TWI629329B - Photocurable adhesive composition, polarizing plate and manufacturing method thereof, optical member, and liquid crystal display device - Google Patents

Abstract

The present invention provides a photocurable adhesive, which shows a bonding force immediately after light irradiation even when a resin film having low moisture permeability is used as a protective film. The bonding force after a certain period of time is relative to various forces. Good, and it will not cause problems after the endurance test, and the adhesion after the end of the moist heat resistance test is also good, and the viscosity is low; and a polarizing plate is formed by using the adhesive to bond a protective film to a polarizer.

A photocurable adhesive composition is an adhesive composition for adhering a protective film composed of a specific four types of transparent resin films to a polarizer composed of a polyvinyl alcohol resin film; Specific ratios include (A) poly (meth) acrylates with 2 to 15 carbons, (B) polyglycidyl ethers with 2 to 10 carbons, and (C) specific structures An oxetane compound, (D) a (meth) acrylic polymer, and (E) a cationic photopolymerization initiator.

Description

Photocurable adhesive composition, polarizing plate and manufacturing method thereof, optical member, and liquid crystal display device

The present invention relates to a photocurable adhesive composition for bonding a polarizer and a protective film in a polarizer, a polarizer obtained by bonding a protective film to a polarizer using the adhesive composition, and the polarizer Of manufacturing method. The present invention also relates to an optical member and a liquid crystal display device using the polarizing plate.

A polarizing plate can be used as one of the optical parts constituting a liquid crystal display device. A polarizing plate is usually incorporated in a liquid crystal display device in a state in which a protective film is laminated on both sides of a polarizer. It is also known to provide a protective film only on one side of a polarizer, but in most cases, it is not only a protective film on the other side, but also another layer having an optical function that is also used as a protective film. In addition, as a method for producing a polarizer, a method is known in which a uniaxially stretched polyvinyl alcohol resin film dyed with a dichroic dye is subjected to boric acid treatment, washed with water, and then dried.

Usually, immediately after the above-mentioned water washing and drying, a protective film is attached to the polarizer. This is because the polarizer after drying has weak physical strength, and when it is wound up, problems such as cracking in the processing direction occur. Therefore, for polarizers after drying, water-based The adhesive, and then the protective film is simultaneously stuck on both sides with the adhesive. As the protective film, a triethylammonium cellulose film having a thickness of 30 to 120 μm is generally used.

When adhering a polarizer and a protective film, especially a protective film made of a triethyl cellulose film, a polyvinyl alcohol-based adhesive is often used, but some people have also tried to use a urethane adhesive instead. Agent. For example, Japanese Patent Application Laid-Open No. 7-20617 (Patent Document 1) describes that a urethane prepolymer is used as an adhesive, and a polarizer having a high water content and cellulose acetate are protected. A film (such as a triethylammonium cellulose film) is then attached.

On the other hand, triethyl cellulose has a high moisture permeability, so the polarizing plate obtained by bonding the resin film as a protective film has the following problems: under humid heat, for example, at a temperature of 70 ° C and a relative humidity of 90% Causes deterioration under conditions. Therefore, a method of solving a related problem by using a resin film having a lower moisture permeability than a triethylammonium cellulose film as a protective film has been proposed. For example, it is known to use an amorphous polyolefin resin as a protective film. Specifically, reducing thermoplastic saturation An olefin resin sheet is laminated on at least one surface of a polarizer as a protective film, and this is described in Japanese Patent Application Laid-Open No. 6-51117 (Patent Document 2).

In the case where such a low-permeability protective film is bonded using a conventional device, a protective film (for example, an aqueous polyvinyl alcohol solution) is used as the main solvent to bond the protective film to a polyvinyl alcohol-based polarizer. Then, the solvent is dried. Such a so-called wet lamination has problems such as insufficient adhesion strength, or poor appearance. This is because films with low moisture permeability are generally thinner than triethyl cellulose Since the membrane has low hydrophobicity and / or moisture permeability, it is impossible to sufficiently dry water as a solvent and the like.

Therefore, in Japanese Patent Application Laid-Open No. 2000-321432 (Patent Document 3), it is proposed that a polyvinyl alcohol-based polarizer and a thermoplastic resin be reduced by the saturation of a thermoplastic resin by using a polyurethane adhesive. A protective film made of an olefin resin is adhered. However, the polyurethane adhesive has a problem that it takes a long time to harden, and the adhesive force may not be sufficient.

On the other hand, it is also known that different types of protective films are bonded to both sides of a polarizer. For example, Japanese Patent Application Laid-Open No. 2002-174729 (Patent Document 4) proposes the following: A protective film made of an amorphous polyolefin-based resin is laminated on one side of a polarizer formed of a thin film, and a resin different from the amorphous polyolefin-based resin (for example, triethylammonium cellulose) is laminated on the other side. ), A protective film; Japanese Patent Application Laid-Open No. 2005-208456 (Patent Document 5) proposes the following: On one surface of a polarizing film formed of a polyvinyl alcohol resin, a specific amino group is contained The cycloolefin-based resin film is laminated with an aqueous first adhesive of an acid ester resin, and is laminated with a second aqueous adhesive different from the first adhesive (for example, an aqueous solution of a polyvinyl alcohol resin) on the other side. Cellulose acetate resin film.

A substance referred to as an amorphous polyolefin-based resin in the aforementioned Patent Document 4 and a cycloolefin-based resin in the aforementioned Patent Document 5 is a substance having a A unit of a monomer formed by a polycyclic cyclic olefin such as an olefin and / or a derivative thereof and a dibridged methylene octahydronaphthalene, and when a double bond remains like a ring-opening polymer, It is preferably a thermoplastic resin obtained by hydrogenation thereof.

In addition, Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 6) discloses an adhesive containing an epoxy resin containing no aromatic ring as a main component, and a method has been proposed in which active energy is irradiated to the adhesive The polarizer and the protective film are bonded by performing cationic polymerization. The epoxy-based adhesive disclosed herein is particularly effective for bonding various transparent resin films typified by amorphous polyolefin resins and cellulose resins to polarizers. However, acrylic adhesives are particularly effective When the resin is a protective film, it is clear that the adhesion is not necessarily sufficient.

Therefore, when the present inventors and others made a resin film with low moisture permeability selected from acrylic resin, polyester resin, polycarbonate resin, and amorphous polyolefin-based resin as a protective film for a polarizer, Development of low-viscosity photocurable adhesives that exhibit good adhesion in a short time step. The results were found to be as follows: A composition containing a glycidyl ether type epoxy resin having an aromatic ring and an oxetane compound produces good adhesion, particularly in a composition containing 5 to 25% by weight of an alicyclic skeleton ( In the case of a meth) acrylate-based monomer, high adhesion and durability are shown (Patent Document 7). However, this adhesive has a problem that although the production step itself may use a short time step such as light irradiation, a sufficient adhesive force will not be exhibited if a period of time does not elapse after the film is wound up. Therefore, there is a problem that it is not easy to perform thin film processing after light irradiation in a production step.

The present inventors have made various efforts to solve the aforementioned problems. As a result of the investigation, it was found that a photocurable adhesive composition containing an alicyclic epoxy compound, a specific poly (meth) acrylate, a cationic photopolymerization initiator, and propylene oxide was effective (Patent Document 8).

This adhesive composition is a photocurable adhesive for polarizing plates which is excellent not only in adhesive strength and durability but also in productivity.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Unexamined Patent Publication No. 7-20617

[Patent Document 2] Japanese Unexamined Patent Publication No. 6-51117

[Patent Document 3] Japanese Patent Laid-Open No. 2000-321432

[Patent Document 4] Japanese Patent Laid-Open No. 2002-174729

[Patent Document 5] Japanese Patent Laid-Open No. 2005-208456

[Patent Document 6] Japanese Patent Laid-Open No. 2004-245925

[Patent Document 7] Japanese Patent Laid-Open No. 2010-209126

[Patent Document 8] Japanese Patent Laid-Open No. 2012-140610

However, in the adhesive of the aforementioned Patent Document 8, it was found that when a protective film made of an acrylic resin is bonded to a polarizer, a humidity and heat resistance test is performed in a high-temperature and high-humidity environment (for example, 60 ° C 90%). , And then return to the normal environment (for example, 23 ° C 50%), the peeling force immediately after returning to the normal environment is quite low.

Regarding the reduction of the adhesion force, when the acrylic resin protective film is peeled off after being left in a normal environment for 15 hours, the protective film is developed. The extent to which the green material is damaged restores the peel adhesion. In addition, even after the end of the moist heat resistance test, the protective film did not peel off under the action of a force (a force in a shearing direction or a vertical direction) applied in the form of a product in which a polarizing plate was attached to glass. However, in the worst case of exposing the polarizer to a high-temperature and high-humidity environment and immediately entering a processing step, it is expected to further improve the peel strength immediately after the end of the moist-heat resistance test.

Furthermore, when an acrylic resin protective film is bonded to a polarizer, a peeling test in which an acrylic resin is bent by attaching a polarizer to a plate such as glass, or a T-type peeling test in which both films are bent Although the adhesive force was good, the peeling test in which the polarizer was bent by attaching an acrylic resin to a plate, such as glass, had a problem that the adhesive force was significantly reduced. For this reason, when a relatively strong force such as bending the polarizer is applied to the end portion in a processing step or the like of the polarizing plate, peeling may occur. In order to prevent such problems, it is required to develop an adhesive that exhibits good adhesion even in a peeling test in which an acrylic resin is fixed to a plate and the polarizer is bent.

The problem to be solved by the present invention is to provide a photocurable adhesive, which is a resin film having low moisture permeability selected from polyester resins, polycarbonate resins, acrylic resins, and amorphous polyolefin resins. In the case of a protective film, the adhesive force appears immediately after light irradiation, and the final adhesive force after a certain period of time is also good. It does not cause problems such as appearance defects after the endurance test. The adhesive force after the end of the moist heat test is also good. Low viscosity before hardening. Further, there is provided an adhesive agent which adheres a protective film made of acrylic resin to a polarizer, A protective film made of acrylic resin was pasted on a board, and a force such as that by which the polarizer was bent was applied, and excellent adhesion was also exhibited.

Another object of the present invention is to provide an optical member capable of forming a liquid crystal display device with excellent reliability by using a polarizing plate using the adhesive, and another object is to apply the same to a liquid crystal display device.

That is, the present invention provides a photocurable adhesive composition, which is an adhesive composition for adhering a protective film to a polarizer, and the protective film is made of polyester resin, polycarbonate resin, acrylic resin, and A transparent resin film selected from the group consisting of an amorphous polyolefin-based resin, the polarizer is composed of a polyvinyl alcohol-based resin film that is uniaxially stretched and adsorbs and aligns with a dichroic pigment, It is characterized by containing: (A) a poly (meth) acrylate having a polyol having 2 to 15 carbons, and (B) a polyol having 2 to 10 carbons (except for alkylene oxide) A polyglycidyl ether other than a polyether polyol having a unit repeat number of 3 or more), (C) a propylene oxide compound represented by the following formula (1),

(D) a polymer having an alkyl (meth) acrylate as an essential structural monomer unit, (E) a cationic photopolymerization initiator, The content ratio of the components (A) to (E) in the composition is:

(A) Ingredient: 15 ~ 50% by weight

(B) Ingredient: 2 ~ 35% by weight

(C) Composition: 2 ~ 50% by weight

(D) Ingredient: 1 ~ 30% by weight

(E) Ingredient: 0.5 to 10% by weight.

The component (A) is preferably a di (meth) acrylate having a diol having 2 to 10 carbon atoms. The (meth) acrylate is more preferably an acrylate.

The component (B) is preferably a diglycidyl ether having a diol having 2 to 10 carbon atoms (except for a polyether diol having 3 or more repeating alkylene oxide units).

(A) component, (B) component, (C) component, (D) component, and (E) component preferably contain 20 to 45% by weight, 5 to 30% by weight, and 5 to 3% in the composition. 35 wt%, 5 to 25 wt%, and 1 to 6 wt%.

The component (D) preferably contains a polymer containing an alkyl (meth) acrylate containing an alkyl group having 1 to 10 carbons as a structural monomer unit and having a weight average molecular weight of 1,000 to 500,000.

The polymer is preferably (D1) a polymer containing 60% by weight or more of methyl methacrylate as a structural monomer unit and having a weight average molecular weight of 1,000 to 200,000 [hereinafter, also referred to as "(D1) Component "]; and (D2) a polymer containing 60% by weight or more of an alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms as a structural monomer unit and having a weight average molecular weight of 1,000 to 200,000 [hereinafter, also referred to as "(D2) component"].

As a component (D2), it is still more preferable that it is a polymer obtained by high temperature polymerization, and this polymer contains 60 weight% or more of alkyl acrylates containing a C1-C10 alkyl group as a structure. The monomer unit has a weight average molecular weight of 1,000 to 20,000.

The component (D) is preferably a material containing the component (D1) and the component (D2).

Furthermore, it is preferable that these photocurable adhesive composition contain at least two alicyclic rings represented by the following formula (2) in the molecule and contain (F) at a content ratio of 1 to 25% by weight in the composition. A photocurable adhesive composition of an epoxy compound of formula epoxy.

The component (F) is preferably an epoxy compound represented by the following formula (3).

Radical polymerizable components such as the component (A) contained in these photocurable adhesive composition can be cured by using radicals generated when the component (E) is decomposed under the action of light. In order to obtain a sufficient reaction rate, the photoradical polymerization initiator is preferably contained as a component (G) in a proportion of 10% by weight or less.

