JP2011033798A - Polarizing plate, method for manufacturing the same, and liquid crystal display device using the polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate in which the adhesive force is improved and the change with time in the polarization degree is suppressed by improving an adhesive technique for adhering a polarizing film and a protection film, that causes a problem in the case when a film formed from a material containing polylactic acid is used as the protective film for a polarizing plate, and to provide a method of manufacturing the same. <P>SOLUTION: In the polarizing plate, a protection film formed from a material containing polylactic acid is laminated at least on one surface of a polarizing film through an adhesive layer, wherein, the adhesive layer is formed by curing a specified radiation curable composition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polarizing plate used for a liquid crystal display device and the like, a method for producing the same, and a liquid crystal display device using the same.

  Liquid crystal display devices are widely used as display devices such as televisions, personal computer monitors, and portable information terminals. Normally, a polarizing plate is used in a liquid crystal display device, because a general liquid crystal display device uses polarized light. The polarizing plate is used as a polarization conversion element for converting natural polarized light of a light source into linearly polarized light, and for converting polarization information controlled by a liquid crystal cell or the like into transmittance information.

  There are various proposals for this polarizing plate, but the most commonly used polarizing plate has a structure in which a polarizing film that performs polarization conversion is sandwiched between two protective films. . As the polarizing film, a film in which a dichroic dye is present in an oriented state mainly in a stretched polyvinyl alcohol film is preferably used. On the other hand, the protective film is used because the polarizing film alone cannot satisfy the characteristics such as the dimensional stability in the heat resistance and wet heat resistance tests, the light resistance, and the wear resistance.

  Although several proposals have been made as protective films, triacetyl cellulose (hereinafter sometimes abbreviated as “TAC”) films are most widely used. Recently, an example in which a protective film also serves as a retardation film which is a kind of polarization conversion element has been proposed and put into practical use.

  TAC is a semi-synthetic resin, and it can be said that it is an environmentally-friendly material in that it uses plant-derived raw materials, although it is partially related to the resin. However, due to the physical properties of the polymer, it is necessary to use the solution casting method as a film manufacturing method, and since a large amount of halogen solvent is used at the time of manufacturing, the environmental load is large, and the film is a truly environmentally friendly material. Is hard to say.

  Polylactic acid not only has the potential to replace petroleum-based resins as plant-derived materials, but is also suitable as an environmentally friendly material because it can be formed into a film by melt extrusion without using a solvent. In addition, it is characterized by optical properties such as possessing high transparency in spite of being crystalline, and it is expected to develop applications that make use of it. In fact, various proposals have been made to use polylactic acid as a protective film for a polarizing plate (see, for example, Patent Documents 1, 2, and 3).

  However, polylactic acid has not been put into practical use as a protective film for polarizing plates at present. One of the major technical problems is considered to be an adhesive technique between the protective film and the polarizing film.

  First, while polylactic acid film is oleophilic, polyvinyl alcohol, which mainly forms the polarizing film, is hydrophilic, it is very difficult to strongly bond them together, including suppression of changes over time. is there.

  In the above-mentioned TAC film, the surface is saponified with an aqueous alkali solution such as an aqueous sodium hydroxide solution to increase the hydrophilicity by converting the acetyl group to a hydroxyl group, and the polarizing film and the protective film are made into an aqueous solvent such as an aqueous polyvinyl alcohol solution. A technique for securing adhesive strength by bonding and drying with a system adhesive is used. Although this method provides high adhesive strength, problems such as alkaline waste liquid treatment and the use of an adhesive with water as a solvent increase the length of the polarizing plate, leading to an increase in equipment size or production speed. In addition, there is a problem that the polarization degree is easily deteriorated due to the problem that the polarizing film is in contact with water for a long time.

  Since the water vapor permeability in TAC is higher than that in polylactic acid, even when an adhesive using water as a solvent is used in the bonding process of the polarizing film and the protective film, the water penetrates and evaporates from the TAC film. It is applicable although there are problems.

  However, since polylactic acid has a water vapor permeability smaller than that of TAC, a longer drying length is required or a production rate is required when an adhesion process using an aqueous adhesive such as polyvinyl alcohol aqueous solution is used. In some cases, problems such as deterioration of polarization degree become more conspicuous.

JP 2002-82223 A JP 2001-337201 A JP 2004-252263 A

An object of the present invention is to improve the adhesion technique between a polarizing film and a protective film, which is a problem when a film made of a material containing polylactic acid is used as a protective film for a polarizing plate, to improve the adhesive force, and to increase the degree of polarization over time. An object of the present invention is to provide a polarizing plate in which changes are suppressed.
Another object of the present invention is to provide a method for producing the polarizing plate.
Still another object of the present invention is to provide a liquid crystal display device using the polarizing plate.

  In view of the prior art, the inventor of the present invention has reached the present invention as a result of intensive studies on the composition of the adhesive.

（式（１）中、ｎは１または２を表し、Ｒ^２０は水素原子またはメチル基を表し、Ｒ^２１は炭素原子数１〜１０のアルキレン基（該アルキレン基中に存在する１個または２個以上のメチレン基は、酸素原子が相互に直接結合しないものとして、それぞれ独立に酸素原子、−ＣＯ−、−ＣＯＯ−又は−ＯＣＯ−で置換されていても良く、該アルキレン基中に存在する１個又は２個以上の水素原子はそれぞれ水酸基、カルボキシル基、イソシアネート基、アルデヒド基、リン酸基で置換されている。）を表す。） That is, the object of the present invention is to
A polarizing plate in which a protective film made of a material containing polylactic acid is laminated on at least one surface of a polarizing film via an adhesive layer, and the adhesive layer cures a radiation curable composition containing the following formula (1) It is achieved by a polarizing plate characterized by being made.

(In the formula (1), n represents 1 or 2, R ²⁰ represents a hydrogen atom or a methyl group, and R ²¹ represents an alkylene group having 1 to 10 carbon atoms (1 or 2 present in the alkylene group). One or more methylene groups may be each independently substituted with an oxygen atom, —CO—, —COO— or —OCO—, as oxygen atoms are not directly bonded to each other, and are present in the alkylene group. 1 or 2 or more hydrogen atoms are each substituted with a hydroxyl group, a carboxyl group, an isocyanate group, an aldehyde group, or a phosphate group.)

３．ポリ乳酸を含む材料が、ポリ乳酸を４０重量％以上含有する、上記の偏光板。
４．ポリ乳酸を含む材料が、ポリメタクリル酸メチルを５０重量％以下含有する、上記の偏光板。
５．接着剤層に光開始剤が含まれる、上記の偏光板。
６．光開始剤が波長３８０ｎｍ以上の光により重合反応開始可能な剤である、上記の偏光板。
７．偏光膜に貼り合わせた保護フィルムに紫外線吸収剤を含む、上記の偏光板。
８．放射線硬化型組成物が下記式（３）で表される、請求項１〜８のいずれか記載の偏光板。

（式（３）中、Ｒ^２２は水素原子またはメチル基を表し、Ｒ^２３は炭素原子数２〜５のアルキレン基（該アルキレン基中に存在する１個のメチレン基は、−ＯＣＯ−で置換されていても良く、該アルキレン基中に存在する１個の水素原子はそれぞれ水酸基、カルボキシル基、イソシアネート基、リン酸基で置換されている。）を表す。） The present invention also includes the following.
1. The above polarizing plate, wherein the polylactic acid is a polylactic acid composed of a poly-D-lactic acid component and a poly-L-lactic acid component, and has a stereocomplex crystallinity (S) of 90% or more.
{Stereocomplex crystallinity (S) is 190 ° C measured by differential scanning calorimetry (DSC)
The polylactic acid homocrystal melting heat (ΔHmh) observed below and the polylactic acid stereocomplex crystal melting heat (ΔHmsc) observed at 190 ° C. or higher were obtained by the following formula (i).
(S) = [ΔHmsc / (ΔHmh + ΔHmsc)] × 100 (i)}
2. Said polarizing plate whose bulk average density | concentration of the terminal group represented by following formula (2) of polylactic acid is lower than the terminal group density | concentration in the vicinity of the adhesion interface by the side of a polarizing film.

3. The polarizing plate described above, wherein the material containing polylactic acid contains 40% by weight or more of polylactic acid.
4). The polarizing plate as described above, wherein the material containing polylactic acid contains 50% by weight or less of polymethyl methacrylate.
5). The polarizing plate as described above, wherein the adhesive layer contains a photoinitiator.
6). The above polarizing plate, wherein the photoinitiator is an agent capable of initiating a polymerization reaction with light having a wavelength of 380 nm or longer.
7). The polarizing plate described above, wherein the protective film bonded to the polarizing film contains an ultraviolet absorber.
8). The polarizing plate according to claim 1, wherein the radiation curable composition is represented by the following formula (3).

(In the formula (3), R ²² represents a hydrogen atom or a methyl group, R ²³ represents an alkylene group having 2 to 5 carbon atoms (one methylene group present in the alkylene group is substituted with —OCO—). And each hydrogen atom present in the alkylene group is substituted with a hydroxyl group, a carboxyl group, an isocyanate group, or a phosphoric acid group.)

（式（１）中、ｎは１または２を表し、Ｒ^２０は水素原子またはメチル基を表し、Ｒ^２１は炭素原子数１〜１０のアルキレン基（該アルキレン基中に存在する１個または２個以上のメチレン基は、酸素原子が相互に直接結合しないものとして、それぞれ独立に酸素原子、−ＣＯ−、−ＣＯＯ−又は−ＯＣＯ−で置換されていても良く、該アルキレン基中に存在する１個又は２個以上の水素原子はそれぞれ水酸基、カルボキシル基、イソシアネート基、アルデヒド基、リン酸基で置換されている。）を表す。） Another object of the present invention is to
A protective film made of a material containing polylactic acid and a polarizing film are formed in advance and bonded together with a radiation curable composition containing the following formula (1) interposed therebetween, and substantially no light having a wavelength of 270 nm or less is irradiated. Thus, the radiation curable composition is cured by the polarizing plate manufacturing method.

(In the formula (1), n represents 1 or 2, R ²⁰ represents a hydrogen atom or a methyl group, and R ²¹ represents an alkylene group having 1 to 10 carbon atoms (1 or 2 present in the alkylene group). One or more methylene groups may be each independently substituted with an oxygen atom, —CO—, —COO— or —OCO—, as oxygen atoms are not directly bonded to each other, and are present in the alkylene group. 1 or 2 or more hydrogen atoms are each substituted with a hydroxyl group, a carboxyl group, an isocyanate group, an aldehyde group, or a phosphate group.)

Still another object of the present invention is to
This can be achieved by a liquid crystal display device using the polarizing plate described above.

According to the present invention, when polylactic acid having a low environmental load is used as a material for a protective film of a polarizing plate, the adhesive strength between the polarizing film and the protective film is improved, and a polarizing plate with little deterioration in polarization degree is provided. Is possible. Furthermore, it is possible to improve productivity in manufacturing the polarizing plate and reduce the environmental load.
When the polarizing plate of the present invention is used in a liquid crystal display device, it is possible to realize a liquid crystal display device in which the change in contrast with time is small and the polarizing plate is not peeled off.

It is a schematic diagram which shows one aspect | mode of the polarizing plate layer structure in this invention. It is a schematic diagram which shows one aspect | mode of the polarizing plate layer structure in this invention. It is a schematic diagram which shows one aspect | mode of the polarizing plate layer structure in this invention. It is a schematic diagram which shows one aspect | mode of the liquid crystal display device structure in this invention.

Hereinafter, the present invention will be described in detail.
<Configuration of polarizing plate and liquid crystal display device>
First, the structure of a polarizing plate and a liquid crystal display device will be described with reference to the drawings. 1 to 3 are schematic views showing one embodiment of the polarizing plate of the present invention.
In FIG. 1, 1 and 3 are protective films containing polylactic acid, 2 is an adhesive layer, 3 is a polarizing layer, and 6 is a polarizing plate.
In FIG. 2, 21 is a protective film containing polylactic acid, 25 is a protective film not containing polylactic acid, 23 is a polarizing layer, 22 and 24 are adhesive layers, and 26 is a polarizing plate. As the protective film 25, a known protective film containing no polylactic acid can be used. As the material, triacetyl cellulose, polycarbonate, copolymer polycarbonate having a fluorene skeleton, polyester, polysulfone, polyethersulfone, cycloolefin polymer, polypropylene, polystyrene, maleic acid-modified polystyrene, acrylic resin and the like are preferable. A known adhesive can be used for the adhesive layer 24 of the protective film and polarizing film made of these materials. For example, when TAC is used as the protective film material, an aqueous polyvinyl alcohol solution can be used as the adhesive after the surface is saponified.

In FIG. 3, 31 is a protective film containing polylactic acid, 2 is an adhesive layer, 33 is a polarizing layer, and 34 is a polarizing plate.
FIG. 4 is a schematic view showing an embodiment of the liquid crystal display device of the present invention. In the figure, 41 and 45 are polarizing plates, 42 and 44 are adhesive layers, and 43 is a liquid crystal cell.
When the polarizing plate having the configuration shown in FIG. 3 is used, it is preferable that the protective film side of the liquid crystal display device shown in FIG. This is because when the protective film is on the inner side, the polarizing layer is exposed and the polarizing layer is significantly deteriorated.

<Characteristics and functions of protective film>
Next, the characteristics and functions of the protective film will be described.
The protective film is installed for the purpose of compensating for the shortage of optical properties and mechanical properties of the polarizing film.
In the polarizing plate shown in FIGS. 1 to 3, as can be understood from the configuration of the liquid crystal display device of FIG. May be installed on the side. The required optical properties differ depending on the two cases.

When the protective film is installed on the liquid crystal cell side with the polarizing film as the center, it may or may not have a retardation plate function.
When the protective film has a retardation function, the protective film may be molecularly oriented by stretching or the like to develop birefringence and then be used as a retardation plate. Moreover, you may use what applied liquid crystal etc. on the optically substantially isotropic protective film, and expressed the phase difference. Further, both the retardation characteristics of the protective film and the coating film such as liquid crystal thereon may have a retardation, and a target retardation value may be expressed by a combination of both. As a coating film on a protective film having a retardation function, a discotic type radiation curable liquid crystal is applied, oriented, and cured by radiation, or a polymer liquid crystal or polyimide is coated on the protective film by a known method. What was formed in can be used.

  Although the necessary phase difference characteristic varies depending on the mode of the liquid crystal, the optimum phase difference value is determined from known knowledge. As the liquid crystal mode, known ones such as a vertical alignment mode, an in-plane switching mode, a twist nematic mode, a super twist nematic mode, and a bend mode can be used.

The protective film having no retardation function is preferably optically isotropic. The in-plane retardation (Re) and thickness direction retardation (Rth) of the protective film are defined by the following formulas (4) and (5), respectively.
Re = (nx−ny) × d (4)
Rth = ((nx + ny) / 2−nz) × d (5)

  nx represents the maximum refractive index in the film plane. ny represents the refractive index in the direction perpendicular to the nx direction in the plane. nz represents the refractive index in the thickness direction. d represents thickness (nm). Re is preferably 10 nm or less, more preferably 7 nm or less, and even more preferably 5 nm or less.

  Rth is preferably 50 nm or less, more preferably 40 nm or less, and most preferably 30 nm or less. When Re is larger than 10 nm or Rth is larger than 50 nm, the protective film may be difficult to function as an optical isotropic member, which may make it difficult to design a liquid crystal display device. In addition, the measurement of the phase difference in the present invention is performed using light having a wavelength of 550 nm unless otherwise specified.

When the protective film is installed on the liquid crystal cell side centering on the polarizing film, the haze is preferably 1% or less, more preferably 0.7% or less, and most preferably 0.5% or less. is there. If the haze is 1% or more, the polarization performance of the polarizing plate, particularly the degree of polarization, decreases due to depolarization, and the contrast of the liquid crystal display device may be decreased. The absolute value of the photoelastic coefficient of the protective film material is preferably less than 10 × 10 ⁻¹² / Pa, more preferably less than 8 × 10 ⁻¹² / Pa, and even more preferably less than 5 × 10 ⁻¹² / Pa, particularly Preferably, it is less than 3 × 10 ⁻¹² / Pa. When the photoelastic coefficient is 10 × 10 ⁻¹² / Pa or more, a change in phase difference is observed due to stress, and as a result, the transmittance of the liquid crystal display device may become uneven and the display quality may be deteriorated.

