubility. To provide a pressure-sensitive adhesive composition.

In addition, with respect to the total 100 parts by weight of the acrylic polymer of the copolymer,
The acrylic polymer is
50 to 95 parts by weight of the (A) alkyl group having a carbon number of C4 to C18 (meth)acrylic acid ester monomer;
0.1 to 10 parts by weight of the (B) copolymerizable monomer containing a hydroxyl group;
0.1 to 1.0 parts by weight of the (C) copolymerizable monomer containing a carboxyl group;
0.1 to 50 parts by weight of the (D) polyalkylene glycol mono(meth)acrylate monomer,
0.1 to 20 parts by weight of (E) a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer that does not contain a hydroxyl group,
The adhesive composition is
0.1 to 10 parts by weight of the (F) difunctional or higher isocyanate compound,
0.001 to 0.5 parts by weight of the (G) crosslinking catalyst and 0.1 to 200 parts by weight of the (H) ketoenol tautomer compound, and further the (I) antistatic agent , a total of 0.05 to 5.0 parts by weight of the antistatic agent contained in the adhesive composition and the antistatic agent copolymerized in the copolymer;
0.01 to 1.0 parts by weight of the (J) polyether-modified siloxane compound,
It is preferable to contain

In addition, the (B) copolymerizable monomer containing a hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) ) acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

Further, the (C) carboxyl group-containing copolymerizable monomer is (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2-(meth) acryloyloxyethyl hexahydrophthal acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethylmalein It is preferably at least one selected from the group of compounds consisting of acids, carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloyloxyethyltetrahydrophthalic acid.

Further, the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer is selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkyleneglycol (meth)acrylate, and ethoxypolyalkyleneglycol (meth)acrylate. In addition, it is preferable that there is at least one kind or more.

The acrylic polymer preferably contains, as the copolymerizable monomer group, at least one of (E) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth)acrylate monomer.

Further, as the (F) di- or more functional isocyanate compound, the di-functional isocyanate compound is an acyclic aliphatic isocyanate compound and is preferably a compound produced by reacting a diisocyanate compound and a diol compound. The diisocyanate compound is an aliphatic diisocyanate and is preferably one selected from the compound group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Further, as the diol compound, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl -2-butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxy pivalate, polyethylene glycol, polypropylene glycol It is preferably composed of one selected from among.
In addition, as the (F) isocyanate compound having two or more functional groups, the trifunctional isocyanate compound includes an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, an adduct of a hexamethylene diisocyanate compound, and an isophorone diisocyanate compound. Adduct, burette of hexamethylene diisocyanate compound, burette of isophorone diisocyanate compound, isocyanurate of tolylene diisocyanate compound, isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, tolylene diisocyanate It is preferably at least one selected from the compound group consisting of adducts of compounds, adducts of xylylene diisocyanate compounds, and adducts of hydrogenated xylylene diisocyanate compounds.

Further, the (I) antistatic agent is an ionic compound having a melting point of 25 to 50° C., which is contained in an amount of 0.05 to 5.0 parts by weight per 100 parts by weight of the copolymer, and / Or, it is preferably an acryloyl group-containing ionic compound copolymerized in the copolymer in an amount of 0.05 to 5.0% by weight.

Further, the HLB value of (J) the polyether-modified siloxane compound is preferably 7-15.

In addition, the pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition has an adhesive strength of 0.05 to 0.1 N/25 mm at a low peeling speed of 0.3 m/min, and a high peeling speed of 30 m/min. is preferably 1.0 N/25 mm or less.

Further, the pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition preferably has a surface resistivity of 9.0×10 ⁺¹¹ Ω/□ or less and a peeling electrification voltage of ±0 to 0.5 kV.

The present invention also provides a pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition on one side or both sides of a resin film.

Further, the present invention provides a surface protection film comprising a pressure-sensitive adhesive layer formed by cross-linking the pressure-sensitive adhesive composition on one side of a resin film.

Moreover, the surface protective film of the present invention can be used as a surface protective film for polarizing plates.

Further, in the surface protection film of the present invention, it is preferable that the surface of the resin film opposite to the side on which the pressure-sensitive adhesive layer is formed is subjected to antistatic and antifouling treatment.

According to the present invention, it is possible to satisfy all the performances required for the pressure-sensitive adhesive layer of the surface protective film, which could not be solved by the prior art, and to obtain excellent antistatic performance. It was possible to prevent the remaining occurrence. Specifically, the amount of the antistatic agent added can be reduced while maintaining excellent antistatic performance, and the performance of preventing the occurrence of adhesive residue can be further improved.
Furthermore, the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer has an average repeating number of alkylene oxides constituting the polyalkylene glycol chain of 3 to 14, and the diester content in the monomer is 0.3% or less. With a water content of 0.1% or less and a haze value of 2% or less in an aqueous solution with a solubility of 20% in water, excellent polymerization stability and improved hydrophilicity Therefore, it becomes possible to form a pressure-sensitive adhesive layer having an excellent antistatic effect.

The present invention will be described below based on preferred embodiments.
The pressure-sensitive adhesive composition of the present invention comprises, as a main agent, (A) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C4 to C18, and (B) a copolymer containing a hydroxyl group as a group of copolymerizable monomers. (C) a copolymerizable monomer containing a carboxyl group; (D) a polyalkylene glycol mono(meth)acrylic acid ester monomer; and (E) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy A copolymer acrylic polymer containing at least one group-containing alkyl (meth)acrylate monomer, further comprising (F) a bifunctional or higher isocyanate compound, (G) a crosslinking catalyst, and (H) a ketoenol tautomer. (I) an ionic compound having a melting point of 25 to 50° C. as an antistatic agent and/or an acryloyl group-containing ionic compound; and (J) a polyether-modified siloxane compound, In the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer, the average number of repeating alkylene oxides constituting the polyalkylene glycol chain is 3 to 14, and the diester content in the monomer is 0.3% or less. , a polyalkylene glycol mono(meth)acrylic acid ester monomer having a water content of 0.1% or less and a haze value of 2% or less in a 20% aqueous solution with water solubility. and

Further, with respect to 100 parts by weight of the total acrylic polymer of the copolymer, the acrylic polymer is (A) 50 to 95 parts by weight of a (meth) acrylic acid ester monomer having a C4 to C18 alkyl group. and (B) 0.1 to 10 parts by weight of a copolymerizable monomer containing a hydroxyl group, (C) 0.1 to 1.0 parts by weight of a copolymerizable monomer containing a carboxyl group, ( D) 0.1 to 50 parts by weight of a polyalkylene glycol mono(meth)acrylic acid ester monomer, and (E) 0.1 to 20 parts of a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth)acrylate monomer. and parts by weight.

