JP2005316101A - Protection film for polarizing plate, polarizing plate with reflection preventing function and optical product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection film for polarizing plate having an excellent reflection preventing performance, excellent mechanical strength, and efficiently manufactured at low cost, and to provide a polarizing plate with reflection preventing function using the protection film for polarizing plate, and an optical product furnished with the polarizing plate having the reflection preventing function. <P>SOLUTION: The protection film for polarizing plate is composed by laminating a low diffraction index layer directly or via another layer on a surface of a base material film made of a transparent resin. The protection film for polarizing plate is characterized in that the low diffraction index layer has the refractive index of 1.25 to 1.36, and the variation in the reflectance after a steel wool test is within 50%. The polarizing plate with reflection preventing function is formed by using the protection film for polarizing plate, and the optical product is furnished with the polarizing plate with reflection preventing function. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polarizing plate protective film in which a low refractive index layer is laminated on a base film made of a transparent resin, a polarizing plate with an antireflection function, and an optical product including the polarizing plate.

  In recent years, in displays such as liquid crystal displays, it has been reduced on a transparent substrate (base film) in order to minimize external image reflection, reflection, glare, etc. on the screen and make the screen easier to see (improving visibility). An antireflection film having a refractive index layer is used.

Conventionally, as a low refractive index material used for a low refractive index layer, inorganic materials such as MgF ₂ and SiO ₂ ; organic materials such as a fluororesin; and the like are known. In order to obtain high antireflection performance, the difference in refractive index between these two layers is increased so that the minimum value of the reflectance between the layer on which the low refractive index layer is laminated and the low refractive index layer can be reduced. It is preferable to do this.

  However, since the low refractive index material used in the past has a small difference in refractive index from the base film, in order to obtain excellent antireflection performance, a higher refractive index is applied to the base film surface. It is necessary to form a multilayer film in which a high refractive index layer and a low refractive index layer are stacked, and there is a problem in terms of manufacturing cost.

  In order to solve this problem, several methods for forming a low refractive index layer having a low refractive index by increasing the porosity using hollow silica-based fine particles have been proposed. For example, Patent Document 1 discloses a method for forming a transparent film having a low refractive index by applying and drying a coating agent composition obtained by dispersing hollow silica-based fine particles in a matrix-forming material. . According to this method, high antireflection performance can be obtained without stacking the high refractive index layer and the low refractive index layer.

  However, since the strength of the obtained matrix is weak and the cohesive force is poor, the mechanical strength required as a polarizing plate protective film for liquid crystal display devices and the like may be insufficient, which has been a problem. In recent years, there are many things used outdoors, such as a mobile telephone, and the more excellent mechanical strength is calculated | required.

  On the other hand, Patent Document 2 proposes an antireflection film in which a single layer low refractive index layer having excellent mechanical strength is laminated on a base film. However, although this antireflection film is a single layer and excellent in mechanical strength, a sufficient antireflection performance cannot be obtained due to the high refractive index of the antireflection layer.

JP 2001-233611 A JP 2003-294907 A

  The present invention has been made in view of the state of the prior art, and has a superior antireflection performance, excellent mechanical strength, and a polarizing plate protective film that can be produced efficiently and at low cost. It is an object to provide a polarizing plate with an antireflection function using an antireflection film and an optical product including the polarizing plate with an antireflection function.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have a base film made of a transparent resin having a certain range of low refractive index, and a fluctuation in reflectance before and after the steel wool test is 50% or less. It has been found that a polarizing plate protective film excellent in antireflection performance and mechanical strength can be obtained efficiently and at low cost by laminating a low refractive index layer. Moreover, when a polarizing plate was laminated | stacked on this antireflection film, it discovered that the polarizing plate with an antireflection function excellent in antireflection performance and mechanical strength was obtained, and came to complete this invention.

  Thus, according to the first aspect of the present invention, there is provided a polarizing plate protective film in which a low refractive index layer is laminated directly or via another layer on one side of a base film made of a transparent resin, the low refractive index A polarizing plate protective film is provided, wherein the layer has a refractive index of 1.25 to 1.36, and a change in reflectance after a steel wool test is within 50%.

In the polarizing plate protective film of the present invention, it is preferable that the low refractive index layer comprises hollow fine particles of an inorganic compound.
In the polarizing plate protective film of the present invention, the transparent resin is preferably at least one of an alicyclic structure-containing polymer resin, a cellulose resin, or a polyester resin.

According to a second aspect of the present invention, the antireflection function is characterized in that the polarizing plate is laminated on one surface of the base film of the polarizing plate protective film of the present invention where the low refractive index layer is not provided. An attached polarizing plate is provided.
According to a third aspect of the present invention, there is provided an optical product comprising the polarizing plate with an antireflection function of the present invention.

According to the present invention, a polarizing plate protective film excellent in transparency, mechanical strength, and antireflection performance can be obtained efficiently and at low cost.
The polarizing plate with an antireflection function of the present invention uses the polarizing plate protective film of the present invention, and is excellent in antireflection performance and can be formed at low cost.
Since the optical product of the present invention comprises the polarizing plate with an antireflection function of the present invention, it is excellent in antireflection performance, visibility, etc., and can be produced at low cost.

  Hereinafter, the present invention will be described in terms of 1) a polarizing plate protective film, 2) a polarizing plate with an antireflection function, and 3) an optical product.

1) Polarizing plate protective film The polarizing plate protective film of the present invention is a polarizing plate protective film in which a low refractive index layer is laminated directly or via another layer on one side of a base film made of a transparent resin. The low-refractive index layer has a refractive index of 1.25 to 1.36, and a change in reflectance after a steel wool test is within 50%.

Although the base film used for this invention will not be restrict | limited especially if it consists of a synthetic resin (transparent resin) which is excellent in transparency, what consists of a synthetic resin whose total light transmittance is 80% or more by 1 mm thickness is preferable. Examples of the transparent resin constituting the base film include, for example, alicyclic structure-containing polymer resins, polyester polymer resins, cellulose polymer resins, polycarbonate polymer resins, polysulfone polymer resins, and polyether sulfone resins. Examples thereof include polymer resins, polystyrene polymer resins, polyolefin polymer resins, polyvinyl alcohol polymer resins, polyvinyl chloride polymer resins, and polymethacrylate polymer resins.
These transparent resins may be used alone or in combination of two or more.

  Among these, since the birefringence is small, cellulose polymer resins such as alicyclic structure-containing polymer resin, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. From the viewpoint of transparency, low hygroscopicity, dimensional stability, light weight, etc., alicyclic structure-containing polymer resin, triacetyl cellulose and polyethylene terephthalate are more preferable, and alicyclic Structure-containing polymer resins are particularly preferred.

