JPH08211376A - Transparent laminated film - Google Patents

Abstract

PURPOSE: To improve resistance against org. solvents, alkali resistance and resistance against etching liquid by forming a protective layer comprising a hardened layer of a silicone hardening resin. CONSTITUTION: This transparent laminated film is produced by forming a protective layer comprising a hardened layer of a silicone hardening resin on the surface of a polymer film. As for the silicone hardening resin, a resin containing 40wt.% trialkoxy silane is preferable. It is preferable to add acid soln. such as hydrochloric acid and acetic acid to accelerate hardening of the silicone hardening resin. As for the polymer film, a transparent film such as polyester, polycarbonate, polyarylate and polysulfone is used. Especially, an optically isotropic polymer film having <=20nm retardation and >=85% transmittance for 550nm wavelength light is preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent laminated film having excellent solvent resistance and transparency.
In particular, the present invention relates to a transparent laminated film suitable for a transparent substrate such as a liquid crystal display panel, a touch panel, a flat lighting panel, and a transparent electrode substrate.

[0002]

2. Description of the Related Art In recent years, in addition to the demands for lighter and thinner and larger size members for liquid crystal display devices, long-term reliability,
There are high demands on the degree of freedom of shape and curved surface display. In particular, as the use of portable and mobile devices such as pagers (pagers), mobile phones, electronic organizers, and pen input devices becomes widespread, these transparent substrates and transparent electrode substrates are thick, heavy, and cracked. Transparent substrates and transparent electrode substrates using a plastic film as a substrate have been studied in place of the easy glass substrate, and some of them have been put into practical use.

However, this plastic film substrate is generally inferior in solvent resistance to the glass substrate.
By the way, the transparent electrode substrate of a plastic film provided with a transparent conductive layer, when used in the above liquid crystal display panel or the like, an acidic aqueous solution for etching the transparent conductive layer, an alkaline liquid for dissolving the resist after patterning, and depending on the application. It is exposed to an organic solvent when the alignment film is formed. At this time, the plastic film may be swollen or whitened and may be further dissolved, so that it cannot be used as an electrode substrate.

As a concrete proposal for improving this problem,
It has been proposed to provide a plastic film with a protective layer having solvent resistance. For example, JP-A-64-500
No. 22, etc. propose to provide a resin layer for crosslinking a phenoxy ether type resin with an isocyanate group or the like by a coating method, but the solvent resistance is not sufficiently satisfied. Further, Japanese Patent Laid-Open No. 5-313150 proposes to provide an active energy ray-curable resin layer, but a release film is required at the time of curing, which causes difficulty in the process.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the above problems and has sufficient solvent resistance, specifically, organic solvent resistance, alkali resistance and etching solution resistance required for various applications. To provide a transparent laminated film having high solvent resistance, satisfying all of the requirements at the same time, having a small load on the process, and being sufficiently applicable to various display electrode substrates, particularly to liquid crystal display elements that are particularly demanding. The purpose is to

[0006]

The above object can be achieved by the present invention described below. That is, the present invention is a transparent laminated film in which a protective layer having solvent resistance is provided on at least one surface of a polymer film, wherein the protective layer is a cured product of a silicone-based curable resin. It is a laminated film.

According to the present invention described above, the layer formed of a cured product of a silicone-based curable resin has a high solvent resistance which simultaneously satisfies the above-mentioned organic solvent resistance, alkali resistance and etching solution resistance, and It was made by finding that the optical characteristics are also sufficient.

Hereinafter, the present invention will be described in detail.

In the present invention, having solvent resistance means that the substrate is an acidic aqueous solution for etching the transparent conductive layer, patterning as in the case of applying a polymer film substrate provided with a transparent conductive layer to an electrode substrate for various displays. It means that when exposed to an alkaline liquid for dissolving the resist later, and, depending on the application, various solvents such as an organic solvent during the preparation of the alignment film, it does not swell, whiten or dissolve, and does not pass these solvents. That is, when exposed to the solvent by providing a layer having solvent resistance, the layer having solvent resistance does not swell or whiten or dissolve and does not penetrate the solvent, and the polymer film serving as the substrate is a solvent. Protecting against swelling, whitening and dissolution due to.

As described above, the present invention is characterized in that a silicone-based curable resin is used for the solvent-resistant protective layer provided on the polymer film.

