TW201902713A - Method for manufacturing laminated body, laminated body, polarizing plate and manufacturing method of polarizing plate - Google Patents

Abstract

Provided is a laminate which exhibits excellent adhesion between a polyester resin substrate and a polyvinyl alcohol resin layer. This laminate comprises: a polyester resin substrate, on the surface of which a highly adhesive layer is formed; and a polyvinyl alcohol resin layer which is laminated on the polyester resin substrate with the highly adhesive layer being interposed therebetween. The contact angle with water of the highly adhesive layer is 70 DEG or more immediately after water is dropped thereon, and decreases by 2 DEG or more when 30 seconds have elapsed from the dropping.

Description

Laminated body, manufacturing method of laminated body, polarizing plate and manufacturing method of polarizing plate

The present invention relates to a laminated body, a method for manufacturing the laminated body, a polarizing plate, and a method for manufacturing a polarizing plate.

BACKGROUND OF THE INVENTION A method is proposed in the literature to form a polarizer by forming a polyvinyl alcohol resin layer on a polyester resin substrate and extending and dyeing the laminate (for example, Patent Document 1). The manufacturing method of the said polarizer is attracting attention, for example, it is considered that it can contribute to thickness reduction of an image display device.

The above-mentioned polyester-based resin substrate can be used as a protective layer of a polarizer without peeling off. This makes it possible to directly use a laminated body of a polyester resin substrate and a polarizer as a polarizer instead of attaching a protective film to a polarizer, for example, it can contribute to cost reduction of an image display device.

Prior Art Literature Patent Literature Patent Literature 1: Japanese Patent Laid-Open No. 2000-338329

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, the laminated body of a polyester resin substrate and a polarizer obtained by the method described above, that is, a polarizing plate, has the adhesion of the polyester resin substrate and the polarizer. Inadequacy.

The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a laminated body having excellent adhesion between a polyester resin substrate and a polyvinyl alcohol resin layer, a method for producing the laminated body, A polarizing plate having excellent adhesion between an ester-based resin substrate and a polarizer, and a method for manufacturing the polarizing plate.

Means for Solving the Problems The laminated body of the present invention includes a polyester resin substrate having an easy-adhesive layer formed on the surface thereof, and a polyvinyl alcohol resin layer which is laminated on the polyester resin substrate through the easy-adhesion layer. ; The water contact angle of the easy-adhesive layer is 70 ° or more when the water droplets are immediately dropped onto the easy-adhesive layer, and 30 seconds after the dropping, the angle decreases by more than 2 °. In one embodiment, the easy-adhesion layer contains a polyvinyl alcohol-based component and a polyolefin-based component. In one embodiment, a blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component is 10:90 to 50:50. According to another aspect of the present invention, a method for manufacturing a laminated body can be provided. The method for manufacturing the laminated body includes the following steps: forming an easy-adhesive layer on the surface of the polyester-based resin substrate; and forming a polyvinyl alcohol-based resin layer on the surface of the easy-adhesive layer; When the water drops reach the above-mentioned easy-adhesive layer, it is 70 ° or more, and after 30 seconds from the dropping, the water level decreases by 2 ° or more. According to another aspect of the present invention, a method for manufacturing a polarizing plate is provided. The manufacturing method of the polarizing plate includes the following steps: dyeing and stretching the laminated body, thereby making the polyvinyl alcohol-based resin layer into a polarizer. According to another aspect of the present invention, a polarizing plate can be provided. The polarizing plate has: a polyester resin substrate having an easy-adhesion layer formed on the surface; and a polarizer, laminated on the polyester resin substrate through the easy-adhesion layer; the thickness of the polarizer is 10 μm or less; The water contact angle of the subsequent layer is more than 70 ° immediately after the water droplets are dropped onto the easy-adhesion layer, and after 30 seconds from the dropping, the contact angle decreases by more than 2 °.

Advantageous Effects of Invention According to the present invention, by using a water contact angle of 70 ° or more when the water is just dropped, and an easy-adhesion layer that is reduced by 2 ° or more after 30 seconds after dropping, a polyester-based resin substrate and polyethylene can be provided. A laminated body having excellent adhesion of an alcohol-based resin layer, a method for producing the laminated body, and a polarizing plate having excellent adhesion between a polyester-based resin substrate and a polarizer.