  The alicyclic structure-containing polymer resin has an alicyclic structure in the repeating unit of the polymer resin, and the polymer resin having an alicyclic structure in the main chain and an alicyclic structure in the side chain. Any polymer resin can be used.

  Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferable from the viewpoint of thermal stability. Although there is no restriction | limiting in particular in carbon number which comprises an alicyclic structure, Usually, 4-30 pieces, Preferably it is 5-20 pieces, More preferably, it is 5-15 pieces. When the number of carbon atoms constituting the alicyclic structure is in this range, a base film excellent in heat resistance and flexibility can be obtained.

  The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer resin may be appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, more preferably. Is 90% by weight or more. If the number of repeating units having an alicyclic structure is too small, the heat resistance is undesirably lowered. In addition, repeating units other than the repeating unit which has an alicyclic structure in an alicyclic structure containing polymer resin are suitably selected according to the intended purpose.

  Specific examples of the alicyclic structure-containing polymer resin include (i) a norbornene polymer, (ii) a monocyclic olefin polymer, (iii) a cyclic conjugated diene polymer, and (iv) a vinyl alicyclic ring. Formula hydrocarbon polymers, hydrides thereof and the like. Among these, norbornene-based polymers are preferable from the viewpoints of transparency and moldability.

  Specific examples of the norbornene-based polymer include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, and those Hydrides of the above, addition polymers of norbornene monomers, addition copolymers with other monomers copolymerizable with norbornene monomers, and the like. Among these, from the viewpoint of transparency, a ring-opening (co) polymer hydride of a norbornene monomer is particularly preferable.

Examples of the norbornene-based monomer include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene), derivatives of these compounds (for example, those having a substituent in the ring), and the like. Here, examples of the substituent include an alkyl group, an alkylene group, an alkoxycarbonyl group, and a carboxyl group. In addition, these substituents may be the same or different and a plurality may be bonded to the ring. Norbornene monomers can be used alone or in combination of two or more.

  Other monomers capable of ring-opening copolymerization with norbornene monomers include, for example, monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene; Derivatives thereof; and the like.

Ring-opening polymers of norbornene monomers and ring-opening copolymers of norbornene monomers and other monomers copolymerizable therewith are polymerized in the presence of a ring-opening polymerization catalyst. Can be obtained.
As the ring-opening polymerization catalyst, a commonly used known catalyst can be used.

  Examples of other monomers that can be addition-copolymerized with norbornene-based monomers include, for example, α-olefins having 2 to 20 carbon atoms such as ethylene and propylene, and derivatives thereof; cycloolefins such as cyclobutene and cyclopentene, and these Derivatives; non-conjugated dienes such as 1,4-hexadiene and the like. These monomers can be used alone or in combination of two or more. In these, an alpha olefin is preferable and ethylene is more preferable.

  Norbornene monomer addition polymers and addition copolymers of norbornene monomers and other monomers copolymerizable therewith are obtained by polymerizing the monomers in the presence of an addition polymerization catalyst. Can be obtained. As the addition polymerization catalyst, a commonly used known catalyst can be used.

  Ring-opening polymer of norbornene monomer, ring-opening copolymer of norbornene monomer and other monomer capable of ring-opening copolymerization, addition polymer of norbornene monomer, and norbornene Addition of a known hydrogenation catalyst to the hydride of an addition polymer of a system monomer and another monomer copolymerizable therewith, preferably hydrogenates a carbon-carbon unsaturated bond by 90% or more. Can be obtained.

Examples of the monocyclic olefin-based polymer include addition polymers such as cyclohexene, cycloheptene, and cyclooctene.
Examples of the cyclic conjugated diene polymer include polymers obtained by 1,2-addition polymerization or 1,4-addition polymerization of cyclic conjugated diene monomers such as cyclopentadiene and cyclohexadiene.

  The vinyl alicyclic hydrocarbon polymer is a polymer having a repeating unit derived from vinylcycloalkane or vinylcycloalkene. Examples of the vinyl alicyclic hydrocarbon polymer include polymers of vinyl alicyclic hydrocarbon compounds such as vinyl cycloalkanes such as vinyl cyclohexane, vinyl cycloalkenes such as vinyl cyclohexene, and hydrides thereof; styrene, α-methyl Examples thereof include hydrides of aromatic ring portions of polymers of vinyl aromatic hydrocarbon compounds such as styrene.

  The vinyl alicyclic hydrocarbon polymer is a random copolymer of a vinyl alicyclic hydrocarbon compound or a vinyl aromatic hydrocarbon compound and another monomer copolymerizable with these monomers, It may be a copolymer such as a block copolymer and a hydride thereof. Examples of the block copolymerization include diblock, triblock, or more multiblock and gradient block copolymerization, but are not particularly limited.

  The molecular weight of the transparent resin is usually 10,000 to 300 in terms of polyisoprene or polystyrene equivalent weight average molecular weight measured by gel permeation chromatography using cyclohexane as a solvent (toluene if the polymer resin does not dissolve). 5,000, preferably 15,000-250,000, more preferably 20,000-200,000, the mechanical strength and moldability of the base film are highly balanced and suitable. .

  Although the glass transition temperature of the said transparent resin should just be selected suitably according to a use purpose, Preferably it is 80 degreeC or more, More preferably, it is the range of 100-250 degreeC. A base film made of a transparent resin having a glass transition temperature in such a range is excellent in durability without causing deformation or stress in use under high temperature and high humidity.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the transparent resin is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0 to 6.0, more preferably 1. .1 to 4.0. By adjusting the molecular weight distribution in such a range, the mechanical strength and molding processability of the base film are well balanced.

  The base film used in the present invention can be obtained by molding the transparent resin material into a film by a known molding method.

  Examples of a method for forming the transparent resin material into a film include a solution casting method and a melt extrusion method. Among these, the melt extrusion molding method is preferable because the content of volatile components in the film and the thickness unevenness can be reduced. Further, examples of the melt extrusion method include a method using a die such as a T die, an inflation method, and the like, but a method using a T die is preferable in terms of excellent productivity and thickness accuracy.

  When adopting a method using a T die as a method for forming a film, the melting temperature of the transparent resin in the extruder having the T die is preferably 80 to 180 ° C. higher than the glass transition temperature of the transparent resin. More preferably, the temperature is higher by 100 to 150 ° C. If the melting temperature in the extruder is excessively low, the fluidity of the transparent resin may be insufficient. Conversely, if the melting temperature is excessively high, the resin may be deteriorated.

  Furthermore, it is preferable to pre-dry the transparent resin to be used before forming into a film. The preliminary drying is performed using, for example, a hot air dryer or the like in the form of pellets or the like. The drying temperature is preferably 100 ° C. or more, and the drying time is preferably 2 hours or more. By performing preliminary drying, it is possible to reduce the amount of volatile components in the film and to prevent foaming of the transparent resin to be extruded.

