JP2018188648A - Adhesive composition and surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition for forming an adhesive layer of a surface protective film for a polarizing plate which has excellent antistatic performance, is excellent in a balance of adhesive force at a low peeling speed and a high peeling speed, has a long pot life, and is excellent in durability and reworkability, and to provide a surface protective film.SOLUTION: A pentamethylenediisocyanate compound contains (A) an acrylic polymer being a copolymer obtained by copolymerization of (B) 0.1-10 pts.wt. of the total of copolymerizable monomers containing a hydroxyl group, (C) 0.05-1.0 pts.wt. of the total of copolymerizable monomers containing a carboxyl group, and (D) 5-50 pts.wt. of the total of polyalkyleneglycol mono(meth)acrylate monomers based on 100 pts.wt. of the total of a (meth)acrylate monomer having an alkyl group having 4 to 18 carbon atoms, (E) a crosslinking agent and (F) an antistatic agent, where (E) the crosslinking agent is a bi-or higher pentamethylenediisocyanate compound.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition and a surface protective film. More specifically, polarized light that has excellent antistatic performance, has a good balance of adhesive strength at a low peeling speed and a high peeling speed, has a long pot life, and has excellent durability and reworkability. The present invention relates to a pressure-sensitive adhesive composition and a surface protective film for forming a pressure-sensitive adhesive layer of a surface protective film for a plate.

  Conventionally, in a manufacturing process of an optical member such as a polarizing plate and a retardation plate that are members constituting a liquid crystal display, a surface protective film for temporarily protecting the surface of the optical member is attached. Such a surface protective film is used only in the process of manufacturing the optical member, and is peeled off from the optical member when the optical member is incorporated into the liquid crystal display. Since such a surface protective film for protecting the surface of the optical member is used only in the production process, it may be generally called a process film.

In this way, the surface protective film used in the process of manufacturing the optical member has an adhesive layer formed on one side of an optically transparent polyethylene terephthalate (PET) resin film, but is bonded to the optical member. Until then, the release film subjected to the release treatment for protecting the pressure-sensitive adhesive layer is bonded onto 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 capability, hue, contrast, and foreign matter mixing of the liquid crystal display plate in a state where the surface protective film is bonded. As the required performance for the surface protective film, it is required that no bubbles or foreign substances adhere to the pressure-sensitive adhesive layer.
Further, in recent years, when the surface protective film is peeled off from an optical member such as a polarizing plate or a retardation plate, the peeling charge generated due to static electricity generated when the pressure-sensitive adhesive layer is peeled off from the adherend is electrically controlled by the liquid crystal display. There is a concern that it may affect circuit failure, and excellent antistatic performance is required for the pressure-sensitive adhesive layer.
Moreover, when bonding a surface protective film to optical members, such as a polarizing plate and a phase difference plate, for some reason, a surface protective film may be once peeled off and a surface protective film may be bonded again. At that time, it is required that the pressure-sensitive adhesive layer of the surface protective film has an appropriate adhesive force and can be easily peeled off from the optical member of the adherend.
At this time, it is required that the adherend is not contaminated, that is, so-called adhesive residue does not occur.
In addition, when the surface protective film is finally peeled off from an optical member such as a polarizing plate or a retardation plate, it is required to be able to be peeled off quickly. It is required that the adhesive force change little depending on the peeling speed so that it can be quickly peeled even by so-called high-speed peeling.

Thus, in recent years, as required performance for the pressure-sensitive adhesive layer constituting the surface protective film, (1) balancing adhesive force at a low peeling speed and a high peeling speed, (2) excellent Antistatic performance, (3) durability, and (4) reworkability are demanded from the viewpoint of ease of use in using the surface protective film. Here, excellent reworkability means that the adherend is not contaminated after being traced with a ballpoint pen over the surface protective film via the adhesive layer.
However, these (1) to (4), which are required performances for the pressure-sensitive adhesive layer constituting the surface protective film, are required for the pressure-sensitive adhesive layer of the surface protective film even though each of the required performances can be satisfied. It was a very difficult task to satisfy all the required performances (1) to (4) at the same time.

  For example, (1) The following proposals are known for balancing the adhesive force at a low peeling speed and at a high peeling speed and preventing the occurrence of adhesive residue.

An acrylic pressure-sensitive adhesive comprising a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound as a main component and a crosslinking treatment with a crosslinking agent. In the layer, there is a problem that the adhesive is transferred to the adherend side when adhered for a long period of time, and the adhesive strength with respect to the adherend is highly increased 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 was used, and this was crosslinked with a crosslinking agent. What provided the adhesive layer is known (patent document 1).
In addition, the same copolymer as described above is blended with a small amount of a copolymer of a (meth) acrylic acid alkyl ester and a carboxyl group-containing copolymer, and a pressure-sensitive adhesive layer obtained by crosslinking with a crosslinking agent is provided. Etc. have been proposed. However, they can be used for surface protection of plastic plates with a low surface tension and a smooth surface. There was also a problem that the removability at the time of peeling was inferior.

In order to solve these problems, a) 100 parts by weight of (meth) acrylic acid alkyl ester having (meth) acrylic acid alkyl ester having 8 to 10 carbon atoms as a main component, b) containing a carboxyl group A copolymer of a monomer mixture obtained by adding 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; ) A pressure-sensitive adhesive composition in which an equivalent amount or more of a crosslinking agent is blended with respect to the carboxyl group of the component has been proposed (Patent Document 2).
The pressure-sensitive adhesive composition described in Patent Document 2 does not cause a peeling phenomenon such as floating during processing or storage, and has a low adhesive strength with time and is excellent in removability, and is stored for a long time. In particular, even if stored for a long time in a high-temperature atmosphere, it can be re-peeled with a small force, and no adhesive residue is left on the adherend.

As for (2) excellent antistatic performance, a method of kneading an antistatic agent into the base film is shown as a method for imparting antistatic performance to the surface protective film. Examples of the antistatic agent include (a) various cationic antistatic agents having a cationic group such as a quaternary ammonium salt, a pyridinium salt, and a primary to tertiary amino group, and (b) a sulfonate group, sulfuric acid. Anionic antistatic agents having anionic groups such as ester bases, phosphate ester bases, phosphonate bases, (c) amphoteric antistatic agents such as amino acid-based and aminosulfuric acid ester-based, (d) amino alcohol-based, glycerin-based And nonionic antistatic agents such as polyethylene glycol, and (e) a polymeric antistatic agent obtained by increasing the molecular weight of the antistatic agent as described above (Patent Document 3).
Further, in recent years, it has been proposed that such an antistatic agent is contained in the base film or directly in the pressure-sensitive adhesive layer rather than being applied to the surface of the base film.

