KR20070075340A - Adhesive compositions and adhesive sheets comprising the same - Google Patents

Abstract

Provided are an adhesive composition, which has an excellent releasing property when applied to optical films and is superior in transparency and coating property, and adhesive sheets comprising the same. The adhesive composition contains (A) an acrylic polymer comprising a C4-12 alkylester of (meth)acrylic acid as a main monomer and having a weight average molecular weight of 50x10^4 to 90x10^4 and (B) oligomer which is obtained by copolymerizing at least (b1) (meth)acrylate with (b2) an amide compound and has a weight average molecular weight of 3000-20000, with the proviso that the (meth)acrylate(b1) is a (meth)acrylate of which a homopolymer has a glass transition temperature of 60-190°C, and the amide compound(b2) has a polymerizable functional group and is a compound represented by a formula 1 of R^1-CO-NR^2R^3. In the formula 1, each of R^1 to R^3 is independently a hydrogen atom or monovalent organic group, or any two of R1 to R3 are bound to each other to form a ring structure and the remaining one is a hydrogen atom or monovalent organic group.

Description

Adhesive Compositions and Adhesive Sheets Comprising the Same

Japanese Patent Laid-Open No. 17856767

Japanese Patent No. 3516035

Japanese Patent Laid-Open No. 2001-89731

The present invention relates to an adhesive composition and an adhesive sheet comprising the same. Specifically, the present invention relates to an acrylic pressure-sensitive pressure-sensitive adhesive composition for adhering to a plastic film such as polycarbonate, acrylic resin plate or PET, glass plate, etc., and the present invention further comprises an adhesive layer comprising the composition. It relates to an adhesive sheet to be made.

In recent years, the use of a flat panel display (FPD) is remarkable. In manufacture of FPD, the process of laminating | stacking an optical film which has various functions, etc. via an adhesive is essential.

According to the disclosure of Japanese Patent Application Laid-Open No. Hei 1785785 (JP01-178567A), the pressure-sensitive adhesive containing an acrylic polymer whose molecular weight is appropriately adjusted improves adhesiveness, transparency, foaming and peeling resistance. Examples of other pressure-sensitive adhesives include various pressure-sensitive adhesives such as tackifiers, etc. to improve foaming and peeling properties, thereby improving adhesiveness to plastic substrates, and polymers obtained by copolymerizing monomers for increasing adhesion. Pressure-sensitive adhesives and the like.

According to the disclosure of Japanese Patent No. 3516035 (JP3516035 B), a pressure-sensitive adhesive containing a polymer obtained by copolymerizing a carboxyl group-containing monomer and an oligomer formed by copolymerizing an amino group-containing monomer has excellent adhesiveness and foaming resistance at room temperature and high temperature. Indicates.

According to the disclosure of JP 2001-89731 A (JP2001-89731 A), (A) (meth) acrylic acid ester homopolymer or copolymer with a weight average molecular weight of 500,000 to 2.5 million, and (B) weight average molecular weight 5000 To 500,000 (meth) acrylic acid ester homopolymer or copolymer in a weight ratio of 100: 1 to 100: 50, and having a nitrogen-containing functional group in any one of (A) and (B). This is provided.

In recent years, what has high re-peelability (rework) property is calculated | required by an optical film. Repeelability means that peeling of the optical film which once adhered is easy. When peeling an optical film which has a problem etc. requires large force, or an adhesive remains in a base material etc., re-peelability becomes low.

According to a new discovery by the inventors, a large force is required to peel off the optical film using the pressure-sensitive adhesive disclosed in Japanese Patent No. 3516035, which is concerned about damaging the substrate or the like. According to a further discovery of the present inventors, it is difficult to say that the pressure-sensitive adhesive disclosed in Japanese Patent Laid-Open No. 2001-89731 shows excellent re-peelability.

An object of the present invention is to provide a pressure-sensitive adhesive composition excellent in re-peelability and at the same time excellent in transparency and coating property when applied to an optical film and a pressure-sensitive adhesive sheet containing the same.

Therefore, this inventor earnestly examined in order to achieve the said subject. As a result, the inventors discovered that the above problems can be achieved by containing both a specific polymer and a specific oligomer, and completed the following invention.

(1) The pressure-sensitive adhesive composition containing the following polymer A and oligomer B.

