TWI757513B - Laminate and method for producing the laminate - Google Patents

Abstract

The present invention provides a laminate having excellent adhesion and suppressing both peeling from the resin substrate side and peeling from the polyvinyl alcohol-based resin layer side. The laminate of the present invention has a resin substrate, a primer layer, and a polyvinyl alcohol-based resin layer in this order; wherein, the primer layer and the polyvinyl alcohol-based resin layer are formed by the following methods: The primer coating layer and the polyvinyl alcohol-based resin coating layer are sequentially arranged on the resin substrate, so that 5% to 70 volume % of the primer coating layer is dissolved into the polyvinyl alcohol-based resin coating layer. The primer coating layer contains two or more resin components and the resin component contains a polyvinyl alcohol-based component, and the blending ratio of the polyvinyl alcohol-based component in the resin component of the primer coating layer is: 5%~50%.

Description

Laminate and method for producing the laminate

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

Background of the Invention

There is a document that proposes a method of producing a polarizing film by forming a polyvinyl alcohol-based resin layer on a resin substrate, and dyeing and extending the laminate (for example, Patent Document 1). By this method, a polarizing film having a relatively thin thickness can be obtained, and it is therefore attracting attention, for example, by contributing to the reduction in thickness of an image display device.

The said polarizing film can be used in the state laminated|stacked on the said resin base material as it is. In this embodiment, it is required that the polyvinyl alcohol-based resin layer (polarizing film) and the resin substrate must have sufficient adhesion. The specific requirements are: the polyvinyl alcohol-based resin layer will not be peeled off from the resin substrate during the manufacture of the polarizing film (such as stretching and conveying), the polarizing film will not be peeled off from the resin substrate during rework, and the polyvinyl alcohol-based resin layer will not be peeled off due to processing (such as punching). ) or the shock during use, resulting in embossing of the polarizing film or resin substrate, etc.

In order to improve the said adhesiveness, it is proposed to provide a primer layer containing a polyvinyl alcohol type material between a resin base material and a polyvinyl alcohol type resin layer (patent document 2). With this technique, peeling from the resin substrate side can be suppressed well, but peeling from the polyvinyl alcohol-based resin layer side cannot be sufficiently suppressed.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2000-338329

Patent Document 2: Japanese Patent No. 4950357

Summary of Invention

The present invention was made to solve the above-mentioned problems, and its main object is to provide a laminate having excellent adhesion and suppressing both peeling from the resin substrate side and peeling from the polyvinyl alcohol-based resin layer side.

According to the present invention, a laminated body is provided, and the laminated body has a resin base material, a primer layer and a polyvinyl alcohol-based resin layer in this order. The primer layer and the polyvinyl alcohol-based resin layer are formed by: in the primer coating layer and the polyvinyl alcohol-based resin coating layer sequentially provided on the resin substrate, the 5 to 70 volume % of the primer coating layer is eluted into the polyvinyl alcohol-based resin coating layer to form. In addition, the primer coating layer contains two or more resin components and the resin component contains a polyvinyl alcohol-based component, and the blending ratio of the polyvinyl alcohol-based component in the resin component in the primer coating layer is 5 weights %~50% by weight.

In one embodiment, the thickness of the undercoat layer is 0.2 μm˜2.0 μm .

In one embodiment, the polyvinyl alcohol-based component contains an acetylacetate group-modified polyvinyl alcohol.

In one Embodiment, the said primer coating layer contains the said polyvinyl alcohol-type component and a polyolefin-type component.

In one embodiment, the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component (polyvinyl alcohol-based component: polyolefin-based component) is 5:95 to 50:50 on a weight basis.

According to another aspect of the present invention, there is provided a method for producing a laminate, wherein the laminate has a resin substrate, an undercoat layer, and a polyvinyl alcohol-based resin layer in this order. The manufacturing method of the laminated body comprises the following steps: forming a primer coating layer on one side of a resin substrate, and forming a polyvinyl alcohol-based resin coating layer on the surface of the primer coating layer; and applying the primer coating 5% to 70% by volume of the layer is eluted into the polyvinyl alcohol-based resin, and the primer coating layer and the polyvinyl alcohol-based resin coating layer are respectively made into a primer layer and a polyvinyl alcohol-based resin layer. The primer coating layer contains two or more resin components and the resin component contains a polyvinyl alcohol-based component, and the blending ratio of the polyvinyl alcohol-based component in the resin component of the primer coating layer is 5% by weight to 50% by weight. weight%.

In one embodiment, the thickness of the undercoat layer is 0.2 μm˜2.0 μm .

In one embodiment, the polyvinyl alcohol-based component contains an acetylacetate group-modified polyvinyl alcohol.

In one Embodiment, the said primer coating layer contains the said polyvinyl alcohol-type component and a polyolefin-type component.

In one embodiment, the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component (polyvinyl alcohol-based component: polyolefin-based component) is 5:95 to 50:50 on a weight basis.

According to another aspect of the present invention, there is provided an optical laminate having a resin substrate, an undercoat layer and a polarizing film in this order. In this optical laminate, the polyvinyl alcohol-based resin layer of the laminate is a polarizing film in which a dichroic substance is adsorbed and aligned.

According to another aspect of the present invention, there is provided a method for producing an optical laminate, wherein the optical laminate has a resin substrate, an undercoat layer and a polarizing film in this order. The manufacturing method of the optical laminate comprises the steps of: producing a laminate having a resin substrate, an undercoat layer and a polyvinyl alcohol-based resin layer in this order by the above-mentioned manufacturing method of the laminate; and the polyvinyl alcohol-based resin The layer is dyed and stretched to make a polarizing film.