  As for (3) durability, in recent years, there has been a demand for improving the so-called durability that the pressure-sensitive adhesive layer does not have a significant increase in adhesive strength at high temperatures and high humidity. Furthermore, in recent years, a crosslinking catalyst is used to increase the crosslinking rate in the step of forming a pressure-sensitive adhesive layer by crosslinking the pressure-sensitive adhesive composition. Along with that, the pot life (potential time) is shortened, and the pressure-sensitive adhesive composition that has passed the specified pot life is disposed of, which causes a new problem of increasing economic loss. For this reason, in order to reduce manufacturing cost, it is calculated | required to set it as the adhesive composition with a long pot life.

As for (4) reworkability, for example, an adhesive in which an acrylic compound curing agent and a specific silicate oligomer are mixed 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 alkyl acrylate having an alkyl group having about 2 to 12 carbon atoms, an alkyl methacrylate having an alkyl group having about 4 to 12 carbon atoms, and the like as a main monomer component, for example, a carboxyl group-containing monomer, etc. Other functional group-containing monomer components can be included. In general, the main monomer is preferably contained in an amount of 50% by weight or more, 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 is said that it is desired to be 0.01 to 25% by weight. Such a pressure-sensitive adhesive composition described in Patent Document 4 has little change over time in cohesive force and adhesive force even at high temperature or high temperature and high humidity, and exhibits an excellent effect on adhesive force to a curved surface. It has reworkability.
In general, when the pressure-sensitive adhesive layer has a soft property, adhesive residue is likely to be generated, and reworkability is likely to be reduced. That is, it is difficult to peel off when pasted by mistake, and it is difficult to re-paste. From this, it is considered necessary to make the pressure-sensitive adhesive layer have a certain hardness by crosslinking a monomer having a functional group such as a carboxyl group to the main agent in order to have reworkability.

JP-A-63-225677 JP-A-11-256111 Japanese Patent Laid-Open No. 11-070629 JP-A-8-199130

Currently, TAC films (triacetyl cellulose compounds), acrylic films, and the like are used as protective films for polarizing plates used in liquid crystal displays and the like.
The present invention relates to a pressure-sensitive adhesive composition and a surface protective film for forming a pressure-sensitive adhesive layer of a surface protective film for a polarizing plate using these protective films.
In the prior art, the required performance for the pressure-sensitive adhesive layer constituting the surface protective film is to balance the adhesive force at a low peeling speed and at a high peeling speed, excellent antistatic performance, durability, and rework. Although properties and the like have been demanded, it has not been possible to satisfy all the required performances required for the pressure-sensitive adhesive layer of the surface protective film, even though each required performance can be satisfied.

  The present invention has been made in view of the above circumstances, has an excellent antistatic performance, has a low peel rate, and a high peel rate, has a good balance of adhesive strength, and has a long pot life, It is an object of the present invention to provide a pressure-sensitive adhesive composition and a surface protective film for forming a pressure-sensitive adhesive layer of a surface protective film for polarizing plates, which are excellent in durability and reworkability.

  In order to solve the above-mentioned problems, the present invention provides a pressure-sensitive adhesive composition containing an acrylic polymer, (E) a crosslinking agent, and (F) an antistatic agent, wherein the acrylic polymer is (A) At least one or more (meth) acrylic acid ester monomers having 4 to 18 carbon atoms in the alkyl group, (B) at least one copolymerizable monomer containing a hydroxyl group, and (C) a carboxyl group A copolymer obtained by copolymerizing at least one kind of copolymerizable monomer and at least one kind of (D) polyalkylene glycol mono (meth) acrylic acid ester monomer. Is a bifunctional or higher functional pentamethylene diisocyanate compound, and the antistatic agent (F) is a solid ionic compound at a temperature of 25 to 50 ° C. and a melting point of 25 to 50 ° C. Providing a pressure-sensitive adhesive composition characterized.

  The acrylic polymer contains (B) a hydroxyl group with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms. The total of at least one kind of polymerizable monomers is 0.1 to 10 parts by weight, and the total of at least one kind of copolymerizable monomers containing the (C) carboxyl group is 0.05 to 1.0. 5 to 50 parts by weight of the total of at least one kind of the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer, and (G) a nitrogen-containing vinyl monomer or alkoxy group containing no hydroxyl group. This is a copolymer obtained by copolymerizing 0.1 to 20 parts by weight of a total of at least one of the containing alkyl (meth) acrylate monomers. It is preferred. The (E) cross-linking agent is a bifunctional or higher pentamer with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. 0.1 to 10 parts by weight of a methylene diisocyanate compound, 0.001 to 0.5 parts by weight of (H) a crosslinking catalyst, and (I) 0.1 to 300 parts by weight of a ketoenol tautomer compound It is preferable to contain.

  The (F) antistatic agent is contained in the pressure-sensitive adhesive composition with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. A total of 0.01 to 5.0 parts by weight of an ionic compound that is solid at 25 ° C. and a acryloyl group-containing ionic compound copolymerized in the copolymer. It is preferable to contain. The (D) polyalkylene glycol mono (meth) acrylate monomer is selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate. Moreover, it is preferable that the average number of alkylene oxides constituting the polyalkylene glycol chain is 3 to 14 and the absorbance in a 25% aqueous solution state is 0.04 or less.

  The (E) crosslinking agent is a trifunctional pentamethylene diisocyanate compound, and one or more pentamethylene diisocyanates comprising 1,5-pentamethylene diisocyanate, 1,4-pentamethylene diisocyanate, and 1,3-pentamethylene diisocyanate The compound is preferably at least one selected from isocyanurate, adduct, and burette.

  The (H) crosslinking catalyst is preferably a metal chelate compound. The weight ratio (I) / (H) of the (H) crosslinking catalyst to the (I) ketoenol tautomer compound is preferably 70 to 1000.

  The copolymerizable monomer containing the (B) 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, and at least one selected from the group of compounds consisting of N-hydroxyethyl (meth) acrylamide are preferable.

  The copolymerizable monomer containing the (C) carboxyl group is (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, It is preferably at least one selected from the group of compounds consisting of carboxypolycaprolactone mono (meth) acrylate and 2- (meth) acryloyloxyethyltetrahydrophthalic acid.

  Furthermore, 0.01-1 part by weight of the polyether-modified siloxane compound is added to 100 parts by weight in total of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. It is preferable to include.

  The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition has a gel fraction of 95 to 100%, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer at a low peeling rate of 0.3 m / min is 0.04 to It is preferably 0.2 N / 25 mm, and the adhesive strength at a high peeling speed of 30 m / min is preferably 2.0 N / 25 mm or less.

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

  Moreover, this invention provides the adhesive film formed by forming the adhesive layer formed by bridge | crosslinking the said adhesive composition on the single side | surface or both surfaces of a resin film.

  Moreover, this invention provides the surface protection film which consists of the said adhesive film and is used as a use of the surface protection film for polarizing plates.

  It is preferable that an antistatic treatment and an antifouling treatment are performed on the surface of one side of the resin film opposite to the side on which the pressure-sensitive adhesive layer is formed.