The base film used in the present invention preferably has a saturated water absorption of less than 0.05%. By using a material having a saturated water absorption rate of less than 0.05%, when a low refractive index layer is formed, moisture is not released and the quality is not deteriorated and productivity is not lowered. In addition, the base film does not expand and contract due to moisture absorption due to long-term use, and the low refractive index layer does not peel from the base film.
The saturated water absorption rate of the base film can be measured according to JIS K7209.

  Moreover, as a base film, what gave the surface modification process to the single side | surface or both surfaces can be used. By performing the surface modification treatment, adhesion to the low refractive index layer and other layers described later can be improved. Examples of the surface modification treatment include energy beam irradiation treatment and chemical treatment.

  Examples of the energy ray irradiation treatment include corona discharge treatment, plasma treatment, electron beam irradiation treatment, ultraviolet ray irradiation treatment, and the like. From the viewpoint of treatment efficiency, corona discharge treatment and plasma treatment are preferred, and corona discharge treatment is particularly preferred. The chemical treatment may be performed by immersing in an aqueous oxidizing agent solution such as potassium dichromate solution or concentrated sulfuric acid and then thoroughly washing with water. It is effective to shake in the immersed state, but there is a problem that the surface dissolves or transparency decreases when treated for a long period of time, depending on the reactivity, concentration, etc. of the chemical used, the treatment time etc. It needs to be adjusted.

  Although the thickness of a base film is 10-1000 micrometers normally, from a viewpoint of transparency and mechanical strength, Preferably it is 30-300 micrometers, More preferably, it is 40-200 micrometers.

  In the polarizing plate protective film of the present invention, it is preferable to interpose another layer between the base film and the low refractive index layer. Examples of the other layers include a hard coat layer and a primer layer.

  The hard coat layer is formed for the purpose of reinforcing the surface hardness, repeated fatigue resistance and mechanical strength of the base film. The material for forming the hard coat layer is not particularly limited as long as it shows a hardness of “2H” or higher in the pencil hardness test specified in JIS K5400. Examples thereof include organic hard coat materials such as organic silicone, melamine, epoxy, and acrylic; inorganic hard coat materials such as silicon dioxide; and the like. Of these, the use of a polyfunctional acrylate hard coat material is preferred from the viewpoint of good adhesion and excellent productivity.

  The method for forming the hard coat layer is not particularly limited. For example, there is a method in which a hard coat layer forming coating solution is applied onto a substrate film by a known coating method, and is irradiated with ultraviolet rays and cured. Can be mentioned. Although the thickness of a hard-coat layer is not specifically limited, Usually, 0.5-30 micrometers, Preferably it is 3-15 micrometers.

  The primer layer is formed for the purpose of imparting and improving the adhesion between the base film and the low refractive index layer. Examples of the material constituting the primer layer include polyester urethane resins, polyether urethane resins, polyisocyanate resins, polyolefin resins, resins having a hydrocarbon skeleton in the main chain, polyamide resins, acrylic resins, and polyester resins. Examples thereof include resins, vinyl chloride / vinyl acetate copolymers, chlorinated rubber, cyclized rubber, and modified products obtained by introducing polar groups into these polymers. Among these, a modified product of a resin having a hydrocarbon skeleton in the main chain and a modified product of a cyclized rubber can be suitably used.

  Examples of the resin having a hydrocarbon skeleton in the main chain include a polybutadiene skeleton or a resin having a polybutadiene skeleton hydrogenated to at least a part thereof, specifically, a polybutadiene resin, a hydrogenated polybutadiene resin, a styrene / butadiene / styrene. Examples thereof include a block copolymer (SBS copolymer), a hydrogenated product thereof (SEBS copolymer), and the like. Among these, a modified product of a hydrogenated product of a styrene / butadiene / styrene block copolymer can be suitably used.

  As a compound for introducing a polar group used for obtaining a modified product of a polymer, a carboxylic acid or a derivative thereof is preferable. For example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid; halides, amides, imides, anhydrides and esters of unsaturated carboxylic acids such as maleyl chloride, maleimide, maleic anhydride and citraconic anhydride And the like; and the like. Among these, a modified product with an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride is excellent in adhesion, and thus can be suitably used. Among the unsaturated carboxylic acids or anhydrides thereof, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are more preferable, and maleic acid and maleic anhydride are particularly preferable. These unsaturated carboxylic acids and the like can be modified by mixing two or more kinds.

  The method for forming the primer layer is not particularly limited, and examples thereof include a method in which a primer layer forming coating solution is applied on a base film by a known coating method. The thickness of the primer layer is not particularly limited, but is usually 0.01 to 5 μm, preferably 0.1 to 2 μm.

  Moreover, various compounding agents can be added to the resin materials constituting the base film, hard coat layer and primer layer as desired. The compounding agent is not particularly limited as long as it is usually used in thermoplastic resin materials. For example, antioxidants such as phenolic antioxidants, phosphoric acid antioxidants, sulfur antioxidants; UV absorbers such as triazole UV absorbers, benzoate UV absorbers, benzophenone UV absorbers, acrylate UV absorbers, metal complex UV absorbers; light stabilizers such as hindered amine light stabilizers; dyes and pigments Colorants such as: Aliphatic alcohol esters, polyhydric alcohol esters, fatty acid amides, inorganic particles, etc. Lubricants: triester plasticizers, phthalic acid ester plasticizers, fatty acid-basic acid ester plasticizers, oxyacid esters Plasticizers such as plasticizers; antistatic agents such as fatty acid esters of polyhydric alcohols; and the like.

  The low refractive index layer of the polarizing plate protective film of the present invention has a refractive index of 1.25 to 1.36, preferably 1.25 to 1.33, and a change in reflectance after the steel wool test is 50. % Or less, preferably 30% or less.

When the refractive index of the low refractive index layer is less than 1.25, the strength of the low refractive index layer is weak and the desired mechanical strength required as a polarizing plate protective film cannot be obtained. The antireflection effect may not be obtained.
The refractive index can be obtained by measuring using, for example, a known spectroscopic ellipsometer.

The change in reflectance after the steel wool test is the ratio of the change in reflectance measured before and after the test of rubbing the surface of the polarizing plate protective film 10 times with a load of 0.05 MPa applied to the steel wool. Where R ^{b is} the reflectance before the steel wool test and R ^a is the reflectance after the steel wool test.

  The reflectance can be obtained as a reflectance at a wavelength of 550 nm by measuring a reflection spectrum at a predetermined incident angle using, for example, a known spectrophotometer. The reflectance of the low refractive index layer is preferably 0.5% or less, more preferably 0.3% or less. It can be said that a material having a small variation in reflectance is excellent in mechanical strength.

