TWI654237B - (meth)acrylic resin composition and (meth)acrylic resin film using the same - Google Patents

Abstract

Provided are a (meth) acrylic resin composition, a (meth) acrylic resin film using the composition and an extension film thereof, and a (meth) acrylic resin film or an extension film and a polarizing film containing the same. A polarizing plate in which the (meth) acrylic resin composition contains (meth) acrylic resin A and a glass transition temperature lower than that of (meth) acrylic resin A and a weight average molecular weight of 100,000 or more ( (Meth) acrylic resin B.

Description

(Meth) acrylic resin composition and (meth) acrylic resin film using the same

The present invention relates to a (meth) acrylic resin composition and a (meth) acrylic resin film using the same. The present invention also relates to a polarizing plate having a (meth) acrylic resin film.

In recent years, liquid crystal display devices that have low power consumption, operate at low voltage, and are lightweight and thin are widely used in information display devices such as mobile phones, portable information terminal devices, computer monitors, and televisions. Such information display devices require reliability under severe environments depending on the application. For example, the liquid crystal display device used in car navigation systems may have extremely high temperature and humidity in the car. Compared with ordinary televisions and personal computer screens, stricter temperature and humidity conditions are required. . Moreover, when a polarizing plate is used in a liquid crystal display device to enable display, among the liquid crystal display devices required to have such strict temperature and / or humidity conditions, the polarizing plate constituting the liquid crystal display device is also required to have high Durable.

Generally, a polarizing plate has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film, and the polarizing film includes a polyvinyl alcohol-based resin that adsorbs and aligns a dichroic dye. In addition, conventionally, cellulose triacetate is widely used in the protective film, and the protective film is adhered to the polarizing film through an adhesive containing an aqueous solution of a polyvinyl alcohol resin. However, the polarizing plate laminated with a protective film containing cellulose triacetate has high polar moisture, so when used for a long time in a high-humidity environment, the polarizing performance is low, or the protective film and polarizing film are degraded. A situation where peeling occurs.

Therefore, for example, as described in Japanese Patent Application Laid-Open No. 2011-123169, an attempt has been made to use a (meth) acrylic resin film having a lower moisture permeability than a cellulose triacetate film as a protective film for a polarizing plate. By using a (meth) acrylic resin film having a low moisture permeability as the protective film of the polarizing plate, it is possible to improve the moisture resistance of the polarizing plate.

However, the (meth) acrylic resin film has poor toughness (flexibility) and is easy to break. Therefore, when the film is formed by melt extrusion, the film is broken when the film is stretched. Or cracks and gaps. When cracks and gaps occur, the fragments may contaminate the process.

Japanese Unexamined Patent Publication No. 63-077963 and Japanese Unexamined Patent Publication No. 2012-018383 describe that by compounding rubber elastomer particles in a (meth) acrylic resin, the impact resistance and the impact resistance of the film can be improved. Improved film-forming properties when manufacturing thin films. By using this method, the impact resistance of the (meth) acrylic resin film can be improved and the toughness can be improved. But rubber When the content of the elastomer particles increases, the heat shrinkage of the film increases, and the heat resistance of the film, or even the heat resistance of the polarizing plate using the film, may decrease.

An object of the present invention is to provide a (meth) acrylic resin composition capable of forming a thin film exhibiting good toughness and low heat shrinkage, and a (meth) acrylic resin film using the composition. Another object of the present invention is to provide a polarizing plate having the (meth) acrylic resin film.

The present invention provides a (meth) acrylic resin composition, a (meth) acrylic resin film, a stretched film, and a polarizing plate shown below.

[1] A (meth) acrylic resin composition comprising (meth) acrylic resin A and (meth) acrylic resin A having a glass transition temperature lower than that of (meth) acrylic resin A and a weight average molecular weight of 100,000 or more Based) acrylic resin B.

[2] The (meth) acrylic resin composition according to [1], wherein the glass transition temperature of the (meth) acrylic resin A and the glass transition temperature of the (meth) acrylic resin B are The difference is below 20 ° C.

[3] The (meth) acrylic resin composition according to [1] or [2], which is a melt-kneaded product of the (meth) acrylic resin A and the (meth) acrylic resin B.

[4] A (meth) acrylic resin film containing the (meth) acrylic resin composition according to any one of [1] to [3].

[5] A stretched film obtained by stretching the (meth) acrylic resin film according to [4].

[6] A polarizing plate comprising: a polarizing film; and a (meth) acrylic resin film according to [4] or an extending film according to [5] laminated on at least one side of the polarizing film.

[7] The polarizing plate according to [6], wherein the (meth) acrylic resin film or the stretched film is laminated on one side of the polarizing film, and another transparent resin film is laminated on the other side.

According to the present invention, it is possible to provide a (meth) acrylic resin film and a stretched film thereof that exhibit good toughness, good handleability (bendability), and small heat shrinkage. Moreover, according to this invention, the polarizing plate with high heat resistance can be provided.

<(Meth) acrylic resin composition>

The (meth) acrylic resin composition of the present invention contains one or two or more (meth) acrylic resins A, and one or two or more glass transition temperatures are lower than the (meth) acrylic resin. A resin composition of (meth) acrylic resin B having a low resin A and a weight average molecular weight of 100,000 or more. When the (meth) acrylic resin composition of the present invention is used, it is possible to improve the shortcomings of the conventional (meth) acrylic resin film that is poor in operability (bendability) due to poor toughness, and it is possible to form a heat shrinkage ratio. Small (meth) acrylic resin film with good heat resistance.

By improving the toughness, it is possible to suppress film cracks and nicks that may occur when the (meth) acrylic resin composition is formed into a film and when the formed film is subjected to an extension treatment, and it is possible to suppress the formation of cracks and Process contamination caused by chips generated by the notches. Furthermore, by using a (meth) acrylic resin film or a stretched film containing a (meth) acrylic resin composition of the present invention which has a small heat shrinkage rate, as a protective film to be attached to a polarizing film, That is, the heat resistance of a polarizing plate can be improved.

In addition, in the present invention, the "(meth) acrylic resin" based on the "(meth) acrylic resin composition", "(meth) acrylic resin", and "(meth) acrylic resin film" This means methacrylic and / or acrylic, and the same applies to "(meth) acrylic" such as "(meth) acrylic monomer" described later.

The (meth) acrylic resin composition of the present invention includes a (meth) acrylic resin A having a high glass transition temperature and a (meth) acrylic resin B having a low glass transition temperature. When the glass transition temperature of the (meth) acrylic resin A to T _gA, the glass transition temperature of the (meth) acrylic resin B is defined as T _gB, T _gA and T _gB difference between the (T _gA -T _gB ) Is preferably below 20 ° C. By setting T _gA -T _gB to 20 ° C or lower, the above-mentioned effects (both improved toughness and improved heat resistance) can be easily exhibited. When T _gA -T _{gB is higher} than 20 ° C, sufficient heat resistance may not be obtained, or the heat resistance may be deteriorated compared to when a single (meth) acrylic resin is used alone.

Since the above-mentioned effects (both improved toughness and improved heat resistance) can be easily exhibited, T _gA -T _gB is preferably 3 ° C or higher, more preferably 7 ° C or higher, and more preferably 10 ° C or higher. . When T _gA -T _{gB is} less than 3 ° C, the meaning of using two types of (meth) acrylic resins is lacking, and there is a tendency that sufficient toughness or sufficient heat resistance cannot be obtained after film formation.

T _gA and T _gB are each selected so that T _gA -T _gB falls within the above range. From the viewpoint of both improving toughness and improving heat resistance, T _gA -T _gB is within the above range. It is preferable to select T _gA from a range of 100 ° C. or higher and T _gB from a range of 80 ° C. or higher. Each of T _gA and T _gB is usually 150 ° C. or lower, preferably 140 ° C. or lower.

The glass transition temperatures T _gA and T _gB can be measured in accordance with JIS K7121: 1987, and specifically can be measured using the method described in the items of the examples described later.

The weight average molecular weight M _wA of the (meth) acrylic resin A is not particularly limited, but may be in the range of 10,000 to 1,000,000, and preferably 200,000 or less. When M _{wA is} greater than 1,000,000, or when it is greater than 200,000 as the case may be, the melt viscosity of the (meth) acrylic resin composition becomes too high, and melt-kneading with (meth) acrylic resin B and The process of forming a (meth) acrylic resin composition into a film becomes difficult.

By setting the weight average molecular weight M _wB of the (meth) acrylic resin B to 100,000 or more, the above-mentioned effects (both improved toughness and improved heat resistance) can be exhibited. M _wB is preferably 120,000 or more, and more preferably 150,000 or more. When M _{wB is} less than 100,000, the obtained (meth) acrylic resin film may have insufficient improvement in toughness, or the toughness may be deteriorated compared to when a single (meth) acrylic resin is used alone.

The M _wB system may be, for example, 1,000,000 or less, and preferably 200,000 or less. When M _{wB is} more than 1,000,000, or when it is more than 200,000, the melt viscosity of the (meth) acrylic resin composition becomes too high, and the melt-kneading with (meth) acrylic resin A and the ( The process of forming a (meth) acrylic resin composition into a film becomes difficult. M _wB may be larger or smaller than M _wA , or may be the same degree (for example, the same) as M _wA .

The weight average molecular weights M _wA and M _wB are weight average molecular weights obtained by using gel permeation chromatography (GPC) and using a methacrylic resin (methyl methacrylate) as a standard sample, and specifically, they can be used. It measured by the method described in the item of the Example mentioned later.

