KR20200017398A - Laminated body, manufacturing method of laminated body, polarizing plate, and manufacturing method of polarizing plate - Google Patents

Abstract

Provided is a laminate having excellent adhesion between a polyester-based resin substrate and a polyvinyl alcohol-based resin layer. The laminate has a polyester resin substrate having an easily adhesive layer formed on its surface, and a polyvinyl alcohol resin layer laminated on the polyester resin substrate via an easily adhesive layer. It is 70 degrees or more immediately after 1 minute, and decreases by 2 degrees or more after 30 second passes from dripping.

Description

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

This invention relates to a laminated body, the manufacturing method of a laminated body, a polarizing plate, and the manufacturing method of a polarizing plate.

The method of obtaining a thin polarizer by forming a polyvinyl alcohol-type resin layer on a polyester-type resin base material, and extending | stretching and dyeing this laminated body is proposed (for example, patent document 1). The manufacturing method of such a polarizer attracts attention as it can contribute to thinning of an image display apparatus, for example.

The polyester resin substrate can be used as a protective layer of the polarizer without peeling off. Thereby, the laminated body of a polyester-type resin base material and a polarizer can be used as a polarizing plate as it is, without bonding a protective film to a polarizer, for example, and can contribute to cost reduction of an image display apparatus.

Japanese Laid-Open Patent Publication No. 2000-338329

However, the polarizing plate which is a laminated body of the polyester resin base material and polarizer obtained by the above method may become inadequate adhesiveness of a polyester resin base material and a polarizer.

This invention is made | formed in order to solve the said conventional subject, The main objective is the laminated body excellent in the adhesiveness of a polyester resin base material and a polyvinyl alcohol-type resin layer, the manufacturing method of such a laminated body, polyester resin It is providing the polarizing plate which is excellent in adhesiveness with a base material and a polarizer, and the manufacturing method of such a polarizing plate.

The laminated body of this invention has the polyester resin base material with an easily bonding layer formed on the surface, and the polyvinyl alcohol-type resin layer laminated | stacked on the said polyester resin base material through the said easily bonding layer, The said easily bonding layer The water contact angle of is 70 ° or more immediately after dropping water on the easily bonding layer, and decreases by 2 ° or more after 30 seconds have elapsed from the dropping.

In one embodiment, the easily bonding layer contains a polyvinyl alcohol component and a polyolefin component.

In one embodiment, the compounding ratio of the said polyvinyl alcohol component and the said polyolefin component is 10: 90-50: 50.

According to another situation of this invention, the manufacturing method of a laminated body is provided. The manufacturing method of this laminated body includes forming an easily bonding layer on the surface of a polyester resin base material, and forming a polyvinyl alcohol-type resin layer on the surface of the easily bonding layer, The water contact angle of the said easily bonding layer is the said It is 70 degrees or more immediately after water is dripped at an adhesive layer, and it decreases by 2 degrees or more as 30 second passes from this dripping.

According to another situation of this invention, the manufacturing method of a polarizing plate is provided. The manufacturing method of this polarizing plate includes making the said polyvinyl alcohol-type resin layer a polarizer by dyeing and extending | stretching the said laminated body.

According to another situation of this invention, a polarizing plate is provided. This polarizing plate has the polyester resin base material with an easily bonding layer formed on the surface, and the polarizer laminated | stacked on the said polyester resin base material through the said easily bonding layer, The thickness of the said polarizer is 10 micrometers or less, The contact angle is 70 ° or more immediately after dropping water on the easily bonding layer, and decreases by 2 ° or more after 30 seconds have elapsed from the dropping.

According to the present invention, the water contact angle is 70 ° or more immediately after dropping water, and by using an easy-adhesive layer that decreases by 2 ° or more after 30 seconds have elapsed from the dropping, the polyester-based resin substrate and the polyvinyl alcohol-based resin layer The laminated body excellent in adhesiveness, the manufacturing method of such a laminated body, and the polarizing plate excellent in adhesiveness of a polyester-type resin base material and a polarizer can be provided.

