JP2008250260A - Adhesive for polarizing plate and polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive for a polarizing plate which allows high-speed production of a polarizing plate having a structure in which a polarizer and a polarizing plate protective film are stuck together. <P>SOLUTION: The adhesive for a polarizing plate includes a urethane (meth)acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth)acrylate compound, and a polyol (meth)acrylate obtained form a polyol compound and a hydroxyl group-containing (meth)acrylate compound or a carboxyl group-containing (meth)acrylate compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a polarizing plate adhesive used for bonding a polarizer and a polarizing plate protective film when producing a polarizing plate having a configuration in which a polarizer and a polarizing plate protective film are bonded together, and The present invention relates to a polarizing plate that can be produced using this.

  Since liquid crystal display devices have features such as power saving, light weight, thinness, and the like, they have rapidly spread in recent years in place of conventional CRT displays. As a general liquid crystal display device, as shown in FIG. 2, a liquid crystal display device having an incident side polarizing plate 102 </ b> A, an outgoing side polarizing plate 102 </ b> B, and a liquid crystal cell 101 can be exemplified. The polarizing plates 102A and 102B are configured so as to selectively transmit only linearly polarized light having a vibration surface in a predetermined vibration direction, and are crossed so that the vibration directions are perpendicular to each other. They are arranged facing each other in a Nicol state. The liquid crystal cell 101 includes a large number of cells corresponding to the pixels, and is disposed between the polarizing plates 102A and 102B. Furthermore, the polarizing plates 102A and 102B have a configuration in which polarizing plate protective films 122A and 122B are bonded to both surfaces of the polarizers 112A and 112B.

  As such a liquid crystal display device, those using various driving methods are known depending on the arrangement form of the liquid crystal material used in the liquid crystal cell. The main ones of liquid crystal display devices that are popular today are classified into TN, STN, MVA, IPS, OCB, and the like. Among them, those having the MVA and IPS driving methods have come into widespread use.

  As the polarizing plate constituting the liquid crystal display device, conventionally, a film made of polyvinyl alcohol as the polarizer is impregnated with iodine and uniaxially stretched to form a complex of polyvinyl alcohol and iodine. In general, the polarizing plate protective film uses a film made of a cellulose derivative typified by triacetylcellulose. Moreover, as a manufacturing method of the polarizing plate which has such a structure, the method of laminating the said polarizing plate protective film on both surfaces of the said polarizer through the polyvinyl alcohol aqueous solution as an adhesive agent is common. About such a polarizing plate and its manufacturing method, it is disclosed by patent documents 1-8, for example.

By the way, with the recent increase in demand for liquid crystal display devices, the demand for the polarizing plate is also increasing, and it is required to produce a high-quality polarizing plate with high productivity. However, in the conventional polarizing plate having the above-described configuration, since an aqueous polyvinyl alcohol solution is used as the adhesive, it takes time to dry the adhesive in the polarizing plate manufacturing process, and this becomes a rate-limiting factor. Therefore, there is a problem that it is difficult to improve productivity. In this regard, in order to achieve both improvement in productivity and drying of the adhesive, a method of lengthening the drying process of the polarizing plate manufacturing apparatus has also been studied, but such a method greatly increases the equipment cost. There was a problem.
Moreover, in order to adhere the polarizing plate protective film made of triacetyl cellulose to a polarizer made of polyvinyl alcohol, it is necessary to saponify the surface of the polarizing plate protective film to improve the adhesion to polyvinyl alcohol. It is said that. For this reason, when using a polarizing plate protective film made of triacetylcellulose, it is necessary to perform a saponification treatment step before bonding with a polarizer, and the problem that the manufacturing process of the polarizing plate becomes complicated is also pointed out. It was.

  In order to solve such problems, studies on alternatives to polyvinyl alcohol aqueous solutions as the adhesives have been actively conducted. For example, Patent Document 9 discloses a polarizing plate in which a polarizer and a polarizing plate protective film are bonded with an adhesive layer made of an active energy ray-curable compound. Patent Documents 10 and 11 disclose a polarizing plate in which a polarizer and a polarizing plate protective film are bonded by an adhesive made of an isocyanate compound or the like. However, the polarizing plate bonded using such an adhesive has a problem that adhesion between the polarizer and the polarizing plate protective film is poor.

  For these reasons, the demand for the polarizing plate used in the liquid crystal display device is increasing, but it has excellent adhesion between the polarizer and the polarizing plate protective film, and at a high production rate. The problem of not being able to manufacture has become apparent.

Japanese Patent No. 3148513 Japanese Patent No. 3427130 Japanese Patent No. 3525543 Japanese Patent No. 3629286 JP-A-1-32203 Japanese Patent Laid-Open No. 3-64703 Japanese Patent Laid-Open No. 5-681 JP-A-8-271733 JP 2004-70290 A Japanese Patent No. 3724792 JP 2003-177247 A

  The present invention has been made in view of such problems, and an adhesive for polarizing plate capable of producing a polarizing plate having a configuration in which a polarizer and a polarizing plate protective film are bonded together at high speed. The main purpose is to provide.

  In order to solve the above problems, the present invention provides a urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meta And a polyol (meth) acrylate obtained from an acrylate compound.

According to the polarizing plate adhesive of the present invention, by including the urethane (meth) acrylate and the polyol (meth) acrylate, the polarizer and the polarizing plate protective film can be bonded without using a solvent. . For this reason, by using the adhesive for polarizing plates of the present invention, it is not necessary to perform a step of drying the solvent when bonding the polarizer and the polarizing plate protective film in the step of manufacturing the polarizing plate. .
From such a thing, according to this invention, the adhesive agent for polarizing plates which can manufacture the polarizing plate which has the structure by which the polarizer and the polarizing plate protective film were bonded together at high speed can be obtained.

  Moreover, according to the adhesive agent for polarizing plates of this invention, the viscosity as the whole adhesive agent for polarizing plates can be made low by including the said urethane (meth) acrylate and the said polyol (meth) acrylate. For this reason, since the adhesive agent for polarizing plates of this invention becomes the thing excellent in thin film coating property, it also has the advantage that a thin adhesive layer can be formed.

  In the present invention, the urethane (meth) acrylate preferably has an isocyanate group (NCO group). When the urethane (meth) acrylate has an isocyanate group (NCO group), for example, the polarizing plate adhesive of the present invention is used to bond a polarizer made of polyvinyl alcohol and a polarizing plate protective film. In addition, the isocyanate group (NCO group) can react with a hydroxyl group included in the polarizer to form a urethane bond, thereby significantly improving the adhesiveness between the polarizer and the polarizing plate protective film. It is possible. Moreover, since it reacts with the polar group produced | generated when surface treatments, such as a polarizer and / or polarizing plate protective film, such as corona treatment, can form a urethane bond similarly, This is because it is possible to further improve the adhesiveness with the polarizing plate protective film.

  Moreover, it is preferable that the adhesive agent for polarizing plates of this invention contains the base-material penetrating monomer which has permeability with respect to a polarizing plate protective film. It is because the adhesive for polarizing plates of this invention can be made excellent in adhesiveness with a polarizing plate protective film by containing such a base-penetrating monomer. Moreover, it is because the viscosity of the adhesive agent for polarizing plates of the present invention can be lowered by containing such a substrate-penetrating monomer, and the coating property of the thin film can be further improved.

  Moreover, the silane coupling agent may be contained in the adhesive agent for polarizing plates of this invention. By including a silane coupling agent, for example, when a polarizing plate using a polarizer made of polyvinyl alcohol is produced using the polarizing plate adhesive of the present invention, the adhesion with the polarizer is improved. This is because it can be improved. Moreover, since the silane coupling agent also contributes to lowering the viscosity of the polarizing plate adhesive of the present invention at the same time, the use of the silane coupling agent makes the polarizing plate adhesive of the present invention more thin film coatable. It is because it can be made excellent.

  In the present invention, the polyol compound is preferably a polyether polyol. This is because by using polyether polyol as the polyol compound, it is easy to impart flexibility to the adhesive layer produced using the adhesive for polarizing plates of the present invention. In addition, for example, when a polarizing plate using a polarizer made of polyvinyl alcohol is produced using the polarizing plate adhesive of the present invention, the adhesiveness with the polarizer can be improved. .

  Furthermore, in the present invention, the polyisocyanate compound is preferably an alicyclic polyisocyanate compound. It is because the adhesive agent for polarizing plates of this invention can be made excellent in adhesiveness with a polarizing plate protective film because the said polyisocyanate compound is an alicyclic polyisocyanate compound.

  The present invention comprises a polarizer comprising polyvinyl alcohol, an adhesive layer formed on both sides of the polarizer, and a polarizing plate protective film formed on both sides of the polarizer and formed on the adhesive layer. A urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) There is provided a polarizing plate comprising a cured product of a polyol (meth) acrylate obtained from an acrylate compound, and having a urethane bond formed at least between the adhesive layer and the polarizer.

According to the present invention, the adhesive layer includes the urethane (meth) acrylate and a cured product of the polyol (meth) acrylate, and at least a urethane bond is formed between the adhesive layer and the polarizer. Therefore, a polarizing plate excellent in adhesiveness between the polarizer and the polarizing plate protective film can be obtained.
Further, the urethane (meth) acrylate and the cured product of the polyol (meth) acrylate contained in the adhesive layer are such that the adhesive layer emits light to the urethane (meth) acrylate and the polyol (meth) acrylate. Since it can produce | generate by irradiating, in the process of manufacturing the polarizing plate of this invention, it becomes unnecessary to use a solvent in order to form the said contact bonding layer. For this reason, it becomes unnecessary to install the process of drying the said contact bonding layer in the process of manufacturing the polarizing plate of this invention.
Furthermore, when the adhesive layer contains the urethane (meth) acrylate and a cured product of the polyol (meth) acrylate, the adhesive layer can be thinned. For this reason, according to this invention, the polarizing plate excellent in the cutting process characteristic can be obtained.

