JP2003193014A - Pressure-sensitive adhesive composition for polarizing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive composition for a polarizing film, capable of enough preventing the occurrences of peeling, air bubbles, and a whitely spotting phenomenon, and excellent in reworkability and recyclability. <P>SOLUTION: This pressure-sensitive adhesive composition for the polarizing film contains (A) an acrylic copolymer, (B) a multifunctional compound, and (C) a silane coupling agent in specified amounts, wherein the acrylic copolymer (A) has a weight-average molecular weight of ≥800,000 and a glass transition temperature of (Tg) ≤-45°C and contains carboxyl groups in its molecule, the multifunctional compound (B) comprises (b-1) a specified polyisocyanate compound, (b-2) a specified polyaziridine compound, and/or (b-3) a specified polyepoxy compound, and the silane coupling agent (C) contains a mercapto group or an alicyclic epoxy group. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition for a polarizing film for sticking a polarizing film used for a liquid crystal display panel to a glass cell such as a liquid crystal cell. , An acrylic copolymer having a weight average molecular weight of 800,000 or more and a glass transition temperature (Tg) of −45 ° C. or less and containing a carboxyl group in the molecule (A)
Based on the acrylic copolymer (A) component as a polyfunctional compound (B) having reactivity with a specific polyisocyanate compound (b-1) a specific amount and / or polyepoxy compound (b-
2) A pressure-sensitive adhesive composition for a polarizing film, which contains a specific amount and a specific amount of a mercapto group- or alicyclic epoxy group-containing silane coupling agent (C).

[0002]

2. Description of the Related Art A liquid crystal display panel used in a wide range of fields as a display device is generally a liquid crystal cell in which a liquid crystal component oriented in a predetermined direction is sandwiched between two supporting substrates such as glass, and the liquid crystal cell. The polarizing film is attached to the surface of the supporting substrate of the cell using a pressure sensitive adhesive.

In recent years, liquid crystal display panels have been used as display devices for personal computers, wall-mounted televisions, car navigation systems, etc., so that the pressure-sensitive adhesive used therein is required to have a high degree of transparency. In addition, such a liquid crystal display panel is often used under severe conditions such as high temperature and high humidity, and in that case, peeling and air bubbles are generated at the interface between the pressure sensitive adhesive layer and the supporting substrate, and pressure sensitive There is a problem of occurrence of a so-called white drop phenomenon in which light leaks from the peripheral portion of the liquid crystal display plate and becomes white, which occurs because the adhesive layer cannot follow the contraction of the polarizing film. The occurrence of such peeling, bubbles, and blanking phenomenon is caused by insufficient adhesive force, insufficient cohesive force, and insufficient flexibility of the pressure-sensitive adhesive that adheres the polarizing film to the supporting substrate.

Further, in this technical field, when a polarizing film having such a pressure-sensitive adhesive layer is adhered to a liquid crystal cell and foreign matter is mixed in, damaged, or an adhesion error occurs,
The polarizing film will be peeled off and re-adhered. At that time, ease of operation and partial retention of the pressure-sensitive adhesive on the surface of the adherend such as a glass cell after peeling off the polarizing film, and cloudiness There is a problem (reworkability) such as occurrence of. Further, recently, in order to recycle an expensive liquid crystal cell, peeling of a polarizing film from a used liquid crystal display plate is often performed. At that time, it is easy to peel the polarizing film, and a glass cell is used. Characteristics such as no damage and no contamination of glass cell surface (recyclability)
However, it has come to be demanded as a new problem to be solved.

Various proposals have been made in order to prevent the occurrence of the above-mentioned peeling, air bubbles, white voids, and the like. For example, Japanese Patent Application Laid-Open No. 9-145925 discloses an alkyl (alkyl) having 2 to 12 carbon atoms. Alkoxysilyl group as a chain transfer agent for 100 parts by weight of a monomer mixture whose main component is 70 to 99.5% by weight of (meth) acrylate and 0.3 to 30% by weight of at least one kind having a carboxyl group, an amide group or a hydroxyl group. Obtained by copolymerization using 0.001 to 0.1 parts by weight of a thiol compound containing, a weight average molecular weight Mw of 800 to 1.5 million, and the ratio Mw / Mn of the Mw and the number average molecular weight Mn is 1.5 to 3.5. Disclosed is a pressure-sensitive adhesive type polarizing plate having a cross-linked acrylic pressure-sensitive adhesive composition containing a copolymer as a main component formed on at least one surface of a polarizer.

In the pressure-sensitive adhesive type polarizing plate proposed above, the occurrence of peeling, air bubbles, white voids, etc. can be suppressed to some extent, but this is mainly due to the fact that an acrylic copolymer containing an alkoxysilyl group-containing thiol compound used mainly as a chain transfer agent is used. It is thought that this is due to the regulation action of the molecular weight. This means that if there are too many alkoxysilyl group-containing thiol compounds,
The molecular weight of the acrylic copolymer is lowered and bubbles are easily generated (the right column on page 4, [0024] of the above publication), and such an effect is obtained by using a thiol compound containing a hydroxyl group instead of a thiol compound containing an alkoxysilyl group. It is clear from the description that it can be achieved by using a compound (page 4, right column [0025] of the same publication).

The publication of the above proposal does not mention anything about the reworkability and the recyclability.

Further, the inventors of the present invention further tried the above-mentioned examples, and found that the pressure-sensitive adhesive obtained had a problem in reworkability due to its too high initial adhesive force, and therefore, when peeling the polarizing film. Moreover, it was found that the glass cell surface was not sufficiently recyclable due to contamination.

Further, Japanese Patent Laid-Open No. 9-269413 discloses a polarizing plate having an adhesive layer which has excellent optical properties and durability under high temperature and high humidity conditions.
At least one surface of the polarizing plate having specific characteristics, an acrylic resin containing a functional group that reacts with an epoxy group (A),
Silane-based compound having functional group that reacts with epoxy group
(B), a compound having at least two epoxy groups
A polarizing plate provided with an adhesive layer containing (C) and a crosslinking agent (D) is disclosed.

As the acrylic resin (A) of the second proposal, an acrylic copolymer containing a carboxyl group is described as in the present invention, and as the silane compound (B),
Examples of the mercapto group-containing silane compound used in the present invention, the specific polyepoxy compound used in the present invention is also exemplified in the compound (C), also a specific one used in the present invention as a crosslinking agent (D) Parts are illustrated.

However, in the embodiment which is a concrete embodiment of the invention of the second proposal, the butyl acrylate / acrylic acid different from the preferred acrylic copolymer of the present invention is used as the acrylic resin (A). = 95/5 (weight ratio), an acrylic copolymer is disclosed, but the average molecular weight thereof is not described, and therefore there is no description or difference in the effect thereof. The silane-based compound (B) is 3-triethoxysilylpropylsuccinic anhydride, the compound (C) is glycerol diglycidyl ether, and the crosslinking agent (D) is tolylene diisocyanate / methylolpropane adduct. The body is only disclosed.

When the inventors of the present invention retested the embodiment of the second proposal, the pressure-sensitive adhesive obtained was also
The initial adhesive strength is too high and there is a problem in reworkability, lack of recyclability due to contamination of the glass cell surface at the time of peeling the polarizing film, and further there are problems such as peeling in durability test. It turned out to be.

[0013]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pressure-sensitive adhesive for a polarizing film, which can sufficiently prevent the occurrence of peeling, bubbles, and white spots, and is excellent in reworkability and recyclability. To provide an agent composition.

As a result of intensive studies to solve the above problems, the present inventors have found that, for example, they have a weight average molecular weight of 1.2 million and a glass transition temperature (Tg) of −55 ° C. Polyisocyanate derived from hexamethylene diisocyanate (HMDI) using a high molecular weight acrylic copolymer copolymerized 1% by weight based on
1,3-bis (N, N'-diglycidylaminomethyl) polyepoxy compounds such as cyclohexane and mercapto group-containing silane coupling agents such as γ-mercaptopropyltrimethoxysilane, 100 parts by weight of the acrylic copolymer Based on the above, the pressure-sensitive adhesive composition for a polarizing film containing 1.5 parts by weight, 0.005 parts by weight and 0.3 parts by weight, respectively,
It was found that it is soft and has excellent strength and viscoelasticity, and can solve all the above problems as a pressure-sensitive adhesive for polarizing films, and further studies have been completed to complete the present invention.