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

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

A. Laminate

1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention. The laminate 100 is a polyvinyl alcohol (PVA) laminated on the polyester resin substrate 10 via the polyester resin substrate 10 having the easily adhesive layer 20 formed on the surface thereof, and the easily adhesive layer 20. It has a system resin layer 30. The water contact angle of the easily bonding layer 20 is 70 degrees or more immediately after water is dripped at the easily bonding layer 20, and it decreases more than 2 degrees as 30 second passes from dripping. The time-dependent change (decrease) of the water contact angle is typically by measuring the water contact angle θ1 immediately after dropping water on the easily adhesive layer and the water contact angle θ2 30 seconds after the dropping, and subtracting θ1 from θ2. Obtained. The water contact angle immediately after dripping water to an easily bonding layer is typically the water contact angle measured 1 second after dripping. In one embodiment, the easily bonding layer 20 contains a polyvinyl alcohol component and a polyolefin component. In this case, the compounding ratio of the polyvinyl alcohol component and the polyolefin component is preferably 10:90 to 50:50. Thereby, the laminated body excellent in the adhesiveness of a polyester-type resin base material and a PVA-type resin layer can be obtained. In one embodiment, the said laminated body can be used for manufacture of a polarizing plate. The manufacturing method of a polarizing plate includes what makes a PVA system resin layer a polarizer by dyeing and extending | stretching a laminated body as mentioned later in item D.

A-1. Polyester resin base material

As a forming material of a polyester-type resin base material, For example, alicyclic dicarboxylic acid or alicyclic containing polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), isophthalic acid, a cyclohexane ring, etc. Copolymer PET (PET-G), other polyesters, copolymers and blends thereof, including diols of formula, etc. can be used. Among them, it is preferable to use amorphous (not crystallized) PET or copolymerized PET. According to these resins, in the unstretched state, they are amorphous, have excellent stretchability suitable for high magnification stretching, and can be given heat resistance and dimensional stability by crystallization by stretching and heating. Moreover, heat resistance to the extent which can apply | coat and dry PVA system resin in an unstretched state can be ensured.

The glass transition temperature (Tg) of a polyester resin base material becomes like this. Preferably it is 170 degrees C or less. By using such a polyester-based resin substrate, stretchability can be sufficiently secured while suppressing crystallization of the PVA-based resin layer. In consideration of satisfactorily performing plasticization and stretching in water of the polyester-based resin substrate with water, the temperature is more preferably 120 ° C or lower. In one embodiment, the glass transition temperature of a polyester resin base material becomes like this. Preferably it is 60 degreeC or more. By using such a polyester-based resin substrate, the polyester-based resin substrate is deformed (for example, irregularities, sagging, wrinkles, etc.) when the coating liquid containing PVA-based resin described later is applied and dried. Problems can be prevented. Moreover, extending | stretching of a laminated body can be performed favorably at preferable temperature (for example, about 60 degreeC-about 70 degreeC). In another embodiment, when apply | coating and drying a coating liquid containing PVA system resin, the glass transition temperature lower than 60 degreeC may be sufficient, unless a polyester-type resin base material does not deform | transform. In addition, glass transition temperature (Tg) is a value calculated | required according to JISK71121.

In one embodiment, it is preferable that a polyester resin base material has a water absorption of 0.2% or more, More preferably, it is 0.3% or more. Such a polyester-based resin substrate absorbs water and can plasticize by acting as a plasticizer. As a result, extending | stretching stress can be reduced significantly in underwater extending | stretching, and it can be excellent in stretchability. On the other hand, the water absorption of a polyester resin base material becomes like this. Preferably it is 3.0% or less, More preferably, it is 1.0% or less. By using such a polyester resin base material, the dimensional stability of a polyester resin base material falls remarkably at the time of manufacture, and the problem of deterioration of the external appearance of the laminated body obtained can be prevented. Moreover, it can prevent that it breaks at the time of extending | stretching in water, or peels a PVA system resin layer from a polyester resin base material. In addition, water absorption is a value calculated | required according to JISK7209.

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

The surface of a polyester resin base material may be previously surface-modified (for example, corona treatment). According to such a process, adhesiveness can be improved further.

A-2. Adhesive layer

As mentioned above, the water contact angle of an easily bonding layer is 70 degrees or more immediately after dripping water, and decreases by 2 degrees or more as 30 second passes from dripping. The water contact angle of the easily bonding layer immediately after dripping water becomes like this. Preferably it is 75 degrees-85 degrees. The change over time of the water contact angle due to the passage of 30 seconds from the dripping is preferably -2 ° (2 ° decrease) to -5 ° (5 ° decrease). The water-contact angle of the easily-adhesive layer immediately after dripping water is 70 degrees or more, and the time-dependent change (decrement) of the water-contact angle by 30 seconds after dripping is 2 degrees or more, so that the PVA-based resin layer is formed on the easily-adhesive layer. When formed, the composition for easily bonding layer formation can elute to a PVA-type resin layer. Specifically, when the time-dependent change in the water contact angle is from -2 ° to -5 °, when forming a coating layer of PVA-based resin on the easily adhesive layer, about 10% by volume to 34% by volume of the composition for easily adhesive layer forming is formed. It can elute to the coating layer of PVA system resin. Thereby, adhesiveness of a polyester-type resin base material and a PVA-type resin layer can be improved.

