WO2018230429A1 - 積層体、積層体の製造方法、偏光板、および偏光板の製造方法 - Google Patents
積層体、積層体の製造方法、偏光板、および偏光板の製造方法 Download PDFInfo
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- WO2018230429A1 WO2018230429A1 PCT/JP2018/021827 JP2018021827W WO2018230429A1 WO 2018230429 A1 WO2018230429 A1 WO 2018230429A1 JP 2018021827 W JP2018021827 W JP 2018021827W WO 2018230429 A1 WO2018230429 A1 WO 2018230429A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
- B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/14—Printing or colouring
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
- B32B2038/0028—Stretching, elongating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/40—Properties of the layers or laminate having particular optical properties
- B32B2307/42—Polarizing, birefringent, filtering
Definitions
- the present invention relates to a laminate, a method for producing a laminate, a polarizing plate, and a method for producing a polarizing plate.
- Patent Document 1 There has been proposed a method of obtaining a thin polarizer by forming a polyvinyl alcohol resin layer on a polyester resin substrate and stretching and dyeing the laminate (for example, Patent Document 1). Such a method for manufacturing a polarizer has been attracting attention, for example, as it can contribute to a reduction in the thickness of an image display device.
- the polyester-based resin base material can be used as a protective layer for a polarizer without being peeled off.
- the laminated body of a polyester-type resin base material and a polarizer can be used as it is as a polarizing plate, without bonding a protective film to a polarizer, For example, it can contribute to the cost reduction of an image display apparatus.
- the polarizing plate that is a laminate of the polyester resin base material and the polarizer obtained by the above method may have insufficient adhesion between the polyester resin base material and the polarizer.
- the present invention has been made in order to solve the above-described conventional problems, and the main purpose thereof is a laminate having excellent adhesion between a polyester-based resin substrate and a polyvinyl alcohol-based resin layer, and production of such a laminate. It is in providing the polarizing plate which is excellent in the adhesiveness of a method, a polyester-type resin base material, and a polarizer, and the manufacturing method of such a polarizing plate.
- the laminate of the present invention has a polyester resin base material having an easy-adhesion layer formed on the surface, and a polyvinyl alcohol resin layer laminated on the polyester resin base material via the easy-adhesion layer.
- the water contact angle of the easy-adhesion layer is 70 ° or more immediately after water is dropped onto the easy-adhesion layer, and decreases by 2 ° or more after 30 seconds have passed since the addition.
- an easily bonding layer contains a polyvinyl alcohol-type component and a polyolefin-type component.
- the blending ratio of the polyvinyl alcohol component to the polyolefin component is 10:90 to 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 easy-adhesion layer on the surface of the polyester-based resin base material, and forming a polyvinyl alcohol-based resin layer on the surface of the easy-adhesion layer.
- the water contact angle is 70 ° or more immediately after dropping water on the easy-adhesion layer, and decreases by 2 ° or more after 30 seconds have passed since the dropping.
- 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 into a polarizer by dye
- a polarizing plate is provided.
- This polarizing plate has a polyester-based resin substrate having an easy-adhesion layer formed on the surface, and a polarizer laminated on the polyester-based resin substrate via the easy-adhesion layer.
- the thickness is 10 ⁇ m or less, and the water contact angle of the easy-adhesion layer is 70 ° or more immediately after the water is dropped onto the easy-adhesion layer, and decreases by 2 ° or more when 30 seconds elapse from the dropping.
- the water contact angle is 70 ° or more immediately after dropping water, and decreases by 2 ° or more after 30 seconds have passed from the dropping.
- the laminated body which is excellent in the adhesiveness of a material and a polyvinyl alcohol-type resin layer, the manufacturing method of such a laminated body, and the polarizing plate which is excellent in the adhesiveness of a polyester-type resin base material and a polarizer can be provided.
- FIG. 1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention.
- the laminate 100 includes a polyester resin substrate 10 having an easy adhesion layer 20 formed on the surface, and a polyvinyl alcohol (PVA) resin layer 30 laminated on the polyester resin substrate 10 with the easy adhesion layer 20 interposed therebetween.
- PVA polyvinyl alcohol
- the water contact angle of the easy-adhesion layer 20 is 70 ° or more immediately after dropping water on the easy-adhesion layer 20, and decreases by 2 ° or more when 30 seconds elapse from the dropping.
- the change (decrease) in the water contact angle with time is typically measured by measuring the water contact angle ( ⁇ 1) immediately after dropping water on the easy adhesion layer and the water contact angle ( ⁇ 2) 30 seconds after dropping.
- the water contact angle immediately after dropping water on the easy adhesion layer is typically a water contact angle measured 1 second after the dropping.
- the easy-adhesion layer 20 includes a polyvinyl alcohol-based component and a polyolefin-based component.
- the blending ratio of the polyvinyl alcohol component to the polyolefin component is preferably 10:90 to 50:50.
- the laminated body excellent in the adhesiveness of a polyester-type resin base material and a PVA-type resin layer can be obtained.
- the laminate can be used to make a polarizing plate.
- the manufacturing method of a polarizing plate includes making a PVA-type resin layer into a polarizer by dyeing
- polyester resin base material As a forming material of the polyester resin base material, for example, alicyclic type including polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), isophthalic acid, cyclohexane ring, etc.
- PET-G polyethylene terephthalate
- PBT polybutylene terephthalate
- PEN polyethylene naphthalate
- isophthalic acid cyclohexane ring
- PET-G copolymerized PET
- PET-G containing a dicarboxylic acid or an alicyclic diol, other polyesters, copolymers or blends thereof, and the like can be used.
- PET-G containing a dicarboxylic acid or an alicyclic diol, other polyesters, copolymers or blends thereof, and the like
- PET-G containing a dicarboxylic acid or an alicyclic diol, other polyester
- the glass transition temperature (Tg) of the polyester resin substrate is preferably 170 ° C. or lower.
