JP5887404B2 - Adhesive composition for optical film, adhesive optical film, and laminate - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition for optical films, a pressure-sensitive adhesive optical film, and a laminate.

  In recent years, image display devices have been used under various applications and conditions. For example, they are often used not only under room temperature conditions but also under severe conditions such as high temperature and high temperature and humidity. . Examples of the use under a high temperature or high temperature and humidity condition include use in a tropical region, use inside a vehicle, and inside an outdoor measuring instrument.

  An optical film such as a polarizing film constituting the image display device is produced by adsorbing a dichroic dye to a polymer film such as polyvinyl alcohol, and stretching and orienting the film. For this reason, the optical film is easily shrunk under a high temperature or high humidity environment, and dimensional deformation is likely to occur. Moreover, once dimensional deformation occurs in the optical film, it is difficult to completely return to the original dimensions even if the temperature and humidity conditions are changed. As a result, the pressure-sensitive adhesive layer is cracked, peeled off or floated due to the influence of the stress caused by the dimensional change of the optical film, or light leakage due to the polarization axis distortion occurs in the image display device.

  Further, in recent years, there has been a demand for an image display apparatus having a large screen, high image quality, and high durability. For example, in the case where the image display device is a liquid crystal display device, in order to meet the demand for power saving, a method using an LED as a light source is often adopted. In the case of a liquid crystal display device using an LED as a light source, a demand for high image quality and high durability against heat and light derived from the light source are remarkable. However, in the case of a liquid crystal display device that employs a system that uses an LED as a light source, light leakage tends to be noticeable because the luminance of the LED that is the light source is high.

JP 2007-169329 A

  The present invention exhibits excellent durability under high temperature and high humidity conditions, and can reduce light leakage when used for adhesion between an adherend such as a liquid crystal cell and an optical film such as a polarizing film. It is an object of the present invention to provide a pressure-sensitive adhesive composition for an optical film, and a pressure-sensitive adhesive optical film and a laminate using the same.

  In order to solve such problems, the present inventors formed a pressure-sensitive adhesive layer using a pressure-sensitive adhesive composition having a predetermined viscoelastic property, and an adherend such as a liquid crystal cell and an optical film such as a polarizing film. The present inventors have found that light leakage can be reduced when used for adhesion to the substrate.

1. The pressure-sensitive adhesive composition for an optical film according to an aspect of the present invention includes an acrylic polymer (A) having a crosslinkable functional group and a crosslinker (B), and has a maximum deformation rate defined below of 10%. The strain recovery rate defined below is 50% or more.

Maximum deformation rate: For a test piece obtained by cutting a 1 mm thick adhesive sheet obtained by applying the optical film adhesive composition on a flat plate and drying it to Φ8 mm, using a rheometer, the following measurement step Deformation rate (%) at the time when the deformation rate becomes maximum when performing 1 to 3 in order

Final deformation ratio: Deformation ratio (%) of the test piece after performing the following measurement steps 1 to 3 in order using a rheometer

Strain recovery rate: About the test piece obtained by cutting the adhesive sheet of 1 mm thickness obtained by applying the adhesive composition for optical film on a flat plate and drying it to Φ8 mm, based on the following formula (1) Calculated value

Strain recovery rate (%) = (maximum deformation rate−final deformation rate) / maximum deformation rate × 100 (1)

Measurement step 1: While increasing the temperature of the sample piece from 23 ° C. to 80 ° C. at a constant rate for 15 minutes, the shear stress of the sample piece is increased from 0 Pa to 1000 Pa at a constant rate for 15 minutes.

Measurement step 2: Increase the shear stress from 1000 Pa to 2000 Pa at a constant rate for 30 minutes while maintaining the temperature of the sample piece at 80 ° C. for 30 minutes.

Measurement step 3: While decreasing the temperature of the sample piece from 80 ° C. to 23 ° C. at a constant rate for 15 minutes, the shear stress of the sample piece is reduced from 2000 Pa to 0 Pa at a constant rate for 15 minutes.

  2. 2. The optical film pressure-sensitive adhesive composition according to 1 above, wherein the acrylic polymer (A) having a crosslinkable functional group does not have a crosslinkable functional group and has a glass transition temperature (Tg) of 0 ° C. or higher. (Meth) acrylic acid ester (a2) 5 to 55% by mass, (meth) acrylic acid ester (a2) 44 having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 ° C. It is a polymer of a monomer mixture containing 5 to 94.5% by mass and 0.5 to 6% by mass of a monomer (a3) having a crosslinkable functional group (wherein (a1) in the monomer mixture) The total amount of (a2) and (a3) is 90 to 100% by mass.

  3. 3. The optical film pressure-sensitive adhesive composition according to 1 or 2, wherein the (meth) acrylic acid ester (a1) is a (meth) acrylic acid alkyl ester, and the alkyl ester site of the (meth) acrylic acid alkyl ester is The constituting alkyl chain (wherein the alkyl chain has 1 to 20 carbon atoms) may be a linear or branched alkyl chain.

  4). In the pressure-sensitive adhesive composition for an optical film according to any one of 1 to 3, the acrylic polymer (A) having the crosslinkable functional group may have a Tg of −70 to 0 ° C.

  5. 5. The optical film pressure-sensitive adhesive composition according to any one of 1 to 4, wherein the acrylic polymer (A) having the crosslinkable functional group may have a weight average molecular weight of 500,000 to 2,000,000.

  6). In the optical film pressure-sensitive adhesive composition according to any one of 1 to 5 above, the gel fraction may be 70% or more.

7). The pressure-sensitive adhesive composition for an optical film according to another aspect of the present invention includes an acrylic polymer (A) having a crosslinkable functional group, and a crosslinker (B).
The acrylic polymer (A) having the crosslinkable functional group is
(Meth) acrylic acid ester (a1) 5 to 55% by mass having no crosslinkable functional group and having a glass transition temperature (Tg) of 0 ° C. or higher;
(Meth) acrylic acid ester (a2) 44.5-94.5% by mass having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 ° C .;
0.5-6 mass% of monomer (a3) having a crosslinkable functional group;
(Here, the total amount of the (a1), (a2) and (a3) in the monomer mixture is 90 to 100% by mass), and the gel fraction is 70%. That can be the end.

  8). In the pressure-sensitive adhesive optical film according to another aspect of the present invention, a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition for optical films according to any one of 1 to 7 above is provided on one side or both sides of the optical film.

  9. The adhesive optical film described in 8 above can be an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and a light diffusion film.

  10. The laminated body which concerns on the other aspect of this invention is the adhesive for optical films in any one of said 1 thru | or 7 provided between the glass substrate, the polarizing plate, and the said glass substrate and the said polarizing plate. And a pressure-sensitive adhesive layer obtained by forming the composition into a film and heating it.