  Furthermore, the low refractive index layer used in the present invention preferably comprises hollow fine particles of an inorganic compound. The inorganic compound hollow fine particles are not particularly limited as long as they are inorganic hollow fine particles in which cavities are formed inside the outer shell, but silica-based hollow fine particles are preferable.

As the inorganic compound, an inorganic oxide is common. As the inorganic _{oxide, SiO 2, Al 2 O 3} , B 2 O 3, TiO 2, ZrO 2, SnO 2, Ce 2 O 3, P 2 O 5, Sb 2 O 3, MoO 3, ZnO 2, WO One or two or more of ₃ or the like can be mentioned. Examples of the two or more inorganic oxides include TiO ₂ —Al ₂ O ₃ , TiO ₂ —ZrO ₂ , In ₂ O ₃ —SnO ₂ , and Sb ₂ O ₃ —SnO ₂ . These can be used alone or in combination of two or more.

  As the inorganic hollow fine particles, (A) an inorganic oxide single layer, (B) a single layer of a composite oxide or mixed oxide composed of different types of inorganic oxides, and (C) the above (A) and (B) The thing including the double layer of this can be used.

The outer shell may be porous with pores, or the pores may be closed and the cavity sealed with respect to the outside of the outer shell.
The outer shell is preferably a plurality of inorganic oxide coating layers comprising an inner first inorganic oxide coating layer and an outer second inorganic oxide coating layer. By providing the second inorganic oxide coating layer on the outer side, the fine pores of the outer shell are closed to make the outer shell dense, and furthermore, the inorganic hollow fine particles in which the inner cavity is sealed can be obtained.

  The thickness of the outer shell is preferably in the range of 1 to 50 nm, particularly 5 to 20 nm. If the thickness of the outer shell is less than 1 nm, the inorganic hollow fine particles may not maintain a predetermined particle shape. On the other hand, when the thickness of the outer shell exceeds 50 nm, the cavities in the inorganic hollow fine particles are small, and as a result, the ratio of the cavities may be reduced and the refractive index may not be sufficiently lowered. Furthermore, the thickness of the outer shell is preferably in the range of 1/50 to 1/5 of the average particle diameter of the inorganic hollow fine particles.

  When the first inorganic oxide coating layer and the second inorganic oxide coating layer are provided as outer shells as described above, the total thickness of these layers may be in the range of 1 to 50 nm. For the densified outer shell, the thickness of the second inorganic oxide coating layer is preferably in the range of 20 to 40 nm.

  The cavity may contain the solvent used when preparing the inorganic hollow fine particles and / or a gas that enters during drying, and a precursor material for forming the cavity described later remains in the cavity. Also good.

  The precursor material is a porous material that remains after removing some of the constituent components of the core particles from the core particles surrounded by the outer shell. As the core particles, porous composite oxide particles made of different types of inorganic oxides are used. The precursor material may remain slightly attached to the outer shell or may occupy most of the interior of the cavity.

  The solvent or gas may be present in the pores of the porous material. When the removal amount of the constituent components of the core particles at this time increases, the volume of the cavity increases, and inorganic hollow fine particles having a low refractive index are obtained. The transparent coating obtained by blending these inorganic hollow fine particles reflects with a low refractive index. Excellent prevention performance.

  The average particle diameter of the inorganic hollow fine particles is not particularly limited, but is preferably in the range of 5 to 2000 nm, and more preferably 20 to 100 nm. If it is smaller than 5 nm, the effect of lowering the refractive index due to hollowness is small. Conversely, if it is larger than 2000 nm, the transparency is extremely deteriorated, and the contribution due to diffuse reflection increases. Here, the average particle diameter is a number average particle diameter by observation with a transmission electron microscope.

  The method for producing inorganic hollow fine particles as described above is described in detail in, for example, Japanese Patent Application Laid-Open No. 2001-233611, and the inorganic hollow fine particles that can be used in the present invention are produced based on the method described therein. In addition, commercially available inorganic hollow fine particles can also be used.

  The blending amount of the hollow fine particles of the inorganic compound is not particularly limited, but is preferably 10 to 30% by weight with respect to the entire low refractive index layer. When the blending amount is within this range, a polarizing plate protective film having both low refractive index properties and mechanical strength can be obtained.

The hollow fine particles of the inorganic compound can also be used in the form of a dispersion. The type of the organic solvent used in the dispersion is not particularly limited. For example, lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol; ethylene glycol, ethylene glycol monobutyl ether, acetic acid Ethylene glycol derivatives such as ethylene glycol monoethyl ether; diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; diacetone alcohol; aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane and n-heptane; And esters such as ethyl and butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone;
These organic solvents can be used alone or in combination of two or more.

  The low refractive index layer was formed by laminating a composition containing hollow inorganic fine particles (hereinafter sometimes referred to as “low refractive index layer forming composition”) on a base film or a base film. It can be formed by coating on the surface of other layers and subjecting to drying / heating treatment as necessary. In order for the low refractive index layer to be formed to have the above-described refractive index and reflectance fluctuation, the low refractive index layer-forming composition contains a metal oxide composite. preferable.

The metal oxide complex is formed from one or more compounds selected from the group consisting of the following (a) to (c), and has — (OM) _m —O in the molecule. -(In formula, M represents a metal atom or a metalloid atom, m represents a natural number.) What has a bond is more preferable.

(A) A compound represented by formula (1): MX _n .
(B) At least one partial hydrolysis product of the compound represented by the formula (1).
(C) At least one complete hydrolysis product of the compound represented by the formula (1).

In the compound represented by the formula (1) of the above (a), in the formula (1), M represents a metal atom or a metalloid atom.
Examples of the metal atom or metalloid atom include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as magnesium, calcium, barium and strontium; periodic table 3B of boron, aluminum, gallium, indium and thallium Element; Group 4B element of periodic table such as silicon, germanium, tin, lead; Group 5B element of periodic table such as phosphorus, arsenic, antimony; scandium, titanium, vanadium, iron, nickel, copper, zinc, yttrium, Transition metal elements such as zirconium, niobium, tantalum, and tungsten; lanthanoids such as lanthanum, cerium, and neodymium; and the like. Among these, a periodic table group 3B element, a periodic table group 4B element, and a transition metal element are preferable, aluminum, silicon, titanium, and zirconium are more preferable, and silicon (Si) is further preferable.

X is a halogen atom such as a chlorine atom or a bromine atom; a monovalent hydrocarbon group which may have a substituent; an oxygen atom; an organic acid radical such as an acetate radical or a nitrate radical; a β-diketonate such as acetylacetonate A group; an inorganic acid group such as a nitrate group or a sulfate group; an alkoxy group such as a methoxy group, an ethoxy group, an n-propoxy group or an n-butoxy group; or a hydroxyl group.
N represents the valence of M (metal atom or metalloid atom). When n is 2 or more, X may be the same or different.