  When the protective film is installed outside the liquid crystal cell with respect to the polarizing film, the protective film is not involved in the polarization state control used to control the image of the liquid crystal display device. A phase difference function is not required. However, if the phase difference is large, interference may occur, and it is preferable that the phase difference is small. Re is preferably 100 nm or less, more preferably 50 nm or less. The haze is preferably 2% or less, more preferably 1% or less.

  The thickness of the protective film is preferably 5 to 300 μm regardless of the position, and is preferably thicker from the viewpoint of ease of wrinkling during handling (wrinkle prevention), more preferably 10 μm or more, More preferably, it is 20 micrometers or more, and 30 micrometers or more are especially preferable.

  Further, from the viewpoint of transparency, the thinner is advantageous, more preferably 200 μm or less, further preferably 150 μm or less, and particularly preferably 100 μm or less. Moreover, it is preferable that it is transparent with visible light.

  It is preferable that the protective film does not absorb visible light regardless of the position. On the other hand, it is preferable to absorb ultraviolet rays for protecting the polarizing film and the liquid crystal layer. In particular, when the protective film is installed outside the liquid crystal cell with respect to the polarizing film, it is preferable to add an ultraviolet absorber. However, when the protective film is installed inside the liquid crystal cell, there is no ultraviolet absorber. May be. As the ultraviolet absorber, known ones described later are used. Specifically, the light transmittance at a wavelength of 380 nm of the protective film is preferably 20% or less, the light transmittance at a wavelength of 375 nm is 1% or less, and the light transmittance at a wavelength of 500 nm is preferably 80% or more.

<Material of protective film>
The protective film in the polarizing plate of the present invention is at least one made of a material containing polylactic acid. Polylactic acid consists of a poly D-lactic acid component and / or a poly L-lactic acid component. The polylactic acid component in the protective film needs to be 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 70% by weight or more, and most preferably 75% by weight or more. It is. If the polylactic acid is less than 40% by weight, crystallization of the polylactic acid is difficult to occur, which may cause a problem in heat resistance. When a resin other than polylactic acid is contained, a thermoplastic resin is preferable from the viewpoint of film moldability.

  Examples of thermoplastic resins other than polylactic acid include polyester resins other than polylactic acid resins, polyamide resins, polyacetal resins, polyolefin resins such as polyethylene resins and polypropylene resins, polystyrene resins, acrylic resins, polyurethane resins, chlorinated polyethylene resins, Chlorinated polypropylene resin, aromatic and aliphatic polyketone resin, fluorine resin, polyphenylene sulfide resin, polyetherketone resin, polyimide resin, thermoplastic starch resin, AS resin, ABS resin, AES resin, ACS resin, polyvinyl chloride Resin, polyvinylidene chloride resin, vinyl ester resin, MS resin, polycarbonate resin, polyarylate resin, polysulfone resin, polyethersulfone resin, phenoxy resin, polyphenylene oxa De resins, poly-4-methylpentene-1, polyetherimide resin, and thermoplastic resins such as polyvinyl alcohol resins. Particularly preferred is polymethyl methacrylate from the viewpoint of good compatibility with polylactic acid and a close refractive index. The content of polymethyl methacrylate in the protective film is preferably 50% by weight or less, more preferably 40% by weight or less, and still more preferably 30% by weight or less. When polymethyl methacrylate is more than 50% by weight, it is difficult to crystallize polylactic acid, which may cause problems in heat resistance and the like.

Also particularly preferred as polylactic acid is stereocomplex polylactic acid. The stereocomplex polylactic acid is composed of a poly-D-lactic acid component and a poly-L-lactic acid component and has a stereocomplex crystal, and the stereocrystallization degree represented by the following formula (i) is 90% or more. It is preferable.
{Stereocomplex crystallinity (S) is 190 ° C measured by differential scanning calorimetry (DSC)
The polylactic acid homocrystal melting heat (ΔHmh) observed below and the polylactic acid stereocomplex crystal melting heat (ΔHmsc) observed at 190 ° C. or higher were obtained by the following formula (i).
(S) = [ΔHmsc / (ΔHmh + ΔHmsc)] × 100 (i)}

  Polylactic acid having a stereocomplex crystal is known to have higher transparency and heat resistance than ordinary polylactic acid (poly L lactic acid alone or poly D lactic acid alone). preferable. The stereocomplex crystallinity (S) is preferably in the range of 93% to 100%, more preferably 95% to 100%. Particularly preferably, the stereocomplex crystallinity (S) is 100%.

  Furthermore, in the present invention, the polylactic acid preferably has crystallinity, and the stereocomplex crystallization rate (Sc) defined by the formula (ii) is determined by the intensity ratio of diffraction peaks by wide-angle X-ray diffraction (XRD) measurement. ) Is more preferably 50% or more. A range of preferably 50 to 100%, more preferably 70 to 100%, particularly preferably 90 to 100% is selected.

That is, when the polylactic acid has the Sc, the transparency, heat resistance, and heat and humidity resistance of the protective film can be more suitably satisfied. In particular, regarding transparency, it is possible to significantly reduce haze as compared with polylactic acid not having a stereocomplex crystal, and it is more suitable as a material for a protective film. Further, even if the surface treatment described later is performed, the crystal structure prevents the entire bulk from being embrittled, and the preferred functional group is easily developed only on the surface.
Sc (%) = [ΣI _SCi / (ΣI _SCi + I _HM )] × 100 (ii)
[Where ΣI _SCi = I _SC1 + I _SC2 + I _SC3 and I _SCi (i = 1 to 3) are integrated intensities of diffraction peaks around 2θ = 12.0 °, 20.7 °, and 24.0 °, respectively. I _HM represents the integrated intensity I _HM of a diffraction peak derived from a homocrystal appearing in the vicinity of 2θ = 16.5 °. ]

  Further, from the same viewpoint, in the present invention, the crystallization rate of polylactic acid homocrystal, particularly the crystallization rate by XRD measurement, is at least 5%, preferably 5 to 60%, more preferably 7 to 50%, and still more preferably 10%. A range of 45% is selected.

  Further, the melting point of the polylactic acid stereocomplex crystal is suitably selected in the range of 190 to 250 ° C., more preferably 200 to 230 ° C., and the crystal melting enthalpy by DSC measurement is 20 J / g or more, preferably 20 to 80 J / g, More preferably, a range of 30 to 80 J / g is selected.

  If the melting point of the polylactic acid stereocomplex crystal is less than 190 ° C., the significance of stereocomplex crystal formation will be small. Furthermore, when it exceeds 250 ° C., when forming the protective film used in the present invention, it is necessary to form the film at a high temperature of 250 ° C. or higher, and it may be difficult to suppress thermal decomposition of the resin. It is. The same argument applies to the value of crystal melting enthalpy.

  In order to suitably satisfy the stereocomplex crystallinity, stereocomplex crystallization rate, and various crystallinity parameters described above, the weight ratio of poly (D-lactic acid) component to poly (L-lactic acid) component is 90/10. To 10/90.

  More preferably, it is in the range of 80/20 to 20/80, more preferably 30/70 to 70/30, particularly preferably 40/60 to 60/40, and theoretically preferably as close to 1/1 as possible. Selected.

  The polylactic acid preferably contains a compound having a specific functional group as a heat and humidity resistance improver. As the moisture and heat resistance improver, those that mainly function as a carboxyl end group blocking agent are preferable, and examples thereof include carbodiimide compounds, aromatic carbodiimide compounds, epoxy compounds, and oxazoline compounds, but in terms of effects, carbodiimide compounds are preferred. is there. The amount is preferably in the range of 0.001 to 5 parts by weight per 100 parts by weight of polylactic acid. If the amount is less than 0.001 part by weight, the function as a carboxyl group sealing agent is insufficient. Further, if it is applied in a large amount beyond this range, it is not preferred because the concern of deterioration of the resin hue or plasticization due to undesirable side reactions such as decomposition of the agent itself is increased.

  The carbodiimide compound is a compound having at least one carbodiimide functional group in the molecule, and examples thereof include the following compounds. In particular, carbodiimide compounds can be end-capped and polymer chain extended by the reaction of the terminal carboxyl group and the carbodiimide group, even if a terminal double bond and a terminal carboxyl group are generated by the mechanism of the following formula (6). The adhesion between the polarizing film and the protective film can be improved while preventing embrittlement.

  Specific examples of carbodiimide compounds include dicyclohexyl carbodiimide, diisopropyl carbodiimide, diisobutyl carbodiimide, dioctyl carbodiimide, octyl decyl carbodiimide, di-tert-butyl carbodiimide, dibenzyl carbodiimide, N-octadecyl-N'-phenyl carbodiimide, N-benzyl -N'-phenylcarbodiimide, N-benzyl-N'-tolylcarbodiimide, N-tolyl-N'-cyclohexylcarbosiimide, p-phenylenebis (cyclohexylcarbodiimide), hexamethylenebis (cyclohexylcarbodiimide), ethylenebis (phenylcarbodiimide) ), Ethylenebis (cyclohexylcarbodiimide), and other mono- or polycarbodiimide compounds It is.

Examples of the aromatic carbodiimide compound include the following compounds.
For example, diphenylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, bis (p-aminophenyl) carbodiimide, bis (p-chlorophenyl) carbodiimide, bis (o-chlorophenyl) carbodiimide, bis (o-ethylphenyl) Carbodiimide, bis (p-ethylphenyl) carbodiimide bis (o-isopropylphenyl) carbodiimide, bis (p-isopropylphenyl) carbodiimide, bis (o-isobutylphenyl) carbodiimide, bis (p-isobutylphenyl) carbodiimide, bis (2, 5-dichlorophenyl) carbodiimide, bis (2,6-dimethylphenyl) carbodiimide, bis (2,6-diethylphenyl) carbodiimide, bis (2-ethyl-6-isopropyl) Ruphenyl) carbodiimide, bis (2-butyl-6-isopropylphenyl) carbodiimide, bis (2,6-diisopropylphenyl) carbodiimide, bis (2,6-di-tert-butylphenyl) carbodiimide, bis (2,4,6 -Trimethylphenyl) carbodiimide, bis (2,4,6-triisopropylphenyl) carbodiimide, bis (2,4,6-tributylphenyl) carbodiimide, diβ-naphthylcarbosiimide, N-tolyl-N'-phenylcarbosi Examples include mono- or polycarbodiimide compounds such as imide, p-phenylenebis (o-toluylcarbodiimide), p-phenylenenebis (p-chlorophenylcarbodiimide), 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide .

  Of these, industrially available dicyclohexylcarbodiimide and bis (2,6-diisopropylphenyl) carbodiimide can also be suitably used. Commercially available polycarbodiimide compounds have the advantage of being usable without the need for synthesis. As such a commercially available polycarbodiimide compound, for example, “Carbodilite” LA-1 sold by Nisshinbo Co., Ltd. under the trade name “Carbodilite”, or HMV-8CA, aqueous type “Carbodilite” V-02, V- 02-L2, V-04, E-01, E-02, E-03A, E-04, and Rhein Chemie Japan Co., Ltd., sold under the trade name "STABAXOL" "I", "Stabuxol" P, "Stavaxol" P-100 and the like are preferably exemplified.

  The carbodiimide compound is particularly preferably a carbodiimide having a cyclic structure, and is preferably used because it does not release harmful gases such as isocyanate when the resin is melted. Furthermore, the cyclic carbodiimide is advantageous in the following points as compared with the chain carbodiimide. In other words, when the cyclic carbodiimide reacts with the carboxyl end group of polylactic acid, it is incorporated into the end of the polymer chain, and then the end becomes an isocyanate group, so that the low molecular weight isocyanate compound is not liberated. Further, this isocyanate group enables the extension of the polymer chain. In order to improve the adhesion between the polarizing film and the protective film, a surface treatment described later may be performed, but the presence of this compound can further suppress the embrittlement of the entire bulk.

  Here, the carbodiimide having a cyclic structure has one carbodiimide group (-N = C = N-) and a structure in which the first nitrogen and the second nitrogen are bonded by a bonding group. . When the compound has a plurality of cyclic structures, one ring has only one carbodiimide group. The number of atoms in the cyclic structure is preferably 8 to 50, more preferably 10 to 30, and still more preferably 10 to 20.

  Here, the number of atoms in the ring structure means the number of atoms that directly constitute the ring structure, and is, for example, 8 for an 8-membered ring and 50 for a 50-membered ring. This is because if the number of atoms in the cyclic structure is smaller than 8, the stability of the cyclic carbodiimide compound is lowered, and it may be difficult to store and use. From the viewpoint of reactivity, there is no particular restriction on the upper limit of the number of ring members, but cyclic carbodiimide compounds having more than 50 atoms are difficult to synthesize, and the cost may increase significantly. From this viewpoint, the number of atoms in the cyclic structure is preferably selected in the range of 10-30, more preferably 10-20.

The cyclic structure is preferably a structure represented by the following formula (10).

  In the formula, Q is a divalent to tetravalent linking group that is an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof, each of which may contain a hetero atom and a substituent. A heteroatom in this case refers to O, N, S, P. Two of the valences of this linking group are used to form a cyclic structure. When Q is a trivalent or tetravalent linking group, it is bonded to a polymer or other cyclic structure via a single bond, a double bond, an atom, or an atomic group.

  The linking group may include a heteroatom and a substituent, each having a divalent to tetravalent carbon number of 1 to 20 aliphatic group, a divalent to tetravalent carbon number of 3 to 20 alicyclic group, A linking group which is a tetravalent aromatic group having 5 to 15 carbon atoms or a combination thereof and has a necessary number of carbon atoms to form the cyclic structure defined above is selected. Examples of combinations include structures such as an alkylene-arylene group in which an alkylene group and an arylene group are bonded.

式中、Ａｒ^１およびＡｒ^２は各々独立に、それぞれヘテロ原子ならびに置換基を含んでいてもよい、２〜４価の炭素数５〜１５の芳香族基である。 The linking group (Q) is preferably a divalent to tetravalent linking group represented by the following formula (10-1), (10-2) or (10-3).

In the formula, Ar ¹ and Ar ² are each independently a 2- to 4-valent aromatic group having 5 to 15 carbon atoms which may contain a hetero atom and a substituent.

  As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group (divalent) include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

R ¹ and R ² each independently contain a heteroatom and a substituent, each having 2 to 4 valent aliphatic groups having 1 to 20 carbon atoms and 2 to 4 valent fatty acids having 3 to 20 carbon atoms A cyclic group, and a combination thereof, or a combination of the aliphatic group, the alicyclic group, and a divalent to tetravalent aromatic group having 5 to 15 carbon atoms.

  Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. As the alkanetriyl group, methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group, Examples include a hexadecantriyl group. As alkanetetrayl group, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like. These aliphatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group. As cycloalkanetriyl group, cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group Group, cyclododecane triyl group, cyclohexadecane triyl group and the like. As cycloalkanetetrayl group, cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Yl group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

X ¹ and X ² each independently contain a heteroatom and a substituent, each having a 2 to 4 valent aliphatic group having 1 to 20 carbon atoms and a 2 to 4 valent fatty acid having 3 to 20 carbon atoms It is a cyclic group, a divalent to tetravalent aromatic group having 5 to 15 carbon atoms, or a combination thereof.

  Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. As the alkanetriyl group, methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group, Examples include a hexadecantriyl group. As alkanetetrayl group, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like. These aliphatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group. As the alkanetriyl group, cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like. As the alkanetetrayl group, cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

In the formulas (10-1) and (10-2), s and k are integers of 0 to 10, preferably 0 to 3, and more preferably 0 to 1. If s and k exceed 10, the cyclic carbodiimide compound becomes difficult to synthesize, and the cost may increase significantly. From this viewpoint, the integer is preferably selected in the range of 0 to 3. When s or k is 2 or more, X ¹ or X ² as a repeating unit may be different from other X ¹ or X ² .

