JP2013199544A - Adhesive composition, adhesive, and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition excellent in reworkability, wherein the composition can be peeled off an adherend attached once, without making an adhesive remain on the adherend; and to provide the adhesive and an adhesive sheet.SOLUTION: An adhesive composition contains: a first acrylic polymer (A) that has a weight-average molecular weight of 500,000-1,000,000 and further has a reactive functional group; and a second acrylic polymer (B) that has a weight average molecular weight of 9,000-40,000 and does not have the reactive functional group. An adhesive is made by crosslinking the adhesive composition.

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive (a material obtained by crosslinking a pressure-sensitive adhesive composition), and a pressure-sensitive adhesive sheet used for optical display panels and the like.

  In recent years, adhesive films have been applied to industrial products using glass substrates such as front plates and modules of display devices to impart various characteristics. For example, in a plasma display panel (PDP), an optical filter is used on the front surface for the purpose of suppressing leakage of near infrared rays, neon light, electromagnetic waves and the like generated from the PDP to the outside. This optical filter normally has a configuration in which a glass substrate is used as a support and an adhesive film having a performance capable of achieving the above-described object is laminated.

  When the adhesive film is attached to the front plate or the module, the adhesive film needs to be peeled off and a new adhesive film attached again when the adhesive film is attached to the front plate or the module. However, when adhesive residue is left on the adherend when the adhesive film is peeled off, the front plate and the module cannot be reused (reworked). In order to avoid this problem, the adhesive film is required to have no adhesive residue at the time of peeling.

  By the way, recently, a laminate in which an adhesive layer is sandwiched between two types of release films (light release type release film and heavy release type release film) having different release forces is prepared, and one release film (light release type release film). In many cases, the pressure-sensitive adhesive layer exposed by peeling off the film is bonded to a substrate to produce a pressure-sensitive adhesive film (Patent Document 1).

Japanese Patent Laid-Open No. 2003-177241

  However, when the laminate as described above is used, the anchoring effect of the adhesive on the base material is small compared to the case where the adhesive is directly applied to the base material or the transfer coating is applied. The base material adhesion of the agent is low.

  In addition, when a glass substrate is used as an adherend, a silane coupling agent is often added to the adhesive in consideration of floating and peeling under high temperature and high humidity conditions. Thereby, adhesiveness with an adhesive layer and the glass substrate which is a to-be-adhered body will improve with pasting time.

  For the above reasons, in particular, an adhesive film obtained by using the laminate as described above has a problem that an adhesive residue tends to occur when it is peeled off after being applied to a glass substrate for a long time.

  The present invention has been made in view of such a situation, and can be peeled off from the adherend without leaving the adhesive on the adherend once adhered, and has excellent reworkability. It aims at providing a composition, an adhesive, and an adhesive sheet.

  In order to achieve the above object, first, the present invention has a weight average molecular weight of 500,000 to 1,000,000, a first acrylic polymer (A) having a reactive functional group, and a weight average molecular weight of 9,000. The pressure-sensitive adhesive composition is characterized by containing a second acrylic polymer (B) having a reactive functional group of ˜40,000 (Invention 1).

  The pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to the above invention (Invention 1) can be applied to the adherend without leaving the pressure-sensitive adhesive on the adherend even after being stuck to the adherend (especially glass) for a long time. It can be peeled off from the body and has excellent reworkability.

  In the said invention (invention 1), it is preferable that the reactive functional group which the said 1st acrylic polymer (A) has is a hydroxyl group (invention 2).

  In the said invention (invention 1 and 2), it is preferable that the said 1st acrylic polymer (A) contains 0.5-10 mass% of reactive functional group containing monomers as a structural component (invention 3).

  In the said invention (invention 1-3), content of the said 2nd acrylic polymer (B) is 0.1-50 mass parts with respect to 100 mass parts of said 1st acrylic polymers (A). It is preferable (Invention 4).