  The above-mentioned pressure-sensitive adhesive composition for optical films has moderate adhesive strength, exhibits excellent durability under high temperature conditions or high temperature and high humidity conditions, and adherends such as liquid crystal cells and optical films such as polarizing films. When used for adhesion to a film, light leakage can be reduced. In addition, the pressure-sensitive adhesive optical film using the pressure-sensitive adhesive composition for an optical film is adhered to an adherend such as a liquid crystal cell with an appropriate adhesive force, and has excellent durability under high temperature conditions or high temperature and high humidity conditions. When it is used for adhesion to an adherend such as a liquid crystal cell, light leakage can be reduced.

FIG. 1 is a graph schematically illustrating the change with time of the deformation rate of the optical film pressure-sensitive adhesive composition according to one embodiment of the present invention, measured using a rheometer. FIG. 2 is a diagram schematically illustrating a method of measuring the luminance of the image display device (liquid crystal display panel) in the embodiment of the present invention. FIG. 3 is a diagram illustrating a method for measuring the deformation rate of a test piece of the pressure-sensitive adhesive composition of the present invention using a rheometer. FIG. 4 is a cross-sectional view schematically showing an example of a laminate including a pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive composition for an optical film according to one embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, “parts” means “parts by mass” and “%” means “mass%” unless otherwise specified.

1. Optical film pressure-sensitive adhesive composition An optical film pressure-sensitive adhesive composition according to an embodiment of the present invention (hereinafter, sometimes simply referred to as “pressure-sensitive adhesive composition”) is an acrylic resin having a crosslinkable functional group. Polymer (A) (hereinafter sometimes simply referred to as “component (A)”) and crosslinking agent (B) (hereinafter sometimes simply referred to as “component (B)”). Including.

The pressure-sensitive adhesive composition for an optical film according to this embodiment has a maximum deformation rate defined below of 10% or less and a strain recovery rate defined below of 50% or more.

Maximum deformation rate: For a test piece obtained by cutting a 1 mm thick adhesive sheet obtained by applying the optical film adhesive composition on a flat plate and drying it to Φ8 mm, using a rheometer, the following measurement step Deformation rate (%) at the time when the deformation rate becomes maximum when performing 1 to 3 in order

Final deformation ratio: Deformation ratio (%) of the test piece after performing the following measurement steps 1 to 3 in order using a rheometer

Strain recovery rate: For a test piece obtained by cutting an adhesive sheet having a thickness of 1 mm obtained by applying and drying the adhesive composition for an optical film according to the present embodiment on a flat plate to Φ8 mm, the following formula (1 ) Calculated based on

Strain recovery rate (%) = (maximum deformation rate−final deformation rate) / maximum deformation rate × 100 (1)

Measurement step 1: While increasing the temperature of the sample piece from 23 ° C. to 80 ° C. at a constant rate for 15 minutes, the shear stress of the sample piece is increased from 0 Pa to 1000 Pa at a constant rate for 15 minutes.

Measurement step 2: Increase the shear stress from 1000 Pa to 2000 Pa at a constant rate for 30 minutes while maintaining the temperature of the sample piece at 80 ° C. for 30 minutes.

Measurement step 3: While decreasing the temperature of the sample piece from 80 ° C. to 23 ° C. at a constant rate for 15 minutes, the shear stress of the sample piece is reduced from 2000 Pa to 0 Pa at a constant rate for 15 minutes.

1.1. Maximum Deformation Rate and Strain Restoration Rate The “maximum deformation rate” in the present invention is an index of the ease of deformation of the pressure-sensitive adhesive composition. It can be said that the larger the maximum deformation rate, the easier the pressure-sensitive adhesive composition is deformed. In the pressure-sensitive adhesive composition for an optical film according to this embodiment, if the maximum deformation rate exceeds 10%, the pressure-sensitive adhesive layer cannot follow the expansion or contraction of the pressure-sensitive adhesive adherend. May occur, preventing light leakage. In the pressure-sensitive adhesive composition for an optical film according to the present embodiment, the maximum strain rate is 10% or less in that birefringence generated in the pressure-sensitive adhesive can be more reliably prevented and light leakage can be further reduced. It is preferably 8% or less.

  In addition, the “strain recovery rate” in the present invention is an index of the ease of recovery of a deformed pressure-sensitive adhesive composition, and it can be said that the greater the strain recovery rate, the easier the pressure-sensitive adhesive composition recovers from deformation. In the optical film pressure-sensitive adhesive composition according to this embodiment, when the strain recovery rate is less than 50%, the deformation of the pressure-sensitive adhesive layer is difficult to recover, so birefringence generated in the pressure-sensitive adhesive is not eliminated, and light It may not be possible to prevent leakage. In the pressure-sensitive adhesive composition for an optical film according to this embodiment, the strain recovery rate is 50% or more in that birefringence generated in the pressure-sensitive adhesive can be quickly eliminated and light leakage can be further reduced. It is preferable that it is 70% or more.

  In the present invention, the “deformation rate (%)” at a certain point in time is {circumferential movement amount M (μm) of φ8 mm jig installed in the rheometer} / {before performing the measurement steps 1 to 3 described above. The thickness of the sample piece T (μm)} × 100 (%) is assumed (see FIG. 3).

  The “maximum deformation rate” and “distortion recovery rate” in the present invention will be described with reference to FIG. FIG. 1 is a graph for schematically explaining the change with time of the deformation rate of the optical film pressure-sensitive adhesive composition according to this embodiment, measured using a rheometer. That is, FIG. 1 shows the results of measuring the viscoelastic properties (rheological properties) of the optical film pressure-sensitive adhesive composition according to the present embodiment by sequentially performing the measurement steps 1 to 3 using a rheometer. . That is, the deformation rate of the optical film pressure-sensitive adhesive composition according to this embodiment is a value measured using a rheometer.

  Measurement steps 1 to 3 simulate deformation that occurs over a long period of time when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition for optical films according to this embodiment is formed on the surface of the adherend.

  In the measurement step 1, the temperature and shear stress of the sample piece are increased at a constant rate for a predetermined time (15 minutes). In the measurement step 2, the sample piece is held under a constant temperature (80 ° C.) and a constant shear stress (1000 Pa). In the measurement step 3, the temperature and shear stress of the sample piece are decreased at a constant rate for a predetermined time (15 minutes).

  Referring to FIG. 1, the deformation rate continues to increase during the measurement steps 1 and 2, and the deformation rate reaches the maximum (maximum deformation rate) at the end of the measurement step 2 (the deformation at the time when the deformation rate becomes the maximum). The rate is the maximum deformation rate.) Thereafter, in the measurement step 3, the deformation rate decreases with the temperature and shear stress of the sample piece, and at the end of the measurement step 3, the deformation rate in the measurement step 3 is minimized (final deformation rate). A strain recovery rate is calculated from the final deformation rate and the maximum deformation rate based on the equation (1).

