KR102129192B1 - Laminate and method of manufacturing the laminate - Google Patents

Abstract

The present invention provides a laminate having both excellent adhesion and excellent appearance. The laminate of the present invention has a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate. The resin substrate side of the polyvinyl alcohol-based resin layer is an intermediate region in which a polyolefin component is present.

Description

Laminate and method of manufacturing the laminate

The present invention relates to a laminate having a polyvinyl alcohol-based resin layer.

A method of obtaining a polarizing film by forming a polyvinyl alcohol-based resin layer on a resin substrate and stretching and dyeing the laminate is proposed (for example, Patent Document 1). According to such a method, since a thin polarizing film is obtained, it is attracting attention that it can contribute to, for example, thinning of an image display device.

The polarizing film may be used while being laminated on the resin substrate. In such an embodiment, it is required that the polyvinyl alcohol-based resin layer (polarizing film) and the resin substrate have sufficient adhesiveness. Specifically, in the production of a polarizing film (for example, in stretching and conveying), the polyvinyl alcohol-based resin layer will not peel off from the resin substrate, and the polarizing film and the resin base will not peel off during rework, It is required that the polarizing film or the resin substrate will not be lifted during processing (for example, punching) or impact during use.

In order to improve the adhesiveness, it has been proposed to form a base layer containing a polyvinyl alcohol-based material between a resin substrate and a polyvinyl alcohol-based resin layer (Patent Document 2). However, when forming the undercoating layer, there is a problem that an excellent appearance is not obtained well.

Japanese Patent Application Publication No. 2000-338329 Japanese Patent No. 4950357

The present invention has been made to solve the above problems, and its main purpose is to provide a laminate having both excellent adhesion and excellent appearance.

According to the present invention, a laminate is provided. The laminate of the present invention has a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate. The resin substrate side of the polyvinyl alcohol-based resin layer is an intermediate region in which a polyolefin component is present.

In one embodiment, the intermediate region contains a polyvinyl alcohol-based component and a polyolefin-based component.

In one embodiment, the polyvinyl alcohol-based component contains acetoacetyl-modified polyvinyl alcohol.

In one embodiment, the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component is 5:95 to 60:40.

In one embodiment, the thickness of the intermediate region is 100 nm to 1000 nm.

According to another aspect of the present invention, a method for manufacturing a laminate is provided. The manufacturing method of this laminate is a step of forming a base layer by applying a composition for forming a base layer containing a polyolefin component on one side of a resin substrate, and a coating liquid containing a polyvinyl alcohol-based resin on the surface of the base layer. And forming a polyvinyl alcohol-based resin coating layer.

In one embodiment, the composition for forming the undercoating layer contains a polyvinyl alcohol-based component and a polyolefin-based component.

In one embodiment, the polyvinyl alcohol-based component contains acetoacetyl-modified polyvinyl alcohol.

In one embodiment, the mixing ratio of the solid content of the polyvinyl alcohol-based component and the polyolefin-based component is 5:95 to 60:40.

In one embodiment, the thickness of the undercoat layer is 500 nm to 3000 nm.

According to another aspect of the present invention, a method of manufacturing a polarizing plate is provided. The manufacturing method of this polarizing plate includes the process of extending|stretching and dyeing the laminated body obtained by the said manufacturing method.

According to another aspect of the present invention, a polarizing plate is provided. This polarizing plate has a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate. The resin substrate side of the polyvinyl alcohol-based resin layer is an intermediate region in which a polyolefin component is present, and the polyvinyl alcohol-based resin layer is a polarizing film in which a dichroic substance is adsorbed and oriented.

In one embodiment, the intermediate region contains a polyvinyl alcohol-based component and a polyolefin-based component.

In one embodiment, the polyvinyl alcohol-based component contains acetoacetyl-modified polyvinyl alcohol.

In one embodiment, the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component is 5:95 to 60:40.

In one embodiment, the thickness of the intermediate region is 100 nm to 1000 nm.

According to the present invention, by setting the resin substrate side of the polyvinyl alcohol-based resin layer as an intermediate region in which a polyolefin component is present, a laminate having both excellent adhesion and excellent appearance can be obtained.

1 is an SEM observation photograph of a cross section of a laminate of Examples and Comparative Examples.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Laminate

The laminate of the present invention has a resin substrate and a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") layer formed on one side of the resin substrate, and at least a polyolefin-based component is present on the resin substrate side of the PVA-based resin layer. It is an intermediate region. In one embodiment, the intermediate region substantially corresponds to a primer layer to be described later, and the PVA-based resin layer includes a primer layer and a PVA-based resin coating layer to be described later. In another embodiment, the PVA-based resin layer substantially constitutes a single layer, and the intermediate region is, for example, a commercial region of the PVA-based resin coating layer and the undercoat layer. Further, the PVA-based resin layer may be a polarizing film by various treatments, and the laminate may be a polarizing plate.