According to the present invention, by sequentially forming a resin substrate, a primer coating layer containing a polyvinyl alcohol-based component, and a polyvinyl alcohol-based resin coating layer, and allowing a part of the primer coating layer to dissolve at a predetermined elution rate. The polyvinyl alcohol-based resin coating layer is eluted, and a laminate with excellent adhesion can be obtained.

FIG. 1 is an SEM observation photograph of a cross-section (a) of a primer coating layer and a cross-section (b) of the primer layer at the time of producing the laminate of the reference example.

Form for carrying out the invention

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

A. Manufacturing method of laminated body

The present invention provides a method for manufacturing a laminated body, and the laminated body is sequentially It has a resin base material, an undercoat layer, and a polyvinyl alcohol-based resin (hereinafter sometimes referred to as "PVA-based resin") layer. The manufacturing method of the laminated body of the present invention comprises the following steps: forming a primer coating layer on one side of a resin substrate, and forming a PVA-based resin coating layer on the surface of the primer coating layer; and applying the primer coating 5% to 70% by volume of the layer is eluted into the PVA-based resin coating layer, and the primer coating layer and the PVA-based resin coating layer are respectively made into a primer layer and a PVA-based resin layer.

A-1. Forming a primer coating layer

The primer coating layer is typically formed by applying the primer layer forming composition to one side of the resin substrate.

Arbitrary and appropriate materials can be used for the constituent material of the above-mentioned resin base material. For example, ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins, olefin-based resins such as polypropylene, (meth)acrylic-based resins, polyamide-based resins, polycarbonate-based resins, Its copolymer resin and the like. Preferably, a polyethylene terephthalate-based resin can be used. Among them, amorphous polyethylene terephthalate-based resins are particularly preferably used. Specific examples of the amorphous polyethylene terephthalate-based resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, or a copolymer further containing cyclohexanedimethanol as glycol.

The glass transition temperature (Tg) of the resin substrate is preferably 170°C or lower. The use of the resin base material can suppress crystallization of the PVA-based resin layer in the production of an optical laminate to be described later, and at the same time, sufficiently ensure extensibility. Considering that the resin substrate can be plasticized with water and the water extension can be smoothly carried out, More preferably, it is 120 degrees C or less. In one embodiment, the glass transition temperature of the resin substrate is preferably 60°C or higher. By using the resin substrate, inconveniences such as deformation of the resin substrate (for example, unevenness, slump, wrinkles, etc.) can be prevented when coating and drying a coating liquid containing a PVA-based resin described later. In addition, the laminated body can be stretched at a suitable temperature (for example, about 60° C. to 70° C.). In another embodiment, the glass transition temperature may be lower than 60° C. as long as the resin substrate is not deformed when the coating liquid containing the PVA-based resin is applied and dried. In addition, glass transition temperature (Tg) is the value calculated|required based on JISK7121.

In one embodiment, the water absorption rate of the resin substrate is preferably 0.2% or more, more preferably 0.3% or more. Such resin substrates absorb water, and water acts as a plasticizer for plasticization. As a result, the elongation stress can be greatly reduced in water elongation, and the elongation is excellent. On the other hand, the water absorption rate of the resin base material is preferably 3.0% or less, more preferably 1.0% or less. By using such a resin base material, the dimensional stability of the resin base material during manufacture of the optical laminate can be prevented from being remarkably reduced, and the resulting optical laminate can be prevented from deteriorating in appearance. It can prevent the PVA-based resin layer from being broken or peeled off from the resin substrate when extended in water. In addition, the water absorption rate is the value calculated|required based on JISK7209.

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

A surface modification treatment (eg, corona treatment, etc.) may be performed on the surface of the resin substrate in advance, and an easy-adhesion layer may also be formed. Adhesion can be further improved by these treatments.

The said composition for undercoat layer formation contains 2 or more types of resin components, and this resin component contains a polyvinyl alcohol-type component. Arbitrary and appropriate PVA-type resin can be used for this polyvinyl-alcohol-type component. Specifically, polyvinyl alcohol and modified polyvinyl alcohol may be mentioned. The modified polyvinyl alcohol is, for example, polyvinyl alcohol modified with an acetoxyacetyl group, a carboxylic acid group, an acryl group and/or a urethane group. Among these, PVA modified with an acetyl acetyl group is suitable. A polymer having at least a repeating unit represented by the following general formula (I) is preferably used for the acetylacetate group-modified PVA.

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

The average degree of polymerization of the acetylacetate group-modified PVA is preferably 1000-10000, more preferably 1200-5000. The degree of saponification of the acetylacetate-modified PVA should preferably be above 97 mol%. The pH of the 4 wt % aqueous solution of the acetylacetate group-modified PVA is preferably 3.5 to 5.5. In addition, the average polymerization degree and saponification degree can be calculated|required by JISK6726-1994.

Any appropriate resin component can be used as the other resin component that can be used together with the above-mentioned polyvinyl alcohol-based component. Specific examples include polyolefin-based components, polyester-based components, polyurethane-based components, and polypropylene-based components. components, styrene butadiene-based components, vinylidene chloride-based components, vinyl chloride-based components, and the like. By using the other resin components described above in combination with the polyvinyl alcohol-based component, a laminate having excellent adhesion can be obtained. Moreover, when a polyolefin type component is used, in addition to the effect of improving adhesiveness, the effect of improving an external appearance can also be acquired.