Furthermore, regarding these photocurable adhesive composition, In order to obtain a coated surface excellent in smoothness, it is preferable to include a leveling agent as the component (I) in the composition in an amount of 0.01 to 0.5% by weight.

In addition, the present invention provides a polarizing plate, which is a polarizing plate obtained by bonding a protective film to a polarizer with an adhesive. The protective film is selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and The polarizer is made of a transparent resin film in a crystalline polyolefin resin, and the polarizer is made of a polyvinyl alcohol resin film that is uniaxially stretched and adsorbs and aligns with a dichroic pigment. The adhesive is made of It is formed from any one of the photocurable adhesive compositions described above.

The polarizing plate can be manufactured by a method including the step of applying an adhesive coating step of any one of the photocurable adhesive composition described above to at least one of the bonding surfaces of the polarizer and the protective film; A bonding step of bonding a polarizer and a protective film from the obtained adhesive layer; and curing the photocurable adhesive composition in a state where the polarizer and the protective film are bonded by the adhesive layer Hardening step. Specifically, a method can be adopted in which the above-mentioned photocurable adhesive composition that is not cured is applied to a polarizer, a protective film is adhered on the coated surface of the adhesive composition, and then the adhesive composition is cured. A method for forming an adhesive layer: coating the protective film with the above-mentioned photocurable adhesive composition that is not hardened, then bonding a polarizer to the surface of the adhesive composition, and curing the adhesive composition. Method for forming an adhesive layer; casting the uncured photocurable adhesive composition between a polarizer and a protective film, and sandwiching the adhesive composition of the polarizer and the protective film with a roller or the like to sandwich the adhesive composition While uniformly squeezing and expanding, and crimping, the adhesive composition is hardened to form an adhesive layer. Method, etc.

The present invention further provides an optical member in which the above-mentioned polarizing plate and other optical layers showing optical functions are laminated. The other optical layer in this case preferably includes a retardation plate. A liquid crystal display device in which the optical member is arranged on one or both sides of a liquid crystal cell is also provided.

The photocurable adhesive composition of the present invention is a case where a resin film having a low moisture permeability selected from a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin resin is used as a protective film. In this case, the adhesive force immediately appeared after light irradiation, and the final adhesive force after a certain period of time was also good, and no problems such as appearance failure after the durability test were caused. Further, the adhesive force after the end of the moist heat resistance test was excellent. This adhesive composition system is especially useful when a protective film consists of an acrylic resin. This adhesive composition is obtained when an acrylic resin is bonded to a polarizer, and in a peeling test in which the peeling strength is weakened, that is, when the acrylic resin is fixed to a smooth plate and the polarizer is bent The following peel test also showed good adhesion. Thereby, it is excellent also in the point which does not peel easily in a process step.

In addition, since the adhesive composition of the present invention has a very low viscosity, it is easy to apply thinly and adhere without defects. Regarding a polarizing plate obtained by bonding a polarizer and a protective film using the adhesive composition, the adhesive composition is not only cured in a short time step such as light irradiation, but also obtained immediately after the light irradiation is completed. Adhesive force of a certain strength can be manufactured with good productivity.

Furthermore, regarding the combination of this polarizing plate and other optical layers, The obtained optical member can form a liquid crystal display device having excellent reliability.

[Form of Implementing Invention]

Hereinafter, the present invention will be described in detail. In the present invention, when a protective film made of a transparent resin film is next attached to a polarizer made of a polyvinyl alcohol-based resin film that is uniaxially stretched and adsorbs and aligns with a dichroic pigment, a specific composition is used. Photocurable adhesive composition. By polarizing the polarizer and the protective film through the photocurable adhesive composition in this manner, a polarizing plate can be obtained. This polarizing plate can be made into an optical member by being laminated with other optical layers having optical functions. In addition, by disposing the optical member on at least one side of the liquid crystal cell, a liquid crystal display device can be manufactured. Hereinafter, the order of the photocurable adhesive composition, the manufacturing method of a polarizing plate, a polarizing plate, an optical member, and a liquid crystal display device is demonstrated.

[Photocurable adhesive composition]

In the present invention, in order to adhere the polarizer and the protective film, a photocurable adhesive composition having a specific composition is used. Hereinafter, this photocurable adhesive composition may be simply referred to as "photocurable adhesive" or "composition". The photocurable adhesive of the present invention is a photocurable adhesive that must contain the following five components (A), (B), (C), (D), and (E).

(A) a poly (meth) acrylate having a polyol having 2 to 15 carbons, (B) a polyol having 2 to 10 carbons (but excluding poly Polyglycidyl ether other than ether polyol), (C) a propylene oxide compound represented by the following formula (1),

(D) A polymer having an alkyl (meth) acrylate as an essential structural monomer unit, and (E) a cationic photopolymerization initiator.

In the present specification, (meth) acrylate means acrylate or (meth) acrylate, and (meth) acrylfluorenyl means acrylfluorenyl or methacrylfluorenyl.

In this specification, the poly (meth) acrylate of (A) is also referred to as "(A) component" or "poly (meth) acrylate (A)", and the epoxy of (B) is also referred to The compound is called "(B) component" or "epoxy compound (B)", and the propylene oxide compound of (C) is also called "(C) component" or "propylene oxide compound (C)", and The polymer having the (D) alkyl (meth) acrylate as an essential structural monomer unit is referred to as "(D) component", and the cationic photopolymerization initiator of (E) is referred to as "(E) Component "or" cationic photopolymerization initiator (E) ".

The content ratios of the components (A) to (E) are based on the entire composition, and the component (A) is set to 15 to 50% by weight, the component (B) is set to 2 to 35% by weight, ( C) The component is set to 2 to 50% by weight, the (D) component is set to 1 to 30% by weight, and the (E) component is set to 0.5 to 10% by weight.

The photocurable adhesive may optionally contain As a component (F), the epoxy compound which has at least two alicyclic epoxy group represented by Formula (2) mentioned later is preferable to set it as the content ratio of 1-25 weight% in a composition. The component (F) is preferably an epoxy compound represented by the formula (3) described later.

In addition, a photo radical polymerization initiator may be contained as the (G) component, and the content ratio is preferably 10% by weight or less. In addition, when the component (F) is blended, it is preferable to contain 1 to 10% by weight of a propylene oxide compound represented by the formula (4) described later as the (H) component. Further, a leveling agent may be contained as the (I) component.

In this specification, the epoxy compound (F) is also referred to as "(F) component" or "epoxy compound (F)", and the photoradical polymerization initiator of (G) is also referred to as "(G) ) Component "or" photoradical polymerization initiator (G) ", and the propylene oxide compound of (H) is also referred to as" (H) component "or" propylene oxide compound (H) ", and (I) The leveling agent is called "(I) ingredients" or "leveling agent (I)".

<Poly (meth) acrylate (A)>

In the photocurable adhesive of the present invention, the poly (meth) acrylate which is the component (A) is a poly (meth) acrylate having a polyhydric alcohol having 2 to 15 carbon atoms.

The durability of the (meth) acrylic acid ester having a number of (meth) acrylic acid fluorenyl groups in the molecule of 1 is likely to be insufficient.

By using the component (A), the viscosity of the composition is reduced, and the adhesion to the protective film and the durability are excellent. Here, as (A) component, the di (meth) acrylate which has a diol with 2-10 carbon atoms is more preferable from a viewpoint of low viscosity, adhesive force, and durability. another The (meth) acrylate is preferably an acrylate from the viewpoint of curability.

Specific examples of the component (A) include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 3-methyl-1,5-pentanediol. Di (meth) acrylate, cyclohexane dimethylol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, 1,9- Nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, diethylene glycol Alcohol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tricyclodecane dimethyloldi (Meth) acrylate, trimethylolpropane tri (meth) acrylate, bis (trimethylolpropane) tetra (meth) acrylate, neopentaerythritol tri or tetra (meth) acrylate, Dipentaerythritol penta or hexa (meth) acrylate, and hydrogenated bisphenol A di (meth) acrylate and the like.

The component (A) may have an ester skeleton and / or an isocyanurate skeleton. Specific examples of the compound having an ester skeleton include an esterification reaction product of neopentyl glycol with hydroxytrimethylacetic acid and (meth) acrylic acid. Examples of the compound having an isotricyanate skeleton include Diisotricyanate alkylene oxide adducts of di- or tri (meth) acrylates are produced.

Among them, the esterification reaction products of 1,6-hexanediol di (meth) acrylate and neopentyl glycol with hydroxytrimethylacetic acid and (meth) acrylic acid have reduced viscosity, adhesion, and durability. The viewpoint of being excellent and having less odor is especially preferable.

The content ratio of the component (A) is within a range of 15 to 50% by weight based on the entire composition. By setting this ratio, the adhesive force immediately after the light irradiation is completed, the final adhesive force, and durability can be made good. In addition, when the content ratio of the (A) component is in the range of 20 to 45 wt%, the adhesion can be made better.

<Epoxy Compound (B)>

In the photocurable adhesive of the present invention, the epoxy compound serving as the component (B) is a polyol having 2 to 10 carbon atoms (except for polyether polyols having an alkylene oxide unit having a repeating number of 3 or more). ) Polyglycidyl ether.

The epoxy compound having the number of glycidyl ether groups in the molecule of 1 and the durability such as adhesive force and / or cold-heat cycle resistance tends to be insufficient. In addition, even with a polyol having 2 to 10 carbons, the polyglycidyl ether compound obtained from a polyether polyol having an alkylene oxide unit having a repeating number of 3 or more is durable, such as adhesion and / or cold-heat cycle resistance. Sex also tends to become insufficient.

By using the component (B), the viscosity of the composition is reduced, and the adhesion to the polarizer is excellent. Here, as the component (B), from the viewpoint that the composition can be made to have a low viscosity and can be made into a substance having excellent adhesion, a diol having 2 to 10 carbon atoms (but excluding epoxy Diglycidyl ether other than polyether diols having an alkane unit repeating number of 3 or more.

Specific examples of the component (B) include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6- Hexylene glycol diglycidyl Ether, cyclohexane dimethylol diglycidyl ether, 1,9-nonanediol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, hydroquinone diglycidyl ether, intermediate Resorcinol diglycidyl ether, trimethylolpropane triglycidyl ether, neopentaerythritol tri- or tetraglycidyl ether, and di- or triglycidyl ether of ethylene isocyanate adducts .

Among them, alkanediol diglycidyl ether having 2 to 10 carbon atoms is particularly preferred from the viewpoint of low viscosity and adhesion.

The content ratio of the component (B) is in the range of 2 to 35% by weight based on the entire composition. By setting this ratio, the adhesive force immediately after the light irradiation is completed, the final adhesive force, and the adhesive force after the moist heat resistance test can be made good. From this viewpoint, the content ratio of the component (B) is preferably 5 to 30% by weight, more preferably 10 to 30% by weight, and still more preferably 15 to 30% by weight.

<Propylene oxide compound (C)>

In the photocurable adhesive of this invention, the propylene oxide compound which becomes (C) component is a propylene oxide compound represented by following formula (1).

The content ratio of the component (C) is in the range of 2 to 50% by weight based on the entire composition. By setting this ratio, the adhesive force immediately after the light irradiation and the final adhesive force can be made good. By blending the component (C) in an appropriate amount, the adhesion to various substrates is improved, but particularly the adhesion to the acrylic resin protective film is greatly improved.

When the content of the component (C) is less than 2% by weight, the adhesive force immediately after the light irradiation and the final adhesive force are insufficient. Moreover, when it exceeds 50 weight%, the adhesive force with respect to a polarizer will fall.

The content ratio of the component (C) is preferably 5 to 35% by weight, and more preferably 10 to 30% by weight, from the viewpoint of more excellent adhesion.

<Polymer (D) using alkyl (meth) acrylate as an essential structural monomer unit>

In the photocurable adhesive of the present invention, by including the component (D), the final adhesive force and the adhesive force after the moist heat resistance test can be made good.

As the component (D), various polymers can be used as long as the polymer has an alkyl (meth) acrylate as an essential structural monomer unit. As the component (D), it is preferable that the alkyl (meth) acrylate is a structural monomer unit, and the polymer contains 50 mol% or more of the total structural monomer units in the polymer, more preferably Preferably, the polymer contains 80 mol% or more.

Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, secondary butyl (meth) acrylate, and (meth) Tertiary butyl acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n- (meth) acrylate Octyl ester, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, (formyl) N-dodecyl acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and the like.

Among these compounds, an alkyl (meth) acrylate containing an alkyl group having 1 to 10 carbons is preferred, and an alkyl (meth) acrylate having a lower alkyl group having 1 to 4 carbons is more preferred.

The component (D) may be a copolymer of an alkyl (meth) acrylate and an ethylenically unsaturated monomer (hereinafter referred to as "other monomer") that is copolymerizable with the (meth) acrylate.

