KR102032016B1 - Pressure-sensitive adhesive composition for polarization plates, pressure-sensitive adhesive sheet for polarization plates, polarization plate with pressure-sensitive adhesive layer, laminate body and flat panel display - Google Patents

Abstract

INDUSTRIAL APPLICATION This invention can be used suitably for bonding a polarizing plate and various optical members (especially a thin transparent substrate), can effectively suppress the curvature of the said member in a thermal environment, can effectively prevent light leakage, and is also suitable for a tool. An object of the present invention is to provide an adhesive composition having excellent processing characteristics such as no adhesion. The present invention
(A): (meth) acrylic resin which contains the structural unit derived from the monomer of following (a1)-(a4) in the following ratio;
(a1) 5-50 weight% of (meth) acrylic-type monomers whose Tg of a homopolymer is 0 degreeC or more.
(a2) 43-93.9 weight% of (meth) acrylic-type monomer whose Tg of homopolymer is -60 degreeC or more and less than 0 degreeC
(a3) 1.1-7 weight% of (meth) acrylic-type monomer which has a carboxyl group (a4) 0-10 weight% of other monomers
(B): 0.15-1.5 weight part crosslinking agent with respect to 100 weight part of said (meth) acrylic resins,
(C): It is an adhesive composition for polarizing plates containing a silane coupling agent.

Description

PRESSURE-SENSITIVE ADHESIVE COMPOSITION FOR POLARIZATION PLATES, PRESSURE-SENSITIVE ADHESIVE SHEET FOR POLARIZATION PLATES, POLARIZATION PLATE WITH PRESSURE-SENSITIVE ADHESIN LAYER, LAMP BODY AND FLAT PANEL DISPLAY}

This invention is used for adhesion | attachment with a polarizing plate and an optical member, for example, a thin transparent substrate, and is excellent in the processing characteristic at room temperature, and becomes an adhesive excellent in stress relaxation property at the time of heating, and curvature of the said optical member is fully suppressed. Laminating which the transparent substrate is laminated | stacked on the adhesive layer of the adhesive composition for polarizing plates, the adhesive sheet for polarizing plates which have the adhesive layer containing this composition, the polarizing plate with an adhesive layer in which the said adhesive layer was formed at least on one side, and the adhesive layer of the said polarizing plate with adhesive layer. It relates to a flat panel display having a sieve and a polarizing plate or a laminate with the pressure-sensitive adhesive layer.

With respect to the pressure-sensitive adhesive for the field of flat panel displays (FPD), the demand for high image quality, high quality, and high durability is increasing with the increase of the size of the display, the spread of the LED system, and the reduction of the display device.

For example, a liquid crystal display (LCD) classified as FPD is formed of a liquid crystal panel, a backlight and a peripheral circuit, which is typically composed of each layer of a polarizing plate, a glass substrate having transparent electrodes, a color filter, and the like. The glass substrate has the structure containing the liquid crystal cell which clamped the liquid crystal.

The said polarizing plate is comprised by the multilayered structure of a heterogeneous material (polarizing film which consists of a polyvinyl alcohol-type film which adsorbed and oriented iodine or a dichroic dye, the protective film which consists of triacetyl cellulose, etc.), and each material differs from each other physical and chemical Has characteristics. Therefore, especially in the manufacture of FPD, there is a process performed in an environment of high temperature and high humidity, and in the case of LCD, the temperature rises to about 40 to 60 ° C. due to heat from the backlight, but under such heat environment, shrinkage and The extent of the dimensional change of each layer which comprises the polarizing plate by swelling differs, and its different extent is also large. For this reason, a polarizing plate lacks dimensional stability as a whole.

And by this dimension change, various influences generate | occur | produce various performance represented by light leakage and durability as the whole polarizing plate. Moreover, it is known that the said light leakage, durability, etc. generate | occur | produce also according to the adhesive type used for adhesion | attachment of optical films, such as a polarizing plate, and adhesion of a liquid crystal cell (glass substrate) and a polarizing plate.

In the present situation, the combination of polarizing plate type and adhesive type supports the above various required performances, but the required performances are required to be higher, such as high image quality and high durability, with large screens and thinner displays. have.

Here, with respect to the pressure-sensitive adhesive species, in order to solve the light leakage caused by the dimensional change of the polarizing plate, the peeling under a high temperature and high humidity environment, pay attention to various properties of the polymer constituting the pressure-sensitive adhesive, expressing good light leakage prevention performance and In order to secure high durability, a review has been made.

For example, in patent documents 1 and 2, the amount of creep by load under normal temperature or high temperature of the adhesive layer which adhere | attaches a polarizing plate and a predetermined optical member with a polarizing plate is made large, and a polarizing plate is made to follow an adhesive layer to a polarizing plate. A technique for relieving the stress acting on the optical member by the dimensional change of the optical fiber and thereby improving the display unevenness of the liquid crystal display device has been proposed. However, especially when the amount of creep is large at room temperature, the processing characteristics are inferior, such as contamination due to the sticking out of the pressure-sensitive adhesive, slippage, adhesion to the blade, and the like, in work processes such as punching and bonding.

Then, as an adhesive which reduced the adhesive which cuts out from the cut-off surface, the adhesive which the creep amount in room temperature is small and the increase amount of the creep amount by the increase of temperature in a constant temperature range is more than a fixed value was proposed (patent Document 3).

Moreover, in patent document 4, it contains 70 weight% or more of n-butyl (meth) acrylates, and does not contain a carboxyl group-containing monomer or contains less than 2 weight% with respect to the adhesive used for bonding of a touchscreen structural member. The double-sided adhesive tape using the acrylic adhesive layer obtained by superposing | polymerizing a monomer component is proposed. Since there is no examination about the hard characteristic and crosslinking design of an adhesion layer in this document, when the adhesive tape which has the said adhesion layer is used for bonding of a polarizing plate and a liquid crystal cell (glass substrate of), durability and a process characteristic of an adhesion layer are Insufficient and light leakage is also concerned.

Patent document 5 is a monomer having a C2-C18 alkyl (meth) acrylic acid ester of a linear or branched alkyl group as an adhesive having durability that can suppress warpage of an optical film such as a polarizing plate even when placed in a low temperature environment. The weight average molecular weight of 30-2.5 million acrylic polymer which makes a unit a main frame | skeleton, and copolymerizes the copolymerization monomer copolymerized with the said (meth) acrylic-acid alkylester as a monomer unit is contained as a base polymer, and Tg is -35 degreeC The optical adhesive layer which is the following is proposed.

In addition, Patent Document 6 contains an acrylic polymer (A), an ionic compound (B), and a crosslinking agent (C) each composed of the following monomer components (a1) to (a4) and having a weight average molecular weight of 1 million or more. The adhesive composition for optical films whose gel fraction after crosslinking is 60 weight% or more is disclosed: Monomer component (a1); n-butyl (meth) acrylate 10-89.9 mass% monomer component (a2); 5-50 mass% of specific (meth) acrylic-acid alkylester monomers

Monomer component (a3); Monomer 5-40 mass% monomer component (a4) which has an alkylene oxide group; 0.1-10 mass% of monomers containing a hydroxyl group

Patent Literature 7 contains an acrylic copolymer containing 0.1 to 1% by weight of a repeating unit having a carboxyl group and 0.01 to 0.5% by weight of a repeating unit having a hydroxyl group in the molecule (A) (however, the weight of the acrylic copolymer is 100% by weight. %), Based on 100 parts by weight of the acrylic copolymer having a weight average molecular weight (Mw) of not less than 800,000 and a glass transition temperature (Tg) of -40 ° C or less, (B) 0.3 to 3 parts by weight of a polyisocyanate compound, And (C) a pressure-sensitive adhesive composition for polarizing films comprising 0.05 to 5 parts by weight of a mercapto group or an alicyclic epoxy group-containing silane coupling agent as an essential component,

Patent Document 8 has an adhesive tape having at least one layer of a polyacrylate-based pressure-sensitive adhesive having a weight average molecular weight M _w in the range of 200,000 ≤ M _w ≤ 1 million g / mol, wherein the polyacrylate is ( a) 55 ~ 92% by weight of one or a plurality of types of the general formula CH ₂ = acrylic monomer of the CH-COOR ₁ (R ₁ is meant a hydrocarbon residue of a C4 ~ C14, and component (a) homopolymer of the monomer of Glass transition temperature _{TG, aH} of a polymer is -20 degrees C or less), and (b) 5-30 weight% of 1 type or multiple types of copolymerizable monomers (glass transition temperature of homopolymer of monomer of component (b)) T _{G, bH} is 0 ° C. or more), and (c) 3 to 15% by weight of one or plural kinds of copolymerizable monomers which promote crosslinking reaction of polyacrylates, The adhesive tape, wherein the polyacrylate satisfies specific parameters It has set forth.