The (meth) acrylic resins A and B are polymers containing a structural unit derived from a (meth) acrylic monomer. The (meth) acrylic resins A and B are typically polymers containing methacrylates, and it is preferred that methacrylates are used as the main body, that is, 50% by weight or more based on the total monomer amount. The polymer derived from the methacrylate-derived constitutional unit is more preferably a polymer containing 80% by weight or more of the methacrylate-derived constitutional unit. The (meth) acrylic resins A and B may each be a methacrylate homopolymer, or may be a structural unit derived from a methacrylate containing 50% by weight or more based on the total monomer amount and A copolymer of 50% by weight or more of a structural unit derived from another polymerizable monomer.

The methacrylic acid esters that can constitute the (meth) acrylic resins A and B are alkyl methacrylates that can be used. Examples include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and tert-butyl methacrylate. Alkyl methacrylate having 1 to 8 carbon atoms in alkyl groups such as esters, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and 2-hydroxyethyl methacrylate. The carbon number of the alkyl group is preferably 1 to 4. In the (meth) acrylic resins A and B, methacrylates may be used alone or in combination of two or more.

Among them, from the viewpoint of heat resistance, the (meth) acrylic resins A and B preferably contain a constituent unit derived from methyl methacrylate, and more preferably 50 weight based on the total monomer amount. The constituent unit is more than 80% by weight, and more preferably 80% by weight or more.

Examples of the other polymerizable monomers that can constitute the (meth) acrylic resins A and B include polymerizable monomers other than acrylate, methacrylate, and acrylate. As the acrylate, an alkyl acrylate can be used. Specific examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, third butyl acrylate, and acrylic acid. Alkyl acrylates having 1 to 8 carbon atoms in alkyl groups such as 2-ethylhexyl, cyclohexyl acrylate, and 2-hydroxyethyl acrylate. The carbon number of the alkyl group is preferably 1 to 4. In the (meth) acrylic resins A and B, only one kind of acrylate may be used alone, or two or more kinds may be used in combination.

Examples of polymerizable monomers other than methacrylate and acrylate include monofunctional monomers having one polymerizable carbon-carbon double bond in the molecule, and at least two polymerizable carbon-carbons in the molecule. As many double bonds The functional monomer is preferably a monofunctional monomer. Specific examples of monofunctional monomers include: styrene-based monomers such as styrene, α-methylstyrene, vinyl toluene, and halogenated styrene; cyanoolefins such as acrylonitrile and methacrylonitrile; Unsaturated acids such as acrylic acid, methacrylic acid, and maleic anhydride; N-substituted maleimide.

Specific examples of the polyfunctional monomer include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, and trimethylolpropane triacrylate; Such as allyl acrylate, allyl methacrylate, allyl cinnamate and other unsaturated carboxylic acid esters; such as diallyl phthalate, diallyl maleate, Polyallyl esters of polyacids such as allyl esters, triallyl isotricyanates, and the like; aromatic polyalkenyl compounds such as divinylbenzene. The polymerizable monomers other than methacrylate and acrylate may be used alone or in combination of two or more.

The preferred monomer composition of the (meth) acrylic resins A and B is based on the total monomer amount, 50 to 100% by weight of alkyl methacrylate, 0 to 50% by weight of alkyl acrylate, etc. The polymerizable monomers other than 0 to 50% by weight, preferably 50 to 99.9% by weight of alkyl methacrylates, 0.1 to 50% by weight of alkyl acrylates, and 0 to 50% by weight of polymerizable monomers other than these 49.9% by weight, more preferably 80 to 99.9% by weight of alkyl methacrylate, 0.1 to 20% by weight of alkyl acrylate, and 0 to 19.9% by weight of polymerizable monomers other than these.

By radically polymerizing the monomer composition containing the above monomers, (meth) acrylic resins A and B can be individually prepared. The monomer composition contains a solvent and a polymerization initiator as needed. The (meth) acrylic resins A and B have glass transition temperatures T _gA and T _gB and weight average molecular weights M _wA and M _wB , which can be adjusted by the type of monomer, the content ratio of each monomer, the polymerization conditions, and the polymerization. Degree and so on.

In addition, it is also effective to introduce a ring structure into the main chain of the polymer in a method for increasing the glass transition temperature of the (meth) acrylic resin. In particular, the ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic amidine structure, and a lactone structure. Specific examples include cyclic acid anhydride structures such as glutaric anhydride structure and succinic anhydride structure; cyclic fluorene imine structures such as glutarimide imine structure and succinimide structure; butyrolactone, valerolactone, etc Lactone ring structure. As the content of the ring structure in the main chain increases, the glass transition temperature of the (meth) acrylic resin can be increased. The cyclic acid anhydride structure and the cyclic fluorene imine structure can be introduced by the following methods: introduction by copolymerizing monomers having a cyclic structure such as maleic anhydride and maleimide Method; by dehydration after polymerization. A method of introducing a cyclic acid anhydride structure by a de-methanol condensation reaction; and a method of introducing a cyclic amidine structure by reacting an amine compound. A resin (polymer) having a lactone ring structure can be obtained by using the following method: After preparing a polymer having a hydroxyl group and an ester group in a polymer chain, it is heated and, if necessary, an organic phosphorus A method of cyclizing and condensing hydroxyl groups and ester groups of the obtained polymer to form a lactone ring structure in the presence of a compound catalyst.

Polymers having a hydroxyl group and an ester group in the polymer chain can be obtained by, for example, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, 2- (hydroxymethyl) Isopropyl acrylate, n-butyl 2- (hydroxymethyl) acrylate (Meth) acrylic acid esters having a hydroxyl group and an ester group, such as an ester, and tert-butyl 2- (hydroxymethyl) acrylate, are obtained as a part of the monomer. A more specific method for preparing a polymer having a lactone ring structure is described in, for example, Japanese Patent Application Laid-Open No. 2007-254726.

As long as the (meth) acrylic resin composition of the present invention contains (meth) acrylic resin A and (meth) acrylic resin B (the (meth) acrylic resin A and (meth) acrylic acid) The combination of the resin B) can include all the forms, but in order to effectively obtain the desired effect (both improving toughness and improving heat resistance), any of the following forms is preferred.

[a] A solid melt-kneaded product obtained by melt-kneading (meth) acrylic resin A and (meth) acrylic resin B; [b] (meth) acrylic resin A A liquid melt-kneaded product obtained by melt-kneading with (meth) acrylic resin B; and [c] solid or liquid (meth) acrylic resin A and solid or liquid A mixture of (meth) acrylic resin B.

The melt-kneaded products of [a] and [b] are typically melt-kneaded products obtained by finely mixing and dispersing (meth) acrylic resin A and (meth) acrylic resin B. In the present invention, the melt-kneaded product may be solid or liquid. The melt-kneaded product of the above [a] may be a molded product that has been processed into a desired shape, or may be a non-molded product. Examples of the shape of the molded product include a granular shape, a pellet shape, and a film shape. The melt-kneaded product of the above-mentioned [b] is, for example, a liquid state of a (meth) acrylic resin composition prepared by heating when forming into a film or the like, for example. Melt and mix.

The mixture of the above-mentioned [c] may be, for example, a solid (meth) acrylic resin A such as a granular or pellet shape, and a solid (meth) acrylic resin such as a granular or pellet shape. A mixture of B. Such a mixture can be used as a raw material for the melt-kneaded product of [a] or [b].

In the (meth) acrylic resin composition of the present invention, the content ratio of the (meth) acrylic resin A to the (meth) acrylic resin B is based on a weight ratio of 90/10 to 10/90 as It is preferably 80/20 to 20/80, and more preferably 80/20 to 40/60. By adjusting the content ratio within this range, a desired effect (both improved toughness and improved heat resistance) can be effectively obtained. When the content of the (meth) acrylic resin A is too large, the toughness of the obtained (meth) acrylic resin film tends to be insufficient. On the other hand, when the content of the (meth) acrylic resin B is too large, the heat shrinkage ratio of the obtained (meth) acrylic resin film tends to increase.

The (meth) acrylic resin composition of the present invention may contain one or two or more kinds of lubricants, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, ultraviolet absorbers, and infrared rays as required. Additives such as absorbents, antistatic agents, antioxidants, solvents.

When the lubricant is contained, the (meth) acrylic resin film containing the (meth) acrylic resin composition can be prevented from being taken up tightly when rolled up into a roll shape, thereby improving the performance. Package appearance in rolled state. The lubricant may have a function of improving the slippage of the surface of the (meth) acrylic resin film, and examples thereof include stearic acid compounds, (meth) acrylic compounds, and ester compounds. Especially stearic acid compounds Suitable for use as a lubricant.

Examples of stearic acid-based compounds that are lubricants include stearic acid itself, and also stearates such as methyl stearate, ethyl stearate, and monoglyceryl stearate; stearic acid Amine; such as sodium stearate, calcium stearate, zinc stearate, lithium stearate, magnesium stearate and other metal stearates; such as 12-hydroxystearic acid, 12-hydroxystearate, 12-hydroxystearic acid such as zinc 12-hydroxystearate, calcium 12-hydroxystearate, lithium 12-hydroxystearate, magnesium 12-hydroxystearate, and metal salts thereof. In particular, stearic acid is suitable for use.

The blending amount of the lubricant is in a range of usually 0.15 parts by weight or less, preferably 0.1 parts by weight or less, and more preferably 0.07 parts by weight or less based on 100 parts by weight of the total of the (meth) acrylic resins A and B. When the amount of the lubricant is too large, the lubricant may ooze out of the (meth) acrylic resin film or reduce the transparency of the film.

The ultraviolet absorber is a compound that absorbs ultraviolet rays having a wavelength of 400 nm or less. When a (meth) acrylic resin film containing a (meth) acrylic resin composition is used as a protective film for a polarizing film, an ultraviolet absorber can be added to the (meth) acrylic resin composition to make it The durability of a polarizing plate obtained by bonding this protective film to a polarizing film is improved. That is, when the (meth) acrylic resin film contains an ultraviolet absorber, the color tone of the polarizing plate using the film as a protective film is not deteriorated, and the ultraviolet rays can be efficiently blocked and the polarizing plate can be suppressed. Reduced polarization during long-term use.