Polymer A: The acrylic polymer of the weight average molecular weight 50 * 10 <^4> -90 * 10 <^{4> which} has a C4-C12 alkyl ester of (meth) acrylic acid as a main monomer,

Oligomer B: The oligomer of the weight average molecular weights 3000-20000 formed by copolymerizing the following (meth) acrylate b1 and the amide compound b2 at least.

[Wherein, (meth) acrylate b1 is a (meth) acrylate having a glass transition temperature of 60 ° C to 190 ° C when used as a homopolymer, and the amide compound b2 has a polymerizable functional group and is represented by the following formula (1) being].

R ¹ -CO-NR ² R ³

Wherein R ¹ to R ³ are each independently a hydrogen atom or a monovalent organic group, or R ¹ to R ³ Any two of them combine with each other to form a ring structure, and the remaining one is a hydrogen atom or a monovalent organic group.

(2) The pressure-sensitive adhesive composition according to the above (1), wherein the polymerizable functional group of the amide compound b2 is an alkenyl group.

(3) In the above (1), R ¹ is an alkenyl group having 2 to 4 carbon atoms, R ² and R ³ are each independently an alkyl group having 1 to 4 carbon atoms, or are bonded to each other to form a 4 to 8 membered ring structure Pressure-sensitive adhesive composition.

(4) The pressure-sensitive adhesive composition of (1), wherein R ¹ and R ² are bonded to each other to form a 4 to 8 membered ring structure, and R ³ is an alkenyl group having 2 to 4 carbon atoms.

(5) The pressure-sensitive adhesive composition of (1), wherein the amide compound b2 is at least one of acryloyl morpholine, N-vinylpyrrolidone, dialkylacrylamide, and maleimide.

(6) The pressure-sensitive adhesive composition according to any one of (1) to (5), wherein (meth) acrylate b1 is an alkyl ester having 1 to 4 carbon atoms of methacrylic acid.

(7) The pressure-sensitive adhesive composition according to any one of (1) to (6), containing 100 parts by weight of polymer A and 5 to 35 parts by weight of oligomer B.

(8) The pressure-sensitive adhesive composition according to any one of (1) to (7), further comprising 0.01 to 5 parts by weight of a crosslinking agent containing a polyfunctional epoxy compound, based on 100 parts by weight of the polymer A.

(9) The adhesive sheet provided with the adhesive layer containing the adhesive composition in any one of said (1)-(8).

The pressure-sensitive adhesive composition of the present invention exhibits excellent re-peelability when used for bonding an optical film, particularly a polyethylene terephthalate (PET) film, to an optical substrate such as glass, and at the same time, shows excellent transparency and coatability.

Although the mechanism showing excellent re-peelability is not clear, the oligomer B formed by copolymerizing a high Tg (meth) acrylate b1 and a monomer b2 of a specific chemical structure improves the adhesion to the optical film and at the same time, such as glass It is interpreted as achieving the exquisite balance that the adhesive force to a board | substrate does not rise too much.

The pressure-sensitive adhesive composition of the present invention contains polymer A and oligomer B.

<Polymer A>

Polymer A is an acrylic polymer having a weight average molecular weight of 50 × 10 ⁴ to 90 × 10 ⁴ , and the main monomer is an alkyl ester having 4 to 12 carbon atoms of (meth) acrylic acid.

"A C4-C12 alkyl ester of (meth) acrylic acid" means a C4-C12 alkyl group of the said alkyl ester, and n-butyl group, isobutyl group, sec-butyl is mentioned as an example of such an alkyl group. Group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, isooctyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group, isodecyl group, Undecyl group, dodecyl group, etc. are mentioned. As a monomer for the polymer A, the alkyl ester which has the said alkyl group can be used 1 type (s) or 2 or more types. In the whole monomer for the polymer A, the alkyl ester of 4 to 12 carbon atoms of (meth) acrylic acid is preferably 50% by weight or more, more preferably 50 to 99.5% by weight. If it is in this range, favorable peeling force and cohesion force can be obtained.

Preferably, the polymer A is copolymerized with a carboxyl group-containing compound. Specific examples of the carboxyl group-containing compound include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid and fumaric acid, and these may be used alone or in combination of two or more. In consideration of both good adhesiveness and coatability, the carboxyl group-containing compound preferably occupies 0.5 to 10% by weight, more preferably 0.5 to 5% by weight in the whole monomer for the polymer A.