A-1. Resin base

Any suitable material may be employed as the constituent material of the resin substrate. For example, ester resins such as polyethylene terephthalate resins, cycloolefin resins, olefin resins such as polypropylene, (meth)acrylic resins, polyamide resins, polycarbonate resins, and copolymer resins thereof Can be lifted. Preferably, a polyethylene terephthalate-based resin is used. Among them, an amorphous polyethylene terephthalate-based resin is preferably used. Specific examples of the amorphous polyethylene terephthalate-based resin include copolymers further containing isophthalic acid as dicarboxylic acid, and copolymers further containing cyclohexanedimethanol as glycol.

The glass transition temperature (Tg) of the resin base material is preferably 170° C. or less. By using such a resin base material, it is possible to sufficiently secure stretchability while suppressing crystallization of the PVA-based resin layer. Considering that the plasticization of the resin substrate with water and stretching in water are satisfactory, it is more preferably 120°C or lower. In one embodiment, the glass transition temperature of the resin substrate is preferably 60°C or higher. By using such a resin substrate, problems such as deformation of the resin substrate (for example, unevenness, sagging, wrinkles, etc.) can be prevented when the coating liquid containing the PVA-based resin described later is applied and dried. have. Moreover, extending|stretching of a laminated body can be performed at preferable temperature (for example, about 60 degreeC-70 degreeC). In another embodiment, if the resin substrate is not deformed when the coating liquid containing the PVA-based resin is applied and dried, a glass transition temperature lower than 60°C may be used. In addition, the glass transition temperature (Tg) is a value calculated according to JIS K 7121.

In one embodiment, the resin substrate preferably has an absorbency of 0.2% or more, and more preferably 0.3% or more. Such a resin substrate absorbs water, and water can be plasticized by performing a plasticizer function. As a result, the stretching stress in water stretching can be significantly reduced, and the stretching performance can be excellent. On the other hand, the water absorption of the resin substrate is preferably 3.0% or less, and more preferably 1.0% or less. By using such a resin substrate, it is possible to prevent problems such as deterioration of the dimensional stability of the resin substrate at the time of manufacture and deterioration of the appearance of the resulting laminate. Moreover, it can prevent that it break|ruptures at the time of extending|stretching underwater, and peeling of a PVA system resin film from a resin base material. In addition, water absorption is a value calculated|required according to JISK 7209.

The thickness of the resin substrate is preferably 20 μm to 300 μm, more preferably 30 μm to 200 μm.

The surface of the resin substrate may be subjected to a surface modification treatment (for example, corona treatment, etc.) in advance, or an easily bonding layer may be formed. According to such a process, adhesiveness can be improved further.

A-2. PVA-based resin layer

Any suitable resin may be employed as the PVA-based resin forming the PVA-based resin layer. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are mentioned. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined according to JIS K 6726-1994. By using a PVA-based resin having such saponification degree, a polarizing film excellent in durability can be obtained. When the degree of saponification is too high, there is a possibility of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the purpose. The average polymerization degree is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. In addition, the average degree of polymerization can be obtained in accordance with JIS K 6726-1994.

The thickness of the PVA-based resin layer is typically 20 μm or less, preferably 15 μm or less. When the PVA-based resin layer is made of a polarizing film, the thickness is preferably 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less, particularly preferably 6 μm or less. On the other hand, the thickness of the PVA-based resin layer is preferably 1.0 μm or more, and more preferably 2.0 μm or more.

When the PVA-based resin layer is a polarizing film, the PVA-based resin layer is substantially in a state in which dichroic substances are adsorbed and oriented, and preferably exhibits absorption dichroism at a wavelength of 380 nm to 780 nm. In this case, the simplex transmittance of the PVA-based resin layer is preferably 40.0% or more, more preferably 41.0% or more, still more preferably 42.0% or more, and particularly preferably 43.0% or more. The polarization degree of the PVA-based resin layer is preferably 99.8% or more, more preferably 99.9% or more, still more preferably 99.95% or more.

As described above, the resin substrate side of the PVA-based resin layer is an intermediate region in which a polyolefin component is present. By forming such a region, excellent adhesion and excellent appearance can be achieved. The thickness of the intermediate region is, for example, 100 nm to 1000 nm. The intermediate region can be confirmed, for example, by observing the cross section of the laminate with a scanning electron microscope (SEM). In addition, the presence or absence of a polyolefin-based component can be confirmed by, for example, time-of-flight secondary ion mass spectrometry (TOF-SIMS) or infrared spectroscopy (IR). In one embodiment, the intermediate region contains a polyvinyl alcohol-based component and a polyolefin-based component. In addition, the details of the polyolefin-based component and the polyvinyl alcohol-based component will be described later.