X ³ is a divalent to tetravalent C 1-20 aliphatic group, a divalent to tetravalent C 3-20 alicyclic group, each of which may contain a heteroatom and a substituent, A tetravalent aromatic group having 5 to 15 carbon atoms, or a combination thereof.

  Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. As the alkanetriyl group, methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group, Examples include a hexadecantriyl group. As alkanetetrayl group, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like. These aliphatic groups may contain a substituent, such as an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, or an ester group. , Ether group, aldehyde group and the like.

  Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group. As the alkanetriyl group, cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like. As the alkanetetrayl group, cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may contain a substituent, such as an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, and an ester. Group, ether group, aldehyde group and the like.

  As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ may contain a hetero atom, and when Q is a divalent linking group, Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ are all divalent groups. When Q is a trivalent linking group, one of Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ is a trivalent group. When Q is a tetravalent linking group, one of Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ is a tetravalent group, or two are trivalent It is a group.

式中、Ｑｃは、脂肪族基、脂環族基、芳香族基またはこれらの組み合わせである４価の結合基であり、ヘテロ原子を保有していてもよい。Ｚ^１およびＺ^２は、環状構造を担持する担体である。Ｚ^１およびＺ^２は、互いに結合して環状構造を形成していてもよい。 As the cyclic carbodiimide used in the present invention, a compound represented by the following formula (14) is more preferable.

In the formula, Qc is a tetravalent linking group which is an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof, and may have a hetero atom. Z ¹ and Z ² are carriers that support a cyclic structure. Z ¹ and Z ² may be bonded to each other to form a cyclic structure.

  The aliphatic group, alicyclic group, and aromatic group are the same as those described in Formula (1). However, in the compound of the formula (14), Qc is tetravalent. Accordingly, one of these groups is a tetravalent group or two are trivalent groups. Qc is preferably a tetravalent linking group represented by the following formula (14-1), (14-2) or (14-3).

Ａｒｃ^１、Ａｒｃ^２、Ｒｃ^１、Ｒｃ^２、Ｘｃ^１、Ｘｃ^２、Ｘｃ^３、ｓおよびｋは、各々式（１０−１）〜（１０−３）の、Ａｒ^１、Ａｒ^２、Ｒ^１、Ｒ^２、Ｘ^１、Ｘ^２、Ｘ^３、ｓおよびｋと同じである。但し、Ａｒｃ^１、Ａｒｃ^２、Ｒｃ^１、Ｒｃ^２、Ｘｃ^１、Ｘｃ^２およびＸｃ^３は、これらの内の一つが４価の基であるか、二つが３価の基である。

Arc ¹ , Arc ² , Rc ¹ , Rc ² , Xc ¹ , Xc ² , Xc ³ , s and k are respectively Ar ¹ , Ar ² , R ¹ , Same as R ² , X ¹ , X ² , X ³ , s and k. However, Arc ¹ , Arc ² , Rc ¹ , Rc ² , Xc ¹ , Xc ² and Xc ³ are either a tetravalent group or two are trivalent groups.

Z ¹ and Z ² are preferably each independently a single bond, a double bond, an atom, an atomic group or a polymer. Z ¹ and Z ² are bonding parts, and a plurality of cyclic structures are bonded via Z ¹ and Z ² to form a structure represented by the formula (14).

Examples of the cyclic carbodiimide compound (14) include the following compounds.

  As an epoxy compound, a glycidyl ether compound, a glycidyl ester compound, a glycidyl amine compound, a glycidyl imide compound, a glycidyl amide compound, and an alicyclic epoxy compound can be preferably used.

  Examples of glycidyl ether compounds include, for example, stearyl glycidyl ether, phenyl glycidyl ether, ethylene oxide lauryl alcohol glycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentylene glycol diglycidyl ether, Bisphenol A obtained by condensation reaction of bisphenols such as polytetramethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether and other bis (4-hydroxyphenyl) methane with epichlorohydrin Diglycidyl ether type epoxy resin Etc. can be mentioned, among others bisphenol A diglycidyl ether type epoxy resin is preferable. Examples of glycidyl ester compounds include glycidyl benzoate, glycidyl stearate, persic acid glycidyl ester, terephthalic acid diglycidyl ester, phthalic acid diglycidyl ester, cyclohexanedicarboxylic acid diglycidyl ester, adipic acid diglycidyl ester, and succinic acid. Examples include acid diglycidyl ester, dodecanedioic acid diglycidyl ester, pyromellitic acid tetraglycidyl ester, and the like. Among them, benzoic acid glycidyl ester and versatic acid glycidyl ester are preferable.

  Examples of the glycidylamine compound include tetraglycidylamine diphenylmethane, triglycidyl-p-aminophenol, diglycidylaniline, diglycidyltoluidine, tetraglycidylmetaxylenediamine, triglycidyl isocyanurate, and the like.

  Examples of glycidyl imide and glycidyl amide compounds include N-glycidyl phthalimide, N-glycidyl-4,5-dimethyl phthalimide, N-glycidyl-3,6-dimethyl phthalimide, N-glycidyl succinimide, N-glycidyl-1 , 2,3,4-tetrahydrophthalimide, N-glycidyl maleimide, N-glycidyl benzamide, N-glycidyl stearyl amide, etc., among which N-glycidyl phthalimide is preferable.

  Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexyl-3,4-cyclohexylcarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene diepoxide, N-methyl-4,5- Examples thereof include epoxycyclohexane-1,2-dicarboxylic imide, N-phenyl-4,5-epoxycyclohexane-1,2-dicarboxylic imide and the like. Furthermore, a polyepoxy compound containing the above compound as a monomer unit, particularly a polyepoxy compound having an epoxy group as a pendant group in a side chain, and the like can be mentioned as suitable agents.

  As other epoxy compounds, epoxy-modified fatty acid glycerides such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized whale oil, phenol novolac type epoxy resins, cresol novolac type epoxy resins and the like can be used.

  Examples of the oxazoline compound include 2-methoxy-2-oxazoline, 2-butoxy-2-oxazoline, 2-stearyloxy-2-oxazoline, 2-cyclohexyloxy-2-oxazoline, 2-allyloxy-2-oxazoline, 2-benzyl Oxy-2-oxazoline, 2-p-phenylphenoxy-2-oxazoline, 2-methyl-2-oxazoline, 2-cyclohexyl-2-oxazoline, 2-methallyl-2-oxazoline, 2-crotyl-2-oxazoline, 2 -Phenyl-2-oxazoline, 2-o-ethylphenyl-2-oxazoline, 2-o-propylphenyl-2-oxazoline, 2-p-phenylphenyl-2-oxazoline, 2,2'-bis (2-oxazoline) ), 2,2′-bis (4-methyl-2-oxa Phosphorus) 2,2′-bis (4-butyl-2-oxazoline), 2,2′-m-phenylenebis (2-oxazoline), 2,2′-p-phenylenebis (4-methyl-2-oxazoline) ), 2,2′-p-phenylenebis (4,4′-methyl-2-oxazoline), 2,2′-ethylenebis (2-oxazoline), 2,2′-tetramethylenebis (2-oxazoline) 2,2'-hexamethylenebis (2-oxazoline), 2,2'-ethylenebis (4-methyl-2-oxazoline), 2,2'-tetramethylenebis (4,4'-dimethyl-2-) Oxazoline), 2,2′-cyclohexylenebis (2-oxazoline), 2,2′-diphenylenebis (4-methyl-2-oxazoline), and the like.

  In the polylactic acid in the present invention, the poly-D-lactic acid component is composed of D-lactic acid units, preferably 90 to 100 mol% of D-lactic acid units and 0 to 10 mol% of copolymerized units other than D-lactic acid. . Further, the poly-L-lactic acid component is composed of L-lactic acid units, preferably 90 to 100 mol% of L-lactic acid units and 0 to 10 mol% of copolymerized units other than L-lactic acid.

In the above, the D-, L-lactic acid unit, which is the main repeating unit, is more preferably selected from the range of 95 to 100 mol%, more preferably 98 to 100 mol%.
The copolymer unit other than the main repeating unit is preferably selected in the range of 0 to 10 mol%, more preferably 0 to 5 mol%, and still more preferably 0 to 2 mol%.

  Copolymerized units include units derived from dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones and the like having functional groups capable of forming two or more ester bonds, and various polyesters, various polyethers, various types composed of these various components. Examples are units derived from polycarbonate and the like.

  Examples of the dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid. Examples of the polyhydric alcohol include aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, glycerin, sorbitan, neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol. Or aromatic polyhydric alcohol etc., such as what added ethylene oxide to bisphenol, etc. are mentioned. Examples of the hydroxycarboxylic acid include glycolic acid and hydroxybutyric acid. Examples of the lactone include glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, and δ-valerolactone.

  The weight average molecular weight of the poly L-lactic acid and poly D-lactic acid component in the present invention is preferably 100,000 to 500,000, more preferably 110,000 to 350,000, in order to achieve both the mechanical properties and moldability of the protective film. More preferably, a range of 12 to 250,000 is selected.

Poly L-lactic acid and poly D-lactic acid can be produced by a conventionally known method.
For example, it can be produced by ring-opening polymerization of L- or D-lactide in the presence of a metal-containing catalyst. In addition, low molecular weight polylactic acid containing a metal-containing catalyst is crystallized as desired or without crystallization, under reduced pressure or from normal pressure, in the presence of an inert gas stream, or absent It can also be produced by solid phase polymerization. Furthermore, it can be produced by a direct polymerization method in which lactic acid is subjected to dehydration condensation in the presence or absence of an organic solvent.

  The polymerization reaction can be carried out in a conventionally known reaction vessel. For example, in ring-opening polymerization or direct polymerization method, a vertical reactor or a horizontal reactor equipped with a stirring blade for high viscosity, such as a helical ribbon blade, is used alone, or Can be used in parallel. Moreover, any of a batch type, a continuous type, a semibatch type may be sufficient, and these may be combined.

  Alcohol may be used as a polymerization initiator. Such alcohol is preferably non-volatile without inhibiting the polymerization of polylactic acid, such as decanol, dodecanol, tetradecanol, hexadecanol, octadecanol, ethylene glycol, trimethylolpropane, pentaerythritol, etc. Can be suitably used.

  It can be said that the polylactic acid prepolymer used in the solid-phase polymerization method is preferably crystallized in advance from the viewpoint of preventing resin pellet fusion. The prepolymer is polymerized in a solid state in a fixed vertical or horizontal reaction vessel, or in a reaction vessel (such as a rotary kiln) that rotates itself like a tumbler or kiln, in the temperature range from the glass transition temperature of the prepolymer to less than the melting point. Is done.

  Metal-containing catalysts include alkali metals, alkaline earth metals, rare earths, transition metals, fatty acid salts such as aluminum, germanium, tin, antimony, titanium, carbonates, sulfates, phosphates, oxides, hydroxides , Halides, alcoholates and the like.

  Among them, fatty acid salts, carbonates, sulfates, phosphates, oxides, hydroxides containing at least one metal selected from tin, aluminum, zinc, calcium, titanium, germanium, manganese, magnesium and rare earth elements Products, halides, and alcoholates are preferred.

  Tin compounds due to low catalytic activity and side reactions, specifically stannous chloride, stannous bromide, stannous iodide, stannous sulfate, stannic oxide, tin myristate, tin octylate Tin-containing compounds such as tin stearate and tetraphenyltin are exemplified as preferred catalysts.

  Among these, tin (II) compounds, specifically, diethoxytin, dinonyloxytin, tin (II) myristate, tin (II) octylate, tin (II) stearate, tin (II) chloride and the like are suitable. Illustrated.

The amount of the catalyst used is 0.42 × 10 ⁻⁴ to 100 × 10 ⁻⁴ (mol) per 1 kg of lactide, and is 1.68 × 10 ^{−4 in} consideration of reactivity, color tone and stability of the resulting polylactides. To 42.1 × 10 ⁻⁴ (mol), particularly preferably 2.53 × 10 ⁻⁴ to 16.8 × 10 ⁻⁴ (mol) mol.

The metal-containing catalyst used for polylactic acid polymerization is preferably deactivated with a conventionally known deactivator prior to using polylactic acid.
Examples of such a deactivator include an organic ligand comprising a group of chelate ligands having an imino group and capable of coordinating to a polymerized metal catalyst, dihydridooxoline (I) acid, dihydridotetraoxodilin (II, II ) Acid, hydridotrioxoline (III) acid, dihydridopentaoxodiphosphorus (III) acid, hydridopentaoxodi (II, IV) acid, dodecaoxohexaphosphorus (III) acid, hydridooctaoxotriphosphate (III, IV) , IV) acid, octaoxotriphosphoric acid (IV, III, IV), hydridohexaoxodiphosphoric acid (III, V), hexaoxodiphosphoric acid (IV), decaoxotetraphosphoric acid (IV), hedecaoxotetralin (IV ) acid, Eneaokiso triphosphate (V, IV, IV) acid value 5 or less low oxidation number phosphoric acids such as acid, by the formula xH _{2 O} · _{yP 2} O ₅ Orthophosphoric acid of x / y = 3, 2> x / y> 1, and polyphosphoric acid referred to as diphosphoric acid, triphosphoric acid, tetraphosphoric acid, pentaphosphoric acid and the like based on the degree of condensation, and mixtures thereof, Metaphosphoric acid represented by x / y = 1, especially trimetaphosphoric acid, tetrametaphosphoric acid, ultraphosphoric acid represented by 1> x / y> 0 and having a network structure with a part of the phosphorus pentoxide structure (These may be collectively referred to as metaphosphate compounds), and acid salts of these acids, monovalent and polyhydric alcohols, partial esters of polyalkylene glycols, fully ether, phosphono-substituted lower Examples thereof include aliphatic carboxylic acid derivatives.

From the catalyst deactivation ability, it is represented by the formula xH ₂ O · yP ₂ O ₅ , x / y = 3 orthophosphoric acid, 2> x / y> 1, and based on the degree of condensation, diphosphate, triphosphate, tetra Polyphosphoric acid called phosphoric acid, pentaphosphoric acid and the like and mixtures thereof, metaphosphoric acid represented by x / y = 1, especially trimetaphosphoric acid, tetrametaphosphoric acid, 1> x / y> 0, Ultraphosphoric acid having a network structure in which a part of the phosphorus oxide structure is extended (these may be collectively referred to as metaphosphoric acid compounds), and acid salts of these acids, monovalent and polyhydric alcohols Or partial ester phosphorus oxoacids of polyalkylene glycols or acidic esters thereof, phosphono-substituted lower aliphatic carboxylic acid derivatives and the above-mentioned metaphosphoric acid compounds are preferably used.

  The metaphosphoric acid compound used in the present invention is a cyclic metaphosphoric acid in which about 3 to 200 phosphoric acid units are condensed, an ultra-regional metaphosphoric acid having a three-dimensional network structure, or an alkali metal salt or an alkaline earth metal salt thereof. Onium salts). Among them, cyclic sodium metaphosphate, ultra-region sodium metaphosphate, phosphono-substituted lower aliphatic carboxylic acid derivative dihexylphosphonoethyl acetate (hereinafter sometimes abbreviated as DHPA) and the like are preferably used.

  The polylactic acid used in the present invention preferably has a lactide content of 1 to 5000 ppm. The lactide contained in the polylactic acid deteriorates the resin and deteriorates the color tone at the time of melt processing, and in some cases, it may be disabled as a product.

  The poly L- and / or poly D-lactic acid immediately after the melt ring-opening polymerization usually contains 1 to 5% by weight of lactide, but the poly L- and / or poly D-lactic acid molding is completed from the end of the polymerization. At any stage up to the above, a conventionally known lactide weight loss method, that is, a vacuum devolatilization method in a single or multi-screw extruder, or a high vacuum treatment in a polymerization apparatus is carried out alone or in combination. In addition, lactide can be reduced to a suitable range.

  The smaller the lactide content, the better the melt stability and heat-and-moisture resistance of the resin, but there is also the advantage of lowering the resin melt viscosity, making it reasonable and economical to meet the desired purpose. is there. That is, it is reasonable to set it to 1 to 1000 ppm at which practical melt stability is achieved. More preferably, a range of 1 to 700 ppm, more preferably 2 to 500 ppm, particularly preferably 5 to 100 ppm is selected.