  In this invention, it is preferable that the hardened | cured material of the base material permeable monomer which has the permeability | transmittance with respect to the said polarizing plate protective film contains in the said contact bonding layer. It is because the adhesiveness of the said adhesive layer and the said polarizing plate protective film can be improved by containing the hardened | cured material of such a base material permeable monomer in the said adhesive agent.

  Moreover, in this invention, it is preferable that the said polarizing plate protective film consists of a cellulose derivative. According to the present invention, since a polarizing plate protective film made of a cellulose derivative can be used without being subjected to saponification treatment, a higher productivity improvement effect can be obtained as compared with the case of using a polarizing plate protective film made of another material. Because it can be obtained.

  The adhesive agent for polarizing plates of this invention produces the effect that the polarizing plate which has the structure by which the polarizer and the polarizing plate protective film were bonded together can be manufactured with high productivity.

  The present invention relates to a polarizing plate adhesive and a polarizing plate. Hereinafter, the polarizing plate adhesive and the polarizing plate of the present invention will be described in order.

A. First, the polarizing plate adhesive of the present invention will be described. The polarizing plate adhesive of the present invention comprises a urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth). And a polyol (meth) acrylate obtained from an acrylate compound.

By containing the urethane (meth) acrylate and the polyol (meth) acrylate, the polarizing plate adhesive of the present invention can bond the polarizer and the polarizing plate protective film without using a solvent. . For this reason, by using the adhesive for polarizing plates of the present invention, it is not necessary to perform a step of drying the solvent when bonding the polarizer and the polarizing plate protective film in the step of manufacturing the polarizing plate. . That is, by using the polarizing plate adhesive of the present invention, conventionally, when manufacturing a polarizing plate having a configuration in which a polarizer and a polarizing plate protective film are bonded together, the adhesive has become a rate-limiting factor. It is no longer necessary to carry out a drying step of a solvent such as water in which the water is dissolved. For this reason, the polarizing plate which has the structure as mentioned above can be manufactured at high speed by using the adhesive for polarizing plates of the present invention.
Therefore, according to the present invention, it is possible to obtain a polarizing plate adhesive capable of producing a polarizing plate having a configuration in which a polarizer and a polarizing plate protective film are bonded together with high productivity. .

  Moreover, the adhesive agent for polarizing plates of this invention shall make the viscosity as the whole adhesive agent for polarizing plates low by including the said urethane (meth) acrylate and the said polyol (meth) acrylate. Can do. For this reason, since the adhesive for polarizing plates of this invention becomes the thing excellent in thin film coating property, a thin adhesive layer can be formed and, as a result, a polarizing plate with favorable cutting workability is produced. be able to.

In the polarizing plate produced using the polarizing plate adhesive of the present invention, the polarizer and the polarizing plate protective film are bonded to each other by a cured product of the urethane (meth) acrylate and the polyol (meth) acrylate. Will be. For this reason, when preparing a polarizing plate using the polarizing plate adhesive of the present invention, even when a polarizing plate protective film composed of a cellulose derivative typified by triacetyl cellulose is used, saponification is performed as in the past. It is not necessary to perform processing. Conventionally, since a polyvinyl alcohol (PVA) aqueous solution was used as an adhesive, it was necessary to form a hydroxyl group contributing to hydrogen bond formation on the surface of the polarizing plate protective film. This is because the adhesive for adhesive does not develop adhesive force by hydrogen bonding.
Therefore, in the process of producing a polarizing plate having a configuration in which a polarizer made of polyvinyl alcohol (PVA) and a polarizing plate protective film are bonded together by using the polarizing plate adhesive of the present invention, saponification is performed. Since a processing process can be excluded, a polarizing plate manufacturing process can be simplified.

In addition, the ability to eliminate the saponification process as described above has the following advantages. That is, conventionally, in order to obtain a polarizing plate having an additional function, a material having a desired function is contained in the polarizing plate protective film, or a functional layer having a desired function is laminated. . However, conventionally, when a polarizing plate protective film made of a cellulose derivative is used, the above saponification treatment step is required, and thus a material used for imparting a desired function to the polarizing plate protective film made of the cellulose derivative. There is a restriction that only those having alkali resistance can be used.
In this regard, the use of the adhesive for polarizing plate of the present invention eliminates the need for the saponification treatment step. There is an advantage that an appropriate material can be selected and used from a wide range.

  Further, in the polarizing plate produced using the polarizing plate adhesive of the present invention, the polarizer and the polarizing plate protective film are bonded to each other by the cured product of the urethane (meth) acrylate and the polyol (meth) acrylate. Will be. For this reason, the polarizing plate excellent in the adhesiveness of the polarizer which consists of polyvinyl alcohol, and a polarizing plate protective film can be produced by using the adhesive agent for polarizing plates of this invention.

Furthermore, the polarizing plate adhesive of the present invention has the following advantages. That is, in a conventional polarizing plate in which a polarizer made of polyvinyl alcohol and a polarizing plate protective film are bonded together, polyvinyl alcohol has been used as an adhesive for bonding the polarizer and the polarizing plate protective film. However, since polyvinyl alcohol exhibits water solubility, a polarizing plate using such an adhesive has a problem of poor moisture resistance.
In this regard, the polarizing plate produced using the polarizing plate adhesive of the present invention is a polarizer and a polarizing plate protective film made of the urethane (meth) acrylate and the cured product of the polyol (meth) acrylate. It will be glued. Here, since the urethane (meth) acrylate and the cured product of the polyol (meth) acrylate are excellent in water resistance, by using the polarizing plate adhesive of the present invention, durability under a high humidity atmosphere is achieved. A polarizing plate having excellent properties can be produced.

  In addition, "(meth) acrylate" in the present invention is meant to include acrylate and methacrylate.

The adhesive for polarizing plates of this invention contains the said urethane (meth) acrylate and the said polyol (meth) acrylate at least, and may contain another structure as needed.
Hereafter, each structure used for such an adhesive for polarizing plates of this invention is demonstrated in order.

1. Urethane (meth) acrylate First, the urethane (meth) acrylate used in the present invention will be described. The urethane (meth) acrylate used in the present invention is obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound.

  Here, “obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound” means that it can be produced by a reaction between the polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound. To do. Therefore, the urethane (meth) acrylate used in the present invention refers to one having a structure that can be obtained as a reaction product by reacting a polyisocyanate compound with a hydroxyl group-containing (meth) acrylate compound. Become.

  Thus, since the urethane (meth) acrylate used in the present invention is obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound, its structure is usually an isocyanate of the polyisocyanate compound. When the group reacts with the hydroxyl group of the hydroxyl group-containing (meth) acrylate compound, these compounds are bonded. Therefore, the urethane (meth) acrylate used in the present invention has constituent units of the polyisocyanate compound and the hydroxyl group-containing (meth) acrylate compound.

  Hereinafter, the polyisocyanate compound and the hydroxyl group-containing (meth) acrylate compound capable of obtaining the urethane (meth) acrylate used in the present invention will be described in order, and then urethane (meth) acrylate is obtained from these compounds. The method will be described.

(1) Polyisocyanate Compound First, the polyisocyanate compound used in the present invention will be described. The polyisocyanate compound used in the present invention is not particularly limited as long as it has a plurality of isocyanate groups in the molecule. Examples of such polyisocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexylisocyanate), 2,2,4-trimethylhe Samethylene diisocyanate, 1,4-hexamethylene diisocyanate, bis (2-isocyanatoethyl) fumarate, bis (4-isocyanatocyclohexyl) methane, 6-isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, Examples thereof include hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, and norbornane diisocyanate.

  In the present invention, any of these polyisocyanate compounds can be suitably used, and among them, it is preferable to use an alicyclic polyisocyanate compound. By using an alicyclic polyisocyanate compound as the polyisocyanate compound, the urethane (meth) acrylate used in the present invention is used for producing a polarizing plate using the polarizing plate adhesive of the present invention. It is because it can make it excellent in adhesiveness with a protective film.

  Examples of the polyisocyanate compound suitably used in the present invention include Sumitomo Chemical's Sumidur L75, Sumidur IL, Death Module HL and MDI base as TDI base, Sumitomo Chemical Sumidur 44S, Sumidur 44V10, Sumidur 44N20, Sumidur 44V40, Sumidur 44V70, Sumitomo Chemical's Death Module Z4470, etc. can be cited as IPDI bases. By using such an alicyclic polyisocyanate compound, the adhesiveness of the adhesive for polarizing plates of the present invention to the polarizing plate protective film can be further improved.

  In addition, the polyisocyanate compound used for this invention may be one type, or may be two or more types.

(2) Hydroxyl group-containing (meth) acrylate compound Next, the hydroxyl group-containing (meth) acrylate compound used in the present invention will be described. The hydroxyl group-containing (meth) acrylate compound used in the present invention is not particularly limited as long as it has a hydroxyl group and an acrylate group. Examples of such a hydroxyl group-containing (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3-phenyloxy. Propyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 2-hydroxyalkyl (meth) acryloyl phosphate, 4-hydroxycyclohexyl (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, neo Pentyl glycol mono (meth) acrylate, (poly) ethylene glycol monoacrylate, (poly) propylene glycol monoacrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol It can be mentioned pointer (meth) acrylate.

  Moreover, as a hydroxyl-containing (meth) acrylate compound used for this invention, the compound represented by following Structural formula (1) or (2) can also be mentioned, for example.

Here, in the structural formula (1) or (2), R ¹ represents a hydrogen atom or a methyl group, and m represents a number of 1 to 15.

  Furthermore, the hydroxyl group-containing (meth) acrylate compound used in the present invention is obtained, for example, by an addition reaction between a glycidyl group-containing compound such as alkyl glycidyl ether, allyl glycidyl ether, or glycidyl (meth) acrylate and (meth) acrylic acid. The compound which can be mentioned can also be mentioned.

