JP2011127013A - Polypropylene film, polarizing plate using the same, liquid crystal panel and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene film excellent in adhesion to a polarizing film when laminated to the polarizing film through an adhesive layer and suitable for use as a polarizing plate-protecting film, a polarizing plate including the polypropylene film, and a liquid crystal panel and a liquid crystal display using the polarizing plate. <P>SOLUTION: The polypropylene film is obtained when a polypropylene-based resin including isotactics is subjected to melt-kneading, discharged from T-die in a film form, compressed between an elastic roller and a metal roller, and then cooled and solidified. In the polypropylene film, at least one surface comprises a surface whose isotactic crystallinity obtained from infrared spectroscopic measurement by attenuated total reflection method is 60% or less. The polarizing plate includes the polypropylene film, and the liquid crystal panel and the liquid crystal display uses the polarizing plate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a film (polypropylene film) made of a polypropylene resin that can be suitably used as a protective film for a polarizing plate. The present invention also relates to a polarizing plate provided with the polypropylene film, and a liquid crystal panel and a liquid crystal display device using the polarizing plate.

  Liquid crystal display devices are rapidly expanding their use as various display devices by taking advantage of their low power consumption, low voltage operation, light weight and thinness. Performance is required. For example, a liquid crystal display device for a car navigation system may have a higher temperature and humidity in the vehicle in which the liquid crystal display device is placed, and therefore has higher moisture and heat resistance than a liquid crystal display device for a normal television or personal computer. Required. High humidity and heat resistance is also required for polarizing plates applied to liquid crystal display devices used for such applications.

  Conventionally, a polarizing plate has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film made of a polyvinyl alcohol resin on which a dichroic dye is adsorbed and oriented. As the protective film, a cellulose acetate resin film typified by triacetylrose is often used, and an adhesive composed of an aqueous solution of a polyvinyl alcohol resin is often used for laminating the protective film. However, a polarizing plate in which a protective film made of triacetyl cellulose is laminated on both sides or one side of a polarizing film on which a dichroic dye is adsorbed and oriented via an adhesive made of an aqueous solution of a polyvinyl alcohol-based resin, under wet heat conditions. When used for a long time, there are problems that the polarization performance is deteriorated and the protective film and the polarizing film are easily peeled off.

  In order to solve the above problem, Patent Document 1 proposes to use a film made of a polypropylene resin as at least one protective film, thereby suppressing deterioration of the polarizing film under wet heat conditions. It is said that. Further, this document describes that the adhesion between the protective film and the polarizing film is improved by applying a corona treatment to the bonding surface of the protective film made of polypropylene resin.

JP 2007-334295 A

  As shown in Patent Document 1, the polarizing plate using a film made of polypropylene resin as a protective film is more durable under wet heat conditions than when a protective film made of cellulose acetate resin is used. It is excellent. However, as the further study progressed, it was found that depending on the polypropylene resin film, sufficient adhesion to the polarizing film might not be obtained even when surface modification such as corona treatment was performed. .

  Accordingly, an object of the present invention is to provide a polypropylene-based resin film (polypropylene) that has excellent adhesion to the polarizing film when laminated on the polarizing film via an adhesive layer, and can be suitably used as a polarizing plate protective film. Film). Another object of the present invention is to provide a polarizing plate comprising the polypropylene film, which has high adhesion between the polypropylene film and the polarizing film and is excellent in durability performance. Still another object of the present invention is to provide a liquid crystal panel and a liquid crystal display device using the polarizing plate.

  As a result of intensive studies, the inventors have determined that the adhesive strength between the polypropylene film and the polarizing film via the adhesive layer depends on the crystallinity of the adhesive layer side surface in the polypropylene film, and is defined below. It has been found that good adhesive strength can be obtained when the crystallinity of the surface is in a specific range. That is, the present invention is as follows.

  The present invention is a polypropylene film obtained by melting and kneading a polypropylene-based resin containing isotactic, discharging it from a T-die into a film shape, sandwiching it with an elastic roll and a metal roll, and cooling and solidifying it. Thus, at least one surface provides a polypropylene film comprising a surface having a surface isotactic crystallinity of 60% or less obtained by infrared spectroscopic measurement by an attenuated total reflection method.

The diffraction profile of the surface having an isotactic crystallinity of 60% or less obtained by a thin film X-ray diffraction method preferably has the following characteristics.
(1) 2θ of the peak with the highest intensity is 14.6 degrees, and (2) 2θ of the peak with the second highest intensity is 21.2 degrees.

  The surface softening temperature of the surface having the isotactic crystallinity of 60% or less is preferably 100 degrees or more and 120 degrees or less.

  In addition, with respect to the surface having the isotactic crystallinity of 60% or less, three consecutive times under the conditions of an output of 280 W, a line speed of 1.0 m / min, and a distance of 3 mm between the surface and the electrode of the corona treatment apparatus. When the corona treatment is performed, it is preferable that the average diameter of the fine protrusions existing on the corona-treated surface is 10 nm or more and 115 nm or less, and the number of the fine protrusions per square μm is 30 or more and 100 or less. .

  In the polypropylene film of the present invention, one surface may be a surface having the above-mentioned isotactic crystallinity of 60% or less, and the other surface may be a prism-shaped or lens-shaped uneven surface.

  The present invention also relates to a polarizing film comprising a uniaxially stretched polyvinyl alcohol-based resin film in which iodine or a dichroic dye is adsorbed and oriented, and the polypropylene film laminated on one surface of the polarizing film via an adhesive layer A polarizing plate is provided. In the polarizing plate of the present invention, the polypropylene film is laminated so that the surface having an isotactic crystallinity of 60% or less is in contact with the adhesive layer.

  The adhesive layer is preferably composed of a cured product layer of an active energy ray-curable resin composition containing an epoxy resin.

  The polarizing plate of this invention may be provided with the protective film or optical compensation film laminated | stacked on the surface on the opposite side to the surface where the polypropylene film in a polarizing film is laminated | stacked.

  Furthermore, this invention provides a liquid crystal panel provided with a liquid crystal cell and the said polarizing plate laminated | stacked on this liquid crystal cell, and a liquid crystal display device provided with a surface light source element and this liquid crystal panel.

  The polypropylene film of the present invention is excellent in adhesiveness with the polarizing film when laminated on the polarizing film through an adhesive layer, and is an optical film suitable for a polarizing plate protective film. A polarizing plate using the polypropylene film of the present invention as a protective film, and a liquid crystal panel and a liquid crystal display device including the polarizing plate have high adhesive strength between the polypropylene film and the polarizing film and are excellent in durability.

It is a schematic perspective view which shows a preferable example of the surface uneven | corrugated shape which a polypropylene film has. It is a schematic perspective view which shows another example of the preferable surface asperity shape which a polypropylene film has. It is a schematic perspective view which shows another example of the preferable surface asperity shape which a polypropylene film has. It is a schematic perspective view which shows another example of the preferable surface asperity shape which a polypropylene film has. It is a schematic perspective view which shows another example of the preferable surface asperity shape which a polypropylene film has. It is the schematic which shows an example of the film manufacturing apparatus which can be used suitably for manufacture of the polypropylene film of this invention. It is the schematic which shows another example of the film manufacturing apparatus which can be used suitably for manufacture of the polypropylene film of this invention. It is the schematic which shows another example of the film manufacturing apparatus which can be used suitably for manufacture of the polypropylene film of this invention. It is a schematic sectional drawing which shows a preferable example of the polarizing plate of this invention. It is a schematic sectional drawing which shows another preferable example of the polarizing plate of this invention. It is a schematic sectional drawing which shows a preferable example of the liquid crystal panel of this invention, and a liquid crystal display device using the same. 2 is a diffraction profile of the first surface of the polypropylene film 1 obtained in Example 1 by a thin film X-ray diffraction method. 2 is a diffraction profile of the second surface of the polypropylene film 1 obtained in Example 1 by a thin film X-ray diffraction method. It is a diffraction profile by the thin film X-ray diffraction method about the 1st surface of the polypropylene film 8 obtained by the comparative example 2. FIG. It is a diffraction profile by the thin film X-ray diffraction method about the 2nd surface of the polypropylene film 8 obtained by the comparative example 2. FIG.

<Polypropylene film>
The polypropylene film of the present invention is a film made of a polypropylene-based resin containing isotactic, and at least one surface is a surface obtained by infrared spectroscopic measurement by an attenuated total reflection method (ATR) method. It is characterized by comprising a surface having an isotactic crystallinity of 60% or less. The polypropylene film of the present invention having such a surface is excellent in adhesiveness when laminated on a polarizing film through an adhesive layer so that the surface faces the adhesive layer. By using this polypropylene film as a polarizing plate protective film, it is possible to obtain a polarizing plate having excellent adhesion strength between the polarizing film and the protective film and high durability. The isotactic crystallinity of the polypropylene film surface is preferably 55% or less. When the isotactic crystallinity exceeds 60%, the adhesiveness with the adhesive layer is lowered, and it is difficult to obtain sufficient adhesive strength between the polarizing film and the protective film.

  The lower limit of the isotactic crystallinity is not particularly limited, but is preferably 5% or more, more preferably 20% or more in consideration of the mechanical strength and heat resistance of the polypropylene film.

Here, the “isotactic crystallinity of the polypropylene film surface” means the proportion of the isotactic crystal region in the polypropylene film surface composed of the polypropylene-based resin containing isotactic, When it consists only of isotactic polypropylene-type resin, it means the ratio of the crystallization area | region which occupies substantially the polypropylene film surface. The isotactic crystallinity of the polypropylene film surface is measured and calculated by the following method. That is, first, using an infrared spectrophotometer, the infrared spectrum of the polypropylene film surface is measured by the attenuated total reflection method (ATR method). The ATR method referred to here is a method in which a measurement surface of a polypropylene film is directly adhered to a germanium crystal prism, and an infrared spectrum can be obtained for a layer of about several μm on the surface of the film electrode. The isotactic crystallinity X on the surface of the polypropylene film is based on the obtained infrared spectroscopic spectrum and is represented by the following formula:
Isotactic crystallinity X (%) = 109 × (A ₉₉₈ -A ₉₂₀ ) / (A ₉₇₄ -A ₉₂₀ ) -31.4
Sought by. In the above formula, A ₉₉₈ , A ₉₇₄ and A ₉₂₀ are absorbances at wave numbers ₉₉₈ , ₉₇₄ and ₉₂₀ cm ⁻¹ , respectively. The above calculation formula is, for example, J. Appl. Polym. Sci. , 2, 166 (1959); Infrared analysis of materials-basics and applications-(Kodansha Scientific); and [Chemical domain special edition] Infrared absorption spectrum, Vol. 17 (Nanedo) etc. It is a generally known calculation formula.

