TWI758544B - Adhesive composition and surface-protective film - Google Patents

Abstract

The present invention provides an adhesive composition and a surface-protective film for forming the following adhesive layer from the same adhesive composition. The adhesive layer has excellent balance of adhesion under low and high peeling speeds, contamination resistance, excellent adhesion property for surface substrate made of TAC, PMMA, and PET, and excellent antistatic performance that does not degrade over time. The adhesive composition contains a first acrylic polymer having an acid value of 0.1 to 1.0, which is copolymerized by a mono(meth)acrylic acid ester monomer without polyalkylene glycol chain; a second acrylic polymer copolymerized by a mono(meth)acrylic acid ester monomer having polyalkylene glycol chain; (D) an isocyanate compound with more than three functional groups; (G) an ionic compound with a fluorine atom number of more than F7 and having a melting point of about 25-50℃; (E) a crosslinking retarder; and (F) a crosslinking catalyst other than the tin compound.

Description

Adhesive composition and surface protective film

The present invention relates to an antistatic agent-containing adhesive composition and a surface protective film. More specifically, it relates to an antistatic agent-containing adhesive composition that forms an adhesive layer of a surface protective film and is used for the purpose of protecting the surface of a polarizing plate by being attached to a polarizing plate constituting a liquid crystal display, and its use The surface protective film of the composition. The adhesive composition of the present invention has excellent adhesive properties and excellent antistatic properties that do not deteriorate over time.

Conventionally, in the process of preparing optical members, such as a polarizing plate which is a member which comprises a liquid crystal display, the surface protection film for temporarily protecting the surface of an optical member is stuck. Such a surface protection film is used only in the process of manufacturing an optical member, and when attaching an optical member to a liquid crystal display, it peels and removes from an optical member. Since such a surface protection film for protecting the surface of an optical member is used only in a manufacturing process, it is also generally called a process film.

Thus, the surface protection film used in the process of manufacturing an optical member has the structure which the adhesive bond layer was formed in the single side|surface of the polyethylene terephthalate (PET) resin film which has optical transparency. Before bonding to an optical member, the release film which performed the release process in order to protect this adhesive bond layer is bonded to the adhesive bond layer of a surface protection film. Moreover, optical members, such as a polarizing plate, are subject to the product inspection accompanied with optical evaluation, such as the display ability of a liquid crystal display panel, color tone, contrast, foreign matter contamination, in the state which bonded the surface protective film. Therefore, as a performance required for the surface protective film, it is required that no air bubbles, foreign matter and low molecular weight components of the adhesive composition adhere to the adhesive layer, that is, contamination resistance is required. In addition, when peeling the surface protection film from an optical member such as a polarizer, the static electricity generated by the static electricity generated when the adhesive layer is peeled off from the adherend may cause a malfunction of the electric control circuit of the liquid crystal display. Influence. Therefore, the adhesive layer constituting the surface protective film is required to have excellent antistatic properties. Furthermore, in recent years, in addition to conventional triacetyl cellulose (TAC), polymethyl methacrylate (PMMA) etc. Use of materials such as acrylic resins, polyester-based resins such as polyethylene terephthalate (PET), cyclic olefin-based polymers, and polycarbonates. When peeling off the surface protective film attached to the polarizer, the protective layer composed of these materials tends to cause peeling static electricity. Therefore, the antistatic performance more excellent than conventional is required for the adhesive layer for the surface protective film of the polarizer. . Moreover, when finally peeling off the surface protective film from optical members, such as a polarizing plate, it is required that peeling can be performed quickly. That is, in order to enable rapid peeling even at high-speed peeling, it is required that the change in adhesive force due to peeling speed be small.

In this way, in recent years, from the viewpoint of ease of use when using a surface protective film, as a required performance for the adhesive layer constituting the surface protective film, (1) at a low-speed peeling speed and a high-speed peeling speed; , to obtain a balance of adhesion; (2) with pollution resistance; (3) excellent antistatic properties and so on. However, with regard to the above (1) to (3), which are required properties for the adhesive layer constituting the surface protective film, even if each required performance can be satisfied separately, it is difficult to simultaneously satisfy the requirements for the adhesive layer of the surface protective film. (1)~(3) The technical problem of all the required performance. Further, it is also a very difficult technical problem to use the same adhesive composition to form an adhesive layer of a surface protective film that can be used on the surface of the protective layer and satisfies the required properties of the above (1) to (3). In addition to TAC, which is a protective layer material used in the past, acrylic resins such as polymethyl methacrylate (PMMA), polyester resins such as polyethylene terephthalate (PET), and cyclic olefin polymers are also used. , polycarbonate and other materials.

In order to solve such technical problems, for example, with respect to (1) obtaining a balance of adhesive force at low-speed peeling speed and high-speed peeling speed; (2) having contamination resistance; and (3) excellent antistatic performance, it has been The following proposals are known.

With regard to (1) achieving a balance of adhesive force at a low peeling speed and a high peeling speed, in a copolymerizable compound containing an alkyl (meth)acrylate having an alkyl group having a carbon number of 7 or less and a carboxyl group In the acrylic adhesive layer formed by cross-linking the copolymer as the main component with a cross-linking agent, in the case of long-term adhesion, the adhesive is transferred to the adherend side, or the adhesive is transferred to the adherend. There is a problem that the adhesive force of the sticky material has a large increase with time. In order to avoid these problems, it is known to provide an adhesive layer which is a copolymer of an alkyl (meth)acrylate having an alkyl group having 8 to 10 carbon atoms and an alcoholic hydroxyl group. A copolymer of a natural compound, and an adhesive layer obtained by crosslinking the copolymer with a crosslinking agent (Patent Document 1). In addition, there have also been proposed those provided with an adhesive layer, which is a copolymer obtained by blending a small amount of an alkyl (meth)acrylate and a carboxyl group-containing copolymerizable compound with the same copolymer as described above. The adhesive layer is formed by cross-linking the copolymer with a cross-linking agent. However, when they are used for surface protection of plastic sheets with low surface tension and smooth surface, there is a problem of peeling phenomenon such as lifting due to heating during processing or storage, or peeling at high speed in the field of manual work. the problem of poor re-peelability.

In order to solve these problems, there has been proposed an adhesive composition in which, to a) an alkyl (meth)acrylate having an alkyl (meth)acrylate having an alkyl group having 8 to 10 carbon atoms as a main component In 100 parts by weight of the ester, b) 1 to 15 parts by weight of a carboxyl-containing copolymerizable compound and c) 3 to 100 parts by weight of vinyl esters of aliphatic carboxylic acids having 1 to 5 carbon atoms are added to form a monomer A copolymer of a mixture, and a crosslinking agent in an equivalent amount or more with respect to the carboxyl group of the above-mentioned b) component is blended (Patent Document 2). The adhesive composition described in Patent Document 2 does not cause peeling phenomena such as floating during processing or storage, and also has a small increase in adhesive strength over time and excellent re-peelability, even if stored for a long time, especially even in Long-term storage in a high-temperature atmosphere enables re-peeling with a small force, no adhesive residue is generated on the adherend at this time, and re-peeling can be carried out with a small force even when peeling at a high speed.

In addition, regarding (2) having contamination resistance, an adhesive composition is disclosed, which contains 100 parts by mass of a carboxyl group-containing monomer from 0 parts by mass to less than 0.5 parts by mass, and 0.6 to 9 parts by mass of a hydroxyl group-containing monomer A (meth)acrylic copolymer having a weight-average molecular weight of 100,000 or more and less than 1,000,000 composed of a (meth)acrylic monomer and 99.4 to 90.5 parts by mass of a (meth)acrylate monomer; and 0.1 to 0.1 to 5 parts by mass of a carbodiimide-based crosslinking agent (Patent Document 3). The adhesive composition described in Patent Document 3 is characterized in that a carbodiimide-based crosslinking agent is used as a crosslinking agent for a (meth)acrylic copolymer having a specific composition. Thereby, the crosslinked structure which can follow the shrinkage by the pressure and temperature at the time of autoclaving can be formed in an adhesive bond layer. Therefore, the adhesive layer formed using this adhesive composition can suppress or prevent foaming even under high temperature and high pressure conditions (during autoclaving), is excellent in adherend contamination resistance, and is also excellent in transparency .