B. Manufacturing method

The laminate of the present invention can be produced by any suitable method as long as the above structure is obtained. In one embodiment, a step of forming a base layer by applying a composition for forming a base layer containing a polyolefin-based component on one side of the resin substrate, and applying a coating liquid containing a PVA-based resin on the surface of the base layer It is manufactured by the method including the process of forming a PVA system resin coating layer.

B-1. Formation of the undercoat layer

The composition for forming the undercoating layer preferably contains a polyvinyl alcohol-based component and a polyolefin-based component. By setting it as such a composition, the laminated body which has excellent adhesiveness and excellent appearance can be obtained. As the polyvinyl alcohol-based component, any suitable PVA-based resin can be used. Specifically, polyvinyl alcohol and modified polyvinyl alcohol are mentioned. Examples of the modified polyvinyl alcohol include polyvinyl alcohol modified with acetoacetyl group, carboxylic acid group, acrylic group and/or urethane group. Among these, acetoacetyl-modified PVA is preferably used. As acetoacetyl-modified PVA, a polymer having at least a repeating unit represented by the following general formula (I) is preferably used.

[Formula 1]

In the formula (I), the ratio of n to l + m + n is preferably 1% to 10%.

The average degree of polymerization of acetoacetyl-modified PVA is preferably 1000 to 10000, and preferably 1200 to 5000. The saponification degree of acetoacetyl-modified PVA is preferably 97 mol% or more. The pH of the 4% by weight aqueous solution of acetoacetyl-modified PVA is preferably 3.5 to 5.5. In addition, the average degree of polymerization and saponification degree can be determined in accordance with JIS K 6726-1994.

Any suitable polyolefin-based resin may be used as the polyolefin-based component. Examples of the olefin component which is a main component of the polyolefin-based resin include olefin hydrocarbons having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene. These can be used alone or in combination of two or more. Among these, olefinic hydrocarbons having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene, and 1-butene are preferable, and ethylene is more preferably used.

The proportion occupied by the olefin component among the monomer components constituting the polyolefin-based resin is preferably 50% by weight to 95% by weight.

It is preferable that the said polyolefin resin has a carboxyl group and/or its anhydride group. Such a polyolefin-based resin can be dispersed in water, so that the underlying layer can be formed satisfactorily. As a monomer component which has such a functional group, unsaturated carboxylic acid and its anhydride, half ester of unsaturated dicarboxylic acid, and half amide are mentioned, for example. Specific examples of these include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, and crotonic acid.

The molecular weight of the polyolefin-based resin is, for example, 5000 to 80000.

In the composition for forming the undercoating layer, the blending ratio (solid content) of the polyvinyl alcohol-based component and the polyolefin-based component is preferably 5:95 to 60:40, more preferably 20:80 to 50:50. When there are too many polyvinyl alcohol-based components, there exists a possibility that adhesiveness may not be fully acquired. Specifically, there is a fear that the peeling force required when peeling the PVA-based resin layer from the resin substrate is lowered, and sufficient adhesiveness may not be obtained. On the other hand, if the polyvinyl alcohol-based component is too small, there is a fear that the appearance of the resulting laminate may be damaged. Specifically, there is a concern that a problem such as clouding of the coating film occurs when forming the undercoating layer to be described later, making it difficult to obtain a laminate having excellent appearance.

The composition for forming the undercoating layer is preferably aqueous. The base layer forming composition may contain an organic solvent. As an organic solvent, ethanol, isopropanol, etc. are mentioned, for example. The solid content concentration of the composition for forming the undercoating layer is preferably 1.0% by weight to 10% by weight.

You may mix|blend an additive with the composition for base layer formation. As an additive, a crosslinking agent etc. are mentioned, for example. Examples of the crosslinking agent include methylol compounds such as oxazoline, boric acid, and trimethylolmelamine, carbodiimides, isocyanate compounds, and epoxy compounds. The blending amount of the additive in the composition for forming the undercoating layer can be appropriately set depending on the purpose and the like. For example, the blending amount of the crosslinking agent is preferably 10 parts by weight or less, more preferably 0.01 parts by weight to 10 parts by weight, and more preferably, 100 parts by weight of the total amount of the polyvinyl alcohol-based component and the polyolefin-based component. 0.1 to 5 parts by weight.

Any suitable method can be adopted as a method for applying the composition for forming the undercoating layer. For example, roll coat method, spin coat method, wire bar coat method, dip coat method, die coat method, curtain coat method, spray coat method, knife coat method (comma coat method, etc.) can be mentioned.

The composition for forming the undercoating layer is preferably applied so that the resulting undercoating layer has a thickness of 500 nm to 3000 nm, and more preferably 800 nm to 2000 nm. If the thickness of the undercoat layer is too thin, there is a fear that sufficient adhesiveness cannot be obtained. On the other hand, if the thickness of the undercoat layer is too thick, problems such as cratering or non-uniformity in the resulting coating film may occur during formation of the PVA-based resin coating layer, which will be described later, to obtain a laminate having excellent appearance. There is a risk of difficulty.

