KR102053981B1 - Adhesive composition and adhesive film - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having excellent reworkability and high adhesion performance despite being a thin film and a pressure-sensitive adhesive film using the same. (1) 100 total of (meth) acrylate monomers containing at least one selected from the group consisting of alkyl (meth) acrylate monomers having C1 to C14 carbon atoms of alkyl groups and (meth) acrylate monomers having aromatic groups It does not contain a weight part and at least 30 weight part or more of butyl acrylate in (1), and a carboxyl group-containing copolymerizable vinyl monomer, and (2) hydroxyl group-containing copolymerizable vinyl monomer is 0.1-3.5 with respect to (1). The pressure-sensitive adhesive composition containing 0.01 parts by weight to 0.01 parts by weight of an isocyanate compound containing 3 parts by weight, an acid value of 0.1 or less, a weight average molecular weight of 1 million or more copolymers, and (1).

Description

Adhesive composition and adhesive film {ADHESIVE COMPOSITION AND ADHESIVE FILM}

TECHNICAL FIELD This invention relates to the adhesive composition and adhesive film used for bonding of optical members, such as a polarizing plate.

Various adhesive films are proposed in order to bond optical members, such as a polarizing plate and retardation plate, to adherends, such as a liquid crystal cell, via an adhesive layer (for example, refer patent documents 1-2).

Patent document 1 describes the optical adhesive composition which uses butyl acrylate etc. as a monomer of a main component, and contains an acrylamide compound.

Patent document 2 describes the adhesive composition for optics which uses the (meth) acrylate which has a C4-C8 alkyl group as a monomer of a main component, and contains a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer.

Moreover, in order to raise the refractive index of an adhesive layer, the adhesive film which carried out various studies is proposed (for example, refer patent documents 3-8).

Patent Document 3 describes an optical pressure-sensitive adhesive composition having an aromatic ring and containing a tackifier having a refractive index of 1.51 to 1.75.

Patent document 4 describes the adhesive sheet containing the adhesive composition containing the copolymerizable polymer of the acrylic acid modified monomer which has an aromatic ring.

Patent document 5 describes the adhesive composition for optics containing the tackifying resin which has an aromatic ring, and an aromatic phosphate ester plasticizer.

Patent document 6 describes an adhesive in which an adhesive composition containing an acrylic resin and an aromatic compound having one ethylenically unsaturated group is cured.

Patent document 7 describes an optical component formed by fixing a phase difference film and a birefringent plate to each other via an acrylic pressure-sensitive adhesive containing an aromatic monomer.

Patent document 8 describes an adhesive composition containing a urethane resin obtained by reacting an aromatic diisocyanate with an aromatic polyester diol.

Japanese Laid-Open Patent Publication 2012-177022 Japanese Laid-Open Patent Publication 2012-201734 Japanese Unexamined Patent Publication No. 2007-084762 Japanese Unexamined Patent Publication No. 2011-153169 Japanese Laid-Open Patent Publication 2012-167188 Japanese Laid-Open Patent Publication 2012-021148 Japanese Unexamined Patent Publication No. 2006-293281 Japanese Unexamined Patent Publication No. 2009-091522

In recent years, what is requested | required about the adhesive film used for bonding the interlayers of an optical member is made into the adhesive film which made thickness of the adhesive layer thin in order to plan thinning of an optical member.

Generally, since the adhesive force of an adhesive layer is substantially proportional to the thickness of an adhesive layer, when thickness of an adhesive layer is made thin, the adhesive force falls with it.

However, in recent years, even if the pressure-sensitive adhesive film is thin, the pressure-sensitive adhesive film has the same adhesive force as the conventional pressure-sensitive adhesive film (the thickness of the pressure-sensitive adhesive layer is about 30 µm thick) and is left for a long time in an atmosphere of high temperature and high humidity. It is also required to have the performance equivalent to or more than the conventional adhesive film also in the subsequent durability.

Moreover, since only the adhesive layer which abbreviate | omitted the base material of an adhesive film from the point that the thickness of an adhesive layer can be made thin and the adhesive layer which does not need to perform aging treatment (curing at constant temperature) can be formed It is required to set it as the form of NCF (Non Carrier Film) which made into the member structure of "release film / adhesive layer / release film."