[0015]

Therefore, according to the present invention,
(A) to (C) below: (A) Weight average molecular weight of 800,000 or more, glass transition temperature (Tg)
Based on 100 parts by weight of an acrylic copolymer having a -45 ° C or lower and containing a carboxyl group in the molecule,

(B) The acrylic copolymer (A) contains two or more functional groups capable of reacting with the component (A) to form a crosslinked structure.
a polyfunctional compound containing (b-1) and / or (b-2);

(B-1) hexamethylene diisocyanate,
0.15 to 3 parts by weight of a polyisocyanate compound derived from xylylene diisocyanate or hydrogenated xylylene diisocyanate as an active ingredient,

(B-2) a polyepoxy compound which is 1,3-bis (N, N-glycidylaminomethyl) cyclohexane or N, N, N ', N'-tetraglycidyl-m-xylenediamine,
0.15 to 3 parts by weight as an active ingredient,

And

(C) 0.15 to 1 part by weight of a silane coupling agent containing a mercapto group or an alicyclic epoxy group,

There is provided a pressure-sensitive adhesive composition for a polarizing film, characterized by containing as an essential component. Hereinafter, the pressure-sensitive adhesive composition for a polarizing film of the present invention will be described in detail.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic copolymer (A) used in the present invention comprises a repeating unit derived from an acrylic acid ester and a methacrylic acid ester as a main component, for example, the acrylic copolymer (A). The total content is 50% by weight or more, and a carboxyl group is contained in the molecule. Further, the acrylic copolymer (A), if necessary,
Further, a functional group other than the carboxyl group, for example, a hydroxyl group can be contained in the molecule.

The acrylic copolymer (A) which is particularly preferably used in the present invention specifically includes the following monomers (a-1) and (a-2) as essential components:

(A-1) represented by the following general formula (1), H ₂ C = CHCOOR ¹ (1) (wherein R ¹ represents a linear or branched alkyl group having 4 to 10 carbon atoms). Acrylic ester whose glass transition temperature (Tg) of its homopolymer is -50 ° C or lower [hereinafter,
Sometimes referred to as acrylic acid ester or monomer (a-1)], and

(A-2) A monomer having a carboxyl group in the molecule [hereinafter, a carboxyl group-containing monomer or simply a monomer
(sometimes referred to as (a-2)], and, if necessary, together with these monomers (a-1) and (a-2), the following monomers (a-3) and / or Or (a-4),

(A-3) A monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule, which is a monomer other than the above-mentioned monomer (a-2). A monomer [hereinafter sometimes referred to as a functional monomer or simply a monomer (a-3)], and / or
Or

(A-4) Comonomers other than the monomers (a-1) to (a-3), which are copolymerizable with the above monomers (a-1) to (a-3) It is preferable to copolymerize [hereinafter, may be simply referred to as a comonomer or a monomer (a-4)].

Acrylic ester (a-1) of the above general formula (1)
Has a linear or branched alkyl group having 4 to 10 carbon atoms,
The homopolymer is an acrylic acid ester having a glass transition temperature (Tg) of -50 ° C or lower, and specific examples thereof include n-butyl acrylate, 2-ethylhexyl acrylate, and n-butyl acrylate.
Octyl acrylate, isooctyl acrylate, n-
Examples thereof include nonyl acrylate and isononyl acrylate, and among these, n-butyl acrylate, 2-ethylhexyl acrylate and isooctyl acrylate are preferable. These acrylic acid esters may be used alone or in combination of two or more.

The "glass transition temperature (Tg) of a homopolymer" referred to herein is the unit amount described in "Mechanical Properties of Polymers", pages 11 to 35, translated by LE Nielsen, translated by Nojiharu Onogi. The glass transition temperature of the body is applied.

The copolymerization amount of the acrylic acid ester (a-1) is 100 weight% in total of the monomer components (a-1) to (a-4) constituting the acrylic acid copolymer (A). Generally 69, based on%.
It may be in the range of 5 to 99.5% by weight, preferably 79.5 to 99.3% by weight, and more preferably 89.5 to 99.1% by weight. If the copolymerization amount of the acrylic ester (a-1) is not more than the upper limit value, it is preferable because the generation of bubbles due to insufficient cohesive force is suppressed, while if it is not less than the lower limit value, the cohesive force becomes excessive. It is preferable because inconveniences such as peeling and blanking phenomenon are less likely to occur.

Specific examples of the carboxyl group-containing monomer (a-2) include acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride and the like. Among these, acrylic acid, The use of methacrylic acid is preferred. These monomers (a-2) may be used alone or in combination of two or more kinds.

The copolymerization amount of these carboxyl group-containing monomers (a-2) is generally 0.5 to 1.5 based on 100% by weight of the total of the monomer components (a-1) to (a-4). % By weight, preferably 0.
The range is 7 to 1.3% by weight, preferably 0.7 to 1.1% by weight. If the copolymerization amount of the monomer (a-2) is less than or equal to the upper limit, it is preferable because inconveniences such as peeling and white spotting phenomenon due to excessive cohesive force are less likely to occur, while if it is at least the lower limit, The generation of bubbles due to insufficient cohesive force is suppressed, which is preferable.

In the present invention, these monomers (a-1) and (a-
Along with 2), if necessary, the functional monomer
Examples of (a-3) include a monomer having, as a functional group, a hydroxyl group, an amide group or a substituted amide group, an amino group or a substituted amino group, a lower alkoxyl group, an epoxy group, or the like. A monomer having two or more radically polymerizable unsaturated groups in the molecule can also be used.

Specific examples of these functional comonomers include:
For example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate (preferably 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate) Acrylics, 2-hydroxyethyl methacrylate) and other hydroxyl group-containing monomers; for example, acrylamide, methacrylamide, diacetone acrylamide, N-methylol acrylamide,
N-methylolmethacrylamide, Nn-butoxymethylacrylamide, Ni-butoxymethylacrylamide, N,
An amide group- or substituted amide group-containing monomer such as N-dimethylacrylamide, N-methylacrylamide (preferably acrylamide, methacrylamide);

For example, aminoethyl acrylate, N, N-
Dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate (preferably N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate), etc. An amino group- or substituted amino group-containing monomer;

For example, 2-methoxyethyl acrylate,
2-ethoxyethyl acrylate, 2-n-butoxyethyl acrylate, 2-methoxyethoxyethyl acrylate,
2-ethoxyethoxyethyl acrylate, 2-n-butoxyethoxyethyl acrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-n-butoxyethyl methacrylate, 2-methoxyethoxyethyl methacrylate, 2-ethoxyethoxyethyl methacrylate, 2-n-butoxyethoxyethyl methacrylate, methoxy polyethylene glycol monoacrylate, methoxy polyethylene glycol monomethacrylate, (preferably 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-methoxyethyl methacrylate,
2-ethoxyethyl methacrylate, methoxy polyethylene glycol monoacrylate, methoxy polyethylene glycol monomethacrylate) and other lower alkoxy group-containing monomers;

For example, epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, glycidyl methallyl ether (preferably glycidyl acrylate, glycidyl methacrylate); for example, divinylbenzene, diallyl phthalate, triallyl cyanurate, triaryl cyanurate Allyl isocyanurate, ethylene glycol di (meth) acrylate, 1,
2-propylene glycol di (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (Meth) acrylate, trimethylolpropane tri (meth)
Examples thereof include monomers having two or more radically polymerizable unsaturated groups such as acrylate and allyl (meth) acrylate.

These functional monomers (a-3) may be used alone or in combination of two or more, but the generation of bubbles due to insufficient cohesive force is suppressed. From the viewpoints of excellent reworkability and recyclability, it is preferable to use a hydroxyl group-containing monomer.

The copolymerization amount of these functional monomers (a-3) is
In the range of generally 0 to 1% by weight, preferably 0.05 to 0.8% by weight, more preferably 0.1 to 0.6% by weight, based on 100% by weight of the total of the monomer components (a-1) to (a-4). It should be If the copolymerization amount of the monomer (a-3) is less than or equal to the upper limit, it is preferable because inconveniences such as peeling and white spotting phenomenon due to excessive cohesive force are less likely to occur, while using more than the lower limit, The generation of bubbles due to insufficient cohesive force is suppressed, which is preferable.

