JP2017048340A - Adhesive composition for optical use, and adhesive layer and adhesive optical film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition for optical use suitable for the production of an adhesive optical film having high transparency, little degradation and high durability even exposed to strong light for a long time under high temperature and high humidity conditions, and an adhesive layer and an adhesive optical film using the composition.SOLUTION: The adhesive composition for optical use comprises an acrylic (co)polymer resin prepared by polymerizing a monomer composition containing at least an acrylic acid-based alkyl ester, and a UV absorber represented by formula (1).SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to an optical pressure-sensitive adhesive composition that imparts high durability, and a pressure-sensitive adhesive layer and a pressure-sensitive adhesive optical film using the same.

  In recent years, optical films have been industrially produced and used in large quantities due to the widespread use of liquid crystal displays. Liquid crystal displays starting from small displays such as watches and calculators are also applicable to high-priced and highly durable devices such as personal computers, liquid crystal televisions, liquid crystal projectors, in-vehicle instrument panels, and in-vehicle navigation systems. It has come to be. In addition, liquid crystal displays are required to have high brightness. With these changes, durability against high temperature, high humidity, and light irradiation has been increasingly required for liquid crystal displays. Among the reliability of the liquid crystal display, one of the parts that is most desired to be improved is a polarizing plate. A conventional polarizing plate for liquid crystal is a pressure-sensitive adhesive type (hereinafter, also referred to as “adhesive type”) polarization using a pressure-sensitive adhesive in order to reduce assembly loss and optical loss on the surface. There is a demand for improved durability of the pressure-sensitive adhesive layer.

  In general, a pressure-sensitive adhesive polarizing plate is formed on both sides of a stretched polyvinyl alcohol (hereinafter referred to as “PVA”) film in which iodine or a dichroic dye is aligned as a polarizer. An acetyl cellulose (hereinafter also referred to as “TAC”) film is laminated and adhered, and a pressure-sensitive adhesive layer is further provided on the surface of the TAC film. In the production of a liquid crystal display, in general, this pressure-sensitive adhesive polarizing plate has been bonded to the glass plate surface of a liquid crystal cell via a pressure-sensitive adhesive layer. When a liquid crystal cell with a polarizing plate made in this way is exposed for a long time under the conditions of high temperature, high humidity, or high-intensity light irradiation, the polarizing plate becomes deteriorated to become cloudy, discolored, or physically destroyed. In particular, the function as a polarizing plate may be completely lost.

  On the other hand, a method of providing a phase difference plate between a liquid crystal cell and a polarizing plate has become widespread. Known retardation films include stretched films such as polycarbonate and cycloolefin, or films in which retardation is expressed by aligning liquid crystal elements. This one or more retardation plates are bonded to a liquid crystal cell via a pressure-sensitive adhesive layer, and a polarizing plate is bonded to the outermost layer to constitute a liquid crystal display. In this case, as in the case of bonding the polarizing plate alone, exposure to a long time under high temperature, high humidity conditions, or high intensity light irradiation results in white turbidity, discoloration, and physical destruction, and is not so long. With time, the phase difference value may change, the function of the polarizing plate may be lowered, the color may be changed, and eventually the function may be completely lost.

JP 59-11114 A JP-A-4-254803

  As means for preventing the deterioration of the optical film, there are a method for reducing the acrylic acid content of the pressure-sensitive adhesive (for example, Patent Document 1), a method for adding a tertiary amine to the pressure-sensitive adhesive (for example, Patent Document 2), and the like. Proposed. However, although these means are effective in preventing the deterioration of the polarizing plate, the adhesiveness with the glass decreases under high temperature and high humidity, causing peeling and the like, and the durability tends to decrease.

  Accordingly, an object of the present invention is to provide an optical pressure-sensitive adhesive composition suitable for producing a highly durable pressure-sensitive adhesive optical film having high transparency and little deterioration even when exposed to strong light for a long time under conditions of high temperature and high humidity. And providing a pressure-sensitive adhesive layer and a pressure-sensitive adhesive optical film using the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has optically containing an acrylic (co) polymer resin obtained by polymerizing a monomer composition containing at least an acrylic acid alkyl ester and a specific ultraviolet absorber. It has been found that the pressure-sensitive adhesive composition achieves the above object, and has completed the present invention. That is, the present invention relates to the following [1] to [9].