Japanese Laid-Open Patent Publication 2001-272541 Japanese Unexamined Patent Publication No. 2003-50313 Japanese Laid-Open Patent Publication 2001-350020 Japanese Unexamined Patent Publication No. 2010-215794 Japanese Laid-Open Patent Publication 2011-17009 Japanese Laid-Open Patent Publication 2012-131963 Japanese Unexamined Patent Publication No. 2004-224873 Japanese Patent Publication No. 2012-531498

As described above, with the increase in size and thickness of display devices, and the spread of LED systems, demands for various characteristics are becoming more advanced.

In particular, regarding thinning, a transparent substrate (which is a constituent layer of a liquid crystal cell laminated on a polarizing plate via an adhesive, and typically a glass substrate) is used for a liquid crystal cell with a dimensional change during shrinkage of the polarizing plate due to a thermal environment. It is known that bending occurs. In recent years, the thickness of a transparent substrate has become very thin, for example, 0.4 mm or less, and the said warping has become the more likely to generate | occur | produce.

For this reason, even if the adhesive proposed by patent documents 1-3 is used, when a polarizing plate is bonded with such a thin transparent substrate, the curvature of the said board | substrate cannot fully be suppressed and light leakage will arise.

Therefore, this invention can be used suitably for bonding a polarizing plate and various optical members (especially thin transparent substrate), can effectively suppress the curvature of the said member in a thermal environment, and can effectively prevent light leakage, An object of the present invention is to provide an adhesive composition having excellent processing characteristics such as poor adhesion.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, as for the (meth) acrylic resin which comprises an adhesive, it showed a good hard characteristic at room temperature, and showed the outstanding processing characteristic, and also the flexibility at the time of heating It is designed to reduce the stress applied to the optical member (especially a thin transparent substrate), and such a (meth) acrylic resin is combined with a certain amount of crosslinking agent to control the degree of crosslinking within a certain range, and furthermore, the silane coupling agent By mix | blending and improving adhesiveness with respect to the optical member of an adhesive, it discovered that the said subject could be solved and came to complete this invention.

That is, this invention is (A): (meth) acrylic resin which contains the structural unit derived from the monomer of following (a1)-(a4) in the following ratio; (a1) 5-50 weight% of (meth) acrylic monomers whose Tg of a homopolymer is 0 degreeC or more (a2) 43-93.9 weight% of (meth) acrylic monomers whose Tg of a homopolymer is -60 degreeC or more and less than 0 degreeC (a3) carboxyl group 1.1-7 weight% of (meth) acrylic-type monomer which has (a4) Other monomer 0-10 weight%

(B): It is an adhesive composition for polarizing plates containing 0.15-1.5 weight part crosslinking agent with respect to 100 weight part of said (meth) acrylic resins, and (C): silane coupling agent.

From the viewpoint of achieving both a hard property at room temperature and flexibility in heating, it is preferable that the (meth) acrylic monomer (a1) is a (meth) acrylic monomer having an alkyl group having 3 to 8 carbon atoms having a branch, and t- It is more preferable that they are butyl (meth) acrylate and / or isobutyl methacrylate.

The gel fraction of the adhesive composition for polarizing plates of this invention is 50 to 80% of range normally.

The adhesive composition for polarizing plates of this invention has a fixed hardness at room temperature, and is excellent in processing characteristics. Specifically, when the following micro creep test is performed on the composition, the creep value at 23 ° C. is preferably 0.3 mm or less:

The adhesive composition for polarizing plates is apply | coated and dried on the peeling process polyester film, and the adhesive sheet which has an adhesive layer with a film thickness of 25 micrometers is manufactured;

The pressure-sensitive adhesive sheet is bonded so that the polarizing plate and the pressure-sensitive adhesive layer are in contact with the polarizing plate to produce a pressure-sensitive adhesive polarizing plate for evaluation, and aged for 7 days in a dark place at 23 ° C / 50% RH;

The pressure-sensitive adhesive polarizing plate for evaluation was cut to 10 mm in width x 100 mm in length, and the peeled polyester film was peeled off, and on the alkali-treated glass, the adhesive layer was in contact with the glass. Bonding them together so as to form a bonding area to obtain a pressure-sensitive adhesive polarizing plate test piece for evaluation;

Autoclave treatment (50 degreeC, 5 atm) is performed with respect to the tackifying polarizing plate test piece for evaluation, and it is left to stand in 23 degreeC / 50% RH atmosphere for 24 hours;

Next, the said test piece is set to 15 mm in length of the chuck | zipper part for fixation in the chamber BOX of a micro creep measuring device;

The laminated body of the said adhesive layer and the polarizing plate in the said test piece was made into the said laminated body and the said glass in the said test piece after heating in the said chamber BOX to measurement temperature, and leaving still for 40 minutes at a measurement temperature, with a tensile load of 800 g and a tensile time of 1000 second. Pull parallel to the adhesive surface of the laminate and in the longitudinal direction of the laminate;

The shifted distance (mm) of the bonded part of the said glass and a laminated body in the said test piece is measured as a creep value.

Moreover, since the adhesive composition for polarizing plates of this invention shows favorable softness at the time of heating, when the said micro creep test is performed, the ratio of the creep value in 60 degreeC and the creep value in 23 degreeC (60 degreeC creep) Value / 23 ° C creep value) is preferably 1.4 or more.

In the said (meth) acrylic resin (A), Preferably, the ratio of the structural unit derived from the said (meth) acrylic-type monomer (a1) is 5-45 weight%, In the said (meth) acrylic-type monomer (a2) The ratio of the structural unit derived is 49.5 to 90 weight%, the ratio of the structural unit derived from the said (meth) acrylic-type monomer (a3) is 1.5 to 5.5 weight%, and the structural unit derived from the said other monomer (a4) The ratio of is 0-5 weight%.

From the viewpoint of the good hard property at room temperature of the adhesive composition for polarizing plates of this invention, the weight average molecular weight of the said (meth) acrylic resin (A) becomes like this. Preferably it is 500,000-2 million.

In the adhesive sheet for polarizing plates of this invention, the adhesive layer containing the adhesive composition for polarizing plates of this invention is formed on a base film.

In the polarizing plate with an adhesive layer of this invention, the adhesive layer containing the adhesive composition for polarizing plates of this invention is formed in at least single side | surface of a polarizing plate.

The pressure-sensitive adhesive composition of the present invention is particularly preferably used for bonding a polarizing plate and a transparent substrate having a thickness of 0.3 mm or less, and a transparent substrate having a thickness of 0.3 mm or less is provided on the pressure-sensitive adhesive layer of the polarizing plate with a pressure-sensitive adhesive layer obtained by performing such bonding. The laminated body formed by lamination is also included in this invention.

For example, a flat panel display is manufactured by passing through various manufacturing processes using the polarizing plate or laminated body with an adhesive layer demonstrated above.

The adhesive composition for polarizing plates of this invention can be used suitably for bonding of a polarizing plate and various optical members. Since the composition exhibits good hard properties at room temperature, the composition is excellent in processing characteristics, and exhibits flexibility in heating, thereby alleviating stress applied to the optical member by the dimensional change of the polarizing plate, and as a result, the member, in particular a thin transparent substrate. Warping at the time of heating is suppressed favorably.