The easily adhesive layer may be a layer formed only of the composition for easily bonding layer formation described later substantially, or may be a layer or region in which the composition for easily bonding layer formation and the PVA resin layer described later are mixed (including commercial use). When the easily bonding layer is formed, excellent adhesiveness can be obtained. The thickness of the easily adhesive layer is preferably 500 nm to 3000 nm, and more preferably 800 nm to 2000 nm. When the thickness of an easily bonding layer is too thin, there exists a possibility that sufficient adhesiveness may not be obtained. On the other hand, if the thickness of the easily adhesive layer is too thick, problems such as lifting or non-uniformity occur in the resulting coating film during formation of the PVA-based resin coating layer described later, making it difficult to obtain a laminate having excellent appearance. The easily-adhesive layer which may be made to be confirmed can be confirmed, for example by observing the cross section of a laminated body with a scanning electron microscope (SEM).

The easily bonding layer preferably contains a polyvinyl alcohol-based component and a polyolefin-based component. By setting it as such a structure, the temporal change of the water contact angle and water contact angle of an easily bonding layer can become an angle within the said range, As a result, the laminated body excellent in the adhesiveness of a polyester-based resin base material and a PVA-type resin layer can be obtained. . Furthermore, the polarizing plate excellent in the adhesiveness of a polyester-type resin base material and a polarizer can be obtained by dyeing and extending | stretching the said laminated body. 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 an acetoacetyl group, a carboxylic acid group, an acryl group and / or a urethane group. Among these, acetoacetyl-modified PVA is used preferably. As acetoacetyl-modified PVA, the polymer which has at least a repeating unit represented by following General formula (I) is used preferably.

[Formula I]

In the above 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 10,000, and preferably 1200 to 5000. The degree of saponification 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, average polymerization degree and saponification degree can be calculated | required according to JISK6726-1994.

Arbitrary suitable polyolefin resin can be used as said polyolefin component. As an olefin component which is a main component of polyolefin resin, C2-C6 olefin hydrocarbons, such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, are mentioned, for example. These can be used individually or in combination of 2 or more types. Among these, olefin hydrocarbons having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene, and 1-butene are preferable, and ethylene is more preferably used.

Preferably the ratio which an olefin component occupies among the monomer components which comprise the said polyolefin resin is 50 weight%-95 weight%.

It is preferable that the said polyolefin resin has a carboxyl group and / or its anhydride group. Such a polyolefin resin can be dispersed in water, and an easily adhesive layer can be formed satisfactorily. As a monomer component which has such a functional group, unsaturated carboxylic acid, its anhydride, the 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 polyolefin resin is 5000-80000, for example.

The blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component in the easily adhesive layer (the former: the latter (solid content)) is preferably 10:90 to 50:50, more preferably 20:80 to 50:50. When there are too many polyvinyl alcohol-type components, there exists a possibility that adhesiveness may not fully be acquired. Specifically, there exists a possibility that peeling force required when peeling a PVA system resin layer from a polyester resin base material may fall, and sufficient adhesiveness may not be obtained. On the other hand, when there are too few polyvinyl alcohol-type components, there exists a possibility that the external appearance of the laminated body obtained may be impaired. Specifically, problems such as clouding of the coating film may occur at the time of formation of the easily adhesive layer, and it may be difficult to obtain a laminate having excellent appearance.

A-3. PVA system resin layer

Arbitrary suitable resin can be employ | adopted as PVA system resin which forms the said PVA system resin layer. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are mentioned. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying the ethylene-vinyl acetate copolymer. The degree of saponification 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%. Saponification degree can be calculated | required according to JISK6726-1994. The polarizer which is excellent in durability can be obtained by using PVA system resin of such saponification degree. If the degree of saponification is too high, there is a risk of gelation.

The average degree of polymerization of the PVA-based resin may be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. In addition, average polymerization degree can be calculated | required according to JISK6726-1994.

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 a PVA system resin layer becomes like this. Preferably it is 1.0 micrometer or more, More preferably, it is 2.0 micrometers or more.