Embodiments for Implementing the Invention Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

A. Laminated Body FIG. 1 is a schematic cross-sectional view of a laminated body according to an embodiment of the present invention. The laminated body 100 includes: a polyester-based resin substrate 10 having an easy-adhesion layer 20 formed on the surface; and a polyvinyl alcohol (PVA) -based resin layer 30 which is laminated on the polyester-based resin substrate 10 through the easy-adhesion layer 20. The water contact angle of the easy-adhesive layer 20 is more than 70 ° immediately after the water droplets are dropped on the easy-adhesive layer 20, and it will decrease by more than 2 ° after 30 seconds after dropping. The historical change (decrease) of the water contact angle can be represented by measuring the water contact angle (θ1) immediately after the water droplet is dropped onto the easy-adhesive layer, and the water contact angle (θ2) after 30 seconds from the drop. It is calculated by subtracting θ1 from θ2. The water contact angle immediately after the water droplets reached the easy-to-adhesive layer is the water contact angle measured after 1 second after the representative system was dropped. In one embodiment, the easy-adhesion layer 20 contains a polyvinyl alcohol-based component and a polyolefin-based component. At this time, the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component is preferably 10:90 to 50:50. Thereby, a laminated body having excellent adhesion between the polyester-based resin substrate and the PVA-based resin layer can be obtained. In one embodiment, the laminated body can be used for manufacturing a polarizing plate. The manufacturing method of the polarizing plate is as described later in item D, and includes the following steps: dyeing and extending the laminated body, thereby making the PVA-based resin layer into a polarizer.

A-1. Polyester-based resin substrate The forming material of polyester-based resin substrate can be used, for example: polyethylene terephthalate (PET), polybutylene terephthalate (PBT), Polyethylene naphthalate (PEN), isophthalic acid, copolymerized PET (PET-G) containing alicyclic dicarboxylic acids or alicyclic diols containing cyclohexane rings, and other polyesters, As well as such copolymers and blends. Among them, it is preferable to use amorphous (uncrystallized) PET or copolymerized PET. These resins are amorphous in an unstretched state and have excellent elongation properties suitable for high-rate elongation, and are crystallized by elongation and heating to impart heat resistance and dimensional stability. In addition, it is possible to ensure the heat resistance to a practical degree when the PVA-based resin is applied and dried in an unstretched state.

The glass transition temperature (Tg) of the polyester resin substrate is preferably 170 ° C or lower. By using such a polyester-based resin substrate, it is possible to suppress the crystallization of the PVA-based resin layer while ensuring sufficient extensibility. Considering the viewpoints of plasticizing the polyester-based resin substrate with water and smoothly performing water-extension, the temperature is more preferably 120 ° C or lower. In one embodiment, the glass transition temperature of the polyester-based resin substrate is preferably 60 ° C or higher. By using the polyester-based resin substrate, it is possible to prevent deformation of the polyester-based resin substrate (for example, occurrence of unevenness, sag, or wrinkle) when applying and drying a coating solution containing a PVA-based resin described later. And so on. In addition, the laminated body can be stretched well at an appropriate temperature (for example, about 60 ° C to 70 ° C). In another embodiment, when the coating liquid containing the PVA-based resin is applied and dried, as long as the polyester-based resin substrate is not deformed, the glass transition temperature may be lower than 60 ° C. The glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121.

In one embodiment, the water absorption of the polyester resin substrate is preferably 0.2% or more, and more preferably 0.3% or more. This type of polyester-based resin substrate absorbs water, and water can function as a plasticizer to plasticize. As a result, the elongation stress can be greatly reduced during the elongation in water, and excellent extensibility is obtained. On the other hand, the water absorption of the polyester-based resin substrate is preferably 3.0% or less, and more preferably 1.0% or less. By using such a polyester-based resin base material, it is possible to prevent problems such as a significant decrease in the dimensional stability of the polyester-based resin base material during production and deterioration of the appearance of the obtained laminated body. It can also prevent breakage when stretching in water, or peeling of the PVA-based resin layer from the polyester-based resin substrate. The water absorption is a value obtained in accordance with JIS K 7209.

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

The surface of the polyester-based resin substrate may be subjected to surface modification treatment (such as corona treatment) in advance. Through these processes, the adhesion can be further improved.

A-2. Easy-adhesive layer As described above, the water contact angle of the easy-adhesive layer is 70 ° or more immediately after the water droplet is dropped, and it decreases by 2 ° or more after 30 seconds after dropping. When the water drops are just dropped, the water contact angle of the easy-adhesive layer should be 75 ° ~ 85 °. The diachronic change in the contact angle of water generated after 30 seconds from the dropping should be -2 ° (reduction of 2 °) to -5 ° (reduction of 5 °). The water contact angle of the easy-adhesive layer immediately after the water was dropped was 70 ° or more, and the diachronic change (decrease) of the water contact angle generated 30 seconds after the drop was 2 ° or more, thereby forming the easy-adhesive layer with In the case of the PVA-based resin layer, the composition for forming an easy-adhesive layer is allowed to elute to the PVA-based resin layer. Specifically, by changing the duration of the water contact angle to -2 ° to -5 °, when a coating layer of a PVA-based resin is formed on the easy-adhesive layer, 10% by volume of the composition for easy-adhesive layer formation can be made. ~ 34 vol% can be eluted into the coating layer of PVA resin. This can improve the adhesion between the polyester-based resin substrate and the PVA-based resin layer.

