KR20120034002A - Protection sheet and polarizing plate - Google Patents

Abstract

PURPOSE: A protective sheet is provided to have excellent thermal resistance, and UV-ray absorbing ability, and to minimize performance depression of a polarizer, in case of being accepted to a polarizer. CONSTITUTION: A protective sheet comprises sea-island structure which has a matrix phase including thermal resistant acrylic resin as base polymer, and a dispersed phase including acrylic rubber as base polymer. The matrix phase comprises micro particles, and sheet-molded through micro-drawing after extrusion. The elongation rate of the micro-drawing is 1-5 %. The average particle diameter of the micro particle is 0.005-2 micron, and the content is 0.005-1 weight%. The content of the dispersed phase is 5-40 weight%. The protective sheet has the retardation value along planar direction of 0-15 nm, and the retardation value along transverse direction is (-15) - 0 nm.

Description

PROTECTION SHEET AND POLARIZING PLATE}

The present invention relates to a protective sheet and a polarizing plate.

In recent years, the liquid crystal display device has been widely used as a substitute for CRT because of its thinness, light weight, and low power consumption. Specifically, liquid crystal displays are widely used, ranging from small products such as electronic calculators and watches to large products such as automobile instruments, PC monitors, and televisions.

The liquid crystal display element provided in the liquid crystal display device has a liquid crystal cell and a pair of polarizing plates arrange | positioned at both surfaces of a liquid crystal cell. This polarizing plate contains a sheet-shaped polarizer and a pair of protective sheet arrange | positioned at both surfaces of this polarizer. The protective sheet is a sheet for protecting the structure of the polarizer, and is generally formed of tri-acetyl cellulose (hereinafter referred to as "TAC") having a small birefringence and excellent transparency.

However, this TAC does not have sufficient heat and moisture resistance, and when using the polarizing plate which used TAC as a polarizer protective film at high temperature or high humidity, there exists a fault that the performance of polarizing plates, such as polarization degree and a hue, falls. The TAC generates a phase difference with respect to incident light in the oblique direction. In recent years, such a phase difference has significantly influenced the viewing angle characteristic as the size of a liquid crystal display is advanced. Therefore, using heat resistant acrylic resin as a substitute of TAC is examined.

Specifically, a protective sheet of a sea island structure having a matrix phase containing a heat resistant acrylic resin as a main polymer and a dispersed phase containing an acrylic rubber as a main polymer has been studied (for example, Japanese Patent Application Laid-Open No. 2010-70646). Publication).

Since the protective sheet is long in the manufactured state, for example, it is necessary to unwind it from the roller when winding it up and processing it, and it is required to have high surface activity. That is, when using heat resistant acrylic resin as a substitute for TAC, it is necessary to fully raise the heat resistance, ultraviolet absorbing ability, and biactivity of a protective sheet.

Japanese Patent Application Laid-Open No. 2010-70646

This invention is made | formed in view of these problems, and an object of this invention is to provide the polarizing plate which has a high heat resistance, a ultraviolet absorbing ability, and a bipolar protective sheet, and this protective sheet.

The invention made in order to solve the said subject,

As a protective sheet of the island-in-water structure which has a matrix phase containing heat-resistant acrylic resin as a main polymer, and a dispersed phase containing acrylic rubber as a main polymer,

The matrix phase contains fine particles,

The sheet is formed by fine stretching after extrusion.

Since the protective sheet is a protective sheet of an island-in-water structure having a matrix phase containing a heat-resistant acrylic resin as a main polymer and a dispersed phase containing an acrylic rubber as a main polymer, the protective sheet has an effect of high heat resistance and flexibility. have. Moreover, the said matrix phase contains microparticles | fine-particles, The said protective sheet is shape | molded by fine drawing after extrusion. Therefore, the fine particles are arranged so as to protrude from the surface of the protective sheet. As a result, when the surface of the said protective sheet contact | connects the plane of another member, some space is formed between the planes of another member, and the said protective sheet can obtain the effect that a high activity is obtained.

It is preferable that elongation is 1% or more and 5% or less. When the elongation in the stretching step is 1% or more and 5% or less, the effect that the fine particles are arranged so as to protrude from the surface of the protective sheet is exerted.

It is preferable that the average particle diameter of the said microparticles | fine-particles is 0.005 micrometer or more and 2 micrometers or less, and content is 0.005 mass% or more and 1 mass% or less. In this case, the activity of the protective sheet is increased.

It is preferable that content of the said dispersed phase is 5 mass% or more and 40 mass% or less. When the said content is made into 5 mass% or more, the flexibility of the said protective sheet can be made higher. When the said content is 40 mass% or less, transparency of the said protective sheet can be maintained.

In the said protective sheet, it is preferable that the retardation value of a plane direction is 0 nm or more and 15 nm or less, and the retardation value of a thickness direction is -15 nm or more and 0 nm or less. Thereby, a phase difference hardly arises in the transmitted light which permeate | transmitted the said protective sheet, For this reason, even if it uses, for example as a protective sheet of a sheet | seat which has a polarizing function, such as a polarizing plate, the advantage of not impairing this polarizing function is obtained. Have

It is preferable that the said heat resistant acrylic resin has ring structure in a principal chain. Thereby, the said protective sheet can acquire the effect that heat resistance is higher.

It is preferable that the protective sheet is subjected to mat processing on one side or both sides. Thereby, the effect that it becomes easy to stick the surface on which the mat process was given to another member through an adhesive agent etc. is exhibited. For example, the protective sheet can be firmly adhered to the polarizer by attaching the surface on which the mat processing has been applied to one surface of the sheet-shaped polarizer with a water-based adhesive to produce a polarizing plate.

It is preferable that the said protective sheet is equipped with the hard-coat layer laminated | stacked on one side. By the hard coat layer, the scratch resistance of the protective sheet can be improved. Moreover, it is preferable that this hard-coat layer is formed by coating an acrylic paint. Thereby, transparency of the said protective sheet can be maintained.

Moreover, this invention also includes the polarizing plate provided with a sheet-shaped polarizer and a pair of the said protective sheets laminated | stacked on both surfaces of this polarizer via an adhesive bond layer.

As described above, the protective sheet of the present invention can obtain the effect of high heat resistance, ultraviolet absorbing ability and diactivity.

1 is a cross-sectional view of a polarizing plate of an embodiment of the present invention.
2 is a cross-sectional view of a liquid crystal display element of the embodiment of the present invention.
3 is a cross-sectional view of a polarizing plate of another embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the protective sheet etc. of embodiment of this invention are demonstrated, referring drawings suitably.

The protective sheet of this embodiment has a matrix phase containing heat-resistant acrylic resin as a main polymer and a dispersed phase containing acrylic rubber as a main polymer. Thereby, the said protective sheet can acquire the effect that heat resistance and flexibility are high.

Matrix Award

The matrix phase contains a heat resistant acrylic resin as a main polymer. This heat resistant acrylic resin means the polymer containing acrylic monomers, such as acrylic acid and methacrylic acid, and these derivatives as a monomer component. As this heat resistant acrylic resin, For example, Methacrylic acid alkyl esters, such as cyclohexyl methacrylate, t-butyl cyclohexyl methacrylate, and methyl methacrylate; The thing which superposed | polymerized 1 type or multiple types of acrylic monomers chosen from alkyl acrylates, such as methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, and 2-ethylhexyl acrylate, is mentioned. This heat resistant acrylic resin also includes a copolymer of an acrylic monomer and another monomer component. In the case of such copolymerization, the content rate (copolymerization ratio) of the other monomer component is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less with respect to all monomer components constituting the heat resistant acrylic resin. Do.