Further, with respect to 100 parts by weight of the total acrylic polymer of the copolymer, the pressure-sensitive adhesive composition contains (F) 0.1 to 10 parts by weight of a difunctional or higher isocyanate compound, and (G) a crosslinking catalyst. 0.001 to 0.5 parts by weight and (H) 0.1 to 200 parts by weight of a ketoenol tautomer compound, and (I) as an antistatic agent in the adhesive composition 0.05 to 5.0 parts by weight of the total of the antistatic agent contained and the antistatic agent copolymerized in the copolymer, and (J) 0.01 to 1 of the polyether-modified siloxane compound .0 parts by weight.

(A) Examples of (meth)acrylic acid ester monomers having alkyl groups of C4 to C18 carbon atoms include butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, ) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate ) acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, myristyl (meth)acrylate , isomyristyl (meth)acrylate, cetyl (meth)acrylate, isocetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and the like.
When the total acrylic polymer of the copolymer is 100 parts by weight, (A) a (meth)acrylic acid ester monomer having an alkyl group with a carbon number of C4 to C18 is contained in a proportion of 50 to 95 parts by weight. is preferred.

(B) Examples of copolymerizable monomers containing hydroxyl groups include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. hydroxyalkyl (meth)acrylates such as , and hydroxyl group-containing (meth)acrylamides such as N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide and N-hydroxyethyl(meth)acrylamide.
8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) ) at least one compound selected from the compound group consisting of acrylamide and N-hydroxyethyl (meth)acrylamide.
When the total amount of the acrylic polymer in the copolymer is 100 parts by weight, it is preferable that (B) the hydroxyl group-containing copolymerizable monomer is contained in a proportion of 0.1 to 10 parts by weight.

(C) a copolymerizable monomer containing a carboxyl group is (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2 - (meth) acryloyloxypropyl hexahydrophthalate, 2-(meth) acryloyloxyethyl phthalate, 2-(meth) acryloyloxyethyl succinate, 2-(meth) acryloyloxyethyl maleate, carboxy It is preferably at least one selected from the compound group consisting of polycaprolactone mono(meth)acrylate and 2-(meth)acryloyloxyethyltetrahydrophthalic acid.
When the total acrylic polymer of the copolymer is 100 parts by weight, it is preferable to contain (C) a copolymerizable monomer containing a carboxyl group in a proportion of 0.1 to 1.0 parts by weight. .

The (D) polyalkylene glycol mono(meth)acrylic acid ester monomer may be a compound in which one hydroxyl group among the 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 be copolymerized with the main polymer. Other hydroxyl groups may be OH as they are, alkyl ethers such as methyl ether and ethyl ether, saturated carboxylic acid esters such as acetic acid esters, and the like.
The alkylene group possessed by the polyalkylene glycol includes, but is not limited to, an ethylene group, a propylene group, a butylene group, and the like. The polyalkylene glycol may be a copolymer of two or more polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polybutylene glycol. Copolymers of polyalkylene glycol include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol and the like. It may be a block copolymer or a random copolymer.
(D) The polyalkylene glycol mono(meth)acrylic acid ester monomer preferably has an average repeating number of 3 to 14 for the alkylene oxide constituting the polyalkylene glycol chain. The "average number of repeating alkylene oxides" is the average number of repeating alkylene oxide units in the "polyalkylene glycol chain" portion contained in the molecular structure of the (D) polyalkylene glycol mono(meth)acrylate monomer. be.

(D) Polyalkylene glycol mono(meth)acrylic acid ester monomer has a diester content of 0.3% or less, a water content of 0.1% or less, and solubility in water The haze value in a 20% aqueous solution state is preferably 2% or less.
The "diester content in the monomer" is the content (% by weight) of the polyalkylene glycol di(meth)acrylate contained in the (D) polyalkylene glycol mono(meth)acrylate monomer.
The "moisture content" is the content (% by weight) of water contained in the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer.
The “haze value in a 20% aqueous solution state” is the haze value (%) of an aqueous solution of 20% by weight of (D) polyalkylene glycol mono(meth)acrylic acid ester monomer. That is, the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer not only has water solubility (solubility in water) enough to be a 20% aqueous solution, but also has a low haze value (%) in a 20% aqueous solution ( less white turbidity).
In this specification, the haze value of a 20% aqueous solution is a value measured by a haze meter after putting the solution in a quartz cell with an optical path length of 10 mm. This index was introduced to select a highly hydrophilic monomer that provides a solution without white turbidity even at a high concentration as the degree of hydrophilicity of the (D) polyalkylene glycol mono(meth)acrylate monomer. is.

(D) polyalkylene glycol mono(meth)acrylic acid ester monomer selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkyleneglycol (meth)acrylate, ethoxypolyalkyleneglycol (meth)acrylate, At least one or more is preferable.
More specifically, polyethylene glycol-mono (meth) acrylate, polypropylene glycol-mono (meth) acrylate, polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polypropylene glycol-mono (meth) acrylate, polyethylene glycol-poly Butylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, polyethylene glycol-polypropylene glycol-polybutylene glycol-mono(meth)acrylate; methoxypolyethylene glycol-(meth)acrylate, methoxypolypropylene glycol -(meth)acrylate, methoxypolybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polypropylene glycol-polybutylene Glycol-(meth)acrylate, methoxy-polyethyleneglycol-polypropyleneglycol-polybutyleneglycol-(meth)acrylate; ethoxypolyethyleneglycol-(meth)acrylate, ethoxypolypropyleneglycol-(meth)acrylate, ethoxypolybutyleneglycol-(meth)acrylate Acrylate, ethoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, ethoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, ethoxy-polypropylene glycol-polybutylene glycol-(meth)acrylate, ethoxy-polyethylene glycol-polypropylene glycol -polybutylene glycol-(meth)acrylate and the like.
When the total acrylic polymer of the copolymer is 100 parts by weight, it is preferable that the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer is contained in a proportion of 0.1 to 50 parts by weight.