  The pressure-sensitive adhesive composition according to the above inventions (Inventions 1 to 4) preferably further contains a crosslinking agent (Invention 5).

  In the said invention (invention 5), it is preferable that the said crosslinking agent is an isocyanate type crosslinking agent (invention 6).

  The pressure-sensitive adhesive composition according to the above invention (Inventions 1 to 6) preferably further contains a silane coupling agent (Invention 7).

  In the said invention (invention 7), it is preferable that content of the said silane coupling agent is 0.001-1 mass part with respect to 100 mass parts of said 1st acrylic polymers (A) (invention 8). ).

  The pressure-sensitive adhesive composition according to the above invention (Invention 1 to 8) is preferably for an optical display panel (Invention 9).

  2ndly this invention provides the adhesive formed by bridge | crosslinking the said adhesive composition (invention 1-9) (invention 10).

  Thirdly, the present invention is an adhesive sheet comprising two release sheets and an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. A pressure-sensitive adhesive sheet, characterized in that the layer is composed of the pressure-sensitive adhesive (Invention 10) (Invention 11).

  According to the present invention, even after affixing to an adherend (especially glass) for a long time, it can be peeled off from the adherend without leaving an adhesive on the adherend, and has excellent reworkability. can get. Moreover, the adhesive sheet which concerns on this invention exhibits said outstanding effect also as a structure which clamps an adhesive layer with two peeling sheets.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to this embodiment has a weight average molecular weight of 500,000 to 1,000,000, a first acrylic polymer (A) having a reactive functional group, and a weight average molecular weight of 9000 to 40,000. Yes, containing a second acrylic polymer (B) having no reactive functional group, preferably further containing a crosslinking agent (C) and a silane coupling agent (D).

  In the pressure-sensitive adhesive obtained from such a pressure-sensitive adhesive composition, the high molecular weight polymer (A) forms a three-dimensional network structure by chemical crosslinking, and a plurality of low molecular weight polymers (B) are formed in the three-dimensional network structure. Enters and shows moderate tackiness (adhesiveness to the substrate). The adhesive thus obtained can be peeled off from the adherend without leaving the adhesive on the adherend even after being stuck to the adherend (especially glass) for a long time. Excellent reworkability of adherend. This pressure-sensitive adhesive also exhibits the above-described excellent effect even as a pressure-sensitive adhesive sheet having a structure in which the pressure-sensitive adhesive layer is sandwiched between two release sheets.

  Note that the second acrylic polymer (B) having a low molecular weight does not participate in the crosslinking system because it does not have a reactive functional group, and thus has a high degree of freedom. Improved adhesion.

  The first acrylic polymer (A) is a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, a monomer having a reactive functional group (reactive functional group-containing monomer), and optionally used. Preferred is a copolymer with other monomer having no reactive functional group. In addition, in this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

  In addition, the second acrylic polymer (B) is a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms and another monomer having no reactive functional group used as desired. Coalescence is preferred.

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n- (meth) acrylate Examples include decyl, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  On the other hand, the reactive functional group-containing monomer includes a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), and a monomer having an amino group in the molecule (amino group). Containing monomer) and the like. Among them, a hydroxyl group-containing monomer is preferable. In the case of a carboxyl group-containing monomer, when the silane coupling agent (D) is used, the presence of the carboxyl group makes the silane coupling agent (D) more reactive and adhesion to the glass as the adherend. Tends to be improved, and as a result, adhesive residue may be easily generated. On the other hand, in the case of a hydroxyl group-containing monomer, since the hydroxyl group has little contribution to the reaction with the silane coupling agent (D), the adhesive residue as described above hardly occurs.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. These may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  Other monomers having no reactive functional group include, for example, (meth) acrylate esters having an aliphatic ring such as cyclohexyl (meth) acrylate, and aromatic rings such as phenyl (meth) acrylate (meth) Non-crosslinkable acrylamide such as acrylic ester, acrylamide, methacrylamide, etc. Non-crosslinkable tertiary such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Examples thereof include (meth) acrylic acid ester having an amino group, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