It is preferable that the said heat resistant acrylic resin is a polymer containing methyl methacrylate as a monomer component. The compatibility of the heat resistant acrylic resin obtained by heat-resistant acrylic resin containing methyl methacrylate as a monomer component improves. As a polymer which contains methyl methacrylate as a monomer component, the homopolymer of methyl methacrylate, the copolymer of methyl methacrylate, and another monomer etc. are mentioned. As another monomer copolymerizable with methyl methacrylate, For example, alkyl methacrylates other than methyl methacrylate; Acrylic acid alkyl esters and α-hydroxymethyl acrylic acid alkyl esters; Styrene; (alpha) -alkyl, such as alkyl substituted styrene, (alpha) -methylstyrene, (alpha) -methyl- p-methylstyrene, such as o-methylstyrene, p-methylstyrene, 2, 4- dimethyl styrene, ethyl styrene, and p-tert- butyl styrene Aromatic vinyl compounds such as substituted styrene; Unsaturated nitriles such as acrylonitrile and methacrylonitrile; Maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide; Unsaturated carboxylic anhydrides such as maleic anhydride; Unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, and maleic acid, etc. are mentioned. As these other monomers, from the viewpoint of improving the flexibility and heat resistance of the protective sheet obtained, α-hydroxymethylacrylic acid alkyl esters, styrene, alkyl substituted styrenes, α-alkyl substituted styrenes and unsaturated carboxylic acids are preferable. -Hydroxymethyl acrylate alkylesters, styrene, (alpha)-alkyl substituted styrene, and unsaturated carboxylic acids are more preferable, and (alpha)-hydroxymethyl acrylate, styrene, (alpha) -methylstyrene, and methacrylic acid are more preferable. When copolymerizing with methyl methacrylate using α-hydroxymethyl acrylate alkyl esters as another monomer, a dehydration reaction is also performed to form a lactone ring containing a polymer main chain in part, so that the resulting heat-resistant acrylic system is obtained. The heat resistance of the resin is particularly improved. These monomers can be used individually by 1 type or in combination of multiple types. In the copolymer of such methyl methacrylate with another monomer, the content rate of the other monomer component is preferably 50% by mass or less with respect to methyl methacrylate.

As another monomer copolymerizable with said methyl methacrylate, alkyl acrylate esters are preferable. The heat resistance temperature of the heat resistant acrylic resin obtained by using alkyl acrylate ester as another monomer improves, and the fluidity | liquidity at the time of shaping | molding process becomes high. In such a copolymer of methyl methacrylate and alkyl acrylates, the content rate of the alkyl acrylate monomer component is preferably 0.1% by mass or more and 15% by mass or less with respect to all monomer components from the viewpoint of improving heat resistance. 0.2 mass% or more and 14 mass% or less are more preferable, and 1 mass% or more and 12 mass% or less are more preferable.

As said alkyl acrylate, methyl acrylate and ethyl acrylate are preferable because only the small amount copolymerization with methyl methacrylate can obtain the effect of improving fluidity at the time of said shaping | molding process remarkably.

As said heat resistant acrylic resin, isotactic polymethacrylic acid ester or syndiotactic polymethacrylic acid ester can also be used. Moreover, heat resistant acrylic resin may use a commercial item as it is, and can also manufacture from the commercial item used as a precursor.

As a method of manufacturing the said heat resistant acrylic resin, a conventionally well-known method can be employ | adopted, For example, polymerization methods, such as cast polymerization, block polymerization, suspension polymerization, solution polymerization, emulsion polymerization, anionic polymerization, can be employ | adopted. Do. Bulk polymerization or solution polymerization without using a suspending agent or emulsifying agent is preferable, whereby the incorporation of fine foreign matter can be reduced. In addition, in the case of solution polymerization, it is possible to use aromatic hydrocarbon solvents, such as toluene. In the case of the bulk polymerization, the polymerization can be initiated by free radicals generated by heating or ionizing radiation irradiation. Moreover, as a polymerization initiator used for a polymerization reaction, For example, Azo compounds, such as azobisisobutyronitrile; Organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxy-2-ethylhexanoate and the like can be used.

Moreover, when superposing | polymerizing on the temperature conditions of 90 degreeC or more, although solution polymerization is generally employ | adopted, it is preferable to use the thing of 80 degreeC or more for 10 hours half life temperature among the polymerization initiators soluble in an organic solvent. Specifically as such a polymerization initiator, 1, 1-bis (t-butyl peroxy) -3, 3, 5- trimethyl cyclohexane, cyclohexane peroxide, 2, 5- dimethyl- 2, 5- di (benzoyl) Peroxy) hexane, 1,1- azobis (1-cyclohexanecarbonitrile), 2- (carbamoyl azo) isobutyronitrile, etc. are mentioned. As the usage-amount of these polymerization initiators about the said polymerization reaction, 0.005-5 mass parts is preferable with respect to 100 mass parts of all the monomers used for superposition | polymerization.

In the polymerization reaction, a molecular weight regulator can be used as necessary. This molecular weight regulator can be employ | adopted what is generally used in radical polymerization. Specifically, mercaptan compounds, such as butyl mercaptan, octyl mercaptan, dodecyl mercaptan, thioglycolic acid 2-ethylhexyl, can be used, for example. It is preferable to add these molecular weight modifiers in the density | concentration range like the molecular weight of the said heat resistant acrylic resin being a desired range.

Moreover, as a manufacturing method of heat resistant acrylic resin, it is possible to use the method described in Unexamined-Japanese-Patent No. 63-1964 etc., for example. Moreover, as heat resistant acrylic resin, it can also be set as a three or more member copolymer by copolymerizing an alkyl methacrylate and / or an alkyl acrylate, and another 1 or more types of monomers.

In the above-mentioned three or more copolymers, as another monomer component copolymerized with methacrylic acid alkyl ester and / or alkyl acrylate ester, for example, styrene, (alpha) -methylstyrene, o-methylstyrene, p-methylstyrene, o Aromatic vinyl compounds such as ethyl styrene, p-ethyl styrene, and pt-butyl styrene; Unsaturated nitriles such as acrylonitrile, methacrylonitrile and ethacrylonitrile; Maleimides such as N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide; (Meth) acrylamides, such as acrylamide, methacrylamide, N-methyl acrylamide, butoxymethyl acrylamide, and N-propyl methacrylamide; Unsaturated carboxylic anhydrides such as maleic anhydride and itaconic anhydride; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid and maleic acid; Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate Chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6 (meth) acrylic acid It is possible to employ unsaturated carboxylic acid alkyl esters such as pentahydroxyhexyl and (meth) acrylic acid 2,3,4,5-tetrahydroxypentyl.

As resin which comprises a matrix form, you may use acrylic resin (henceforth "acrylic-type resin (A)") other than heat-resistant acrylic resin other than heat-resistant acrylic resin as a main polymer. In this case, the mass ratio (acrylic resin (A) / heat-resistant acrylic resin) of the acrylic resin (A) to the heat-resistant acrylic resin is 0.1 / 99.9 in each of the content of the heat-resistant acrylic resin and the acrylic resin (A) on the matrix. It is preferable that it is more than 50/50 or less. By adjusting the mass ratio of acrylic resin (A) and heat resistant acrylic resin, it is possible to adjust the photoelastic coefficient and glass transition temperature (Tg) of the protective sheet obtained. As said mass ratio, 0.1 / 99.9 or more and 40/60 or less are preferable, and 0.1 / 99.9 or more and 35/65 or less are more preferable.