  According to the present invention, with excellent antistatic performance, at a low peeling speed, and at a high peeling speed, the balance of adhesive strength is excellent, and further, the pot life is long, and durability and reworkability are excellent. The adhesive composition and surface protection film for forming the adhesive layer of the surface protection film for polarizing plates can be provided.

Hereinafter, the present invention will be described based on preferred embodiments.
The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing an acrylic polymer, (E) a crosslinking agent, and (F) an antistatic agent, wherein the acrylic polymer is (A) an alkyl group. At least one (meth) acrylic acid ester monomer having C4 to C18 carbon atoms, (B) at least one copolymerizable monomer containing a hydroxyl group, and (C) a copolymer containing a carboxyl group. It is a copolymer obtained by copolymerizing at least one or more polymerizable monomers and (D) at least one polyalkylene glycol mono (meth) acrylate monomer, and (E) the cross-linking agent is It is a pentamethylene diisocyanate compound having two or more functions, and the antistatic agent (F) is a solid ionic compound at a temperature of 25 ° C. and a melting point of 25 to 50 ° C. That is a pressure-sensitive adhesive composition.

  The acrylic polymer contains (B) a hydroxyl group with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms. The total of at least one kind of polymerizable monomers is 0.1 to 10 parts by weight, and the total of at least one kind of copolymerizable monomers containing the (C) carboxyl group is 0.05 to 1.0. 5 to 50 parts by weight of the total of at least one kind of the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer, and (G) a nitrogen-containing vinyl monomer or alkoxy group containing no hydroxyl group. This is a copolymer obtained by copolymerizing 0.1 to 20 parts by weight of a total of at least one of the containing alkyl (meth) acrylate monomers. It is preferred. The (E) cross-linking agent is a bifunctional or higher pentamer with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. 0.1 to 10 parts by weight of a methylene diisocyanate compound, 0.001 to 0.5 parts by weight of (H) a crosslinking catalyst, and (I) 0.1 to 300 parts by weight of a ketoenol tautomer compound It is preferable to contain.

(A) As a (meth) acrylic acid ester monomer having a C4-C18 alkyl group, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) ) Acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (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, myristyl (meth) acrylate, isomyristyl (meth) acrylate, cetyl (meth) acrylate, isocetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, etc. It is done.
The total of the acrylic polymer is in a ratio of 105 to 200 parts by weight with respect to a total of 100 parts by weight of the (A) alkyl group having at least one kind of (meth) acrylic acid ester monomer having C4 to C18 carbon atoms. The ratio is preferably 110 to 170 parts by weight, more preferably 110 to 140 parts by weight.

(B) As a copolymerizable monomer containing a hydroxyl group, 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate And hydroxyalkyl (meth) acrylates such as N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and hydroxyl-containing (meth) acrylamides such as 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 (meta It is preferably at least one selected from the group of compounds consisting of acrylamide and N-hydroxyethyl (meth) acrylamide.
(B) at least one copolymerizable monomer containing a hydroxyl group with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having a C4-C18 carbon number in the alkyl group (A). It is preferable to contain the total of the seeds in a proportion of 0.1 to 10 parts by weight, more preferably 2 to 8 parts by weight, and particularly preferably 2 to 6 parts by weight. .

(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) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxy It is preferably at least one selected from the group consisting of polycaprolactone mono (meth) acrylate and 2- (meth) acryloyloxyethyl tetrahydrophthalic acid.
(C) at least one of the copolymerizable monomers containing a carboxyl group with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having an alkyl group with C4 to C18 carbon atoms. It is preferable to contain 1 or more types of total in the ratio of 0.05-1.0 weight part, It is more preferable to contain in the ratio of 0.05-0.8 weight part, 0.05-0.5 It is particularly preferable to contain it in a proportion by weight.

(D) The polyalkylene glycol mono (meth) acrylate monomer may be a compound in which one hydroxyl group is esterified as a (meth) acrylate ester among a plurality of hydroxyl groups of the polyalkylene glycol. Since the (meth) acrylic acid ester group becomes a polymerizable group, it can be copolymerized with the main polymer. The other hydroxyl group may be OH or may be an alkyl ether such as methyl ether or ethyl ether, or a saturated carboxylic acid ester such as acetate.
Examples of the alkylene group of the polyalkylene glycol include, but are not limited to, an ethylene group, a propylene group, and a butylene group. The polyalkylene glycol may be a copolymer of two or more polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Examples of the polyalkylene glycol copolymer include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol, and the copolymer includes: It may be a block copolymer or a random copolymer.

  (D) It is preferable that the average repeating number of the alkylene oxide which comprises a polyalkylene glycol chain is 3-14 in the polyalkylene glycol mono (meth) acrylic acid ester monomer. The “average number of repeating alkylene oxides” is the average number of repeating alkylene oxide units in the “polyalkylene glycol chain” part of the molecular structure of the (D) polyalkylene glycol mono (meth) acrylate monomer. is there.

(D) The polyalkylene glycol mono (meth) acrylic acid ester monomer preferably has an absorbance in a 25% aqueous solution state of 0.04 or less. Moreover, it is preferable that the diester content in a monomer is 0.3% or less.
“Diester content in monomer” is the content (% by weight) of polyalkylene glycol di (meth) acrylate contained in (D) polyalkylene glycol mono (meth) acrylate monomer.
The “absorbance in a 25% aqueous solution state” is the absorbance of the aqueous solution in a state where (D) polyalkylene glycol mono (meth) acrylate monomer is a 25% by weight aqueous solution. That is, the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer not only has water solubility (solubility in water) that makes it a 25% aqueous solution, but also has low absorbance (less white turbidity) in the 25% aqueous solution. ) Need that.
In the present specification, the absorbance of a 25% aqueous solution is a value measured by putting the aqueous solution in a quartz cell having an optical path length of 10 mm. This index was introduced to select a highly hydrophilic monomer that can provide a solution free of cloudiness even at high concentrations, as the degree of hydrophilicity of the (D) polyalkylene glycol mono (meth) acrylate monomer. It is.

(D) As polyalkylene glycol mono (meth) acrylate monomer, selected from polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (meth) acrylate, ethoxy polyalkylene glycol (meth) acrylate, It is preferable that it is at least one or more.
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-polyethylene glycol-polypropylene glycol-polybutylene glycol -(Meth) acrylate; ethoxy polyethylene glycol- (meth) acrylate, ethoxy polypropylene glycol- (meth) acrylate, ethoxypolybutylene glycol- (meth) 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 - such as (meth) acrylate.
The (A) polyalkylene glycol mono (meth) acrylate monomer is (D) based on a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having a C4-C18 carbon number in the alkyl group. The total of at least one kind is preferably contained in a proportion of 5 to 50 parts by weight, more preferably contained in a proportion of 5 to 40 parts by weight, and particularly preferably contained in a proportion of 5 to 30 parts by weight. .

