TWI593997B - A polarizing plate protective film includes a polarizing plate and a polarizing plate protective film - Google Patents

Description

Polarizing plate protective film, polarizing plate therewith, and manufacturing method of polarizing plate protective film

The present invention relates to a polarizing plate protective film excellent in flexibility, a polarizing plate including the same, and a method for producing a polarizing plate protective film.

In recent years, display devices have been strongly demanded for enlargement, thinning, or flexibility, and the high functionality of various members including polarizing plates has progressed.

A polarizing plate that is combined with an image display device in which an organic electroluminescence device (hereinafter also referred to as an organic EL device) is mounted generally has a configuration in which a polarizer is disposed between two protective films, and an antireflection function is added to the polarizing plate. A protective film imparting a phase difference is used on the side of the organic EL element. Further, a liquid crystal display device (LCD) has a liquid crystal cell and a pair of polarizing plates sandwiched therebetween.

In the polarizing plate used in the display devices, in particular, the polarizing plate on the visual recognition side is required to have high scratch resistance in order to prevent surface scratches, and therefore, the polarizing plate protective film for the polarizing plate on the visual recognition side is improved. The surface hardness has been explored. For example, improve the polarizer protection A method of laminating a hard coat layer on a base film is known as a method of protecting the surface hardness of a film (for example, refer to Patent Document 1).

However, such a hard coating layer having a high hardness has a problem of poor bendability.

On the other hand, cellulose acetate film which has been widely used as a substrate in the past has the disadvantage of hygroscopicity or moisture permeability, and the cycloolefin film has few disadvantages, water resistance, heat resistance, transparency or dimensional stability. Excellent properties such as excellent thermoplastic resins as protective films have attracted attention. However, the cycloolefin-based resin used has a slightly brittle nature as compared with the cellulose ester resin, and has a problem of poor bendability or workability.

In order to use such a cycloolefin-based resin as a substrate, the flexibility of a polarizing plate protective film having a hard coat layer is improved, and a urethane (meth)acrylate having a specific configuration in the hard coat layer is disclosed. A hard coat film of a compound (for example, refer to Patent Document 2).

However, the polarizing plate protective film having high flexibility required as a display device which can be used for bending is not sufficient.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2013-127058

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2014-16608

The present invention has been made in view of the above problems and circumstances, and a problem to be solved is to provide a polarizing plate protective film excellent in flexibility and a polarizing plate provided therewith. Further, a method of manufacturing a polarizing plate protective film is provided.

In order to solve the above problems, the inventors of the present invention have a benzotriazole-based or triazine-based ultraviolet absorber, or a compound having the following formula, in the process of reviewing the cause of the above problems. (1) The polyester-based additive of the structure shown is a phenomenon in which the elongation at break of the tensile test and the Martens hardness of the surface of the resin layer are increased. Further, by using the resin as a substrate of a polarizing plate protective film having a hard coating layer, it has been found that the flexibility can be greatly improved, and thus the present invention has been completed.

That is, the above problems of the present invention are solved by the following means.

1. A polarizing plate protective film characterized by having a polarizing plate protective film of a resin layer containing a cycloolefin resin as a main component, and adjusting the stretching of the resin layer measured in an environment of 23 ° C ‧55% RH The elongation at break of the test was in the range of 6 to 20%, and the Martens hardness of the surface of the resin layer was in the range of 145 to 160 N/mm ² .

2. The polarizing plate protective film according to item 1, wherein the resin layer has a hard coat layer having a thickness of from 1 to 8 μm.

3. The polarizing plate protective film according to the first aspect, wherein the resin layer contains a benzotriazole-based or triazine-based ultraviolet absorber in an amount of at least 0.5 to 5% by mass based on the cycloolefin-based resin, or ring The olefin-based resin contains a polyester-based additive having a structure represented by the following general formula (1) in an amount of from 1 to 10% by mass.

General formula (1): B-(GA) _n -GB

(wherein B represents a group derived from a hydroxyl group-containing monocarboxylic acid having a ring structure, and G represents an alkanediol having 2 to 12 carbon atoms, a cycloalkanediol having 6 to 12 carbon atoms, and a carbon number; a group derived from a group of 4 to 12 oxyalkylene glycols and an aromatic diol having 6 to 12 carbon atoms, and A represents a free dialkyl dicarboxylic acid having 4 to 12 carbon atoms and 6 carbon atoms. a group derived from a group selected from the group consisting of a naphthenic dicarboxylic acid of ~12 and an aromatic dicarboxylic acid having 8 to 16 carbon atoms, and n represents an integer of 0 or more).

4. The polarizing plate protective film according to Item 1, wherein the thickness of the resin layer is in the range of 20 to 40 μm.

A polarizing plate comprising a polarizing plate protective film according to any one of items 1 to 4, wherein a polarizing film is provided on one side of the polarizer, and a retardation film is provided on the other side of the polarizer.

A method for producing a polarizing plate protective film, which is characterized in that it is a method for producing a polarizing plate protective film having a resin layer containing a cycloolefin resin as a main component and a hard coat layer, and is subjected to the following steps: A benzotriazole-based or triazine-based ultraviolet absorber containing at least 0.5 to 5% by mass of the cycloolefin-based resin, or for the aforementioned ring In the olefin-based resin, a polyester-based additive having a structure represented by the following general formula (1) and a solution containing a cycloolefin-based resin are cast on a substrate in a range of 1 to 10% by mass to form the resin layer.

General formula (1): B-(GA) _n -GB

(wherein B represents a group derived from a hydroxyl group-containing monocarboxylic acid having a ring structure, and G represents an alkanediol having 2 to 12 carbon atoms, a cycloalkanediol having 6 to 12 carbon atoms, and a carbon number; a group derived from a group of 4 to 12 oxyalkylene glycols and an aromatic diol having 6 to 12 carbon atoms, and A represents a free dialkyl dicarboxylic acid having 4 to 12 carbon atoms and 6 carbon atoms. a group derived from a group selected from the group consisting of a naphthenic dicarboxylic acid of ~12 and an aromatic dicarboxylic acid having 8 to 16 carbon atoms, and n represents an integer of 0 or more).

According to the above-described means of the present invention, it is possible to provide a polarizing plate protective film excellent in flexibility and a polarizing plate provided therewith. Further, a method of manufacturing a polarizing plate protective film can be provided.

The mechanism and mechanism of action of the effects of the present invention are not clear, but are presumed as follows.

Fig. 1 is a conceptual diagram showing a mechanism in which a polarizing plate protects a film from cracking. When the polarizing plate protective film having a hard coating layer on the substrate is bent inside while the hard coating layer is bent, it is considered that the substrate of the stretching side is bent at the time of bending. The curved portion A and the portion B of the hard coat layer are cracked. In the polarizing plate protective film of the present invention, since the elongation at the break point of the substrate is high, it is considered that the bent portion A of the substrate can be stretched and cracking is less likely to occur. Further, the portion B of the hard coating layer on the stretch side at the time of bending is considered to be able to alleviate the stress applied to the portion B of the hard coat layer due to the high surface hardness of the resin layer to be contacted, and is considered to be improved by improving the properties of the substrate. The polarizing plate protects the bendability of the film.

A‧‧‧Bending part of the resin layer on the extended side when bent

B‧‧‧Bending part of the hard coating on the extended side when bent

1‧‧‧Polarizer protective film

2‧‧‧Resin layer (substrate)

3‧‧‧hard coating

Fig. 1 is a conceptual diagram showing a mechanism in which a polarizing plate protects a film from cracking.

Fig. 2 is an example of the configuration of a protective film of a polarizing plate.

The polarizing plate protective film of the present invention is a polarizing plate protective film having a resin layer containing a cycloolefin resin as a main component, and is characterized in that the tensile test of the resin layer is measured at 22 ° C in an environment of ‧55% RH The dot elongation is in the range of 6 to 20%, and the Martens hardness of the surface of the resin layer is adjusted to be in the range of 145 to 160 N/mm ² . These features are common technical features of the invention requested by claim 1 to claim 6.