Arbitrary and appropriate polyolefin-type resin can be used for the said polyolefin-type component. The main component of the polyolefin-based resin, that is, the olefin component, includes, for example, olefin-based 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 preferably used, and ethylene is more preferably used.

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

The above-mentioned polyolefin-based resin preferably contains a carboxyl group and/or an acid anhydride group thereof. The above-mentioned polyolefin-based resin can be dispersed in water, so that the undercoat layer can be formed smoothly. Examples of the monomer components having the functional group include unsaturated carboxylic acids and their anhydrides, half esters of unsaturated dicarboxylic acids, and half amides. Specific examples of these include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, and crotonic acid.

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

Arbitrary and appropriate polyester-type resin can be used for the said polyester-type component. As a specific example of the said polyester-type resin, the copolymer which a dicarboxylic acid component and a glycol component are condensation-polymerized can be mentioned.

The dicarboxylic acid component constituting the polyester-based resin is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, and 3-tert-butylisophthalein. acid, oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, fumaric acid, maleic acid, maleic anhydride, iconic acid, icon Unsaturated aliphatic dicarboxylic acids such as acid anhydrides, citraconic acid, citraconic anhydride, dimer acids, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid Alicyclic dicarboxylic acids such as alkanedicarboxylic acid, tetrahydrophthalic acid, and anhydrides thereof.

The glycol component constituting the polyester resin is not particularly limited, and examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 2-methyl-1,3- Propylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethane-2-butanediol Alicyclic glycols such as propylene glycol and the like, and alicyclic glycols such as 1,4-cyclohexanedimethanol and 1,3-cyclobutanedimethanol.

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

In the above-mentioned composition for forming an undercoat layer, the blending ratio of the polyvinyl alcohol-based component and the other resin components (polyvinyl alcohol-based component: other resin components, solid content weight ratio) is 5:95 to 50:50, which is preferably 5:95 to 50:50. 20:80~50:50. When the blending ratio of the polyvinyl alcohol-based component is outside the above-mentioned range, there is a possibility that sufficient adhesiveness cannot be obtained. Specifically, the peeling force required when peeling the PVA-based resin layer from the resin base material may decrease and sufficient adhesion may not be obtained. On the other hand, when there are too few polyvinyl alcohol-type components, there exists a possibility that the peeling force required when peeling a resin base material from a PVA-type resin layer will fall, and sufficient adhesiveness may not be acquired.

The composition for forming an undercoat layer is preferably water-based. The composition for forming an undercoat layer may contain an organic solvent. Ethanol, isopropanol, etc. are mentioned as an organic solvent. The solid content concentration of the composition for forming an undercoat layer is preferably 1.0% by weight to 10% by weight.

唑啉、硼酸、三羥甲基三聚氰胺等羥甲基化合物、碳二亞胺、異氰酸酯化合物、環氧化合物等。底塗層形成用組成物之添加物摻混量可應目的等適當設定。舉例而言，相對於聚乙烯醇系成分與其他樹脂合計100重量份，交聯劑之摻混量宜為10重量份以下，更宜為0.01重量份~10重量份，又更宜為0.1重量份~5重量份。 Additives may also be blended in the composition for forming an undercoat layer. As an additive, a crosslinking agent etc. are mentioned, for example. Cross-linking agents such as

Methylol compounds such as oxazoline, boric acid, and trimethylol melamine, carbodiimides, isocyanate compounds, epoxy compounds, and the like. The blending amount of the additive of the composition for forming an undercoat layer can be appropriately set according to the purpose and the like. For example, the blending amount of the crosslinking agent is preferably 10 parts by weight or less, more preferably 0.01 parts by weight to 10 parts by weight, and more preferably 0.1 parts by weight relative to 100 parts by weight of the polyvinyl alcohol-based components and other resins in total. parts to 5 parts by weight.

Arbitrary and appropriate methods can be employ|adopted for the coating method of the composition for undercoat layer formation. For example, 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 blade coating method (comma coating method, etc.) etc. are mentioned.

The composition for forming an undercoat layer is preferably formed so that the thickness (thickness after drying) of the obtained undercoat layer is 0.3 μm to 3.0 μm , and preferably 0.5 μm to 2.0 μm . coating. If the thickness of the primer coating layer is too thin, sufficient adhesion may not be obtained. On the other hand, if the thickness of the primer coating layer is too thick, there is a possibility of occurrence of defects such as unevenness in the coating film obtained when forming the PVA-based resin coating layer described later.

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

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

The PVA-based resin coating layer is typically formed by coating the surface of the primer coating layer with a coating liquid containing a PVA-based resin. The surface of the primer coating layer used to coat the coating liquid containing the PVA-based resin can also be subjected to surface modification treatment (eg, corona treatment, etc.) in advance. Green adhesion can be further improved by these treatments.

As the coating liquid containing the above-mentioned PVA-based resin, a solution obtained by dissolving the PVA-based resin in a solvent can be used. Arbitrary and appropriate resin can be used for PVA-type resin. For example, polyvinyl alcohol and an ethylene-vinyl alcohol copolymer are mentioned. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymers can be obtained by saponifying ethylene-vinyl acetate copolymers. The degree of saponification of the PVA 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 is obtained according to JIS K 6726-1994. By using the PVA-based resin having the above degree of saponification, a polarizing film excellent in durability can be obtained. When the degree of saponification is too high, there is a risk of gelation.