Moreover, in the conventional adhesive film, since the aging process is performed after bonding an adhesive film to a to-be-adhered body, the adhesiveness of an to-be-adhered body and an adhesive layer was attained.

However, in the adhesive film which took the form of NCF, since the aging of an adhesive layer is already completed, the adhesive force of a to-be-adhered body and an adhesive layer falls short. For this reason, there existed a problem that surface treatment, such as corona treatment, needs to be performed to the surface of a to-be-adhered body.

There is a need for an adhesive film that overcomes these requirements and problems.

This invention is made | formed in view of the said situation, and makes it a subject to provide the adhesive composition which can form the adhesive layer which has the outstanding rework property and the high adhesiveness performance, although it is a thin film.

In order to solve the said subject, the adhesive composition which concerns on this invention makes a butyl acrylate an essential monomer, and does not use a carboxyl group-containing copolymerizable vinyl monomer as a functional group containing monomer, but uses the hydroxyl group containing copolymerizable vinyl monomer. It is characterized by using an isocyanate compound as a crosslinking agent with respect to 1 million or more copolymers, More preferably, using a silane coupling agent together.

Moreover, in order to solve the said subject, this invention is a monomer which consists of (1) the alkyl (meth) acrylate monomer which has C1-C14 carbon number of an alkyl group as a (meth) acrylate monomer, and the (meth) acrylate monomer which has an aromatic group. It contains at least 1 sort (s) or more selected from the group, and does not contain at least 30 weight part or more of butyl acrylate and a carboxyl group-containing copolymerizable vinyl monomer among 100 weight part of said (meth) acrylate monomers, (2) 0.1-3.5 weight part of hydroxyl-containing copolymerizable vinyl monomers with respect to a total of 100 weight part of acrylate monomers, The acryl-type polymer whose acid value is 0.1 or less and a weight average molecular weight is 1 million or more copolymer, and the said (3) 0.01-0.8 weight part of isocyanate compounds are contained as a crosslinking agent with respect to a total of 100 weight part of a (meth) acrylate monomer, Luer that provides a pressure-sensitive adhesive composition.

It is preferable to contain 0.01-0.5 weight part of (4) silane coupling agents further with respect to a total of 100 weight part of the said (meth) acrylate monomer.

Moreover, it is preferable that the said isocyanate compound is the trimethylolpropane adduct of tolylene diisocyanate.

Moreover, the said (2) hydroxyl-containing copolymerizable vinyl monomer is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy It is preferable that it is at least 1 sort (s) or more chosen from the compound group which consists of ethyl (meth) acrylate.

Moreover, this invention is an adhesive layer which bridge | crosslinked the said adhesive composition, The gel fraction after crosslinking is 40 to 75%, The adhesive layer of the adhesive layer of thickness 25micrometer is 1.5-6.0 N / 25mm, The adhesive layer characterized by the above-mentioned. to provide.

Moreover, after bonding the said adhesive layer to a to-be-adhered body, it is preferable that the adhesive force after 70 degreeC x 10 days is 1.5-10 N / 25mm.

Moreover, this invention provides the adhesive film characterized by the said adhesive layer laminated | stacked on one side of the base material.

Moreover, this invention provides the adhesive film used for bonding of the polarizing plate and display panel in which the said adhesive film was used.

Moreover, this invention provides the said adhesive layer used as the adhesive layer of the polarizing plate in which the adhesive layer was formed.

Moreover, this invention provides the said adhesive layer used as the adhesive layer of the polarizing plate in which the adhesive layer in which the phase difference film which has a phase difference of (lambda) / 4 or (lambda) / 2 as a constituent material of a polarizing plate was used.

Moreover, this invention provides the optical film with an adhesive layer in which the said adhesive layer is laminated | stacked on at least one surface of an optical film.

Advantageous Effects of Invention The present invention is characterized in that the pressure-sensitive adhesive layer has a higher gel fraction after crosslinking, while reducing the amount of crosslinking agent and functional group than a conventional pressure-sensitive adhesive layer. The used adhesive film can be obtained.

Although the adhesive film of this invention is a thin film, it has the performance of the outstanding rework property and high adhesiveness.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on preferable embodiment.

