JP2011154267A - Polarizing plate with adhesive layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate with an adhesive layer, including the adhesive layer having excellent adhesiveness to a protective film made of a polypropylene resin. <P>SOLUTION: A polypropylene resin film 14 is adhered to a polarizing film 10 via an adhesive made of a resin composition containing an epoxy compound to be cured by irradiation with an active energy ray and an adhesive layer 15 is provided on a surface opposite to an adhesion surface of the polypropylene resin film 14 to the polarizing film 10. The adhesive layer 15 is formed from an adhesive composition containing an acrylic resin (A) formed by radically polymerizing a monomer composition containing 80 to 94 wt.% (meth)acrylate monomer (A-1), 0.1 to 5 wt.% polar functional group-containing (meth)acrylic monomer (A-2) and 5 to 15 wt.% aromatic ring-containing monomer (A-3) in the presence of a polymerization initiator and having ≤0°C glass transition temperature and an adhesive composition (B) containing a crosslinking agent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polarizing plate in which a polypropylene resin film is bonded to at least one surface of a polarizing film made of a polyvinyl alcohol resin, and a specific pressure-sensitive adhesive layer is formed on the other surface of the polypropylene resin film.

  The polarizing plate is useful as a constituent member of a liquid crystal display device, and the demand for the polarizing plate is rapidly increasing with the spread of the liquid crystal display device. With the application of a liquid crystal display device to a large-sized television or the like, the polarizing plate is also required to be thinner and cheaper while maintaining or improving its performance.

  Traditionally, a polarizing plate has a structure in which a transparent protective film is bonded to at least one side, usually both sides, of a polarizing film made of a polyvinyl alcohol resin on which a dichroic dye is adsorbed and oriented. Conventionally, a film of a cellulose acetate resin typified by triacetyl cellulose has been frequently used as a protective film for a polarizing plate, and the thickness thereof is usually about 40 to 120 μm. For bonding such a cellulose acetate resin film to a polarizing film, an adhesive composed of an aqueous solution of a polyvinyl alcohol resin is often used. However, when a polarizing film made of polyvinyl alcohol resin is laminated with a protective film made of cellulose acetate resin via an adhesive made of an aqueous solution of polyvinyl alcohol resin, the polarizing plate is used for a long time under wet heat conditions. Further, there are problems that the polarization performance is deteriorated and the protective film is peeled off from the polarizing film.

  Furthermore, when the protective film is composed of a cellulose acetate resin, the thickness is required to be at least about 40 μm as described above. There was a handling problem such as the film tearing and breaking. Moreover, since the cellulose acetate resin is formed by a solvent casting method, there is a limit to the cost reduction.

  Therefore, there is an attempt to configure at least one of the protective films bonded to both surfaces of the polarizing film with a resin other than the cellulose acetate resin. For example, in JP-A-8-43812 (Patent Document 1), in a polarizing plate in which protective films are laminated on both sides of a polarizing film, at least one of the protective films is a thermoplastic having a function of a retardation film. It is described that it is composed of a norbornene resin. Japanese Patent Laid-Open No. 2002-174729 (Patent Document 2) includes an amorphous polyolefin resin on one surface of a polarizing film made of a polyvinyl alcohol resin on which iodine or a dichroic dye is adsorbed and oriented. A polarizing plate is described in which a protective film is bonded and a protective film made of a resin different from an amorphous polyolefin-based resin, such as a cellulose acetate-based resin, is bonded to the other surface of the polarizing film.

  Amorphous polyolefin-based resins including norbornene-based resins are also called cycloolefin-based resins, and are relatively excellent in heat resistance and moisture resistance, excellent in transparency, and stretched uniaxially or biaxially. Since an appropriate retardation value is given, it is widely used for reasons such as being suitable for viewing angle compensation and retardation compensation of liquid crystal cells.

  By the way, the amorphous cyclic polyolefin-based resin (cycloolefin-based resin) is a recently put into practical use and is expensive. Recently, with the widespread use of liquid crystal displays, a protective film that is cheaper than a cyclic polyolefin resin film is required. Therefore, JP 2007-334295 A (Patent Document 3) describes a polarizing plate in which a protective film is bonded to both surfaces of a polarizing film, and at least one of the protective films is made of a polypropylene resin. Yes. Since a polypropylene resin film is also available at a low cost, a polarizing plate using a polypropylene resin as a protective film is advantageous in terms of cost.

  Further, studies have been made to use a non-aqueous adhesive instead of the aqueous solution of the polyvinyl alcohol resin that has been traditionally used for joining the polarizing film and the protective film. For example, in JP-A-2004-245925 (Patent Document 4) and JP-A-2008-257199 (Patent Document 5), an adhesive mainly composed of a specific epoxy compound is used and irradiated with active energy rays. A technique for curing an adhesive and bonding a polarizing film and a protective film has been proposed.

JP-A-8-43812 JP 2002-174729 A JP 2007-334295 A JP 2004-245925 A JP 2008-257199 A

  For the purpose of further reducing the cost of the polarizing plate, the present inventors bonded a polypropylene resin film to one side of the polarizing film via an adhesive and the other side of the polarizing film via an adhesive. Then, the structure which bonds the transparent resin film which has a glare-proof function was examined. In this configuration, a pressure-sensitive adhesive layer is provided on the outside of the polypropylene-based resin film, and is bonded to the liquid crystal cell via the pressure-sensitive adhesive layer. In this case, it has become clear that the polypropylene resin film has poor adhesion to the pressure-sensitive adhesive layer, and is inferior to that made of a cyclic polyolefin resin.

  Thus, when adhesiveness with a polypropylene-type resin film worsens, when chip-cutting a polarizing plate with an adhesive layer into a product shape to be bonded to a liquid crystal cell, the adhesive layer partially falls off, and handling properties are improved. In some cases, it becomes worse, or when it is attached to a liquid crystal cell and then exposed to a high temperature environment, peeling occurs between the adhesive layer and the like. In addition, when bonding with a liquid crystal cell, the rework (peeling, rebonding) property calculated | required within the assembly process of a liquid crystal panel may not be satisfy | filled.

  Therefore, as a result of further research to improve the adhesiveness between the pressure-sensitive adhesive layer and a protective film (polypropylene-based resin film) made of a polypropylene resin, by optimizing the pressure-sensitive adhesive composition, It has been found that the adhesiveness of the polypropylene resin film can be increased, and the present invention has been completed.

  Therefore, the objective of this invention is providing the polarizing plate with an adhesive layer provided with the adhesive layer excellent in adhesiveness with the protective film which consists of polypropylene resin.

According to the present invention, a polypropylene resin film is bonded to a polarizing film via an adhesive comprising a resin composition containing an epoxy compound that is cured by irradiation with active energy rays, and the polypropylene resin film A pressure-sensitive adhesive layer laminated on the surface opposite to the adhesive surface to the polarizing film,
(A) (A-1) The following formula (I):

(In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a C 1-14 alkyl group which may be substituted with a C 1-10 alkoxy group.)
80 to 94% by weight of (meth) acrylic acid ester monomer represented by
(A-2) 0.1 to 5% by weight of (meth) acrylic monomer having a polar functional group;
(A-3) 5 to 15% by weight of a monomer having one olefinic double bond and at least one aromatic ring in the molecule;
An acrylic resin having a glass transition temperature of 0 ° C. or lower, obtained by radical polymerization of a monomer composition containing
(B) The polarizing plate with an adhesive layer currently formed from the adhesive composition containing a crosslinking agent is provided.

  The monomer (A-3) having one olefinic double bond and at least one aromatic ring in the molecule is represented by the following formula (II):

(In the formula, R ₃ represents a hydrogen atom or a methyl group, n is an integer of 1 to 8, and R ₄ represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group.)
It is preferable that it is an aromatic ring containing (meth) methacrylic acid ester monomer shown by these.

  The pressure-sensitive adhesive composition may further contain (C) an ionic compound having an organic cation. The ionic compound having the organic cation (C) preferably has a melting point in the range of 30 to 80 ° C.

  It is preferable that the polypropylene resin is substantially composed of a homopolymer of propylene or a copolymer of propylene and ethylene containing 10% by weight or less of ethylene units.

The polypropylene resin film preferably has an in-plane retardation value (R ₀ ) of 30 nm or less. Moreover, it is preferable that a haze value is 0.5% or less.

  The polarizing plate with the pressure-sensitive adhesive layer of the present invention has excellent adhesion between the protective film made of polypropylene resin and the pressure-sensitive adhesive layer, and the protective film is used during the manufacture of liquid crystal panels and liquid crystal display devices and when they are used. Peeling between the adhesive layer and the pressure-sensitive adhesive layer is less likely to occur, thereby improving productivity and reducing defective products. In addition, the polarizing plate with the pressure-sensitive adhesive layer of the present invention is pasted on the surface of the glass substrate after peeling even if the pressure-sensitive adhesive layer is peeled off from the glass substrate when there is some inconvenience after being bonded to the glass substrate. There is little generation | occurrence | production of the remainder etc., it can use again as a glass substrate, and is excellent in rework property. In particular, when an ionic compound is blended in the pressure-sensitive adhesive layer, antistatic properties are imparted, and static electricity when the release film (separator) is peeled off and bonded to the liquid crystal cell can be effectively prevented.