As the silicone-based curable resin, various known silicone-based resins can be applied, but among them, those containing 40% by weight or more of trialkoxysilane are preferable. Less than 40% by weight of trialkoxysilane,
When the content of tetraalkoxysilane is high, the obtained layer becomes too hard, and the layer is cracked or has poor flexibility. Further, if the amount of dialkoxysilane or monoalkoxysilane increases, the desired solvent resistance becomes insufficient.

Here, as the trialkoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane,
Vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-β ( Aminoethyl) γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like. Other components include tetraalkoxysilane, dialkoxysilane, monoalkoxysilane, colloidal silica and the like. Examples of the tetraalkoxysilane include methyl silicate, ethyl silicate and propyl silicate. Examples of dialkoxysilane include dimethyldimethoxysilane, dimethyldiethoxysilane, and diethyldimethoxysilane.
Examples of monoalkoxysilanes include trimethylmethoxysilane and the like.

The silicone-based curable resin of the present invention contains an acrylic resin, a polyurethane resin, an epoxy resin, a melamine resin, a polyvinyl alcohol-based resin, and a urea, from the viewpoint of improving the adhesiveness, as long as the transparency is not impaired. It is possible to add a resin or the like.

To the silicone-based curable resin containing 40% or more of trialkoxysilane, it is preferable to add an acidic aqueous solution such as hydrochloric acid or acetic acid in order to accelerate the curing. Further, the composition can be diluted with a volatile solvent, and examples of the solvent include alcohols, esters, ethers, ketones, and mixed solvents thereof.

Means for providing the above silicone-based curable resin layer include wet coating methods such as Mayer bar coating method, gravure roll coating method and spin coating method, depping method, laminating coating method and the like, but a uniform film. The wet coating method is preferably used from the viewpoint of forming thickness.

The coated silicone-based curable resin layer is cured by heat treatment at a temperature below the glass transition temperature of the polymer film of the substrate to form a cured resin layer having solvent resistance.

The thickness of the silicone-based curable resin layer is preferably 0.1 μm or more and 20 μm or less in terms of the thickness after curing,
It is more preferably 0.2 μm or more and 15 μm or less. 0.1μ
If it is less than m, the effect as a solvent-resistant protective layer becomes insufficient, and if it exceeds 20 μm, the flexibility required for processing, assembly, etc. becomes insufficient, which is not suitable for practical use.

The transparent laminated film provided with this protective layer is
Considering optical applications that require high optical properties such as when used in a display panel such as a liquid crystal display panel, the retardation value is preferably 20 nm or less and the light transmittance at 550 nm is preferably 80% or more. .

Here, the retardation value is a product Δn · d of the known refractive index difference Δn of the birefringence and the film thickness d, and it depends on the measurement wavelength, but the measurement value at the measurement wavelength of 590 nm is the representative value. To do. When the retardation value exceeds 20 nm, it causes coloring especially when used as a liquid crystal display device. On the other hand, when the light transmittance is less than 80%, the transparency as an electrode substrate for various displays becomes insufficient.

When a strong adhesive force is required between the polymer film and the silicone-based curable resin layer, an anchor coat layer is provided on the polymer film and then the silicone-based curable resin layer is provided. Is preferably coated. An acrylic resin or the like can be applied to this anchor coat layer, and it can be provided by wet coating.

When the transparent laminated film may be immersed in a solvent, it is desirable to provide the above protective layers on both sides of the polymer film.

The polymer film in the present invention includes
Known transparent polymer films such as polyester, polycarbonate, polyarylate, polysulfone, and polyethersulfone are applied, but when the above optical applications are included, the retardation value is 20 nm or less, and the light ray at 550 nm is used. An optically isotropic polymer film having a transmittance of 85% or more is preferable.

In general, a polymer film is prepared by a melt extrusion method in which a raw material polymer material is thermally melted and extruded from a die to form a film, or the polymer material is dissolved in a solvent and poured onto a support. It can be obtained by a solution casting method of spreading and heating to evaporate the solvent to form a film, and the solution casting method is preferably used to achieve the retardation. In the melt extrusion method, it is not only difficult to obtain a low retardation film, but also a die line, a gelled product,
Fish eyes are likely to occur, and it is difficult to obtain a film having uniform optical characteristics over a wide area.

Examples of the polymer material for the above-mentioned optically isotropic polymer film include amorphous polymer materials such as polycarbonate, polyarylate, polyether sulfone and polysulfone. From the viewpoint, polycarbonate or polyarylate is particularly preferably used.