The adhesive composition of this invention is (1) at least 1 sort (s) chosen from the monomer group which consists of an alkyl (meth) acrylate monomer which has C1-C14 carbon number of an alkyl group as a (meth) acrylate monomer, and the (meth) acrylate monomer which has an aromatic group. The total of the said (meth) acrylate monomer containing the above and not including at least 30 weight part or more of butyl acrylate and a carboxyl group-containing copolymerizable vinyl monomer in 100 weight part of said total of the said (meth) acrylate monomer. (2) Acrylic polymer containing 0.1-3.5 weight part of hydroxyl-containing copolymerizable vinyl monomers, an acid value of 0.1 or less, and a weight average molecular weight 1 million or more copolymer, and the said (meth) acrylate monomer with respect to 100 weight part (3) What contains 0.01-0.8 weight part of isocyanate compounds as a crosslinking agent with respect to a total of 100 weight part of And a gong.

In the pressure-sensitive adhesive composition according to the present invention, examples of the alkyl (meth) acrylate monomer having an alkyl group of C1 to C14 include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and isopropyl. (Meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, iso Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl ( At least 1 type, such as a meta) acrylate, a tridecyl (meth) acrylate, tetradecyl (meth) acrylate, cyclopentyl (meth) acrylate, and a cyclohexyl (meth) acrylate, is mentioned. The alkyl group of the alkyl (meth) acrylate monomer may be linear, branched or cyclic.

70 weight part or more is preferable and 100 weight part of the sum total of the alkyl (meth) acrylate monomer whose C1-C14 carbon number of an alkyl group is in a total of 100 weight part of a (meth) acrylate monomer. It is preferable that the alkyl (meth) acrylate monomer whose C1-C14 carbon number of an alkyl group is 50-99.9 weight part with respect to 100 weight part of acrylic polymer (copolymer) of an adhesive composition. In the present invention, butyl acrylate is an essential monomer. It is preferable to contain a butyl acrylate at least 30 weight part or more in 100 weight part of total (meth) acrylate monomers.

In the present invention, the pressure-sensitive adhesive composition is a monomer of methyl acrylate in a total of 100 parts by weight of a (meth) acrylate monomer composed of one or more of alkyl (meth) acrylate monomers having C 1 to C 14 carbon atoms in the alkyl group. By containing in a weight part or more ratio, the refractive index of an adhesive layer can be raised to 1.47 or more.

The adhesive composition which concerns on this invention can further contain 1 or more types of the (meth) acrylate monomer which has an aromatic group as a (meth) acrylate monomer. As a (meth) acrylate monomer which has an aromatic group, benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxy butyl (meth) acrylate, 2- (1- Naphthyloxy) ethyl (meth) acrylate, 2- (2-naphthyloxy) ethyl (meth) acrylate, 6- (1-naphthyloxy) hexyl (meth) acrylate, 6- (2-naphthyl Oxy) hexyl (meth) acrylate, 8- (1-naphthyloxy) octyl (meth) acrylate, 8- (2-naphthyloxy) octyl (meth) acrylate, etc. are mentioned. In order to obtain the adhesive layer with high refractive index, it is preferable to mix | blend at least 1 sort (s) or more of the (meth) acrylate monomer which has an aromatic group.

By mixing the (meth) acrylate monomers having these aromatic groups with the alkyl (meth) acrylate monomers having C1 to C14 carbon atoms in the alkyl group, the refractive index of the pressure-sensitive adhesive layer obtained can be increased and adjusted, and the refractive index difference between the optical members is reduced, By reducing the total reflection, the total light transmittance can be improved. In the adhesive layer which concerns on this invention, when making a adhesive composition contain the (meth) acrylate monomer which has an aromatic group, it is preferable to contain in a ratio of 5-30 weight part in 100 weight part of total (meth) acrylate monomers. Do.

Moreover, by copolymerizing the (meth) acrylate monomer which has an aromatic group, the effect of raising the refractive index of an adhesive layer by containing the monomer of methyl acrylate in the ratio of 20 weight part or more among 100 weight part of said (meth) acrylate monomers in total. The refractive index of an adhesive layer can be raised further.

In addition, as mentioned above, as a method of improving the refractive index of an adhesive layer, the method of containing the monomer of methyl acrylate in the ratio of 20 weight part or more in a total of 100 weight part of a (meth) acrylate monomer, and (meth) which has an aromatic group Although there exist two methods of the method of copolymerizing an acrylate monomer, each method can be employ | adopted independently, It is more preferable to use these two methods together.