As specific examples of other monomers, carboxyl group-containing monomers such as (meth) acrylic acid; sulfonyl group-containing monomers such as acrylamine 2-methylpropanesulfonic acid and styrenesulfonic acid; and phosphoric acid Monomers; cyano-containing monomers such as (meth) acrylonitrile; vinyl esters; aromatic vinyl compounds such as styrene and α-methylstyrene; monomers containing acid anhydride groups; (methyl ) Hydroxyl-containing monomers such as hydroxyethyl acrylate, hydroxyethyl (meth) acrylate, and hydroxyalkyl (meth) acrylate, such as hydroxyethyl (meth) acrylate; acrylamide, dimethylacrylamide Monomers containing amine groups, such as diethylpropenamide; monomers containing amine groups; monomers containing iminium groups; epoxy group-containing monomers such as glycidyl (meth) acrylate; ( (Meth) acrylfluorenyl Phthalolines; and vinyl ethers.

As the (D) component, various polymers from the aforementioned polymers can be used.

For the purpose of improving adhesion and improving solubility with the composition, a copolymer of an alkyl (meth) acrylate and an acid group-containing monomer is preferred.

Examples of the acidic group-containing monomer include a carboxyl group-containing monomer, a sulfo group-containing monomer, an acid anhydride group-containing monomer, and a phosphate group-containing monomer, and the carboxyl group-containing monomer is preferred.

The copolymer is preferably a copolymer having an acid value of 20 mgKOH / g or less, and more preferably 15 mgKOH / g or less, for the reason that the storage stability of the composition is good.

The molecular weight of the component (D) is preferably 1,000 to 500,000, more preferably 1,000 to 200,000 in terms of weight average molecular weight (hereinafter referred to as "Mw").

In the present invention, Mw represents a value obtained by converting a molecular weight measured by gel permeation chromatography (hereinafter referred to as "GPC") into polystyrene.

As the component (D), various polymers selected from the aforementioned polymers can be used, but it is preferable that the (meth) acrylic acid alkyl group containing an alkyl group having 1 to 10 carbon atoms is used as a structural monomer unit and the weight is average Polymers with a molecular weight of 1,000 to 500,000.

More preferable examples of the polymer include the following two polymers.

‧ (D1) component: a polymer containing 60% by weight or more of methyl methacrylate as a structural monomer unit and having a Mw of 1,000 to 200,000; (D2) component: A polymer containing 60% by weight or more of an alkyl acrylate containing an alkyl group having 1 to 10 carbons as a structural monomer unit and having a Mw of 1,000 to 200,000.

The component (D1) is a polymer containing methyl methacrylate as a structural monomer unit, containing 60% by weight or more, and having a Mw of 1,000 to 200,000, and is preferred for reasons of excellent adhesion to an acrylic resin.

The component (D1) may be a copolymer with an acidic group-containing monomer. Examples of the acidic group-containing monomer include the same monomers as described above, and preferably Carboxyl-containing monomer.

The copolymer is preferably a copolymer having an acid value of 20 mgKOH / g or less, and more preferably a copolymer having 15 mgKOH / g or less, for the same reason as described above.

The component (D1) is commercially available, and examples include DIANAL BR-80 (containing 60% by weight or more of methyl methacrylate as a structural monomer unit, Mw95,000, and an acid value of 0 mgKOH / g). Polymethyl methacrylate (PMMA) polymer), DIANAL BR-83 (containing 60% by weight or more of methyl methacrylate as structural monomer unit, Mw40,000, PMMA polymer with an acid value of 2 mgKOH / g ) And DIANAL BR-87 (a PMMA polymer containing 60% by weight or more of methyl methacrylate as a structural monomer unit, Mw 25,000, and an acid value of 10.5 mgKOH / g).

The component (D1) can also be produced by high-temperature polymerization (preferably by high-temperature continuous polymerization) described later.

(D2) The component contains 60% by weight or more of an alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms as a structural monomer unit, and Mw is 1,000 to 200,000, and it is preferable because it has excellent final adhesion to a polarizer.

Examples of the alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms include the same compounds as described above.

As for the component (D2), if the alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms is used as a structural monomer unit and 60% by weight or more is contained, it may be combined with an alkyl methacrylate and / or other Copolymer of monomers.

(D2) The component may be one containing an alkyl group having 1 to 10 carbon atoms. An alkyl acrylate, a block copolymer with an alkyl methacrylate and / or other monomers [hereinafter referred to as "(D2-1) component"].

Preferred combinations of the monomers in the component (D2-1) include a block polymer having a polyacrylate block unit and a polymethacrylate block unit, and a block polymer having a polyacrylate block unit and Block polymers such as block units of polymers of other monomers.

Among them, a block polymer having a polyacrylate-based block unit and a polymethacrylate-based block unit is preferable, and polybutyl acrylate and polymethyl methacrylate are more preferably used as the block. Unit block polymer.

The component (D2-1) can be produced by polymerization using a conventional method using the aforementioned monomer, and examples thereof include a radical polymerization method, a living anion polymerization method, a living radical polymerization method, and the like. Examples of the form of polymerization include a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a block polymerization method.

The (D2-1) component is commercially available, and Clarity (LA1114, LA2140e, LA2330, LA2250) made by Kuraray Corporation is listed.

(D2) The component is a polymer having an Mw of 1,000 to 200,000, but a polymer having an Mw of 1,000 to 100,000 is preferable, and 1,000 to 20,000 is more preferable. The polymer having this Mw is preferable because it has a low viscosity and the obtained composition is also easy to be coated with a low viscosity, and / or it can be increased due to the restriction that the composition has a low viscosity The blending number is preferred as a result of which the adhesion can be improved.

When it is desired to produce the low-molecular-weight polymer by a general polymerization method, it is usually necessary to increase a chain transfer agent and / or a polymerization initiator. Use large When a polymer using a chain transfer agent is used in a large amount, the cation hardenability and / or adhesion of the composition tends to decrease, and when a polymer using a large amount of a polymerization initiator is used, the storage stability of the composition tends to decrease.

Therefore, a polymer [hereinafter referred to as "(D2-2) component"] is preferably a polymer produced by high temperature polymerization that does not require a large amount of a chain transfer agent and / or a polymerization initiator. The polymer contains 60% by weight or more of an alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms as a structural monomer unit, and Mw is 1,000 to 20,000.

In the present invention, Mw represents a value obtained by converting the molecular weight measured by GPC into polystyrene.

The temperature for the high-temperature polymerization is preferably 160 to 350 ° C, and more preferably 180 to 300 ° C.

Among the high-temperature polymerizations, the high-temperature continuous polymerization is not only excellent in productivity, but also has the following advantages: since the composition distribution in the copolymer product is hard to occur, the compatibility is excellent.

The high-temperature continuous polymerization can be carried out by a known method (for example, Japanese Patent Application Publication No. 57-502171, Japanese Patent Application Publication No. 59-6207, and Japanese Patent Application Publication No. 60-215007).

Specifically, the method is described as follows: a pressurizable reactor is filled with a solvent, the temperature is set to a predetermined temperature under pressure, and then a monomer, or a polymerization solvent or a polymerization initiator as required, is fed at a constant supply rate. The constituent monomer mixture was supplied to the reactor, and a reaction liquid was extracted in an amount commensurate with the supply amount of the monomer mixture.

The glass transition temperature of the component (D2-2) is preferably 20 ° C or lower, and more preferably -90 to 0 ° C.

In the present invention, the glass transition temperature means a value measured by using a differential scanning calorimeter (DSC) at a temperature increase rate of 2 ° C / minute.

The component (D) in the present invention may be the introduction of a radical polymerizable functional group such as a (meth) acrylfluorenyl group and / or a cationic polymerizable functional group such as an epoxy group and / or a propylene oxide group into the polymer. And the winner. Examples of the method for introducing these functional groups include a method for introducing a functional anion and / or a living radical polymerization terminal, a method for adding a compound having a polymerizable functional group to a functional group in a polymer, and the like. When a cationic polymerizable functional group such as an epoxy group and / or a propylene oxide group is introduced, a (meth) acrylate having these functional groups may be copolymerized.

As the component (D), only one of the aforementioned compounds may be used, or two or more of them may be used in combination.

As a preferable combination of the (D) component, it is preferable to use a combination of the (D1) component and the (D2) component from the viewpoint of making both the adhesion to the polarizer and the adhesion to the protective film excellent. It is more preferable to use the component (D1) and the component (D2-2) in combination.

The combined ratio of the (D1) component and the (D2) component is preferably 1/9 to 7/3.

The content ratio of the component (D) needs to be 1 to 30% by weight, preferably 5 to 25% by weight based on the entire composition. By containing the (D) component in a ratio of 1 to 30% by weight, the adhesive force immediately after the light irradiation is completed, the final adhesive force, and the adhesive force after the moist heat resistance test can be made good.

<Cationic photopolymerization initiator (E)>

The photocurable adhesive of the present invention contains, as the cation-curable component, the epoxy compound (B), the propylene oxide compound (C) described above, and an epoxy compound and / or propylene oxide described later as necessary. Compound, and thus a cationic photopolymerization initiator is blended as the (E) component. The cationic photopolymerization initiator irradiates active energy rays such as visible light, ultraviolet rays, X-rays, and electron rays to generate a cationic species or a Lewis acid, and initiates a polymerization reaction of an epoxy group and / or a propylene oxide group.

By mixing a cationic photopolymerization initiator as the (E) component, curing at room temperature can be performed, and considering the heat resistance of the polarizer and / or the necessity of deformation due to expansion or contraction is reduced, the protective film can be adhered well . In addition, since the cationic photopolymerization initiator functions catalytically by irradiation with active energy rays, even if it is mixed with the epoxy compound (B), the propylene oxide compound (C), and the epoxy compound and / or epoxy described later The propane compound is also excellent in storage stability and / or workability. Examples of the compound that generates a cationic species and / or a Lewis acid by irradiating an active energy ray include an onium salt such as an aromatic diazonium salt, an aromatic iodonium salt, and / or an aromatic sulfonium salt, and iron-propanediamine. Ene complex and so on.

Examples of the aromatic diazonium salt include the following compounds.

Benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, benzenediazonium hexafluoroborate, and the like.

Examples of the aromatic iodonium salt include the following compounds.

Diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, bis (4-nonylphenyl) iodonium hexafluorophosphate Salt, etc.

Examples of the aromatic sulfonium salts include the following compounds.

Triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis (diphenylsulfonium) diphenylsulfide Bishexafluorophosphate, 4,4'-bis [bis (β-hydroxyethoxy) phenylsulfonium] diphenylsulfide, dihexafluoroantimonate, 4,4'-bis [bis (β-hydroxy Ethoxy) phenylsulfonium] diphenylsulfide dihexafluorophosphate, 7- [bis (p-tolylmethylsulfanyl) thionium] -2-isopropylthioxanthone hexafluoroantimonate, 7- [Di (p-toluenylmethyl) thionium] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylthionium-diphenylsulfide Hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonium-diphenylsulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl)- 4'-bis (p-toluenylmethyl) thionium-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like.

Examples of the iron-propadiene complex include the following compounds.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) -reference (Trifluoromethylsulfonyl) methanide and the like.

These cationic photoinitiators may be used individually by 1 type, and may use 2 or more types together. Among them, the aromatic sulfonium salt is particularly preferably used because it has ultraviolet absorption characteristics even in a wavelength range of 300 nm or more, so that it can produce a hardened product that is excellent in hardenability and has good mechanical strength and / or adhesive strength.

(E) The component can be easily obtained from a commercial product. For example, according to the product name, "Kayarad PCI-220", "Kayarad PCI-620" (above, manufactured by Nippon Kayaku Co., Ltd.), and "UVI -6992 "(manufactured by Dow Chemical)," Adekaoptomer SP-150 "," Adekaoptomer SP-160 "(above, made by ADEKA (stock))," CI-5102 "," CIT-1370 "," CIT-1682 " , "CIP-1866S", "CIP-2048S", "CIP-2064S" (above, Japan's Soda Co., Ltd.), "DPI-101", "DPI-102", "DPI-103", "DPI- 105 "," MPI-103 "," MPI-105 "," BBI-101 "," BBI-102 "," BBI-103 "," BBI-105 "," TPS-101 "," TPS-102 " , "TPS-103", "TPS-105", "MDS-103", "MDS-105", "DTS-102", "DTS-103" (above, Midori Chemical Co., Ltd.), "PI- 2074 "(manufactured by Rhodia)," Irgacure250 "," Irgacure PAG103 "," Irgacure PAG108 "," Irgacure PAG121 "," Irgacure PAG203 "(above, made by BASF)," CPI-100P "," CPI-101A "," CPI-210S "," CPI-110P "(above, San-Apro (share) system), etc. . In particular, "CPI-100P" and "CPI-110P" made by San-Apro (stock) are particularly preferable from the viewpoints of hardenability and adhesiveness.

The content ratio of the component (E) is in the range of 0.5 to 10% by weight based on the entire composition. When the proportion is less than 0.5% by weight, the curing of the adhesive becomes insufficient, and the mechanical strength and / or adhesive strength are reduced. On the other hand, when the proportion exceeds 10% by weight, the ionicity of the cured product may be caused. Increasing the amount of the material results in poor hygroscopicity and reduced durability of the hardened material. In addition, the content ratio of the (E) component is preferably 1 to 6% by weight, and by setting it within this range, optical characteristics such as transparency and / or durability can be made better.

<Epoxy Compound (F)>

In the photocurable adhesive of this invention, it is preferable to mix | blend an epoxy compound as a (F) component as mentioned above.

The component (F) is an epoxy compound having at least two alicyclic epoxy groups represented by the following formula (2) in the molecule, and generally, various known curable epoxy compounds can be used.