  In addition to the essential components (A) to (D), the acrylic polymer contains, as an optional component, (G) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or an alkoxy group-containing alkyl (meth) acrylate monomer. Can be included. Among (G), examples of the (G1) nitrogen-containing vinyl monomer include a vinyl monomer containing an amide bond, a vinyl monomer containing an amino group, and a vinyl monomer having a nitrogen-containing heterocyclic structure. More specifically, N-vinyl-2-pyrrolidone, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrazine, 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-vinyllaurylactam; N- ( (Meth) acryloylmorpholine, N- (meth) acryloylpiperazine, N- (meth) acryloylaziridine, N- (meth) acryloylazetidine, N- (meth) acryloylpyrrolidine, N- (meth) acryloylpiperidine, N- (meth) ) Acryloyl azepan, N- (meth) a Cyclic nitrogen vinyl compounds having an N- (meth) acryloyl-substituted heterocyclic structure such as liloyl azocan; heterocyclic rings having nitrogen atoms and ethylenically unsaturated bonds in the ring, such as N-cyclohexylmaleimide and N-phenylmaleimide Cyclic nitrogen vinyl compounds having the formula structure: (meth) acrylamide, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-butyl (meth) acrylamide, etc. ) Acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropylacrylamide, N, N-diisopropyl (meth) acrylamide, N, N-dibutyl (meth) acrylamide N-ethyl-N-methyl (meth) acrylate Dialkyl-substituted (meth) acrylamides such as luamide, N-methyl-N-propyl (meth) acrylamide, N-methyl-N-isopropyl (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 (me ) Dialkylamino (meth) acrylates such as acrylate, 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 and N-methyl-N-isopropylaminopropyl (meth) acrylamide; N-vinylformamide, N-vinylacetate N-vinylcarboxylic acid amides such as N-vinyl-N-methylacetamide; N-methoxymethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide (Meth) acrylamides such as N, N-methylenebis (meth) acrylamide; Unsaturated carboxylic acid nitriles such as (meth) acrylonitrile;

  (G1) The nitrogen-containing vinyl monomer preferably does not contain a hydroxyl group, and more preferably does not contain a hydroxyl group or a carboxyl group. Examples of such monomers include the monomers exemplified above, for example, acrylic monomers containing N, N-dialkyl-substituted amino groups or 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 (G), (G2) 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-isopropoxypropyl ( (Meth) acrylate, 2-butoxypropyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 3-propoxypropyl (meth) acrylate, 3-isopropoxypropyl ( ) Acrylate, 3-butoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, 4-propoxybutyl (meth) acrylate, 4-isopropoxybutyl (meth) acrylate, Examples include 4-butoxybutyl (meth) acrylate.
These alkoxy group-containing alkyl (meth) acrylate monomers have a structure in which an atom of the alkyl group in the alkyl (meth) acrylate is substituted with an alkoxy group.

  (G) A nitrogen-containing vinyl monomer or an alkoxy group containing no hydroxyl group (G) with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having a C4 to C18 carbon number in the alkyl group. It is preferable to contain at least one alkyl (meth) acrylate monomer in a proportion of 0.1 to 20 parts by weight, more preferably in a proportion of 0.3 to 10 parts by weight, and 0.3 to 8 parts by weight. It is particularly preferable to contain it in a proportion of parts. (G1) A nitrogen-containing vinyl monomer not containing a hydroxyl group and (G2) an alkoxy group-containing alkyl (meth) acrylate monomer may be used alone or in combination of two or more.

It is preferable to use a bifunctional or higher pentamethylene diisocyanate compound as the acrylic polymer (E) crosslinking agent. (E) The crosslinking agent is preferably a bifunctional pentamethylene diisocyanate compound (a compound having two NCO groups in one molecule) or a trifunctional or higher functional pentamethylene diisocyanate compound. In the present invention, in particular, (E) the cross-linking agent is a trifunctional pentamethylene diisocyanate compound, which is a kind of 1,5-pentamethylene diisocyanate, 1,4-pentamethylene diisocyanate, 1,3-pentamethylene diisocyanate. The above pentamethylene diisocyanate compound is preferably at least one selected from an isocyanurate body, an adduct body, and a burette body. Among them, examples of adducts include adducts (polyol-modified products) with trivalent or higher polyols (compounds having at least three OH groups in one molecule) such as trimethylolpropane (TMP) and glycerin. .
The (A) cross-linking agent is a bifunctional or higher pentamethylene diisocyanate compound with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. (Or at least one selected from the isocyanurate bodies, adduct bodies, and burette bodies) is preferably contained in a proportion of 0.1 to 10 parts by weight.

(H) The crosslinking catalyst may be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent when a polyisocyanate compound is used as a crosslinking agent, such as a tertiary amine. And organic metal compounds such as amine compounds, metal chelate compounds, organic tin compounds, organic lead compounds, and organic zinc compounds.
Examples of the tertiary amine include trialkylamine, N, N, N ′, N′-tetraalkyldiamine, N, N-dialkylamino alcohol, triethylenediamine, morpholine derivative, piperazine derivative and the like.

The metal chelate compound is a compound in which one or more multidentate ligands L are bonded to the central metal atom M. The metal chelate compound may or may not have one or more monodentate ligands X bonded 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, the m Ls may be the same ligand or different ligands. When n is 2 or more, the n Xs may be the same ligand or different ligands.

Examples of the metal atom M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, and Sn.
As the polydentate ligand L, β-ketoester such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, acetylacetone (also known as 2,4-pentanedione), Examples include β-diketones such as 2,4-hexanedione and benzoylacetone. These are ketoenol tautomeric compounds, and the polydentate ligand L may be an enolate (for example, acetylacetonate) in which enol is deprotonated.
As monodentate ligand X, acyloxy such as halogen atom such as chlorine atom and bromine atom, pentanoyl group, hexanoyl group, 2-ethylhexanoyl group, octanoyl group, nonanoyl group, decanoyl group, dodecanoyl group and octadecanoyl group Group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, alkoxy group such as butoxy group, and the like.

  Specific examples of the metal chelate compound include tris (2,4-pentanedionato) 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-Hexanedionato) aluminum, tetrakis (2,4-hexanedionato) zirconium and the like can be mentioned.

Examples of the organic tin compound include dialkyl tin oxide, fatty acid salt of dialkyl tin, fatty acid salt of stannous and the like.
(H) The crosslinking catalyst is preferably a metal chelate compound or an organic tin compound. As the metal chelate compound, an aluminum chelate compound, a titanium chelate compound, an iron chelate compound, a tin chelate compound and the like are preferable. The organic tin compound is preferably at least one selected from the group consisting of dioctyltin oxide and dioctyltin dilaurate.
0.001 to 0.5 parts by weight of (H) the crosslinking catalyst with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. It is preferable to contain in the ratio.