It is preferable that the weight average molecular weights (Mw) of polymethyl methacrylate (PMMA) conversion by gel permeation chromatography (GPC) of the said heat resistant acrylic resin are 10,000 or more and 400,000 or less, and it is more than 40,000 and 300,000 or less It is preferable and it is more preferable that they are 70,000 or more and 200,000 or less. By making Mw of the said heat resistant acrylic resin into the said range, the intensity | strength of the protective sheet obtained is improved, and the workability and fluidity | liquidity of protective sheet molding improve. Moreover, 1.8 or more and 3.0 or less are preferable, as for molecular weight distribution (Mw / Mn), 1.8 or more and 2.7 or less are more preferable, and 1.8 or more and 2.5 or less are further more preferable.

The heat resistant acrylic resin may be a mixture of two or more kinds of heat resistant acrylic resins having different compositions, molecular weights and the like of the monomer components. In this case, the said weight average molecular weight means the average value.

As a bicat softening temperature of the said heat resistant acrylic resin, it is preferable that they are 105 degreeC or more and 140 degrees C or less, More preferably, 110 degreeC or more is more preferable, and 120 degreeC or more is more preferable. Moreover, as glass transition temperature (Tg) of heat resistant acrylic resin, it is preferable that it is 110 degreeC or more, 115 degreeC or more is more preferable, and 120 degreeC or more is more preferable. As a melt index (ASTM D1238; I condition) of heat resistant acrylic resin, 10g / 10min or less is preferable from a viewpoint of the strength of the protective sheet obtained, 6g / 10min or less is more preferable, 3g / 10min or less is still more preferable. .

Content of content of the acrylic monomer component in heat resistant acrylic resin (1) when heat-resistant acrylic resin is heat resistant acrylic resin which does not contain an aromatic vinyl monomer as a monomer component (it also describes as "heat-resistant acrylic resin (1).") As a thing, it is preferable that it is 40 mass% or more with respect to the all monomer components which comprise heat resistant acrylic resin (1). As this acrylic resin (1), For example, methacrylic acid ester, such as cyclohexyl methacrylate, t-butyl cyclohexyl methacrylate, and methyl methacrylate; The thing which superposed | polymerized 1 or more types of monomers chosen from acrylic esters, such as methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, and 2-ethylhexyl acrylate, can be used.

It is preferable that it is 50,000 or more and 200,000 or less, and, as for the weight average molecular weight of the said acrylic resin (1), 70,000 or more and 150,000 or less are more preferable. The protective sheet obtained by making this weight average molecular weight into the said range is excellent in strength, and excellent in the moldability and fluidity | liquidity at the time of protective sheet shaping | molding.

Moreover, when using together the heat resistant acrylic resin which contains an aromatic vinyl monomer as a monomer component as the heat resistant acrylic resin which comprises a matrix form, and the acrylic resin (1) which does not contain the said aromatic vinyl monomer as a monomer component, it is further another It is also possible to use acrylic resin together. In this case, 20 mass parts or less are preferable with respect to 100 mass parts of total resin which comprises a matrix form, and, as for content of the said other acrylic resin, 10 mass parts or less are more preferable. As for content of the said heat resistant acrylic resin (1), 0.1 mass part or more and 50 mass parts or less are preferable with respect to 100 mass parts of all resin which comprises a matrix form, 0.1 mass part or more and 40 mass parts or less are more preferable, 0.1 Part by mass or more and 35 parts by mass or less are particularly preferable. Moreover, as for content of the said heat resistant acrylic resin, 50 mass parts or more and 99.9 mass parts or less are preferable with respect to 100 mass parts of all resin which comprises a matrix form, 60 mass parts or more and 99.9 mass parts or less are more preferable, 65 mass parts 99.9 mass parts or more are more preferable. The heat resistance of the protective sheet obtained by making content of the heat resistant acrylic resin in a matrix into the said range can be improved. Moreover, the heat resistance of the said protective sheet can be made high by using heat resistant acrylic resin which has a ring structure for a principal chain.

<Distribution phase>

The dispersed phase contains an acrylic rubber as the main polymer. This acrylic rubber means the rubber which contains acrylic monomers, such as acrylic acid and methacrylic acid, and these derivatives as a monomer component. Acrylic rubber may be comprised only by the acryl-type monomer, or may be comprised by the monomer different from an acryl-type monomer. Examples of the acrylic monomers include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, allyl methacrylate, methyl acrylate, ethyl acrylate, i-propyl acrylate, and n-butyl acrylate. As another monomer, For example, aromatic vinyl, such as styrene, (alpha) -methylstyrene, 2-methylstyrene, 4-methylstyrene, 2, 4- diethyl styrene, 4-butoxy styrene, N, N- dimethylamino styrene, etc. compound; Α, β-ethylenically unsaturated nitrile compounds such as acrylonitrile, methacrylonitrile and vinylidene cyanide; Vinyl ester compounds such as vinyl acetate and vinyl propionate; Vinyl ether compounds, such as ethyl vinyl ether, cetyl vinyl ether, and hydroxybutyl vinyl ether, etc. are mentioned. These other monomers can be used individually or in mixture of 2 or more types, respectively.

The acrylic rubber may be crosslinked using a crosslinking agent. As a crosslinking agent, For example, sulfur; Organic peroxides such as 2,4-dichlorobenzoyl peroxide, benzoyl peroxide and di-tert-butylperoxydiisopropylbenzene; Organic sulfur compounds such as tetramethyl thiuram monosulfide and tetramethyl thiuram disulfide; oxime compounds such as p-quinone dioxime and p, p'-dibenzoylquinone dioxime; Polyamines, such as hexamethylenediamine carbamate, etc. are mentioned. When using a crosslinking agent, you may use vulcanization accelerators, such as diphenyl guadiine, zinc dimethyl dithio carbamate, 2-mercapto benzothiazole, dibenzo thiazyl sulfide, as needed. .

The average particle diameter of the said dispersed phase is 1 nm or more and less than 50 nm, It is preferable that it is 2 nm or more and less than 50 nm, It is more preferable that it is 3 nm or more and less than 50 nm. If the average particle diameter of a dispersed phase is less than the said minimum, there exists a possibility that the flexibility of a protective sheet may fall. On the contrary, when the average particle diameter exceeds the upper limit, there is a fear that the transparency of the protective sheet is deteriorated.

In the said protective sheet, as content of the said dispersed phase, 5 mass% or more and 40 mass% or less are preferable with respect to the said protective sheet, 10 mass% or more and 35 mass% or less are more preferable, 20 mass% or more and 30 mass% or less More preferred. When content of a dispersed phase is less than the said minimum, there exists a possibility that the flexibility of a protective sheet may fall. On the contrary, when content of a dispersed phase exceeds the said upper limit, there exists a possibility that transparency of a protective sheet may deteriorate.

As this dispersed phase, what has a multilayered structure is employable. As the multilayer structure, for example, a two-layer structure composed of a core-shell structure, a three-layer structure composed of a central hard layer, a soft layer, and an outer hard layer, or an intermediate hard layer is further added between the soft layer and the outer hard layer. It is possible to adopt a four-layer structure having.

As said two-layer structure, it can be set as the core-shell structure which consists of a core layer which consists of a rubbery polymer, and the shell layer which consists of an acrylic resin glassy polymer, for example. The rubbery polymer used for the core layer is not particularly limited as long as it is rubbery at ordinary temperature. For example, a rubbery polymer having butadiene as a main component (for example, butadiene homopolymer, butadiene-aromatic vinyl copolymer, etc.) Or a rubbery polymer (e.g., butyl acrylate-styrene copolymer, 2-ethylhexyl acrylate-styrene copolymer, etc.) mainly composed of alkyl acrylate esters. Moreover, it is preferable to employ butadiene-styrene copolymer, and by this, strength, productivity, and transparency can be improved. In addition, as a glassy polymer used for a shell layer, if it is a glassy acryl-type polymer at normal temperature, it will not specifically limit, For example, a methyl methacrylate homopolymer, a methylmethacrylate-methylacrylate copolymer, etc. can be used.