It is a cross-sectional schematic diagram which shows a preferable example of the polarizing plate with an adhesive layer which concerns on this invention.

[Polarizing plate with adhesive layer]
Hereinafter, an embodiment is shown and a polarizing plate with an adhesive layer of the present invention is explained in detail. FIG. 1 is a schematic cross-sectional view showing a preferred example of a polarizing plate with an adhesive layer according to the present invention. As shown in FIG. 1, in the present invention, a transparent resin film 13 is bonded to a polarizing film 10 via adhesive layers 11 and 12 made of a resin composition containing an epoxy compound that is cured by irradiation with active energy rays. A protective film 14 made of polypropylene resin is adhered, and a pressure-sensitive adhesive layer 15 is formed on the surface of the protective film 14 made of polypropylene resin opposite to the surface to be bonded to the polarizing film 10. Hereinafter, each layer will be described in detail.

<Polarizing film>
The polarizing film 10 is usually a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and a polyvinyl film on which the dichroic dye is adsorbed. It is manufactured through a step of treating an alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

  The polyvinyl alcohol-based resin can be produced by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The film thickness of the polyvinyl alcohol-based resin original film is, for example, about 10 to 150 μm, preferably about 10 to 100 μm.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, uniaxial stretching can also be performed in a plurality of stages shown here. For uniaxial stretching, a method of stretching uniaxially between rolls having different peripheral speeds, a method of stretching uniaxially using a hot roll, or the like can be adopted. Uniaxial stretching may be performed by dry stretching in which stretching is performed in the air, or may be performed by wet stretching in which a polyvinyl alcohol-based resin film is stretched using a solvent such as water. The draw ratio is usually about 3 to 8 times.

  The polyvinyl alcohol resin film can be dyed with a dichroic dye by, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. In addition, it is preferable to perform the process which a polyvinyl alcohol-type resin film swells by immersing in water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. It is. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous dye solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic organic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid treatment after dyeing with the dichroic dye can be performed by a method of immersing the dyed polyvinyl alcohol resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by a method of immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. The immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain a polarizing film. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying treatment, the moisture content in the polarizing film is reduced to a practical level. The moisture content is usually about 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the polarizing film loses its flexibility, and may be damaged or broken after drying. On the other hand, if the moisture content exceeds 20% by weight, the thermal stability tends to be insufficient.

  As described above, a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol-based resin film can be produced. The resulting polarizing film can have a thickness of, for example, about 5 to 40 μm.

<Polypropylene resin film>
(Polypropylene resin)
In the present invention, the polypropylene resin constituting the resin film to be bonded to the polarizing film may be a resin consisting essentially of a propylene homopolymer, or a copolymer of propylene and another copolymerizable comonomer. The resin which consists of may be sufficient. The homopolymer of propylene is advantageous in that the film rigidity and yield strength can be further increased because the degree of crystallinity is higher than the copolymer of propylene and other copolymerizable comonomers. . Therefore, the handling property in the manufacturing process of the stretched film of the present invention can be further improved by using a resin substantially consisting of a homopolymer of propylene as the polypropylene resin.

  Here, the “substantially propylene homopolymer” is not only a polymer having a propylene unit content of 100% by weight, but also about 0.6% by weight or less for the purpose of improving the productivity of an unstretched film. Propylene / ethylene copolymers containing ethylene units in the range are also included.

  When the polypropylene resin constituting the polypropylene resin film (film 15 in FIG. 1) used in the present invention is a copolymer of propylene and another copolymerizable comonomer, the polypropylene resin is mainly composed of propylene. It is preferable that one or two or more comonomers copolymerizable therewith are copolymerized in a small amount. Specifically, the polypropylene resin comprising such a copolymer is a resin containing a comonomer unit in a range of, for example, 20% by weight or less, preferably 10% by weight or less, more preferably 7% by weight or less. be able to. The comonomer unit content in the copolymer is at least more than 0.6% by weight, preferably 1% by weight or more, more preferably 3% by weight or more. By setting the content of the comonomer unit to 1% by weight or more, processability and transparency can be significantly improved. On the other hand, when the content of the comonomer unit exceeds 20% by weight, the melting point of the polypropylene resin is lowered and the heat resistance tends to be lowered. In addition, when setting it as the copolymer of 2 or more types of comonomer, and propylene, it is preferable that the total content of the unit derived from all the comonomer contained in the copolymer is the said range.

The comonomer copolymerized with propylene can be, for example, ethylene or an α-olefin having 4 to 20 carbon atoms. Specific examples of the α-olefin in this case include the following. 1-butene, 2-methyl-1-propene (above C ₄ ); 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene (above C ₅ ); 1-hexene, 2-ethyl- 1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene ₆ ); 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3-ethyl-1-butene (above C ₇ ); 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl- 1-pentene, 2-propyl-1-pentene, 2,3 Diethyl-1-butene (or C _8); 1-nonene (C _9); 1-decene (C _10); 1-undecene (C _11); 1-dodecene (C _12); 1-tridecene (C ₁₃₎ 1-tetradecene (C ₁₄ ); 1-pentadecene (C ₁₅ ); 1-hexadecene (C ₁₆ ); 1-heptadecene (C ₁₇ ); 1-octadecene (C ₁₈ ); 1-nonadecene (C ₁₉ ) and the like.

  Preferred among the α-olefins are α-olefins having 4 to 12 carbon atoms, specifically 1-butene, 2-methyl-1-propene; 1-pentene, 2-methyl-1- Butene, 3-methyl-1-butene; 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4- Methyl-1-pentene, 3,3-dimethyl-1-butene; 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl- 3-ethyl-1-butene; 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl-1-pen And ten-, 2-propyl-1-pentene, 2,3-diethyl-1-butene; 1-nonene; 1-decene; 1-undecene; 1-dodecene, and the like. From the viewpoint of copolymerizability, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and 1-butene and 1-hexene are more preferable.

  The copolymer may be a random copolymer or a block copolymer. Preferred copolymers include propylene / ethylene copolymers and propylene / 1-butene copolymers. In the propylene / ethylene copolymer and the propylene / 1-butene copolymer, the ethylene unit content and the 1-butene unit content are, for example, 616 of “Polymer Analysis Handbook” (published by Kinokuniya, 1995). Infrared (IR) spectrum measurement can be performed by the method described on the page.

  From the viewpoint of improving the transparency and workability of the stretched film, the copolymer is preferably a random copolymer of propylene mainly composed of propylene and the unsaturated hydrocarbon, and a random copolymer of propylene and ethylene. More preferably, it is a polymer. As described above, the content of the ethylene unit in the propylene / ethylene random copolymer is preferably 1 to 20% by weight, more preferably 1 to 10% by weight, and 3 to 7% by weight. Is more preferable.

In the present invention, the polypropylene resin may be a polymer or copolymer polymerized using a known polymerization catalyst, and examples of the polymerization catalyst include the following.
(1) Ti—Mg-based catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components,
(2) a catalyst system in which a solid catalyst component containing magnesium, titanium and halogen as essential components is combined with an organoaluminum compound and, if necessary, a third component such as an electron donating compound,
(3) Metallocene catalysts.

  Examples of the solid catalyst component (1) include catalyst systems described in JP-A-61-218606, JP-A-61-287904, JP-A-7-216017, and the like. Preferred examples of the organoaluminum compound in the catalyst system of (2) above include triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, tetraethyldialumoxane, and the like. Preferable examples include cyclohexylethyldimethoxysilane, tert-butylpropyldimethoxysilane, tert-butylethyldimethoxysilane, dicyclopentyldimethoxysilane and the like.

  Examples of the metallocene catalyst (3) include catalyst systems described in Japanese Patent No. 2587251, Japanese Patent No. 2627669, Japanese Patent No. 2668732, and the like.

  Among these, metallocene catalysts are preferably used because a polymer or copolymer having a reduced xylene-soluble content is easily obtained.

  Polypropylene resins are, for example, solution polymerization methods using an inert solvent typified by hydrocarbon compounds such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, and liquid monomers as solvents. It can be produced by a bulk polymerization method to be used or a gas phase polymerization method in which a gaseous monomer is polymerized as it is. Polymerization by these methods may be carried out batchwise or continuously.

  The method for reducing the xylene-soluble content of the polypropylene resin to 1% by weight or less is not particularly limited. For example, in the polymerization stage, the degree of polymerization of the polypropylene resin is increased and the ratio of relatively low molecular weight components is increased. Methods known to those skilled in the art, such as a method of lowering, a method of washing a polypropylene-based resin obtained by polymerization with a solvent, extracting and removing solvent-soluble components such as low molecular weight components, and a combination of these methods. be able to. Note that, for example, a polypropylene catalyst obtained by appropriately selecting a polymerization catalyst and controlling the stereoregularity of the polypropylene resin to isotactic or syndiotactic and / or polymerizing with propylene alone. When the xylene-soluble content of the resin is 1% by weight or less, the treatment for reducing the xylene-soluble content of the polypropylene resin obtained by polymerization is not necessarily required.