The easily-adhesive layer may be a layer that is formed only of a composition for easily-adhesive layer formation described later, or may be a layer formed by mixing (including compatibility) the composition for easily-adhesion layer formation and a PVA-based resin layer described later or region. By forming the easy-adhesion layer, excellent adhesion can be obtained. The thickness of the easy-adhesion layer is preferably 500 nm to 3000 nm, and more preferably 800 nm to 2000 nm. If the thickness of the easy-adhesion layer is too thin, sufficient adhesion may not be obtained. On the other hand, if the thickness of the easy-adhesion layer is too thick, when forming the PVA-based resin coating layer described later, defects such as sags and unevenness of the coating film produced may occur, making it difficult to obtain an appearance. The possibility of an excellent laminated body may be confirmed by observing the cross section of the laminated body with a scanning electron microscope (SEM).

The easy-adhesion layer preferably contains a polyvinyl alcohol-based component and a polyolefin-based component. With this composition, the water contact angle and the water contact angle of the easy-adhesive layer can be changed to an angle within the above-mentioned range. As a result, the polyester resin substrate and the PVA resin layer can be adhered to each other. A laminated body with excellent properties. In addition, by dyeing and stretching the laminated body, a polarizing plate having excellent adhesion between a polyester resin substrate and a polarizer can be obtained. As the polyvinyl alcohol-based component, any appropriate PVA-based resin can be used. Specific examples include polyvinyl alcohol and modified polyvinyl alcohol. The modified polyvinyl alcohol is, for example, a polyvinyl alcohol modified by an acetamidine group, a carboxylic acid group, an acrylamide group, and / or a urethane group. Among these, it is more suitable to use acetamidine to modify PVA. As the acetamidine-modified PVA, a polymer having at least a repeating unit represented by the following general formula (I) is preferably used.

[Chemical Formula 1]

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

The average polymerization degree of acetamidine-modified PVA should be 1000 ~ 10000, more preferably 1200 ~ 5000. The saponification degree of acetamidine-modified PVA should be above 97 mole%. The pH of a 4% by weight aqueous solution of acetamidine-modified PVA should be 3.5 to 5.5. The average degree of polymerization and the degree of saponification can be determined from JIS K 6726-1994.

The polyolefin-based component may be any appropriate polyolefin resin. The main component of the polyolefin-based resin is an olefin component. For example, olefin-based hydrocarbons having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene can be mentioned. These may be used alone or in combination of two or more kinds. Among these, olefin-based hydrocarbons having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene, and 1-butene are preferably used, and ethylene is more suitable.

Among the monomer components constituting the polyolefin-based resin, the proportion of the olefin component is preferably 50% to 95% by weight.

The polyolefin-based resin preferably contains a carboxyl group and / or an acid anhydride group thereof. The polyolefin-based resin can be dispersed in water and can form an easy-adhesion layer smoothly. Examples of the monomer component having the functional group include unsaturated carboxylic acids and their anhydrides, half esters of unsaturated dicarboxylic acids, and hemiamine. Specific examples thereof include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, and crotonic acid.

The molecular weight of the polyolefin resin is, for example, 5,000 to 80,000.

In the easy-adhesion layer, the blending ratio of the polyvinyl alcohol-based component to the polyolefin-based component (the former: the latter (solid content)) is preferably 10: 90-50: 50, and more preferably 20: 80-50: 50. When there are too many polyvinyl alcohol-type components, sufficient adhesiveness may not be obtained. Specifically, when the PVA-based resin layer is peeled from the polyester-based resin substrate, the required peeling force may be reduced, and sufficient adhesion cannot be obtained. On the other hand, if the polyvinyl alcohol-based component is too small, the appearance of the obtained laminated body may be damaged. Specifically, when an easy-to-adhere layer is formed, problems such as white turbidity of the coating film may occur, and it is difficult to obtain a laminated body having excellent appearance.

A-3. PVA-based resin layer As the PVA-based resin forming the PVA-based resin layer, any appropriate resin can be used. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The degree of saponification is determined in accordance with JIS K 6726-1994. By using the PVA-based resin having the saponification degree, a polarizing film having excellent durability can be obtained. When the saponification degree is too high, there is a risk of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10,000, preferably 1200 to 4500, and more preferably 1500 to 4300. 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, and more preferably 10 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.