Moreover, as a dispersed phase which has a multilayer structure of three or more layers, what consists of three or more layers of the soft layer which consists of a rubbery polymer, and the hard layer which consists of a glassy polymer is laminated. The rubbery polymer used for the soft layer and the glassy polymer used for the hard layer can be the ones described above for the rubber particles of the two-layer structure.

As long as the effects of the present invention are not impaired, other polymers may be mixed in addition to the heat-resistant acrylic resin constituting the matrix phase and the acrylic rubber constituting the dispersed phase. Moreover, as another polymer, For example, polyolefin resin, such as polyethylene and a polypropylene; Polyamide resins; Polyphenylene sulfide resin; Polyether ether ketone resins; Thermoplastic resins such as polyester, polysulfone, polyphenylene oxide, polyimide, polyetherimide and polyacetal; And thermosetting resins such as phenol resins, melamine resins, silicone resins and epoxy resins. The other polymer can mix single or multiple types. In addition, it is preferable to make content of another polymer into 20 mass parts or less with respect to 100 mass parts of matrix form.

<Ultraviolet absorber>

The protective sheet contains an ultraviolet absorber in the matrix phase. When the protective sheet contains the ultraviolet absorbent in the matrix, the protective sheet can be easily yellowed. Moreover, when the said protective sheet is laminated | stacked on both surfaces of a sheet-shaped polarizer, and a polarizing plate is formed, ultraviolet-ray transmission to a polarizer can be suppressed. Moreover, it is preferable that this ultraviolet absorber is further contained in the said dispersed phase. When the ultraviolet absorber is further contained in the dispersion layer, the dispersion uniformity of the ultraviolet absorber in the protective sheet is improved, and when the protective sheet is laminated on both surfaces of the sheet-shaped polarizer to form a polarizing plate, the ultraviolet rays as the polarizer Permeation can be further suppressed.

As said ultraviolet absorber, a benzotriazole type compound can be used, In addition, a benzophenone type compound, a benzoate type compound, a triazine type compound, a hindered amine type compound, an oxalic acid anilide type compound, a formamidine type compound, and hydroxy It can select suitably from a benzoate type compound, a nickel type compound, etc. These may be used independently and can be used in combination of multiple types. Moreover, in order to prevent deterioration of a polarizing plate, it is preferable that the ultraviolet absorber is excellent in the absorption ability of the ultraviolet-ray of wavelength 370 nm or less, and the absorption of visible light of wavelength 400nm or more is effective for the effective use of visible light.

Moreover, as a ultraviolet absorber, since the said benzotriazole type compound, a benzophenone type compound, a benzoate type compound, and a triazine type compound are high in transparency, and excellent in the effect which prevents deterioration of a polarizing plate among the compounds enumerated above, it is preferable. . It is especially preferable to employ | adopt the ultraviolet absorber which consists of benzotriazole type compounds with less coloring and high transparency.

Specific examples of the benzotriazole-based compound include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole and 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) Phenyl] benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5' -Methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy- 3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2,2'-methylene-bis [4- ( 1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], methyl-3- [3-tert-butyl-5- (2H-benzotriazole-2 Condensate of -yl) -4-hydroxyphenyl] propionate with polyethylene glycol, 2- (2-hydroxyphenyl) benzotriazole-copolymer, 2- (2'-hydroxy-4'-octyl Oxyphenyl) -2H-benzotriazole, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidyl Butyl) phenol, 2,2'-methylenebis (4-tert-butyl-6-2H-benzotriazolylphenol), 2,2'-methylenebis (4-tert-octyl-6-2H-benzotriazolylphenol ), And the like. As a commercial item, a brand name "KEMISORB 279" (made by Chemipro company) and a brand name "TINUVIN 360" (made by BASF Japan company) are mentioned.

Specific examples of the benzophenone-based compound include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2 -Hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis (5-benzoyl-4-hydroxy 2-methoxyphenyl) methane, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4 , 4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, and the like. As a commercial item, a brand name "KEMISORB 12", a "brand name KEMISORB 111" (all are the Chemipro company make), and a brand name "CHIMASSORB 81" (made by BASF Japan company) are mentioned.

As said benzotriazole type compound and a benzophenone type compound, it is preferable that the mass reduction in 300 degreeC and the heating for 20 minutes is 10% or less. The mass reduction in heating at 300 ° C. for 20 minutes is preferably 9% or less, more preferably 8% or less, still more preferably 6% or less, particularly preferably 5% or less. When the mass reduction in heating at 300 degreeC and 20 minutes exceeds the said upper limit, there exists a possibility that sufficient ultraviolet absorbing ability may not be exhibited. As a ultraviolet absorber whose mass loss in heating at 300 degreeC and 20 minutes is 10% or less, Preferably 2,2'- methylenebis [6- (2H- benzotriazol-2-yl) -4- (1,1 , 3,3-tetramethylbutyl) phenol]. As a commercial item, a brand name "KEMISORB 12", a brand name "KEMISORB 111" (all are the Chemipro company make), a brand name "CHIMASSORB 81" (made by BASF Japan company), etc. are mentioned.

As said triazine type compound, the compound which has a 1,3,5-triazine ring can be used preferably, for example. Specifically, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol etc. are mentioned. As a commercial item, the brand name "TINUVIN 1577" (made by BASF Japan Corporation) is mentioned, for example.