After application of the composition for forming the undercoating layer, the coating film may be dried. Drying temperature is 50 degreeC or more, for example.

B-2. Formation of PVA-based resin coating layer

The surface of the undercoating layer to which the coating liquid containing the PVA-based resin is applied may be subjected to surface modification treatment (for example, corona treatment) in advance. According to such a process, adhesiveness can be improved further.

As a coating liquid containing the PVA-based resin, a solution in which the PVA-based resin is dissolved in a solvent is typically used. Examples of the solvent include polyhydric alcohols such as water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, and trimethylolpropane, ethylenediamine, diethylenetriamine, and the like. And amines. These can be used alone or in combination of two or more. Among these, water is preferable. The PVA-based resin concentration of the coating liquid is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. If it is such resin concentration, a uniform coating film can be formed.

You may mix|blend an additive with a coating liquid. As an additive, a plasticizer, surfactant, etc. are mentioned, for example. As a plasticizer, polyhydric alcohols, such as ethylene glycol and glycerin, are mentioned, for example. As a surfactant, nonionic surfactant is mentioned, for example. These can be used for the purpose of further improving the uniformity, dyeability, and stretchability of the resulting PVA-based resin layer. Moreover, as an additive, the component easily adhered is mentioned, for example. Adhesiveness can be further improved by using an easily-adhesive component. As an easily-adhesive component, modified PVA, such as acetoacetyl-modified PVA, is used, for example.

As the coating method of the coating liquid, the same method as the coating method of the composition for forming the undercoating layer may be employed. After application, the coating film can be dried. Drying temperature is 50 degreeC or more, for example.

B-3. Preparation of polarizing film

As described above, the laminate may be subjected to various treatments. Specific examples of various treatments include dyeing treatment, stretching treatment, insolubilization treatment, crosslinking treatment, washing treatment, and drying treatment. These treatments can be appropriately selected according to the purpose. Further, the processing order, timing of processing, and the number of processing can be appropriately set. Hereinafter, each process will be described.

(Dyeing treatment)

The dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic material. Preferably, it is carried out by adsorbing a dichroic substance to the PVA-based resin layer. As the adsorption method, for example, a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing a dichroic substance, a method of applying the dyeing solution to the PVA-based resin layer, and the dyeing solution of PVA And a method of spraying the system resin layer. Preferably, it is a method of immersing a PVA system resin layer in a dyeing solution. This is because the dichroic substance can be adsorbed satisfactorily.

Examples of the dichroic substance include iodine and organic dyes. These can be used alone or in combination of two or more. The dichroic substance is preferably iodine. When iodine is used as a dichroic substance, the dyeing solution is preferably an aqueous solution of iodine. The blending amount of iodine is preferably 0.1 parts by weight to 0.5 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to blend iodide with an aqueous solution of iodine. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Among these, it is preferably potassium iodide. The blending amount of iodide is preferably 0.02 parts by weight to 20 parts by weight, more preferably 0.1 part by weight to 10 parts by weight with respect to 100 parts by weight of water.

The liquid temperature during dyeing of the dyeing solution is preferably 20°C to 50°C in order to suppress the dissolution of the PVA-based resin. When the PVA-based resin layer is immersed in the dyeing solution, the immersion time is preferably 5 seconds to 5 minutes in order to ensure the transmittance of the PVA-based resin layer. In addition, the dyeing conditions (concentration, liquid temperature, immersion time) can be set such that the polarization degree or simple substance transmittance of the finally obtained polarizing film is within a predetermined range. In one embodiment, the immersion time is set so that the polarization degree of the obtained polarizing film is 99.98% or more. In another embodiment, the immersion time is set such that the single transmittance of the obtained polarizing film is 40% to 44%.

(Stretch processing)

Any suitable method can be adopted as the stretching method of the laminate. Specifically, fixed-end stretching (for example, a method using a tenter stretching machine) may be used, or free-end stretching (for example, a method of uniaxial stretching by passing a laminate between rolls having different peripheral speeds). Further, simultaneous biaxial stretching (for example, a method using a simultaneous biaxial stretching machine) may be used, or sequential biaxial stretching may be used. The stretching of the laminate may be performed in one step or in multiple steps. When carried out in multiple steps, the draw ratio (maximum draw ratio) of the laminate to be described later is a product of the draw ratio of each step.

The stretching treatment may be an underwater stretching method performed by immersing the laminate in an stretching bath, or may be an aerial stretching method. In one embodiment, the underwater stretching treatment is performed at least once, and the underwater stretching treatment and the aerial stretching treatment are preferably combined. According to the underwater stretching, the resin substrate or the PVA-based resin layer can be stretched at a temperature lower than the glass transition temperature (typically, about 80° C.), and the PVA-based resin layer can be stretched at a high magnification while suppressing its crystallization. Can. As a result, a polarizing film having excellent polarizing properties can be produced.