B. Method for producing a laminated body The laminated body of the present invention can be produced by any appropriate method. In one embodiment, the laminated system is manufactured by a method including the steps of: forming an easy-adhesive layer on the surface of a polyester-based resin substrate; and forming a PVA-based resin layer on the surface of the easy-adhesive layer.

B-1. Formation of easy-adhesive layer Any appropriate method can be adopted as a method of forming an easy-adhesive layer on the surface of the polyester resin substrate. Representatively, an easy-adhesive layer can be formed by applying the composition for forming an easy-adhesive layer to the surface of a polyester resin substrate and drying it. In the composition for forming an easy-to-adhere layer, the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component (the former: the latter (solid content)) is preferably 10:90 to 50:50, and more preferably 20:80 to 50:50.

The composition for forming an easy-adhesive layer is preferably an aqueous system. The composition for easy adhesion layer formation may contain an organic solvent. Examples of the organic solvent include ethanol and isopropanol. The solid content concentration of the composition for forming an easy-adhesive layer is preferably 1.0% by weight to 10% by weight.

Additives may be blended into the composition for forming an easy-to-adhere layer. Examples of the additives include cross-linking agents. Examples of cross-linking agents Hydroxymethyl compounds such as oxazoline, boric acid, and trimethylolmelamine, carbodiimide, isocyanate compounds, epoxy compounds, and the like. The amount of the additive to be added to the composition for easily forming a 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 to 10 parts by weight, and more preferably 100 parts by weight of the polyvinyl alcohol-based component and the polyolefin-based component in total. 0.1 parts by weight to 5 parts by weight.

As a method for applying the composition for forming an easy-to-adhesive layer, any appropriate method can be adopted. Examples include a roll coating method, a spin coating method, a bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a doctor blade coating method (comma coating method, etc.), and the like.

After coating the composition for forming an easy-to-adhere layer, the coating film can be dried. The drying temperature is, for example, 50 ° C or higher.

B-2. Forming a PVA-based resin layer The method of forming a PVA-based resin layer on the surface of the easy-adhesive layer may be any appropriate method. It is preferable to form a PVA-based resin layer by applying a coating liquid containing a PVA-based resin to the surface of an easy-adhesive layer formed on a polyester-based resin substrate and drying it.

The coating solution containing a PVA-based resin represents a system in which the above-mentioned PVA-based resin is dissolved in a solvent. Examples of the solvent include water, dimethylmethylene, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, and polyhydric alcohols such as trimethylolpropane. Amines such as ethylenediamine and diethylene glycol. These may be used alone or in combination of two or more kinds. Of these, water is preferred. The concentration of the PVA-based resin in the coating liquid is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. As long as it is the resin concentration, a uniform coating film can be formed.

Additives can also be blended in the coating solution. Examples of the additives include plasticizers and surfactants. Examples of the plasticizer include a polyhydric alcohol such as ethylene glycol or glycerin. The surfactant may be, for example, a nonionic surfactant. These can be used in order to further improve the uniformity, dyeability, and elongation of the obtained PVA-based resin layer. In addition, the additives may be easily accessible ingredients. By using the easy-contact component, the adhesion between the polyester-based resin substrate and the PVA-based resin layer can be improved. As a result, defects such as peeling of the PVA-based resin layer from the polyester-based substrate can be suppressed, and dyeing and water elongation described later can be performed favorably. Modified PVA such as acetoacetate-based modified PVA can be used as the easy-to-connect component.

As a coating method of a coating liquid, the same method as the coating method of the composition for forming an easy-adhesion layer mentioned above can be employ | adopted. After coating, the coating film can be dried. The drying temperature at this time is preferably above 50 ° C.

Prior to forming the PVA-based resin layer, a surface treatment (for example, a corona treatment) may be performed on the easy-adhesive layer. By performing the treatment, the adhesion between the polyester-based resin substrate and the PVA-based resin layer can be improved.

C. Polarizing plate The polarizing plate of the present invention includes a polyester-based resin substrate having an easily-adhesive layer formed on the surface, and a polarizer laminated on the polyester-based resin substrate through the easily-adhesive layer. The thickness of the polarizing film is 10 μm or less. The easy-adhesive layer is as described in the above item A-2, and the method for forming the easy-adhesive layer is as described in the above item B-1. Thereby, a polarizing plate having excellent adhesion between the polyester resin substrate and the polarizer can be obtained. The polarizing plate may have a protective film on the side of the polarizer opposite to the easy-adhesive layer.