  Here, the first acrylic polymer (A) preferably contains 0.5 to 10% by mass of the reactive functional group-containing monomer, and particularly preferably 1 to 5% by mass. By containing the reactive functional group-containing monomer in the above range, the degree of cross-linking of the first acrylic polymer (A) is preferable, and in the combination with the second acrylic polymer (B), the above-described effects are obtained. It will be easy to demonstrate. On the other hand, when the amount of the reactive functional group-containing monomer is less than 0.5% by mass, the first acrylic polymer (A) is not sufficiently cross-linked, which may result in poor durability. On the other hand, when the amount of the reactive functional group-containing monomer exceeds 10% by mass, the first acrylic polymer (A) is excessively cross-linked, which may reduce bonding suitability to the adherend. .

  The form of copolymerization of the first acrylic polymer (A) and the second acrylic polymer (B) is not particularly limited, and may be any of random, block, and graft copolymers.

  The weight average molecular weight of the first acrylic polymer (A) is 500,000 to 1,000,000, preferably 600,000 to 900,000, particularly preferably 700,000 to 900,000. That is, the first acrylic polymer (A) is a high molecular weight polymer component. In addition, the mass mean molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method. When the weight average molecular weight of the first acrylic polymer (A) is less than 500,000, the cohesive force is too low and it is difficult to form the pressure-sensitive adhesive layer. Moreover, when the weight average molecular weight of a 1st acrylic polymer (A) exceeds 1 million, an adhesive will become hard too much and the adhesiveness with respect to a to-be-adhered body and a base material will worsen.

  On the other hand, the weight average molecular weight of the second acrylic polymer (B) is 9000 to 40,000, preferably 10,000 to 30,000, and particularly preferably 10,000 to 20,000. That is, the second acrylic polymer (B) is a low molecular weight polymer component. When the weight average molecular weight of the second acrylic polymer (B) is less than 9,000, the polymer (B) may bleed out from the adhesive or volatilize during drying to form an adhesive layer. Occurs. Further, when the weight average molecular weight of the second acrylic polymer (B) exceeds 40,000, the compatibility with the first acrylic polymer (A) is deteriorated, haze is increased, and adhesive residue is further generated. .

  In this embodiment, the 1st acrylic polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type. Similarly, the second acrylic polymer (B) may be used alone or in combination of two or more.

  Content of the 2nd acrylic polymer (B) in the adhesive composition which concerns on this embodiment is 0.1-50 with respect to 100 mass parts of 1st acrylic polymers (A) as solid content ratio. It is preferable that it is a mass part, and it is especially preferable that it is 5-45 mass part. When the content of the second acrylic polymer (B) is less than 0.1 parts by mass, the interaction of the polymer (B) with the base material is reduced, and the adhesion to the base material may be reduced. . On the other hand, when the content of the second acrylic polymer (B) exceeds 50 parts by mass, the compatibility with the first acrylic polymer (A) is deteriorated, the haze is increased, and an optical application such as a display panel. It may become unusable. Moreover, when the content of the second acrylic polymer (B) not involved in the crosslinking system is increased, the gel fraction of the pressure-sensitive adhesive is reduced, and an adhesive residue due to a small cohesive force is generated.

  Preferred examples of the crosslinking agent (C) include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine and the like.

  Examples of the aziridine-based crosslinking agent include diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethanetri-β-aziridinyl. Propionate, toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine, And trimethylolpropane tri-β- (2-methylaziridine) propionate.

  Metal chelate crosslinking agents include chelate compounds whose metal atoms are aluminum, zirconium, titanium, zinc, iron, tin, etc., but aluminum chelate compounds are preferred from the viewpoint of performance. Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy Examples thereof include aluminum monostearyl acetoacetate and diisopropoxy aluminum monoisostearyl acetoacetate.