Any appropriate direction can be selected as the stretching direction of the laminate. In one embodiment, it extends in the longitudinal direction of the elongate laminate. Specifically, the laminate is transported in the longitudinal direction, and is the transport direction (MD). In another embodiment, it extends in the width direction of the elongate laminate. Specifically, the laminate is transported in the longitudinal direction, and is a direction (TD) perpendicular to the transport direction (MD).

The stretching temperature of the laminate can be set to any appropriate value depending on the forming material of the resin substrate, the stretching method, and the like. In the case of employing the aerial stretching method, the stretching temperature is preferably at least the glass transition temperature (Tg) of the resin substrate, more preferably at least 10°C, and more preferably of the resin substrate glass transition temperature (Tg) + 10°C. +15°C or higher. On the other hand, the stretching temperature of the laminate is preferably 170° C. or less. By stretching at such a temperature, the crystallization of the PVA-based resin rapidly progresses, and a problem caused by the crystallization (for example, the orientation of the PVA-based resin layer by stretching is prevented) can be suppressed.

When the underwater stretching method is employed as the stretching method, the liquid temperature of the stretching bath is preferably 40°C to 85°C, more preferably 50°C to 85°C. At such a temperature, it is possible to stretch at a high magnification while suppressing dissolution of the PVA-based resin layer. Specifically, as described above, the glass transition temperature (Tg) of the resin substrate is preferably 60° C. or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is less than 40°C, even if plasticization of the resin substrate with water is taken into consideration, there is a fear that the stretching cannot be satisfactorily. On the other hand, the higher the temperature of the stretching bath becomes, the higher the solubility of the PVA-based resin layer becomes, and there is a fear that excellent polarization properties may not be obtained.

In the case of employing an underwater stretching method, it is preferable that the laminate is immersed in an aqueous boric acid solution to be stretched (boric acid underwater stretching). By using an aqueous solution of boric acid as the stretching bath, the PVA-based resin layer can be provided with rigidity to withstand the tension applied during stretching and water resistance that is not soluble in water. Specifically, boric acid can be crosslinked by hydrogen bonding with a PVA-based resin by generating tetrahydroxyboric acid anion in an aqueous solution. As a result, the PVA-based resin layer is imparted with stiffness and water resistance, can be stretched satisfactorily, and a polarizing film having excellent polarization properties can be produced.

The aqueous boric acid solution is preferably obtained by dissolving boric acid and/or borate in water as a solvent. The concentration of boric acid is preferably 1 part by weight to 10 parts by weight with respect to 100 parts by weight of water. When the boric acid concentration is 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film having higher characteristics can be produced. Further, in addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde or the like in a solvent can also be used.

Preferably, iodide is blended in the stretching bath (aqueous solution of boric acid). By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. Specific examples of the iodide are as described above. The concentration of iodide is preferably 0.05 parts by weight to 15 parts by weight, more preferably 0.5 parts by weight to 8 parts by weight with respect to 100 parts by weight of water.

The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes. Preferably, the underwater stretching treatment is performed after the dyeing treatment.

The draw ratio (maximum draw ratio) of the laminate is preferably 4.0 times or more, more preferably 5.0 times or more with respect to the original length of the laminate. Such a high draw ratio can be achieved, for example, by employing an underwater stretching method (boric acid underwater stretching). In addition, in this specification, the "maximum draw ratio" refers to the draw ratio just before the laminate is broken, and separately refers to a draw ratio at which the laminate is broken, and refers to a value lower than 0.2.

(Insolubilization treatment)

The insolubilization treatment is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. In particular, when the underwater stretching method is employed, water resistance can be imparted to the PVA-based resin layer by performing an insolubilization treatment. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (aqueous solution of boric acid) is preferably 20°C to 40°C. Preferably, the insolubilization treatment is performed after production of the laminate, before dyeing treatment or underwater stretching treatment.

(Crosslinking)

The crosslinking treatment is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. Water resistance can be provided to a PVA system resin layer by performing a crosslinking process. The concentration of the aqueous boric acid solution is preferably 1 part by weight to 4 parts by weight with respect to 100 parts by weight of water. Moreover, when performing a crosslinking process after the said dyeing process, it is preferable to mix|blend an iodide further. By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (aqueous solution of boric acid) is preferably 20°C to 50°C. Preferably, the crosslinking treatment is performed before the underwater stretching treatment. In a preferred embodiment, dyeing treatment, crosslinking treatment, and underwater stretching treatment are performed in this order.

(Cleaning processing)

The washing treatment is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

(Dry treatment)

The drying temperature in the drying treatment is preferably 30°C to 100°C.