Specific examples of the component (F) include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and bis (3,4-epoxycyclohexylmethyl) Group) adipate, 3,4-epoxycyclohexylmethyl-3,4-epoxycaprolactone modified caprolactone, polycarboxylic acid and 3,4-epoxycyclohexyl An esterified product of methanol or a modified product of caprolactone, a silicone-based compound having an alicyclic epoxy group represented by the formula (2) at the terminal, and the like.

The (F) component is preferably an epoxy compound represented by the following formula (3) from the viewpoints of low viscosity, hardenability, excellent adhesion by a cutter insertion method, and durability.

(F) The epoxy compound of a component may be used individually by 1 type, and may mix and use 2 or more types.

Regarding the epoxy compound of the component (F), from the viewpoint of productivity, when the adhesive force immediately after completion of light irradiation is increased, or when the adhesive force by the cutter insertion method is increased, the entire composition is used as a reference. The content is preferably 1 to 25% by weight.

<Photo radical polymerization initiator (G)>

The radically curable components such as the component (A) contained in the photocurable adhesive of the present invention can be cured by using radicals generated when the component (E) is decomposed under the action of light. A sufficient reaction rate is obtained by the irradiation amount, and a photoradical polymerization initiator is preferably blended as the (G) component. The blending ratio of the (G) component is preferably 10% by weight or less, more preferably 0.1 to 10% by weight, and still more preferably 0.1 to 3% by weight based on the entire composition. When the blending amount is 10% by weight or less, the durability is excellent Different, so better.

Specific examples of the (G) component include the following compounds.

4'-phenoxy-2,2-dichloroacetophenone, 4'-tertiary butyl-2,2-dichloroacetophenone, 2,2-dimethoxy-2-phenylacetophenone Ketone, 2-methyl-1- (4-methylphenylthio) -2- Phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, α, α-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1- (4-cumyl) -2-hydroxy-2-methylpropane-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methylpropane-1-one, and 2-benzyl-2-dimethylamino-1- (4- Acetophenone-based photopolymerization initiators such as phenylphenyl) butane-1-one; benzoin, benzoin methyl ether, benzoin ether, benzoin isopropyl ether, and benzoin Benzoin ether-based photopolymerization initiators such as butyl ether; benzophenone, methyl o-benzoyl benzoate, 4-phenylbenzophenone, 4-benzyl-4'-methyl Diphenyl sulfide, and benzophenone-based photopolymerization initiators such as 2,4,6-trimethylbenzophenone; 2-isopropylthioxanthone, 2,4-diethylthio Tonone, 2,4-dichlorothioxanthone, and thioxanthone-based photopolymerization initiators such as 1-chloro-4-propoxythioxanthone; 2,4,6-trimethylbenzyl Diphenylphosphine oxide, bis (2,6-dimethoxybenzyl) -2,4,4-trimethylpentylphosphine oxide, and bis (2,4,6-trimethylbenzyl) Fluorenyl) fluorenylphosphine oxide-based photopolymerization initiators such as phenylphosphine oxide; 1- [4- (phenylthiophenyl)]-1,2-octanedione-2- (O-benzidine oxime ), Such as oxime and ester photopolymerization initiator; camphorquinone.

(G) A component may be used individually by 1 type, and may be used in mixture of 2 or more types depending on the desired performance.

In the case where the (G) component is blended with a photoradical polymerization initiator, the content ratio is based on the entire composition, preferably 10% by weight or less, and more preferably 0.1 to 3% by weight. When the content ratio of the photo radical polymerization initiator (G) is 10% by weight or less, sufficient strength is obtained, and when the content ratio is 0.1% by weight or more, the hardening property of the adhesive is excellent.

<Propylene oxide compound (H)>

In the photocurable adhesive of the present invention, a propylene oxide compound represented by the following formula (4) may be blended as a component (H). Regarding the component (H), when the component (F) is contained, it has the effect of improving the adhesive force immediately after the light irradiation is completed, or when the blade of the cutter is inserted into the acrylic resin protective film. From this viewpoint, the content ratio of the (H) component is preferably 1 to 10% by weight.

<Leveling agent (I)>

In the photocurable adhesive of the present invention, for the purpose of obtaining a coated surface excellent in smoothness, a leveling agent containing the component (I) is preferred.

Examples of the component (I) include polysiloxane-based leveling agents and fluorine-based leveling agents. Various commercially available leveling agents can be used.

A preferable content ratio of the component (I) is 0.01 to 0.5% by weight based on the entire composition. When the addition ratio is 0.01% by weight or more, the effect of adding a leveling agent can be sufficiently obtained. On the contrary, when the addition ratio is 0.5% by weight or less, the adhesiveness is excellent.

<Other hardening ingredients>

The photocurable adhesive of the present invention may contain other cation-curable components and / or radical-curable components in addition to the components (A) to (I) described above.

Examples of the cation-curable component other than the (B) component, the (C) component, the (F) component, and the (H) component include various epoxy compounds and / or propylene oxide compounds, and vinyl ether compounds.

Specific examples of the epoxy compound other than the component (B) and the component (F) include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl bromide of bisphenol A. Ether, phenol novolac epoxy resin, cresol novolac epoxy resin, biphenyl epoxy resin, diglycidyl terephthalate, diglycidyl phthalate, polybutadiene carboxylic acid terminal Addition reaction product of olefin and bisphenol A epoxy resin, dicyclopentadiene dioxide, limonene dioxide, 4-vinylcyclohexene dioxide, polyethylene glycol (repeated number 3 or more) Glycidyl ether, polypropylene glycol (repeated number 3 or more) diglycidyl ether, polytetramethylene glycol (repeated number 3 or more) diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, epoxidized vegetable oil, 2- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 -Glycidoxypropylmethyldimethoxysilane, polybutadiene diglycidyl ether at both terminal hydroxyl groups, polybutadiene Internal epoxide, a compound obtained by epoxidizing a part of the double bond of a styrene-butadiene copolymer [for example, "Epoflend" manufactured by Desir Chemical Industries, Ltd.], and ethylene-butene copolymerization A compound obtained by epoxidizing a part of an isoprene unit of a block copolymer of a polymer and a polyisoprene (for example, "L-207" manufactured by KRATON) and the like.

Specific examples of the propylene oxide compound other than the (C) component and the (H) component include an alkoxy group such as 3-ethyl-3- (2-ethylhexyloxymethyl) propylene oxide. Alkyl-based monofunctional propylene oxide, aromatic ethyl-containing monofunctional propylene oxide such as 3-ethyl-3-phenoxymethyl propylene oxide, 1,4-bis [(3-ethyl ring Oxypropane-3-yl) methoxymethyl] benzene, 1,4-bis [(3-ethyloxypropane-3-yl) methoxy] benzene, 1,3-bis [(3-ethyl Propylene oxide-3-yl) methoxy] benzene, 1,2-bis [(3-ethylpropylene oxide-3-yl) methoxy] benzene, 4,4'-bis [(3- Ethyloxypropane-3-yl) methoxy] biphenyl, 2,2'-bis [(3-ethyloxypropane-3-yl) methoxy] biphenyl, 3,3 ', 5 , 5'-Tetramethyl-4,4'-bis [(3-ethylpropylene oxide-3-yl) methoxy] biphenyl, 2,7-bis [(3-ethylpropylene oxide- 3-yl) methoxy] naphthalene, bis [4-{(3-ethylpropylene oxide-3-yl) methoxy} phenyl] methane, bis [2-{(3-ethylpropylene oxide -3-yl) methoxy} phenyl] methane, 2,2-bis [4-{(3-ethylepoxypropane-3-yl) methoxy} phenyl] propane, novolac phenol formaldehyde Resin based on 3-chloromethyl-3-ethyl propylene oxide The resulting etherification product, 3 (4), 8 (9) - bis [(3-ethyloxetane-3-yl) methoxymethyl] - tricyclo [5.2.1.0 ^2,6] Decane, 2,3-bis [(3-ethylpropane-3-yl) methoxymethyl] norbornane, 1,1,1-tri [(3-ethyloxypropane-3 -Yl) methoxymethyl] propane, 1-butoxy-2,2-bis [(3-ethyloxypropane-3-yl) methoxymethyl] butane, 1,2-bis [{2- (3-Ethoxypropane-3-yl) methoxy} ethylthio] ethane, bis [{4- (3-ethyloxypropane-3-yl) methylthio} Phenyl] sulfide, 1,6-bis [(3-ethyloxypropane-3-yl) methoxy] -2,2,3,3,4,4,5,5-octafluorohexane , 3-[(3-ethyloxypropane-3-yl) methoxy] propyltrimethoxysilane, 3-[(3-ethyloxypropane-3-yl) methoxy] propyl Hydrolyzed condensate of triethoxysilane, 3-[(3-ethyloxypropane-3-yl) methoxy] propyltrialkoxysilane, tetra [(3-ethyloxypropylene-3 -Yl) methyl] silicate, a condensation reaction product of 3-ethyloxypropane-3-ylmethanol and a silane tetraol condensation polymer, and the like.

Specific examples of the vinyl ether compound include cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl. Ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, and the like.

The content ratio of the cation-curable component other than the (B) component, (C) component, (F) component, and (H) component is based on the entire composition, preferably less than 30% by weight, and more preferably less than 20% by weight, particularly preferably less than 10% by weight.

Examples of the radical-curable component other than the component (A) include various compounds, and examples thereof include (meth) acrylic acid esters, (meth) acrylamidines, maleimides, and (meth) Acrylic acid, maleic acid, itaconic acid, (meth) acryl, (meth) acryloyl Porphyrin, N-vinyl-2-pyrrolidone, triallyl isotricyanate, divinyl adipate, vinyltrimethoxysilane, and the like.

Specific examples of (meth) acrylates having one (meth) acrylfluorenyl group in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate Ester, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, (formyl) Base) isooctyl acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) 4-hydroxybutyl acrylate, cyclohexyl (meth) acrylate, iso (meth) acrylate Ester, 1,4-cyclohexane dimethylol mono (meth) acrylate, dicyclopentyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (Meth) acrylate, benzyl (meth) acrylate, (meth) acrylate of phenol alkylene oxide adduct, (Meth) acrylates of alkyl phenol alkylene oxide adducts, (meth) acrylates of o-phenylphenol alkylene oxide adducts, (meth) acrylates of nonylphenol alkylene oxide adduct , 2-methoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, (meth) acrylates of alkylene oxide adducts of 2-ethylhexanol, pentyl Diethylene glycol mono (meth) acrylate, hexanediol mono (meth) acrylate, diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol Alcohol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate, polypropylene glycol mono ( (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-butoxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate Ester, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, (2-ethyl-2-methyl-1,3-dioxolane-4-yl) methyl (meth) acrylate , (2-isobutyl-2-methyl-1,3-dioxolane-4-yl) methyl (meth) acrylate, (1,4-di Oxaspiro [4,5] decane-2-yl) methyl (meth) acrylate, glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate , (3-ethyloxypropane-3-yl) meth (meth) acrylate, 2- (meth) acryloxyethyl isocyanate, allyl (meth) acrylate, N- ( (Meth) acryloxyethylhexahydroxylylenediamine, N- (meth) acryloxyethyltetrahydroxylylenediamine, 2- (meth) acryloxyethyl Hexahydrophthalic acid, 2- (meth) acryloxyethyl succinic acid, ω-carboxy-polycaprolactone mono (meth) acrylate, 2- (meth) acryloxyethyl Base acid phosphate, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyldimethoxymethylsilane, 3- (meth) propylene Ethoxypropyltriethoxysilane and the like.

In addition, specific examples of (meth) acrylates other than the component (A) having two or more (meth) acrylfluorenyl groups in the molecule [hereinafter referred to as "multifunctional (meth) acrylate"] Examples include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, di (meth) acrylate of bisphenol A alkylene oxide adduct, and urethane ( (Meth) acrylates, polyester (meth) acrylates, and epoxy (meth) acrylates. Examples of the polyester (meth) acrylate having three or more (meth) acrylfluorenyl groups include a dendrimer-type (meth) acrylate.

The blending ratio of the polyfunctional (meth) acrylate is preferably 2 to 20% by weight in the composition.

Specific examples of (meth) acrylamide include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, and N, N-diethyl (meth) acryl Ammonium amine, N-hydroxymethyl (meth) acrylamide, N- (3-N, N-dimethylaminopropyl) (meth) acrylamide, methylenebis (meth) acryl Ammonium amine, ethylene bis (meth) acrylamide, N, N-diallyl (meth) propylene Amidine and so on.

Specific examples of maleimidines include N-methylmaleimide, N-hydroxyethylmaleimide, N-hydroxyethylcitrateimine, and N-hydroxyethyl Carbamate reaction of citraconimine and isophorone diisocyanate, etc.

The content ratio of the radically curable component other than the component (A) is preferably less than 20% by weight based on the entire composition.

<Other ingredients without hardening properties>

Further, in the photocurable adhesive of the present invention, other components having no hardenability may be arbitrarily blended within a range that does not impair the effects of the present invention. Specifically, a photosensitizer, a cationic thermal polymerization initiator, Polyol compounds, water, etc.

Specific examples of the photosensitizer include benzophenone, methyl benzophenylidenebenzoate, 2-isopropylthioxanthone, 9,10-dibutoxyanthracene, and the like. Among them, there are compounds corresponding to the photoradical polymerization initiator of the component (G). However, the photosensitizers described herein are sensitive to the cationic photopolymerization initiators of the component (E). Reagents that work. These can be used individually or in mixture of 2 or more types.