C-1. Polarizer The polarizer is essentially a PVA-based resin layer whose iodine is oriented by adsorption. The thickness of the polarizer is 10 μm or less as described above, and is preferably 7.5 μm or less, and more preferably 5 μm or less. On the other hand, the thickness of the polarizer is preferably 0.5 μm or more, and more preferably 1.5 μm or more. If the thickness is too thin, the optical characteristics of the obtained polarizer may decrease. The polarizer should exhibit absorption dichroism at any wavelength of 380nm ~ 780nm. The single transmittance of the polarizer is preferably 40.0% or more, more preferably 41.0% or more, and even more preferably 42.0% or more. The degree of polarization of the polarizer should be 99.8% or more, more preferably 99.9% or more, and more preferably 99.95% or more.

The PVA-based resin forming the PVA-based resin layer is as described in the above item A-3.

C-2. Protective film As described above, the polarizing plate may have a protective film on the side of the polarizer opposite to the easy-adhesive layer. Examples of the material for forming the protective film include (meth) acrylic resins, cellulose resins such as diacetyl cellulose, triethyl cellulose, cycloolefin resins, olefin resins such as polypropylene, and polyterephthalene. Ester-based resins such as ethylene formate-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.

D. Manufacturing method of polarizing plate The manufacturing method of polarizing plate of the present invention includes the following steps: dyeing and extending the laminated body described in the above item A, thereby making a PVA-based resin layer into a polarizer. One embodiment may include the following steps: performing various processes such as a dyeing process, an elongation process, an insoluble process, a crosslinking process, a washing process, and a drying process on the laminated body. These treatments can be appropriately selected depending on the purpose. The processing order, processing sequence, number of processing times, and the like can be appropriately set. Each process will be described below.

D-1. Aerial extension processing The extension method of aerial subsidy extension can be fixed-end extension (such as the method of using a tenter extension machine) or free-end extension (such as passing the laminate through rollers with different peripheral speeds). And uniaxial extension method). In one embodiment, the air-stretching process includes a hot-roller stretching step, which is performed by conveying the laminated body along the longitudinal direction of the laminated body while extending the peripheral speed difference between the hot-rollers. The aerial stretching process includes a zone stretching step and a heat roller stretching step on the representative. In addition, the order of the zone extension step and the hot roll member extension step is not limited, and the zone extension step may be performed first, or the hot roll member extension step may be performed first. The region extension step may also be omitted. In one embodiment, the zone extension step and the hot roll member extension step are performed in this order.

The extension temperature of the laminated body can be set to an arbitrary and appropriate value in accordance with the material for forming the resin substrate. The elongation temperature during the aerial elongation treatment should be above the glass transition temperature (Tg) of the resin substrate, while the glass transition temperature (Tg) of the resin substrate is more preferably + 10 ° C or more, and Tg + 15 ° C is particularly suitable. On the other hand, the upper limit of the extension temperature of the laminate is preferably 170 ° C. Stretching at the above-mentioned temperature can suppress rapid progress of crystallization of the PVA-based resin, and can thereby suppress undesirable conditions caused by the crystallization (for example, the orientation of the PVA-based resin layer is hindered by the stretching).

The stretch ratio of the laminated body can be set to an arbitrary and appropriate value in accordance with the material for forming the resin substrate. The stretching magnification of aerial stretching processing should be 1.5 times or more and 3.0 times or less.

D-2. Insolubilization treatment The above-mentioned insolubilization treatment is performed by immersing a PVA-based resin layer in an aqueous boric acid solution. By applying the insolubilization treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insoluble bath (aqueous boric acid solution) is preferably 20 ° C to 50 ° C. The insolubilization treatment should be performed before the water extension or dyeing treatment.

D-3. Dyeing treatment The dyeing treatment mentioned above is performed by dyeing a PVA-based resin layer with a dichroic substance. It is preferable to perform adsorption of a dichroic substance on a PVA-based resin layer. Examples of the adsorption method include a method of immersing a PVA-based resin layer (layered body) in a dyeing solution containing a dichroic substance, a method of applying the dyeing solution to a PVA-based resin layer, and the dyeing solution. A method of spraying onto a PVA-based resin layer and the like. A method of immersing the laminated body in a dyeing solution is preferably adopted. Because it can absorb dichroic materials well.

Examples of the dichroic material include iodine and organic dyes. These may be used alone or in combination of two or more kinds. The dichroic substance is preferably iodine. When using iodine as a dichroic substance, the above-mentioned dyeing solution is preferably an iodine aqueous solution. The blending amount of iodine is preferably 0.05 to 5.0 parts by weight relative to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is suitable to mix iodide with iodine solution. 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, and titanium iodide. Of these, potassium iodide is preferred. The blending amount of iodide is preferably 0.3 to 15 parts by weight relative to 100 parts by weight of water.