Examples of the hindered amine compound include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-benzyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1- (4-tert-butyl-2-butenyl) -4-hydroxy-2,2,6,6 Tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperi Dean, 1-benzyl-2,2,6,6-tetramethyl-4-piperidylmaleate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1, 2,2,6,6-pentamethyl-4-piperidyl) succinate, bis (2,2,6,6-tetramethyl-4-piperidyl) adipate, bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) fumarate, bis (1,2,3,6-tetramethyl-2 , 6-diethyl-4-piperidyl) sebacate, bis (1-allyl-2,2,6,6-tetramethylol-4-piperidyl) phthalate, bis (1,2,2,6 , 6-pentamethyl-4-piperidyl) Bacate, 1,1 '-(1,2-ethanediyl) bis (3,3,5,5-tetramethylpiperazinone), 2-methyl-2- (2,2,6,6-tetramethyl -4-piperidyl) imino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, 2-methyl-2- (1,2,2,6,6- Pentamethyl-4-piperidyl) imino-N- (1,2,2,6,6-pentamethyl-4-piperidyl) propionamide, 1-propargyl-4-β-cyanoethyl Oxy-2,2,6,6-tetramethylpiperidine, 1-acetyl-2,2,6,6-tetramethyl-4-piperidyl-acetate, trimellitic acid-tris (2,2,6 , 6-tetramethyl-4-piperidyl) ester, 1-acryloyl-4-benzyloxy-2,2,6,6-tetramethylpiperidine, bis (1,2,2,6,6 -Pentamethyl-4-piperidyl) dibutylmalonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) dibenzylmalonate, bis (1,2,3,6 -Tetramethyl-2,6-diethyl-4-piperidyl) dibenzyl-malonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2- (3, 5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate, bis (2,2,6,6 Tetramethyl-4-piperidyl) -1,5-dioxaspiro [5.5] undecane-3,3-dicarboxylate, bis (1,2,2,6,6-pentamethyl-4- Piperidyl) -1,5-dioxaspiro [5.5] undecane-3,3-dicarboxylate, bis (1-acetyl2,2,6,6-tetramethyl-4-piperidyl)- 1,5-dioxaspiro [5.5] undecane-3,3-dicarboxylate, 1,3-bis [2,2 '-[bis (2,2,6,6-tetramethyl-4-pi Ferridyl) -1,3-dioxacyclohexane-5,5-dicarboxylate]], bis (2,2,6,6-tetramethyl-4-piperidyl) -2- [1-methyl Ethyl] -1,3-dioxacyclohexane-5,5-dicarboxylate]], 1,2-bis [2,2 '-[bis (2,2,6,6-tetramethyl-4- Piperidyl) -2-methyl-1,3-dioxacyclohexane-5,5-dicarboxylate]], bis (2,2,6,6-tetramethyl-4-piperidyl) -2 -[2- (3,5-di-tert-butyl-4-hydroxyphenyl)] ethyl-2-methyl-1,3-dioxacyclohexane-5,5-dicarboxylate, bis (2, 6,6-tetramethyl-4-piperidyl) -1,5-dioxaspiro [5.11] heptadecane-3,3-dicarboxyl , Hexane-1 ', 6'-bis-4-carbamoyloxy-1-n-butyl-2,2,6,6-tetramethylpiperidine), toluene-2', 4'-bis ( 4-carbamoyloxy-1-n-butyl-2,2,6,6-tetramethylpiperidine), dimethyl-bis (2,2,6,6-tetramethylpiperidine-4-oxy) -Silane, phenyl-tris (2,2,6,6-tetramethylpiperidine-4-oxy) -silane, tris (1-propyl-2,2,6,6-tetramethyl-4-piperidyl ) -Phosphite, tris (1-propyl-2,2,6,6-tetramethyl-4-piperidyl) -phosphate, phenyl- [bis (1,2,2,6,6-pentamethyl-4 -Piperidyl)]-phosphonate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tetrakis (1, 2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl ) 1,2,3,4-butanetetracarbonamide, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarbonamide , 2-dibutylamino-4,6-non (9-Aza-3-ethyl-8,8,10,10-tetramethyl-1,5-dioxaspiro [5.5] -3-undecylmethoxy) -s-triazine, 2-dibutylamino-4 , 6-bis (9-aza-3-ethyl-8,8,9,10,10-pentamethyl-1,5-dioxaspiro [5.5] -3-undecylmethoxy) -s-triazine, tetra Keith (9-aza-3-ethyl-8,8,10,10-tetramethyl-1,5-dioxaspiro [5.5] -3-undecylmethyl) -1,2,3,4-butanetetracar Voxylate, tetrakis (9-aza-3-ethyl-8,8,9,10,10-pentamethyl-1,5-dioxaspiro [5.5] -3-undecylmethyl) -1,2,3 , 4-butanetetracarboxylate, tridecyl tris (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tridecyl tris ( 1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, di (tridesinol) -bis (2,2,6,6- Tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, di (tridecyl) -bis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 2,2, 4,4-tetramethyl-7-oxa-3,20-diazadispiro [5,1,11,2] henicoic acid-21-one, 3,9-bis [1,1-dimethyl-2- { Tris (2,2,6,6-tetramethyl-4-piperidyloxycarbonyl) butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9 -Bis [1,1-dimethyl-2- {tris (1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl) butylcarbonyloxy} ethyl] -2,4,8, 10-tetraoxaspiro [5.5] undecane, poly (2,2,6,6-tetramethyl-4-piperidylacrylate), poly (1,2,2,6,6-pentamethyl-4- Piperidyl acrylate), poly (2,2,6,6-tetramethyl-4-piperidyl methacrylate), poly (1,2,2,6,6-pentamethyl-4-piperidyl Methacrylate), poly [[[bis (2,2,6,6-tetramethyl-4-piperidyl) itaconate] [vinylbutyl ether]], poly [[[bis (1,2,2 , 6,6-pentamethyl-4-piperidyl) itaconate] [vinylbutyl ether]], poly [[[bis (2,2,6,6-tetramethyl-4-piperidyl) itaco Nate] [vinyl octyl Le]], poly [[[bis (1,2,2,6,6-pentamethyl-4-piperidyl) itaconate] [vinyloctylether]], dimethylsuccinate-2- (4-hydride Roxy-2,2,6,6-tetramethylpiperidyl) ethanol condensate, poly [[hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], poly [[Ethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethylene-4-piperidyl) imino]] , Poly [[[1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2, 6,6-tetramethyl-4-piperidyl) imino]], poly [[[6- (diethylimino) -1,3,5-triazine-2,4-diyl] [(2, 2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], poly [[[6- [(2-ethylhexyl) imino] -1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], poly [[[6-[(1,1,3,3-tetramethylbutyl) Mino] -1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6, 6-tetramethyl-4-piperidyl) imino]], poly [[[6- (cyclohexylimino) -1,3,5-triazine-2,4-diyl] [(2,2, 6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], poly [[[6-morpholi No-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6 -Tetramethyl-4-piperidyl) imino]], poly [[[6- (butoxyimino) -1,3,5-triazine-2,4-diyl] [(2,2,6, 6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], poly [[[6-[(1, 1,3,3-tetramethylbutyl) oxy] -1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] Hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], poly [[oxy [6-[(1-piperidyl) -1,3,5-triazine -2,4-diyloxy-1,2-ethanediyl] [(2,2 , 6,6-tetramethyl-3-oxo-1,4-piperidyl) -1,2-ethanediyl]] [(3,3,5,5-tetramethyl-2-oxo-1,4- Piperidyl) -1,2-ethanediyl]], poly [[oxy [6-[(1,1,3,3-tetramethylbutyl) imino] -1,3,5-triazine-2, 4-diyl oxy-1,2-ethanediyl] [(2,2,6,6-tetramethyl-3-oxo-1,4-piperidyl) -1,2-ethanediyl] [(3,3 , 5,5-tetramethyl-2-oxo-1,4-piperidyl) -1,2-ethanediyl]], poly [[[6-[(ethylacetyl) imino] -1,3,5 -Triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-pi Ferridyl) imino]], poly [[[6-[(2,2,6,6-tetramethyl-4-piperidyl) butylimino] -1,3,5-triazine-2,4 -Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]] , 1,6,11-tris [{4,6-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -1,3,5-tri Azin-2-yl} amino] undecane, 1,6,11-tris [{4,6-bis (N-butyl-N- (1,2,2,6,6-penta) Yl-4-piperidyl) amino) -1,3,5-triazin-2-yl} amino] undecane, 1,6,11-tris [{4,6-bis (N-octyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -1,3,5-triazin-2-yl} amino] undecane, 1,6,11-tris [{4, 6-bis (N-octyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -1,3,5-triazin-2-yl} amino] undecane , Polymethyl-propyl-3-oxy [1 (2,2,6,6-tetramethyl) piperidyl] siloxane, 1,1 ', 1 "-[1,3,5-triazine-2,4 , 6-triyl-tris [(cyclohexylimino) -2,1-ethanediyl]]-tris [3,3,5,5-tetramethylpiperazin-2-one], 1,1,1- Tris [polyoxypropylene- (4,6-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -1,3,5-triazine-2 -Yl} aminoethermethyl] propane, 1,1,1-tris [polyoxyethylene- {4,6-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperi) Di) amino) -1,3,5-triazin-2-yl} aminoethermethyl] propane, 1,1,1-tris [polyoxyethylene- {4,6-bis (N-butyl-N- ( One , 2,2,6,6-pentamethyl-4-piperidyl) amino) -1,3,5-triazin-2-yl} aminoethermethyl] propane, 1,1,1-tris [polyoxy Propylene- {4,6-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -1,3,5-triazin-2-yl} amino Ethermethyl] propane, 1,1,1-tris [polyoxypropylene- {4,6-bis (N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) Amino) -1,3,5-triazin-2-yl} aminoethermethyl] propane, 1,5,8,12-tetrakis [4,6-bis (N- (2,2,6,6- Tetramethyl-4-piperidyl) -butylamino) -1,3,5-triazin-2-yl] -1,5,8,12-tetraazadodecane, 1,5,8,12-tetra Keith [4,6-bis (N- (1,2,2,6,6-pentamethyl-4-piperidyl) -butylamino) -1,3,5-triazin-2-yl] -1 , 5,8,12-tetraazadodecane and the like.