  In the present invention, any of these hydroxyl group-containing (meth) acrylate compounds can be suitably used. Among them, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- It is preferable to use hydroxybutyl (meth) acrylate.

  The hydroxyl group-containing (meth) acrylate compound used in the present invention may be one type or two or more types.

(3) Urethane (meth) acrylate As described above, the urethane (meth) acrylate used in the present invention is obtained from the urethane (meth) acrylate and the hydroxyl group-containing (meth) acrylate. However, the urethane (meth) acrylate used in the present invention preferably has an isocyanate group (NCO group). By using the urethane group (meth) acrylate having an isocyanate group, for example, when the polarizing plate adhesive of the present invention is used to bond a polarizer made of polyvinyl alcohol and a polarizing plate protective film, The isocyanate group (NCO group) can react with a hydroxyl group included in the polarizer to form a urethane bond, and can significantly improve the adhesion between the polarizer and the polarizing plate protective film. Because there is. In addition, the polarizer and / or the polarizing plate protective film can react with polar groups generated when surface treatment such as corona treatment is performed to form a urethane bond in the same manner. This is because the adhesiveness with the plate protective film can be remarkably improved.

  Here, the urethane (meth) acrylate used in the present invention has “isocyanate group (NCO group)” simply means that the urethane (meth) acrylate used in the present invention has an isocyanate group (NCO group). ) It does not mean that it is composed only of acrylate, but urethane (meth) acrylate having an isocyanate group (NCO group) and urethane (meth) acrylate having no isocyanate group (NCO group) are mixed Is also included.

  When using what has an isocyanate group (NCO group) as said urethane (meth) acrylate, as content of the said isocyanate group (NCO group), the isocyanate group (NCO) contained in the whole adhesive agent for polarizing plates of this invention is used. Group) is not particularly limited as long as it can be within a desired range. Use of the adhesive for polarizing plate of the present invention and the urethane contained in the adhesive for polarizing plate of the present invention It can be suitably adjusted according to the amount of (meth) acrylate. Especially in this invention, it is preferable that the quantity of the isocyanate group (NCO group) in the said urethane (meth) acrylate exists in the range of 0.1 mol%-30 mol%, Especially 0.5 mol%-20 It is preferably in the range of mol%, and more preferably in the range of 1 mol% to 10 mol%. If the content of the isocyanate group is less than the above range, the urethane (meth) acrylate may not be able to express the adhesive improvement effect due to containing the isocyanate group (NCO group) to a desired level. is there. On the other hand, if the amount is more than the above range, in the polarizing plate produced using the polarizing plate adhesive of the present invention, the urethane bond formed between the polarizer and the adhesive layer becomes too much, and the time of the adhesive is increased. This is because the change is likely to occur and the polarization characteristics of the polarizer may be impaired.

  Here, the content of the isocyanate group (NCO group) in the urethane (meth) acrylate is disclosed in, for example, Japanese Patent Laid-Open No. 5-155777 based on JIS K1556 “Measurement of Isocyanate in Urethane Resin”. It can be measured by a neutralization titration method. More specifically, 0.1 g of the reaction solution containing the prepolymer was dissolved in 40 ml of 0.01 N di-n-butylamine dimethylformamide solution, and then dissolved in 0.01 N hydrochloric acid in methanol. It can be measured by performing neutralization titration using bromophenol blue as an indicator.

  As described above, the urethane (meth) acrylate used in the present invention can be obtained as a reaction product by reacting a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound. Here, as a method of obtaining the urethane (meth) acrylate used in the present invention by reacting the polyisocyanate compound and the hydroxyl group-containing (meth) acrylate compound, a urethane (meth) acrylate having a desired structure is obtained. Any method can be used according to the type of the polyisocyanate compound and the hydroxyl group-containing (meth) acrylate compound. Examples of such a method include a urethanization reaction between a polyisocyanate component and a hydroxyl group-containing (meth) acrylate compound.

  Moreover, when using what has an isocyanate group (NCO group) as urethane (meth) acrylate used for this invention, as a method of obtaining such urethane (meth) acrylate, for example with respect to the NCO group of polyisocyanate And urethanization reaction in which a small number of moles of hydroxyl group-containing (meth) acrylate is added.

  Furthermore, as a combination of the polyisocyanate compound and the hydroxyl group-containing (meth) acrylate compound constituting the urethane (meth) acrylate used in the present invention, urethane (meth) acrylate having desired adhesiveness can be obtained. If it is a combination, it will not specifically limit. As a suitable combination of the polyisocyanate compound used to obtain the urethane (meth) acrylate used in the present invention and the hydroxyl group-containing (meth) acrylate compound, for example, a combination of IPDI and 2-hydroxyethyl acrylate, IPDI and A combination of (poly) ethylene glycol monoacrylate, a combination of IPDI and (poly) propylene glycol monoacrylate, a combination of IPDI and pentaerythritol tetraacrylate, and the like.

  In addition, the urethane (meth) acrylate used in the present invention may be one type or two or more types.

2. Polyol (meth) acrylate Next, the polyol (meth) acrylate used in the present invention will be described. The polyol (meth) acrylate used in the present invention is obtained from a polyol compound and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound.

  Here, “obtained from a polyol compound and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound” means a reaction between a polyol compound and a hydroxyl group-containing (meth) acrylate compound, or a polyol It means that it can be produced by a reaction between a compound and a carboxyl group-containing (meth) acrylate compound. Therefore, the polyol (meth) acrylate used in the present invention can be obtained as a reaction product by reacting a polyol compound with a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound. It will refer to one having a structure.

  Thus, since the polyol (meth) acrylate used for this invention is obtained from a polyol compound and a hydroxyl-containing (meth) acrylate compound, the hydroxyl group which the said polyol compound has normally has the said hydroxyl-containing ( By reacting with the hydroxyl group of the (meth) acrylate compound, the compound has a structure in which these compounds are bonded. Therefore, the polyol (meth) acrylate used for this invention has a structural unit of the reaction product of the said polyol compound and the said hydroxyl-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound.

  Hereinafter, the polyol compound, the hydroxyl group-containing (meth) acrylate compound, and the carboxyl group-containing (meth) acrylate compound that can obtain the polyol (meth) acrylate used in the present invention will be described in order, and then these compounds will be described. A method for obtaining polyol (meth) acrylate from the above will be described.

(1) Polyol compound Next, the polyol compound used for this invention is demonstrated. The polyol compound used in the present invention is not particularly limited as long as it has a plurality of hydroxyl groups. Examples of such polyol compounds include aromatic polyether polyols, aliphatic polyether polyols, alicyclic polyether polyols, polyester polyols, polycarbonate polyols, and polycaprolactone polyols.
Hereinafter, specific examples of these polyol compounds will be described in order.

  Examples of the aromatic polyether polyol include bisphenol A ethylene oxide addition diol, bisphenol A propylene oxide addition diol, bisphenol A butylene oxide addition diol, bisphenol F ethylene oxide addition diol, and bisphenol F propylene oxide addition diol. And propylene oxide addition diol of bisphenol F, alkylene oxide addition diol of hydroquinone, alkylene oxide addition diol of naphthoquinone, and the like.

  Examples of the aliphatic polyether polyol include at least one selected from ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, substituted tetrahydrofuran, oxetane, substituted oxetane, tetrahydropyran, and oxeban. And the like obtained by ring-opening (co) polymerizing these compounds. Specific examples thereof include, for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, polyisobutylene glycol, copolymer polyol of propylene oxide and tetrahydrofuran, and copolymer of ethylene oxide and tetrahydrofuran. Examples thereof include a polyol, a copolymer polyol of ethylene oxide and propylene oxide, a copolymer polyol of tetrahydrofuran and 3-methyltetrahydrofuran, a copolymer polyol of ethylene oxide and 1,2-butylene oxide, and the like.

  Examples of the alicyclic polyether polyol include hydrogenated bisphenol A ethylene oxide addition diol, hydrogenated bisphenol A propylene oxide addition diol, hydrogenated bisphenol A butylene oxide addition diol, and hydrogenated bisphenol F ethylene oxide addition. Examples include diol, propylene oxide addition diol of hydrogenated bisphenol F, butylene oxide addition diol of hydrogenated bisphenol F, dimethylol compound of dicyclopentadiene, tricyclodecane dimethanol, and the like.

  Examples of the polyester polyol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3- Polyhydric alcohols such as methyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol and phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, Examples thereof include polyester polyols obtained by reacting with polybasic acids such as sebacic acid.

  Examples of the polycarbonate polyol include 1,6-hexane polycarbonate.

  Examples of the polycaprolactone polyol include ε-caprolactone, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, Examples thereof include polycaprolactone diols obtained by reacting with divalent diols such as neopentyl glycol, 1,4-cyclohexanedimethanol and 1,4-butanediol.

  Other polyol compounds that can be used in the present invention include, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4- Examples include cyclohexanedimethanol, polyβ-methyl-δ-valerolactone, hydroxy-terminated polybutadiene, hydroxy-terminated hydrogenated polybutadiene, castor oil-modified polyol, polydimethylsiloxane-terminated diol compound, and polydimethylsiloxane carbitol-modified polyol.