Among (E), (E-1) nitrogen-containing vinyl monomers include vinyl monomers containing an amide bond, vinyl monomers containing an amino group, and vinyl monomers having a nitrogen-containing heterocyclic structure. More specifically, N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl Cyclic nitrogen vinyl compounds having an N-vinyl-substituted heterocyclic structure such as pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-vinyllauryrolactam; N-( meth) acryloylmorpholine, N-(meth)acryloylpiperazine, N-(meth)acryloylaziridine, N-(meth)acryloylazetidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylpiperidine, N-(meth) ) Cyclic nitrogen vinyl compounds having an N-(meth)acryloyl-substituted heterocyclic structure, such as acryloylazepane and N-(meth)acryloylazocane; N-cyclohexylmaleimide, N-phenylmaleimide, etc., nitrogen atoms and Cyclic nitrogen vinyl compounds having a heterocyclic structure having an ethylenically unsaturated bond in the ring; (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nt-butyl(meth) Unsubstituted or monoalkyl-substituted (meth)acrylamide such as acrylamide; N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropylacrylamide, N,N-diisopropyl (meth)acrylamide ) acrylamide, N,N-dibutyl (meth)acrylamide, N-ethyl-N-methyl (meth)acrylamide, N-methyl-N-propyl (meth)acrylamide, N-methyl-N-isopropyl (meth)acrylamide, etc. Dialkyl-substituted (meth)acrylamide; N,N-dimethylaminomethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminoisopropyl (meth) acrylate, N,N-dimethylaminobutyl (meth) acrylate, N,N-diethylaminomethyl (meth) acrylate, N,N-diethylaminoethyl (meth) acrylate, N-ethyl-N-methylaminoethyl (meth) ) acrylate, N-methyl-N-propylaminoethyl (meth)acrylate, N-methyl-N-isopropylaminoethyl (meth)acrylate t) acrylates, dialkylamino (meth)acrylates such as N,N-dibutylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate; N,N-dimethylaminopropyl (meth)acrylamide, N,N- Diethylaminopropyl (meth)acrylamide, N,N-dipropylaminopropyl (meth)acrylamide, N,N-diisopropylaminopropyl (meth)acrylamide, N-ethyl-N-methylaminopropyl (meth)acrylamide, N-methyl- N,N-dialkyl-substituted aminopropyl (meth)acrylamides such as N-propylaminopropyl (meth)acrylamide, N-methyl-N-isopropylaminopropyl (meth)acrylamide; N-vinylformamide, N-vinylacetamide, N- N-vinylcarboxylic acid amides such as vinyl-N-methylacetamide; N-methoxymethyl (meth)acrylamide, N-ethoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, diacetoneacrylamide, N, N - (meth)acrylamides such as methylenebis(meth)acrylamide; unsaturated carboxylic acid nitriles such as (meth)acrylonitrile; and the like.

As the nitrogen-containing vinyl monomer (E-1), those containing no hydroxyl group are preferable, and those containing neither hydroxyl group nor carboxyl group are more preferable. Such monomers include the monomers exemplified above, for example, acrylic monomers containing N,N-dialkyl-substituted amino groups and N,N-dialkyl-substituted amide groups; N-vinyl-2-pyrrolidone, N-vinyl N-vinyl-substituted lactams such as caprolactam and N-vinyl-2-piperidone; N-(meth)acryloyl-substituted cyclic amines such as N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine are preferred.

Among (E), (E-2) alkoxy group-containing alkyl (meth)acrylate monomers include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-isopropoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-methoxypropyl (meth)acrylate, 2-ethoxypropyl (meth)acrylate, 2-propoxypropyl (meth)acrylate, 2-isopropoxy Propyl (meth)acrylate, 2-butoxypropyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 3-propoxypropyl (meth)acrylate, 3-isopropoxypropyl (meth)acrylate Acrylates, 3-butoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, 4-propoxybutyl (meth)acrylate, 4-isopropoxybutyl (meth)acrylate, 4- butoxybutyl (meth)acrylate and the like.
These alkoxy group-containing alkyl(meth)acrylate monomers have a structure in which the alkyl group atoms in the alkyl(meth)acrylate are substituted with alkoxy groups.

The acrylic polymer preferably contains (E) at least one of hydroxyl-free nitrogen-containing vinyl monomers and alkoxy group-containing alkyl (meth)acrylate monomers as a group of copolymerizable monomers. When the total acrylic polymer of the copolymer is 100 parts by weight, (E-1) a nitrogen-containing vinyl monomer containing no hydroxyl group or (E-2) an alkoxy group-containing alkyl (meth)acrylate monomer is added in an amount of 0.1 to 100 parts by weight. It is preferably contained in a proportion of 20 parts by weight. (E-1) Nitrogen-containing vinyl monomers containing no hydroxyl groups and (E-2) alkoxy group-containing alkyl (meth)acrylate monomers may be used singly or in combination of two or more.

(F) The di- or more functional isocyanate compound may be at least one or two or more selected from polyisocyanate compounds having at least two or more isocyanate (NCO) groups in one molecule. Polyisocyanate compounds are classified into aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, alicyclic isocyanates, and the like, and any of them may be used. Specific examples of polyisocyanate compounds include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI). , hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylene diisocyanate (TOID), and tolylene diisocyanate (TDI).
Examples of trifunctional or higher isocyanate compounds include bifunctional isocyanate compounds (compounds having two NCO groups in one molecule) with burette modification and isocyanurate modification, trimethylolpropane (TMP), glycerin and the like. and an adduct (polyol modified product) with a polyol (compound having at least 3 or more OH groups in one molecule).
As the (F) difunctional or higher isocyanate compound, it is possible to use (F-1) the trifunctional isocyanate compound alone or (F-2) the difunctional isocyanate compound alone. It is also possible to use (F-1) a trifunctional isocyanate compound and (F-2) a bifunctional isocyanate compound in combination.