In the pressure-sensitive adhesive composition of the present invention, the acrylic polymer does not contain a carboxyl group-containing copolymerizable vinyl monomer as the functional group-containing monomer, and contains a hydroxyl group-containing copolymerizable vinyl monomer. As the functional group-containing monomer, only the hydroxyl group-containing copolymerizable vinyl monomer may be used.

As a hydroxyl-containing copolymerizable vinyl monomer, for example, 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy Hydroxyl-containing alkyl (meth) acrylates, such as ethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. At least 1 type or more, such as the hydroxyl group containing (meth) acrylamide, is mentioned.

Especially, a hydroxyl-containing copolymerizable vinyl monomer is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxyethyl (meth). It is preferable that it is at least 1 sort (s) or more selected from the group of compounds which consist of an acrylate.

Moreover, in the adhesive layer which concerns on this invention, the hydroxyl group containing copolymerizable vinyl monomer contained in an adhesive composition has a carboxyl group considered that the adhesive layer obtained has an influence on the corrosion property with respect to the to-be-adhered body, such as the ITO surface of a transparent conductive film. It can be used as a copolymerizable monomer for reducing the content of the containing copolymerizable vinyl monomer. For this reason, a hydroxyl-containing copolymerizable vinyl monomer can be helpful in improving the adhesive force of an adhesive layer, and also reducing corrosiveness. In the adhesive layer which concerns on this invention, it is preferable that the hydroxyl group containing copolymerizable vinyl monomer contained in an adhesive composition is 0.1-3.5 weight part in a total of 100 weight part of a (meth) acrylate monomer.

The acrylic polymer of the adhesive composition used for the adhesive layer of this invention is a (meth) acrylate monomer which has a C1-C14 alkyl (meth) acrylate monomer and an aromatic group as a (meth) acrylate monomer. It contains at least 1 sort (s) or more selected from the monomer group which consists of, and does not contain at least 30 weight part or more of butyl acrylate, and a carboxyl group-containing copolymerizable vinyl monomer in 100 weight part of total of said (meth) acrylate monomers, (2) 0.1-3.5 weight part of hydroxyl-containing copolymerizable vinyl monomers are contained with respect to a total of 100 weight part of a (meth) acrylate monomer, an acid value is 0.1 or less and a weight average molecular weight is a copolymer of 1 million or more.

The polymerization method of a copolymer is not specifically limited, A well-known polymerization method, such as a solution polymerization method and an emulsion polymerization method, can be used. It is preferable that the said acryl-type polymer contains 50-100 weight% of acryl-type monomers, such as a (meth) acrylate monomer and (meth) acrylamide.

The said adhesive composition can adjust characteristics, such as a required physical property value, by mix | blending a crosslinking agent and arbitrary additives suitably to the said acrylic polymer.

(3) As a crosslinking agent, a biuret modified body and isocyanurate modified body of diisocyanates, such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate, for example At least 1 sort (s) or more of polyisocyanate compounds, such as an adduct with trivalent or more polyols, such as trimethylol propane and glycerol, is mentioned. It is preferable that an acryl-type polymer has a hydroxyl group as a functional group which can crosslink-react with an isocyanate compound of a crosslinking agent, and it is preferable to contain the monomer which has these functional groups in a side chain. Moreover, it is preferable that an adhesive composition contains 0.01-0.8 weight part of isocyanate compounds with respect to a total of 100 weight part of a (meth) acrylate monomer. (3) You may use only an isocyanate compound as a crosslinking agent. As an isocyanate compound, the adduct body of tolylene diisocyanate is preferable, and the trimethylolpropane adduct body of tolylene diisocyanate is especially preferable.

It is preferable that the said adhesive composition contains (4) silane coupling agent further. (4) As a silane coupling agent, the compound which has at least 1 organic functional group and at least 1 hydrolysable group in 1 molecule, and the alkoxy group etc. which the said hydrolysable group couple | bonded with the silicon atom is mentioned. It is preferable that the said silane coupling agent has at least 1 sort (s) of organic functional group chosen from the group which consists of an epoxy group, a (meth) acryloxy group, a mercapto group, and an amino group. Here, (meth) acryloxy group refers means an acryloxy group (CH ₂ = CHCOO-), or, methacrylic oxy group _{(CH 2 = C (CH 3} ) COO-).