B. Manufacturing Method of Laminate

The laminate of the present invention can be produced by any suitable method. In one embodiment, the said laminated body is manufactured by the method of forming an easily bonding layer on the surface of a polyester resin base material, and forming a PVA system resin layer on the surface of an easily bonding layer.

B-1. Formation of Easy Adhesive Layer

Arbitrary suitable methods may be employ | adopted as a method of forming an easily bonding layer on the surface of a polyester-type resin base material. Typically, the easily-adhesive layer is formed by applying the composition for forming an easily-adhesive layer to the surface of the polyester resin substrate and drying it. In the composition for forming an easily adhesive 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, more preferably 20:80 to 50:50. to be.

The composition for easily bonding layer formation is preferably aqueous. The composition for forming an easily adhesive layer may include an organic solvent. As an organic solvent, ethanol, isopropanol, etc. are mentioned, for example. Solid content concentration of the composition for easily bonding layer formation becomes like this. Preferably it is 1.0 weight%-10 weight%.

You may mix | blend an additive with the composition for easily bonding layer formation. As an additive, a crosslinking agent etc. are mentioned, for example. As a crosslinking agent, methylol compounds, such as oxazoline, a boric acid, trimethylol melamine, a carbodiimide, an isocyanate compound, an epoxy compound, etc. are mentioned, for example. The compounding quantity of the additive in the composition for easily bonding layer formation can be suitably set according to the objective. For example, the compounding amount of the crosslinking agent is preferably 10 parts by weight or less, more preferably 0.01 to 10 parts by weight, still more preferably 0.1 part by weight based on 100 parts by weight of the total of the polyvinyl alcohol-based component and the polyolefin-based component. It is-5 weight part.

Arbitrary appropriate methods can be employ | adopted as a coating method of the composition for easily bonding layer formation. For example, the roll coating method, the spin coating method, the wire bar coating method, the dip coating method, the die coating method, the curtain coating method, the spray coating method, the knife coating method (comma coating method etc.) etc. are mentioned.

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

B-2. Formation of PVA Resin Layer

Arbitrary suitable methods may be employ | adopted as a method of forming a PVA system resin layer on the surface of an easily bonding layer. Preferably, the coating liquid containing PVA system resin is apply | coated to the surface of the easily bonding layer formed in the polyester resin base material, and a PVA system resin layer is formed by drying.

The coating liquid containing PVA system resin is typically the solution which melt | dissolved the said PVA system resin in the solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, amines such as ethylenediamine and diethylenetriamine. Can be. These can be used individually or in combination of 2 or more types. Among these, Preferably it is water. The PVA 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 surfactant, a nonionic surfactant is mentioned, for example. These can be used for the purpose of further improving the uniformity, dyeing property, and stretchability of the obtained PVA-based resin layer. Moreover, as an additive, an easily adhesive component is mentioned, for example. By using an easily bonding component, the adhesiveness of a polyester resin base material and a PVA-type resin layer can be improved. As a result, for example, it is possible to suppress problems such as peeling of the PVA resin layer from the polyester resin substrate and to perform dyeing and stretching in water, which will be described later. As an easily bonding component, modified PVA, such as acetoacetyl modified PVA, is used, for example.

As a coating method of a coating liquid, the same method as the coating method of the said easily bonding layer forming composition can be employ | adopted. After application, the coating film can be dried. The drying temperature in this case becomes like this. Preferably it is 50 degreeC or more.

Before forming a PVA system resin layer, you may surface-treat (for example, corona treatment etc.) to an easily bonding layer. By performing such a process, the adhesiveness of a polyester-type resin base material and a PVA-type resin layer can be improved.

C. Polarizer

The polarizing plate of this invention has the polyester resin base material with an easily bonding layer formed in the surface, and the polarizer laminated | stacked on the polyester resin base material through the easily bonding layer. The thickness of a polarizer is 10 micrometers or less. The adhesive layer is as described in item A-2, and the method of forming the adhesive layer is as described in item B-1. Thereby, the polarizing plate excellent in the adhesiveness of a polyester-type resin base material and a polarizer can be obtained. The polarizing plate may have a protective film on the opposite side to the easily bonding layer of a polarizer.

C-1. Polarizer

The polarizer is substantially a PVA resin layer in which iodine is adsorbed and oriented. The thickness of a polarizer is 10 micrometers or less as mentioned above, Preferably it is 7.5 micrometers or less, More preferably, it is 5 micrometers or less. On the other hand, the thickness of a polarizer becomes like this. Preferably it is 0.5 micrometer or more, More preferably, it is 1.5 micrometers or more. When thickness is too thin, there exists a possibility that the optical characteristic of the polarizer obtained may fall. The polarizer preferably exhibits absorbing dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer is preferably 40.0% or more, more preferably 41.0% or more, and still more preferably 42.0% or more. The polarization degree of the polarizer is preferably 99.8% or more, more preferably 99.9% or more, and still more preferably 99.95% or more.