  The polypropylene resin used in the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 21.18 N in a range of 0.1 to 200 g / 10 minutes in accordance with JIS K 7210. It is preferably within a range of 0.5 to 50 g / 10 minutes, and more preferably within a range of 0.5 to 15 g / 10 minutes. By using a polypropylene resin having an MFR within this range, a uniform polypropylene resin film can be obtained without imposing a large load on the extruder.

  The polypropylene resin may contain a known additive as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent. Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine light stabilizers, and the like, and for example, phenolic antioxidant mechanisms in one molecule. It is also possible to use a composite antioxidant having a unit having both a phosphorus-based antioxidant mechanism and a phosphorus-based antioxidant mechanism. Examples of the UV absorber include UV absorbers such as 2-hydroxybenzophenone and hydroxyphenylbenzotriazole, and benzoate UV blockers. The antistatic agent may be polymer type, oligomer type or monomer type. Examples of the lubricant include higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and salts thereof. As the anti-blocking agent, fine particles having a spherical shape or a shape close thereto can be used regardless of inorganic type or organic type.

  The nucleating agent may be either an inorganic nucleating agent or an organic nucleating agent. Examples of the inorganic nucleating agent include talc, clay, calcium carbonate and the like. Examples of the organic nucleating agent include metal salts such as aromatic carboxylic acid metal salts and aromatic phosphoric acid metal salts, high-density polyethylene, poly-3-methylbutene-1, polycyclopentene, and polyvinylcyclohexane. It is done. Among these, organic nucleating agents are preferable, and the above metal salts and high density polyethylene are more preferable. Moreover, 0.01 to 3 weight% is preferable and, as for the addition amount of the nucleating agent with respect to polypropylene resin, 0.05 to 1.5 weight% is more preferable. A plurality of these additives may be used in combination.

<Manufacture of polypropylene resin film>
The protective film (polypropylene resin film) made of the polypropylene resin used for the polarizing plate of the present invention can be obtained by forming the polypropylene resin. Such a polypropylene resin film is preferably excellent in transparency. Specifically, the total haze value measured according to JIS K 7105 is 10% or less, preferably 7% or less.

  The thickness of the polypropylene resin film is preferably about 5 to 200 μm. More preferably, it is 10 μm or more, and more preferably 150 μm or less.

  The film forming method of the polypropylene resin is not particularly limited, but is an extrusion method from a molten resin, a solvent cast method in which a resin dissolved in an organic solvent is cast on a flat plate, and the solvent is removed to form a film. According to these film forming methods, a polypropylene resin film having substantially no in-plane retardation can be obtained.

  A method for producing a polypropylene resin film by extrusion molding will be described in detail. In this method, a polypropylene resin is melt-kneaded by rotation of a screw in an extruder and extruded from a T die into a sheet. The temperature of the molten sheet to be extruded is about 180 to 300 ° C. If the temperature of the molten sheet at this time is lower than 180 ° C., the spreadability is not sufficient, the thickness of the resulting film becomes non-uniform, and there is a possibility that the film has phase difference unevenness. Further, when the temperature exceeds 300 ° C., the resin is easily deteriorated or decomposed, and bubbles may be generated in the sheet or carbides may be contained.

The extruder may be a single screw extruder or a twin screw extruder. For example, when a single screw extruder is used, L / D, which is the ratio of the screw length L to the diameter D, is about 24 to 36, the screw groove space volume V ₁ in the resin supply section, and the screw groove in the resin metering section. The compression ratio, which is the ratio (V ₁ / V ₂ ) to the space volume V ₂ , is about 1.5 to 4 and is a full flight type, a barrier type, or a screw having a Maddock type kneading part. Can be used. From the viewpoint of suppressing deterioration and decomposition of the polypropylene-based resin and uniformly melting and kneading, the barrier type L / D is 28 to 36 and the compression ratio V ₁ / V ₂ is 2.5 to 3.5. It is preferable to use a screw. Moreover, in order to suppress deterioration and decomposition | disassembly of polypropylene resin as much as possible, it is preferable to make the inside of an extruder into a nitrogen atmosphere or a vacuum. Furthermore, in order to remove the volatile gas generated when the polypropylene-based resin deteriorates or decomposes, it is also preferable to provide an orifice of about 1 mmφ to 5 mmφ at the tip of the extruder to increase the resin pressure at the tip of the extruder. Increasing the resin pressure at the leading end of the extruder by installing an orifice means increasing the back pressure at the leading end, thereby improving the stability of extrusion. The diameter of the orifice to be used is more preferably 2 mmφ or more and 4 mmφ or less.

  The T-die used for extrusion preferably has no fine steps or scratches on the resin flow path surface, and the lip portion is plated or coated with a material having a low coefficient of friction with the molten polypropylene resin. Further, a sharp edge shape with a lip tip polished to 0.3 mmφ or less is preferable. Examples of the material having a small friction coefficient include tungsten carbide type and fluorine type special plating. By using such a T-die, it is possible to suppress the generation of eyes and simultaneously suppress the die line, so that a resin film having excellent appearance uniformity can be obtained. In the T-die, the manifold has a coat hanger shape and preferably satisfies the following condition (A) or (B), and more preferably satisfies the condition (C) or (D).

(A) When the lip width of the T die is less than 1500 mm: the thickness direction length of the T die> 180 mm,
(B) When the lip width of the T die is 1500 mm or more: length in the thickness direction of the T die> 220 mm,
(C) When the lip width of the T die is less than 1500 mm: the length of the T die in the height direction> 250 mm,
(D) When the lip width of the T die is 1500 mm or more: Length in the height direction of the T die> 280 mm.

  By using a T die that satisfies these conditions, the flow of the molten polypropylene resin inside the T die can be adjusted, and the lip portion can be extruded while suppressing thickness unevenness, so that the thickness is increased. A protective film made of a polypropylene resin having excellent accuracy and a more uniform retardation can be obtained.

  In addition, it is preferable to attach a gear pump via an adapter between an extruder and a T die from a viewpoint of suppressing the extrusion fluctuation | variation of polypropylene resin. In addition, it is preferable to attach a leaf disk filter to remove foreign substances in the polypropylene resin.

  The desired polypropylene-based resin film consists of a molten sheet extruded from a T-die, a metal cooling roll (also called a chill roll or a casting roll), and an elastic body that rotates by pressing in the circumferential direction of the metal cooling roll. It can obtain by pinching between touch rolls to include and solidifying by cooling. In this case, the touch roll may be one in which an elastic body such as rubber is directly on the surface, or may be one in which the surface of the elastic body roll is covered with an outer cylinder made of a metal sleeve. When using a touch roll in which the surface of the elastic roll is covered with an outer cylinder made of a metal sleeve, cooling is usually performed by directly sandwiching a molten sheet of polypropylene resin between the metal cooling roll and the touch roll. . On the other hand, in the case of using a touch roll whose surface is an elastic body, a biaxially stretched film of a thermoplastic resin can be interposed between the molten sheet of polypropylene resin and the touch roll for sandwiching.

  When the molten sheet of polypropylene resin is cooled and solidified by being sandwiched between the cooling roll and the touch roll as described above, the surface temperature of the cooling roll and the touch roll may be lowered to rapidly cool the molten sheet. preferable. For example, the surface temperature of both rolls is preferably adjusted to a range of 0 ° C. or higher and 30 ° C. or lower. When these surface temperatures exceed 30 ° C., it takes time to cool and solidify the molten sheet, so that the crystal component in the polypropylene resin grows, and the resulting film may be inferior in transparency. . On the other hand, when the surface temperature of the roll is lower than 0 ° C., the surface of the metal cooling roll is dewed and water droplets are attached, which tends to deteriorate the appearance of the raw film.

  Since the surface state of the metal cooling roll used is transferred to the surface of the polypropylene resin film, there is a possibility that the thickness accuracy of the resulting polypropylene resin film may be lowered if the surface is uneven. . Therefore, it is preferable that the surface of the metal cooling roll is in a mirror surface state as much as possible. Specifically, the roughness of the surface of the metal cooling roll is preferably 0.4 S or less, more preferably 0.05 S to 0.2 S, expressed as a standard sequence of the maximum height. .

  As for the metal roll and the touch roll forming the nip part, the surface hardness of the elastic body is 65 to 80 as a value measured by a spring type hardness test (A type) defined in JIS K 6301. It is preferable that there is, more preferably 70-80. By using a rubber roll having such a surface hardness, it becomes easy to maintain a uniform linear pressure applied to the molten sheet, and a bank of the molten sheet (resin pool) is provided between the metal cooling roll and the touch roll. ) Can be easily formed into a film.

  The pressure (linear pressure) when sandwiching the molten sheet is determined by the pressure for pressing the touch roll against the metal cooling roll. The linear pressure is preferably 50 N / cm or more and 300 N / cm or less, and more preferably 100 N / cm or more and 250 N / cm or less. By setting the linear pressure within the above range, it becomes easy to produce a polypropylene resin film while maintaining a constant linear pressure without forming a bank.