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

Examples of the solvent include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyols such as trimethylolpropane, Amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among these, water is preferred. The concentration of the PVA-based resin in the coating solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. As long as it is the said resin concentration, a uniform coating film can be formed.

Additives can also be mixed in the coating liquid. Examples of additives include plasticizers, surfactants, and the like. As a plasticizer, polyhydric alcohols, such as ethylene glycol and glycerol, are mentioned, for example. As a surfactant, a nonionic surfactant is mentioned, for example. These can be used in order to further improve the uniformity, dyeability, and extensibility of the obtained PVA-based resin layer. Moreover, as an additive, an easily attachable component is mentioned. Adhesion can be further improved by using an easy-to-adhere ingredient. As the easy-to-attach component, modified PVA such as acetylacetate modified PVA can be used.

The coating method of the coating liquid can be the same as the coating method of the above-mentioned composition for forming an undercoat layer. After coating, the coating film can be dried. Drying can be carried out at room temperature (about 25°C) or by heating (for example, above 50°C).

A-3. Dissolution of primer coating layer to PVA-based resin coating layer

The dissolution of the primer coating layer into the PVA-based resin coating layer is caused by the high affinity between the polyvinyl alcohol-based components in the primer coating layer and the PVA-based resin in the PVA-based resin coating layer, and spontaneously occurs. It occurs simultaneously with the formation of the PVA-based resin coating layer (substantially, the coating of the above-mentioned coating liquid). In addition, the elution decreases or ends with a decrease in the driving force due to the concentration gradient of the polyvinyl alcohol-based component or the like. In the present invention, at the time point when the thickness of the primer coating layer stops decreasing and becomes a constant thickness along with the dissolution, it is deemed that the dissolution is completed, and the primer coating layer and the PVA-based resin are then coated with the primer layer. cloth layer It is a primer layer and a PVA resin layer.

Through the above-mentioned dissolution, 5% to 70% by volume of the primer coating layer, preferably 8% to 50% by volume, and more preferably 10% to 40% by volume of the primer coating layer is dissolved into the PVA-based resin coating layer. When the dissolution rate is within this range, a layered body having excellent adhesiveness can be obtained. The dissolution rate can be increased by, for example, increasing the blending ratio of the polyvinyl alcohol-based component in the composition for forming an undercoat layer.

The temperature environment during dissolution is not particularly limited, for example, it can be a temperature environment of 20°C to 100°C, preferably 30°C to 80°C, and more preferably 40°C to 70°C. In addition, the time required for elution (the time from the application of the coating liquid to the completion of elution) may be, for example, about 10 minutes after one application. This elution treatment may be combined with drying treatment of the coating film when the PVA-based resin coating layer is formed.

The thickness of the undercoat layer formed by the above-mentioned dissolution is preferably 0.2 μm to 2.0 μm , more preferably 0.3 μm to 1.8 μm . In addition, the thickness of the PVA-based resin layer is typically 3 μm to 40 μm , and 3 μm to 20 μm is suitable.

B. Laminate

The present invention also provides a laminate having a resin substrate, an undercoat layer, and a polyvinyl alcohol-based resin layer in this order. In the layered product, the primer layer and the polyvinyl alcohol-based resin layer are formed by applying the primer coating layer and the polyvinyl alcohol-based resin coating layer to the resin substrate in this order. In the layer, 5 to 70% by volume of the primer coating layer is eluted into the polyvinyl alcohol-based resin coating layer to form. Therefore, in one embodiment of the present invention, the laminated The PVA-based resin layer of the body contains the eluted component from the primer coating layer, and the primer layer can be formed from the remaining component after removing the eluted component from the primer coating layer. In addition, the primer coating layer contains two or more resin components and the resin component contains a polyvinyl alcohol-based component, and the blending ratio of the polyvinyl alcohol-based component in the resin component of the primer coating layer is 5% by weight~ 50% by weight. By having the above-described configuration, both peeling from the resin base material side and peeling from the polyvinyl alcohol-based resin layer side can be suppressed, and excellent adhesiveness can be obtained.

The layered product of the present invention can be typically produced by the production method described in the above-mentioned item A. Therefore, the formation materials and formation methods of each layer can be set according to the description in item A.

C. Manufacturing Method of Optical Laminate

The present invention also provides a method for producing an optical laminate having a resin substrate, an undercoat layer and a polarizing film in this order. The method for producing an optical laminate of the present invention comprises the steps of: producing a laminate having a resin substrate, an undercoat layer and a PVA-based resin layer in this order by the method for producing a laminate described in item A; and the PVA The resin layer is dyed and stretched to make a polarizing film. In addition to dyeing and stretching the PVA-based resin layer, a process of making the PVA-based resin layer into a polarizing film can be appropriately performed. The treatment for forming a polarizing film includes, for example, insolubilization treatment, cross-linking treatment, washing treatment, drying treatment, and the like. In addition, the number of times, order, etc. of these processes are not specifically limited.

(Dyeing treatment)

The above-mentioned dyeing treatment is performed by dyeing the PVA-based resin layer with a dichroic substance. It is preferable to carry out by making a dichroic substance adsorb|suck on the PVA-type resin layer. The adsorption method includes, for example, immersing a PVA-based resin layer (laminate) A method in a dyeing solution containing a dichroic substance, a method for applying the dyeing solution to a PVA-based resin layer, and a method for spraying the dyeing solution onto the PVA-based resin layer, and the like. Ideally, it is a method of immersing the PVA-based resin layer in a dyeing solution. Because it can adsorb dichroic substances well.