Polycarbonate is 2,2-bis (4-
A main component is hydroxyphenyl) propane, and a copolymerization component may be included for improving optical characteristics and heat resistance. Examples of the copolymerization component include bis (4-oxyphenyl) methane, 1,1-bis (4-oxyphenyl) ethane, 1,1-bis (4-oxyphenyl) butane, 2,
2-bis (4-oxyphenyl) butane, 1,1-cyclohexylene, 9,9-bis (4-hydroxyphenyl) fluorene, 1,1-bis (4-hydroxyphenyl) 3,3,5-trimethylcyclohexane Etc.

Polyarylate contains 2,2-bis (4-hydroxyphenyl) propane component as a main component as a diol component, and terephthalic acid and isophthalic acid as a main component as dicarboxylic acid components.

For the production of these films, as described above, the above-mentioned solution casting method in which polycarbonate or polyarylate is dissolved in a solvent and cast on a support is preferably applied. As the solvent for forming the film, any solvent that basically dissolves polycarbonate or polyarylate can be applied, but methylene chloride or the like is preferably used. The concentration of the raw material polymer in the solution for film formation is 6% by weight.
The amount is preferably 30% by weight or less. If it exceeds 30% by weight, uniform dissolution and storage stability of the solution are poor, and if it is less than 6% by weight, the effective viscosity is low and it is not preferable in practice.

By the way, when a polymer film is used for a transparent electrode substrate of a liquid crystal display panel or the like, a gas barrier property is required. That is, the polymer film generally has gas permeability as compared with the glass substrate, and the permeated gas becomes bubbles in the liquid crystal part, which causes a display defect. Therefore, a layer that prevents gas permeation, that is, a gas barrier layer is required. Therefore, when the above-mentioned transparent laminated film of the present invention is also applied to these applications, it is preferable to provide a gas barrier layer.

This gas barrier layer contains polyvinyl alcohol, polyvinyl alcohol-ethylene copolymer, polyvinylidene chloride and its copolymer, polyacrylonitrile and its copolymer, which are known as polymers having gas barrier properties. Coalition etc. can be applied. Among them, polyvinyl alcohol and polyvinyl alcohol-ethylene copolymer are preferable from the viewpoint of gas generated during incineration.

This gas barrier layer is formed by the wet coating method described for the protective layer. For example, the gas barrier layer of polyvinyl alcohol or polyvinyl alcohol-ethylene copolymer is a known solvent, that is, polyvinyl alcohol is dissolved in water, polyvinyl alcohol-ethylene copolymer is dissolved in a mixed solvent of water and propyl alcohol, It is formed by coating a polymer film by a coating method and removing the solvent by a drying treatment at a temperature not higher than the glass transition temperature of the polymer film.

The thickness of the gas barrier layer varies depending on the required gas barrier performance, but is usually 0.1 μm or more and 50 or more.
μm or less, and when used in a liquid crystal display device, 25
At least oxygen permeation rate at 1 cc / m ² · day · at
A gas barrier property of m or less is required.

When used in the transparent laminated film of the present invention, this gas barrier layer is preferably provided between the polymer film and the silicone-based curable resin layer of the protective layer from the viewpoint of solvent resistance.

In this structure, when the adhesiveness between the polymer film and the gas barrier layer is required, an anchor coat layer is provided between them if necessary. A commercially available urethane adhesive or the like can be used as the anchor coat layer.

Furthermore, the following transparent conductive layer can be provided on the surface of the laminated film of the present invention having the above-mentioned constitution, whereby a transparent conductive laminated film suitable for a transparent electrode of a liquid crystal display panel or the like can be obtained. Obtainable.

Known transparent metals such as tin, indium and titanium, or oxides thereof can be applied to the transparent conductive layer, but the transparent conductive layer is mainly composed of amorphous indium oxide, and the content of tin is 5 to 15% by weight. Those which are contained and have a film thickness of the transparent conductive layer in the range of 20 to 200 nm are preferable from the viewpoint of transparency, conductivity, flexibility and the like.

Indium oxide having high crystallinity has high transparency and conductivity as compared with an amorphous material and is preferable as a transparent electrode material. However, a crystalline film is formed on a film having high flexibility, When this film is bent, it breaks easily and the handleability deteriorates.

Here, the crystallinity and non-crystallinity of the formed indium oxide are defined as follows. When a film of indium oxide was formed by some method and the surface thereof was observed with a transmission electron microscope, the diameter of the amorphous film was 100 at most.
A nanocrystal of about nm is observed. With this observation method, the crystal grain area ratio per unit volume (100 μm ² ) is 20.
% Or less is regarded as non-crystalline.