As the ultraviolet absorber, for example, a diphenyl ketone ultraviolet absorber, a benzotriazole ultraviolet absorber, and acrylonitrile can be used. It is a well-known ultraviolet absorbent such as an ultraviolet absorbent.

Specific examples of the ultraviolet absorber include 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol ], 2- (2'-hydroxy-3'-third butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-third butyl-6- (5 -Chlorobenzotriazol-2-yl) phenol, 2,2'-dihydroxy-4,4'-dimethoxydiphenyl ketone, 2,2 ', 4,4'-tetrahydroxydiphenyl ketone. Among these, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] is One of the best UV absorbers.

The amount of the ultraviolet absorber can be adjusted so that the light transmittance of the (meth) acrylic resin film containing the (meth) acrylic resin composition at a wavelength of 370 nm or less is preferably 10% or less, and more preferably 5% or less, particularly preferably 2% or less. Moreover, it is also preferable to mix | blend an ultraviolet absorber so that the light transmittance of the (meth) acrylic-type resin film at a wavelength of 380 nm may be 25% or less, More preferably, it is 15% or less, Especially preferably, it is 7% or less. The amount of the ultraviolet absorber is appropriately adjusted so that the light transmittance of the (meth) acrylic resin film can satisfy the conditions disclosed herein.

The infrared absorber is a compound that absorbs infrared rays having a wavelength of 800 nm or more, and examples thereof include a nitroso compound or a metal complex salt thereof, a cyanine compound, a squarilium compound, and sulfur Nickel alkoxide complex salt compound, phthalocyanine compound, naphthalocyanine compound, triarylmethane compound, immonium compound, diimmonium compound, naphthoquinone compound, anthracene Quinone compounds, amine compounds, aminium salt compounds, Carbon black, indium tin oxide, antimony tin oxide, oxides, carbides, or borides of metals belonging to Groups 4A, 5A, or 6A of the periodic table. These infrared absorbers are preferably selected so as to be able to absorb the entire infrared rays (light in a range of about 800 to 1100 nm), and it is also possible to use two or more types in combination. The blending amount of the infrared absorber is preferably selected such that the light transmittance of the (meth) acrylic resin film containing the (meth) acrylic resin composition at a wavelength of 800 nm or more is 10% or less.

The timing of adding the (meth) acrylic resin composition to the additives is not particularly limited. For example, when the (meth) acrylic resin composition of the present invention is formed into a film and a molded product such as a (meth) acrylic resin film is produced, when the (meth) acrylic resin composition is in the form of [a] above In the case of solid mixtures belonging to [c], additives can be blended in the solid melt-kneaded product or mixture, followed by melt-kneading and forming a film by melt extrusion or the like. Alternatively, when preparing the melt-kneaded product of the form [a] and the mixture of the form [c], additives may be prepared in advance. When the (meth) acrylic resin composition is in the form [b] described above, additives can be added to the liquid melt-kneaded mixture, and then film formation can be performed by melt extrusion or the like.

<(Meth) acrylic resin film>

The (meth) acrylic resin film of the present invention is a film containing the (meth) acrylic resin composition of the present invention, and is typically a film composed of the (meth) acrylic resin composition of the present invention. Since the (meth) acrylic resin film of the present invention contains the above-mentioned (meth) acrylic resin composition of the present invention, it has excellent toughness, and therefore, the handleability (folding) (Bendability) is good, at the same time the heat shrinkage rate is small and has excellent heat resistance. The (meth) acrylic resin film can be obtained by forming the (meth) acrylic resin composition of the present invention into a film using a general film forming method. In particular, a melt extrusion film forming method can be suitably used.

The so-called melt extrusion film forming method generally refers to feeding a thermoplastic resin into an extruder and melting it, extruding a film-like molten resin from a T-shaped mold, and then directly drawing it onto a cooling roller to cool and solidify it. Method for continuously obtaining a long film. The thickness of the film can be determined by appropriately controlling the lip interval of the T-shaped mold. The thickness of the (meth) acrylic resin film is usually 200 μm or less, and preferably 40 to 150 μm.

The (meth) acrylic resin film can be a single-layer film or a multilayer film having two or more layers. To make a multilayer film, a co-extrusion method is usually used. In the aforementioned melt extrusion film forming method, a plurality of extruders are provided, and the molten resin after passing through each extruder is T-shaped. Extrusion is carried out in such a way that it becomes multilayer in the die. In addition, other methods for forming a multilayer film include a method in which a plurality of extruders and T-shaped molds are continuously arranged, and the extruded film-like molten resin is stacked to form a multilayer film. Method; for a single-layer film formed by forming a film, a method in which film-like molten resins are superimposed to form a multilayer film; a method of pressing a plurality of single-layer films formed by forming a film to form a multilayer film, etc. .

In the case of a (meth) acrylic resin film-based multilayer film, each layer may be formed of a (meth) acrylic resin composition having the same composition, or may be formed of a (meth) acrylic resin composition having a different composition. For example, it is also possible to use a layer containing an ultraviolet absorbent The method of layering the layers of the collector to change the composition of each layer of additives.

The average roughness of the centerline of at least one surface of the (meth) acrylic resin film is preferably about 0.01 to 0.05 μm. When a (meth) acrylic resin film is used as a protective film for a polarizing film, it is preferable that the surface with the center line average roughness of about 0.01 to 0.05 μm is a bonding surface with the polarizing film. The centerline average roughness is a value measured in accordance with a method prescribed by JIS B 0601.

When the average roughness of the centerline of the surface of the (meth) acrylic resin film is less than 0.01 μm, the films are likely to block each other when the film itself is rolled up, and the films are adhered to each other when pulled Since the film may be damaged, the workability may be poor. When the average roughness of the centerline of the surface of the (meth) acrylic resin film is more than 0.05 μm, when an adhesive is used on the surface to laminate the polarizing film, sufficient adhesion may not be obtained, and the film may not be obtained. The roughness of the surface causes the scattering of reflected light to be large. In the liquid crystal display device using the obtained polarizing plate, the display quality level such as whitening of the screen or decrease in contrast may be deteriorated.

The method of adjusting the surface roughness of the centerline of the (meth) acrylic resin film within the above range is not particularly limited. For example, in the melt extrusion film forming method, the surface system of the cooling roller is transferred to it. The contacted film surface can be a method using a cooling roll having a surface roughness within the above range.

The (meth) acrylic resin film may be contained in (a Base) Solvents remaining in acrylic resin A and / or B, or solvents derived from solvents added to the (meth) acrylic resin composition as needed, but in the (meth) acrylic resin film The amount of the residual solvent contained is preferably 0.01% by weight or less based on the weight of the film. The amount of the residual solvent can be determined as a weight reduction value after the (meth) acrylic resin film is heated at 200 ° C. for 30 minutes, or as a quantitative value by a gas chromatograph based on the amount of gas generated by the heating.

When the amount of the residual solvent is 0.01% by weight or less, for example, a polarizing plate formed by using a (meth) acrylic resin film as a protective film for a polarizing film is exposed to high temperatures. In a high-humidity environment, deformation of the protective film can be prevented, and at the same time, deterioration of optical performance of the protective film and the polarizing plate can be prevented.

The (meth) acrylic resin film having a residual solvent content of 0.01% by weight or less is, for example, an extruder that can be used for preparing a (meth) acrylic resin composition, or is used for film formation. It is obtained by providing a vent hole in an appropriate part of the extruder and depressurizing the inside of the extruder from the hole.

The (meth) acrylic resin film of the present invention may include a surface treatment layer laminated on the film. By providing a surface treatment layer to a (meth) acrylic-type resin film, a specific function can be provided according to the kind of surface treatment layer. To give an example of a surface treatment layer, for example, the following layers: [a] a hard coating to prevent surface abrasion, [b] an antistatic layer, [c] an anti-reflection layer, [d] an antifouling layer, [e] An anti-glare layer, which functions to improve visibility, prevent reflection of external light, and reduce moire caused by dryness of iris and color filters.

(Hard coating)

The hard coat layer has a function of improving the surface hardness of the (meth) acrylic resin film, and is provided to prevent surface abrasion and the like. The hard coating is a pencil hardness test specified in JIS K 5600-5-4: 1999 "General Test Methods for Coatings-Part 5: Mechanical Properties of Coating Films-Section 4: Scratch Hardness (Pencil Method)" An optical film having a hard coat layer was measured on a glass plate, and a value of H or harder was shown.

Materials that form a hard coat are usually those that harden due to heat and light. Examples include organic hard coating materials such as organic polysiloxane, melamine, epoxy, acrylic, and urethane acrylate, and inorganic hard coating materials such as silicon dioxide. Among these, a urethane acrylate-based or polyfunctional acrylate-based hard coating material is suitable because it has good adhesion to a (meth) acrylic resin film and excellent productivity.

The hard coat layer can contain various fillers for the purpose of adjusting the refractive index, improving the flexural modulus of elasticity, stabilizing the volume shrinkage rate, and improving the heat resistance, antistatic property, and anti-glare property as needed. The hard coat layer may also contain additives such as antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, leveling agents, and defoamers.

(Antistatic layer)

The antistatic layer is used to impart a surface to the (meth) acrylic resin film. It is provided for the purpose of conductivity and suppressing the influence caused by static electricity. The formation of the antistatic layer can be performed by, for example, applying a resin composition containing a conductive substance (antistatic agent) to a (meth) acrylic resin film. For example, an antistatic hard coat layer can be formed by coexisting an antistatic agent in the hard coat material used when forming the hard coat layer in advance.