In the polypropylene film of the present invention, the surface having an isotactic crystallinity of 60% or less is advantageous in terms of adhesion to the adhesive layer. Therefore, the following (I) or (II) Or (I) and (II).
(I) In the diffraction profile of the surface having an isotactic crystallinity of 60% or less obtained by a thin film X-ray diffraction method, the highest peak 2θ is 14.6 degrees, and the intensity is the second. The high peak 2θ is 21.2 degrees.
(II) The surface softening temperature of the surface where the isotactic crystallinity is 60% or less is 100 degrees or more and 120 degrees or less.

  The characteristic (I) will be described. As crystal forms of isotactic polypropylene, there are mainly α crystal, β crystal, γ crystal, and smectic crystal, which can be identified by X-ray diffraction method. For example, the diffraction profile derived from the α crystal has a diffraction angle (2θ) of around 14.2 degrees, around 16.7 degrees, around 18.5 degrees and a wide angle X-ray diffraction measurement in the range of 10 to 30 degrees. A clear diffraction peak is observed around 21.4 degrees. Most of the diffraction peaks of the β and γ crystals overlap with the α crystal, but the β crystal is observed near 15.9 degrees, the γ crystal is near 20.0 degrees, and peaks that do not overlap with the α crystal are observed. Therefore, it can be distinguished from the α crystal. In the smectic crystal, two broad peaks are observed around 14.6 degrees and 21.2 degrees.

  Therefore, the above characteristic (I) is that the surface diffraction profile having an isotactic crystallinity of 60% or less obtained by the thin film X-ray diffraction method is substantially a diffraction profile derived from a smectic crystal. Meaning that most of the surface is occupied by smectic crystals. When the surface having an isotactic crystallinity of 60% or less has the characteristic (I), the adhesion between the surface of the polypropylene film and the adhesive layer can be further improved.

  Next, the characteristic (II) will be described. The “surface softening temperature” of a surface having an isotactic crystallinity of 60% or less is measured using a local thermal analysis (Nanoscale Thermal Analysis) system. When the surface is gradually heated from room temperature, the surface begins to soften. When the surface softening temperature of the surface of the polypropylene film is 100 ° C. or more and 120 ° C. or less, the adhesion between the surface of the polypropylene film and the adhesive layer can be further improved.

  Further, as will be described later, when the polypropylene film of the present invention and the polarizing film are bonded using an adhesive, the isotactic crystallinity of the polypropylene film is 60% or less for further improvement of the adhesiveness. A corona treatment can be applied to a certain surface in advance, but in this case, etching is performed by the energy of corona discharge, and fine protrusions are generated on the surface (corona treatment surface) of the polypropylene film. When the average diameter of the fine protrusions present on the corona-treated surface after the corona treatment is 10 nm or more and 115 nm or less and the number of the fine protrusions per square μm is 30 or more and 100 or less, adhesion by corona treatment This is preferable because the effect of improving the property can be further improved. This is considered to be due to the fact that the adhesive enters between the fine protrusions, thereby increasing the contact area between the polypropylene film and the adhesive layer.

Here, the fine protrusion existing on the corona-treated surface means a protrusion existing on the surface (corona-treated surface) having an isotactic crystallinity of 60% or less after the corona treatment. The “average diameter” means that the bottom area of each fine protrusion included in a 5 μm × 5 μm region arbitrarily extracted from the corona-treated surface is calculated by image analysis, and the bottom surface of the fine protrusion is the same area as the calculated bottom area It is the average value of each diameter calculated when it is assumed to be a circle. The number of fine protrusions per square μm is a value obtained by converting the number of fine protrusions contained in a 5 μm × 5 μm region arbitrarily extracted from the corona-treated surface per square μm (that is, Divided by 25 μm ² ). Further, the corona treatment to measure the average diameter of fine projections and the number per 1 μm is a surface having an output of 280 W, a line speed of 1.0 m / min, and an isotactic crystallinity of 60% or less. It is performed three times continuously under the condition of a distance of 3 mm from the electrode of the corona treatment apparatus.

  Both sides of the polypropylene film of the present invention can be flat surfaces. In this case, only one side may be composed of a surface having an isotactic crystallinity of 60% or less, or both sides are isotactic. It may consist of a surface with a tic crystallinity of 60% or less. Moreover, as for the polypropylene film of this invention, one surface consists of a flat surface and the other surface may have regular uneven | corrugated shape. In this case, the flat surface is usually a surface having an isotactic crystallinity of 60% or less.

  As the regular concavo-convex shape, a prism shape and a lens shape can be mentioned as suitable ones. FIGS. 1-5 is a schematic perspective view which shows the preferable example of the surface uneven | corrugated shape which a polypropylene film has. Here, the prism shape is a one-dimensional array in which a plane indicated by a locus obtained by translating a shape composed of straight lines (which may include a curve in part) such as a substantially triangular shape is arranged in one direction. For example, the shape shown in FIG. 1 can be mentioned.

  In the prism shape composed of a plurality of protrusions having a triangular cross section shown in FIG. 1, the angle of the vertex in the cross sectional triangle shape can be set to 30 to 100 °, for example, and the pitch of the protrusions (ridge line of adjacent protrusions) The distance between them can be, for example, 5 to 300 μm. Further, the height of the protrusion having a triangular cross section can be set to 10 to 200 μm, for example.

  The two sides in the cross-sectional triangle shape may have the same length or may have different lengths. Further, the heights of the plurality of projections having a triangular cross section in the prism shape may be the same or different. The shape of the groove formed between the protrusions may be a straight line or a curved line. The cross section of the prism may have a triangular shape, a substantially triangular shape including a curve in part, a sawtooth shape, or the like.

  Further, the lens shape means a shape having an uneven structure formed mainly from a curved surface. For example, a curve such as a substantially semicircular arc shape such as the lenticular lens shown in FIG. A one-dimensional lens array in which curved surfaces indicated by trajectories obtained by translating the shape composed of the same shape are arranged in one direction; a circular shape such as a perfect circle or an ellipse (for example, FIG. 3); (For example, FIG. 4), a two-dimensional lens array having bottom surfaces such as triangles, hexagons, and other polygonal shapes and having dome-shaped curved surfaces arranged vertically and horizontally can be given. As another lens shape, a two-dimensional lens array in which projections having a polygonal shape (for example, quadrangular pyramid-like projections) in which planes having various angles are combined as shown in FIG. 5 are arranged vertically and horizontally. And a Fresnel lens.

  In the lenticular lens shown in FIG. 2, the pitch and height of the protrusions can be 10 to 200 μm and 5 to 100 μm, respectively. The pitch and height of the plurality of protrusions constituting the lenticular lens may be the same or different. The shape of the groove formed between the protrusions may be a straight line or a curved line.

  Also, in the lens shape other than the lenticular lens, the plurality of protrusions may have the same height or different heights. The shape of the groove formed between the protrusions may be a straight line or a curved line. In addition, as an irregular shape other than the above, an irregular shape whose cross section is a wave shape like a sine wave can be exemplified.

  The thickness of the polypropylene film of the present invention is preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 150 μm or less. If the thickness is less than 20 μm, the mechanical strength may be remarkably weakened, or if one surface has a regular uneven shape, a part that is difficult to be formed may be formed. On the other hand, when the thickness is larger than 200 μm, the transmittance may be lowered, and it is not preferable from the viewpoint of thinning a polarizing plate using the same.

  Next, the polypropylene resin constituting the polypropylene film of the present invention will be described. Examples of the polypropylene resin used in the present invention include a propylene homopolymer, and a copolymer of propylene and one or more monomers selected from the group consisting of ethylene and an α-olefin having 4 to 20 carbon atoms. Can be mentioned. Moreover, you may use the 2 or more types of polymer mixture selected from these. The copolymer of one or more monomers selected from the group consisting of ethylene and an α-olefin having 4 to 20 carbon atoms and propylene may be a random copolymer or a block copolymer. Also good.

  Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1 -Hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl -1-butene, 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 1-octene, 2-ethyl-1-hexene, 3,3 -Dimethyl-1-hexene, 2-propyl-1-heptene, 2-methyl-3-ethyl-1-heptene, 2,3,4-trimethyl-1-pentene, 2-propyl-1-pentene, 2,3 -Diethyl-1-butene 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-Heputadasen, 1 Okutatesen, 1-nonadecene and the like. Of these, α-olefins having 4 to 12 carbon atoms are preferable, such as 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3- Dimethyl-1-butene, 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 1-octene, 2-ethyl-1-hexene, 3, 3-dimethyl-1-hexene, 2-propyl-1-heptene, 2-methyl-3-ethyl-1-heptene, 2,3,4-trimethyl-1-pentene, 2-propyl-1-pentene, 2, 3-diethyl-1- Ten, 1-nonene, 1-decene, 1-undecene, 1-dodecene, and the like. In particular, from the viewpoint of copolymerizability, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and 1-butene and 1-hexene are more preferable.

  Among the above-described polypropylene resins, in the case of propylene homopolymer or copolymer, from the viewpoint of copolymerization, propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / 1- It is preferable to use an octene copolymer, a propylene / 1-hexene copolymer or a propylene / ethylene / 1-hexene copolymer.

  When the polypropylene resin used in the present invention is a copolymer, the content of the structural unit derived from the comonomer (monomer other than propylene) in the copolymer (when the comonomer is 2 or more, the total content thereof) is: In light of the balance between transparency and heat resistance, the amount is preferably 40% by weight or less, and more preferably 30% by weight.

  As a method for producing a polypropylene resin, a method of homopolymerizing propylene using a known polymerization catalyst, or one or more monomers selected from the group consisting of ethylene and an α-olefin having 4 to 20 carbon atoms; The method of copolymerizing with propylene is mentioned. Known polymerization catalysts include, for example, (1) a Ti—Mg-based catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components, and (2) a solid catalyst component comprising magnesium, titanium and halogen as essential components. In addition, a catalyst system in which an organoaluminum compound is combined with a third component such as an electron donating compound as necessary, (3) a metallocene catalyst, and the like. Among them, a catalyst system in which an organic aluminum compound and an electron donating compound are combined with a solid catalyst component containing magnesium, titanium, and halogen as essential components can be most generally used.

  Preferable specific examples of the organoaluminum compound include, for example, triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, and tetraethyldialumoxane. Specific examples of suitable electron donating compounds include cyclohexylethyldimethoxysilane, tert-butyl-n-propyldimethoxysilane, tert-butylethyldimethoxysilane, and dicyclopentyldimethoxysilane. Examples of the solid catalyst component containing magnesium, titanium and halogen as essential components include catalyst systems described in, for example, JP-A-61-218606, JP-A-61-287904, JP-A-7-216017, and the like. Is mentioned. Examples of the metallocene catalyst include the catalyst systems described in Japanese Patent No. 2587251, Japanese Patent No. 2627669, and Japanese Patent No. 2668732.