As said dichroic substance, iodine and an organic dye are mentioned, for example. These may be used alone or in combination of two or more. Dichroic substances are preferably iodine. When iodine is used as the dichroic substance, the above-mentioned dyeing solution is preferably an aqueous iodine solution. The blending amount of iodine is preferably 0.1 part by weight to 0.5 part by weight with respect to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is suitable to mix iodide in the iodine aqueous 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. Among them, potassium iodide is preferred. The blending amount of the iodide is preferably 0.02 parts by weight to 20 parts by weight with respect to 100 parts by weight of water, and more preferably 0.1 parts by weight to 10 parts by weight.

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

(Extended Processing)

An arbitrary and appropriate method can be adopted as a method of extending the layered body. Specifically, it can be either fixed-end stretching (eg, a method of using a tenter stretching machine) or free-end stretching (eg, a method of uniaxially stretching the laminate through rollers with different peripheral speeds). In addition, it can be synchronous biaxial stretching (for example, a method using a synchronous biaxial stretching machine) or stepwise biaxial stretching. The extension of the laminate may be performed in one stage or in multiple stages. In addition, when performing in multiple stages, the stretching ratio (maximum stretching ratio) of the layered body described later is the product of the stretching ratios of the respective stages.

The stretching treatment may be an underwater stretching method in which the layered body is immersed in a stretching bath, or an air stretching method. In one embodiment, the underwater stretching treatment is performed at least once, and it is preferable to combine the underwater stretching treatment and the air stretching treatment. By stretching in water, it can be stretched at a lower temperature than the glass transition temperature of the resin substrate or the PVA-based resin layer (about 80°C in the representative), and high magnification can be performed while suppressing the crystallization of the PVA-based resin layer. extend. Thus, a polarizing film having excellent polarization characteristics can be produced.

An arbitrary and appropriate direction can be selected for the extending direction of the laminate. In one embodiment, it extends along the longitudinal direction of the elongated laminate. Specifically, the layered body is transported in the longitudinal direction, that is, its transport direction (MD). In another embodiment, it extends along the width direction of the elongated laminated body. Specifically, the laminate is transported in the longitudinal direction, that is, the direction (TD) orthogonal to the transport direction (MD).

The stretching temperature of the laminate can be set to an arbitrary and appropriate value according to the forming material of the resin base material, the stretching method, and the like. air extension In this method, the stretching temperature is preferably higher than the glass transition temperature (Tg) of the resin substrate, more preferably the glass transition temperature (Tg)+10°C or higher of the resin substrate, and particularly preferably Tg+15°C or higher. On the other hand, the stretching temperature of the laminate is preferably 170°C or lower. Stretching at such a temperature can suppress the rapid progress of crystallization of the PVA-based resin, thereby suppressing the inconvenience caused by the crystallization (for example, hindering the alignment of the PVA-based resin layer due to elongation).

When the stretching method in water is used as the stretching method, the temperature of the liquid in the stretching bath is preferably 40°C to 85°C, more preferably 50°C to 85°C. As long as the temperature is within the above-mentioned temperature, the PVA-based resin layer can be suppressed from being dissolved, and at the same time, it can be stretched at a high rate. Specifically, as described above, in consideration of the relationship with the formation of the PVA-based resin layer, the glass transition temperature (Tg) of the resin substrate is preferably 60° C. or higher. At this time, if the stretching temperature is lower than 40° C., even if it is considered that the resin base material can be plasticized with water, it may not be able to be stretched well. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and there is a fear that excellent polarization characteristics cannot be obtained.

In the case of the underwater stretching method, a method of immersing the layered body in a boric acid aqueous solution for stretching (boric acid water stretching) is preferable. By using the boric acid aqueous solution as the stretching bath, the PVA-based resin layer can be imparted with rigidity capable of withstanding the tension applied during stretching and water resistance insoluble in water. Specifically, boric acid generates tetrahydroxyboronic acid anion in an aqueous solution and can be cross-linked with PVA-based resin by hydrogen bonding. As a result, rigidity and water resistance can be imparted to the PVA-based resin layer, and the PVA-based resin layer can be extended well, and a polarizing film having excellent polarizing properties can be produced.

The above boric acid aqueous solution preferably dissolves boric acid and/or borate Obtained in solvent namely water. The boric acid concentration is preferably 1 to 10 parts by weight relative to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film with higher characteristics can be produced. In addition to boric acid or borate, an aqueous solution obtained by dissolving boron compounds such as borax, glyoxal, and glutaraldehyde in a solvent can also be used.

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

The immersion time for the layered body to be immersed in the stretching bath is preferably 15 seconds to 5 minutes. The extension treatment in water should be carried out after the dyeing treatment.

The stretching ratio (maximum stretching ratio) of the layered body is preferably 4.0 times or more, and more preferably 5.0 times or more, with respect to the original length of the layered body. The high extension ratio can be achieved by using, for example, an underwater extension method (boric acid water extension). In addition, the "maximum stretching ratio" in the present specification means the stretching ratio before the layered body is fractured, and is a value lower than the value by 0.2 after confirming the stretching ratio at which the layered body is fractured.

(non-dissolving treatment)

The above-mentioned insolubilization treatment is performed by immersing the PVA-based resin layer in an aqueous solution of boric acid. In particular, when the underwater stretching method is used, water resistance can be imparted to the PVA-based resin layer by performing the insolubilization treatment. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insoluble bath (boric acid aqueous solution) is preferably 20°C to 40°C. Insoluble treatment is suitable for It is performed after the laminated body is produced, or before dyeing treatment or underwater stretching treatment.