（Ｒ_１及びＲ_２は各々独立して、水素原子、アミノ基、アルキル基、アルキルエーテル基、炭素数１〜６のアルキルエステル基、シアノ基、ベンゾチアゾール基、又は置換基を有するフェニル基を示し、Ｒ_３は水素原子、アミノ基、シアノ基、又は炭素数１〜３のアルキルチオール基を示し、Ｒ_４は水素原子、炭素数１〜３のアルキル基、又はアリル基を示す。）
で表される紫外線吸収剤と
を含有する光学用粘着剤組成物。
［２］ 前記紫外線吸収剤が、下記式（２）：

（Ｒ_１、Ｒ_３、及びＲ_４は式（１）におけるものと同じものを示す。）
で表される上記［１］に記載の光学用粘着剤組成物。
［３］ 前記アクリル酸系アルキルエステルが、（メタ）アクリル酸ｎ−ブチル、（メタ）アクリル酸ｔ−ブチル、及び（メタ）アクリル酸メチルからなる群から選択される１種以上である上記［１］又は［２］に記載の光学用粘着剤組成物。
［４］ 前記モノマー組成物が、アクリル酸系アルキルエステル１００質量部に対して、水酸基を有する重合性モノマーを０．５〜７質量部と、アミド基を有する重合性モノマーを０．５〜２９質量部とをさらに含む上記［１］〜［３］のいずれかに記載の光学用粘着剤組成物。
［５］ 前記モノマー組成物が、アクリル酸系アルキルエステル１００質量部に対して、０．５〜７質量部のカルボキシル基を有する重合性モノマーをさらに含む上記［１］〜［４］のいずれかに記載の光学用粘着剤組成物。
［６］ 前記アクリル（共）重合樹脂の重量平均分子量が５００，０００〜２，０００，０００である上記［１］〜［５］のいずれかに記載の光学用粘着剤組成物。
［７］ 上記［１］〜［６］のいずれかに記載の光学用粘着剤組成物から得られる粘着剤層。
［８］ 光学フィルムの片面又は両面に上記［７］に記載の粘着剤層を備える粘着型光学フィルム。
［９］ 前記光学フィルムが、偏光性フィルム又は位相差フィルムである上記［８］に記載の粘着型光学フィルム。 [1] An acrylic (co) polymer resin obtained by polymerizing a monomer composition containing at least an acrylic acid alkyl ester;
Following formula (1):

(R ₁ and R ₂ are each independently a hydrogen atom, an amino group, an alkyl group, an alkyl ether group, an alkyl ester group having 1 to 6 carbon atoms, a cyano group, a benzothiazole group, or a phenyl group having a substituent. R ₃ represents a hydrogen atom, an amino group, a cyano group, or an alkylthiol group having 1 to 3 carbon atoms, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an allyl group.)
The optical adhesive composition containing the ultraviolet absorber represented by these.
[2] The ultraviolet absorber is represented by the following formula (2):

(R ₁ , R ₃ , and R ₄ are the same as those in formula (1).)
The adhesive composition for optics as described in said [1] represented by these.
[3] The above-mentioned [1], wherein the acrylic acid alkyl ester is at least one selected from the group consisting of n-butyl (meth) acrylate, t-butyl (meth) acrylate, and methyl (meth) acrylate. 1] or [2] The optical pressure-sensitive adhesive composition according to [2].
[4] The monomer composition has 0.5 to 7 parts by mass of a polymerizable monomer having a hydroxyl group and 0.5 to 29 parts of a polymerizable monomer having an amide group with respect to 100 parts by mass of an acrylic acid alkyl ester. The optical pressure-sensitive adhesive composition according to any one of the above [1] to [3], further comprising a mass part.
[5] Any of the above [1] to [4], wherein the monomer composition further comprises a polymerizable monomer having a carboxyl group of 0.5 to 7 parts by mass with respect to 100 parts by mass of the acrylic acid alkyl ester. An optical pressure-sensitive adhesive composition as described in 1.
[6] The optical pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the acrylic (co) polymer resin has a weight average molecular weight of 500,000 to 2,000,000.
[7] A pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to any one of [1] to [6].
[8] A pressure-sensitive adhesive optical film comprising the pressure-sensitive adhesive layer according to the above [7] on one side or both sides of the optical film.
[9] The pressure-sensitive adhesive optical film according to [8], wherein the optical film is a polarizing film or a retardation film.

  The present invention relates to an optical pressure-sensitive adhesive composition suitable for producing a highly durable pressure-sensitive adhesive optical film having high transparency and little deterioration even when exposed to strong light for a long time under conditions of high temperature and high humidity, and the use thereof. A pressure-sensitive adhesive layer and a pressure-sensitive adhesive optical film can be provided.

[Optical pressure-sensitive adhesive composition]
The optical pressure-sensitive adhesive composition according to the present invention is an acrylic (co) polymer resin containing an acrylic (co) polymer resin obtained by polymerizing a monomer composition containing at least an acrylic acid alkyl ester, and an ultraviolet absorber. It is an adhesive composition.

  The acrylic (co) polymer resin is a (co) polymer of a monomer composition containing at least an acrylic acid alkyl ester. The monomer composition contains, in addition to acrylic acid alkyl ester, further monomer components such as a polymerizable monomer having a hydroxyl group, a polymerizable monomer having an amide group, and / or a polymerizable monomer having a carboxyl group, as necessary. be able to. The monomer composition preferably contains at least two or more acrylic acid alkyl esters or at least one or more acrylic acid acrylic esters and one or more different monomer components.