  Polymerization methods for polypropylene resins include solvent polymerization using an inert solvent typified by hydrocarbon compounds such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, and liquid monomers as solvents. A bulk polymerization method used as a gas phase polymerization method, a gas phase polymerization method carried out in a gaseous monomer, and the like, preferably a bulk polymerization method or a gas phase polymerization method which can be easily post-treated. These polymerization methods may be a batch method or a continuous method.

  From the viewpoint of good mechanical properties of the resulting polypropylene film and versatility, the stereoregularity of the polypropylene-based resin used in the present invention is isotactic, syndiotactic, or atactic. It is preferable that the ratio is large, and it is particularly preferable that the ratio is substantially composed of only an isotactic propylene resin.

  The polypropylene-based resin may be a blend of two or more types of polypropylene-based resins having different molecular weights, proportions of structural units derived from propylene, and the like, and may appropriately contain polymers and additives other than the polypropylene-based resins. Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent, and a plurality of these may be used in combination.

  Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine antioxidants (HALS), and phenolic and phosphorus antioxidant mechanisms in one molecule. And a composite type antioxidant containing a unit having the following.

  Examples of the UV absorber include UV absorbers such as 2-hydroxybenzophenone and hydroxytriazole, and UV blockers such as benzoate.

  Examples of the antistatic agent include a polymer type, an oligomer type, and a monomer type.

  Examples of the lubricant include higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and metal salts thereof.

  Examples of the nucleating agent include sorbitol nucleating agents, organophosphate nucleating agents, rosin nucleating agents, and polymer nucleating agents such as polyvinylcycloalkane. As the anti-blocking agent, fine particles having a spherical shape or a shape close thereto can be used regardless of inorganic type or organic type.

  The melt flow rate (MFR) of the polypropylene resin used in the present invention is a value measured according to JIS K 7210 (test temperature, nominal load is according to JIS K 7210, Annex B, Table 1), and is usually 0.1 g. / 10 minutes to 50 g / 10 minutes, and preferably about 0.5 g / 10 minutes to 20 g / 10 minutes. By using a polypropylene resin having an MFR in such a range, a uniform film can be formed without imposing a large load on the extruder.

  The molecular weight distribution of the polypropylene resin used in the present invention is usually 1-20. The molecular weight distribution is the ratio of Mn to Mw (= Mw / Mn) measured and calculated using o-dichlorobenzene at 140 ° C. as the solvent and polystyrene as the standard sample.

<Production method of polypropylene film>
The polypropylene film of the present invention is obtained by melt-kneading the polypropylene-based resin containing the above-mentioned isotactic and discharging it into a film form from a T die, sandwiching it with an elastic roll and a metal roll, and cooling and solidifying it. . According to such a manufacturing method, it has a surface with an isotactic crystallinity of 60% or less, and more preferably has the above characteristics (I) and (II), and the fine protrusions after corona treatment It becomes possible to produce a polypropylene film having a diameter and a number within the above range with high productivity.

  6-8 is the schematic which shows the example of the film manufacturing apparatus which can be used suitably for manufacture of the polypropylene film of this invention. Hereinafter, the structure of a film production apparatus that can be suitably used for producing the polypropylene film of the present invention and a method for producing a polypropylene film using the same will be described with reference to FIGS.

(Extruder)
In the production of a polypropylene film using the film production apparatus 100 shown in FIG. 6 (the same applies to the film production apparatuses 200 and 300 shown in FIGS. 7 and 8), first, a hopper (not shown) is sent to the extruder 1. The above polypropylene resin is introduced. At this time, in order to suppress deterioration, decomposition, etc. of the polypropylene resin during kneading, before supplying the resin to the extruder 1, the nitrogen gas is heated to 40 ° C. or more and (Tm−20 ° C.) or less at 1 It is preferable to perform preliminary drying for about 10 to 10 hours (Tm [° C.] is the melting peak temperature of the polypropylene resin in differential scanning calorimetry specified in JIS K 7121). It is preferable to perform gas replacement with an inert gas such as nitrogen gas or argon gas at 20 ° C. to 120 ° C. The extruder 1 extrudes the supplied polypropylene resin while melting and kneading it, and conveys the molten polypropylene resin to the T-die 2.

  When melt-kneading the polypropylene resin in the extruder 1, a screw is used. As the screw, when the extruder 1 is a single screw extruder, L / D = 24 to 36 and a compression ratio of 1.5. A type having kneading portions of -4 full flight type, barrier type or Maddock type can be used. From the viewpoint of suppressing deterioration and decomposition of the polypropylene resin and uniformly melting and kneading, it is preferable to use a barrier type screw having L / D = 28 to 36 and a compression ratio of 2.5 to 3.5.

  Further, in order to remove volatile gas generated when the polypropylene resin is deteriorated or decomposed, it is also preferable to provide an orifice of 1 mm or more and 5 mmφ or less at the tip of the extruder 1 to increase the resin pressure at the tip of the extruder 1. Increasing the resin pressure at the tip of the extruder 1 means increasing the back pressure at the tip, thereby improving the stability of extrusion. The orifice to be used is more preferably 2 mmφ or more and 4 mmφ or less. In addition, it is preferable to attach a gear pump via the adapter between the extruder 1 and the T die 2 from a viewpoint of suppressing the extrusion fluctuation | variation of polypropylene resin. Moreover, it is preferable to attach a leaf disk filter (not shown) in order to remove foreign substances in the polypropylene resin.

(T die)
The T-die 2 is connected to the extruder 1 and has a manifold 2b for spreading the molten polypropylene resin conveyed from the extruder 1 in the lateral direction. Further, the T die 2 is provided with a discharge port 2a that communicates with the manifold 2b and discharges a molten polypropylene-based resin spread laterally by the manifold 2b. Therefore, the molten polypropylene resin discharged from the discharge port 2a of the T die 2 is formed into a sheet shape (hereinafter, the molten polypropylene resin formed into a sheet shape is also referred to as a “molten sheet”). ).

  The temperature of the discharged molten sheet is preferably 180 ° C. or higher and 300 ° C. or lower. The temperature of the molten resin is measured using a resin thermometer at the discharge port 2a portion of the T die 2. When the temperature of the molten sheet is less than 180 ° C., the spreadability is inferior, and thus there is a tendency for unevenness in thickness to occur due to non-uniform elongation in the air gap. On the other hand, when the temperature of the molten sheet exceeds 300 ° C., the resin deteriorates and the discharge port 2a is contaminated due to generation of decomposition gas, die line is generated, and the appearance of the polypropylene film is deteriorated. It tends to end up.

  The T die 2 is also preferably free from minute steps or scratches on the wall surface of the flow path of the molten polypropylene resin. The discharge port 2a portion (lip portion) of the T-die 2 is a material having a small coefficient of friction with the molten polypropylene resin, and is plated or coated with a hard material (for example, tungsten carbide-based or fluorine-based special plating). It is preferable that the radius of curvature of the tip portion of the discharge port 2a can be reduced (the tip portion of the discharge port 2a has a shape called a so-called sharp edge).

  The tip end portion of the discharge port 2a of the T die 2 is preferably in the shape of a sharp edge having a radius of curvature at the discharge port of 0.1 mm or less, on the wall surface of the flow path of the molten polypropylene resin. The radius is more preferably 0.05 mm or less, and the curvature radius is more preferably 0.03 mm or less. By using such a T-die 2, it is possible to suppress the occurrence of “eyes” at the discharge outlet 2 a and at the same time, it is possible to suppress the die line. Can be further improved. However, when the curvature radius is 0.01 mm or less, although these effects are improved, the strength at the tip of the discharge port 2a is reduced, and the discharge port 2a is damaged, thereby causing a large die line or the like. May occur.

  The length (the length of the air gap) H from the molten resin discharge port 2a in the T die 2 to the time when the molten sheet is clamped by the elastic roll 3 and the metal roll 4 installed therebelow is: It has a surface with an isotactic crystallinity of 60% or less, and more preferably has the above characteristics (I) and (II), and the diameter and number of fine protrusions after corona treatment are within the above range. Since it is easy to obtain a polypropylene film, the thickness is preferably about 50 mm to 250 mm, and more preferably about 50 mm to 180 mm. When the length H of the air gap exceeds 250 mm, the cooling efficiency decreases due to exposure to air for a long time, and the isotactic crystallinity of the surface tends to increase. There is a tendency that a large retardation is generated in the polypropylene film to be formed. The lower limit of the air gap length H depends on the size of the T-die and the diameters of the elastic roll 3 and the metal roll 4, and is necessarily about 50 mm.

(Elastic roll)
In the present invention, the elastic roll means an elastically deformable metal roll or rubber roll. As the elastically deformable metal roll, the elastic roll 3 having the configuration shown in FIG. 6 can be suitably used. The elastic roll 3 with which the film manufacturing apparatus 100 shown by FIG. 6 is provided is equivalent to the forming roll described in Japanese Patent No. 3422798, and specifically, a metal strip having a cylindrical shape. (Also referred to as an endless belt) 3a, a rubber roll 3b (one in the example of FIG. 6) disposed inside the band 3a, and a liquid that fills the space between the band 3a and the rubber roll 3b L is an elastically deformable metal roll having L and temperature adjusting means (not shown) for adjusting the temperature of the liquid L.

  The band-shaped body 3a is formed in a cylindrical shape by a metal thin film that can be elastically deformed, such as spring steel, stainless steel, nickel steel, etc., and there is no seam on the surface thereof. Both sides of the strip 3a are closed by a closing member (not shown). As the strip 3a, one having a thickness of about 100 μm to 1500 μm, a diameter of about 200 mm to 600 mm, and a surface roughness of 0.5 S or less can be used, and preferably the surface roughness is 0.2 S or less. It is. The diameter of the strip 3a is set to an appropriate size according to the processing speed of the polypropylene film, but when the diameter of the strip 3a is in the above range, the processing speed of the polypropylene film is several m / min. It can respond in a range of ˜100 tens m / min.

  The rubber roll 3b has a cylindrical shape, and can be elastically deformed and rotated inside the strip 3a. The rubber roll 3b can be formed of EPDM (ethylene-propylene-diene rubber), neoprene or silicone having a hardness of about 30 to 90. The diameter of the rubber roll 3b can be about 100 mm to 250 mm.

  As the liquid L, for example, water, ethylene glycol, oil or the like can be used. By adjusting the temperature of the liquid L by a temperature adjusting means (not shown), the surface temperature of the strip 3a is indirectly adjusted.

  In this invention, it is preferable that the thickness of the strip | belt-shaped body 3a is about 350-500 micrometers, and the hardness of the rubber roll 3b is about 60-75. When the thickness of the belt-like body 3a is less than 350 μm and the hardness of the rubber roll 3b is less than 60, the elasticity of the elastic roll 3 becomes too low, and it is difficult to uniformly hold the elastic roll 3 in the width direction. It tends to be. Moreover, when the thickness of the strip | belt-shaped body 3a exceeds 500 micrometers and the hardness of the rubber-made roll 3b exceeds 75, the rigidity as the elastic roll 3 will become high too much, and it exists in the tendency for the effect of softly pinching to become weak.