Among these, as the compound represented by the formula (1), the formula (2): R _w SiY _4-w (wherein R represents a monovalent hydrocarbon group which may have a substituent). And w represents an integer of 0 to 2, and when w is 2, R may be the same or different, Y represents a hydrolyzable group, and Y may be the same or different. A silicon compound represented by formula (1) may be particularly preferable.

  Examples of the monovalent hydrocarbon group which may have a substituent include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group; a cyclopentyl group, A cycloalkyl group such as a cyclohexyl group; an aryl group optionally having a substituent such as a phenyl group, a 4-methylphenyl group, a 1-naphthyl group, and a 2-naphthyl group; an alkenyl group such as a vinyl group and an allyl group; Aralkyl groups such as benzyl group, phenethyl group and 3-phenylpropyl group; Haloalkyl groups such as chloromethyl group, γ-chloropropyl group and 3,3,3-trifluoropropyl group; Alkenyl such as γ-methacryloxypropyl group Carbonyloxyalkyl group; an epoxy group having an epoxy group such as γ-glycidoxypropyl group or 3,4-epoxycyclohexylethyl group It can be exemplified, and the like; alkyl groups having an amino group such as 3-aminopropyl group; an alkyl group having a mercapto group such as γ- mercaptopropyl group; kill group. Among these, an alkyl group having 1 to 4 carbon atoms and a phenyl group are preferable because of easy synthesis and availability.

Y represents a hydrolyzable group. Here, the hydrolyzable group refers to a group that is hydrolyzed in the presence of an acid or a base catalyst as desired to form a — (O—Si) _m —O— bond.

  Specific examples of the hydrolyzable group include alkoxy groups such as methoxy group, ethoxy group and propoxy group; acyloxy groups such as acetoxy group and propionyloxy group; oxime group (—O—N═C—R ′ (R ″)) ), Enoxy group (—O—C (R ′) ═C (R ″) R ′ ″), amino group, aminoxy group (—O—N (R ′) R ″), amide group (—N (R ') -C (= O) -R ") and the like. In these groups, R ′, R ″, and R ′ ″ each independently represent a hydrogen atom or a monovalent hydrocarbon group. Among these, Y is preferably an alkoxy group from the standpoint of availability. .

  The silicon compound represented by the formula (2) is preferably a silicon compound in which w is an integer of 0 to 2 in the formula (2). Specific examples thereof include alkoxysilanes, acetoxysilanes, oxime silanes, enoxysilanes, aminosilanes, aminoxysilanes, amidosilanes and the like. Among these, alkoxysilanes are more preferable because of their availability.

  In the formula (2), examples of the tetraalkoxysilane in which w is 0 include tetramethoxysilane and tetraethoxysilane. Examples of the organotrialkoxysilane in which w is 1 include methyltrimethoxysilane and methyltriethoxy. Examples include silane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, and the like. Examples of the diorganodialkoxysilane in which w is 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.

  The molecular weight of the compound represented by the formula (1) is not particularly limited, but is preferably 40 to 300, and more preferably 100 to 200.

  At least one partial hydrolysis product (hereinafter referred to as “compound (3)”) of the compound represented by formula (1) of (b), and represented by formula (1) of (c). At least one complete hydrolysis product of the compound (hereinafter referred to as “compound (4)”) is obtained by fully or partially hydrolyzing one or more of the compounds represented by the formula (1). Can be obtained by condensation.

Compound (3) and Compound (4) include, for example, a metal tetraalkoxide represented by M (Or) ₄ (M represents the same meaning as described above, and r represents a monovalent hydrocarbon group). It can be obtained by hydrolysis in the presence of water in an amount such that the ratio [H ₂ O] / [Or] is 1.0 or more, for example 1.0 to 5.0, preferably 1.0 to 3.0. it can.
Hydrolysis can be performed by stirring the whole volume at a temperature of 5 to 100 ° C. for 2 to 100 hours.

  When hydrolyzing the compound represented by the formula (1), a catalyst may be used as necessary. The catalyst to be used is not particularly limited, but the obtained partial hydrolyzate and / or hydrolyzate is likely to have a two-dimensional cross-linked structure, and the condensed compound is easily made porous. From the viewpoint of shortening the time required, an acid catalyst is preferred.

  The acid catalyst to be used is not particularly limited. For example, acetic acid, chloroacetic acid, citric acid, benzoic acid, dimethylmalonic acid, formic acid, propionic acid, glutaric acid, glycolic acid, maleic acid, malonic acid, toluenesulfonic acid, Organic acids such as acids; inorganic acids such as hydrochloric acid, nitric acid, and halogenated silane; acidic sol-like fillers such as acidic colloidal silica and oxidized titania sol; These acid catalysts can be used alone or in combination of two or more.

  Instead of the acid catalyst, a base catalyst such as an aqueous solution of an alkali metal or alkaline earth metal hydroxide such as sodium hydroxide or calcium hydroxide, an aqueous ammonia or an aqueous solution of amines may be used.

  The molecular weights of the compound (3) and the compound (4) are not particularly limited, but usually the weight average molecular weight is in the range of 200 to 5,000.

  The composition for forming a low refractive index layer may be preferably applied to a base film or other layer to form a coating film, and it may be preferable that at least partial hydrolysis of the matrix forming material occurs. From the above, it is preferable to include water or a mixture of water and another organic solvent.

  Examples of the organic solvent to be used include lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol and isobutanol; ethylene glycol derivatives such as ethylene glycol, ethylene glycol monobutyl ether and ethylene glycol monoethyl ether; diethylene glycol, And hydrophilic organic solvents such as diethylene glycol derivatives such as diethylene glycol monobutyl ether; diacetone alcohol; and combinations of two or more thereof.

  In combination with the hydrophilic organic solvent, aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane and n-heptane; esters such as ethyl acetate and butyl acetate; methyl ethyl ketone and methyl Ketones such as isobutyl ketone; oximes such as methyl ethyl ketoxime; and combinations of two or more of these; and the like can be used.

  When the composition for forming a low refractive index layer contains the compounds (a) and (b), it preferably contains a curing catalyst. As a result, when the composition for forming a low refractive index layer is applied to the surface of the base film to form a coating film and dried, the condensation reaction is promoted to increase the crosslinking density in the coating film, and the water resistance of the coating film And the effect which can improve alkali resistance can be acquired.

  Examples of the curing catalyst to be used include metal chelate compounds such as Ti chelate compounds and Zr chelate compounds; organic acids and the like.

  The composition for forming a low refractive index layer may further contain a known silane coupling agent. When a low refractive index layer is formed on a base film using the composition for forming a low refractive index layer by including a silane coupling agent, the adhesion between the base film and the low refractive index layer is improved. May improve.