The content of the photosensitizer is preferably less than 3% by weight based on the entire composition.

Specific examples of the cationic thermal polymerization initiator include benzylsulfonium salt, thiophenium salt, chioraniumu salt, benzylammonium salt, pyridinium salt, hydrazine salt, Carboxylic acid esters, sulfonic acid esters, amine imine, and the like. As for these initiators, commercially available products can be easily obtained, for example, each of them is represented by a trade name, and examples are: "Adekaoputon CP77" and "Adekaoputon CP66" (above, made by ADEKA (Stock)), "CI-2639" And "CI-2624" (above, Japan's Soda Co., Ltd.), "San-Aid SI-60L", "San-Aid SI-80L" and "San-Aid SI-100L" (above, Sanxin Chemical Industry) (Share) system) and so on.

The content of the cationic thermal polymerization initiator is preferably less than 3% by weight based on the entire composition.

Specific examples of the polyol compound include ethylene glycol, propylene glycol, polyether polyol compounds, polyester polyol compounds, polycaprolactone polyol compounds, polycarbonate polyol compounds, and the like.

The blending ratio of the polyol compound is preferably less than 10% by weight based on the entire composition.

Regarding the viscosity of the photocurable adhesive of the present invention, in order to obtain coatability that can be used in the manufacturing process of a polarizing plate, that is, to obtain a coated surface that is excellent in smoothness even in a thin film, the viscosity at 25 ° C is better It is 150mPa. Below s, more preferably 100mPa. s or less. More preferably, it is 50 mPa. s or less.

In the photocurable adhesive of the present invention, a small amount of water may be added in order to improve the adhesion to a polarizer having high dryness. In this case, the amount of water added is preferably less than 3% by weight, and more preferably less than 1% by weight based on the entire composition.

Other than these, as long as the effect of the present invention is not impaired, an ion trapping agent, an antioxidant, a light stabilizer, and a chain transfer agent may be blended. , Tackifiers, thermoplastic resins, metal oxide particles, defoamers, pigments, organic solvents, etc.

[Polarizer]

The photo-curable adhesive described above is used to adhere a protective film to a polarizer made of a polyvinyl alcohol-based resin film that is uniaxially stretched and adsorbs and aligns a dichroic dye. The protective film is thus used. The polarizing plate is attached to a polarizer. That is, the polarizing plate of the present invention is a polarizing plate obtained by bonding a protective film to a polarizing plate. The polarizing plate is made of a polyvinyl alcohol-based resin film that is uniaxially stretched and adsorbs and aligns a dichroic dye. The protective film may be attached to only one side of the polarizer, or may be attached to both sides of the polarizer. When a protective film is bonded to both surfaces of a polarizer, each protective film may be a protective film made of the same kind of resin, or a protective film made of different kinds of resin.

<Polarizer>

The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers that can be copolymerized therewith are also exemplified. Examples of other monomers copolymerized in vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol resin is usually in the range of 85 to 100 mol%, preferably in the range of 98 to 100 mol%. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and / or polyvinyl acetal obtained by modification with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 10,000. Around.

The polarizing plate is produced through the following steps: a step of uniaxially stretching such a polyvinyl alcohol-based resin film; a step of dyeing the polyvinyl alcohol-based resin film with a dichroic pigment to adsorb the dichroic pigment; A step of processing a polyvinyl alcohol-based resin film to which a dichroic pigment has been adsorbed by an aqueous boric acid solution; a step of washing with a boric acid aqueous solution after treatment; and attaching a protective film to the dichroism by performing these steps The dye undergoes a step of uniaxially stretching the polyvinyl alcohol-based resin film by adsorption alignment.

Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before or during a boric acid treatment. It is needless to say that uniaxial stretching may be performed at these multiple stages. For uniaxial stretching, uniaxial stretching may be performed between rollers having different peripheral speeds, or uniaxial stretching may be performed using a hot roller. In addition, it may be dry stretching performed in the air, or wet stretching performed in a state swollen with a solvent. The stretching ratio is usually about 4 to 8 times.

In order to dye a polyvinyl alcohol-based resin film with a dichroic dye, for example, the polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically, iodine or a dichroic dye can be used.

In the case of using iodine as a dichroic dye, the following method is generally used: a polyvinyl alcohol-based resin film is immersed in a film containing iodine and iodine Potassium solution in water, thereby staining. The content of iodine in the aqueous solution is usually about 0.01 to 0.5 parts by weight with respect to 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 10 parts by weight with respect to 100 parts by weight of water. The temperature of the aqueous solution is usually about 20 to 40 ° C, and the immersion time in the aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method is generally adopted in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye to dye. The content of the dichroic dye in the aqueous solution is usually about 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight based on 100 parts by weight of water. The aqueous solution may contain inorganic salts such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80 ° C, and the immersion time in the aqueous solution is usually about 30 to 300 seconds.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The content of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by weight, and preferably about 5 to 12 parts by weight, based on 100 parts by weight of water. When using iodine as a dichroic dye, it is preferable that this boric-acid aqueous solution contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is usually about 2 to 20 parts by weight, and preferably 5 to 15 parts by weight relative to 100 parts by weight of water. The immersion time in the boric acid aqueous solution is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, and still more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C or higher, and preferably 50 to 85 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. After washing A drying process is performed to obtain a polarizer. The temperature of the water in the water washing treatment is usually about 5 to 40 ° C, and the immersion time is usually about 2 to 120 seconds. The subsequent drying treatment is usually performed by using a hot-air dryer and / or a far-infrared heater. The drying temperature is usually 40 ~ 100 ℃. The processing time in the drying process is usually about 120 to 600 seconds.

In this way, a polarizing plate composed of a polyvinyl alcohol-based resin film in which iodine or a dichroic dye as a dichroic dye is adsorbed and aligned can be obtained.

<Protective film>

Next, the protective film was bonded to one side or both sides of the polarizer using the photocurable adhesive described above. Traditionally widely used three acetyl cellulose film as a protective film of the polarizing plate having a substantially 400g / m moisture permeability of about ^2/24 hours, but in the present invention, at least one face sheet bonded to the polarizer protective film A resin exhibiting lower moisture permeability than the triethyl cellulose is used, that is, a polyester resin, a polycarbonate resin, an acrylic resin, or an amorphous polyolefin-based resin.

The type of the polyester resin used for the protective film is not particularly limited, but in terms of mechanical properties, solvent resistance, scratch resistance, cost, etc., polyethylene terephthalate is particularly preferred. Polyethylene terephthalate refers to a resin composed of more than 80 mol% of repeating units composed of polyethylene terephthalate, and may also include structural units derived from other copolymerization components. Examples of other copolymerization components include isophthalic acid, p-β-hydroxyethoxybenzoic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, and bis (4-carboxybenzene Groups) dicarboxylic acids such as ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, and 1,4-dicarboxycyclohexane; Diol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol Diol component. These dicarboxylic acid components and / or diol components may be used in combination of two or more of them, if necessary. A hydroxycarboxylic acid such as p-hydroxybenzoic acid may be used together with the dicarboxylic acid component and / or the diol component. As other copolymerization components, a dicarboxylic acid component and / or a diol component having a amine bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used in a small amount.

As a method for producing a polyester resin, any of the following methods can be adopted: a so-called direct polymerization method in which terephthalic acid and ethylene glycol (further use of other dicarboxylic acids and / or other diols) are directly reacted with each other. A so-called transesterification reaction method in which a dimethyl terephthalate is subjected to a transesterification reaction with ethylene glycol (and further, if necessary, dimethyl esters of other dicarboxylic acids and / or other diols). Moreover, a polyester resin may contain a well-known additive as needed. Examples of the additives that can be contained include slip agents, anti-blocking agents, thermal stabilizers, antioxidants, antistatic agents, light resistance agents, and impact resistance improvers. However, since transparency is required as a protective film laminated on a polarizing film, the amount of these additives is preferably controlled to a minimum beforehand.

By forming the raw resin into a film shape and subjecting it to uniaxial stretching or biaxial stretching, a protective film made of a stretched polyester resin can be produced. By performing the stretching treatment, a film having high mechanical strength can be obtained. The method for producing the stretched polyester resin film is arbitrary and is not particularly limited, and examples thereof include a method in which an orientation-free thin film obtained by melting the raw material resin and extruding it in a sheet shape is obtained. The film was transversely stretched by a tenter at a temperature equal to or higher than the glass transition temperature, and then subjected to a heat fixing treatment.

In the case of using a polyester resin as a protective film, in order to obtain good adhesion, it is preferable to perform a corona treatment before applying the adhesive, or to use a polyester resin film having a surface with an easily-adhesive layer.

The polycarbonate resin used for the protective film is a polyester formed of carbonic acid and a diol or bisphenol. Among these, an aromatic polycarbonate having diphenylalkane in its molecular chain is preferably used because it is excellent in heat resistance, weather resistance, and acid resistance. Examples of such polycarbonates include 2,2-bis (4-hydroxyphenyl) propane (also known as bisphenol A), 2,2-bis (4-hydroxyphenyl) butane, and 1,1- Derived from bisphenols such as bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) isobutane, or 1,1-bis (4-hydroxyphenyl) ethane Polycarbonate.

As a method for producing a polycarbonate resin film, any method such as a casting film forming method and a melt extrusion method can be used. As an example of a specific manufacturing method, a method of dissolving a polycarbonate resin in a suitable organic solvent to prepare a polycarbonate resin solution, casting the polycarbonate resin solution on a metal support, and forming the mesh from the The metal support is peeled off, and the peeled net is dried by hot air to obtain a film.

The acrylic resin used for the protective film is not particularly limited, but it is generally a polymer of monomers mainly composed of methacrylate, and a copolymer obtained by copolymerizing a small amount of other comonomer components with it is preferred. As a methacrylate which becomes a main component of an acrylic resin, an alkyl methacrylate is usually preferably used, and methyl methacrylate is particularly preferably used. In addition, as a comonomer component, methyl acrylate and propylene are generally used. Ethyl enoate, butyl acrylate, 2-ethylhexyl acrylate, and the like. Furthermore, an aromatic vinyl compound such as styrene and / or a vinyl cyanide compound such as acrylonitrile may be used as a comonomer component.

As a method for producing the acrylic resin, any method such as ordinary block polymerization, suspension polymerization, and emulsion polymerization can be adopted. Among them, it is particularly preferable to use a block polymerization in which a water-soluble component is not present in the polymerization system. In addition, in order to obtain a suitable glass transition temperature or to obtain a viscosity showing moldability for molding into a suitable film, it is preferred to use a chain transfer agent during polymerization. The amount of the chain transfer agent may be appropriately determined depending on the type and composition of the monomer. In addition, the acrylic resin may contain a well-known additive as needed. Examples of well-known additives include slip agents, anti-blocking agents, thermal stabilizers, antioxidants, antistatic agents, light stabilizers, impact resistance improvers, and surfactants. However, since transparency is required as a protective film laminated on a polarizing film, the amount of these additives is preferably controlled to a minimum beforehand.

As a method for producing the acrylic resin film, any method such as a melt casting method, a melt extrusion method such as a T-die method and / or a blow molding method, or a calendering method can be used. Among them, a method for forming a film by melt-extruding a raw resin from a T-die, and contacting at least one side of the obtained film-like material with a roller or a tape is preferable from the viewpoint of obtaining a good film with a good surface texture. .

The acrylic resin may contain acrylic rubber particles as an impact modifier from the viewpoints of film-forming properties of the film and / or impact resistance of the film. The acrylic rubber particles referred to here are particles containing an elastic polymer mainly composed of acrylate as an essential component. Examples of the particles include particles having a single-layer structure substantially including only the elastic polymer, and particles having a multilayer structure having the elastic polymer as one layer. Examples of related elastic polymers include crosslinked elastic copolymers obtained by copolymerizing other vinyl monomers and crosslinkable monomers which are copolymerizable with alkyl acrylate as a main component. Examples of the alkyl acrylate which is a main component of the elastic polymer include alkyl acrylates having an alkyl group having a carbon number of about 1 to 8 such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. It is particularly preferable to use an acrylate having an alkyl group having four or more carbon atoms. Examples of other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methacrylates such as methyl methacrylate and benzene Aromatic vinyl compounds such as ethylene, vinyl cyanide compounds such as acrylonitrile, and the like. Examples of the crosslinkable monomer include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di (meth) acrylate and butanediol (Meth) acrylates of polyols such as di (meth) acrylates, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate, divinylbenzene, and the like.

Further, a protective film may be made of a laminate of a film made of an acrylic resin not containing rubber particles and a film made of an acrylic resin containing rubber particles.

When an acrylic resin is used as the protective film, when the composition of the present invention is used, good adhesiveness can be obtained even without corona treatment, but the adhesiveness of the adhesive is good or the adhesiveness is improved. For better purposes, it can also be applied before the adhesive is applied. Apply corona treatment.

Amorphous polyolefin resins used for protective films are usually The resin derived from the polymerization unit derived from a polycyclic cyclic olefin such as an olefin and / or a derivative thereof and a dibromethylene octahydronaphthalene is preferably a case where a double bond remains like a ring-opening polymer. A thermoplastic resin obtained by hydrogenating it. The amorphous polyolefin-based resin may be a copolymer of a cyclic olefin and a chain olefin, or a polar group may be introduced. Among them, the thermoplastic saturation drop The olefin resin is representative. Examples of commercially available amorphous polyolefin resins include "ARTON" by JSR, "ZEONEX" by ZEON, and "ZEONOR" by ZEON, and "APO" by Mitsui Chemicals, and "APEL", etc. When forming an amorphous polyolefin-based resin into a thin film, a known method such as a solvent casting method and a melt extrusion method is suitably used for the film formation.