In addition, regarding (3) excellent antistatic performance, as a method for imparting antistatic properties to a surface protective film, a method of kneading an antistatic agent into a base film and the like are known. As antistatic agents, for example, (a) various cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts, first-order amine groups to third-order amine groups are disclosed; (b) sulfonate salts (c) Amphoteric antistatic agents such as amino acid, aminosulfate, etc.; (d) aminoalcohol, glycerin Nonionic antistatic agents such as polyglycols and polyethylene glycols; (e) high molecular weight antistatic agents and the like obtained by molecularizing the above antistatic agents (Patent Document 4). In addition, in recent years, it has been proposed that such an antistatic agent is not contained in the base film or coated on the surface of the base film, but contained in the adhesive layer.

In addition, an antistatic adhesive composition is disclosed, which is obtained by dispersing a salt having an anion containing a fluorine group and a sulfonyl group, characterized in that the above-mentioned salt having an anion containing a fluorine group and a sulfonyl group, The dispersion is performed in a state of being dissolved in a polyether ester-based plasticizer containing a polyether group in the main chain (Patent Document 5). Regarding the adhesive composition described in Patent Document 5, it is disclosed to use, as a plasticizer, a plasticizer composed of an ester composed of a mono- or dibasic carboxylic acid having a saturated or unsaturated acyclic hydrocarbon group and a It is an ester formed by an alcohol of 1 to 20 acyclic hydrocarbon groups; or an ester in which the unsaturated group in the unsaturated acyclic hydrocarbon group is epoxidized. It is considered that such a mono- or di-carboxylic acid having a saturated or unsaturated acyclic hydrocarbon group has a carbon number close to that of the acrylic monomer constituting the acrylic copolymer used in the adhesive layer. Therefore, the compatibility with the antistatic adhesive composition is good, and it can be suitably retained in the plasticizer acrylic antistatic adhesive composition, thereby suppressing bleed-out. [Prior Art Literature] [Patent Literature]

Patent Document 1: JP 63-225677 A Patent Document 2: JP 11-256111 A Patent Document 3: JP 2011-122054 A Patent Document 4: JP 11-070629 A Patent Document 5: Japanese Patent Laid-Open No. 2014-118469

[Technical problem to be solved by the present invention]

As described above, in the prior art, as the performance required for the adhesive layer constituting the surface protective film, it is required to obtain a balance of adhesive force at a low-speed peeling speed and a high-speed peeling speed, to have contamination resistance, and to have excellent antistatic properties. performance, etc. However, even if each required performance can be satisfied separately, all required performances required for the adhesive layer of the surface protective film cannot be satisfied at the same time. Furthermore, in the prior art, it was not possible to prepare an adhesive layer that can be used for all surface substrates composed of TAC, PMMA, and PET, and that simultaneously satisfies all the required properties for an adhesive layer of a surface protective film.

The present invention has been made in view of the above-mentioned circumstances, and its technical problem is to provide an adhesive composition and a surface protective film which are excellent in the balance of adhesive force under low-speed peeling speed and high-speed peeling speed, and have contamination resistance and excellent adhesion performance . In addition, the technical problem is to provide an adhesive composition and a surface protective film that can form an adhesive layer from the same adhesive composition. Excellent antistatic properties that deteriorate over time. [Technical means to solve technical problems]

In an adhesive composition having antistatic properties and a surface protective film using the same, the relationship between antistatic properties and contamination resistance to adherends is a trade-off relationship , it is extremely difficult to improve stain resistance while maintaining antistatic properties. Therefore, the inventors of the present invention solved the technical problem by taking the following adhesive composition as the technical idea of the present invention. The adhesive composition contains: a first acrylic copolymer obtained by copolymerizing a carboxyl group-containing copolymerizable monomer in a manner that does not contain a polyalkylene glycol chain-containing mono(meth)acrylate monomer A second acrylic polymer containing a mono(meth)acrylate monomer containing a polyalkylene glycol chain, preferably containing: a polyether-containing polysiloxane compound; an anion having a fluorine number of F7 or more (For example, nonafluorobutanesulfonate anion) is an antistatic agent formed of an ionic compound having a melting point of 25°C or higher.

In order to solve the above-mentioned technical problems, the present invention provides an adhesive composition comprising an acrylic polymer, an antistatic agent and a crosslinking agent, wherein the acrylic polymer is the following first acrylic polymer and the second acrylic polymer, wherein the first acrylic polymer is a first acrylic polymer of a copolymer having an acid value of 0.1 to 1.0 and a weight average molecular weight of more than 300,000 and 1.2 million or less, which does not contain In the form of a polyalkylene glycol chain-containing mono(meth)acrylate monomer, a (meth)acrylate monomer having a carbon number of C1 to C18 with respect to a total of 100 parts by weight of the (A) alkyl group At least one or more of the monomers, at least one or more of (B) a hydroxyl group-containing copolymerizable monomer and a total of 0.01 to 0.6 weight parts of (C) at least one of the carboxyl group-containing copolymerizable monomers are copolymerized in an amount of 1.0 to 6.0 parts by weight. The first acrylic polymer is composed of at least one kind of (meth)acrylate monomers having a carbon number of C1 to C18 in the (A) alkyl group in a total of 100 parts by weight, 2-ethylhexyl acrylate is contained in an amount of 70 parts by weight or more, and the second acrylic polymer is a second acrylic polymer of a copolymer obtained by copolymerizing the following: (a) Carbon of an alkyl group At least one or more of (meth)acrylate monomers having an atomic number of C1 to C18, (b) at least one or more of hydroxyl-containing copolymerizable monomers, and (c) polyalkylene glycol chain-containing mono( At least one or more of meth)acrylate monomers, the glass transition temperature of the first acrylic polymer and the second acrylic polymer is 0°C or lower, and the crosslinking agent is (D) trifunctional or higher The isocyanate compound, the antistatic agent is (G) an ionic compound with an anion having a fluorine atom number of F7 or more, and an ionic compound formed by a cation and an anion with a melting point of 25 to 50° C. The adhesive composition further contains (E ) A crosslinking retarder and (F) a crosslinking catalyst other than a tin compound as a crosslinking catalyst.

The adhesive composition of the present invention is an adhesive composition for a surface protective film attached to the protective layer of the polarizer of the polarizer, preferably: the protective layer of the polarizer of the polarizer is selected from the group consisting of TAC film, One of the group consisting of PMMA film and PET film, and the surface treatment performed on the surface of the protective layer of the polarizer of the polarizer is selected from untreated, AG treatment, LR treatment, AR treatment, AG - One of the groups consisting of LR processing and AG-AR processing.

Preferably: the anion of the ionic compound contains selected from C ₆ F ₅ (CF ₂ ) _n COO ⁻ , C ₆ F ₅ (CF ₂ ) _n SO ₃ ⁻ , C ₆ F ₅ (CF ₂ ) _n O ⁻ , C ₆ F ₅ O(CF ² ) _n SO ₃ ^- , (C ₆ F ₅ CO) ₂ N ^- , (C ₆ F ₅ CO) ₃ C ^- , (C ₆ F ₅ SO ₂ ) ₂ N ^- , (C ₆ F ₅ SO ₂ ) ₃ C ^- , (C ₆ F ₅ OSO ₂ ) ₂ N ^- , (C ₆ F ₅ OSO ₂ ) ₃ C ^- , (C ₆ F ₅ ) ₄ B ^- , CF ₃ (CF ₂ ) ₃ SO ₃ ^- At least one or more of the group consisting of as an anion, the ionic compound is contained in a ratio of 0.01 to 15 parts by weight with respect to 100 parts by weight of the first acrylic polymer.

Preferably: the cation of the ionic compound is selected from the group consisting of pyridinium, imidazolium, phosphonium, peronium, pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, pyridinium, pyrazole One of the group consisting of pyrazolium, methylium, lithium, and morpholinium, with respect to 100 parts by weight of the first acrylic polymer, in an amount of 0.01 to 15 parts by weight The ratio contains the ionic compound.

Preferably, the surface resistivity of the adhesive layer obtained by crosslinking the adhesive composition is 1.0×10 ^{+ 12} Ω/□ or less, and the adhesive layer is suitable for forming a low refractive index layer using a fluorine compound. The peeling electrostatic voltage of the low-refractive index layer formed on the surface to be adhered is in the range of -0.3~+0.3kV, and the adhesive layer formed by crosslinking the adhesive composition to the polarizer is in the range of When the low-speed peeling speed is 0.3 m/min, the adhesive force is 0.04 to 0.2 N/25 mm, and when the high-speed peeling speed is 30 m/min, the adhesive force is 2.0 N/25 mm or less.