In the present invention, these monomers (a-1) and (a-
2), or optionally used together with the monomers (a-1) to (a-3), specific examples of the comonomer (a-4), other than the (a-1) Acrylic acid ester of, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, i-butyl acrylate, t-butyl acrylate, tridecyl acrylate,
Stearyl acrylate, oleyl acrylate, etc. (preferably methyl acrylate); Methacrylic acid ester such as ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl Methacrylate, cyclohexyl methacrylate, benzyl methacrylate, etc. (preferably methyl methacrylate);

Saturated fatty acid vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, "vinyl versatate" (trade name) and the like (preferably vinyl acetate); aromatic vinyl monomers such as styrene and α- Methylstyrene, vinyltoluene and the like (preferably styrene); and vinyl cyanide monomers such as acrylonitrile and methacrylonitrile (preferably acrylonitrile);

Examples of the comonomer (a-4) include dimethylmalate, di-n-butylmalate, di-2-ethylhexylmalate, di-n-octylmalate, dimethylfumarate, di- A maleic acid or a fumaric acid diester such as n-butyl fumarate, di-2-ethylhexyl fumarate or di-n-octyl fumarate; can also be used.

The copolymerization amount of these comonomer (a-4) is based on the total 100% by weight of the above monomer components (a-1) to (a-4).
Generally, it is in the range of 0 to 30% by weight, preferably 0 to 25% by weight, more preferably 0 to 20% by weight. Monomer
If the copolymerization amount of (a-4) is less than or equal to the upper limit, it is preferable because inconveniences such as peeling and white spotting phenomenon due to excessive cohesive force are less likely to occur, while use of at least the lower limit causes insufficient cohesive strength. The generation of bubbles due to the above is suppressed, which is preferable.

Acrylic copolymer used in the present invention
The weight average molecular weight (Mw) of (A) is required to be 800,000 or more, preferably 1,000,000 or more, and more preferably 110 to 1,500,000. The weight average molecular weight (M
If w) is less than the lower limit, it is not preferable because bubbles are generated due to insufficient cohesive force. On the other hand, if it is at most the upper limit value, an acrylic copolymer having a structure with a low branching degree is easily obtained, which is preferable.

The weight average molecular weight (Mw) and number average molecular weight (Mw) of the acrylic copolymer (A) preferably used in the present invention are
The ratio Mw / Mn with n) is generally 20 or less, preferably 5 to 15. When the value of Mw / Mn is less than or equal to the upper limit, inconveniences such as generation of bubbles and deterioration of reworkability due to insufficient cohesive force are less likely to occur, which is preferable.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the acrylic copolymer are the values measured by the following method.

[0047]Method of measuring average molecular weight (Mw and Mn) Measure according to the following (1) to (3). (1) Apply the acrylic copolymer solution to the release paper and apply at 100 ℃
And dried for 2 minutes to obtain a film-shaped acrylic copolymer
It (2) The film-shaped acrylic copolymer obtained in (1) above
Body with tetrahydrofuran so that the solid content is 0.2%
Dissolve. (3) Gel permeation chromatograph under the following conditions.
The weight of acrylic copolymer is calculated by using the fee (GPC).
The average molecular weight (Mw) and the number average molecular weight (Mn) are measured.

(Condition) GPC: HLC-8220 GPC (manufactured by Tosoh Corporation) Column: TSK-GEL GMHXL 4 pieces used Mobile phase solvent: Tetrahydrofuran Flow rate: 0.6 ml / min Column temperature: 40 ℃

Acrylic copolymer used in the present invention
(A) also needs to have a glass transition temperature (Tg) of −45 ° C. or lower, and preferably −50 ° C. or lower. If the Tg is too high above the temperature, the adhesive strength to the supporting substrate becomes too high, and the reworkability deteriorates, which is not preferable.

In the present invention, the glass transition temperature (Tg) of the acrylic copolymer is a value measured and determined by the following.

[0051]Glass transition temperature (Tg) Measure according to the following (1) to (3). (1) Apply the acrylic copolymer solution to the release paper and apply at 100 ℃
And dried for 2 minutes to obtain a film-shaped acrylic copolymer
It (2) Made of aluminum foil with a thickness of about 0.05 mm, inner diameter of about 5 mm,
Approximately 10 mg of the sample obtained in (1) was placed in a cylindrical cell with a depth of approximately 5 mm.
The weighed one is used as a measurement sample. (3) Seiko Denshi Kogyo Co., Ltd. SSC-5000 type differential scanning calorie
-1 using a differential scanning calorimeter
Measure from 50 ℃ at a heating rate of 10 ℃ / min.

Further, the acrylic copolymer (A) used in the present invention is preferably a low branching degree polymer.

[0053] In general polymers of the general formula [η] = KM _r ^a can be expressed by [Mark Hoinku (Mark-Houwink) equations] are known. Here, [η] is the intrinsic viscosity, M _r is the molecular weight of the polymer, and K and a are constants depending on the types of polymer and solvent and the temperature. This expression is log [η] = alogM _r + lo
It can be rewritten as gK, where a is logM _r is X
Axis, the slope when plotting log [η] as the Y axis (the slope of the Mark Hoink plot), where logK is Y
It becomes a cutting edge.

The degree of polymer branching can be known by the gradient (a) of the above Mark-Houwink plot. A polymer having a large value has a low branching structure, and a polymer having a small value has a high branching degree. It has a degree structure.
The acrylic copolymer (A) used in the present invention preferably has a in the range of 0.3 to 1.5, particularly 0.5 to 1.0. By using such a low branching degree acrylic copolymer (A), a pressure-sensitive adhesive layer having more excellent viscoelasticity can be obtained. If the gradient is less than or equal to the upper limit, there will be no inconvenience such as a decrease in the smoothness of the coated surface after applying the solution of the pressure-sensitive adhesive composition, and if it is more than the lower limit, It is preferable because the effect of improving the durability can be obtained.

The Mark Hoink plot is
It is measured by the following method.

[0056]Measuring the slope of the Mark Hoink plot
Method Measure according to the following (1) to (6). (1) Apply the acrylic copolymer solution to the release paper and apply at 100 ℃
And dried for 2 minutes to obtain a film-shaped acrylic copolymer
It (2) The obtained film-shaped acrylic copolymer was
Hydrofuran solid content 1% by weight, 2% by weight, 3% by weight
% And 4% by weight. (3) High sensitive differential refractometer [DRM-1021,
Otsuka Electronics Co., Ltd.]
Measure the ratio (dn / dc) to the amount of change (dc). (4) The film-like acrylic copolymer obtained in (1) above
Tetrahydrofuran makes the solid content 0.2% by weight
Dissolve.

(5) The intrinsic viscosity ([η]) and the weight average molecular weight ([η]) of the acrylic copolymer were measured using a refraction / differential pressure viscosity detector [T60A, manufactured by Asahi Techneion Co., Ltd.] under the following conditions. Mw)
To measure. (Conditions) GPC: HLC-8220 GPC [Tosoh Corporation
Column]: TSK-GEL GMHXL 2 used Mobile phase solvent: Tetrahydrofuran Flow rate: 0.8 ml / min Column temperature: 40 ° C When measuring, the dn / dc of the acrylic copolymer is the value determined in (3) above. Using. (6) Calculate the slope of Mark Hoink plot by the following formula. Mark Hoink plot slope (a) = Log [η] / Lo
g (Mw)

Acrylic copolymer used in the present invention
(A) is not particularly limited to the polymerization method,
Although it can be polymerized by a known method such as solution polymerization, emulsion polymerization, suspension polymerization, in producing the pressure-sensitive adhesive composition of the present invention using a mixture of copolymers obtained by the polymerization, treatment steps are Polymerization by solution polymerization is preferred because it is relatively simple and can be carried out in a short time.

In the solution polymerization, generally, a predetermined organic solvent, a monomer, a polymerization initiator and, if necessary, a chain transfer agent are charged in a polymerization tank, and the mixture is fed in a nitrogen stream or at the reflux temperature of the organic solvent. The reaction is carried out by heating for several hours while stirring. In this case, at least a part of the organic solvent, the monomer, the polymerization initiator and / or the chain transfer agent may be sequentially added.