- Tg glass transition temperature
- the polyester-based resin base material is plasticized with water and performing good stretching in water, it is more preferably 120 ° C. or lower.
- the glass transition temperature of the polyester resin substrate is preferably 60 ° C. or higher.
- the laminate can be stretched satisfactorily at a suitable temperature (for example, about 60 ° C. to 70 ° C.).
- a glass transition temperature lower than 60 ° C. may be used as long as the polyester resin base material is not deformed when applying and drying a coating solution containing a PVA resin.
- the glass transition temperature (Tg) is a value determined according to JIS K 7121.
- the polyester resin base material preferably has a water absorption rate of 0.2% or more, and more preferably 0.3% or more.
- a polyester resin base material absorbs water, and the water can act as a plasticizer to be plasticized.
- the stretching stress can be greatly reduced in stretching in water, and the stretchability can be excellent.
- the water absorption rate of the polyester resin substrate is preferably 3.0% or less, more preferably 1.0% or less.
- the thickness of the polyester resin substrate is preferably 20 ⁇ m to 300 ⁇ m, more preferably 30 ⁇ m to 200 ⁇ m.
- the surface of the polyester resin substrate may be subjected to a surface modification treatment (for example, a corona treatment) in advance. Such treatment can further improve the adhesion.
- a surface modification treatment for example, a corona treatment
- the water contact angle of the easy-adhesion layer is 70 ° or more immediately after the water is dropped, and decreases by 2 ° or more after 30 seconds have passed since the dropping.
- the water contact angle of the easy-adhesion layer immediately after dripping water is preferably 75 ° to 85 °.
- the change with time of the water contact angle with the passage of 30 seconds from dropping is preferably ⁇ 2 ° (decrease of 2 °) to ⁇ 5 ° (decrease of 5 °).
- the water contact angle of the easy-adhesion layer immediately after dropping water is 70 ° or more, and the change (decrease) in water contact angle over time after 30 seconds has passed since dropping is 2 ° or more.
- the easy-adhesion layer-forming composition can be eluted into the PVA resin layer.
- a composition for forming an easily adhesive layer is formed when a PVA-based resin coating layer is formed on the easily adhesive layer.
- Of about 10 to 34% by volume can be eluted in the coating layer of the PVA resin.
- the easy-adhesion layer may be a layer formed substantially only from the composition for forming an easy-adhesion layer described later, and the composition for forming an easy-adhesion layer and a PVA-based resin layer described later are mixed (compatible). A layer or region that is included).
- 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.
- the thickness of the easy-adhesion layer is too thick, when forming a PVA-based resin coating layer described later, defects such as repelling and unevenness in the resulting coating film occur, resulting in excellent appearance.
- the easy-adhesion layer that may make it difficult to obtain a laminate can be confirmed by, for example, observing the cross section of the laminate with a scanning electron microscope (SEM).
- the easy adhesion layer preferably contains a polyvinyl alcohol-based component and a polyolefin-based component.
- a polyvinyl alcohol-based component By setting it as such a composition, the water contact angle of an easily bonding layer and the time-dependent change of a water contact angle can become an angle in said range, As a result, the adhesiveness of a polyester-type resin base material and a PVA-type resin layer Can be obtained.
- stretching the said laminated body can obtain the polarizing plate which is excellent in the adhesiveness of a polyester-type resin base material and a polarizer.
- Any appropriate PVA-based resin can be used as the polyvinyl alcohol-based component. Specific examples include polyvinyl alcohol and modified polyvinyl alcohol.
- modified polyvinyl alcohol examples include polyvinyl alcohol modified with an acetoacetyl group, a carboxylic acid group, an acrylic group and / or a urethane group.
- acetoacetyl-modified PVA is preferably used.
- a polymer having at least a repeating unit represented by the following general formula (I) is preferably used.
- the ratio of n to l + m + n is preferably 1% to 10%.
- the average degree of polymerization of the acetoacetyl-modified PVA is preferably 1000 to 10,000, and preferably 1200 to 5,000.
- the saponification degree of acetoacetyl-modified PVA is preferably 97 mol% or more.
- the pH of a 4% by weight aqueous solution of acetoacetyl-modified PVA is preferably 3.5 to 5.5.
- the average polymerization degree and saponification degree can be determined according to JIS K 6726-1994.
- any appropriate polyolefin resin can be used as the polyolefin component.
- the olefin component that is a main component of the polyolefin resin include olefin hydrocarbons having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene. These may be used alone or in combination of two or more. Among these, olefinic hydrocarbons having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene are preferable, and ethylene is more preferably used.
- the proportion of the olefin component in the monomer component constituting the polyolefin resin is preferably 50% by weight to 95% by weight.
- the polyolefin-based resin preferably has a carboxyl group and / or an anhydride group thereof.
- a polyolefin resin can be dispersed in water, and an easy-adhesion layer can be formed well.
- the monomer component having such a functional group include unsaturated carboxylic acids and anhydrides thereof, half esters and half amides of unsaturated dicarboxylic acids. 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, 5000 to 80000.
- the blending ratio of the polyvinyl alcohol component and the polyolefin component is preferably 10:90 to 50:50, more preferably 20:80 to 50:50.
- the peeling force required when peeling the PVA-based resin layer from the polyester-based resin substrate may be reduced, and sufficient adhesion may not be obtained.
- the external appearance of the laminated body obtained may be impaired.
- problems such as a clouding of the coating film may occur, and it may be difficult to obtain a laminate having an excellent appearance.
- PVA-type resin layer Arbitrary appropriate resin may be employ
- examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer.
- Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
- the ethylene-vinyl alcohol copolymer can be obtained by saponifying an 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%. .
- the degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizer having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.
- the average degree of polymerization of the PVA 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 determined according to JIS K 6726-1994.