  The above crosslinking agents (C) may be used individually by 1 type, and may be used in combination of 2 or more type. Content of the crosslinking agent (C) in the adhesive composition which concerns on this embodiment is 0.1-5 mass parts with respect to 100 mass parts of 1st acrylic polymers (A) as solid content ratio. It is preferable that it is 0.5-2 mass parts especially. The content of the cross-linking agent (C) is within this range, so that the resulting pressure-sensitive adhesive can be made excellent in durability, and can effectively prevent adhesive residue and has better reworkability. Can be.

  The adhesive composition which concerns on this embodiment can improve the adhesiveness with respect to the glass of the adhesive which is obtained when an adherend is glass by containing a silane coupling agent (D). . Such a pressure-sensitive adhesive is excellent in adhesion durability, and does not cause defects such as floating and peeling even under high temperature and high humidity conditions.

  The silane coupling agent (D) is an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the pressure-sensitive adhesive component, and having light transmittance, for example, substantially A transparent one is preferred.

  Content of the silane coupling agent (D) in the adhesive composition which concerns on this embodiment is 0.001-1 mass part with respect to 100 mass parts of 1st acrylic polymers (A) as solid content ratio. It is preferable that it is 0.005-0.05 mass part especially.

  Specific examples of the silane coupling agent (D) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- Examples include amino group-containing silicon compounds such as (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane. These may be used individually by 1 type and may be used in combination of 2 or more type.

  In the above-mentioned adhesive composition, various additives usually used for acrylic adhesives, for example, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, antistatic agents, are optionally used. An agent, a refractive index adjusting agent, etc. can be added.

[Adhesive]
The pressure-sensitive adhesive according to this embodiment is obtained by crosslinking the pressure-sensitive adhesive composition. What is necessary is just to heat-process in order to bridge | crosslink the said adhesive composition. In addition, this heat processing can also serve as the drying process at the time of volatilizing the dilution solvent etc. of an adhesive composition.

  When performing heat processing, it is preferable that heating temperature is 70-150 degreeC, and it is especially preferable that it is 90-110 degreeC. The heating time is preferably 30 seconds to 5 minutes, particularly preferably 1 minute to 3 minutes.

  When the pressure-sensitive adhesive composition contains a crosslinking agent (C), the above heat treatment starts a crosslinking reaction between the first acrylic polymer (A) having a reactive functional group and the crosslinking agent (C). proceed. Thereby, the shape as an adhesive layer will be maintained favorable. Furthermore, it is particularly preferable to provide a curing period of about 1 to 2 weeks at room temperature (for example, 23 ° C., 50% RH) after the heat treatment.

  The haze value of the obtained pressure-sensitive adhesive is preferably less than 2%, particularly preferably 1% or less. It becomes a preferable adhesive for optical uses, such as a display panel, because a haze value is this value.

  The above-described pressure-sensitive adhesive is suitable for optical applications, and can be preferably used for adhesion to a front plate or a module used in an optical display panel such as a plasma display panel, in particular, a glass substrate and a desired film. It can be preferably used for adhesion to a substrate (for example, a polyethylene terephthalate (PET) film substrate on which a layer having a desired function is formed).

  According to the pressure-sensitive adhesive according to the present embodiment, it can be peeled off from the adherend without leaving the pressure-sensitive adhesive on the adherend even after sticking to the adherend (particularly glass) for a long time. Excellent reworkability. Moreover, when the said adhesive contains a silane coupling agent (D), it is excellent also in adhesive durability especially, and even when it puts on high temperature high humidity conditions, defects, such as a float and peeling, do not generate | occur | produce. Furthermore, the said adhesive exhibits said outstanding effect also as an adhesive sheet of the structure which clamps an adhesive layer with two peeling sheets.