B-4. Etc

The said polarizing plate may have the protective film arrange|positioned on the opposite side to the side in which the resin base material of a polarizing film is arrange|positioned. As a material for forming a protective film, for example, (meth)acrylic resin, diacetyl cellulose, triacetyl cellulose and other cellulose-based resins, cycloolefin-based resins, polypropylene-based olefin-based resins, polyethylene terephthalate-based resins, etc. And ester-based resins, polyamide-based resins, polycarbonate-based resins, and copolymer resins thereof. The thickness of the protective film is preferably 10 μm to 100 μm. The protective film may be laminated on the polarizing film via an adhesive layer, or may be laminated in close contact (without an adhesive layer). The adhesive layer is typically formed of an adhesive or an adhesive.

The polarizing plate can be mounted on, for example, a liquid crystal display device. In this case, it is preferable that the polarizing film is mounted on the liquid crystal cell side rather than the resin substrate. According to such a structure, the influence of the phase difference which a resin base material can have on the image characteristic of the obtained liquid crystal display device can be excluded.

Example

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited by these examples. In addition, the measuring method of thickness is as follows. In addition, "parts" and "%" in Examples and Comparative Examples below represent "parts by weight" and "% by weight", respectively.

(thickness)

It measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C").

[Example 1]

As a resin base material, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 µm) having a long shape, an absorption rate of 0.75%, and a Tg of 75°C was used.

Corona treatment is performed on one side of the resin substrate, and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industries, trade name "Kosefimer Z200", polymerization degree 1200, saponification degree 99.0 mol% or more, acetoacetyl modification degree 4.6) %) aqueous solution of a 4.0% aqueous solution and a modified polyolefin resin aqueous dispersion (manufactured by UNITICA, trade name "Arowbase SE1030N", solid content concentration 22%) and a mixture solution of pure water (solid content concentration 4.0%) after drying to a thickness of 2000 nm. It was applied as much as possible and dried at 60°C for 3 minutes to form a primer layer. Here, the mixing ratio of the solid content of acetoacetyl-modified PVA and the modified polyolefin in the mixed solution was 30:70.

Subsequently, a corona treatment was performed on the surface of the undercoating layer, and the polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl denaturation 4.6%, saponification degree 99.0 mol were applied to the corona-treated surface. % Or more, and an aqueous solution containing Nippon Synthetic Chemical Industry Co., Ltd. product name "Kosefimer Z200") in a ratio of 9:1 was applied and dried at 25°C to form a PVA-based resin layer having a thickness of 11 µm. In this way, a laminate was prepared.

The obtained laminate was uniaxially stretched free end 2.0 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 120°C (air assisted stretching).

Subsequently, the layered product was immersed in an insolubilization bath at a liquid temperature of 30°C (an aqueous solution of boric acid obtained by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).

Subsequently, it was immersed in a dyeing bath at a liquid temperature of 30°C while adjusting the iodine concentration and immersion time so that the obtained polarizing plate had a predetermined transmittance. In this example, 0.2 part by weight of iodine was blended with respect to 100 parts by weight of water, and 1.0% by weight of potassium iodide was blended to iodine aqueous solution obtained for 60 seconds (staining treatment).

Subsequently, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 30° C. (an aqueous solution of boric acid obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) (crosslinking treatment).

Thereafter, the layered product was immersed in a boric acid aqueous solution at a liquid temperature of 70°C (an aqueous solution obtained by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water and 5 parts by weight of potassium iodide), while being intercalated between rolls having different circumferences Uniaxial stretching was performed in the direction (longitudinal direction) so that the total draw ratio was 5.5 times (underwater stretching).

Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 30°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) (washing treatment).

In this way, a laminate (polarizing plate) having a polarizing film having a thickness of 5 μm formed on one side of a resin substrate having a thickness of 30 μm was obtained.

[Example 2]

A polarizing plate was obtained in the same manner as in Example 1, except that the mixed solution was applied so that the thickness after drying was 1000 nm.

[Example 3]

A polarizing plate was obtained in the same manner as in Example 1 except that the mixed solution was applied so that the thickness after drying was 500 nm.

[Example 4]

A polarizing plate was obtained in the same manner as in Example 1 except that the mixing ratio of the solid content of acetoacetyl-modified PVA and the modified polyolefin in the mixed solution was 50:50.

[Example 5]

A mixed solution of a 4.0% aqueous solution of acetoacetyl-modified PVA (Kosefimer Z200) and an aqueous dispersion of a modified polyolefin resin (trade name "Arrow Base SD1030N", solid content concentration 22%) and pure water at the time of formation of the undercoat layer. A polarizing plate was obtained in the same manner as in Example 1 except that (solid content concentration 4.0%) was used.