In the present invention, any of these polyol compounds can be suitably used, but among them, polyether polyol is preferably used. The reason is as follows.
1stly, although the adhesive agent for polarizing plates of this invention is used in order to produce a polarizing plate by bonding a polarizer and a polarizing plate protective film, the adhesive agent for polarizing plates of this invention is used. The adhesive layer produced in this manner contains a cured product of the above-described urethane (meth) acrylate and polyol (meth) acrylate. Here, when the polyether polyol is used as the polyol compound, the cured product can be softened, so that it is possible to form a flexible adhesive layer using the polarizing plate adhesive of the present invention. Become. Here, when the polarizing plate is produced industrially, it is usually a product in a form in which a long one is wound in a roll shape, but by making the adhesive layer flexible, When the polarizing plate is wound into a roll shape, there is a remarkable effect that the surface shape can be prevented from being damaged by a knick or the like.
Secondly, the polyether polyol has an ether bond site that contributes to hydrogen bonding in the molecule, and therefore has excellent adhesion to polyvinyl alcohol. For this reason, as a result of using a polyether polyol as the polyol compound, the polyol (meth) acrylate used in the present invention can be made excellent in adhesiveness with a polarizer made of polyvinyl alcohol. It is because the adhesiveness with respect to the polarizer which consists of polyvinyl alcohol of the adhesive for water can be improved.
Third, the polyether polyol has a low glass transition temperature and has a property of spreading and spreading on the surface of the polarizing plate protective film, and the property does not change even after curing. This is because stable adhesiveness is exhibited even if changed.

  Examples of the polyether polyol preferably used in the present invention include polyethylene glycol, polypropylene glycol, and derivatives thereof.

  In addition, the polyol compound used for this invention may be one type, or may be two or more types.

  The polyol compound used in the present invention preferably has a number average molecular weight in the range of 500 to 12000, more preferably in the range of 1500 to 9000, and particularly preferably in the range of 3500 to 9000. preferable. This is because, when the number average molecular weight is smaller than the above range, in the polarizing plate produced using the polarizing plate adhesive of the present invention, the adhesion between the polarizer and the polarizing protective film may be lowered. . Moreover, when larger than the said range, it is because the viscosity of the adhesive agent for polarizing plates of this invention will become high too much, and coating suitability may be impaired.

(2) Hydroxyl group-containing (meth) acrylate compound The hydroxyl group-containing (meth) acrylate compound used in the present invention is not particularly limited as long as it has a hydroxyl group and an acrylate group. As such a hydroxyl group-containing (meth) acrylate compound, the same compounds as those described in the above section “1. Urethane (meth) acrylate” can be used, and thus description thereof is omitted here.

(3) Carboxyl group-containing (meth) acrylate compound The carboxyl group-containing (meth) acrylate compound used in the present invention is not particularly limited as long as it has a carboxyl group and an acrylate group. Examples of the carboxyl group-containing (meth) acrylate compound used in the present invention include acrylic acid, methacrylic acid, carboxyethyl acrylate and carboxypentyl acrylate, itaconic acid and maleic acid, fumaric acid and crotonic acid, and an acid anhydride group. Examples thereof include maleic anhydride and itaconic anhydride. In the present invention, any of these carboxyl group-containing (meth) acrylate compounds can be suitably used, and among them, acrylic acid and methacrylic acid are more preferably used.

(4) Polyol (meth) acrylate As described above, the polyol (meth) acrylate used in the present invention reacts a polyol compound with a carboxyl group-containing (meth) acrylate compound or a hydroxyl group-containing (meth) acrylate compound, It can be obtained as the reaction product. Here, the method of obtaining the polyol (meth) acrylate used in the present invention by reacting the above polyol compound with the carboxyl group-containing (meth) acrylate compound or the hydroxyl group-containing (meth) acrylate compound has a desired structure. The method is not particularly limited as long as it is a method capable of obtaining a polyol (meth) acrylate, and is arbitrary depending on the type of the polyol compound and the hydroxyl group-containing (meth) acrylate compound or the carboxyl group-containing (meth) acrylate compound. The method can be used. Examples of such a method include esterification or transesterification of a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound with respect to the hydroxyl group of the polyol compound.

  Moreover, as a combination of the above-mentioned polyol compound constituting the polyol (meth) acrylate used in the present invention and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound, a polyol having a desired adhesiveness ( It is not particularly limited as long as it is a combination capable of obtaining a (meth) acrylate. As a suitable combination of the polyol compound used for obtaining the polyol (meth) acrylate used in the present invention and the hydroxyl group-containing (meth) acrylate compound or the carboxyl group-containing (meth) acrylate compound, for example, polypropylene glycol and 2-hydroxy Examples include a combination of ethyl acrylate, a combination of polyethylene glycol and 2-hydroxyethyl acrylate, a combination of polypropylene glycol and acrylic acid, or a combination of polyethylene glycol and acrylic acid.

  The polyol (meth) acrylate used in the present invention preferably has a number average molecular weight in the range of 100 to 100,000, more preferably in the range of 200 to 50,000, and more preferably 300 to 30. Within the range of 1,000. If the number average molecular weight is smaller than the above range, in the polarizing plate produced using the polarizing plate adhesive of the present invention, the adhesion between the polarizer and the polarizing plate protective film may be lowered. It is. Moreover, when larger than the said range, it is because the viscosity of the adhesive agent for polarizing plates of this invention will become high too much, and coating suitability may be impaired.

  In addition, the polyol (meth) acrylate used for this invention may be one type, and may be two or more types.

3. Other compounds The adhesive for polarizing plates of the present invention contains at least the urethane (meth) acrylate and the polyol (meth) acrylate, but may contain other compounds as necessary. Good. As said other compound used for this invention, if a desired function can be provided to the adhesive agent for polarizing plates of this invention, it will not specifically limit, It selects suitably according to the specific use. Can be used. Among them, examples of the other compound that can be suitably used in the present invention include a base-penetrating monomer, a photopolymerization initiator, and a silane coupling agent.
Here, the adhesive agent for polarizing plates of this invention can be made excellent in adhesiveness with a polarizing plate protective film by containing the said base-penetrating monomer. Moreover, by containing a base-penetrating monomer, the viscosity of the adhesive for polarizing plates of the present invention can be reduced, and the thin film coatability can be improved.
On the other hand, by including the silane coupling agent, for example, when a polarizing plate using a polarizer made of polyvinyl alcohol is produced using the polarizing plate adhesive of the present invention, Adhesiveness can be improved. Moreover, since the silane coupling agent also contributes to lowering the viscosity of the polarizing plate adhesive of the present invention at the same time, the use of the silane coupling agent makes the polarizing plate adhesive of the present invention more thin film coatable. It can be made excellent.
Hereinafter, these other compounds will be described in order.

(1) Base material permeable monomer First, the said base material permeable monomer is demonstrated. The base material permeable monomer used in the present invention is permeable to a polarizing plate protective film bonded to a polarizer when a polarizing plate is prepared using the polarizing plate adhesive of the present invention. is there.

  Here, “having permeability to the polarizing plate protective film” means that at least a part of the monomer penetrates into the base material. The substrate-permeable monomer used in the present invention has the above-mentioned “permeability to the polarizing plate protective film” when the polarizing plate protective film is immersed in the substrate-permeable monomer. It can be evaluated by confirming that at least a part of the film swells or dissolves.

The substrate permeable monomer used in the present invention is not particularly limited as long as it has permeability to the polarizing plate protective film. Among them, the substrate-permeable monomer used in the present invention is preferably one that is compatible with at least one of the urethane (meth) acrylate and the polyol (meth) acrylate, and particularly the urethane (meth) acrylate and It is preferable that it is compatible with the polyol (meth) acrylate. By using such a substrate-permeable monomer, the viscosity of the polarizing plate adhesive of the present invention can be adjusted to a predetermined range by changing the content of the substrate-permeable monomer. Because.
Here, the base-penetrating monomer used in the present invention has the above-mentioned “compatibility” means having an affinity for each other, specifically, when the adhesive layer is formed. Further, it means that one side does not aggregate and precipitate due to phase separation or the like, and the coating film does not whiten, and no increase in haze is observed in the visible light region.

  In the present invention, it is preferable to use a compound having an acrylate group as the substrate-penetrating monomer. The reason is as follows. That is, the base material penetrating monomer used in the present invention has a function of penetrating the surface of a polarizing plate protective film used when a polarizing plate is produced using the polarizing plate adhesive of the present invention. As described above, the polarizing plate adhesive of the present invention includes urethane (meth) acrylate and polyol (meth) acrylate each having an acrylate group. Therefore, by using a compound having an acrylate group as the base material permeable monomer used in the present invention, the base material permeable monomer acts by polymerizing with the urethane (meth) acrylate or the polyol (meth) acrylate. As a result, it becomes possible to produce a polarizing plate having better adhesion between the polarizer and the polarizing plate protective film by using the polarizing plate adhesive of the present invention.

  The base-penetrating monomer having an acrylate group may have a single acrylate group or may have a plurality of acrylate groups.

  Examples of the base-penetrating monomer having an acrylate group used in the present invention include a nonpolar acrylate having a small polarity and a polar acrylate having a large polarity.

  Examples of the nonpolar acrylate include monoacrylates such as styrene, isobornyl acrylate, and cyclohexyl acrylate; 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethyloltricyclodecane diacrylate, 2- Examples include diacrylates such as methyl-1,8-octanediol diacrylate, 1,10-decanediol diacrylate, and tricyclodecane dimethanol diacrylate.

  Examples of the polar acrylate include monoacrylates such as polyethylene glycol monoacrylate and polypropylene glycol monoacrylate; morpholine acrylate, 2-ethyl-2-butylpropanepropanediol diacrylate, polyethylene glycol diacrylate, and polypropylene glycol diacrylate. And polyacrylates such as pentaerythritol triacrylate, trimethylolpropane acrylic acid benzoate, and trimethylolpropane triacrylate.

  As the substrate-penetrating monomer used in the present invention, any of the nonpolar acrylate and the polar acrylate can be suitably used. For example, when producing a polarizing plate using the adhesive for polarizing plates of this invention, when using the polarizing plate protective film which consists of a cellulose derivative, the said nonpolar acrylate and the said polar acrylate are used suitably. it can. Examples of substrate penetrating monomers that are particularly preferably used in such cases include 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, isobornyl acrylate, morpholine acrylate, and pentaerythritol triacrylate. Etc. Moreover, when producing a polarizing plate using the adhesive agent for polarizing plates of this invention, when using the polarizing plate protective film which consists of cycloolefin type resin, the said polar acrylate can be used suitably. Examples of the substrate-penetrating monomer that is particularly preferably used in such a case include tricyclodecane dimethanol diacrylate, morpholine acrylate, and the like.