1 is a light leakage size R in a screen of a 19 inch size liquid crystal panel used for evaluation of light leakage characteristics in Examples, and a luminance measurement portion (La, in a 1 cm diameter area around each corner); Lb, Lc, Ld) and the luminance measurement part Lcenter in the 1 cm diameter area of a monitor center part are shown.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

[Adhesive Composition for Polarizing Plate]

The adhesive composition for polarizing plates of the present invention (hereinafter also referred to simply as "composition of the present invention") is as described above with a specific (meth) acrylic resin (A), a specific amount of a crosslinking agent (B), and a silane coupling agent (C ). Hereinafter, each of these components is demonstrated. In addition, in this specification, (meth) acryl means methacryl or acryl, and (meth) acrylate means methacrylate or acrylate.

[(A) (meth) acrylic resin]

The (meth) acrylic resin (A) constituting the composition of the present invention contains the structural units derived from the specific monomers (a1) to (a4) as described above in a specific ratio (derived from other monomers (a4)). It does not need to contain the structural unit to make). Hereinafter, the monomer used as each structural unit is demonstrated.

<(A1) (meth) acrylic monomer>

The said (meth) acrylic resin (A) contains the structural unit derived from the (meth) acrylic-type monomer (a1) whose glass transition temperature (Tg) of a homopolymer is 0 degreeC or more. In addition, Tg of the homopolymer of the said (meth) acrylic-type monomer (a1) is 200 degrees C or less normally. Thus, the structural unit derived from the monomer with high Tg of a homopolymer contributes to the outstanding hard characteristic at room temperature of the (meth) acrylic resin (A) and also the composition of this invention containing it.

In the present specification, unless the Tg is specifically mentioned, the test piece (homopolymer) for measuring Tg is heated at a rate of 10 ° C / min in a range of -60 ° C to 180 ° C under N ₂ atmosphere, and DSC It is the glass transition temperature calculated | required by calorimetric measurement with (differential scanning calorimeter DSC8230). The measurement is performed in accordance with JIS K 7121 (Method of Measuring Transition Temperature of Plastics).

Moreover, about the glass transition temperature (Tg (degreeC)) of a homopolymer, the glass transition temperature (Tg (K) of various homopolymers (homopolymer) described in "POLYMERHANDBOOK 3rd edition" (Issued by John Wiley & Sons, Inc.) See also)). For reference, Tg of the homopolymer of some various monomers (including monomers other than a (meth) acrylic monomer) is shown in following Table 1 (it is a ° C unit display).

The (meth) acrylic monomer (a1) is not particularly limited as long as it satisfies the requirements of Tg. Examples thereof include (meth) acrylates having an alkyl group having 1 to 20 carbon atoms, and the number of carbon atoms of the alkyl group. 3-8 are preferable from a viewpoint of making compatible the favorable hard characteristic at room temperature and the favorable flexibility at the time of heating.

Moreover, it is preferable that (meth) acrylic-type monomer (a1) is (meth) acrylate which has the alkyl group which has a branch from a same viewpoint.

As a specific example of such a (meth) acrylic-type monomer (a1), methyl (meth) acrylate, ethyl methacrylate, propyl (meth) acrylate, i-propyl methacrylate, n-butyl methacrylate, iso Butyl methacrylate, t-butyl (meth) acrylate, pentyl acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, tetradecyl acrylate, hexadecyl (meth) acrylate and stearyl (Meth) acrylate is mentioned.

Among these, t-butyl (meth) acrylate and isobutyl methacrylate are preferable from said viewpoint, and t-butyl (meth) acrylate is especially preferable. Moreover, in this invention, the (meth) acrylic-type monomer (a1) demonstrated above may be used individually by 1 type, and may be used in combination of 2 or more type.

<(A2) (meth) acrylic monomer>

The (meth) acrylic resin (A) used for this invention contains the structural unit derived from the (meth) acrylic-type monomer (a2) whose Tg of a homopolymer is -60 degreeC or more and less than 0 degreeC. Thus, the structural unit derived from the monomer with low Tg of a homopolymer contributes to the outstanding flexibility at the time of heating of the (meth) acrylic resin (A) and the adhesive composition for polarizing plates of this invention containing it further.

Although the said (meth) acrylic-type monomer (a2) is not specifically limited as long as Tg of a homopolymer exists in the said range, Preferably it is (meth) acrylate which does not have rigid structure like an aromatic ring. In addition, in this specification, the said aromatic ring is a structure in which the valence which has (pi) electrons was arranged in cyclic form, satisfy | fills the Whikel rule, the (pi) electron delocalized, and points out that the said ring has a planar structure.

Specific examples of such a (meth) acrylic monomer (a2) include ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl methacrylate, isopentyl acrylate and hexyl ( Meth) acrylate, heptyl acrylate, isoamyl acrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl (meth) acrylate, n-nonyl acrylate, isononyl acrylate, n- Decyl (meth) acrylate, isodecyl (meth) acrylate, n-lauryl acrylate, and n-tridecyl (meth) acrylate.

Among these, n-butylacrylate is preferable from a viewpoint of achieving the outstanding flexibility at the time of heating with respect to the composition of this invention. Moreover, in this invention, the (meth) acrylic-type monomer (a2) demonstrated above may be used individually by 1 type, and may be used in combination of 2 or more type.

<(A3) (meth) acrylic monomer>

The (meth) acrylic resin (A) used for this invention contains the structural unit derived from the (meth) acrylic-type monomer (a3) which has a carboxyl group. In the (meth) acrylic resin (A) in the composition of the present invention, a part of the carboxyl groups of the structural unit derived from the monomer (a3) is involved in the crosslinking by the action of the crosslinking agent (B) described later, and partly Is not crosslinked, and is considered to form a hydrogen bond (the carboxyl group which does not form a crosslinked hydrogen bond is also considered to exist). When heating, since this hydrogen bond is cut | disconnected, it is thought that the flexibility of the (meth) acrylic resin (A) containing the said structural unit rises.

Moreover, crosslinking formation (and formation of a hydrogen bond) by a carboxyl group is important for demonstrating the effect of this invention, For example, with crosslinking by a hydroxyl group, the effect of this invention is not acquired.

The (meth) acrylic monomer (a3) is not particularly limited as long as it has a carboxyl group, and specific examples thereof include (meth) acrylic acid, β-carboxyethyl (meth) acrylate, and (meth) acrylate β-carboxyethyl. And carboxyl group-containing (meth) acrylates, such as 5-carboxypentyl (meth) acrylic acid, mono (meth) acryloyloxyethyl ester, and ω-carboxypolycaprolactone mono (meth) acrylate.

Among these, acrylic acid is preferable from the viewpoint of achieving excellent flexibility during heating. Moreover, in this invention, (meth) acrylic-type monomer (a3) may be used individually by 1 type, and may be used in combination of 2 or more type.

<(A4) other monomers>

In the present invention, structural units derived from other monomers (a4) other than the monomer components (a1) to (a3) for the adjustment of various properties within the range not impairing the effects of the present invention, It can be made to contain in a meth) acrylic resin (A).

As an example of such another monomer (a4),

As the hydroxyl group-containing monomer, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) Hydroxyl group-containing (meth) acrylates such as acrylate and 8-hydroxyoctyl (meth) acrylate;

As an amino group containing monomer, amino group containing (meth) acrylates, such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, are mentioned, for example;

As an amide group containing monomer, it is (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-hexyl (meth) acryl, for example. Amide and dimethylaminoethyl (meth) acrylate;

As a nitrogen-type heterocyclic containing monomer, vinylpyrrolidone, acryloyl morpholine, and vinyl caprolactam are mentioned, for example.

Moreover, in the monomer which has a (meth) acrylic structure, when an ester part has an alkylene oxide group, a side chain is easy to move and since the hard property in room temperature of the adhesive composition for polarizing plates of this invention tends to worsen, It is preferable that the (meth) acrylic resin (A) used for the said composition does not contain the structural unit derived from the (meth) acryl monomer which has an alkylene oxide group.