As an embodiment of the present invention, it is preferable that the resin layer has a hard coat layer having a thickness of 1 to 8 μm in view of the effect of the present invention. Further, the resin layer contains a benzotriazole-based or triazine-based ultraviolet absorber in an amount of at least 0.5 to 5% by mass based on the cycloolefin-based resin. When the polyester-based additive having the structure represented by the above formula (1) is contained in the range of from 1 to 10% by mass in the above-mentioned cycloolefin-based resin, the free volume of the resin can be exhibited and the hardness can be improved. . It is also preferred because it contains a free volume and can also increase the elongation at break point by resin-additive interaction.

Further, in the present invention, it is preferred that the thickness of the resin layer be in the range of 20 to 40 μm. Therefore, when it is 40 μm or less, the stretching of the curved portion A of the resin layer on the extending side at the time of bending as shown in FIG. 1 becomes small, and as a result, the bending resistance is improved, and if it is 20 μm or more, it is obtained. It has sufficient flexibility as a resin layer.

According to an embodiment of the present invention, it is preferable that the polarizing plate protective film is provided on one side of the polarizer and the retardation film is provided on the other side of the polarizer.

Further, a method for producing a polarizing plate protective film which is a resin layer having a cycloolefin-based resin as a main component and a hard coat layer of the present invention is preferably characterized in that the resin layer is formed by the following steps. A method for producing a polarizing plate protective film: a benzotriazole-based or triazine-based ultraviolet absorber containing at least 0.5 to 5% by mass of the cycloolefin-based resin, or 1 to 10 by mass for the above-mentioned cycloolefin-based resin A polyester-based additive having a structure represented by the above formula (1) and a solution containing a cycloolefin-based resin are cast on a substrate in a range of %.

Hereinafter, the present invention and its constituent elements and aspects/patterns for carrying out the invention will be described in detail. In the present invention, "~" is used in the sense of including the numerical values described before and after the lower limit and the upper limit.

"Summary of polarizing plate protective film"

The polarizing plate protective film of the present invention is characterized by a polarizing plate protective film having a resin layer containing a cycloolefin resin as a main component, and is adjusted to a tensile test of the above resin layer measured at 23 ° C ‧55% RH atmosphere The elongation at break point is in the range of 6 to 20%, and the Martens hardness of the surface of the resin layer is in the range of 145 to 160 N/mm ² .

Fig. 2 is an example of a protective film for a polarizing plate of the present invention. The polarizing plate protective film 1 of the present invention may directly use the resin layer 2 as a substrate, but preferably has a hard coat layer 3 on the resin layer 2.

With such a configuration, the flexibility can be improved without impairing the excellent characteristics of the hard coat layer and the cycloolefin resin.

The thickness of the protective film of the polarizing plate varies depending on the purpose of use, but is usually in the range of 5 to 100 μm, preferably 15 to 50 μm in the case of a liquid crystal display device, and particularly preferably in the range of 20 to 40 μm in consideration of the recent thinning. Inside. The thickness of the hard coat layer is preferably in the range of 1 to 10 μm. More preferably in the range of 1 to 8 μm. It is better in the range of 3~5μm.

[break point elongation]

The elongation of the breaking point of the tensile test of the resin layer of the present invention measured in an environment of 23 ° C ‧55% RH is in the range of 6 to 20%, preferably in the range of 10 to 20%. When it is less than 6%, the bending occurs at the bent portion A of the resin layer, and good bending property cannot be obtained. Further, if the elongation at break point exceeds 20%, it is difficult to maintain the elongation at break and the Martens hardness.

The elongation at break was measured in accordance with the method described in JIS K 7127 at 23 ° C in an environment of ‧55% RH. The sample was cut out to have a width of 10 mm and a length of 130 mm, and was obtained by performing a tensile test at a distance between the jigs of 100 mm and a tensile speed of 100 mm/min.

The rupture point elongation can be, for example, the TENSILON universal testing machine RTF series of I&D.

[Martens hardness]

The resin layer of the present invention has a Martens hardness of 145 to 160 N/mm ² as measured on a surface of ‧55% RH at 23 °C. It is preferably in the range of 148 to 160 N/mm ² . By setting the Martens hardness of the resin layer within this range, it is considered that the stress applied to the curved portion B of the hard coat layer in the hard coat layer is not concentrated and is moderated, and cracking is less likely to occur. When the Martens hardness of the surface is less than 145 N/mm ² , the hard coating layer cracking at the time of bending cannot be prevented.

In the present invention, the hardness measured by the state of the load test load (pushing) is determined by the value of the load-pushing depth curve when the load is increased. Martens hardness includes both plastic and elastic deformation components. The Martens hardness is defined for the quadrangular pyramid and the triangular cone. Specifically, as shown in the following formula (a), it is defined as a value obtained by dividing the test load F by the surface area As of the pressure intrusion from the contact zero.

Formula (a) Horse hardness = F / As

The horse hardness is based on the method specified in ISO 14577, self-loading - Press in the depth test. An example of the specific measurement method is shown below.

Performed in the order of the test in accordance with ISO 14577. As the testing machine, an ultra-fine hardness tester (for example, FISHER INSTRUMENTS, trade name "FISHER SCOPE 100C") was used, and as the pressure system, a pyramidal diamond press having a square base and a face angle of 136 was used.

The temperature at the time of the test was set to 23 ° C, and a load of 10 mN was applied to the pressure difference film at a constant speed. The Martens hardness was determined by using square pyramidal diamond presses on the test piece. The calculation of the Martens hardness is obtained by applying a load (10 mN) to the retardation film and dividing by the value of the surface area of the intrusion that exceeds the contact zero.

"Cycloolefin resin"

The polarizing plate protective film of the present invention has a resin layer containing a cycloolefin resin as a main component. The cycloolefin resin of the present invention is exemplified by a (co)polymer having a cycloolefin monomer having the following structure.

Wherein R ¹ to R ⁴ are each independently a hydrogen atom, a hydrocarbon group, a halogen atom, a hydroxyl group, a carboxyl group, an ester group, an alkoxy group, a cyano group, a decylamino group, a fluorenylene group, a decyl group or a polar group ( a hydrocarbon group substituted with a halogen atom, a hydroxyl group, an ester group, an alkoxy group, a cyano group, a decylamino group, a guanidino group or a decyl group. However, two or more R ¹ to R ⁴ may be bonded to each other to form a bond. a saturated bond, a monocyclic ring or a polycyclic ring, which may have a double bond or an aromatic ring, and R ¹ and R ² or R ³ and R ⁴ may also form an alkylene group, p, m Is an integer greater than 0].

In the above formula (2), R ¹ and R ^{3 are} preferably a hydrogen atom or a hydrocarbon number of 1 to 10, more preferably 1 to 4, particularly preferably 1 to 2, and R ² and R ⁴ are a hydrogen atom or a monovalent group. The organic group, at least one of R ² and R ⁴ represents a polar group having a polarity other than a hydrogen atom or a hydrocarbon group, m is an integer of 0 to 3, p is an integer of 0 to 3, more preferably m + p = 0 to 4, Better 0~2, especially good for m=1, p=0. The specific monomer of m=1 and p=0 is preferable in terms of the high glass transition temperature of the obtained cycloolefin resin and excellent mechanical strength.

Examples of the polar group of the specific monomer include a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amine group, a decylamino group, a cyano group, etc., and the polar groups may also be bonded via a linking group such as a methylene group. . Further, a hydrocarbon group or the like which is bonded by a polar divalent organic group such as a carboxyl group, an ether group, a decyl ether group, a thioether group or an imine group as a linking group is also exemplified as a polar group. Among these, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or an aryloxycarbonyl group is preferred, and an alkoxycarbonyl group or an aryloxycarbonyl group is particularly preferred.