Examples of the silane coupling agent having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidyl silane. Doxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, 2- (3,4-epoxycyclo Hexyl) ethylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 5,6-epoxyhexylmethyldimethoxysilane, 5,6 -Epoxyhexyl methyl diethoxysilane, 5, 6- epoxyhexyl triethoxysilane, etc. are mentioned.

As a silane coupling agent which has a (meth) acryloxy group, 3- (meth) acryloxypropyl trimethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxy Propyl triethoxysilane, 3- (meth) acryloxypropyl methyl diethoxysilane, 3- (meth) acryloxypropyl dimethyl ethoxysilane, 3- (meth) acryloxypropyl dimethyl methoxysilane, etc. are mentioned.

As a silane coupling agent which has a mercapto group, for example, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptopropyl Triethoxysilane etc. are mentioned.

As a silane coupling agent which has an amino group, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-phenyl-3- aminopropyl trimethoxysilane, N-2- (amino Ethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldiethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N- 2- (aminoethyl) -3-aminopropyltriethoxysilane, 3- (methylamino) propyltrimethoxysilane, 3- (methylamino) propyltriethoxysilane, etc. are mentioned.

Moreover, the alkoxy oligomer (silicon alkoxy oligomer) etc. which oligomerized including the said organic functional group can also be used as a silane coupling agent.

(4) As for content of a silane coupling agent, 0.01-0.5 weight part of silane coupling agents is preferable with respect to a total of 100 weight part of a (meth) acrylate monomer.

As other arbitrary components, well-known additives, such as antioxidant, surfactant, a hardening accelerator, a plasticizer, a filler, a crosslinking catalyst, a crosslinking retardant, a hardening retardant, a processing aid, an antioxidant, can be mix | blended suitably. These may be used alone or in combination of two or more thereof.

The adhesive layer of this invention can be obtained by crosslinking an adhesive composition after apply | coating the said adhesive composition to a base material or a release film. It is preferable that the gel fraction of the adhesive layer after crosslinking is 40 to 75%.

When used for interlayer bonding of an optical member, etc., it is preferable that it is a thin adhesive layer, 1 micrometer-25 micrometers are preferable, and, as for the thickness of the said adhesive layer, 5 micrometers-25 micrometers are more preferable. In addition, although the adhesive force of an adhesive layer is generally proportional to the thickness of an adhesive layer, it is preferable that the adhesive force of the adhesive layer whose thickness is 25 micrometers is 1.5-6.0 N / 25mm. Moreover, after bonding an adhesive layer to a to-be-adhered body, it is preferable that the adhesive force after 70 degreeC x 10 days is 1.5-10 N / 25mm. As an adherend, glass plates, such as an alkali free glass, a resin film etc. are mentioned.

When the adhesive layer which concerns on this invention is used for the interlayer bonding of an optical member, etc., in order to reduce reflection of the light ray in the interface of an adhesive layer and an optical member, it is preferable that refractive index difference is as small as possible. For this reason, it is preferable that the refractive index of the said adhesive layer is 1.47-1.50.

The adhesive film of this invention can be manufactured by forming the adhesive layer of this invention on one surface of a base material or a release film.

As a base film used for formation of an adhesive layer, and a release film (separator) which protects an adhesive surface, resin films, such as a polyester film, etc. can be used.

The base film can be subjected to antistatic treatment by antifouling treatment with a silicone-based, fluorine-based releasing agent, coating agent, silica fine particles or the like, application or mixing of an antistatic agent, etc., on the side opposite to the side where the pressure-sensitive adhesive layer of the resin film is formed.

A mold release process is performed to a release film with silicone type, a fluorine-type release agent, etc. to the surface of the side matched with the adhesive face of an adhesive layer.

It can also be set as the structure of a "release film / adhesive layer / release film" by aligning the surface on which the mold release process of the release film was performed to both surfaces of one adhesive layer, respectively. In this case, it is possible to bond with optical members, such as an optical film, by peeling a release film of both sides sequentially or simultaneously and exposing an adhesive surface. As an optical film, a polarizing film, retardation film, an antireflection film, an antiglare (anti glare) film, an ultraviolet absorbing film, an infrared absorption film, an optical compensation film, a brightness improving film, etc. are mentioned.