(Anti-reflection layer)

The anti-reflection layer is a layer for preventing reflection of external light, and is provided on the surface of the (meth) acrylic resin film directly or through other layers such as a hard coat layer. The (meth) acrylic resin film having an anti-reflection layer preferably has a reflectance at an incident angle of 5 ° for light having a wavelength of 430 to 700 nm to be less than 2%, and more preferably has a light intensity of 550 nm for light. The reflectance at the same incident angle becomes 1% or less.

The thickness of the anti-reflection layer may be set to about 0.01 to 1 μm, and preferably 0.02 to 0.5 μm. The anti-reflection layer may include a refractive index that is smaller than the refractive index of the layer [(meth) acrylic resin film, hard coat layer, etc.] provided, and specifically 1.30 to 1.45 A low-refractive index layer having a refractive index; a low-refractive index layer of a thin film containing an inorganic compound and a high-refractive index layer of a thin film containing an inorganic compound are alternately laminated in a plurality of layers.

The material for forming the low-refractive index layer is not particularly limited as long as it has a smaller refractive index. For example, a resin material such as ultraviolet curable (meth) acryl fluorene-based resin; a mixed material obtained by dispersing inorganic fine particles such as colloidal silica in a resin; a sol-gel containing an alkoxysilane ( sol-gel) materials. Such a low refractive index layer can be borrowed It is formed by coating a polymer that has been polymerized, or it may be coated in the state of a monomer or oligomer of a precursor, and then polymerized and hardened to form it. In order to impart antifouling properties, each material preferably contains a compound having a fluorine atom in the molecule.

The sol-gel material used to form the low refractive index layer is suitable for those having a fluorine atom in the molecule. A typical example of a sol-gel material having a fluorine atom in the molecule is polyfluoroalkylalkoxysilane. The polyfluoroalkylalkoxysilane may be a compound represented by the following formula: CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃ Here, R represents an alkyl group having 1 to 5 carbon atoms. , N is an integer from 0 to 12. Especially preferred are compounds in which n is 2 to 6 in the above formula.

Specific examples of the polyfluoroalkylalkoxysilane include the following compounds.

3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3,3,4,4,5,5,6,6,7,7 , 8,8,8-tridecafluorooctyltrimethoxysilane, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyltriethyl Oxysilane, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10,10-heptadecafluorodecyltrimethoxysilane, and 3 , 3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltriethoxysilane and the like.

The low refractive index layer may be formed of a cured product of a thermosetting fluorine-containing compound or an active energy ray-hardening fluorine-containing compound. The hardened system preferably has a coefficient of dynamic friction in the range of 0.03 to 0.15 to prevent water The contact angle is preferably in the range of 90 to 120 °. Examples of the curable fluorinated compound include polysilane-containing silane compounds (for example, the above-mentioned 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10 , 10,10-heptadecafluorodecyltriethoxysilane, etc.), and fluoropolymers with crosslinkable functional groups.

The fluorine-containing polymer having a crosslinkable functional group can be produced by the following methods: 1) a method of copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group; or 2) using A method of copolymerizing a fluorine-containing monomer and a monomer having a functional group, and then adding a compound having a crosslinkable functional group to the above-mentioned functional group in the polymer.

Examples of the above-mentioned fluorine-containing single system include, for example, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxy Uh (perfluoro-2,2-dimethyl-1,3-dioxole) and other fluoroolefins; (meth) acrylic acid partially or fully fluorinated alkyl ester derivatives; (meth) acrylic acid fully or partially fluorinated ethylene Ethers.

Examples of the monomer having a crosslinkable functional group or the compound having a crosslinkable functional group include, for example, those having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate. Monomers; monomers with carboxyl groups such as acrylic acid and methacrylic acid; monomers with hydroxyl groups such as hydroxyalkyl acrylate and hydroxyalkyl methacrylate; monomers with olefins such as allyl acrylate and allyl methacrylate Monomer having amine group; monomer having amine group; monomer having sulfonic group.

The material used to form the low-refractive-index layer can improve scratch resistance, so it can be dispersed in fine particles containing inorganic compounds such as silica, alumina, titania, zirconia, and magnesium fluoride in an alcohol solvent. Made of sol. From the viewpoint of antireflection, the inorganic compound fine particles used for this purpose have a smaller refractive index, which is more preferable. The inorganic compound fine particles may be those having voids, and hollow fine particles of silicon dioxide are particularly preferred. The average particle diameter of the hollow fine particles is preferably in a range of 5 to 2000 nm, and particularly preferably in a range of 20 to 100 nm. The average particle diameter referred to herein means a number average particle diameter obtained by observation with a transmission electron microscope.

(Antifouling layer)

The antifouling layer is provided for imparting water repellency, oil repellency, sweat resistance, antifouling properties, and the like. A suitable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound system include fluorocarbon, perfluorosilane, and polymer compounds thereof. The formation method of the antifouling layer can be a physical vapor growth method, a chemical vapor growth method, a wet coating method, or the like, which are representative examples of vapor deposition and sputtering depending on the material to be formed. The average thickness of the antifouling layer is usually about 1 to 50 nm, and preferably 3 to 35 nm.

(Anti-glare layer)

The anti-glare layer is a layer having a fine uneven shape on the surface, and is preferably formed using the hard coating material.

The anti-glare layer having a fine uneven shape on the surface can be formed by the following methods: 1) forming a coating film containing fine particles on a (meth) acrylic resin film, and providing the unevenness based on the fine particles Method; 2) After forming a coating film containing fine particles or not containing fine particles on a (meth) acrylic resin film, press it onto a mold (roller, etc.) whose surface has been provided with an uneven shape, and transfer the uneven shape. Method (also known as embossing).

In the method 1), a (meth) acrylic resin film may be coated with a curable resin composition containing a curable transparent resin and fine particles, and the coating layer may be hardened by irradiation or heating with light such as ultraviolet rays. To form an anti-glare layer. The curable transparent resin is preferably selected from a material having a high hardness (hard coating). The curable transparent resin can be a photocurable resin such as an ultraviolet curable resin, a thermosetting resin, an electron beam curable resin, and the like. From the viewpoints of productivity and the hardness of the obtained anti-glare layer, A photocurable resin is preferably used, and an ultraviolet curable resin is more preferable. When a photocurable resin is used, the curable resin composition system further contains a photopolymerization initiator.

The photocurable resin system can usually use a polyfunctional (meth) acrylate. Specific examples include: di- or tri- (meth) acrylate of trimethylolpropane; tri- or tetra- (meth) acrylate of neopentyl tetraol; belonging to at least 1 hydroxyl group in the molecule A polyfunctional urethane (meth) acrylate which is a reaction product of (meth) acrylate and diisocyanate. These polyfunctional (meth) acrylates can be used individually or in combination of 2 or more types as needed.

In addition, it is also possible to prepare a mixture of a polyfunctional urethane (meth) acrylate, a polyol (meth) acrylate, and a (meth) acrylfluorene-based polymer having an alkyl group containing two or more hydroxyl groups. Light-curing resin. The polyfunctional urethane (meth) acrylate constituting the photocurable resin can be produced using, for example, (meth) acrylic acid and / or (meth) acrylate, a polyol, and a diisocyanate. Specifically, it can be adjusted in the molecule by using (meth) acrylic acid and / or (meth) acrylic acid ester and polyol. A hydroxy (meth) acrylate having at least one hydroxy group therein and reacted with a diisocyanate to produce a polyfunctional urethane (meth) acrylate. The polyfunctional urethane (meth) acrylate manufactured in this way also becomes the photocurable resin itself disclosed above. At the time of production, one type of (meth) acrylic acid and / or (meth) acrylic acid ester may be used, or two or more types may be used in combination. Similarly, one type of polyol and one diisocyanate may also be used. Two or more types can be used in combination.

The (meth) acrylate used as a raw material of the polyfunctional urethane (meth) acrylate is a chain or cyclic alkyl ester of (meth) acrylic acid. Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and the like ( Alkyl meth) acrylates, and cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate.

Polyols, which are another raw material of polyfunctional urethane (meth) acrylates, are compounds having at least two hydroxyl groups in the molecule. Examples include ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6- Hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol , Neopentyl glycol ester of hydroxytrimethylacetic acid, cyclohexanedimethanol, 1,4-cyclohexanediol, spiroglycol, tricyclodecane dimethylol, hydrogenated bisphenol A, epoxy Ethylene oxide addition to bisphenol A, propylene oxide addition to bisphenol A, trimethylolethane, trimethylolpropane, glycerol, 3-methylpentane-1,3 , 5-triol, neopentaerythritol, dinepentaerythritol, trinepentaerythritol, glucose, etc.

Multifunctional urethane (meth) acrylate is another kind of diisocyanate. It is a compound with 2 isocyanate groups (-NCO) in the molecule. It can be aromatic, aliphatic or alicyclic. Of various diisocyanates. Specific examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5 -Naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl diisocyanate, stub diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane Diisocyanates, and nuclear hydrides of diisocyanates having aromatic rings among them.

The polyhydric alcohol (meth) acrylate constituting the photocurable resin together with a polyfunctional urethane (meth) acrylate is a (formaldehyde) of a compound (that is, a polyol) having at least two hydroxyl groups in the molecule. Based) acrylate. Specific examples thereof include neopentaerythritol di (meth) acrylate, neopentaerythritol tri (meth) acrylate, neopentaerythritol tetra (meth) acrylate, and dipentaerythritol hexa ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, and the like. The polyol (meth) acrylate may be used alone or in combination of two or more. The polyhydric alcohol (meth) acrylate system preferably contains neopentyltetraol triacrylate and / or neopentyltetraol tetraacrylate.