  By having a lactide content in such a range, the polylactic acid component can improve the stability of the resin during the melt-casting of the protective film in the present invention, and the advantage that the film can be efficiently manufactured and the heat-and-moisture stability of the film , Low gas can be improved.

  The weight average molecular weight of the polylactic acid used in the present invention is selected in consideration of the relationship between the molding processability and the mechanical and thermal properties of the obtained molded product. That is, the weight average molecular weight is preferably 80,000 or more, more preferably 100,000 or more, and further preferably 130,000 or more in order to exert mechanical and thermal properties such as strength, elongation and heat resistance of the composition. is there.

However, as the weight average molecular weight increases, the melt viscosity of polylactic acid increases exponentially. When melt molding such as injection molding is performed, the molding temperature is set to the heat resistant temperature of polylactic acid so that the resin viscosity is within the moldable range. There are cases where it must be set higher than this.
Specifically, when polylactic acid is molded at a temperature exceeding 300 ° C., the film product is colored due to the thermal decomposition of the resin, and there is a high possibility that the value as a product is low.

  Therefore, the weight average molecular weight of the polylactic acid composition is preferably 500,000 or less, more preferably 400,000 or less, and still more preferably 300,000 or less. Therefore, the weight average molecular weight of polylactic acid is preferably 80,000 to 500,000, more preferably 100,000 to 400,000, and still more preferably 130,000 to 300,000.

  The ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is referred to as molecular weight dispersion (Mw / Mn). A large molecular weight dispersion means that there are many ratios of large molecules and small molecules compared to the average molecular weight.

  That is, for example, a polylactic acid having a weight average molecular weight of about 250,000 and a molecular weight dispersion of 3 or more may have a large proportion of molecules having a molecular weight greater than 250,000. In this case, the melt viscosity becomes large, It is not preferable in terms of molding. In addition, in a polylactic acid composition having a relatively small weight average molecular weight of about 80,000 and a large molecular weight dispersion, the proportion of molecules having a molecular weight of less than 80,000 may increase. In this case, the durability of the mechanical properties of the molded product may be increased. Is not preferable in use. From this viewpoint, the range of molecular weight dispersion is preferably 1.5 to 2.4, more preferably 1.6 to 2.4, and still more preferably 1.6 to 2.3.

  As described above, the polylactic acid of the present invention is obtained by bringing the poly L-lactic acid component and the poly D-lactic acid component into contact with each other at a weight ratio in the range of 10/90 to 90/10, preferably by melt contact. Preferably, it can be obtained by melt-kneading contact.

  The contact temperature between the poly L-lactic acid component and the poly D-lactic acid component is 220 to 290 ° C., preferably 220 to 280 ° C., more preferably from the viewpoint of improving the stability of the polylactic acid when melted and the stereocomplex crystallinity. A range of 225 to 275 ° C. is selected.

  The melt kneading method is not particularly limited, but a conventionally known batch type or continuous type melt mixing apparatus is preferably used. For example, melt-stirred tanks, single- and twin-screw extruders, kneaders, non-shaft vertical stirrers, "Vibolac" manufactured by Sumitomo Heavy Industries, Ltd., N-SCR manufactured by Mitsubishi Heavy Industries, Ltd., Hitachi, Ltd. You can use glass blades, lattice blades or Kenix type stirrers, or Sulzer type SMLX type static mixer equipped pipe type polymerization equipment, but it is a self-cleaning type polymerization equipment in terms of productivity, quality of polylactic acid, especially color tone. A certain non-shaft vertical stirring tank, N-SCR, twin-screw extruder, etc. are preferably used.

  In the polylactic acid used in the present invention, a method of blending a specific additive in order to stably and highly advance the formation of a stereocomplex polylactic acid crystal is preferably applied without departing from the gist of the present invention.

  That is, for example, a method of adding a metal phosphate represented by the following formula (22) or (23) as a stereocomplex crystallization accelerator can be mentioned.

式（２２）中、Ｒ^１１は水素原子または炭素原子数１〜４のアルキル基を表し、Ｒ^１２、Ｒ^１３はそれぞれ独立に、水素原子、または炭素原子数１〜１２のアルキル基を表し、Ｍ_１はアルカリ金属原子、アルカリ土類金属原子、亜鉛原子またはアルミニウム原子を表し、ｐは１または２を表し、ｑはＭ_１がアルカリ金属原子、アルカリ土類金属原子、亜鉛原子のときは０を、アルミニウム原子の時は１または２を表す。

In formula (22), R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ¹² and R ¹³ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, M ₁ represents an alkali metal atom, an alkaline earth metal atom, a zinc atom or an aluminum atom, p represents 1 or 2, and q represents 0 when M ₁ is an alkali metal atom, an alkaline earth metal atom or a zinc atom. Represents an aluminum atom, 1 or 2.

式（２３）中Ｒ^１４、Ｒ^１５およびＲ^１６は各々独立に、水素原子または炭素原子数１〜１２のアルキル基を表し、Ｍ_２はアルカリ金属原子、アルカリ土類金属原子、亜鉛原子またはアルミニウム原子を表し、ｐは１または２を表し、ｑはＭ_２がアルカリ金属原子、アルカリ土類金属原子、亜鉛原子のときは０を、アルミニウム原子の時は１または２を表す。

In the formula (23), R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and M ₂ represents an alkali metal atom, an alkaline earth metal atom, a zinc atom or aluminum. P represents 1 or 2, q represents 0 when M ₂ is an alkali metal atom, alkaline earth metal atom, or zinc atom, and 1 or 2 when M ₂ is an aluminum atom.

M ₁ and M ₂ of the metal phosphate represented by the formula (22) or (23) are preferably Na, K, Al, Mg, Ca, Li, and in particular, Li, K, Na, Al, and Li. Al can be most preferably used.

  As these metal phosphates, trade names manufactured by ADEKA Corporation, “ADEKA STAB” NA-11, NA-71 and the like are exemplified as suitable agents. The metal phosphate is used in an amount of 0.001 to 2 wt%, preferably 0.005 to 1 wt%, more preferably 0.01 to 0.5 wt%, more preferably 0.02 to 0.3 wt% with respect to polylactic acid. It is preferable. When the amount is too small, the effect of improving the stereocomplex crystallinity (S) is small, and when too large, the stereocomplex crystal melting point is lowered, which is not preferable.

Furthermore, if desired, a known crystallization nucleating agent described below can be used in combination in order to enhance the action of the metal phosphate. Of these, calcium silicate, talc, kaolinite, and montmorillonite are preferably selected.
The amount of crystallization nucleating agent used is selected in the range of 0.05 to 5 wt%, more preferably 0.06 to 2 wt%, and still more preferably 0.06 to 1 wt% with respect to polylactic acid.

  In addition, a functional group selected from the group of stereocomplex crystallization aids [(epoxy group, oxazoline group, oxazine group, isocyanate group, ketene group and carbodiimide group) (hereinafter sometimes abbreviated as a specific functional group) is a molecule. And a method of adding a compound having at least one compound].

  In the present invention, the stereocomplex crystallization aid means that a specific functional group reacts with the molecular end of polylactic acid to partially link a poly L-lactic acid unit and a poly D-lactic acid unit to form a stereocomplex crystal. It is an agent that the present inventors speculate that it is promoted.

  As the stereocomplex crystallization aid, a known agent can be suitably applied as a carboxyl terminal group blocking agent for conventional polyesters described below. Especially, a carbodiimide compound is suitably selected from the stereocomplex crystal formation promotion effect.

  However, stereocomplex crystallization aids, especially nitrogen-containing stereocomplex crystallization aids, have a high risk of causing deterioration of the working environment due to malodor and deterioration of the color tone of polylactic acid due to thermal decomposition of the agent during stereocomplex crystal formation. Therefore, it is preferable not to use it, and when using it, it is limited to a case where emphasis is placed on the high-level formation of stereocomplex crystals, and it is preferable to use it while suppressing it as little as possible.

  The amount of the stereocomplex crystallization aid used is not more than 1 wt%, preferably 0 to 0.5 wt%, more preferably 0 to 0.3 wt%, still more preferably 0 to 0.1 wt% in the same standard as above. Is selected.

  That is, it is preferable to apply the above-described stereogenic accelerator method alone, and when emphasizing stereocomplex crystal formation, it is preferably selected to be applied in combination with the stereocomplex crystallization aid method.

In the present invention, the carboxyl end group concentration of polylactic acid is 0.01 to 10 (equivalent / 10 ⁶ g), and {hereinafter (equivalent / 10 ⁶ g) may be abbreviated as (equivalent / ton). } Is preferred. The range of 0.02 to 2 (equivalent / ton) is more preferable, and the range of 0.02 to 1 (equivalent / ton) is more preferably selected.

  When the carboxyl end group concentration is within this range, the melt stability and wet heat stability can be improved. In order to reduce the carboxyl end group concentration of polylactic acid to 10 (equivalent / ton) or less, a conventionally known method for reducing the carboxyl end group concentration in the polyester composition can be suitably applied. It can also be amidated.

  The protective film used in the present invention includes thermoplastic resins other than polylactic acid, stabilizers, ultraviolet absorbers, crystallization accelerators, fillers, mold release agents, antistatic agents, plasticizers and impact stabilizers. At least one selected from the group consisting of: The polylactic acid used in the present invention preferably contains a stabilizer. As a stabilizer, what is used for the stabilizer of a normal thermoplastic resin can be used. For example, an antioxidant, a light stabilizer, etc. can be mentioned. By blending these agents, a protective film excellent in mechanical properties, moldability, heat resistance and durability can be obtained.

Examples of the antioxidant include hindered phenol compounds, hindered amine compounds, phosphite compounds, thioether compounds, and the like.
Examples of hindered phenol compounds include n-octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl-5 ′). -Tert-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol- Bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) -Propionate], 2,2′-methylene-bis (4-methyl-tert-butylphenol), triethylene glycol-bis [3- (3-tert -Butyl-5-methyl-4-hydroxyphenyl) -propionate], tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 3,9-bis [ 2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro (5,5) undecane, etc. Is mentioned. As a hindered amine compound, N, N′-bis-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionylhexamethylenediamine, N, N′-tetramethylene-bis [3- (3′-Methyl-5′-tert-butyl-4′-hydroxyphenyl) propionyl] diamine, N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionyl ] Hydrazine, N-salicyloyl-N′-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N′-bis [2- {3- (3,5-di) -Tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] oxyamide and the like. Preferably, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] and tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl) -4-hydroxyphenyl) propionate] methane and the like.

  As the phosphite compound, those in which at least one P—O bond is bonded to an aromatic group are preferable. Specifically, tris (2,6-di-tert-butylphenyl) phosphite, tetrakis ( 2,6-di-tert-butylphenyl) 4,4′-biphenylene phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol di-phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-ditridecyl phosphite-5-tert-butylphenyl) butane, tris (mixed mono and di-no Butylphenyl) phosphite, tris (nonylphenyl) phosphite, 4,4'-isopropylidene-bis (phenyl - dialkyl phosphite), and the like.

  Among them, tris (2,6-di-tert-butylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, bis (2,6-di-tert-butyl) -4-Methylphenyl) pentaerythritol-di-phosphite, tetrakis (2,6-di-tert-butylphenyl) 4,4'-biphenylene phosphite and the like can be preferably used.

  Specific examples of thioether compounds include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, pentaerythritol-tetrakis (3-lauryl thiopropionate), Pentaerythritol-tetrakis (3-dodecylthiopropionate), pentaerythritol-tetrakis (3-octadecylthiopropionate), pentaerythritol tetrakis (3-myristylthiopropionate), pentaerythritol-tetrakis (3-stearylthio) Propionate) and the like.

  Examples of the light stabilizer include oxybenzophenone compounds, cyclic imino ester compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, hindered amine compounds, nickel complex compounds, and the like. I can do it. As a light stabilizer, you may use in combination with the ultraviolet absorber and what capture | acquires the radical produced | generated by photooxidation.

  As the ultraviolet absorber, a cyclic imino ester compound, a benzophenone compound, and a benzotriazole compound are preferable in that absorption in visible light can be minimized. In addition, from the viewpoint of preventing deterioration of the polarizing film and the liquid crystal, those having excellent absorption ability of ultraviolet rays having a wavelength of 370 nm or less and less visible light absorption having a wavelength of 400 nm or more are preferable from the viewpoint of liquid crystal display performance.

  Specific examples of useful benzotriazole ultraviolet absorbers include 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′-hydroxy-3 ′, 5′-di-tert-butylphenyl)- 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2, 2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2 ′ Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy Examples include, but are not limited to, a mixture of -5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate. As commercially available products, TINUVIN 109, TINUVIN 171, TINUVIN 326, and TINUVIN 328 (all manufactured by Ciba Specialty Chemicals) can be preferably used.

  Specific examples of the cyclic imino ester compound include 2,2′-bis (3,1-benzoxazin-4-one), 2,2′-p-phenylenebis (3,1-benzoxazin-4-one). ), 2,2′-m-phenylenebis (3,1-benzoxazin-4-one), 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazin-4-one) 2,2 ′-(2,6-naphthalene) bis (3,1-benzoxazin-4-one), 2,2 ′-(1,5-naphthalene) bis (3,1-benzoxazine-4-one) ON), 2,2 ′-(2-methyl-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2-nitro-p-phenylene) bis (3,1 -Benzoxazin-4-one) and 2,2 '-(2-chloro-p- Eniren) bis (3,1-benzoxazin-4-one) is illustrated. Among them, 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazin-4-one) And 2,2 ′-(2,6-naphthalene) bis (3,1-benzoxazin-4-one) are preferred, especially 2,2′-p-phenylenebis (3,1-benzoxazine-4 -On) is preferred. Cyclic iminoesters can be used alone or in combination of two or more.

  The cyclic imino ester can be produced by various methods disclosed in the pamphlet of WO 03/035735. That is, any of a method using isatoic anhydride as a raw material (in particular, a method using recrystallized isatoic anhydride) and a method using anthranilic acid can be used. A cyclic imino ester compound can be obtained by reacting these acid compounds with a carboxylic acid chloride compound. These may be recrystallized after production as disclosed in JP-B-62-31027. Such compounds are commercially available from Takemoto Yushi Co., Ltd. as CEi-P (trade name) and from CYTEC as CYASORB UV-3638 (trade name) and can be easily used.

  Examples of benzophenone compounds include benzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxybenzophenone, 2,2'4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'- Dihydroxy-4,4′-dimethoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 5-chloro-2-hydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxy- 2 ' Carboxybenzophenone, 2-hydroxy-4- (2-hydroxy-3-methyl-acryloxyisopropoxy) benzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid hydrate, 2-hydroxy-4-octyloxy Examples include benzophenone, 4-benzyloxy-2-hydroxybenzophenone, 1,4-bis (4-benzoyl-3-hydroxyphenoxy) -butane, and the like.

  The protective film in the present invention can contain an organic or inorganic crystallization accelerator. By containing the crystallization accelerator, the action of the stereocomplex crystal accelerator can be further enhanced, and a molded product having excellent mechanical properties, heat resistance, and moldability can be obtained.

  As the crystallization accelerator used in the present invention, those generally used as crystal nucleating agents for crystalline resins can be used, and both inorganic crystal nucleating agents and organic crystal nucleating agents can be used. .

  As inorganic crystal nucleating agents, talc, kaolin, silica, synthetic mica, clay, zeolite, graphite, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium carbonate, calcium sulfate, barium sulfate, calcium sulfide, boron nitride, Examples thereof include montmorillonite, neodymium oxide, aluminum oxide, and phenylphosphonate metal salt.

  These inorganic crystal nucleating agents are treated with various dispersion aids in order to enhance the dispersibility in the composition and the effect thereof, and the primary particle diameter becomes a highly dispersed state of about 0.01 to 0.5 μm. Some are preferred.