About PVA resin which forms the said PVA resin layer, it is as having demonstrated in the said A-3 item.

C-2. Protective film

The polarizing plate may have a protective film on the opposite side to the easily adhesive layer of the polarizer as described above. As a forming material of the said protective film, For example, cellulose resin, such as (meth) acrylic-type resin, diacetyl cellulose, and triacetyl cellulose, olefin resin, such as cycloolefin resin, polypropylene, ester type, such as polyethylene terephthalate resin Resins, polyamide resins, polycarbonate resins, copolymer resins thereof, and the like. The thickness of a protective film becomes like this. Preferably it is 10 micrometers-100 micrometers.

D. Manufacturing Method of Polarizing Plate

The manufacturing method of the polarizing plate of this invention includes what makes a PVA system resin layer a polarizer by dyeing and extending | stretching the laminated body demonstrated in said A item. In one embodiment, the laminate may include various treatments such as dyeing treatment, stretching treatment, insolubilization treatment, crosslinking treatment, washing treatment and drying treatment. These treatments can be appropriately selected depending on the purpose. Further, the processing order, processing timing, processing count, and the like can be appropriately set. Hereinafter, each process will be described.

D-1. Aerial stretching treatment

The stretching method of the air-assisted stretching may be fixed-end stretching (for example, stretching using a tenter stretching machine) or free-end stretching (for example, uniaxial stretching by passing a laminate between rolls having different circumferential speeds). do. In one embodiment, the air-stretching process includes the heat roll extending | stretching process of extending | stretching by the circumferential speed difference between heat rolls, conveying the said laminated body in the longitudinal direction. The air stretching treatment typically includes a zone stretching process and a heat roll stretching process. In addition, the order of a zone extending process and a heat roll extending process is not limited, A zone extending process may be performed first, and a heat roll extending process may be performed first. The zone stretching step may be omitted. In one embodiment, the zone stretching process and the hot roll stretching process are performed in this order.

The extending | stretching temperature of a laminated body can be set to arbitrary appropriate values according to the formation material etc. of a resin base material. The stretching temperature in the air stretching treatment is preferably equal to or higher than the glass transition temperature (Tg) of the resin substrate, more preferably equal to or higher than the glass transition temperature (Tg) + 10 ° C of the resin substrate, particularly preferably Tg + 15 ° C or higher. to be. On the other hand, the upper limit of the extending | stretching temperature of a laminated body becomes like this. Preferably it is 170 degreeC. By extending | stretching at such temperature, it can suppress that the crystallization of PVA system resin advances rapidly, and can suppress the problem by the said crystallization (for example, disturbing the orientation of the PVA system resin layer by extending | stretching).

The draw ratio of a laminated body can be set to arbitrary appropriate values according to the formation material of a resin base material, etc. The draw ratio in the air stretching treatment is preferably 1.5 times or more and 3.0 times or less.

D-2. Insolubilization treatment

The insolubilization treatment is typically carried out by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing insolubilization treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous 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 insolubilization bath (boric acid solution solution) is preferably 20 ° C to 50 ° C. Preferably, the insolubilization treatment is performed before the stretching or dyeing treatment in water.

D-3. Dyeing treatment

The dyeing treatment is typically carried out by dyeing the PVA-based resin layer with a dichroic substance. Preferably, the dichroic substance is adsorbed onto the PVA resin layer. As the adsorption method, for example, a method of immersing a PVA-based resin layer (laminate) in a dyeing solution containing a dichroic substance, a method of coating the dyeing solution on a PVA-based resin layer, and the dyeing solution to a PVA-based resin layer And a method of spraying. Preferably, it is a method of immersing a laminated body in dyeing liquid. It is because a dichroic substance can adsorb | suck favorably.

Examples of the dichroic substance include iodine and organic dyes. These can be used individually or in combination of 2 or more types. The dichroic material is preferably iodine. When iodine is used as the dichroic substance, the dyeing solution is preferably an iodine aqueous solution. The blending amount of iodine is preferably 0.05 part by weight to 5.0 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 the iodide in an aqueous solution of iodine. Examples of 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, potassium iodide is preferable. The compounding amount of iodide is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of water.