  When sandwiching a biaxially stretched film of a thermoplastic resin together with a molten sheet of polypropylene resin between a metal cooling roll and a touch roll, the thermoplastic resin constituting the biaxially stretched film is a polypropylene resin and Any resin that does not strongly heat-seal can be used. Specific examples include polyester, polyamide, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polyacrylonitrile. Among these, polyesters that have little dimensional change due to humidity, heat, and the like are most preferable. In this case, the thickness of the biaxially stretched film is usually about 5 to 50 μm, preferably 10 to 30 μm.

  In this method, the distance (air gap) from the lip of the T die to the pressure between the metal cooling roll and the touch roll is preferably 200 mm or less, and more preferably 160 mm or less. The molten sheet extruded from the T-die is stretched from the lip to the roll, and orientation tends to occur. By shortening the air gap as described above, a film having a smaller orientation can be obtained. The lower limit value of the air gap is determined by the diameter of the metal cooling roll to be used, the diameter of the touch roll, and the tip shape of the lip to be used, and is usually 50 mm or more.

  Moreover, the processing speed when producing a polypropylene resin film by this method is determined by the time required for cooling and solidifying the molten sheet. When the diameter of the metal cooling roll to be used is increased, the distance at which the molten sheet is in contact with the cooling roll becomes longer, so that production at a higher speed is possible. Specifically, when a 600 mmφ metal cooling roll is used, the processing speed is about 5 to 20 m / min at the maximum.

  The molten sheet sandwiched between the metal cooling roll and the touch roll is cooled and solidified by contact with the roll. And after slitting an edge part as needed, it is wound up by a winder and turns into a roll-shaped polypropylene resin film. At this time, in order to protect the surface until the roll-shaped polypropylene-based resin film is used, the surface protection film made of another thermoplastic resin is bonded to one or both surfaces of the roll-shaped polypropylene resin film. Also good. When a molten sheet of polypropylene resin is sandwiched between a metal cooling roll and a touch roll together with a biaxially stretched film made of a thermoplastic resin, the biaxially stretched film is used as one surface protective film. You can also. As described above, a protective film made of a polypropylene resin film can be produced.

  The haze value of the polypropylene resin film used as the protective film in the present invention is preferably 0.5% or less, and more preferably 0.3% or less. As a method for suppressing the haze value of the polypropylene resin film to 0.5% or less, (A) a method for producing a resin obtained by random copolymerization of propylene and an unsaturated hydrocarbon other than propylene, (B ) A method of adding a nucleating agent to a polypropylene resin, (C) a method of forming a film by increasing the cooling efficiency of a casting roll during extrusion molding, and the like. These methods are appropriately combined so that the haze value of the polypropylene resin film is 0.5% or less.

(A) Method by Random Copolymerization The random copolymerization method includes a method of producing a random copolymer of propylene as a main component and an arbitrary unsaturated hydrocarbon. Specific examples thereof include propylene / ethylene random copolymer, propylene / 1-butene random copolymer, propylene / 1-hexene random copolymer, propylene / ethylene / 1-octene random copolymer, propylene / ethylene / Examples thereof include 1-butene random copolymers, and among these, a copolymer with ethylene is particularly preferable.

  When the copolymer is used, unsaturated hydrocarbons other than propylene preferably have a copolymerization ratio in the range of about 1 to 20% by weight, more preferably in the range of 2 to 10% by weight. Preferably, it is more preferable to set it within the range of 3 to 7% by weight.

  By setting the unit of unsaturated hydrocarbons other than propylene to 1% by weight or more, processability and transparency tend to be improved. However, when the ratio exceeds 10% by weight, the melting point of the resin is lowered and the heat resistance tends to deteriorate. In addition, when setting it as the copolymer of two or more types of comonomers and propylene, it is preferable that the total content of the unit derived from all the comonomers contained in the copolymer is the said range.

(B) Method by addition of nucleating agent The nucleating agent used in the present invention may be either an inorganic nucleating agent or an organic nucleating agent. Examples of the inorganic nucleating agent include talc, clay, calcium carbonate and the like. Examples of the organic nucleating agent include metal salts such as aromatic carboxylic acid metal salts and aromatic phosphoric acid metal salts, high-density polyethylene, poly-3-methylbutene-1, polycyclopentene, and polyvinylcyclohexane. It is done. Among these, organic nucleating agents are preferable, and the above metal salts and high density polyethylene are more preferable. Moreover, 0.01-3 weight% is preferable and, as for the addition amount of the nucleating agent with respect to a propylene polymer, 0.05-1.5 weight% is more preferable.

  The nucleating agent may be added by a method that can be uniformly dispersed in a polypropylene resin. For example, in the polymerization step for producing the polypropylene resin, a method of adding a nucleating agent to the polymerization reaction mixture during the polymerization reaction or immediately after the completion of the polymerization reaction can be mentioned. The nucleating agent may be added as a solution dissolved in a solvent, may be added in a state of being pulverized into a powder form so that it can be easily dispersed, or may be added in a molten state by heating. .

(C) Method by Rapid Cooling in Extrusion Molding The polypropylene resin film used in the present invention comprises a molten sheet extruded from a T-die, a metal cooling roll (also called a chill roll or a casting roll), and the metal cooling roll. It can be obtained by being pinched with a touch roll including an elastic body that presses and rotates in the circumferential direction, and is cooled and solidified. At this time, from the viewpoint of suppressing the haze value to 0.5% or less, it is preferable to lower the surface temperature of the touch roll and quench the molten sheet. For example, the surface temperature of both rolls is preferably adjusted to a range of 0 ° C. or higher and 30 ° C. or lower. When these surface temperatures exceed 30 ° C., it takes time to cool and solidify the molten sheet, so that the crystal component in the polypropylene resin grows, and the resulting film may be inferior in transparency. . On the other hand, when the surface temperature of the roll is lower than 0 ° C., the surface of the metal cooling roll is dewed and water droplets are attached, which tends to deteriorate the appearance of the raw film.

  It is also effective to reduce the thickness of the molten sheet. This is because by controlling the film thickness to be thin, the haze value can be reduced and at the same time the cooling efficiency by the metal cooling roll can be increased. At that time, the extrusion amount of the molten sheet can be arbitrarily selected.

Furthermore, the polypropylene resin film preferably has an in-plane retardation value (R ₀ ) at a wavelength of 590 nm of 30 nm or less, and more preferably 10 nm or less. When the in-plane retardation of the film increases, light leakage during black display increases and the contrast ratio decreases significantly.

  Further, the angle formed by the MD (machine direction) and the optical axis of the protective film is preferably ± 5 ° or less, and more preferably ± 3 ° or less. When the above angle is larger than ± 5 °, light leakage at the time of black display becomes large, and the reduction in contrast ratio becomes remarkable.

  Furthermore, the value of the transmittance parameter calculated from the in-plane retardation and the angle between the MD and the optical axis is preferably 0.03 or less, more preferably 0.007 or less, and still more preferably 0.00. 001 or less. When this value is larger than 0.03, the light leakage at the time of black display becomes remarkable, and the reduction of the contrast ratio becomes remarkable.

The transmittance parameter is a parameter defined by the following equation:
(Transmittance ^{parameter) = sin 2 2θ × sin 2} (π × R 0/590)
Here, θ represents the angle formed by the MD of the protective film and the optical axis, and R ₀ represents in-plane retardation at a wavelength of 590 nm.

[Transparent resin film]
The transparent resin film (film 13 in FIG. 1) constituting the polarizing plate with the pressure-sensitive adhesive layer of the present invention is not particularly limited as long as it has transparency, and may be a protective film made of the above-described polypropylene-based resin. You may make it laminate | stack the protective film which consists of resin other than. Examples of protective films made of resins other than polypropylene resins include films made of cellulose acetate resins such as triacetyl cellulose and diacetyl cellulose, polyester resin films, (meth) acrylic resin films, polycarbonate resin films, etc. Is mentioned. Considering the ease of adhesion with the polarizing film and the ease of forming the surface treatment layer described later, a cellulose acetate resin film, particularly a triacetyl cellulose film is preferably used. The thickness of the protective film made of a resin other than the polypropylene resin is usually about 0.1 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 100 μm. In addition, a surface treatment layer such as a hard coat layer, an antireflection layer, and an antiglare layer may be formed on the surface opposite to the adhesive surface to the polarizing film 10.

<Adhesive layer>
An adhesive is used for bonding the polarizing film 10 and the polypropylene resin film 14 and for bonding the polarizing film 10 and the transparent resin film 13. This adhesive contains an epoxy compound and is cured by irradiation with active energy rays, heating, drying, etc., and the polarizing film 10, the polypropylene resin film 14, and the transparent resin film 13 stretched with the polarizing film 10 are put into practical use. Any material can be used as long as it can be bonded with sufficient strength.