- the thickness of the PVA resin layer is typically 20 ⁇ m or less, preferably 15 ⁇ m or less, and more preferably 10 ⁇ m or less. On the other hand, the thickness of the PVA resin layer is preferably 1.0 ⁇ m or more, more preferably 2.0 ⁇ m or more.
- the laminated body of this invention may be manufactured by arbitrary appropriate methods.
- the laminate is produced by a method including forming an easy-adhesion layer on the surface of the polyester-based resin base material and forming a PVA-based resin layer on the surface of the easy-adhesion layer. Is done.
- the easy-adhesion layer is formed by applying a composition for forming an easy-adhesion layer on the surface of a polyester-based resin substrate and drying it.
- the blending ratio of the polyvinyl alcohol component to the polyolefin component is preferably 10:90 to 50:50, more preferably 20:80 to 50. : 50.
- the easy-adhesion layer-forming composition is preferably aqueous.
- the composition for easily bonding layer formation may contain an organic solvent. Examples of the organic solvent include ethanol and isopropanol.
- the solid content concentration of the easily adhesive layer forming composition is preferably 1.0% by weight to 10% by weight.
- An additive may be added to the easy-adhesion layer forming composition.
- the additive include a crosslinking agent.
- the crosslinking agent include methylol compounds such as oxazoline, boric acid, and trimethylolmelamine, carbodiimide, isocyanate compounds, and epoxy compounds.
- the compounding quantity of the additive in the composition for easily bonding layer formation can be suitably set according to the objective etc.
- the amount of the crosslinking agent is preferably 10 parts by weight or less, more preferably 0.01 parts by weight to 10 parts by weight, and still more preferably with respect to 100 parts by weight of the total of the polyvinyl alcohol component and the polyolefin component. 0.1 to 5 parts by weight.
- Arbitrary appropriate methods can be employ
- Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method and the like).
- the coating film After application of the easy-adhesion layer-forming composition, the coating film can be dried.
- the drying temperature is, for example, 50 ° C. or higher.
- PVA-based resin layer Any appropriate method may be adopted as a method of forming the PVA-based resin layer on the surface of the easy-adhesion layer.
- a PVA-based resin layer is formed by applying a coating solution containing a PVA-based resin to the surface of the easy-adhesion layer formed on the polyester-based resin base material and drying it.
- the coating solution containing the PVA resin is typically a solution obtained by dissolving the PVA resin in a solvent.
- the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among these, water is preferable.
- the concentration of the PVA resin in the coating solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film can be formed.
- Additives may be added to the coating solution.
- the additive include a plasticizer and a surfactant.
- the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin.
- the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the resulting PVA-based resin layer.
- an easily bonding component is mentioned, for example. By using an easy-adhesion component, the adhesiveness of a polyester-type resin base material and a PVA-type resin layer can be improved.
- the easily adhesive component for example, modified PVA such as acetoacetyl-modified PVA is used.
- the same method as the coating method of the composition for easily bonding layer formation can be employed.
- the coating film After application, the coating film can be dried.
- the drying temperature in this case is preferably 50 ° C. or higher.
- the easy-adhesion layer Before forming the PVA-based resin layer, the easy-adhesion layer may be subjected to a surface treatment (for example, corona treatment). By performing such a treatment, the adhesion between the polyester-based resin substrate and the PVA-based resin layer can be improved.
- a surface treatment for example, corona treatment
- the polarizing plate of the present invention comprises a polyester resin substrate having an easy-adhesion layer formed on the surface, and a polarizer laminated on the polyester resin substrate via the easy-adhesion layer.
- the thickness of the polarizer is 10 ⁇ m or less.
- the easy adhesion layer is as described in the above section A-2, and the formation method of the easy adhesion layer is as described in the above section 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 side opposite to the easily adhesive layer of the polarizer.
- the polarizer is substantially a PVA resin layer in which iodine is adsorbed and oriented.
- the thickness of the polarizer is 10 ⁇ m or less, preferably 7.5 ⁇ m or less, and more preferably 5 ⁇ m or less.
- the thickness of the polarizer is preferably 0.5 ⁇ m or more, more preferably 1.5 ⁇ m or more. If the thickness is too small, the optical properties of the resulting polarizer may be reduced.
- the polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm.
- the single transmittance of the polarizer is preferably 40.0% or more, more preferably 41.0% or more, and further preferably 42.0% or more.
- the polarization degree of the polarizer is preferably 99.8% or more, more preferably 99.9% or more, and further preferably 99.95% or more.
- the PVA resin forming the PVA resin layer is as described in the section A-3.
- a polarizing plate can have a protective film on the opposite side to the easily bonding layer of a polarizer.
- the material for forming the protective film include (meth) acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins, olefin resins such as polypropylene, and ester resins such as polyethylene terephthalate resins. Examples thereof include resins, polyamide resins, polycarbonate resins, and copolymer resins thereof.
- the thickness of the protective film is preferably 10 ⁇ m to 100 ⁇ m.
- the manufacturing method of the polarizing plate of this invention includes making a PVA-type resin layer into a polarizer by dye
- the laminate may be subjected to various processes such as a dyeing process, a stretching process, an insolubilizing process, a crosslinking process, a washing process, and a drying process. These processes can be appropriately selected depending on the purpose. Further, the processing order, the processing timing, the number of processings, and the like can be set as appropriate. Each process will be described below.
- the stretching method for air-assisted stretching may be fixed-end stretching (for example, stretching using a tenter stretching machine), or free-end stretching (for example, uniaxial stretching through a laminate between rolls having different peripheral speeds).
- stretching process includes the hot roll extending process extended
- the aerial stretching process typically includes a zone stretching process and a hot roll stretching process.
- stretching process and a hot roll extending process is not limited, A zone extending process may be performed previously and a hot roll extending process may be performed previously. The zone stretching step may be omitted. In one embodiment, a zone extending process and a hot roll extending process are performed in this order.