  Organic nucleating agents include calcium benzoate, sodium benzoate, lithium benzoate, potassium benzoate, magnesium benzoate, barium benzoate, calcium oxalate, disodium terephthalate, dilithium terephthalate, dipotassium terephthalate, lauric acid Sodium phosphate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, barium myristate, sodium octacolate, calcium octacolate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, Barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, salicylate Examples include organic carboxylic acid metal salts such as zinc, aluminum dibenzoate, sodium β-naphthoate, potassium β-naphthoate, and sodium cyclohexanecarboxylate, and organic sulfonic acid metal salts such as sodium p-toluenesulfonate and sodium sulfoisophthalate. It is done.

  In addition, stearic acid amide, ethylene bislauric acid amide, palmitic acid amide, hydroxy stearic acid amide, erucic acid amide, trimesic acid tris (t-butylamide) and other organic carboxylic acid amides, low density polyethylene, high density polyethylene, polyiso Propylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltrialkylsilane, high melting point polylactic acid, sodium salt of ethylene-acrylic acid copolymer, sodium of styrene-maleic anhydride copolymer Examples thereof include salts (so-called ionomers), benzylidene sorbitol and derivatives thereof such as dibenzylidene sorbitol.

Among these, at least one selected from talc and metal organic carboxylic acid salts is preferably used. Only one type of crystal nucleating agent may be used in the protective film of the present invention, or two or more types may be used in combination.
The content of the crystallization accelerator is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 20 parts by weight per 100 parts by weight of polylactic acid.

  Examples of the antistatic agent used in the present invention include (β-lauramidopropionyl) trimethylammonium sulfate, quaternary ammonium salts such as sodium dodecylbenzenesulfonate, sulfonate compounds, and alkyl phosphate compounds. It is done.

  In the protective film of the present invention, the antistatic agent may be used singly or in combination of two or more. The content of the antistatic agent is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of polylactic acid.

  As the plasticizer used in the present invention, generally known plasticizers can be used. Examples include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, phosphate ester plasticizers, polyalkylene glycol plasticizers, and epoxy plasticizers.

  As a polyester plasticizer, acid components such as adipic acid, sebacic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, Examples thereof include polyesters composed of diol components such as 1,6-hexanediol and diethylene glycol, and polyesters composed of hydroxycarboxylic acids such as polycaprolactone. These polyesters may be end-capped with a monofunctional carboxylic acid or a monofunctional alcohol.

  Examples of the glycerol plasticizer include glycerol monostearate, glycerol distearate, glycerol monoacetomonolaurate, glycerol monoacetomonostearate, glycerol diacetomonooleate, and glycerol monoacetomonomontanate.

  Polyvalent carboxylic acid plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, trimellitic acid tributyl, trimellitic acid trioctyl, Trimellitic acid esters such as trihexyl meritate, isodecyl adipate, adipic acid esters such as adipate-n-decyl-n-octyl, citrate esters such as tributyl acetylcitrate, bis (2-ethylhexyl) azelate, etc. Examples include sebacic acid esters such as azelaic acid ester, dibutyl sebacate, and bis (2-ethylhexyl) sebacate.

  Examples of the phosphate ester plasticizer include tributyl phosphate, tris phosphate (2-ethylhexyl), trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, diphenyl-2-ethylhexyl phosphate, and the like.

  Polyalkylene glycol plasticizers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (ethylene oxide.propylene oxide) block and / or random copolymers, ethylene oxide addition polymers of bisphenols, tetrahydrofuran addition polymers of bisphenols, etc. And end-capping compounds such as a terminal epoxy-modified compound, a terminal ester-modified compound and a terminal ether-modified compound.

  Examples of the epoxy plasticizer include an epoxy triglyceride composed of alkyl epoxy stearate and soybean oil, and an epoxy resin using bisphenol A and epichlorohydrin as raw materials.

  Specific examples of other plasticizers include benzoic acid esters of aliphatic polyols such as neopentyl glycol dibenzoate, diethylene glycol dibenzoate, triethylene glycol-bis (2-ethylbutyrate), and fatty acids such as stearamide. Examples thereof include fatty acid esters such as amide and butyl oleate, oxyacid esters such as methyl acetylricinoleate and butyl acetylricinoleate, pentaerythritol, various sorbitols, polyacrylic acid esters, silicone oils, and paraffins.

  As the plasticizer, at least one selected from polyester-type plasticizers and polyalkylene-type plasticizers is preferably used, and only one type may be used or two or more types may be used in combination.

  The content of the plasticizer is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 20 parts by weight, and further preferably 0.1 to 10 parts by weight per 100 parts by weight of the protective film. In the present invention, each of the crystal nucleating agent and the plasticizer may be used alone, or more preferably used in combination.

<Formation of protective film, stretching method>
In order to form a resin composition containing polylactic acid obtained by the above-described method, a known molding technique such as extrusion molding or cast molding can be used. For example, the film can be formed using an extruder equipped with a T die, an I die, a circular die and the like.

  When an unstretched film is obtained by extrusion molding, a material in which polylactic acid and other components are previously melt-kneaded can be used, or it can be molded through melt-kneading at the time of extrusion molding. An unstretched film can be produced by extruding a molten film onto a cooling drum and then bringing the film into close contact with a rotating cooling drum and cooling. At this time, the molten film is blended with an electrostatic adhesion agent such as quaternary phosphonium salt of sulfonic acid, and an electric charge is easily applied from the electrode to the film melting surface in a non-contact manner, whereby the film is adhered to the rotating cooling drum. By making it, you may obtain an unstretched film with few surface defects.

  At that time, the ratio (draft ratio) between the lip opening of the extrusion die and the thickness of the sheet extruded on the cooling drum is preferably 2 or more and 80 or less. If the draft ratio is less than 2, the take-off speed from the extrusion die lip becomes too slow, and the speed of separation of the polymer from the die lip becomes slow, which may increase the number of defects such as die lip stripe defects, which may be undesirable. From this viewpoint, the draft ratio is preferably 3 or more, more preferably 5 or more, still more preferably 9 or more, and particularly preferably 15 or more. On the other hand, if the draft ratio is greater than 80, the deformation when the polymer leaves the die lip may be too large, or the flow may become unstable, resulting in poor thickness variation (thickness unevenness), which may be undesirable. From this viewpoint, the draft ratio is preferably 60 or less, more preferably 40 or less, and particularly preferably 30 or less.

The unstretched film can be stretched by known longitudinal uniaxial stretching, lateral uniaxial stretching, simultaneous biaxial stretching, or the like. Further, the film is preferably subjected to a heat setting treatment after stretching in order to enhance crystallinity and to suppress heat shrinkability.
The draw ratio is appropriately determined depending on the target retardation value.

  In order to make the protective film optically isotropic, the area stretch ratio (longitudinal magnification x lateral magnification) is preferably 3.0 times or less, more preferably 2.0 times or less, and even more preferably 1.7 times or less. The range is preferably 1.02 times or more, more preferably 1.05 times or more. When the area stretch ratio is 3.0 times or more, it may be difficult to satisfy the optical isotropy, and when it is less than 1.02, it is crystallized in the next heat setting step. May be difficult.

  The stretching temperature is preferably selected from the glass transition temperature (Tg) to the crystallization temperature (Tc) of the resin composition. Furthermore, a temperature range higher than Tg and as close to Tc as possible but not causing crystallization of polylactic acid is more suitably employed to suppress Re and Rth.

Since the molecular chain is fixed at a temperature lower than Tg, it is difficult to suitably proceed the stretching operation, and the crystallization of polylactic acid proceeds at Tc or higher, and in this case, the stretching process should proceed well. It becomes difficult.
Accordingly, the stretching temperature is more preferably Tg-5 ° C or higher, further preferably Tg-10 ° C or higher, more preferably Tc + 5 ° C or lower, and further preferably Tc + 10 ° C or lower.

  From the viewpoint of achieving both physical properties of the film and stabilization of the stretching process, the stretching temperature is preferably set from the above temperature range. The upper limit of the stretching temperature should be set as appropriate in consideration of the apparatus characteristics because the film properties and the stabilization of the stretching process are in conflict.

The protective film containing polylactic acid is preferably heat-set in the temperature range from the crystallization temperature (Tc) of the resin composition to the crystal melting start temperature (Tm *) of the stereocomplex phase polylactic acid. By performing this heat setting treatment, crystallization of the stereocomplex phase polylactic acid is promoted, and the heat shrinkage rate is suitably reduced, and the storage elastic modulus E ′ is measured at a room temperature (25 ° C.) by dynamic viscoelasticity (DMA) measurement. Can be maintained at a value greater than 0.5 × 10 ⁸ Pa without exhibiting a minimum value in the temperature range of 1 to 150 ° C.

The heat treatment temperature is preferably 90 to Tm * (° C), more preferably 100 to (Tm * -30) (° C), and still more preferably 105 to (Tm * -40) (° C).
The heat treatment is preferably performed in the range of 1 second to 30 minutes. When the heat treatment temperature is high, a relatively short time is required, and when the heat setting temperature is low, a relatively long time is required.

<Surface condition of protective film, surface treatment and radiation curable composition>
In the polarizing plate of the present invention, the above-described protective film and a polarizing film described later are bonded by curing a radiation curable composition as an adhesive.

In order to improve the adhesion between the protective film made of a material containing polylactic acid and the polarizing film, the bulk average concentration of the terminal group represented by the following formula (2) of the polylactic acid forming the protective film is It is preferably lower than the end group concentration in the vicinity of the adhesion interface.
In the present invention, “near the interface” means a portion having a thickness of 2 μm from the interface toward the center.

  When the terminal group of the above formula (2) is present, the adhesiveness is improved. When the following formula (1) which is a radiation curable composition in the present invention is polymerized, the covalent bond is formed with the formula (2). The formation is known from the measurement results of proton NMR, and it seems that the adhesive force is remarkably improved.

  However, since the increase in the concentration of the terminal group (2) may cause embrittlement of the film, it is ideal that the terminal structure (2) exists only in the vicinity of the adhesive interface with the polarizing film. Therefore, it is preferable that the bulk average concentration of the terminal group represented by the above formula (2) is lower than the terminal group concentration in the vicinity of the adhesive interface on the polarizing film side.

  The ratio of the end group bulk average concentration of the above formula (2) to the end group concentration in the vicinity of the adhesive interface on the polarizing film side is preferably 1/2 to 1/300, more preferably 1/3 to 1 /. 200, more preferably 1/4 to 1/100.

There are several possible generation mechanisms of the above-mentioned formula (2) which is a polylactic acid end group. For example, a mechanism of the following formula (6) by ultraviolet irradiation is considered.

  The concentration of the end group of the above formula (2) is quantified by proton NMR, but is defined as equivalent per ton of resin forming the protective film, that is, equivalent / ton. Here, the bulk average concentration is the bulk average concentration of the end group of the above formula (2) in the entire protective film, and is evaluated by proton NMR after being dissolved in an appropriate solvent such as deuterated chloroform. On the other hand, the concentration of the terminal group of the above formula (2) in the vicinity of the adhesive interface on the polarizing film side is cut out with a knife or the like from the interface toward the center, and dissolved in an appropriate solvent as in the bulk. Evaluated by proton NMR.

  The end group bulk average concentration of the above formula (2) is preferably 0 to 10 equivalents / ton, more preferably 1 to 9 equivalents / ton, further preferably 1.5 to 8 equivalents / ton, and most preferably 2. .5-7 equivalents / ton. If the end group bulk concentration exceeds 10 equivalents / ton, the entire film may become brittle, which is not preferable.

  On the other hand, the terminal group concentration in the vicinity of the adhesive interface is preferably 3 to 300 equivalents / ton, more preferably 5 to 200 equivalents / ton, further preferably 7 to 100 equivalents / ton, and most preferably 10 to 60 equivalents / ton. ton. If the terminal group concentration in the vicinity of the adhesion interface is less than 3 equivalents / ton, sufficient adhesion may not be obtained, and if it exceeds 300 equivalents / ton, surface embrittlement will be significant, and adhesion will be obtained as well. There may not be.

  As a method for adjusting the terminal group of the above formula (2) to an appropriate amount mainly only on the surface, known ultraviolet ozone treatment, corona discharge treatment, atmospheric pressure plasma treatment and the like can be used. However, simply performing these treatments does not result in an optimum interface for adhesion. To optimize the functional group concentration of the above formula (2), optimization including treatment conditions, polymer composition, production method, etc. There is a need to.

As a guideline for these surface treatment conditions, when the contact angle of water before the surface treatment is C _B and the contact angle of water after the surface treatment is C _A , the relationship between them is expressed by the following formula (7). It is preferably represented.
1 ° <C _B -C _A <60 ° (7)
More preferably,
2 ° <C _B -C _A <45 ° (8)
More preferably,
3 ° <C _B -C _A <40 ° (9)
Most preferably 4 ° <C _B -C _A <35 ° (10)
It is.

When C _B -C _A is smaller than the range of the above formula (7), it may be difficult to sufficiently increase the terminal group (2), and adhesion may not be secured. In some cases, the surface or the whole becomes too brittle and adhesion cannot be obtained. These contact angles may not necessarily be related to adhesion. The contact angle can be measured by a known method.

（式（１）中、ｎは１または２を表し、Ｒ^２０は水素原子またはメチル基を表し、Ｒ^２１は炭素原子数１〜１０のアルキレン基（該アルキレン基中に存在する１個または２個以上のメチレン基は、酸素原子が相互に直接結合しないものとして、それぞれ独立に酸素原子、−ＣＯ−、−ＣＯＯ−又は−ＯＣＯ−で置換されていても良く、該アルキレン基中に存在する１個又は２個以上の水素原子はそれぞれ水酸基、カルボキシル基、イソシアネート基、アルデヒド基、リン酸基で置換されている。）を表す。） In this invention, what hardened | cured the radiation-curable composition of following formula (1) is used as an adhesive agent of the protective film which consists of a material containing a polarizing film and polylactic acid.

(In the formula (1), n represents 1 or 2, R ²⁰ represents a hydrogen atom or a methyl group, and R ²¹ represents an alkylene group having 1 to 10 carbon atoms (1 or 2 present in the alkylene group). One or more methylene groups may be each independently substituted with an oxygen atom, —CO—, —COO— or —OCO—, as oxygen atoms are not directly bonded to each other, and are present in the alkylene group. 1 or 2 or more hydrogen atoms are each substituted with a hydroxyl group, a carboxyl group, an isocyanate group, an aldehyde group, or a phosphate group.)

R ²¹ in formula (1) preferably does not contain an aromatic ring. When R ²¹ contains an aromatic ring, the adhesion with a polarizing film containing polyvinyl alcohol as a main component and a protective film containing polylactic acid as a main component tends to be poor. Since hydroxyl group contained in R ^21, a carboxyl group, an isocyanate group, an aldehyde group, a phosphoric acid group, which between hydroxyl groups of polyvinyl alcohol, hydrogen bonding is believed that the force of interaction such as the acid-base properties works, adhesive It is considered that the adhesive force is increased as compared with the case where only van der Waals force exists between the interfaces. R ²¹ must be at least one of a hydroxyl group, a carboxyl group, an isocyanate group, an aldehyde group, and a phosphoric acid group, but if four or more are present, radical polymerization does not proceed sufficiently due to steric hindrance or the like. In some cases, the adhesive strength may be reduced, so that the number is preferably 3 or less.

The number of carbon atoms in the alkylene groups of formula R ²¹ is required to be 1 to 10. If the carbon atom group is 0, the composition after curing is too hard and cracks and the like are generated after curing, and if the number of carbon atoms is 11 or more, the composition is too flexible and has sufficient adhesive strength. I cannot get it. The number of alkylene groups is preferably 2 to 6, and more preferably 2 to 5.

（式（３）中、Ｒ^２２は水素原子またはメチル基を表し、Ｒ^２３は炭素原子数２〜５のアルキレン基（該アルキレン基中に存在する１個のメチレン基は、−ＯＣＯ−で置換されていても良く、該アルキレン基中に存在する１個の水素原子はそれぞれ水酸基、カルボキシル基、イソシアネート基、リン酸基で置換されている。）を表す。）
上記式（３）を満足することで放射線硬化型組成物においてより良好な接着性が確保できる。 More preferably, the above formula (1) satisfies the following formula (3).