Preferably, the (B) hydroxyl group-containing copolymerizable monomer of the first acrylic polymer and the (b) hydroxyl group-containing copolymerizable monomer of the second acrylic polymer are selected from ( 8-Hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxyl At least one or more selected from the group consisting of (meth)acrylamide, N-methylol (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide, the (C) containing The copolymerizable monomer of the carboxyl group is selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acrylooxyethyl hexahydroortho Phthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxy Ethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyltetrahydrophthalate At least one or more of the compound group consisting of dicarboxylic acid.

Preferably: the (E) cross-linking retarder is a compound of keto-enol tautomer, and the (E) is contained in a ratio of 0.1 to 300 parts by weight relative to 100 parts by weight of the first acrylic polymer. E) a cross-linking retarder, the (F) cross-linking catalyst is at least one metal chelate compound selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds, relative to 100 The first acrylic polymer in parts by weight contains the (F) cross-linking catalyst in a ratio of 0.001 to 0.5 parts by weight, and the ratio of (E)/the (F) parts by weight is 80 to 1000.

Preferably: relative to 100 parts by weight of the first acrylic polymer, the adhesive composition contains a polyether-modified polyether having an HLB value of 6 to 12 and a weight average molecular weight of 10,000 or less in a ratio of 0.01 to 0.5 parts by weight. Siloxane compounds.

Preferably: relative to 100 parts by weight of the first acrylic polymer, the adhesive composition contains the second acrylic polymer in a ratio of 0.1 to 5.0 parts by weight as the second acrylic polymer , using at least one or more of (meth)acrylate monomers having C1 to C18 carbon atoms with respect to (a) the total of 100 parts by weight of the (a) alkyl group, and (b) containing 2.0 to 12.0 parts by weight in terms of copolymerization A copolymer of at least one or more copolymerizable monomers of a hydroxyl group and at least one or more of (c) a polyalkylene glycol chain-containing mono(meth)acrylate monomer in a total amount of 1 to 30 parts by weight. Further, the weight average molecular weight of the copolymer is preferably more than 300,000 and 1 million or less, particularly preferably more than 300,000 and 800,000 or less. Furthermore, it is preferable that at least one or more of (meth)acrylate monomers having carbon atoms of C1 to C18 with respect to the total of 100 parts by weight of the (A) alkyl group of the first acrylic polymer, ( B) The total weight part β1 = 100×(B)/(A) of at least one or more of the hydroxyl group-containing copolymerizable monomer, with respect to the total of 100 weight parts of the second acrylic polymer (a) The total weight parts of at least one or more of the (meth)acrylate monomers having an alkyl group with a carbon number of C1 to C18 and (b) at least one or more of the hydroxyl group-containing copolymerizable monomers β2 = 100×(b )/(a), the ratio K=β2/β1 of the β1 to the β2 is in the range of 1.0 to 2.0.

The second acrylic polymer is a copolymer with a weight average molecular weight exceeding 300,000 and below 800,000; the polyalkylene glycol chain-containing mono(meth)acrylate monomer constitutes a polyalkylene The average number of repeating units of the alkylene oxide of the glycol chain is 3 to 14; the diester component in the mono(meth)acrylate monomer containing the polyalkylene glycol chain is 0.2 % or less; in 100 parts by weight of the second acrylic polymer, preferably in a proportion of 1 to 50 parts by weight, more preferably in a proportion of 1 to 40 parts by weight, particularly preferably in a proportion of 1 to 30 parts by weight Selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate At least one or more in the group as the polyalkylene glycol chain-containing mono(meth)acrylate monomer.

Further, the present invention provides an adhesive film, wherein an adhesive layer obtained by crosslinking the above-mentioned adhesive composition is laminated on one side of a resin film.

Moreover, this invention provides the surface protection film using the said adhesive film.

Moreover, this invention provides the surface protective film for polarizers using the said adhesive film.

Furthermore, the present invention provides an optical film with an adhesive layer in which an adhesive layer cross-linked with the above-mentioned adhesive composition is laminated on at least one side of the optical film.

Furthermore, the present invention provides an adhesive film in which antistatic treatment and antifouling treatment are performed on one side of the resin film, that is, the side opposite to the side on which the adhesive layer is formed. [Inventive effect]

According to the present invention, it is possible to provide an adhesive composition and a surface protective film which are excellent in the balance of adhesive force at a low peeling speed and a high peeling speed, and have contamination resistance and excellent adhesive performance. Further, it is possible to provide an adhesive composition and a surface protective film that can form an adhesive layer from the same adhesive composition, and the adhesive layer can be used for a surface base material composed of TAC, PMMA, PET, and has a tendency to deteriorate over time. excellent antistatic properties.

Hereinafter, the present invention will be described based on preferred embodiments. The adhesive composition of the present embodiment contains an acrylic polymer, an antistatic agent and a crosslinking agent, and is characterized in that the acrylic polymer is the following first acrylic polymer and second acrylic polymer, The first acrylic polymer is the first acrylic polymer of a copolymer with an acid value of 0.1 to 1.0 and a weight average molecular weight of more than 300,000 and 1.2 million or less, which does not contain a polyalkylene glycol chain. In the form of the mono(meth)acrylate monomer, at least one or more of the (meth)acrylate monomers having a carbon number of C1 to C18 in the (A) alkyl group with respect to a total of 100 parts by weight are copolymerized. 1.0 to 6.0 parts by weight of (B) at least one or more of the hydroxyl group-containing copolymerizable monomers and 0.01 to 0.6 parts by weight of (C) at least one or more of the carboxyl group-containing copolymerizable monomers in total, the first An acrylic polymer is contained in a ratio of 70 parts by weight or more in at least one or more of the (meth)acrylate monomers having C1-C18 carbon atoms in the (A) alkyl group in a total of 100 parts by weight 2-ethylhexyl acrylate, the second acrylic polymer is a second acrylic polymer of a copolymer obtained by copolymerizing the following: (a) (a) the number of carbon atoms in the alkyl group is C1 to C18 ( At least one or more of meth)acrylate monomers, (b) at least one or more of hydroxyl group-containing copolymerizable monomers, and (c) polyalkylene glycol chain-containing mono(meth)acrylate monomers At least one or more, the glass transition temperature of the first acrylic polymer and the second acrylic polymer is 0°C or lower, the crosslinking agent is (D) a trifunctional or higher isocyanate compound, the antistatic The agent is (G) an ionic compound having an anion having a fluorine number of F7 or more and a melting point of 25 to 50° C. formed by a cation and an anion, and the adhesive composition further contains (E) a crosslinking retarder and (E) a crosslinking retarder and ( F) Crosslinking catalysts other than tin compounds of the crosslinking catalyst.

Compared with the conventional adhesive composition for surface protection films, the adhesive composition of this embodiment has the outstanding adhesive performance and the outstanding anti-peeling electrostatic performance which does not deteriorate with time. In particular, an adherend such as an optical film is formed by laminating an antifouling layer containing a fluorine compound or a composition for forming a low refractive index layer containing a fluorine compound on the surface of an optical film or the like serving as the adherend surface. When the low-refractive index layer is an adherend, compared with the existing surface protective film, the surface protective film of this embodiment has excellent adhesion performance and excellent anti-static anti-static performance that does not deteriorate over time, so that both anti-static performance can be achieved. Significant effect on performance and stain resistance. That is, the adhesive composition of the present embodiment and the surface protective film using the same have excellent adhesive performance and excellent anti-peeling electrostatic performance that does not deteriorate over time, and therefore have great industrial utility value.

The acrylic polymer used in the adhesive composition of the present embodiment is the main ingredient polymer of the adhesive composition, and the glass transition temperature is 0°C or lower. In addition, it is preferable that the acrylic polymer is a copolymer mainly composed of a (meth)acrylate monomer having C1 to C18 carbon atoms in the (A) alkyl group.