Further, at least one of R ² and R ⁴ is a monomer having a polar group represented by the formula -(CH ₂ ) _n COOR , and the obtained cycloolefin-based resin has a high glass transition temperature and low hygroscopicity, and It is preferred in terms of excellent adhesion of various materials. In the formula of the above specific polar group, R is a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms, preferably an alkyl group.

Specific examples of the copolymerizable monomer include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, dicyclopentadiene, and norbornene.

The carbon number as the cyclic olefin is preferably from 4 to 20, more preferably from 5 to 12.

In the present invention, the cycloolefin resin may be used alone or in combination of two or more.

The preferred molecular weight of the cycloolefin resin of the present invention is 0.2 to 5 dL/g, more preferably 0.3 to 3 dL/g, particularly preferably 0.4 to 1.5 dL/g, in terms of intrinsic viscosity [η]inh. The polystyrene-equivalent number average molecular weight (Mn) measured by a permeation chromatography (GPC) is 8,000 to 100,000, more preferably 10,000 to 80,000, particularly preferably 12,000 to 50,000, and a weight average molecular weight (Mw) of 20,000 to 300,000. It is better for 30,000~250000, especially for those ranging from 4000~20000.

When the intrinsic viscosity [η]inh, the number average molecular weight, and the weight average molecular weight are in the above range, heat resistance, water resistance, chemical resistance, mechanical properties of the cycloolefin resin, and moldability as a cycloolefin film of the present invention It is getting better.

The glass transition temperature (Tg) of the cycloolefin resin of the present invention is usually 110 ° C or higher, preferably 110 to 350 ° C, more preferably 120 to 250 ° C, and particularly preferably 120 to 220 ° C. When the Tg is 110 ° C or higher, there is no secondary processing due to use under high temperature conditions or coating or printing. Concerns about the deformation. On the other hand, when Tg is 350 ° C or less, the molding process becomes easy, and the resin is not deteriorated by heat during molding.

The polarizing plate protective film has a resin layer containing a cycloolefin resin as a main component. The main component means that 50% by weight or more of the resin layer is a cycloolefin resin, and preferably 70 to 90% by mass or more.

In the cycloolefin resin, a specific hydrocarbon resin described in Japanese Laid-Open Patent Publication No. Hei 9-221577, No. 10-287732, or a conventional thermoplastic resin can be blended, for example, in the range of the present invention. The thermoplastic elastomer, the rubbery polymer, the organic fine particles, the inorganic fine particles, and the like may contain additives such as a specific wavelength dispersing agent, a sugar ester compound, an antioxidant, a peeling accelerator, rubber particles, and a plasticizer.

The cycloolefin-based resin described above can be preferably used as a commercial product, and can be sold under the trade names of ARTON G, ARTON F, ARTON R, and ARTON RX from JSR (shares), and A trade name seller of ZEONOR ZF14, ZF16, ZEONEX 250 or ZEONEX 280 from Japan ZEON.

"Polyester Additives and UV Absorbers"

The resin layer of the present invention preferably contains a benzotriazole-based or triazine-based ultraviolet absorber in an amount of at least 0.5 to 5% by mass based on the cycloolefin-based resin, or contains the above in an amount of from 1 to 10% by mass. A polyester-based additive having the structure represented by the formula (1).

The present inventors have found that the above-mentioned cycloolefin-based resin is contained a benzotriazole-based or triazine-based ultraviolet absorber, or a polyester-based additive having a structure represented by the above formula (1), having a tensile point elongation at a tensile test and a surface of a resin layer The phenomenon of increased hardness. These phenomena are characteristics of a cycloolefin-based resin because they are not found in the cellulose ester-based resin. As described above, the phenomenon in which the above characteristics are changed by a specific compound is not clear, but it is presumed that the radical volume of the resin is sufficiently buried by the additives to increase the density of the substrate.

The preferred range of the amount of the cycloolefin-based resin to be added varies depending on the additive. When the benzotriazole-based or triazine-based ultraviolet absorber is used, it is preferably in the range of 0.5 to 5% by mass, more preferably in the range of 1 to 4% by mass. When the polyester-based additive having the structure represented by the above formula (1) is used, the additive is preferably in the range of from 1 to 10% by mass, more preferably from 3 to 8% by mass.

<benzotriazole-based and triazine-based ultraviolet absorbers>

The benzotriazole-based ultraviolet absorber is not particularly limited, but is exemplified by, for example, 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5. '-Di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole, 2,2'-Asia Methyl bis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (molecular weight 659; as an example of a commercial product, ADEKA) LA31), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (molecular weight 447.6; as a commercial example, Japan BASF) TINUVIN 234) of the company.

The triazine-based ultraviolet absorber is not particularly limited. Examples are, for example, 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxyl -4-ethoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxy Phenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4 -diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-dodecane Oxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, [2 -(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyl)oxyphenol] (TINUVIN 1577FF, trade name, manufactured by BASF, Japan), [2-[ 4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol] (CYASORB UV-1164, trade name, SAITECH INDUSTRIES) and so on.

<Polyester additive>

The polyester-based additive is a dehydration condensation reaction between a diol and a dicarboxylic acid, and a hydroxyl group of a hydroxyl group-containing monocarboxylic acid having a ring structure is obtained by a dehydration condensation reaction between a diol and a dicarboxylic acid. And get the compound.

The polyester-based additive has a compound having a structure represented by the following formula (1).

General formula (1): B-(GA) _n -GB

Wherein B represents a derivative derived from a hydroxyl group-containing monocarboxylic acid having a ring structure; The basis. The ring structure means a structure having an aliphatic hydrocarbon ring, an aliphatic heterocyclic ring, an aromatic hydrocarbon ring or an aromatic hetero ring, and preferably means a structure having an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring. The hydroxyl group-containing monocarboxylic acid having a ring structure is an alicyclic monocarboxylic acid having 5 to 20 carbon atoms, an aromatic monocarboxylic acid having 7 to 20 carbon atoms, and a mixture thereof.

The alicyclic monocarboxylic acid having 5 to 20 carbon atoms is preferably an alicyclic monocarboxylic acid having 6 to 15 carbon atoms. Examples of the alicyclic monocarboxylic acid include 4-hydroxycyclohexyl acetic acid, 3-hydroxycyclohexyl acetic acid, 2-hydroxycyclohexyl acetic acid, 4-hydroxycyclohexylpropionic acid, 4-hydroxycyclohexylbutyric acid, 4-hydroxyl ring Hexyl glycolic acid, 4-hydroxy-o-methylcyclohexyl acetic acid, 4-hydroxy-m-methylcyclohexyl acetic acid, 4-hydroxy-p-methylcyclohexyl acetic acid, 5-hydroxy-m-methylcyclohexyl Acetic acid, 6-hydroxy-o-methylcyclohexyl acetic acid, 2,4-dihydroxycyclohexyl acetic acid, 2,5-dihydroxycyclohexyl acetic acid, 2-(hydroxymethyl)cyclohexyl acetic acid, 3-(hydroxyl) Cyclohexyl acetic acid, 4-(hydroxymethyl)cyclohexylacetic acid, 2-(1-hydroxy-1-methylethyl)cyclohexylacetic acid, 3-(1-hydroxy-1-methylethyl) ring Hexyl acetic acid, 4-(1-hydroxy-1-methylethyl)cyclohexyl acetic acid, and the like.

The aromatic monocarboxylic acid having 5 to 20 carbon atoms is preferably an aromatic monocarboxylic acid having 6 to 15 carbon atoms. Examples of the aromatic monocarboxylic acid include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 4-hydroxy-o-methylbenzoic acid, 3-hydroxy-p-methylbenzoic acid, 5- Hydroxy-o-methylbenzoic acid, 6-hydroxy-o-methylbenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2-(hydroxymethyl)benzoic acid, 3- (hydroxymethyl)benzoic acid, 4-(hydroxymethyl)benzoic acid, 2-(1-hydroxy-1-methylethyl)benzoic acid, 3-(1-hydroxy-1-methylethyl)benzene Formic acid, 4-(1-hydroxy-1-methylethyl)benzoic acid Wait.