  Moreover, it is also preferable to use the elastic roll 6 of the structure shown by FIG. 7 as an elastic roll. The elastic roll 6 provided in the film manufacturing apparatus 200 shown in FIG. 7 is equivalent to the forming belt means described in Japanese Patent Laid-Open No. 7-040370, and specifically, is made of a metal metal having a cylindrical shape. A belt (also referred to as an endless belt) 6a, and two rolls 6b and 6c that are arranged along the outer peripheral surface of the metal roll 4 and parallel in the longitudinal direction inside the belt 6a, It is an elastically deformable metal roll having temperature adjusting means (not shown) for adjusting the surface temperature of the strip 6a. The roll 6b is a rubber roll, and the roll 6c is a metal roll. The surface temperature of the strip 6a is adjusted by adjusting the surface temperature of the roll 6c with the temperature adjusting means.

  The band-like body 6a is formed in a cylindrical shape by a metal thin film that can be elastically deformed, such as spring steel, stainless steel, nickel steel, etc., and there is no seam on the surface thereof. The belt-like body 6a is stretched over a rubber roll 6b and a metal roll 6c, and the tension (tension) of the belt-like body 6a can be adjusted by making the distance between the rolls 6b and 6c close to or apart from each other. It is like that. As the belt-like body 6a, one having a thickness of about 300 μm to 800 μm and a diameter of about 200 mm to 600 mm when formed into a cylindrical shape can be used, and the surface roughness is preferably 0.2 S or less.

  The rolls 6b and 6c have a columnar shape and are rotatable inside the strip 6a. The rubber roll 6b can be formed of EPDM (ethylene-propylene-diene rubber), neoprene or silicone having a hardness of about 30 to 90. Moreover, as the rolls 6b and 6c, those having a diameter of about 80 mm to 200 mm can be used.

  When the elastic roll 6 is used, the position where the molten sheet discharged from the discharge port 2a of the T-die 2 is first sandwiched between the strip 6a and the metal roll 4 is the starting point of the sandwiching pressure, and the sandwiched resin Is the end point of the pinching pressure at a position away from the belt-like body 6a and the metal roll 4.

  In the present invention, it is preferable that the thickness of the belt-like body 6a is about 350 μm to 600 μm, and the hardness of the rubber roll 6b is about 60 to 80. If the thickness of the belt-like body 6a is less than 350 μm and the hardness of the rubber roll 6b is less than 60, the elasticity of the elastic roll 6 becomes too low, and the elastic roll 6 may be uniformly pinched in the width direction. It tends to be difficult. On the other hand, if the thickness of the belt-like body 6a exceeds 600 μm and the hardness of the rubber roll 6b exceeds 80, the rigidity as the elastic roll 6 becomes too high. A polypropylene film having a surface with a degree of conversion of 60% or less, more preferably having the above characteristics (I) and (II), and having a diameter and number of fine protrusions after corona treatment within the above range is obtained. This is not preferred because it tends to increase the possibility of phase difference in the resulting polypropylene film.

  Furthermore, it is also preferable to use the elastic roll 7 having the configuration shown in FIG. 8 as the elastic roll. The elastic roll 7 provided in the film manufacturing apparatus 300 shown in FIG. 8 is equivalent to the pressing roll described in Japanese Patent Laid-Open No. 11-235747, specifically, a highly rigid metal inner cylinder 7a and A thin metal outer cylinder 7b disposed outside the metal inner cylinder 7a, a fluid shaft cylinder 7c disposed inside the metal inner cylinder 7a, a space between the metal inner cylinder 7a and the thin metal outer cylinder 7b, and An elastically deformable metal roll having a liquid L filling the fluid shaft cylinder 7c and a temperature adjusting means (not shown) for adjusting the temperature of the liquid L.

  The metal inner cylinder 7a, the thin metal outer cylinder 7b, and the fluid shaft cylinder 7c are arranged so as to be coaxial. The metal inner cylinder 7a is provided with a plurality of through holes 7d along the circumferential direction thereof. Therefore, the liquid L circulates in the elastic roll 7 in the order of the fluid shaft cylinder 7c, the through hole 7d, and the space between the metal inner cylinder 7a and the thin metal outer cylinder 7b.

  The thin metal outer cylinder 7b is made of stainless steel or the like, has no seam on its surface, and has flexibility. The thin metal outer cylinder 7b is thinned within a range in which the thin cylinder theory of elastic mechanics can be applied in order to have flexibility, flexibility and resilience close to rubber elasticity. As the thin metal outer cylinder 7b, one having a thickness of about 2000 μm to 5000 μm, a diameter of about 200 mm to 500 mm, and a surface roughness of 0.5 S or less can be used. 2S or less. If the thickness of the thin metal outer cylinder 7b is less than 2000 μm, the pressure when the molten sheet is clamped by the elastic roll 7 and the metal roll 4 tends to be non-uniform, and if it exceeds 5000 μm, the thin metal outer cylinder 7b The elasticity of 7b (elastic roll 7) becomes large, and depending on the thickness of the molten sheet discharged from the discharge port 2a of the T-die 2, a resin pool (bank) tends to be generated when the molten sheet is clamped. It is in.

  As the liquid L, for example, water, ethylene glycol, oil, or the like can be used. By adjusting the temperature of the liquid L by a temperature adjusting means (not shown), the surface temperature of the thin metal outer cylinder 7b is indirectly adjusted.

  Further, as described above, a rubber roll can be used as the elastic roll. When a rubber roll is used as the elastic roll, the surface hardness is preferably 65 to 80, and more preferably 70 to 80. By using a rubber roll having such a surface hardness, it becomes easy to maintain a uniform linear pressure applied to the molten sheet, and without causing a bank (resin pool) between the metal roll 4 and the rubber roll. It becomes easy to form a molten sheet. When the bank is formed, it has a surface having an isotactic crystallinity of 60% or less, and more preferably has the above characteristics (I) and (II), and the diameter of the fine protrusions after corona treatment and It is difficult to obtain a polypropylene film whose number falls within the above range, and there is a tendency that the retardation of the obtained polypropylene film tends to be large. .

  When a rubber roll is used as the elastic roll, it is preferable to insert a support in the gap between the molten sheet and the rubber roll when the molten sheet is sandwiched between the rubber roll and the metal roll. As the support, for example, a biaxially stretched film made of a thermoplastic resin can be used.

  It is preferable to use a support having excellent smoothness. Since the surface opposite to the surface in contact with the metal roll in the molten sheet is in contact with the support and is sandwiched between the rolls, the surface state of the support is transferred to the obtained polypropylene film surface. . Therefore, the smoothness of the obtained surface becomes better as the surface roughness of the support used is smaller and smoother. The surface roughness of the support used is preferably from 0.01 μm to 1.5 μm, more preferably from 0.01 μm to 1.0 μm. Moreover, the thickness of the support body to be used needs to be 5 micrometers or more and less than 50 micrometers, Preferably it is 10 micrometers or more and 30 micrometers or less. When the support used is thinner than 5 μm, it is not preferable because it tends to cause wrinkles, which causes problems in handling. On the other hand, when it is 50 μm or more, the cooling efficiency of the molten sheet deteriorates, and the isotactic crystal A polypropylene film having a surface with a degree of conversion of 60% or less, more preferably having the above characteristics (I) and (II), and having a diameter and number of fine protrusions after corona treatment within the above range is obtained. This is not preferable because it is difficult to form and the transparency of the resulting polypropylene film deteriorates. As the thermoplastic resin constituting the support, any resin that does not strongly heat-fuse with a polypropylene resin may be used. Specifically, polyester, polyamide, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, Such as polyacrylonitrile. Of these, polyesters that undergo little dimensional change due to humidity, heat, etc. are most preferred.

  The melted sheet sandwiched between the rubber roll and the metal roll together with the support is cooled and solidified, and then laminated with the support, and after slitting the end if necessary, a winder The laminate of the polypropylene film and the support can be obtained. It is also possible to peel the support in front of the winder and wind only the polypropylene film. When the support sandwiched between rolls is peeled off from the polypropylene film, the polypropylene film is preferably peeled and removed after the temperature of the polypropylene film is cooled to 60 ° C. or lower, preferably 40 ° C. or lower. If the support is peeled off in a state where the temperature of the polypropylene film is high, the film may be deformed to cause orientation, and the retardation may be increased.

  Among the above-mentioned elastic rolls, it is preferable to use a metal roll that can be elastically deformed because it is excellent in the smoothness of the surface in contact with the elastic roll. The surface of the elastically deformable metal roll is preferably in a mirror state.

(Metal roll)
The metal roll 4 provided in the film manufacturing apparatus 100 shown in FIG. 6 (the same applies to the film manufacturing apparatuses 200 and 300 shown in FIGS. 7 and 8) includes a highly rigid metal outer cylinder 4a and an inner side of the metal outer cylinder 4a. The disposed fluid shaft cylinder 4b, the liquid L filling the space between the metal outer cylinder 4a and the fluid shaft cylinder 4b and the fluid shaft cylinder 4b, and temperature adjusting means for adjusting the temperature of the liquid L (not shown) Z). The fluid shaft cylinder 4b is provided with a plurality of through holes 4c along the circumferential direction thereof. The diameter of the metal roll 4 can be about 200 mm to 600 mm. In the metal roll 4, similarly to the elastic roll, the surface temperature of the metal outer cylinder 4a is indirectly adjusted by adjusting the temperature of the liquid L by a temperature adjusting means (not shown), and the discharge port of the T die 2 together with the elastic roll. The molten sheet discharged from 2a is cooled and solidified.

  Here, in the case of producing a polypropylene film having one surface having a regular uneven surface such as a prism shape or a lens shape, either the elastic roll or the metal roll is provided with a transfer mold. In order to transfer the shape more accurately, it is preferable to provide a transfer mold on the surface of the metal roll. Hereinafter, a metal roll having a transfer mold on the surface is also referred to as a “transfer roll”.

  The transfer mold is provided on the surface of the transfer roll, pressed against the surface of the molten sheet, and transferred to the molten sheet with the surface shape as an inverted mold. The transfer mold is composed of a plurality of recesses provided on the transfer roll surface. The shape of the concave portion, the groove depth, the pitch interval, and the like are determined according to the desired surface irregularity shape of the polypropylene film. The transfer type groove may be parallel to the circumferential direction of the transfer roll, may be parallel to the width direction of the transfer roll, or may form a certain angle with the circumferential direction.

  As a method for producing the transfer mold, a known method can be adopted. For example, the surface of a transfer roll made of stainless steel, steel, or the like is subjected to a plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating, or the like. Examples of a method of processing the shape by performing removal processing using a diamond tool, a metal grindstone, or the like, laser processing, or chemical etching on the plated surface after application.