Furthermore, the (F-1) trifunctional isocyanate compound used in the present invention includes 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, (F-1-1) at least one or more selected from the group of first aliphatic isocyanate compounds consisting of a buret form of a hexamethylene diisocyanate compound and a burette form of an isophorone diisocyanate compound, and a tolylene diisocyanate compound. isocyanurate, isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, adduct of tolylene diisocyanate compound, adduct of xylylene diisocyanate compound, adduct of hydrogenated xylylene diisocyanate compound (F-1-2) at least one selected from the group of second aromatic isocyanate compounds. It is preferable to use (F-1-1) the first group of aliphatic isocyanate compounds and (F-1-2) the second group of aromatic isocyanate compounds in combination. In the present invention, (F-1) as the trifunctional isocyanate compound, (F-1-1) at least one or more selected from the first group of aliphatic isocyanate compounds, and (F-1-2 ) By using at least one or more selected from the second aromatic isocyanate compound group, the balance of adhesive strength in the low-speed peeling region and the high-speed peeling region can be further improved.
Further, (F-1) the trifunctional isocyanate compound comprises at least one or more selected from the first aliphatic isocyanate compound group (F-1-1), and the (F-1-2 ) containing 0.5 to 5.0 parts by weight in total with respect to 100 parts by weight of the copolymer, at least one selected from the second group of aromatic isocyanate compounds. preferably (F-1-1) at least one selected from the first group of aliphatic isocyanate compounds, and (F-1-2) from the second group of aromatic isocyanate compounds The mixing ratio of (F-1-1):(F-1-2) with at least one or more selected from is within the range of 10%:90% to 90%:10% by weight. is preferred.

Furthermore, the (F-2) bifunctional isocyanate compound used in the present invention is an acyclic aliphatic isocyanate compound, and is preferably a compound produced by reacting a diisocyanate compound with a diol compound.
For example, a diisocyanate compound in the general formula "O=C=N-X-N=C=O" (where X is a divalent group), the general formula "HO-Y-OH" (where Y is a divalent group ) represents the diol compound, examples of the compound produced by reacting the diisocyanate compound and the diol compound include compounds represented by the following general formula Z.

[general formula Z]
O=C=N-X-(NH-CO-O-Y-O-CO-NH-X) _n -N=C=O

Here, n is an integer of 0 or more. When n is 0, the general formula Z represents "O=C=N-X-N=C=O". As the bifunctional acyclic aliphatic isocyanate compound, a compound in which n is 0 in the general formula Z (a diisocyanate compound that has not reacted with the diol compound) may be included, but a compound in which n is an integer of 1 or more is an essential component. It is preferable to include as The difunctional acyclic aliphatic isocyanate compound may be a mixture of compounds in which n in the general formula Z is different.

A diisocyanate compound represented by the general formula "O=C=N-X-N=C=O" is an aliphatic diisocyanate. X is preferably an acyclic, aliphatic, divalent group. The aliphatic diisocyanate is preferably one or more selected from the compound group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

A diol compound represented by the general formula “HO—Y—OH” is an aliphatic diol. Y is preferably an acyclic, aliphatic, divalent group. Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2 -butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxy pivalate, polyethylene glycol, polypropylene glycol It is preferable to consist of one selected or two or more selected.

The weight ratio (F-1/F-2) of the (F-1) trifunctional isocyanate compound to the (F-2) bifunctional isocyanate compound is preferably 1-90.
When the total acrylic polymer of the copolymer is 100 parts by weight, it is preferable that (F) the isocyanate compound having a functionality of 2 or more is contained in a proportion of 0.1 to 10 parts by weight.

(G) The cross-linking catalyst may be any substance that functions as a catalyst for the reaction (cross-linking reaction) between the copolymer and the cross-linking agent when a polyisocyanate compound is used as the cross-linking agent, such as a tertiary amine. amine compounds, metal chelate compounds, organotin compounds, organolead compounds, organometallic compounds such as organozinc compounds, and the like.
Tertiary amines include trialkylamines, N,N,N',N'-tetraalkyldiamines, N,N-dialkylaminoalcohols, triethylenediamine, morpholine derivatives, piperazine derivatives and the like.

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 bound to the metal atom M. For example, when the general formula of a metal chelate compound having one metal atom M is represented by M(L) _m (X) _n , m≧1 and n≧0. When m is 2 or more, m L may be the same ligand or different ligands. When n is 2 or more, n Xs may be the same ligand or different ligands.

Metal atoms M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, Sn and the like.
Examples of the multidentate ligand L include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate and stearyl acetoacetate, acetylacetone (also known as 2,4-pentanedione), β-diketones such as 2,4-hexanedione and benzoylacetone. These are keto-enol tautomeric compounds, which in the polydentate ligand L may be deprotonated enolates of enols (eg acetylacetonate).
The monodentate ligand X includes halogen atoms such as chlorine and bromine atoms, acyloxy groups such as pentanoyl, hexanoyl, 2-ethylhexanoyl, octanoyl, nonanoyl, decanoyl, dodecanoyl and octadecanoyl group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, alkoxy group such as butoxy group, and the like.

Specific examples of metal chelate compounds include tris(2,4-pentanedionato)iron (III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum tris Acetylacetonate, zirconium tetrakisacetylacetonate, tris(2,4-hexanedionato)iron(III), bis(2,4-hexanedionato)zinc, tris(2,4-hexanedionato)titanium, tris (2,4-hexanedionato)aluminum, tetrakis(2,4-hexanedionato)zirconium and the like.

Examples of organic tin compounds include dialkyltin oxides, dialkyltin fatty acid salts, stannous fatty acid salts, and the like.
(G) The crosslinking catalyst is preferably a metal chelate compound or an organic tin compound. As metal chelate compounds, aluminum chelate compounds, titanium chelate compounds, iron chelate compounds, tin chelate compounds and the like are preferable. The organic tin compound is preferably at least one selected from the compound group consisting of dioctyltin oxide and dioctyltin dilaurate.
When the total acrylic polymer of the copolymer is 100 parts by weight, (G) the cross-linking catalyst is preferably contained in a proportion of 0.001 to 0.5 parts by weight.

(H) Ketoenol tautomer compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate and stearyl acetoacetate, acetylacetone and 2,4-hexanedione. , β-diketones such as benzoylacetone. (H) The keto-enol tautomeric compound blocks the isocyanate group of the cross-linking agent in the pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, thereby causing excessive viscosity of the pressure-sensitive adhesive composition after blending the cross-linking agent. It is possible to suppress the rise and gelation and extend the pot life of the pressure-sensitive adhesive composition.
(H) As the keto-enol tautomeric compound, at least one compound selected from the group of compounds consisting of acetylacetone and ethyl acetoacetate is preferable.
It is preferable that the (H) ketoenol tautomer compound is contained in a proportion of 0.1 to 200 parts by weight when the total acrylic polymer of the copolymer is 100 parts by weight.