The temperature of the dyeing liquid during dyeing should be 20 ° C ~ 40 ° C. When the PVA-based resin layer is immersed in the dyeing solution, the immersion time is preferably 10 seconds to 300 seconds. Under these conditions, the dichroic substance can be sufficiently adsorbed on the PVA-based resin layer. In addition, the dyeing conditions (concentration, liquid temperature, and immersion time) can be set so that the polarization degree or monomer transmittance of the polarizer finally obtained is within a predetermined range. In one embodiment, the immersion time is set so that the polarization degree of the obtained polarizer becomes 99.98% or more. In another embodiment, the immersion time is set so that the unit transmittance of the obtained polarizer is about 40%.

D-4. Cross-linking treatment The above-mentioned cross-linking treatment is representatively performed by immersing a PVA-based resin layer (layered body) in an aqueous boric acid solution. By performing a crosslinking treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 5 parts by weight relative to 100 parts by weight of water. When the crosslinking treatment is performed after the dyeing treatment, it is preferable to further mix iodide. By blending iodide, the elution of iodine which has been adsorbed on the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 to 5 parts by weight relative to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (aqueous boric acid solution) should preferably be 20 ° C to 60 ° C. The cross-linking treatment is preferably performed before the elongation treatment in water. The preferred embodiment is to perform the aerial stretching treatment, the dyeing treatment, and the crosslinking treatment in this order.

D-5. Extension treatment in water Any arbitrary method can be adopted as the extension method in the extension treatment in water. Specifically, it may be a fixed-end extension (for example, a method using a tenter stretcher) or a free-end extension (for example, a method for uniaxial extension of a laminated body through rollers with different peripheral speeds). In addition, it may be synchronous biaxial stretching (for example, a method using a synchronous biaxial stretching machine) or stepwise biaxial stretching. The extension of the laminate can be performed in one stage or in multiple stages. When carried out in multiple stages, the stretch magnification (maximum stretch magnification) of the laminate is the product of the stretch magnifications of each stage.

The extending direction of the laminated body can be selected in any desired direction. In one embodiment, it extends along the long-side direction of the long laminated body. Specifically, the laminated body is transported in the long side direction, that is, its transport direction (MD). In another embodiment, it extends along the width direction of the long laminated body. Specifically, the laminated body is transported in the longitudinal direction, that is, the direction (TD) orthogonal to the transport direction (MD) thereof.

The extension temperature of the laminated body can be set to an arbitrary and appropriate value in accordance with the forming material and extension method of the resin base material. The elongation temperature is preferably 40 ° C to 85 ° C and more preferably 50 ° C to 85 ° C. As long as the temperature is within the above range, the PVA-based resin layer can be suppressed from dissolving, and at the same time, it can be stretched at a high rate. Specifically, as described above, when considering the relationship with the formation of the PVA-based resin layer, the glass transition temperature (Tg) of the resin substrate is preferably 60 ° C or higher. At this time, if the stretching temperature is lower than 40 ° C, even if it is considered that the resin substrate is plasticized with water, it may not be stretched well. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and it is feared that excellent optical characteristics cannot be obtained.

Extension in water is preferably performed by immersing the laminate in an aqueous solution of boric acid (extension in boric acid). By using an aqueous boric acid solution as the stretching bath, the PVA-based resin layer can be provided with rigidity capable of withstanding the tension applied during stretching and water resistance insoluble in water. Specifically, boric acid generates a tetrahydroxyborate anion in an aqueous solution, and can be crosslinked with a PVA-based resin through hydrogen bonding. As a result, it is possible to impart rigidity and water resistance to the PVA-based resin layer and to extend well, and a polarizer having excellent optical characteristics (for example, polarization degree) can be produced.

The above boric acid aqueous solution is preferably obtained by dissolving boric acid and / or a borate in a solvent, that is, water. The boric acid concentration is preferably 1 to 10 parts by weight relative to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, it is possible to effectively suppress the dissolution of the PVA-based resin layer, and to manufacture a polarizer with higher characteristics. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, etc. in a solvent may be used.

If a dichroic substance (represented by iodine) has been adsorbed on the PVA-based resin layer by a dyeing treatment in advance, it is preferable to mix iodide in the above-mentioned extension bath (aqueous boric acid solution). By blending iodide, the elution of iodine which has been adsorbed on the PVA-based resin layer can be suppressed. 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, and titanium iodide. Of these, potassium iodide is preferred. The concentration of iodide is preferably 0.05 to 15 parts by weight, and more preferably 0.5 to 8 parts by weight relative to 100 parts by weight of water.