  Examples of the acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic. 1 type selected from the group consisting of C1-12 alkyl esters of (meth) acrylic acid such as n-butyl acid, t-butyl (meth) acrylate, and dodecyl (meth) acrylate, or a combination of two or more types is there. Preferably, the acrylic acid alkyl ester is one kind or two or more kinds selected from the group consisting of n-butyl (meth) acrylate, t-butyl (meth) acrylate, and (meth) acrylate-methyl. It is a combination. In particular, the acrylic acid alkyl ester is a combination of n-butyl (meth) acrylate and t-butyl (meth) acrylate, or n-butyl (meth) acrylate, t-butyl (meth) acrylate, and ( A combination of (meth) methyl acrylate is preferable because durability is particularly good. Here, “(meth) acrylic acid” means acrylic acid and / or methacrylic acid.

  The content of the monomer unit based on the acrylic acid-based alkyl ester in the acrylic (co) polymer resin is preferably 50 to 100% by mass, more preferably 70 to 95% by mass. When the content of the acrylic acid alkyl ester is 50% by mass or more, the solubility of the ultraviolet absorber is increased, and a decrease in transmittance due to precipitation of the ultraviolet absorber is suppressed. Furthermore, even when exposed to high temperature, high humidity, and high intensity light, the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition is deteriorated, for example, foaming, generation of minute defects, precipitation of ultraviolet absorbers, etc. Decrease in adhesiveness and transparency with glass, film and the like hardly occur, and degradation of the optical film provided with the pressure-sensitive adhesive layer, such as discoloration, white turbidity, and physical destruction, can be reduced.

  Examples of the polymerizable monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2- Examples include hydroxy C1-5 alkyl (meth) acrylates such as hydroxypropyl methacrylate, diethylene glycol monoacrylate, and diethylene glycol (meth) acrylates such as diethylene glycol monomethacrylate, and glycidyl methacrylate and allyl glycidyl ether. The content of the polymerizable monomer having a hydroxyl group in the monomer composition is preferably 0.5 to 7 parts by mass, more preferably 0.8 to 4.3 parts by mass with respect to 100 parts by mass of the acrylic acid alkyl ester. It is. By containing a polymerizable monomer having a hydroxyl group, the transparency of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition is further increased, and the high-temperature, high-humidity, and high-pressure of the pressure-sensitive adhesive layer and the optical film provided with the pressure-sensitive adhesive layer are increased. The durability against intense light irradiation can be further improved.

  Examples of polymerizable monomers having an amide group include N, N-dimethylaminopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N-methylolacrylamide, and acrylamide. Examples include acrylamide monomers. The content of the polymerizable monomer having an amide group in the monomer composition is preferably 0.5 to 29 parts by mass, more preferably 3 to 21 parts by mass with respect to 100 parts by mass of the acrylic acid alkyl ester. By including a polymerizable monomer having an amide group, the transparency of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition is increased, and the high-temperature, high-humidity, and high-pressure of the pressure-sensitive adhesive layer and the optical film provided with the pressure-sensitive adhesive layer are increased. The durability against intense light irradiation can be further improved.

  Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, and itaconic acid. When the polymerizable monomer having a carboxyl group is contained in the monomer composition in combination with the polymerizable monomer having an amide group, the compatibility of the pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive composition is not impaired. This is preferable because the transparency is not lowered. The content of the polymerizable monomer having a carboxyl group in the monomer composition is preferably 0.5 to 7 parts by mass, more preferably 1 to 4.3 parts by mass with respect to 100 parts by mass of the acrylic acid alkyl ester. . By containing a polymerizable monomer having a carboxyl group in the above range, the UV absorber can be made higher in concentration while suppressing a decrease in the transmittance of the pressure-sensitive adhesive layer, and at a high temperature, high humidity, and high strength. Even under light irradiation conditions, it is possible to further enhance the effect of suppressing deterioration of the pressure-sensitive adhesive layer, for example, deterioration of transparency and adhesion over a long period of time.

  Examples of the polymerizable monomer having no functional group include vinyl acetate, acrylonitrile, and styrene. The content of the polymerizable monomer having no functional group in the monomer composition is preferably 0 to 43 parts by mass with respect to 100 parts by mass of the acrylic acid alkyl ester. By containing a polymerizable monomer having no functional group, the adhesive property of the pressure-sensitive adhesive layer is improved, the transparency is improved, the adhesive property is improved at low and high temperatures, and the optical pressure-sensitive adhesive composition is an optical film. There is an effect such as improving the surface property at the time of coating.