(In the formula (3), R ²² represents a hydrogen atom or a methyl group, R ²³ represents an alkylene group having 2 to 5 carbon atoms (one methylene group present in the alkylene group is substituted with —OCO—). And each hydrogen atom present in the alkylene group is substituted with a hydroxyl group, a carboxyl group, an isocyanate group, or a phosphoric acid group.)
By satisfying the above formula (3), better adhesiveness can be secured in the radiation curable composition.

  As the above formula (1), preferably hydroxymethyl methacrylate, dihydroxymethyl methacrylate, hydroxyethyl methacrylate, dihydroxyethyl methacrylate, trihydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, 1-hydroxyethyl methacrylate, hydroxypropyl methacrylate, dihydroxypropyl methacrylate, Trihydroxypropyl methacrylate, 1-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, hydroxybutyl methacrylate, dihydroxybutyl methacrylate, trihydroxybutyl methacrylate, 1-hydroxybutyl methacrylate, 2-hydroxybutyl methacrylate, 3 Hydroxybutyl methacrylate, 4-hydroxylbutyl methacrylate, carboxymethyl methacrylate, dicarboxymethyl methacrylate, carboxyethyl methacrylate, dicarboxyethyl methacrylate, tricarboxyethyl methacrylate, 2-carboxyethyl methacrylate, 1-carboxyethyl methacrylate, carboxypropyl methacrylate, di Carboxypropyl methacrylate, tricarboxypropyl methacrylate, 1-carboxypropyl methacrylate, 2-carboxypropyl methacrylate, 3-carboxypropyl acrylate, carboxybutyl methacrylate, dicarboxybutyl methacrylate, tricarboxybutyl methacrylate, 1-carboxybutyl methacrylate 2-carboxybutyl methacrylate, 3-carboxybutyl methacrylate, 4-carboxylbutyl methacrylate, methacryloyloxyethyl-succinic acid, 2-methacryloyloxyethyl-succinic acid, methacryloyloxymethyl-succinic acid, methacryloyloxybutyl- Succinic acid, methacryloyloxypropyl-succinic acid, 2-methacryloyloxyethyl acid phosphate, methacryloyloxyethyl acid phosphate, methacryloyloxymethyl acid phosphate, methacryloyloxybutyl acid phosphate, methacryloyloxypropyl acid Dophosphate, methacryloyloxymethyl isocyanate, methacryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, hydroxy Cymethyl acrylate, dihydroxymethyl acrylate, hydroxyethyl acrylate, dihydroxyethyl acrylate, trihydroxyethyl acrylate, 2-hydroxyethyl acrylate, 1-hydroxyethyl acrylate, hydroxypropyl acrylate, dihydroxypropyl acrylate, trihydroxypropyl acrylate, 1-hydroxypropyl Acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, hydroxybutyl acrylate, dihydroxybutyl acrylate, trihydroxybutyl acrylate, 1-hydroxybutyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, 4-hydroxylbutyl acrylate , Cal Xymethyl acrylate, dicarboxymethyl acrylate, carboxyethyl acrylate, dicarboxyethyl acrylate, tricarboxyethyl acrylate, 2-carboxyethyl acrylate, 1-carboxyethyl acrylate, carboxypropyl acrylate, dicarboxypropyl acrylate, tricarboxypropyl acrylate, 1 -Carboxypropyl acrylate, 2-carboxypropyl acrylate, 3-carboxypropyl acrylate, carboxybutyl acrylate, dicarboxybutyl acrylate, tricarboxybutyl acrylate, 1-carboxybutyl acrylate, 2-carboxybutyl acrylate, 3-carboxybutyl acrylate, 4 -Carboxyl butyl acrylate, Acryloyloxyethyl-succinic acid, 2-acryloyloxyethyl-succinic acid, acryloyloxymethyl-succinic acid, acryloyloxybutyl-succinic acid, acryloyloxypropyl-succinic acid, 2-acryloyloxyethyl acid Phosphate, acryloyloxyethyl acid phosphate, acryloyloxymethyl acid phosphate, acryloyloxy butyl acid phosphate, acryloyloxypropyl acid phosphate, acryloyloxymethyl isocyanate, acryloyloxyethyl isocyanate, 2-acryloyl Loxyethyl isocyanate, hydroxymeth (acrylicyloxypropyl) methacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, 2-hydroxy-3-actyl Liloyloxypropyl acrylate, hydroxymeta (a) acryloyloxyethyl meta (a) acrylate, hydroxy meta (a) acryloyl butyl meta (a) acrylate, hydroxy meta (a) acryloyloxypentyl meta (a) acrylate, etc. It is.

  From the viewpoints of polymerization rate and adhesiveness, acrylates are more preferable in the above formulas (1) and (3), and the production rate of the polarizing plate is improved by using the acrylates of the above formulas (1) and (3). Can be made. In the above formula (1), n is more preferably 1 from the viewpoint of adhesiveness.

  In the radiation curable composition, the content of the above formula (1) needs to be 60% by weight or more, preferably 70% or more, more preferably 80% or more, and most preferably 90% or more. . In addition to the above formula (1), a photoinitiator, a photoinitiator assistant, a crosslinking agent, a (meth) acrylate other than the above formula (1), and the like may be contained.

  In particular, it is preferable that a photoinitiator is contained when the radiation curable composition is cured by light such as ultraviolet rays. The amount of photoinitiator is preferably 0.1 to 10% by weight, more preferably 0.2 to 7% by weight, and still more preferably 0.5 to 5% with respect to 100% by weight of the radiation curable composition. % By weight, most preferably 1 to 4% by weight.

  As the photoinitiator, those usually used in this field can be used. For example, acetophenone initiator, benzoin initiator, benzophenone initiator, thioxanthone initiator, s-triazine initiator, etc. Initiators and the like.

  Here, specific examples of the photoinitiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Benzyldimethyl ketal, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (Methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-hydroxy-2-methyl-1- [4 -(1-Methylvinyl) phenyl] propan-1-one oligomer, benzoin, benzoin methyl ether, benzoin ethyl ether Ter, benzoin isopropyl ether, benzoin isobutyl ether, benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 3,3 ′, 4,4′-tetra (tert-butyl) Peroxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2, 4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (4-methoxynaphthyl) -1,3,5- Triazine, 2, -Bis (trichloromethyl) -6-piperonyl-1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (4-methoxystyryl) -1,3,5-triazine, 2,4- Bis (trichloromethyl) -6- [2- (5-methylfuran-2-yl) ethenyl] -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- [2- (furan- 2-yl) ethenyl] -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (4-diethylamino-2-methylstyryl) -1,3,5-triazine, 2,4- Bis (trichloromethyl) -6- (3,4-dimethoxystyryl) -1,3,5-triazine, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,2′-bis (o-chlorophenyl) ) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, benzyl, 9,10-phenanthrenequinone, camphor Quinone, methyl phenylglyoxylate, titanocene compound, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one, Phenylglyoxylic acid methyl ester, 2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one, bis (2,6- Dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide is preferably used.

  The surface of the protective film to which the polarizing film is not adhered may have a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the protective film itself, or can be provided separately from the protective film as an optical layer.

<Production method of polarizing film>
The polarizing film can be produced by a known method. The polarizing film is mainly formed from a polyvinyl alcohol resin. The polarizing film is a uniaxially stretched film obtained by dyeing a polyvinyl alcohol resin film with a dichroic substance (typically iodine or a dichroic dye). The polymerization degree of the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film is preferably 100 to 5000, and more preferably 1400 to 4000. If the degree of polymerization is too low, the film tends to be stretched when performing predetermined stretching, and if the degree of polymerization is too high, tension may be abnormally required for stretching, and mechanical stretching may not be possible.

  The polyvinyl alcohol-based resin film constituting the polarizing film can be formed by any appropriate method (for example, a casting method in which a solution obtained by dissolving a resin in water or an organic solvent is cast, a casting method, an extrusion method). Although the thickness of a polarizing film is suitably set according to the objective and use of the liquid crystal display device in which a polarizing plate is used, it is about 5-80 micrometers normally.

  As a manufacturing method of the polarizing film, any appropriate method is adopted depending on the purpose, material used, conditions and the like. For example, the system which uses the said polyvinyl alcohol-type resin film for a series of manufacturing processes including a swelling, dyeing | staining, bridge | crosslinking, extending | stretching, a water washing, and a drying process is employ | adopted normally. In each processing step except the drying step, the treatment is performed by immersing the polyvinyl alcohol-based resin film in a liquid containing a solution used in each step. The order, number of times, and presence / absence of each treatment of swelling, dyeing, crosslinking, stretching, washing and drying can be appropriately set according to the purpose, materials used and conditions. For example, several processes may be performed simultaneously in one step, and the swelling process, the dyeing process, and the crosslinking process may be performed simultaneously. Further, for example, it can be suitably employed to perform the crosslinking treatment before and after the stretching treatment. For example, the water washing process may be performed after all the processes, or may be performed only after a specific process.

  The swelling step is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath filled with water. By this treatment, dirt on the surface of the polyvinyl alcohol-based resin film and an anti-blocking agent can be washed, and unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based resin film. Glycerin, potassium iodide or the like is appropriately added to the swelling bath. The temperature of the swelling bath is usually about 20 to 60 ° C., and the immersion time in the swelling bath is usually about 0.1 to 10 minutes.

  The dyeing process is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath containing a dichroic substance such as iodine. As the solvent used for the dye bath solution, water is generally used, but an appropriate amount of an organic solvent compatible with water may be added. A dichroic substance is normally used in the ratio of 0.1-1 weight part with respect to 100 weight part of solvents. When iodine is used as the dichroic substance, the dye bath solution preferably further contains an auxiliary agent such as iodide. This is because the dyeing efficiency is improved. The auxiliary is preferably used in a proportion of 0.02 to 20 parts by weight, more preferably 2 to 10 parts by weight, with respect to 100 parts by weight of the solvent. Specific examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The temperature of the dyeing bath is usually about 20 to 70 ° C., and the immersion time in the dyeing bath is usually about 1 to 20 minutes.

  The crosslinking step is typically performed by immersing the dyed polyvinyl alcohol-based resin film in a treatment bath containing a crosslinking agent (hereinafter sometimes abbreviated as a crosslinking bath). Arbitrary appropriate crosslinking agents are employ | adopted as a crosslinking agent. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used alone or in combination. As the solvent used for the solution of the crosslinking bath, water is generally used, but an appropriate amount of an organic solvent having compatibility with water may be added. A crosslinking agent is normally used in the ratio of 1-10 weight part with respect to 100 weight part of solvents. When the concentration of the crosslinking agent is less than 1 part by weight, sufficient optical properties cannot be obtained. When the concentration of the cross-linking agent exceeds 10 parts by weight, the stress generated in the film during stretching increases, and the resulting polarizing plate may shrink. It is desirable that the solution of the crosslinking bath further contains an auxiliary agent such as iodide. This is because it is easy to obtain uniform characteristics in the plane. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. Specific examples of iodide are the same as those in the dyeing process. The temperature of the crosslinking bath is usually about 20 to 70 ° C, preferably 40 to 60 ° C. The immersion time in the crosslinking bath is usually about 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

  The polarizing film stretching step may be performed at any stage as described above. Specifically, it may be performed after the dyeing process, may be performed before the dyeing process, may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process, or may be performed after the crosslinking process. The cumulative draw ratio of the polyvinyl alcohol-based resin film is usually 5 times or more. Preferably it is 5 to 7 times, more preferably 5 to 6.5 times. When the cumulative draw ratio is less than 5 times, it is difficult to obtain a polarizing plate having a high degree of polarization. When the cumulative draw ratio exceeds 7 times, the polyvinyl alcohol-based resin film may be easily broken. Arbitrary appropriate methods are employ | adopted as a specific method of extending | stretching. For example, when a wet stretching method is employed, a polyvinyl alcohol resin film is stretched at a predetermined magnification in a treatment bath. As the stretching bath solution, a solution in which various metal salts, iodine, boron or zinc compounds are added to a solvent such as water or an organic solvent (for example, ethanol) is preferably used.

  The water washing step is typically performed by immersing the polyvinyl alcohol-based resin film subjected to the above-described various treatments in a treatment bath. The unnecessary residue of the polyvinyl alcohol-based resin film can be washed away by the water washing step. The washing bath may be pure water or an aqueous solution of iodide (eg, potassium iodide, sodium iodide, etc.). The concentration of the aqueous iodide solution is preferably 0.1 to 10% by weight. An auxiliary agent such as zinc sulfate or zinc chloride may be added to the aqueous iodide solution. The temperature of the water washing bath is preferably 10 to 60 ° C, more preferably 30 to 40 ° C. The immersion time is 1 second to 1 minute. The washing step may be performed only once, or may be performed a plurality of times as necessary. When implemented several times, the kind and density | concentration of the additive contained in the washing bath used for each process are adjusted suitably. For example, the water washing step includes a step of immersing the polyvinyl alcohol resin film subjected to the above various treatments in an aqueous potassium iodide solution (0.1 to 10% by weight, 10 to 60 ° C.) for about 1 second to 1 minute, and pure water. Including rinsing process. Further, in the water washing step, an organic solvent (for example, ethanol) having compatibility with water may be appropriately added in order to improve the surface of the polarizing film and increase the drying efficiency of the polarizing film.

  Arbitrary appropriate methods (For example, natural drying, ventilation drying, heat drying) may be employ | adopted for a drying process. For example, the drying temperature in the case of heat drying is usually about 20 to 80 ° C., and the drying time is usually about 1 to 10 minutes. A polarizing film is obtained as described above.

The polarizing film used in the present invention has a moisture content of preferably 15% by weight or less, more preferably 0 to 14% by weight, and further preferably 1 to 14% by weight. When the moisture content is larger than 15% by weight, the dimensional change of the obtained polarizing plate becomes large, and there may be a problem that the dimensional change under high temperature or high temperature and high humidity becomes large.
What is necessary is just to adjust the moisture content of the polarizing film of this invention by arbitrary appropriate methods. For example, there is a method of controlling by adjusting the conditions of the drying step in the production process of the polarizing film.

<Production method of polarizing plate>
The polarizing plate of the present invention is produced by bonding a protective film and a polarizing film with the radiation curable composition interposed therebetween. The manufacturing method includes a step of applying the radiation curable composition to a surface of the polarizing film on which the adhesive layer is formed and / or a surface of the protective film on which the adhesive layer is formed; a polarizing film and a protective film; Are bonded to each other via the radiation curable composition; and the polarizing film and the protective film bonded together via the radiation curable composition are cured by irradiation with radiation, It is preferable to include the process to do. The polarizing plate may be produced by batch or roll-to-roll, but roll-to-roll is preferable in consideration of productivity.

The adhesive coating method is appropriately selected depending on the viscosity of the adhesive and the target thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, and the like. In addition, for coating, a method such as a dapping method can be appropriately used.
The polarizing film and the protective film are bonded together via the adhesive applied as described above. The polarizing film and the protective film can be bonded together using a roll laminator or the like.

After laminating the polarizing film and the protective film, radiation is irradiated to cure the adhesive. As radiation, ultraviolet rays and / or electron beams are preferably used, and ultraviolet rays are preferred.
The viscosity of the radiation curable adhesive composition is preferably 0.1 to 5000 mPa · s, more preferably 0.5 to 1000 mPa · s, and still more preferably 1 to 500 mPa · s.

  As thickness of the adhesive after hardening, 0.1-10 micrometers is preferable, More preferably, it is 0.3-7 micrometers, More preferably, it is 0.5-5 micrometers. When the adhesive thickness is less than 0.1 μm, sufficient adhesive strength may not be obtained, and when it is greater than 10 μm, it is difficult to apply uniformly, resulting in poor appearance of the polarizing plate. There is.

  As a light source in the case of using ultraviolet rays, a known low-pressure mercury lamp, high-pressure mercury lamp, ultrahigh-pressure mercury lamp, xenon lamp, metal halide lamp, excimer lamp, light-emitting diode, or the like is preferably used. Polylactic acid absorbs light at a wavelength of 250 nm or less, but when irradiated with intense light in this wavelength region, decomposition may occur due to the reaction mechanism of the formula (6). Therefore, it is preferable to cut the ultraviolet light having a wavelength of 270 nm or less to cure the radiation curable composition. More preferably, the wavelength is 280 nm or less, more preferably the wavelength is 280 nm or less, and most preferably, the wavelength is 300 nm or less. The ultraviolet ray can be cut by a known method. For example, an appropriate selection of an ultraviolet light source or an ultraviolet ray cut filter can be used.