- the stretching temperature of the laminate can be set to any appropriate value according to the forming material of the resin base material.
- the stretching temperature in the air stretching treatment is preferably not less than the glass transition temperature (Tg) of the resin substrate, more preferably glass transition temperature (Tg) of the resin substrate + 10 ° C. or more, particularly preferably Tg + 15 ° C. or more.
- the upper limit of the stretching temperature of the laminate is preferably 170 ° C.
- the draw ratio of the laminate can be set to any appropriate value according to the forming material of the resin base material.
- the draw ratio in the air drawing treatment is preferably 1.5 times or more and 3.0 times or less.
- the insolubilization treatment is typically performed by immersing a PVA resin layer in an aqueous boric acid solution. By performing the insolubilization treatment, water resistance can be imparted to the PVA resin layer.
- the concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water.
- the liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C. to 50 ° C.
- the insolubilization treatment is performed before the underwater stretching or dyeing treatment.
- the dyeing process is typically performed by dyeing the PVA resin layer with a dichroic substance. Preferably, it is performed by adsorbing a dichroic substance to the PVA resin layer.
- the adsorption method include a method of immersing a PVA resin layer (laminated body) in a staining solution containing a dichroic substance, a method of applying the staining solution to a PVA resin layer, and a method of applying the staining solution to a PVA system.
- Examples include a method of spraying on the resin layer. Preferably, it is a method of immersing the laminate in the staining solution. This is because the dichroic substance can be adsorbed well.
- the dichroic substance examples include iodine and organic dyes. These may be used alone or in combination of two or more.
- the dichroic material is preferably iodine.
- the staining solution is preferably an iodine aqueous solution.
- the blending amount of iodine is preferably 0.05 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 add an iodide to the aqueous 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. Etc. Among these, potassium iodide is preferable.
- the blending amount of iodide is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of water.
- the liquid temperature during staining of the staining liquid is preferably 20 ° C. to 40 ° C.
- the immersion time is preferably 10 seconds to 300 seconds. Under such conditions, the dichroic substance can be sufficiently adsorbed to the PVA resin layer.
- the staining conditions can be set so that the polarization degree or single transmittance of the finally obtained polarizer is within a predetermined range. In one embodiment, immersion time is set so that the polarization degree of the polarizer obtained may be 99.98% or more. In another embodiment, the immersion time is set so that the single transmittance of the obtained polarizer is about 40%.
- the crosslinking treatment is typically performed by immersing a PVA resin layer (laminated body) in an aqueous boric acid solution. By performing the crosslinking treatment, water resistance can be imparted to the PVA resin layer.
- the concentration of the boric acid aqueous solution is preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.
- blend an iodide it is preferable to mix
- the blending amount of iodide is preferably 1 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 is preferably 20 ° C. to 60 ° C.
- the crosslinking treatment is performed before the underwater stretching treatment. In a preferred embodiment, an air stretching process, a dyeing process, and a crosslinking process are performed in this order.
- Underwater stretching treatment Any appropriate method can be adopted as a stretching method in the underwater stretching treatment. Specifically, it may be fixed end stretching (for example, a method using a tenter stretching machine) or free end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Moreover, simultaneous biaxial stretching (for example, a method using a simultaneous biaxial stretching machine) or sequential biaxial stretching may be used.
- the stretching of the laminate may be performed in one stage or in multiple stages. When performing in multiple stages, the draw ratio (maximum draw ratio) of the laminate is the product of the draw ratios of each stage.
- any appropriate direction can be selected as the stretching direction of the laminate. In one embodiment, it extends
- the stretching temperature of the laminate can be set to any appropriate value depending on the resin base material, the stretching method, and the like.
- 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
- the glass transition temperature (Tg) of the resin base material is preferably 60 ° C. or higher in relation to the formation of the PVA-based resin layer. In this case, when the stretching temperature is lower than 40 ° C., there is a possibility that the stretching cannot be satisfactorily performed even in consideration of plasticization of the resin base material with water. 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 possibility that excellent optical properties cannot be obtained.
- the stretching in water is preferably performed by immersing the laminate in a boric acid aqueous solution (stretching in boric acid in water).
- a boric acid aqueous solution as the stretching bath, the PVA resin layer can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water.
- boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with a PVA resin by hydrogen bonding.
- rigidity and water resistance can be imparted to the PVA-based resin layer, the film can be stretched satisfactorily, and a polarizer having excellent optical characteristics (for example, polarization degree) can be produced.
- 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 to 10 parts by weight with respect to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizer having higher characteristics can be produced.
- an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.
- an iodide is preferably added to the stretching bath (boric acid aqueous solution).
- 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.
- the concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 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, for example, by employing an underwater drawing method (boric acid underwater drawing).
- the “maximum stretch ratio” refers to a stretch ratio immediately before the laminate is ruptured. Separately, a stretch ratio at which the laminate is ruptured is confirmed, and a value that is 0.2 lower than that value. .
- the underwater stretching process is performed after the dyeing process.
- the cleaning process is typically performed by immersing the PVA resin layer in an aqueous potassium iodide solution.
- the drying temperature in the drying treatment is preferably 30 ° C to 100 ° C.
- Polyester-based resin base material is an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 ⁇ m) having a water absorption of 0.75% and Tg of 75 ° C. It was.
- One side of the polyester-based resin base material is subjected to corona treatment, and this corona treatment surface is subjected to acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Gosefimer Z200”, polymerization degree 1200, saponification degree 99.
- PVA acetoacetyl-modified PVA
- the mixed liquid mixture solid content concentration 4.0%) was applied so that the thickness after drying was 2000 nm, and dried at 60 ° C. for 3 minutes to form an easy adhesion layer.