  In addition, the base-penetrating monomer used in the present invention may be one type or two or more types.

  When such a substrate-penetrating monomer is contained in the polarizing plate adhesive of the present invention, the content of the polarizer and polarizing plate protective film is desired using the polarizing plate adhesive of the present invention. There is no particular limitation as long as the polarizing plate bonded with adhesive strength can be produced. In particular, the content of the base-penetrating monomer in the present invention is in the range of 10 to 200 parts by weight with respect to 100 parts by weight of the above-mentioned mixture of urethane (meth) acrylate and polyol (meth) acrylate. In particular, it is preferably in the range of 30 to 150 parts by weight, more preferably in the range of 50 to 100 parts by weight. This is because if the content of the substrate-penetrating monomer is less than the above range, the viscosity of the polarizing plate adhesive of the present invention becomes too high, and coating suitability may be impaired. Further, if the amount is larger than the above range, the adhesive property between the polarizer and the polarizing plate protective film may not reach the desired range when the polarizing plate is produced using the polarizing plate adhesive of the present invention. It is.

(2) Photopolymerization initiator Next, the photopolymerization initiator will be described. The photopolymerization initiator used in the present invention has a function of inducing a curing reaction of the urethane (meth) acrylate and the polyol (meth) acrylate when irradiated with ultraviolet rays.

The photopolymerization initiator used in the present invention is not particularly limited as long as it can induce the curing reaction of the urethane (meth) acrylate and the polyol (meth) acrylate by absorbing light in a predetermined wavelength region. It is not something. Among them, the photopolymerization initiator used in the present invention is preferably one that does not absorb in the wavelength region of 500 nm or more, particularly preferably one that does not absorb in the wavelength region of 480 nm or more, It is preferable that it does not show absorption in a wavelength region of 450 nm or more. This is because if the photopolymerization initiator exhibits absorption in the above-mentioned wavelength region, the polarizing plate produced using the polarizing plate adhesive of the present invention may become strong.
Here, in the present invention, “not exhibiting absorption” means that the absorbance of a solution in which a photopolymerization initiator is dissolved in toluene at a concentration of 5% by mass is measured using a spectrophotometer. It shall mean that the light absorbency is 0.5% or less.

  In addition, when a polarizing plate is prepared using the polarizing plate adhesive of the present invention, since the photopolymerization initiator is usually irradiated with ultraviolet rays through the polarizing plate protective film, the above used in the present invention. The photopolymerization initiator is preferably one that can induce a curing reaction by absorbing light in a wavelength region other than the wavelength region absorbed by the polarizing plate protective film. Here, the polarizing plate protective film used when preparing the polarizing plate using the polarizing plate adhesive of the present invention usually prevents the polarizing plate protective film itself from being deteriorated by ultraviolet rays, Alternatively, in order to prevent the polarizer from being deteriorated by ultraviolet rays, an ultraviolet absorber is often contained. In such a case, it is preferable to use a photopolymerization initiator that can induce a curing reaction by absorbing light having a wavelength longer than the wavelength region absorbed by the ultraviolet absorbent as the photopolymerization initiator used in the present invention. For example, when the ultraviolet absorber absorbs light of 400 nm or less, the photopolymerization initiator is one that can induce the curing reaction described above by absorbing light having a wavelength longer than 400 nm. It is preferable.

  When the viewpoint of coloring and the viewpoint of the absorption characteristics of the polarizing plate protective film are combined, the photopolymerization initiator used in the present invention is on the longer wavelength side than the wavelength region absorbed by the polarizing plate protective film, And it is preferable to use what can induce hardening reaction by absorbing the light of shorter wavelength side than 500 nm. In the present invention, normally, as such a photopolymerization initiator, those capable of inducing a curing reaction by absorbing light having a wavelength region in the range of 400 nm to 500 nm are preferably used.

  Examples of such photopolymerization initiators include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamine) benzophenone, α-amino acetophenone, 4, 4-dichlorobenzophenone, 4-benzoyl-4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone P-tert-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyldimethyl ketal, benzylmethoxyethyl acetal Benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-tert-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzsuberone, methyleneanthrone, 4-azidobenzylacetophenone, 2,6-bis (p- Azidobenzylidene) cyclohexane, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2 -(O-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoy ) Oxime, Michler's ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, Naphthalene sulfonyl chloride, quinoline sulfonyl chloride, n-phenylthioacridone, 4,4-azobisisobutyronitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, Adeca N1717, carbon tetrabromide, Examples include combinations of photoreducing dyes such as tribromophenylsulfone, benzoin peroxide, eosin, and methylene blue with reducing agents such as ascorbic acid and triethanolamine.

  As content of the said photoinitiator in the adhesive agent for polarizing plates of this invention, when producing a polarizing plate using the adhesive agent for polarizing plates of this invention, the said urethane (meth) acrylate and said polyol ( The meth) acrylate is not particularly limited as long as it can be cured within a desired time. Among them, in the present invention, the content of the photopolymerization initiator is preferably in the range of 0.1% by mass to 10% by mass, particularly preferably in the range of 1% by mass to 7% by mass, It is preferably in the range of 2% to 5% by mass.

  In addition, the photoinitiator used for this invention may be 1 type, or 2 or more types.

(3) Silane coupling agent Next, the said silane coupling agent is demonstrated. As a silane coupling agent used in the present invention, when a polarizing plate is produced using the polarizing plate adhesive of the present invention, it can contribute to improvement in adhesion between the polarizer or the polarizing plate protective film and the adhesive layer. If it is a thing, it will not specifically limit. Examples of such silane coupling agents include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3 -Glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxy Propyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3- Aminopropyltrie Xysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, Examples thereof include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. In the present invention, any of these silane coupling agents can be suitably used, and among them, a silane coupling agent having an amino group or a mercapto group is preferably used.

  Moreover, when a silane coupling agent is contained in the adhesive agent for polarizing plates of this invention, it is preferable that it is in the range of 0.1 mass%-10 mass% as it is content, Especially 0.3 mass It is preferable to be within the range of 7% to 7% by weight, and it is particularly preferable to be within the range of 0.5% to 3% by weight.

  In addition, the silane coupling agent used for this invention may be 1 type, or 2 or more types.

4). Adhesive for polarizing plate The adhesive for polarizing plate of the present invention contains at least the urethane (meth) acrylate and the polyol (meth) acrylate, but the urethane contained in the adhesive for polarizing plate of the present invention ( As a content ratio of the (meth) acrylate and the polyol (meth) acrylate, a polarizing plate in which a polarizer and a polarizing plate protective film are bonded with a desired adhesive force using the polarizing plate adhesive of the present invention is produced. There is no particular limitation as long as it is within a possible range. Especially in this invention, it is preferable that content of the said polyol (meth) acrylate with respect to 100 weight part of said urethane (meth) acrylates exists in the range of 5 weight part-300 weight part, Especially 10 weight part-200 weight part. Is preferably in the range of 20 parts by weight to 150 parts by weight. If the content of the polyol (meth) acrylate is less than the above range, the adhesive may not be sufficiently spread out on the base material, resulting in poor adhesion. This is because there is a concern that the adhesive strength decreases when moisture is absorbed.

Moreover, the adhesive agent for polarizing plates of this invention has the advantage that the viscosity as the whole adhesive agent for polarizing plates can be made low by including the said urethane (meth) acrylate and the said polyol (meth) acrylate. Is. Thus, the fact that the viscosity of the entire polarizing plate adhesive can be reduced means that when the polarizing plate is produced using the polarizing plate adhesive of the present invention, the adhesive layer can be thinned and cut. This contributes to obtaining a polarizing plate excellent in aptitude.
Here, as a viscosity of the adhesive for polarizing plates of this invention, when producing a polarizing plate using the adhesive for polarizing plates of this invention, the coating system etc. which apply the adhesive for polarizing plates of this invention, etc. The viscosity of the adhesive for polarizing plates of the present invention is preferably in the range of 0.1 cps to 10,000 cps, and particularly 0.5 cps to 7,000 cps. Preferably, it is in the range of 1 cps to 5,000 cps. If the viscosity is lower than the above range, it may be difficult to obtain a uniform adhesive layer due to dripping when the adhesive is placed on the substrate before bonding. This is because the base material needs to be stretched at a risk of being destroyed.
Moreover, although the temperature range used as a preferable viscosity is dependent on the softening temperature of the base material to be used, the range of 10 to 80 degreeC normally, Preferably 23 to 60 degreeC is preferable. This is because it is difficult to control the temperature below 10 ° C., and when it is above 80 ° C., the polarizer may be damaged.
The viscosity of the adhesive for polarizing plates of the present invention can be increased by increasing the molecular weight of at least one of the urethane (meth) acrylate and the polyol (meth) acrylate, and the urethane (meth). It can be lowered by reducing the molecular weight of at least one of the acrylate and the polyol (meth) acrylate.

Furthermore, when using what has an isocyanate group (NCO group) as said urethane (meth) acrylate, as an amount of the isocyanate group contained in the adhesive agent for polarizing plates of this invention, the adhesive agent for polarizing plates of this invention is used. And the amount of the urethane (meth) acrylate contained in the polarizing plate adhesive of the present invention can be appropriately adjusted and used. Among them, in the adhesive for polarizing plates of the present invention, the amount of the isocyanate group (NCO group) is preferably in the range of 0.1 mol% to 30 mol%, particularly 0.5 mol% to 20 mol. %, Preferably in the range of 1 mol% to 10 mol%. If the content of the isocyanate group is less than the above range, there is a possibility that the effect of improving the adhesiveness by using a compound containing an isocyanate group (NCO group) as the urethane (meth) acrylate cannot be expressed to a desired level. Because. On the other hand, if the amount is larger than the above range, in the polarizing plate produced using the polarizing plate adhesive of the present invention, too many urethane bonds are formed between the polarizer and the adhesive layer. This is because the characteristics may be impaired.
In addition, about the method of measuring content of the said isocyanate group (NCO group), since it is the same as that of the method mentioned above, description here is abbreviate | omitted.