The adhesive film of this invention can be used for pasting together various optical films for peripheral members of the liquid crystal display device which mainly uses a polarizing plate, various optical films for touch panels, various optical films for electronic paper, and various optical films for organic EL.

Moreover, it can be set as the optical film with an adhesive layer in which the said adhesive layer is laminated | stacked on at least one surface of these optical films. Specifically, "optical film / adhesive layer / optical film", "optical film / adhesive layer / mold release film", "optical film / adhesive layer", "optical film / adhesive layer / optical film / adhesive layer / optical film" And "optical film / adhesive layer / optical film / adhesive layer / mold release film", and "release film / adhesive layer / optical film / adhesive layer / mold release film".

For example, when it has an adhesive layer protected with a release film like "optical film / adhesive layer / mold release film", a release film is peeled off and an adhesive layer is expressed like an "optical film / adhesive layer", and another optical By bonding with a film, the structure similar to the "optical film / adhesive layer / optical film" in which the adhesive layer was used for interlayer bonding is obtained.

The adhesive film of this invention is used suitably for bonding of a polarizing plate and a display panel. For example, it is used as an adhesive layer of the polarizing plate in which an adhesive layer was formed. As a constituent material of the polarizing plate, a retardation film having a phase difference of λ / 4 or λ / 2 may be used.

Example

Hereinafter, the present invention will be described in detail through examples.

<Production of Acrylic Polymer>

Example 1

Nitrogen gas was introduce | transduced into the reaction apparatus provided with the stirrer, the thermometer, the reflux condenser, and the nitrogen inlet tube, and the air in the reaction apparatus was replaced with nitrogen gas. Thereafter, 60 parts by weight of a solvent (ethyl acetate) was added to the reaction apparatus together with 100 parts by weight of butyl acrylate and 0.2 parts by weight of 8-hydroxyoctyl acrylate. Then, 0.1 weight part of azobisisobutyronitrile was dripped over 2 hours as a polymerization initiator, and it reacted at 65 degreeC for 6 hours, and the acrylic polymer solution (1) used for Example 1 with a weight average molecular weight of 1 million or more was carried out. Got it. A part of the acrylic polymer was taken out and used as a measurement sample of acid value mentioned later.

[Examples 2 to 5 and Comparative Examples 1 to 3]

Examples 2-5 and Comparative Example 1 were carried out in the same manner as in the acrylic polymer solution (1) used in Example 1, except that the composition of the monomers was set as described in (1) and (2) in Table 1, respectively. The acrylic polymer solution used for -3 was obtained. In addition, although a measurement result is not specifically shown, the weight average molecular weight of the acrylic polymer contained in the acrylic polymer solution of Examples 2-5 and Comparative Examples 1-3 is 1 million or more.

<Manufacture of an adhesive composition, an adhesive layer, and an adhesive film>

Example 1

0.2 weight part of coronate L (trimethylolpropane (TMP) adduct of a tolylene diisocyanate (TDI) compound) with respect to the acrylic polymer solution (1) of Example 1 manufactured as mentioned above, KBM-403 (3- 0.05 weight part of glycidoxy propyl trimethoxysilane) was added, and it stirred and mixed, and obtained the adhesive composition of Example 1. The pressure-sensitive adhesive composition is crosslinked by applying the pressure-sensitive adhesive composition on a release film made of a silicone resin-coated polyethylene terephthalate (PET) film and then drying at 90 ° C. to remove the solvent, and then aging under 23 ° C. and 50% RH for 7 days. The adhesive film of Example 1 which has the 25-micrometer-thick adhesive layer on one side of a release film was obtained.

[Examples 2 to 5 and Comparative Examples 1 to 3]

The adhesive films of Examples 2 to 5 and Comparative Examples 1 to 3 were prepared in the same manner as in the adhesive film of Example 1, except that the compositions of the additives were the same as those described in the groups (3) and (4) in Table 1, respectively. Got it.

In Table 1, the numerical value of a weight part is shown in parentheses as addition ratio from group (2) to (4) calculated | required by making the sum total of group (1) into 100 weight part.