- the solid content mixing ratio of acetoacetyl-modified PVA and modified polyolefin in the mixed solution was 50:50.
- the surface of the easy-adhesion 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) were applied to the corona-treated surface.
- An aqueous solution containing 6%, a saponification degree of 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Gosefimer Z200”) at a ratio of 9: 1 was applied and dried at 25 ° C. to obtain a thickness.
- An 11 ⁇ m PVA resin layer was formed. Thus, a laminate was produced. 2.
- the obtained laminate was uniaxially stretched free end in a longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (air-assisted stretching).
- the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).
- an insolubilization bath a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water
- insolubilization treatment a dyeing bath having a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the obtained polarizing plate had a predetermined transmittance.
- iodine 0.2 parts by weight was blended with 100 parts by weight of water, and immersed in an aqueous iodine solution obtained by blending 1.0 part by weight of potassium iodide (dyeing treatment). . Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking treatment).
- the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C.
- a boric acid aqueous solution an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water
- a cleaning bath an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water
- Example 2 A polarizing plate was obtained in the same manner as in Example 1, except that the solid content ratio of acetoacetyl-modified PVA and 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 ratio of acetoacetyl-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 mixing ratio of the solid content of acetoacetyl-modified PVA and modified polyolefin in the mixed solution was 10:90.
- 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 (Gosefimer Z200) was used for forming the easy adhesion layer.
- acetoacetyl-modified PVA Gosefimer Z200
- ⁇ Comparative example 2> A polarizing plate was obtained in the same manner as in Example 1 except that the solid content ratio of acetoacetyl-modified PVA and modified polyolefin in the mixed solution was 90:10.
- Example 3 A polarizing plate was obtained in the same manner as in Example 1 except that the mixing ratio of the solid content of acetoacetyl-modified PVA and modified polyolefin in the mixed solution was 70:30.
- ⁇ Comparative example 4> When forming an easy-adhesion layer, a modified polyolefin resin aqueous dispersion (trade name “Arrow Base SE1030N”, manufactured by Unitika Ltd., solid content concentration 22%) and a mixed solution (solid content concentration 4.0%) mixed with pure water are used. A polarizing plate was obtained in the same manner as in Example 3 except that it was used.
- This measurement sample was cut with a cutter knife between the polarizer and the polyester resin substrate, the polyester resin substrate was raised to form an angle of 90 ° with respect to the polarizer surface, and the peeling speed was 3000 mm.