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to an embodiment of the present invention includes two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. It is comprised from the adhesive layer 11 pinched | interposed into peeling sheet 12a, 12b. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

  In the pressure-sensitive adhesive sheet 1, the pressure-sensitive adhesive layer 11 is made of a pressure-sensitive adhesive formed by crosslinking the above-described pressure-sensitive adhesive composition.

  The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined according to the purpose of use of the pressure-sensitive adhesive sheet 1, but is usually in the range of 5 to 100 μm, preferably 10 to 60 μm. For example, an optical member, particularly an optical display panel or the like In the case of a pressure-sensitive adhesive layer used for adhesion to a front plate or a module, it is preferably 10 to 50 μm, particularly preferably 10 to 30 μm.

  Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film, a liquid crystal polymer film, or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 11) of the release sheets 12a and 12b is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents.

  One of the release sheets 12a and 12b (for example, the release sheet 12a) is preferably a light release type release sheet, and the other (for example, the release sheet 12b) is preferably a heavy release type release sheet. Thus, in order to provide a peeling force difference between the release sheets 12a and 12b, it can be achieved by changing the type of the release agent, performing a release process on one side, and not performing a release process on the other side.

  Although there is no restriction | limiting in particular about the thickness of release sheet 12a, 12b, Usually, it is about 20-150 micrometers.

  In order to produce the pressure-sensitive adhesive sheet 1, a coating solution containing the pressure-sensitive adhesive composition and, if desired, a solvent is applied to the release surface of one release sheet 12 a (or 12 b), and the heat treatment described above is performed. After forming the pressure-sensitive adhesive layer 11, the release surface of the other release sheet 12 b (or 12 a) is superimposed on the pressure-sensitive adhesive layer 11.

  As a method for applying the coating solution, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.

  Examples of the solvent include alcohols such as methanol, ethanol, propanol, butanol and 1-methoxy-2-propanol; aliphatic hydrocarbons such as hexane, heptane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; Halogenated hydrocarbons such as ethylene chloride; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolv solvents such as ethyl cellosolve are used. These solvents can be used alone or in combination of two or more.

  The pressure-sensitive adhesive sheet 1 according to the present embodiment is suitable for optical applications, and can be preferably used for adhesion to a front plate or a module used for an optical display panel such as a plasma display panel. For example, when used for adhesion between a glass substrate and a desired film base (for example, a PET film base on which a layer having a desired function is formed), one release sheet 12a (light release type) from the pressure-sensitive adhesive sheet 1 is used. The pressure-sensitive adhesive layer 11 exposed by peeling off and the film base material are bonded together, and then the pressure-sensitive adhesive layer 11 exposed by peeling off the other release sheet 12b (heavy release type) and the glass substrate are bonded together. To do.

  According to the pressure-sensitive adhesive sheet 1 according to this embodiment, even after the pressure-sensitive adhesive layer 11 is bonded to an adherend (particularly a glass substrate) for a long time, the pressure-sensitive adhesive is not dropped from the film base material, The pressure-sensitive adhesive layer 11 can be peeled off from the adherend without leaving the pressure-sensitive adhesive on the adherend, and the reworkability is excellent. Further, when the pressure-sensitive adhesive layer 11 contains a silane coupling agent (D), it is particularly excellent in adhesion durability, and even when it is placed under a high temperature and high humidity condition, defects such as floating and peeling do not occur.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Production Example 1] (Preparation of first acrylic polymer (A1))
Butyl acrylate (BA), methyl methacrylate (ММA), 2-hydroxyethyl acrylate (2HEA), and methacrylamide (МAAm) are BA / ММA / 2HEA / МAAm = 86.5 / 10/3 / Copolymerized at a mass ratio of 0.5, diluted with a mixed solvent of methyl ethyl ketone and toluene, and a solution of the first acrylic polymer (A1) having a weight average molecular weight of about 800,000 (solid content: 40.7 mass%) Got.