(Crosslinking treatment)

The above-mentioned crosslinking treatment can be typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. By performing the crosslinking treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight relative to 100 parts by weight of water. In addition, when the crosslinking treatment is performed after the above dyeing treatment, it is preferable to further blend iodide. By blending the iodide, the elution of the iodine adsorbed on the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 to 5 parts by weight relative to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the cross-linking bath (boric acid aqueous solution) is preferably 20°C to 50°C. The cross-linking treatment is preferably carried out before the extension treatment in water. In a suitable embodiment, dyeing treatment, crosslinking treatment, and underwater stretching treatment are performed in this order.

(cleaning treatment)

The above-mentioned cleaning treatment can be typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

(drying treatment)

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

D. Optical laminate

The present invention also provides an optical laminate having a resin substrate, an undercoat layer and a polarizing film in this order. The optical laminate of the present invention may be a polarizing film in which the polyvinyl alcohol-based resin layer of the laminate described in the item A is formed into a dichroic substance and oriented by adsorption.

The thickness of the polarizing film is preferably 10 μm or less, preferably 8 μm or less, more preferably 7 μm or less, and even more preferably 6 μm or less. On the other hand, the thickness of the polarizing film is preferably 1.0 μm or more, more preferably 2.0 μm or more.

The polarizing film is essentially the above-mentioned PVA-based resin layer in which dichroic substances are adsorbed and aligned, and is suitable for exhibiting absorption dichroism at any wavelength of 380 nm to 780 nm. At this time, the monomer transmittance of the polarizing film (PVA-based resin layer) is preferably 40.0% or more, more preferably 41.0% or more, more preferably 42.0% or more, and particularly preferably 43.0% or more. The degree of polarization of the polarizing film (PVA-based resin layer) is preferably 99.8% or more, more preferably 99.9% or more, and more preferably 99.95% or more.

The optical layered product of the present invention can be typically produced by the method for producing an optical layered product described in the section C.

E. Application of Optical Laminate

According to the optical laminate of the present invention, the resin base material can be used as an optical member without peeling off the polarizing film. At this time, the resin base material can function as a protective film of the polarizing film, for example. Alternatively, the optically functional film may be laminated on the polarizing film of the optical laminate through any appropriate adhesive layer, and then the resin substrate may be peeled off. The said optically functional film can function as a polarizing film protective film, a retardation film, etc., for example.

Example

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

(thickness)

Using a digital micrometer (manufactured by Anritsu, product name "KC-351C") Determination.

(dissolution rate)

It can be calculated by the following formula.

Dissolution rate (%)=([The thickness of the primer coating layer before applying the coating solution]-[The thickness of the primer layer])/[The thickness of the primer coating layer before applying the coating solution]× 100

[Example 1]

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

Corona treatment is applied to one side of the resin substrate, and the mixed solution (solid content concentration 4.0%) is applied on the corona treated side so that the thickness after drying becomes 2000 nm, and then dried at 60°C for 3 A primer coating layer is formed in minutes, and the mixed solution is a mixture of acetyl acetyl group-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200", degree of polymerization 1200, degree of saponification 99.0 mol% or more, ethyl acetate A 4.0% aqueous solution of an acyl group modification degree of 4.6%), a modified polyolefin resin aqueous dispersion (manufactured by Unitika, trade name "ARROW BASE SE1030N", solid content concentration 22%) mixed with pure water. Here, the mixing ratio of the solid content of the acetylacetate-modified PVA and the modified polyolefin in the mixed solution is 30:70.

Then, corona treatment is applied to the surface of the primer coating layer, and the corona treated surface is coated with polyvinyl alcohol in a ratio of 9:1 (degree of polymerization 4200, degree of saponification 99.2 mol%) at 25°C. And the aqueous solution of acetyl acetyl group modified PVA (polymerization degree 1200, acetyl acetyl group modification degree 4.6%, saponification degree above 99.0 mol%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200") After drying, a PVA-based resin coating layer with a thickness of 11 μm was formed.

Next, it left still at 65 degreeC for 10 minutes or more, and the structural component of the primer coating layer was eluted to the PVA-type resin coating layer. As described above, a laminate including the resin base material, the primer layer, and the PVA-based resin layer in this order can be produced.

The obtained layered body was uniaxially stretched 2.0 times at the free end along the longitudinal direction (longitudinal direction) between rollers with different peripheral speeds in an oven at 120° C. (subsidiary stretching in the air).

Next, the layered body 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) at a liquid temperature of 30° C. for 30 seconds (insolubility treatment).

Next, it was immersed in a dyeing bath with a liquid temperature of 30° C. and the iodine concentration and the immersion time were adjusted at the same time, so that the obtained polarizing film had a predetermined transmittance. In this example, it was immersed for 60 seconds in an iodine aqueous solution obtained by blending 0.2 parts by weight of iodine and 1.0 parts by weight of potassium iodide with respect to 100 parts by weight of water (dyeing treatment).

Next, it was immersed in a cross-linking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds in a cross-linking bath (cross-linking treatment) .

Then, while immersing the layered body in an aqueous solution of boric acid at a liquid temperature of 70° C. (an aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water), between the rollers with different peripheral speeds The longitudinal direction (longitudinal direction) was uniaxially stretched so that the total stretching magnification was 5.5 times (in-water stretching).

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

As described above, an optical laminate (polarizing plate) in which a polarizing film with a thickness of 5 μm was formed on one side of a resin substrate with a thickness of 30 μm was obtained.