1.2. (A) Component In the present invention, the “acrylic polymer” means at least one selected from acrylic acid, acrylate, acrylate, methacrylic acid, methacrylate, and methacrylic ester in the structural unit. A polymer containing 50% by mass or more. In the present invention, “(meth) acrylic acid” is a concept including acrylic acid and methacrylic acid. In the present invention, the “crosslinkable functional group” means a functional group capable of reacting with the crosslinking agent (B), and more specifically, a hydroxyl group, a carboxyl group, an amino group, an amide group, and an acid anhydride. It means at least one group selected from the group.

  Content of (A) component in the adhesive composition which concerns on this embodiment can be 90-99.99 mass parts with respect to 100 mass parts of adhesive compositions which concern on this embodiment, and is 95-99. It is preferably 8 parts by mass.

  In the pressure-sensitive adhesive composition according to this embodiment, the component (A) does not have a crosslinkable functional group and has a (meth) acrylic acid ester (a1) (hereinafter referred to as a glass transition temperature (Tg) of 0 ° C. or higher. Or (meth) acrylic acid having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 ° C. Ester (a2) (hereinafter sometimes simply referred to as “component (a2)”) 44.5 to 94.5% by mass and monomer (a3) having a crosslinkable functional group (hereinafter simply referred to as “(a3) ) Component ").) 0.5 to 6% by mass of a monomer mixture polymer.

1.2.1. Component (a1) The component (a1) can be, for example, a (meth) acrylic acid ester represented by the following general formula (1) and having a Tg of 0 ° C. or higher.

[ Chemical 1 ]
(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched alkyl group, an alicyclic group, or an aromatic ring-containing group.)

Examples of the (meth) acrylic acid ester having a Tg of 0 ° C. or higher as the component (a1) include methyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, n-hexadecyl acrylate, n -(Meth) acrylic acid alkyl ester having a linear alkyl group at the ester site such as hexadecyl methacrylate, stearyl acrylate, stearyl methacrylate;
(meth) acrylic acid alkyl ester having a branched alkyl group at the ester site such as t-butyl acrylate, i-propyl methacrylate, i-butyl methacrylate, t-butyl methacrylate;
(Meth) acrylic acid alkyl ester having an alicyclic group at an ester site such as cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate;
Examples include (meth) acrylic acid alkyl esters having an aromatic ring group at an ester site such as benzyl methacrylate, benzyl acrylate, and 2-naphthyl acrylate, and one of these may be used alone or in combination of two or more. . Among these, the component (a1) is a (meth) acrylic acid alkyl ester in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to the present embodiment can further reduce light leakage of the image display device. The alkyl chain constituting the alkyl ester moiety of the (meth) acrylic acid alkyl ester is preferably a linear or branched alkyl chain, and more preferably has a branched alkyl chain. In this case, the number of carbon atoms of the alkyl chain is 1 to 20 (preferably 1) in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to this embodiment can further reduce the light leakage of the image display device. To 10).

  When the content of the component (a1) in the monomer mixture for obtaining the polymer as the component (A) is less than 5% by mass, light leakage may not be sufficiently suppressed. When it exceeds%, the pressure-sensitive adhesive layer becomes too hard, and the workability of sticking may deteriorate or the durability may be adversely affected. In order to obtain a pressure-sensitive adhesive layer that sufficiently suppresses light leakage and has excellent durability, the content of the component (a1) in the monomer mixture for obtaining the polymer as the component (A) is 5 It is preferable that it is -55 mass%, and it is more preferable that it is 10-40 mass%.

1.2.2. Component (a2) The component (a2) can be, for example, a (meth) acrylic acid ester represented by the following general formula (1) and having a Tg of less than 0 ° C.

[Chemical 2]
(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched alkyl group, an alicyclic group, or an aromatic ring-containing group.)

  Examples of the (a) component (meth) acrylic acid ester having a Tg of less than 0 ° C. include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, and n-hexyl. It has a linear alkyl group at the ester site such as methacrylate, n-pentyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, n-lauryl methacrylate, n-lauryl acrylate, n-tetradecyl methacrylate, etc. (Meth) acrylic acid alkyl ester; i-propyl acrylate, i-butyl acrylate, i-octyl acrylate, i-octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate (Meth) acrylic acid alkyl ester having a branched alkyl group at the ester site; and (meth) acrylic acid alkyl ester having an aromatic ring group at the ester site such as phenoxyethyl acrylate, one of which may be used alone or Two or more kinds can be used in combination. Among these, the component (a2) is a (meth) acrylic acid alkyl ester in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to this embodiment can further reduce light leakage, ) The alkyl chain constituting the alkyl ester moiety of the acrylic acid alkyl ester is preferably a linear or branched alkyl chain, more preferably a linear alkyl chain. In this case, the number of carbon atoms of the alkyl chain is 1 to 20 (preferably 1) in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to this embodiment can further reduce the light leakage of the image display device. To 10).

  When the content of the component (a2) in the monomer mixture for obtaining the polymer as the component (A) is less than 44.5% by mass, the balance of the adhesive properties is lost, and the adhesion to the adherend is reduced. On the other hand, if it exceeds 94.5% by mass, light leakage may not be sufficiently suppressed. In order to obtain a pressure-sensitive adhesive layer that sufficiently suppresses light leakage and has excellent durability, the content of the component (a2) in the monomer mixture for obtaining the polymer as the component (A) is 44 It is preferably 5 to 94.5% by mass, more preferably 50 to 89.5% by mass, and still more preferably 60 to 86% by mass.

1.2.3. (A3) Component The (a3) component is a monomer other than the (a1) component and the (a2) component, and has a crosslinkable functional group. Examples of the component (a3) include carboxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and N, N-dimethylaminoethyl. Acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, acrylamide, N, N-dimethylaminopropyl acrylamide, acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, acrylonitrile, Among these, it can be used combining 1 type (s) or 2 or more types which essentially require the monomer which has a crosslinkable functional group. Among these, the component (a3) is preferably an alkyl (meth) acrylate and an alkyl amide having a crosslinkable functional group, or one of them in terms of excellent crosslinking performance with the crosslinking agent as the component (B). More preferably, it is at least one selected from alkyl (meth) acrylate having a hydroxyl group, acrylic acid, and alkylamide.

1.2.4. The total amount of the component (a1), the component (a2), and the component (a3) In the pressure-sensitive adhesive composition according to this embodiment, from the viewpoint of achieving a predetermined maximum deformation rate and strain recovery rate, the weight of the component (A) The total amount of the component (a1), the component (a2) and the component (a3) in the monomer mixture for obtaining a coalescence can be 90 to 100% by mass, and preferably 95 to 100% by mass. .