(H) The ketoenol tautomer compound has the effect of suppressing crosslinking, contrary to the (G) crosslinking catalyst, so the ratio of the (H) ketoenol tautomer compound to the (G) crosslinking catalyst is appropriately adjusted. is preferably set to In order to prolong the pot life of the pressure-sensitive adhesive composition and improve the storage stability, the weight part ratio (H)/(G) of (H) ketoenol tautomer compound/(G) crosslinking catalyst is higher. preferable. The value of (H)/(G) is preferably in the range of 1-700, more preferably 30-300, most preferably 80-300.

(I) The antistatic agent includes an antistatic agent contained in the pressure-sensitive adhesive composition and an antistatic agent copolymerized in the copolymer. The total content of (I) the antistatic agent is preferably 0.05 to 5.0 parts by weight per 100 parts by weight of the acrylic polymer in the copolymer.
(I) The antistatic agent is preferably (I-1) an ionic compound having a melting point of 25 to 50° C. and/or (I-2) an acryloyl group-containing ionic compound.
In the present invention, (I) as an antistatic agent, (I-1) an ionic compound having a melting point of 25 to 50° C. is added to the copolymer, and/or (I-2) an acryloyl group-containing ionic compound is copolymerized into the copolymer. Since these antistatic agents (I) have low melting points and long-chain alkyl groups, they are presumed to have high affinity with acrylic copolymers.

(I-1) The ionic compound having a melting point of 25 to 50° C. is an ionic compound having a cation and an anion, wherein the cation is a pyridinium cation, an imidazolium cation, a pyrimidinium cation, or a pyrazolium cation. , pyrrolidinium cations, nitrogen _- containing onium cations such as ammonium cations, phosphonium cations ^, sulfonium cations, ^and the like. acid salt (RC ₆ H ₄ SO ₃ ⁻ ), perchlorate (ClO ₄ ⁻ ), tetrafluoroborate (BF ₄ ⁻ ), bis(fluorosulfonyl)imide salt (FSI), bis(trifluoromethanesulfonyl ) Compounds that are inorganic or organic anions such as imide salts (TFSI) and trifluoromethanesulfonates (TF). It is preferably solid at room temperature (for example, 25° C.), and a melting point of 25 to 50° C. can be obtained by selecting the chain length of the alkyl group, the position and number of substituents, and the like. The cation is preferably a quaternary nitrogen-containing onium cation, such as quaternary pyridinium cations such as 1-alkylpyridinium (the carbon atoms at positions 2 to 6 may be substituted or unsubstituted), and 1, quaternary imidazolium cations such as 3-dialkylimidazolium (carbon atoms at positions 2, 4 and 5 may be substituted or unsubstituted); quaternary ammonium cations such as tetraalkylammonium; .
(I-1) The ionic compound having a melting point of 25 to 50° C. is preferably contained in an amount of 0.05 to 5.0 parts by weight per 100 parts by weight of the copolymer.

The acryloyl group-containing ionic compound (I-2) is an ionic compound having a cation and an anion, wherein the cation is (meth)acryloyloxyalkyltrialkylammonium [R ₃ N ⁺ -C _n H _2n -OCOCQ =CH ₂ with Q=H or CH ₃ , R=alkyl], and the anions are phosphate hexafluoride (PF ₆ ⁻ ), thiocyanate (SCN ⁻ ), organic sulfonate (RSO ₃ ⁻ ), perchlorate (ClO ₄ ⁻ ), tetrafluoroborate (BF ₄ ⁻ ), ^F -containing imide salt (RF ₂ N ⁻ ), etc. Compounds that are anions are included. R ^F of the F-containing imide salt (R ^F ₂ N ⁻ ) includes a perfluoroalkanesulfonyl group such as a trifluoromethanesulfonyl group and a pentafluoroethanesulfonyl group, and a fluorosulfonyl group. Examples of F-containing imide salts include bis(fluorosulfonyl)imide salt [(FSO ₂ ) ₂ N ⁻ ], bis(trifluoromethanesulfonyl)imide salt [(CF ₃ SO ₂ ) ₂ N ⁻ ], bis(pentafluoroethanesulfonyl ) and bissulfonylimide salts such as imide salts [(C ₂ F ₅ SO ₂ ) ₂ N ⁻ ].
(I-2) The acryloyl group-containing ionic compound is preferably copolymerized in an amount of 0.05 to 5.0% by weight in the copolymer.

Specific examples of (I) the antistatic agent are not particularly limited, but specific examples of the (I-1) ionic compound having a melting point of 25 to 50° C. include 1-octylpyridinium phosphorus hexafluoride acid, 1-nonylpyridinium hexafluorophosphate, 2-methyl-1-dodecylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecyl pyridinium dodecylbenzenesulfonate, 4-methyl-1-octylpyridinium hexafluorophosphate, quaternary ammonium trifluoromethanesulfonic acid and the like. (I-2) Specific examples of the acryloyl group-containing ionic compound include dimethylaminomethyl (meth)acrylate methyl hexafluorophosphate [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ PF ₆ ⁻ , where Q=H or CH ₃ ], dimethylaminoethyl (meth)acrylate bis(trifluoromethanesulfonyl)imidomethyl salt [(CH ₃ ) ₃ N ⁺ (CH ₂ ) ₂ OCOCQ=CH _2. (CF ₃ SO ₂ ) ₂ N ⁻ , where Q=H or CH ₃ ], dimethylaminomethyl methacrylate bis(fluorosulfonyl)imidomethyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH _2. (FSO ₂ ) ₂ N ⁻ , where , Q=H or CH ₃ ] and the like.