The acrylic polymer used in the adhesive composition of the present embodiment is a first acrylic polymer containing no polyalkylene glycol chain-containing mono(meth)acrylate monomer and a polyalkylene-containing A second acrylic polymer of a mono(meth)acrylate monomer of a diol chain.

The first acrylic polymer is a copolymer having a glass transition temperature of 0°C or lower, which is composed of (A) an alkyl group so as not to contain a polyalkylene glycol chain-containing mono(meth)acrylate monomer. A (meth)acrylate monomer having a carbon number of C1 to C18, (B) a hydroxyl group-containing copolymerizable monomer, and (C) a carboxyl group-containing copolymerizable monomer are copolymerized. In addition, the second acrylic polymer is a copolymer having a glass transition temperature of 0° C. or lower, which is composed of (a) at least one or more of (meth)acrylate monomers whose alkyl groups have C1 to C18 carbon atoms, (a) b) At least one or more of hydroxyl group-containing copolymerizable monomers and (c) at least one or more of polyalkylene glycol chain-containing mono(meth)acrylate monomers are copolymerized.

The (meth)acrylate monomer having (A) the alkyl group of the first acrylic polymer having C1 to C18 carbon atoms, and the (a) alkyl group of the second acrylic polymer having the carbon number of C1 The (meth)acrylate monomers of ~C18 include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, (meth)acrylate ) isobutyl acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylate ) 2-ethylhexyl acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, (meth)acrylic acid Lauryl ester, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, Heptadecyl (meth)acrylate, octadecyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. The alkyl group of the (meth)acrylic acid alkyl ester monomer may be linear, branched, or cyclic.

The first acrylic polymer used in the adhesive composition of the present embodiment preferably contains at least 100 parts by weight of the (A) alkyl group (meth)acrylate monomer having C1 to C18 carbon atoms in total. In one or more kinds, 2-ethylhexyl acrylate is contained in a ratio of 70 parts by weight or more.

The first acrylic polymer used in the adhesive composition of the present embodiment contains (B) a hydroxyl group-containing copolymerizable monomer. In addition, the second acrylic polymer contains (b) a hydroxyl group-containing copolymerizable monomer. The (B) hydroxyl group-containing copolymerizable monomer of the first acrylic polymer and the (b) hydroxyl group-containing copolymerizable monomer of the second acrylic polymer are preferably selected from 8-hydroxyoctane (meth)acrylate Ester, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-methylol At least one or more of the group of compounds consisting of oxyethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and the like.

It is preferable that the total amount of the first acrylic polymer is 1.0 to 6.0 parts by weight relative to 100 parts by weight in total of (A) at least one of the (meth)acrylate monomers having C1 to C18 carbon atoms in the alkyl group. (B) at least one or more of the hydroxyl group-containing copolymerizable monomer is contained in a proportion of 1.6 to 5.8 parts by weight, more preferably 1.6 to 5.8 parts by weight, particularly preferably 2.1 to 5.8 parts by weight.

It is preferable that the total amount of the second acrylic polymer is 2.0 to 12.0 parts by weight relative to 100 parts by weight of (a) at least one of the (meth)acrylate monomers having C1 to C18 carbon atoms in the alkyl group in total. (b) at least one or more of the hydroxyl group-containing copolymerizable monomer is contained in a proportion of 3.0 to 11.0 parts by weight, particularly preferably 4.0 to 10.0 parts by weight.

At least one or more (B) hydroxyl group-containing (meth)acrylate monomers having C1 to C18 carbon atoms in the first acrylic polymer with respect to 100 parts by weight of the (A) alkyl group in total The total weight part β1 of at least one or more of the copolymerizable monomers is represented by β1=100×(B)/(A). Similarly, at least one or more of the (meth)acrylate monomers having a carbon number of C1 to C18 with respect to (a) the alkyl group in the second acrylic polymer in total of 100 parts by weight, (b) ) The total weight part β2 of at least one or more of the hydroxyl group-containing copolymerizable monomer is represented by β2=100×(b)/(a). The weight part β2 of (b) in the second acrylic polymer is preferably equal to or more than the weight part β1 of (B) in the first acrylic polymer, and the ratio K=β2/β1 is preferably in the range of 1.0 to 2.0.

The first acrylic polymer used in the adhesive composition of the present embodiment contains (C) a carboxyl group-containing copolymerizable monomer. (C) The carboxyl group-containing copolymerizable monomer is preferably selected from (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxy ethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(methyl) base) acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxy At least one or more of the compound group consisting of ethyltetrahydrophthalic acid and the like.

The first acrylic polymer is preferably 0.01 to 0.6 parts by weight in total with respect to 100 parts by weight of (A) at least one of the (meth)acrylate monomers having C1 to C18 carbon atoms in the alkyl group in total. (C) at least one or more of the carboxyl group-containing copolymerizable monomer is contained in a proportion of 0.01 to 0.5 parts by weight, particularly preferably 0.01 to 0.4 parts by weight.

The second acrylic polymer used in the adhesive composition of the present embodiment contains (c) a polyalkylene glycol chain-containing mono(meth)acrylate monomer. Therefore, in the adhesive composition of the present embodiment, it is considered that the second acrylic polymer containing the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer serves as an antistatic adjuvant. Play a role. The second acrylic polymer is preferably contained in a ratio of 0.1 to 5.0 parts by weight, more preferably 0.1 to 3.5 parts by weight, and particularly preferably 0.1 to 2.5 parts by weight relative to 100 parts by weight of the first acrylic polymer thing. When the content of the second acrylic polymer is less than the above-mentioned range, the surface resistivity and the peeling electrostatic voltage increase, and the antistatic performance decreases. In addition, the contamination resistance to the polarizer deteriorates.

As the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer, one of the plurality of hydroxyl groups contained in the polyalkylene glycol is esterified to (methyl) A compound made of acrylate may be used. Since the (meth)acrylate group is a polymerizable group, it can be copolymerized with the second acrylic polymer. It can also be other polyalkylene glycol mono(meth)acrylates whose hydroxyl groups are still OH, or alkoxy polyalkylene glycol mono(meth)acrylates whose hydroxyl groups are changed to alkyl ethers. esters, etc. Moreover, since polyalkylene glycol mono(meth)acrylate corresponds to (c), even if it contains a hydroxyl group, it is not classified into (B) or (b).

As the polyalkylene glycol constituting the polyalkylene glycol chain, any glycol compound having one or two or more types of alkylene groups may be used, and examples thereof include polyethylene glycol, polypropylene glycol, and polybutylene. Glycol, polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol, etc.

In the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer, the average number of repeating units of the alkyleneoxy group constituting the polyalkylene glycol chain is preferably 3 to 14. The "average number of repeating units of an alkyleneoxy group" means the "polyalkylene glycol chain" contained in the molecular structure of the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer. ” section, the average number of repeating alkyleneoxy units.

In addition, it is preferable that the diester component in the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer be 0.2% or less. "The diester component in the monomer" refers to the polyalkylene glycol di(meth)acrylate contained in the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer content (wt%).

The (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer is preferably selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol ( At least one or more of the group consisting of meth)acrylate and ethoxypolyalkylene glycol (meth)acrylate. In 100 parts by weight of the second acrylic polymer, the ratio of the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer in the second acrylic polymer is preferably 1 to 50 weight parts The ratio of parts by weight is more preferably a ratio of 2 to 35 parts by weight, and particularly preferably a ratio of 2 to 25 parts by weight.

In addition, in 100 parts by weight of the second acrylic polymer, it is preferable to contain 1 to 50 parts by weight, more preferably 1 to 40 parts by weight, and particularly preferably 1 to 30 parts by weight. In the group consisting of alkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, ethoxypolyalkylene glycol (meth)acrylate At least one or more as (c) a polyalkylene glycol chain-containing mono(meth)acrylate monomer. In addition, at least one or more of (meth)acrylate monomers having C1 to C18 carbon atoms in the (a) alkyl group with respect to 100 parts by weight in total, preferably (c) polyalkylene glycol chain-containing The total of at least one or more of the mono(meth)acrylate monomers is a ratio of 1 to 30 parts by weight.