As the above-mentioned organic solvent for polymerization, for example,
Benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-
Aromatic hydrocarbons such as xylene, tetralin, decalin and aromatic naphtha; for example, n-hexane, n-heptane,
Fatty or alicyclic hydrocarbons such as n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil; for example, ethyl acetate, acetic acid n-
Butyl, n-amyl acetate, 2-hydroxyethyl acetate, acetic acid
Esters such as 2-butoxyethyl, 3-methoxybutyl acetate and methyl benzoate; for example, ketones such as acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, methylcyclohexanone;

For example, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether; for example, methyl alcohol, ethyl alcohol, n-propyl. Alcohols such as alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol; These organic solvents may be used alone or in admixture of two or more.

Among these organic solvents for polymerization, it is preferable to use an organic solvent which hardly causes chain transfer during the polymerization reaction, such as esters and ketones, in the polymerization of the acrylic copolymer (A). In particular, it is preferable to use ethyl acetate, methyl ethyl ketone, acetone or the like from the viewpoint of the solubility of the acrylic copolymer (A) and the ease of the polymerization reaction.

As the above-mentioned polymerization initiator, it is possible to use organic peroxides, azo compounds and the like which can be used in ordinary solution polymerization.

Examples of such organic peroxides include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide and di-i-propyl peroxide. Oxydicarbonate, di-
2-Ethylhexyl Peroxydicarbonate, t-Butyl Peroxy Vivalate, 2,2-Bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-Bis (4,4-di-t -
Amylperoxycyclohexyl) propane, 2,2-bis
(4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t -Butylperoxycyclohexyl) butane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) butane, and the like,

Examples of the azo compound include 2,2'-azobis-i-butylnitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2, 4-dimethylvaleronitrile and the like can be mentioned.

Among these organic peroxides, in the polymerization of the acrylic copolymer (A), it is preferable to use a polymerization initiator which does not cause a graft reaction during the polymerization reaction, and it is particularly preferable to use an azobis type. The amount used is usually 0.01 to 2 parts by weight, preferably 0.1 to 1.0 part by weight, based on 100 parts by weight of the total amount of monomers.

In addition, a chain transfer agent is usually not used in the production of the acrylic copolymer (A) used in the present invention, but it is necessary to the extent that the object and effect of the present invention are not impaired. It can be used accordingly.

Examples of such chain transfer agents include:
Cyanoacetic acid; C1-C8 alkyl esters of cyanoacetic acid; Bromoacetic acid; Bromoacetic acid C1-C8 alkyl esters; Aromatic compounds such as anthracene, phenanthrene, fluorene, and 9-phenylfluorene;
Aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone,
Benzoquinone derivatives such as 2,3,5,6-tetramethyl-p-benzoquinone; Borane derivatives such as tributylborane;

Halogenated carbonization of carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, 3-chloro-1-propene, etc. Hydrogens; aldehydes such as chloral and furaldehde: C1-18
Aromatic mercaptans such as thiophenol and toluene mercaptan; mercaptoacetic acid, alkyl esters of mercaptoacetic acid having 1 to 10 carbon atoms, hydroxyalkyl mercaptans having 1 to 12 carbon atoms, terpenes such as vinylene and terpinolene And the like.

The polymerization temperature is generally about 30 to 180 ° C.,
It is preferably in the range of 50 to 150 ° C, more preferably 50 to 90 ° C, and further preferably 50 to 80 ° C.

When unreacted monomers are contained in the polymer obtained by the solution polymerization method or the like, it is possible to purify by a reprecipitation method with methanol or the like to remove the unreacted monomers. Is.

The pressure-sensitive adhesive composition for a polarizing film of the present invention, together with the acrylic copolymer (A) as an essential component,
The following containing 2 or more, preferably 2 to 4 functional groups capable of reacting with the acrylic copolymer (A) to form a crosslinked structure.
(b-1), (b-2) and / or (b-3),

(B-1) hexamethylene diisocyanate,
A polyisocyanate compound derived from xylylene diisocyanate or hydrogenated xylylene diisocyanate,

(B-2) Tetramethylolmethane tris (β-
Aziridinyl propionate) or trimethylolpropane tris (β-aziridinyl propionate) polyaziridine compound, and / or

(B-3) a polyepoxy compound which is 1,3-bis (N, N-glycidylaminomethyl) cyclohexane or N, N, N ′, N′-tetraglycidyl-m-xylenediamine, It comprises a functional compound (B).

In order to provide a pressure-sensitive adhesive composition for a polarizing film, which is capable of sufficiently preventing the occurrence of peeling, air bubbles and white spots, and is excellent in reworkability and recyclability. I have been diligently researching. As a result, the acrylic copolymer (A), the polyfunctional compound (B)
As, polyisocyanate compounds such as polyisocyanates derived from hexamethylene diisocyanate (HMDI) (b-1), polyaziridine compounds such as tetramethylolmethane tris (β-aziridinyl propionate) (b-2) and Polarizing film only by using any one or two or more compounds selected from polyepoxy compounds (b-3) such as 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane It has been found that a pressure-sensitive adhesive for use can solve all these problems.

Hexamethylene diisocyanate as described above,
Polyisocyanate compound derived from xylylene diisocyanate or hydrogenated xylylene diisocyanate (b-1)
Examples thereof include polyisocyanate compounds derived from various polyisocyanates such as dimers or trimers of these polyisocyanates or adducts of these polyisocyanates with polyols such as trimethylolpropane.

Among these polyisocyanate compounds, the trimer of hexamethylene diisocyanate, the adduct of hexamethylene diisocyanate and trimethylolpropane, and the adduct of hydrogenated xylylene diisocyanate and trimethylolpropane are particularly preferable.

The amount of the polyisocyanate compound (b-1) used is required to be 0.15 to 3 parts by weight as an active ingredient, based on 100 parts by weight of the acrylic copolymer (A). It is preferably in the range of 2 to 2 parts by weight.

Examples of the polyaziridine compound (b-2) include tetramethylolmethane tris (β-aziridinyl propionate) or trimethylolpropane tris (β-
A polyaziridine compound which is aziridinyl propionate) can be used. The amount of these polyaziridine compounds (b-2) used is in the range of 0.001 to 0.1 parts by weight, particularly 0.001 to 0.05 parts by weight, as an active ingredient, based on 100 parts by weight of the acrylic copolymer (A). Is preferred.

Examples of the polyepoxy compound (b-3) include 1,3-bis (N, N-glycidylaminomethyl) cyclohexane or N, N, N ', N'-tetraglycidyl-m-xylylenediamine. Can be used. The amount of these polyepoxy compounds (b-3) used is 0.005 to 0.3 parts by weight, particularly 0.01 to 0.2 parts by weight, as an active ingredient, based on 100 parts by weight of the acrylic copolymer (A). Is preferred.

Polyisocyanate compound (b-1) and polyaziridine compound (b-2) as the polyfunctional compound (B)
And / or the amount of the polyepoxy compound (b-3) used is preferably not less than the above lower limit value because the generation of bubbles due to insufficient cohesive force is suppressed, and is not more than the above upper limit value. It is preferable that peeling due to excessive cohesive force, white spots and the like are less likely to occur.

In the present invention, a polyfunctional compound (B) containing the above polyisocyanate compound (b-1), polyaziridine compound (b-2) and / or polyepoxy compound (b-3)
Can be used alone or in combination of two or more. Polyisocyanate compound (b-1), polyaziridine compound (b-2) and polyepoxy compound (b-3)
When used in combination, each can be appropriately selected within the above-mentioned usage amount range, polyisocyanate compound (b-1) and polyaziridine compound (b-2)
In the case of, preferably, the polyisocyanate compound (b
-1): The polyaziridine compound (b-2) is preferably in the range of 1 to 500: 1, particularly 10 to 300: 1 by weight of the active ingredient. In the case of the epoxy compound (b-3), preferably, the polyisocyanate compound (b-1): polyepoxy compound (b-3) is 1 to 300: 1, particularly 10 to 100 by weight ratio of the active ingredient. It is preferable to use it in the range of 1: 1.

In the present invention, if necessary, the polyisocyanate compound (b-
1), a polyaziridine compound (b-2) and / or a polyepoxy compound (b-3) together with these polyisocyanate compound (b-1), polyaziridine compound (b-2) and polyepoxy compound (b-3 It is also possible to use a polyfunctional compound other than the above).