(I) Ketoenol tautomeric compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, acetylacetone, 2,4-hexanedione And β-diketones such as benzoylacetone. (I) The ketoenol tautomer compound is an excess of the pressure-sensitive adhesive composition after blending of the crosslinking agent by blocking the isocyanate group of the crosslinking agent in the pressure-sensitive adhesive composition using the polyisocyanate compound as a crosslinking agent. An increase in viscosity and gelation can be suppressed, and the pot life of the pressure-sensitive adhesive composition can be extended.
(I) The keto enol tautomer compound is preferably at least one selected from the group consisting of acetylacetone and ethyl acetoacetate.
The (A) ketoenol tautomer compound is added in an amount of 0.1 to 300 with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having an alkyl group with a carbon number of C4 to C18. It is preferable to contain in the ratio of a weight part, and the ratio of 1.0-30.0 weight part is more preferable.

  The (I) ketoenol tautomer compound has an effect of suppressing crosslinking, as opposed to the (H) crosslinking catalyst, so that the ratio of (I) ketoenol tautomer compound to the (H) crosslinking catalyst is appropriately set. It is preferable to set to. In order to lengthen the pot life of the pressure-sensitive adhesive composition and improve the storage stability, the weight ratio (I) / (H) of the (H) crosslinking catalyst to the ketoenol tautomer compound is 70 to 1000. It is preferable that

(F) The antistatic agent is preferably (F1) an ionic compound having a melting point of 25 to 50 ° C. and / or (F2) an acryloyl group-containing ionic compound.
In the present invention, (F) as an antistatic agent, (F1) an ionic compound having a melting point of 25 to 50 ° C. is added to the copolymer, and / or (F2) an acryloyl group-containing ionic compound is copolymerized. Copolymerizes inside. Since these (F) antistatic agents have a low melting point and have a long-chain alkyl group, it is presumed that they have a high affinity with an acrylic copolymer.

  (F) As an antistatic agent, the antistatic agent contained in an adhesive composition and the antistatic agent copolymerized in the said copolymer are mentioned. (F) Antistatic agent is contained in the pressure-sensitive adhesive composition with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. (F1) 0.01 to 5.0 parts by weight of the total of the ionic compound having a melting point of 25 to 50 ° C. and the (F2) acryloyl group-containing ionic compound copolymerized in the copolymer It is preferable that it is contained in proportion.

(F1) An ionic compound having a melting point of 25 to 50 ° C. is an ionic compound having a cation and an anion, and the cation is pyridinium cation, imidazolium cation, pyrimidinium cation, pyrazolium cation, pyrrole Nitrogen-containing onium cations such as dinium cation and ammonium cation, phosphonium cation, sulfonium cation and the like, and the anion is hexafluorophosphate (PF ₆ ⁻ ), thiocyanate (SCN ⁻ ), alkylbenzene sulfonate (RC ₆ H ₄ SO ₃ ⁻ ), perchlorate (ClO ₄ ⁻ ), tetrafluoroborate (BF ₄ ⁻ ), bis (fluorosulfonyl) imide salt (FSI), bis (trifluoromethanesulfonyl) imide Salt (TFSI), trifluoromethanesulfonate (TF) Inorganic or compound which is an organic anion and the like. (F1) The ionic compound having a melting point of 25 to 50 ° C. is preferably solid at room temperature (for example, 25 ° C.), and the melting point is 25 depending on the selection of the chain length of the alkyl group, the position and number of substituents, and the like. A product of ˜50 ° C. can be obtained. The cation is preferably a quaternary nitrogen-containing onium cation, and a quaternary pyridinium cation such as 1-alkylpyridinium (the carbon atom at the 2-6 position may be substituted or unsubstituted), or 1, Quaternary imidazolium cations such as 3-dialkylimidazolium (the carbon atoms at 2, 4, and 5 positions may be substituted or unsubstituted), quaternary ammonium cations such as tetraalkylammonium, and the like. .
(F1) The ionic compound having a melting point of 25 to 50 ° C. is based on a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. , Preferably in a proportion of 0.01 to 5.0 parts by weight.

(F2) The acryloyl group-containing ionic compound is an ionic compound having a cation and an anion, and the cation is (meth) acryloyloxyalkyltrialkylammonium [R ₃ N ⁺ —C _n H _2n —OCOCQ═CH ₂ , where Q = H or CH ₃ , R = alkyl] and the like (meth) acryloyl group-containing cation, and the anion is hexafluorophosphate (PF ₆ ⁻ ), thiocyanate (SCN ⁻ ), Inorganic or organic anions such as organic sulfonate (RSO ₃ ⁻ ), perchlorate (ClO ₄ ⁻ ), tetrafluoroborate (BF ₄ ⁻ ), and F-containing imide salt (R ^F ₂ N ⁻ ) There are certain compounds. F-containing imide salt (R F ² _N ^-) as the R ^F of, trifluoromethanesulfonyl group, and perfluoro alkane sulfonyl group or fluorosulfonyl group, such as pentafluoroethane sulfonyl group. Examples of the F-containing imide salt include bis (fluorosulfonyl) imide salt [(FSO ₂ ) ₂ N ⁻ ], bis (trifluoromethanesulfonyl) imide salt [(CF ₃ SO ₂ ) ₂ N ⁻ ], and bis (pentafluoroethanesulfonyl). ) Bissulfonylimide salts such as imide salts [(C ₂ F ₅ SO ₂ ) ₂ N ⁻ ].
(F2) The acryloyl group-containing ionic compound is 0.01 to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) alkyl group having C4 to C18 carbon atoms. It is preferable to be copolymerized in the copolymer in a proportion of 5.0 parts by weight.

(F) Specific examples of the antistatic agent are not particularly limited. (F1) Specific examples of the ionic compound having a melting point of 25 to 50 ° C. include 1-octylpyridinium hexafluorophosphate. 1-nonylpyridinium hexafluorophosphate, 2-methyl-1-dodecylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecyl Examples thereof include benzene sulfonate and 4-methyl-1-octylpyridinium hexafluorophosphate. Specific examples of the (F2) acryloyl group-containing ionic compound include dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ · PF ₆ ⁻ , However, 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 according to the present invention can optionally contain (J) a polyether-modified siloxane compound. (J) The polyether-modified siloxane compound is a siloxane compound having a polyether group, and in addition to a normal siloxane unit [—SiR ¹ ₂ —O—], a siloxane unit having a polyether group [—SiR ¹ (R having _{^{2 O (R 3 O) n}} R 4) -O- ]. Here, R ¹ is one or more alkyl groups or aryl groups, R ² and R ³ are one or more alkylene groups, and R ⁴ is one or more alkyl groups or acyl groups. Etc. (terminal group). Examples of the polyether group include 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 to 14. The polyether-modified siloxane compound having an HLB value of 7 to 14 with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (C) C4 to C18 carbon atoms in the alkyl group. It is preferable that 0.01-1 weight part is contained. More preferably, it is 0.1-0.5 weight part. HLB is a hydrophilic / lipophilic balance (hydrophilic / lipophilic ratio) defined in, for example, JIS K3211 (surfactant term).