Examples of monomers other than the (c) polyalkylene glycol chain-containing mono(meth)acrylate monomer to be copolymerized as the second acrylic polymer include carbon atoms of the above-mentioned (a) alkyl group. At least one kind or more of (meth)acrylate monomers having an atomic number of C1 to C18, and (b) hydroxyl group-containing copolymerizable monomers. The monomers (a) and (b) that are copolymerized as the second acrylic polymer may be different from the monomers (A) and (B) that are copolymerized as the first acrylic polymer. The carboxyl group-containing copolymerizable monomer may not be copolymerized with the second acrylic polymer.

The preparation method of the acrylic polymer contained in the adhesive composition of the present embodiment is not particularly limited, and suitable and well-known polymerization methods such as solution polymerization method and emulsion polymerization method can be used. The weight average molecular weight of the copolymer of the first acrylic polymer is, for example, more than 300,000 and 1,200,000 or less. The weight average molecular weight of the copolymer of the second acrylic polymer is, for example, more than 300,000 and 1,000,000 or less, preferably more than 300,000 and 800,000 or less, preferably more than 400,000 and 800,000 or less. When the weight-average molecular weight of the copolymer of the second acrylic polymer is 300,000 or less, the contamination resistance to the polarizer is deteriorated, which is not preferable.

The acid value of the first acrylic polymer is preferably 0.1 to 1.0. Thereby, contamination resistance can be improved. Here, the "acid value" is one of the indexes showing the content of the acid, and is expressed in mg of potassium hydroxide required to neutralize 1 g of the carboxyl group-containing polymer. The acid value of the second acrylic polymer is preferably 1.0 or less, and may be 0.0 when the carboxyl group-containing copolymerizable monomer is not copolymerized with the second acrylic polymer.

The adhesive composition of this embodiment contains (G) an antistatic agent. The (G) antistatic agent of the present embodiment is an ionic compound composed of a cation and an anion, which has an anion having a fluorine number of F7 or more. The ionic compound preferably has a melting point of 25 to 50°C and is solid at normal temperature (for example, 25°C). The ionic compound is preferably contained in a ratio of 0.01 to 15 parts by weight, more preferably 0.01 to 10 parts by weight, and particularly preferably 0.01 to 8 parts by weight with respect to 100 parts by weight of the first acrylic polymer.

Examples of the anion of the ionic compound include C ₆ F ₅ (CF ₂ ) _n COO ⁻ , C ₆ F ₅ (CF ₂ ) _n SO ₃ ⁻ , C ₆ F ₅ (CF ₂ ) _n O ⁻ , C ₆ F ₅ O(CF ₂ ) _n SO ₃ ^- , (C ₆ F ₅ CO) ₂ N ^- , (C ₆ F ₅ CO) ₃ C ^- , (C ₆ F ₅ SO ₂ ) ₂ N ^- , (C ₆ F ₅ SO ₂ ) ₃ C ^- , (C ₆ F ₅ OSO ₂ ) ₂ N ^- , (C ₆ F ₅ OSO ₂ ) ₃ C ^- , (C ₆ F ₅ ) ₄ B ^- , CF ₃ (CF ₂ ) At least one or more of the group consisting of ₃ SO ₃ ^- . Here, n is an integer of 1 or more. Examples of the cation of the ionic compound include pyridinium, imidazolium, phosphonium, peronium, pyrrolidinium, guanidinium, ammonium, isourium, thiouronium, pyridinium, pyrazolium, methyl At least one or more selected from the group consisting of onium, lithium, and morpholinium.

Specific examples of the (G) antistatic agent include, for example, methyltrioctylammonium tris(pentafluorobenzenesulfonyl)methide salt, 3-methyl-1-octylpyridinium nonafluorobutane Sulfonate, 1-ethyl-3-methylimidazolium tetrakis(pentafluorophenyl)borate, 1-butyl-1-methylpyridinium bis(pentafluorobenzenesulfonyl)imide salt, etc. .

The adhesive composition of the present embodiment further contains (D) a trifunctional or higher isocyanate compound as a crosslinking agent. (D) Trifunctional or higher isocyanate compounds include, for example, hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and the like A diisocyanate-based biuret-modified product or an isocyanurate-modified product, an adduct with a trivalent or higher polyol such as trimethylolpropane or glycerin, and the like. (D) As a ratio of a trifunctional or more isocyanate compound, the ratio of 0.01-5 weight part with respect to 100 weight part of 1st acryl-type polymers is mentioned, for example.

The adhesive composition of this embodiment may contain (E) a crosslinking retarder. (E) As a crosslinking retarder, methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and acetoacetate are exemplified β-ketoesters such as stearyl ester, or β-diketones such as acetylacetone, 2,4-hexanedione, and benzalacetone. These cross-linking retarders are compounds of keto-enol tautomers, and in the adhesive composition using polyisocyanate compounds as cross-linking agents, the isocyanate groups of the cross-linking agent are blocked by blocking. , it is possible to suppress excessive viscosity increase or gelation of the adhesive composition after blending the cross-linking agent, and prolong the pot life of the adhesive composition. (E) The crosslinking retarder is preferably a compound of a keto-enol tautomer, particularly preferably at least one or more selected from the group of compounds consisting of acetylacetone and ethylacetate. The (E) crosslinking retarder is preferably contained in a ratio of 0.1 to 300 parts by weight with respect to 100 parts by weight of the first acrylic polymer.

The adhesive composition of the present embodiment may contain a crosslinking catalyst other than the tin compound as the (F) crosslinking catalyst. When a polyisocyanate compound is used as the crosslinking agent, the (F) crosslinking catalyst may be any one that acts as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent. Examples of crosslinking catalysts other than tin compounds include amine compounds such as tertiary amines, metal chelate compounds, organic lead compounds, organic metal compounds such as organic zinc compounds, and the like.

(F) The metal chelate compound as a crosslinking catalyst is a compound in which one or more multidentate ligands L are bonded to the central metal atom M. The metal chelate compound may have at least one monodentate ligand X bound to the metal atom M, or may not have the monodentate ligand X. Specific examples of the metal chelate compound include tris(2,4-pentanedione)iron (III), iron triacetate, titanium triacetate, ruthenium triacetate, and zinc diacetate acetonate. , aluminum triacetate, zirconium tetraacetate, tris (2,4-hexanedione) iron (III), bis (2,4-hexanedione) zinc, tris (2,4-hexanedione) Titanium, tris (2,4-hexanedione) aluminum, tetrakis (2,4-hexanedione) zirconium, etc.

As the (F) crosslinking catalyst, at least one metal chelate compound selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound is preferable. The (F) crosslinking catalyst is preferably contained in a ratio of 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the first acrylic polymer.

Since the (E) crosslinking retarder has an effect of inhibiting crosslinking in contrast to the (F) crosslinking catalyst, it is preferable to appropriately set the ratio of the (E) crosslinking retarder and the (F) crosslinking catalyst. In order to prolong the pot life of the adhesive composition and improve the storage stability, the weight ratio of (E)/(F) is preferably 80-1000. Here, the weight part ratio of (E)/(F) is the value of the quotient calculated by dividing the weight part of (E) by the weight part of (F).

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

(H) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 6 to 12. In addition, (H) is preferably contained in a ratio of 0.01 to 0.5 parts by weight, more preferably in a ratio of 0.02 to 0.35 parts by weight, and particularly preferably in a ratio of 0.02 to 0.25 parts by weight with respect to 100 parts by weight of the first acrylic polymer Polyether modified siloxane compound. The HLB value means, for example, a hydrophilic-lipophilic balance value (hydrophilic-lipophilic ratio) defined in JIS K3211 (terminology of surfactants) or the like.

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 having a hydridosilyl group through a hydrosilylation reaction. on the main chain. Specifically, dimethylsiloxane-methyl (polyoxyethylene) siloxane copolymer, dimethyl siloxane, methyl (polyoxyethylene) siloxane, methyl poly(oxypropylene) siloxane copolymer, dimethylsiloxane and methyl(polyoxypropylene) siloxane polymer, etc.

By blending the (H) polyether-modified siloxane compound into the adhesive composition, the adhesive force and reworkability of the adhesive layer can be improved. The weight average molecular weight of the (H) polyether-modified siloxane compound is preferably 10,000 or less. From the viewpoint of compatibility with the first acrylic polymer, although the polyether-modified siloxane compound with a low HLB value and low molecular weight has good compatibility, as long as it is a polyether-modified siloxane compound with a low molecular weight Alkane compounds, even if the HLB value is high and the compatibility with the polymer is slightly low, it is possible to obtain excellent antistatic properties.