5. Use of the adhesive for polarizing plate The adhesive for polarizing plate of the present invention can be used for producing a polarizing plate having a structure in which a polarizer used for a liquid crystal display device and the like and a polarizing plate protective film are bonded together. It is used for bonding a polarizing plate protective film.

  A method for producing a polarizing plate using the polarizing plate adhesive of the present invention will be described. As a method for producing a polarizing plate using the polarizing plate adhesive of the present invention, a structure in which a polarizer and a polarizing plate protective film are bonded via an adhesive layer comprising the polarizing plate adhesive of the present invention. If it is a method which can manufacture the polarizing plate which has, it will not specifically limit. As such a method, for example, the polarizing plate adhesive of the present invention was applied to both sides of the polarizer and the step of applying the polarizing plate adhesive of the present invention to one surface of the polarizing plate protective film. The urethane (meth) acrylate and the polyol (meth) acrylate are cured by irradiating the adhesive for polarizing plate of the present invention with ultraviolet rays through the step of bonding the polarizing plate protective film and the polarizing plate protective film. The manufacturing method which has a process can be mentioned.

  The polarizer used for producing the polarizing plate using the polarizing plate adhesive of the present invention is not particularly limited as long as it has predetermined polarization characteristics, but is usually a film made of polyvinyl alcohol. A material in which a complex of polyvinyl alcohol and iodine is formed by impregnating with iodine and uniaxially stretching it is used.

  Moreover, as a polarizing plate protective film used when manufacturing a polarizing plate using the adhesive agent for polarizing plates of this invention, the function which prevents that a polarizer is exposed to the water | moisture content in air, etc., and a polarizer There is no particular limitation as long as it has a function of preventing the dimensional change. As such a polarizing plate protective film, it is possible to use a film made of a cellulose derivative typified by cellulose triacetate, which has been widely used, and a film made of a cycloolefin-based resin. .

  Specific examples of the polarizing plate protective film made of the cycloolefin resin include, for example, Topas manufactured by Ticona, Arton manufactured by JSR, ZEONOR manufactured by Nippon Zeon, ZEONEX manufactured by Nippon Zeon, and Appel manufactured by Mitsui Chemicals. be able to.

B. Next, the polarizing plate of the present invention will be described. The polarizing plate of the present invention comprises a polarizer made of polyvinyl alcohol, an adhesive layer formed on both sides of the polarizer, and a polarizing plate protective film formed on both sides of the polarizer and formed on the adhesive layer. The adhesive layer has a urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing ( A cured product with a polyol (meth) acrylate obtained from a (meth) acrylate compound is included, and at least a urethane bond is formed between the adhesive layer and the polarizer.

Such a polarizing plate of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of the polarizing plate of the present invention. As illustrated in FIG. 1, a polarizing plate 10 of the present invention includes a polarizer 1 made of polyvinyl alcohol, an adhesive layer 2 formed on both surfaces of the polarizer 1, and both surfaces of the polarizer 1, And a polarizing plate protective film 3 formed on the adhesive layer 2.
In such an example, in the polarizing plate 10 of the present invention, the adhesive layer 2 includes a cured product of the urethane (meth) acrylate and the polyol (meth) acrylate, and at least the adhesive layer 2 and the polarized light. A urethane bond is formed with the child 1.

According to the present invention, the adhesive layer includes the urethane (meth) acrylate and a cured product of the polyol (meth) acrylate, and at least a urethane bond is formed between the adhesive layer and the polarizer. Therefore, a polarizing plate having excellent adhesion between the polarizer and the polarizing plate protective film can be obtained.
Further, the urethane (meth) acrylate and the cured product of the polyol (meth) acrylate contained in the adhesive layer are such that the adhesive layer emits light to the urethane (meth) acrylate and the polyol (meth) acrylate. Since it can produce | generate by irradiating, in the process of manufacturing the polarizing plate of this invention, it becomes unnecessary to use a solvent in order to form the said contact bonding layer. For this reason, it becomes unnecessary to install the process of drying the said contact bonding layer in the process of manufacturing the polarizing plate of this invention.

Moreover, when the said adhesive layer contains the hardened | cured material of the said urethane (meth) acrylate and the said polyol (meth) acrylate, in the polarizing plate of this invention, it becomes possible to make the said adhesive layer into a thin film. For this reason, according to this invention, the polarizing plate excellent in the cutting process characteristic can be obtained.
Here, the reason why the polarizing plate having excellent cutting work characteristics can be obtained by the adhesive layer containing the urethane (meth) acrylate and a cured product of the polyol (meth) acrylate is as follows. is there.
In other words, the polarizing plate of the present invention can be easily produced by using an adhesive for polarizing plate containing the urethane (meth) acrylate and the polyol (meth) acrylate. The adhesive for polarizing plates containing (meth) acrylate and the above polyol (meth) acrylate has a low viscosity and has thin film coatability. For this reason, it becomes possible to form a thin adhesive layer by forming the adhesive layer using such an adhesive for polarizing plates, and as a result, a polarizing plate having excellent cutting characteristics can be obtained. It is.

  Moreover, in this invention, since the hardened | cured material of the said urethane (meth) acrylate and the said polyol (meth) acrylate is contained in the said contact bonding layer, it is represented by the triacetyl cellulose as said polarizing plate protective film. Even when a polarizing plate protective film made of a cellulose derivative is used, it is not necessary to saponify the polarizing plate protective film as in the prior art. In the past, since an aqueous PVA solution was used as an adhesive, it was necessary to form hydroxyl groups that contribute to the formation of hydrogen bonds on the surface of the polarizing plate protective film, but the adhesive used in the present invention is This is because the adhesive force is not expressed by hydrogen bonding. Therefore, the polarizing plate of the present invention can be produced without performing a saponification treatment step even when a polarizing plate protective film made of a cellulose derivative is used, and simplifies the polarizing plate production step. Has the advantage of being able to

  In addition, the fact that the polarizing plate of the present invention can be produced without performing the saponification treatment step described above has the following advantages. That is, in order to obtain a polarizing plate having an additional function, a material having a desired function is contained in the polarizing plate protective film, or a functional layer having a desired function is conventionally laminated. . However, conventionally, when a polarizing plate protective film made of a cellulose derivative is used, the saponification treatment step is necessary, so that a material used for imparting a desired function to the polarizing plate protective film made of the cellulose derivative is used. There is a restriction that only compounds having alkali resistance can be used. In this respect, since the polarizing plate of the present invention can be produced without performing the saponification treatment step, it is not necessary to limit the compounds that can be used as materials having a predetermined function to those having alkali resistance. Thus, an appropriate material can be selected and used from a wide range.

In addition to the above effects, the polarizing plate of the present invention has the following advantages. That is, in the conventional polarizing plate, polyvinyl alcohol has been used as an adhesive for bonding the polarizer and the polarizing plate protective film. Since polyvinyl alcohol exhibits water solubility, a polarizing plate using such an adhesive has a problem of poor moisture resistance.
In this respect, the adhesive layer used in the present invention contains the urethane (meth) acrylate and a cured product of the polyol (meth) acrylate, so that the durability of the adhesive force is maintained even in a high humidity atmosphere. It will be excellent. For this reason, the polarizing plate of this invention has the advantage that it is excellent in durability in a high-humidity atmosphere.

  In addition, "(meth) acrylate" in the present invention is meant to include acrylate and methacrylate.

The polarizing plate of the present invention has at least the polarizer, the adhesive layer, and the polarizing plate protective film.
Hereafter, each structure used for such a polarizing plate of this invention is demonstrated in order.

1. First, the adhesive layer used in the present invention will be described. The adhesive layer used in the present invention is formed on both surfaces of a polarizer described later, and has a function of bonding a polarizer described later and a polarizing plate protective film. The adhesive layer used in the present invention comprises a urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meta ) A cured product of a polyol (meth) acrylate obtained from an acrylate compound. By using such an adhesive layer, the polarizing plate of the present invention is excellent in adhesiveness between a polarizer and a polarizing plate protective film described later, and excellent in productivity.
Hereinafter, the adhesive layer used in the present invention will be described in detail.

  The urethane (meth) acrylate and polyol (meth) acrylate used for the adhesive layer in the present invention are the same as those described in the above section “A. Adhesive for polarizing plate”, and are therefore described here. Is omitted.

The adhesive layer used in the present invention contains at least a cured product of the urethane (meth) acrylate and the polyol (meth) acrylate, but the configuration of the urethane (meth) acrylate contained in the adhesive layer. As a ratio of the unit and the constituent unit of the polyol (meth) acrylate, depending on the type of the urethane (meth) acrylate and the polyol (meth) acrylate, or the type of the polarizing plate protective film used in the present invention Thus, it can be appropriately adjusted within a range where desired adhesiveness can be imparted to the adhesive layer. In particular, in the present invention, the ratio of the urethane (meth) acrylate constituent unit contained in the adhesive layer to the polyol (meth) acrylate constituent unit (urethane (meth) acrylate constituent unit: polyol (meta ) The structural unit of acrylate) is preferably in the range of 1: 0.05 to 1: 3, particularly preferably in the range of 1: 0.1 to 1: 2, and more preferably 1: 0. It is preferable to be in the range of 2 to 1: 1.5. It is because the adhesiveness of the said adhesive layer can be made higher because the said ratio exists in such a range.
Here, the ratio can be determined by elemental analysis.