  Further, the surface of the transfer roll may be subjected to plating treatment such as chromium plating, copper plating, nickel plating, nickel-phosphorous plating, etc. at a level that does not impair the accuracy of the surface shape after the transfer mold is formed.

(Cooling roll)
The cooling roll is a roll for further cooling the molten sheet sandwiched between the elastic roll and the metal roll. The cooling roll 5 provided in the film manufacturing apparatus 100 shown in FIG. 6 (the same applies to the film manufacturing apparatuses 200 and 300 shown in FIGS. 7 and 8) has the same configuration as that of the metal roll 4, and is concrete. Includes a highly rigid metal outer cylinder 5a, a fluid shaft cylinder 5b disposed inside the metal outer cylinder 5a, a space between the metal outer cylinder 5a and the fluid shaft cylinder 5b, and the fluid shaft cylinder 5b. The liquid L and temperature adjusting means (not shown) for adjusting the temperature of the liquid L are provided. The fluid shaft cylinder 5b is provided with a plurality of through holes 5c along the circumferential direction thereof. As the cooling roll 5, a mirror surface having a diameter of about 200 mm to 600 mm and a surface roughness of 0.2 S or less can be used. Similarly, in the cooling roll 5, the surface temperature of the metal outer cylinder 5a is indirectly adjusted by adjusting the temperature of the liquid L by a temperature adjusting means (not shown).

  The molten sheet discharged from the discharge port 2a of the T die 2 is sandwiched between the elastic roll and the metal roll (including the transfer roll), and cooled and solidified to produce a polypropylene film. The pressure (linear pressure) for pinching is determined by the pressure which presses an elastic roll against a metal roll, and is preferably 1 to 300 N / mm, more preferably 1 to 200 N / mm. When the linear pressure is less than 1 N / mm, it is difficult to uniformly control the linear pressure on the molten sheet, and when the metal roll is a transfer roll, it tends to be difficult to transfer the transfer mold with high accuracy. . Further, when the linear pressure exceeds 300 N / mm, the molten sheet is strongly pinched, so that the melted sheet is formed into a bank that is formed while accumulating in the pinched portion, and the isotactic crystal is formed. A polypropylene film having a surface with a degree of conversion of 60% or less, more preferably having the above characteristics (I) and (II), and having a diameter and number of fine protrusions after corona treatment within the above range is obtained. It is difficult to be produced, and a large retardation tends to appear in the obtained polypropylene film.

  As a method for controlling the pressure to be pinched (linear pressure), (1) a method of adjusting a roll interval by installing a triangular wedge-shaped “claw” called a cotter in a portion to be pinched, and adjusting the cotter, (2) A method in which both the elastic roll and the metal roll are pressed until they abut against a cotter adjusted at a predetermined pressure using hydraulic pressure, air, or the like. In addition, there are a method in which the number of rotations of the screw is controlled without using a cotter, and the pressure is mechanically steplessly pressed to a predetermined position, and a method in which a servo motor is used in the hydraulic system.

  Moreover, the distance clamped with an elastic roll and a metal roll is 1-30 mm, Preferably it is 1-15 mm. When the clamping distance is within this range, when the metal roll is a transfer roll, the transfer mold can be accurately transferred. As a method of controlling the pinching distance, (1) a method of adjusting a roll interval by installing a triangular wedge-shaped “claw” called a cotter at a pinching portion and adjusting the cotter; (2) an elastic roll The method of adjusting the elasticity of is generally.

  The surface temperature of the elastic roll and the metal roll at the time of sandwiching the molten sheet is not particularly limited, but the molten sheet can be rapidly cooled, and thereby the surface having an isotactic crystallinity of 60% or less can be obtained. More preferably, a polypropylene film having the above characteristics (I) and (II) and having a diameter and number of fine protrusions after corona treatment within the above range can be easily obtained, and has high transparency. Since the film is easily obtained, the surface temperature of at least one of the elastic roll or the metal roll is preferably 0 to 60 ° C, more preferably the surface temperature of at least one of the rolls is 0 to 40 ° C. More preferably, the surface temperature of at least one roll is 0-30 degreeC.

  In addition, the processing speed of a polypropylene film becomes quick, so that the diameter of metal rolls, such as a transfer roll, is large. For example, when the diameter of the metal roll is 600 mm, the processing speed of the polypropylene film can be set to a maximum of about 50 m / min, usually about 30 m / min.

  The elastic roll and the metal roll are generally arranged in a line below the T die 2. The elastic roll and the metal roll are arranged at a predetermined interval, and the interval between the elastic roll and the metal roll, the rotational speed of the elastic roll, the metal roll and the cooling roll, and the discharge from the discharge port 2a of the T die 2 are discharged. The thickness of the polypropylene film is defined by the discharge amount of the molten sheet.

  The polypropylene film further cooled by the cooling roll is slit (cut) at the ear as necessary, and is wound up by a winder or cut into single sheets. Temporary protective film to protect the surface of the polypropylene film before or after use, before or after slitting (cutting) the ears of the polypropylene film May be laminated.

<Polarizing plate>
9 and 10 are schematic cross-sectional views showing preferred examples of the polarizing plate of the present invention. The polarizing plate of the present invention is a polarizing film 101 and a protective film laminated on one surface of the polarizing film 101 with an adhesive layer 103, like the polarizing plates 10 and 11 shown in FIGS. And at least a polypropylene film. This polypropylene film is the polypropylene film of the present invention having a surface with the above-mentioned isotactic crystallinity of 60% or less, and is laminated on the polarizing film 101 so that the surface is in contact with the adhesive layer 103. The polypropylene film may be a polypropylene film 102a having a flat surface opposite to the adhesive layer 103 as in the polarizing plate 10 shown in FIG. 9, or the polarizing plate 11 shown in FIG. As described above, the surface opposite to the adhesive layer 103 side may be a polypropylene film 102b having a regular uneven shape such as a prism shape or a lens shape.

  As shown in FIGS. 9 and 10, the polarizing plate of the present invention is preferably a resin film 104 such as a protective film or an optical compensation film laminated on the other surface of the polarizing film 101 with an adhesive layer 105 interposed therebetween. Is further provided.

  Since the polarizing plate of the present invention uses the polypropylene film of the present invention, the polarizing film and the protective film are excellent in adhesive strength and have high durability.

  The polarizing plate of the present invention can be used as a viewing side polarizing plate disposed on the viewing side of the liquid crystal cell, or disposed on the back side of the liquid crystal cell (disposed between the liquid crystal cell and the surface light source element). Although it can be used as a back side polarizing plate, the polarizing plate 11 shown in FIG. 10 having a regular uneven shape on the surface is particularly suitable as the back side polarizing plate. Hereinafter, the polarizing plate of the present invention will be described in detail.

(Polarizing film)
Specifically, the polarizing film used in the polarizing plate of the present invention (the polarizing film 101 in FIGS. 9 and 10) is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film. As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film, a saponified polyvinyl acetate resin can be used. Polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith, such as ethylene-vinyl acetate copolymers. Etc. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

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

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known appropriate method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 10-150 micrometers.

  A polarizing film is usually a process of dyeing an original film made of polyvinyl alcohol resin as described above with a dichroic dye and adsorbing the dichroic dye (dyeing process), and the dichroic dye is adsorbed. The polyvinyl alcohol-based resin film is produced through a step of treating with a boric acid aqueous solution (boric acid treatment step) and a step of washing with water after the treatment with the boric acid aqueous solution (water washing treatment step).

  Further, in the production of the polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched, but this uniaxial stretching may be performed before the dyeing treatment step or during the dyeing treatment step, It may be performed after the dyeing process. When uniaxial stretching is performed after the dyeing treatment step, this uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in these plural stages. Uniaxial stretching may be performed uniaxially between rolls having different peripheral speeds, or may be performed uniaxially using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 3 to 8 times.

  The dyeing of the polyvinyl alcohol-based resin film with the dichroic dye in the dyeing treatment step is performed, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine, a dichroic dye or the like is used. Examples of dichroic dyes include C.I. I. Dichroic direct dyes composed of disazo compounds such as DIRECT RED 39, and dichroic direct dyes composed of trisazo, tetrakisazo compounds and the like are included. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

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

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution, usually, 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water, preferably 1 × 10 ^-3 to 1 parts by weight, particularly preferably 1 × 10 ^{- 3} to 1 × 10 ⁻² parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is usually 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 10 to 1800 seconds. is there.

  The boric acid treatment step is performed by immersing a polyvinyl alcohol-based resin film dyed with a dichroic dye in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye in the dyeing process described above, the boric acid-containing aqueous solution used in this boric acid treatment process preferably contains potassium iodide. In this case, the amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  In the subsequent washing process, the polyvinyl alcohol-based resin film after the boric acid treatment described above is washed with water, for example, by immersing it in water. The water temperature in the water washing treatment is usually 5 to 40 ° C., and the immersion time is usually 1 to 120 seconds. After the water washing treatment, a drying treatment is usually performed to obtain a polarizing film. The drying process can be performed using, for example, a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually 30 to 100 ° C, preferably 50 to 80 ° C. The time for the drying treatment is usually 60 to 600 seconds, preferably 120 to 600 seconds.

  Thus, a polarizing film is obtained by subjecting the polyvinyl alcohol-based resin film to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment and water washing treatment. The thickness of the polarizing film is usually in the range of 5 to 40 μm.

(Resin film)
As in the example shown in FIGS. 9 and 10, a protective film or an optical compensation film is provided on the surface of the polarizing film 101 opposite to the surface on which the polypropylene films 102 a and 102 b are laminated via an adhesive layer 105. A resin film 104 such as may be laminated.

  Examples of the resin film 104 include cellulose resin films such as triacetyl cellulose film (TAC film), polyolefin resin films, acrylic resin films, polyester resin films such as polyethylene terephthalate, and the like.

  Examples of the cellulose-based resin constituting the cellulose-based resin film include a partially esterified product or a completely esterified product of cellulose, such as cellulose acetate ester, propionate ester, butyrate ester, and mixed esters thereof. Can be mentioned. More specifically, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate and the like can be mentioned. When such a cellulose resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. Examples of commercially available cellulose ester resin films that can be used as protective films include “Fujitack TD80”, “Fujitack TD80UF”, “Fujitack TD80UZ” (manufactured by FUJIFILM Corporation), “KC8UX2M”, “ KC8UY "(manufactured by Konica Minolta Opto, Inc.).

  Moreover, as an optical compensation film comprising a cellulose resin film, for example, a film containing a compound having a retardation adjusting function in the cellulose resin film; a compound having a retardation adjusting function is applied to the surface of the cellulose resin film. And a film obtained by uniaxially or biaxially stretching a cellulose resin film. Examples of the optical compensation film made of a commercially available cellulose resin film include “WV BZ 438”, “WV EA” (manufactured by FUJIFILM Corporation), “KC4FR-1”, “KC4HR-1” (and above). And Konica Minolta Opto Co., Ltd.).