In the case of using an amorphous polyolefin-based resin as a protective film, in order to obtain good adhesion, it is preferable to perform a corona treatment before applying the adhesive.

On a polarizing plate used on the visible side of a liquid crystal display device, anti-glare properties can be imparted to a protective film disposed on the visible side, that is, the side opposite to the liquid crystal cell. In this case, an anti-glare layer having surface unevenness is generally provided on the surface of the protective film that is configured as the visible side, that is, the surface opposite to the surface that is bonded to the polarizer. The anti-glare layer is generally formed by applying irregularities to an active energy ray-curable resin by an emboss method, or by blending an active energy ray-curable resin with a refractive index different from that of the active energy ray-curable resin. The fine particles are hardened to impart unevenness. In addition, when the protective film is made of acrylic resin, The laminated film is also effective in forming a protective film: a light-scattering layer obtained by blending fine particles having a refractive index different from that of an acrylic resin configured as a binder, and a transparent layer made of an acrylic resin not containing the fine particles Laminated film. In this case, a form may be adopted in which a laminated film composed of two layers of the light-scattering layer and the transparent layer is bonded to a polarizer on the light-scattering layer side, and / or the above-mentioned transparent layer The three-layer structured laminated film obtained by sandwiching both sides of the light scattering layer of the present invention is bonded to a polarizer on one transparent layer. Furthermore, even when an acrylic resin laminated film provided with anti-glare properties by including such a light-scattering layer is used as a protective film, it becomes the surface on the visible side, that is, the surface bonded to the polarizer. It is also effective to provide an anti-glare layer as described above on the opposite side of the surface to further improve the anti-glare performance.

As described above, particularly when an acrylic resin film is used as a protective film, the single-component epoxy resin containing no aromatic ring as shown in the aforementioned Patent Document 6 (Japanese Patent Laid-Open No. 2004-245925) Adhesiveness is not necessarily sufficient. However, the composition of the present invention generates a good adhesive force even when the acrylic resin film is used as a protective film. Therefore, this invention is especially useful when an acrylic resin film is used as a protective film.

In the present invention, the polyester resin, the polycarbonate resin, the acrylic resin, and the amorphous polyolefin-based resin described above are bonded to at least one surface of the polarizer with the photocurable adhesive described above. A protective film formed of a selected transparent resin film. Only when a protective film is laminated on one side of a polarizer, for example, a polarizer may be used. The other side is directly provided with an adhesive layer or the like for bonding to other members such as a liquid crystal cell.

On the other hand, when a protective film is bonded to both surfaces of a polarizer, each protective film may be the same kind of protective film, or may be a different kind of protective film. Specifically, for example, the following forms can be used: a form in which a polyester resin film is bonded to both sides of the polarizer as a protective film; a form in which a polycarbonate resin is bonded to both sides of the polarizer as a protective film; and both sides of the polarizer are bonded The form of acrylic resin as a protective film; the form of laminating an amorphous polyolefin resin as a protective film on both sides of a polarizer; the laminating of polyester resin, polycarbonate resin, acrylic resin, and amorphous on one side of a polarizer A transparent resin film selected from any of polyolefin resins is used as a protective film, and any one of polyester resin, polycarbonate resin, acrylic resin, and amorphous polyolefin resin is bonded to the other side of the polarizer. In addition, the transparent resin film is different from the above-mentioned protective film in the form of a protective film. Further, it is possible to adopt a form in which a transparent resin film selected from a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin-based resin is laminated on one side of the polarizer as a protective film and polarized On the other side of the sheet, a transparent resin film different from any one selected from a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin-based resin is bonded as a protective film. When the protective film is bonded to both sides of the polarizer, the two protective films may be bonded one by one to each side in stages, or the two sides may be bonded in one stage.

When a protective film is bonded to both sides of a polarizer, one of them is set to a polyester resin, a polycarbonate resin, In the case of other resin films having different acrylic resins and amorphous polyolefin-based resins, preferred examples of the other resins include cellulose-based resins. In addition, according to the present invention, a protective film made of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin-based resin bonded to one surface of the polarizer is provided with the photocurable adhesive described above. Next, the protective film laminated on the other surface of the polarizer may be bonded with another adhesive. For example, when a protective film made of a resin film having a relatively high moisture permeability, such as a cellulose resin film, is provided on one surface of the polarizer, a polymer film may be used on the bonding surface of the resin film having high moisture permeability. Adhesives other than epoxy based adhesives such as vinyl alcohol based adhesives. However, the photocurable adhesive of the present invention also has a high adhesive force to the cellulose-based resin film exemplified herein. Therefore, the use of the same adhesive on both sides of the polarizer makes the operation easy, which is advantageous.

Examples of the cellulose-based resin that can be used as the other protective film include partially or completely esterified cellulose, and examples thereof include cellulose acetate, propionate, butyrate, and mixed esters thereof. Wait. Specific examples include triethyl cellulose, diethyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like. Examples of commercially available films made of such cellulose ester resins include "Fujitac TD80", "Fujitac TD80UF", "Fujitac TD80UZ", and Konica Minolta Opto (stock) made by Fujifilm. "KC8UX2M" and "KC8UY". In addition, a cellulose-based resin film provided with an optical compensation function can also be used. Examples of related optical compensation films include: Films obtained with compounds having a poor adjustment function, films obtained by applying a compound having a phase difference adjusting function to the surface of a cellulose-based resin film, films obtained by uniaxially or biaxially stretching a cellulose-based resin film, etc. . Examples of commercially available cellulose-based optical compensation films include "Wide View Film WVBZ438" and "Wide View Film WVEA" by Fuji Film, and "KC4FR-1" by Konica Minolta Opto "And" KC4HR-1 ".

Examples of other resins different from polyester resins, polycarbonate resins, acrylic resins, and amorphous polyolefin-based resins and transparent resins having low moisture permeability that can be used as the other protective film include polyfluorinated resins. , Alicyclic polyfluorene imine resin, etc.

Regarding the protective film, before bonding to the polarizer, the bonding surface may be subjected to easy-adhesion treatment such as saponification treatment, corona treatment, primer treatment, and anchor coating treatment. In addition, the surface of the protective film on the side opposite to the side to which the polarizer is bonded may include various treatment layers such as a hard coat layer, an anti-reflection layer, and an anti-glare layer. The thickness of the protective film is usually in the range of about 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm.

[Manufacturing method of polarizing plate]

The polarizing plate of the present invention can be manufactured by a method including the steps of selecting a polarizer and a resin selected from a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polyolefin-based resin as described above. At least one of the bonding surfaces of the protective film formed of the transparent resin film is coated with the photo-curable adhesive as described above, and the polarizer and the protective film are bonded by the obtained adhesive layer. paste A curing step of curing the photocurable adhesive in a state where the polarizer and the protective film are bonded together with the adhesive layer.

<Adhesive coating step>

In the adhesive application step, the photocurable adhesive described above is applied to at least one of the bonding surfaces of the polarizer and the protective film. When a photocurable adhesive is directly applied to the surface of a polarizer or a protective film, the coating method is not particularly limited. For example, various coating methods such as a doctor blade, a wire rod, a die coater, a comma coater, and a gravure coater can be used. In addition, a method may be used in which a photocurable adhesive agent described above is cast between a polarizer and a protective film, and then pressurized with a roller or the like to uniformly squeeze and expand.

The gas ambient temperature in the adhesive coating step is preferably 15 to 30 ° C, and particularly preferably 20 to 25 ° C. In addition, the relative humidity of the coating gas environment is preferably 80% or less, more preferably 70% or less, even more preferably 30 to 70%, and particularly preferably 40 to 60%. By adjusting the temperature and humidity of the gas environment in the adhesive application step to the above-mentioned ranges, the adhesive force development speed and / or the final adhesive force can be stably good.

In addition, unlike the temperature of the gas environment, the temperature of the adhesive at the time of coating may be increased by heating or heating for the purpose of improving the coatability due to lowering of viscosity and / or improving the adhesive force described later. The heating or heating temperature at this time is preferably 80 ° C or lower, and more preferably in the range of 20 to 60 ° C. However, it is preferable that the adhesive coating film is exposed to 15 to 30 ° C. and 80% humidity from the viewpoint of making the adhesive force development speed and / or the final adhesive force good after the application to the film and the bonding step. The following gas environment.

<Laminating step>

After the photocurable adhesive is applied in this manner, it is supplied to the bonding step. In this bonding step, for example, when a photocurable adhesive is applied to the surface of the polarizer by the previous coating step, a protective film is laminated thereon, and the surface of the protective film is applied by the previous coating step. In the case of a photocurable adhesive, a polarizer is laminated there. When a photocurable adhesive is cast between the polarizer and the protective film, the polarizer and the protective film are stacked in this state. When a protective film is bonded to both surfaces of a polarizer, and when the photocurable adhesive of this invention is used on both surfaces, a protective film is laminated | stacked on both surfaces of a polarizer with a photocurable adhesive, respectively. . Further, in this state, in general, a protective film is laminated on both sides of the polarizer with a roller or the like (when the protective film is laminated on one side of the polarizer, or on both sides of the polarizer. In the case of this, it is clamped from the protective film side on both sides) and pressurized. Here, the material of the roller can be metal and / or rubber. The rollers arranged on both sides may be the same material or different materials.

<Hardening step>

As described above, the laminate in a state where the polarizer and the protective film are bonded with the uncured photocurable adhesive is then supplied to the curing step. In this hardening step, the photocurable adhesive is irradiated with an active energy ray to harden an adhesive layer containing an epoxy compound, a (meth) acrylate, a propylene oxide compound, and the like, thereby polarizing and protecting the polarizer. The film went on. When a protective film is bonded to one side of a polarizer, active energy rays may be irradiated from either the polarizer side or the protective film side. When a protective film is bonded to both sides of the polarizer, In a state where the protective film is bonded to both sides of the light sheet with respective photocurable adhesives, it is advantageous to irradiate the active energy rays from either side of the protective film and simultaneously cure both photocurable adhesives. However, when an ultraviolet absorber is blended into any of the protective films (for example, when a cellulose-based resin film containing a ultraviolet absorber is used as one of the protective films), the active energy ray is ultraviolet rays. In the case of ultraviolet rays, ultraviolet rays are usually irradiated from the other side of the protective film on which the ultraviolet absorber is not blended.

As the active energy rays, visible rays, ultraviolet rays, X-rays, electron rays, and the like can be used, but ultraviolet rays are generally preferred because they are easy to handle and have a sufficient curing rate. There is no particular limitation on the source of the active energy ray, but those with a light emission distribution below 400 nm can be used, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. , LED lights, etc.

The light irradiation intensity to the photocurable adhesive is a light irradiation intensity determined for each target composition, and although it is not particularly limited, for the activation of the polymerization initiator, the irradiation intensity in the effective wavelength range is preferably set to UV-B (ultraviolet light in the middle wavelength range of 280 to 320 nm) is set so as to be 1 to 3,000 mW / cm ² . When the irradiation intensity is 1 mW / cm ² or more, the reaction time is a moderate length. On the other hand, when the irradiation intensity is 3,000 mW / cm ² or less, the heat radiated from the lamp and the heat generated during the polymerization of the photocurable adhesive It can suppress yellowing of the photocurable adhesive and / or deterioration of the polarizer.

The light irradiation time to the photocurable adhesive is to control the light irradiation time of each hardened composition. Although it is not particularly limited, the cumulative light amount expressed by the product of the irradiation intensity and the irradiation time is preferably UV-B according to 10 ~ 5,000mJ / cm ² When the accumulated light amount is 10 mJ / cm ² or more, the generation of active centers derived from the polymerization initiator is sufficient, and then the curing of the agent layer is sufficiently progressed. On the other hand, when the accumulated light amount is 5,000 mJ / cm ² or less, the irradiation time is moderate. , Excellent productivity.

When the photocurable adhesive is hardened by irradiating an active energy ray, it is preferable to harden the polarizer such that the polarizing degree, transmittance, hue, and transparency of the protective film do not reduce the functions of the polarizing plate.

In the polarizing plate thus obtained, the thickness of the adhesive layer is usually 50 μm or less, preferably 20 μm or less, further preferably 10 μm or less, and particularly preferably 5 μm or less.

As a preferred method of increasing the adhesive force between the adhesive and the protective film of the present invention, after the polarizer is bonded to the protective film using the adhesive, the optical properties of the polarizer may not be damaged before the active energy rays are irradiated. Within the range of characteristics, a heating step is added. The heating conditions at this time are preferably within a range in which no shrinkage of the polarizer and / or deterioration of optical characteristics occurs. The preferable heating conditions are changed according to the molecular weight of the acrylic resin, but examples include 1 to 10 seconds at 60 ° C and 5 to 30 seconds at 40 ° C. After the heating, until the completion of the active energy ray irradiation, even if the temperature of the adhesive is cooled below 40 ° C, the effect of improving the adhesive force is not impaired.