Examples of such polyfunctional compounds include diphenylmethane diisocyanate, triphenylmethane triisocyanate, tolylene diisocyanate, isophorone diisocyanate, dimers or trimers of polyisocyanates thereof, and polyisocyanates thereof, and trimethylol. Polyisocyanate compounds other than the polyisocyanate compound (b-1) such as polyisocyanate compounds derived from various polyisocyanates such as adducts with polyols such as propane;

For example, a reaction product of the above polyisocyanate compound such as N, N'-hexamethylenebis (1-aziridinecarboxamide), methylenebis [N- (1-aziridinylcarbonyl) -4-aniline] and ethyleneimine Things and (poly)
Compounds other than the above (b-2) obtained by adding ethyleneimine to a polyvalent ester of a polyol such as alkylene glycol, trimethylolpropane, pentaerythritol and α, β-unsaturated carboxylic acid such as (meth) acrylic acid;

For example, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcin diglycidyl ether,
2,2-Dibromoneopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate, tris A polyepoxy compound other than the polyepoxy compound (b-2) such as (glycidoxyethyl) isocyanurate;

Examples thereof include melamine formaldehyde condensate; metal salts; metal chelate compounds.
These polyfunctional compounds can also be used alone or in combination of two or more.

These polyisocyanate compounds (b-
1), the amount of polyfunctional compound other than the polyaziridine compound (b-2) and / or the polyepoxy compound (b-3) is based on 100 parts by weight of the acrylic copolymer (A), Usually 0
Is in the range of 3 parts by weight.

The pressure-sensitive adhesive composition for a polarizing film of the present invention comprises, as an essential component, an acrylic copolymer (A) and a functional group capable of reacting with the acrylic copolymer (A) to form a crosslinked structure. Along with the polyisocyanate compound (b-1) having two or more groups, a polyfunctional compound (B) containing a polyaziridine compound (b-2) and / or a polyepoxy compound (b-3),
It contains a silane coupling agent (C) containing a mercapto group or an alicyclic epoxy group.

The present inventors have found that the silane coupling agent often used in pressure-sensitive adhesive compositions for polarizing films is
The effects on the physical properties of the pressure-sensitive adhesive composition, particularly the physical properties such as durability and reworkability, have been investigated. As a result, silane coupling agents containing a mercapto group or an alicyclic epoxy group have significantly higher performance than other silane coupling agents such as 3-triethoxysilylpropylsuccinic acid (anhydride). It was found that it could be improved.

Examples of such a mercapto group- or alicyclic epoxy group-containing silane coupling agent (C) that can be used in the present invention include, for example, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and γ. -A mercapto group-containing silane compound such as mercaptopropyldimethoxymethylsilane, and β- (3,4-
Epoxycyclohexyl) ethyltrimethoxysilane,
Examples thereof include alicyclic epoxy group-containing silane compounds such as β- (3,4-epoxycyclohexyl) ethyltriethoxysilane.

The amount of the silane coupling agent (C) used is 0.15 to 1 based on 100 parts by weight of the acrylic copolymer (A).
It is necessary that the amount is parts by weight, and preferably 0.2 to 0.8 parts by weight. If the amount used is too small below the lower limit value, peeling and other inconveniences are likely to occur, and if it is more than the upper limit value too large, peeling and other inconveniences are likely to occur, which is not preferable.

The pressure-sensitive adhesive composition of the present invention includes the above-mentioned acrylic copolymer (A), the polyisocyanate compound (b-1), the polyaziridine compound (b-2) and / or the polyepoxy. In addition to the polyfunctional compound (B) containing the compound (b-3), and a mercapto group- or alicyclic epoxy group-containing silane coupling agent (C), if necessary, a pressure-sensitive adhesive composition for a polarizing film. Compounds that are usually blended with the product, for example, silane coupling agents other than the silane coupling agent (C), weather resistance stabilizers, tackifiers, plasticizers, softeners, dyes, pigments, inorganic fillers and the like are appropriately blended. can do.

Examples of the silane coupling agent that can be used in combination include 3-triethoxysilylpropylsuccinic acid (anhydride), 3-trimethoxysilylpropylsuccinic acid (anhydride), and 3-methyldimethoxysilylpropylsuccinic acid. Carboxyl group-containing silane compounds such as acid (anhydride), methyldiethoxysilylpropylsuccinic acid (anhydride), 1-carboxy-3-triethoxysilylpropylsuccinic acid (anhydride); for example, N- (β- Aminoethyl) -γ-
Aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β
-Aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and other amino group-containing silane compounds; A hydroxyl group-containing silane compound such as γ-hydroxypropyltrimethoxysilane; an amide group-containing silane compound such as γ-amidopropyltrimethoxysilane; an isocyanate group-containing silane such as γ-isocyanatopropyltrimethoxysilane Examples thereof include system compounds.

The pressure-sensitive adhesive composition for a polarizing film of the present invention comprises the acrylic copolymer (A) and the polyfunctional compound.
The gel content after forming a crosslinked structure with (B) is preferably 40 to 80% by weight, and particularly preferably 50 to 75% by weight. When the gel content is at least the lower limit value, it is possible to suppress inconveniences such as bubbles, and when it is at most the upper limit value, peeling and white spot phenomenon are less likely to occur, which is preferable. The gel content is
It is measured by the following method.

[0097]Measurement of gel content of pressure sensitive adhesive composition Measure according to the following (1) to (7). (1) Apply the pressure-sensitive adhesive composition solution on release paper and let it stand at room temperature.
After air-drying for 30 minutes, fully dry at 100 ° C for 5 minutes.
Form a pressure sensitive adhesive layer. (2) The pressure-sensitive adhesive layer was aged at 23 ° C and 65% relative humidity for 10 days.
To live. (3) The above film on a precisely weighed glass rod (diameter 5 mm x 30 mm)
Approximately 1g of pressure-sensitive adhesive layer is applied, and at 1:00 in the desiccator
Allow to dry. After that, accurately measure the weight with a precision balance
And prepare a sample.

(4) Put the sample obtained in (3) into a cylindrical filter paper (No. 84). (5) About 100 ml of solvent (ethyl acetate) is put into a 200 ml round bottom flask of a Soxhlet extractor, which is precisely weighed, and Soxhlet extraction is carried out for 4 hours. (6) After cooling, the solvent (ethyl acetate) in the round bottom flask is volatilized with a rotary evaporator, and then the round bottom flask containing the above extract is dried at 100 ° C. for 3 hours and in a desiccator for 1 hour. Then, the weight is accurately measured with a precision balance. (7) Calculate the gel content by the following formula. Gel content (wt%) = 100-[(AB) / (CD)] x 100 where A is the weight of the round bottom flask after extraction (g), B is the weight of the round bottom flask (g), and C is the sample. (G), D is the weight (g) of the glass rod.

The pressure-sensitive adhesive composition for a polarizing film of the present invention preferably has a logarithmic decay rate at 30 to 100 ° C. of 0.1 to 0.5, particularly 0.15 to 0.4. If the logarithmic decrement is equal to or more than the lower limit value, peeling and white spotting phenomenon can be prevented from occurring. It is preferable because it is less likely to cause inconvenience. The logarithmic decay rate is a value measured by the following method.

[0100]Measurement of logarithmic decay rate of pressure sensitive adhesive composition Measure according to the following (1) to (3). (1) Apply the solution of the pressure-sensitive adhesive composition to the polyester-based peeling film.
Apply to Rum, dry at 100 ℃ for 2 minutes, 25μm thick pressure sensitive
Form an adhesive layer. (2) The polarizing film is pressure-bonded to the pressure-sensitive adhesive layer, and
After curing for 10 days at 65 ℃ and relative humidity of 65%,
Cut to size. (3) A rigid pendulum tester [TEIC RPT-α100,
Manufactured by A & D Co., Ltd.)
Set. (Conditions) Frame: FRB-10 Measuring unit: RBP-30 Temperature rising rate: 2 ℃ / min

Next, the polarizing film of the present invention will be described. The polarizing film in the present invention is one in which a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition of the present invention described above is formed on at least one surface of a polarizing base film. The pressure-sensitive adhesive layer for sticking to the surface of the supporting substrate is formed in the same manner as the conventional polarizing film, except that the pressure-sensitive adhesive composition of the present invention is formed. . That is, for example, as shown in FIG. 1, the polarizing film 1 in the present invention
Is a polarizing base film 2 comprising a polarizer 2a and protective layers 2b and 2c laminated on both sides of the polarizer 2a, a pressure-sensitive adhesive layer 3 formed on the surface of the protective layer 2c, and It comprises a release paper 4 attached via a pressure-sensitive adhesive layer 3.