The liquid temperature at the time of dyeing of a dyeing liquid becomes like this. Preferably it is 20 degreeC-40 degreeC. When immersing a PVA system resin layer in a dyeing liquid, immersion time becomes like this. Preferably it is 10 second-300 second. Under such conditions, the dichroic substance can be sufficiently adsorbed onto the PVA resin layer. In addition, dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the polarization degree or single transmittance of the polarizer finally obtained may become a predetermined range. In one embodiment, the immersion time is set so that the polarization degree of light polarizer obtained may be 99.98% or more. In another embodiment, immersion time is set so that the unitary transmittance of the polarizer obtained may be about 40%.

D-4. Crosslinking treatment

The crosslinking treatment is typically carried out by dipping a PVA-based resin layer (laminate) in an aqueous boric acid solution. Water resistance can be provided to a PVA system resin layer by performing a crosslinking process. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. In addition, when performing a crosslinking process after the said dyeing process, it is also preferable to mix | blend an iodide. By mix | blending an iodide, the elution of the iodine made to adsorb | suck to the PVA system resin layer can be suppressed. The blending amount of the 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 (boric acid aqueous solution) is preferably 20 ° C to 60 ° C. Preferably, the crosslinking treatment is performed before the underwater stretching treatment. In a preferred embodiment, aerial stretching treatment, dyeing treatment and crosslinking treatment are performed in this order.

D-5. Underwater stretching

Arbitrary appropriate methods can be employ | adopted as the extending | stretching method in the underwater extending | stretching process. Specifically, it may be fixed end stretching (eg, a method using a tenter stretching machine) or free end stretching (eg, uniaxial stretching through a laminate between rolls having different circumferential speeds). Moreover, simultaneous biaxial stretching (for example, a method using a simultaneous biaxial stretching machine) may be sufficient, and biaxial stretching may be sequentially. Stretching of the laminate may be performed in one step or may be performed in multiple steps. When performing in multiple stages, the draw ratio (maximum draw ratio) of a laminated body is the product of draw ratio of each step.

Arbitrary appropriate directions can be selected as a extending direction of a laminated body. In one embodiment, it extends | stretches to the longitudinal direction of the elongate laminated body. Specifically, the laminate is conveyed in the longitudinal direction, and the conveyance direction MD is used. In another embodiment, the film is stretched in the width direction of the long laminate. Specifically, it is a direction (TD) which conveys a laminated body in a longitudinal direction and orthogonally crosses the conveyance direction (MD).

The extending | stretching temperature of a laminated body can be set to arbitrary appropriate values according to the formation material, extending | stretching system, etc. of a resin base material. The stretching temperature is preferably 40 ° C to 85 ° C, more preferably 50 ° C to 85 ° C. If it is such temperature, it can extend | stretch at high magnification, suppressing melt | dissolution of a PVA system resin layer. Specifically, as above-mentioned, the glass transition temperature (Tg) of a resin base material becomes like this. Preferably it is 60 degreeC or more in relationship with formation of a PVA system resin layer. In this case, when extending | stretching temperature is less than 40 degreeC, even if it considers plasticization of the resin base material by water, there exists a possibility that it may not extend | stretch satisfactorily. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and there is a fear that excellent optical characteristics cannot be obtained.

Stretching in water is preferably carried out by immersing the laminate in an aqueous boric acid solution (stretching in boric acid). By using boric acid aqueous solution as a stretching bath, the rigidity which endures the tension | tensile_strength applied at the time of extending | stretching to a PVA system resin layer, and water resistance which does not melt | dissolve in water can be provided. Specifically, boric acid can form tetrahydroxyboric acid anion in aqueous solution, and can bridge | crosslink by PVA system resin and hydrogen bond. As a result, rigidity and water resistance can be provided to a PVA resin layer, it can extend | stretch favorable, and the polarizer which has the outstanding optical characteristic (for example, polarization degree) can be manufactured.

The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 part by weight to 10 parts by weight with respect to 100 parts by weight of water. By making a boric acid concentration 1 weight part or more, melt | dissolution of a PVA system resin layer can be suppressed effectively, and the polarizer of a higher characteristic can be produced. In addition to boric acid or borates, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

When a dichroic substance (typically, iodine) is adsorb | sucked to PVA system resin layer previously by the dyeing process, Iodide is mix | blended preferably with the said stretching bath (boric acid aqueous solution). By mix | blending an iodide, the elution of the iodine made to adsorb | suck to the PVA system resin layer can be suppressed. Examples of 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, potassium iodide is preferable. The concentration of the 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 draw ratio (maximum draw ratio) of the laminate is typically 4.0 times or more, preferably 5.0 times or more with respect to the original length of the laminate. Such a high draw ratio can be achieved by employ | adopting an underwater drawing system (boric-acid underwater drawing), for example. In addition, in this specification, "maximum draw ratio" means the draw ratio just before a laminated body breaks, and confirms the draw ratio which a laminated body fractures separately, and means the value lower than the value.