In addition, as another preferable method for improving the adhesive force between the adhesive and the protective film of the present invention, the following method can be cited: even if it is not heated, that is, even at 20 to 25 ° C., And protection The length of the film to the manufacturing line where the active energy ray is irradiated becomes longer, thereby extending the time after the adhesive is brought into contact with the acrylic resin to about 60 seconds.

However, the adhesive of the present invention has a merit that the contact time between the adhesive and the acrylic resin-based protective film exhibits good adhesion even at a temperature of 20 to 25 ° C. for about 20 to 30 seconds.

[Optical member]

When a polarizing plate is used, an optical member obtained by laminating an optical layer showing an optical function other than a polarizing function on one side thereof may be produced. The optical layer laminated on the polarizing plate for the purpose of forming an optical member includes, for example, a reflective layer, a transflective reflective layer, a light scattering layer, a retardation plate, a light collecting plate, and a brightness-improving film for forming a liquid crystal display device. And other various parts. The reflective layer, the transflective reflective layer, and the light-scattering layer are used when forming an optical member composed of a reflective type, a transflective type, and / or a scattering type, or a dual-purpose polarizing plate. Components.

The reflective polarizing plate is used in a liquid crystal display device of a type that reflects incident light from a visible side and displays the light. A light source such as a backlight can be omitted, and the liquid crystal display device can be easily made thinner. In addition, the transflective polarizer is used in a liquid crystal display device of a type that is displayed in a reflective form in a bright place and is displayed using a light source such as a backlight in a dark place. Regarding the optical member as a reflective polarizing plate, for example, a foil and / or a vapor-deposited film made of a metal such as aluminum is attached to a protective film on a polarizer, thereby forming a reflective layer. Regarding the optical member that is a transflective polarizing plate, the reflective layer may be a translucent mirror, or a reflective plate containing pearl pigment or the like may be used to attach a reflective plate A polarizing plate is thus formed. On the other hand, regarding the optical member as the scattering-type polarizing plate, for example, various methods such as a method of applying a matting treatment to a protective film on the polarizing plate, a method of applying a resin containing fine particles, and a method of attaching a thin film containing fine particles , Thereby forming a fine uneven structure on the surface.

Further, the formation of the optical member as a polarizing plate for both reflection and scattering can be performed by, for example, providing a reflective layer reflecting the uneven structure on the fine uneven structure surface of the scattering-type polarizing plate. The reflective layer having a fine uneven structure has the advantages of scattering diffused incident light, preventing directivity and / or flicker, and suppressing uneven brightness. In addition, the resin layer and / or film containing fine particles also has the advantage that incident light and reflected light are scattered when the fine particle containing layer is transmitted, so that unevenness in light and dark can be more suppressed. The reflective layer reflecting the fine uneven structure on the surface can be formed by directly attaching a metal to the surface of the fine uneven structure by a method such as vacuum deposition, ion plating, sputtering, and / or plating. As the fine particles blended to form a fine uneven structure on the surface, for example, inorganic fine particles composed of silicon dioxide, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, and the like having an average particle diameter of 0.1 to 30 μm can be used. Organic fine particles composed of crosslinked or uncrosslinked polymers.

On the other hand, a retardation plate as the optical layer is used for the purpose of compensating the retardation of a liquid crystal cell and the like. Examples thereof include birefringent films composed of stretch films of various plastics, films obtained by aligning and fixing discotic liquid crystals and / or nematic liquid crystals, and forming the liquid crystal layer on a film substrate. And obtained Qualitative and so on. In this case, as a film substrate supporting the alignment liquid crystal layer, a cellulose-based film such as triacetylfluorene cellulose is preferably used.

Examples of plastics that form a birefringent film include polycarbonates, polyvinyl alcohols, polystyrenes, polyolefins such as polymethyl methacrylate, polypropylene, polyarylates, polyamides, and amorphous polymers. Olefin resin, etc. The stretched film may be a stretched film obtained by processing in a suitable manner such as uniaxial and / or biaxial. In addition, it may be a birefringent film in which the refractive index in the thickness direction of the film is controlled by applying a shrinkage force and / or a stretching force to the heat-shrinkable film. In addition, two or more retardation plates may be used in combination for the purpose of controlling optical characteristics such as wideband.

The light collecting plate is a component used for the purpose of controlling the light path, and can be formed in the form of a prism array sheet and / or a lens array sheet, or a dot-attached sheet.

The brightness-improving film is a component used for the purpose of improving the brightness in a liquid crystal display device or the like. As an example thereof, a plurality of films having mutually different refractive index anisotropies are laminated and the reflectance is increased. An anisotropically designed reflective linearly polarized separation sheet, a cholesteric liquid crystal polymer alignment film, and / or a circularly polarized separation sheet obtained by supporting an alignment liquid crystal layer on a film substrate, and the like.

As for the optical member, one or two or more layers selected according to the purpose of use from the polarizing plate and the reflective layer to the transflective reflective layer, the light scattering layer, the retardation plate, the condenser plate, and the brightness enhancement film can be selected. The optical layers are combined to make two or three layers On the stack. In this case, two or more optical layers such as a light scattering layer and / or a retardation plate, a light collecting plate, and / or a brightness enhancement film may be disposed. In addition, it is not limited to the arrangement of each optical layer.

Various optical layers forming the optical member are integrated with the polarizing plate by using an adhesive. Therefore, the adhesive used is not particularly limited as long as it is an adhesive that forms an adhesive layer well. It is preferable to use an adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoints of simplicity of the publishing industry and / or prevention of optical distortion. As the adhesive, an adhesive obtained by using an acrylic polymer and / or a silicone polymer, polyester, polyurethane, polyether, or the like as a base polymer can be used. Among them, it is preferable to select and use an adhesive, such as an acrylic adhesive, which is excellent in optical transparency, maintains moderate wettability and / or cohesion, and has excellent adhesion to a substrate. It further has weather resistance and / or heat resistance, and does not cause peeling problems such as floating and / or peeling under heating and / or humidifying conditions. In the acrylic adhesive, an alkyl ester of (meth) acrylic acid having an alkyl group having a carbon number of 20 or less such as methyl and / or ethyl or butyl, and (meth) acrylic and / The functional group-containing acrylic monomers such as hydroxyethyl (meth) acrylate and the like are polymerized by blending such that the glass transition temperature is preferably 25 ° C or lower, and more preferably 0 ° C or lower. An acrylic copolymer having a weight average molecular weight of 100,000 or more can be used as the base polymer.

The formation of the adhesive layer on the polarizing plate can be performed, for example, by dissolving or dispersing the adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a liquid having a solid concentration of 10 to 40% by weight. , Which is directly coated on a polarizing plate to form an adhesive layer Method, and / or a method of forming an adhesive layer on the isolation film in advance, and transferring it to a polarizing plate to form an adhesive layer. The thickness of the adhesive layer is determined depending on the adhesive force and the like, but a range of about 1 to 50 μm is appropriate.

In addition, the adhesive layer may also be blended as needed: fillers including glass fibers, glass beads, resin beads, metal powders and / or other inorganic powders, pigments and / or colorants, antioxidants, UV absorbers, etc. The ultraviolet absorber includes a salicylate-based compound and / or a benzophenone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, a nickel complex salt-based compound, and the like.

[Liquid crystal display device]

By disposing the above-mentioned optical members on one or both sides of the liquid crystal cell, a liquid crystal display device can be manufactured. The liquid crystal cell to be used is arbitrary. For example, an active matrix driving type liquid crystal cell represented by a thin film transistor type, a simple matrix driving type liquid crystal cell represented by a super twisted nematic type, and the like can be used. The liquid crystal cell forms a liquid crystal display device. The optical components provided on both sides of the liquid crystal cell may be the same optical component or different optical components.

[Example]

Hereinafter, the present invention will be described in more detail by showing examples and comparative examples, but the present invention is not limited to these examples. In the examples, the percentage indicating the amount used or the content ratio is based on weight unless otherwise specified. In addition,% of humidity indicates a relative humidity at 23 ° C. The parts are parts by weight.

In Examples and Comparative Examples, the photocurable adhesive composition Each component used in the preparation of the product is as follows, and is hereinafter represented by the compound name or each symbol (trade name itself or a part thereof).

(A) Component: Poly (meth) acrylate compound

HDDA: 1,6-hexanediol diacrylate, "LIGHT ACRYLATE 1,6HX-A" manufactured by Kyoeisha Chemical Co., Ltd.

(B) Ingredient: Polyglycidyl ether compound

HD-DGE: 1,6-hexanediol diglycidyl ether, "Denacol EX-212L" (0.4% total chlorine) manufactured by Nagase chemtex.

(C) component: a propylene oxide compound represented by the said Formula (1)

OXT-221: 3-ethyl-3-[(3-ethyloxypropane-3-yl) methoxymethyl] propylene oxide, "Aron Oxetane OXT-221" manufactured by Toa Kosei Co., Ltd.

(D) component: (meth) acrylic polymer

BR-87: PMMA polymer containing 60% by weight or more of methyl methacrylate as a structural monomer unit, Mw 25,000, acid value 10.5 mgKOH / g, "DIANAL BR-87" manufactured by Mitsubishi Rayon Corporation ".

Polymer A: A polymer obtained in Production Example 1 described later.

(E) component: cationic photopolymerization initiator

CPI-110P: Triarylsulfonium hexafluorophosphate (100% active ingredient), "CPI-110P" manufactured by San-Apro.

(F) Ingredient: Alicyclic epoxy compound

CEL-2021: an alicyclic epoxy compound represented by the aforementioned formula (3), and "Celloxide 2021P" manufactured by Daicel Chemical Industries, Ltd.

(G) Ingredient: Photo radical polymerization initiator

Irg-184: 1-hydroxy-cyclohexyl-phenyl-ketone, "" Irgacure 184 ".

(H) component: a propylene oxide compound represented by the said Formula (4)

OXT-101: 3-ethyl-3-hydroxymethyl propylene oxide, "Aron Oxetane OXT-101" manufactured by Toa Kosei Corporation.

(I) Ingredient: Leveling agent

SH-28: Toray Dow Corning's polysiloxane-based leveling agent "DOW CORNING TORAY SH 28 PAINT ADDITIVE".

[Manufacturing example 1]

The jacket temperature of the 1000-mL pressure stirred tank reactor equipped with an oil jacket was maintained at 181 ° C. Next, while maintaining the pressure in the reactor constant, starting from isobutyl acrylate (45 parts), 2-ethylhexyl acrylate (45 parts), methyl methacrylate (10 parts), and isocyanate as polymerization solvents, A monomer mixture consisting of propanol (9 parts), methyl ethyl ketone (9 parts), and tertiary butyl peroxide (0.25 parts) as a polymerization initiator at a constant feed rate (48 g / min, residence time: 12 Minutes) is continuously supplied from the raw material tank to the reactor, and the reaction liquid corresponding to the supply amount of the monomer mixture is continuously extracted from the outlet. Immediately after the start of the reaction, after the reaction temperature was temporarily reduced, it was found that the temperature increased due to the heat of polymerization, but the internal temperature of the reactor was maintained at 183 to 185 ° C by controlling the temperature of the oil jacket. The time point 36 minutes after the reactor internal temperature stabilized was taken as the starting point of the reaction liquid collection, and the reaction was continued for 25 minutes thereafter. As a result, 1.2 kg of the monomer mixed liquid was supplied and 1.2 kg of the reaction liquid was recovered. Thereafter, the reaction solution was introduced into a thin-film evaporator to separate volatile components such as unreacted monomers, thereby removing volatile components such as unreacted monomers, to obtain a polymer "Polymer A". GPC measurement was performed, and the result was a polystyrene-equivalent number. The weight average molecular weight (Mn) is 2,500, the weight average molecular weight (Mw) is 7,500, and the viscosity at 25 ° C is 20,000 mPa. s.

○ Example 1 to Example 4, Comparative Example 1 to Comparative Example 8

[Preparation of Photocurable Adhesive Composition]

The respective components shown in Tables 1 to 3 were blended at respective ratios, and stirred and mixed according to a conventional method to prepare a photocurable adhesive composition.

The viscosity at 25 ° C. of the obtained composition was measured with an E-type viscometer manufactured by Toki Sangyo Co., Ltd.

[Production of polarizing plate]

Here, as the protective film, the following two films are used.

Stretch drop Ethylene resin film: 70 μm thick, trade name "ZEONOR film", made by Japan Zeon Corporation. This film is subjected to a corona discharge treatment, and is then supplied to a lamination with a polarizer.

Acrylic resin film: 80 μm thick, trade name “Technolloy S001”, manufactured by Sumitomo Chemical Co., Ltd. This film was also subjected to a corona discharge treatment, and was then supplied to a bonding with a polarizer.

In the above stretch drop The composition prepared on the corona discharge treated surface of the olefin resin film was coated with a bar coater to a thickness of 3 μm. This coated surface was bonded to a polarizer obtained by iodine adsorption and alignment with polyvinyl alcohol using a manual pressure roller.

Next, on the corona discharge treated surface of the acrylic resin film, the composition prepared above was applied with a bar coater to a thickness of 3 μm. Thereafter, a liquid pressure composition was used to reduce the pressure with a manual pressure roller. The polarizing plate in which the olefin resin film is integrated is bonded to the coating surface of the acrylic resin film.

Using a UV irradiation device with a conveyor belt (the lamp uses high-pressure mercury lamps made by EYE Graphics), the polarizers obtained by laminating the protective film on both sides are The surface of the olefin resin film was irradiated with ultraviolet rays at a cumulative light amount of 250 mJ / cm ² (UV-B), and the adhesive composition was cured.