  The method for coating the composition for forming a low refractive index layer on the base film is not particularly limited, and a known coating method can be employed. Examples of the coating method include a wire bar coating method, a dip method, a spray method, a spin coating method, and a roll coating method.

After obtaining the coating film of the composition for forming a low refractive index layer, the low refractive index layer can be formed by drying and heating and firing as necessary. The temperature of the heating performed as necessary is usually 50 to 200 ° C, preferably 80 to 150 ° C.
The thickness of the obtained low refractive index layer is usually 10 to 1000 nm, preferably 50 to 500 nm.

  The polarizing plate protective film of the present invention can further form an antifouling layer on the low refractive index layer in order to protect the low refractive index layer and enhance the antifouling performance.

  The material for forming the antifouling layer is not particularly limited as long as the function of the low refractive index layer is not inhibited and the required performance as the antifouling layer is satisfied. Usually, a compound having a hydrophobic group can be preferably used. As specific examples, a perfluoroalkylsilane compound, a perfluoropolyethersilane compound, or a fluorine-containing silicone compound can be used. As a method for forming the antifouling layer, for example, physical vapor deposition methods such as vapor deposition and sputtering; chemical vapor deposition methods; wet low refractive index layer forming methods; . The thickness of the antifouling layer is not particularly limited, but is usually preferably 20 nm or less, and more preferably 1 to 10 nm.

  The layer structural example of the polarizing plate protective film of this invention is shown in FIG. A polarizing plate protective film 20 shown in FIG. 1 has a structure in which a low refractive index layer 14 containing hollow fine particles 14 a is laminated via a hard coat layer 12 formed on a base film 10. The polarizing plate protective film of this invention is not limited to what is shown in FIG. 1, What is necessary is just to have a low refractive index layer on a base film at least.

  Even after the steel wool test, the polarizing plate protective film of the present invention has excellent mechanical strength with no scratches observed on the film surface by visual observation.

  The polarizing plate protective film of the present invention is, for example, a mobile phone, a digital information terminal, a pager (registered trademark), navigation, a liquid crystal display for vehicle use, a liquid crystal monitor, a light control panel, a display for OA equipment, a display for AV equipment, etc. It is useful as a protective film for polarizing plates such as various liquid crystal display elements, electroluminescence display elements, and touch panels.

2) Polarizing plate with antireflection function In the polarizing plate with antireflection function of the present invention, a polarizing plate is laminated on one side of the base film of the polarizing plate protective film of the present invention where the low refractive index layer is not provided. It is characterized by.

  The polarizing plate is not particularly limited as long as it has a function as a polarizing plate. For example, a polyvinyl alcohol (PVA) -based or polyene-based polarizing plate can be used.

  The manufacturing method of a polarizing plate is not specifically limited. As a method of manufacturing a PVA-based polarizing plate, a method of stretching uniaxially after iodine ions are adsorbed on a PVA-based film, a method of adsorbing iodine ions after stretching a uniaxially stretched PVA-based film, A method of simultaneously performing iodine ion adsorption and uniaxial stretching, a method of stretching a uniaxial film after dyeing a PVA film with a dichroic dye, a method of stretching a uniaxial film and then adsorbing with a dichroic dye, a PVA system The method of performing simultaneously dyeing | staining with a dichroic dye and uniaxial stretching to a film is mentioned. In addition, as a method for producing a polyene-based polarizing plate, a method of heating and dehydrating in the presence of a dehydration catalyst after stretching a PVA-based film uniaxially, and in the presence of a dehydrochlorination catalyst after stretching a polyvinyl chloride-based film uniaxially. And publicly known methods such as heating and dehydrating.

  Lamination | stacking with a polarizing plate protective film and a polarizing plate can be bonded together using appropriate adhesion means, such as an adhesive agent and an adhesive. Examples of the adhesive or pressure-sensitive adhesive include acrylic, silicone, polyester, polyurethane, polyether, rubber, and the like. Among these, from the viewpoint of heat resistance and transparency, it is preferable to use an acrylic material.

  In the polarizing plate with an antireflection function of the present invention, a protective film may be laminated via an adhesive or an adhesive layer on the surface of the polarizing plate on which the polarizing plate protective film of the present invention is not laminated. Good. As a protective film, what consists of material with low optical anisotropy is preferable. The material having low optical anisotropy is not particularly limited, and examples thereof include cellulose esters such as triacetyl cellulose and alicyclic structure-containing polymers. However, transparency, low birefringence, dimensional stability, etc. From the viewpoint of superiority, an alicyclic structure-containing polymer is preferred. Examples of the alicyclic structure-containing polymer include those described in the explanation part of the base film. Examples of the adhesive or pressure-sensitive adhesive include those similar to the adhesive or pressure-sensitive adhesive used for laminating the polarizing plate protective film and the polarizing plate.

  An example of the layer structure of the polarizing plate with antireflection function of the present invention is shown in FIG. The polarizing plate 30 with an antireflection function shown in FIG. 2 has a polarizing plate 18 on the surface side of the polarizing plate protective film 20 of the present invention on which the low refractive index layer 14 is not provided, with an adhesive or pressure-sensitive adhesive layer 16 interposed therebetween. And the protective film 10a is laminated on the other surface side of the polarizing plate 18 with an adhesive or pressure-sensitive adhesive layer 16 interposed therebetween.

  Since the polarizing plate with an antireflection function of the present invention uses the polarizing plate protective film of the present invention, the polarizing plate has excellent mechanical strength.

3) Optical product The optical product of the present invention includes the polarizing plate with an antireflection function of the present invention. Preferable specific examples of the optical product of the present invention include a liquid crystal display device, a touch panel, an electroluminescence display device, a plasma panel display device and the like.

  As an example of an optical product including the polarizing plate with antireflection function of the present invention, FIG. 3 shows a layer configuration example of a liquid crystal display device including the polarizing plate with antireflection function of the present invention. The liquid crystal display device shown in FIG. 3 includes a polarizing plate 40, a retardation plate 50, a liquid crystal cell 60, and the polarizing plate 30 with an antireflection function of the present invention in order from the bottom. The polarizing plate 30 with an antireflection function is formed on the liquid crystal cell 60 by being bonded to the polarizing plate surface via an adhesive or pressure-sensitive adhesive layer (not shown). In the liquid crystal cell 60, for example, as shown in FIG. 4, two electrode substrates 80 each having a transparent electrode 70 are arranged at a predetermined interval with the transparent electrodes 70 facing each other, and a liquid crystal 90 is disposed in the gap. It is produced by enclosing. In FIG. 4, 100 is a seal.