- the force (N / 15 mm) required for peeling at / min was measured by the above “VPA-2”.
- the water contact angle of the easy adhesion layer immediately after dropping water is 70 ° or more, and the water contact angle of the easy adhesion layer is 2 ° or more after 30 seconds have passed since the dropping.
- the decreasing polarizing plates of Examples 1 to 4 were excellent in adhesion between the polarizer and the polyester resin substrate.
- the laminate of the present invention is suitably used for producing a polarizing plate.
- the polarizing plate of the present invention is suitably used for image display devices such as liquid crystal display devices and organic EL display devices.
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Abstract
Description
1つの実施形態においては、易接着層が、ポリビニルアルコール系成分とポリオレフィン系成分とを含む。
1つの実施形態においては、上記ポリビニルアルコール系成分と上記ポリオレフィン系成分との配合比が、10:90~50:50である。
本発明の別の局面によれば、積層体の製造方法が提供される。この積層体の製造方法は、ポリエステル系樹脂基材の表面に易接着層を形成することと、上記易接着層の表面にポリビニルアルコール系樹脂層を形成することと、を含み、上記易接着層の水接触角は、上記易接着層に水を滴下した直後に70°以上であり、該滴下から30秒が経過することにより2°以上減少する。
本発明の別の局面によれば、偏光板の製造方法が提供される。この偏光板の製造方法は、上記積層体を染色および延伸することにより上記ポリビニルアルコール系樹脂層を偏光子とすることを含む。
本発明の別の局面によれば、偏光板が提供される。この偏光板は、表面に易接着層が形成されたポリエステル系樹脂基材と、上記易接着層を介して上記ポリエステル系樹脂基材に積層された偏光子と、を有し、上記偏光子の厚みが10μm以下であり、上記易接着層の水接触角は、上記易接着層に水を滴下した直後に70°以上であり、該滴下から30秒が経過することにより2°以上減少する。
図1は、本発明の1つの実施形態による積層体の概略断面図である。積層体100は、表面に易接着層20が形成されたポリエステル系樹脂基材10と、易接着層20を介してポリエステル系樹脂基材10に積層されたポリビニルアルコール(PVA)系樹脂層30と、を有する。易接着層20の水接触角は、易接着層20に水を滴下した直後に70°以上であり、滴下から30秒が経過することにより2°以上減少する。上記水接触角の経時変化(減少)は、代表的には、易接着層に水を滴下した直後の水接触角(θ1)と、滴下から30秒後の水接触角(θ2)とを測定し、θ2からθ1を差し引くことにより得られる。易接着層に水を滴下した直後の水接触角は、代表的には、滴下から1秒後に測定される水接触角である。1つの実施形態においては、易接着層20はポリビニルアルコール系成分とポリオレフィン系成分とを含む。この場合、ポリビニルアルコール系成分とポリオレフィン系成分との配合比は、好ましくは10:90~50:50である。これにより、ポリエステル系樹脂基材とPVA系樹脂層との密着性に優れる積層体が得られ得る。1つの実施形態においては、上記積層体は偏光板の作製に用いられ得る。偏光板の製造方法は、D項で後述するように、積層体を染色および延伸することによりPVA系樹脂層を偏光子とすることを含む。
ポリエステル系樹脂基材の形成材料としては、例えば、ポリエチレンテレフタレート(PET)、ポリブチレンテレフタレート(PBT)、ポリエチレンナフタレート(PEN)、イソフタル酸、シクロヘキサン環等を含む脂環式のジカルボン酸または脂環式のジオール等を含む共重合PET(PET-G)、その他ポリエステル、および、これらの共重合体やブレンド体等を用いることができる。なかでも、非晶質の(結晶化していない)PETまたは共重合PETを用いることが好ましい。これらの樹脂によれば、未延伸状態では非晶で高倍率延伸に適した優れた延伸性を有し、延伸、加熱により結晶化することで、耐熱性および寸法安定性を付与できる。さらに、未延伸の状態でPVA系樹脂を塗布、乾燥することが可能な程度の耐熱性を確保できる。
上記のとおり、易接着層の水接触角は、水を滴下した直後に70°以上であり、滴下から30秒が経過することにより2°以上減少する。水を滴下した直後の易接着層の水接触角は、好ましくは75°~85°である。滴下から30秒が経過することによる水接触角の経時変化は、好ましくは-2°(2°の減少)~-5°(5°の減少)である。水を滴下した直後の易接着層の水接触角が70°以上であり、かつ、滴下から30秒が経過することによる水接触角の経時変化(減少)が2°以上であることにより、易接着層の上にPVA系樹脂層を形成した場合に易接着層形成用組成物がPVA系樹脂層に溶出し得る。具体的には、上記水接触角の経時変化が-2°~-5°であることにより、易接着層の上にPVA系樹脂の塗布層を形成したときに、易接着層形成用組成物の10体積%~34体積%程度がPVA系樹脂の塗布層に溶出し得る。これにより、ポリエステル系樹脂基材とPVA系樹脂層との密着性が向上し得る。
上記PVA系樹脂層を形成するPVA系樹脂としては、任意の適切な樹脂が採用され得る。例えば、ポリビニルアルコール、エチレン-ビニルアルコール共重合体が挙げられる。ポリビニルアルコールは、ポリ酢酸ビニルをケン化することにより得られる。エチレン-ビニルアルコール共重合体は、エチレン-酢酸ビニル共重合体をケン化することにより得られる。PVA系樹脂のケン化度は、通常85モル%~100モル%であり、好ましくは95.0モル%~99.95モル%、さらに好ましくは99.0モル%~99.93モル%である。ケン化度は、JIS K 6726-1994に準じて求めることができる。このようなケン化度のPVA系樹脂を用いることによって、耐久性に優れた偏光子が得られ得る。ケン化度が高すぎる場合には、ゲル化してしまうおそれがある。