[Example 6]

A mixed solution of a 4.0% aqueous solution of acetoacetyl-modified PVA (Kosefimer Z200) and an aqueous dispersion of a modified polyolefin resin (Unityka, trade name "Arrowbase SE1035NJ2", solid content concentration 22%) at the time of formation of the undercoat layer and pure water The polarizing plate was obtained like Example 4 except having used (solid content concentration 4.0%).

[Example 7]

At the time of formation of the undercoat layer, a 4.0% aqueous solution and a modified polyolefin resin of acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industries, trade name "Kosefimer Z410", polymerization degree 2200, saponification degree 97.5-98.5%, acetoacetyl modification degree 4.6%) A polarizing plate was obtained in the same manner as in Example 1 except that a mixed solution (solid content concentration: 4.0%) was mixed with an aqueous dispersion (manufactured by Unitica Co., Ltd., trade name "arrow base SE1030N", solid content concentration: 22%).

[Example 8]

A polarizing plate having a thickness of 6 µm and a polarizing film having a thickness of 6 µm on one side of a resin substrate having a thickness of 37 µm was obtained in the same manner as in Example 1, except that the stretching ratio of aerial assisted stretching was 4.0 times, and insoluble treatment and underwater stretching were not performed. .

[Comparative Example 1]

A polarizing plate was obtained in the same manner as in Example 1, except that the PVA-based resin coating layer was directly formed on the resin substrate without forming a primer layer.

[Comparative Example 2]

A polarizing plate was obtained in the same manner as in Example 8, except that the PVA-based resin coating layer was directly formed on the resin substrate without forming a primer layer.

[Comparative Example 3]

A polarizing plate was obtained in the same manner as in Example 3 except that a 4.0% aqueous solution of acetoacetyl-modified PVA (Gosefimer Z200) was used in forming the undercoat layer.

[Comparative Example 4]

A polarizing plate was obtained in the same manner as in Example 2 except that a 4.0% aqueous solution of acetoacetyl-modified PVA (Gosefimer Z200) was used in forming the undercoat layer.

[Comparative Example 5]

A polarizing plate was obtained in the same manner as in Example 1 except that a 4.0% aqueous solution of acetoacetyl-modified PVA (Gosefimer Z200) was used in forming the undercoat layer.

[Comparative Example 6]

A polarizing plate was prepared in the same manner as in Example 8, except that a 4.0% aqueous solution of acetoacetyl-modified PVA (Kosefimer Z200) was used to form the undercoating layer, and this mixture was applied so that the thickness after drying was 1000 nm. Got.

[Comparative Example 7]

A polarizing plate was obtained in the same manner as in Example 3 except that a polyester aqueous emulsion resin (manufactured by UNITICA, trade name "Eritel KT0507E6") was used in forming the undercoat layer.

[Comparative Example 8]

A polarizing plate was obtained in the same manner as in Example 2, except that a polyester aqueous emulsion resin (manufactured by UNITICA, trade name "Eritel KT0507E6") was used in forming the undercoat layer.

[Comparative Example 9]

A polarizing plate was obtained in the same manner as in Example 2 except that a modified polyolefin resin aqueous dispersion (arrow base SB1035NJ2) was used in forming the undercoat layer.

[Comparative Example 10]

The same procedure as in Example 3 was performed except that a mixed solution of 10 g of a 4.0% aqueous solution of acetoacetyl-modified PVA (Kosefimer Z200) and 62.5 g of a polyester aqueous emulsion resin (Eritel KT0507E6) was used at the time of formation of the undercoat layer. , To obtain a polarizing plate. Here, the mixing ratio of the solid content of acetoacetyl-modified PVA and polyester in the mixed solution was 50:50.

[Comparative Example 11]

The same procedure as in Example 1 was performed except that a mixed solution of 10 g of a 4.0% aqueous solution of acetoacetyl-modified PVA (Kosefimer Z200) and 62.5 g of a polyester aqueous emulsion resin (Eritel KT0507E6) was used at the time of formation of the undercoat layer. , To obtain a polarizing plate. Here, the mixing ratio of the solid content of acetoacetyl-modified PVA and polyester in the mixed solution was 50:50.

(evaluation)

The following evaluation was performed about the said Example and the comparative example. Table 1 summarizes the evaluation results. In addition, the results of SEM observation (6500 times) of the cross-section of the laminate after stretching in Example 1, Example 2, Example 8, Comparative Example 1 and Comparative Example 11 are shown in FIG. 1.

1. Adhesion

Adhesiveness was evaluated by measuring the PVA peeling force and the base peeling force. The measuring method of PVA peeling force and base peeling force is as follows.