  Furthermore, the pressure-sensitive adhesive composition according to this embodiment is a content of a monomer having an alkylene oxide group in that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to this embodiment can further reduce light leakage. Is preferably 5% by mass or less, and more preferably not containing a monomer having an alkylene oxide group. As a monomer which has an alkylene oxide group, the reactive emulsifier which has the (meth) acryl monomer which has an alkylene oxide group in a side chain, and an alkylene oxide group is mentioned, for example. In the present invention, “the pressure-sensitive adhesive composition does not contain a monomer having an alkylene oxide group” means that the content of the monomer having an alkylene oxide group in the pressure-sensitive adhesive composition is 2% by mass or less. In particular, the content of the monomer having an alkylene oxide group in the pressure-sensitive adhesive composition is preferably 0 to 2% by mass.

1.2.5. Tg
In the pressure-sensitive adhesive composition according to this embodiment, by achieving the predetermined maximum deformation rate and strain recovery rate, light leakage can be prevented and durability can be enhanced. It is preferably −70 to 0 ° C., more preferably −40 to −10 ° C. In the present invention, the Tg of the component (A) is a value calculated by the following formula (2) (FOX formula).

1 / Tg _A = W _a1 / Tg _a1 + W _a2 / Tg _a2 + W _a3 / Tg _a3 (2)
(In the formula, Tg _A represents the glass transition temperature (K) of the component (A), and Tg _a1 , Tg _a2 , and Tg _a3 were prepared from the constituent monomers (a1), (a2), and (a3), respectively. The glass transition temperature (Tg (K)) of the homopolymer is shown, and W _a1 , W _a2 and W _a3 are the weights of the constituent monomers (a1), (a2) and (a3) contained in the component (A), respectively. Indicates the fraction.)
In addition, since Tg _A is calculated as an absolute temperature (K) by the above formula (2), it is converted to a Celsius temperature (° C.) as necessary.

The glass transition temperatures of homopolymers prepared from typical monomers are shown in Table 1 below. More specifically, for example, Polymer Handbook Fourth Edition, Wiley-Interscience, 2003) It is described in.

1.2.6. Weight average molecular weight (Mw)
In addition, in the pressure-sensitive adhesive composition according to this embodiment, from the viewpoint of preventing light leakage and increasing durability by achieving predetermined maximum deformation rate and strain recovery rate, the component (A) is The weight average molecular weight (Mw) is preferably 500,000 to 2,000,000, more preferably 800,000 to 1,800,000. Here, the weight average molecular weight of the component (A) is obtained by using GPC (gel permeation chromatography) and calculating the weight average molecular weight (Mw) in terms of standard polystyrene under the following conditions.
<GPC measurement conditions>
Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)
GPC column configuration: The following five 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
Diluted with tetrahydrofuran so that the sample concentration is 1.0 mg / cm ³ Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 cm ³ / min
Column temperature: 40 ° C
Moreover, it is preferable that (A) component concerning this embodiment has the molecular weight distribution (weight average molecular weight / number average molecular weight) calculated | required by said GPC in the range of 4-7.

1.2.7. Gel fraction Further, in the pressure-sensitive adhesive composition according to the present embodiment, by achieving the predetermined maximum deformation rate and strain recovery rate, it is possible to prevent light leakage and enhance durability. It is preferable that the gel fraction of the adhesive composition which concerns on a form is 70% or more, and it is more preferable that it is 77% or more.

In the pressure-sensitive adhesive composition according to this embodiment, the gel fraction is, for example, the type and amount of the component (a3) in the monomer mixture used when preparing the pressure-sensitive adhesive composition, and the crosslinking that is the component (B). It can be adjusted according to the type and amount of the agent used. As for the gel fraction, 0.1 g (dry weight (1)) of the crosslinked adhesive was collected in a sample bottle, and 30 cc of ethyl acetate was further added to the sample bottle and shaken for 24 hours. After that, the contents of the sample bottle were filtered with a 200 mesh stainless steel wire mesh, the residue on the wire mesh was dried at 100 ° C. for 2 hours, and the dry weight (dry weight (2)) was measured. 3).
Gel fraction (%) = (dry weight (2) / dry weight (1)) × 100 (3)

1.3. (B) Component In the pressure-sensitive adhesive composition according to the present embodiment, the crosslinking agent as the component (B) is not particularly limited as long as it is a crosslinking agent capable of crosslinking with the component (A) at room temperature or under heating. Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, and a metal chelate crosslinking agent. Among these, an isocyanate crosslinking agent is preferable.

  Specific examples of the isocyanate-based crosslinking agent include xylylene diisocyanate, tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like, Illustrative are isocyanate compounds and isocyanurates obtained by subjecting these to addition reaction with bivalent or higher alcohol compounds such as trimethylolpropane.

  Moreover, the urethane prepolymer type isocyanate etc. which made the isocyanate compound addition reaction to well-known polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, polyisoprene polyol, etc. are mentioned. Of these, xylylene diisocyanate and its derivatives are preferably used. Moreover, when (A) component has a carboxyl group, an isocyanate type crosslinking agent and an epoxy crosslinking agent can also be used together.

  The content of the component (B) in the pressure-sensitive adhesive composition according to this embodiment is based on 100 parts by mass of the pressure-sensitive adhesive composition according to this embodiment from the viewpoint of achieving a predetermined gel fraction (for example, 70% or more). 0.01 to 3 parts by mass, preferably 0.1 to 1.5 parts by mass.

1.4. Other components The adhesive composition for optical films which concerns on this embodiment can further contain components other than (A) component and (B) component as needed. For example, the pressure-sensitive adhesive composition according to the present embodiment includes (C) a silane coupling agent (hereinafter sometimes simply referred to as “component (C)”), as long as the effects of the present invention are not impaired. (D) An ionic compound (hereinafter sometimes simply referred to as “component (D)”), an antioxidant, an ultraviolet absorber, a tackifier, a plasticizer, and the like may be blended.

1.4.1. (C) Silane coupling agent When the pressure-sensitive adhesive composition for an optical film according to this embodiment contains the component (C), the surface of the adherend is used with the pressure-sensitive adhesive composition for an optical film according to this embodiment. When the pressure-sensitive adhesive layer is formed, good adhesion with the adherend can be maintained. Component (C) is, for example, a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, or methacryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Silicon compounds having an epoxy structure such as methyldimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane And an amino group-containing silicon compound such as N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; and 3-chloropropyltrimethoxysilane; an oligomer type silane coupling agent, etc. Meta) Acrylic Copo Silane coupling agents having a functional group reactive with the functional group contained in the mer (A) is preferable because hardly cause peeling in wet heat environment.

  The content of the component (C) in the pressure-sensitive adhesive composition for optical films according to the present embodiment is from the viewpoint of maintaining good adhesion to the adherend, and the pressure-sensitive adhesive composition for optical films according to the present embodiment. It can be 0-0.5 mass part with respect to 100 mass parts, and it is preferable that it is 0.05-0.3 mass part.