  Of these, a cationically polymerizable photocurable adhesive composition containing an epoxy compound and a photocationic polymerization initiator is preferred. The adhesive composition is more preferably usable without a solvent. That is, an active energy obtained by selecting a photocationically curable epoxy compound that is solvent-free and has an appropriate fluidity and gives an appropriate curing adhesive strength, and blending a cationic polymerization initiator suitable for it. The linear curable adhesive composition can omit a drying facility in the curing process, and generally adheres the polypropylene resin film 14 which is difficult to adhere in other photocuring and thermosetting systems to the polarizing film 10 with a good adhesive force. . In addition, by irradiating with an appropriate active energy dose, the curing rate can be accelerated and the production rate can be improved.

  Examples of epoxy compounds used in such adhesive compositions include glycidyl etherified products of aromatic compounds or chain compounds having a hydroxyl group, glycidyl aminated products of compounds having an amino group, and C—C double bonds. Epoxy product of chain compound having alicyclic epoxy compound in which glycidyloxy group or epoxyethyl group is bonded directly to saturated carbon ring or via alkylene, or epoxy group is directly bonded to saturated carbon ring and so on. These epoxy compounds may be used alone or in combination with a plurality of different types. Of these, alicyclic epoxy compounds are preferably used because of their excellent cationic polymerizability.

  The glycidyl etherified product of an aromatic compound or a chain compound having a hydroxyl group can be obtained, for example, by a method of addition condensation of epichlorohydrin to the hydroxyl group of the aromatic compound or chain compound under basic conditions. Examples thereof include bisphenol type epoxy resins, polyaromatic ring type epoxy resins, alkylene glycol type epoxy resins and the like.

  Examples of bisphenol type epoxy resins include glycidyl etherified products of bisphenol A and oligomers thereof, glycidyl etherified products of bisphenol F and oligomers thereof, 3,3 ′, 5,5′-tetramethyl-4,4′-biphenol. Examples thereof include glycidyl etherified products and oligomers thereof.

  Examples of polyaromatic epoxy resins include glycidyl etherified products of phenol novolac resins, glycidyl etherified products of cresol novolac resins, glycidyl etherified products of phenol aralkyl resins, glycidyl etherified products of naphthol aralkyl resins, and glycidyl ethers of phenol dicyclopentadiene resins. And the like. Furthermore, glycidyl etherified products of trisphenols and oligomers thereof also belong to the polyaromatic ring type epoxy resin.

  Examples of the alkylene glycol type epoxy resin include glycidyl etherification product of ethylene glycol, glycidyl etherification product of diethylene glycol, glycidyl etherification product of 1,4-butanediol, glycidyl etherification product of 1,6-hexanediol, and the like.

  A glycidyl aminated product of a compound having an amino group can be obtained by a method in which epichlorohydrin is addition-condensed to the amino group of the compound under basic conditions. The compound having an amino group may have a hydroxyl group at the same time. For example, glycidyl amination product of 1,3-phenylenediamine and oligomer thereof, glycidyl amination product and oligomer of 1,4-phenylenediamine, glycidyl amination and glycidyl etherification product of 3-aminophenol and oligomer thereof Glycidyl amination and glycidyl etherification product of 4-aminophenol and oligomers thereof.

  An epoxidized product of a chain compound having a C—C double bond can be obtained by a method of epoxidizing a C—C double bond of the chain compound under a basic condition using a peroxide. . Examples of the chain compound having a C—C double bond include butadiene, polybutadiene, isoprene, pentadiene, hexadiene and the like. Terpenes having a double bond can also be used as a raw material for epoxidation, and examples of acyclic monoterpenes include linalool. Examples of peroxides used for epoxidation include hydrogen peroxide, peracetic acid, tert-butyl hydroperoxide, and the like.

  An alicyclic epoxy compound in which a glycidyloxy group or an epoxyethyl group is bonded to a saturated carbocycle directly or via alkylene is an aromatic ring of an aromatic compound having a hydroxyl group, typically a bisphenol as mentioned above. Examples thereof include a glycidyl etherified product of a hydrogenated cyclic polyhydroxy compound obtained by hydrogenation, a glycidyl etherified product of a saturated cyclic compound having a hydroxyl group, and an epoxidized product of a saturated cyclic compound having a vinyl group.

  The epoxy compound as described above can be easily obtained as a commercial product. Examples of commercially available products are "Epicoat" sold by Japan Epoxy Resin Co., Ltd., "Epicron" sold by DIC Corporation, and "Epototo" sold by Toto Kasei Corporation. "Adeka Resin" sold by ADEKA Co., Ltd., "Denacol" sold by Nagase ChemteX Corporation, "Dow Epoxy" sold by Dow Chemical Company, and sold by Nissan Chemical Industries, Ltd. There is "tepic".

  On the other hand, an alicyclic epoxy compound in which an epoxy group is directly bonded to a saturated carbocyclic ring, for example, peroxidizes a CC double bond of a non-aromatic cyclic compound having a C—C double bond in the ring. Can be obtained by a method of epoxidizing the product under basic conditions. As a non-aromatic cyclic compound having a C—C double bond in the ring, for example, a compound having a cyclopentene ring, a compound having a cyclohexene ring, a cyclopentene ring or a cyclohexene ring added with at least two additional carbon atoms And a polycyclic compound forming the ring. This non-aromatic cyclic compound having a C—C double bond in the ring may have another C—C double bond outside the ring. Examples of non-aromatic cyclic compounds having a C—C double bond in the ring include cyclohexene, 4-vinylcyclohexene, limonene and α-pinene, which are monocyclic monoterpenes.

  An alicyclic epoxy compound in which an epoxy group is directly bonded to a saturated carbocyclic ring has an alicyclic structure having an epoxy group directly bonded to the ring as described above in the molecule through an appropriate linking group. It may be a compound in which at least two are formed. Examples of the linking group herein include groups having an ester bond, an ether bond, an alkylene bond, and the like.

  Examples of alicyclic epoxy compounds in which an epoxy group is directly bonded to a saturated carbocycle include the following.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,
1,2-epoxy-4-vinylcyclohexane,
1,2-epoxy-4-epoxyethylcyclohexane,
1,2-epoxy-1-methyl-4- (1-methylepoxyethyl) cyclohexane,
3,4-epoxycyclohexylmethyl (meth) acrylate,
An adduct of 2,2-bis (hydroxymethyl) -1-butanol and 4-epoxyethyl-1,2-epoxycyclohexane,
Ethylene bis (3,4-epoxycyclohexanecarboxylate),
Oxydiethylene bis (3,4-epoxycyclohexanecarboxylate),
1,4-cyclohexanedimethyl bis (3,4-epoxycyclohexanecarboxylate),
3- (3,4-epoxycyclohexylmethoxycarbonyl) propyl 3,4-epoxycyclohexanecarboxylate and the like.

  Commercially available alicyclic epoxy compounds in which an epoxy group is directly bonded to a saturated carbocyclic ring as described above can also be easily obtained. Examples of commercially available products include “Celoxide” and “Cyclomer” sold by Daicel Chemical Industries, Ltd., and “Syracure” sold by Dow Chemical Company.

  The curable adhesive composition containing the epoxy compound may further contain an active energy ray-curable compound other than the epoxy compound. Examples of the active energy ray-curable compound other than the epoxy compound include an oxetane compound and an acrylic compound. Especially, since a cure rate can be improved in cationic polymerization, it is preferable to use an oxetane compound together.

  The oxetane compound is a compound having a 4-membered ring ether in the molecule, and examples thereof include the following.

1,4-bis [(3-ethyloxetane-3-yl) methoxymethyl] benzene,
3-ethyl-3- (2-ethylhexyloxymethyl) oxetane,
Bis (3-ethyl-3-oxetanylmethyl) ether,
3-ethyl-3- (phenoxymethyl) oxetane,
3-ethyl-3- (cyclohexyloxymethyl) oxetane,
Phenol novolac oxetane,
1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene and the like.

  As for oxetane compounds, commercially available products can be easily obtained. Examples of commercially available products include “Aron Oxetane” sold by Toagosei Co., Ltd. and “ETERNACOLL” sold by Ube Industries, Ltd.

  As the curable compound including the epoxy compound and the oxetane compound, it is preferable to use a curable compound which is not diluted with an organic solvent or the like in order to make the curable adhesive composition obtained by blending these compounds solvent-free. In addition, a small amount of components including a cationic photopolymerization initiator and a sensitizer constituting the adhesive composition to be described later are also a powder of the compound alone from which the organic solvent has been removed and dried rather than those dissolved in the organic solvent. It is preferable to use a body or a liquid.

  The cationic photopolymerization initiator is an agent that generates an active energy ray, for example, a cationic species upon irradiation with ultraviolet rays, and provides an adhesive strength and a curing rate required for an adhesive composition in which it is incorporated. Good. Examples include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes. These photocationic polymerization initiators may be used alone or in combination with a plurality of different types.

Examples of the aromatic diazonium salt include the following compounds.
Benzenediazonium hexafluoroantimonate,
Benzenediazonium hexafluorophosphate,
Benzenediazonium hexafluoroborate, etc.

Examples of the aromatic iodonium salt include the following compounds.
Diphenyliodonium tetrakis (pentafluorophenyl) borate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium hexafluoroantimonate,
Bis (4-nonylphenyl) iodonium hexafluorophosphate and the like.