The polymer A may further copolymerize monomers other than the said monomers (hereinafter "other monomers"). In the whole monomer for the polymer A, the "other monomer" preferably occupies less than 0 or 50% by weight, and more specifically, the amount can be appropriately selected according to the kind of the "other monomer". For example, when it considers expressing favorable adhesiveness, the usage-amount of a "other monomer" is determined so that the glass transition point of polymer A may be -20 degrees C or less normally.

Examples of the "other monomer" include alkyl esters having 1 to 3 carbon atoms of (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate and isopropyl (meth) acrylate; Alkyl esters having 13 to 18 carbon atoms of (meth) acrylic acid, such as tridecyl methacrylate and stearyl (meth) acrylate; Functional monomers such as hydroxyalkyl (meth) acrylate, glycerin dimethacrylate, glycidyl (meth) acrylate, methylglycidyl methacrylate, and 2-methacryloyloxyethyl isocyanate; Polyfunctional monomers such as triethylene glycol diacrylate, ethylene glycol dimethacrylate and trimethylolpropane tri (meth) acrylate; Vinyl acetate, styrene, cyclohexylmaleimide, acryloyl morpholine, N-vinylpyrrolidone, N, N-dialkylacrylamide, and the like.

The polymerization method for obtaining the polymer A is not particularly limited, and a solution polymerization method, an emulsion polymerization method, a UV polymerization method, or the like, which is a general production method of the acrylic polymer, can be appropriately selected, and solution polymerization is performed in terms of transparency, water resistance, cost, and the like. The law is preferred. In the polymerization to obtain the polymer A, the weight average molecular weight of the polymer A can be adjusted, and such means are known in the art, for example, appropriately changing the radical concentration, the polymerization temperature, the monomer concentration, and the like. Can be.

In the case of solution polymerization, an initiator is usually used, and examples of the initiator include 2,2'-azobisisobutyronitrile and 2,2'-azobis (4-methoxy-2,4-dimethylvalero. Nitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1- Azo compounds such as carbonitrile), 2,2'-azobis (2,4,4-trimethylpentane) and dimethyl 2,2'-azobis (2-methylpropionate); Benzoyl peroxide, t-butylhydroperoxide, di-t-butylperoxide, t-butylperoxybenzoate, dicumylperoxide, 1,1-bis (t-butylperoxy) 3,3,5- Oil-soluble initiators including peroxide-based compounds such as trimethylcyclohexane and 1,1-bis (t-butylperoxy) cyclododecane; and the like, and these may be used alone or in combination of two or more. You can also use together.

The amount of the initiator is not particularly limited and is usually 0.01 to 1 part by weight based on 100 parts by weight of the monomer.

The solvent for solution polymerization is not particularly limited, and general solvents such as ethyl acetate, toluene, n-butyl acetate, n-hexane, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, and the like are exemplified, and these may be used alone. In addition, you may use 2 or more types together.

The weight average molecular weight of polymer A is 50 * 10 <^4> -90 * 10 <^4> , Preferably it is 55 * 10 <^4> -85 * 10 <^4> , More preferably, it is 60 * 10 <^4> -80 * 10 <^4> . If the weight average molecular weight of a polymer is less than 50x10 <^{4>, the} adhesive obtained will not show sufficient adhesive force and cohesion force, but if it is larger than 90x10 <^4> , the obtained adhesive will show high viscosity and it is unsuitable because it is poor in coating property.

The weight average molecular weight of polymer A is measured by gel permeation chromatography (GPC) method. Specifically, the polymer to be measured is taken as a 0.2% tetrahydrofuran (THF) solution, and measured by standard polystyrene conversion using THF as eluent. Apparatus: HLC-8120GPC manufactured by TOSOH, Column: TSKgelSuperHM-H / H4000 / H3000 / H2000, Flow rate: 0.6 mL / min, Detector: RI, Column temperature 40 ° C.

<Oligomer B>

Oligomer B is a copolymer containing at least (meth) acrylate b1 and amide compound b2 as monomers.