1.4.2. (D) Ionic compound Moreover, the adhesive composition which concerns on this embodiment may contain the ionic compound (D). When the pressure-sensitive adhesive composition according to the present embodiment contains the component (D), when the pressure-sensitive adhesive layer is formed on the surface of the adherend using the pressure-sensitive adhesive composition according to the present embodiment, charging of the adherend is performed. Can be effectively prevented. Examples of the component (D) include an ionic compound that is composed of an anion and a cation and is liquid or solid at 25 ° C., specifically, an alkali metal salt, an ionic liquid (liquid at 25 ° C. Shape), surfactants and the like.

Examples of the alkali metal salt include compounds comprising an alkali metal cation such as lithium, sodium and potassium and an anion. Specifically, sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, potassium chlorate , Potassium nitrate, sodium nitrate, sodium carbonate, sodium thiocyanate, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, sodium acetate, sodium alginate, sodium lignin sulfonate, sodium toluene sulfonate, LiCF ₃ SO ₃ , Li (CF _{3 SO 2) 2 N, Li (} CF 3 SO 2) IN, Li (C 2 F 5 SO 2) 2N, Li (C 2 F 5 SO 2) IN, Li (CF 3 SO 2) 3 C and the like .

As the cation constituting the ionic liquid, piperidinium cation, pyrrolidinium cation, cation having pyrroline skeleton, cation having pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyra Examples include an azolium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, and a tetraalkylphosphonium cation, and examples of anions constituting the ionic liquid include Cl ⁻ , Br ⁻ , I ⁻ , and AlCl _4. ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) n ⁻ (n = 2 to 3), (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO) N ^{− and the} like can be mentioned.

And as said ionic compound, it is comprised from these cations and anions, and a liquid ionic compound is mentioned at 25 degreeC. Specific examples of such ionic compounds include 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindole tetrafluoroborate, 1,2-dimethylindole tetrafluoroborate, and 1-ethyl. Carbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazole 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium dicyanamide, 1 Ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluoro Butyrate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis ( Trifluoromethanesulfonyl) imide, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl- 3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1 -Hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium bis (trifluoromethanesulfonyl) imide, 1-methylpyrazolium tetrafluoroborate, 3- Methylpyrazolium tetrafluoroborate, tetrahexylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium bis (penta Fluoroethanesulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium trifluoromethane Sulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (pentafluoroethanesulfonyl) imide, glycidyltrimethylammonium trifluoromethanesulfonate, glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide, glycidyltrimethyl Ammonium bis (pentafluoroethanesulfonyl) imide, 1-butylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-3-methylimidazolium ( Trifluoromethanesulfonyl) trifluoroacetamide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) an Ni (trifluoromethanesulfonyl) trifluoroacetamide, diallyldimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, glycidyltrimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, N, N-dimethyl-N-ethyl-N-propylammonium bis ( Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-he Ptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-nonylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dipropylammonium bis (trifluoromethanesulfonyl) ) Imide, N, N-dimethyl-N-propyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N -Dimethyl-N-propyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl- -Butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-pentyl-N-hexyl Ammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl- N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl -N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, triethylpropylammonium bis (trifluoromethanesulfonyl) imide, triethylpentylammonium bis (Trifluoromethanesulfonyl) imide, triethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-ethylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl- N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluorome Tansulfonyl) imide, N, N-dipropyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N -Dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoro) Romethanesulfonyl) imide and the like.

  As the surfactant, any of nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants can be used.

  Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkylphenyls such as polyoxyethylene octylphenyl ether and polyoxyethylene nonielphenyl ether. Sorbitan higher fatty acid esters such as ethers, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene monolaurate, poly Polyoxyethylene higher fatty acid esters such as oxyethylene monostearate; for example, oleic acid monoglyceride, stearic acid monoglycera Glycerine higher fatty acid esters such as de, polyoxyethylene, polyoxypropylene, polyoxyalkylenes and their block copolymers such as polyoxyethylene butylene.

  Examples of the cationic surfactant include alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, benzalkonium chloride salt, and alkyldimethylammonium ethosulphate.

  Examples of the anionic surfactant include sodium laurate, sodium oleate, N-acyl-N-methylglycine sodium salt, carboxylate such as sodium polyoxyethylene lauryl ether carboxylate, sodium dodecylbenzenesulfonate, dialkylsulfosuccinate. Acid ester salts, sulfonates such as sodium dimethyl-5-sulfoisophthalate, sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate, sodium polyoxyethylene lauryl phosphate And phosphoric acid ester salts such as sodium polyoxyethylene nonylphenyl ether phosphate.

  Examples of the amphoteric surfactants include carboxybetaine surfactants, aminocarboxylates, imidazolinium petines, lecithins, and alkylamine oxides. In addition, conductive polymers, conductive carbon, ammonium chloride, aluminum chloride, copper chloride, iron chloride, ammonium sulfate, and the like can be used.

  Among these, alkali metal salts are preferable, and lithium perchlorate is particularly preferably used.

  Content of (D) component in the adhesive composition for optical films which concerns on this embodiment can be 0-3 mass parts with respect to 100 mass parts of adhesive compositions for optical films which concern on this embodiment. 0.05 to 2.5 parts by mass is preferable.

1.5. (A) Polymerization Method of Component (A) The polymerization method of component (A) is not particularly limited and can be polymerized by known methods such as solution polymerization, emulsion polymerization, suspension polymerization, etc. In producing the pressure-sensitive adhesive composition of the present invention using a mixture of coalesces, it is preferable to perform polymerization by solution polymerization from the viewpoint that the treatment process is relatively simple and can be performed in a short time.

  In solution polymerization, generally, a predetermined organic solvent, each monomer, a polymerization initiator, and a chain transfer agent used as necessary are charged in a polymerization tank, under a nitrogen stream or a reflux temperature of the organic solvent, The reaction is carried out by heating for several hours with stirring.

  In this case, at least a part of the organic solvent, the monomer and / or the polymerization initiator may be added sequentially. Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, aromatic naphtha; For example, aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil; Esters such as n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate; for example, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, Ketones such as cyclohexanone and methylcyclohexanone; Glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl And alcohols such as alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t-butyl alcohol. These organic solvents can be used alone or in admixture of two or more.

  Among these organic solvents for polymerization, in the polymerization of the component (A), it is preferable to use an organic solvent that hardly causes chain transfer during the polymerization reaction, for example, esters and ketones. In view of solubility and ease of polymerization reaction, use of ethyl acetate, methyl ethyl ketone, acetone or the like is preferable.

  As the polymerization initiator, it is possible to use organic peroxides, azo compounds and the like that 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 peroxydicarbonate. , Di-2-ethylhexyl peroxydicarbonate, t-butyl peroxybivalate, 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-butyronitrile and 2,2 ′. -Azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, etc. can be mentioned.

  Among these organic peroxides, a polymerization initiator that does not cause a graft reaction during the polymerization reaction of the component (A) is preferable, and an azo type is particularly preferable. The amount of use 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.