Examples of the aromatic sulfonium salt include the following compounds.
Triphenylsulfonium hexafluorophosphate,
Triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrakis (pentafluorophenyl) borate,
Diphenyl (4-phenylthiophenyl) sulfonium hexafluoroantimonate,
4,4'-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate,
4,4′-bis [di (β-hydroxyethoxyphenyl) sulfonio] diphenyl sulfide bishexafluoroantimonate,
4,4′-bis [di (β-hydroxyethoxyphenyl) sulfonio] diphenyl sulfide bishexafluorophosphate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,
4-phenylcarbonyl-4'-diphenylsulfoniodiphenyl sulfide hexafluorophosphate,
4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfoniodiphenyl sulfide hexafluoroantimonate,
4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

Examples of the iron-allene complex include the following compounds.
Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,
Cumene-cyclopentadienyl iron (II) hexafluorophosphate,
Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide.

  Among these photocationic polymerization initiators, the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, and therefore provides an adhesive layer having excellent curability and good mechanical strength and adhesive strength. Therefore, it is preferably used.

  A commercial product can also be easily obtained as the cationic photopolymerization initiator. Examples of commercially available products are “Kayarad” sold by Nippon Kayaku Co., Ltd., “Syracure” sold by Union Carbide, and photoacid generators sold by San Apro Corporation. Agent "CPI", photoacid generators "TAZ", "BBI" and "DTS" sold by Midori Chemical Co., Ltd., "Adekaoptomer" sold by ADEKA Corporation, sold by Rhodia There is “RHODORSIL”.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of total amounts of a photocurable adhesive composition, Preferably it is 1-15 weight part. When the amount is less than 0.5 parts by weight, curing becomes insufficient, and the mechanical strength and adhesive strength of the adhesive layer may be lowered. On the other hand, when the amount exceeds 20 parts by weight, the ionic substance in the adhesive layer increases, so that the hygroscopicity of the adhesive layer increases, and the durability performance of the obtained polarizing plate may be lowered.

  The photocurable adhesive composition can contain a photosensitizer as necessary. By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the adhesive layer can be further improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes.

  Examples of carbonyl compounds that can be photosensitizers include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and α, α-dimethoxy-α-phenylacetophenone; anthracene such as 9,10-dibutoxyanthracene Compounds; benzophenones and derivatives thereof such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; 2 Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; aceto such as α, α-diethoxyacetophenone Examples include phenone derivatives; xanthone derivatives; fluorenone derivatives. Examples of organic sulfur compounds that can serve as photosensitizers include 2-chlorothioxanthone and thioxanthone derivatives such as 2-isopropylthioxanthone. In addition, benzyl compounds and uranyl compounds can also be used as photosensitizers. These photosensitizers may be used alone or in combination with a plurality of different types.

  When mix | blending a photosensitizer, it is preferable that the compounding quantity shall be the range of 0.1-20 weight part with respect to 100 weight part of total amounts of a photocurable adhesive composition.

  Various additives can be blended in the photocurable adhesive composition as long as the effect is not impaired. Examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent.

  The photocurable adhesive composition only needs to have a viscosity that can be applied to the film by an appropriate method, and the viscosity at 25 ° C. is preferably in the range of 10 to 30,000 mPa · sec. More preferably, it is in the range of 50 to 6,000 mPa · sec. When the viscosity is less than 10 mPa · sec, the apparatus that can be applied is limited, and even if the application can be performed, it tends to be difficult to obtain a uniform coating film without unevenness. On the other hand, when the viscosity exceeds 30,000 mPa · sec, it becomes difficult to flow, the number of devices that can be applied in the same way is limited, and a uniform coating without unevenness tends to be difficult to obtain. The viscosity referred to here is a value measured at 60 rpm after the temperature of the composition is adjusted to 25 ° C. using a B-type viscometer.

[Adhesive layer]
The pressure-sensitive adhesive layer (pressure-sensitive adhesive layer 15 in FIG. 1) constituting the polarizing plate with the pressure-sensitive adhesive layer of the present invention comprises an acrylic resin (A) and a crosslinking agent (B) having a glass transition temperature (Tg) of 0 ° C. or less. It is formed from the adhesive composition to contain. Here, the acrylic resin (A) is 80 to 94% by weight of a (meth) acrylic acid ester monomer (A-1) represented by the following formula (I) and a (meth) acrylic monomer (A) having a polar functional group. -2) 0.1 to 5% by weight and a monomer (A-3) having 5 to 15% by weight of a monomer having one olefinic double bond and at least one aromatic ring in the molecule The composition is obtained by radical polymerization in the presence of a polymerization initiator. The pressure-sensitive adhesive layer formed from such a pressure-sensitive adhesive composition has excellent adhesion to the protective film (polypropylene-based resin film) 14 made of the polypropylene-based resin, and after being bonded to a glass substrate, When peeling, the glass substrate can be peeled relatively easily without causing adhesive residue and the like, and has excellent reworkability.

In the above formula, R ₁ is a hydrogen atom or a methyl group, and R ₂ is an alkyl group having 1 to 14 carbon atoms. In the alkyl group, any one or more hydrogen atoms may be substituted with an alkoxy group having 1 to 10 carbon atoms.

Examples of the (meth) acrylic acid ester monomer (A-1) represented by the formula (I) include n-butyl acrylate in which R ₁ in the formula (I) is H and R ₂ is an n-butyl group. And ₂ -ethylhexyl acrylate in which R ₁ is H and R ₂ is a 2-ethylhexyl group. For example, when R ₁ is H and R ₂ is an alkyl group substituted with an alkoxy group, 2-methoxyethyl acrylate, ethoxymethyl acrylate, and the like can be given.

  The (meth) acrylic monomer (A-2) having a polar functional group is a polar functional group such as a hydroxyl group, a carboxyl group, an amino group, or an epoxy group, and one olefinic double bond (usually (meth) acryloyl). Group) in the molecule. Among them, 2-hydroxyethyl acrylate is preferably used as the one having a hydroxyl group. Acrylic acid is preferably used as the carboxyl group.

  Examples of the monomer (A-3) having one olefinic double bond and at least one aromatic ring in the molecule include styrene, phenyl (meth) acrylate, benzyl (meth) acrylate, and the like. In particular, those represented by the following formula (II) are preferable because they have a good whiteout prevention function when used as a polarizing plate.

Here, in said formula, R < ₃ > represents a hydrogen atom or a methyl group, n is an integer of 1-8, R < ₄ > represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group.

  Examples of such a monomer (A-3) include phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide-modified nonylphenol (meth) acrylate, and hydroxyethylated o-phenylphenol (meth) acrylate. Can be mentioned. Among these, phenoxyethyl acrylate is more preferable.

  In the present invention, the monomer (A-1), monomer (A-2), and monomer (A-3) content in the monomer composition is a monomer that is a main monomer that plays a main role as an adhesive ( Since the performance of the monomer (A-2) and the monomer (A-3) having high functionality while maintaining the ratio of A-1) high, the monomer (A-1) / monomer (A -2) / monomer (A-3) = 80 to 94 wt% / 0.1 to 5 wt% / 5 to 15 wt%, preferably 85 to 92 wt% / 0.5 to 3 wt% / 5 to 12% by weight.

  The acrylic resin (A) may further contain a copolymerizable monomer other than the monomers (A-1) to (A-3) as a copolymerization component. Such monomers may be used alone, or a plurality of different monomers may be used in combination. Content with respect to the whole acrylic resin of the structural unit derived from monomers other than such (A-1)-(A-3) is 0-20 weight% normally, Preferably it is 0-10 weight%.

  The molecular weight of the acrylic resin (A) is preferably 1,000,000 to 2,000,000 as a weight average molecular weight (Mw) in terms of standard polystyrene by gel permeation chromatography (GPC). When the weight average molecular weight is 1,000,000 or more, the adhesiveness under high temperature and high humidity is improved, and there is a tendency that the possibility of floating or peeling between the glass substrate and the pressure-sensitive adhesive layer is reduced. This is preferable because reworkability tends to be improved. In addition, when the weight average molecular weight is 2 million or less, even if the size of the polarizing plate bonded to the pressure-sensitive adhesive layer changes, the pressure-sensitive adhesive layer changes following the change in size, so that the liquid crystal cell This is preferable because there is no difference between the brightness of the peripheral edge and the brightness of the center, and white spots and color unevenness tend to be suppressed. Furthermore, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferably in the range of 3-7.

  Moreover, the glass transition temperature (Tg) of acrylic resin (A) shall be 0 degrees C or less, Preferably it is -5 degrees C or less, More preferably, it is -20 degrees C or less. When the glass transition temperature exceeds 0 ° C., the adhesion between the polypropylene and the pressure-sensitive adhesive layer is not sufficient.

  As a manufacturing method of acrylic resin (A), various well-known methods, such as solution polymerization method, emulsion polymerization method, block polymerization method, suspension polymerization method, are employ | adopted, for example. The acrylic resin (A) is usually produced by radical polymerization of the monomer composition in the presence of a polymerization initiator. The polymerization initiator is used in an amount of about 0.001 to 5 parts by weight with respect to 100 parts by weight of the total amount of monomers constituting the acrylic resin (A). Examples of the polymerization initiator include azo compounds, organic peroxides, inorganic peroxides, and redox initiators in which a peroxide and a reducing agent are used in combination. Of these, 2,2'-azobisisobutyronitrile, benzoyl peroxide, ammonium persulfate, and the like are preferably used.