In addition, the (meth) acrylfluorenyl group having an alkyl group containing two or more hydroxyl groups is formed in the photocurable resin together with the polyfunctional urethane (meth) acrylate and the polyol (meth) acrylate. A polymer is one having an alkyl group containing two or more hydroxyl groups in one constituent unit. For example, a polymer containing 2,3-dihydroxypropyl (meth) acrylate as a constituent unit, and a polymer containing 2,3-dihydroxypropyl (meth) acrylate and (meth) simultaneously Polymers such as 2-hydroxyethyl acrylate as a constituent unit.

As described above, by using the (meth) acrylic-based photocurable resin as exemplified above, it is possible to improve the adhesive strength with the (meth) acrylic resin film while improving the mechanical strength and effectively prevent the surface. Injured anti-glare film.

The fine particles are preferably those having an average particle diameter of 0.5 to 5 μm and a refractive index difference from the hardened transparent resin after hardening of 0.02 to 0.2. By using fine particles having an average particle diameter and a refractive index difference within this range, haze can be effectively exhibited. The average particle diameter of the fine particles can be obtained by a dynamic light scattering method or the like. The average particle diameter at this time is a weight average particle diameter.

The fine particles may be organic fine particles or inorganic fine particles. Resin particles can usually be used as the organic fine particle system, and examples thereof include crosslinked poly (meth) acrylic particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, and crosslinked polymethacrylic acid. Ester particles, silicone resin particles, polyimide particles, and the like. In addition, inorganic fine particles can be used: silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate Wait.

As the photopolymerization initiator system, various substances such as acetophenone system, diphenyl ketone system, benzoin ether system, amine system, and phosphine oxide system can be used. Examples of compounds classified as acetophenone-based photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone (alias: benzil dimethyl ketal )), 2,2-diethoxyacetophenone, 1- (4-isopropylphenyl) -2- Hydroxy-2-methylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-2-morpholinyl-1- (4-methylthiophenyl) propane-1-one. Examples of compounds classified as diphenylketone-based photopolymerization initiators include diphenylketone, 4-chlorodiphenylketone, and 4,4'-dimethoxydiphenylketone. Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether and benzoin propyl ether. Examples of compounds classified as amine-based photopolymerization initiators include N, N, N ', N'-tetramethyl-4,4'-diaminodiphenyl ketone (alias: Michelinone (Michler's ketone)). Examples of the phosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzylidene diphenylphosphine oxide. In addition, xanthone-based compounds, thioxanthone-based compounds, and the like can also be used as photopolymerization initiators.

These photopolymerization initiators are commercially available. Examples of representative commercially available products are listed under the product name, such as "IRGACURE 907", "IRGACURE 184", and "LUCIRIN TPO" sold by BASF, Germany.

The curable resin composition contains a solvent as needed. As the solvent, any organic solvent that can dissolve each component constituting the curable resin composition, such as ethyl acetate and butyl acetate, can be used. It is also possible to use a mixture of two or more organic solvents.

The curable resin composition may contain a leveling agent, and for example, a fluorine-based or silicone-based leveling agent can be used. Polysiloxane-based leveling agents include reactive polysiloxane, polydimethylsiloxane, polyether-modified polydimethylsiloxane, polymethylalkylsiloxane, and the like. Polysilicone-based leveling agents are particularly preferred, which are reactive polysilicone and silicone-based leveling agents. Use contains In the case of a reactive polysiloxane leveling agent, it can impart lubricity to the surface of the anti-glare layer, and can continue to have excellent scratch resistance for a long period of time. When a silicone-based leveling agent is used, film formability can be improved.

On the other hand, when the method (embossing method) of 2) is used to form the anti-glare layer having a fine surface uneven shape, a mold having a fine uneven shape is used to transfer the shape of the mold to (meth) The resin layer formed on the acrylic resin film may be sufficient. When an embossing method is used to form a fine surface uneven shape, the resin layer system to which the uneven shape is transferred may or may not contain fine particles. The resin constituting the resin layer is preferably a photocurable resin as exemplified in the method 1), and is more preferably an ultraviolet curable resin. However, instead of the ultraviolet curable resin, a visible light curable resin that can be cured under visible light having a longer wavelength than ultraviolet rays by appropriately selecting a photopolymerization initiator can be used.

In the embossing method, a curable resin composition containing a photocurable resin such as an ultraviolet curable resin is applied to a (meth) acrylic resin film, and the coating layer is pressed against the uneven surface of a mold. While being hardened, the uneven surface of the mold was transferred to the coating layer. More specifically, ultraviolet rays are irradiated from the (meth) acrylic resin film side while the curable resin composition is applied to the (meth) acrylic resin film and the coating layer is adhered to the uneven surface of the mold. The coating layer is cured by waiting for light, and then the (meth) acrylic resin film having the cured coating layer (anti-glare layer) is peeled from the mold, and the uneven shape of the mold is transferred to the anti-glare layer.

The thickness of the anti-glare layer is not particularly limited, but is usually 2 to 30 μm, preferably 3 μm or more, and more preferably 20 μm or less. When the anti-glare layer is too thin, sufficient hardness cannot be obtained, and the surface tends to be easily injured. On the other hand, when the anti-glare layer is too thick, cracks may occur easily, or the hardening shrinkage of the anti-glare layer may cause the film to curl and reduce productivity The tendency.

The haze value of the (meth) acrylic resin film having an anti-glare layer is preferably in a range of 5 to 50%. When the haze value is too small, sufficient anti-glare performance cannot be obtained. If a polarizing plate provided with a (meth) acrylic resin film with such an anti-glare layer is applied to an image display device, external light is likely to be reflected on the screen Situation. On the other hand, when the haze value is too large, although the reflection of external light can be reduced, the sharpness of the screen displayed in black is low. The haze value is a ratio of the diffusion transmittance to the total light transmittance, and can be measured in accordance with JIS K 7136: 2000 "Method for Obtaining Haze of Plastic-Transparent Materials".

<Stretch film>

The stretched film of the present invention is a thin film obtained by stretching the (meth) acrylic resin film of the present invention described above. Since the stretched film of the present invention also contains the (meth) acrylic resin composition of the present invention described above, it has excellent toughness, and therefore has good handleability (bendability), and has a small heat shrinkage and excellent heat resistance. Sex.

Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include a mechanical flow direction (MD) of an unstretched film, a direction (TD) orthogonal to the film, and a direction obliquely crossing the mechanical flow direction (MD). Biaxial extension can be simultaneous biaxial extension in two extension directions, or sequential biaxial extension after extending in a predetermined direction first and then in other directions.

The stretching process can be performed in the longitudinal direction (mechanical flow direction: MD) by using two or more pairs of nip rolls that increase the peripheral speed on the exit side, or hold the unstretched film with a chuck The two side ends of the lens are expanded in a direction orthogonal to the mechanical flow direction (TD), and are performed.

The stretching ratio of the stretching treatment is preferably greater than 0 to 500%, and more preferably 100 to 300%. When the stretching ratio is more than 300%, the film thickness becomes too thin and easily breaks, or the operability is deteriorated. The stretch magnification is calculated according to the following formula: stretch magnification (%) = 100 × {(length after stretching)-(length before stretching)} / (length before stretching)

The elongation temperature is set to a temperature at which the (meth) acrylic resin film can be stretched so that the entire (meth) acrylic resin film exhibits fluidity. The glass transition temperature of the (meth) acrylic resin film is preferably from -40 ° C to In the range of + 40 ° C, more preferably in the range of -25 ° C to + 25 ° C, and particularly preferably in the range of -15 ° C to + 15 ° C.

The thickness of the stretched film is usually 100 μm or less, and preferably 10 to 80 μm.

<Polarizer>

The polarizing plate of the present invention includes: a polarizing film; and the (meth) acrylic resin film of the present invention or the stretched film of the present invention, which is laminated on at least one side of the polarizing film. The (meth) acrylic resin film and the stretched film can be protective films that protect the polarizing film. In the polarizing plate of the present invention, the (meth) acrylic resin film or stretched film of the present invention may be laminated on both sides of the polarizing film, or the (methyl) of the present invention may be laminated on one side of the polarizing film. ) Acrylic resin film or stretched film, and other transparent resin film with a protective film or retardation film laminated on the other surface. These (meth) acrylic resin films, stretch films, transparent resin films, and polarizing film systems can be bonded using an adhesive.

(Polarizing film)

The polarizing film can be produced according to a known method through the following steps: a step of uniaxially stretching the polyvinyl alcohol resin film; and dyeing the polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye. A step of treating a polyvinyl alcohol-based resin film having adsorbed a dichroic pigment with a boric acid aqueous solution; and a step of washing with a boric acid aqueous solution after treatment. The polarizing film obtained in this way is one having an absorption axis in the direction after the uniaxial stretching.

As the polyvinyl alcohol-based resin, one obtained by saponifying a polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth) acrylamidoamines having an ammonium group, and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may also be modified. For example, polyvinyl formal, polyvinyl acetal, etc. modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000. It is preferably about 1500 to 5000.

A film made of such a polyvinyl alcohol-based resin can be used as a base film of a polarizing film. The method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a known method can be adopted. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, and is, for example, about 10 to 150 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before, simultaneously with, or after dyeing with a dichroic pigment. When uniaxial stretching is performed after dyeing, the uniaxial stretching system may be performed before or during a boric acid treatment. It is also possible to perform uniaxial extension in these plural stages.

Uniaxial stretching can be performed by separating rollers with different peripheral speeds, or by using heat roller clamping. The uniaxial stretching system may be dry stretching in the air, or wet stretching in a state where the polyvinyl alcohol-based resin film is swollen with a solvent such as water and an organic solvent. The stretching ratio is usually about 3 to 8 times.

Dyeing a polyvinyl alcohol-based resin film using a dichroic dye can be performed, for example, by immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic pigment system, boron and a dichroic organic dye can be used. It is preferable that the polyvinyl alcohol-based resin film be immersed in water before the dyeing treatment.