(Meth) acrylate b1 is (meth) acrylate whose glass transition temperature at the time of using as a homopolymer is 60 degreeC-190 degreeC. Specifically, C1-C4 alkyl ester of methacrylic acid, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate; Isobornyl acrylate, cyclohexyl methacrylate, isobornyl methacrylate and the like.

The glass transition temperature is the glass transition point temperature (K) of the homopolymer, and numerical values are exemplified in "Polymer Handbook", 3rd edition, John Wiley & Sons, Inc. (1989).

In the whole monomer for oligomer B, (meth) acrylate b1 becomes like this. Preferably it occupies 50 weight% or more, More preferably, it occupies 50-97 weight%. If it exists in this range, adhesiveness to an optical film will rise and it will be compatible that adhesive force to a board | substrate, such as a glass plate, does not raise too much.

Amide compound b2 is represented by the formula (1), and has a polymerizable functional group. Therefore, R ¹ to R ^{3 in the} formula At least one of them has a polymerizable functional group. R ¹ to R ³ At least one of them is preferably an alkenyl group, more preferably an alkenyl group having 2 to 4 carbon atoms, and particularly preferably a vinyl group.

When two or more of R ¹ to R ³ do not form a ring structure bonded to each other, as described above, R ¹ to R ³ At least one has a polymerizable functional group, and the remainder is not specifically limited, Preferably it is a C1-C4 alkyl group, More preferably, R <^1> is a C2-C4 alkenyl group, R <^2> , R <^3> is Each independently represents an alkyl group having 1 to 4 carbon atoms, and a particularly preferable combination is R ¹ is a vinyl group, and R ² and R ³ are each independently an ethyl group or a methyl group.

When R ¹ and R ² are bonded to each other to form a ring structure, the ring structure necessarily includes "-CO-N-" represented by Formula 1, and the ring structure may further have a hetero atom, The ring structure is preferably a 4 to 8 membered ring structure, and particularly preferable ring structures are a pyrrolidone ring and a maleimide ring. "CO" in the said description means carbonyl (C = O). In the amide compound b2, the polymerizable functional group may be in a ring structure, or R ³ may have. When R ¹ and R ² are bonded to each other to form a ring structure, R ³ is preferably an alkenyl group having 2 to 4 carbon atoms, and particularly preferably a vinyl group.

When R ² and R ³ are bonded to each other to form a ring structure, the ring structure necessarily includes a nitrogen atom represented by Formula 1, and the ring structure may further have a hetero atom, preferably 4 to It is an 8-membered ring structure, and a particularly preferable ring structure is a morpholine ring. The functional group which can superpose | polymerize may be in ring structure, and R <^1> may have it. When R ² and R ³ are bonded to each other to form a ring structure, R ¹ is preferably an alkenyl group having 2 to 4 carbon atoms, and particularly preferably a vinyl group.

As a specific example of a preferable amide compound b2, dialkyl acrylamides, such as acryloyl morpholine (ACMO), N-vinylpyrrolidone (NVP), diethyl acrylamide, dimethyl acrylamide, maleimide, cyclohexyl maleimide Maleimide, such as these, etc. are mentioned.

In the whole monomer for oligomer B, the amide compound b2 preferably accounts for 3 to 50% by weight, more preferably 10 to 30% by weight. If it exists in this range, adhesive force to a board | substrate, such as a glass plate, will not increase too much, the adhesive force to an optical film will rise, and a rework property is achieved as a result.

The oligomer B may further copolymerize monomers ("monomers other than b1 and b2") other than the said (meth) acrylate b1 and the amide compound b2. In the whole monomer for oligomer B, "monomers other than b1 and b2" preferably occupies less than 0 or 10 weight%, More preferably, it occupies less than 0 or 7 weight%. As a specific example of "monomers other than b1 and b2", the carboxyl group-containing monomer which can be copolymerized in order to improve the compatibility of polymer A and oligomer B, and the tertiary amine which can be copolymerized are mentioned. Specific examples of the carboxyl group-containing monomer are (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, and the like, and these may be used alone or in combination of two or more. Specific examples of the tertiary amine copolymerizable are N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and the like. Since these amines are easy to yellow under high temperature, the use of a carboxyl group-containing monomer is preferable for the purpose of improving compatibility.