In this invention, the other monomer (a4) demonstrated above may be used individually by 1 type, and may be used in combination of 2 or more type.

<The manufacturing method of (meth) acrylic resin (A)>

The (meth) acrylic resin (A) described above is a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method for each monomer component (a1) to (a3) and, if necessary, other monomers (a4). It can manufacture by superposing | polymerizing by conventionally well-known polymerization methods, such as these. Among these methods, since the adjustment of the molecular weight of resin is easy and there is little mixing of impurities into a reaction system, it is preferable to employ the solution polymerization method.

In the solution polymerization method, copolymerization is performed by dissolving or dispersing a mixture of the monomer components forming the (meth) acrylic resin (A) in the reaction solvent by adding an organic solvent as a reaction solvent and adding a polymerization initiator under stirring. Conduct the reaction.

As said organic solvent, For example, ester solvents, such as ethyl acetate; Ketone solvents such as methyl ethyl ketone, formaldehyde and acetoaldehyde; Ether solvents such as dimethyl ether; Aromatic solvents such as toluene and xylene; Alicyclic solvents such as cyclohexane; And aliphatic solvents such as hexane and octane. These solvent may be used individually by 1 type, and may be used as 2 or more types of mixed solvent.

Moreover, as said polymerization initiator, 2,2'- azobisisobutyronitrile (AIBN), 2,2'- azobis (4-methoxy-2, 4- dimethylvaleronitrile), 2,2 ' Azo compounds, such as-azobis-2, 4- dimethylvaleronitrile and 1,1'- azobiscyclohexane-1-carbonitrile; Isobutyryl peroxide, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxy neodecanoate, di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, di-sec -Butyl peroxydicarbonate, 1,1,3,3, -tetramethylbutylperoxy neodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, benzoyl peroxide, di-tert-butylperoxide, lau Royl peroxide, tert-butyl-oxy-2-ethylhexanoate, and the like. These can be used individually by 1 type or in combination of 2 or more type.

In the solution polymerization method, the reaction temperature of the copolymerization reaction using these reaction solvents and a polymerization initiator is usually in the range of 50 to 90 ° C, preferably 60 to 85 ° C, and the reaction time is usually 1 to 10 hours. Preferably, it is 2 to 8 hours and reaction pressure is normal pressure-0.1 Mpa normally.

By changing the injection amount of each monomer component in these polymerizations, and various conditions, the ratio, weight average molecular weight, molecular weight distribution, etc. of each structural unit in (meth) acrylic resin (A) mentioned later can be adjusted.

<Characteristics of (meth) acrylic resin (A)>

For example, the (meth) acrylic resin (A) manufactured by the method mentioned above has the structural unit derived from the (meth) acrylic-type monomer (a1) whose Tg of a homopolymer is 0 degreeC or more, and thereby it is at room temperature It is excellent in the hard characteristic, and the adhesive composition for polarizing plates of this invention is excellent in processing characteristic. Moreover, the said (meth) acrylic resin (A) has a structural unit derived from the (meth) acrylic-type monomer (a2) whose Tg of a homopolymer is -60 degreeC or more and less than 0 degreeC, and the part of this structural unit is flexible at the time of heating. By suppressing the bending of optical members such as a transparent substrate due to the change in the heating dimension of the polarizing plate, good light leakage preventing performance is achieved. Moreover, the said (meth) acrylic resin (A) has a structural unit derived from the (meth) acrylic-type monomer (a3) which has a carboxyl group, and a part of said carboxyl group is bridge | crosslinked by the crosslinking agent (B) mentioned later, and of this invention The hard property at room temperature of a composition is raised and a processing property is raised as a result. On the other hand, it is thought that the hydrogen bond formed by the carboxyl group is cut | disconnected at the time of heating, The structural unit derived from the said monomer (a3) at the time of heating gives the composition of this invention the flexibility at the time of heating, and the curvature of the said optical member It is thought to contribute to the suppression of and to improve the light leakage prevention performance.

In such a (meth) acrylic resin (A), the structural unit derived from the said (meth) acrylic-type monomer (a1) occupies 5-50 weight% in 100 weight% of all the structural units, and the said (meth) acrylic-type monomer The structural unit derived from (a2) occupies 43-93.9 weight% in 100 weight% of all the structural units, and the structural unit derived from the said (meth) acrylic-type monomer (a3) is 1.1- in 100 weight% of all structural units. Occupies 7% by weight. In addition, the sum total of the structural unit derived from these monomers (a1)-(a3) is 90 weight% or more and 100 weight% or less. Moreover, (meth) acrylic resin (A) may contain the structural unit derived from the said other monomer (a4), and the ratio becomes 0 to 10 weight% in 100 weight% of all the structural units.

If the ratio of the structural unit derived from the said (meth) acrylic-type monomer (a1) is less than 5 weight%, (meth) acrylic resin (A) cannot exhibit sufficient hard characteristic in room temperature, and the composition of this invention is processed When the characteristic falls and exceeds 50% by weight, the hard characteristic becomes excessive, the flexibility at the time of heating becomes insufficient, and it becomes difficult to suppress the warping of the optical member. From such a point, the ratio of the structural unit derived from a (meth) acrylic-type monomer (a1) becomes like this. Preferably it is 5-48 weight%, More preferably, it is 5-45 weight%.

If the proportion of the structural unit derived from the (meth) acrylic monomer (a2) is less than 43% by weight, the flexibility at the time of heating becomes insufficient, while if it exceeds 93.9% by weight, the pressure-sensitive adhesive becomes too soft, and the pressure-sensitive adhesive comes out. , Scratches on the surface, a decrease in punching aptitude, and the like occur. From such a point, the ratio of the structural unit derived from a (meth) acrylic-type monomer (a2) becomes like this. Preferably it is 46-92 weight%, More preferably, it is 49.5-90 weight%.

If the ratio of the structural unit derived from the said (meth) acrylic-type monomer (a3) is less than 1.1 weight%, sufficient crosslinking rate cannot be achieved, the hard characteristic in room temperature will become inadequate, and the composition of this invention will have processing characteristics. It falls. On the other hand, when the said ratio exceeds 7 weight%, crosslinking rate will become high too much, the flexibility at the time of heating will become inadequate, and it will become difficult to suppress the curvature of an optical member. From such a point, the ratio of the structural unit derived from a (meth) acrylic monomer (a3) becomes like this. Preferably it is 1.3-6 weight%, More preferably, it is 1.5-5.5 weight%.

If the ratio of the structural unit derived from the said other monomer (a4) is 0 to 10 weight%, the various characteristics of the composition of this invention can be adjusted, without impairing the effect of this invention. The proportion of the structural unit derived from the other monomer (a4) is preferably 0 to 5% by weight.

The injection weight ratio of each monomer component at the time of manufacturing a (meth) acrylic resin (A) is reflected in the quantity of the structural unit derived from these (meth) acrylic-type monomers (a1)-(a4).

The weight average molecular weight of the (meth) acrylic resin (A) containing the various structural units demonstrated above is 500,000 or more normally. By setting it as such a weight average molecular weight, the favorable hard characteristic in room temperature is provided to (meth) acrylic resin (A), and the composition of this invention has favorable processing characteristic.

In addition, in this specification, a weight average molecular weight shall refer to the weight average molecular weight of standard polystyrene conversion measured by GPC, and the weight average molecular weight of (meth) acrylic resin (A) becomes like this from the said viewpoint, Preferably it is 50 It is 1 million-2 million, More preferably, it is 1 million-2 million.

Moreover, the molecular weight distribution (Mw / Mn) of the said (meth) acrylic resin (A) is normally 2 from a viewpoint of the processing characteristic which arises from the contamination with respect to the to-be-adhered body at the time of rework, and the adhesive composition becomes soft. It is -10, Preferably it is 4-8, Tg is -55-0 degreeC normally from a viewpoint of aptitude wettability, an adhesive characteristic, and a hard characteristic.