Among these, a hydroxyl group-containing monocarboxylic acid (hydroxy group-containing aromatic monocarboxylic acid) containing an aromatic ring is preferred because it imparts sufficient hydrophobicity to the polarizing plate protective film and is easy to control the deterioration of the polarizer due to moisture. .

In the formula, G is an alkanediol having 2 to 12 carbon atoms, a cycloalkanediol having 6 to 12 carbon atoms, an oxyalkylene glycol having 4 to 12 carbon atoms, and a aryl group having 6 to 12 carbon atoms. At least one derived group selected from the group consisting of diols.

The alkanediol having 2 to 12 carbon atoms comprises ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol , 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentylene glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dihydroxymethylpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3) , 3-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentane Glycol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1 , 12-octadecanediol and the like.

Examples of the cycloalkanediol having 6 to 12 carbon atoms include hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane), hydrogenated bisphenol B (2,2-bis(4-hydroxycyclohexyl) ) Butane).

Examples of the oxyalkylene glycol having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol.

Examples of the aromatic diol having 6 to 12 carbon atoms include bisphenol A and bisphenol B.

The diol may be used alone or as a mixture of two or more. Among them, an alkanediol having 2 to 12 carbon atoms is preferred because it is excellent in compatibility with a cycloolefin resin.

In the formula, A represents at least one selected from the group consisting of an alkanedicarboxylic acid having 4 to 12 carbon atoms, a cycloalkanedicarboxylic acid having 6 to 12 carbon atoms, and an aromatic dicarboxylic acid having 8 to 16 carbon atoms. The base derived.

Examples of the alkyl dicarboxylic acid having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, dodecanedicarboxylic acid and the like.

Examples of the cycloalkanedicarboxylic acid having 6 to 16 carbon atoms include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1, 5-decahydronaphthalene dicarboxylic acid, 1,4-decahydronaphthalene dicarboxylic acid, and the like.

Examples of the aromatic dicarboxylic acid having 8 to 16 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, and 1,4-naphthalene dicarboxylic acid.

The dicarboxylic acid is used alone or as a mixture of two or more. The dicarboxylic acid is preferably a mixture of an alkanedicarboxylic acid and an aromatic dicarboxylic acid. The content ratio of the alkanedicarboxylic acid to the aryldicarboxylic acid is preferably an alkanedicarboxylic acid: aryldicarboxylic acid = 40:60 to 99:1, more preferably 50:50 to 90:10.

In the formula, n represents an integer of 0 or more.

The number average molecular weight of the polyester-based additive is preferably from 300 to 30,000, more preferably from 300 to less than 700, more preferably from 300 to 600. When the number average molecular weight is a certain value or more, it is easy to suppress bleeding. When the number average molecular weight is a certain value or less, the compatibility with the cycloolefin resin is not easily impaired. Inhibition of turbidity rise.

The number average molecular weight of the polyester-based additive is determined by gel permeation chromatography. Specifically, a gel permeation chromatography (GPC) measuring apparatus ("HLC-8330" manufactured by TOSOH Co., Ltd.) can be used, and the number average molecular weight (Mn) in terms of standard polystyrene of the ester compound can be measured under the following measurement conditions. .

(measurement conditions)

Column: "TSK gel SuperHZM-M" × 2 roots and "TSK gel SuperHZ-2000" × 2

Protection column: "TSK SuperH-H"

Developing solvent: tetrahydrofuran

Flow rate: 0.35 mL/min

The number average molecular weight of the polyester-based additive can be adjusted by the reaction time of condensation or polycondensation.

The acid value of the polyester-based additive is preferably 0.5 mgKOH/g or less, more preferably 0.3 mgKOH/g or less. The hydroxyl value of the polyester-based additive is preferably 25 mgKOH/g or less, more preferably 15 mgKOH/g or less.

The synthesis of the polyester-based additive can be carried out by any of the following methods: a hot melt condensation method for esterification or transesterification of a dicarboxylic acid, a diol, and a terminal sealing monocarboxylic acid by a usual method; or An interfacial condensation method of a dicarboxylic acid and a monocarboxylic acid for terminal sealing with ruthenium chloride and a diol. The feed ratio of the diol to the dicarboxylic acid is adjusted to be a diol at the molecular end.

<microparticle>

The base film further contains fine particles (matting agent) in order to impart slidability to the surface. The fine particles may be composed of an inorganic compound or a resin.

Examples of inorganic compounds are ceria, titania, alumina, zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, hydrated calcium citrate, aluminum citrate, magnesium citrate and calcium phosphate. Wait.

Examples of the resin include polyoxyxylene resin, fluororesin, and acrylic resin. Among them, polyoxynoxy resins are preferred, especially those having a three-dimensional network structure, such as TOSPEARL 103, TOSPEARL 105, TOSPEARL 108, TOSPEARL 120, TOSPEARL 145, TOSPEARL 3120, and TOSPEARL 240 (the above is Toshiba Polyoxide) The product name seller of the system).

Among these, cerium oxide fine particles are preferred in terms of reducing the turbidity of the film. Examples of the cerium oxide microparticles are AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (the above is manufactured by Japan AEROSIL Co., Ltd.), and the film is kept at a lower turbidity based on the side. The effect of lowering the friction coefficient is increased, preferably AEROSIL 200V, AEROSIL R972V.

The average particle diameter of the primary particles of the fine particles is preferably from 5 to 400 nm, more preferably from 10 to 300 nm. The fine particles may be contained as a secondary aggregate mainly having a particle diameter of 0.05 to 0.3 μm, and if the particles having an average particle diameter of 100 to 400 nm are not aggregated, they may be contained as primary particles.

"Method for manufacturing resin layer"

The resin layer can be produced by any method, but it is preferably produced by a solution casting method because it is easy to form a film even if the resin having a large molecular weight is easily formed, and the additive is easily added uniformly in the resin layer. The resin layer is formed by casting a solution containing a cycloolefin-based resin onto a substrate. Specifically, a resin layer is preferably formed by casting a solution containing a cycloolefin-based resin onto a substrate.

The resin layer is produced by the steps of: 1) dissolving the above components in a solvent to prepare a dope, 2) pouring the dope onto the annular substrate, and 3) drying the cast dope. The step of peeling off the film, 4) the step of drying and stretching the film.

Further, in the following description, the film of only the resin layer of the present invention is referred to as a resin film.

The solvent used in the step 1) is, for example, a chlorine-based solvent such as chloroform or dichloromethane; an aromatic solvent such as toluene, xylene, benzene or a mixed solvent thereof; methanol, ethanol, isopropanol, and positive An alcohol solvent such as butanol or 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl hydrazine, dioxane, cyclohexanone, Tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether, and the like. These solvents may be used alone or in combination of two or more.

In the solution casting method, although the concentration of the cycloolefin resin in the dope is higher, the concentration is higher than the drying load after casting on the substrate, but when the concentration of the cycloolefin resin is too high, When filtering The load is increased to make the filtration accuracy worse. The concentration is preferably from 10 to 35% by mass, more preferably from 15 to 25% by mass. The substrate in the casting step is preferably a surface-modified mirror, and the substrate is preferably a stainless steel strip or a cast and the surface is plated with a modified roller.

The casting width can be set to 1~4m. The surface temperature of the substrate in the casting step is set to be -50 ° C ~ boiling below the temperature of foaming. When the temperature is high, the drying speed of the web is accelerated, which is preferable, but when it is too high, the sheet is foamed to deteriorate the planarity.

The preferred substrate temperature is suitably determined at 0 to 100 ° C, more preferably 5 to 30 ° C. Alternatively, it may be a method in which the sheet is gelated by cooling to be peeled off from the drum in a state containing a large amount of residual solvent. The method of controlling the temperature of the substrate is not particularly limited, and there is a method of blowing warm air or cold air, and a method of bringing warm water into contact with the inside of the substrate. Since the warm water is used for efficient heat transfer, it is preferable to shorten the temperature of the substrate for a certain period of time.