[Example 2]

An optical layered body was produced in the same manner as in Example 1, except that the above-mentioned mixed solution was applied so that the thickness after drying was 1000 nm.

[Example 3]

An optical layered body was produced in the same manner as in Example 1, except that the above-mentioned mixed solution was applied so that the thickness after drying was 500 nm.

[Example 4]

An optical layered product was obtained in the same manner as in Example 1, except that the solid content mixing ratio of the acetylacetate group-modified PVA and the modified polyolefin in the mixed solution was set to 50:50.

[Example 5]

Except for the formation of the primer coating layer, a 4.0% aqueous solution of acetylacetate-modified PVA (GOHIMER Z200), a modified polyolefin resin aqueous dispersion (manufactured by Unitika, trade name "ARROW BASE SD1030N", An optical layered product was obtained in the same manner as in Example 1, except that the mixed solution (solid content concentration 4.0%) was mixed with pure water.

[Example 6]

In addition to the formation of the primer coating layer, the use of acetyl acetyl group modified A mixed solution (solid content concentration) obtained by mixing a 4.0% aqueous solution of PVA (GOHSEFIMER Z200), a modified polyolefin resin aqueous dispersion (manufactured by Unitika, trade name "ARROW BASE SE1035NJ2", solid content concentration 22%) and pure water 4.0%), an optical laminate was obtained in the same manner as in Example 4.

[Example 7]

Except for the formation of the primer coating layer, PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410" modified with acetyl acetyl group, degree of polymerization 2200, degree of saponification 97.5~98.5%, acetyl acetyl group A 4.0% aqueous solution with a base modification degree of 4.6%), an aqueous dispersion of modified polyolefin resin (manufactured by Unitika Co., Ltd., trade name "ARROW BASE SE1030N", solid content concentration 22%) mixed with pure water. An optical layered body was obtained in the same manner as in Example 1 except that the solid content concentration was 4.0%.

[Example 8]

A primer layer was formed on one side of a resin substrate with a thickness of 37 μm in the same manner as in Example 1, except that the stretching ratio of the auxiliary stretching in the air was set to 4.0 times, and the insolubility treatment and water stretching were not carried out. An optical laminate with a polarizing film with a thickness of 6 μm .

[Example 9]

In addition to the use of a mixed solution of 10 g of a 4.0% aqueous solution of acetyl acetyl modified PVA (GOHSEFIMER Z200) and 62.5 g of polyester water-based emulsion resin (elitel KT0507E6) when forming the primer coating layer, according to An optical laminate was obtained in the same manner as in Example 1. Here, mix The mixing ratio of the solid content of the acetylacetate-modified PVA and polyester in the combined solution is 50:50.

[Comparative Example 1]

An optical laminate was obtained in the same manner as in Example 1, except that the primer coating layer was not formed and the PVA-based resin coating layer (PVA-based resin layer) was directly formed on the resin substrate.

[Comparative Example 2]

An optical laminate was obtained in the same manner as in Example 3, except that a 4.0% aqueous solution of acetylacetate-modified PVA (GOHSEFIMER Z200) was used in forming the primer coating layer.

[Comparative Example 3]

An optical laminate was obtained in the same manner as in Example 2, except that a 4.0% aqueous solution of acetylacetate-modified PVA (GOHSEFIMER Z200) was used in forming the primer coating layer.

[Comparative Example 4]

An optical layered product was obtained in the same manner as in Example 1, except that a 4.0% aqueous solution of acetylacetate-modified PVA (GOHSEFIMER Z200) was used in forming the primer coating layer.

[Comparative Example 5]

Except for using 4.0% aqueous solution of acetylacetate modified PVA (GOHSEFIMER Z200) to form the primer coating layer, and coating the mixed solution in such a way that the dry thickness is 1000 nm, the same procedure as in the examples was carried out. 8 An optical laminate was obtained in the same manner.

[Comparative Example 6]

An optical laminate was obtained in the same manner as in Example 3, except that an aqueous polyester emulsion resin (manufactured by Unitika, trade name "elitel KT0507E6") was used for forming the primer coating layer.

[Comparative Example 7]

An optical laminate was obtained in the same manner as in Example 2, except that a polyester aqueous emulsion resin (manufactured by Unitika, trade name "elitel KT0507E6") was used for forming the primer coating layer.

(Assessment of Adhesion)

For the above Examples and Comparative Examples, adhesion was evaluated by measuring the PVA peel force and the substrate peel force. The evaluation results are summarized in Table 1. In addition, the measurement methods of PVA peeling force and substrate peeling force are as follows.

(PVA peel force)

The obtained optical layered product was coated with an adhesive on the surface of the resin substrate, and then adhered to a glass plate, and a reinforcing polyimide tape (manufactured by Nitto Denko Co., Ltd., polyamide tape) was adhered to the polarizing film surface. Amine adhesive tape No. 360A), and produced the sample for measurement. Use a cutting knife to make a cut between the polarizing film and the resin substrate of the sample for measurement, and then stick it with an angle-variable type. The film peeling analysis device "VPA-2" (manufactured by Kyowa Interface Chemical Co., Ltd.) measures the peeling speed when the polarizing film and the polyimide tape for reinforcement are lifted at an angle of 90° with respect to the surface of the resin substrate. It is the force (N/15mm) required for peeling at 3000mm/min.