The weight average molecular weight of oligomer B is 3000-20000, Preferably it is 3000-10000. The oligomer B with a weight average molecular weight exceeding 20000 becomes poor in compatibility with the polymer A, and the adhesive composition obtained easily becomes turbid. When the oligomer B whose weight average molecular weight is less than 3000 is used, the adhesive composition which is poor in durability is obtained. The weight average molecular weight of oligomer B is measured by GPC method similarly to the case of polymer A.

The polymerization method for obtaining oligomer B is not specifically limited, The solution polymerization method, emulsion polymerization method, UV polymerization method, etc. which are well-known manufacturing methods can be selected suitably, In the point of transparency, water resistance, cost, etc., the solution polymerization method is desirable.

In the case of solution polymerization, the initiator and solvent illustrated in the superposition | polymerization for obtaining the polymer A can be used suitably. The initiator is preferably used 0.1 to 15 parts by weight based on 100 parts by weight of the monomer.

In order to control the molecular weight of oligomer B, a chain transfer agent can also be used at the time of superposition | polymerization. A conventional chain transfer agent can use a conventional thing suitably, For example, lauryl mercaptan, glycidyl mercaptan, 2-mercaptoethanol, mercaptoacetic acid, thioglycolic acid 2-ethylhexyl, 2, 3- dimercapto- 1-propanol, (alpha) -methylstyrene dimer, etc. are mentioned. Among these, 1 type may be used or 2 or more types may be used together. The chain transfer agent is usually used in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the monomer.

<Adhesive Composition>

According to the present invention, the pressure-sensitive adhesive composition preferably contains 5 to 35 parts by weight, more preferably 10 to 25 parts by weight of oligomer B with respect to 100 parts by weight of polymer A. If it is in the said range, the effect which added oligomer B is fully exhibited, and there exists little possibility that it will adversely affect the adhesive characteristic of the polymer A.

In addition, unless otherwise indicated, a weight part in this specification means solid weight. In other words, components that volatilize after drying at 130 ° C. for 3 minutes are not counted in parts by weight.

The adhesive composition of this invention may contain a crosslinking agent further. As a crosslinking agent, what is known conventionally is contained widely, Polyfunctional melamine compounds, such as methylated methylol melamine and butylated hexamethylol melamine; Polyfunctional epoxy compounds such as diglycidyl aniline, glycerin diglycidyl ether, and 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane; 1 in polyfunctional isocyanate compounds, such as tolylene diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, trimethylolpropanetolylene diisocyanate, polyether polyisocyanate, polyester polyisocyanate, etc. Species or two or more kinds may be used. Here, a polyfunctional epoxy compound is a compound which has 2 or more of epoxy rings in a molecule | numerator.

According to the present invention, the amount of the crosslinking agent contained in the pressure-sensitive adhesive composition is usually 0.01 to 20 parts by weight, preferably 0.01 to 10 parts by weight, and more preferably 0.01 to 5 parts by weight based on 100 parts by weight of the polymer A in the composition. It is weight part or 0.05-10 weight part, More preferably, it is 0.05-1 weight part.

The pressure-sensitive adhesive composition of the present invention may further contain general additives, namely ultraviolet absorbers, light stabilizers, peeling adjusters, tackifiers, plasticizers, softeners, fillers, colorants (such as pigments and dyes), anti-aging agents, surfactants, and the like. According to the present invention, the total content of the polymer A and the oligomer B in the pressure-sensitive adhesive composition is preferably 80 to 100% by weight, more preferably 90 to 100% by weight.

<Adhesive sheet>

The adhesive sheet of this invention is equipped with the adhesive layer containing the above-mentioned adhesive composition. The form of an adhesive sheet is not specifically limited, For example, what can be called a sheet or a tape in the art, etc. are contained. The adhesive sheet may or may not have a so-called base material. The adhesive layer in the adhesive sheet without a base material can be obtained by apply | coating and drying an adhesive composition on a peeling liner, for example. When using a base material, the said base material may be a transparent plastic film etc. whose thickness is 10-1000 micrometers normally, and an adhesive layer is provided in one side or both sides of a base material. The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is usually 5 to 1000 µm, preferably 10 to 100 µm.

The adhesive sheet by this invention is suitable for fixing of an optical film, for example. As an optical film, PET film, TAC film, a polycarbonate film, etc. are mentioned. Optical products, such as an acrylic resin board, a polycarbonate board, and a glass board, are bonded together through the adhesive layer of the adhesive sheet of this invention, and optical products, such as a PDP and a touch panel, can be manufactured suitably. .