The pressure-sensitive adhesive layer 3 preferably has a dry thickness of 10 to 50 μm, particularly 15 to 30 μm.

In the polarizing film of the present invention shown in FIG. 1, the pressure sensitive adhesive layer 3 and the release paper 4 are made of the protective layer 2c.
Although it is provided only on the side, the pressure-sensitive adhesive layer 3 and the release paper 4 may be provided on both the protective layer 2b side and the protective layer 2c side.
Further, the protective layers 2b and 2c may or may not be provided, and instead of the protective layer or together with the protective layer, a layer having other functions such as a reflective layer and an antiglare layer may be provided.

[0104]

EXAMPLES The effects of the present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The preparation of test pieces and various test methods and evaluation methods used in Examples and Comparative Examples are as follows.

[0105](1) Creation of test polarizing film Dry on release paper surface-treated with silicone release agent
Later coating amount is 20 g / m²So that the pressure sensitive adhesive composition
Apply and dry in a hot air circulation dryer at 100 ° C for 90 seconds.
After forming the pressure sensitive adhesive layer, the polarizing base film [poly
Polarizer based on vinyl alcohol (PVA) film
Cellulose triacetate (TAC) film on both sides of
Laminated; about 190 μm] on the back side of the pressure-sensitive adhesive
Laminate it with the layer surface, pass it through a pressure nip roll and crimp it
A light film was obtained.

[0106](2) Initial adhesive strength measurement and adherend surface contamination
Evaluation (Evaluation of reworkability) The polarizing film created in the previous section (1) is scaled to 25 mm × 150 mm.
Then, this piece of polarizing film is laminated on a table.
Using a machine to crimp a 1.1 mm thick soda glass plate for testing
Use as a sample. Autoclave the sample (50
℃, 5kg / cm², 20 minutes), and then at 23 ° C and 65% RH for 24 hours
After leaving for a period of time (conditioning treatment), peeling 180 °
The adhesive force (peeling speed: 300 mm / min) is measured.
Also, visually observe the state of the glass plate surface after peeling.
And evaluate according to the following criteria.

(Evaluation Criteria) ⊚: No abnormal appearance such as cloudy weather can be confirmed. ◯: A thin cloud can be confirmed at the peeling start portion. Δ: A thin cloud can be seen on the entire surface. ×: A dark cloud can be seen on the entire surface.

Among the pressure-sensitive adhesive layers formed from the pressure-sensitive adhesive composition for a polarizing film, those having a high adhesive force that cannot be peeled from the liquid crystal cell (glass cell) are reworkable. Is not preferable. The adhesive force measured by the above method is 1200 g / 25 mm or less, and particularly 1000 g / 25 mm or less is excellent in reworkability, and the adhesive force is 1200 g / 25 mm.
If it exceeds mm, there is a problem in reworkability. In addition, there is also a problem in reworkability when adhesive residue or cloudyness occurs on the glass surface after peeling.

[0109](3) Adhesive force measurement after heat treatment and adherend surface
Evaluation of contamination (evaluation of recyclability) It was created in the same manner as in the previous item (2) and autoclaved.
Allow the test sample to stand for 1 hour at 23 ° C and 65% RH
After that, heat treatment at 70 ℃ for 3 hours, then
After conditioning as in (1), peel 180 °
Measures the adhesive force at peeling (peeling speed: 300 mm / min)
It

The state of the glass plate surface after peeling is visually observed and evaluated according to the following criteria.

(Evaluation criteria) ⊚: No abnormal appearance such as cloudy weather can be confirmed. ◯: A thin cloud can be confirmed at the peeling start portion. Δ: A thin cloud can be seen on the entire surface. ×: A dark cloud can be seen on the entire surface.

Among the pressure-sensitive adhesive layers formed from the pressure-sensitive adhesive composition for a polarizing film, those having a high adhesive strength that cannot be peeled off from the liquid crystal cell (glass cell) are recyclable. Is not preferable. Adhesive strength measured by the above method is 1500 g / 25 mm or less, and especially 1000 g / 25 mm or less is excellent in recyclability, and the adhesive strength is
If it exceeds 1500 g / 25 mm, there is a problem in recyclability.
In addition, there is a problem in recyclability when adhesive residue is left on the glass surface after peeling.

[0113](4) Durability evaluation 70mm cut so that the long side is 45 ° to the absorption axis
Front (2) except using a polarizing film piece of × 140mm (long side)
Create a test sample and autoclave
And condition it as in (2) above.
After treatment, leave for 1000 hours under the following temperature and humidity conditions
Then, evaluate the occurrence of bubbles and the state of peeling by visual observation.
It The evaluation criteria are as follows.

[0114]a) 100 ° C, dry (100 ° C, dry evaluation
Standard) ⊚: No bubbles are observed. ◯: Generation of bubbles having a diameter of less than 100 μm is slightly observed. Δ: Many bubbles having a diameter of 100 to 200 μm are recognized. ×: Many bubbles having a diameter of 200 μm or more are recognized.

[0115]b) 65 ° C, 95% RH (Evaluation basis for 65 ° C, 95% RH
Quasi) A: There is no peeling. ◯: Peeling off within 500 μm. Δ: Peeling less than 2 mm. X: Peeling off of 2 mm or more.

[0116](5) White blank phenomenon evaluation test Align the polarizing plates on both sides of the soda glass plate in the same manner as in (4) above.
The film was attached so that its polarization axes were orthogonal to each other.
Create a test sample and condition it as in (4) above.
After the aging treatment, leave it in the dry condition of 90 ℃ for 24 hours
It Next, using the simple photometric device shown in FIG.
While moving the sample,
The brightness is measured for each point. Evaluation of whiteness is measured
The average value of luminous intensity at
Value divided by the average value of luminance in ,,, and
Represented by At that time, the brightness of the measurement point becomes 0.05 or less.
Adjust the light intensity of the backlight to measure the brightness
To do.

The value measured by the above method is ideally 1.0, but in practice, the value is 2.5 or less, especially 2.0 or less.
In the case of the following, there is practically no white drop phenomenon and no problem in use. However, if this value exceeds 2.5 and becomes large,
A white drop phenomenon is visually recognized, which causes a problem.

[0118]Production of acrylic copolymer (A) Production example 1 Counter equipped with a thermometer, stirrer, nitrogen inlet tube and reflux condenser
In the reactor, 99 parts by weight of n-butyl acrylate (BA),
1 part by weight of phosphoric acid (AA), 100 parts by weight of ethyl acetate and azo
Add 0.2 parts by weight of bisisobutyronitrile (AIBN),
After replacing the air in the reaction vessel with nitrogen gas, stir it under nitrogen.
In an atmosphere, raise the temperature of the reaction vessel to 65 ° C and react for 6 hours
Then, the temperature was further raised to 70 ° C. and the reaction was carried out for 2 hours. That
Then, add 20 parts by weight of ethyl acetate to azobisisobutyronitrile.
A solution in which 0.4 parts by weight was dissolved was added dropwise over 1 hour.
And reacted for 2 hours. After the reaction is complete, the reaction mixture is
Dilute with ene and dissolve the acrylic copolymer with a solid content of 20% by weight.
A liquid was obtained.

The viscosity of the resulting acrylic copolymer solution was 6500 mPa · s, and the acrylic copolymer had a glass transition point (Tg) of about −55 ° C. and a weight average molecular weight (Mw) of about 12
It had a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio Mw / Mn of about 6.7 and a Mark-Hoink plot slope value (a) of 0.75.

Production Examples 2 to 3 In Production Example 1, the initial reaction temperature of 65 ° C. was changed to 70 ° C., and the addition amount of the initial AIBN was 0.2 parts by weight to 0.35 parts by weight or
Acrylic copolymer solutions were obtained in the same manner as in Production Example 1 except that the amount was changed to 0.25 part by weight. The viscosity of the resulting acrylic copolymer solution, and the glass transition point (Tg) of the copolymer, the weight average molecular weight (Mw), and the ratio Mw of the weight average molecular weight (Mw) to the number average molecular weight (Mn). / Mn and mark-
Table 1 shows the gradient values (a) of the Hoink plot.