In the case of using warm air, the temperature of the sheet may be lowered by the latent heat of vaporization of the solvent, and the warm air having a boiling point or higher of the solvent may be used, and the wind may be prevented from being foamed and the temperature higher than the target temperature may be used.

In particular, it is preferred to change the temperature of the substrate and the temperature of the drying air from casting to peeling to effect effective drying.

In order to make the transparent resin film exhibit good planarity, the amount of residual solvent when the sheet is peeled off from the substrate is preferably from 10 to 150% by mass, more preferably from 20 to 40% by mass or from 60 to 130% by mass, particularly preferably from 20 to 20%. 30% by mass or 70 to 120% by mass.

The amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(M - N) / N} × 100

Further, M is the mass of the sample taken at any time during or after the production of the sheet or film, and N is the mass after heating M at 115 ° C for 1 hour.

Further, in the drying step of the transparent resin film, the sheet is peeled off from the substrate and further dried, and the residual amount of the solvent is preferably 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0% to 0.01% by mass or less.

The film drying step is carried out by means of a general roll drying method (the sheets are alternately passed through a plurality of rolls arranged one above the other and dried) or a tenter method to transport the sheets while drying.

In the stretching step, the elongation of the maximum stretching direction (the direction in which the elongation is the largest) is preferably from 5 to 30%, more preferably from 12 to 28%. For example, when extending in the two-axis direction orthogonal to each other, the transport direction (MD direction) is set to 0 to 15%, and the width direction (TD direction) is set to 5 to 30%. The elongation (%) is defined by the following formula.

Elongation (%) = {(length of the film after stretching (length of extension) - length of film (extension direction) before stretching / length of (stretching direction) of film before stretching} × 100

The extension temperature is 120 to 180 ° C, preferably 140 to 180 ° C, more preferably 145 to 165 ° C.

The residual solvent of the film at the start of stretching is preferably less than 5% by mass, more preferably 4% by mass or less, and still more preferably 2% by mass or less, from the viewpoint of suppressing the increase in turbidity. Residual solvent at the beginning of the extension When the amount is less than 5% by mass, it is preferred to set the drying step to evaporate the solvent during the process of peeling the cast concentrate from the substrate and transferring it.

The method for extending the film is not particularly limited, and may be a method in which the plurality of rolls have a peripheral speed difference, and a difference in the circumferential direction of the roll is used in the MD direction; or a film may be fixed by a tenter or a needle by a tenter. The method of extending the extension of the jig or the needle in the TD direction, and the like. Among them, the extension of the TD direction is preferably carried out by a tenter, which may be a needle tenter or a clamp tenter.

In the other steps, it is the same as the conventional solution casting method, for example, paragraphs 0109 to 0140 of JP-A-2012-48214.

Hard Coating

The polarizing plate protective film of the present invention preferably has a hard coat layer. By having a hard coat layer, impact resistance, ease of handling, and the like of the polarizing plate can be improved.

The material for forming the hard coat layer is not particularly limited as long as it exhibits a hardness of "HB" or more in the pencil hardness test prescribed by JIS K5700, but is preferably a cured product containing a reactive wire curable compound as active wire curability. As the compound, a component containing a monomer having an ethylenically unsaturated double bond can be preferably used. The active-curable compound is exemplified by an ultraviolet curable compound or an electron beam curable compound, but a compound which is cured by ultraviolet irradiation is preferred because it is excellent in mechanical film strength (scratch resistance, pencil hardness).

For example, there are organic polyoxane type, melamine type, epoxy type, acrylate type, polyfunctional (meth)acrylic type compound, etc. Machine hard coating materials; inorganic hard coating materials such as cerium oxide. Among them, a hard coating forming material of a (meth)acrylic or polyfunctional (meth)acrylic compound is preferably used because of its excellent adhesion and excellent productivity. Here, the (meth)acryl group means a propenyl group and a methacryl group.

The (meth) acrylate may, for example, be a (meth) acrylate oligo having one polymerizable unsaturated group in the molecule, two having three or more, and having three or more polymerizable unsaturated groups in the molecule. Polymer. (Meth) acrylate may be used alone or in combination of two or more.

Further, in the hard coat layer of the present invention, various additives may be further formulated as needed within the range not impairing the effects of the present invention. For example, an antioxidant, an ultraviolet stabilizer, an ultraviolet absorber, a surfactant, a leveling agent, an antistatic agent, or the like can be used, and the hard coat layer of the present invention contains particles having an average particle size of 0.2 to 10 μm. The anti-glare property is imparted, and the high refractive index fine particles are dispersed and the refractive index can be imparted.

The leveling agent is effective in reducing surface irregularities especially when a hard coat layer is applied. As the leveling agent, for example, a polyoxymethylene-based leveling agent is preferably a dimethylpolysiloxane-polyoxyalkylene copolymer.

The particles having an average particle size of 0.2 to 10 μm are preferably inorganic particles, and examples of the inorganic particles are cerium oxide, zinc oxide, ITO (indium oxide/tin oxide), ATO (cerium oxide/tin oxide), and tin oxide. At least one or more selected from the group consisting of indium oxide, tungsten oxide, composite tungsten oxide, and cerium oxide. Among them, yttrium oxide fine particles are preferred because of the effect of particularly improving the surface hardness. Moreover, the ultraviolet absorbing property is added to the hard coat layer, and the deterioration of the hard coat layer is suppressed. From the viewpoint, it is preferred to use ITO, ATO, tungsten oxide or composite tungsten oxide.

As the ultraviolet stabilizer, for example, a hindered amine-based ultraviolet stabilizer having high ultraviolet stability can be preferably used. By including the ultraviolet stabilizer in the hard coat layer, the radicals generated by the ultraviolet rays, active oxygen, and the like can be inertized, and the ultraviolet stabilizer, weather resistance, and the like can be improved.

Examples of the ultraviolet absorber include, for example, a salicylic acid-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, a cyanoacrylate-based ultraviolet absorber, and a triazine-based ultraviolet absorber. As the benzoxazinone-based ultraviolet absorber or the like, one or two or more selected from the group may be used. Among them, a triazine-based ultraviolet absorber and a benzoxazinone-based ultraviolet absorber are preferred from the viewpoint of dispersibility. Further, as the ultraviolet absorber, a polymer having an ultraviolet absorbing group in a molecular chain can also be preferably used. When the polymer having an ultraviolet absorbing group in the molecular chain is used, it is possible to prevent deterioration of the ultraviolet absorbing function due to bleeding of the ultraviolet absorbing agent or the like. The ultraviolet absorbing group is exemplified by a benzotriazole group, a benzophenone group, a cyanoacrylate group, a triazinyl group, a salicylate group, a benzylidene malonate group or the like. Among them, benzotriazolyl, benzophenone, and triazinyl are particularly preferred.

The method of forming the hard coat layer is not particularly limited, and the coating liquid of the hard coat forming material may be subjected to a dipping method, a spray method, a slip coating method, a bar coating method, a roll coating method, or a die mouth. A conventional method such as a coating method, a gravure coating method, or a screen printing method is applied to an optical film containing a polymer having an alicyclic structure, and is removed by drying in an atmosphere such as air or nitrogen. The cloth-based acrylic hard coat material is cross-linked and cured by ultraviolet rays or electron beams, and is coated with a polyoxymethylene-based, melamine-based or epoxy-based hard coat material and thermally cured. In the case of drying, since the film thickness unevenness of the coating film is likely to occur, it is preferred to adjust the suction and the exhaust gas so as not to impair the appearance of the coating film, and the coating film is controlled to be uniform. When a material hardened by ultraviolet rays is used, the irradiation time of the hard coating forming material after application by ultraviolet irradiation is usually in the range of 0.01 second to 10 seconds, and the irradiation amount of the energy source source is cumulative exposure at an ultraviolet wavelength of 365 nm. The gauge is usually in the range of from 40 mJ/cm ² to 1000 mJ/cm ² . Further, the irradiation of ultraviolet rays may be carried out in an inert gas such as nitrogen or argon, or may be carried out in the air.