  The acrylic resin (A) thus obtained is blended with the crosslinking agent (B) to obtain a pressure-sensitive adhesive composition. In the acrylic resin (A), the crosslinking agent (B) has at least 2 functional groups capable of crosslinking with a structural unit derived from the (meth) acrylic monomer (A-2) having a polar functional group in the molecule. Examples of such compounds include isocyanate compounds, epoxy compounds, metal chelate compounds, and aziridine compounds.

  Among these crosslinking agents, isocyanate compounds are preferably used. Examples of the isocyanate compound include tolylene diisocyanate, an adduct obtained by reacting tolylene diisocyanate with a polyol, a dimer of tolylene diisocyanate, and a trimer of tolylene diisocyanate, and hexamethylene diisocyanate, hexamethylene. Examples thereof include adducts obtained by reacting diisocyanates with polyols, dimers of hexamethylene diisocyanate, and trimers of hexamethylene diisocyanate.

  The compounding quantity of a crosslinking agent (B) is 0.01-5 weight part normally with respect to 100 weight part of acrylic resin (A), Preferably it is 0.1-5 weight part, More preferably, it is 0.2. ~ 3 parts by weight. When the amount of the crosslinking agent (B) relative to 100 parts by weight of the acrylic resin (A) is 0.01 parts by weight or more, particularly 0.1 parts by weight or more, the durability of the pressure-sensitive adhesive layer tends to be improved. Moreover, when it is 5 parts by weight or less, white spots tend to be inconspicuous when the polarizing plate with an adhesive layer is applied to a liquid crystal display device.

  In addition, although the said adhesive composition which forms an adhesive layer may contain only a comparatively high molecular weight acrylic resin (A) as a resin component, acrylics other than acrylic resin (A) are included. Resin may be included. As an acrylic resin other than the acrylic resin (A), for example, the structural unit derived from the (meth) acrylic acid ester monomer represented by the formula (I) is a main component, and the weight average molecular weight is 50,000 to 300,000. Those in the range are mentioned.

  As a raw material of the pressure-sensitive adhesive composition as described above, a commercially available product can be easily obtained. For example, various acrylic monomers can be obtained from Nippon Shokubai Co., Ltd. or Toagosei Co., Ltd. 2,2'-azobisisobutyronitrile, which is a polymerization initiator, can be obtained from Otsuka Chemical Co., Ltd., Nippon Finechem Co., Ltd. and the like. Hexamethylene diisocyanate and its trimethylolpropane adduct as a cross-linking agent, tolylene diisocyanate and its trimethylolpropane adduct, etc. are obtained from Mitsui Chemicals Polyurethanes, Sumika Bayer Urethane, Nippon Polyurethane Industry, etc. be able to.

  The pressure-sensitive adhesive layer used in the present invention preferably has antistatic properties in order to eliminate static electricity charged on the pressure-sensitive adhesive layer-attached polarizing plate. The polarizing plate with the pressure-sensitive adhesive layer peels off the peelable protective film (peeling film) and peels off the peeling film (separator) protecting the pressure-sensitive adhesive layer and bonds the polarizing plate to the liquid crystal cell. When the pressure-sensitive adhesive layer has antistatic properties, the static electricity is quickly removed, the display circuit of the liquid crystal cell is destroyed, and the liquid crystal molecules are disturbed. Is suppressed.

  In order to impart antistatic properties to the pressure-sensitive adhesive layer, generally, a method in which the pressure-sensitive adhesive composition contains metal fine particles, metal oxide fine particles, or fine particles coated with metal, etc .; consisting of an electrolyte salt and an organopolysiloxane A method of incorporating an ionic conductive composition; a method of blending an organic salt-based antistatic agent, and the like are employed. On the other hand, the required antistatic property holding time is required to be about 6 months at maximum from the viewpoint of production, distribution and storage period of a general polarizing film.

  Therefore, in order to impart antistatic properties to the pressure-sensitive adhesive layer used in the present invention, it is preferable to add an ionic compound to the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer. This ionic compound is preferably an ionic compound (C) having an organic cation since it has excellent compatibility with the pressure-sensitive adhesive composition. In particular, those having a melting point in the range of 30 to 80 ° C are preferable.

  The organic cation component constituting the ionic compound (C) having an organic cation is preferably selected from those having a melting point of the ionic compound of 30 to 80 ° C. Among them, a release film provided on the adhesive layer From the viewpoint that it is difficult to be charged when the (separator) is peeled off, a pyridinium cation or an imidazolium cation is more preferable. On the other hand, in the ionic compound (C), the anion component serving as the counter ion of the organic cation component is preferably selected from those in which the melting point of the ionic compound can be 30 to 80 ° C. It may be an organic anion. Among these, an anion component containing a fluorine atom is preferably used from the viewpoint of providing an ionic compound having excellent antistatic performance, and a hexafluorophosphate anion is more preferable.

  The ionic compound (C) having an organic cation can be appropriately selected from a combination of the organic cation component and the anion component. For example, N-hexylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, N- Examples include octyl-4-methylpyridinium hexafluorophosphate, N-butyl-4-methylpyridinium hexafluorophosphate, N-methyl-4-hexylpyridinium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluorophosphate. It is done. Such ionic compounds (C) may be used alone or in combination of two or more.

  30-80 degreeC is preferable and, as for melting | fusing point of the ionic compound (C) which has an organic cation, 35-70 degreeC is more preferable. When melting | fusing point exceeds 80 degreeC, compatibility with an ionic compound (C) and acrylic resin (A) may worsen. If the melting point is less than 30 ° C., the antistatic long-term stability may be inferior.

  The content of the ionic compound (C) having an organic cation with respect to 100 parts by weight of the acrylic resin (A) is preferably 0.2 to 8 parts by weight, and more preferably 0.5 to 3 parts by weight. When the ionic compound (C) having an organic cation is contained in an amount of 0.2 part by weight or more with respect to 100 parts by weight of the acrylic resin (A), the antistatic performance is improved, and the amount is 8% by weight. If it is at most parts, it is preferable because durability is easily maintained.

  There are commercially available ionic compounds as described above, for example, pyridinium cation type ionic compounds (manufactured by Guangei Chemical Co., Ltd.), imidazolium cation type ionic compounds (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and aliphatic quaternary compounds. Examples include quaternary ammonium cation type ionic compounds (manufactured by Nisshinbo Industries, Ltd.).

  In the pressure-sensitive adhesive composition, if necessary, a silane coupling agent, a crosslinking catalyst, a weathering stabilizer, a tackifier, a plasticizer, a softening agent, a dye, a pigment, an inorganic filler, a resin other than the acrylic resin (A), And one or more selected from solvents and the like may be blended. It is also useful to blend an ultraviolet curable compound into the pressure-sensitive adhesive composition and to cure it by irradiating with ultraviolet rays after forming the pressure-sensitive adhesive layer to form a harder pressure-sensitive adhesive layer.

  The pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive composition (typically a pressure-sensitive adhesive solution containing a solvent) mainly composed of the acrylic resin (A) as described above, and an adhesive surface of the polypropylene resin film 14 to the polarizing film 10. In addition to being able to be formed by the method of applying to the opposite surface and drying, the adhesive composition (typically an adhesive solution containing a solvent) is applied to the release treatment surface of the film that has been subjected to the release treatment. Then, after forming the pressure-sensitive adhesive layer by drying, this film with the pressure-sensitive adhesive layer is opposite to the adhesive surface of the polypropylene resin film 14 to the polarizing film 10 so that the pressure-sensitive adhesive layer side becomes the bonding surface. It can also be formed by a method of bonding to the side surface. It is preferable that a surface of the polypropylene resin film 14 on which the pressure-sensitive adhesive layer 15 is formed is opposite to the surface of the polypropylene-based resin film 14 that is opposite to the surface to be bonded to the polarizing film 10. Thereby, the adhesiveness of the said polypropylene resin film 14 and the adhesive layer 15 can further be improved. The pressure-sensitive adhesive layer 15 may be formed after the transparent resin film 13 and the polypropylene-based resin film 14 are bonded to the polarizing film 10 via the adhesive layers 11 and 12, or the pressure-sensitive adhesive layer. 15 is formed on the polypropylene resin film, and as a laminate of the polypropylene resin film 14 and the adhesive layer 15, the polarizing film 10 and the transparent resin film 13 are laminated to produce a polarizing plate with an adhesive layer. Also good.

  Although the thickness of an adhesive layer is determined according to the adhesive force etc., it is about 1-40 micrometers normally. In order to obtain a thin polarizing plate with an adhesive layer without impairing properties such as processability and durability, the thickness of the adhesive layer is preferably about 3 to 25 μm. In addition, by setting the thickness of the pressure-sensitive adhesive layer to about 3 to 25 μm, it is possible to maintain brightness when the liquid crystal display device is viewed from the front or from an oblique direction, and to prevent blurring or blurring of the display image. it can.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited by these examples. In the examples, “part” and “%” representing the amount used and the content are based on weight unless otherwise specified.