  The thickness of the protective film or optical compensation film made of a cellulose resin film is not particularly limited, but is preferably in the range of 20 to 90 μm, and more preferably in the range of 30 to 90 μm. When the thickness is less than 20 μm, it is difficult to handle the film. On the other hand, when the thickness exceeds 90 μm, the workability is inferior, and it is disadvantageous in reducing the thickness and weight of the resulting polarizing plate. .

  Examples of the optical compensation film made of the polyolefin resin film include a uniaxially stretched or biaxially stretched cycloolefin resin film. When applied to a liquid crystal panel for a large-sized liquid crystal television, particularly a liquid crystal panel having a vertical alignment (VA) mode liquid crystal cell, as the optical compensation film, a stretched product of a cycloolefin-based resin film has optical characteristics and durability. It is suitable also from this point. Here, the cycloolefin resin film is a film made of a thermoplastic resin having a unit of a monomer made of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer. The cycloolefin-based resin film may be a hydrogenated product of a ring-opening polymer using a single cycloolefin or a hydrogenated product of a ring-opening copolymer using two or more cycloolefins. And an addition copolymer of a chain olefin and / or an aromatic compound having a vinyl group. Further, those having a polar group introduced into the main chain or side chain are also effective.

  Commercially available thermoplastic cycloolefin-based resins are “Topas” sold by TOPAS ADVANCED POLYMERS GmbH in Germany, “Arton” sold by JSR Corporation, and Nippon Zeon Corporation. There are “ZEONOR” and “ZEONEX”, “APEL” (both trade names) sold by Mitsui Chemicals, Inc., and the like, which can be suitably used. A cycloolefin resin film can be obtained by forming such a cycloolefin resin. As a film forming method, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, for example, “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd., “Zeonor Film” sold by Nippon Zeon Co., Ltd., “Arton Film” sold by JSR Co., Ltd. (All are trade names) and the like are also commercially available, and these can also be used suitably.

  If the thickness of the optical compensation film made of the stretched cycloolefin-based resin film is too thick, the workability will be inferior, and the transparency will be lowered, and it will be disadvantageous in reducing the thickness and weight of the polarizing plate. Therefore, the thickness is preferably about 20 to 80 μm.

(Adhesive layer)
The polarizing plate of this invention can be obtained by bonding the said polypropylene film to one surface of the polarizing film mentioned above using an adhesive agent. Thereby, with reference to FIG. 9 and FIG. 10, the polarizing plate by which the polypropylene films 102a and 102b were laminated | stacked on the surface of the polarizing film 101 via the adhesive bond layer 103 is obtained. When the resin film 104 is laminated on the other surface of the polarizing film 101, the bonding between the polarizing film 101 and the resin film 104 is similarly performed using an adhesive. This adhesive forms the adhesive layer 105. When the resin film 104 is bonded to the polarizing film 101, the adhesive used for bonding the polypropylene films 102a and 102b and the adhesive used for bonding the resin film 104 may be the same type of adhesive. It may be a different type of adhesive. Examples of the adhesive used for laminating these films include a water-based adhesive, that is, an adhesive in which an adhesive component is dissolved or dispersed in water, and an adhesive composed of an active energy ray-curable resin composition. Can do.

  Examples of the aqueous adhesive include an aqueous adhesive using a polyvinyl alcohol resin or a urethane resin as an adhesive component.

  When a polyvinyl alcohol-based resin is used as an adhesive component, the polyvinyl alcohol-based resin is not only partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, but also carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and methylol group-modified polyvinyl. It may be a modified polyvinyl alcohol resin such as alcohol and amino group-modified polyvinyl alcohol. Usually, the water-based adhesive having a polyvinyl alcohol resin as an adhesive component is prepared as an aqueous solution of a polyvinyl alcohol resin. The density | concentration of the polyvinyl alcohol-type resin in an adhesive agent is about 1-10 weight part normally with respect to 100 weight part of water, Preferably it is about 1-5 weight part.

  In order to improve the adhesiveness, it is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to the adhesive having a polyvinyl alcohol resin as an adhesive component. Examples of water-soluble epoxy resins include polyamide polyamine epoxy resins obtained by reacting epichlorohydrin with polyamide polyamines obtained by reaction of polyalkylene polyamines such as diethylenetriamine and triethylenetetramine with dicarboxylic acids such as adipic acid. Can be suitably used. Commercially available products of such polyamide polyamine epoxy resins include “Smiles Resin 650” and “Smiles Resin 675” sold by Sumika Chemtex Co., Ltd., and “WS-525” sold by Japan PMC Co., Ltd. Or the like. The addition amount of these curable components or crosslinking agents (the total amount when added together) is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight, relative to 100 parts by weight of the polyvinyl alcohol resin. . When the addition amount of the curable component and the crosslinking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin, the effect of improving adhesiveness tends to be reduced, and the curable component, When the addition amount of the crosslinking agent exceeds 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the adhesive layer tends to become brittle.

  When a urethane resin is used as the adhesive component, examples of suitable adhesive compositions include a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group. Here, the polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the skeleton. Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion. Polyester-based ionomer urethane resins are known per se. For example, JP-A-7-97504 describes an example of a polymer dispersant for dispersing a phenol-based resin in an aqueous medium. In JP-A-2005-070140 and JP-A-2005-181817, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group is used as an adhesive, and a polarizing film made of a polyvinyl alcohol resin is used as a cycloolefin resin. It is shown that a resin film is bonded.

  As a method of applying an adhesive to the surface of a polarizing film and / or a film (polypropylene film or resin film) bonded to the polarizing film, a generally known method may be used. For example, a casting method or a Mayer bar coating method , Gravure coating method, comma coater method, doctor blade method, die coating method, dip coating method, spraying method and the like. The casting method is a method of spreading and spreading an adhesive on the surface of a film to be coated while moving it in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. After apply | coating an adhesive agent, a polarizing film and the film bonded by this are overlap | superposed, and a film is bonded by pinching | interposing with one or several nip rolls. In this case, the material of the nip roll can be metal or rubber. In the case of using a plurality of rolls, the material thereof may be the same or different.

  After the pasting, the polarizing plate can be obtained by drying and curing the adhesive layer. This drying process is performed, for example, by blowing hot air, and the temperature is usually in the range of 40 to 100 ° C., and preferably in the range of 60 to 100 ° C. The drying time is usually 20 to 1200 seconds.

  The thickness of the adhesive layer after drying is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, and more preferably 0.01 to 1 μm. If the thickness of the adhesive layer after drying is less than 0.001 μm, the adhesion may be insufficient, and if the thickness of the adhesive layer after drying exceeds 5 μm, the appearance of the polarizing plate is poor. May occur. In addition, it is preferable that the thickness of the adhesive bond layer after bonding using the said nip roll etc. before drying and hardening is 5 micrometers or less, and it is preferable that it is 0.01 micrometers or more.

  After the drying treatment, sufficient adhesive strength may be obtained by performing curing at a temperature of room temperature or higher for at least half a day, usually 1 day or longer. Such curing is typically performed in a state of being wound in a roll. The preferable curing temperature is in the range of 30-50 ° C, more preferably 35-45 ° C. When the curing temperature exceeds 50 ° C., so-called “roll tightening” is likely to occur in the roll winding state. The humidity during curing is not particularly limited, but is preferably selected so that the relative humidity is in the range of about 0% RH to 70% RH. The curing time is usually about 1 to 10 days, preferably about 2 to 7 days.

  Moreover, as an adhesive agent which consists of the said active energy ray curable resin composition, the photocurable adhesive agent etc. which consist of a mixture of a photocurable epoxy resin and a photocationic polymerization initiator are mentioned, for example. Examples of the photocurable epoxy resin include alicyclic epoxy resins, epoxy resins having no alicyclic structure, and mixtures thereof. The photocurable adhesive may contain an acrylic resin, an okitacene resin, a urethane resin, a polyvinyl alcohol resin, etc. in addition to the photocurable epoxy resin, and together with the photocationic polymerization initiator or the photocationic polymerization initiator. Instead of this, a radical photopolymerization initiator may be included. When an adhesive composed of an active energy ray-curable resin composition is used, the resulting adhesive layer is composed of a cured product layer of the composition.

  In the case of using a photocurable adhesive, the photocurable adhesive is applied to the polarizing film and / or the film (polypropylene film or resin film) bonded to the polarizing film, and after these films are bonded, the activity The photocurable adhesive is cured by irradiating with energy rays. The application method of a photocurable adhesive and the bonding method of a film can be made the same as that of an aqueous adhesive. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low pressure mercury lamp, the medium pressure mercury lamp, the high pressure mercury lamp, the ultrahigh pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW. / Cm ² is preferable. If the irradiation intensity is 0.1 mW / cm ² or more, not too long reaction times, if it is 6000mW / cm ² or less, due to heat generation during the curing of heat and light-curing adhesive is radiated from the light source There is little risk of yellowing of the epoxy resin and deterioration of the polarizing film. The light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive to be cured and is not particularly limited. However, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10. It is preferably set to be 10000 mJ / m ² . When the cumulative amount of light to the photocurable adhesive is 10 mJ / m ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and 10000 mJ / m ^2. In the case of the following, the irradiation time does not become too long, and good productivity can be maintained.

  When curing a photo-curable adhesive by irradiation with active energy rays, the curing should be performed under conditions that do not deteriorate the functions of the polarizing plate such as the degree of polarization, transmittance and hue of the polarizing film, and transparency of the polypropylene film and resin film. It is preferable to do so.

  The thickness of the adhesive layer after irradiation with active energy rays is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, and more preferably 0.01 to 1 μm.

  The adhesive forming the adhesive layer may be any of the above-mentioned water-based adhesive and an adhesive made of an active energy ray-curable resin composition, but from the viewpoint of productivity, the active energy ray-curable resin composition It is preferable to use an adhesive made of a material.

  Prior to the bonding of the polypropylene film and the resin film to the polarizing film, plasma treatment, corona treatment, and ultraviolet irradiation are performed to improve the adhesiveness on the adhesive surface of the polarizing film and / or the film to be bonded thereto. Surface treatment such as treatment, flame (flame) treatment, and saponification treatment may be performed. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide. In particular, it is preferable to apply a corona treatment to the adhesive surface (surface having an isotactic crystallinity of 60% or less) of the polypropylene film.

  The corona treatment is a treatment for activating the surface of the film disposed between the electrodes by discharging by applying a high voltage between the electrodes. The effect of corona treatment varies depending on the type of electrode, electrode spacing, voltage, humidity, material of the film to be bonded, etc., but in the present invention, in order to improve the adhesion between the polarizing film and the polypropylene film, For example, it is preferable to set the electrode interval to 1 to 5 mm and the moving speed to about 3 to 20 m / min. Corona treatment may be performed multiple times on the same surface. The ambient temperature and ambient relative humidity during the corona treatment can be set, for example, to about 0 to 40 ° C. and about 17 to 70% RH, respectively. However, the ambient relative humidity during the corona treatment is preferably adjusted so that no condensation occurs on the corona treatment surface.