The hard coating layer has a dry layer thickness and a layer thickness of 1 to 8 μm, preferably 3 to 5 μm.

(Manufacturing method of polarizing plate protective film having hard coating layer)

A polarizing plate protective film having a hard coating layer (also referred to as a polarizing plate protective film having an HC layer) is produced by the steps of: 1) preparing a resin film as described above, and 2) coating an active film on the resin film. After the coating liquid for the energy ray hardened layer, the step of drying and hardening to obtain an active energy ray hardened layer is obtained.

The steps of preparing the resin film of the above 1) are as described above.

The application of the coating liquid for an active energy ray-hardening layer of the above 2) can be carried out by any means such as a dipping method, a die coating method, a wire coating method, or a spray method.

The curing of the coating film of the coating liquid for the active energy ray-hardening layer of the above 2) can be carried out by irradiating the active energy ray. Examples of the light source that illuminates the active energy ray (preferably ultraviolet ray) are a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, and the like. The irradiation light may be about 20 to 10000 mJ/cm ² , preferably 50 to 2000 mJ/cm ² . The irradiation time is preferably from 0.5 second to 5 minutes, and is preferably from 3 seconds to 2 minutes based on the viewpoint of work efficiency and the like.

<polarizer>

The polarizer is an element that passes only the light of the deflecting surface in one direction, and a representative polarizer is now known as a polyvinyl alcohol-based polarizing film. The polyvinyl alcohol-based polarizing film has a dyed iodine for a polyvinyl alcohol-based film and a dyed dichroic dye.

The polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and dyed with iodine or a dichroic dye (preferably, a film treated with a boron compound for durability); The vinyl alcohol-based film is dyed with iodine or a dichroic dye, and then subjected to a uniaxially stretched film (preferably, a film treated with a boron compound for durability treatment). The absorption axis of the polarizer is parallel to the direction in which the film extends.

For example, an ethylene modification having an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol% described in JP-A-2003-248232, JP-A-2003-342322, and the like is used. Polyvinyl alcohol and the like. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cut-off temperature of 66 to 73 ° C is preferably used.

The thickness of the polarizer is preferably 5 to 30 μm, and is preferably 10 to 20 μm in order to reduce the thickness of the polarizing plate.

<Other polarizing plate protective film>

On the other surface of the polarizer, the polarizing plate protective film or the base film may be disposed as needed, and other polarizing plate protective films may be disposed.

Other polarizing plate protective films include commercially available cellulose halide films (eg, KONICA MINOLTA TAC KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC8UY). -HA, KC8UX-RHA, KC8UE, KC4UE, KC4HR-1, KC4KR-1, KC4UA, KC6UA, the above is KONICA MINOLTA (share) system, etc.

The present invention preferably comprises the polarizing plate protective film of the present invention on one side of the polarizer, and a retardation film on the other side of the polarizer.

Other polarizing plate protective films are preferably retardation films. The hysteresis value of the retardation film is determined according to the type of liquid crystal cell to be combined, but it is preferably 20, for example, at 23 ° C, ‧55% RH, and the retardation value Ro(590) measured in the in-plane direction at a wavelength of 590 nm is 20 ~100nm, the hysteresis value Rth(590) of the preferred thickness direction is 70~300nm. The protective film having a hysteresis value of the above range is suitable as, for example, a retardation film of a VA type liquid crystal cell or the like. Each hysteresis value was determined by the following method.

The hysteresis values Ro and Rth are respectively defined by the following equations.

Formula (I): Ro = (n _{x -} n _y ) × _d (nm)

Formula (II): Rth={(n _x +n _y )/2-n _z }×d(nm)

(In the formulae (I) and (II), n _x represents the refractive index of the slow axis direction x in which the refractive index of the film in the in-plane direction is the largest; n _y represents the in-plane direction of the film orthogonal to the aforementioned slow axis direction x The refractive index of the direction y; n _z represents the refractive index of the thickness direction z of the film; d (nm) represents the film thickness)

The hysteresis values Ro and Rth can be obtained, for example, by the following method.

1) The polarizing plate protective film was conditioned at 23 ° C ‧ 55% RH, and the average refractive index of the polarizing plate protective film after humidity control was measured by an Abbe refractometer or the like.

2) Measurement of RO by measuring the light having a wavelength of 590 nm in parallel with the normal line of the surface of the film after the humidity-protected polarizing plate protective film was measured by KOBRA-21DH manufactured by Oji Scientific Instruments Co., Ltd.

3) Using KOBRA-21ADH, the in-plane slow axis of the polarizing plate protective film is measured as an oblique axis (rotation axis), and light having a wavelength of 590 nm is incident from an angle (incident angle (θ)) to the normal θ of the film surface. The hysteresis value of time R (θ). The hysteresis value R(θ) can be measured in the range of θ from 0 to 50° at 6 o'clock every 10°. The in-plane slow axis means the axis with the largest refractive index in the plane of the film, which can be confirmed by KOBRA-21ADH.

4) From the measured Ro and R(θ) and the average refractive index and film thickness, n _x , n _y and n _z were calculated by KOBRA-21ADH, and Rth at a measurement wavelength of 590 nm was calculated. The hysteresis value can be measured at 23 ° C ‧ 55% RH.

The thickness of the protective film of the other polarizing plate is not particularly limited, and is preferably 10 to 250 μm, more preferably 10 to 100 μm, and particularly preferably 30 to 60 μm.

The polarizing plate of the present invention can be obtained by the steps of: bonding a polarizer to the polarizing plate protective film of the present invention via an adhesive; and cutting the laminated laminate into a specific size.

The adhesive used for the bonding may be a fully saponified polyvinyl alcohol aqueous solution (water paste) or an active energy ray-curable adhesive.

[Examples]

The invention will be specifically described below by way of examples, but the invention is not limited thereto. In addition, in the examples, the expression "parts" or "%" is used, and unless otherwise specified, "mass parts" or "mass%" are indicated.

The compounds used in the following examples are shown along with their abbreviations.

[Synthesis of Polyester Additives]

The polyester-based additives P1 to P5 having the structure represented by the general formula (1) and the polyester-based additives P6 and P7 as other polyester-based additives are synthesized.

(Synthesis of polyester additive P1)

341 parts of ethylene glycol, terephthalic acid and succinic acid were fed in a molar ratio of 5:5 of 410 parts, 610 parts of 4-hydroxybenzoic acid and 0.35 parts of tetraisopropyl titanate as an esterification catalyst. In a 2L four-necked flask equipped with a thermometer, a stirrer, and a rapid cooling tube, the mixture was stirred under a nitrogen stream, and the excess monovalent alcohol was refluxed while continuing to heat at 230 ° C until the acid value became 2 or less, and the product was continuously removed. Water. Next, unreacted ethylene glycol was distilled off under reduced pressure of 4 × 10 ² Pa or less at 200 ° C to obtain a polyester-based additive P1.

<Synthesis of polyester additive P2~P5>

The polyester-based additives P2 to P5 were obtained in the same manner except that the types of the diol, the dicarboxylic acid, and the terminal blocking monocarboxylic acid were changed as shown in Table 1.

<Synthesis of polyester-based additives P6 and P7>

The polyester-based additives P6 and P7 were obtained in the same manner except that the types and molecular weights of the diol, the dicarboxylic acid, and the terminal blocking monocarboxylic acid were changed as shown in Table 1.

The number average molecular weight of the obtained polyester-based additive was measured by the following method.

(Measurement of number average molecular weight (Mn))

A gel permeation chromatography (GPC) measuring apparatus ("HLC-8330" manufactured by TOSOH Co., Ltd.) was used, and the number average molecular weight (Mn) of the polyester compound in terms of standard polystyrene was measured under the following conditions.