  The monomer composition contains 100 parts by mass of an acrylic acid alkyl ester, 0.5 to 7 parts by mass of a polymerizable monomer having a hydroxyl group, and 0.5 to 29 parts by mass of a polymerizable monomer having an amide group. However, the durability of the resulting pressure-sensitive adhesive optical film can be further enhanced, which is particularly suitable. The monomer composition further contains 0.5 to 7 parts by mass of a polymerizable monomer having a carboxyl group, so that a decrease in the transmittance of the pressure-sensitive adhesive layer is suppressed even when the concentration of the ultraviolet absorber is increased, and high temperature. An optical pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer in which deterioration, for example, a decrease in transparency and adhesion, is further suppressed over a long period of time even under high humidity and high-intensity light irradiation conditions can be obtained. .

  The acrylic (co) polymer resin can be produced by dissolving the monomer composition in an organic solvent and radical (co) polymerizing it in an organic solvent by a general method. Examples of the organic solvent used for polymerization include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, and methyl ethyl ketone and Examples thereof include ketones such as methyl isobutyl ketone. Examples of the polymerization catalyst used for radical polymerization include azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, and the like, which are normal polymerization catalysts.

  The acrylic (co) polymer resin includes monomer units based on each monomer contained in the monomer composition, and the content of each monomer unit corresponds to the content of each monomer in the monomer composition. Accordingly, the acrylic (co) polymer resin preferably contains 50 to 100% by mass of a monomer unit based on an acrylic acid alkyl ester, and, optionally, 100 parts by mass of a monomer unit based on an acrylic acid alkyl ester, 0.5 to 7 parts by mass of a monomer unit based on a polymerizable monomer having a hydroxyl group, preferably 0.5 to 29 parts by mass of a monomer unit based on a polymerizable monomer having an amide group, and a polymerizable monomer having a carboxyl group Preferably, the monomer unit based on is preferably 0.5 to 7 parts by mass, and / or the monomer unit based on a polymerizable monomer having no functional group is preferably further included in an amount of 0 to 43 parts by mass.

  The acrylic (co) polymer resin has a glass transition temperature (hereinafter abbreviated as Tg) of −20 ° C. or less, preferably −30 ° C. to −60 ° C., and a weight average molecular weight of 500,000 to 2,000,000. 000, preferably 700,000 to 1,600,000. When Tg exceeds −20 ° C., the adhesive strength is poor and the durability may be inferior. Further, if the weight average molecular weight is less than 500,000, the heat resistance may be insufficient, and if it exceeds 2,000,000, the adhesion tends to be insufficient, and peeling or the like is likely to occur. is there.

で表される紫外線吸収剤である。
式（１）において、Ｒ_１及びＲ_２は各々独立に、水素原子、アミノ基、アルキル基、アルキルエーテル基、炭素数１〜６のアルキルエステル基、シアノ基、ベンゾチアゾール基、又は置換基を有するフェニル基を示す。アルキル基の炭素数は、好ましくは１〜５である。アルキルエーテルの炭素数は、好ましくは１〜６である。フェニル基が有する置換基は、好ましくは水素原子、炭素数１〜３のアルキル基、炭素数１〜３の低級アルコキシル基、塩素原子、臭素原子、アミノ基、ニトロ基、ヒドロキシル基、シアノ基、カルボニル基、又はアルキルエステル基である。
Ｒ_３は水素原子、アミノ基、シアノ基、又は炭素数１〜３のアルキルチオール基を示す。
Ｒ_４は水素原子、炭素数１〜３のアルキル基、又はアリル基を示す。
本発明者は、ベンゾトリアゾール系やヒドロキシフェニルトリアジン系等の紫外線吸収剤が、光学フィルムの耐久性能の付与にほとんど効果がないのに対し、式（１）で表される紫外線吸収剤を上述のアクリル（共）重合樹脂と組み合わせると、高温、高湿度、及び高強度の光照射条件に対する耐久性を著しく向上させることを予想外にも見出した。 The ultraviolet absorber is represented by the following formula (1):

It is an ultraviolet absorber represented by these.
In Formula (1), R ₁ and R ₂ each independently represent a hydrogen atom, an amino group, an alkyl group, an alkyl ether group, an alkyl ester group having 1 to 6 carbon atoms, a cyano group, a benzothiazole group, or a substituent. It has a phenyl group. Preferably carbon number of an alkyl group is 1-5. The carbon number of the alkyl ether is preferably 1-6. The substituent of the phenyl group is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a lower alkoxyl group having 1 to 3 carbon atoms, a chlorine atom, a bromine atom, an amino group, a nitro group, a hydroxyl group, a cyano group, A carbonyl group or an alkyl ester group.
R ₃ represents a hydrogen atom, an amino group, a cyano group, or an alkylthiol group having 1 to 3 carbon atoms.
R ₄ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an allyl group.
The present inventor has shown that the ultraviolet absorber represented by the formula (1) is not effective in imparting the durability performance of the optical film, while the ultraviolet absorber such as benzotriazole or hydroxyphenyltriazine is almost ineffective. It has been unexpectedly found that when combined with an acrylic (co) polymer resin, the durability against high temperature, high humidity, and high intensity light irradiation conditions is remarkably improved.