  Further, in the production of the component (A) contained in the pressure-sensitive adhesive composition of the present invention, it is normal not to use a chain transfer agent, but as long as it does not impair the object and effect of the present invention. It is possible to use.

  Examples of such chain transfer agents include cyanoacetic acid; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; anthracene, phenanthrene, fluorene, 9 -Aromatic compounds such as phenylfluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone, 2, 3, 5, Benzoquinone derivatives such as 6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloro Methane, tribromomethane, 3-chloro-1-propyl Halogenated hydrocarbons such as pens; Aldehydes such as chloral and fulleraldehyde: Alkyl mercaptans having 1 to 18 carbon atoms; Aromatic mercaptans such as thiophenol and toluene mercaptan; 1 to 10 carbon atoms of mercaptoacetic acid and mercaptoacetic acid And alkyl esters of 1 to 12 carbons, terpenes such as pinene and terpinolene, and the like.

  The polymerization temperature of the component (A) is generally about 30 to 180 ° C, preferably 40 to 150 ° C, and more preferably 50 to 90 ° C. When an unreacted monomer is contained in a polymer obtained by a solution polymerization method or the like, it can be purified by a reprecipitation method using methanol or the like in order to remove the monomer.

1.6. Manufacture of an adhesive composition The adhesive composition which concerns on this embodiment is normally prepared by mixing the said (A) and (B) component and arbitrary components as needed simultaneously or in arbitrary orders. Moreover, when mixing (A) component and (B) component, when preparing (A) component by solution polymerization, (B) component is added to the solution containing (A) component after the completion of polymerization. In addition, when the component (A) is prepared by bulk polymerization, uniform mixing becomes difficult after the completion of the polymerization. Therefore, it is preferable to add and mix the component (B) during the polymerization.

1.7. Applications and operational effects The pressure-sensitive adhesive composition according to this embodiment can be suitably used as an adhesive for optical films (described in detail later). According to the pressure-sensitive adhesive composition according to the present embodiment, it exhibited excellent durability under high temperature and high humidity conditions, and was used for adhesion between an adherend such as a liquid crystal cell and an optical film such as a polarizing film. In this case, light leakage can be reduced. When the image display device includes a retardation film, since the retardation film is provided between the liquid crystal cell and the polarizing film, the pressure-sensitive adhesive composition according to this embodiment is provided between the retardation film and the polarizing film. An adhesive layer using can be provided.

  For example, in the LED-type image display device (liquid crystal display device) that employs the LED as a light source, the pressure-sensitive adhesive composition according to the present embodiment is used for bonding an adherend such as a liquid crystal cell and an optical film such as a polarizing film. In this case, good light leakage prevention characteristics and high durability can be realized, so that the image quality of the image display device can be improved. In this case, the pressure-sensitive adhesive composition according to this embodiment can be used as an adhesive having the VA mode polarizing film or the IPS mode polarizing film as an adherend, but can achieve high image quality. In this respect, it can be suitably used as an adhesive having a VA mode polarizing film as an adherend.

  For example, when the pressure-sensitive adhesive composition according to this embodiment is used as an adhesive having a VA mode polarizing film as an adherend, a large-sized (for example, 10 inches or more, preferably 19 inches or more) image display. When the pressure-sensitive adhesive composition according to this embodiment is used to form the adhesive layer of the device, the large-sized image display device has a large shrinkage due to the stress caused by dimensional deformation, particularly because the polarizing film has a large shrinkage. The influence of peeling is large, and the influence of light leakage due to the distortion of the polarization axis is large. For this reason, the adhesive layer is useful in that it can achieve high image quality by being excellent in durability and reducing light leakage.

  It is estimated that the light leakage prevention characteristic which is one effect of the adhesive composition which concerns on this embodiment is based on the following two action mechanisms. 1stly, when the stress resulting from shrinkage | contraction of a polarizing film is added to the adhesive composition which concerns on this embodiment, the deformation rate of the adhesive composition which concerns on this embodiment is small (the adhesive composition which concerns on this embodiment) Therefore, the shrinkage of the polarizing film can be moderately suppressed, the distortion of the polarizing axis of the polarizing film can be reduced, and as a result, light leakage can be reduced. Second, when the stress of the polarizing film is released, the strain recovery rate of the pressure-sensitive adhesive composition according to the present embodiment is 50% or more, so that the pressure-sensitive adhesive composition according to the present embodiment is deformed. Therefore, the distortion of the polarization axis due to the contraction of the polarizing film is quickly restored, and as a result, the light leakage of the image display device can be reduced.

  That is, when an adhesive layer is provided on the surface of an optical film (polarizing film) using the adhesive composition according to this embodiment, the deformation rate of the adhesive layer is small (the adhesive composition according to this embodiment). The above-mentioned maximum strain rate is 10% or less), the first characteristic that moderately suppresses the shrinkage of the optical film, and the second characteristic that quickly restores the deformation of the pressure-sensitive adhesive layer (this embodiment) The pressure-sensitive adhesive composition according to this embodiment has both the above-described strain recovery rate of 50% or more), and the adhesive composition according to this embodiment achieves high durability of the image display device, and The light leakage of the image display device can be reduced.

2. 2. Adhesive optical film and laminate 2.1. Adhesive Optical Film An adhesive optical film according to another embodiment of the present invention is provided with an adhesive layer containing the optical film adhesive composition according to the above embodiment on one or both sides of the optical film. In producing the pressure-sensitive adhesive optical film according to the present embodiment, the pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition on the optical film with a gravure coater, Mayer bar coater, air knife coater, roll coater, or the like. It may be formed by drying and crosslinking the pressure-sensitive adhesive composition applied thereon at room temperature or by heating, or by forming a pressure-sensitive adhesive layer on a release film and transferring it to the optical film. Good. Moreover, the thickness of an adhesive layer is 1-50 micrometers normally, Preferably it is about 5-30 micrometers. In addition, in order to protect an adhesive layer before using an adhesive optical film, you may laminate | stack a peeling film on the surface of this adhesive layer.

  Examples of the pressure-sensitive adhesive optical film according to the present embodiment include those used in image display devices such as FPD, such as a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and the like. It can be an optical film selected from the group consisting of light diffusing films. Although the thickness of an optical film can be suitably selected according to the intended purpose, it is 10-500 micrometers normally, Preferably it is about 15-300 micrometers.

2.2. Laminated body The laminated body which concerns on one Embodiment of this invention is the adhesive composition for optical films which concerns on the said embodiment provided between the glass substrate, the polarizing plate, and the said glass substrate and the said polarizing plate. And a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) obtained by molding into a film and heating.

2.2.1. Laminated Structure FIG. 4 is a cross-sectional view schematically showing an example (laminated body 200) of a laminated body according to an embodiment of the present invention. As shown in FIG. 1, the laminate 200 includes a glass substrate 110, a polarizing film (polarizing plate) 130, and an adhesive layer 120 provided between the glass substrate 110 and the polarizing film 130.