(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 by a hydrosilylation reaction. it can. Specifically, dimethylsiloxane-methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane-methyl (polyoxyethylene) siloxane-methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane-methyl (polyoxypropylene) Examples thereof include siloxane polymers. The HLB value of the polyether-modified siloxane compound can be adjusted by selecting the ratio between the polyether group and the siloxane group.
By adding a polyether-modified siloxane compound having an HLB value of 7 to 14 to the pressure-sensitive adhesive composition, the pressure-sensitive adhesive strength and rework performance of the pressure-sensitive adhesive can be improved. When the pressure-sensitive adhesive composition does not contain a polyether-modified siloxane compound, the cost becomes lower.
However, in the present invention, by adding a predetermined amount of (D) polyalkylene glycol mono (meth) acrylic acid ester monomer to the pressure-sensitive adhesive, the hydrophilicity can be obtained without including a siloxane compound such as a polyether-modified siloxane compound. In order to improve, the adhesive layer excellent in antistatic property can be formed.

  In addition, copolymerizable (meth) acrylic monomers, (meth) acrylamide monomers, dialkyl-substituted acrylamide monomers, surfactants, curing accelerators, plasticizers, fillers, curing retarders containing alkylene oxide as other components In addition, known additives such as processing aids, anti-aging agents, and antioxidants can be appropriately blended. These may be 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 is copolymerizable with (A) a (meth) acrylic acid ester monomer having an alkyl group having C4 to C18 and (B) a hydroxyl group. A monomer, (C) a copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono (meth) acrylate monomer, and an optional component (G) a nitrogen-containing vinyl monomer or alkoxy containing no hydroxyl group It can be synthesized by polymerizing a group-containing alkyl (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. The optional monomer (G) can be omitted.
(F) When (F2) acryloyl group-containing ionic compound is used as the antistatic agent, the copolymer of the main agent used in the pressure-sensitive adhesive composition of the present invention is (A) an alkyl group having C4 to C18 carbon atoms. (Meth) acrylic acid ester monomer, (B) copolymerizable monomer containing hydroxyl group, (C) copolymerizable monomer containing carboxyl group, and (D) polyalkylene glycol mono (meth) acrylic acid It is possible to synthesize by polymerizing an ester monomer, an optional component (G) a nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth) acrylate monomer that does not contain a hydroxyl group, and (F2) an acryloyl group-containing ionic compound. it can. The optional monomer (G) can be omitted.
The pressure-sensitive adhesive composition of the present invention further comprises (E) a cross-linking agent, (H) a cross-linking catalyst, (I) a ketoenol tautomer compound, and an optional additive as appropriate. Can be prepared. When (F2) an acryloyl group-containing ionic compound is polymerized in the main copolymer, (F1) an ionic compound having a melting point of 25 to 50 ° C. is further added to the copolymer. It does not matter whether or not it is added.

At the time of producing the copolymer of the main agent, 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 mixing of moisture into the pressure-sensitive adhesive composition. In particular, since the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer has high hydrophilicity, it is preferable to use a monomer having a low water content.
Each monomer used in the production of the copolymer of the main agent should be the amount of multifunctional (bifunctional or higher) monomer that can function as a crosslinking agent as much as possible in order to avoid an increase in viscosity of the pressure-sensitive adhesive composition. It is preferable to reduce. In particular, since the (D) polyalkylene glycol mono (meth) acrylate monomer is a di (meth) acrylate ester of a bifunctional monomer corresponding to the diester, it is preferable to use a monomer having a small amount of diester.

The copolymer is preferably an acrylic polymer, and an acrylic monomer such as a (meth) acrylic acid ester monomer, (meth) acrylic acid, or (meth) acrylamide is added to 100 parts by weight of the acrylic polymer. On the other hand, it is preferable to contain in the ratio of 50-100 weight part.
Moreover, it is preferable that the acid value of an acrylic polymer is 0.01-8.0. As a result, the contamination property can be improved and the performance of preventing the occurrence of adhesive residue can be improved.
Here, the “acid value” is one of indices indicating 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 crosslinking the pressure-sensitive adhesive composition has a pressure-sensitive adhesive strength at a low peeling speed of 0.3 m / min of 0.04 to 0.2 N / 25 mm and a high speed peeling speed of 30 m / min. The adhesive strength is preferably 2.0 N / 25 mm or less. Thereby, the performance with little change in the adhesive force depending on the peeling speed can be obtained, and it is possible to peel quickly even by high speed peeling. In addition, when the surface protective film is once peeled off for re-sticking, excessive force is not required and it is easy to peel off from the adherend.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition preferably has a surface resistivity of 9.0 × 10 ⁺¹¹ Ω / □ or less and a peeling 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. When the surface resistivity is large, the performance of releasing static electricity generated by electrification at the time of peeling is inferior. For this reason, by making the surface resistivity sufficiently small, the stripping voltage generated due to static electricity generated when the adherend peels off the adhesive layer is reduced, and the electrical control circuit of the adherend is affected. Can be suppressed.

  It is preferable that the gel fraction of the pressure-sensitive adhesive layer after crosslinking the pressure-sensitive adhesive composition of the present invention is 95 to 100%. Because of the high gel fraction, the adhesive force does not become excessive at a low peeling speed, and the elution of unpolymerized monomers or oligomers from the copolymer is reduced, resulting in reworkability and high temperature / high humidity. Durability is improved and contamination of the adherend can be suppressed.

  The pressure-sensitive adhesive film of the present invention is formed by forming a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present invention on one side or both sides of a resin film. Moreover, the surface protective film of this invention is a surface protective film formed by forming the adhesive layer formed by bridge | crosslinking the adhesive composition of this invention on the single side | surface of a resin film. In the pressure-sensitive adhesive composition of the present invention, since the components (A) to (I) are blended in a balanced manner, it has excellent antistatic performance, and at a low peeling speed and a high peeling speed, Excellent balance of adhesive strength, and excellent durability and reworkability (no adherence of contamination to the adherend after tracing the surface protective film with a ballpoint pen through the adhesive layer) Become. For this reason, it can be used conveniently as a use of the adhesive layer of the surface protective film for polarizing plates.

As the base film of the pressure-sensitive adhesive film of the present invention and the base film of a release film (separator) that protects the pressure-sensitive adhesive layer, a resin film such as a polyester film can be used.
The base film of the pressure-sensitive adhesive film of the present invention has an antifouling effect due to a silicone-based, fluorine-based release agent or coating agent, silica fine particles, etc. on the side opposite to the side where the pressure-sensitive adhesive layer is formed on one side of the resin film. An antistatic treatment such as treatment, application of an antistatic agent or kneading can be performed.
Further, the release film is subjected to a release treatment with a silicone-based or fluorine-based release agent or the like on the surface of the pressure-sensitive adhesive layer that is to be combined with the pressure-sensitive adhesive surface.