(Adhesive layer)
An adhesive layer for bonding the liquid crystal cell and the polarizing plate may be formed on the surface of the polarizing film opposite to the surface on which the polypropylene film is laminated. When a resin film such as a protective film or an optical compensation film is laminated on the surface of the polarizing film opposite to the surface on which the polypropylene film is laminated, a liquid crystal cell and a polarizing plate are bonded on the resin film. An adhesive layer can be formed.

  As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, a conventionally known appropriate pressure-sensitive adhesive can be used, and examples thereof include an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer can be provided by a method in which such a pressure-sensitive adhesive is, for example, an organic solvent solution, which is applied onto a base film (for example, a polarizing film) by a die coater or a gravure coater and dried. Moreover, it can provide also by the method of transcribe | transferring the sheet-like adhesive formed on the plastic film (it is called a separate film) to which the mold release process was given to a base film. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably in the range of 2 to 40 μm.

<Liquid crystal panel and liquid crystal display device>
FIG. 11 is a schematic cross-sectional view showing a preferred example of the liquid crystal panel of the present invention and a liquid crystal display device using the same. The liquid crystal display device shown in FIG. 11 according to the present invention includes a light source plate 30 and a surface light source element 30 including a light source device 31 that is disposed on one side of the light guide plate 32 on the side of the light guide plate 32. The liquid crystal panel 20 is disposed on the surface light source element 30. The liquid crystal panel 20 includes a liquid crystal cell 13, a polarizing plate 11 that is a back side polarizing plate laminated on one surface of the liquid crystal cell 13 (surface on the surface light source element 30 side), and the other surface of the liquid crystal cell 13 (viewing). The polarizing plate 12 is a viewing-side polarizing plate laminated on the side surface. In the example shown in FIG. 11, the polarizing plate 11 is a polarizing plate provided with a polypropylene film 102b having a prism-shaped surface shown in FIG. The polarizing plates 11 and 12 are bonded to the liquid crystal cell 13 via the adhesive layers 106a and 106b, respectively.

  The polarizing plate 11, which is a back side polarizing plate, is bonded to the liquid crystal cell 13 on the resin film 104 side. More specifically, the liquid crystal cell 13 and the polarizing plate 11 are made of a polypropylene film 102 b in the polarizing film 101. The surface opposite to the surface on which the layers are stacked faces the liquid crystal cell 13, that is, the prism-shaped surface of the polypropylene film 102b forms the surface light source element-side surface of the liquid crystal panel 20, and the prism-shaped surface It is bonded so as to face the light source element 30.

  The liquid crystal panel 20 having the above configuration and the liquid crystal display device using the same are excellent in durability since the polarizing plate of the present invention is used as the back side polarizing plate. In addition, since the polypropylene film 102b also has a function of deflecting light from the surface light source element 30 as well as a function as a polarizing plate protective film, a conventionally used film having a light deflection function can be omitted. As a result, a thin liquid crystal display device is achieved. The back side polarizing plate of the liquid crystal panel is not necessarily the polarizing plate according to the present invention, and may be a conventionally known polarizing plate.

  In the liquid crystal display device of the present invention, the polarizing plate 12 that is the viewing side polarizing plate may be the polarizing plate of the present invention, or may be a conventionally known polarizing plate.

  The type of the liquid crystal cell 13 is not particularly limited, and is a conventionally known liquid crystal cell such as a vertical alignment (VA) mode, a twisted birefringence (TN) mode, a supertwisted birefringence (STN) mode, and a transverse electric field (IPS) mode. It's okay.

  In the liquid crystal display device of the present invention, as the surface light source element, a direct type light source using a diffusion plate, an edge type light source using a light guide plate, or the like can be used. As shown in FIG. It is preferable to use an edge-type light source (surface light source element 30) including the light source device 31 disposed on the side of the light guide plate 32. As the light guide plate 32, for example, a flat plate or wedge-shaped member made of a transparent resin such as an acrylic resin can be used. A pattern is added to the back surface or both surfaces of the light guide plate by screen printing using ink, etching, or blasting. In addition, a minute reflection element or a minute refraction element having a reflection function may be formed on the back surface or both surfaces of the light guide plate.

  As the light source device 31, a light source device in which point light sources such as LEDs are arranged in a line, or a light source device including a rod-like light source such as a cold cathode tube can be used. In the liquid crystal display device of the present invention, the surface light source may have one light source device arranged on one side of the light guide plate, or two light source devices arranged on two sides facing the light guide plate. You may do it.

  In the liquid crystal display device of the present invention, a conventionally known appropriate configuration can be adopted for configurations other than those described above. For example, the liquid crystal display device of the present invention may further include a light diffusing plate, a light diffusing sheet, a reflecting plate, and the like.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not prescribed | regulated by these examples. In addition, the isotactic crystallinity of the surface of the polypropylene film produced in the following example, diffraction profile by thin film X-ray diffraction method, surface softening temperature, surface shape after corona treatment, thickness, haze, and in-plane retardation value R _e and the melt flow rate (MFR) and melting point of the polypropylene resin containing isotactic used for the production of the polypropylene film were measured using the following apparatus and measurement conditions.

(1) Surface Isotactic Crystallinity Infrared spectroscopic spectrum measurement by the attenuated total reflection method [Attenuated Total Reflection (ATR) method] was performed with the following apparatus and measurement procedure.
Apparatus: Infrared spectrophotometer DIGILAB FTS7000, microscope system UMA600 Stingray (all manufactured by Varian Technologies Japan),
Measurement mode: ATR method (Ge 30 °),
・ Resolution: 4cm ^-1
・ Total number of times: 64 times
ATR-IR measurement procedure: The IR spectrum was measured by directly pressing the polypropylene film surface against a Ge (germanium) crystal prism.

Then, based on the obtained infrared spectrum, the following formula:
Isotactic crystallinity X (%) = 109 × (A ₉₉₈ -A ₉₂₀ ) / (A ₉₇₄ -A ₉₂₀ ) -31.4
Was used to determine the isotactic crystallinity X. In the above formula, A ₉₉₈ , A ₉₇₄ and A ₉₂₀ are absorbances at wave numbers ₉₉₈ , ₉₇₄ and ₉₂₀ cm ⁻¹ , respectively.

(2) Surface Diffraction Profile A surface diffraction profile obtained by a thin film X-ray diffraction method was obtained using the following apparatus and measurement conditions.
・ Device: Multifunctional X-ray diffractometer for surface structure evaluation (manufactured by Rigaku Corporation),
X-ray source: CuKα ray,
-Tube voltage-tube current: 50 kV-300 mA,
-Incident optical system (I): Artificial multilayer parabolic mirror (half-value width 0.057 °)
1st slit (width 1.0mm, height 10mm),
-Incident optical system (II): Solar slit (Vertical divergence suppression, 0.48 °)
Second slit (width 0.2 mm, height 10 mm),
-Light receiving optical system (detection unit): solar slit (vertical divergence suppression, 0.41 °),
Scanning axis: 2θχ / φ (In-Plane diffraction method),
-Incident angle (ω): 0.13 ° ± 0.01 °,
・ Measurement interval: 0.02 °,
Measurement speed: 5 ° / min.

  Next, the position (2θ) of the peak with the highest intensity (hereinafter referred to as the first peak) and the peak with the second highest intensity (hereinafter referred to as the second peak) were extracted from the obtained diffraction profile.

(3) Surface softening temperature Using the following measuring device, heat was applied to the film at a temperature increase rate of 15 ° C./s from room temperature, and the temperature at which the surface started to soften was measured. In order to measure the accurate surface softening temperature of the sample, a calibration curve was first created, and then the sample was measured. As calibration samples, polycaprolactone (surface softening temperature: 55 ° C.), polymethyl methacrylate (PMMA, surface softening temperature: 131.5 ° C.), polyethylene terephthalate (PET, surface softening temperature: 235 ° C.) Was used. Measurement was performed twice or three times at different measurement positions, and the average value was defined as the surface softening temperature.
-Apparatus: Local thermal analysis system Nano-TA2 (model name and model number, manufactured by Anasys Instruments),
Measurement mode: Closed contact mode (5 μm square, scan speed: 1 Hz),
Cantilever: AN2-200 (Anasys Instruments)

(4) Surface shape after corona treatment After performing corona treatment on the polypropylene film surface under the following conditions, the surface shape of the corona treatment surface is measured with the following apparatus and measurement conditions, and by the following image analysis, The average diameter of the fine protrusions present on the corona-treated surface and the number of fine protrusions per square μm were determined.

(Corona treatment conditions)
Using a corona treatment device (high-frequency power source; CT-0212 manufactured by Kasuga Electric Co., Ltd., transmitter body; CT-0212 manufactured by Kasuga Electric Co., Ltd., high voltage transformer; CT-T022 manufactured by Kasuga Electric Co., Ltd.), the surface of the polypropylene film and the electrodes of the corona treatment device The corona treatment was performed three times continuously under the conditions of an output of 280 W, a line speed of 1.0 m / min, an ambient temperature of 23 ° C., and an ambient relative humidity of 55% RH.

(Surface shape observation)
-Apparatus: Local thermal analysis system Nano-TA2 (model name and model number, manufactured by Anasys Instruments),
Measurement mode: Closed contact mode (5 μm square, resolution (number of measurement points per scanning line); 512, scan speed: 1 Hz),
Cantilever: P-MAN-SICC-0 (PACIFIC NANOTECHNOLOGY),
・ Measurement temperature: Room temperature.

(Image analysis)
・ Software: Image analysis software SPIP (Image Metrology),
Analytical conditions: First, the captured 5 μm square image was tilt-corrected with the above-described tilt correction diagram of the software, and subsequently filtered with 50 pixels × 50 pixels to correct a large swell. Next, using the “grain analysis” tool of the above software for the obtained corrected image, a branch line between adjacent fine projections is detected as a segment type; particle, detection method; branch line, and a 5 μm square image is obtained. Calculating the bottom area of each microprojection contained in the surface, assuming that the bottom surface of the microprojection is a circle with the same area as the calculated bottom area, obtaining the diameter of each microprojection, and calculating the average of these In addition, the number of fine protrusions per square μm was determined.

(5) Thickness of polypropylene film The thickness of 5 points | pieces was measured using the contact-type thickness meter (NI-5ON make MS-5C), and the average value was made into the thickness of a polypropylene film.

(6) Haze of polypropylene film It measured using the haze meter "HM-150" type | mold made from Murakami Color Research Laboratory based on JISK7136.

(7) plane retardation value R _e polypropylene film
It measured using the phase difference measuring apparatus (Oji Scientific Instruments Co., Ltd. product, KOBRA-WPR).