[(B) crosslinking agent]

Next, the crosslinking agent (B) which the adhesive composition for polarizing plates of this invention contains is demonstrated. The crosslinking agent (B) causes a crosslinking group and a crosslinking reaction in the carboxyl group of the (meth) acrylic monomer (a3) and, if present, the structural unit derived from the other monomer (a4), and the gel of the composition of the present invention. The fraction is adjusted to a predetermined range described later. Thereby, while ensuring good adhesiveness of a polarizing plate and its to-be-adhered body, it is thought that the said composition exhibits favorable flexibility at the time of heating, suppresses the curvature of an optical member, and achieves the favorable light leakage prevention performance. Moreover, a hydroxyl group, a carboxyl group, an epoxy group, an amino group, an amide group, a tertiary amino group etc. are mentioned as an example of the said crosslinkable group.

The crosslinking agent (B) is not particularly limited as long as it can cause a crosslinking reaction with the (meth) acrylic resin (A). Examples thereof include an isocyanate crosslinking agent, a metal chelate crosslinking agent and an epoxy crosslinking agent.

As a specific example of the said isocyanate type crosslinking agent, tolylene diisocyanate, chlorphenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenyl Isocyanate monomers, such as methane diisocyanate; Isocyanate compound which added these isocyanate monomers to trimethylol propane etc .; Isocyanurate compound; Burette type compound; Furthermore, the urethane prepolymer type isocyanate which carried out addition reaction with a well-known polyether polyol, polyester polyol, acryl polyol, polybutadiene polyol, polyisoprene polyol, etc. is mentioned.

As the metal chelate crosslinking agent, isopropyl alcohol, acetylacetone, ethyl acetoacetate, or the like is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium or zirconium. The compound etc. which were mentioned are mentioned.

Specific examples thereof include aluminum isopropylate, diisopropoxybisacetylacetone titanate, and aluminum triethylacetoacetate.

Specific examples of the epoxy-based crosslinking agent include ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis (N, N-diglyl). Cydylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl-m-xylylenediamine, N, N, N', N'-tetraglycidylaminophenylmethane, triglycidyl Isocyanurate, mN, N- diglycidylaminophenylglycidyl ether, N, N- diglycidyl toluidine and N, N- diglycidyl aniline.

The crosslinking agent (B) demonstrated above may be used individually by 1 type, and may be used in combination of 2 or more type. Such a crosslinking agent (B) is contained 0.15-1.5 weight part with respect to 100 weight part of (meth) acrylic resins (A) in the adhesive composition for polarizing plates of this invention.

By containing a certain amount of crosslinking agent (B) in this way, an appropriate degree of crosslinking (gel fraction) is achieved for the composition of the present invention, and good hard property at room temperature (which leads to good processing properties) and good flexibility at heating. (This leads to suppression of the prevention of the warpage of the adherend of the polarizing plate, whereby good light leakage prevention performance is achieved). From such a viewpoint, content of the said crosslinking agent (B) becomes like this. Preferably it is 0.3-1.2 weight part with respect to 100 weight part of (meth) acrylic resins (A).

[(C) Silane Coupling Agent]

The adhesive composition for polarizing plates of this invention contains a silane coupling agent (C). A silane coupling agent (C) forms bonds, such as a chemical bond, with various to-be-adhered bodies, and improves the adhesiveness of a polarizing plate and a to-be-adhered body. It is especially effective for adhesion with a glass substrate.

As said silane coupling agent (C), Polymerizable unsaturated-group containing silicon compounds, such as vinyl trimethoxysilane, vinyl triethoxysilane, and methacryloxypropyl trimethoxysilane; Silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; And 3-chloropropyltrimethoxysilane; And oligomeric silane coupling agents.

Of these, the use of a silane coupling agent having a functional group that reacts with a functional group (such as a carboxyl group) contained in the (meth) acrylic resin (A) is preferable in that it is difficult to cause peeling from the adherend of the polarizing plate in a moist heat environment. Do.

The compounding quantity of the silane coupling agent (C) in the composition of this invention is 0.01-0.3 weight part normally with respect to 100 weight part of (meth) acrylic resins (A), Preferably it is 0.05-0.25 weight part. Moreover, a silane coupling agent (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

[Other components]

In the adhesive composition for polarizing plates of this invention, an antistatic agent, antioxidant, a ultraviolet absorber, a coloring agent, a pigment, dye, tackifying resin, a surface lubricant, a leveling agent, a softener, an antioxidant, a light stabilizer, a photoinitiator, and a polymerization prohibition as needed. You may contain other components, such as a filler, an organic particle, an inorganic particle, or a plasticizer. The composition of the present invention may contain 5 to 50 parts by weight of an acrylic copolymer having a weight average molecular weight Mw of less than 100,000, which does not contain a crosslinkable functional group, based on 100 parts by weight of the (meth) acrylic resin (A) as the softener. . Moreover, the composition of this invention may contain the solvent and other solvent used for manufacture of (meth) acrylic resin (A).

[Adhesive Composition for Polarizing Plate]

The adhesive composition for polarizing plates of this invention contains the (meth) acrylic resin (A) demonstrated above, a specific amount of crosslinking agent (B), and a silane coupling agent (C).

It is thought that (meth) acrylic resin (A) has the various structural units exhibiting the favorable hard characteristic in room temperature, and the flexibility at the time of heating. The composition of this invention containing such a (meth) acrylic resin (A) is excellent in processing characteristic.

In addition, due to the presence of a specific amount of the crosslinking agent (B), the gel fraction of the composition of the present invention is usually from 50 to 80%, and because of this, good hard properties at room temperature are achieved, and the gel fraction is not too high. In heating, the composition becomes soft. Thereby, it is assumed that the stress applied to the adherend (optical member such as a transparent substrate) is alleviated by the dimensional change of the polarizing plate at the time of heating. As a result, the warpage of the adherend is suppressed, and good light leakage prevention performance is achieved. do.

Moreover, in the specific composition of this invention, since the gel fraction is adjusted to the said specific range, the cohesion force of a composition is enough and the stress relaxation property at the time of heating is also excellent. Therefore, the composition of this invention is excellent also in wet heat durability, for example, even if it becomes an adhesive layer mentioned later and puts in a wet heat environment, foaming and heat insulation hardly generate | occur | produce in the said adhesive layer.

Moreover, since the composition of this invention contains a silane coupling agent (C), a polarizing plate and a to-be-adhered body can fully be adhere | attached.

Since the composition of this invention has the favorable hard characteristics at room temperature as mentioned above, the creep value in 23 degreeC is 0.5 mm or less when the following micro creep test is performed. In view of practicality such as processing characteristics, the creep value at 23 ° C is preferably 0.3 mm or less.

Smile creep test

The adhesive composition for polarizing plates of this invention is apply | coated and dried on the peeling process polyester film, and the adhesive sheet which has an adhesive layer with a film thickness of 25 micrometers is manufactured.

The pressure sensitive adhesive sheet is bonded so that the polarizing plate and the pressure sensitive adhesive layer are in contact with the polarizing plate to produce a pressure-sensitive adhesive polarizing plate for evaluation, and are aged for 7 days in a dark place at 23 ° C / 50% RH.

The pressure-sensitive adhesive polarizing plate for evaluation was cut to 10 mm in width x 100 mm in length, and the peeled polyester film was peeled off, and on the alkali-treated glass, the adhesive layer was in contact with the glass. It bonds so that it may become a bonding area, and it sets it as the adhesive polarizing plate test piece for evaluation.

The pressure-sensitive adhesive polarizing plate test piece for evaluation is subjected to autoclave treatment (50 ° C., 5 atm) and allowed to stand for 24 hours in a 23 ° C./50% RH atmosphere.

Next, the said test piece is set to 15 mm in length of the chuck | zipper part for fixation in the chamber BOX of a micro creep measuring device.