  The liquid crystal mode of the liquid crystal 90 is not particularly limited. The liquid crystal modes include TN (Twisted Nematic), STN (Super Twisted Nematic), HAN (Hybrid Alignment Nematic), VA (Vertical Alignment), MVA (Multiple Alignment). OCB (Optical Compensated Bend) type and the like.

  In addition, the liquid crystal display device shown in FIG. 4 has a normally white mode that is bright when the applied voltage is low, a dark display when the applied voltage is high, a dark display when the applied voltage is low, and a normally black mode that is bright when the applied voltage is high. Can be used.

  The optical product of the present invention is excellent in visibility. In other words, when the display panel is darkly displayed and visually observed from the front, a point or surface with excessively high brightness may appear and it may be difficult to see, have discomfort (glare), or may be reflected. Absent. This excellent visibility does not change even after the steel wool test.

Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.
The test and evaluation in an Example and a comparative example were performed with the following method.

Using a refractive index high-speed spectroscopic ellipsometry (model number: M-2000U, manufactured by JA Woollam), a measurement wavelength of 400-1000 nm and an incident angle of 55, 60, and 65 degrees were measured, respectively. Calculated.

The surface was reciprocated 10 times in a state where a load of 0.05 MPa was applied to the scratch-resistant steel wool # 0000, and the surface state after the test was visually observed.
○: Scratches are not recognized.
Δ: Slight scratches are observed.
X: Scratches are observed.

Reflectance and reflectance fluctuation spectrophotometer (UV-visible near-infrared spectrophotometer V-570, manufactured by JASCO Corporation) was used to measure the reflection spectrum at an incident angle of 5 degrees, and the reflectance at a wavelength of 550 nm was determined. .
The reflectance fluctuation was obtained by the following formula. R ^b represents the reflectance before the steel wool test, and R ^a represents the reflectance after the test.

The visibility liquid crystal display element was darkly displayed and the substrate was visually observed from the front side, and evaluated in the following three stages. Glare refers to discomfort and difficulty in seeing when a point or surface with excessively high brightness is visible in the field of view.
○: No glare or reflection is seen.
Δ: Some glare and reflection are seen.
X: Glare and reflection are seen.

(Production Example 1) Production of base film Pellets of norbornene-based polymer (trade name: ZEONOR 1420R, manufactured by Nippon Zeon Co., Ltd., glass transition temperature: Tg 136 ° C., saturated water absorption: less than 0.01% by weight), air It dried for 4 hours at 110 degreeC using the distribute | circulated hot air dryer. The pellets were then coated with a coat hanger type T die with a lip width of 650 mm with an average surface height Ra = 0.05 μm and a chrome plated tip of the die lip on which a leaf disk-shaped polymer filter (filtration accuracy 30 μm) was installed. A long base film 1A having a width of 600 mm was obtained by melt extrusion at 260 ° C. using a short shaft extruder having the same. The content of the volatile component of the obtained long base film was 0.01% by weight or less, and the saturated water absorption was 0.01% by weight or less. Moreover, the film thickness of this base film was 40 micrometers.

(Production Example 2) Preparation of hard coat agent Hexafunctional urethane acrylate oligomer (trade name: NK Oligo U-6HA, manufactured by Shin-Nakamura Chemical Co., Ltd.) 30 parts, butyl acrylate 40 parts, isobornyl methacrylate (trade name: NK Ester 1B (Manufactured by Shin-Nakamura Chemical Co., Ltd.) 30 parts and 2,2-dimethoxy-1,2-diphenylethane-1-one 10 parts were mixed with a homogenizer to prepare a hard coat agent comprising an ultraviolet curable resin composition.

(Production Example 3) Preparation of primer solution Hydrogenated maleic anhydride-modified styrene / butadiene / styrene block copolymer (trade name: Tuftec M1913, manufactured by Asahi Kasei Co., Ltd., melt index value: 200 g, 1.0 g at 5 kg load) / 10 minutes, styrene block content 30% by weight, hydrogenation rate 80% or more, maleic anhydride addition amount 2%) are dissolved in a mixed solvent of 8 parts of xylene and 40 parts of methyl isobutyl ketone, A tetrafluoroethylene filter was filtered to prepare only the complete solution as a primer solution.

(Production Example 4) Preparation of coating solution for forming low refractive index layer Tetramethoxysilane oligomer (trade name: methyl silicate 51, manufactured by Colcoat Co., Ltd.), methanol, water, and 0.01N hydrochloric acid aqueous solution were used in a mass ratio of 21:36. : 2: 2 and the mixture was stirred for 2 hours in a high-temperature bath at 25 ° C. to adjust the weight average molecular weight to 850 to obtain a silicone resin.
Next, a hollow silica isopropanol dispersion sol (manufactured by Catalyst Kasei Kogyo Co., Ltd., solid content 20% by weight, average primary particle diameter of about 35 nm, outer shell thickness of about 8 nm) is added to the silicone resin as hollow silica fine particles, and hollow silica fine particles / silicone resin are added. (Condensation compound equivalent) is blended so that the weight ratio is 8: 2 based on solid content, and then diluted with methanol so that the total solid content is 1%, and coating solution A for forming a low refractive index layer is obtained. Prepared.

Production Example 5 Preparation of Silicon Alkoxide Solution A Solution A was prepared by mixing tetramethoxysilane oligomer (trade name: methyl silicate 51, manufactured by Colcoat Co.) with methanol at a mass ratio of 47:71. In addition, liquid B was prepared by mixing water, aqueous ammonia (28 wt%), and methanol in a weight ratio of 60: 1.2: 97.2. And A liquid and B liquid were mixed by ratio of 16:17, and the silicon alkoxide solution A was prepared.

(Production Example 6) Preparation of silicon alkoxide solution B Silicon alkoxide solution B was prepared in the same manner as in Production Example 4 except that tetramethoxysilane oligomer and methanol were blended in a mass ratio of 47:78 in Production Example 5. Was prepared.

Example 1
Using a high frequency transmitter (corona generator HV05-2, manufactured by Tamtec) on both sides of the base film obtained in Production Example 1, with a wire electrode having a diameter of 1.2 mm at an output voltage of 100%, an output of 250 W, A corona discharge treatment was performed for 3 seconds under the conditions of an electrode length of 240 mm and a work electrode distance of 1.5 mm, and surface modification was performed so that the surface tension was 0.072 N / m, thereby obtaining a surface-modified base film.
The primer solution obtained in Production Example 3 was applied to one side of the surface-modified base film using a die coater so that the thickness of the primer layer after drying was 0.5 μm, It was dried in a drying furnace for 5 minutes to obtain a base film having a primer layer.
Continuously using a die coater so that the film thickness of the hard coat layer after curing the hard coat agent obtained in Production Example 2 is 5 μm on the side of the base film having the primer layer having the primer layer. It was applied to. Subsequently, after drying at 80 degreeC for 5 minute (s), ultraviolet irradiation (integrated light quantity 300mJ / cm < ² >) was performed, the hard-coat agent was hardened, the hard-coat layer laminated | multilayer film was obtained, and it wound up in roll shape. The thickness of this hard coat layer was 5 μm.