  Moreover, as above-mentioned, the contact bonding layer used for this invention can make thickness thin by containing the hardened | cured material of the said urethane (meth) acrylate and the said polyol (meth) acrylate. . Here, as the thickness of the adhesive layer used in the present invention, the flexibility of the polarizing plate of the present invention can be within a desired range, and the optical characteristics of the polarizing plate of the present invention are within the desired range. If it is the range which can be made, it will not specifically limit. In particular, in the present invention, the thickness of the adhesive layer is preferably in the range of 0.01 μm to 100 μm, particularly preferably in the range of 0.05 μm to 70 μm, and more preferably in the range of 0.08 μm to 50 μm. It is preferable to be within. When the thickness is thicker than the above range, the flexibility of the polarizing plate of the present invention is impaired. For example, when the polarizing plate of the present invention is manufactured, the manufactured polarizing plate can be wound into a roll shape. This is because it is feared that it will be difficult. Moreover, it is because the color of the polarizing plate of this invention may change. On the other hand, when the thickness is thinner than the above range, the adhesion between the polarizer and the polarizing plate protective film described later may be insufficient.

The adhesive layer used in the present invention contains at least the urethane (meth) acrylate and a cured product of the polyol (meth) acrylate, but may contain other compounds as necessary. . The other compound used in the present invention is not particularly limited as long as a desired function can be imparted to the adhesive layer, and any compound can be selected depending on the specific mode of the polarizing plate of the present invention. It can be used. Among these, examples of other compounds that can be suitably used in the present invention include a cured product of a base-penetrating monomer, a silane coupling agent, and the like.
Hereinafter, these other compounds will be described in order.

(1) Cured product of substrate permeable monomer First, the cured product of the substrate permeable monomer will be described. The hardened | cured material of the base material permeable monomer used for this invention is a hardened | cured material of the base material permeable monomer which has permeability | transmittance with respect to the polarizing plate protective film mentioned later. When the cured product of the base material-permeable monomer is contained in the adhesive layer, the polarizing plate of the present invention can be made more excellent in the adhesiveness between the adhesive layer and the polarizing plate protective film.

The cured product of the substrate-permeable monomer used in the present invention is obtained by curing the substrate-permeable monomer.
Here, the base-penetrating monomer is the same as that described in the section “A. Adhesive for polarizing plate”, and therefore, the description thereof is omitted here.

  Further, the cured product of the base material permeable monomer used in the present invention is obtained by curing the base material permeable monomer. An embodiment cured by reacting permeable monomers with each other, or an embodiment cured by reacting the substrate permeable monomer with the urethane (meth) acrylate or the polyol (meth) acrylate. It may be.

  In addition, the base-penetrating monomer used in the present invention may be one type or two or more types.

When the adhesive layer used in the present invention contains a cured product of the substrate-permeable monomer, the content of the constituent unit of the substrate-permeable monomer contained in the adhesive layer is the polarizing plate of the present invention. In the above, there is no particular limitation as long as the adhesive strength between the adhesive layer and the polarizing plate protective film described below is within a range where the adhesive strength can be set to a desired level. Especially, in this invention, it exists in the range of 0.1 weight part-200 weight part with respect to 100 weight part of polymers of the said urethane (meth) acrylate and the said polyol (meth) acrylate contained in a contact bonding layer. In particular, it is preferably in the range of 0.5 to 100 parts by weight, and more preferably in the range of 1 to 70 parts by weight.
In addition, content of the structural unit of the said base-penetrating monomer in a contact bonding layer can be calculated | required by the elemental analysis method, for example.

(2) Silane coupling agent Next, the said silane coupling agent is demonstrated. The silane coupling agent used in the present invention is not particularly limited as long as it can contribute to the improvement of the adhesive function of the adhesive layer.
Here, since the silane coupling agent used in the present invention is the same as that described in the above-mentioned section “A. Adhesive for polarizing plate”, detailed description thereof is omitted here.

  When the adhesive layer used in the present invention contains a silane coupling agent, the amount of the silane coupling agent contained in the adhesive layer is preferably in the range of 0.1% by mass to 10% by mass, It is preferably in the range of 0.3 mass% to 7 mass%, particularly preferably in the range of 0.5 mass% to 5 mass%.

  In addition, the silane coupling agent used for this invention may be one type, or may be two types.

2. Next, the polarizing plate protective film used in the present invention will be described. The polarizing plate protective film used in the present invention is both surfaces of a polarizer to be described later, and is formed on the above-described adhesive layer. In the polarizing plate of the present invention, the polarizer described later includes moisture in the air, etc. It has a function to prevent exposure to light, a function to prevent dimensional change of the polarizer, and the like.

The polarizing plate protective film used in the present invention is not particularly limited as long as it can protect the polarizer in the polarizing plate of the present invention and has desired transparency. Among them, the polarizing plate protective film used in the present invention preferably has a transmittance in the visible light region of 80% or more, and more preferably 90% or more.
Here, the transmittance of the polarizing plate protective film can be measured by JIS K7361-1 (Testing method of total light transmittance of plastic-transparent material).

  As a material constituting the polarizing plate protective film used in the present invention, for example, cellulose derivative, cycloolefin resin, polymethyl methacrylate, polyvinyl alcohol, polyimide, polyarylate, polyethylene terephthalate, polysulfone, polyethersulfone, amorphous polyolefin, Examples thereof include modified acrylic polymers, polystyrene, epoxy resins, polycarbonates and polyesters. In particular, in the present invention, it is preferable to use a cellulose derivative or a cycloolefin resin as the resin material.

  Especially as said cellulose derivative, if it has the function which prevents the polarizer mentioned later in the polarizing plate of this invention from being exposed to the water | moisture content etc. in the air, and the function which prevents the dimensional change of a polarizer, especially. It is not limited. In particular, in the present invention, it is preferable to use cellulose esters as the cellulose derivative, and among the cellulose esters, it is preferable to use cellulose acylates. This is because cellulose acylates are advantageous in terms of availability because they are widely used industrially.

  As said cellulose acylates, C2-C4 lower fatty acid ester is preferable. The lower fatty acid ester may include only a single lower fatty acid ester such as cellulose acetate, and may include a plurality of fatty acid esters such as cellulose acetate butyrate and cellulose acetate propionate. There may be.

In the present invention, among the above lower fatty acid esters, cellulose acetate can be particularly preferably used. As the cellulose acetate, it is most preferable to use triacetyl cellulose having an average acetylation degree of 57.5% to 62.5% (substitution degree: 2.6 to 3.0). This is because such triacetylcellulose is excellent in optical isotropy.
Here, the degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation can be determined by measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). In addition, the acetylation degree of the triacetyl cellulose which comprises a triacetyl cellulose film can be calculated | required by said method, after removing impurities, such as a plasticizer contained in a film.

  Conventionally, when a film made of a cellulose derivative is used as a polarizing plate protective film, it has been necessary to improve the adhesiveness with a polarizer made of polyvinyl alcohol by saponifying the surface. However, in the present invention, since the adhesive layer as described above is used, a polarizing plate protective film made of a cellulose derivative is not subjected to saponification treatment even when a polarizer made of polyvinyl alcohol is used. Can be used. For this reason, in the present invention, by using a polarizing plate protective film made of a cellulose derivative, a higher productivity improvement effect can be obtained than when a polarizing plate protective film made of another material is used.

On the other hand, the cycloolefin resin is not particularly limited as long as it is a resin having a monomer unit composed of a cyclic olefin (cycloolefin). Examples of such a monomer comprising a cyclic olefin include norbornene and polycyclic norbornene monomers.
In addition, as the cycloolefin resin used in the present invention, either a cycloolefin polymer (COP) or a cycloolefin copolymer (COC) can be suitably used.

  The cycloolefin resin used in the present invention may be a homopolymer of a monomer composed of the above cyclic olefin or a copolymer.

In addition, the cycloolefin resin used in the present invention preferably has a saturated water absorption at 23 ° C. of 1% by mass or less, and in particular, has a range of 0.1% to 0.7% by mass. preferable. This is because by using such a cycloolefin-based resin, it is possible to make the polarizing plate of the present invention less susceptible to changes in optical properties and dimensions due to water absorption.
Here, the saturated water absorption is obtained by immersing in 23 ° C. water for 1 week according to ASTM D570 and measuring the increased weight.

  Furthermore, the cycloolefin resin used in the present invention preferably has a glass transition point in the range of 100 ° C to 200 ° C, particularly preferably in the range of 100 ° C to 180 ° C, and in particular, 100 ° C. What is in the range of -150 degreeC is preferable. This is because, when the glass transition point is within the above range, the polarizing plate of the present invention can be made more excellent in heat resistance and processability.

  Specific examples of the polarizing plate protective film made of a cycloolefin resin used in the present invention include, for example, Ticona Topas, JSR Arton, Nippon Zeon Corporation ZEONOR, Nippon Zeon Corporation ZEONEX, Mitsui Chemicals, Inc. Examples include apels.

  The configuration of the polarizing plate protective film used in the present invention is not limited to a configuration composed of a single layer, and may have a configuration in which a plurality of layers are laminated. Moreover, when it has the structure by which the several layer was laminated | stacked, the layer of the same composition may be laminated | stacked, and the several layer which has a different composition may be laminated | stacked.

  In addition, the thickness of the polarizing plate protective film used in the present invention can bring the flexibility of the polarizing plate of the present invention into a desired range, and by bonding the polarizer to the polarizer described later, There is no particular limitation as long as the dimensional change can be within a predetermined range. In particular, the thickness of the polarizing plate protective film used in the present invention is preferably in the range of 5 μm to 200 μm, particularly preferably in the range of 15 μm to 150 μm, and more preferably in the range of 30 μm to 100 μm. Is preferred. This is because if the thickness is thinner than the above range, the dimensional change of the polarizing plate of the present invention may increase. Moreover, when the thickness is thicker than the above range, for example, when the polarizing plate of the present invention is cut, processing waste may increase or the cutting blade may be worn quickly.