The laminated body of the said adhesive layer and the polarizing plate in the said test piece was made into the said laminated body and the said glass in the said test piece after heating in the said chamber BOX to measurement temperature, and leaving still for 40 minutes at a measurement temperature, with a tensile load of 800 g and a tensile time of 1000 second. It is pulled in parallel to the adhesive surface of and also in the longitudinal direction of the laminate.

The shift distance (mm) of the bonded part of the said glass and a laminated body in the said test piece is measured, and let this be a creep value.

Moreover, since the composition of this invention shows favorable flexibility at the time of heating as mentioned above, the creep value in 60 degreeC in the case of performing the said micro creep test is 0.2 mm or more. From the viewpoint of effectively preventing warpage of the optical member and achieving good light leakage preventing performance, the creep value at 60 ° C is preferably 0.3 mm or more.

In addition, in order to effectively prevent the warping of the optical member, it is also important that the flexibility of the composition of the present invention rises by a certain level or more when the temperature is raised from room temperature to a heated state, specifically, a creep value at 60 ° C. and 23 ° C. It is necessary that ratio of creep value in (60 degreeC creep value / 23 degreeC creep value) is 1.3 or more. In consideration of actual use, the ratio is preferably 1.4 or more, more preferably 1.5 or more, and usually the ratio is 25 or less.

<Use of the pressure-sensitive adhesive composition for polarizing plate>

The adhesive composition for polarizing plates of this invention demonstrated above is excellent in both the hard characteristics at room temperature and the flexibility at the time of heating, and it is favorable in processing characteristics, suppresses the curvature of the adherend of a polarizing plate, and shows the outstanding light leakage prevention performance.

For this reason, the composition of this invention is suitable for the bonding use of a polarizing plate and various optical members. In particular, the composition of the present invention can be used for bonding an optical member having a very thin, for example, bonding of a transparent substrate having a thickness of 0.4 mm or less (in a liquid crystal cell) and a polarizing plate, which are recently employed in the field of display devices. The curvature at the time of the heating of a transparent substrate can be suppressed.

In particular, in recent years, even thinner layers have been used, and transparent substrates having a thickness of 0.3 mm or less have also been used. However, the composition of the present invention is also preferable for bonding applications of such very thin transparent substrates and polarizing plates. It is difficult to generate warpage.

<The manufacturing method of the adhesive composition for polarizing plates>

The manufacturing method of the adhesive composition for polarizing plates of this invention is not restrict | limited, The composition of this invention is obtained by mixing the various structural components of the composition mentioned above by a well-known method. Moreover, you may use a solvent in order to mix well.

In addition, the prepared composition of the present invention is usually cured for a certain period of time (for example, 3 to 7 days at room temperature (23 ° C. 50% RH) and 2 to 5 days at 40 ° C. 90% RH under accelerated heating). (Maturation), and the crosslinking reaction is advanced to a certain degree, adjusted to the appropriate gel fraction, and used.

[Adhesive sheet]

When using the adhesive composition for polarizing plates of this invention as an adhesive, when an adhesive layer is formed on a base film and it is an adhesive sheet, handling is easy and convenient.

When the said base film considers handling property, such as when using the said adhesive sheet in the manufacturing process of a flat panel display, it is preferable that it is a peeling film, As the material, it is polyester, polyolefin, polyether, for example. Etc. can be mentioned.

The adhesive sheet of this invention can be manufactured by apply | coating and drying the coating liquid containing the composition of this invention on a base film, for example, vaporizing the solvent etc. contained in a coating liquid, and forming an adhesive layer of desired thickness. . Although the thickness of the said adhesive layer is not specifically limited, The range of 5-100 micrometers is preferable, and the range which is 10-50 micrometers is more preferable. If the thickness of this adhesive layer is less than 5 micrometers, predetermined performance (wet heat durability etc.) may not be exhibited, and when it exceeds 100 micrometers, the processing characteristic at the time of cutting an adhesive sheet may fall.

Moreover, in the adhesive sheet of this invention, the surface which does not contact the said base film surface of the said adhesive layer may be coat | covered with a peeling film, and the said peeling film may be peeled off at the time of use.

[Polarizing Plate with Adhesive Layer]

By forming the adhesive layer containing the adhesive composition for polarizing plates of this invention in the at least single side | surface of a polarizing plate, the polarizing plate with an adhesive layer which is excellent in processing characteristic and the outstanding light leakage prevention performance was achieved also in a thermal environment as mentioned above is obtained. .

Since the composition of this invention is excellent in the flexibility at the time of heating as mentioned above, it is transparent substrates, such as a glass substrate (preferably thickness 0.4mm or less, More preferably thickness 0.3 on the adhesive layer of the said polarizing plate with an adhesive layer) In the laminated body which laminated | stacked the thing of mm or less, even if it is hard to apply stress to the said transparent substrate by the dimension change of a polarizing plate, even if it heats, curvature hardly arises.

<Manufacturing method of the polarizing plate with an adhesive layer>

The polarizing plate with an adhesive layer of this invention is manufactured by the following (1)-(3) methods, for example.

(1) The coating liquid containing the adhesive composition for polarizing plates of this invention is apply | coated to the peeling layer of a peeling film by a well-known method (die coat method, knife coat method, etc.), and the solvent etc. which are contained in a coating liquid by thermal drying, etc. Is vaporized, and the adhesive layer which has a desired thickness is formed, and this is bonded together with a polarizing plate.

(2) The coating liquid containing the composition of this invention is apply | coated to a polarizing plate by a well-known method (die coat method, knife coat method, etc.), the solvent etc. contained in a coating liquid are vaporized by heat drying, and a desired thickness is made The adhesive layer which has is formed, and this is bonded together to the peeling layer of a peeling film.

(3) The coating liquid containing the composition of this invention is apply | coated to the peeling layer of a 1st peeling film by a well-known method (die coat method, knife coat method, etc.), and the solvent etc. which are contained in a coating liquid by heat drying are It vaporizes, the adhesive layer which has a desired thickness is formed, this is bonded together with the peeling layer (usually lower peeling force than a 1st peeling film) of a 2nd peeling film, and a noncarrier adhesive film is manufactured. Then, a 2nd peeling film is peeled off and an adhesive layer is bonded together with a polarizing plate.

Moreover, although the thickness of the adhesive layer in the polarizing plate with an adhesive layer obtained is not specifically limited, The range of 5-100 micrometers is preferable, and the range which is 10-50 micrometers is more preferable. If the thickness of this adhesive layer is less than 5 micrometers, predetermined performance may not be exhibited, and when it exceeds 100 micrometers, the processing characteristic at the time of cutting the polarizing plate with an adhesive layer may fall.

In the composition of this invention, as mentioned above, after formation of the said adhesive layer, it cures for a fixed period and advances a crosslinking reaction. And after adjusting to an appropriate gel fraction, the said adhesive layer can be affixed on the structural layer etc. of the flat panel display mentioned later.

[Flat panel display]

For example, by bonding a polarizing plate, a transparent substrate, etc. using the adhesive composition for polarizing plates of this invention (as a result, the laminated body demonstrated in the term of the said [polarizing plate with an adhesive layer] is obtained), the outstanding anti-bending performance as mentioned above Based light leakage prevention performance is achieved.

It is possible to manufacture a flat panel display using such a polarizing plate and the composition of the present invention, and the FPD thus produced is also included in the scope of the present invention.

As FPD, a liquid crystal display (LCD), a plasma display (PDP), a field emission type display (FED), etc. are mentioned.

LCDs generally have a liquid crystal layer sandwiched by a glass substrate having a transparent electrode, an alignment film or color filter is formed between the glass substrate and the liquid crystal layer, and a polarizing plate is formed on the surface opposite to the surface close to the liquid crystal layer of the glass substrate. It is a structure which has a laminated body structure formed.

In general, a PDP has a laminate structure in which a phosphor layer exists between opposing glass substrates, and various dielectric layers, electrodes, and other functional layers are formed on a surface close to the phosphor layer of the glass substrate.