Production Examples 4-8 In Production Example 1, 99 parts by weight of BA and AA1 were used as monomers.
Acrylic copolymer solutions were obtained in the same manner as in Production Example 1 except that the monomers shown in Table 1 were used instead of using parts by weight. The viscosity of the resulting acrylic copolymer solution, and the glass transition point (Tg) of the copolymer, the weight average molecular weight (Mw), and the ratio Mw of the weight average molecular weight (Mw) to the number average molecular weight (Mn). / Mn and the slope value (a) of the Mark-Hoink plot are shown in Table 1.

Production Example 9 An acrylic copolymer solution was produced in the same manner as in Example 1 of JP-A-9-145925. That is, in the same reactor used in Production Example 1, 94 parts by weight of BA, 6 parts by weight of AA, 100 parts by weight of ethyl acetate and the silane coupling agent (C) were used.
Γ-mercaptopropyltrimethoxysilane (trade name: Sila Ace S810; manufactured by Chisso Corporation) (S810) is 0.
[0097] Incorporation of parts by weight and nitrogen bubbling for 30 minutes were performed to substantially remove dissolved oxygen. Then, the content temperature of the reaction vessel was raised to 60 ° C. under a nitrogen atmosphere with stirring, 0.03 part by weight of AIBN was added, and the reaction was carried out for 7 hours. After the reaction was completed, the reaction mixture was diluted with toluene to give a solid content of 20% by weight.
An acrylic copolymer solution of was obtained. The viscosity of the resulting acrylic copolymer solution, and the glass transition point (Tg), weight average molecular weight (Mw), weight average molecular weight (M
Table 1 shows the ratio Mw / Mn of w) to the number average molecular weight (Mn) and the gradient value (a) of the Mark-Hoink plot.

Production Example 10 An acrylic copolymer solution similar to that described in Example 1 of JP-A-9-269413 was produced. However, since the publication only discloses a schematic production method, the polymerization reaction was carried out according to Example 1 with respect to unclear points. That is, 95 parts by weight of BA, 5 parts by weight of AA, 100 parts by weight of toluene and 0.1 part by weight of benzoyl peroxide (BPO) were placed in the same reactor used in Production Example 1, and the air in the reaction vessel was replaced with nitrogen gas. After substituting with, the content temperature of the reaction vessel was raised to 65 ° C. and reacted for 6 hours in a nitrogen atmosphere with stirring, and further raised to 70 ° C. and reacted for 2 hours. Then, a solution of 0.4 parts by weight of azobisisobutyronitrile dissolved in 20 parts by weight of ethyl acetate was added dropwise over 1 hour, and the reaction was continued for 2 hours. After completion of the reaction, the reaction mixture was diluted with toluene to obtain an acrylic copolymer solution having a solid content of 20% by weight. The viscosity of the resulting acrylic copolymer solution, and the glass transition point (Tg) of the copolymer,
Table 1 shows the weight average molecular weight (Mw), the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn), and the gradient value (a) of the Mark-Hoink plot.

The abbreviations of the monomers in Table 1 are as follows. EHA: 2-ethylhexyl acrylate BA: butyl acrylate EA: ethyl acrylate MA: methyl acrylate MMA: methyl methacrylate AA: acrylic acid HEA: 2-hydroxyethyl acrylate

[0125]

[Table 1]

[0126]Production of pressure-sensitive adhesive composition for polarizing film Example 1 As the acrylic copolymer (A), the acrylic copolymer of Production Example 1
500 parts by weight of copolymer solution (about 100 parts by weight as a copolymer)
Polyisocyanate as a polyfunctional compound (B).
Nate compound (b-1) [trade name: Takenate D-120N; Take
(Danaku Kogyo Co., Ltd.) (D-120N) 2.0 parts by weight (active ingredient
About 1.5 parts by weight), and silane coupling agent (C)
Γ-mercaptopropyltrimethoxysilane [Product
Name: Cyla Ace S810; manufactured by Chisso Corporation] (S810) 0.3
Add parts by weight, stir well and pressure-sensitive adhesive for polarizing film
A solution of the agent composition was obtained. Using this pressure sensitive adhesive composition
Then, the above-mentioned logarithmic decay rate and gel content were measured. Got
Composition of pressure-sensitive adhesive composition and its characteristic value
The viscosity of the solution of the composition, the logarithm of the pressure-sensitive adhesive layer after crosslinking
The attenuation rate and gel content are shown in Table 2.

Next, the obtained solution of the pressure-sensitive adhesive composition for polarizing film was applied to a polyester release film and then dried. The coating thickness after drying at this time is 25 μm.
I adjusted it to be. Next, the pressure-sensitive adhesive layer applied on this release film was transferred onto a polarizing base film and aged for 10 days under the conditions of a temperature of 23 ° C. and 65% RH to obtain a polarizing film.

With respect to the obtained polarizing film, reworkability, recyclability, durability and white drop phenomenon were evaluated according to the above-mentioned test methods. The results obtained are shown in Table 4.

Examples 2-11 and Comparative Examples 1-6 In Example 1, the polyisocyanate compound "Takenate D-120N" was used as the solid content as the polyfunctional compound (B).
Instead of using 1.5 parts by weight and 0.3 parts by weight of "Sila Ace S810" as the silane coupling agent (C), as shown in Table 2, the type and / or amount of the polyfunctional compound (B) is changed, and / or A solution of the pressure-sensitive adhesive for a polarizing film was obtained in the same manner as in Example 1, except that the type and / or amount of the silane coupling agent (C) was changed or not used. Using these pressure-sensitive adhesive compositions,
The logarithmic decay rate and gel content were measured in the same manner as in Example 1 below. Table 2 shows the compounding composition of the obtained pressure-sensitive adhesive composition, its characteristic values, that is, the viscosity of the solution of the composition, the logarithmic decrement of the pressure-sensitive adhesive layer after crosslinking, and the gel content.

Polarizing films were obtained in the same manner as in Example 1 using these pressure-sensitive adhesive solutions, and reworkability, recyclability, durability and white blanking phenomenon were evaluated according to the above-mentioned test methods. . The results obtained are shown in Table 4.

Examples 12 to 16 and Comparative Examples 7 to 8 In Example 1, instead of using the acrylic copolymer solution of Production Example 1 as the acrylic copolymer (A), Production Examples 2 to 8 were used. A pressure sensitive adhesive solution for a polarizing film was obtained in the same manner as in Example 1 except that the acrylic copolymer solution was used. Using these pressure-sensitive adhesive compositions,
The logarithmic decay rate and gel content were measured in the same manner as in Example 1 below. Table 3 shows the composition of the obtained pressure-sensitive adhesive composition, its characteristic values, that is, the viscosity of the solution of the composition, the logarithmic decrement of the pressure-sensitive adhesive layer after crosslinking, and the gel content.

Polarizing films were obtained in the same manner as in Example 1 using these pressure-sensitive adhesive solutions, and the reworkability, recyclability, durability and white spot phenomenon were evaluated according to the above-mentioned test methods. . The results obtained are shown in Table 4.

Comparative Example 9 In Example 1, instead of using the acrylic copolymer solution of Production Example 1 as the acrylic copolymer (A), the acrylic copolymer solution of Production Example 9 was used. 2.0 parts by weight of `` D-120N '' as the functional compound (B) (1.
5 parts by weight), 3.5 parts by weight of "L" (about 2.63 parts by weight as an active ingredient), and tributylamine 0.
Solutions of the pressure-sensitive adhesive for polarizing films were obtained in the same manner as in Example 1 except that 5 parts by weight was added and the silane coupling agent (C) was not used. Using this pressure-sensitive adhesive composition, the logarithmic decay rate and gel content were measured in the same manner as in Example 1 below. Table 3 shows the composition of the obtained pressure-sensitive adhesive composition, its characteristic values, that is, the viscosity of the solution of the composition, the logarithmic decrement of the pressure-sensitive adhesive layer after crosslinking, and the gel content.

Using these pressure-sensitive adhesive solutions, polarizing films were obtained in the same manner as in Example 1, and reworkability, recyclability, durability and white spot phenomenon were evaluated according to the above-mentioned test methods. . The results obtained are shown in Table 4.