The pressure-sensitive adhesive composition of the present invention contains (J) a polyether-modified siloxane compound. (J) _The polyether ^- modified siloxane compound is ^a siloxane compound having a polyether group. ² O(R ³ O) _n R ⁴ )—O—]. Here, R ¹ is one or two or more alkyl groups or aryl groups, R ² and R ³ are one or two or more alkylene groups, and R ⁴ is one or two or more alkyl groups or acyl groups. etc. (end group). The polyether group includes polyoxyalkylene groups such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] and a polyoxypropylene group [(C ₃ H ₆ O) _n ].
(J) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 7-15. HLB is the hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) defined, for example, in JIS K3211 (surfactant terms).
(J) The polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a silicon hydride group through a hydrosilylation reaction. can. Specifically, dimethylsiloxane/methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxyethylene) siloxane/methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxypropylene) A siloxane polymer etc. are mentioned.
By incorporating (J) the polyether-modified siloxane compound into the adhesive composition, the adhesive strength and rework performance of the adhesive can be improved. It is preferable that (J) the polyether-modified siloxane compound is contained in a proportion of 0.01 to 1.0 parts by weight when the total acrylic polymer of the copolymer is 100 parts by weight.

Furthermore, as other components, copolymerizable (meth) acrylic monomers containing alkylene oxide, (meth) acrylamide monomers, dialkyl-substituted acrylamide monomers, surfactants, curing accelerators, plasticizers, fillers, curing retarders, Known additives such as processing aids, anti-aging agents, and antioxidants can be appropriately added. These are used alone or in combination of two or more.

The copolymer of the main agent used in the pressure-sensitive adhesive composition of the present invention includes (A) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C4 to C18 and (B) a hydroxyl group-containing copolymerizable a monomer, (C) a copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono(meth)acrylic acid ester monomer, and (E) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl It can be synthesized by polymerizing at least one (meth)acrylate monomer. The polymerization method of the copolymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.
(I) When an acryloyl group-containing ionic compound (I-2) is used as an antistatic agent, the copolymer of the main agent used in the pressure-sensitive adhesive composition of the present invention has (A) an alkyl group with a carbon number of C4 to C18 (meth) acrylic acid ester monomer, (B) a copolymerizable monomer containing a hydroxyl group, (C) a copolymerizable monomer containing a carboxyl group, and (D) a polyalkylene glycol mono(meth) Synthesized by polymerizing an acrylic acid ester monomer, (E) at least one nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth)acrylate monomer, and (I-2) an acryloyl group-containing ionic compound. be able to.
The pressure-sensitive adhesive composition of the present invention comprises the above copolymer, (F) a difunctional or higher isocyanate compound, (G) a crosslinking catalyst, (H) a ketoenol tautomer compound, and (I) an antistatic As an agent, an ionic compound having a melting point of 25 to 50 ° C. and / or an acryloyl group-containing ionic compound, (J) a polyether-modified siloxane compound, and an appropriate optional additive are blended. be able to. When the (I-2) acryloyl group-containing ionic compound is polymerized in the copolymer of the main agent, the antistatic agent (I) may be further added to the copolymer, or may not be added. I don't mind.

In the production of the main copolymer, it is preferable to carry out the polymerization reaction under anhydrous conditions, such as solution polymerization using an anhydrous organic solvent, in order to reduce the contamination of water in the pressure-sensitive adhesive composition. In particular, since the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer is highly hydrophilic, it is preferable to use one having a low moisture content.
In order to avoid an increase in the viscosity of the pressure-sensitive adhesive composition, each monomer used in the production of the copolymer of the main agent should contain as much as possible a polyfunctional (bifunctional or higher) monomer that can function as a cross-linking agent. preferably reduced. In particular, (D) polyalkylene glycol mono(meth)acrylic acid ester monomer has a low diester content because the corresponding diester content is a di(meth)acrylic acid ester of a bifunctional monomer.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of acrylic monomers such as (meth)acrylic acid ester monomers, (meth)acrylic acid, and (meth)acrylamides.
Also, the acid value of the acrylic polymer is preferably 0.01 to 8.0. As a result, it is possible to improve the staining property and improve the adhesive residue prevention performance.
Here, the "acid value" is one index of the acid content, and is expressed in mg of potassium hydroxide required to neutralize 1 g of a polymer containing a carboxyl group.

The pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition has an adhesive strength of 0.05 to 0.1 N/25 mm at a low peel speed of 0.3 m / min, and a high peel speed of 30 m / min. It is preferable that the adhesive strength is 1.0 N/25 mm or less. As a result, it is possible to obtain a performance in which the adhesive strength does not change much depending on the peeling speed, and it is possible to peel off quickly even with high-speed peeling. Moreover, when the surface protective film is once peeled off for reattachment, it is easy to peel off from the adherend without requiring excessive force.

The pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition preferably has a surface resistivity of 9.0×10 ⁺¹¹ Ω/□ or less and a peel electrostatic voltage of ±0 to 0.5 kV. In the present invention, "±0 to 0.5 kV" means 0 to -0.5 kV and 0 to +0.5 kV, that is, -0.5 to +0.5 kV. If the surface resistivity is high, the static electricity generated by charging at the time of peeling is inferior to the ability to escape. The charged voltage is reduced, and the influence on the electrical control circuit of the adherend can be suppressed.

The gel fraction of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive after cross-linking) formed by crosslinking the pressure-sensitive adhesive composition of the present invention is preferably 95 to 100%. Due to such a high gel fraction, the adhesive strength does not become excessive at low peeling speeds, and the elution of unpolymerized monomers or oligomers from the copolymer is reduced, resulting in reworkability and high temperature and high humidity. Durability is improved, and contamination of adherends can be suppressed.

The pressure-sensitive adhesive film of the present invention is obtained by forming a pressure-sensitive adhesive layer formed by cross-linking the pressure-sensitive adhesive composition of the present invention on one side or both sides of a resin film. Further, the surface protective film of the present invention is a surface protective film obtained by forming a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present invention on one side of a resin film. Since the components (A) to (J) described above are blended in a well-balanced manner, the pressure-sensitive adhesive composition of the present invention has excellent antistatic performance, and at low peeling speed and high peeling speed, Excellent balance of adhesive force, durability performance, and rework performance (no contamination transfer to the adherend after tracing the surface protective film through the adhesive layer with a ballpoint pen). Become. Therefore, it can be suitably used as a surface protection film for polarizing plates.