This experiment was performed under the conditions of 23 ° C and 50% relative humidity.

In addition, in the experiments of Tables 1 to 3, after the adhesive composition was applied to the acrylic resin film, the time until the irradiation with ultraviolet rays was uniformly in the range of 20 to 25 seconds.

[Evaluation test]

Regarding the polarizing plate after ultraviolet irradiation, the following methods were used to evaluate the adhesion force immediately after the ultraviolet irradiation, the cutting machine insertion adhesion force, the bending and peeling adhesion force of the polarizers at room temperature (before the moist heat resistance test), and the moist heat resistance The results are shown in Tables 1 to 3 after the test, the bending and peeling adhesion force of the polarizer after the moisture and heat resistance test, and the cold-heat cycle test.

<Adhesion immediately after ultraviolet irradiation>

Fifteen seconds after the ultraviolet light was irradiated, the acrylic resin film and the polarizer were peeled off by hand, and it was judged according to the following three levels based on the degree of hardening at this time and the adhesive force.

(Circle): It is hardened sufficiently, and it has sufficient adhesive force which does not peel in the film conveyance process in manufacture.

△: Although hardened, the adhesion was slightly weak.

X: Insufficient hardening and easy generation of air bubbles during the film transport step, or hardening, but the adhesive force is quite weak, and it is easy to peel off during the film transport step.

<Cutting Machine Insertion Force>

For a polarizing plate that has been passed for more than two days after UV irradiation, the blade of the cutting blade is inserted obliquely from above the acrylic resin film, and it is determined according to the following four levels based on the appearance and force at this time.

：: The blade cannot enter, or the resistance is quite strong even when the blade enters, and the acrylic resin film immediately breaks.

○: The blade entered, but the resistance was strong, and when the peeling was intended to be expanded, the acrylic resin film was broken.

(Triangle | delta): Resistance is felt even if a blade enters, but peeling can be enlarged.

×: The blade enters, and the resistance decreases as the blade advances with a little force at the interface.

<Flexible peeling adhesion force of polarizers at room temperature (before humidity and heat test)>

The polarizing plate that had been irradiated with ultraviolet rays for 2 days or more was cut into a strip shape having a width of 1 inch and a length of 15 cm, and the acrylic resin film side was attached to the glass plate with an adhesive tape. Next, move the upper side to the lower side. The polarizer film of the olefin-based resin film was peeled, and a 180 ° peel test was performed at a tensile speed of 300 mm / min. The adhesive force (N / inch) is described in the table.

<Damp and heat resistance test>

The polarizing plate that had been irradiated with ultraviolet rays for more than 2 days was cut into a width of 4 cm and a length of 6 cm, and was left in a high-temperature and high-humidity environment at 60 ° C and a relative humidity of 90% for 500 hours. The polarizing plate after the moisture and heat resistance test was visually observed for peeling and discoloration, and was judged according to the following three levels.

○: No peeling or discoloration was observed.

Δ: Peeling and discoloration were slightly observed.

×: Peeling and discoloration were found.

<Bending and Peel Adhesion of Polarizer After Moisture Resistance Test>

The polarizing plate that had been irradiated with ultraviolet rays for 2 days or more was cut into a strip shape having a width of 1 inch and a length of 15 cm, and the acrylic resin film side was attached to the glass plate with an adhesive tape. This was left in a high-temperature, high-humidity environment at 60 ° C. and a relative humidity of 90% for 500 hours, and then taken out at an environment of 23 ° C. and a relative humidity of 50%, and the adhesive force after 5 minutes after removal was measured. Regarding the measurement, The polarizer film of the olefin-based resin film was peeled and peeled at a stretching speed of 300 mm / minute at 180 °. The results were shown in (N / inch) in the table.

<Cold and hot cycle test>

The polarizing plate that had been irradiated with ultraviolet rays for more than 2 days was repeatedly subjected to a cycle of 300 times at -35 ° C for 60 minutes and then at + 70 ° C for 60 minutes, thereby performing a cold-heat shock cycle test. The polarizing plate after the cold-heat cycle test was visually observed, and it was judged by the following three levels.

○: No appearance defect was found.

(Triangle | delta): The external appearance was found slightly.

×: A defective appearance was found.

The composition of Example 1 is low in viscosity and excellent in coating properties. Adhesive force immediately after the end of ultraviolet irradiation, adhesive force of a cutting machine, bending and peeling adhesive force of a polarizer of a normal-temperature storage product, moist heat resistance test, moist heat resistance test The results of the subsequent bending and peeling adhesion of the polarizer and the results of the cold-heat cycle test were all good. In particular, the polarizing plate before and after the moist heat resistance test was excellent in peeling adhesion.

The composition of Example 2 and Example 3 is a composition obtained by reducing the (B) component and the (C) component and adding the (F) component and (H) component to the composition of Example 1, and cutting The inserting force of the machine is particularly excellent. Regarding the bending and peeling adhesive force of the polarizer, Example 2 containing the component (B) of 19% has a stronger adhesive force than Example 3 having a content of the component (B) of 11%.

Regarding the composition of Example 2 in which the (D1) component and the (D2) component are used in combination, an example in which the polymer (A) as the (D) component does not include the (D1) component and only the polymer (A) as the (D2) component is included. 4 Comparatively speaking, the cutting machine insertion adhesion force and the bending and peeling adhesion force of the polarizer before and after the moist heat resistance test are superior. That is, the adhesiveness using the (D1) component and the (D2) component as the (D) component is excellent. However, the composition of Example 4 has a lower viscosity than the composition of Example 2.

On the other hand, regarding the compositions of Comparative Examples 1 to 3 which do not contain the (D) component, at least one of the adhesion force immediately after the end of the ultraviolet irradiation, the cutter insertion adhesion force, and the cold-heat cycle test were defective. .

In addition, regarding the composition of Comparative Example 4 not containing the component (B), the polarizing plate had a poor peeling adhesion force before and after the moist heat test, and the composition of Comparative Example 5 having the component (B) exceeding the upper limit of 35% by weight was in Immediately after the ultraviolet irradiation, the adhesion was poor. Regarding the composition of Comparative Example 5, the results of the cutter insertion adhesion force and the cold-heat cycle test were also insufficient.

Regarding the composition of Comparative Example 6 in which the component (A) exceeded the upper limit of 50% by weight, the cutting force of the cutter was poor, and the bonding force immediately after the end of ultraviolet irradiation and the polarizing plate peeling and bonding force were insufficient. Regarding the composition of Comparative Example 7 in which the component (A) had a lower limit of 15% by weight, the adhesive force immediately after the end of ultraviolet irradiation was insufficient even though it contained many (F) components excellent in hardenability. Furthermore, the polarizing plate after the moist heat resistance test had a poor peeling adhesion force.

Regarding the composition of Comparative Example 8 not containing the component (C), the polarizing sheet bending peeling adhesion force of the room-temperature storage product was poor, and the adhesion force and the cutter insertion adhesion force immediately after the end of ultraviolet irradiation were insufficient.

○ Example 5

In Example 3, the time from the application of the adhesive composition to the acrylic resin film until the ultraviolet ray was irradiated was set to 60 seconds for a long time, and all experiments were performed in the same manner as in Example 3.

As a result, both the polarizer and the acrylic resin film were firmly adhered before and after the moist heat resistance test, and they could not be peeled off, and the peeling adhesion force could not be measured. In this way, the time for which the acrylic resin film is eroded by the adhesive is increased, and the adhesive force can be greatly improved.

In addition, the results of the adhesion force immediately after the ultraviolet irradiation, the cutter insertion adhesion force, the moist-heat resistance test, and the cold-heat cycle test were similar to those of Example 3.

[Industrial availability]

The photocurable adhesive composition of the present invention has a low viscosity and is easy to apply into a thin film. The adhesive force immediately after the end of light irradiation and the final adhesive force are excellent. The adhesive force after the end of the moist heat resistance test is also excellent. The polarizing plate is also excellent in durability, and thus can be preferably used for manufacturing a polarizing plate.

Claims (19)

A photocurable adhesive composition is an adhesive composition for adhering a protective film to a polarizer. The protective film is selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and an amorphous polymer. The polar resin is composed of a transparent resin film in the group of olefin resins. The polarizer is composed of a polyvinyl alcohol resin film that is uniaxially stretched and adsorbs and aligns with a dichroic pigment. The composition is characterized in that: (A) a poly (meth) acrylate having a polyhydric alcohol having 2 to 15 carbons; (B) a polyglycidyl ether having a polyhydric alcohol having 2 to 10 carbons, wherein the polyhydric alcohol is in addition to alkylene oxide units (C) a propylene oxide compound represented by the following formula (1); (D) a polymer using alkyl (meth) acrylate as an essential structural monomer unit; (E) a cationic photopolymerization initiator; and the content ratio of the components (A) to (E) in the composition is: ( A) ingredients: 15-50% by weight, (B) ingredients: 2-35% by weight, (C) ingredients: 2-50% by weight, (D) ingredients: 1-30% by weight, (E) ingredients: 0.5 ~ 10% by weight. The photocurable adhesive composition according to claim 1, wherein the component (A) is a di (meth) acrylate having a diol having 2 to 10 carbon atoms. For example, the photocurable adhesive composition according to claim 1, wherein the component (B) is a diglycidyl ether having a diol having 2 to 10 carbon atoms, wherein the diol has a repeating number of 3 or more of alkylene oxide units. Other than polyether diols. For example, the photocurable adhesive composition of claim 1, wherein the content ratios of (A) component, (B) component, (C) component, (D) component, and (E) component in the composition are 20 ~ 45 wt%, 5 to 30 wt%, 5 to 35 wt%, 5 to 25 wt%, and 1 to 6 wt%. For example, the photocurable adhesive composition of claim 1, wherein the component (D) includes a polymer containing an alkyl (meth) acrylate containing an alkyl group having 1 to 10 carbons as a structural monomer unit, And the weight average molecular weight is 1,000 ~ 500,000. The photocurable adhesive composition according to claim 5, wherein the component (D) contains (D1): a polymer containing 60% by weight or more of methyl methacrylate as a structural monomer unit, and the weight average The molecular weight is 1,000 ~ 200,000. The photocurable adhesive composition according to claim 5, wherein the component (D) contains (D2): a polymer containing 60% by weight or more of an alkyl acrylate containing an alkyl group having 1 to 10 carbon atoms Structural monomer unit, and the weight average molecular weight is 1,000 ~ 200,000. The photocurable adhesive composition according to claim 7, wherein the component (D2) contains a polymer which is a polymer obtained by polymerization at 160 to 350 ° C, and the polymer contains 60% by weight or more of carbon 1 to 10 alkyl acrylates are used as structural monomer units, and the weight average molecular weight is 1,000 to 20,000. For example, the photocurable adhesive composition of claim 6, wherein the (D) component is a combination of the (D1) component and the (D2) component, and the (D2) component contains 60% by weight or more of a carbon number of 1 to 10 An alkyl acrylate is a polymer having a structural monomer unit and an Mw of 1,000 to 200,000. The photocurable adhesive composition according to claim 1, further comprising at least two alicyclic rings represented by the following formula (2) in the molecule at a content ratio of 1 to 25% by weight in the composition. An epoxy compound of an oxygen group as the (F) component, The photocurable adhesive composition according to claim 10, wherein the component (F) is an epoxy compound represented by the following formula (3): The photocurable adhesive composition according to claim 1, further comprising (G) a photoradical polymerization initiator in a proportion of 10% by weight or less in the composition. For example, the photocurable adhesive composition of claim 1 further includes a propylene oxide compound represented by the following formula (4) as a component (H) in a content ratio of 1 to 10% by weight in the composition. The photocurable adhesive composition according to claim 1, further comprising 0.01 to 0.5% by weight of a leveling agent as a component (I) in the composition. A polarizing plate is a polarizing plate obtained by bonding a protective film to a polarizer with an adhesive. The protective film is selected from the group consisting of polyester resin, polycarbonate resin, acrylic resin, and amorphous polyolefin. The resin group consists of a transparent resin film. The polarizer is composed of a polyvinyl alcohol resin film that is uniaxially stretched and adsorbs and aligns with a dichroic pigment. It is characterized in that the adhesive is composed of The photocurable adhesive composition of any one of items 1 to 14 is formed. A method for manufacturing a polarizing plate, which is a method for manufacturing a polarizing plate by bonding a protective film to a polarizer with an adhesive, the protective film is selected from the group consisting of a polyester resin, a polycarbonate resin, an acrylic resin, and The polarizing film is composed of a transparent resin film in the group of amorphous polyolefin resins. The polarizer is composed of a polyvinyl alcohol resin film that is uniaxially stretched and has an orientation of a dichroic dye. The following steps: an adhesive coating step, applying a photocurable adhesive composition according to any one of claims 1 to 14 to at least one of the bonding surfaces of the polarizer and the protective film; the bonding step, The polarizer is bonded to the protective film through the obtained adhesive layer; and the curing step is the photocurable adhesive in a state where the polarizer and the protective film are bonded through the adhesive layer. The composition is hardened. An optical member characterized in that another optical layer is laminated on a polarizing plate as in claim 15. The optical member according to claim 17, wherein the other optical layer includes a retardation plate. A liquid crystal display device is characterized by arranging an optical member as claimed in claim 17 on one or both sides of a liquid crystal cell.