The FED generally includes a glass substrate, an anode electrode (anode) formed on the substrate, a phosphor layer formed on the electrode, a vacuum space, and a glass substrate on which a cathode electrode (cathode) is formed, facing the phosphor layer with the space therebetween. It has a structure having a laminate structure of.

The polarizing plate with an adhesive layer of this invention or the laminated body which laminated | stacked the transparent substrate thereon comprises a part of constituent layers of these FPDs. Moreover, it is also possible to laminate | stack at least one part of the structural layer of FPD one by one using the adhesive sheet of this invention.

Example

Hereinafter, an Example demonstrates this invention in detail.

<Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of (meth) acrylic resin>

The weight average molecular weight of (meth) acrylic resin is calculated | required by standard polystyrene conversion on the following conditions by GPC (gel permeation chromatography).

<GPC measurement condition>

Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC column configuration: the following five consecutive columns (all manufactured by Tosoh Corporation)

(1) TSK-GEL HXL-H (guard column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

Sample concentration: Dilute with tetrahydrofuran to 1.0 mg / cm 3

Mobile phase solvent: tetrahydrofuran

Flow rate: 1.0 cm 3 / min

Column temperature: 40 ℃

[Production example of (meth) acrylic resin]

(Meth) acrylic monomer (a1), (meth) acrylic monomer (a2), (meth) acrylic monomer (a3) and other monomers (a4) in a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube. Was injected according to the blending ratios shown in Tables 2 and 3 below (units of the numerical values related to the monomers in the table were parts by weight), and then ethyl acetate was injected at a blending amount such that the monomer concentration was 50 wt%.

Subsequently, 0.1 weight part of 2,2'- azobisisobutyronitrile is added with respect to a total of 100 weight part of a monomer component, stirring is carried out while substituting air in a reaction container with nitrogen gas, and it heated up at 60 degreeC, and then 4 The reaction was time. After the completion of reaction, the mixture was diluted with ethyl acetate to obtain a (meth) acrylic resin solution.

In addition, the meaning of the symbol in Table 1 and 2 is as follows.

AA: acrylic acid

BA: n-butyl acrylate

t-BA: t-butyl acrylate

MMA: Methyl methacrylate

MA: Methylacrylate

i-BMA: Isobutyl methacrylate

HEA: 2-hydroxyethyl acrylate

[Manufacture of Adhesion Processing Polarizing Plate for Evaluation]

Using the (meth) acrylic resin solution obtained by the said manufacture example, the compounding of solid table | surfaces Tables 6-6 (solid content mix, numerical value are 100 weight part with respect to (meth) acrylic resin (it shows a "sticker")). Each component was mixed and the solution of the adhesive composition was obtained.

The adhesive sheet which has a 25-micrometer-thick adhesive layer was obtained by apply | coating and drying the solution of this adhesive composition on the surface of the peeled-processed polyester film. After this adhesive sheet is affixed on one side of a polarizing film (TAC (triacetylcellulose) -PVA (polyvinyl alcohol) -TAC constitution), it is aged for 7 days on 23 degreeC / 50% RH dark conditions, and the adhesive processing polarizing plate for evaluation Got.

[evaluation]

Various evaluation demonstrated below was performed using the obtained adhesive processing polarizing plate for evaluation. These evaluation results are also shown together in Tables 4-6 of the later.

<Gel fraction>

The obtained adhesive composition was apply | coated and dried on the surface of the PET film in which peeling process was performed so that the thickness after drying might be set to 20 micrometers. Then, the PET film to which the peeling process was performed was similarly bonded to the other surface of the apply | coated adhesive composition, and it was set as the test piece. The test piece was stored at 23 ° C. and 50% RH, and about 0.1 g of the pressure-sensitive adhesive was taken from the test piece into the sample bottle every day from immediately after the start of storage (day 0), and 30 cc of ethyl acetate was added thereto to infiltrate for 24 hours. The contents of the sample bottle were filtered off with a 200 mesh stainless steel wire mesh, and the residue weight after drying for 2 hours at 100 ° C. on the wire mesh was taken as dry weight. Based on these values, the gel fraction was measured by the following formula.

Gel fraction (%) = (dry weight / adhesive weight taken) × 100

In addition, the gel fraction in Tables 4-6 shows the gel fraction measured value after aging is completed and stabilized.

<Smile creep test>

The adhesive-processing polarizing plate for evaluation was cut into a width of 10 mm × 100 mm in length, and the adhesive-processing polarizing plate for evaluation, which had been stripped from the exfoliated polyester film, was further exposed on the alkali-treated glass so that the pressure-sensitive adhesive layer was in contact with the glass. It bonded together so that it might become a 10 mm bonding area, autoclave process (50 degreeC, 5 atm) was performed, and it left still for 24 hours in 23 degreeC / 50% RH atmosphere after that. This was used as the sample for micro creep test.

The test sample set was implemented by the length of 15 mm of the chuck | zipper part for fixation in the chamber BOX of a micro creep measuring device (model name: TA.TX.PLUS made by Eco Seiki Co., Ltd.). After the inside of the chamber BOX was heated to the measurement temperature and left at the measurement temperature for 40 minutes, the laminate and the laminate of the pressure-sensitive adhesive layer and the polarizing film in the sample for micro creep test were subjected to a tensile load of 800 g and a tensile time of 1000 seconds. Pulled parallel to the adhesive side of the glass and in the longitudinal direction of the laminate. The deviation distance (mm) of the bonded part of the said glass and the laminated body after pulling out was confirmed (measured), and it was set as the micro creep test result.

<Light leakage characteristic>

(Light leak size R)

A pressure-sensitive adhesive polarizing plate for evaluation obtained by peeling a polyester film subjected to peeling treatment to a 19-inch size liquid crystal panel is bonded to the glass substrate of the liquid crystal panel so that the pressure-sensitive adhesive layer contacts the glass substrate of the liquid crystal panel, and the polarizing plate and the liquid crystal panel are cross nicol. It was left to stand for 240 hours, and it was left to stand in 23 degreeC / 50% RH atmosphere for 2 hours.

Then, the liquid crystal panel which bonded the said polarizing plate was connected to PC in the dark room, and it was set as full screen black display. In this state, the part where light leakage generate | occur | produced visually was confirmed, and the distance from the corner of the said screen of the light leakage generation part was measured as FIG. 1, and it was set as light leakage size R (mm). If R is 30 mm or less, use as a panel for liquid crystal displays is possible.

(ΔL (Cd / ㎡))

In the full screen black display state, luminance (L, Lb, Lc, Ld) in the area of 1 cm in diameter near each corner and luminance Lcenter in the area of 1 cm in diameter in the center of the monitor are measured by a luminance meter (highland). It measured using RISA-COLOR / CD8) and the light leakage ((DELTA) L) was calculated | required by the following formula.

Formula: ΔL = (La + Lb + Lc + Ld) / 4-Lcenter

Smaller ΔL (Cd / m 2) means less light leakage (from backlight), and if it is usually less than 2.0, it can be used as a liquid crystal display panel.

<Bending>

An adhesive adhesion polarizing plate for evaluation of 130 mm × 230 mm was bonded to 0.3 mm × 150 mm × 250 mm borosilicate-based glass so as to cross nicol, and an Auto Clave treatment (50 ° C. 5 atm) was performed. After the Auto Clave treatment, the mixture was allowed to stand for 72 hr in a 70 ° C atmosphere.

Then, the degree of curvature of the said glass was measured using the steel plate, and it was set as the bending evaluation result. Usually, if it is 2 mm or less, Preferably it is 1 mm or less, More preferably, it is 0.5 mm or less, it can be used practically without a problem.

<Processing characteristic>

With respect to the pressure-sensitive adhesive polarizing plate for evaluation, punching was performed 10,000 times in a predetermined mold, and the adhesion of the pressure-sensitive adhesive to the blade was visually determined. Evaluation criteria are as follows.