Not limited to the above-mentioned additives, surfactants, curing accelerators, plasticizers, fillers, curing retarders, processing aids, antiaging agents, antioxidants, etc. may be appropriately blended in the adhesive composition of the present embodiment. well-known additives. These additives may be used alone or in combination of two or more.

The adhesive composition of this embodiment is suitable as an adhesive composition for surface protection films bonded together on the protective layer of the polarizer of a polarizer. Here, at least one kind selected from the group consisting of a TAC-type film, a PMMA-type film, and a PET-type film can be mentioned as the protective layer of the polarizer of a polarizing plate. Here, TAC is an abbreviation for triacetyl cellulose, PMMA is an abbreviation for polymethyl methacrylate, and PET is an abbreviation for polyethylene terephthalate. The adhesive composition of the present embodiment can be used for three or more surface substrates composed of TAC, PMMA, and PET through the same adhesive layer.

In addition, the surface treatment applied to the surface of the protective layer of the polarizer of the polarizer may be selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment at least one. Here, AG refers to anti-glare, LR refers to low reflection, and AR refers to anti-reflection. The adhesive composition of the present embodiment can improve the surface of the polarizer. The substrate is PMMA or PET, and at least one of AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment has been carried out. pollution resistance.

In the adhesive layer obtained by crosslinking the adhesive composition of the present embodiment, the surface resistivity of the adhesive layer is preferably 1.0×10 ^{+ 12} Ω/□ or less, and more preferably 5.0×10 ^{+ 11} Ω/ □ or less, particularly preferably 1.0×10 ^{+ 11} Ω/□ or less. When the surface resistivity is large, the performance of releasing static electricity generated when the adhesive layer is peeled off from the adherend is poor. Therefore, by sufficiently reducing the surface resistivity, the peeling electrostatic voltage caused by the static electricity generated when the adhesive layer is peeled off from the adherend can be reduced, and the influence on the adherend can be suppressed.

In order to form an adhesive layer by crosslinking the adhesive composition of the present embodiment, the adhesive layer preferably has a low refractive index formed on the surface to be adhered using the composition for forming a low refractive index layer containing a fluorine compound. The peel electrostatic voltage of the layer is in the range of -0.3 to +0.3 kV. As the fluorine compound used in the composition for forming the low refractive index layer, one or two or more of fluorinated olefins, fluorinated vinyl ethers, fluorinated alkyl (meth)acrylates, and the like can be exemplified Fluorine-containing copolymers of polymers, condensates of fluorinated alkyl-containing silane compounds, etc. The fluorinated copolymer may be copolymerized with non-fluorinated monomers such as olefins, vinyl ethers, and (meth)acrylates in addition to fluorinated monomers. The low refractive index layer may be combined with a high refractive index layer or the like to constitute an antireflection layer.

The adhesive force of the adhesive layer obtained by crosslinking the adhesive composition of the present embodiment to the polarizer is preferably 0.04 to 0.2 N/25 mm at a low-speed peeling speed of 0.3 m/min, and at a high-speed peeling speed The adhesive strength at 30 m/min is preferably 2.0 N/25 mm or less, and the adhesive strength at a high-speed peeling speed of 30 m/min is more preferably 0.2 to 1.6 N/25 mm. Thereby, the performance with little change of the adhesive force due to the peeling speed is obtained, and the peeling can be performed quickly even by high-speed peeling. Further, even when the surface protective film is temporarily peeled off for re-attachment, excessive force is not required, and it is easy to peel off from the adherend.

The gel fraction of the adhesive layer obtained by crosslinking the adhesive composition of the present embodiment is preferably 95 to 100%, and more preferably 97 to 100%. With such a high gel fraction, the adhesive force will not be too large at a low peeling speed, which can reduce the dissolution of unpolymerized monomers or oligomers from the copolymer, and improve reprocessing or high temperature and high humidity. Durability, inhibit contamination by sticky matter.

The adhesive film of this embodiment is formed by forming an adhesive layer obtained by crosslinking the adhesive composition of this embodiment on one side or both sides of a resin film. Moreover, the surface protective film of this embodiment is a surface protective film which formed the adhesive bond layer which bridge|crosslinked the adhesive composition of this embodiment on the single side|surface of a resin film. The adhesive composition of the present embodiment has excellent antistatic properties, has an excellent balance of adhesive force at a low peeling speed and a high peeling speed, and has contamination resistance. Therefore, it can be suitably used for the use of the surface protection film of a polarizing plate.

As the base film of the adhesive layer or the release film (separator film) for protecting the adhesive surface, a resin film such as a polyester film or the like can be used. Antistatic treatment and antifouling treatment can be performed on one side of the resin film, that is, on the side opposite to the side on which the adhesive layer is formed. Examples of the antistatic treatment include coating or kneading of an antistatic agent. Examples of the antifouling treatment include treatments based on polysiloxane-based and fluorine-based release agents or coating agents, silica fine particles, and the like. The release film may be subjected to release treatment with a polysiloxane-based, fluorine-based, long-chain alkyl-based release agent, or the like, on the surface on the side that is bonded to the adhesive surface of the adhesive layer.

Moreover, the optical film with an adhesive bond layer can be obtained by laminating|stacking the adhesive bond layer which bridge|crosslinked the adhesive bond composition of this embodiment on at least one surface of an optical film. As an optical film, a polarizing film, a retardation film, an antireflection film, an anti-glare film, an ultraviolet absorption film, an infrared absorption film, an optical compensation film, a brightness improvement film, etc. are mentioned. As an apparatus to which an optical member is applied, a liquid crystal panel, an organic EL panel, a touch panel, etc. are mentioned. In the case of an optical surface protective film and an adhesive film such as a surface protective film for polarizers, it is preferable that the base film and the adhesive layer have sufficient transparency. [Example]

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

<Preparation of First Acrylic Polymer> [Example 1] Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen gas introduction pipe, and the air in the reaction apparatus was replaced with nitrogen gas. Then, 90 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl acrylate, 5.5 parts by weight of 8-hydroxyoctyl acrylate, and 0.2 parts by weight of acrylic acid were added to the reaction apparatus, while adding a solvent (ethyl acetate) ester). Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and the reaction was carried out at 65° C. for 6 hours to obtain the first acrylic polymer used in Example 1. [Examples 2 to 6 and Comparative Examples 1 to 3] The same composition as the first acrylic acid used in the above Example 1 was used, except that the components of the monomers were as described in (A) to (C) of Table 1, respectively. In the same manner as the polymer solution, the first acrylic polymer solutions used in Examples 2 to 6 and Comparative Examples 1 to 3 were obtained.

<Preparation of Adhesive Composition and Surface Protective Film> [Example 1] To the first acrylic polymer solution of Example 1 prepared as described above, 2.0 parts by weight of a crosslinking agent (CORONATE HX), 9 parts by weight of a crosslinking retarder (acetone), 0.1 part by weight of a crosslinking catalyst (titanium triacetone), 0.9 part by weight of an antistatic agent (methyltrioctylammonium tris(pentafluorobenzenesulfonate) base) methide salt), 0.05 parts by weight of polyether-modified siloxane compound (HLB=7), 0.2 parts by weight of copolymer B-1 (molecular weight 600,000), and stirring and mixing to obtain Example 1 Adhesive composition. After coating the adhesive composition on a release film (polysiloxane-coated PET film), the solvent was removed by drying at 90° C. to obtain an adhesive layer with a thickness of 20 μm. Then, the adhesive layer with the release film was transferred to the opposite side of the base film (PET film with antistatic and antifouling treatment on one side) to the antistatic and antifouling treated side On the above, the surface protection film of Example 1 which has the laminated structure of "substrate film/adhesive layer/release film" was obtained. [Examples 2 to 6 and Comparative Examples 1 to 3] The same surface protection as in Example 1 was used except that the components of the additives were as described in (D) to (H) and Copolymer B in Table 1, respectively. In the same manner as the film, the surface protection films of Examples 2 to 6 and Comparative Examples 1 to 3 were obtained.