When boron is used as a dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing boron and potassium iodide and dyed is generally adopted. The content of boron in this aqueous solution is relative to 100 weight The amount of water is usually about 0.01 to 1 part by weight. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. The immersion time (dyeing time) in the aqueous solution is usually about 20 to 1800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic organic dye and is usually dyed is used. The content of the dichroic organic dye in the aqueous solution is usually about 1 × 10 ^-4 to 10 parts by weight, and preferably about 1 × 10 ^-3 to 1 part by weight, per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dichroic dye aqueous solution used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) in the aqueous solution is usually about 10 to 1800 seconds.

The boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. The content of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, and preferably 5 to 12 parts by weight, per 100 parts by weight of water. When boron is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time in an aqueous solution containing boric acid is usually about 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. Contains boron The temperature of the acid aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

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

After washing with water, a polarizing film is obtained by drying. The drying process can be performed using a hot-air dryer and a far-infrared heater. The temperature of the drying process is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The time of the drying treatment is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

The moisture content of the polarizing film is reduced to a practical level by the drying process. Its moisture content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film may be lost and the polarizing film may be damaged or broken after it is dried. On the other hand, when the moisture content is more than 20% by weight, the thermal stability of the polarizing film tends to be insufficient.

The thickness of the polarizing film with the dichroic pigment adsorbed and aligned obtained in this manner can usually be about 5 to 40 μm.

(Transparent resin film)

As described above, the surface of the polarizing film to which the (meth) acrylic resin film or the stretched film of the present invention is bonded is the surface on the opposite side, and other transparent resin films can be bonded. The transparent resin film may be a protective film of a polarizing plate or a retardation film.

The transparent resin film system can be, for example, a cellulose triacetate film, a polycarbonate film, a polyethylene terephthalate film, a (meth) acrylic resin film, a (meth) acrylic resin layer, and a polycarbonate resin. Laminated laminated films, olefin-based resin films, and the like. In particular, an olefin-based resin film can be suitably used.

The olefin resin refers to, for example, polymerization of a chain olefin monomer such as ethylene and propylene, or a cyclic olefin monomer such as norbornene and other cyclopentadiene derivatives using a polymerization catalyst. And the obtained resin.

Examples of the olefin-based resin obtained from the chain-shaped olefin monomer include a polyethylene-based resin and a polypropylene-based resin. In particular, polypropylene-based resins which are homopolymers of propylene are preferred. Also, a polypropylene-based copolymer resin obtained by copolymerizing propylene as a main component and copolymerizing a comonomer with the propylene as a main component is usually 1 to 20% by weight, preferably 3 to 10% by weight. Better.

The comonomer capable of copolymerizing with propylene is preferably ethylene, 1-butene or 1-hexene. Among them, because of its excellent transparency and stretchability, it is particularly suitable for the use of ethylene, and a polypropylene-based copolymer resin obtained by copolymerizing ethylene at a ratio of 1 to 20% by weight, especially at a ratio of 3 to 10% by weight One of the better. By setting the copolymerization ratio of ethylene to 1% by weight or more, the effects of improving transparency and stretch processability can be exhibited. On the other hand, when the ratio is more than 20% by weight, the melting point of the resin decreases, and the heat resistance required for the protective film or the retardation film may be impaired.

Polypropylene resins can be easily obtained in the market. For example, "PRIME POLYPRO" sold by Prime Polymer Co., Ltd. under the brand name, "NOVATEC" and "WINTEC" sold by POLYPRO Corporation of Japan are mentioned. "Sumitomo NOBLEN" sold by Sumitomo Chemical Co., Ltd., "Sunallomer" sold by Sunallomer Co., Ltd., etc.

The olefin-based resin obtained by polymerizing a cyclic olefin monomer is generally also referred to as a cyclic olefin-based resin, an alicyclic olefin-based resin, or a norbornene-based resin. This is called a cyclic olefin resin.

Examples of the cyclic olefin-based resin system include ring-opening of norbornene or a derivative thereof obtained from a cyclopentadiene and an olefin via a Diels-Alder reaction as a monomer, Resin obtained by metathesis polymerization and then by hydrogenation; tetracyclododecene or its derivative obtained from Dicyclopentadiene and olefins or (meth) acrylates through Diels-Adel reaction As a monomer, a resin obtained by ring-opening metathesis polymerization and then by hydrogenation; using two or more kinds of norbornene, tetracyclododecene, derivatives thereof, or other cyclic olefin monomers, A resin obtained by ring-opening metathesis and copolymerization in the same manner and then obtained by hydrogenation; at least one cyclic olefin selected from the group consisting of norbornene, tetracyclododecene, and derivatives thereof, and ethylene A resin or the like obtained by addition copolymerization of an aliphatic or aromatic compound of a radical.

Cyclic olefin-based resins can also be easily obtained in the market. For example, the cyclic olefin resins are each manufactured by TOPAS ADVANCED POLYMERS GmbH of Germany and traded in Japan. "TOPAS" sold by POLYPLASTICS AG is manufactured by JSR AG. "ARTON" for sale is manufactured by Japan Zeon Corporation. "ZEONOR" and "ZEONEX" sold are manufactured by Mitsui Chemicals Corporation. "APEL" etc. for sale.

By forming the film of the above-mentioned linear olefin-based resin or cyclic olefin-based resin and forming a thin film, a transparent resin film to be bonded to one side of the polarizing film can be produced. The method for forming a thin film is not particularly limited, and a melt extrusion film forming method is suitable.

Commercial products can also be easily obtained from olefin-based resin films. For example, if it is a polypropylene-based resin film, "FILMAX CPP film", which is a brand name and sold by FILMAX, and SunTox Corporation, can be cited. "SUNTOX" sold, "TOHCELLO" sold by Tohcello Co., Ltd., "TOYO PAIREN FILM" sold by Toyo Textile Co., Ltd., "TORAYFAN" sold by TORAY Film Processing Co., Ltd., and Japan Polyace Co., Ltd. "Nippon Polyace" sold, "Taihe FC" sold by Futaura Chemical Co., Ltd., etc. In the case of a cyclic olefin-based resin film, "ZEONOR film" sold under the brand name and sold by Japan Zeon Corporation, and "ARTON film" sold by JSR Corporation can be cited.

For a transparent resin film, an optically functional film may be laminated on the surface, or an optically functional layer may be coated. Examples of such an optically functional film and optically functional layer include an easy-adhesive layer, a conductive layer, and a hard coat layer.

By extending the olefin-based resin film described above and providing the film with refractive index anisotropy, the function of the retardation film can be provided. Delay The stretching method may be appropriately selected in accordance with the required refractive index anisotropy, and is not particularly limited. For example, a longitudinal uniaxial stretching, a transverse uniaxial stretching, or a biaxial stretching in the vertical and horizontal directions can be adopted.

Because olefin-based resins have a positive refractive index anisotropy, and the refractive index becomes the largest in the direction of stress, a film system formed by uniaxially extending it usually provides n _x > n _y ≒ n _z . Refractive index anisotropy. Here, the refractive index of the in-plane slow axis direction of the n _x- based film (the direction in which the refractive index becomes the largest in the plane, and the direction of extension in the case of a resin having positive refractive index anisotropy), and the refractive index of the n _y- based film The refractive index in the inner fast axis direction (the direction orthogonal to the slow axis in the plane), n _z is the refractive index in the normal direction of the film. Thin film systems in which olefin-based resins are sequentially biaxially stretched generally provide refractive index anisotropy of n _x > n _y > n _z .

In addition, in order to provide the required refractive index characteristics, a retardation film can be produced by bonding a heat-shrinkable film to the intended film instead of stretching or shrinking the film while stretching. . This operation is usually performed in order to obtain a retardation film having a refractive index anisotropy of n _x > n _z > n _y or n _z > n _x ≧ n _y .

A retardation film containing an olefin-based resin can also easily obtain a commercially available product. Examples of retardation films containing cyclic olefin-based resins include "ZEONOR film" sold under the brand name and sold by Japan Zeon Corporation, "ARTON film" sold by JSR Corporation, and Sekisui Chemical "S-SINA retardation film" sold by Industrial Corporation.

(Adhesive)

The bonding of the (meth) acrylic resin film or the stretched film and the polarizing film, and the bonding of the polarizing film and the transparent resin film can be performed as described above. Prior to bonding, at least one of the bonding surface of the (meth) acrylic resin film or the stretched film and the polarizing film and the bonding surface of the polarizing film and the (meth) acrylic resin film or the stretched film are at least Corona discharge treatment, plasma irradiation treatment, and electron beam irradiation treatment are performed in advance on at least one of the bonding surface between the polarizing film and the transparent resin film and the bonding surface between the transparent resin film and the polarizing film. 2. Other surface activation treatments are better.

The adhesive used at the time of lamination can be arbitrarily selected and used from those who exhibit adhesion to the laminated film. Typical examples include: water-based adhesives, even if the adhesive components are dissolved in water, or the adhesive components are dispersed in water; and active energy rays containing components that harden by irradiating active energy rays are hardened. Sex adhesive. From the viewpoint of productivity, it is suitable to use an active energy ray-curable adhesive.

First, when a water-based adhesive is described, for example, a composition using a polyvinyl alcohol-based resin and a urethane resin as main components may be mentioned as a preferable adhesive.

When a polyvinyl alcohol-based resin is used as a main component of the water-based adhesive, the polyvinyl alcohol-based resin may be partially saponified polyvinyl alcohol or completely saponified polyvinyl alcohol, and, for example, carboxyl-modified polyvinyl alcohol, ethyl acetamidine Modified polyvinyl alcohol resins such as modified polyvinyl alcohol, methylol modified polyvinyl alcohol, and amino modified polyvinyl alcohol. When a polyvinyl alcohol-based resin is used as an adhesive component, the adhesive system is mostly an aqueous solution prepared as a polyvinyl alcohol-based resin. Concentration of polyvinyl alcohol resin in aqueous solution of adhesive The degree refers to 100 parts by weight of water, usually about 1 to 10 parts by weight, and preferably 1 to 5 parts by weight.