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

<Manufacture 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, and the air in the reactor was replaced with nitrogen gas. Thereafter, 100 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 8-hydroxyoctyl acrylate, 0.2 parts by weight of acrylic acid, polypropylene glycol monoacrylate (average number of repeating alkylene oxides constituting the polyalkylene glycol chain) in the reactor 60 parts by weight of a solvent (ethyl acetate) was added together with 10 parts by weight of an n = 12, 25% aqueous solution at 0.03) and 5 parts by weight of N-vinylpyrrolidone. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was dropped over 2 hours and reacted at 65 ° C. for 6 hours, and the acrylic copolymer solution used in Example 1 having a weight average molecular weight of 500,000 was used. Got. A part of the acrylic copolymer was collected and used as a sample for measuring the acid value described later.
[Examples 2 to 6 and Comparative Examples 1 to 4]
The monomer composition is the same as that of the acrylic copolymer solution used in Example 1 except that the composition of each monomer is as described in (A) to (D), (G) and (F2) of Table 1. Thus, acrylic copolymer solutions used in Examples 2 to 6 and Comparative Examples 1 to 4 were obtained.

<Production of pressure-sensitive adhesive composition and surface protective film>
[Example 1]
To the acrylic copolymer solution of Example 1 produced as described above, 1.0 part by weight of 1-octylpyridinium hexafluorophosphate and 8.5 parts by weight of acetylacetone were added and stirred, and then the pentamethylene diisocyanate compound. The pressure-sensitive adhesive composition of Example 1 was obtained by adding 0.5 parts by weight of the isocyanurate body and 0.1 parts by weight of titanium trisacetylacetonate and stirring and mixing. 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 adhesive layer has a thickness of 25 μm A sheet was obtained.
Then, the adhesive sheet was transferred to the opposite side of the antistatic and antifouling surface of the polyethylene terephthalate (PET) film that had been antistatic and antifouling treated on one side. 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 6 and Comparative Examples 1 to 4]
The composition of the additive is the same as that of the surface protective film of Example 1 except that the compositions of (E), (H), (I), (F2), and (J) in Table 2 are used. Thus, surface protective films of Examples 2 to 6 and Comparative Examples 1 to 4 were obtained.

In Table 1 and Table 2, the compounding ratio of each component is shown by enclosing the numerical value of parts by weight in parentheses, with the total of group (A) as 100 parts by weight. (F) Among the antistatic agents, the (F2) acryloyl group-containing ionic compound copolymerized in the copolymer is described in the column of Table 1, but is added after polymerization. (F1) Melting point is 25 The ionic compounds that are solid at a temperature of -50 ° C at 25 ° C are listed in another column of Table 2.
In addition, Table 3 and Table 4 show the names of the abbreviations of the components used in Tables 1 and 2. Coronate (registered trademark) HX (an isocyanurate of hexamethylene diisocyanate compound (HDI)) is a trade name of Nippon Polyurethane Industry Co., Ltd. Regarding the group (D) in Table 3, the numerical value “n” is the average number of repeating alkylene oxides constituting the polyalkylene glycol chain. The value of “diester” is the diester content (%) in the monomer. The numerical value of “absorbance” is the absorbance in a 25% aqueous solution state. Moreover, the value of “(I) / (H)” in Table 2 indicates a weight ratio.

<Test method and evaluation>
The surface protective films in Examples 1 to 6 and Comparative Examples 1 to 4 were aged in an atmosphere of 23 ° C. and 50% RH for 7 days, and then the release film (PET film coated with a silicone resin) was peeled off to give an adhesive. What exposed the layer was used as a measurement sample of the gel fraction and surface resistivity of the pressure-sensitive adhesive layer.
Further, the surface protective film on which the pressure-sensitive adhesive layer was exposed was bonded to the surface of the polarizing plate attached to the liquid crystal cell via the pressure-sensitive adhesive layer, and allowed to stand for 1 day, then at 50 ° C., 5 atm, 20 Samples that were autoclaved for minutes and allowed to stand at room temperature for an additional 12 hours were used as measurement samples for the adhesive strength, peeling voltage, reworkability, and durability of the adhesive layer.

<Gel fraction of adhesive layer>
After the aging is completed, the mass of the pressure-sensitive adhesive layer separated from the measurement sample before being attached to the polarizing plate is accurately measured, immersed in toluene for 24 hours, and then filtered through a 200 mesh wire net. Then, after drying a filtered material at 100 degreeC for 1 hour, the mass of the residue was measured correctly and the gel fraction of the adhesive layer (adhesive layer after bridge | crosslinking) was computed from the following formula | equation.
Gel fraction (%) of the pressure-sensitive adhesive layer = insoluble part mass (g) / mass of the pressure-sensitive adhesive layer (g) × 100

<Adhesive strength of adhesive layer>
The measurement sample obtained above (25 mm wide surface protective film bonded to the surface of the polarizing plate) was peeled at a low peeling rate (0.3 m / min) and 180 ° direction using a tensile tester. The peel strength measured after peeling at a high peel rate (30 m / min) was defined as the adhesive strength (N / 25 mm) of the pressure-sensitive adhesive layer.

<Surface resistivity of adhesive layer>
After aging, before bonding to the polarizing plate, peel off the release film (silicone resin-coated PET film) to expose the adhesive layer, and use a resistivity meter Hiresta UP-HT450 (manufactured by Mitsubishi Chemical Analytech) The surface resistivity (Ω / □) of the pressure-sensitive adhesive layer was measured.

<Peeling voltage>
When the measurement sample obtained above is peeled 180 ° at a tensile speed of 30 m / min, the voltage (charge voltage) generated by charging the polarizing plate is measured with high-precision electrostatic sensors SK-035 and SK-200 ( (Manufactured by Keyence Co., Ltd.), and the maximum value of the measured value was defined as the peel voltage (kV).

<Reworkability>
Here, excellent reworkability means that the adherend is not contaminated after being traced with a ballpoint pen over the surface protective film via the adhesive layer.
After tracing the surface protective film of the measurement sample obtained above with a ballpoint pen (using a scratch test device manufactured by Tester Sangyo Co., Ltd., applying a load of 500 g and going back and forth three times), the surface from the polarizing plate The protective film was peeled off, the surface of the polarizing plate was observed, and it was confirmed that the polarizing plate had no contamination transfer. Judgment criteria for evaluating reworkability were “◯” when there was no contamination transfer on the polarizing plate, “△” when the contamination transfer was confirmed at least partially along the trace traced with the ballpoint pen, and traced with the ballpoint pen. The case where contamination transfer was confirmed along the trajectory, and the release of the adhesive was also confirmed from the surface of the adhesive layer was evaluated as “x”.