Although indium oxide is originally a transparent electric insulator, it becomes a semiconductor when it contains a trace amount of impurities or when it is slightly oxygen-deficient. Preferred semiconductor metal oxides include indium oxide containing tin or fluorine as an impurity, and particularly preferably, indium oxide containing 5 to 15% by weight of tin is
Shows good conductivity while maintaining high transparency.

The thickness is 20 to 200.
The range of nm is preferred. If the thickness is less than 20 nm, the sheet resistance becomes electrically high, and it becomes difficult to utilize it as a good transparent conductive film. When the thickness is more than 200 nm, it becomes difficult to obtain a value of 80% or more as the 550 nm transmittance of the film, and the film is easily cracked when bent, which makes it difficult to handle.

Hereinafter, examples of the present invention will be described together with comparative examples.

[0041]

EXAMPLES Various physical properties of Examples and Comparative Examples were measured as follows. (1) Solvent resistance (a) Organic solvent resistance It was immersed in N-methylpyrrolidone at 80 ° C for 3 minutes, and the change in appearance was visually observed.

(B) Alkali resistance It was immersed in an aqueous 3.5 wt% NaOH solution at 25 ° C. for 10 minutes, thoroughly washed with running water, dried and weighed, and the weight difference before and after immersion was judged.

(C) Resistance to Etching Liquid 35% ferric chloride aqueous solution, 35% hydrochloric acid, and water were mixed at a ratio of 1: 1: 1 by weight for 10 minutes at 25 ° C. under running water. After thorough washing, it was dried and weighed, and the weight difference before and after immersion was judged. (2) Light transmittance Using Hitachi U-3500, a wavelength of 550
An integrated sphere type light transmittance of nm was measured. (3) Retardation measurement Multi-wavelength birefringence measuring device M-15 manufactured by JASCO Corporation
0 was used for measurement at a wavelength of 590 nm. (4) Oxygen permeability measurement 25 using MOCON Oxytran 2 / 20MH
It was measured at ° C.

Example 1 As a polymer film for a substrate, a polycarbonate film was prepared by the solution casting method as follows.

After dissolving 20 parts by weight of a polycarbonate resin (specifically, C-1400 manufactured by Teijin Kasei Co., Ltd.) in 80 parts by weight of methylene chloride, it is cast on a glass plate with an applicator and then dried. It was placed inside and gradually heated from room temperature. When the residual solvent reaches 13% by weight, peel it off from the glass plate and
It was dried at 0 ° C. until the residual solvent amount became 0.1% by weight or less to obtain a polycarbonate film. The thickness of this film was 98 μm.

An anchor coat layer was formed on one surface of this polycarbonate film. The anchor coat layer is made of polyurethane resin. Specifically, 100 parts by weight of A310 manufactured by Takeda Pharmaceutical Co., Ltd. is used as the polyol component of the main agent, and 2 parts of A3 manufactured by the same company is used as the isocyanate component of the curing agent.
After mixing 5 parts by weight, it was formed by coating with a Meyer bar and heat treatment at 130 ° C. for 30 minutes. The thickness of the anchor coat layer was 1 μm.

Next, a gas barrier layer was laminated on this anchor coat layer. The gas barrier layer is made of polyvinyl alcohol (specifically, PVA-11 manufactured by Kuraray Co., Ltd.).
7) 12 parts by weight was uniformly dissolved in 88 parts by weight of water as a solvent, and the solution was applied with a Meyer bar and heat-treated at 110 ° C. for 30 minutes to form the film. The thickness of the gas barrier layer is 8
μm. The film having this structure will be referred to as a polymer film with a gas barrier layer.

A protective layer was laminated on the polymer film with the gas barrier layer as follows to obtain a transparent laminated film. The protective layer was composed of 18 g of γ-aminopropyltrimethoxysilane, 14.8 g of methyltrimethoxysilane, 2.6 g of dimethyldimethoxysilane and 1N of 0.01N hydrochloric acid.
A coating liquid of a silicone-based curable resin obtained by adding 1.5 g and stirring for 3 hours while maintaining the temperature at 20 ° C. was prepared. Apply this coating solution
After coating on one side of the polymer film with a gas barrier layer with a Meyer bar and heat treating at 135 ° C. for 10 minutes,
Similarly, the other surface was coated and heat-treated in the same manner, and a protective layer was laminated on both surfaces. The protective layers each had a thickness of 3.5 μm.