Comparative Example 10 In Example 1, the acrylic copolymer solution of Production Example 10 was used instead of the acrylic copolymer solution of Production Example 1 as the acrylic copolymer (A). 2.0 parts by weight of `` D-120N '' as the functional compound (B) (1.
5 parts by weight) Instead of using 1.0 part by weight of "L" (about 0.75 parts by weight as an active ingredient) and 1.0 part by weight of glycerol diglycidyl ether (GDG), a silane coupling agent
Instead of using 0.3 part by weight of "S810" as (C), 3-triethoxysilylpropylsuccinic anhydride [trade name: GF-2
0; manufactured by Wacker-Chemie GmbH] (GF-20) was used in the same manner as in Example 1 to obtain a pressure-sensitive adhesive solution for a polarizing film. Further tributylamine 0.
Solutions of the pressure-sensitive adhesive for polarizing films were obtained in the same manner as in Example 1 except that 5 parts by weight was added and the silane coupling agent (C) was not used.

Polarizing films were obtained in the same manner as in Example 1 using these pressure-sensitive adhesive solutions, and reworkability, recyclability, durability and white spot phenomenon were evaluated according to the above-mentioned test methods. . The results obtained are shown in Table 4.

The polyfunctional compounds shown in Tables 2 and 3
The abbreviations for (B) and silane coupling agent (C) are as follows.

D-120N: "Takenate D-120N" Hydrogenated xylylene diisocyanate / trimethylolpropane adduct, about 75% by weight of active ingredient [Takeda Pharmaceutical Co., Ltd.] D-110N: "Takenate D-110N" Xylylene diisocyanate / trimethylolpropane adduct, active ingredient approx.
75 wt% [Takeda Pharmaceutical Co., Ltd.] N75: "Sumijour N75" hexamethylene diisocyanate trimer (biuret type), active ingredient about 75 wt%
[Sumitomo Bayer Urethane Co., Ltd.] HL: “Coronate HL” hexamethylene diisocyanate / trimethylol propane adduct, 75% by weight of active ingredient [Nippon Polyurethane Co., Ltd.] HX: “Coronate HX” hexamethylene diisocyanate / 3 Polymer (isocyanurate type), active ingredient about 100% by weight [Nippon Polyurethane Co., Ltd.] L: "Coronate L" tolylene diisocyanate / trimethylolpropane adduct, active ingredient about 75% by weight [Nippon Polyurethane Co., Ltd.] Made)

TAZO: “TAZO” Tetramethylolmethane-
Tris (β-aziridinyl propionate), about 1 active ingredient
00 wt% [Mutual Yakuko Co., Ltd.] TAZM: "TAZM" trimethylolpropane-tris (β-aziridinyl propionate), about 100 wt% active ingredient [Mutual Yakuko Co., Ltd.]

TET-C: “TETRAD-C” 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane [Mitsubishi Gas Chemical Co., Ltd.
Co., Ltd.] TET-X: "TETRAD-X" N, N, N ', N'-tetraglycidyl-m-
Xylylenediamine, active ingredient about 100% by weight [Mitsubishi Gas Chemical Co., Inc.] GDG: Glycerol diglycidyl ether, active ingredient about 1
00% by weight

S810: "Sila Ace S810" γ-mercaptopropyltrimethoxysilane, about 100% by weight of active ingredient
[Manufactured by Chisso Corporation] S530: "Sila Ace S530" β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, about 100% by weight of active ingredient [Manufactured by Chisso Corporation] S510: "Sila Ace S510" γ-gly Sidoxypropyltrimethoxysilane, about 100% by weight of active ingredient [Chisso
GF-20: 3-triethoxysilylpropyl succinic anhydride, about 100% by weight of active ingredient [Wacker-Chemie GmbH]

[0142]

[Table 2]

[0143]

[Table 3]

[0144]

[Table 4]

[0145]

The pressure-sensitive adhesive composition for a polarizing film of the present invention has an acrylic copolymer having a weight average molecular weight and a glass transition temperature (Tg) within a specific range and having a carboxyl group in the molecule. With respect to (A), a specific polyisocyanate compound (b-1) a specific amount and / or a polyepoxy compound as a polyfunctional compound (B) having reactivity with the component (A)
(b-2) The silane coupling agent (C) containing a specific amount and a mercapto group or an alicyclic epoxy group is contained in a specific amount range.

The pressure-sensitive adhesive composition for a polarizing film of the present invention having the above-mentioned constitution can sufficiently prevent peeling, foaming and white spotting phenomenon, and is excellent in reworkability and recyclability. Moreover, the adherend is not contaminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a polarizing film having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention.

FIG. 2 is a conceptual diagram of an apparatus used for an evaluation test of a white drop phenomenon.

FIG. 3 is a conceptual diagram showing measurement points in an evaluation test of a white blank phenomenon.

[Explanation of symbols]

1: Polarizing film 2: Polarization base film 2a: Polarizer 2b, 2c: protective layer 3: Pressure-sensitive adhesive layer 4: Release paper 5: Simple photometric device 6: Light source 7: Diffuser 8: Luminance meter 9: Glass plate 10: Test sample 11: Shading plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) G02F 1/1335 510 G02F 1/1335 510 (72) Inventor Masami Uemae 53 Yoneyama Minami-cho, Sano City, Tochigi Prefecture Japan Carbide Kogyo Co., Ltd. House F-term (reference) 2H091 FB02 FB12 FD16 GA17 LA02 LA03 LA04 LA05 LA06 LA09 LA12 LA30 4J040 DF041 DF051 DF061 EC231 EC232 EF291 EF301 GA01 GA07 GA11 GA14 GA22 HD35 HD37 JB09 LA01 LA02 MA05 MB03 NA17 NA20 PA20

Claims (8)

[Claims] 1. The following (A) to (C): (A) Weight average molecular weight of 800,000 or more, glass transition temperature (Tg)
Based on 100 parts by weight of an acrylic copolymer having a carboxyl group in the molecule at −45 ° C. or lower, (B) a functional group capable of reacting with the acrylic copolymer (A) component to form a crosslinked structure. It contains two or more groups and has the following (b-1), (b-2) and / or
(b-3) a polyfunctional compound containing; (b-1) a polyisocyanate compound derived from hexamethylene diisocyanate, xylylene diisocyanate or hydrogenated xylylene diisocyanate as an active ingredient
0.15 to 3 parts by weight, (b-2) tetramethylolmethane tris (β-aziridinyl propionate) or trimethylolpropane tris (β
-Aziridinyl propionate) is a polyaziridine compound as an active ingredient 0.001 to 0.1 parts by weight, (b-3) 1,3-bis (N, N-glycidylaminomethyl) cyclohexane or N, N, N A polyepoxy compound that is', N'-tetraglycidyl-m-xylenediamine is used as an active ingredient.
A pressure-sensitive adhesive for a polarizing film, containing 0.005 to 0.3 part by weight and (C) 0.15 to 1 part by weight of a silane coupling agent containing a mercapto group or an alicyclic epoxy group as essential components. Agent composition. 2. The acrylic copolymer (A) contains a repeating unit derived from an acrylic ester and a methacrylic ester in a total amount of 50% by weight or more based on the acrylic copolymer. The pressure-sensitive adhesive composition according to claim 1. 3. The acrylic copolymer (A) comprises the following monomer (a-
1) to (a-4), (a-1) the following general formula (1), H ₂ C = CHCOOR ¹ (1) (wherein R ¹ is a linear or branched alkyl group having 4 to 10 carbon atoms). Acrylic ester whose homopolymer has a glass transition temperature (Tg) of -50 ° C or lower 69.5 ~
99.5% by weight, (a-2) 0.5-
1.5% by weight, (a-3) a monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule, other than the monomer (a-2) Monomer 0 to 1% by weight (a-4) Copolymerizable with the above monomers (a-1) to (a-3), other than the monomers (a-1) to (a-3) 0 to 30% by weight of the comonomer of [wherein the total amount of the monomers (a-1) to (a-4) is 100% by weight] is copolymerized. The pressure-sensitive adhesive composition described. 4. A monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule,
The pressure-sensitive adhesive composition according to claim 3, wherein the monomer (a-3) other than the monomer (a-2) is a monomer having a hydroxyl group in the molecule. 5. The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic copolymer (A) is a low branching degree polymer. 6. The pressure-sensitive adhesive composition according to claim 1, 3 or 5, wherein the acrylic copolymer (A) has a Mark-Houink plot gradient (a) of 0.3 to 1.5. 7. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a gel content of 40 to 80% by weight based on the weight thereof after the crosslinked structure is formed. Any one of 6
The pressure-sensitive adhesive composition according to the item. 8. The feeling according to claim 1, wherein the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a logarithmic decay rate at 0.1 to 0.5 at 30 to 100 ° C. Pressure-adhesive composition.