Moreover, as said oxalic acid anilide type compound, N, N'-diethyl oxalic acid-bis-anilide, 2-ethoxy-2'-ethyloxalic acid-bis-anilide, 2-ethoxy-5-tert- Butyl-2'-ethyloxalic acid-bis-anilide, 2-ethoxy-5-tert-butyl-2'-ethyl-4'-tert-butyloxalic acid-bis-anilide, etc. are mentioned. As a commercial item, a brand name "TINUVIN 312" and a brand name "TINUVIN 315" (made by BASF Japan company) are mentioned.

Moreover, as said formamidine type ultraviolet absorber, N- (4-ethoxycarbonylphenyl) -N'-methyl-N'-phenylformamidine and N- (4-ethoxycarbonylphenyl) -N'-ethyl- N'-phenylformamidine, N- (4-ethoxycarbonylphenyl) -N'-ethoxyl-N'-phenylformamidine and N- (4-ethoxycarbonylphenyl) -N ', N '-Diphenylformamidine and the like.

Examples of the triazine compound as the ultraviolet absorber include 2- [4,6-di (2,4-xylyl) -1,3,5-triazin-2-yl] -5-octyloxyphenol and 2- (4, 6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol and the like. As the hydroxybenzoate light stabilizer of the component (c), 2,4-di-tert-butylphenyl-3 ', 5'-di-tert-butyl-4'-hydroxybenzoate and 2,6-di- tert-butylphenyl-3 ', 5'-di-tert-butyl-4'-hydroxybenzoate, n-hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate and n-octa Decyl-3,5-di-tert-butyl-4-hydroxybenzoate and the like can be used.

Moreover, it is preferable that melting | fusing point of the said ultraviolet absorber is 110 degreeC or more, It is more preferable that it is 120 degreeC or more, It is still more preferable that it is 130 degreeC or more. When the melting point of the ultraviolet absorber is less than the above lower limit, there is less volatilization when heat melting for processing, precipitation and aggregation of the ultraviolet absorber at molding outlets such as extrusion exit are less likely to occur, and contamination during sheet molding occurs. It is difficult and does not impair transparency of the sheet.

As content of the said ultraviolet absorber, 0.5 mass% or more and 10 mass% or less are preferable with respect to a matrix phase, 1 mass% or more and 9 mass% or less are more preferable, 2 mass% or more and 8 mass% or less are more preferable. If content of a ultraviolet absorber is less than the said minimum, there exists a possibility that the protective sheet obtained may not fully absorb an ultraviolet-ray. Moreover, when content of a ultraviolet absorber exceeds the said upper limit, there exists a possibility that the heat resistance of a protective sheet may fall.

Moreover, you may use the compound which has a phenolic hydroxyl group and a C4-C12 branched alkyl group or a C4-C12 linear alkoxy group together as a ultraviolet absorber. Since the phenolic hydroxyl group of the said ultraviolet absorber has high polarity, it has high affinity with respect to the said heat resistant acrylic resin which has a high polar ester group. Since the branched alkyl group or linear alkoxy group of the said ultraviolet absorber contains a carbon chain of low polarity and a suitable length, it has high affinity with the acrylic rubber which is easy to interact with the carbon chain. Therefore, the said ultraviolet absorber becomes easy to exist in the interface of a heat resistant acrylic resin and an acrylic rubber. Therefore, in the matrix of the protective sheet, the ultraviolet absorber is uniformly dispersed. As a result, the protective sheet can exhibit excellent ultraviolet absorbing ability.

<Particulates>

The protective sheet contains fine particles in a matrix phase. Silicon dioxide is preferably used as the material of the fine particles, but in addition, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, calcium silicate hydrate, aluminum silicate, magnesium silicate, calcium phosphate, and the like. It is also possible to use organic materials such as inorganic materials and crosslinked polymers. In addition, it is preferable to employ silicon dioxide as the material of the fine particles because the haze of the protective sheet can be reduced. In addition, it is preferable to adopt microparticles | fine-particles surface-treated with the organic material of the silicon dioxide from a viewpoint of making the haze of a protective sheet smaller. Examples of the organic substance used for this surface treatment include halosilanes, alkoxysilanes, silazanes, and siloxanes. As a commercial item, for example, a brand name "silopobic" (made by Fujisilician Kagaku Corporation) and "aerosil 200V" (made by Nippon Aerosil company) and "aerosil R972V" (Nippon Aero) Judge). These may be used alone or in combination.

It is preferable that the average particle diameter of the said microparticle is 0.005 micrometer or more and 2 micrometer or less, and its 0.05 micrometer or more and 1 micrometer or less are more preferable. In this case, the activity of the protective sheet is increased. Moreover, these microparticles | fine-particles are arrange | positioned so that it may protrude from the surface of a protective sheet, It is preferable that the maximum protrusion height of these microparticles | fine-particles is 0.01 micrometer or more and 0.1 micrometer, and 0.02 micrometer or more and 0.05 micrometer or less are more preferable. In this case, the activity of the protective sheet is increased. In addition, the microparticles | fine-particles are extended | stretched (fine stretching) at the time of protective sheet formation, and microparticles protrude from the surface as mentioned above, and are provided.

0.005 mass% or more and 1 mass% or less are preferable with respect to the said protective sheet, as for content of the said microparticles | fine-particles, 0.01 mass% or more and 0.5 mass% or less are more preferable, 0.1 mass% or more and 0.3 mass% or less are especially preferable.

The fine particles may be contained not only in the matrix phase but also in the dispersed phase. As microparticles | fine-particles contained in the said dispersed phase, it can be set as the same material, maximum protrusion height, and compounding quantity as the microparticles | fine-particles contained in said matrix phase.

<Protection Sheet>

The protective sheet is formed by extrusion molding a mixture of a heat resistant acrylic resin forming a matrix phase and an acrylic rubber forming a dispersed phase, for example. Here, it is preferable that the protective sheet is molded while finely stretching during the extrusion molding. In addition, fine extending | stretching means extending | stretching about 10% or less of elongation rate. Moreover, 1% or more and 5% or less of the elongation rate in this fine extending process is preferable. In order to realize the elongation, for example, the extrusion is performed in a state where the pulling rate for pulling the cooled and molded sheet is 0.3% larger than the extrusion speed at which the molten material is extruded during extrusion molding. As described above, by fine stretching after extrusion, the fine particles tend to be arranged in a state in which they protrude from the surface of the protective sheet, thereby improving the activity of the protective sheet. In addition, because of the fine stretching, the transparency of the protective sheet can be maintained. In addition, although this micro-stretching process can carry out biaxial stretching fine-drawing in a biaxial direction, it is preferable to set it as uniaxial stretching.

The thickness of the protective sheet is preferably 15 µm or more and 400 µm or less, more preferably 20 µm or more and 300 µm or less, still more preferably 40 µm or more and 200 µm or less, particularly preferably 40 µm or more and 150 µm or less. By carrying out thickness of a protective sheet in the said range, sufficient toughness can be provided to a protective sheet, and winding of a protective sheet can be performed easily, and handling property improves.

As thickness of the polarizing plate bonded together with a polarizer using the said protective sheet, 150 micrometers or more and 800 micrometers or less are preferable, 180 micrometers or more and 700 micrometers or less are more preferable, 200 micrometers or more and 600 micrometers or less are more preferable. By carrying out thickness of a polarizing plate in the said range, sufficient toughness can be given to a polarizing plate, and winding property of a polarizing plate can be performed easily, and handleability improves.