(Substrate peel force)

The obtained optical layered body was coated with an adhesive on the side of the polarizing film, and was bonded to a glass plate to prepare a sample for measurement. Use a cutting knife for this measurement After making a notch between the polarizing film of the sample and the resin substrate, pick up the resin substrate at an angle of 90° with respect to the surface of the polarizing film according to the above "VPA-2" measurement, and use the peeling speed of 3000mm/ The force required for peeling at min (N/15mm).

As shown in Table 1, the PVA peeling force and the substrate peeling force of the optical laminates of Examples were both 0.6 N or more, and it was found that the adhesiveness was excellent. In addition, the optical layered bodies of Examples 1 to 7 and 9 maintained sufficient adhesion even when underwater stretching was performed. On the other hand, Comparative Example 1 in which the undercoat layer was not formed and Comparative Examples 2 to 5 in which the undercoat layer only contained the polyvinyl alcohol-based component were not sufficiently dense for peeling from the PVA-based resin layer (polarizing film) side. stickiness. Moreover, in Comparative Examples 6 and 7 in which the undercoat coating layer did not contain a polyvinyl alcohol-based component, sufficient adhesion was not obtained with respect to peeling from the resin substrate side.

[Reference Example 1]

A layered product was obtained in the same manner as in Example 9, except that the mixed liquid was applied so that the thickness after drying was 1.7 μm . Fig. 1(a) shows the result of SEM observation (6500 times) of the cross section of the primer coating layer (the cross section of the laminate of [resin substrate/primer coating layer]), and Fig. 1(b) shows the The result of SEM observation (6500 times) of the cross section of the coating layer (the cross section of the laminate of [resin base layer/undercoat layer/PVA resin layer]). As shown in FIGS. 1( a ) and 1 ( b ), a primer layer having a thickness of 0.6 μm is formed by elution of polyvinyl alcohol-based components and the like from the primer coating layer formed with a thickness of 1.7 μm .

industrial availability

The built-up layer of the present invention is suitable for use in, for example, an image display device. Specifically, it is suitable for use as a resistance to liquid crystal panels and organic EL devices such as LCD TVs, LCD monitors, mobile phones, digital cameras, video cameras, portable game machines, car navigation machines, photocopiers, printers, fax machines, clocks, microwave ovens, etc. reflector, etc.

Claims (12)

A laminate comprising a resin substrate, an undercoat layer and a polyvinyl alcohol-based resin layer in sequence; wherein the undercoat layer and the polyvinyl alcohol-based resin layer are formed by the following methods: sequentially disposed on In the primer coating layer and the polyvinyl alcohol-based resin coating layer on the resin substrate, 5 to 70 volume % of the primer coating layer is dissolved in the polyvinyl alcohol-based resin coating layer to form The primer coating layer contains two or more resin components and the resin component contains a polyvinyl alcohol-based component, and the blending ratio of the polyvinyl alcohol-based component in the resin component of the primer coating layer is 5% by weight~ 50% by weight. The laminate according to claim 1, wherein the thickness of the undercoat layer is 0.2 μm to 2.0 μm. The layered product according to claim 1 or 2, wherein the polyvinyl alcohol-based component contains an acetylacetate group-modified polyvinyl alcohol. The laminate according to claim 1 or 2, wherein the primer coating layer contains the polyvinyl alcohol-based component and the polyolefin-based component. The laminate according to claim 4, wherein the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component (polyvinyl alcohol-based component: polyolefin-based component) is 5:95 to 50:50 on a weight basis. A method for manufacturing a laminate, which is a method for manufacturing a laminate having a resin substrate, a primer layer and a polyvinyl alcohol-based resin layer in this order, and the method comprises the steps of: forming a primer on one side of the resin substrate cloth layer, and coat the primer A polyvinyl alcohol-based resin coating layer is formed on the surface of the layer; and 5% to 70% by volume of the primer coating layer is dissolved in the polyvinyl alcohol-based resin coating layer, and the primer coating layer and the The polyvinyl alcohol-based resin coating layer is made into a primer layer and a polyvinyl alcohol-based resin layer, respectively; the primer coating layer contains two or more resin components and the resin component contains a polyvinyl alcohol-based component, and the primer coating layer contains two or more resin components. The blending ratio of the polyvinyl alcohol-based component in the resin component of the cloth layer is 5% by weight to 50% by weight. The manufacturing method of claim 6, wherein the thickness of the undercoat layer is 0.2 μm to 2.0 μm. The production method according to claim 6 or 7, wherein the polyvinyl alcohol-based component contains an acetylacetate group-modified polyvinyl alcohol. The production method according to claim 6 or 7, wherein the primer coating layer contains the polyvinyl alcohol-based component and the polyolefin-based component. The production method according to claim 9, wherein the blending ratio of the polyvinyl alcohol-based component and the polyolefin-based component (polyvinyl alcohol-based component: polyolefin-based component) is 5:95 to 50:50 on a weight basis. An optical laminate comprising a resin substrate, an undercoat layer and a polarizing film in sequence; and the polyvinyl alcohol-based resin layer of the laminate according to any one of claims 1 to 5 is formed by adsorption and alignment of a dichroic substance polarizing film. A manufacturing method of an optical laminate, the optical laminate has a resin substrate, an undercoat layer and a polarizing film in sequence, and the method comprises the following steps: According to the manufacturing method of the laminated body according to any one of Claims 6 to 10, a laminated body having a resin base material, a primer layer and a polyvinyl alcohol-based resin layer in this order is produced; and the polyvinyl alcohol-based resin layer It is dyed and stretched to make a polarizing film.

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