(8) Melt flow rate (MFR) of polypropylene resin containing isotactic
According to JIS K7210, the measurement was performed at a temperature of 230 ° C. and a load of 21.18 N.

(9) Melting point Tm of polypropylene-based resin containing isotactic
A polypropylene resin containing isotactic was hot press molded to produce a sheet having a thickness of 0.5 mm. In this hot press molding, a polypropylene resin containing isotactic material is preheated at 230 ° C. for 5 minutes in a hot press machine, then pressurized to 50 kgf / cm ² over 3 minutes and held for 2 minutes, then at 30 ° C. and 30 kgf / Press to cool at cm ² for 5 minutes. About 10 mg of the slice of the produced press sheet, a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer Co.) was used, and after adding the thermal history of [1] to [5] below in a nitrogen atmosphere, 50 ° C. To 180 ° C. at a heating rate of 5 ° C./min to prepare a melting curve. In this melting curve, the temperature (° C.) showing the highest endothermic peak was determined, and this was taken as the melting point Tm of the polypropylene resin containing isotactic.
[1] Heat at 220 ° C. for 5 minutes.
[2] Cooling from 220 ° C. to 150 ° C. at a temperature drop rate of 300 ° C./min.
[3] Incubate at 150 ° C. for 1 minute.
[4] Cool from 150 ° C. to 50 ° C. at a temperature drop rate of 5 ° C./min.
[5] Incubate at 50 ° C for 1 minute.

<Example 1: Production of polypropylene film 1>
Using the film production apparatus 200 shown in FIG. 7, the polypropylene film 1 was produced by the following procedure. First, an isotactic polypropylene resin A (propylene homopolymer, MFR = 7 g / 10 min, Tm = 164 ° C.) heated to 270 ° C. 50 mmφ extruder 1 (screw: L / D = 32, full The melt is kneaded with a flight screw) and fed from the extruder 1 to the gear pump, adapter, and T-die 2 (all set at 270 ° C.) installed after the extruder 1 in this order. A polypropylene resin sheet (molten resin) in a molten state was discharged from the outlet 2a (lip port). The temperature of the molten resin at the discharge port portion of the T die 2 was 270 ° C. Then, the molten resin is sandwiched between an elastic roll 6 (no transfer mold) and a metal roll 4 (no transfer mold) under the manufacturing conditions shown in Table 1, and further cooled by a metal roll 5 to produce a polypropylene film 1. did. The resulting film had a thickness 107.1Myuemu, haze 1.3%, in-plane retardation value R _e was 20.6 nm.

  The “clamping distance” shown in Table 1 indicates the length that the molten resin is clamped between the elastic roll 6 and the metal roll 4. The pressure paper (Fuji Film Business Supply Co., Ltd. pre-scale LLW) was sandwiched, and the distance in the MD direction of the colored portion of the pressure-sensitive paper was measured and used as the pressure distance. Moreover, the used elastic roll 6, the metal roll 4, and the cooling roll 5 have the following structures.

(Elastic roll 6)
Strip 6a: made of metal, surface roughness 0.2S, thickness 300 μm,
Roll 6b: made of silicone, diameter 160mm, hardness 60,
Roll 6c: metal, diameter 160mm,
(Metal roll 4)
Metal outer cylinder 4a: metal, diameter 300mm,
(Cooling roll 5)
Metal outer cylinder 5a: made of metal, diameter 300 mm, surface roughness 0.1S (mirror surface).

<Examples 2-6 and Comparative Examples 1-2: Production of polypropylene films 2-8>
In the same manner as in Example 1 except that the film production conditions (surface temperature, clamping distance, linear pressure and line speed of metal roll 4 and elastic roll 6) were changed as shown in Table 1, polypropylene films 2 to 8 were used. Was made. The thickness of the obtained polypropylene film, the haze and the in-plane retardation value R _e are also shown in Table 1.

  In addition, isotactic crystallinity of the first surface (surface cooled and solidified by the metal roll 4) and the second surface (surface cooled and solidified by the elastic roll 6) of the obtained polypropylene films 1 to 8, Table 2 summarizes the positions (2θ) of the first and second peaks extracted from the diffraction profile, the surface softening temperature, the diameter of the fine protrusions present on the corona-treated surface, and the number of fine protrusions per square μm. 12 to 15 show the first surface and the second surface of the polypropylene film 1 obtained in Example 1, the first surface and the second surface of the polypropylene film 8 obtained in Comparative Example 2, respectively. It is a diffraction profile.

<Example 7: Production of polarizing plate>
(1) Preparation of polarizing film A polyvinyl alcohol film having an average degree of polymerization of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was immersed in pure water at 30 ° C., and then the weight of iodine / potassium iodide / water. It was immersed at 30 ° C. in an aqueous solution having a ratio of 0.02 / 2/100. Then, it was immersed at 56.5 ° C. in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100. Subsequently, the film was washed with pure water at 8 ° C. and then dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

(2) Preparation of UV curable adhesive Trade name “Epicoat YX8000” (diglycidyl ether of nuclear hydrogenated bisphenol A, which is a hydrogenated epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. 10.0 g having an equivalent weight, 4.0 g of a product name “CI5102” which is a photocationic polymerization initiator manufactured by Nippon Soda Co., Ltd., and a product name “CS7001” which is a photosensitizer manufactured by Nippon Soda Co., Ltd. ”1.0 g was weighed into a 100 ml disposable cup, mixed and defoamed to prepare an ultraviolet curable adhesive.

(3) Production of Polarizing Plate On one surface of the polarizing film, the first surface of any of the polypropylene films 1 to 8 obtained in Examples 1 to 6 and Comparative Examples 1 and 2 (cooled by the metal roll 4). The surface is solidified) or the second surface (the surface cooled and solidified by the elastic roll 6) is used as a bonding surface, and is bonded using the ultraviolet curable adhesive, and the other surface is a cycloolefin film. (ZEONOR 75 μm, manufactured by Nippon Zeon Co., Ltd.) was bonded using the ultraviolet curable adhesive. In addition, a corona treatment device (high frequency power source: CT-0212 manufactured by Kasuga Electric Co., Ltd., transmitter body: CT-0212 manufactured by Kasuga Electric Co., Ltd., high voltage transformer; CT-T022), and adjusted so that the distance between the polypropylene film surface and the electrode of the corona treatment device is 3 mm, output 280 W, line speed 1.0 m / min, ambient temperature 23 ° C., ambient relative humidity 55% RH Under these conditions, the corona treatment was performed three times in succession. Next, by passing it once through a UV irradiation device manufactured by Nippon Batteries Co., Ltd. (UV lamp uses “HAL400NL” at 80 W and irradiation distance is 50 cm) at a line speed of 1.0 m / min. The ultraviolet curable adhesive was cured to obtain a polarizing plate.

(Evaluation of adhesion between polarizing film and polypropylene film)
For the 16 polarizing plates obtained in Example 7, the adhesion between the polarizing film and the polypropylene film was evaluated by the following method. First, a cut was made using a cutter on the polypropylene film side to confirm whether or not peeling occurred. Next, the cutter blade was inserted between the polypropylene film and the polarizing film and pushed forward to confirm the ease of entry of the cutter blade. The evaluation test was conducted, and the adhesion was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2.
A: The blade of the cutter does not advance at all and the adhesiveness is high.
B: The blade of the cutter advances a little, but stops immediately, and the adhesiveness is relatively high.
C: Although there is no peeling at the time of making the cut, the blade of the cutter is pushed forward, the two films are separated, and the adhesiveness is relatively low.
D: Peeling occurs when the cut is made, and the adhesiveness is low.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 Extruder, 2 T die, 2a Discharge port, 2b Manifold, 3, 6, 7 Elastic roll, 3a, 6a Strip, 3b Rubber roll, 4 Metal roll, 4a, 5a Metal outer cylinder, 4b, 5b, 7c Fluid shaft cylinder, 4c, 5c, 7d through hole, 5 cooling roll, 6b, 6c roll, 7a metal inner cylinder, 7b thin metal outer cylinder, 10, 11, 12 polarizing plate, 13 liquid crystal cell, 20 liquid crystal panel, 30 surfaces Light source element, 31 Light source device, 32 Light guide plate, 100, 200, 300 Film manufacturing device, 101 Polarizing film, 102a, 102b Polypropylene film, 103, 105 Adhesive layer, 104 Resin film, 106a, 106b Adhesive layer.

Claims (10)

It is a polypropylene film obtained by melting and kneading a polypropylene-based resin containing isotactic and discharging it from a T die into a film, sandwiching it with an elastic roll and a metal roll, and cooling and solidifying it,
At least one surface is a polypropylene film comprising a surface having an isotactic crystallinity of 60% or less obtained by infrared spectroscopic measurement by an attenuated total reflection method.   In the diffraction profile of the surface having an isotactic crystallinity of 60% or less obtained by thin film X-ray diffraction method, the highest peak 2θ is 14.6 degrees, and the second highest peak The polypropylene film according to claim 1, wherein 2θ is 21.2 degrees.   The polypropylene film according to claim 1 or 2, wherein the surface softening temperature of the surface having the isotactic crystallinity of 60% or less is 100 degrees or more and 120 degrees or less.   For the surface with the isotactic crystallinity of 60% or less, three consecutive corona treatments under the conditions of an output of 280 W, a line speed of 1.0 m / min, and a distance of 3 mm between the surface and the electrode of the corona treatment device. The average diameter of the fine protrusions existing on the corona-treated surface is 10 nm or more and 115 nm or less, and the number of the fine protrusions per square μm is 30 or more and 100 or less. The polypropylene film according to any one of the above. One surface consists of a surface having an isotactic crystallinity of 60% or less,
The polypropylene film according to any one of claims 1 to 4, wherein the other surface is an uneven surface having a prism shape or a lens shape. A polarizing film comprising a uniaxially stretched polyvinyl alcohol-based resin film in which iodine or a dichroic dye is adsorbed and oriented;
A polarizing plate comprising the polypropylene film according to any one of claims 1 to 5 laminated on one surface of the polarizing film via an adhesive layer,
The polypropylene film is a polarizing plate that is laminated so that the surface of which the isotactic crystallinity is 60% or less is in contact with the adhesive layer.   The said adhesive bond layer is a polarizing plate of Claim 6 which consists of a hardened | cured material layer of the active energy ray curable resin composition containing an epoxy resin.   The polarizing plate of Claim 6 or 7 provided with the protective film or optical compensation film laminated | stacked on the surface on the opposite side to the surface where the said polypropylene film is laminated | stacked in the said polarizing film.   A liquid crystal panel provided with a liquid crystal cell and the polarizing plate in any one of Claims 6-8 laminated | stacked on the said liquid crystal cell.   A liquid crystal display device comprising a surface light source element and the liquid crystal panel according to claim 9.

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