In the protective sheet, the retardation value Re in the planar direction is preferably 0 nm or more and 15 nm or less. Moreover, it is preferable that retardation value Rth of thickness direction is -15 nm or more and 0 nm or less. Here, the retardation value Re in the planar direction and the retardation value Rth in the thickness direction are defined by equations (a) and (b), respectively.

Re1 = (nx1-ny1) × d [nm] (a)

Rth1 = {(nx1 + ny1) / 2-nz1} × d [nm] (b)

Here, nx1 is a principal refractive index of the protective sheet in the planar direction. ny1 is the refractive index of the direction orthogonal to nx1. nz1 is the main refractive index in the thickness direction of the protective sheet. d is the thickness of the protective sheet.

It is preferable that the protective sheet is subjected to mat processing on one side or both sides. Thereby, the effect that it becomes easy to stick the surface on which the mat process was given to another member through an adhesive agent etc. is exhibited. For example, the protective sheet can be firmly adhered to the polarizer by attaching the surface on which the mat processing has been applied to one surface of the sheet-shaped polarizer with a water-based adhesive to produce a polarizing plate.

It is preferable that the said protective sheet is equipped with the hard-coat layer laminated | stacked on one side. The hard coat layer can improve the scratch resistance of the protective sheet. Moreover, it is preferable that this hard-coat layer is formed by coating an acrylic paint. Thereby, transparency of the said protective sheet can be maintained.

The haze of the protective sheet is not particularly limited, but is preferably 3% or less, more preferably 2% or less.

<Polarizing plate>

The protective sheet can be used as a polarizing plate protective sheet. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the polarizing plate of embodiment of this invention. As shown in FIG. 1, the polarizing plate has a pair of protective sheets 1 and a plate-shaped polarizer 2 interposed between the pair of protective sheets 1. The said protective sheet 1 and the polarizer 2 are stuck by adhesive (not shown), such as aqueous glue, for example. For example, each of the pair of protective sheets 1 is laminated on both surfaces of the polarizer 2 via an adhesive layer, whereby a polarizing plate is formed.

<Liquid crystal display element>

The polarizing plate provided with the protective sheet 1 can be used in a liquid crystal display device. It is sectional drawing of the liquid crystal display element of embodiment of this invention. As shown in FIG. 2, the liquid crystal display element has a liquid crystal panel 3 and a pair of polarizing plates arranged one by one on each of both surfaces of the liquid crystal panel 3. As described above, the polarizing plate is a plate in which a pair of protective sheets 1 and a polarizer 2 interposed between the pair of protective sheets 1 are laminated through an adhesive. Each of the liquid crystal panel 3 and a pair of polarizing plates is stuck by adhesive 4, such as an ultraviolet curable adhesive.

<Other embodiment>

In addition, this invention is not limited to the said embodiment, A various design change is possible, It is also possible to perform mat processing to the single side | surface or both surfaces of the said protective sheet. Thereby, the effect that it becomes easy to adhere | attach the surface on which the mat process was given to another member through an adhesive agent etc. is exhibited. In the polarizing plate of FIG. 3, the mat layer 5 is formed on one side of each of the pair of protective sheets 1. And the polarizer 2 is arrange | positioned between the mat layers 5 of this pair of protective sheet 1, and the mat layer 5 and the polarizer 2 are stuck by the water-based adhesive agent (not shown). This mat layer 5 can be formed using a mat agent, and specifically, the coating liquid containing a mat agent can be coated on the single side | surface of the protective sheet 1, and the mat layer 5 can be formed. As the mat agent, organic or inorganic fine particles can be used, and for example, silica, talc, calcium carbonate, precipitated barium sulfate, alumina, acidic clay, clay, magnesium carbonate, carbon black, tin oxide, titanium white, Urea powder resin etc. can be used.

3, it is also possible to employ | adopt the structure by which the hard-coat layer 6 was laminated | stacked on the single side | surface of the said protective sheet. In the polarizing plate of FIG. 3, in one of the pair of protective sheets 1, the hard coat layer 6 is laminated on the surface of the protective sheet 1 that is not opposed to the polarizer 2. Thereby, the scratch resistance of the protective sheet 1 can be improved. The hard coat layer 6 is formed by coating an acrylic paint. Thereby, the hard-coat layer 6 also ensures transparency, and the transparency of the protective sheet 1 can be maintained.

(Example 1)

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

<Production of Heat Resistant Acrylic Resin>

Synthesis Example 1

(Heat resistant acrylic resin (A-1):

(Synthesis of methyl methacrylate-styrene-methacrylic acid-backbone 6-membered ring lactone)

As a monomer, 35 mass parts of methyl methacrylates, 25 mass parts of styrene, 15 mass parts of (alpha)-hydroxymethyl acrylates, 8 mass parts of methacrylic acid, 20 mass parts of metha xylenes as a polymerization reaction, Nippon Yushi Corporation make Perhexa C "(1,1-di (tert-butylperoxy) cyclohexane) 50 mass ppm, and the mixed liquid which consists of 1500 mass ppm of n-octyl mercaptans as a molecular weight regulator were prepared. This mixed solution was continuously supplied to a 3 L-jacketed complete mixing reactor at a feed rate of 1.5 L / hr, and polymerization was performed at a temperature of 125 ° C. The main chain by dehydration from the hydroxymethyl group and the methoxycarbonyl group bonded to the polymer main chain by continuously supplying the polymerization reaction liquid derived from the reactor to a high temperature degassing apparatus having a residence time of 2 hours set at a temperature of 260 ° C. The production | generation reaction of 6-membered ring lactone and the removal of unreacted material were performed. After that, heat treatment was performed to obtain a heat resistant acrylic resin (A-1). The heat-resistant acrylic resin (A-1) was analyzed by neutralization titration, IR spectrum, and ¹³ C-NMR. As a result, methyl methacrylate-derived structural unit, styrene-derived structural unit, and main chain 6-membered ring lactone-containing structural unit were analyzed. And the content of each of the structural units derived from methacrylic acid were 45% by mass, 30% by mass, 18% by mass and 7% by mass. Moreover, the melt flow rate value (ASTM-D1238; 230 degreeC, 3.8 kg load) of heat resistant acrylic resin (A-1) was 1.1 g / 10min, glass transition temperature (Tg) was 135 degreeC, and refractive index was 1.528.

Synthesis Example 2

(Heat resistant acrylic resin (A-2):

(Synthesis of methyl methacrylate-α-methylstyrene-methacrylic acid-backbone 6-membered ring lactone)

As a monomer, 48 mass parts of methyl methacrylate, 18 mass parts of (alpha) -methylstyrene, 8 mass parts of (alpha)-hydroxymethyl acrylates, 5 mass parts of methacrylic acid, 40 mass parts of tert-butanol as a polymerization solvent, as a polymerization initiator 500 mass ppm of 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane and 200 mass ppm of n-octyl mercaptans as a molecular weight regulator were prepared. This mixed solution was continuously supplied to a 3 L-jacketed complete mixing reactor at a feed rate of 1.5 L / hr, and polymerization was carried out at a temperature of 125 ° C. The polymerization reaction liquid derived from the said reactor was continuously supplied to the high temperature degassing apparatus of the residence time of 2 hours set to the temperature of 260 degreeC, and the main chain 6-membered ring lactone formation reaction and removal of unreacted material were performed. After that, heat treatment was performed to obtain a heat resistant acrylic resin (A-2). The heat resistant acrylic resin (A-2) was analyzed by neutralization titration, IR spectrum, and ¹³ C-NMR, and as a result, methyl methacrylate-derived structural unit, α-methylstyrene-derived structural unit, and main chain 6-membered ring lactone were analyzed. Each content rate of the containing structural unit and the methacrylic acid derived structural unit was 80 mass%, 11 mass%, 6 mass%, and 3 mass%. Moreover, the melt flow rate value (ASTM-D1238; 230 degreeC, 3.8 kg load) of heat resistant acrylic resin (A-2) was 1.5 g / 10min, glass transition temperature (Tg) was 132 degreeC, and refractive index was 1.504.