○: no attachment, △: slightly attached, ×: attached

<Foaming and heat insulation>

Adhesion-processed polarizing plate for peeling off the exfoliated polyester film was bonded to an alkali-free glass of 19 inch size to form a test plate, which was foamed after standing for 500 hr in a test environment (60 ° C / 95% RH). The external appearance change of heat insulation was visually confirmed, and it evaluated according to the following criteria. In addition, foaming is caused by lack of cohesion due to low crosslinking degree, and thermal insulation is caused by lack of stress relaxation force due to excessively high crosslinking degree.

Foam-size

○: no foaming at all

△: diameter of foam is 1 mm or less

X: The diameter of foaming is larger than 1 mm

Foaming amount

○: no foaming at all

△: number of foam is 10 or less

×: the number of foam is more than 10

Insulation-Size

○: not visible at all

(Triangle | delta): A generation area is less than 5% with respect to the whole bonded part in a test plate (100%).

X: The generation area is 5% or more relative to the entire bonded portion (100%) in the test plate.

Insulation-position

○: no

(Triangle | delta): There exists a fault only in the position less than 0.5 mm from an edge part.

X: There exists a fault in the position of 0.5 mm or more from an edge part.

The composition of the adhesive composition of an Example and a comparative example and the said various evaluation result are put together in the following Tables 4-6, and are shown.

In addition, the meaning of the symbol in Tables 4-6 is as follows.

L-45: TDI type isocyanate compound (L-45 by Soken Chemical Co., Ltd.)

TD: XDI type isocyanate compound (TD-75 by Mitsui Takeda Pharmaceutical Co., Ltd.)

Al chelate: Al chelate compound (E-5XM manufactured by Soken Chemical Co., Ltd.)

Tetrid C: 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd.)

KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

In Comparative Example 1, since the amount of the crosslinking agent used did not satisfy the lower limit specified in the present invention, the gel fraction was very low, and foaming occurred due to the lack of cohesive force, so that light leakage and bending could not be measured.

In Comparative Example 2, the amount of the crosslinking agent exceeded the upper limit specified in the present invention, the gel fraction was very high, and the ratio between the 60 ° C. creep value and the 23 ° C. creep value was about 1, and the stress caused by the dimensional change of the polarizing plate at the time of heating. This was not alleviated and the warpage was large and light leakage occurred.

The comparative example 3 used resin which does not contain the structural unit derived from a (meth) acrylic-type monomer (a1), A 23 degreeC creep value was large, fell in the hard characteristic at room temperature, and fell in the processing characteristic. Light leakage also occurred.

The comparative example 4 used resin which does not contain the structural unit derived from a (meth) acrylic-type monomer (a1) and a (meth) acrylic-type monomer (a3), but contains the structural unit derived from the monomer which has a hydroxyl group, The warpage was large.

In Comparative Example 5, the ratio of the structural unit derived from the (meth) acrylic monomer (a3) was less than the lower limit of the ratio defined in the present invention, and the resin containing the structural unit derived from the monomer having a hydroxyl group was used. Insufficient processing characteristics resulted in large warpage and thermal insulation. Although hydroxyl group also reacts with a crosslinking agent and forms bridge | crosslinking, it turns out that the effect of this invention is not acquired by it.

The comparative example 6 uses the same resin as the comparative example 5, and doubles the usage-amount of a crosslinking agent. Although the processing characteristics and heat insulation improved because the amount of crosslinking increased, it was considered that the stress relaxation at the time of heating was inadequate, and curvature and light leakage generate | occur | produced.

Comparative Example 7 is an example of using a pressure-sensitive adhesive composition having a composition substantially the same as the pressure-sensitive adhesive produced in Production Example 1 of Patent Document 3. Although the hard property at room temperature was excellent, it showed the favorable processing characteristic, but when used for bonding a 0.3 mm-thick glass substrate and a polarizing plate, it is considered that stress relaxation is inadequate, warpage and light leakage generate | occur | produce, and also the insulation degree Seemed.

Claims (12)

(A): (meth) acrylic resin which contains the structural unit derived from the monomer of following (a1)-(a4) in the following ratio;
(a1) 5-50 weight% of (meth) acrylic-type monomers whose Tg of a homopolymer is 0 degreeC or more and has a C3-C8 alkyl group which has a branch.
(a2) 43-93.9 weight% of (meth) acrylic-type monomer whose Tg of homopolymer is -60 degreeC or more and less than 0 degreeC
(a3) 1.1-7 weight% of (meth) acrylic-type monomer which has a carboxyl group
(a4) 0-10 weight% of other monomers
(B): 0.15-1.5 weight part crosslinking agent with respect to 100 weight part of said (meth) acrylic resins,
(C): Adhesive composition for polarizing plates containing a silane coupling agent. The method of claim 1,
Pressure-sensitive adhesive composition for polarizing plates having a gel fraction of 50% to 80%. The method of claim 1,
The adhesive composition for polarizing plates whose creep value in 23 degreeC is 0.3 mm or less when the following micro creep tests are performed with respect to the said adhesive composition for polarizing plates:
The adhesive composition for polarizing plates is apply | coated and dried on the peeling process polyester film, and the adhesive sheet which has an adhesive layer with a film thickness of 25 micrometers is manufactured;
The pressure sensitive adhesive sheet is bonded so that the polarizing plate and the pressure sensitive adhesive layer are in contact with the polarizing plate to produce a pressure-sensitive adhesive polarizing plate for evaluation, and aged for 7 days in a dark place at 23 ° C / 50% RH;
The pressure-sensitive adhesive polarizing plate for evaluation was cut to 10 mm in width x 100 mm in length, and the peeled polyester film was peeled off, and on the alkali-treated glass, the adhesive layer was in contact with the glass. Bonding them together so as to form a bonding area to obtain a pressure-sensitive adhesive polarizing plate test piece for evaluation;
The autoclave process (50 degreeC, 5 atm) is performed with respect to the adhesion-processing polarizing plate test piece for evaluation, and it is left to stand in 23 degreeC / 50% RH atmosphere for 24 hours;
Next, the said test piece is set to the length of 15 mm of the chuck | zipper part for fixation in the chamber BOX of a micro creep measuring device;
The laminated body of the said adhesive layer and the polarizing plate in the said test piece was made into the said laminated body and the said glass in the said test piece after heating in the said chamber BOX to measurement temperature, and leaving still for 40 minutes at a measurement temperature, with a tensile load of 800 g and a tensile time of 1000 second. Pull parallel to the adhesive surface of the laminate and in the longitudinal direction of the laminate;
The shifted distance (mm) of the bonded part of the said glass and a laminated body in the said test piece is measured as a creep value. The method of claim 3, wherein
The adhesive composition for polarizing plates whose ratio (60 degreeC creep value / 23 degreeC creep value) of the creep value in 60 degreeC and the creep value in 23 degreeC is 1.4 or more when the said micro creep test is performed. The method of claim 1,
In the said (meth) acrylic resin (A), the ratio of the structural unit derived from the said (meth) acrylic-type monomer (a1) is 5-45 weight%, and the structural unit derived from the said (meth) acrylic-type monomer (a2). The proportion of the structural unit derived from the above-mentioned (meth) acrylic monomer (a3) is 1.5 to 5.5% by weight, and the ratio of the structural unit derived from the other monomer (a4) is 0. The adhesive composition for polarizing plates which is-5 weight%. The method of claim 1,
The adhesive composition for polarizing plates whose said (meth) acrylic-type monomer (a1) is t-butyl (meth) acrylate and / or isobutyl methacrylate. The method of claim 1,
The adhesive composition for polarizing plates whose weight average molecular weights of the said (meth) acrylic resin (A) are 500,000-2 million. The adhesive sheet for polarizing plates in which the adhesive layer containing the adhesive composition for polarizing plates of any one of Claims 1-7 is formed on a base film. A polarizing plate with a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive composition for polarizing plates according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer is formed on at least one side of the polarizing plate. The laminated body by which the transparent substrate of thickness 0.3mm or less is laminated | stacked on the adhesive layer of the polarizing plate with an adhesive layer of Claim 9. The flat panel display which has a polarizing plate with an adhesive layer of Claim 9. The flat panel display which has a laminated body of Claim 10.