In order to improve adhesion, it is preferable to add a hardening component such as glyoxal and a water-soluble epoxy resin or a cross-linking agent to the water-based adhesive containing a polyvinyl alcohol resin as a main component. Examples of the water-soluble epoxy resin system include polyamine polyamines obtained by reacting polyalkylene polyamines such as diethylene glycol and triethylene glycol with dicarboxylic acids such as adipic acid. Polyamine epoxy resin obtained by reacting with epichlorohydrin. Commercially available products of such polyamidopolyamine epoxy resins are "Sumirez Resin 650" and "Sumirez Resin 675" sold by Taoka Chemical Industry Co., Ltd., and "WS- 525 ", etc., may be suitable for use. The addition amount of such a hardening component or a crosslinking agent is usually 1 to 100 parts by weight, and preferably 1 to 50 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin. When the added amount is small, the adhesiveness-improving effect becomes small. On the other hand, when the added amount is large, the adhesive layer tends to become brittle.

When a urethane resin is used as the main component of the water-based adhesive, examples of a suitable adhesive composition include a polyester-based ionic polymer-type urethane resin and a resin having a glycidyloxy group. A mixture of compounds. The polyester-based ionic polymer-type urethane resin referred to herein means a urethane resin having a polyester skeleton and a small amount of an ionic component (hydrophilic component) introduced therein. The ionic polymer urethane resin is emulsified in water without using an emulsifier and becomes an emulsion, so it is suitable as an aqueous adhesive. The use of a polyester-based ionic polymer-type urethane resin for the bonding of a polarizing film and a protective film is described in, for example, In Japanese Patent Laid-Open No. 2005-70139, Japanese Patent Laid-Open No. 2005-70140, and Japanese Patent Laid-Open No. 2005-181817.

On the other hand, when an activated energy ray-curable adhesive is used, the component constituting the adhesive that is hardened by irradiating the active energy ray (hereinafter, referred to as a "curable component" for short) may be a ring. Oxygen compounds, oxetane compounds, (meth) acrylic compounds, and the like. When using a cationic polymerizable compound such as an epoxy compound and an oxetane compound, a cationic polymerization initiator is prepared. When a radical polymerizable compound such as a (meth) acrylic compound is used, a radical polymerization initiator is prepared. Among them, it is particularly preferable to use an epoxy compound as one of the hardening components, and an alicyclic epoxy compound having an epoxy group directly bonded to a saturated carbocyclic ring as one of the hardening components. The agent is particularly good. It is also effective to use an oxetane compound in combination.

Epoxy compounds are easily available on the market. For example, there are "EPICOAT" series sold by JAPAN EPOXY RESINS Co., Ltd. under their respective trade names, "Epiclon" series sold by DIC Co., Ltd., and Totsu Kasei Co., Ltd. The "EpoTohto" series sold, the "ADEKARESIN" series sold by ADEKA AG, the "DENACOL" series sold by NAGASE CHEMTEX AG, the "Dow Epoxy" series sold by DOW Chemical, and Nissan Chemical Industries "TEPIC", etc., sold by a stock company.

An alicyclic epoxy compound having an epoxy group directly bonded to a saturated carbocyclic ring can also be easily obtained on the market, for example, "CELLOXIDE" which is a brand name and is sold by Daicel Chemical Industry Co., Ltd. Series and "CYCLOMER" series, "Cyracure" series sold by DOW Chemical, etc.

The oxetane compounds can also be easily obtained in the market, for example, there are "ARON OXETANE" series sold under the trade name of Toa Kosei Co., Ltd., and "ETERNACOLL" series sold by Ube Kosan Co., Ltd.

Cationic polymerization initiators can also easily obtain commercially available products, such as the "KAYARAD" series sold under the brand name and sold by Nippon Kayakusho, the "Cyracure" series sold by Union Carbide, and the SAN- A series of photoacid generators "CPI" sold by APRO AG, photoacid generators "TAZ", "BBI" and "DTS" sold by MIDORI Chemicals AG, and "ADEKA OPTOMER" sold by ADEKA AG Series, "RHODORSIL" series sold by Rhodia, etc.

The active-energy-ray-curable adhesive system can contain a photosensitizer as needed. By using a photosensitizer, reactivity can be improved, and the mechanical strength and adhesive strength of the adhesive layer can be further improved. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfide, a redox compound, an azo and diazo compound, an anthracene compound, a halogen compound, and a photoreducing dye.

Moreover, various additives can be mix | blended in the range which does not impair the adhesiveness of an active-energy-ray-hardenable adhesive agent. Examples of the additive system include ion trapping agents, antioxidants, chain transfer agents, adhesion-imparting agents, thermoplastic resins, fillers, flow modifiers, plasticizers, and defoamers. Agent. In addition, a hardening component that can be hardened by a reaction mechanism different from the cationic polymerization can be prepared within a range that does not impair its adhesiveness.

When a film is bonded using an active energy ray-curable adhesive, the film is bonded through a layer including the adhesive, and then the active energy ray is irradiated to harden the adhesive layer. The active energy ray-curable adhesive used on one side of the polarizing film and the active energy ray-curable adhesive used on the other side may have the same composition or different compositions, but are used to harden the two. The irradiation of active energy rays is preferably performed simultaneously.

The active energy rays used for curing the active energy ray-curable adhesive are, for example, X-rays having a wavelength of 1 to 10 nm, ultraviolet rays having a wavelength of 10 to 400 nm, and visible rays having a wavelength of 400 to 800 nm. Among them, in particular, in terms of ease of use, ease of preparation of active energy ray-curable adhesives, stability, and curing performance, ultraviolet rays are suitable for use. The ultraviolet light source can be, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, and the like having a light emission distribution below a wavelength of 400 nm.

The thickness of the adhesive layer obtained using the active energy ray-curable adhesive is usually about 1 to 50 μm, and particularly preferably in the range of 1 to 10 μm.

Since the polarizing plate of the present invention uses the (meth) acrylic resin film or stretched film of the present invention as a protective film to be bonded to a polarizing film, it is not easy to deform and optical even in a high temperature environment. Degraded characteristics and excellent heat resistance.

The polarizing plate of the present invention is a polarizing plate that can be suitably used as a liquid crystal panel used in a liquid crystal display device, and is particularly suitable as a polarizing plate that is arranged on the viewing side of a liquid crystal cell. When the polarizing plate of the present invention is arranged on the viewing side of the liquid crystal cell, the polarizing plate arranged on the back side of the liquid crystal cell may be the polarizing plate of the present invention or another polarizing plate. The liquid crystal cell constituting the liquid crystal panel can be various liquid crystal cells used in this field.

The polarizing plate is bonded to the liquid crystal cell and can be performed through an adhesive layer formed in advance on the surface of the polarizing plate. The adhesive layer can be laminated on one of the protective films included in the polarizing plate. For example, the (meth) acrylic resin film or the stretched film of the present invention is laminated on one side of the polarizing film, and the other side is laminated on the other side. In a polarizing plate made of a transparent resin film, an adhesive layer can be provided on the outer surface of the transparent resin film. When this polarizing plate is used as a viewing-side polarizing plate and is bonded to a liquid crystal cell through an adhesive layer, it becomes a liquid crystal panel in which a (meth) acrylic resin film or a stretched film is arranged on the viewing side.

Generally, an adhesive layer is formed by the following (meth) acrylic adhesive: (meth) acrylic acid ester as a main component, and a (meth) acrylic monomer containing a functional group Copolymerized (meth) acrylic resin as a (meth) acrylic adhesive as an adhesive component.

<Example>

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, the contents and percentages and parts used are based on weight unless otherwise specified.

In the following examples and comparative examples, the resin described in the following [A] (hereinafter referred to as "resin A") was used as the (meth) acrylic resin A, and the following [B1] or [B2 ] (Hereinafter referred to as "resin B1" and "resin B2") as (meth) acrylic resin B.

[A] "Altglas HT121" (glass transition temperature T _gA : 124 ° C, weight average molecular weight M _wA : 78200, number average molecular weight M _nA : 41200, molecular weight dispersion M _wA / M _nA : 1.9), [B1] a methyl methacrylate resin containing 80% by weight or more of a structural unit derived from methyl methacrylate (glass transition temperature T _gB : 110 ° C., weight average molecular weight M _wB : 162000 Number average molecular weight M _nB : 84500, molecular weight dispersion M _wB / M _nB : 1.9), [B2] a methyl methacrylate resin (glass transfer) containing 80% by weight or more of a structural unit derived from methyl methacrylate Temperature T _gB : 107 ° C., weight average molecular weight M _wB : 134000, number average molecular weight M _nB : 67000, molecular weight dispersion M _wB / M _nB : 2.0).

<Example 1>

The pelletized resin A and the pelletized resin B1 were put into an extruder at a weight ratio of 75:25 to prepare a (meth) acrylic resin composition, and the mixture was heated and melt-kneaded to obtain a liquid state. Melt and mix. This melt-kneaded liquid mixed resin was continuously extruded in a film form from a T-shaped mold, and was cured using a cooling roller to form a long (meth) acrylic acid having a thickness of 120 μm. System resin film [unstretched product].

In addition, the unstretched product was subjected to a uniaxial stretching process in the longitudinal direction to produce a stretched film with a thickness of 96 μm [longitudinal stretched product]. The elongation temperature is set to a glass transition temperature of an unstretched product (that is, the above-mentioned mixed resin) + 10 ° C, and the elongation ratio is set to 2.2 times.