<Production of Acrylic Rubber>

Synthesis Example 3

(Acrylic rubber fine particles of three-layer structure)

300 mass parts of ion-exchange water was charged to the reaction container with a stirrer, and it heated up at 70 degreeC, carrying out nitrogen substitution, and then 0.3 mass parts of sodium dihexyl sulfosuccinate and 0.3 mass parts of potassium persulfate were added. Subsequently, a mixture consisting of 23 parts by mass of methyl methacrylate, 2 parts by mass of n-acrylic acid-n-butyl, and 0.03 parts by mass of allyl methacrylate was added, and the polymerization reaction was completed for 1 hour. Subsequently, after adding the mixture which consists of 22 mass parts of n-butyl acrylate, 28 mass parts of styrene, and 1.0 mass part of allyl methacrylate as a monomer over 2 hours, it maintained for 2 hours and completed reaction. Furthermore, after adding the monomer mixture which consists of 22 mass parts of methyl methacrylates, 3 mass parts of n-butyl acrylates, and 0.05 mass part of n-octyl mercaptans as a molecular weight modifier as a monomer over 1 hour, hold | maintains for 1 hour, and completes reaction. I was. After the obtained latex was salted out using sodium sulfate as a salting agent, dehydration, water washing, dehydration, and drying were performed, and acrylic rubber (B-1) was obtained as powder. The particle size of the obtained acrylic rubber fine particles (B-1) was 45 nm, and the refractive index was 1.519.

Synthesis Example 4

(Synthesis of Acrylic Rubber Fine Particles in Two-Layer Structure)

300 mass parts of ion-exchange water was charged to the reaction container with a stirrer, and it heated up at 70 degreeC, replacing with nitrogen, and 0.3 mass parts of sodium dihexyl sulfosuccinates and 0.3 mass parts of potassium persulfate were charged. Subsequently, after adding the mixture which consists of 24 mass parts of n-butyl acrylates, 28 mass parts of styrene, and 2.0 mass parts of allyl methacrylate as a monomer over 2 hours, it maintained for 2 hours and completed reaction. Subsequently, after adding the mixture which consists of 45 mass parts of methyl methacrylate as a monomer, 3 mass parts of n-butyl acrylates, and 0.05 mass part of n-octyl mercaptan as a molecular weight modifier over 1 hour, it hold | maintained for 1 hour and completed reaction. . The resulting latex was salted out using sodium sulfate as a salting agent, and then dehydrated, washed with water, dehydrated and dried to obtain acrylic rubber fine particles (B-2) having a two-layer structure as powder. The particle size of the obtained acrylic rubber fine particles (B-2) was 49 nm, and the refractive index was 1.518.

<Production of Protective Sheet>

Example 1

45 mass parts of heat resistant acrylic resin (A-1) obtained by the said synthesis example, 15 weight part of (A-2), 20 mass parts of acrylic rubber microparticles (B-1), and 20 mass parts of (B-2) After blending, 0.3 wt% of fine particles for giving an active function to the surface of the protective sheet 1 are added, and the screw rotation speed, the in-cylinder resin temperature of the extruder, and the temperature of the T die are adjusted using a T-die extruder. The protective sheet of Example 1 was obtained by shape | molding, carrying out fine extending | stretching (extension 3%) after extrusion.

EXAMPLE 2-6

The addition of 0.3% by weight of fine particles in Example 1 was changed to add 0.2% by weight in Example 2, and changed to 0.18% by weight in Example 3, and changed to 0.15% by weight in Example 4. And in Example 5, it changed so that 0.12 weight% may be added and in Example 6, it changed so that 0.1 weight% may be added. This obtained the protective sheet of each Example.

[Comparative Example]

In addition, the microparticles | fine-particles were not added in the comparative example that 0.3 weight% of microparticles | fine-particles in Example 1 were added. This obtained the protective sheet of a comparative example.

[evaluation]

The surface roughness Ra of the protective sheets of Examples 1-6 and the comparative example was measured at 10 places, and the average surface roughness of each protective sheet was computed. Table 1 shows the average surface roughness of each protective sheet.

As apparent from Table 1, it was found that the surface roughness of the protective sheet to which the fine particles were added 0.15% by weight was the largest. In addition, if the addition amount is constant, the surface roughness does not increase even if the addition amount is increased, and if the addition amount is 0.1 wt% or more and 0.2 wt% or less, a preferable surface roughness is obtained. It turned out that it was obtained.

EXAMPLES 7-11

In Example 4, when the elongation was 3%, the elongation was changed to 0.5% in Example 7, the elongation was changed to 1% in Example 8, the elongation was changed to 5% in Example 9, and the elongation was 7% in Example 10. In Example 11, the elongation was changed to 10%. This obtained the protective sheet of each Example.

[evaluation]

The surface roughness Ra of the protective sheets of Examples 7-11 and Example 4 was measured at ten places, the average surface roughness of each protective sheet was computed, and haze was also measured. In addition, haze was measured using the double beam system haze computer (HZ-2) by the Sugashi Kenki Corporation. Table 2 shows the results of each protective sheet.

As is clear from Table 2, even when the elongation is 0.5%, a constant surface roughness is obtained, but it can be seen that a sufficient surface roughness is obtained when the elongation is 1% or more. If the elongation is 10%, sufficient surface roughness is obtained, but the haze becomes large. For this reason, in order to make haze about 2%, 7% or less of elongation is preferable, and in order to make haze 2% or less, it turned out that it is more preferable that elongation is 5% or less.

The polarizing plate of this invention can be used as a component of the liquid crystal display element incorporated in a liquid crystal display device. The protective sheet of this invention can be used as a polarizing plate component.

1 Protective sheet
2 polarizer
3 liquid crystal panel
4 glue
5 mat layer
6 hard coat floors

Claims (9)

As a protective sheet of the island-in-water structure which has a matrix phase containing heat-resistant acrylic resin as a main polymer, and a dispersed phase containing acrylic rubber as a main polymer,
The matrix phase contains fine particles,
A protective sheet, wherein the protective sheet is formed by fine stretching after extrusion. The protective sheet according to claim 1, wherein the elongation is at least 1% and at most 5%. The protective sheet according to claim 1, wherein an average particle diameter of the fine particles is 0.005 µm or more and 2 µm or less and a content of 0.005 mass% or more and 1 mass% or less. The protective sheet according to claim 1, wherein a content of the dispersed phase is 5% by mass or more and 40% by mass or less. The protective sheet according to claim 1, wherein the retardation value in the planar direction is 0 nm or more and 15 nm or less, and the retardation value in the thickness direction is -15 nm or more and 0 nm or less. The protective sheet according to claim 1, wherein the heat resistant acrylic resin has a ring structure in the main chain. The protective sheet according to claim 1, wherein mat processing is performed on one or both surfaces. The method of claim 1, further comprising a hard coat layer laminated on one side,
This hard coat layer is formed by coating an acrylic paint, The protective sheet characterized by the above-mentioned. With a sheet-shaped polarizer,
The polarizing plate provided with the pair of protective sheets of Claim 1 laminated | stacked on both surfaces of this polarizer via an adhesive bond layer.

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