As an intensity | strength of ultraviolet light, 10-1000 mW / cm < ² > is preferable, More preferably, it is 20-700 mW / cm < ² >, More preferably, it is 30-500 mW / cm < ² >. If it is less than 10 mW / cm ² , it takes too much time to cure, resulting in poor productivity. If it is greater than 1000 mW / cm ² , the polarizing performance of the polarizing film may be deteriorated by heat. Further, as the integrated light quantity is preferably from 100~10000mJ / cm ^2, more preferably 200~5000mJ / cm ^2, more preferably from 300~3000mJ / cm ^2. Is less than 100 mJ / cm ² may become insufficient curing, and when greater than 10000 mJ / cm ² may polarization performance of the polarizing film is deteriorated by heat. The irradiation direction of the ultraviolet light may be from one side or both sides of the polarizing plate.

  When the radiation curable composition is cured with light such as ultraviolet rays, the protective film contains an ultraviolet absorber and when the ultraviolet rays are irradiated from the protective film side, the photoinitiator of the radiation curable composition It is preferable to appropriately select the photoinitiation reaction wavelength of which is longer than the ultraviolet absorption wavelength region of the protective film. That is, the radiation curable composition preferably contains a photoinitiator that performs an initiation reaction with light having a wavelength of 380 nm or longer. This is because, as described above, a preferable light transmittance when it is necessary to add an ultraviolet absorber to the protective film is 20% or less at a wavelength of 380 nm, and a light transmittance at a wavelength of 375 nm is 1% or less. . For example, among the aforementioned photoinitiators, those having an extinction coefficient (ml / (g · cm)) at a wavelength of 405 nm of 1 or more, preferably 10 or more, more preferably 100 or more can be preferably used. This extinction coefficient can be measured by, for example, a spectroscope after dissolving a photoinitiator in a methanol solvent or the like.

  Such photoinitiators are preferably bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2 , 4,6-trimethylbenzoyl-diphenyl-phosphine oxide, mixture of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone, 2,4,6 A mixture of trimethylbenzoyl-diphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one, and the like.

  In the case of using an electron beam as radiation, the irradiation direction of the electron beam can be applied from any appropriate direction. Preferably, it irradiates from the protective film side. When irradiated from the polarizing film side, the polarizing film may be deteriorated by the electron beam.

  Any appropriate condition can be adopted as the electron beam irradiation condition as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and may be insufficiently cured. If the acceleration voltage exceeds 300 kV, the penetrating force through the sample is too strong and the electron beam bounces off, causing a protective film or polarized light. There is a risk of damaging the membrane. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficiently cured, and when it exceeds 100 kGy, the protective film and the polarizing film are damaged, resulting in a decrease in mechanical strength and yellowing, thereby obtaining predetermined optical characteristics. Can not.

  When performing the said manufacturing method with a continuous line, although depending on the hardening time of an adhesive agent, Preferably it is 1-500 m / min, More preferably, it is 5-300 m / min, More preferably, it is 10-100 m / min. is there. If the line speed is too low, productivity is poor. When the line speed is too high, the adhesive is not sufficiently cured, and the target adhesiveness may not be obtained.

  Although a heat treatment step may be provided after the bonding step, the heat treatment temperature is preferably 40 to 100 ° C, more preferably 50 to 85 ° C. If it is less than 40 degreeC, there is little effect as a heat treatment process, and if it exceeds 100 degreeC, a polarizing film may deteriorate. The heat treatment time is preferably about 5 seconds to 10 minutes. If it is less than 5 seconds, the effect of heat treatment cannot be expected, and if it exceeds 10 minutes, there may be a problem in productivity.

  The adhesive peel strength between the polarizing film and the protective film is preferably 2 N / 25 mm or more in the 90 ° peel test, more preferably 3 N / 25 mm or more, still more preferably 4 N / 25 mm or more, and most preferably 5 N / 25 mm or more. . When the 90 ° C. peel strength is less than 2 N / 25 mm, there may be a problem in practical use of the polarizing plate. In the present invention, unless otherwise specified, the peel rate in the peel strength evaluation was 200 mm / min, and the film width was 25 mm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention does not receive any limitation by this.

(Evaluation methods)
(1) Weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer:
The weight average molecular weight and number average molecular weight of the polymer were measured by gel permeation chromatography (GPC) and converted to standard polystyrene. GPC measuring instrument is detector; differential refractometer (manufactured by Shimadzu Corporation) RID-6A column; Toso-Co., Ltd. TSKgel G3000HXL, TSKgel G4000HXL, TSKgel G5000HXL and TSKguardcocumHXL-L TSKgel G2000HXL, TSKgelG3000HXL, and TSKguardcocumHXL-L connected in series were used.
Chloroform was used as an eluent, 10 μl of a sample having a concentration of 1 mg / ml (chloroform containing 1% hexafluoroisopropanol) was injected at a temperature of 40 ° C. and a flow rate of 1.0 ml / min.

(2) DSC measurement such as degree of stereo [S (%)], crystal melting temperature, etc .:
Using DSC (TA Instrument, TA-2920), the sample was heated to 250 ° C. at 10 ° C./min under a nitrogen stream in the first cycle, and the glass transition temperature (Tg), stereocomplex phase poly Lactic acid crystal melting temperature (Tm *), stereocomplex phase polylactic acid crystal melting enthalpy (ΔHms) and homophase polylactic acid crystal melting enthalpy (ΔHmh) were measured.
In addition, the crystallization start temperature (Tc *) and the crystallization temperature (Tc) were measured by rapidly cooling the measurement sample and then performing a second cycle measurement under the same conditions. The degree of stereogenicity is a value determined by the following formula (ii) from the stereocomplex phase and homophase polylactic acid crystal melting enthalpy obtained by the above measurement.
S = [ΔHms / (ΔHmh + ΔHms)] × 100 (ii)
(However, ΔHms is the melting enthalpy of complex phase crystals, ΔHmh is the melting enthalpy of homophase polylactic acid crystals)

(3) End group concentration measurement of formula (2):
The terminal group concentration of the formula (2) was measured using a 500 MHz high resolution nuclear magnetic resonance apparatus ( ¹ H-NMR: equipment name ECA-500 manufactured by JEOL Ltd.). The sample was dissolved using deuterated chloroform as a solvent, and the equivalent / ton of the functional group was determined from the peak intensity around the chemical shift of 5.8 to 6.5. A bulk average density | concentration is a bulk average density | concentration of the end group of the said Formula (2) in the whole protective film. On the other hand, regarding the concentration of the terminal group of the above formula (2) in the vicinity of the adhesive interface on the polarizing film side, a 2 μm resin was cut out from the interface toward the center with a knife or the like and evaluated in the same manner as the bulk. The results are shown in Table 2. In the table, “surface” is the concentration of the end group of the above formula (2) on this surface, and “bulk” indicates this bulk average concentration.

(4) Thickness measurement:
The measurement was made with an electronic micrometer manufactured by Anritsu Corporation.

(5) Measurement of retardation value (Re) and thickness direction retardation value (Rth):
The phase difference Re value and Rth, which are products of birefringence Δn and film thickness d, were measured by a trade name “M150” manufactured by JASCO Corporation, which is a spectroscopic ellipsometer. The Re value was measured with the incident light beam and the film surface orthogonal. The Rth value (nm) is a three-dimensional refractive index obtained by measuring the phase difference value at each angle by changing the angle between the incident light beam and the film surface, and curve fitting with a known refractive index ellipsoid equation. Nx, ny, and nz were obtained.

(6) Polarization degree measurement:
Two polarizing plates (3 cm × 4 cm) are cut out, and the parallel transmittance Y _/// and the orthogonal transmittance Y _直交 of the two polarizing plates are changed to a product name “U-4000” manufactured by Hitachi, Ltd. which is a spectroscope. The degree of polarization (P (%)) was determined using the following formula (11). The transmittance referred to here is parallel light transmittance, and the Y value of the CIE XYZ color system in a 2 ° visual field C light source was used.

(7) Adhesive Peel Strength Test In order to evaluate the adhesive force between the polarizing film and the protective film, a 90 ° peel test was performed using a product name “5500R” of a tensile tester manufactured by Instron. The peeling speed was 200 mm / min. Moreover, although the peeling surface exists in two places, front and back, the peeling strength (Table 4) mentioned later described the average value of both. However, only Example 15 describes only the peel strength between the protective film 2 and the polarizing film. In the measurement, a polarizing plate is attached to a glass plate with an adhesive, the adhesive layer on the side to be measured is on the side opposite to the glass plate, and the peel strength is maintained while maintaining the protective film on the outermost surface at 90 ° to the glass substrate. Was measured.

(8) Measurement of parallel light transmittance of protective film:
The parallel light transmittance of the protective film was measured with a trade name “U-4000” manufactured by Hitachi, Ltd., which is a spectroscope. Table 1 shows the parallel light transmittances T ₃₈₀ , T ₄₀₅ , and T ₅₀₀ at wavelengths of ₃₈₀ , ₄₀₅ , and ₅₀₀ nm.

(9) Measurement of extinction coefficient of photoinitiator:
The extinction coefficient at 405 nm of the photoinitiator was evaluated under the trade name “U-4000” manufactured by Hitachi, Ltd. using a quartz cell with a solvent of acetonitrile and an optical path length of 1 cm. The results are shown in Table 3. In the present invention, trade names “Irgacure 184”, “Irgacure 819”, and “Irgacure 1870” manufactured by Ciba Geigy are referred to as I184, I819, and I1870, respectively. I819 and I1870 absorb even light having a wavelength of 400 nm or more to cause a polymerization initiation reaction.

(10) Total light transmittance and haze measurement:
The total light transmittance (%) and haze value (%) were evaluated using the brand name “COH-300A” manufactured by Nippon Denshoku Industries Co., Ltd.

(11) Identification of cyclic carbodiimide structure by nuclear magnetic resonance (NMR) and determination of cyclic carbodiimide in polyester composition:
The synthesized cyclic carbodiimide compound was confirmed by ¹ H-NMR and ¹³ C-NMR. For NMR, a trade name “JNR-EX270” manufactured by JEOL Ltd. was used. Deuterated chloroform was used as the solvent.

(12) Identification of carbodiimide skeleton of cyclic carbodiimide by infrared spectroscopy (IR):
The presence or absence of the carbodiimide skeleton of the synthesized cyclic carbodiimide compound was confirmed by FT-IR at 2100-2200 cm ⁻¹ characteristic of carbodiimide. For FT-IR, a trade name “Magna-750” manufactured by Thermo Nicolay Co., Ltd. was used.

[Reference example]
<Production of cyclic carbodiimide (TX-1)>
o- nitrophenol (0.11 mol) and pentaerythrityl tetra bromide (0.025 mol), potassium carbonate _{(0.33mol), N, N- N} 2 dimethylformamide 200ml in reactor installed with a stirrer and a heating device After charging in an atmosphere and reacting at 130 ° C. for 12 hours, DMF was removed under reduced pressure, and the resulting solid was dissolved in 200 ml of dichloromethane and separated three times with 100 ml of water. The organic layer was dehydrated with 5 g of sodium sulfate, and dichloromethane was removed under reduced pressure to obtain an intermediate product D (nitro form).

  Next, intermediate product D (0.1 mol), 5% palladium carbon (Pd / C) (2 g), and 400 ml of ethanol / dichloromethane (70/30) were charged into a reactor equipped with a stirrer, and 5 hydrogen substitution was performed. The reaction was performed in a state where hydrogen was constantly supplied at 25 ° C., and the reaction was terminated when there was no decrease in hydrogen. When Pd / C was recovered and the mixed solvent was removed, an intermediate product E (amine body) was obtained.

Next, triphenylphosphine dibromide (0.11 mol) and 150 ml of 1,2-dichloroethane were charged and stirred in a reactor equipped with a stirring device, a heating device, and a dropping funnel in an N ₂ atmosphere. A solution prepared by dissolving the intermediate product E (0.025 mol) and triethylamine (0.25 mol) in 50 ml of 1,2-dichloroethane was gradually added dropwise thereto at 25 ° C. After completion of dropping, the reaction is carried out at 70 ° C. for 5 hours. Thereafter, the reaction solution was filtered, and the filtrate was separated 5 times with 100 ml of water. The organic layer was dehydrated with 5 g of sodium sulfate, and 1,2-dichloroethane was removed under reduced pressure to obtain an intermediate product F (triphenylphosphine compound).

Next, in a reactor equipped with a stirrer and a dropping funnel, di-tert-butyl dicarbonate (0.11 mol), N, N-dimethyl-4-aminopyridine (0.055 mol), dichloromethane under N ₂ atmosphere. 150 ml is charged and stirred. Thereto, 100 ml of dichloromethane in which the intermediate product F (0.025 mol) was dissolved was slowly added dropwise at 25 ° C. After dropping, react for 12 hours. Then, the solid substance obtained by removing dichloromethane was purified to obtain a cyclic carbodiimide compound (abbreviated as TX-1) having a structure shown below (molecular weight: 516). The structure of TX-1 was confirmed by NMR and IR.

<Manufacture of polylactic acid>
Polylactic acid was prepared as follows.
(1) Production of poly L-lactic acid (PLLA1):
To 100 parts by weight of L-lactide (manufactured by Musashino Chemical Laboratory, Inc., optical purity 100%), 0.005 part by weight of octylate is added, and 180 ° C. in a reactor equipped with a stirring blade in a nitrogen atmosphere. Then, 1.2 times equivalent of phosphoric acid with respect to tin octylate was added, and then the remaining lactide at 13.3 Pa was removed under reduced pressure to form a chip to obtain poly L-lactic acid (PLLA1).
The obtained poly L-lactic acid (PLLA1) had a weight average molecular weight of 152,000, a glass transition point (Tg) of 55 ° C., and a melting point of 175 ° C.

(2) Production of poly-D-lactic acid (PDLA1):
In the production of PLLA1, polymerization was carried out under the same conditions except that L-lactide was changed to D-lactide (manufactured by Musashino Chemical Laboratory, Inc., optical purity 100%) to obtain poly D-lactic acid (PDLA1). .
The obtained poly-D-lactic acid (PDLA1) had a weight average molecular weight (Mw) of 151,000, a glass transition point (Tg) of 55 ° C., and a melting point of 175 ° C.

(3) Production of stereocomplex polylactic acid (SCPLA1):
50 parts by weight of PLLA1 and PDLA1 obtained by the above operation and a metal phosphate (“ADEKA STAB” NA-71: 0.1 part by weight, manufactured by ADEKA Corporation) are supplied to the first supply port of the biaxial kneader. The mixture was melted and kneaded at a cylinder temperature of 250 ° C. to obtain stereocomplex polylactic acid (SCPLA1). The glass transition point (Tg) was 55 ° C. and the melting point was 216 ° C.

(4) Production of blend resin (SP1) of stereocomplex polylactic acid and polymethyl methacrylate (PMMA):
After blending 80 parts by weight and 20 parts by weight of a product name “Acrypet VH001” which is SPLLA1 obtained by the above operation and PMMA made by Mitsubishi Rayon Co., Ltd. with a blender, 110 ° C. and vacuum drying for 5 hours, kneading From the first supply port of the machine, melt kneading while evacuating at a cylinder temperature of 230 ° C. and a vent pressure of 13.3 Pa, extruding the strand into a water tank, chipping with a chip cutter, and blending composition of SPLLA1 and PMMA (SP1) Got. The glass transition point (Tg) was 59 ° C. and the melting point was 216 ° C.