Preferably, the underwater stretching treatment is carried out after the dyeing treatment.

D-6. Cleaning treatment

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

D-7. Dry treatment

The drying temperature in a drying process becomes like this. Preferably it is 30 degreeC-100 degreeC.

Example

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method and evaluation method of each characteristic are as follows.

(1) thickness

It measured using the digital micrometer (the Anritsu make, product name "KC-351C").

(2) water contact angle

The water contact angle of the adhesive layer was measured using an automatic contact angle meter (DM500) manufactured by Kyowa Interface Science Co., Ltd., and analyzed using FAMAS (contact angle measurement add-in software). Ultrapure water was used for the water for measurement, and the droplets were 0.5 µl.

After forming an easily bonding layer on the surface of a polyester resin base material, the water contact angle ((theta) 1) after 1 second passed after water was dripped at the easily bonding layer, and the water contact angle (theta) 2 after 30 second from dripping were measured, and it was 30 second. The time-dependent change (θ2-θ1) of the water contact angle over time was calculated.

<Example 1>

1. Fabrication of laminate

As a polyester resin base material, the amorphous isophthalic-acid copolymerization polyethylene terephthalate (IPA copolymerization PET) film (thickness: 100 micrometers) of elongate water absorption of 0.75% and Tg 75 degreeC was used.

Corona treatment is performed on one side of the polyester resin base material, and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name "Gocefimer Z200", polymerization degree 1200, saponification degree 99.0 mol% or more, acetoacetyl on the corona treatment surface After drying a 4.0% aqueous solution of a degree of modification (4.6%), a modified polyolefin resin aqueous dispersion (Unitica Co., Ltd., trade name "Arobase SE1030N", solid content concentration 22%) and pure water (solid content concentration 4.0%) It applied so that it might be set to 2000 nm, and it dried at 60 degreeC for 3 minutes, and formed the easily bonding layer. Here, the solid content compounding ratio of acetoacetyl-modified PVA and modified polyolefin in the liquid mixture was 50:50.

Subsequently, the surface of the easily adhesive layer was subjected to corona treatment, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol) were subjected to corona treatment. An aqueous solution containing not less than% and manufactured by Nippon Synthetic Chemicals Co., Ltd., brand name "Gocefimer Z200" in a ratio of 9: 1 was applied and dried at 25 ° C to form a PVA resin layer having a thickness of 11 µm. In this way, a laminated body was produced.

2. Fabrication of Polarizer

The obtained laminated body was uniaxially stretched free end by 2.0 times in the longitudinal direction (length direction) between rolls from which a circumferential speed differs in 120 degreeC oven (air auxiliary stretching).

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

Subsequently, it was immersed in the dyeing bath of 30 degreeC of liquid temperature, adjusting iodine density | concentration and immersion time so that the polarizing plate obtained may become predetermined | prescribed transmittance | permeability. In the present Example, 0.2 weight part of iodine was mix | blended with respect to 100 weight part of water, and 1.0 weight part of potassium iodide was mix | blended, and it was immersed for 60 second in the aqueous solution of iodine obtained.

Subsequently, it was immersed for 30 second in the crosslinking bath (The boric acid aqueous solution obtained by mix | blending 3 weight part of potassium iodide, and mixing 3 weight part of boric acid with respect to 100 weight part of water) with a liquid temperature of 30 degreeC (crosslinking process).

Thereafter, the laminate was immersed in an aqueous boric acid solution having a liquid temperature of 70 ° C. (aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water and 5 parts by weight of potassium iodide) to form a spool between rolls having different circumferential speeds. Uniaxial stretching was performed so that a total draw ratio might be 5.5 times in the direction (length direction) (underwater stretching).

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

In this way, the polarizing plate in which the polarizer with a thickness of 5 micrometers was formed in the one side of the polyester resin base material with a thickness of 30 micrometers was obtained.

<Example 2>

A polarizing plate was obtained in the same manner as in Example 1 except that the solid content compounding ratio of acetoacetyl-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 content blending ratio of acetoacetyl-modified PVA and the 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 content blending ratio of acetoacetyl-modified PVA and the 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 a 4.0% aqueous solution of acetoacetyl-modified PVA (Gocefimer Z200) was used in the formation of the easily adhesive layer.