A resin film such as a polyester film can be used as the base film of the pressure-sensitive adhesive layer and the release film (separator) that protects the pressure-sensitive adhesive surface.
On the side of the base film opposite to the side of the resin film on which the pressure-sensitive adhesive layer is formed, silicone-based or fluorine-based release agents or coating agents, antifouling treatment with silica fine particles, etc., antistatic agent coating, Antistatic treatment such as kneading can be applied.
The release film is subjected to release treatment with a silicone-based or fluorine-based release agent or the like on the side of the release film that is to be matched with the adhesive surface of the adhesive layer.

EXAMPLES The present invention will be specifically described below with reference to examples.

<Production of acrylic copolymer>
[Example 1]
Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube to replace the air in the reactor with nitrogen gas. After that, 100 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 8-hydroxyoctyl acrylate, 0.4 parts by weight of acrylic acid, polypropylene glycol monoacrylate (average number of repeating alkylene oxides constituting the polyalkylene glycol chain) was added to the reactor. n=12, diester content in monomer is 0.1%, solubility in water is 20%, haze value in aqueous solution is 0.8, water content is 0.05%) 8 parts by weight, N-vinylpyrrolidone 60 parts by weight of a solvent (ethyl acetate) was added along with 5 parts by weight. Thereafter, 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and reacted at 65° C. for 6 hours to obtain an acrylic copolymer solution having a weight average molecular weight of 500,000 and used in Example 1. got 1. A part of the acrylic copolymer was sampled and used as a sample for acid value measurement, which will be described later.
[Examples 2 to 9 and Comparative Examples 1 to 4]
In the same manner as acrylic copolymer solution 1 used in Example 1 above, except that the compositions of the monomers are set as described in (A) to (E) and (I-2) in Table 1. , to obtain acrylic copolymer solutions used in Examples 2 to 9 and Comparative Examples 1 to 4.

<Production of pressure-sensitive adhesive composition and surface protection film>
[Example 1]
1.0 parts by weight of 1-octylpyridinium hexafluorophosphate, 8.5 parts by weight of acetylacetone, and a polyether-modified siloxane compound (HLB= 7) was added and stirred, and then 2.5 parts by weight of Coronate HX (an isocyanurate form of a hexamethylene diisocyanate compound) and 0.1 part by weight of titanium trisacetylacetonate were added and mixed with stirring to obtain the pressure-sensitive adhesive composition of Example 1. got stuff After applying this adhesive composition on a release film made of a polyethylene terephthalate (PET) film coated with a silicone resin, the solvent is removed by drying at 90 ° C., and the thickness of the adhesive layer is 25 μm. got a sheet.
After that, the pressure-sensitive adhesive sheet is transferred to the opposite side of the antistatic and antifouling treated side of the polyethylene terephthalate (PET) film having one side antistatic and antifouling treated. A surface protective film of Example 1 having a laminated structure of "PET film/adhesive layer/release film (silicone resin-coated PET film)" was obtained.
[Examples 2 to 9 and Comparative Examples 1 to 4]
Examples 2 to 9 and Comparative Examples 1 to 2 were prepared in the same manner as the surface protective film of Example 1 above, except that the compositions of the additives were each as described in (F) to (J) in Table 2. 4 surface protective film was obtained.

Tables 1 and 2 are an integral table showing the compounding ratio of each component divided into two, and in both cases the total weight of group (A) is 100 parts by weight. indicated by . In addition, Tables 3 and 4 show the compound names of the abbreviations of the components used in Tables 1 and 2. Coronate (registered trademark) HX, HL and L are trade names of Nippon Polyurethane Industry Co., Ltd. Takenate (registered trademark) D-140N, D-127N, D-110N and D-120N are Mitsui Chemicals, Inc. The company's product name. Regarding group (D) in Table 3, the numerical value of "n" is the average repeating number of alkylene oxides constituting the polyalkylene glycol chain. The numerical value of "diester" is the diester content (%) in the monomer. The numerical value of "moisture content" is the moisture content (%). The numerical value of "haze" is the haze value (%) in a 20% aqueous solution state.
In Table 1, among (I) antistatic agents, (I-2) acryloyl group-containing ionic compound copolymerized in the copolymer is added after polymerization (I) antistatic agent described in the column.

<Synthesis of bifunctional isocyanate compound>
The bifunctional isocyanate compounds of Synthesis Examples 1 to 3 were synthesized by the following method. As shown in Tables 5 and 6, a diisocyanate and a diol compound were mixed at a molar ratio of NCO/OH=16, reacted at 120° C. for 3 hours, and then evaporated under reduced pressure using a thin film evaporator. Unreacted diisocyanate was removed to obtain the desired bifunctional isocyanate compound.

<Test method and evaluation>
After aging the surface protective films in Examples 1 to 9 and Comparative Examples 1 to 4 in an atmosphere of 23 ° C. and 50% RH for 7 days, peel off the release film (silicone resin-coated PET film) and remove the adhesive. The exposed layer was used as a sample for surface resistivity measurement.
Furthermore, the surface protective film with the adhesive layer exposed is attached to the surface of the polarizing plate attached to the liquid crystal cell via the adhesive layer, left for one day, and then left at 50° C. for 20 minutes at 5 atm. After being autoclaved and allowed to stand at room temperature for 12 hours, the adhesive strength, peeling electrification voltage, reworkability and durability were measured.

<Adhesive strength>
The measurement sample obtained above (a surface protective film with a width of 25 mm was attached to the surface of the polarizing plate) was peeled at a low speed (0.3 m / min) and a high speed using a tensile tester in a 180 ° direction. was peeled off at a peel speed (30 m/min), and the measured peel strength was taken as the adhesive strength.

<Surface resistivity>
After aging, before bonding to the polarizing plate, the release film (silicone resin-coated PET film) is peeled off to expose the adhesive layer, and a resistivity meter Hiresta UP-HT450 (manufactured by Mitsubishi Chemical Analytic Tech) is used. The surface resistivity of the adhesive layer was measured.

<Peeling electrification voltage>
The voltage (charged voltage) generated when the polarizing plate is charged when the measurement sample obtained above is peeled 180° at a tensile speed of 30 m / min is measured by high-precision electrostatic sensors SK-035 and SK-200 (stock (manufactured by Keyence Corporation), and the maximum measured value was taken as the peeling electrification voltage.