The extension ratio (maximum extension ratio) of the laminated body is 4.0 times or more, and preferably 5.0 times or more, relative to the original length of the laminated body. The high elongation ratio can be achieved by using, for example, an elongation method in water (elongation in boric acid). In addition, the "maximum extension ratio" in this specification means the extension ratio before the laminated body is fractured, and it is a value which is 0.2 lower than the value after confirming the extension ratio of the laminated body after fracture.

The elongation treatment in water is preferably performed after the dyeing treatment.

D-6. Washing process The washing process can be performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

D-7. Drying treatment The drying temperature in the drying treatment should be 30 ℃ ~ 100 ℃. Examples

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. The measurement method and evaluation method of each characteristic are as follows. (1) Thickness was measured using a digital micrometer (manufactured by Anritsu Corporation, product name "KC-351C"). (2) Water contact angle The water contact angle of the easy-adhesion layer was measured using an automatic contact angle meter (DM500) manufactured by Kyowa Interface Science Co., Ltd., and analyzed using FAMAS (contact angle measurement plug-in). The water used for the measurement was ultrapure water, and the titration was 0.5 μl. After the easy-adhesive layer was formed on the surface of the polyester-based resin substrate, the water contact angle (θ1) after 1 second after the water droplets were dropped onto the easy-adhesive layer, and the water contact angle (θ2) after 30 seconds from the drop were measured, and Calculate the diachronic change (θ2-θ1) caused by the water contact angle after 30 seconds.

〈Example 1〉 1. Laminated polyester resin base material is made of an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) having an elongated shape, a water absorption of 0.75%, and a Tg of 75 ° C. Film (thickness: 100 μm). Corona treatment was applied to one side of the polyester resin substrate, and the mixed solution (solid content concentration 4.0%) was applied on the corona-treated surface so that the thickness after drying became 2000 nm, and then at 60 ° C. It is dried for 3 minutes to form an easy-adhesive layer. The mixed solution is based on acetamidine modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200", polymerization degree 1200, saponification degree 99.0 mol% or more, A 4.0% aqueous solution of acetoacetic acid modified with 4.6%), and a modified polyolefin resin aqueous dispersant (manufactured by Unitika, trade name "ARROW BASE SE1030N", solid content concentration of 22%) mixed with pure water . Here, the blending ratio of the solid content of the acetamidine-modified PVA and the modified polyolefin in the mixed liquid is 50:50. Corona treatment is then applied to the surface of the easy-adhesive layer, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mole%) and B Aqueous solution of PVA modified with PVA (Polymerization degree 1200, Acetoacetate modified 4.6%, Saponification degree above 99.0 mole%, manufactured by Japan Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200") and dried, A PVA-based resin layer having a thickness of 11 μm was formed. A laminated body was produced as described above. 2. Fabrication of polarizers The obtained laminated body was extended freely and uniaxially by 2.0 times in the longitudinal direction (long side direction) between rollers with different peripheral speeds in a 120 ° C oven (air-assisted extension). Next, the laminated body was immersed in an insoluble bath (aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ° C. for 30 seconds (insolubilization treatment). Next, immerse it 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 has a predetermined transmittance. In this example, it was immersed in an aqueous iodine solution obtained by mixing 0.2 parts by weight of iodine and 1.0 part by weight of potassium iodide with respect to 100 parts by weight of water (dyeing treatment). Next, it was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ° C (crosslinking treatment) . After that, the laminate was immersed in a boric acid aqueous solution at a liquid temperature of 70 ° C (aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with 100 parts by weight of water) along the rollers at different peripheral speeds. Uniaxial stretching was performed in the longitudinal direction (long-side direction) so that the total stretching ratio was 5.5 times (stretching in water). Then, the laminated body was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 30 ° C (washing treatment). According to the above, a polarizing plate having a polarizer with a thickness of 5 μm formed on one side of a polyester resin substrate having a thickness of 30 μm can be obtained.

<Example 2> A polarizing plate was obtained in the same manner as in Example 1 except that the solid content blend ratio of the acetoacetic acid modified PVA and the modified polyolefin in the mixed solution was 30:70.

<Example 3> A polarizing plate was obtained in the same manner as in Example 1 except that the solid component blending ratio of acetoacetic acid modified PVA and modified polyolefin in the mixed solution was 20:80.

<Example 4> A polarizing plate was obtained in the same manner as in Example 1 except that the solid component blending ratio of acetoacetic acid modified PVA and modified polyolefin in the mixed solution was 10:90.

<Comparative Example 1> A polarizing plate was obtained in the same manner as in Example 1 except that an 4.0% aqueous solution of acetamidine-modified PVA (GOHSEFIMER Z200) was used in forming the easy-adhesion layer.