で表される化合物であることが好ましい。式（２）中、Ｒ_１、Ｒ_３、及びＲ_４は、式（１）と同じものを示す。
式（１）で表される紫外線吸収剤が、式（２）で表される化合物であるとき、光学用粘着剤組成物の耐久性をさらに向上させることが出来る。 The ultraviolet absorber represented by the formula (1) is represented by the following formula (2):

It is preferable that it is a compound represented by these. In formula (2), R ₁ , R ₃ , and R ₄ are the same as those in formula (1).
When the ultraviolet absorber represented by Formula (1) is a compound represented by Formula (2), the durability of the optical pressure-sensitive adhesive composition can be further improved.

（化合物例２）

（化合物例３）

（化合物例４）

（化合物例５）

（化合物例６）

（化合物例７）

（化合物例８）

（化合物例９）

（化合物例１０）

（化合物例１１）

（化合物例１２）

Specific examples of the ultraviolet absorber represented by the formula (1) are shown below.

(Compound Example 1)

(Compound Example 2)

(Compound Example 3)

(Compound Example 4)

(Compound Example 5)

(Compound Example 6)

(Compound Example 7)

(Compound Example 8)

(Compound Example 9)

(Compound Example 10)

(Compound Example 11)

(Compound Example 12)

  The content of the ultraviolet absorber represented by the formula (1) is preferably 0.1% by mass to 10% by mass in the resin solid content which is the optical pressure-sensitive adhesive composition. If the content of the ultraviolet absorber represented by the formula (1) in the optical pressure-sensitive adhesive composition is not 0.1% by mass or more, the effect may not be obtained, but the optical pressure-sensitive adhesive composition Since it is necessary to keep the amount within a range that does not affect precipitation (transparency) and adhesiveness, the content is more preferably 0.3% by mass to 5% by mass, and further preferably 0.5% by mass to 2% by mass. By containing the ultraviolet absorber represented by the formula (1) in the above range, it not only absorbs light having a wavelength of 420 nm or less and reduces the deterioration of the optical film, but also adheres to the adhesive layer by transmitting light. It is possible to reduce deterioration of properties. In particular, light having a wavelength near 400 nm is light in a band that deteriorates the film and the adhesive layer. Therefore, by containing the ultraviolet absorber represented by the formula (1), high temperature, high temperature and humidity, and high strength are obtained. Even if it is exposed to an environment irradiated with light for a long period of time, discoloration such as yellowing of the optical film and physical destruction can be suppressed, and durability can be greatly improved. Additives such as ultraviolet absorbers may become a deterioration factor of the pressure-sensitive adhesive layer, but even if the ultraviolet light absorber represented by the formula (1) is contained in the optical pressure-sensitive adhesive composition, The decrease in transparency and adhesiveness of the pressure-sensitive adhesive layer when exposed to an environment irradiated with high temperature and high humidity and strong light for a long time is greatly reduced. Therefore, the optical film which provided the adhesive layer which consists of an optical adhesive composition of this application can implement | achieve high durability.

  The optical pressure-sensitive adhesive composition may further contain a crosslinking agent. The crosslinking agent has an effect of further crosslinking the acrylic (co) polymer resin and further enhancing the durability of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition and the optical film provided with the pressure-sensitive adhesive. The type of the crosslinking agent can be appropriately selected by those skilled in the art. For example, polyisocyanate compounds such as aliphatic diisocyanates and aromatic diisocyanates, melamine compounds such as butyl etherified styrene melamine and trimethylol melamine, diamine compounds, epoxy resin compounds, urea resin compounds, metal salts, and the like are crosslinking agents. Used as The content of the crosslinking agent in the optical pressure-sensitive adhesive composition is preferably 0.001 to 10% by mass, more preferably 0.01 to 3% by mass. When the crosslinking agent is added to the acrylic (co) polymer resin, it forms a crosslinking even at room temperature, but the crosslinking by the crosslinking agent can be promoted by performing a heating treatment from 30 ° C. to 60 ° C., for example.

  The optical pressure-sensitive adhesive composition can contain other additives as required, as long as the performance of the pressure-sensitive adhesive is not adversely affected. Examples of the additive include terpene resins and rosin resins. The content of the additive in the optical pressure-sensitive adhesive composition can be appropriately determined by those skilled in the art.