<Durability of adhesive layer>
The measurement sample obtained above was allowed to stand in an atmosphere of 60 ° C. and 90% RH for 250 hours, then taken out to room temperature, and further allowed to stand for 12 hours. Then, the adhesive strength was measured and clearly compared with the initial adhesive strength. It was confirmed that there was no significant increase. The criteria for evaluating the durability of the pressure-sensitive adhesive layer are “○” when the adhesive strength after the test is 1.5 times or less of the initial adhesive strength, and “X” when the adhesive strength exceeds 1.5 times. did.

Table 5 shows the evaluation results. The surface resistivity was expressed by a system in which “m × 10 ^{+ n} ” is “mE + n” (where m is an arbitrary real value and n is a positive integer).

The surface protective films of Examples 1 to 6 have an adhesive strength of 0.04 to 0.2 N / 25 mm at a low peeling speed of 0.3 m / min to the adherend of the polarizing plate, and high speed peeling. Adhesive strength at a speed of 30 m / min is 2.0 N / 25 mm or less, surface resistivity is 9.0 × 10 ⁺¹¹ Ω / □ or less, peeling voltage is ± 0 to 0.5 kV, adhesive After the surface protective film was traced with a ballpoint pen through the layer, the adherend was not contaminated and excellent in durability when left in an atmosphere of 60 ° C. and 90% RH for 250 hours.
In addition, the pressure-sensitive adhesive composition used for the surface protective films of Examples 1 to 6 has a weight ratio (I) / (H) of (H) crosslinking catalyst to (I) keto enol tautomer compound of 70 to 1000. (83 to 500) and had an improved pot life as long as 6 hours or longer.
That is, (1) Balancing the adhesive strength at a low peeling speed and a high peeling speed, (2) all antistatic performance, (3) durability, and (4) all reworkability requirements. It meets the performance at the same time.

  Since the surface protective film of Comparative Example 1 uses an HDI isocyanurate body as a crosslinking agent, the gel fraction of the pressure-sensitive adhesive layer has a low value, and a low peeling speed of 0.3 m / min and a high peeling speed of 30 m / min. The adhesive strength was too high, and the reworkability and durability were slightly inferior.

  The surface protective film of Comparative Example 2 is because the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer is not copolymerized with an acrylic polymer, and an HDI isocyanurate body is used as a crosslinking agent. The gel fraction of the layer becomes a low value, the adhesive strength 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 the peeling voltage are high, reworkability and durability It was somewhat inferior.

  The surface protective film of Comparative Example 3 includes (C) an excessive amount of copolymerizable monomers containing a carboxyl group, uses an HDI isocyanurate as a crosslinking agent, and includes (I) a ketoenol tautomer compound. Because there is no (that is, the weight ratio of (I) / (H) is 0), the pot life becomes too short, and the gelation of the pressure-sensitive adhesive composition has progressed before coating, so that coating cannot be performed. It was.

  The surface protective film of Comparative Example 4 is an adhesive in which (B) a copolymerizable monomer containing a hydroxyl group and (C) a copolymerizable monomer containing a carboxyl group are not copolymerized with an acrylic polymer. The gel fraction of the layer becomes 0%, and the absorbance in the 25% aqueous solution state of (D) polyalkylene glycol mono (meth) acrylate monomer is large, and the peeling speed is as low as 0.3 m / min. The adhesive strength at a speed of 30 m / min was too great, and the reworkability and durability were inferior. In addition, since (F) the antistatic agent was not included, the surface resistivity and the stripping voltage increased.

  As described above, in the surface protective films of Comparative Examples 1 to 4, (1) balancing the adhesive force at a low peeling speed and a high peeling speed, (2) excellent antistatic performance, (3) All the required performances of durability and (4) reworkability could not be satisfied at the same time.

Claims (6)

A pressure-sensitive adhesive composition comprising an acrylic polymer, (E) a crosslinking agent, and (F) an antistatic agent,
The acrylic polymer is
(A) With respect to a total of 100 parts by weight of at least one or more of (meth) acrylic acid ester monomers having an alkyl group with a carbon number of C4 to C18,
(B) 0.1-10 parts by weight of the total of at least one copolymerizable monomer containing a hydroxyl group;
(C) 0.05 to 1.0 part by weight of the total of at least one copolymerizable monomer containing a carboxyl group;
(D) a copolymer obtained by copolymerizing 5 to 50 parts by weight of a total of at least one polyalkylene glycol mono (meth) acrylate monomer,
The pressure-sensitive adhesive composition, wherein the (E) crosslinking agent is a bifunctional or higher functional pentamethylene diisocyanate compound. The acrylic polymer does not further contain (G) a hydroxyl group with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms. 0.1 to 20 parts by weight of a total of at least one of a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer is copolymerized,
The (E) crosslinking agent is a trifunctional pentamethylene diisocyanate compound, and one or more pentamethylene diisocyanates comprising 1,5-pentamethylene diisocyanate, 1,4-pentamethylene diisocyanate, and 1,3-pentamethylene diisocyanate The pressure-sensitive adhesive composition according to claim 1, wherein the compound is at least one selected from an isocyanurate body, an adduct body, and a burette body. The pressure-sensitive adhesive composition is used as the crosslinking agent (E) with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms. 0.1 to 10 parts by weight of a bi- or higher functional pentamethylene diisocyanate compound, 0.001 to 0.5 parts by weight of (H) a crosslinking catalyst, and (I) 0.1 to 0.1 part of a ketoenol tautomer compound. ~ 300 parts by weight,
The pressure-sensitive adhesive composition is used as the antistatic agent (F) with respect to a total of 100 parts by weight of at least one (meth) acrylic acid ester monomer having (A) an alkyl group having C4 to C18 carbon atoms. A ionic compound that is solid at a temperature of 25 ° C. and a melting point of 25 to 50 ° C. in a proportion of 0.01 to 5.0 parts by weight,
The (D) polyalkylene glycol mono (meth) acrylate monomer was selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate, The average repeat number of alkylene oxides constituting at least one kind of polyalkylene glycol chain is 3 to 14, and the absorbance in a 25% aqueous solution state is 0.04 or less. Or the adhesive composition of 2. The copolymerizable monomer containing the (B) hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate. At least one selected from the group consisting of N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide,
The copolymerizable monomer containing the (C) carboxyl group is (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, The carboxypolycaprolactone mono (meth) acrylate or 2- (meth) acryloyloxyethyltetrahydrophthalic acid is selected from the group of compounds, and is at least one or more types. A pressure-sensitive adhesive composition according to claim 1.   A surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition according to claim 1 on one side of a resin film.   A surface protective film for a polarizing plate comprising the surface protective film according to claim 5.