  The polarizing plate protective film used in the present invention may have retardation. By using a polarizing plate protective film having retardation, there is an advantage that the polarizing plate of the present invention can have a viewing angle compensation function for a liquid crystal display device.

  The aspect in which the polarizing plate protective film used in the present invention has retardation is not particularly limited as long as it can exhibit desired retardation. As such an aspect, for example, it has a configuration composed of a single layer and includes an optical property developing agent that exhibits retardation, and has retardation, and the above-described transparent resin material. A mode having retardation can be given by having a configuration in which a retardation layer containing a compound having refractive index anisotropy is laminated on a substrate. In the present invention, any of these embodiments can be suitably used.

  In addition, since the polarizing plate protective film which consists of the said cellulose derivative can be used for the polarizing plate of this invention as mentioned above, without performing a saponification process, the material which can be used in order to express the said phase difference There is an advantage that there are fewer restrictions. That is, as described above, conventionally, when using a polarizing plate protective film made of a cellulose derivative, a saponification treatment was required, so the material used to impart retardation to the polarizing plate protective film is: There was a restriction that it had to have alkali resistance capable of withstanding saponification. However, in the present invention, since the polarizing plate protective film made of the above cellulose derivative can be used without saponification treatment, there is no such limitation, and a material that can express a desired retardation is selected more widely. Has the advantage that it becomes possible.

3. Next, the polarizer used in the present invention will be described. The polarizer used for this invention consists of polyvinyl alcohol, and has a function which provides a polarizing characteristic to the polarizing plate of this invention.

  It is composed of the polarizer polyvinyl alcohol used in the present invention, and is not particularly limited as long as it can impart desired polarization characteristics to the polarizing plate of the present invention, and is generally used for a polarizing plate of a liquid crystal display device. The polarizer used can be used without particular limitation. As such a polarizer, usually, a film made of polyvinyl alcohol is impregnated with iodine and uniaxially stretched to form a complex of polyvinyl alcohol and iodine.

4). Polarizing plate The polarizing plate of the present invention is characterized in that a urethane bond is formed at least between the adhesive layer and the polarizer. As described above, since the urethane bond is formed between the adhesive layer and the polarizer, the polarizing plate of the present invention has excellent adhesion between the adhesive layer and the polarizer.
Here, in the polarizing plate of this invention, it can confirm that the urethane bond is formed between the said contact bonding layer and the said polarizer, for example by the elemental analysis method.

  In the present invention, the aspect in which the urethane bond between the adhesive layer and the polarizer is formed is not particularly limited. Among these, since the present invention contains a cured product of urethane (poly) acrylate in the adhesive layer, usually, an isocyanate group remaining in the urethane (poly) acrylate and polyvinyl alcohol constituting the polarizer. It becomes the aspect formed by condensing with the hydroxyl group.

  The aspect in which the urethane bond is formed in the polarizing plate of the present invention is not particularly limited as long as the urethane bond is formed at least between the adhesive layer and the polarizer. Therefore, the urethane bond may be formed only between the adhesive layer and the polarizer, or between the adhesive layer and the polarizer, and between the adhesive layer and the polarizing plate. The aspect formed between protective films may be sufficient.

  As an example in which the urethane bond is also formed between the adhesive layer and the polarizing plate protective film, for example, the polarizing plate protective film made of triacetyl cellulose is used and remains in the triacetyl cellulose. What is formed when a hydroxyl group and the isocyanate group which remains in the said urethane (poly) acrylate condense can be mentioned.

  In the present invention, in order to form a urethane bond between the adhesive layer and the polarizing plate protective film, the polarizing plate protective film is provided with a hydroxyl group that contributes to the formation of a urethane bond on the surface. May be used. Examples of the polarizing plate protective film having a hydroxyl group that contributes to the formation of urethane bonds on the surface include a polarizing plate protective film made of a cellulose derivative whose surface is saponified.

  The polarizing plate of the present invention has two adhesive layers on both surfaces of the polarizer, but the two adhesive layers may have the same composition or different compositions. It may be a thing. The polarizing plate of the present invention uses two polarizing plate protective films, but the two polarizing plate protective films may be the same or different. Good.

5. Next, a method for producing the polarizing plate of the present invention will be described. The method for producing the polarizing plate of the present invention is not particularly limited as long as it is a method capable of producing a polarizing plate having the above configuration. As such a method, for example, a polarizing plate adhesive containing the urethane (meth) acrylate and polyol (meth) acrylate described above and further containing a photopolymerization initiator is used. The step of coating on one side of the polarizing plate protective film, the step of bonding the polarizing plate protective film having the polarizing plate coated on both sides of the polarizer, and the polarizing plate protective film And a step of curing the urethane (meth) acrylate and the polyol (meth) acrylate by irradiating the adhesive for polarizing plate with ultraviolet rays.
The polarizing plate of the present invention can be easily produced by using the polarizing plate adhesive according to the present invention as the polarizing plate adhesive.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Next, the present invention will be described more specifically by showing examples.

(Preparation of urethane (meth) acrylate)
Add 32.9 g of isophorone diisocyanate to a reaction vessel equipped with a stirrer, heat the vessel to 40 ° C. to 55 ° C., add 0.39 g of dibutyltin dilaurate and 5.3 g of 2-hydroxyethyl acrylate, and add 55-70 Stir at 90 ° C. for 90 minutes. The residual isocyanate content of the obtained urethane (meth) acrylate was 5.3%.

(Preparation of adhesive for polarizing plate I)
10.0 g of polyethylene glycol 400 diacrylate (PEG400DA-D product name: Daicel Cytec Co., Ltd.) is mixed as the polyol (meth) acrylate with 10.0 g of the urethane (meth) acrylate obtained above, and the liquid temperature 90.8 g of Lucillin TPO (manufactured by BASF Corporation) was added while stirring at 50 ° C. to 60 ° C. and stirred until a uniform resin solution was obtained. Thereby, the adhesive agent I for polarizing plates of this invention was obtained.

(Preparation of polarizing plate adhesive II)
10.0 g of acryloyl morpholine (ACMO manufactured by Kojin Co., Ltd.) was further added as a base material penetrating monomer to the polarizing plate adhesive I prepared as described above to obtain a polarizing plate adhesive II.

1. Example 1
The adhesive for polarizing plate I heated to 40 ° C. was applied on a triacetyl cellulose film (manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm and laminated from both sides of a polarizer made of polyvinyl alcohol. 200 mJ / cm ² of ultraviolet rays were irradiated from the acetyl cellulose film surface with a UV irradiation device (H bulb manufactured by Fusion UV Systems). A polarizing plate was prepared by performing this operation on both sides.

2. Example 2
A polarizing plate was produced in the same manner as in Example 1 except that the polarizing plate adhesive II was used instead of the polarizing plate adhesive I.

3. Comparative Example A polarizing plate was produced in the same manner as in Example 1 except that only the urethane (meth) acrylate was used instead of the polarizing plate adhesive I.

4). Evaluation The peeling test between the polarizer and the polarizing plate protective film was performed on the polarizing plates prepared in the above Examples and Comparative Examples. In the peel test, a polarizing plate having a width of 25 mm and a length of 150 mm was used, and the peel strength when peeled at 180 ° by a Tensilon tensile tester manufactured by Orientec was measured according to JIS Z0237.
As a result, in the polarizing plates produced in Examples 1 and 2, peeling between the boundaries between the polarizer and the polarizing plate protective film did not occur, and when the load was continuously applied, the polarizing plate protective film was broken.
On the other hand, in the polarizing plate produced in the comparative example, it peeled between the boundaries of a polarizer and a polarizing plate protective film.

It is the schematic which shows an example of the polarizing plate of this invention. It is the schematic which illustrates typically a part of common liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polarizer 2 ... Adhesion layer 3 ... Polarizing plate protective film 10 ... Polarizing plate 101 ... Liquid crystal cell 102A, 102B ... Polarizing plate 112A, 112B ... Polarizer 122A, 122B ... Polarizing plate protective film

Claims (9)

Urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound,
A polarizing plate adhesive comprising: a polyol compound; and a polyol (meth) acrylate obtained from a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound.   The adhesive for polarizing plates according to claim 1, wherein the urethane (meth) acrylate has an isocyanate group (NCO group).   The adhesive for polarizing plates according to claim 1, comprising a base material penetrating monomer that has permeability to the polarizing plate protective film.   The adhesive for polarizing plates according to any one of claims 1 to 3, wherein a silane coupling agent is contained.   The polarizing plate adhesive according to any one of claims 1 to 4, wherein the polyol compound is a polyether polyol.   The adhesive for polarizing plates according to any one of claims 1 to 5, wherein the polyisocyanate compound is an alicyclic polyisocyanate compound. A polarizing plate comprising a polarizer made of polyvinyl alcohol, an adhesive layer formed on both sides of the polarizer, and a polarizing plate protective film formed on both sides of the polarizer and formed on the adhesive layer. ,
The adhesive layer is a urethane (meth) acrylate obtained from a polyisocyanate compound and a hydroxyl group-containing (meth) acrylate compound,
A cured product of a polyol compound and a polyol (meth) acrylate obtained from a hydroxyl group-containing (meth) acrylate compound or a carboxyl group-containing (meth) acrylate compound, and at least between the adhesive layer and the polarizer A polarizing plate, wherein a urethane bond is formed on the polarizing plate.   The polarizing plate according to claim 7, wherein the adhesive layer contains a cured product of a base-penetrating monomer that has permeability to the polarizing plate protective film.   The polarizing plate according to claim 7 or 8, wherein the polarizing plate protective film is made of a cellulose derivative.

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