[Adhesive layer]
The pressure-sensitive adhesive layer of the present invention is formed from an optical pressure-sensitive adhesive composition. The pressure-sensitive adhesive layer is generally formed on a protective layer such as an optical film, particularly a polarizing film and a retardation film, or a cellulose-based protective layer provided thereon. The method for forming the pressure-sensitive adhesive layer is not particularly limited, and methods commonly used by those skilled in the art can be used. For example, a method of applying and drying an optical pressure-sensitive adhesive composition, and a method of applying to a release film and drying And a method of transferring the adhesive layer provided. The application is not particularly limited, but can be performed using a coater of a coating system such as a roll coating method, a spin coating method, and a screen coating method. Application | coating of the optical adhesive composition is performed so that the thickness after drying becomes 5-50 micrometers preferably. The thickness of the pressure-sensitive adhesive layer is more preferably 10 to 30 μm, and still more preferably 15 to 25 μm, because durability can be improved.

  The pressure-sensitive adhesive layer according to the present invention is useful as a pressure-sensitive adhesive layer for optical films, and particularly useful as a pressure-sensitive adhesive for bonding a polarizing film or retardation film coated with a cellulose-based protective layer and a glass substrate. is there. The pressure-sensitive adhesive layer according to the present invention is less susceptible to appearance abnormalities such as foaming, peeling and deterioration even when left for a long time in a high temperature and high humidity state and under light irradiation, and maintains transparency and adhesion. Degradation of the optical film provided with the pressure-sensitive adhesive layer can be greatly reduced.

[Adhesive optical film]
The pressure-sensitive adhesive optical film includes an optical film and the pressure-sensitive adhesive layer on one side or both sides of the optical film. The pressure-sensitive adhesive layer may be disposed so as to be in direct contact with the optical film, or may be disposed on the optical film with a layer such as a protective layer for the optical film interposed therebetween. The optical film is not particularly limited, and is, for example, a polarizing film or a retardation film. Polarizing films are usually impregnated with polarizing elements such as iodine and dichroic dyes on films formed from polyvinyl alcohol resins such as polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, and saponified ethylene-vinyl acetate copolymers. In this case, a material imparted with polarization by stretching is preferably used, but other types may be used. As the retardation film, a film provided with retardation by stretching a film produced from a resin such as polyvinyl alcohol, polycarbonate, or cycloolefin is preferably used. It may be a coated film or a film having the layer.

  As the optical film, a film formed by molding a plastic having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, etc. is preferably used, but a plastic film having such a function is used as an optical protective layer. You may provide further on the single side | surface or both surfaces of a film. Examples of plastics having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, etc. include polyester resins, cellulose resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimides. Thermoplastic resins such as epoxy resins, polyolefin resins, and acrylic resins, and thermosetting resins and ultraviolet curable resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone resins. . The polyolefin-based resin may be a non-crystalline polyolefin-based resin having a cyclic polyolefin polymerized unit such as norbornene or a polycyclic norbornene-based monomer. In addition to or in place of the plastic film, a cellulose-based protective layer may be provided on one side or both sides of the optical film. As the cellulose-based protective layer, a cellulose-based film, particularly triacetate cellulose and other transparent acetylcellulose-based films are generally used.

  The pressure-sensitive adhesive optical film according to the present invention retains the transparency and adhesiveness of the pressure-sensitive adhesive layer even when exposed to a high temperature, a high humidity condition, or a high-intensity light condition for a long time. Deterioration such as discoloration and physical destruction, for example, change in retardation value, functional deterioration and discoloration of the polarizing film are reduced, and high durability is achieved. Adhesive type optical films are useful for the use of highly durable and reliable liquid crystal displays using such properties, and are particularly useful for the display of vehicles, various industrial instruments, household appliances, etc. It is.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these.

[Example 1]
83 parts by weight of n-butyl acrylate and 13 parts by weight of methyl acrylate are dissolved in 185 parts by weight of ethyl acetate, 0.05 parts by weight of azobisisobutyronitrile is added, and the reaction is carried out at 70 ° C. for 5 hours. An acrylic copolymer resin (weight average molecular weight: 1,200,000) was obtained. Further, 100 parts by mass of an acrylic copolymer resin solution (viscosity 2,000 cps / 25 ° C.) prepared with ethyl acetate so that the resin content becomes 20% by mass was added to trimethylolpropane (1 mol) of tolylene diisocyanate (3 mol). ) Adduct 0.5 part by mass, γ-glycidoxypropylmethoxysilane 0.5 part by mass, UV absorber as an indole derivative having the structure of the formula (1) (BONASORB UA-3901 manufactured by Orient Chemical Industries) 0 2 parts by mass were mixed and stirred to obtain an optical pressure-sensitive adhesive composition. The obtained pressure-sensitive adhesive composition for optics was coated on a polyvinyl alcohol polarizing plate (SHC-12U, manufactured by Polatechno Co., Ltd.) using a triacetyl cellulose film as a protective layer so that the film thickness after drying was 23 μm. Were laminated so as to be in direct contact with the protective layer and pressed with a roller to produce an adhesive polarizing plate.