In addition, the compound name of the symbol of each component used in Table 1 is shown in Table 2. Coronate L is a trade name of Nippon Polyurethane Industry Co., Ltd., D-110N is a trade name of Mitsui Chemical Co., Ltd., and KBM-403 and KBM-803 are trade names of Shin-Etsu Chemical Co., Ltd. TDI means tolylene diisocyanate, TMP means trimethylolpropane and XDI means xylylene diisocyanate. In Table 1 and Table 2, the carboxyl group-containing copolymerizable vinyl monomer was described in group (2) together with the hydroxyl group-containing copolymerizable vinyl monomer.

<Test method and evaluation>

The release film (silicon resin-coated PET film) was peeled from the adhesive films in Examples 1-5 and Comparative Examples 1-3, the adhesive layer was expressed, and the adhesive layer was transferred to one side of the polarizing plate (film).

<Measuring method of adhesive force>

An adhesive layer having a thickness of 25 μm was transferred to one surface of a polarizing plate (film) having a thickness of 180 μm, thereby obtaining an adhesive film (optical film having an adhesive layer formed) as a sample.

The obtained pressure-sensitive adhesive film was bonded to a non-tin surface washed with acetone of an alkali free glass with a squeeze roll, and subjected to autoclave treatment under conditions of 50 ° C. and 0.5 MPa × 20 minutes, and then returned to an atmosphere of 23 ° C. × 50% RH for 1 hour. Passed. The peeling strength of the adhesive film after that is measured with the tensile tester based on JISZ0237 "adhesive tape and adhesive sheet test method," and the peeling strength at the time of peeling at 300 mm / min in 180 degree direction is an adhesive film. It was set as the adhesive force (N / 25mm) of the adhesive layer of the.

<Measurement method of acid value>

The acid value of the acrylic polymer was dissolved in a solvent (mixed with diethyl ether and ethanol in a volume ratio of 2: 1), and the concentration was about 0.1 using a potentiometric automatic titrator (AT-610, Kyoto Electronics). Potentiometric titration was carried out with a mol / l potassium hydroxide ethanol solution to determine the amount of potassium hydroxide ethanol solution required to neutralize the sample. And the acid value was calculated | required from the following formula.

Acid value = (B × f × 5.611) / S

B = amount of 0.1 mol / L potassium hydroxide ethanol solution used in titration (ml)

factor of f = 0.1mol / l potassium hydroxide ethanol solution

S = mass (g) of solids in the sample

<Measurement method of gel fraction>

After the end of aging, the mass of the measurement sample before bonding to the polarizing plate is accurately measured, and after immersion in toluene for 24 hours, it is filtered through a 200 mesh wire mesh. Then, after drying a filtrate at 100 degreeC for 1 hour, the mass of a residue was measured correctly and the gel fraction of the adhesive layer (pressure-sensitive adhesive after crosslinking) was computed from the following formula | equation.

Gel fraction (%) = insoluble partial mass (g) / adhesive mass (g) x 100

<Test method of the durability>

A 10 cm-thick adhesive film produced in the same manner as the measurement of the adhesive force was bonded to the non-tinned surface of the alkali-free glass in the same manner to prepare a sample prepared in a predetermined atmosphere (80 ° C. dry atmosphere, or 60 ° C. × 90% RH). Atmosphere), and after leaving for 250 hours under 23 ° C. × 50% RH atmosphere, the adhesive film state was visually observed after 1 hour to determine durability.

There is no peeling and foaming of an adhesive film.

(Triangle | delta) ... and peeling and foaming generate | occur | produce in a part of adhesive film.

Peeling and foaming generate | occur | produce the whole of an adhesive film.

<Test method of rework property>

After a 10-cm-thick adhesive film produced by the same method as the measurement of adhesive force was bonded to the non-tinned surface of an alkali-free glass by the same method, the sample produced was left for 10 days in an atmosphere of 70 ° C, and then taken out in an atmosphere of 23 ° C, The reworkability was judged by measuring the adhesive force of the adhesive film after leaving for 1 hour.

The adhesive force after (circle) 70 degreeC * 10 days is 1.5-10 N / 25mm.

Although adhesive force after (triangle | delta) ... 70 degreeC x 10 days is larger than 10 N / 25 mm, it is 20 N / 25 mm or less.