[Table 1]

In Table 1, the total amount of (meth)acrylate monomers having C1 to C18 in the alkyl group (A) was set to 100 parts by weight, and the parts by weight of each component were determined. In addition, although "I-2" of Comparative Example 2 is described in the column (A) for convenience, it does not belong to the (meth)acrylate monomer having C1-C18 carbon atoms in the (A) alkyl group. In addition, in Table 1, in each column of (D), (E), (F), (G), (H), (copolymer B), the first acrylic polymer is set to 100 parts by weight, The content ratio (parts by weight) of each component is shown by the numerical value in parentheses ( ).

In addition, the compound name of the abbreviation symbol of each component used in Table 1 is shown in Tables 2-3. The second acrylic polymer in the above-described embodiment is "copolymer B", and the meanings of the abbreviations of the component monomers (a), (b), and (c) are described in (A) and (B), respectively. , (I). In addition, CORONATE (registered trademark) HX, CORONATE HL and CORONATE L are trade names of TOSOH CORPORATION, and TAKENATE (registered trademark) D-140N is a trade name of Mitsui Chemicals, Inc.

[Table 2]

[table 3]

(G) In the antistatic agent, G-1 to G-4 are all solid ionic compounds having a melting point of 25° C. or more and having an anion having a fluorine number of F7 or more. G-5 is a solid ionic compound having a melting point of 25° C. or higher and having an anion having a fluorine atom of F5. (H) In the polyether-modified siloxane compound, the weight average molecular weights of H-1 to H-6 are all 10,000 or less. (1) Among the polyalkylene glycol chain-containing mono(meth)acrylate monomers, the diester component in the monomers of I-1 to I-3 is 0.2% or less, and the monomer of I-4 The diester component is 0.8%. In addition, n in the column of Group (I) in Table 3 is a numerical value representing the average number of repeating units of an alkyleneoxy group.

<Test Method and Evaluation> The surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were aged for 7 days in an atmosphere of 23° C. and 50% RH, respectively, and then evaluated by the following test methods.

<Test method of adhesive force> The release film was peeled off, the surface protection film with the adhesive layer exposed was attached to the surface of the polarizer through the adhesive layer, and after standing for 1 day, the test was performed at 50° C. and 5 atmospheres for 20 minutes. After the autoclave was further placed at room temperature for 12 hours, it was used as a sample for the measurement of adhesive force. Using a tensile tester, the obtained measurement sample was peeled off in the 180° direction at a low speed (0.3 m/min) or a high speed (30 m/min), and the measured peel strength was used as the adhesive force. Here, the protective layer of the polarizer of the polarizer is selected from the group consisting of triacetyl cellulose (TAC), polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET). one of the groups. In addition, for the LR polarizer and the AG-LR polarizer, the surface of the protective layer of the polarizer of the polarizer was subjected to a low reflection surface treatment using a composition containing a fluorine compound.

<Test method for surface resistivity> After curing the surface protective film, before bonding it to the polarizer, the release film was peeled off to expose the adhesive layer, and a resistivity meter HIRESTA UP-HT450 (Mitsubishi Chemical Analytech Co. ., Ltd. manufactured) to measure the surface resistivity of the adhesive layer.

<Test method for peeling electrostatic voltage> The release film is peeled off, and the surface protection film exposing the adhesive layer is bonded to a polarizer having a low refractive index layer containing a fluorine compound on the adherend surface. A low-refractive-index layer formed from the composition used. When the surface protective film is peeled at 180° at a tensile speed of 30 m/min, the voltage (electrostatic voltage) generated by the charging of the adherend is measured using high-precision electrostatic sensors SK-035 and SK-200 (manufactured by KEYENCE CORPORATION). , and the maximum value of the measured values was taken as the peeling electrostatic voltage.

<Test method of stain resistance> Using a bonding machine, each polarizer selected from the five types shown in Table 4 was bonded to one side of a glass plate via an adhesive layer (double-sided adhesive tape). Then, the surface protection film was bonded to the surface of each polarizer using a bonding machine. After storage for 3 days and 30 days in an environment of 23° C. and 50% RH, the surface protective film was peeled off, and the contamination state of the surface of the polarizing plate was visually observed. As a criterion for the contamination resistance, the case where the surface of each polarizing plate was free of contamination was evaluated as "○", the case with slight contamination was evaluated as "△", and the case with contamination was evaluated as "x".

Table 4 shows the evaluation results of the surface protective films in Examples 1 to 6 and Comparative Examples 1 to 3. "Surface resistivity" is represented by writing "m×10 ⁺ⁿ " as "mE+n" (where m is an arbitrary real value, and n is a positive integer). The column of "contamination resistance (surface base material/surface treatment)" shows the results of evaluation for each of the material and surface treatment of the surface base material (protective layer of polarizer) of five types of polarizers. Plain for "surface treatment" means untreated.

[Table 4]

The surface protection films of Examples 1 to 6 had an adhesive force of 0.04 to 0.2 N/25 mm at a low-speed peeling speed of 0.3 m/min and a high-speed peeling speed of 30 m/min to the polarizer as an adherend The adhesive force at the time is 2.0N/25mm or less, and the adhesive performance is excellent. In addition, the surface resistivity of the adhesive layer of the surface protective films of Examples 1 to 6 was 1.0×10 ⁺¹² Ω/□ or less, and the adhesive layer pair was formed using the composition for forming a low refractive index layer containing a fluorine compound. The peeling electrostatic voltage of the low refractive index layer on the adhered surface is in the range of -0.3~+0.3kV, and the antistatic performance is excellent. Furthermore, the surface protective films of Examples 1 to 6 did not contaminate the polarizer as an adherend even after storage for 3 days and 30 days, and were excellent in contamination resistance. That is, it was confirmed that the evaluation result about the surface protective film of Examples 1-6 shown in Table 4 can solve the technical problem of this invention.

In the adhesive composition of Comparative Example 1, the weight average molecular weight of the copolymer B-5 was 10,000, which was small. In addition, the diester component of I-4 contained in the copolymer B-5 was 0.8%, which was large, and the average number of repeating units, n=23, was large. Moreover, (b) component contained in the copolymer B-5 of a 2nd acrylic polymer is 3 weight part, and it is less than 5.5 weight part of (B) component contained in a 1st acrylic polymer. The surface protective film of Comparative Example 1 using such an adhesive composition was excellent in contamination resistance to the polarizing plate based on TAC used so far, but was resistant to two types of polarizers based on PMMA or PET. Slightly less polluting.

In addition, in the adhesive composition of Comparative Example 2, the first acrylic polymer was copolymerized with a polyalkylene glycol chain-containing mono(meth)acrylate monomer, and (B) a hydroxyl group-containing copolymerizable The ratio of the monomer is 6.5 parts by weight, which is more. The surface protective film of Comparative Example 2 using such an adhesive composition had a low adhesive force of 0.03 N/25 mm at a low peeling speed of 0.3 m/min, which was low and poor in adhesive performance. The contamination resistance of the polarizer is poor, and the contamination resistance to the other polarizer is slightly poorer.

In addition, in the adhesive composition of Comparative Example 3, (C) the ratio of the carboxyl group-containing copolymerizable monomer is 1.5 parts by weight or more, and the antistatic agent contains an anion of F5 having a fluorine number smaller than that of F7. The peeling electrostatic voltage of the surface protective film of Comparative Example 3 using such an adhesive composition was 0.6 kV, which was high, and the antistatic performance was poor. In addition, the contamination resistance to the three polarizers was poor, and the resistance to the other polarizer was poor. Slightly less polluting.

In this way, the surface protection films of Comparative Examples 1 to 3 could not solve the technical problem of the present invention. In addition, for the surface protection film produced in the same manner as in Example 1 except that the copolymer B was not contained, the surface resistivity was increased, and the peeling electrostatic voltage was increased at the same time, and the antistatic performance was poor. Pollution is also poor.

without.

without.