<Example>

Hereinafter, the present invention will be described in more detail with reference to Examples, but these examples are by no means intended to limit the present invention. In addition, in the following description, unless otherwise indicated, a part and% means a weight part and weight%.

<Acrylic polymer A1>

97 parts of butyl acrylate, 3 parts of acrylic acid, 0.2 parts of azobisisobutyronitrile and 185.7 parts of ethyl acetate as a polymerization solvent were charged into a separate flask, and the mixture was stirred for 1 hour while introducing nitrogen gas. Thus, after removing oxygen in a flask, it heated up at 63 degreeC and made it react for 10 hours, and toluene was added and the acrylic polymer solution A1 of 25 weight% of solid content concentration was obtained. The weight average molecular weight was 850,000.

<Acrylic polymer A2>

85 parts of butyl acrylate, 10 parts of methyl acrylate, 5 parts of acrylic acid, 0.2 parts of azobisisobutyronitrile and 233.3 parts of ethyl acetate were added to a separate flask, and then the acrylic polymer solution A2 was added in the same manner as in <Acrylic polymer A1>. Got it. The weight average molecular weight was 650,000.

<Acrylic polymer A3>

97 parts of butyl acrylate, 3 parts of acrylic acid, 0.2 parts of azobisisobutyronitrile and 100 parts of ethyl acetate as a polymerization solvent were charged into a separate flask, and then acrylic polymer solution A3 was obtained by the same operation as <acrylic polymer A1>. The weight average molecular weight was 1.5 million.

<Acrylic oligomer B1>

80 parts of methyl methacrylate (Tg: 105 ° C.), 20 parts of acryloyl morpholine, 3 parts of 2-mercaptoethanol, 0.2 parts of azobisisobutyronitrile and 100 parts of toluene as a polymerization solvent were added to a separate flask, Stir for 1 hour while introducing nitrogen gas. Thus, after removing oxygen in a flask, it heated up at 70 degreeC and made it react for 3 hours, and also made it react at 75 degreeC for 2 hours, and obtained the acrylic oligomer solution B1 of 50 weight% of solid content concentration. The weight average molecular weight was 4000.

<Acrylic oligomer B2>

75 parts of methyl methacrylate (Tg: 105 ° C), 25 parts of diethylacrylamide, 10 parts of α-methylstyrene dimer, 10 parts of azobisisobutyronitrile and 120 parts of toluene as a polymerization solvent were charged into a separate flask, Stir for 1 hour while introducing nitrogen gas. Thus, after removing oxygen in a flask, it heated up at 85 degreeC and made it react for 5 hours, and obtained acrylic oligomer solution B2 of 50 weight% of solid content concentration. The weight average molecular weight was 4500.

<Acrylic oligomer B3>

Fractional flask with 80 parts of methyl methacrylate (Tg: 105 ° C.), 20 parts of acryloyl morpholine, 5 parts of acrylic acid, 0.9 parts of 2-mercaptoethanol, 0.2 parts of azobisisobutyronitrile and 100 parts of toluene as a polymerization solvent. It injected | throwed-in, and the acrylic oligomer solution B3 of 50 weight% of solid content concentration was obtained after operation similar to <acrylic oligomer B1> after that. The weight average molecular weight was 13500.

<Acrylic oligomer B4>

80 parts of methyl methacrylate (Tg: 105 ° C.), 20 parts of acryloyl morpholine, 0.25 parts of 2-mercaptoethanol, 0.2 parts of azobisisobutyronitrile and 100 parts of toluene as a polymerization solvent were charged into a separate flask, Then, acrylic oligomer solution B4 of 50 weight% of solid content concentration was obtained by operation similar to <acrylic oligomer B1>. The weight average molecular weight was 50000.

<Acrylic oligomer B5>

Except having changed the acryloyl morpholine into N-vinylpyrrolidone, it carried out similarly to <acryl-type oligomer B1>, and obtained the acryl-type oligomer solution B5. The weight average molecular weight was 4000.