  After leaving the coating liquid A for forming a low refractive index layer obtained in Production Example 4 for 1 hour, it is coated on the hard coat layer laminated film with a wire bar coater to form a coating film having a thickness of about 100 nm. After being left to dry for 1 hour, the film was heat-treated at 120 ° C. for 10 minutes in an oxygen atmosphere to obtain a laminated film 2A on which a low refractive index layer was formed.

Example 2
A laminated film 2B having an antireflection layer formed in the same manner as in Example 1 except that a 40 μm thick triacetylcellulose (TAC) film (trade name: KC4UX2M, manufactured by Konica Minolta) was used as the base film. It was.

Example 3
A laminated film 2C having an antireflection layer formed in the same manner as in Example 1 except that a polyethylene terephthalate (PET) film (trade name: Lumirror T60 # 38, manufactured by Toray Industries, Inc.) having a thickness of 38 μm was used as the base film. Obtained.

Comparative Example 1
The silicon alkoxide solution obtained in Production Example 5 was dropped on the hard coat laminated film 1D with a spin coater after 1 minute from the start of mixing to form a low refractive index layer. The rotation chamber of the spin coater was in a methanol atmosphere, and the rotation speed was 700 rpm for 10 seconds. After forming the low refractive index layer, it was left for 1 minute and 15 seconds to obtain a thin film in which silicon alkoxide was gelled.
This gel-like thin film was immersed in a curing solution having a composition in which water, 28% aqueous ammonia, and methanol were mixed at a mass ratio of 162: 4: 640 for 5 minutes, and then cured at room temperature all day and night. Furthermore, this thin film was immersed in a 10% isopropanol solution of hexamethyldisilazane to perform a hydrophobic treatment.
Next, this hydrophobized gel compound is washed by immersing it in isopropanol, placed in a high-pressure vessel, filled with liquefied carbon dioxide gas, and supercritically dried at 80 ° C., 16 MPa for 2 hours, A laminated film 2D having a silica airgel thin film with a thickness of 100 nm formed on the surface was obtained.

Comparative Example 2
A laminated film 2E was obtained in the same manner as in Comparative Example 1 except that the silicon alkoxide solution B obtained in Production Example 6 was used when forming the low refractive index layer.

  Using the laminated films 2A to 2E of Examples 1 to 3 and Comparative Examples 1 and 2 obtained above, the refractive index, reflectance, reflectance fluctuation, and scratch resistance of the low refractive index layer were measured or evaluated. . The results are summarized in Table 1.

From Table 1, as for laminated film 2A-2C of Examples 1-3, the refractive index of a low refractive index layer exists in the range of 1.25-1.36, and a reflectance fluctuation | variation is less than 50%.
The laminated films 2A to 2C of Examples 1 to 3 have a low reflectance and are useful as an optical film having an antireflection function. No scratches are observed on the surface in visual observation after the steel wool test, and the mechanical strength is not observed. Is excellent.

Examples 4 to 6, Comparative Examples 3 and 4
(1) Production of polarizing plate with antireflection function A polyvinyl alcohol film having a degree of polymerization of 2400 and a thickness of 75 μm is immersed in a 40 ° C. dyeing bath containing iodine and potassium iodide, followed by dyeing treatment, Stretching and crosslinking were performed in an acidic bath at 60 ° C. to which potassium iodide was added so that the total stretch ratio was 5.3 times. After washing with water, it was dried at 40 ° C. to obtain a polarizing plate having a thickness of 28 μm.

  On the base film surface side of the laminated films 2A to 2E obtained in Examples 1 to 3 and Comparative Examples 1 and 2, via the acrylic adhesive (trade name: DP-8005 clear, manufactured by Sumitomo 3M), the above A polarizing plate is attached, and further, a surface-modified substrate film is attached to the polarizing plate via an acrylic adhesive, and the polarizing plate 3A with an antireflection function has the same layer configuration as that shown in FIG. ˜3E was made.

(2) Production of liquid crystal display element A liquid crystal display cell (3 inches, thickness of the plastic substrate 400 μm) using a plastic cell substrate is prepared, and the front side of the liquid crystal display cell and the polarizing plate 3A with antireflection function obtained above. The 3E polarizing plate side was bonded to each other. Further, another polarizing plate was prepared, and this was used for the rear, and was bonded to the opposite surface of the liquid crystal display cell, thereby producing liquid crystal display elements 4A to 4E.
About the obtained liquid crystal display elements 4A to 4E, the visibility before and after the steel wool test was evaluated. The evaluation results are shown in Table 2.

  Unlike the liquid crystal display elements 4D and 4E obtained in Comparative Examples 7 and 8, the liquid crystal display elements 4A to 4C obtained in Examples 4 to 6 have no glare or reflection even after the steel wool test. I couldn't see it.

FIG. 1 is a cross-sectional view of the layer structure of the polarizing plate protective film of the present invention. FIG. 2 is a cross-sectional view of the layer structure of the polarizing plate with an antireflection function of the present invention. FIG. 3 is a cross-sectional view of the layer structure in which the polarizing plate with an antireflection function of the present invention is bonded to a liquid crystal display cell. 4 is a cross-sectional view of the layer structure of the liquid crystal display cell shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Base film, 10a ... Protective film, 12 ... Hard coat layer, 14 ... Low refractive index layer, 14a ... Inorganic hollow fine particle, 16 ... Adhesive layer, 18 ... Polarizing film, 20 ... Polarizing plate protective film, 30 ... Polarizing plate with antireflection function, 40 ... polarizing plate, 50 ... phase difference plate, 60 ... liquid crystal cell, 70 ... transparent electrode, 80 ... electrode substrate, 90 ... liquid crystal, 100 ... seal

Claims (5)

  A polarizing plate protective film in which a low refractive index layer is laminated directly or via another layer on one side of a base film made of a transparent resin, wherein the low refractive index layer has a refractive index of 1.25. A polarizing plate protective film, which is ˜1.36 and has a reflectance fluctuation within 50% after the steel wool test.   The polarizing plate protective film according to claim 1, wherein the low refractive index layer comprises hollow fine particles of an inorganic compound.   The polarizing plate protective film according to claim 1, wherein the transparent resin is at least one of an alicyclic structure-containing polymer resin, a cellulose resin, or a polyester resin.   A polarizing plate is laminated on one surface of the base film of the polarizing plate protective film according to any one of claims 1 to 3 on which the low refractive index layer is not provided. Polarizer.   An optical product comprising the polarizing plate with an antireflection function according to claim 4.

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