  More specifically, the laminate 200 includes a glass substrate 110, a pressure-sensitive adhesive layer 120 provided on the glass substrate 110, and a polarizing film 130 provided on the glass substrate 110 via the pressure-sensitive adhesive layer 120. Including. The glass substrate 110 and the polarizing film 130 are bonded via an adhesive layer 120.

  In FIG. 4, the adhesive layer 120 is formed on the surface of the adherend (glass substrate 110). As a method of forming the pressure-sensitive adhesive composition according to the present embodiment on the surface of the adherend, after applying the pressure-sensitive adhesive composition to the surface of a release film (separator) with good smoothness and drying the coating film, The transfer method which transfers the said coating film to the surface of a specific resin film can be mentioned.

  The laminate according to the present embodiment is included in, for example, an image display device (particularly a liquid crystal display device). In this case, the glass substrate included in the laminate according to the present embodiment is a glass substrate for a liquid crystal display device.

2.2.2. Glass substrate The glass substrate which comprises the laminated body which concerns on this embodiment can be a glass substrate used for image display apparatuses. The image display device can be, for example, a TFT (thin film transistor) liquid crystal display device used for a liquid crystal television, a computer monitor, a mobile phone, a tablet, and the like.

2.2.3. Effect The laminate according to the present embodiment is a glass substrate, a polarizing film, and the optical film pressure-sensitive adhesive composition according to the embodiment, which is provided between the glass substrate and the polarizing film. By including the pressure-sensitive adhesive layer obtained by molding, heating and drying appropriately, excellent durability can be exhibited under high temperature and high humidity conditions, and light leakage can be reduced.

3. EXAMPLES Hereinafter, the present invention will be described based on the following examples, but the present invention is not limited to the examples.

3.1. (A) Preparation of component A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with a monomer mixture having the blending ratio shown in Tables 2 and 3 below, and then ethyl acetate was added to the monomer concentration. Was added in an amount of 50% by mass. Next, 0.1 part by mass of azobisisobutyronitrile was added, the mixture was stirred while the air in the reaction vessel was replaced with nitrogen gas, and the temperature was raised to 60 ° C., followed by reaction for 4 hours. After completion of the reaction, the mixture was diluted with ethyl acetate to obtain component (A) (acrylic polymers A to L).

3.2. Preparation of adhesive processing polarizing plate for evaluation Above 3.1. Using the component (A) obtained in the above, each component was added in the blending (solid blending) shown in Tables 3 and 4 below, and the pressure-sensitive adhesive compositions of Examples 1 to 15 and Comparative Examples 1 to 5 Solution was obtained. The pressure-sensitive adhesive composition solution was applied to the surface of the peeled polyester film and dried to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 20 μm. After sticking this pressure-sensitive adhesive sheet on one side of the polarizing film for VA mode, it was aged in a dark place at 23 ° C./50% RH for 7 days to obtain a pressure-sensitive adhesive processed polarizing plate for evaluation.

  For each evaluation adhesive polarizing plate, maximum deformation rate, strain recovery rate, light leakage (LED using light source: LED method) and light leakage (without using LED as light source) shown in Table 3 and Table 4 below : Non-LED method) and wet heat durability (foaming and tearing) were evaluated by the following methods.

3.3. Evaluation method 3.3.1. Maximum deformation rate and strain recovery rate The acrylic copolymer solutions of Examples 1 to 15 and Comparative Examples 1 to 5 shown in Tables 3 and 4 were applied to the surface of the release-treated polyester film and dried to allow air to enter. As a test piece, the film was formed to a thickness of 1 mm and cut to Φ8 mm. About this test piece, the said measurement process 1 thru | or 3 was performed in order using a rheometer (model name: MCR300, Nippon Shibel Hegner), the said maximum deformation rate was measured, and strain recovery rate based on said (1) Was calculated.

3.3.2. Light leakage 19-inch size VA liquid crystal panel (I / O Data Co., Ltd., model: removed from LCD-A191EW), and peeled polyester film peeled off for evaluation. The layers were bonded so that the layer was in contact with the liquid crystal panel and the evaluation pressure-sensitive adhesive-processed polarizing plate was crossed Nicol, and allowed to stand in an atmosphere at 80 ° C. for 240 hours, and then in an atmosphere at 23 ° C./50% RH. And left for 2 hours. Thereafter, the VA liquid crystal panel on which the polarizing plate was bonded was connected to a personal computer in a dark room to display a full screen black. In this test, evaluation was performed using two types of light source (backlight), LED (LED method) and fluorescent lamp (non-LED method). As shown in FIG. 2, the full screen black display monitor has luminance (La, Lb, Lc, Ld) in a 1 cm diameter area near each corner and luminance (Lcenter) in a 1 cm diameter area in the center of the monitor. ) Was measured using a luminance meter (manufactured by Highland, model name: RISA-COLOR / CD8), and light leakage (ΔL) was calculated based on the following formula (4). Smaller ΔL means less light leakage (from the backlight). Usually, if ΔL is less than 2.0, it can be used as a liquid crystal display panel.
ΔL = (La + Lb + Lc + Ld) / 4−Lcenter (4)

  Further, as indicated by a dotted line in FIG. 2, a range (R) where light leakage occurred in the vicinity of the corner of the display monitor was visually measured. The smaller the area where light leakage occurs, the smaller the light leakage. Normally, if R is less than 20 mm, it can be used as a liquid crystal display panel.

3.3.3. Wet heat durability The adhesive processing polarizing plate for evaluation which peeled off the peeled polyester film was cut into a 15 inch size (233 mm × 309 mm), and an adhesive layer was formed on one surface of a non-alkali glass plate having a thickness of 0.5 mm. It stuck using the laminator roll so that the said glass plate might be touched. After pasting, a test plate was obtained by pressurizing in an autoclave (manufactured by Kurihara Seisakusho) under conditions of 0.5 MPa, 50 ° C., and 20 minutes. The test plate thus obtained was left under conditions of 60 ° C./90% RH for 500 hours. After completion of the test, the test plate is taken out from the test environment and left to stand for 2 hours in a 23 ° C./50% RH atmosphere, and then visually observed for foaming (cohesion insufficient) and tearing (overcrosslinking) in the adhesive layer. The wet heat durability was evaluated according to the following evaluation criteria.