[Production Example 2] (Preparation of first acrylic polymer (A2))
Butyl acrylate (BA), methyl methacrylate (ММA), 2-hydroxyethyl acrylate (2HEA), and acrylic acid (AA) are BA / ММA / 2HEA / AA = 86/10/3/1. The copolymer was copolymerized at a mass ratio and diluted with a mixed solvent of methyl ethyl ketone and toluene to obtain a solution (solid content: 40.0 mass%) of the first acrylic polymer (A2) having a weight average molecular weight of about 800,000.

[Production Example 3] (Preparation of second acrylic polymer (B1))
Butyl acrylate (BA) and methyl methacrylate (ММA) are copolymerized at a mass ratio of BA / ММA = 50/50, diluted with a mixed solvent of methyl ethyl ketone and toluene, and the weight average molecular weight is about 15,000. Of the second acrylic polymer (B1) was obtained (solid content: 14.7% by mass).

[Production Example 4] (Preparation of second acrylic polymer (B2))
Butyl acrylate (BA) and methyl methacrylate (ММA) are copolymerized at a mass ratio of BA / ММA = 50/50, diluted with a mixed solvent of methyl ethyl ketone and toluene, and the weight average molecular weight is about 30,000. A solution of the acrylic polymer (B2) 2 (solid content: 16.6% by mass) was obtained.

[Production Example 5] (Preparation of second acrylic polymer (B3))
Butyl acrylate (BA) and methyl methacrylate (ММA) are copolymerized at a mass ratio of BA / ММA = 50/50 and diluted with a mixed solvent of methyl ethyl ketone and toluene to give a weight average molecular weight of about 50,000. 2 was obtained (solid content: 48.0% by mass) of the acrylic polymer (B3).

Here, the above-mentioned weight average molecular weight is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Example 1]
The first acrylic polymer (A1) obtained in Production Example 1, the second acrylic polymer (B1) obtained in Production Example 3, and a xylene diisocyanate-based crosslinking agent (TD- 75, solid content: 75% by mass) and a silane coupling agent composed of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403, solid content: 100% by mass) are shown in Table 1. It mixed by the composition (1) and the coating liquid of the adhesive composition was prepared. In addition, the mixing amount in Table 1 represents the solid content ratio.

[Examples 2 to 9, Comparative Examples 1 to 4]
A coating solution for the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the types and blending ratios of the components constituting the pressure-sensitive adhesive composition were changed as shown in Table 1.

[Test Example 1] (Compatibility evaluation)
The appearance of the coating solution of the adhesive composition prepared in Examples and Comparative Examples was visually observed to evaluate the compatibility. If it is colorless and transparent, the compatibility is good, and if it is cloudy, it can be judged that the compatibility is poor. The results are shown in Table 2.

[Test Example 2] (Haze value measurement)
Using the knife coater, the coating solution of the adhesive composition prepared in Examples and Comparative Examples was applied to the release agent-treated surface of a heavy release type release film (Lintec Corporation, SP-PET38T103-1, thickness: 38 μm). It apply | coated so that the thickness after drying might be set to 25 micrometers, It was made to dry at 90 degreeC for 60 second, and the adhesive layer was formed. Next, a release-treated surface of a light-release type release film (manufactured by Lintec, SP-PET382120, thickness: 38 μm) was bonded to the adhesive layer.

  After aging for 1 week, the light release type release film was peeled off, and the exposed pressure-sensitive adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), which was used as a sample for haze value measurement. About this sample, the haze value (%) was measured according to JISK7136 using a haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH5000) as the zero point of soda lime glass. The results are shown in Table 2.

[Test Example 3] (Reworkability evaluation)
Using the knife coater, the coating solution of the adhesive composition prepared in Examples and Comparative Examples was applied to the release agent-treated surface of a heavy release type release film (Lintec Corporation, SP-PET38T103-1, thickness: 38 μm). It apply | coated so that the thickness after drying might be set to 25 micrometers, It was made to dry at 90 degreeC for 60 second, and the adhesive layer was formed. Next, a release-treated surface of a light-release type release film (manufactured by Lintec, SP-PET382120, thickness: 38 μm) was bonded to the adhesive layer.