<Acrylic oligomer B6>

95 parts of methyl methacrylate (Tg: 105 DEG C), 5 parts of dimethylaminoethyl methacrylate, 3 parts of 2-mercaptoethanol, 0.2 parts of azobisisobutyronitrile and 100 parts of toluene as a polymerization solvent were added to a separate flask. And acrylic oligomer solution B6 was obtained after operation similar to <acrylic oligomer B1> after that. The weight average molecular weight was 6000.

<Acrylic oligomer B7>

Except having changed methyl methacrylate into butyl acrylate (Tg: -55 degreeC), it carried out similarly to <acrylic oligomer B1>, and obtained acrylic oligomer solution B7. The weight average molecular weight was 4000.

In the following description, "part" means a weight part in solid content conversion.

<Example 1>

An adhesive solution was prepared by adding 15 parts of acrylic oligomer solution B1 to 0.6 parts of acrylic polymer solution A1 and 0.6 parts of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy-based crosslinking agent. . The solution was cast on a polyethylene terephthalate film having a surface treated with a thickness of 38 μm so as to have a thickness of about 25 μm after drying, heated and dried at 130 ° C. for 3 minutes, and further aged at 50 ° C. for 72 hours. An adhesive sheet was produced.

<Example 2>

10 parts of the acrylic oligomer solution B2 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy crosslinking agent were added to 100 parts of the acrylic polymer solution A2, and the same procedure as in Example 1. Pressure-sensitive adhesive sheet was prepared.

<Example 3>

10 parts of acrylic oligomer solution B3 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy-based crosslinking agent were added to 100 parts of acrylic polymer solution A2, and the same procedure as in Example 1. Pressure-sensitive adhesive sheet was prepared.

<Example 4>

20 parts of acrylic oligomer solution B5 and 100 parts of acrylic polymer solution A1 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy-based crosslinking agent were added to the same mixture as in Example 1. Pressure-sensitive adhesive sheet was prepared.

Comparative Example 1

20 parts of the acrylic oligomer solution B4 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy crosslinking agent were added to 100 parts of the acrylic polymer solution A1, and the same procedure as in Example 1. Pressure-sensitive adhesive sheet was prepared.

Comparative Example 2

20 parts of the acrylic oligomer solution B1 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy crosslinking agent were added to 100 parts of the acrylic polymer solution A3, and the same procedure as in Example 1. Pressure-sensitive adhesive sheet was prepared.

Comparative Example 3

An adhesive sheet was prepared in the same manner as in Example 1 by adding 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy-based crosslinking agent to 100 parts of an acrylic polymer solution A1.

<Comparative Example 4>

10 parts of the acrylic oligomer solution B6 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy-based crosslinking agent were added to 100 parts of the acrylic polymer solution A1, and the same procedure as in Example 1. Pressure-sensitive adhesive sheet was prepared.

Comparative Example 5

10 parts of the acrylic oligomer solution B7 and 0.5 part of 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane as a tetrafunctional epoxy crosslinking agent were added to 100 parts of the acrylic polymer solution A1, and the same procedure as in Example 1. Pressure-sensitive adhesive sheet was prepared.

The following each test was done about the above adhesive sheet. The test results are shown in Table 1 below.

<Removability Test Condition 1>

The adhesive sheet was laminated on a PET film (Toyo Bonde Co., Ltd. make, A4300 # 100), cut to 25 mm width, and had a release thickness of 38 μm PET laminated on the side opposite to A4300 # 100 of the adhesive sheet. The film was peeled off and the soda lime glass (Matsunami Glass Co., Ltd. product number S) was laminated | stacked on the exposed adhesive layer, and the laminated body of A4300 # 100-adhesive layer-soda lime glass was obtained. Lamination was performed at the pressure of 10 kg / cm using the lamination apparatus. After leaving the obtained laminated body for 10 days at room temperature, the speed | rate is changed in the range of 0.3-10 m / min, and peeling angle is changed in the range of 30-180 degrees, respectively, and a laminated body of PET film and an adhesive layer from soda-lime glass It peeled and confirmed visually the adhesive residual state on soda-lime glass.

Criteria;

○: no adhesive remains on the soda-lime glass

×: adhesive remains on soda-lime glass

<Removability Test Condition 2>

0.3 mm / min, 90 degree peeling angle after leaving the laminated body obtained by laminating | stacking the adhesive sheet cut | disconnected to 20 mm width on # 25 PET film (Toray Co., Ltd. product, Lumirror S-10) at 50 degreeC for 1 day. The force required to peel from the soda lime glass, that is, the adhesive force (unit: N / 20 mm) was measured.