Column: "TSK gel SuperHZM-M" × 2 roots and "TSK gel SuperHZ-2000" × 2

Protection column: "TSK SuperH-H"

Developing solvent: tetrahydrofuran

Flow rate: 0.35 mL/min

These results are shown in Table 1. Further, in Table 1, HBPA represents hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane).

[Cycloolefin resin]

COP1: cycloolefin resin (ARTON G7810, manufactured by JSR)

COP2: cycloolefin resin (ARTON R5000, manufactured by JSR)

COP3: cycloolefin resin (ARTON RX4500, manufactured by JSR)

[Benzotriazole-based UV absorber]

UV1: TINUVIN 928 (made by BASF, Japan)

UV2: ADEKASTAB LA-31 (made by Adeka)

UV3: 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2-benzotriazole

UV4: (2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole

UV5: 2-(2'-hydroxy-3',5'-di-third-pentylphenyl)benzotriazole

UV6: 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole [triazine UV absorber]

UV7: TINUVIN 477 (made by BASF, Japan)

UV8: ADEKASTAB LA-F70 (made by Adeka)

UV9: 2,4,6-tris(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine

UV10: 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyphenyl)-1,3,5-triazine

UV11: 2,4,6-tris(2-hydroxy-3-methyl-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl) -1,3,5-triazine

UV12: 2,4,6-tris(2-hydroxy-3-methyl-4-hexyloxyphenyl)-1,3,5-triazine

[Inorganic Microparticles]

Inorganic particles: SiO ₂ microparticles (AEROSIL R972V, manufactured by Japan AEROSIL Co., Ltd.)

[Hard coating layer coating solution]

(Modulation of Hard Coating Layer Coating Liquid 1 (HC1))

The hard coat layer coating liquid 1 of the following composition was prepared. UV curing type After the resin was mixed with the surfactant and propylene glycol monomethyl ether, the mixture was stirred for 30 minutes to prepare a hard coat layer coating liquid 1.

(Modulation of Hard Coating Layer Coating Liquid 2 (HC2))

The hard coat layer coating liquid 2 of the following composition was prepared in the same manner as the hard coat layer coating liquid 1.

(modulation of hard coating layer coating liquid 3 (HC3))

The hard coat layer coating liquid 3 of the following composition was prepared in the same manner as the hard coat layer coating liquid 1.

UV curable resin (OPSTAR Z7527, manufactured by JSR)

[Preparation of microparticle dispersion and microparticle addition solution]

11.3 parts by mass of granules (AEROSIL R972V, manufactured by AEROSIL Co., Ltd.) and 84 parts by mass of ethanol were stirred and mixed for 50 minutes in a dispersing machine, and then dispersed in a high-pressure emulsifier.

To the dichloromethane (100 parts by mass) which was sufficiently stirred in the dissolution tank, 5 parts by mass of the fine particle dispersion was slowly added. Further, it is dispersed by an attritor so that the particle diameter of the secondary particles becomes a specific size. This was filtered with FINEMATE NF manufactured by Nippon Seisaku Co., Ltd. to prepare a fine particle addition liquid.

"Production of Polarizing Plate Protective Film 1" [modulation of main concentrated liquid]

The main dope of the following composition was prepared. First, dichloromethane and ethanol were added to the pressure tank. The cycloolefin resin was introduced while stirring in a pressure dissolution tank to which a mixed solution of dichloromethane and ethanol was fed. It was completely dissolved by heating while stirring. The mixture was filtered using Angstrom filter paper No. 244 made of a filter paper (strand) to prepare a main dope.

(main concentrate)

The above components were placed in a closed container, and the main dope was dissolved and dissolved while stirring. Next, the dope was uniformly poured on the stainless steel belt base at a temperature of 31 ° C and a width of 1800 mm using an endless belt casting apparatus. The temperature of the stainless steel belt is controlled at 28 °C.

On the stainless steel strip substrate, the solvent was evaporated so that the amount of residual solvent in the cast film became 30%. Next, it was peeled off from the stainless steel strip substrate at a peeling tension of 128 N/m. The residual solvent at the start of the peeling film extension was 5% by mass. Next, the drying was carried out by a plurality of rolls to the drying zone, and the end portion held by the tenter jig was cut by a laser cutter, and then wound up to prepare a resin film 1 having a thickness of 30 μm and a width of 1200 mm.

On one surface of the resin film 1 obtained above, the hard coat layer coating liquid 1 was applied using a micro gravure, and the film was applied to a dry film thickness of 5 μm and dried.

Then, the coating film was irradiated with ultraviolet light at a light amount of 270 mJ/cm ² in the atmosphere using a high-pressure mercury lamp, and cured, and a polarizing plate protective film 1 having a hard coat layer formed on the transparent resin film 1 was produced.

"Production of Polarizing Plate Protective Film 2"

In the production of the polarizing plate protective film 1, on the stainless steel tape substrate, the solvent is evaporated so that the amount of residual solvent in the cast film becomes 30%. Thereafter, the peeled film was stretched by 10% in the width direction at 160 ° C. The resin film 2 and the polarizing plate protective film 2 were produced in the same manner as in the production of the polarizing plate protective film 1 .

"Production of Polarizing Plate Protective Film 3"

In the production of the polarizing plate protective film 2, it was extended by 20% in the width direction at 160 °C. Similarly to the production of the polarizing plate protective film 2, the resin film 3 and the polarizing plate protective film 3 were produced.

"Production of Polarizing Plate Protective Film 4"

In the production of the polarizing plate protective film 1, the resin film 3 and the polarizing plate protective film 3 were produced in the same manner as in the production of the polarizing plate protective film 2 except that the main dope was changed as follows. In the microparticles, the amount of the additive liquid was adjusted so that the solid content was 1% by mass based on the cycloolefin resin (COP1).

(main concentrate)

Similarly to the production of the polarizing plate protective film 1, the resin film 4 and the polarizing plate protective film 4 were produced.

"Production of Polarizing Plate Protective Film 5"

In the production of the polarizing plate protective film 4, the amount of the main dope is changed so that the solid content of the fine particles is 5% by mass with respect to the cycloolefin resin COP1. Similarly to the production of the polarizing plate protective film 4, the resin film 5 and the polarizing plate protective film 5 were produced.

"Production of Polarizing Plate Protective Film 6"

In the production of the polarizing plate protective film 1, the resin film 6 and the polarizing plate protective film 6 were produced in the same manner as in the production of the polarizing plate protective film 1 except that the main dope was changed as follows.

(main concentrate)

"Manufacture of polarizing plate protective film 7~50"

In the production of the polarizing plate protective film 6, the type, the additive, and the amount of the cycloolefin resin contained in the main dope, the thickness of the resin layer, and the thickness of the hard coat layer and the type of the coating liquid are as follows. In the same manner as in the production of the polarizing plate protective film 6, the resin films 7 to 50 and the polarizing plate protective films 7 to 50 were produced in the same manner as in Table 2 and Table 3.

"Evaluation of polarizing plate protective film"

The following evaluations were performed on the produced resin films 1 to 50 and the polarizing plate protective films 1 to 50.

<Evaluation of elongation at break point>

The evaluation of the elongation at break was performed on a resin layer (resin film) having no hard coat layer.

The sample was cut to a width of 10 mm and a length of 130 mm in the direction orthogonal to the film transport direction (TD direction) and the transport direction (MD direction) under the conditions of 23 ° C and ‧55% RH according to the method described in JIS K 7127. The tensile test was carried out with a distance between the clamps of 100 mm and a tensile speed of 100 mm/min. In Tables 2 and 3, the average value of the values obtained in the TD direction and the MD direction was used. The elongation at break point was measured using an I & D (strand) TENSILON universal testing machine RTF series.

(Evaluation of surface hardness: determination of Martens hardness)

The measurement of the Martens hardness is performed on a resin layer (resin film) having no hard coat layer.