The obtained transparent laminated film had a retardation of 10 nm, a light transmittance of 90% and an oxygen transmittance of 0.
It was 2 cc / square meter · day · atm, and there was no problem in solvent resistance, and it was a transparent laminated film excellent in optical properties, gas barrier properties and solvent resistance.

Example 2 As a polymer film for a substrate, a polyarylate film was prepared by the solution casting method as follows.

Polyarylate (U- manufactured by Unitika Ltd.)
After dissolving 23 parts by weight of 100) in 77 parts by weight of methylene chloride, the mixture was cast on a glass plate with an applicator, then placed in a dryer and gradually heated from room temperature. When the residual solvent was 15% by weight, it was peeled from the glass plate and dried at 120 ° C. while balancing the vertical and horizontal tensions until the residual solvent amount became 0.08% by weight to obtain a polyarylate film. The thickness of this film was 101 μm.

The same anchor coat layer, gas barrier layer and protective layer as those in Example 1 were laminated on this polyarylate film in the same manner as in Example 1.

The obtained transparent laminated film had a retardation of 11 nm and a light transmittance of 88%, was free from solvent resistance, and was a transparent laminated film excellent in optical characteristics and solvent resistance.

Example 3 A transparent laminated film was obtained by directly laminating the same protective layer as that of Example 1 on both sides of the polycarbonate film obtained in Example 1 as described below.

The obtained transparent laminated film had a retardation of 10 nm and a light transmittance of 90%, had no solvent resistance, and was an optical laminated film excellent in optical characteristics and solvent resistance.

Further, an indium-tin oxide layer was formed as a transparent conductive layer on one surface by a sputtering method. As the sputtering target, a target having a composition of indium / tin = 90/10 by weight and a packing density of 90% was used. The obtained transparent laminated film with a transparent conductive layer was suitable for a transparent electrode substrate such as a transparent touch panel.

Comparative Example 1 A protective layer was laminated on the polymer film with a gas barrier layer obtained in Example 1 as follows to obtain a transparent laminated film.

For the protective layer, 40 parts by weight of a phenoxy resin (YP-50 manufactured by Tohto Kasei Co., Ltd.) was dissolved in 60 parts by weight of methyl ethyl ketone, and 40 parts by weight of A3, Takeda Pharmaceutical Co., Ltd. was added as an isocyanate and mixed uniformly. What was applied was coated on one side of the polymer film with a gas barrier layer with a Meyer bar, heat-treated at 80 ° C. for 4 minutes, and then on the other side in the same manner with a Meyer bar. After heat treatment at 80 ° C. for 4 minutes, heat treatment was further performed at 135 ° C. for 20 minutes to form both surfaces. The protective layers each had a thickness of 8 μm.

The transparent laminated film thus obtained had a retardation of 11 nm, a light transmittance of 90% and an oxygen transmittance of 0.1.
It was 5 cc / square meter.day.atm, but during the organic solvent resistance test, the swelling of the optical laminated film was so bad that the shape was not retained, and the organic solvent resistance was poor.

The above results are summarized in Table 1.

[0061]

[Table 1]

[0062]

INDUSTRIAL APPLICABILITY The present invention has a solvent-resistant protective layer formed of a silicone resin, and has excellent solvent resistance that simultaneously satisfies organic solvent resistance, alkali resistance and etching solution resistance, and has an optical property. It realizes a transparent laminated film having excellent characteristics and can be widely applied to display devices such as liquid crystal display panels, transparent substrates such as touch panels, transparent electrode substrates and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Tamura 4-3-2 Asahigaoka, Hino City, Tokyo Teijin Limited Tokyo Research Center

Claims (5)

[Claims] 1. A transparent laminated film having a protective layer having solvent resistance on at least one surface of a polymer film, wherein the protective layer is a cured product of a silicone-based curable resin. the film. 2. The transparent laminated film according to claim 1, wherein the silicone-based curable resin is a silicone-based curable resin containing 40% by weight or more of trialkoxysilane. 3. The retardation value of the laminated film is 2.
0 nm or less and 80% light transmittance at 550 nm
It is above, The transparent laminated film of Claim 1 or Claim 2. 4. The transparent laminated film according to claim 3, wherein the polymer film is a polycarbonate film or a polyarylate film. 5. The transparent laminated film according to claim 1, wherein a transparent conductive layer is provided on one outermost side.