<Reworkability>
After tracing the surface protective film of the measurement sample obtained above with a ballpoint pen (load 500 g, 3 reciprocations), the surface protective film was peeled off from the polarizing plate and the surface of the polarizing plate was observed. Confirmed no migration. The evaluation target criteria are "○" when there is no contamination transfer to the polarizing plate, "△" when contamination transfer is confirmed at least partially along the trace traced with the ballpoint pen, and along the trace traced with the ballpoint pen. A case where transfer of contamination was confirmed and separation of the adhesive from the surface of the adhesive was also confirmed was evaluated as "x".

<Durability>
After leaving the measurement sample obtained above in an atmosphere of 60 ° C. and 90% RH for 250 hours, taking it out to room temperature and leaving it for another 12 hours, the adhesive strength is measured and compared with the initial adhesive strength. It was confirmed that there was no significant increase. As for the evaluation target criteria, when the adhesive strength after the test was 1.5 times or less of the initial adhesive strength, it was evaluated as "good", and when it exceeded 1.5 times, it was evaluated as "poor".

Table 7 shows the evaluation results. In addition, the surface resistivity was expressed by a method of setting "m×10 ⁺ⁿ " to "mE+n" (where m is an arbitrary real number and n is a positive integer).

The surface protective films of Examples 1 to 9 have an adhesive strength of 0.05 to 0.1 N/25 mm at a low peel speed of 0.3 m / min, and an adhesive strength of 1 at a high peel speed of 30 m / min. 0 N/25 mm or less, a surface resistivity of 9.0×10 ⁺¹¹ Ω/□ or less, a peeling electrification voltage of ±0 to 0.5 kV, and a pressure-sensitive adhesive layer on the surface protective film. There was no transfer of contamination to the adherend after tracing with a ballpoint pen, and the durability was also excellent when left in an atmosphere of 60°C and 90% RH for 250 hours.
That is, (1) balance of adhesive strength at low and high peel speeds, (2) prevention of adhesive residue, (3) excellent antistatic performance, and (4) All requirements for rework performance are satisfied at the same time.

Since the surface protective film of Comparative Example 1 does not contain (F) a bifunctional or higher isocyanate compound, (G) a crosslinking catalyst, and (H) a ketoenol tautomer compound, the peeling speed is as high as 0.3 m/min. The adhesive strength at a peeling speed of 30 m/min was too large, the surface resistivity and peeling electrification voltage were high, and the reworkability and durability were poor.
The surface protective film of Comparative Example 2 has a large average repeating number of alkylene oxides constituting the polyalkylene glycol chain of the (D) polyalkylene glycol mono(meth)acrylate monomer, a large diester content, and a high moisture content. Possibly due to the low solubility in water, the adhesive force at a low peeling speed of 0.3 m/min and a high peeling speed of 30 m/min is too large, the surface resistivity and peeling electrification voltage are high, and the durability is poor. rice field.
The surface protective film of Comparative Example 3 has a large average repeating number of alkylene oxides constituting the polyalkylene glycol chain of the (D) polyalkylene glycol mono(meth)acrylate monomer, a large diester content, and a high moisture content. Possibly due to the low solubility in water, the pot life was too short and cross-linking progressed before coating, so coating could not be carried out.
The surface protective film of Comparative Example 4 has a large diester content of the (D) polyalkylene glycol mono(meth)acrylate monomer, has a high water content, and is poorly polymerizable and viscous, probably because it has a high water content and low solubility in water. Coating could not be performed due to defects.
Thus, in the surface protective films of Comparative Examples 1 to 4, (1) the adhesive strength was balanced at low peeling speed and high peeling speed, (2) the occurrence of adhesive residue was prevented, (3) excellent antistatic performance and (4) rework performance could not be satisfied at the same time.

Claims (5)

A pressure-sensitive adhesive composition containing an acrylic polymer,
The acrylic polymer, relative to the total 100 parts by weight of the acrylic polymer,
(A) 50 to 95 parts by weight of a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C4 to C18;
(B) 0.1 to 10 parts by weight of a copolymerizable monomer containing a hydroxyl group;
(C) 0.1 to 1.0 parts by weight of a copolymerizable monomer containing a carboxyl group;
(D) 0.1 to 50 parts by weight of a polyalkylene glycol mono(meth)acrylate monomer;
(E) copolymerized with 0.1 to 20 parts by weight of a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer that does not contain a hydroxyl group,
The pressure-sensitive adhesive composition further
(F) 0.1 to 10 parts by weight of a bifunctional or higher isocyanate compound,
(G) 0.001 to 0.5 parts by weight of a cross-linking catalyst;
(H) 0.1 to 200 parts by weight of a ketoenol tautomer compound;
(I) As an antistatic agent, 0.05 to 5.0 parts by weight of an ionic compound having a solid melting point of 25 to 50°C at a temperature of 25°C, and/or copolymerized in the acrylic polymer 0.05 to 5.0 parts by weight of an ionic compound containing an acryloyl group;
(J) 0.01 to 1.0 parts by weight of a polyether-modified siloxane compound having an HLB value of 7 to 15;
and
The value of (H)/(G), which is the weight part ratio of the (H) ketoenol tautomer compound and the (G) crosslinking catalyst, is 1 to 700,
(B) the copolymerizable monomer containing a hydroxyl group 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)acrylamide, at least one selected from the group of compounds,
(C) the copolymerizable monomer containing a carboxyl group is (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, At least one or more selected from the group of compounds consisting of carboxypolycaprolactone mono(meth)acrylate and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid,
The (D) polyalkylene glycol mono(meth)acrylic acid ester monomer has an average repeating number of alkylene oxides constituting the polyalkylene glycol chain of 3 to 14,
The diester content in the (D) polyalkylene glycol mono(meth)acrylic acid ester monomer is 0.3% or less, the water content is 0.1% or less, and the solubility in water is 20% aqueous solution A pressure-sensitive adhesive composition characterized by having a haze value of 2% or less under normal conditions. The (D) polyalkylene glycol mono (meth) acrylic acid ester monomer is selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxy polyalkylene glycol (meth) acrylate, 2. The pressure-sensitive adhesive composition according to claim 1, comprising at least one or more. A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition according to claim 1 or 2, formed on one side or both sides of a resin film. 3. A surface protection film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition according to claim 1 or 2, formed on one side of a resin film. 5. The surface protective film according to claim 4, which is used as a surface protective film for a polarizing plate.