The A side (the outer air contact surface at the time of casting) and the B side (the contact surface of the stainless steel strip at the time of casting) of each of the resin films produced above were measured in accordance with the order of the test in accordance with ISO 14577. In a 23 ° C ‧55% RH environment, a micro-hardness tester (manufactured by FISHER INSTRUMENTS, trade name "FISHER SCOP 100C") was used as a tester, and a pyramid-shaped diamond whose base was square and had an opposite angle of 136° was used as a press. The pressure is measured.

The measurement was carried out by applying a load of 10 mN to the resin film at a constant speed. The Martens hardness is calculated by applying a load (10 mN) to the retardation film and dividing it by the value of the surface area of the invading pressure that exceeds the contact zero. The table shows the average of the values obtained for the A side and the B side.

(evaluation of bending)

As the evaluation of the bendability, a bending test of a resin film having no hard coat layer and a polarizing plate protective film having a hard coat layer was carried out. Further, the display unevenness in the liquid crystal display screen to which the polarizing plate protective film having the hard coat layer after the bending test was attached was visually evaluated.

(Bending test of resin film and polarizing plate protective film)

In the bending test, the MIT folding fatigue test (MIT-D, manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the short test piece in which the MD was in the longitudinal direction and the TD was in the width direction was fixed, and one end of the test piece was fixed, and the other end was bent back and forth. The test piece was measured for the number of times of bending until the test piece was broken. The setting conditions of this test are as follows. Further, at the time of the test, the number of bending of the test piece toward one side was one. The test was carried out twice, and the arithmetic mean of the results of the two tests was rounded off by the effective value of 2 digits as the measurement result of the folding resistance. Further, the upper limit of the measurement result of the bending property was set to 100,000 times.

(setting conditions)

Bending radius: R=0.38mm, load: 0.5kgf, test piece width: 1cm, distance between pinch and rotating shaft: 100mm, bending angle: 135°, bending speed: 175 times/min, number of tests: n=2

The evaluation is performed by adding the following evaluation levels.

◎: 100,000 bending times

○: The number of bending times is more than 50,000 times and less than 100,000 times.

△: The number of bending times is more than 10,000 times and less than 50,000 times.

×: The number of bending times is less than 10,000 times

(The display of the curved portion is uneven)

(Production of polarizing plate 1~50)

The polarizing plate was produced in a usual manner. After the corona discharge treatment of the polarizing plate protective film 1 to 50 having a hard coating layer for 10,000 bending tests, a completely saponified polyvinyl alcohol 5% aqueous solution was applied as an adhesive to one side of the polarizer. A retardation film (KC4KR-1, manufactured by KONICA MINOLTA Co., Ltd.) was attached to the other surface. At this time, the slow axis of the retardation film KC4KR-1 and the absorption axis of the polarizer are bonded to each other in such a manner as to be orthogonal to each other. Further, the corona discharge treatment was performed once using a corona treatment apparatus (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) under the conditions of an output of 0.3 kW and a treatment speed of 3 m/min.

<Production of Liquid Crystal Display Devices 1 to 50>

The polarizing plate on the visual recognition side of the commercially available IPS type liquid crystal display device was peeled off, and the polarizing plates 1 to 50 produced above were attached to the glass surface of the liquid crystal cell (IPS type) to fabricate a liquid crystal display device. At this time, the hard coat layer of the polarizing plate protective films 1 to 50 produced as described above becomes the display surface side. In the manner of the polarizing plate, the polarizing plate is cut out such that the absorption axis faces in the same direction as the polarizing plate to be bonded in advance.

(Inhomogeneous evaluation of liquid crystal display device)

With respect to the liquid crystal display devices 1 to 50 produced, the linear unevenness caused by the bending test was evaluated by the following evaluation reference function.

◎: No unevenness was observed at the bend

○: The line is unevenly seen at the bend

△: The line is unevenly seen in the bend

×: The bending test of 10,000 times was not satisfied, or the coarse linear unevenness table 2 and Table 3 were clearly observed to show the above results.

From the above results, it is understood that the polarizing plate protective film which satisfies the requirements of the present invention is excellent in flexibility.

Claims (6)

A polarizing plate protective film comprising a polarizing plate protective film containing a resin layer containing a cycloolefin resin as a main component, wherein the resin layer contains at least a benzotriazole-based or triazine-based ultraviolet absorber, or contains The polyester-based additive having the structure represented by the following formula (1) is adjusted so that the elongation at break of the tensile test of the resin layer measured in an environment of 23 ° C ‧55% RH is in the range of 6 to 20%. And the surface of the resin layer has a Martens hardness of 145 to 160 N/mm ² , and the formula (1): B-(GA) _n -GB (wherein B represents a hydroxyl group derived from a ring-containing structure) a group derived from a monocarboxylic acid, G represents an alkanediol having 2 to 12 carbon atoms, a cycloalkanediol having 6 to 12 carbon atoms, an oxyalkylene glycol having 4 to 12 carbon atoms, and a carbon atom. a group derived from a group of 6 to 12 aromatic diols, and A represents a free dialkyl dicarboxylic acid having 4 to 12 carbon atoms, a cycloalkanedicarboxylic acid having 6 to 12 carbon atoms, and a carbon number. A group derived from a compound selected from the group consisting of 8 to 16 aromatic dicarboxylic acids, and n represents an integer of 0 or more). The polarizing plate protective film of claim 1, wherein the resin layer has a hard coat layer having a thickness of from 1 to 8 μm. The polarizing plate protective film of claim 1, wherein the resin layer contains a benzotriazole-based or triazine-based ultraviolet absorber in an amount of at least 0.5 to 5% by mass based on the cycloolefin-based resin, or a cycloolefin The resin contains a polyester-based additive having a structure represented by the following general formula (1) in a range of from 1 to 10% by mass: general formula (1): B-(GA) _{n -} GB (wherein B represents a self-containing ring) a group derived from a hydroxyl group-containing monocarboxylic acid, wherein G represents an alkanediol having 2 to 12 carbon atoms, a cycloalkanediol having 6 to 12 carbon atoms, and an alkylene oxide having 4 to 12 carbon atoms. a group derived from a group of alcohols and an aromatic diol having 6 to 12 carbon atoms, and A represents a free dialkyl dicarboxylic acid having 4 to 12 carbon atoms and a cycloalkaned dicarboxylic acid having 6 to 12 carbon atoms. And a group derived from a compound selected from the group consisting of 8 to 16 carbon atoms having an aromatic dicarboxylic acid, and n is an integer of 0 or more). The polarizing plate protective film of claim 1, wherein the thickness of the resin layer is in the range of 20 to 40 μm. A polarizing plate comprising a polarizing plate protective film according to any one of claims 1 to 4 on one side of the polarizer, and a retardation film on the other side of the polarizer. A method for producing a polarizing plate protective film, which is characterized in that a method for producing a polarizing plate protective film having a resin layer containing a cycloolefin resin as a main component and a hard coat layer is produced, and is subjected to the following steps: The cycloolefin resin contains a benzotriazole-based or triazine-based ultraviolet absorber in an amount of at least 0.5 to 5% by mass, or contains the following formula in the range of 1 to 10% by mass based on the cycloolefin-based resin. (1) A polyester-based additive having a structure and a solution containing a cycloolefin-based resin cast on a substrate to form the above-mentioned resin layer, and the general formula (1): B-(GA) _n -GB (wherein B It represents a group derived from a hydroxyl group-containing monocarboxylic acid having a ring structure, and G represents an alkanediol having 2 to 12 carbon atoms, a cycloalkanediol having 6 to 12 carbon atoms, and a carbon number of 4 to 12; a group derived from a group selected from the group consisting of an oxyalkylene glycol and an aromatic diol having 6 to 12 carbon atoms, and A represents an alkanedicarboxylic acid having a free carbon number of 4 to 12 and a ring of 6 to 12 carbon atoms. a group derived from a group selected from the group consisting of an alkanedicarboxylic acid and an aromatic dicarboxylic acid having 8 to 16 carbon atoms, and n represents 0. The above integer).