[Example 2]
83 parts by weight of n-butyl acrylate, 1 part by weight of 2-hydroxyethyl acrylate and 12 parts by weight of N, N-dimethylacrylamide are dissolved in 185 parts by weight of ethyl acetate, and 0.05 part by weight of azobisisobutyronitrile Was added and reacted at 70 ° C. for 5 hours to obtain an acrylic copolymer resin (weight average molecular weight: 1,3500,000, Tg: −37 ° C.). Further, 100 parts by weight of an acrylic copolymer resin solution (viscosity 2,000 cps / 25 ° C.) prepared with ethyl acetate so that the resin content becomes 20% by mass was added to trimethylolpropane (1 mol) of tolylene diisocyanate (3 mol). ) 0.5 parts by mass of adduct, 0.5 parts by mass of γ-glycidoxypropylmethoxysilane, UV absorber having the structure of formula (1) (BONASORB UA-3901 manufactured by Orient Chemical Industry Co., Ltd.) An optical pressure-sensitive adhesive composition was obtained by mixing 1.0 part by mass with respect to the resin solid content of Example 1. Using the optical pressure-sensitive adhesive composition thus obtained, Example 1 was obtained. In the same manner, an adhesive polarizing plate was produced.

[Example 3]
In Example 2, an ultraviolet absorber (BONASORB UA-3901 manufactured by Orient Chemical Industries Co., Ltd.) having the structure of formula (1) is replaced with an ultraviolet absorber (Orient Chemical Industries, Ltd.), which is another indole derivative having the structure of formula (1). An optical pressure-sensitive adhesive composition was prepared in the same manner except that it was changed to BONASORB UA-3902), and a pressure-sensitive adhesive polarizing plate was produced.

[Example 4]
In Example 2, the ultraviolet absorber (BONASORB UA-3901 manufactured by Orient Chemical Co., Ltd.) having the structure of the formula (1) is replaced with the ultraviolet absorber (Orient Chemical Industries Co., Ltd.), which is another indole derivative having the structure of the formula (1). An optical pressure-sensitive adhesive composition was prepared in the same manner except that the product was changed to BONASORB UA-3911), and a pressure-sensitive adhesive polarizing plate was prepared.

[Example 5]
83 parts by weight of n-butyl acrylate, 1 part by weight of methyl acrylate, 1 part by weight of 2-hydroxyethyl acrylate, 3 parts by weight of acrylic acid and 6 parts by weight of N, N-dimethylacrylamide are dissolved in 185 parts by weight of ethyl acetate. Then, 0.05 part by mass of azobisisobutyronitrile was added and reacted at 70 ° C. for 5 hours to obtain an acrylic copolymer resin (weight average molecular weight: 11,150,000, Tg: −37 ° C.). . An optical pressure-sensitive adhesive composition was prepared in the same manner as in Example 2 except that the acrylic copolymer resin thus obtained was used, and a pressure-sensitive adhesive polarizing plate was produced.

[Example 6]
In Example 2, it is the same except that the addition amount of the ultraviolet absorber having the structure of the formula (1) (BONASORB UA-3901 manufactured by Orient Chemical Industry Co., Ltd.) is changed from 1.0 part by mass to 0.5 part by mass. Then, an optical pressure-sensitive adhesive composition was prepared to produce a pressure-sensitive adhesive polarizing plate.

[Example 7]
In Example 2, it is the same except that the addition amount of the ultraviolet absorbent (Orient Chemical Industries, Ltd. BONASORB UA-3901) having the structure of the formula (1) is changed from 1.0 part by mass to 3.0 parts by mass. Then, an optical pressure-sensitive adhesive composition was prepared to produce a pressure-sensitive adhesive polarizing plate.

[Comparative Example 1]
In Example 2, an optical pressure-sensitive adhesive composition was prepared in the same manner except that an ultraviolet absorber having a structure of the formula (1) (BONASORB UA-3901 manufactured by Orient Chemical Industry Co., Ltd.) was not added to the acrylic copolymer resin solution. The pressure-sensitive adhesive polarizing plate was prepared.

[Comparative Example 2]
In Example 2, instead of 0.1 parts by mass of the ultraviolet absorber having the structure of the formula (1) (BONASORB UA-3901 manufactured by Orient Chemical Industry Co., Ltd.), a benzotriazole-based ultraviolet absorber (Tinvin-109 manufactured by BASF) An optical pressure-sensitive adhesive composition was prepared in the same manner except that 1.0 part by mass was blended with respect to the acrylic copolymer resin solution to prepare a pressure-sensitive adhesive polarizing plate.

[Comparative Example 3]
In Example 2, instead of 0.1 part by mass of the ultraviolet absorber having the structure of the formula (1) (BONASORB UA-3901 manufactured by Orient Chemical Industry Co., Ltd.), a hydroxyphenyltriazine-based ultraviolet absorber (Tinvin 460 manufactured by BASF) An optical pressure-sensitive adhesive composition was prepared in the same manner except that 1.0 part by mass was blended with respect to the acrylic copolymer resin solution to prepare a pressure-sensitive adhesive polarizing plate.