<Comparative Example 2> A polarizing plate was obtained in the same manner as in Example 1 except that the solid component blending ratio of acetoacetic acid modified PVA and modified polyolefin in the mixed solution was 90:10.

<Comparative Example 3> A polarizing plate was obtained in the same manner as in Example 1 except that the solid content blending ratio of acetoacetic acid modified PVA and modified polyolefin in the mixed solution was 70:30.

<Comparative Example 4> When forming an easy-adhesion layer, a modified polyolefin resin aqueous dispersion (manufactured by Unitika, trade name "ARROW BASE SE1030N", solid content concentration: 22%) was mixed with pure water ( A solid content concentration was 4.0%), and a polarizing plate was produced in the same manner as in Example 3 except for this.

(Evaluation) For the above examples and comparative examples, the adhesion was evaluated by measuring the PVA peeling force and the substrate peeling force. The evaluation results are integrated in Table 1. The measurement methods of the PVA peeling force and the substrate peeling force are as follows. (PVA peeling force) The obtained polarizing plate was coated with an adhesive on the side of the polyester resin substrate surface, and then bonded to a glass plate, and a polyimide tape for reinforcement was bonded to the surface of the polarizer (Nitto Denko Polyurethane Imide Adhesive Tape No. 360A), and a sample for measurement was prepared. A cutting knife was used to draw a cut between the polarizer of the sample for measurement and the polyester-based resin substrate, and then an angle-variable adhesion-film peeling analysis device "VPA-2" (manufactured by Kyowa Interface Chemical Co., Ltd.) was used. ), And measured the force required to pick up the polarizer and the polyimide tape for reinforcement at an angle of 90 ° with respect to the polyester resin substrate surface and peel it at a peeling speed of 3000mm / min (N / 15mm ). (Substrate Peeling Force) The obtained polarizing plate was coated with an adhesive on the surface of the polarizer and bonded to a glass plate to prepare a sample for measurement. After making a cut with a cutter between the polarizer of the sample for measurement and the polyester-based resin substrate, the polyester resin substrate was measured at 90 with respect to the surface of the polarizer by the above-mentioned "VPA-2" measurement. The force required for picking up at an angle of ° and peeling at a peeling speed of 3000 mm / min (N / 15 mm). [Table 1]

It is obvious from Table 1 that the polarizing plates of Examples 1 to 4 had a water contact angle of 70 ° or more when the water-dropping layer was just dropped, and the water-tapling contact angle of the easy-sticking layer after 30 seconds passed from the drop. Reduced by 2 ° or more, the adhesiveness between the polarizer and the polyester resin substrate is excellent.

Industrial Applicability The laminated body of the present invention is suitable for production of a polarizing plate. The polarizing plate of the present invention can be suitably used in an image display device such as a liquid crystal display device or an organic EL display device.

10‧‧‧ polyester resin substrate

20‧‧‧ Easy to attach layer

30‧‧‧Polyvinyl alcohol resin layer

100‧‧‧Laminated body

FIG. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention.

Claims (6)

A laminated body comprising: a polyester-based resin substrate having an easy-adhesive layer formed on its surface; and a polyvinyl alcohol-based resin layer which is laminated on the polyester-based resin substrate through the easily-adhesive layer; and water of the easily-adhesive layer. The contact angle is 70 ° or more immediately after the water droplet is dropped onto the easy-adhesion layer, and the contact angle decreases by 2 ° or more after 30 seconds from the dropping. The laminated body according to claim 1, wherein the easy-adhesive layer contains a polyvinyl alcohol-based component and a polyolefin-based component. For example, the laminated body of claim 2, wherein the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component is 10:90 to 50:50. A method for manufacturing a laminated body, comprising the steps of: forming an easy-adhesive layer on a surface of a polyester-based resin substrate; and forming a polyvinyl alcohol-based resin layer on the surface of the easy-adhesive layer; When the water droplets are dropped onto the easy-adhesion layer, the angle is 70 ° or more, and after 30 seconds from the dropping, the water droplets are reduced by 2 ° or more. A method for manufacturing a polarizing plate includes the steps of dyeing and extending the multilayer body according to any one of claims 1 to 3, thereby forming the aforementioned polyvinyl alcohol-based resin layer into a polarizer. A polarizing plate comprising: a polyester-based resin substrate having an easy-adhesive layer formed on a surface; and a polarizer, laminated on the polyester-based resin substrate through the easy-adhesive layer; a thickness of the polarizer is 10 μm or less; The water contact angle of the easy-adhesive layer is 70 ° or more when water droplets are immediately dropped onto the easy-adhesive layer, and 30 seconds after the dropping, the angle decreases by more than 2 °.