Claims (15)

An adhesive composition, which is an adhesive composition containing an acrylic polymer, an antistatic agent and a crosslinking agent, wherein the acrylic polymer is the following first acrylic polymer and second acrylic acid The first acrylic polymer is a first acrylic polymer of a copolymer having an acid value of 0.1 to 1.0 and a weight average molecular weight of more than 300,000 and 1.2 million or less, which does not contain a polyalkylene group In the form of the mono(meth)acrylate monomer of the diol chain, at least one or more of the (meth)acrylate monomers having C1 to C18 carbon atoms with respect to the (A) alkyl group are added to 100 parts by weight, (B) 1.0 to 6.0 parts by weight in total of at least one or more of the hydroxyl group-containing copolymerizable monomers and (C) 0.01 to 0.6 parts by weight of at least one or more of the carboxyl group-containing copolymerizable monomers in total, the first The acrylic polymer contains acrylic acid 2- acrylic acid in a ratio of 70 parts by weight or more in a total of 100 parts by weight of at least one or more of the (meth)acrylate monomers having C1 to C18 carbon atoms in the (A) alkyl group Ethylhexyl ester, the second acrylic polymer is a second acrylic polymer of a copolymer obtained by copolymerizing the following: (a) (meth)acrylic acid having an alkyl group with a carbon number of C1 to C18 At least one or more of ester monomers, (b) at least one or more of hydroxyl-containing copolymerizable monomers, and (c) at least one or more of polyalkylene glycol chain-containing mono(meth)acrylate monomers, The glass transition temperature of the first acrylic polymer and the second acrylic polymer is 0°C or lower, the crosslinking agent is (D) a trifunctional or higher isocyanate compound, and the antistatic agent is (G) having a fluorine atom An ionic compound having a melting point of 25 to 50°C composed of a cation and an anion having an anion number of F7 or more, the adhesive composition further comprising (E) a crosslinking retarder and (F) a crosslinking catalyst other than a tin compound other than crosslinking catalysts. The adhesive composition according to claim 1, which is an adhesive composition for a surface protection film attached to a protective layer of a polarizer of a polarizer, wherein the protection of the polarizer of the polarizer is The layer is one selected from the group consisting of TAC film, PMMA film, and PET film, and the surface treatment implemented on the surface of the protective layer of the polarizer of the polarizer is selected from untreated, AG treatment, One of the group consisting of LR processing, AR processing, AG-LR processing, and AG-AR processing. The adhesive composition according to claim 1 or 2, wherein the anion of the ionic compound contains C ₆ F ₅ (CF ₂ ) _n COO ⁻ , C ₆ F ₅ (CF ₂ ) _n SO ₃ ^- , C ₆ F ₅ (CF ₂ ) _n O ^- , C ₆ F ₅ O(CF ₂ ) _n SO ₃ ^- , (C ₆ F ₅ CO) ₂ N ^- , (C ₆ F ₅ CO) ₃ C ^- , (C ₆ F ₅ SO ₂ ) ₂ N ^- , (C ₆ F ₅ SO ₂ ) ₃ C ^- , (C ₆ F ₅ OSO ₂ ) ₂ N ^- , (C ₆ F ₅ OSO ₂ ) ₃ C ^- , (C 6 F 5 OSO 2 ) 2 N - At least one or more of the group consisting of ₆ F ₅ ) ₄ B ^- and CF ₃ (CF ₂ ) ₃ SO ₃ ^- is used as an anion in an amount of 0.01 to 15 parts by weight relative to 100 parts by weight of the first acrylic polymer The proportion of containing the ionic compound. The adhesive composition according to claim 1 or 2, wherein the cation of the ionic compound is selected from the group consisting of pyridinium, imidazolium, phosphonium, peronium, pyrrolidinium, guanidinium, ammonium, isuronium, One of the group consisting of thiouronium, pyridinium, pyrazolium, methyl onium, lithium, and morpholinium, with respect to 100 parts by weight of the first acrylic polymer, in an amount of 0.01 to 15 parts by weight proportions containing the ionic compound. The adhesive composition according to claim 1 or 2, wherein the adhesive layer formed by crosslinking the adhesive composition has a surface resistivity of 1.0×10 ⁺¹² Ω/□ or less, and the adhesive The peeling electrostatic voltage of the adhesive layer to the low-refractive-index layer formed on the adhered surface using the composition for forming a low-refractive-index layer containing a fluorine compound is in the range of -0.3~+0.3kV, so that the adhesive composition The adhesive force of the cross-linked adhesive layer to the polarizer is 0.04~0.2N/25mm when the low-speed peeling speed is 0.3m/min, and the adhesive force when the high-speed peeling speed is 30m/min is 2.0N /25mm or less. The adhesive composition according to claim 1 or 2, wherein the (B) hydroxyl group-containing copolymerizable monomer of the first acrylic polymer, and the (B) of the second acrylic polymer b) The hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, (meth)acrylic acid At least one selected from the group of compounds consisting of 2-hydroxyethyl ester, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide One or more, the (C) carboxyl-containing copolymerizable monomer is selected from (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)propylene Ethyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2- (Meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acrylonitrile At least one or more of the compound group consisting of oxyethyltetrahydrophthalic acid. The adhesive composition according to claim 1 or 2, wherein the (E) crosslinking retarder is a compound of keto-enol tautomer, relative to 100 parts by weight of the first acrylic acid The polymer contains the (E) cross-linking retarder in a proportion of 0.1 to 300 parts by weight, and the (F) cross-linking catalyst is selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds. The at least one metal chelate compound of 100 parts by weight of the first acrylic polymer contains the (F) cross-linking catalyst in a ratio of 0.001 to 0.5 parts by weight, the (E)/the (F) The weight ratio of 80~1000. The adhesive composition according to claim 1 or 2, wherein, with respect to 100 parts by weight of the first acrylic polymer, the adhesive composition contains an HLB value in a ratio of 0.01 to 0.5 parts by weight Polyether-modified siloxane compounds with a weight-average molecular weight of 6 to 12 and below 10,000. The adhesive composition according to claim 1 or 2, wherein, with respect to 100 parts by weight of the first acrylic polymer, the adhesive composition contains the second acrylic polymer in a ratio of 0.1 to 5.0 parts by weight An acrylic polymer, the second acrylic polymer is a copolymer having a weight average molecular weight of more than 300,000 and 1 million or less, which is formed by a (methyl) group having a carbon number of C1 to C18 relative to the (a) alkyl group At least one or more of acrylate monomers in total of 100 parts by weight, (b) at least one or more of hydroxyl group-containing copolymerizable monomers in total of 2.0 to 12.0 parts by weight and (c) polyalkylene glycol chain-containing mono( At least one or more of the meth)acrylate monomers are copolymerized in a total of 1 to 30 parts by weight, and the first acrylic polymer has a (methyl) carbon number of C1 to C18 with respect to the (A) alkyl group. At least one or more of the acrylate monomers are 100 parts by weight in total, (B) parts by weight of the total of at least one or more of the hydroxyl group-containing copolymerizable monomers β1=100×(B)/(A), the second acrylic acid (a) At least one of (meth)acrylate monomers having a carbon number of C1 to C18 relative to the alkyl group of the polymer is 100 parts by weight in total, (b) at least one of hydroxyl-containing copolymerizable monomers The above total parts by weight β2=100×(b)/(a), and the ratio K=β2/β1 of the β1 to the β2 is in the range of 1.0 to 2.0. The adhesive composition according to claim 1 or 2, wherein the second acrylic polymer is a copolymer having a weight average molecular weight of more than 300,000 and less than 800,000, and the polyalkylene glycol chain-containing In the mono(meth)acrylate monomers, the average number of repeating units of the alkyleneoxy groups constituting the polyalkylene glycol chain is 3 to 14, and the polyalkylene glycol chain-containing mono(methyl) The diester component in the acrylate monomer is 0.2% or less, and in 100 parts by weight of the second acrylic polymer, in a proportion of 1 to 50 parts by weight selected from polyalkylene glycol mono(methyl) ) acrylate, methoxypolyalkylene glycol (meth)acrylate, at least one of the group consisting of ethoxypolyalkylene glycol (meth)acrylate, as the polyalkylene Mono(meth)acrylate monomers of alkyl glycol chains. An adhesive film, characterized in that an adhesive layer obtained by cross-linking the adhesive composition according to any one of claims 1 to 10 of the scope of application is laminated on one side of a resin film. A surface protection film using the adhesive film described in claim 11 of the scope of application. A surface protective film for polarizers using the adhesive film described in claim 11. An optical film with an adhesive layer, which is laminated on at least one side of the optical film with an adhesive formed by cross-linking the adhesive composition as described in any one of the 1st to 10th items of the patent application scope. layer. The adhesive film according to claim 11, wherein antistatic treatment and antifouling treatment are performed on one side of the resin film, that is, the side opposite to the side on which the adhesive layer is formed.