[Durability test]
The adhesive polarizing plates obtained in Examples 1 to 7 and Comparative Examples 1 to 3 were cut into a rectangle having a size of 120 mm in the absorption axis (stretching axis) direction and 80 mm in the transmission axis (non-stretching axis) direction, and then peeled off. What peeled off the film and stuck on the glass using the pressure type roller was used as a sample for a durability test. The surface of the sample on the side of the polarizing plate was subjected to a test of irradiation for 750 hours in an environment of 85 ° C. and 50% relative humidity with a high-pressure mercury lamp light resistance tester (Ushio Electric Co., Ltd., ultra-high pressure mercury lamp 2000 W). About the sample before irradiation and the sample after irradiation, the amount of change of single-piece | unit transmittance | permeability and b * value of a polarizing plate single-piece | unit was confirmed using the spectrophotometer (Hitachi High-Tech Fielding U-4100). The single transmittance is a Y value measured based on a two-degree field of JIS Z 8722 and corrected for visibility. Moreover, the adhesiveness of glass and a polarizing plate was investigated visually. The results are shown in Table 1. The adhesion was evaluated as “◯” when no peeling or micro defects occurred in the initial state, and “X” when peeling or micro defects occurred compared to the initial state.

  As can be seen from the results in Table 1, the samples using the adhesive polarizing plates of Examples 1 to 7 have small changes in single transmittance and b * value before and after the durability test, and after the durability test. It was also confirmed that there was almost no deterioration such as discoloration of the polarizing plate, white turbidity, and physical destruction. Furthermore, the sample using the adhesive polarizing plate of Examples 1 to 7 also had good adhesion and transparency of the adhesive layer after the durability test. On the other hand, the samples using the adhesive polarizing plates of Comparative Examples 1 to 3 had increased single transmittance and b * value after the durability test, and white turbidity and yellowing were confirmed. In addition, in the samples using the adhesive type polarizing plates of Comparative Examples 1 to 3, abnormalities in appearance such as foaming and peeling were observed in the adhesive layer after the durability test, and the adhesiveness and transparency were lowered.

  Therefore, the optical pressure-sensitive adhesive composition according to the present invention is useful for bonding an optical film, has high durability, and provides good results. The pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to the present invention is less susceptible to appearance abnormalities such as foaming, peeling, and deterioration even when left for a long time in a high-temperature and high-humidity state and under light irradiation. And transparency can be maintained and deterioration of an optical film can be reduced significantly. Therefore, the pressure-sensitive adhesive optical film using the optical pressure-sensitive adhesive composition according to the present invention is used for liquid crystal display applications, and is particularly useful for vehicle applications, various industrial instruments, household appliance displays, and the like. The durability and reliability of these liquid crystal display devices over a long period of time can be improved.

Claims (9)

An acrylic (co) polymer resin obtained by polymerizing a monomer composition containing at least an acrylic acid alkyl ester;
Following formula (1):

(R ₁ and R ₂ are each independently a hydrogen atom, an amino group, an alkyl group, an alkyl ether group, an alkyl ester group having 1 to 6 carbon atoms, a cyano group, a benzothiazole group, or a phenyl group having a substituent. R ₃ represents a hydrogen atom, an amino group, a cyano group, or an alkylthiol group having 1 to 3 carbon atoms, and R ₄ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an allyl group.)
The optical adhesive composition containing the ultraviolet absorber represented by these. The ultraviolet absorber is represented by the following formula (2):

(R ₁ , R ₃ , and R ₄ are the same as those in formula (1).)
The optical adhesive composition of Claim 1 represented by these.   The acrylic acid alkyl ester is at least one selected from the group consisting of n-butyl (meth) acrylate, t-butyl (meth) acrylate, and methyl (meth) acrylate. An optical pressure-sensitive adhesive composition as described in 1.   The monomer composition is 0.5 to 7 parts by mass of a polymerizable monomer having a hydroxyl group and 0.5 to 29 parts by mass of a polymerizable monomer having an amide group with respect to 100 parts by mass of an acrylic acid alkyl ester. The optical pressure-sensitive adhesive composition according to claim 1, further comprising:   The optical pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the monomer composition further comprises a polymerizable monomer having 0.5 to 7 parts by mass of a carboxyl group with respect to 100 parts by mass of the acrylic acid alkyl ester. Agent composition.   The optical pressure-sensitive adhesive composition according to claim 1, wherein the acrylic (co) polymer resin has a weight average molecular weight of 500,000 to 2,000,000.   The adhesive layer obtained from the optical adhesive composition in any one of Claims 1-6.   A pressure-sensitive adhesive optical film comprising the pressure-sensitive adhesive layer according to claim 7 on one side or both sides of the optical film.   The pressure-sensitive adhesive optical film according to claim 8, wherein the optical film is a polarizing film or a retardation film.