(PVA peeling force)

The polarizing plate obtained on the glass plate was applied and adhered to the resin substrate surface side, and a polyimide tape (manufactured by Nitto Electric Industries Co., Ltd., polyimide adhesive tape No.360A) was attached to the polarizing film surface to prepare a measurement sample. Did. A notch was formed with a cutter knife between the polarizing film of the sample for measurement and the resin substrate, and the polarizing film and the polyimide tape for reinforcement were raised to form an angle of 90° with respect to the resin substrate surface, and the peeling rate was 3000 mm/min. The force (N/15 mm) required for peeling was measured by an angle material type adhesive/film peeling analysis device “VPA-2” (manufactured by Kyowa Interface Chemical Co., Ltd.).

(Base peeling force)

The polarizing plate obtained on the glass plate was apply|coated and stuck to the polarizing film surface side, and the sample for measurement was produced. The force required to form a notch with a cutter knife between the polarizing film of the sample for measurement and the resin substrate, to stand the resin substrate to form an angle of 90° with respect to the polarizing film surface, and to peel at a peel rate of 3000 mm/min (N/15 mm) was measured by "VPA-2" above.

2. Appearance

When the formation of the undercoat layer and the application of the polyvinyl alcohol solution were performed, the appearance of the coating film was visually observed.

As shown in Table 1, the layered product of the Examples has excellent adhesion and appearance. Sufficient adhesiveness is maintained even when extending underwater. On the other hand, in Comparative Examples 1 and 2 in which the undercoat layer was not formed, sufficient adhesion was not obtained. In Comparative Examples 3 to 6 in which an undercoat layer was formed without using a polyolefin-based component, sufficient adhesion was not obtained, and the thicker the undercoat layer, the more cratering occurred during the formation of the undercoat layer (when applied), and the cratering generation part. It becomes air bubbles, and the appearance deteriorates. In Comparative Examples 7 to 9 in which an undercoat layer was formed without using a polyvinyl alcohol-based component, the coating film became cloudy when the undercoat layer was formed, and excellent appearance was not obtained. In Comparative Examples 10 and 11 in which an undercoat layer was formed using a polyvinyl alcohol-based component and a polyester-based component, aggregates (odoltodol) were formed in the undercoat layer, and excellent appearance was not obtained.

Industrial availability

The laminate of the present invention is preferably used, for example, in an image display device. Specifically, it is preferable as a liquid crystal panel such as a liquid crystal television, a liquid crystal display, a mobile phone, a digital camera, a video camera, a portable game machine, a car navigation system, a copy machine, a printer, a fax machine, a clock, a microwave oven, an antireflection plate of an organic EL device, and the like. Is used.

Claims (16)

It has a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate,
The laminate in which the resin substrate side of the polyvinyl alcohol-based resin layer is an intermediate region containing a polyvinyl alcohol-based component and a polyolefin-based component and not containing a crosslinking agent. delete According to claim 1,
The laminate, wherein the polyvinyl alcohol-based component contains acetoacetyl-modified polyvinyl alcohol. The method according to claim 1 or 3,
The laminate having a solids weight ratio of the polyvinyl alcohol-based component to the polyolefin-based component is 5:95 to 60:40. The method according to claim 1 or 3,
The laminated body having the thickness of the intermediate region is 100 nm to 1000 nm. A step of forming a base layer by applying a composition for forming a base layer containing a polyvinyl alcohol-based component and a polyolefin-based component on one side of the resin substrate, and not containing a crosslinking agent;
And a step of forming a polyvinyl alcohol-based resin coating layer by applying a coating liquid containing a polyvinyl alcohol-based resin on the surface of the undercoating layer. delete The method of claim 6,
The said polyvinyl alcohol-type component contains acetoacetyl-modified polyvinyl alcohol, The manufacturing method of a laminated body. The method of claim 6,
The weight ratio of the solid content of the said polyvinyl alcohol-based component and the said polyolefin-based component is 5:95-60:40, The manufacturing method of a laminated body. The method of claim 6,
The thickness of the said undercoat layer is 500 nm-3000 nm, The manufacturing method of a laminated body. The manufacturing method of a polarizing plate including the process of extending|stretching and dyeing the laminated body obtained by the manufacturing method of the laminated body in any one of Claims 6 and 8-10. It has a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate,
The resin substrate side of the polyvinyl alcohol-based resin layer is an intermediate region containing a polyvinyl alcohol-based component and a polyolefin-based component and not containing a crosslinking agent,
The polarizing plate, wherein the polyvinyl alcohol-based resin layer is a polarizing film in which a dichroic substance is adsorbed and oriented. delete The method of claim 12,
The polarizing plate, wherein the polyvinyl alcohol-based component includes acetoacetyl-modified polyvinyl alcohol. The method of claim 12 or 14,
The polarizing plate whose solid content weight ratio of the said polyvinyl alcohol-type component and the said polyolefin component is 5:95-60:40. The method of claim 12 or 14,
A polarizing plate having a thickness of the intermediate region of 100 nm to 1000 nm.

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