(Production Example 1: Production of polypropylene resin film)
Propylene homopolymer (melting point = 153 ° C, crystallinity = 52%, polymerized continuously by gas phase polymerization using solid catalyst (Ziegler-Natta catalyst) containing magnesium, titanium and halogen as essential components) ) Was used as a polypropylene resin, melted and kneaded into a 90 mmφ extruder having a cylinder temperature of 250 ° C., and extruded from a 1250 mm wide T-die attached to the extruder. The extruded molten polypropylene resin is cooled by a casting roll (air gap is 90 mm) adjusted to 10 ° C. and an air chamber to obtain a protective film (polypropylene resin film) made of a polypropylene resin having a thickness of 40 μm. It was. The obtained film had an in-plane retardation of 13.1 nm and a haze value of 0.7%.

(Production Example 2: Production of UV-curable adhesive)
Trade name “Epicoat (registered trademark) YX8000” (diglycidyl ether of nuclear hydrogenated bisphenol A, having an epoxy equivalent of about 205 g / equivalent), which is a hydrogenated epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. 10 And 1 part of a trade name “CS7001”, a photosensitizer manufactured by Nippon Soda Co., Ltd., were mixed and defoamed to prepare an adhesive made of a curable resin composition containing an epoxy resin.

(Production Example 3: Production of Polarizing Plate)
First, a protective film (transparent resin film) made of triacetyl cellulose is bonded to one side of a polarizing film obtained by adsorbing and orienting iodine on a polyvinyl alcohol-based resin film via the ultraviolet curable adhesive obtained in Production Example 2. did. Separately, one side of the polypropylene resin film obtained in Production Example 1 was subjected to a corona discharge treatment under the condition of an integrated dose of 1,680 J / m ² , and the corona treatment surface was applied within 30 seconds after the corona discharge treatment. The polarizing film was bonded to the surface opposite to the side on which the triacetylcellulose film was bonded via the ultraviolet curable adhesive obtained in Production Example 2. Then, using an ultraviolet irradiation system (Fusion UV Systems), the adhesive is cured by irradiating ultraviolet rays from the polypropylene resin film side under the conditions of an output of 1,000 mW / cm ² and an irradiation amount of 500 mJ / cm ^2. It was. Thus, a polarizing plate was obtained in which a protective film made of triacetylcellulose was laminated on one side of the polarizing film, and a polypropylene resin film was laminated on the other side via the ultraviolet curable adhesive.

(Production Example 4: Sheet film for pressure-sensitive adhesive layer)
(A-1) 90.6 parts butyl acrylate, (A-3) 8.0 parts phenoxyethyl acrylate, (A-2) 1.0 parts 2-hydroxyethyl acrylate and 0. N-octyl-4-methylpyridinium hexafluorophosphate as an ionic compound with respect to 100 parts of an ethyl acetate solution of an acrylic resin copolymer (acrylic resin (A)) obtained by copolymerizing 4 parts (Melting point 44 ° C.) 0.8 parts, glycidoxypropyltrimethoxysilane 0.5 part as a silane coupling agent, and a trimethylolpropane adduct of tolylene diisocyanate as a crosslinking agent in an ethyl acetate solution (solid content 75) %) Is mixed in a solid content of 0.5 part, and ethyl acetate is added so that the solid content concentration is 13%. It was set as the coating liquid. The ethyl acetate solution of the acrylic resin (A) was prepared by using 0.14 parts of azobisisobutyronitrile (polymerization initiator) with respect to 100 parts of the monomer composition composed of the monomers. The mixture was radically polymerized in a container having an internal temperature of 54 to 56 ° C. for about 12 hours while adding ethyl acetate as appropriate so that the concentration of the resin would be 35%, and the final solid content was further increased using ethyl acetate. Is adjusted to 20%. The glass transition temperature of the acrylic resin (A) was −40 ° C. The glass transition temperature was measured by differential scanning calorimetry (DSC). The acrylic resin (A) had a polystyrene-equivalent weight average molecular weight Mw of 1,7110,000 and Mw / Mn of 4.3 by GPC. The structural unit derived from 2-hydroxyethyl acrylate which is a hydroxyl group-containing unsaturated monomer in the acrylic resin (A) is 1%, and derived from acrylic acid which is a carboxyl group-containing unsaturated monomer. The structural unit is 0.4%.

  After coating and drying the coating solution on a release treatment surface of a 38 μm thick polyethylene terephthalate film (separator) that has been subjected to a release treatment, a separator is further bonded onto the formed adhesive layer. As a result, a sheet-shaped antistatic pressure-sensitive adhesive having a thickness of 20 μm was prepared.

[Example 1]
The surface of the polarizing plate obtained in Production Example 3 on the side of the polypropylene resin film, and the separator release surface (pressure-sensitive adhesive layer surface) of the sheet obtained by removing the separator on one side from the sheet-like antistatic adhesive obtained in Production Example 4 ) And a corona discharge treatment at an integrated dose of 15.9 kJ / m ² , and within 5 minutes after the corona discharge treatment, the corona treatment surfaces are bonded together to form an adhesive layer on the polarizing plate. Thus, a polarizing plate with an adhesive layer was obtained.

[Comparative Example 1]
The surface of the polarizing plate obtained in Production Example 3 on the polypropylene resin film side was subjected to a corona discharge treatment with an integrated irradiation amount of 15.9 kJ / m ² . Within 5 minutes after corona discharge treatment, an acrylic sheet-like adhesive (with a separator on one side; a commercial product) containing butyl acrylate and acrylic acid as monomer components is bonded to the corona-treated surface. The polarizing plate with an adhesive layer was obtained.

[Evaluation test]
The pressure-sensitive adhesive layer-attached polarizing plate having the surface protective film obtained in Example 1 or Comparative Example 1 was allowed to stand for 1 day in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%, and then had a width of 25 mm and a length of about 200 mm. The surface protective film is peeled off, and the adhesion between the pressure-sensitive adhesive layer and the polypropylene resin film is evaluated at three points in the length direction using an adhesion evaluation device manufactured by Nippon System Group Co., Ltd. did. Evaluation was made using a styrene rubber having a hardness of 60 degrees, and when the sample was slid 20 times in a certain direction of 25 mm width while pressing with a pressing force of 0.4 MPa, the pressure-sensitive adhesive layer was removed from the polypropylene resin film. The three-point average of the peeled length was determined as the peel distance. The smaller the peeling distance, the better the adhesion. The measurement was performed in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%. The results are shown in Table 1.

  DESCRIPTION OF SYMBOLS 10 Polarizing film, 11, 12 Adhesive layer, 13 Transparent resin film, 14 Polypropylene-type resin film, 15 Adhesive layer.

Claims (8)

A polypropylene resin film is bonded to the polarizing film via an adhesive composed of a resin composition containing an epoxy compound that is cured by irradiation with active energy rays, and is opposite to the adhesive surface of the polypropylene resin film to the polarizing film. Adhesive layer is provided on the side surface,
The pressure-sensitive adhesive layer is
(A) (A-1) The following formula (I):

(In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a C 1-14 alkyl group which may be substituted with a C 1-10 alkoxy group.)
80 to 94% by weight of (meth) acrylic acid ester monomer represented by
(A-2) 0.1 to 5% by weight of (meth) acrylic monomer having a polar functional group;
(A-3) 5 to 15% by weight of a monomer having one olefinic double bond and at least one aromatic ring in the molecule;
An acrylic resin having a glass transition temperature of 0 ° C. or lower, obtained by radical polymerization of a monomer composition containing
(B) The polarizing plate with an adhesive layer currently formed from the adhesive composition containing a crosslinking agent. The monomer (A-3) having one olefinic double bond and at least one aromatic ring in the molecule is represented by the following formula (II):

(In the formula, R ₃ represents a hydrogen atom or a methyl group, n is an integer of 1 to 8, and R ₄ represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group.)
The polarizing plate with an adhesive layer according to claim 1, which is an aromatic ring-containing (meth) acrylic acid ester monomer represented by:   The polarizing plate with an adhesive layer according to claim 1 or 2, wherein the adhesive composition further contains (C) an ionic compound having an organic cation.   The polarizing plate with an adhesive layer according to any one of claims 1 to 3, wherein the ionic compound (C) having an organic cation has a melting point of 30 to 80 ° C.   The said polypropylene resin is a polarizing plate with an adhesive layer in any one of Claims 1-4 which consists of a homopolymer of a propylene substantially.   The said polypropylene resin is a polarizing plate with an adhesive layer in any one of Claims 1-4 which consists of a copolymer of the propylene and ethylene containing 10 weight% or less ethylene unit. The polarizing plate with an adhesive layer according to claim 1, wherein the polypropylene resin film has an in-plane retardation value (R ₀ ) of 30 nm or less.   The said polypropylene resin film is a polarizing plate with an adhesive layer in any one of Claims 1-7 whose haze value is 0.5% or less.

Images