本発明の積層体は、任意の適切な方法により製造され得る。1つの実施形態においては、上記積層体は、ポリエステル系樹脂基材の表面に易接着層を形成することと、易接着層の表面にPVA系樹脂層を形成することと、を含む方法により製造される。
ポリエステル系樹脂基材の表面に易接着層を形成する方法としては、任意の適切な方法が採用され得る。代表的には、ポリエステル系樹脂基材の表面に、易接着層形成用組成物を塗布し、乾燥することにより、易接着層を形成する。易接着層形成用組成物において、ポリビニルアルコール系成分とポリオレフィン系成分との配合比(前者:後者(固形分))は、好ましくは10:90~50:50、さらに好ましくは20:80~50:50である。
易接着層の表面にPVA系樹脂層を形成する方法としては、任意の適切な方法が採用され得る。好ましくは、ポリエステル系樹脂基材に形成された易接着層の表面に、PVA系樹脂を含む塗布液を塗布し、乾燥することにより、PVA系樹脂層を形成する。
本発明の偏光板は、表面に易接着層が形成されたポリエステル系樹脂基材と、易接着層を介してポリエステル系樹脂基材に積層された偏光子と、を有する。偏光子の厚みは10μm以下である。易接着層については上記A-2項で説明したとおりであり、易接着層の形成方法は上記B-1項で説明したとおりである。これにより、ポリエステル系樹脂基材と偏光子との密着性に優れる偏光板が得られ得る。偏光板は、偏光子の易接着層とは反対側に保護フィルムを有していてもよい。
偏光子は、実質的には、ヨウ素が吸着配向されたPVA系樹脂層である。偏光子の厚みは、上記のとおり10μm以下であり、好ましくは7.5μm以下であり、より好ましくは5μm以下である。一方、偏光子の厚みは、好ましくは0.5μm以上、より好ましくは1.5μm以上である。厚みが薄すぎると得られる偏光子の光学特性が低下するおそれがある。偏光子は、好ましくは、波長380nm~780nmのいずれかの波長で吸収二色性を示す。偏光子の単体透過率は、好ましくは40.0%以上、より好ましくは41.0%以上、さらに好ましくは42.0%以上である。偏光子の偏光度は、好ましくは99.8%以上、より好ましくは99.9%以上、さらに好ましくは99.95%以上である。
偏光板は、上記のとおり、偏光子の易接着層とは反対側に保護フィルムを有し得る。上記保護フィルムの形成材料としては、例えば、(メタ)アクリル系樹脂、ジアセチルセルロース、トリアセチルセルロース等のセルロース系樹脂、シクロオレフィン系樹脂、ポリプロピレン等のオレフィン系樹脂、ポリエチレンテレフタレート系樹脂等のエステル系樹脂、ポリアミド系樹脂、ポリカーボネート系樹脂、これらの共重合体樹脂等が挙げられる。保護フィルムの厚みは、好ましくは10μm~100μmである。
本発明の偏光板の製造方法は、上記A項で説明した積層体を染色および延伸することによりPVA系樹脂層を偏光子とすることを含む。1つの実施形態においては、積層体に、染色処理、延伸処理、不溶化処理、架橋処理、洗浄処理、乾燥処理などの各種処理を施すことを含み得る。これらの処理は、目的に応じて適宜選択され得る。また、処理順序、処理のタイミング、処理回数等、適宜設定され得る。以下、各々の処理について説明する。
空中補助延伸の延伸方法は、固定端延伸(たとえば、テンター延伸機を用いて延伸する方法)でもよいし、自由端延伸(たとえば、周速の異なるロール間に積層体を通して一軸延伸する方法)でもよい。一つの実施形態においては、空中延伸処理は、上記積層体をその長手方向に搬送しながら、熱ロール間の周速差により延伸する熱ロール延伸工程を含む。空中延伸処理は、代表的には、ゾーン延伸工程と熱ロール延伸工程とを含む。なお、ゾーン延伸工程と熱ロール延伸工程の順序は限定されず、ゾーン延伸工程が先に行われてもよく、熱ロール延伸工程が先に行われてもよい。ゾーン延伸工程は省略されてもよい。1つの実施形態においては、ゾーン延伸工程および熱ロール延伸工程がこの順に行われる。
上記不溶化処理は、代表的には、ホウ酸水溶液にPVA系樹脂層を浸漬することにより行う。不溶化処理を施すことにより、PVA系樹脂層に耐水性を付与することができる。当該ホウ酸水溶液の濃度は、水100重量部に対して、好ましくは1重量部~4重量部である。不溶化浴(ホウ酸水溶液)の液温は、好ましくは20℃~50℃である。好ましくは、不溶化処理は、水中延伸や染色処理の前に行う。
上記染色処理は、代表的には、PVA系樹脂層を二色性物質で染色することにより行う。好ましくは、PVA系樹脂層に二色性物質を吸着させることにより行う。当該吸着方法としては、例えば、二色性物質を含む染色液にPVA系樹脂層(積層体)を浸漬させる方法、PVA系樹脂層に当該染色液を塗工する方法、当該染色液をPVA系樹脂層に噴霧する方法等が挙げられる。好ましくは、染色液に積層体を浸漬させる方法である。二色性物質が良好に吸着し得るからである。
上記架橋処理は、代表的には、ホウ酸水溶液にPVA系樹脂層(積層体)を浸漬することにより行う。架橋処理を施すことにより、PVA系樹脂層に耐水性を付与することができる。当該ホウ酸水溶液の濃度は、水100重量部に対して、好ましくは1重量部~5重量部である。また、上記染色処理後に架橋処理を行う場合、さらに、ヨウ化物を配合することが好ましい。ヨウ化物を配合することにより、PVA系樹脂層に吸着させたヨウ素の溶出を抑制することができる。ヨウ化物の配合量は、水100重量部に対して、好ましくは1重量部~5重量部である。ヨウ化物の具体例は、上述のとおりである。架橋浴(ホウ酸水溶液)の液温は、好ましくは20℃~60℃である。好ましくは、架橋処理は水中延伸処理の前に行う。好ましい実施形態においては、空中延伸処理、染色処理および架橋処理をこの順で行う。
水中延伸処理における延伸方法としては、任意の適切な方法を採用することができる。具体的には、固定端延伸(例えば、テンター延伸機を用いる方法)でもよいし、自由端延伸(例えば、周速の異なるロール間に積層体を通して一軸延伸する方法)でもよい。また、同時二軸延伸(例えば、同時二軸延伸機を用いる方法)でもよいし、逐次二軸延伸でもよい。積層体の延伸は、一段階で行ってもよいし、多段階で行ってもよい。多段階で行う場合、積層体の延伸倍率(最大延伸倍率)は、各段階の延伸倍率の積である。
上記洗浄処理は、代表的には、ヨウ化カリウム水溶液にPVA系樹脂層を浸漬させることにより行う。
乾燥処理における乾燥温度は、好ましくは30℃~100℃である。
(1)厚み
デジタルマイクロメーター(アンリツ社製、製品名「KC-351C」)を用いて測定した。
(2)水接触角
易接着層の水接触角について、協和界面科学株式会社製の自動接触角計(DM500)を使って測定し、FAMAS(接触角測定アドインソフトウェア)を使って解析した。測定用の水は、超純水を用い、液滴は0.5μlとした。
ポリエステル系樹脂基材の表面に易接着層を形成した後、易接着層に水を滴下してから1秒経過後の水接触角(θ1)と、滴下から30秒後の水接触角(θ2)とを測定し、30秒経過による水接触角の経時変化(θ2-θ1)を算出した。