Comparative Example 2

A polarizing plate was obtained in the same manner as in Example 1 except that the solid content blending ratio of acetoacetyl-modified PVA and the 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 acetoacetyl-modified PVA and the modified polyolefin in the mixed liquid was 70:30.

<Comparative Example 4>

The same procedure as in Example 3 was carried out except that a modified polyolefin resin aqueous dispersion (Unitica Co., Ltd., trade name "Arobase SE1030N", solid content concentration 22%) and a mixture of pure water (solid content concentration 4.0%) were used to form the easily-adhesive layer. To obtain a polarizing plate.

(evaluation)

About the said Example and the comparative example, adhesiveness was evaluated by measuring PVA peeling force and a base material peeling force. The evaluation results are summarized in Table 1. The measuring method of PVA peeling force and a base material peeling force is as follows.

(PVA Peeling Force)

The obtained polarizing plate is apply | coated to a glass plate, and an adhesive is apply | coated to a polyester resin base material surface side, and a polyimide tape (Nitto Denko Co., Ltd. product, polyimide adhesive tape No. 360A) for reinforcement is bonded together to a polarizer surface for a measurement Samples were made. The cutter knife is cut between the polarizer and the polyester resin base material of the sample for measurement, and the polarizer and the polyimide tape for reinforcement are made to have an angle of 90 ° with respect to the polyester resin base material surface, and the peel rate is 3000. The force (N / 15 mm) required when peeling at mm / min was measured by angle material type adhesion | attachment / film peeling analyzer "VPA-2" (made by Kyowa Interface Chemical Co., Ltd.).

(Substrate peeling force)

The obtained polarizing plate was apply | coated the adhesive on the polarizer surface side, and it bonded to the glass plate, and the sample for a measurement was produced. When a cutter knife is cut out between the polarizer of this measurement sample and a polyester-based resin base material, and a polyester-based resin base material is made to make an angle of 90 degrees with respect to a polarizer surface, and it peels at a peeling speed of 3000 mm / min. The required force (N / 15 mm) was measured by the "VPA-2" above.

TABLE 1

As is apparent from Table 1, the polarizing plates of Examples 1 to 4 in which the water contact angle of the easily adhesive layer immediately after dropping water is 70 ° or more, and the water contact angle of the easily adhesive layer decreases by 2 ° or more by 30 seconds from the dripping. , The adhesiveness between the polarizer and the polyester resin base material was excellent.

The laminated body of this invention is used suitably for manufacture of a polarizing plate. The polarizing plate of this invention is used suitably for image display apparatuses, such as a liquid crystal display device and an organic electroluminescence display.

10: polyester resin base material
20: adhesive layer
30: polyvinyl alcohol-based resin layer
100: laminate

Claims (6)

It has a polyester resin base material with an easily bonding layer formed on the surface, and the polyvinyl alcohol-type resin layer laminated | stacked on the said polyester resin base material through the said easily bonding layer,
The water contact angle of the said easily bonding layer is 70 degrees or more immediately after water is dripped at the said easily bonding layer, and the laminated body which reduces by 2 degrees or more after 30 second passes from the said dripping. The method of claim 1,
The laminated body in which the said easily bonding layer contains a polyvinyl alcohol-type component and a polyolefin type component. The method of claim 2,
The laminated body whose compounding ratio of the said polyvinyl alcohol component and the said polyolefin component is 10: 90-50: 50. Forming an easily adhesive layer on the surface of the polyester-based resin substrate,
It includes forming a polyvinyl alcohol-based resin layer on the surface of the easily adhesive layer,
The water contact angle of the said easily bonding layer is 70 degrees or more immediately after water is dripped at the said easily bonding layer, and the manufacturing method of the laminated body reduces by 2 degrees or more as 30 second passes from the said dripping. The manufacturing method of the polarizing plate containing making the said polyvinyl alcohol-type resin layer into a polarizer by dyeing and extending | stretching the laminated body in any one of Claims 1-3. It has a polyester resin base material with an easily bonding layer formed on the surface, and the polarizer laminated | stacked on the said polyester resin base material through the said easily bonding layer,
The thickness of the said polarizer is 10 micrometers or less,
The water contact angle of the said easily bonding layer is 70 degrees or more immediately after water is dripped at the said easily bonding layer, and the polarizing plate reduces by more than 2 degrees after 30 second passes from the said dripping.

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