Adhesion after x 10 占 폚 x 10 days is greater than 20 N / 25 mm (cannot be peeled).

Table 3 shows the results of the evaluation. Regarding the acid value, the acrylic polymers of Examples 1 to 5 which do not contain a carboxyl group-containing copolymerizable vinyl monomer and the acrylic polymers of Comparative Example 1 which have an acid value of 0.1 or less and contain a carboxyl group-containing copolymerizable vinyl monomer It was confirmed that the acid value of was greater than 0.1.

The adhesive films of Examples 1-5 had the adhesive force of the adhesive layer of thickness 25micrometer in the range of 1.5-6.0 N / 25mm, the gel fraction of the adhesive layer after crosslinking was 40 to 75%, and was excellent in adhesiveness and durability. Moreover, since the adhesive force after 70 degreeC x 10 days after bonding to a to-be-adhered body was the range of 1.5-10 N / 25mm, it was also excellent in rework property. That is, in the adhesive films of Examples 1-5, requirements and a problem were able to be overcome.

The pressure-sensitive adhesive film of Comparative Example 1 does not contain butyl acrylate as a (meth) acrylate monomer, but contains a carboxyl group-containing copolymerizable vinyl monomer as a functional group-containing monomer and has a high gel fraction. Adhesive strength was strong and the durability and rework property in the atmosphere of 60 degreeCx90% RH were inferior.

The pressure-sensitive adhesive film of Comparative Example 2 is because the compounding amount of the hydroxyl group-containing copolymerizable vinyl monomer in the pressure-sensitive adhesive composition is too large, and the gel fraction is high, so that the durability in the atmosphere of 60 ° C. × 90% RH is inferior, and the durability and resibility in the 80 ° C. dry atmosphere Walk was also slightly off.

Since the adhesive film of Comparative Example 3 does not contain either a carboxyl group-containing copolymerizable vinyl monomer or a hydroxyl group-containing copolymerizable vinyl monomer in the pressure-sensitive adhesive composition, the acrylic polymer is not crosslinked, the gel fraction is 0, and the adhesive force of the pressure-sensitive adhesive layer having a thickness of 25 μm. This is very strong. As a result, durability and reworkability were inferior.

As described above, in the pressure-sensitive adhesive films of Comparative Examples 1 to 3, conventional requirements and problems could not be overcome.

Claims (5)

In the adhesive layer which crosslinks the adhesive composition containing an acrylic polymer and a crosslinking agent,
The acrylic polymer,
(A) As a (meth) acrylate monomer, At least 1 sort (s) or more of the (meth) acrylate monomer which has an aromatic group and at least 1 sort (s) of the C1-C14 alkyl (meth) acrylate monomer of an alkyl group are contained, 100 parts by weight in total of the (meth) acrylate monomer,
(B) As functional group containing monomer, only 0.1-3.5 weight part of hydroxyl-containing copolymerizable vinyl monomers
It is an acrylic polymer copolymerized, the acid value is 0.1 or less, and a weight average molecular weight is 1 million or more copolymers,
In total of 100 weight part of said (meth) acrylate monomers, 30 weight part or more of butyl (meth) acrylates and the sum total of at least 1 or more types of (meth) acrylate monomer which have an aromatic group are contained in the ratio of 5-30 weight part Done by
The said adhesive composition consists of 0.01-0.8 weight part of isocyanate compounds and 0.01-0.5 weight part of silane coupling agents as said crosslinking agent with respect to a total of 100 weight part of said (meth) acrylate monomers,
The said silane coupling agent has at least 1 sort (s) or more organic functional group chosen from the group which consists of an epoxy group, a (meth) acryloxy group, and a mercapto group, The adhesive layer characterized by the above-mentioned. The method of claim 1,
The hydroxyl group-containing copolymerizable vinyl monomer (B) is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (Meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide and at least one or more selected from the group consisting of compounds Pressure-sensitive adhesive layer. The adhesive layer of Claim 1 or 2 was laminated | stacked on one surface of a base material, The adhesive film characterized by the above-mentioned. The method according to claim 1 or 2,
An adhesive layer used as an adhesive layer of the polarizing plate in which an adhesive layer was formed. The optical film with an adhesive layer in which the adhesive layer of Claim 1 or 2 is laminated | stacked on at least one surface of an optical film.