(Foam-size)
○: No foaming is observed Δ: Foam diameter is 1 mm or less ×: Foam diameter is greater than 1 mm

(Foaming-generation amount)
○: No foaming is observed Δ: The number of foams is 10 or less ×: The number of foams is more than 10

(Tear-size)
○: No tearing is observed Δ: The area where tearing occurs is less than 5% with respect to the entire bonding part (100%) in the test plate x: The area where tearing occurs is the entire bonding part in the test plate (100%) over 5%

(Rear-position)
◯: No tearing Δ: Defects only in the 1 cm width region near each end of the test plate ×: Defects in the 1 cm region near each end of the test plate and outside the region

Abbreviations in Table 2, Table 3, and Table 4 have the following meanings.
AA: Acrylic acid AM: Acrylamide BA: n-Butyl acrylate t-BA: Tertiary butyl acrylate i-BMA: Isobutyl methacrylate HEA: 2-hydroxyethyl acrylate L-45: TDI isocyanate compound (L-45 manufactured by Soken Chemical Co., Ltd.) )
MA: methyl acrylate MEA: methoxyethyl acrylate i-PMA: isopropyl methacrylate TD: XDI-based isocyanate compound (TD-75 manufactured by Mitsui Takeda)
KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
Antistatic agent (component (D): ionic compound): 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide

  From the results of Tables 1 to 4, the compositions of Examples 1 to 15 were obtained using the compositions having a maximum deformation rate of 10% or less and a strain recovery rate of 50% or more. The pressure-sensitive adhesive composition according to the present embodiment has both the first characteristic in which the adhesive layer is appropriately suppressed from shrinkage of the optical film and the second characteristic in which deformation of the pressure-sensitive adhesive layer is quickly restored. By providing, high adhesive strength and excellent durability can be realized, and light leakage can be reduced. On the other hand, the compositions of Comparative Examples 1 to 6 do not satisfy both the maximum deformation rate of 10% or less and the strain recovery rate of 50% or more. It can be understood that the adhesive layer obtained by using the above does not achieve the first characteristic and the second characteristic at the same time, and therefore the light leakage cannot be sufficiently reduced.

  1 sample piece, 2 jig, 10 final deformation rate, 20 maximum deformation rate, 100 image display device, La, Lb, Lc, Ld brightness near the corner of the image display device, brightness at the center of the Lcenter image display device, M Circumferential movement amount, T sample piece thickness, 110 glass substrate, 120 pressure-sensitive adhesive layer, 130 polarizing film, 200 laminate.

Claims (9)

An acrylic polymer (A) having a crosslinkable functional group, and a crosslinking agent (B),
The maximum deformation rate defined below is 10% or less, and the strain recovery rate defined below is 50% or more, an optical film pressure-sensitive adhesive composition ,
The acrylic polymer (A) having the crosslinkable functional group is
(Meth) acrylic acid ester (a1) 5 to 55% by mass having no crosslinkable functional group and having a glass transition temperature (Tg) of 0 ° C. or higher;
(Meth) acrylic acid ester (a2) 44.5-94.5% by mass having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 ° C .;
0.5-6 mass% of monomer (a3) having a crosslinkable functional group;
(Here, the total amount of (a1), (a2) and (a3) in the monomer mixture is 90 to 100% by mass)).
Content of the said acrylic polymer (A) component is 95-99.8 mass parts with respect to 100 mass parts of adhesive compositions,
The pressure-sensitive adhesive composition for an optical film, wherein the crosslinking agent (B) is an isocyanate crosslinking agent.

Maximum deformation rate: For a test piece obtained by cutting a 1 mm thick adhesive sheet obtained by applying the optical film adhesive composition on a flat plate and drying it to Φ8 mm, using a rheometer, the following measurement step Deformation rate (%) at the time when the deformation rate becomes maximum when performing 1 to 3 in order

Final deformation ratio: Deformation ratio (%) of the test piece after performing the following measurement steps 1 to 3 in order using a rheometer

Strain recovery rate: About the test piece obtained by cutting the adhesive sheet of 1 mm thickness obtained by applying the adhesive composition for optical film on a flat plate and drying it to Φ8 mm, based on the following formula (1) Calculated value

Strain recovery rate (%) = (maximum deformation rate−final deformation rate) / maximum deformation rate × 100 (1)

Measurement step 1: While increasing the temperature of the sample piece from 23 ° C. to 80 ° C. at a constant rate for 15 minutes, the shear stress of the sample piece is increased from 0 Pa to 1000 Pa at a constant rate for 15 minutes.

Measurement step 2: Increase the shear stress from 1000 Pa to 2000 Pa at a constant rate for 30 minutes while maintaining the temperature of the sample piece at 80 ° C. for 30 minutes.

Measurement step 3: While decreasing the temperature of the sample piece from 80 ° C. to 23 ° C. at a constant rate for 15 minutes, the shear stress of the sample piece is reduced from 2000 Pa to 0 Pa at a constant rate for 15 minutes. The (meth) acrylic acid ester (a1) is a (meth) acrylic acid alkyl ester,
The (meth) (wherein, a carbon atom number in the alkyl chain is 1 to 20.) Alkyl chain constituting the alkyl ester moiety of the acrylic acid alkyl ester is a linear or branched alkyl chain, wherein Item 2. The pressure-sensitive adhesive composition for an optical film according to Item 1 . The pressure-sensitive adhesive composition for an optical film according to claim 1 or 2 , wherein the acrylic polymer (A) having a crosslinkable functional group has a Tg of -70 to 0 ° C. The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 3 , wherein the acrylic polymer (A) having a crosslinkable functional group has a weight average molecular weight of 500,000 to 2,000,000. The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 4 , wherein the gel fraction is 70% or more. An acrylic polymer (A) having a crosslinkable functional group, and a crosslinking agent (B),
The acrylic polymer (A) having the crosslinkable functional group does not have a crosslinkable functional group and has a glass transition temperature (Tg) of 0 ° C. or higher (meth) acrylic acid ester (a1) of 5 to 55% by mass. When,
(Meth) acrylic acid ester (a2) 44.5-94.5% by mass having no crosslinkable functional group and having a glass transition temperature (Tg) of less than 0 ° C .;
0.5-6 mass% of monomer (a3) having a crosslinkable functional group;
(Wherein the total amount of the (a1), (a2) and (a3) in the monomer mixture is 90 to 100% by mass),
Content of the said acrylic polymer (A) component is 95-99.8 mass parts with respect to 100 mass parts of adhesive compositions,
The pressure-sensitive adhesive composition for an optical film, wherein the crosslinking agent (B) is an isocyanate crosslinking agent and has a gel fraction of 70% or more. A pressure-sensitive adhesive optical film in which a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition for an optical film according to claim 1 is provided on one side or both sides of the optical film. The pressure-sensitive adhesive optical film according to claim 7 , which is an optical film selected from the group consisting of a polarizing film, a retardation film, an elliptical polarizing film, an antireflection film, a brightness enhancement film, and a light diffusion film. A glass substrate;
A polarizing plate;
The adhesive layer obtained by shape | molding the adhesive composition for optical films of any one of Claim 1 thru | or 6 formed in the film form, and heating between the said glass substrate and the said polarizing plate. When,
A laminate comprising: