KR20150050418A - (meth)acrylic resin composition and (meth)acrylic resin film using the same - Google Patents

Abstract

Provided are a (meth)acrylic resin composition including a (meth)acrylic resin A, and a (meth)acrylic resin B which has the glass transition temperature lower than the (meth) acrylic resin A and has greater than or equal to 100,000 of the weight average molecular weight; a (meth)acrylic resin film using the same and an elongated film thereof; and a polarizing plate including the (meth)acrylic resin film or the elongated film, and a polaroid film.

Description

TECHNICAL FIELD The present invention relates to a (meth) acrylic resin composition and a (meth) acrylic resin film using the same. BACKGROUND ART [0002]

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.

2. Description of the Related Art In recent years, a liquid crystal display device that consumes a small amount of power and operates at a low voltage and is lightweight and thin has been widely used in information display devices such as cellular phones, portable information terminals, computer monitors, and televisions. Such an information display device is required to have reliability under a severe environment depending on its use. For example, in a car navigation system liquid crystal display device, the temperature and humidity inside the vehicle in which it is placed may become very high, and the temperature and humidity conditions required are more stringent than those of ordinary monitors for a television or a personal computer. In a liquid crystal display device, a polarizing plate is used to enable the display. In a liquid crystal display device requiring such a strict temperature and / or humidity condition, a polarizing plate constituting it is required to have high durability.

The polarizing plate usually has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film made of a polyvinyl alcohol resin in which a dichroic dye is adsorbed and oriented. Conventionally, triacetyl cellulose is widely used for this protective film, and this protective film is bonded to the polarizing film through an adhesive composed of an aqueous solution of polyvinyl alcohol resin. However, the polarizing plate in which the protective film made of triacetylcellulose is laminated has a high moisture permeability of triacetyl cellulose, so that when the polarizing plate is used for a long time under a high humid environment, the polarization performance deteriorates or the protective film and the polarizing film peel off have.

Therefore, it has been attempted to use a (meth) acrylic resin film having a lower moisture permeability as a protective film of a polarizing plate than a triacetyl cellulose film, as disclosed in, for example, Japanese Patent Laid-Open Publication No. 2011-123169. Improvement in moisture resistance of the polarizing plate is expected by using a (meth) acrylic resin film having a low moisture permeability as a protective film of the polarizing plate.

However, the (meth) acrylic resin film tends to break due to its toughness (flexibility), so that when the film is formed by melt extrusion or when the formed film is subjected to stretching treatment, the film may be broken, cracked, or torn . If cracks or irregularities occur, the debris may contaminate the manufacturing process.

Japanese Patent Application Laid-Open Nos. 63-077963 and 2012-018383 disclose that when rubber elastomer particles are blended with a (meth) acrylic resin, the impact resistance when formed into a film and the film formability at the time of film formation Can be improved. According to this method, the impact resistance of the (meth) acrylic resin film can be improved and the toughness can be improved. However, if the content of the rubber elastomer particles is increased, the heat shrinkage of the film becomes large, and the heat resistance of the film, and furthermore, the heat resistance of the polarizing plate using the film may be deteriorated.

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

The present invention provides the following (meth) acrylic resin composition, (meth) acrylic resin film, stretched film and polarizer.

[1] A resin composition comprising the (meth) acrylic resin A,

(Meth) acrylic resin B having a lower glass transition temperature than the (meth) acrylic resin A and a weight average molecular weight of 100000 or more

(Meth) acrylic resin composition.

[2] The (meth) acrylic resin composition according to [1], 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 20 ° C. or less.

[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)

[4] A (meth) acrylic resin film comprising 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 film,

(Meth) acrylic resin film according to [4] or a stretched film according to [5], which is laminated on at least one surface of the polarizing film

.

[7] The polarizer 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.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a (meth) acrylic resin film exhibiting a good toughness and having a good handleability (bending property) and a small heat shrinkage ratio and a stretched film thereof. Further, according to the present invention, a polarizing plate having high heat resistance can be provided.

≪ (Meth) acrylic resin composition >

The (meth) acrylic resin composition of the present invention comprises one or more of (meth) acrylic resins A and a (meth) acrylic resin having a glass transition temperature lower than that of the (meth) acrylic resin A and a weight average molecular weight of 100000 or more Resin B, and the like. According to the (meth) acrylic resin composition of the present invention, it is possible to improve the drawbacks of the conventional (meth) acrylic resin film in which the toughness is lowered and the handling property (bending property) is deteriorated, and the heat shrinkage rate is low Meth) acrylic resin film can be formed.

The improvement in toughness makes it possible to suppress the cracking or peeling of the film which may be caused when the (meth) acrylic resin composition is formed or when the film formed is subjected to the stretching treatment, and the cracks or cracks Contamination can be suppressed. Further, the heat resistance of the polarizing plate can be improved by using a (meth) acrylic resin film having a small heat shrinkage ratio of the (meth) acrylic resin composition of the present invention or a stretched film thereof as a protective film to be bonded to a polarizing film.

In the present invention, "(meth) acrylic" in the "(meth) acrylic resin composition", "(meth) acrylic resin" and "(meth) acrylic resin film" means methacrylic and / This also applies to "(meth) acrylic" in the "(meth) acrylic monomers" described later.

The (meth) acrylic resin composition of the present invention comprises a (meth) acrylic resin A having a higher glass transition temperature and a (meth) acrylic resin B having a lower glass transition temperature. (Meth) when the glass transition temperature of the acrylic resin A T _gA, (meth) the glass transition temperature of the acrylic resin B in T _gB, T _gA and T _gB difference (T _{gA gB} -T) is of not more than 20 ℃ desirable. When T _gA -T _{gB is set} to 20 ° C or lower, the above-mentioned effects (both improvement in toughness and improvement in heat resistance) are likely to occur. If T _gA -T _gB is more than 20 캜, sufficient heat resistance can not be obtained or heat resistance may be deteriorated rather than when one type of (meth) acrylic resin is used alone.

T _gA -T _gB is preferably 3 ° C or higher, more preferably 7 ° C or higher, and more preferably 10 ° C or higher, since the above-mentioned effect (both of improvement in toughness and improvement in heat resistance) desirable. When T _gA -T _gB is less than 3 캜, the significance of using two kinds of (meth) acrylic resins is lowered, and toughness can not be obtained when the film is formed, or sufficient heat resistance can not be obtained.

T _gA and T _gB are preferably selected so that T _gA -T _gB falls within the above range. From the viewpoint of both improvement in toughness and improvement in heat resistance, T _{gA and} T _gB are selected so that T _gA -T _gB is within the above range 100 deg. C or higher, and _TgB is preferably selected in the range of 80 deg. C or higher. T _gA and T _gB are each usually 150 ° C or lower, preferably 140 ° C or lower.

The glass transition temperatures T _gA and T _gB are measured in accordance with JIS K 7121: 1987, and specifically can be measured by the method described in the section of Examples to be described later.

The weight average molecular weight M _wA of the (meth) acrylic resin A is not particularly limited and may be, for example, in the range of 10,000 to 1,000,000, preferably 200,000 or less. The melt viscosity of the (meth) acrylic resin composition becomes excessively high when the _MwA exceeds 1, ₀₀₀₀₀ , or in some cases, exceeds 200,000, so that melt kneading with the (meth) acrylic resin B and melt kneading with the (meth) The molding process may not be easy.

The weight average molecular weight _MwB of the (meth) acrylic resin B is 100000 or more, whereby the above-described effect (both improvement in toughness and improvement in heat resistance) can be achieved. M _wB is preferably at least 120000, more preferably at least 150000. If M _wB is less than 100000, improvement in toughness of the resulting (meth) acrylic resin film may become insufficient, or toughness may be deteriorated rather than when one type of (meth) acrylic resin is used alone.

M _wB can be, for example, 1000000 or less, but is preferably 200000 or less. When the M _wB is more than 100,000 or more than 200,000 in some cases, the melt viscosity of the (meth) acrylic resin composition becomes excessively high and the melt viscosity of the (meth) acrylic resin A and the melt viscosity of the The molding process may not be easy. M _wB may be larger or smaller than M _wA , or may be the same as M _wA (for example, the same).

The weight average molecular weights M _wA and M _wB are weight average molecular weights obtained by using gel permeation chromatography (GPC) with a methacrylic resin (methyl methacrylate) as a standard sample. Specifically, the weight average molecular weights Of the present invention.

(Meth) acrylic resins A and B are polymers containing constituent units derived from (meth) acrylic monomers. The (meth) acrylic resins A and B are typically polymers containing methacrylic acid esters, preferably methacrylic acid esters as the main components, that is, based on the total amount of monomers, methacrylic acid ester- Is a polymer containing at least 50% by weight of constituent units, and more preferably at least 80% by weight of constituent units derived from methacrylic acid ester. Each of the (meth) acrylic resins A and B may be a homopolymer of methacrylic acid ester, and may contain, based on the total monomer amount, at least 50% by weight of constitutional units derived from methacrylic acid ester and constitutional units derived from other polymerizable monomers By weight or less and 50% by weight or less.

As the methacrylic acid ester capable of forming the (meth) acrylic resins A and B, methacrylic acid alkyl ester can be used. Specific examples thereof include methyl methacrylate, ethyl methacrylate, methacrylic acid n Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, 2- Ethyl methacrylate alkyl ester having 1 to 8 carbon atoms in the alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 4. In the (meth) acrylic resins A and B, the methacrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.

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

Examples of the above other polymerizable monomer that can form the (meth) acrylic resins A and B include polymerizable monomers other than acrylic acid ester, methacrylic acid ester and acrylic acid ester. Specific examples of the acrylic acid ester include acrylic acid methyl ester, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2- Ethylhexyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, and the like. The number of carbon atoms in the alkyl group is preferably 1 to 4. In the (meth) acrylic resins A and B, the acrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.

Examples of the polymerizable monomer other than the methacrylate ester and the acrylate ester include monofunctional monomers having one polymerizable carbon-carbon double bond in the molecule and polyfunctional monomers having at least two polymerizable carbon- Although monomers can be mentioned, monofunctional monomers are preferably used. Specific examples of monofunctional monomers include styrene-based monomers such as styrene,? -Methylstyrene, vinyltoluene, and halogenated styrene; Alkenyl cyanide such as acrylonitrile and methacrylonitrile; Unsaturated acids such as acrylic acid, methacrylic acid and maleic anhydride; 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; Alkenyl esters of unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate and allyl cinnamic acid; Polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate and triallyl isocyanurate, and aromatic polyalkenyl compounds such as divinyl benzene. The polymerizable monomers other than the methacrylic acid ester and the acrylic acid ester may be used singly or in combination of two or more.

The preferable monomer composition of the (meth) acrylic resins A and B is 50 to 100% by weight of the methacrylic acid alkyl ester, 0 to 50% by weight of the alkyl acrylate, and the other polymerizable monomers More preferably 0 to 50% by weight, and more preferably 50 to 99.9% by weight of alkyl methacrylate, 0.1 to 50% by weight of alkyl acrylate, 0 to 49.9% by weight of other polymerizable monomers, Is 80 to 99.9% by weight of an alkyl methacrylate ester, 0.1 to 20% by weight of an alkyl acrylate ester, and 0 to 19.9% by weight of a polymerizable monomer other than these.

(Meth) acrylic resins A and B can be prepared by radical polymerization of the monomer composition containing the monomer as described above. The monomer composition may contain, if necessary, a solvent or a polymerization initiator. The glass transition temperatures T _gA and T _gB and the weight average molecular weights M _wA and M _wB of the (meth) acrylic resins A and B can be controlled by adjusting the types of monomers, the content ratios of the respective monomers, the polymerization conditions, have.

As a method for increasing the glass transition temperature of the (meth) acrylic resin, it is also effective to introduce a ring structure into the main chain of the polymer. In particular, the ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone structure. Specifically, a cyclic imide structure such as a cyclic acid anhydride structure such as an anhydroglutaric acid structure and an anhydrous succinic acid structure, a glutarimide structure and a succinimide structure, a lactone ring such as butyrolactone and valerolactone Structure. The larger the content of the ring structure in the main chain, the higher the glass transition temperature of the (meth) acrylic resin. The cyclic acid anhydride structure or the cyclic imide structure may be introduced by copolymerization of a monomer having a cyclic structure such as maleic anhydride or maleimide, a method of introducing a cyclic acid anhydride structure by a dehydration-demethanol condensation reaction after polymerization A method of introducing a cyclic imide structure by reacting an amino compound, and the like. The resin (polymer) having a lactone ring structure can be produced by preparing a polymer having a hydroxyl group and an ester group in a polymer chain, and then, by heating, the hydroxyl group and the ester group in the obtained polymer are reacted with a catalyst To form a lactone ring structure to form a lactone ring structure.

Examples of the polymer having a hydroxyl group and an ester group in the polymer chain include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) (Meth) acrylate having a hydroxyl group and an ester group such as n-butyl acrylate, n-butyl acrylate and t-butyl 2- (hydroxymethyl) acrylate as part of the monomer. A more specific method for preparing a polymer having a lactone ring structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-254726.

The (meth) acrylic resin composition of the present invention is a resin composition comprising (meth) acrylic resin A and (meth) acrylic resin B (a combination of (meth) acrylic resin A and (meth) acrylic resin B) But it is preferable to be one of the following modes in order to effectively obtain a desired effect (both improvement in toughness and improvement in heat resistance).

(A) a solid melt-kneaded product obtained by melt kneading the (meth) acrylic resin A and the (meth) acrylic resin B,

(B) a liquid melt-kneaded product obtained by melt kneading (meth) acrylic resin A and (meth) acrylic resin B,

[C] A mixture of a solid or liquid (meth) acrylic resin A and a solid or liquid (meth) acrylic resin B mixed.

The melt-kneaded product of [a] and [b] is typically a melt-kneaded product obtained by mixing and dispersing a (meth) acrylic resin A and a (meth) acrylic resin B microstatically. In the present invention, the melt-kneaded product may be in a solid state or in a liquid state. The melt-kneaded product of [a] may be a molded product obtained by molding into a desired shape, or may be a non-molded product. Examples of the shape of the molded article include granular, pellet, film and the like. The melt-kneaded product of the above-mentioned [b] is a liquid melt-kneaded product of a (meth) acrylic resin composition which is prepared by heating when molding with a film or the like.

The mixture of [c] may be, for example, a mixture of a solid (meth) acrylic resin A such as a granular or pellet type and a solid (meth) acrylic resin B such as a granular or pallet type, Can be 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 preferably 90/10 to 10/90, more preferably 80/20 to 20/90, More preferably 80/20 to 40/60, and still more preferably 80/20 to 40/60. By adjusting the content ratio within this range, it is possible to effectively obtain a desired effect (both improvement in toughness and improvement in heat resistance). If the content of the (meth) acrylic resin A is excessively large, the toughness of the obtained (meth) acrylic resin film tends to become insufficient. On the other hand, if the content of the (meth) acrylic resin B is excessively large, the heat shrinkage ratio of the resulting (meth) acrylic resin film tends to become large.

The (meth) acrylic resin composition of the present invention may contain one or two additives such as a lubricant, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, an antioxidant, It may contain more than two species.

When a lubricant is added, the (meth) acrylic resin film composed of the (meth) acrylic resin composition can be prevented from being wound in the form of a roll, thereby improving defects in the wound state. The lubricant may be any one having a function of improving the sliding property of the surface of the (meth) acrylic resin film, and examples thereof include a stearic acid compound, a (meth) acrylic compound and an ester compound. Among them, a stearic acid-based compound is preferably used as a lubricant.

Examples of the stearic acid-based compound which is a lubricant include, in addition to stearic acid itself, stearic acid esters such as methyl stearate, ethyl stearate and monoglyceride stearate; Stearic acid amide; Stearic acid metal salts such as sodium stearate, calcium stearate, zinc stearate, lithium stearate, and magnesium stearate; Hydroxystearic acid, sodium 12-hydroxystearate, zinc 12-hydroxystearate, calcium 12-hydroxystearate, lithium 12-hydroxystearate, magnesium 12- Hydroxystearic acid and metal salts thereof. Among them, stearic acid is preferably used.

The blending amount of the lubricant is 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 the total 100 parts by weight of the (meth) acrylic resins A and B. If the amount of the lubricant is too large, the lubricant may bleed out from the (meth) acrylic resin film, or the transparency of the film may be deteriorated.

The ultraviolet absorber is a compound which absorbs ultraviolet rays having a wavelength of 400 nm or less. (Meth) acrylic resin composition is used as a protective film of a polarizing film, the ultraviolet absorber is added to the (meth) acrylic resin composition to improve the durability of the polarizing plate to which the protective film is bonded to the polarizing film Can be improved. That is, by containing the ultraviolet absorber in the (meth) acrylic resin film, the ultraviolet rays can be efficiently blocked without deteriorating the color tone of the polarizing plate using the film as the protective film, and the polarization degree during the long-term use of the polarizing plate can be suppressed .

As the ultraviolet absorber, known ultraviolet absorbers such as benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and acrylonitrile-based ultraviolet absorbers can be used.

Specific examples of the ultraviolet absorber include: 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol- Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-t-butyl-6- (5-chlorobenzotriazol- Phenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone. Among them, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] is one of preferable ultraviolet absorbers.

The blending amount of the ultraviolet absorber is preferably 10% or less, more preferably 5% or less, at the wavelength of 370 nm or less of the (meth) acrylic resin film composed of the (meth) acrylic resin composition, 2% or less. It is also preferable to blend an ultraviolet absorber so that the light transmittance of the (meth) acrylic resin film at a wavelength of 380 nm is 25% or less, more preferably 15% or less, particularly 7% or less. The blending amount of the ultraviolet absorber is appropriately adjusted so that the light transmittance of the (meth) acrylic resin film satisfies the conditions shown here.

The infrared absorbing agent is a compound that absorbs infrared rays having a wavelength of 800 nm or more, and examples thereof include nitroso compounds or metal complex salts thereof, cyanine compounds, squarylium compounds, thiol nickel complex compounds, phthalocyanine compounds, naphthalocyanine compounds, Based compounds, triarylmethane-based compounds, imonium-based compounds, diimmonium-based compounds, naphthoquinone-based compounds, anthraquinone-based compounds, amino compounds, aminium-based compounds, carbon black, indium tin oxide, antimony tin oxide, Group 4A of the periodic table, Oxide, carbide, or boride of a metal belonging to Group 6A or Group 6A. These infrared absorbing agents are preferably selected so as to be able to absorb infrared rays (light having a wavelength in the range of about 800 to about 1100 nm), and two or more kinds of infrared absorbing agents may be used in combination. The blending amount of the infrared absorber is preferably selected so that the light transmittance at a wavelength of 800 nm or more of the (meth) acrylic resin film made of, for example, the (meth) acrylic resin composition is 10% or less.

The timing of adding the additive to the (meth) acrylic resin composition is not particularly limited. For example, when the (meth) acrylic resin composition of the present invention is formed into a film of a (meth) acrylic resin film by forming a film of the (meth) acrylic resin composition, , An additive may be added to such a solid melt-kneaded product or mixture, and thereafter melt-kneaded and formed by melt extrusion or the like. Alternatively, the additives may be blended in advance at the time of preparing the melt-kneaded product of the form [a] or the mixture of the form [c]. When the (meth) acrylic resin composition is in the form of [b], the additive may be added to the melt-kneaded product in a liquid phase, and then the mixture may be formed 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 made of the (meth) acrylic resin composition of the present invention. Since the (meth) acrylic resin film of the present invention contains the (meth) acrylic resin composition of the present invention, it is excellent in toughness, and therefore has good handleability (bending property), low heat shrinkage, Do. The (meth) acrylic resin film can be obtained by forming the above-mentioned (meth) acrylic resin composition of the present invention by a general film-forming method. Among them, the melt extrusion film forming method is preferably adopted.

The melt extrusion film-forming method generally refers to a method in which a thermoplastic resin is put into an extruder to melt it, and a film-like molten resin is extruded from a T die, and is directly pulled on a cooling roll and cooled and solidified to obtain a continuous long film. The thickness of the film can be determined by appropriately controlling the rib spacing and the like of the T die. The thickness of the (meth) acrylic resin film is usually 200 占 퐉 or less, preferably 40 to 150 占 퐉.

The (meth) acrylic resin film may be a single layer film or a multilayer film of two or more layers. In order to obtain a multilayer film, a co-extrusion method is generally adopted in which a plurality of extruders are provided in the above-mentioned melt extrusion forming method and the molten resin passed through each extruder is extruded so as to become a multilayer in the T die. As another method for forming the multilayered film, there are a method in which a plurality of extruders and T-dies are successively arranged and the extruded film-like molten resin is superimposed to form a multilayered film; a method in which a film- A method of forming a multi-layered film by pressing a plurality of film-formed single-layer films, and the like.

When the (meth) acrylic resin film is a multilayer film, each layer may be formed of a (meth) acrylic resin composition having the same composition or a (meth) acrylic resin composition having a different composition. For example, the composition of the additives may be changed for each layer, such as a lamination structure of a layer containing an ultraviolet absorber and a layer not containing an ultraviolet absorber.

The center line average roughness of at least one surface of the (meth) acrylic resin film is preferably about 0.01 to 0.05 mu m. When a (meth) acrylic resin film is used as a protective film of a polarizing film, it is preferable that the surface having a center line average roughness of about 0.01 to 0.05 mu m is a bonding surface to a polarizing film. The center line average roughness is a value measured according to the method specified in JIS B 0601.

If the center line average roughness of the surface of the (meth) acrylic resin film is less than 0.01 탆, the film tends to cause blocking between the films when the film itself is formed into a roll shape, and the film is broken due to adhesion between the films when drawn. There is a case that the sex is lowered. When the centerline average roughness of the surface of the (meth) acrylic resin film is more than 0.05 mu m, sufficient adhesion may not be obtained when the surface of the (meth) acrylic resin film is laminated on the polarizing film by using an adhesive. Scattering of the reflected light due to the scattering of the reflected light becomes large, and in the liquid crystal display device using the obtained polarizing plate, the screen may be whitened or the contrast may be deteriorated.

The method of controlling the surface roughness of the center line of the (meth) acrylic resin film within the above range is not particularly limited, but in the melt extrusion film forming method, the surface of the cooling roll is transferred to the surface of the film contacting the surface, A method using a cooling roll having roughness is adopted.

The (meth) acrylic resin film may contain a solvent remaining in the (meth) acrylic resin A and / or B, or a solvent derived from a solvent added to the (meth) acrylic resin composition if necessary, The amount of the residual solvent contained in the (meth) acrylic resin film 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 loss value when the (meth) acrylic resin film is heated at 200 占 폚 for 30 minutes or as a gas chromatographic quantitative value of the gas amount generated by the heating.

When the amount of the residual solvent is 0.01 wt% or less, deformation of the protective film can be prevented even when the polarizing plate using, for example, a (meth) acrylic resin film as a protective film of a polarizing film is exposed under a high temperature and high humidity environment, Deterioration of the optical performance of the film and the polarizing plate can be prevented.

The (meth) acrylic resin film having a residual solvent amount of 0.01% by weight or less can be produced, for example, in an extruder which can be used for preparing a (meth) acrylic resin composition or a vent hole is formed in an appropriate part of an extruder And the pressure inside the extruder is reduced from the hole.

The (meth) acrylic resin film of the present invention may have a surface treatment layer laminated on the film. By imparting the surface treatment layer to the (meth) acrylic resin film, a specific function according to the kind of the surface treatment layer can be given. Examples of the surface treatment layer include, for example,

[A] Hard coat layer for preventing surface scratches,

[B] Antistatic layer,

[C] antireflection layer,

[D] Antifouling layer,

[E] an antiglare layer which improves the visibility, prevents external light from appearing on the image, reduces the light and light caused by the interference of the prism sheet and the color filter,

to be.

(Hard coat layer)

The hard coating layer has a function of increasing the surface hardness of the (meth) acrylic resin film and is formed for the purpose of preventing scratches on the surface. The hard coat layer is subjected to a pencil hardness test (having a hard coat layer) specified in JIS K 5600-5-4: 1999 " Paint General Test Methods- Part 5: Mechanical Properties of Coating Film- Section 4: Scratch Hardness The optical film is measured on a glass plate), it is preferable to show H or a harder value thereof.

The material for forming the hard coat layer is generally cured by heat or light. For example, organic hard coating materials such as organic silicon-based, melamine-based, epoxy-based, acrylic, and urethane acrylate-based materials and inorganic hard coating materials such as silicon dioxide can be cited. Of these, a urethane acrylate-based or polyfunctional acrylate-based hard coating material is preferably used because it has good adhesion to the (meth) acrylic resin film and excellent productivity.

The hard coat layer may contain various fillers for the purpose of adjusting the refractive index, improving the bending elastic modulus, stabilizing the volume shrinkage ratio, and further improving the heat resistance, antistatic property, light resistance, and the like. The hard coat layer may also contain additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent.

(Antistatic layer)

The antistatic layer is formed for the purpose of imparting conductivity to the surface of the (meth) acrylic resin film and suppressing the influence of static electricity. For forming the antistatic layer, for example, a method of applying a resin composition containing a conductive material (antistatic agent) onto a (meth) acrylic resin film can be adopted. For example, an antistatic hard coat layer can be formed by allowing an antistatic agent to coexist in the hard coat material used for forming the hard coat layer.

(Antireflection layer)

The antireflection layer is a layer for preventing reflection of external light and is formed directly on the surface of the (meth) acrylic resin film or through another layer such as a hard coat layer. The (meth) acrylic resin film having an antireflection layer preferably has a reflectance of 2% or less at an incident angle of 5 DEG with respect to light having a wavelength of 430 to 700 nm, and preferably has a reflectance at the same incident angle with respect to light having a wavelength of 550 nm of 1% Or less.

The thickness of the antireflection layer may be about 0.01 to 1 占 퐉, but is preferably 0.02 to 0.5 占 퐉. The antireflection layer is preferably made of a low refractive index layer having a refractive index smaller than that of the layer in which it is formed (the (meth) acrylic resin film or the hard coating layer), specifically a refractive index of 1.30 to 1.45, A plurality of thin film high refractive index layers made of a refractive index layer and an inorganic compound alternately stacked on one another, or the like.

The material for forming the low refractive index layer is not particularly limited as long as the refractive index is small. For example, a resin material such as an ultraviolet curable (meth) acrylic resin; A hybrid material in which inorganic fine particles such as colloidal silica are dispersed in a resin; A sol-gel material containing an alkoxysilane, and the like. Such a low refractive index layer may be formed by applying a polymerized polymer, or may be formed by applying the monomer in the form of a monomer or oligomer, which is a precursor, and then polymerizing and curing it. Further, each of the materials preferably contains a compound having a fluorine atom in the molecule in order to impart antifouling property.

As the sol-gel material for forming the low refractive index layer, those having fluorine atoms in the molecule are preferably used. A typical example of a sol-gel material having fluorine atoms in the molecule is polyfluoroalkylalkoxysilane. The polyfluoroalkylalkoxysilane is, for example,

CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃

, Wherein R represents an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 0 to 12. Among them, a compound in which n is 2 to 6 in the above formula is preferable.

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-tridecafluorooctyltriethoxysilane,

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl trimethoxysilane,

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl triethoxysilane and the like.

The low refractive index layer may be composed of a cured product of a thermosetting fluorine compound or an active energy ray curable fluorine compound. The cured product preferably has a coefficient of dynamic friction within a range of 0.03 to 0.15, and preferably has a contact angle to water in a range of 90 to 120 °. As the curable fluorine compound, a polyfluoroalkyl group-containing silane compound (for example, 3,3,4,4,5,5,6,6,6,7,7,8,8,9,9,10,10,10 -Heptadecafluorodecyltriethoxysilane, etc.), and fluorine-containing polymers having a crosslinkable functional group.

The fluorine-containing polymer having a crosslinkable functional group can be prepared by copolymerizing 1) a monomer containing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or 2) a method of copolymerizing a monomer having a functional group with a fluorine-containing monomer, And then adding a compound having a functional group.

Examples of the fluorine-containing monomer include fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, and perfluoro-2,2-dimethyl-1,3-dioxol ; Partially or completely fluorinated alkyl ester derivatives of (meth) acrylic acid; (Meth) acrylic acid, and partially or fully fluorinated vinyl ethers of (meth) acrylic acid.

Examples of the monomer having a crosslinkable functional group or the compound having a crosslinkable functional group include monomers having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; Monomers having a carboxyl group such as acrylic acid or methacrylic acid; Monomers having a hydroxyl group such as hydroxyalkyl acrylate and hydroxyalkyl methacrylate; Monomers having an alkenyl group such as allyl acrylate or allyl methacrylate; Monomers having an amino group; Sulfonic acid group-containing monomers.

The material for forming the low refractive index layer may be composed of a sol in which inorganic compound fine particles such as silica, alumina, titania, zirconia, and magnesium fluoride are dispersed in an alcohol solvent from the viewpoint of improving scratch resistance It is possible. Therefore, the inorganic compound fine particles to be used preferably have a smaller refractive index from the viewpoint of antireflection property. The inorganic fine particles may have voids, and hollow fine particles of silica are particularly preferable. The average particle diameter of the hollow fine particles is preferably in the range of 5 to 2000 nm, more preferably 20 to 100 nm. The average particle diameter referred to herein is the number average particle diameter determined by transmission electron microscope observation.

(Stratum corneum)

The antifouling layer is formed to impart water repellency, oil repellency, cold resistance, antifouling property and the like. A preferred material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, and polymer compounds thereof. The method of forming the antifouling layer may be physical vapor deposition, chemical vapor deposition, wet coating or the like, in which vapor deposition and sputtering are typical examples, depending on the material to be formed. The average thickness of the antifouling layer is usually about 1 to 50 nm, preferably 3 to 35 nm.

(Antiglare layer)

The antiglare layer is a layer having a fine concavo-convex shape on its surface, and is preferably formed using the hard coating material described above.

The antiglare layer having a fine concavo-convex shape on its surface can be obtained by (1) forming a coating film containing fine particles on a (meth) acrylic resin film and forming concavo-convex based on the fine particles, (2) (Such as an embossing method) in which a coating film which is not formed on a (meth) acrylic resin film is pressed on a metal mold (roll or the like) .

In the method (1), a curable resin composition containing a curable transparent resin and fine particles is applied on a (meth) acrylic resin film, and the coating layer is cured by irradiation with light such as ultraviolet rays or heating to form an antiglare layer . The curable transparent resin is preferably selected from a material having a high hardness (hard coat). As such a curable transparent resin, a photo-curable resin such as an ultraviolet curable resin, a thermosetting resin, an electron beam curable resin or the like can be used. From the viewpoints of productivity and hardness of the obtained antiglare layer, a photo-curable resin is preferably used, Is an ultraviolet curing resin. When a photocurable resin is used, the curable resin composition further includes a photopolymerization initiator.

As the photo-curable resin, polyfunctional (meth) acrylate is generally used. Specific examples thereof include di- or tri (meth) acrylates of trimethylolpropane; Tri- or tetra- (meth) acrylates of pentaerythritol; (Meth) acrylate which is the reaction product of (meth) acrylate and diisocyanate having at least one hydroxyl group in the molecule. These multifunctional (meth) acrylates can be used singly or in combination of two or more as necessary.

Also, a mixture of a multifunctional urethane (meth) acrylate, a polyol (meth) acrylate, and a (meth) acrylic polymer having an alkyl group containing two or more hydroxyl groups may be used as a photocurable resin. The multifunctional urethane (meth) acrylate constituting the photo-curable resin is prepared by using, for example, (meth) acrylic acid and / or a (meth) acrylic acid ester, a polyol and a diisocyanate. Specifically, a hydroxy (meth) acrylate having at least one hydroxyl group in a molecule is prepared from (meth) acrylic acid and / or a (meth) acrylate ester and a polyol, and reacted with a diisocyanate to obtain a polyfunctional urethane ) Acrylate can be produced. The multifunctional urethane (meth) acrylate thus produced is also the photocurable resin itself which has been previously described. In the production thereof, the (meth) acrylic acid and / or the (meth) acrylic acid ester may be used either singly or in combination of two or more, and the polyol and the diisocyanate may be used in the same manner Or two or more of them may be used in combination.

The (meth) acrylic acid ester which is one raw material of the polyfunctional urethane (meth) acrylate may be a chain type or a cyclic alkyl ester of (meth) acrylic acid. Specific examples thereof include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl And cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate.

The polyol which is another raw material of the polyfunctional urethane (meth) acrylate is a compound having at least two hydroxyl groups in the molecule. Examples thereof include aliphatic diols such as ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, Nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol esters of hydroxypivalic acid, cyclohexanedimethyl Ethylene oxide adduct bisphenol A, propylene oxide adduct bisphenol A, trimethylol ethane, trimethylol propane, glycerin, 3-methylpentane, 1-methylpentane 1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, glucose and the like.

The diisocyanate which is another raw material of the polyfunctional urethane (meth) acrylate is a compound having two isocyanate groups (-NCO) in the molecule, and various aromatic, aliphatic or alicyclic diisocyanates can be used. Specific examples include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3 ' -Dimethyl-4,4'-diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and a nuclear hydrogen addition product of a diisocyanate having an aromatic ring therebetween have.

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

The (meth) acrylic polymer having an alkyl group containing two or more hydroxyl groups, which constitutes a photocurable resin together with these polyfunctional urethane (meth) acrylates and polyol (meth) acrylates, Having two or more alkyl groups. For example, a polymer containing 2,3-dihydroxypropyl (meth) acrylate as a constitutional unit or a polymer containing 2,3-dihydroxypropyl (meth) acrylate and 2-hydroxyethyl (meth) As a constituent unit, and the like.

By using the (meth) acrylic photopolymerizable resin as described above, it is possible to obtain an antiglare film which can improve the adhesion with the (meth) acrylic resin film, improve the mechanical strength, and effectively prevent the scratch on the surface .

It is preferable that the fine particles have an average particle diameter of 0.5 to 5 占 퐉 and a difference in refractive index from the curable transparent resin after curing is 0.02 to 0.2. By using fine particles having an average particle diameter and a refractive index difference within this range, it is possible to effectively develop haze. The average particle diameter of the fine particles can be obtained by a dynamic light scattering method or the like. In this case, the average particle diameter becomes the weight average particle diameter.

The fine particles may be organic fine particles or inorganic fine particles. As the organic fine particles, resin particles are generally used, and examples thereof include crosslinked poly (meth) acrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, And the like. As the inorganic fine particles, silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate and the like can be used.

As the photopolymerization initiator, various types such as acetophenone, benzophenone, benzoin ether, amine, and phosphine oxide can be used. Examples of compounds classified as acetophenone-based photopolymerization initiators are 2,2-dimethoxy-2-phenylacetophenone (aka benzyldimethylketal), 2,2-diethoxyacetophenone, 1- (4- 2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone and 2-methyl-2-morpholino-1- (4-methylthiophenyl) do. Examples of compounds classified as benzophenone-based photopolymerization initiators include benzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone. Examples of compounds classified as benzoin ether photopolymerization initiators include benzoin methyl ether, benzoin propyl ether. Examples of compounds classified as amine-based photopolymerization initiators include N, N, N ', N'-tetramethyl-4,4'-diaminobenzophenone (alias Michler ketone). Examples of the phosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide. In addition, xanton-based compounds and thioxanthone-based compounds can also be used as photopolymerization initiators.

These photopolymerization initiators are commercially available. Examples of representative commercial products include "Irgacure 907", "Irgacure 184", and "Lucillin TPO" sold by BASF, Germany.

The curable resin composition may contain a solvent as required. As the solvent, any organic solvent capable of dissolving each component constituting the curable resin composition such as ethyl acetate or butyl acetate can be used. Two or more kinds of organic solvents may be mixed and used.

The curable resin composition may contain a leveling agent, for example, a fluorine-based or silicone-based leveling agent may be used. Silicone leveling agents include reactive silicones, polydimethylsiloxanes, polyether-modified polydimethylsiloxanes, and polymethylalkylsiloxanes. Among silicone leveling agents, preferred are leveling agents based on reactive silicones and siloxanes. When a leveling agent made of reactive silicon is used, sliding property is imparted to the surface of the antiglare layer, and excellent scratch resistance can be maintained for a long period of time. Further, if a siloxane leveling agent is used, film formability can be improved.

On the other hand, in the case of forming an antiglare layer having a fine surface concavo-convex shape by the method (embossing method) described in 2) above, a mold having fine concavo-convex shapes is used and the shape of the mold is placed on a (meth) And then transferred to the formed resin layer. In the case of forming the fine surface concave-convex shape by the emboss method, the resin layer onto which the convexo-concave shape is transferred may or may not contain fine particles. The resin constituting the resin layer is preferably a photo-curing resin as exemplified in the above-mentioned method 1), more preferably an ultraviolet-curable resin. However, by appropriately selecting a photopolymerization initiator instead of the ultraviolet ray-curable resin, a visible light curable resin which can be cured to visible light having a longer wavelength than ultraviolet ray can be used.

In the emboss method, a curable resin composition containing a photo-curing resin such as an ultraviolet ray-curable resin is applied on a (meth) acrylic resin film, and the coating layer is cured while pressing on the uneven surface of the mold, Layer. More specifically, the curable resin composition is coated on a (meth) acrylic resin film, and light such as ultraviolet rays is irradiated from the (meth) acrylic resin film side in a state in which the coating layer is in contact with the uneven surface of the mold, And then the (meth) acrylic resin film having the coating layer (antiglare layer) after curing is peeled from the mold to transfer the concave-convex shape of the mold to the antiglare layer.

The thickness of the antiglare layer is not particularly limited, but is generally 2 to 30 μm, preferably 3 μm or more, and more preferably 20 μm or less. If the antiglare layer is too thin, a sufficient hardness can not be obtained and the surface tends to be scratched. On the other hand, if the antiglare layer is too thick, it tends to be easily broken or the curling of the film due to curing shrinkage of the antiglare layer tends to lower productivity.

The haze value of the (meth) acrylic resin film having the antiglare layer is preferably in the range of 5 to 50%. When the haze value is too small, sufficient antiglare performance can not be obtained, and when a polarizing plate having a (meth) acrylic resin film with an antiglare layer is applied to an image display apparatus, the visibility of the external light is likely to occur on the screen. On the other hand, if the haze value is too large, the visibility of the external light can be reduced, but the sharpness of the screen of black display is lowered. The haze value is a ratio of the diffusion transmittance to the total light transmittance, and is measured in accordance with JIS K 7136: 2000 " Method for determining haze of plastic-transparent material ".

<Stretched film>

The stretched film of the present invention is a film obtained by stretching the (meth) acrylic resin film of the present invention. Since the stretched film of the present invention also contains the (meth) acrylic resin composition of the present invention, it is excellent in toughness, and therefore has good handleability (bending property), low heat shrinkage and excellent heat resistance.

Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include a machine direction MD of the unstretched film, a direction perpendicular to the MD, and a direction crossing obliquely to the machine direction MD. The biaxial stretching may be simultaneous biaxial stretching in which two stretching directions are simultaneously performed, or may be sequential biaxial stretching after stretching in a predetermined direction and then stretching in other directions.

The stretching treatment may be carried out by stretching in the machine direction (machine direction: MD) using two or more pairs of nip rolls having a larger peripheral speed on the exit side, holding both ends of the unstretched film with a chuck, (TD) orthogonal to the direction of the film.

The stretching magnification by the stretching treatment is preferably more than 0 to 500%, more preferably 100 to 300%. When the draw ratio exceeds 300%, the film thickness becomes too thin to be easily broken or the handling property is deteriorated. The stretching magnification was calculated by the following formula:

(%) = 100 x (length after stretching) - (length before stretching)} / (length before stretching)

.

The stretching temperature is set to a temperature higher than the temperature at which the entirety of the (meth) acrylic resin film exhibits fluidity to such an extent that it can be stretched, and is preferably within the range of -40 ° C to + 40 ° C of the glass transition temperature of the (meth) More preferably in the range of -25 ° C to + 25 ° C, and more preferably in the range of -15 ° C to + 15 ° C.

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

<Polarizer>

The polarizing plate of the present invention comprises a polarizing film, the (meth) acrylic resin film of the present invention laminated on at least one side of the polarizing film, or the stretched film of the present invention. The (meth) acrylic resin film and the stretched film may be a protective film for protecting the polarizing film. In the polarizing plate of the present invention, the (meth) acrylic resin film or the stretched film according to the present invention may be laminated on both sides of the polarizing film, and the (meth) acrylic resin film or the stretched film And another transparent resin film which is a protective film or a retardation film may be laminated on the other side. These (meth) acrylic resin films, stretched films, transparent resin films and polarizing films can be bonded together using an adhesive.

(Polarizing film)

The polarizing film can be produced by a known method such as a process of uniaxially stretching a polyvinyl alcohol resin film, a process of adsorbing the dichroic dye by staining the polyvinyl alcohol resin film with a dichroic dye, a process of adsorbing the dichroic dye A process of treating a polyvinyl alcohol resin film with an aqueous solution of boric acid and a process of washing with water after treatment with an aqueous solution of boric acid. The thus obtained polarizing film has an absorption axis in the uniaxially stretched direction.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include (meth) acrylamides having unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and ammonium groups.

The degree of saponification of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1000 to 10000, preferably about 1500 to 5000.

Such a polyvinyl alcohol resin film is used as the original film of the polarizing film. The method of forming the polyvinyl alcohol resin is not particularly limited, and a known method is adopted. The film thickness of the polyvinyl alcohol original film is not particularly limited, but is, for example, about 10 to 150 mu m.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with the dichroic dye, after dyeing, or after dyeing. In the case of uniaxial stretching after dyeing, the uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed in such a plurality of steps.

The uniaxial stretching may be performed by passing between spaced apart rolls having different main speeds, or may be carried out by sandwiching the rolls between the rolls. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which a polyvinyl alcohol resin film is stretched by using a solvent such as water or an organic solvent. The stretching magnification is usually about 3 to 8 times.

The dyeing of the polyvinyl alcohol resin film by the dichroic dye can be performed by, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, iodine or a dichroic organic dye is used. It is preferable that the polyvinyl alcohol resin film is immersed in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. 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 normally about 20 to 40 캜. The immersion time (dyeing time) for this 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 of dying and dyeing the polyvinyl alcohol resin film into an aqueous solution containing a water-soluble dichroic organic dye is generally adopted. The content of the dichroic organic dye in this aqueous solution is usually about 1 x ^10-4 to 10 parts by weight, preferably about 1 x ^{10-3 to} 1 part by weight, per 100 parts by weight of water. The 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 캜. The immersion time (dyeing time) for this aqueous solution is usually about 10 to 1800 seconds.

The boric acid treatment after dyeing with a dichroic dye can be carried out by dipping the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid. The content of boric acid in the aqueous solution containing boric acid is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution containing boric acid contains potassium iodide. The content of potassium iodide in the aqueous solution containing boric acid 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 for the boric acid-containing aqueous solution is usually about 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 占 폚 or higher, preferably 50 to 85 占 폚, and more preferably 60 to 80 占 폚.

The polyvinyl alcohol resin film after boric acid treatment is usually subjected to water washing treatment. The water washing treatment is carried out, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 캜. The immersion time is usually about 1 to 120 seconds.

After washing with water, drying treatment is carried out to obtain a polarizing film. The drying treatment can be performed using a hot-air dryer or a far-infrared heater. The temperature of the drying treatment is usually about 30 to 100 占 폚, preferably 50 to 80 占 폚. The time for the drying treatment is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

By the drying treatment, the water content of the polarizing film is reduced to a practically acceptable level. The water content thereof is usually 5 to 20% by weight, preferably 8 to 15% by weight. If the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. On the other hand, when the moisture content exceeds 20% by weight, the thermal stability of the polarizing film tends to become insufficient.

The thickness of the polarizing film in which the dichroic dye thus obtained is adsorbed and oriented can be usually about 5 to 40 mu m.

(Transparent resin film)

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

The transparent resin film may be, for example, a triacetylcellulose film, a polycarbonate film, a polyethylene terephthalate film, a (meth) acrylic resin film, a laminate film of a (meth) acrylic resin layer and a polycarbonate resin layer, . Of these, an olefin-based resin film is preferably used.

The olefinic resin is a resin obtained by polymerizing a cyclic olefin monomer such as a chain olefin monomer such as ethylene or propylene, or a cyclic olefin monomer such as norbornene or another cyclopentadiene derivative with a polymerization catalyst.

Examples of the olefin-based resin obtained from the chain olefin monomer include a polyethylene-based resin and a polypropylene-based resin. Among them, a propylene-based resin which is a homopolymer of propylene is preferable. Also preferred is a polypropylene-based copolymer resin obtained by copolymerizing propylene with a comonomer copolymerizable therewith at a ratio of usually 1 to 20% by weight, preferably 3 to 10% by weight.

The comonomer copolymerizable with propylene is preferably ethylene, 1-butene or 1-hexene. Of these, ethylene is preferably used because transparency and stretchability are relatively good, and a polypropylene copolymer resin obtained by copolymerizing ethylene in a proportion of 1 to 20% by weight, particularly 3 to 10% by weight, is one of preferred. When the copolymerization ratio of ethylene is 1% by weight or more, transparency and stretchability are improved. On the other hand, if the proportion exceeds 20% by weight, the melting point of the resin is lowered, and the heat resistance required for the protective film or the retardation film may be impaired.

The polypropylene resin is commercially available, for example, "Prime Polypro" sold by Prime Polymer Co., Ltd., "Novatec" and "Wintech" sold by Japan Polypro Corporation, &Quot; Sumitomonobrene &quot; sold by Sumitomo Chemical Co., Ltd., and &quot; Sundaromer &quot; sold by Sundarom Corporation.

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

As the cyclic olefin resin, ring-opening metathesis polymerization is carried out using, for example, norbornene or a derivative thereof obtained by a Diels-Alder reaction from cyclopentadiene and olefins as monomers, and a resin obtained by subsequent hydrogenation ; Ring-opening metathesis polymerization is carried out by using dicyclopentadiene, tetracyclododecene or its derivative obtained by the Diels-Alder reaction from an olefin or a (meth) acrylate ester as a monomer, followed by hydrogenating the resulting resin ; Norbornene, tetracyclododecene, derivatives thereof, or other cyclic olefin monomers, followed by ring-opening metathesis copolymerization, followed by hydrogenation; And resins obtained by addition copolymerization of at least one cyclic olefin selected from norbornene, tetracyclododecene and derivatives thereof and an aliphatic or aromatic compound having a vinyl group.

For example, "TOPAS" (Topaz), which is produced by TOPAS ADVANCED POLYMERS GmbH of Germany and sold by Polyplastics Co., Ltd., Japan, and JSR Co., Ltd., "Arton" which is manufactured and sold, "Zeonoa" and "Zeonex" manufactured and sold by Nippon Zeon Co., Ltd. and "Arpel" manufactured and sold by Mitsui Chemicals, Inc., and the like.

The film of the chain olefin resin or the cyclic olefin resin is formed into a film to make a transparent resin film to be bonded to one side of the polarizing film. The method of film formation is not particularly limited, but a melt extrusion film forming method is preferably adopted.

Olefin resin films can also be easily obtained commercially. For example, in the case of a polypropylene type resin film, "FILMAX CPP film" sold by FILMAX under the trade name of "SUNTOX" sold by Sun Toms Co., Toyobo Pylen Film sold by Toyo Boseki Co., Ltd., Toraypan sold by Torei Film Processing Co., Ltd., and Japan Poly Ace Co., Ltd. "Nippon Polyes", and "Tyco FC" sold by Futamura Chemical Co., Ltd., and the like. Examples of the cyclic olefin based resin film include "Zeonoa Film" sold under the trade name of Nippon Zeon Co., Ltd. and "Aton Film" sold by JSR Corporation.

The transparent resin film may be laminated with an optical functional film on its surface or coated with an optical functional layer. Examples of the optically functional film and the optical functional layer include an adhesive layer, a conductive layer, and a hard coating layer.

By stretching the above-described olefin-based resin film and imparting refractive index anisotropy to the film, the function of the retardation film can be imparted. The stretching method may be appropriately selected according to the refractive index anisotropy required, and is not particularly limited. For example, all-axis stretching, transverse uniaxial stretching, or longitudinal and transverse biaxial stretching are adopted.

Since an olefin resin has a positive refractive index anisotropy and a refractive index becomes largest in a direction in which stress is applied, a film uniaxially stretched gives a refractive index anisotropy of usually n _x > n _y ≒ n _z . Herein, n _x is the refractive index in the in-plane slow axis direction of the film (in the direction in which the refractive index is maximum in the plane, and in the stretching direction in the resin having the positive refractive index anisotropy), and n _y is the in-plane fast axis direction Axis), and n _z is the refractive index in the normal direction of the film. The olefin-based resin film is a sequential biaxial stretching, it gives a refractive index anisotropy of the normal _{n x> n y> n z} .

Further, in order to impart a desired refractive index characteristic, the retardation film may be produced by bonding a heat-shrinkable film to a target film and shrinking the film together with the stretching process instead of the stretching process. This operation is usually carried out to obtain a retardation film whose refractive index anisotropy is n _x > n _z > n _y or n _z > n _x ≥n _y .

A retardation film made of an olefin-based resin can also be commercially available. For example, in the case of a phase difference film made of a cyclic olefin-based resin, "Zeonoa Film" marketed by Nippon Zeon Co., Ltd., "Aton film" marketed by JSR Corporation, marketed by Sekisui Chemical Co., And &quot; Escherichia phase difference film &quot;.

(glue)

As described above, an adhesive is used for bonding the (meth) acrylic resin film or the stretched film to the polarizing film, or for bonding the polarizing film and the transparent resin film. Prior to the bonding, at least one of the bonding surface of the (meth) acrylic resin film or the stretched film with the polarizing film and the bonding surface of the polarizing film with the (meth) acrylic resin film or the stretched film, It is preferable that corona discharge treatment, plasma irradiation treatment, electron beam irradiation treatment, and other surface activation treatment are carried out on at least one of the bonding surface with the resin film and the bonding surface with the polarizing film in the transparent resin film.

The adhesive used for bonding may be arbitrarily selected from those exhibiting adhesion to the film to be bonded. Typically, an aqueous adhesive, that is, an active energy ray-curable adhesive containing a component dissolved in water or an adhesive component dispersed in water, or a component cured by irradiation with an active energy ray can be given. From the viewpoint of productivity, an active energy ray-curable adhesive is preferably used.

First, with respect to the water-based adhesive, for example, a composition using a polyvinyl alcohol resin or a urethane resin as a main component can be mentioned as a preferable adhesive.

When a polyvinyl alcohol resin is used as a main component of the water based adhesive, the polyvinyl alcohol resin may be a partially saponified polyvinyl alcohol or a completely saponified polyvinyl alcohol, a carboxyl group-modified polyvinyl alcohol, an acetoacetyl group-modified polyvinyl alcohol, Modified polyvinyl alcohol resins such as polyvinyl alcohol modified with an alkyl group, polyvinyl alcohol modified with an amino group, or the like. When a polyvinyl alcohol resin is used as an adhesive component, the adhesive is often prepared as an aqueous solution of a polyvinyl alcohol resin. The concentration of the polyvinyl alcohol resin in the aqueous adhesive solution is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of water.

In order to improve the adhesiveness, it is preferable to add a curing component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to an aqueous adhesive containing a polyvinyl alcohol resin as a main component. Examples of water-soluble epoxy resins include polyamides obtained by reacting epichlorohydrin with polyamide polyamines obtained by the reaction of polyalkylene polyamines such as diethylene triamine and triethylene tetramine with dicarboxylic acids such as adipic acid, Amide polyamine epoxy resins. Examples of commercially available products of such polyamide polyamine epoxy resins include "Sumirez Resin 650" and "Sumirez Resin 675" sold by Taoka Chemical Industry Co., Ltd. and "WS-525" sold by Japan PMC Co., And these can be preferably used. The addition amount of these curable components or crosslinking agent is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the polyvinyl alcohol resin. When the addition amount is small, the adhesive property improving effect is small. On the other hand, when the addition amount is large, the adhesive layer tends to become weak.

When a urethane resin is used as a main component of the water-based adhesive, a mixture of a polyester-based ionomer-type urethane resin and a compound having a glycidyloxy group can be mentioned as an example of a suitable adhesive composition. The polyester-based ionomer-type urethane resin referred to here is a urethane resin having a polyester skeleton in which a small amount of an ionic component (hydrophilic component) is introduced. The ionomeric urethane resin is preferable as an aqueous adhesive since it emulsifies directly by emulsification in water without using an emulsifier. The use of a polyester-based ionomer-type urethane resin for bonding a polarizing film and a protective film is disclosed, for example, in JP-A-2005-70139, JP-A-2005-70140, JP-A-2005-181817 Lt; / RTI &gt;

On the other hand, when an activation energy ray-curable adhesive is used, a component (hereinafter sometimes simply referred to as a &quot; curable component &quot;) that is cured by irradiation of an active energy ray constituting the component is an epoxy compound, an octacene compound, Compounds and the like. When a cationic polymerizable compound such as an epoxy compound or an octacene compound is used, a cationic polymerization initiator is incorporated. When a radical polymerizable compound such as a (meth) acrylic compound is used, a radical polymerization initiator is blended. Among them, an adhesive that makes the epoxy compound one of the curable components is preferable, and an adhesive that makes the alicyclic epoxy compound having an epoxy group directly bonded to the saturated carbon ring as one of the curable components is preferable. It is also effective to use an oxetane compound in combination therewith.

Epoxy compounds are commercially available, for example, under the trade names of "Epicoat" series sold by Japan Epoxy Resin Co., Ltd., "Epiclon" series sold by DIC Co., Ltd., and sold by Toto Chemical Co., Ltd. "Adeka Resin" series sold by Adeka Corporation, "Dena Cole" series sold by Nagase Chemtex Co., Ltd., "Dow Epoxy" series sold by Dow Chemical Company, Nissan Chemical And "Tepic" sold by Kogyo Co., Ltd.

Alicyclic epoxy compounds in which an epoxy group is bonded directly to a saturated carbon ring can also be commercially available. Examples of the alicyclic epoxy compounds include &quot; Ceroxides &quot; series and &quot; Cyclomer series &quot;, which are commercially available from Daicel Chemical Industries, , And "Sulacure" series sold by Dow Chemical.

Oxetane compounds are also commercially available. Examples thereof include "Aron oxetane" series sold by Toagosei Co., Ltd. and "ETERNACOLL" series sold by Ube Industries, Ltd. under trade names.

Cationic polymerization initiation system. Commercially available products can be easily obtained. For example, "Kayarad" series sold by Nippon Kayaku Co., Ltd., "Siracure" series sold by Union Carbide Co., TAZ "," BBI "and" DTS "sold by Midori Kagaku Co., Ltd.," Adeka Optomer "series sold by ADEKA Co., Ltd., And "RHODORSIL" series which are sold in the market.

The active energy ray-curable adhesive may contain a photosensitizer if necessary. By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the adhesive layer can be further improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfates, redox compounds, azo and diazo compounds, anthracene compounds, halogen compounds, and photo-reducible pigments.

In addition, various additives can be added to the active energy ray-curable adhesive within a range that does not impair the adhesiveness thereof. Examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer and a defoaming agent. Further, a curing component which is cured by a reaction mechanism other than the cation polymerization may be added within a range not deteriorating the adhesiveness.

In the case of bonding a film using an active energy ray-curable adhesive, the film is bonded through a layer made of the adhesive, and then the active energy ray is irradiated to cure 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 be of the same composition or different compositions, but it is preferable to simultaneously irradiate active energy rays for curing both .

The active energy ray used for curing the active energy ray-curable adhesive may be, for example, an X-ray having a wavelength of 1 to 10 nm, an ultraviolet ray having a wavelength of 10 to 400 nm, a visible light having a wavelength of 400 to 800 nm, or the like. Among them, ultraviolet rays are preferably used from the viewpoints of ease of use and easiness of preparation of active energy ray-curable adhesive, stability and curing performance. Examples of the ultraviolet light source include low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps and metal halide lamps having a light emission distribution of 400 nm or less.

The thickness of the adhesive layer obtained by using the active energy ray-curable adhesive is usually about 1 to 50 mu m, but is preferably in the range of 1 to 10 mu m.

Since the (meth) acrylic resin film or the stretched film of the present invention is applied as the protective film to be bonded to the polarizing film of the present invention, the polarizing plate is not easily deformed or deteriorated in optical properties under high temperature environment, and is excellent in heat resistance.

The polarizing plate of the present invention can be preferably used as a polarizing plate constituting a liquid crystal panel used in a liquid crystal display, and is particularly preferable as a polarizing plate disposed on the viewer side of a liquid crystal cell. In the case where the polarizing plate of the present invention is disposed on the viewer side of the liquid crystal cell, the polarizing plate disposed on the back side of the liquid crystal cell may be a polarizing plate according to the present invention or another polarizing plate. The liquid crystal cell constituting the liquid crystal panel may be various ones used in this field.

The bonding of the polarizing plate to the liquid crystal cell can be performed through a pressure-sensitive adhesive layer previously formed on the surface of the polarizing plate. The pressure-sensitive adhesive layer can be laminated on one protective film of the polarizing plate. For example, a (meth) acrylic resin film or stretched film of the present invention is bonded to one side of a polarizing film, and another transparent resin film In the bonded polarizing plate, a pressure-sensitive adhesive layer can be formed on the outer surface of the transparent resin film. When the polarizing plate is bonded to the liquid crystal cell through the pressure-sensitive adhesive layer as a viewing side polarizing plate, a (meth) acrylic resin film or a stretched film is disposed on the viewer side.

The pressure-sensitive adhesive layer is generally formed of a (meth) acrylic pressure-sensitive adhesive containing a (meth) acrylic acid ester as a main component and a (meth) acrylic resin having a functional group-containing (meth) acrylic monomer as a pressure-sensitive adhesive component.

Yes

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "%" and "part" indicating the content or amount are based on weight unless otherwise specified.

In the following Examples and Comparative Examples, a resin (hereinafter referred to as &quot; resin A &quot;) was used as the (meth) acrylic resin A and the following [B1] or (Hereinafter, referred to as "resin B1" and "resin B2", respectively) were used.

[A] Al Kema (ARKEMA) use of methyl methacrylate-based resin is "Alts glass (ALTUGLAS) HT121" (glass transition temperature of the produced T _gA: 124 ℃, weight average molecular weight M _wA: 78200, number-average molecular weight M _nA: 41200, molecular weight distribution M _wA / M _nA : 1.9),

[B1] A methyl methacrylate resin having a glass transition temperature T _{gB of} 110 占 폚, a weight average molecular weight M _{wB of} 162000, a number average molecular weight M _{nB of} 84500, Molecular weight distribution M _wB / M _{n B} : 1.9),

[B2] methacrylate of methyl methacrylate-based resin containing a constituent unit of methylmethacrylate derived at least 80% by weight (glass transition temperature T _gB: 107 ℃, weight average molecular weight M _wB: 134000, a number average molecular weight M _nB: 67000, Molecular weight distribution M _wB / M _{n B} : 2.0).

&Lt; Example 1 >

A pallet type resin A and a pallet type resin B1 were charged into an extruder at a weight ratio of 75:25 to prepare a (meth) acrylic resin composition, which was melted and kneaded by heating to obtain a liquid melt-kneaded product. This melt-kneaded liquid mixed resin was continuously extruded from a T-die in a film form and solidified using a cooling roll to produce a long (meth) acrylic resin film (unmodified) having a thickness of 120 탆.

In addition, the unstretched product was subjected to a full-axis stretching treatment to produce a stretched film of 96 占 퐉 in thickness (new standing article). The drawing temperature was set to the glass transition temperature of the unstretched product (i.e., the above mixed resin) + 10 占 폚, and the draw ratio was 2.2 times.

Further, the unstretched product was subjected to the longitudinal stretching process and then subjected to the transverse stretching process to perform the sequential biaxial stretching process to produce a stretched film (longitudinally and transversely stretched product) having a thickness of 40 탆. The stretching temperature was set to a glass transition temperature of the unstretched product (i.e., the above mixed resin) + 10 ° C for both longitudinal stretching and transverse stretching, and the stretching magnifications for longitudinal stretching and transverse stretching were 2.2 times and 2.0 times, respectively.

&Lt; Examples 2 to 4 and Comparative Examples 1 to 4 >

(Meth) acrylic resin film (unmodified product) was produced in the same manner as in Example 1, except that the mixed resin (melt-kneaded product) or the single resin shown in Table 1 was used as the resin composition used in the production of the Film [unbreakable] was produced. In addition, by using the undrawn product, a longitudinally new product and / or a vertically and horizontally elongated product were produced in the same manner as in Example 1. In addition, in Comparative Example 2, as the rubber particles blended in the resin A, the innermost layer was composed of a hard polymer polymerized using methyl methacrylate and a small amount of allyl methacrylate, and the intermediate layer was composed of butyl acrylate as the main component , And a soft elastic polymer polymerized by using styrene and a small amount of allyl methacrylate, and the outermost layer has a three-layer structure composed of a hard polymer polymerized by using methyl methacrylate and a small amount of ethyl acrylate And an average particle diameter up to an elastic body as an intermediate layer was 240 nm.

The following properties of the mixed resin (melt-kneaded product) or the single resin used in each of the examples and comparative examples were measured, and the following evaluation tests were carried out on the unstretched product, the longitudinally new product, and the longitudinally and transversely stretched product obtained in each of the examples and the comparative examples . The results are shown in Table 1.

(1) Weight average molecular weight, number average molecular weight and molecular weight distribution of mixed resin or single resin 40 mg of a mixed resin or a pallet type single resin having a pellet shape was dissolved in 20 mL of tetrahydrofuran to prepare a sample to be measured. And elution time and strength were measured. From these measurements, the weight average molecular weight M _w and the number average molecular weight M _n were determined on the basis of the calibration curve of the standard sample to calculate the molecular weight dispersion M _w / M _n .

Details of the GPC measurement conditions are as follows.

ㆍ GPC apparatus: "HLC-8320GPC" manufactured by Tosoh Corporation,

Gel penetration chromatography column: one in which two TSKgel-SuperHZ2500 and TSKgel-SuperHRC manufactured by Tosoh Corporation are connected in series,

Column temperature: 40 DEG C,

ㆍ Detector: RI detector,

ㆍ Measured sample injection amount: 20 μL,

ㆍ Mobile phase: tetrahydrofuran,

Flow rate of mobile phase: 1.0 mL / min,

Standard sample: Seven monodispersed methyl methacrylate of known weight average molecular weight (all manufactured by Showa Denko K.K.).

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

And a pellet-type mixed resin or a pellet-shaped resin was obtained at a nitrogen flow rate of 100 ml / min by a differential scanning calorimetry method based on JIS K 7121: 1987 using a DSC apparatus [DSC7020, manufactured by Seiko Instruments Inc.] The single resin was heated to 150 ° C at a temperature raising rate of 20 ° C / min and held for 5 minutes, then cooled down to -50 ° C at a temperature decreasing rate of 10 ° C / minute and held for 1 minute. Subsequently, the glass transition temperature was raised from -50 ° C to 210 ° C at a heating rate of 10 ° C / min to obtain the midpoint glass transition temperature (Tmg), which was regarded as the glass transition temperature. The larger this value is, the higher the heat resistance is.

(3) Evaluation of the toughness of the unfinished or new product

(3-1) Mandrel test

A test piece having a length of 120 mm and a width of 10 mm in the machine direction (MD) of the film in the machine direction was cut out from the film. A mandrel bending test was performed on the test piece by winding it around a cylindrical core bar using a flexural tester (cylindrical mandrel method) manufactured by TP Kiken KK to bend the test piece along its width direction. , The minimum diameter of the mandrel free from creep, crack, and breakage was obtained. The smaller the value of the minimum diameter, the better the toughness of the film, and the better the handling and the processability. The mandrel test was conducted on unfinished and new products.

(3-2) Charpy impact test

Was measured in accordance with the Charpy impact test for measuring the impact absorption energy of the plastic specified in JIS K 7111: 2006 "Method of obtaining plastic-Charpy impact characteristics - Part 1: Non-shattering impact test". Specifically, first, a test piece having a length of 82 mm and a width of 10 mm, in which the mechanical extrusion direction (MD) of the film was the longitudinal direction, was cut from the film. The JIS standard specifies the case where a test piece having a notch is used and the case where a test piece without a notch is used. In the present invention, a test piece without a notch is used. Next, in order to prevent the test piece from moving due to the impact when punching with the hammer, both ends of the test piece in the long side direction were fixed to a support, and a hammer was attached to the support with a Charpy impact tester (hammer weighing 1.0 J) manufactured by Yasuda Seiki KK The energy required for rupture of the film (impact absorption energy, mJ) was measured by aligning the longitudinal direction of the knife edge so as to be parallel to the width direction at the longitudinal center portion of the test piece. As the impact absorption energy is larger, the film is less prone to cracking, peeling, cracking and breakage, good toughness, and excellent handling and workability. Measurement of Charpy impact absorption energy was carried out with respect to an unfinished product.

(3-3) Number of times the film breaks when a new product is manufactured from an unfinished new product

The number of times of breakage of the film produced when a longitudinally long product (about 50 m) was produced from the undrawn product having a long length under the above-described stretching conditions was counted. The smaller the number of times of breakage, the better the toughness of the film and the better the workability.

(4) Evaluation of the heat resistance of unfinished or new products

(4-1) Measurement of heat shrinkage rate

A test piece having a length of 120 mm and a width of 120 mm in the machine direction (MD direction) and a width (TD direction: perpendicular to the MD) of the film was cut from the film, At two points (50 mm). The test piece was subjected to a heating test in which it was allowed to stand in an oven at 100 캜 for 10 minutes. (Length between markings) in the MD direction and the TD direction before and after the heating test was measured using Digital Noise, and with respect to each of the MD direction and the TD direction, the following formula:

Heat shrinkage percentage (%) = 100 占 (length before heating - length after heating) / (length before heating)

(%) Of the heat shrinkage was determined. The smaller the heat shrinkage ratio, the better the heat resistance. The measurement of the shrinkage percentage of the heat shrinkage was performed on unstirred new products and longitudinally and laterally stretched products.

(4-2) Measurement of high temperature tensile modulus

The tensile modulus (MPa) of the film was measured by using a tensile tester ("Autograph AG-1" manufactured by Shimadzu Corporation) under the condition of a temperature of 80 ° C under a tensile rate of 1 mm / min . The higher the tensile modulus of elasticity, the better the heat resistance. The measurement of the high-temperature tensile modulus of elasticity was carried out on the longitudinally and transversely elongated products.

Example Comparative Example One 2 3 4 One 2 3 4 Suzy
Composition
(Weight ratio) Resin A 75 50 75 50 100 70 - - Resin B1 25 50 - - - - 100 - Resin B2 - - 25 50 - - - 100 Rubber particles - - - - - 30 - - The weight average molecular weight M _w 101000 - - - 78200 - 162000 134000 Number average molecular weight M _n 51500 - - - 41200 - 84500 67000 Molecular weight dispersion M _w / M _n 2.0 - - - 1.9 - 1.9 2.0 Glass transition temperature (캜) 120 115 117 115 124 114 110 107 Personality evaluation [Unbreakable] Mandrel test (mmφ) 3 3 4 3 4 One 3 3 [New goods] mandrel test (mmφ) 6 - - - 8 - - - [Unstable] Charpy impact test (mJ) 33 35 28 33 31 108 58 42 [Unbreakable] Number of film breaks (times) One One 2 One 3 to 4 0 One One Heat resistance
evaluation [Unconventional] MD / TD Heat Shrinkage (%) 0.2 / 0.2 - - - 0.1 / 0.1 - - 0.5 / 0.3 [Vertically and Horizontally New] MD / TD Heat Shrinkage (%) 0.2 / 0.1 0.4 / 0.3 0.2 / 0.2 0.3 / 0.4 0.1 / 0.1 0.5 / 0.5 0.5 / 0.5 0.5 / 0.7 [Vertically and Horizontally New] High Temperature Tensile Modulus (MPa) 1660 1560 1640 1580 1730 1200 1500 1410

Claims (7)

(Meth) acrylic resin A,
(Meth) acrylic resin B having a lower glass transition temperature than the (meth) acrylic resin A and a weight average molecular weight of 100000 or more
(Meth) acrylic resin composition. The (meth) acrylic resin composition according to claim 1, wherein a difference between a glass transition temperature of the (meth) acrylic resin (A) and a glass transition temperature of the (meth) acrylic resin (B) The (meth) acrylic resin composition according to claim 1 or 2, which is a melt-kneaded product of the (meth) acrylic resin A and the (meth) acrylic resin B. A (meth) acrylic resin film comprising the (meth) acrylic resin composition according to claim 1. A stretched film obtained by stretching the (meth) acrylic resin film according to claim 4. A polarizing film,
The (meth) acrylic resin film according to claim 4, which is laminated on at least one surface of the polarizing film, or the stretched film according to claim 5
. The polarizing plate according to claim 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.