Furthermore, a 40 μm-thick stretch film [horizontal and vertical stretch product] is produced by performing a sequential biaxial stretching process in which the unstretched product is longitudinally stretched and then laterally stretched. The elongation temperature means that the glass transition temperature of the unstretched product (that is, the above-mentioned mixed resin) is + 10 ° C in both the longitudinal extension and the lateral extension, and the extension ratios of the longitudinal extension and the lateral extension are set to 2.2 times and 2.0 times, respectively.

<Examples 2 to 4, Comparative Examples 1 to 4>

The resin composition used in the production of the (meth) acrylic resin film [unstretched product] was the same as in Example 1 except that the mixed resin (melt-kneaded product) or a single resin described in Table 1 was used. Then, a (meth) acrylic resin film [unstretched product] was prepared. Moreover, using this unstretched product, it carried out similarly to Example 1, and produced the longitudinally stretched product and / or the longitudinally stretched product. Furthermore, in Comparative Example 2, the rubber particles blended in the resin A use the following: elastomer particles containing a three-layer structure of an innermost layer, an intermediate layer, and an outermost layer, wherein the innermost layer contains A rigid polymer polymerized by methyl methacrylate and a small amount of allyl methacrylate. The intermediate layer is based on butyl acrylate as the main component and contains polymerized by using styrene and a small amount of allyl methacrylate. The softest elastomer is made of a hard polymer that is polymerized by using methyl methacrylate and a small amount of ethyl acrylate. The particle size is 240 nm.

For the mixed resins (melt-kneaded products) or single resins used in the examples and comparative examples, the following physical properties were measured, and the unstretched products, longitudinally stretched products, and vertical and horizontal directions obtained in each of the examples and comparative examples were measured at the same time. The extended product was subjected to the following evaluation tests. The results are shown in Table 1.

(1) Weight average molecular weight, number average molecular weight and molecular weight dispersion of mixed resin or single resin

40 mg of pellet-shaped mixed resin or pellet-shaped single resin was dissolved in 20 mL of tetrahydrofuran to prepare a measurement sample, and the dissolution time and strength were measured using a GPC device. From these measured values, a weight average molecular weight M _w and a number average molecular weight M _n were obtained using a calibration curve obtained using a standard sample as a reference, and a molecular weight dispersion M _w / M _{n was} calculated.

The details of the GPC measurement conditions are as follows.

． GPC device: "HLC-8320GPC" made by TOSOH ． Gel Permeation Chromatography Columns: Each is composed of one "TSKgel-SuperHZ2500" made by TOSOH and two "TSKgel-SuperHRC" connected in series. ． Column temperature: 40 ℃, ． Detector: RI detector, ． Measuring sample injection volume: 20 μL, ． Mobile phase: tetrahydrofuran, ． Flow rate of mobile phase: 1.0mL / min, ． Standard sample: Seven types of monodisperse methyl methacrylate (all manufactured by Showa Denko Corporation) with known weight average molecular weight.

(2) Glass transition temperature of mixed resin or single resin

Using a DSC device ["DSC7020" manufactured by Seiko Instruments Co., Ltd.], a pellet-shaped mixed resin or a pellet-shaped single resin was flowed at a nitrogen flow rate of 100 ml / min in accordance with a differential scanning thermal analysis method based on JIS K7121: 1987. After increasing the temperature to 150 ° C at a temperature increasing rate of 20 ° C / min and holding it for 5 minutes, the temperature was lowered to 10 ° C / minute to -50 ° C and maintaining the temperature for 1 minute. Next, the temperature was raised from −50 ° C. to 210 ° C. at a heating rate of 10 ° C./minute, and the intermediate point glass transition temperature (Tmg) was determined and set as the glass transition temperature. A larger value indicates higher heat resistance.

(3) Evaluation of toughness of unstretched product or stretched product

(3-1) Mandrel test

From the film, a test piece having a length of 120 mm and a width of 10 mm with the mechanical extrusion direction (MD) of the film as the length direction was cut out. For this test piece, a bending resistance tester (cylindrical mandrel method) manufactured by TP Giken Co., Ltd. was used to wind the test piece around the cylindrical mandrel and bend the test piece along its width direction. The core rod bending test is to determine the minimum diameter of a core rod that does not cause cracks, nicks, cracks, or breaks in the film. The smaller the value of the minimum diameter, the better the toughness of the film, and the better the handleability and processability. The mandrel test is performed on unstretched products and longitudinally stretched products.

(3-2) Charpy impact test

Measured in accordance with JIS K 7111: 2006 "Plastics-Charpy-type flushing characteristics-Part 1: Non-instrumentation-based flushing test" specified in the Chabill-type flushing test for measuring the energy absorbed by plastics . Specifically, first, the film is cut out from the film in the mechanical extrusion direction (MD) of the film. It is a test piece with a length of 82 mm and a width of 10 mm in the longitudinal direction. The above-mentioned JIS standard is prescribed for a case where a test piece with a notch is used and a case where a test piece without a notch is used, and in the present invention, it is a test piece without a notch. Next, in order to prevent the test piece from moving due to punching when punched with a hammer, the two ends of the test piece in the long side direction are fixed to the support table, and a Chaba punch of Yasuda Seiki Co., Ltd. is used. The testing machine (weight measurement by 1.0J) measures the energy required for film breakage (impact absorption energy, mJ) by striking the hammer with its blade length in the center of the test piece's longitudinal direction parallel to the width direction. . The greater the energy absorbed by the impact, the less cracks, nicks, cracks, and fractures will occur in the film, and the toughness will be good, and the film will have excellent handleability and processability. The measurement of the Chabbe-type shock absorption energy is performed on an unstretched product.

(3-3) Number of film breaks when manufacturing a longitudinally stretched product from an unstretched product

The total number of film breakages that occur when a longitudinally extended product of a certain length (approximately 50 m) is produced from a long unstretched product under the above-mentioned stretching conditions. The smaller the number of breaks, the better the toughness of the film and the more excellent the processability.

(4) Evaluation of heat resistance of unstretched products or stretched products

(4-1) Measurement of heat shrinkage

A test piece with a length of 120 mm and a width (TD direction: a direction orthogonal to the MD) of 120 mm with the film's mechanical extrusion direction (MD) as the length direction was cut out from the film. The MD direction and the TD direction were respectively from the center. Mark 50 points (two places) from the beginning. About this test piece, the heating test which stood still in the oven at 100 degreeC for 10 minutes was performed. Using digital cursor cards Digital vernier calipers measure the amount of dimensional change (length between marks) in the MD and TD directions before and after the heating test. For the MD and TD directions, calculate the heat shrinkage (%) according to the following formula: heating Shrinkage (%) = 100 × (length before heating-length after heating) / (length before heating) The smaller the heat shrinkage, the more excellent the heat resistance. The measurement of the heat shrinkage ratio is performed for an unstretched product and a longitudinally stretched product.

(4-2) Determination of high temperature tensile elastic modulus

A tensile tester ("AUTOGRAPH AG-1" manufactured by Shimadzu Corporation) was used to perform a tensile test under a condition of a temperature of 80 ° C and a tensile speed of 1 mm / minute to measure the tensile elastic modulus of the film. (MPa). The higher the tensile elastic modulus, the more excellent the heat resistance. The measurement of the high-temperature tensile elastic modulus is performed for a longitudinally and vertically stretched product.

Claims (11)

A (meth) acrylic resin composition containing (meth) acrylic resin A and (meth) with a glass transition temperature lower than that of (meth) acrylic resin A and a weight average molecular weight of 100,000 or more Acrylic resin B, wherein the difference between the glass transition temperature of the (meth) acrylic resin A and the glass transition temperature of the (meth) acrylic resin B is 10 ° C or higher and 20 ° C or lower, and the (meth) acrylic acid The glass transition temperature of the series resin B is 110 ° C or lower. A (meth) acrylic resin composition containing (meth) acrylic resin A and (meth) with a glass transition temperature lower than that of (meth) acrylic resin A and a weight average molecular weight of 100,000 or more Acrylic resin B, wherein the difference between the glass transition temperature of the (meth) acrylic resin A and the glass transition temperature of the (meth) acrylic resin B is 10 ° C or higher and 20 ° C or lower, and the (meth) acrylic acid The resin B is a polymer containing 80% by weight or more of a constituent unit derived from an alkyl methacrylate. The (meth) acrylic resin composition according to item 1 or 2 of the patent application scope, wherein the glass transition temperature of the (meth) acrylic resin A and the glass transition of the (meth) acrylic resin B The temperature difference is 14 ° C or more. The (meth) acrylic resin composition according to item 1 or 2 of the patent application scope, which is a melt-kneaded product of the (meth) acrylic resin A and the (meth) acrylic resin B. The (meth) acrylic resin composition according to item 1 or 2 of the scope of patent application, wherein the weight average molecular weight of the (meth) acrylic resin B is 134,000 or more. The (meth) acrylic resin composition according to item 1 or 2 of the patent application scope, wherein the glass transition temperature of the (meth) acrylic resin A is 100 ° C or higher. The (meth) acrylic resin composition according to item 1 or 2 of the patent application scope, wherein the glass transition temperature of the (meth) acrylic resin B is 80 ° C. or higher. A (meth) acrylic resin film containing the (meth) acrylic resin composition as described in item 1 or 2 of the scope of patent application. An extension film is obtained by extending the (meth) acrylic resin film described in item 8 of the scope of patent application. A polarizing plate comprising: a polarizing film; and a (meth) acrylic resin film as described in item 8 of the scope of patent application or as described in item 9 of the scope of patent application being laminated on at least one side of the polarizing film. Of stretch film. The polarizing plate according to item 10 of the scope of patent application, wherein the (meth) acrylic resin film or the stretched film is laminated on one side of the polarizing film, and another transparent resin film is laminated on the other side. .