  After aging for 1 week, the light release type release film was peeled off, and the exposed adhesive layer was bonded to a PET film substrate (PET100A4300, thickness: 100 μm, manufactured by Toyobo Co., Ltd.). The laminated body which consists of an agent layer / PET film base material (= heavy peeling type peeling film / PET film base material with an adhesive layer) was obtained.

  After the laminate was cut out to 25 mm × 250 mm and the heavy release type release film was peeled off, the exposed adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.) as an adherend with a 2 kg rubber roller, This was used as a sample for reworkability evaluation.

After leaving the obtained sample in a standard environment (23 ° C., 50% RH) for 1 day, 4 days or 7 days, using a tensile tester (Orientec Corp., Tensilon), peeling speed of 300 mm / Min, with the condition of a peeling angle of 180 °, the PET film substrate with the pressure-sensitive adhesive layer is peeled off from the adherend, and the remaining state of the pressure-sensitive adhesive (glue remaining state) on the adherend surface and the surface of the exposed pressure-sensitive adhesive layer The state of (adhesive surface) was evaluated. The evaluation criteria are as follows. The results are shown in Table 2.
[Evaluation criteria]
○: No adhesive residue and no rough surface on the adhesive surface (good reworkability)
Δ: No adhesive residue, but rough surface on peeled surface (good reworkability)
×: Residue remaining (poor reworkability)

[Test Example 4] (Heat and humidity resistance evaluation)
The sample prepared by the above reworkability evaluation was left for 1000 hours under high temperature and high humidity (60 ° C./95% RH), and then the presence or absence of peeling / floating of the PET film substrate with the adhesive layer was visually evaluated. . The results are shown in Table 2.
[Evaluation criteria]
○: No floating / peeling ×: Floating / peeling

  As is clear from Table 2, the pressure-sensitive adhesives prepared in the examples are excellent in compatibility, have a low haze value, are excellent in reworkability, and are excellent in durability under high temperature and high humidity.

  The pressure-sensitive adhesive composition, pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention are particularly suitable for adhesion between a glass substrate and a film substrate in an optical display panel or the like.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet

Claims (11)

A first acrylic polymer (A) having a weight average molecular weight of 500,000 to 1,000,000 and having a reactive functional group;
A pressure-sensitive adhesive composition comprising a second acrylic polymer (B) having a weight average molecular weight of 9000 to 40,000 and having no reactive functional group.   The pressure-sensitive adhesive composition according to claim 1, wherein the reactive functional group of the first acrylic polymer (A) is a hydroxyl group.   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the first acrylic polymer (A) contains 0.5 to 10% by mass of a reactive functional group-containing monomer as a constituent component.   The content of the second acrylic polymer (B) is 0.1 to 50 parts by mass with respect to 100 parts by mass of the first acrylic polymer (A). 4. The adhesive composition according to any one of 3.   The pressure-sensitive adhesive composition according to claim 1, further comprising a cross-linking agent.   The pressure-sensitive adhesive composition according to claim 5, wherein the crosslinking agent is an isocyanate-based crosslinking agent.   The pressure-sensitive adhesive composition according to claim 1, further comprising a silane coupling agent.   The pressure-sensitive adhesive composition according to claim 7, wherein the content of the silane coupling agent is 0.001 to 1 part by mass with respect to 100 parts by mass of the first acrylic polymer (A). object.   It is an object for optical display panels, The adhesive composition as described in any one of Claims 1-8.   The adhesive which bridge | crosslinks the adhesive composition as described in any one of Claims 1-9. Two release sheets,
An adhesive sheet comprising an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets,
The said adhesive layer consists of an adhesive of Claim 10, The adhesive sheet characterized by the above-mentioned.

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