<Transparency test>

The adhesive sheet is bonded to the slide glass `` S-1111 '' (haze value 0.4%) manufactured by Matsunami Glass Co., Ltd., and the haze value (%) by haze meter `` HM-150 '' (manufactured by Murakami Shikisai Kijutsu Co., Ltd.). (Diffusion transmittance / total light transmittance x 100) was measured.

Criteria;

○: haze value is less than 1.0%

X: haze value is 1.0% or more

<Coatability>

(Circle), application | coating stripe etc. which generate | occur | produced in the application | coating surface of an adhesive solution and which were smooth by the observation with the naked eye at the time of sample preparation were made into x, and the application | coating surface was not smooth.

As is clear from Table 1 and Table 2, according to the present invention, a pressure-sensitive adhesive composition satisfying transparency, re-peelability, and coatability at the same time can be obtained. When the molecular weight of the oligomer B is too large as in Comparative Example 1, white turbidity occurs, and when the molecular weight of the polymer A is too large as in Comparative Example 2, coating properties are poor and coating streaks are likely to occur, and oligomer B is added as in Comparative Example 3. If not used, the adhesive remains, and when using the oligomer B which does not copolymerize the amide compound b2 as in Comparative Example 4, the adhesive force is too high, and the acrylate component has a too low Tg (meth) acrylate as in Comparative Example 5. If only oligomer was used, the adhesive remained.

This application is based on Japanese Patent Application No. 2006-5120 filed in Japan, the contents of which are all incorporated herein.

According to the present invention, when applied to an optical film, it is possible to provide a pressure-sensitive adhesive composition excellent in re-peelability and at the same time excellent in transparency and coatability, and a pressure-sensitive adhesive sheet containing the same.

Claims (9)

Polymer A which is an acrylic polymer of the weight average molecular weight 50x10 <^4> -90 * 10 <^4> which uses a C4-C12 alkyl ester of (meth) acrylic acid as a main monomer, and Oligomer B which is an oligomer having a weight average molecular weight of 3000 to 20000 formed by copolymerizing at least the following (meth) acrylate b1 and an amide compound b2, provided that the (meth) acrylate b1 has a glass transition temperature of 60 ° C to It is (meth) acrylate which is 190 degreeC, and an amide compound b2 is a compound which has a polymerizable functional group, and is represented by following General formula (1). Pressure-sensitive adhesive composition containing. <Formula 1> R ¹ -CO-NR ² R ³ Wherein R ¹ to R ³ are each independently a hydrogen atom or a monovalent organic group, or any two of R ¹ to R ³ are bonded to each other to form a ring structure, and the remaining one is a hydrogen atom or monovalent oil. Appliance. The adhesive composition of Claim 1 whose polymerizable functional group which the amide compound b2 has is an alkenyl group. The pressure-sensitive adhesive according to claim 1, wherein R ¹ is an alkenyl group having 2 to 4 carbon atoms, and R ² and R ³ are each independently an alkyl group having 1 to 4 carbon atoms, or are bonded to each other to form a 4 to 8 membered ring structure. Composition. The pressure-sensitive adhesive composition of claim 1, wherein R ¹ and R ² are bonded to each other to form a 4 to 8 membered ring structure, and R ³ is an alkenyl group having 2 to 4 carbon atoms. The pressure-sensitive adhesive composition of claim 1, wherein the amide compound b2 is at least one of acryloyl morpholine, N-vinylpyrrolidone, dialkylacrylamide, maleimide. The pressure-sensitive adhesive composition of claim 1, wherein the (meth) acrylate b1 is an alkyl ester having 1 to 4 carbon atoms of methacrylic acid. The pressure-sensitive adhesive composition according to claim 1, which contains 100 parts by weight of polymer A and 5 to 35 parts by weight of oligomer B. The adhesive composition of Claim 1 which further contains 0.01-5 weight part of crosslinking agents containing a polyfunctional epoxy compound with respect to 100 weight part of polymer A. The adhesive sheet provided with the adhesive layer containing the adhesive composition in any one of Claims 1-8.