(5) Production of blend resin (SPT1) of stereocomplex polylactic acid, polymethyl methacrylate (PMMA) and cyclic carbodiimide (TX-1):
SCPLA1 obtained by the above operation, PMMA made by Mitsubishi Rayon Co., Ltd., trade name “Acrypet VH001”, and cyclic carbodiimide (TX1) are mixed by 80 parts by weight, 20 parts by weight, and 1 part by weight with a blender, 110 ° After vacuum drying for 5 hours, supply from the first supply port of the kneading machine, melt kneading while evacuating at a cylinder temperature of 230 ° C and a vent pressure of 13.3 Pa, extruding the strand into a water tank, and tipping with a chip cutter To obtain a blend composition (SPT1). The glass transition point (Tg) was 59 ° C. and the melting point was 216 ° C.

(6) Production of blend resin (SPTV1) of stereocomplex polylactic acid, polymethyl methacrylate (PMMA), cyclic carbodiimide (TX1), and UV absorber (UV1):
SPLLA 1 obtained by the above operation, trade name “Acrypet VH001” which is PMMA made by Mitsubishi Rayon Co., Ltd., cyclic carbodiimide (TX-1), ultraviolet light which is trade name “Seesorb 107” made by Cypro Kasei Co., Ltd. The absorbent 2,2′-dihydroxy-4,4′-dimethoxybenzophenone was mixed with 80 parts by weight, 20 parts by weight, 0.8 parts by weight and 0.9 parts by weight, respectively, and dried in a vacuum at 110 ° C. for 5 hours. Thereafter, the mixture is supplied from the first supply port of the kneading machine, melted and kneaded while evacuating at a cylinder temperature of 230 ° C. and a vent pressure of 13.3 Pa, extruded into a water tank, chipped with a chip cutter, and blended composition (SPTV1 ) The glass transition point (Tg) was 58 ° C. and the melting point was 215 ° C.

(7) Production of blend resin (STV1) of stereocomplex polylactic acid, cyclic carbodiimide (TX-1), and ultraviolet absorber (UV1):
Ultraviolet absorber 2,2′-dihydroxy which is SPLLA1, trade name “Acrypet VH001”, PMMA made by Mitsubishi Rayon Co., Ltd., cyclic carbodiimide (TX1), trade name “Seasorb 107” made by Cypro Kasei Co., Ltd. -4,4'-dimethoxybenzophenone 80 parts by weight, 20 parts by weight, 0.8 parts by weight and 0.9 parts by weight were mixed with a blender, dried at 110 ° C. for 5 hours, and then supplied to the first kneader. It was supplied from the mouth, melted and kneaded while evacuating at a cylinder temperature of 230 ° C. and a vent pressure of 13.3 Pa, extruded into a water tank, and chipped with a chip cutter to obtain a blend composition (STV1). The glass transition point (Tg) was 58 ° C. and the melting point was 215 ° C.

<Manufacture of protective film>
(1) Production of protective film (F1):
The resin SPT1 was dried at 100 ° C. for 5 hours, melted and kneaded in an extruder at 225 ° C., melt-extruded in a film form from a T-die at a die temperature of 225 ° C., closely adhered to the surface of the cooling drum at 40 ° C., and solidified. A stretched film was obtained. The film thickness was 43 μm. Thereafter, this unstretched film was stretched at a stretching temperature of 75 ° C. and a magnification of 1.05 times with a tenter horizontal uniaxial stretching machine, and then heat-set at 115 ° C. with the same equipment, whereby a protective film having a thickness of 41 μm. (F1) was obtained.

(2) Production of protective film with retardation function (F2):
An unstretched film was obtained using resin SPT1 in the same manner as in Film Production Example 1. The film thickness was 60 μm. Thereafter, the unstretched film was stretched at a stretching temperature of 75 ° C. and a magnification of 1.4 times with a tenter horizontal uniaxial stretching machine, and then heat-fixed at 115 ° C. with the same equipment to obtain a protective film having a thickness of 41 μm. (F2) was obtained.

(3) Production of protective film (F3):
A protective film (F3) having a thickness of 41 μm was obtained in the same manner as in Film Production Example 1 except that the resin SP1 was used.

(4) Production of protective film (F4):
A protective film (F2) having a thickness of 41 μm was obtained in the same manner as in Film Production Example 1 except that the resin SPTV1 was used.

(5) Production of protective film (F5):
A protective film (F5) having a thickness of 41 μm was obtained in the same manner as in Film Production Example 1 except that the resin STV1 was used and the heat setting temperature in the tenter transverse uniaxial stretching machine was 105 ° C.
Table 1 shows the optical characteristics of the protective films F1 to F5.

<Surface treatment of protective film>
For the surface treatment of the protective film, corona treatment discharge or ultraviolet ozone treatment was used. The corona discharge treatment was performed under the condition of 70 W · min / m ² using a corona surface treatment apparatus manufactured by Kasuga Electric Co., Ltd. In addition, the ultraviolet ozone treatment was performed using a product name “eye ozone cleaning apparatus OC-2506” manufactured by Eye Graphics Co., Ltd., and the treatment time was 30 seconds. However, only in Example 9, the time of the ultraviolet ozone treatment was 1 minute. Table 2 shows the presence / absence and method of surface treatment in Examples and Comparative Examples. The above formula (2) end group concentration after the surface treatment is also shown in Table 2.

<Manufacture of polarizing film>
A polyvinyl alcohol film having a thickness of 80 μm was dyed in an iodine solution of 5% by weight (weight ratio: iodine / potassium iodide = 1/10) at 30 ° C. for 1 minute. Then, it is immersed in an aqueous solution containing 3% by weight boric acid and 2% by weight 30 ° C. potassium iodide for 1 minute, and further an aqueous solution at 60 ° C. containing 4% by weight boric acid and 3% by weight potassium iodide. The film was stretched up to 6 times while immersed in the medium for 1 minute, and then immersed in a 5 wt% potassium iodide aqueous solution at 30 ° C. for 1 minute. Then, it dried for 3 minutes in 80 degreeC oven, and obtained the polarizing film of thickness 30 micrometers.

[Examples 1 to 14]
In each Example, the protective film shown in Table 2 was used. Further, as shown in Table 2, except for Example 10, the surface of the polarizing film and the adhesive surface of the film were all subjected to surface treatment.
Using a coater equipped with a wire bar coater on both sides of the polarizing film, the radiation curable composition shown in Table 2 is applied and laminated in the arrangement of the protective film 1, the polarizing film, and the protective film 2. It bonded together using the laminator. In addition, all radiation curable compositions are liquid at normal temperature (25 degreeC), and the solvent is not used.

Subsequently, the bonded film is introduced into an ultraviolet curing device having a low-pressure mercury lamp in which a cut filter for cutting ultraviolet rays of 300 nm or less is installed, and light is irradiated from the protective film 1 side in an air atmosphere. And cured. The intensity of the irradiated light was measured by a trade name “UVPF-36” which is an ultraviolet illuminance meter manufactured by Eye Graphic Co., Ltd. The light intensity was 30 mW / cm ² and the integrated light amount was 1 J / cm ² . A polarizing plate was obtained which was adhered by a layer made of a cured product of a radiation curable composition having a thickness of 4 μm. That is, the obtained polarizing plate is formed by laminating the protective film 1, the adhesive layer, the polarizing film, the adhesive layer, and the protective film 2 in this order.
As shown in Table 4, it can be seen that in any of the Examples, the initial polarization degree and the peel strength are excellent, and the change is small even after 80 ° C. DRY 500 hours and 60 ° C. 90% RH 500 hours.

[Example 15]
As a protective film 1, a film made of a material containing polylactic acid was used on one surface, and a polarizing plate using TAC on the other surface was prepared as follows.
100 parts by weight of triacetyl cellulose, 12 parts by weight of triphenyl phosphate, 300 parts by weight of methylene chloride, and 50 parts by weight of methanol were put into a sealed container, kept at 80 ° C. under pressure, and completely dissolved while stirring. Next, this solution was filtered, cooled, kept at 30 ° C., and coated on a PET film attached to a glass substrate with an applicator. After leaving still in this state for 5 minutes, drying was further terminated in an oven at 100 ° C. for 1 hour to obtain a protective film (TAC1) having a film thickness of 40 μm.

Subsequently, TAC1 was immersed in a 2.6 mol / L aqueous sodium hydroxide solution at 40 ° C. for 50 seconds, then washed with water, dried and saponified. Thereafter, the saponified protective film TAC1 was laminated with TAC1 and the polarizing film using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive, dried at 80 ° C. for 3 minutes, and adhered to one side of the polarizing film.
About adhesion | attachment of the protective film on the opposite side on both sides of a polarizing film with TAC1, it implemented on the conditions described in Table 1 and Table 2 similarly to Example 1, and produced the polarizing plate.
In Table 4, it can be seen that the initial polarization degree and the peel strength are excellent, and the change is small even after 80 hours of DRY 500 hours and after 60 degrees C and 90% RH 500 hours.

[Comparative Examples 1, 2, 4 to 6]
A polarizing plate was produced in the same manner as in Example 1 except that the protective film described in Table 2 and the radiation curable composition were used. COP and PC, which are protective films in Table 2, are trade names “ZEONOR ZF14” made by Nippon Zeon Co., Ltd., which is made of an alicyclic olefin polymer, and Teijin Chemicals Ltd., which is made of a polycarbonate having a bisphenol A skeleton. An optically isotropic film with a trade name of “Pure Ace” is shown.
As shown in Table 4, it was found that all of them were poor in adhesive strength and unsuitable as a polarizing plate. Moreover, it turned out that an initial stage polarization degree is low compared with an Example.

[Comparative Example 3]
Implemented except that a completely saponified polyvinyl alcohol 5% aqueous solution was used as the adhesive instead of the radiation curable composition, and that the adhesive was cured by drying with heat (80 ° C. for 3 minutes). A polarizing plate was produced in the same manner as in Example 1.
As shown in Table 4, it was found that the adhesive strength was poor and it was not suitable as a polarizing plate. Moreover, it turned out that an initial stage polarization degree is low compared with an Example.

In Table 2, the abbreviations mean the following.
Corona discharge: Corona discharge treatment was performed as a surface treatment on the protective film adhesive layer side.
UV ozone: UV ozone treatment was performed as the surface treatment on the protective film adhesive layer side.
Saponification: A saponification treatment was performed as a surface treatment on the protective film adhesive layer side.
Surface: concentration (equivalent / ton) of formula (2) in the vicinity of the adhesive interface on the protective film polarizing film side
Bulk: concentration of the above formula (2) in the protective film bulk (equivalent / ton)
HA: Trade name “Light Ester HOP-A” manufactured by Kyoeisha Chemical Co., Ltd.
The main component is 2-hydroxypropyl acrylate.
AA: Trade name “Karenz AOI” manufactured by Showa Denko KK
Contains 97% or more of 2-acryloyloxyethyl isocyanate.
MM: Trade name “Karenz MOI” manufactured by Showa Denko KK
Contains 97% or more of 2-methacryloyloxyethyl isocyanate.
MA: Trade name “HOA-MA” manufactured by Kyoeisha Chemical Co., Ltd.
The main component is 2-acryloyloxyethyl-succinic acid.
PA: Trade name “Light Acrylate P-1A” manufactured by Kyoeisha Chemical Co., Ltd.
Mainly composed of 2-acryloyloxyethyl acid phosphate.
HM: Kyoeisha Chemical Co., Ltd. trade name “Light Ester HOP”
The main component is 2-hydroxypropyl methacrylate.
EM: Trade name “Light Ester HO-250” manufactured by Kyoeisha Chemical Co., Ltd.
Mainly 2-hydroxyethyl methacrylate.
EA: Trade name “Light Ester HOA” manufactured by Kyoeisha Chemical Co., Ltd.
The main component is 2-hydroxyethyl acrylate.
BA: Trade name “Light Acrylate HOB-A” manufactured by Kyoeisha Chemical Co., Ltd.
Mainly composed of 2-hydroxybutyl acrylate.
MMA: Trade name “Light Ester M” manufactured by Kyoeisha Chemical Co., Ltd.
Mainly methyl methacrylate.
PHA: Trade name “Light Acrylate PO-A” manufactured by Kyoeisha Chemical Co., Ltd.
The main component is phenoxyethyl acrylate.

DESCRIPTION OF SYMBOLS 1 Protective film made of material containing polylactic acid 2 Adhesive layer 3 Polarizing layer 4 Adhesive layer 5 Protective film made of material containing polylactic acid 6 Polarizing plate 21 Protective film made of material containing polylactic acid 22 Adhesive layer 23 Polarizing layer 24 Adhesive Layer 25 Protective film 26 made of a material not containing polylactic acid Polarizing plate 31 Protective film 32 made of a material containing polylactic acid Adhesive layer 33 Polarizing layer 34 Polarizing plate 41 Polarizing plate 42 Adhesive layer 43 Liquid crystal cell 44 Adhesive layer 45 Polarizing plate

Claims (11)

A polarizing plate in which a protective film made of a material containing polylactic acid is laminated on at least one surface of a polarizing film via an adhesive layer, and the adhesive layer cures a radiation curable composition containing the following formula (1) A polarizing plate characterized by being made.

(In the formula (1), n represents 1 or 2, R ²⁰ represents a hydrogen atom or a methyl group, and R ²¹ represents an alkylene group having 1 to 10 carbon atoms (1 or 2 present in the alkylene group). One or more methylene groups may be each independently substituted with an oxygen atom, —CO—, —COO— or —OCO—, as oxygen atoms are not directly bonded to each other, and are present in the alkylene group. 1 or 2 or more hydrogen atoms are each substituted with a hydroxyl group, a carboxyl group, an isocyanate group, an aldehyde group, or a phosphate group.) The polarizing plate according to claim 1, wherein the polylactic acid is a polylactic acid composed of a poly-D-lactic acid component and a poly-L-lactic acid component, and the stereocomplex crystallinity (S) is 90% or more.
{Stereocomplex crystallinity (S) is 190 ° C measured by differential scanning calorimetry (DSC)
The polylactic acid homocrystal melting heat (ΔHmh) observed below and the polylactic acid stereocomplex crystal melting heat (ΔHmsc) observed at 190 ° C. or higher were obtained by the following formula (i).
(S) = [ΔHmsc / (ΔHmh + ΔHmsc)] × 100 (i)} The polarizing plate of Claim 1 or 2 whose bulk average density | concentration of the terminal group represented by following formula (2) of polylactic acid is lower than the terminal group density | concentration in the adhesive interface vicinity in the polarizing film side.

  The polarizing plate according to claim 1, wherein the material containing polylactic acid contains 40% by weight or more of polylactic acid.   The polarizing plate according to claim 1, wherein the material containing polylactic acid contains 50% by weight or less of polymethyl methacrylate.   The polarizing plate in any one of Claims 1-5 in which a photoinitiator is contained in an adhesive bond layer.   The polarizing plate according to claim 4, wherein the photoinitiator is an agent capable of initiating a polymerization reaction by light having a wavelength of 380 nm or more.   The polarizing plate according to claim 1, wherein the protective film bonded to the polarizing film contains an ultraviolet absorber. The polarizing plate according to claim 1, wherein the radiation curable composition is represented by the following formula (3).

(In the formula (3), R ²² represents a hydrogen atom or a methyl group, R ²³ represents an alkylene group having 2 to 5 carbon atoms (one methylene group present in the alkylene group is substituted with —OCO—). And each hydrogen atom present in the alkylene group is substituted with a hydroxyl group, a carboxyl group, an isocyanate group, or a phosphoric acid group.) A protective film made of a material containing polylactic acid and a polarizing film are formed in advance and bonded together with a radiation curable composition containing the following formula (1) interposed therebetween, and substantially no light having a wavelength of 270 nm or less is irradiated. The manufacturing method of a polarizing plate which cures a radiation hardening type composition like this.

(In the formula (1), n represents 1 or 2, R ²⁰ represents a hydrogen atom or a methyl group, and R ²¹ represents an alkylene group having 1 to 10 carbon atoms (1 or 2 present in the alkylene group). One or more methylene groups may be each independently substituted with an oxygen atom, —CO—, —COO— or —OCO—, as oxygen atoms are not directly bonded to each other, and are present in the alkylene group. 1 or 2 or more hydrogen atoms are each substituted with a hydroxyl group, a carboxyl group, an isocyanate group, an aldehyde group, or a phosphate group.)   The liquid crystal display device using the polarizing plate in any one of Claims 1-9.

Images