1.積層体の作製
ポリエステル系樹脂基材として、長尺状で、吸水率0.75%、Tg75℃の非晶質のイソフタル酸共重合ポリエチレンテレフタレート(IPA共重合PET)フィルム(厚み:100μm)を用いた。
ポリエステル系樹脂基材の片面に、コロナ処理を施し、このコロナ処理面に、アセトアセチル変性PVA(日本合成化学工業社製、商品名「ゴーセファイマーZ200」、重合度1200、ケン化度99.0モル%以上、アセトアセチル変性度4.6%)の4.0%水溶液と変性ポリオレフィン樹脂水性分散体(ユニチカ社製、商品名「アローベースSE1030N」、固形分濃度22%)と純水を混合した混合液(固形分濃度4.0%)を、乾燥後の厚みが2000nmになるように塗布し、60℃で3分間乾燥し、易接着層を形成した。ここで、混合液におけるアセトアセチル変性PVAと変性ポリオレフィンとの固形分配合比は50:50であった。
次いで、易接着層表面に、コロナ処理を施し、このコロナ処理面に、ポリビニルアルコール(重合度4200、ケン化度99.2モル%)およびアセトアセチル変性PVA(重合度1200、アセトアセチル変性度4.6%、ケン化度99.0モル%以上、日本合成化学工業社製、商品名「ゴーセファイマーZ200」)を9:1の比で含む水溶液を25℃で塗布および乾燥して、厚み11μmのPVA系樹脂層を形成した。こうして、積層体を作製した。
2.偏光板の作製
得られた積層体を、120℃のオーブン内で周速の異なるロール間で縦方向(長手方向)に2.0倍に自由端一軸延伸した(空中補助延伸)。
次いで、積層体を、液温30℃の不溶化浴(水100重量部に対して、ホウ酸を4重量部配合して得られたホウ酸水溶液)に30秒間浸漬させた(不溶化処理)。
次いで、液温30℃の染色浴に、得られる偏光板が所定の透過率となるようにヨウ素濃度、浸漬時間を調整しながら浸漬させた。本実施例では、水100重量部に対して、ヨウ素を0.2重量部配合し、ヨウ化カリウムを1.0重量部配合して得られたヨウ素水溶液に60秒間浸漬させた(染色処理)。
次いで、液温30℃の架橋浴(水100重量部に対して、ヨウ化カリウムを3重量部配合し、ホウ酸を3重量部配合して得られたホウ酸水溶液)に30秒間浸漬させた(架橋処理)。
その後、積層体を、液温70℃のホウ酸水溶液(水100重量部に対して、ホウ酸を4重量部配合し、ヨウ化カリウムを5重量部配合して得られた水溶液)に浸漬させながら、周速の異なるロール間で縦方向(長手方向)に総延伸倍率が5.5倍となるように一軸延伸を行った(水中延伸)。
その後、積層体を液温30℃の洗浄浴(水100重量部に対して、ヨウ化カリウムを4重量部配合して得られた水溶液)に浸漬させた(洗浄処理)。
こうして、厚み30μmのポリエステル系樹脂基材の片側に厚み5μmの偏光子が形成された偏光板を得た。
混合液におけるアセトアセチル変性PVAと変性ポリオレフィンとの固形分配合比を30:70としたこと以外は実施例1と同様にして、偏光板を得た。
混合液におけるアセトアセチル変性PVAと変性ポリオレフィンとの固形分配合比を20:80としたこと以外は実施例1と同様にして、偏光板を得た。
混合液におけるアセトアセチル変性PVAと変性ポリオレフィンとの固形分配合比を10:90としたこと以外は実施例1と同様にして、偏光板を得た。
易接着層の形成に際し、アセトアセチル変性PVA(ゴーセファイマーZ200)の4.0%水溶液を用いたこと以外は実施例1と同様にして、偏光板を得た。
混合液におけるアセトアセチル変性PVAと変性ポリオレフィンとの固形分配合比を90:10としたこと以外は実施例1と同様にして、偏光板を得た。
混合液におけるアセトアセチル変性PVAと変性ポリオレフィンとの固形分配合比を70:30としたこと以外は実施例1と同様にして、偏光板を得た。
易接着層の形成に際し、変性ポリオレフィン樹脂水性分散体(ユニチカ社製、商品名「アローベースSE1030N」、固形分濃度22%)と純水を混合した混合液(固形分濃度4.0%)を用いたこと以外は実施例3と同様にして、偏光板を得た。
上記実施例および比較例について、PVA剥離力および基材剥離力を測定することにより、密着性を評価した。評価結果を表1にまとめる。PVA剥離力および基材剥離力の測定方法は、以下のとおりである。
(PVA剥離力)
ガラス板に、得られた偏光板をポリエステル系樹脂基材面側に粘着剤を塗布して貼り合わせ、偏光子面に補強用のポリイミドテープ(日東電工(株)製、ポリイミド粘着テープNo.360A)を貼り合わせて、測定用サンプルを作製した。この測定用サンプルの偏光子とポリエステル系樹脂基材との間にカッターナイフで切込みを入れ、偏光子および補強用のポリイミドテープをポリエステル系樹脂基材面に対して90°の角度をなすように立ち上げ、剥離速度3000mm/minで剥離する際に要する力(N/15mm)を角度自在タイプ粘着・皮膜剥離解析装置「VPA-2」(共和界面化学株式会社製)により測定した。
(基材剥離力)
ガラス板に、得られた偏光板を偏光子面側に粘着剤を塗布して貼り合わせて、測定用サンプルを作製した。この測定用サンプルの偏光子とポリエステル系樹脂基材との間にカッターナイフで切込みを入れ、ポリエステル系樹脂基材を偏光子面に対して90°の角度をなすように立ち上げ、剥離速度3000mm/minで剥離する際に要する力(N/15mm)を上記「VPA-2」により測定した。
20 易接着層
30 ポリビニルアルコール系樹脂層
100 積層体
Claims (6)
- 表面に易接着層が形成されたポリエステル系樹脂基材と、前記易接着層を介して前記ポリエステル系樹脂基材に積層されたポリビニルアルコール系樹脂層と、を有し、
前記易接着層の水接触角は、前記易接着層に水を滴下した直後に70°以上であり、該滴下から30秒が経過することにより2°以上減少する、積層体。 - 前記易接着層が、ポリビニルアルコール系成分とポリオレフィン系成分とを含む、請求項1に記載の積層体。
- 前記ポリビニルアルコール系成分と前記ポリオレフィン系成分との配合比が、10:90~50:50である、請求項2に記載の積層体。
- ポリエステル系樹脂基材の表面に易接着層を形成することと、
前記易接着層の表面にポリビニルアルコール系樹脂層を形成することと、を含み、
前記易接着層の水接触角は、前記易接着層に水を滴下した直後に70°以上であり、該滴下から30秒が経過することにより2°以上減少する、積層体の製造方法。 - 請求項1から3のいずれかに記載の積層体を染色および延伸することにより前記ポリビニルアルコール系樹脂層を偏光子とすることを含む、偏光板の製造方法。
- 表面に易接着層が形成されたポリエステル系樹脂基材と、前記易接着層を介して前記ポリエステル系樹脂基材に積層された偏光子と、を有し、
前記偏光子の厚みが10μm以下であり、
前記易接着層の水接触角は、前記易接着層に水を滴下した直後に70°以上であり、該滴下から30秒が経過することにより2°以上減少する、偏光板。
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