JP3034938B2 - Optically isotropic laminate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optically isotropic laminate having improved rigidity, and particularly to an optically isotropic laminate suitable for an electrode substrate for a large-sized liquid crystal display panel. is there.

2. Description of the Related Art Conventionally, glass has been used as an electrode substrate for a liquid crystal display panel, but there are problems such as being heavy, being unable to be thin, being easily damaged, and being difficult to be mass-produced. Recently, plastics substrates have become widespread.

The present applicant also has a structure in which a gas-permeable resin layer is provided on at least one surface of the optically isotropic substrate sheet layer via an anchor coat layer, and a cured cross-linkable resin layer is further provided on the gas-permeable resin layer. Japanese Patent Laid-Open No. for electrode substrate for liquid crystal display panel
A patent application has been filed as Japanese Patent Publication No. 63-71829 and has already been put to practical use.

Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 50021 discloses a liquid crystal in which two laminated films each composed of an air-permeable resin layer / a crosslinked resin cured material layer are laminated and integrated via an adhesive layer with the air-permeable resin layers facing each other. There is a disclosure about an electrode substrate for a display panel.
Japanese Patent No. 50022 discloses an electrode substrate for a liquid crystal display panel having a structure of a crosslinked resin cured layer / air-permeable resin layer / crosslinked resin cured layer.

Problems to be Solved by the Invention Liquid crystal display panels have surprisingly evolved in recent years,
In addition, the size is increasing year by year. As a substrate for a large liquid crystal display panel, a glass substrate is still mainstream, but is gradually being replaced by a plastics substrate.

However, a thick plastic substrate is inevitable to have a large retardation value, while a thin plastic substrate having a small retardation value does not return immediately when touched by a hand. However, problems such as the formation of a liquid crystal ring at the location touched by the above are likely to occur.

JP-A-63-71829 according to the above-mentioned applicant's application
Japanese Patent Application Laid-Open No. 64-50021 and Japanese Patent Application Laid-Open No. 64-50022 are also excellent as small to medium-sized substrates, but have the same problems as large substrates described above. It was necessary to further improve.

An object of the present invention is to provide a plastics liquid crystal display panel electrode substrate having a small retardation value and rigidity in a situation where a large-sized plastics electrode substrate is desired. Things.

Means for Solving the Problems The optically isotropic laminate of the present invention has a retardation value of 20.
An air-permeable resin layer (2) is provided on at least one side of the light-isotropic substrate sheet layer (1) having a thickness of not more than nm by a casting method, and a cross-linkable resin is provided on the air-permeable resin layer (2) by a casting method. Two or more of the laminated sheets (4) provided with the cured resin layer (3) are interposed via an adhesive layer (ad) such that the crosslinked resin cured layer (3) is the outermost layer on both sides. It has a configuration in which it is attached.

 Hereinafter, the present invention will be described in detail.

Optically isotropic substrate sheet layer (1) Examples of the optically isotropic substrate sheet layer (1) include layers formed from a resin such as polyarylene ester, polycarbonate, polysulfone, polyethersulfone, or a polyolefin having a cyclo group.

The thickness of the optically isotropic substrate sheet layer (1) is usually 25 to 500.
μm, preferably in the range of 30 to 200 μm.

The retardation value of the optically isotropic substrate sheet layer (1) is set to 20 nm or less. If the retardation value is larger than this, the proper viewing angle as a panel becomes narrow, and interference fringes are generated, so that the readability of a liquid crystal display panel is reduced.

Air-permeable resin layer (2) The air-permeable resin layer (2) refers to its oxygen permeability (ASTM D
-1434-75 measured in accordance with) the 30cc / 24hr · m ² · atm or less,
The resin layer is preferably 20 cc / 24 hr · m ² · atm or less.

As such a resin layer, an acrylonitrile component,
Examples include a layer formed from a polymer containing at least 50 mol% of a vinyl alcohol component or a vinylidene halide component. In particular, polyvinyl alcohol or a copolymer modified or grafted product thereof, a vinyl alcohol-based resin layer such as an ethylene-vinyl alcohol copolymer having an ethylene content of 15 to 50 mol%, and especially an ethylene-vinyl alcohol copolymer layer are preferable. is there.

The thickness of the air-permeable resin layer (2) is usually set in the range of 1 to 50 μm, preferably 2 to 20 μm. If the thickness is less than 1 μm, the air permeability is insufficient, and increasing the thickness more than necessary only increases the cost and has no industrial significance.

Crosslinked Resin Cured Product Layer (3) The crosslinked resin cured product layer (3) is preferably selected from phenoxy ether type crosslinkable resin, epoxy resin, acrylic resin, acrylic epoxy resin, melamine resin, phenol resin or urethane resin. It is composed of a cured product of a crosslinked resin obtained. A particularly preferred resin among the crosslinkable resins is a phenoxyether-type crosslinked polymer in which a polyfunctional compound is subjected to a crosslinking reaction with a hydrogen portion of a hydroxyl group of a phenoxyether-type polymer represented by the following general formula.

(Wherein, R ^{1 to} R ⁶ are each hydrogen, a lower alkyl group having 1 to 3 carbon atoms or Br, R ⁷ is a lower alkylene group having 2 to 4 carbon atoms, m is an integer of 0 to 3, n is 20 In addition, as a polyfunctional compound (crosslinking agent) to be reacted to obtain a crosslinked polymer, a group having a high reaction activity with a hydroxyl group, for example, an isocyanate group, a carboxyl group, or a carboxyl group may be used. Compounds having two or more of the same or different reactivity-inducing groups (for example, halides, active amides, active esters, acid anhydride groups, etc.), mercapto and the like can be mentioned.

The thickness of the crosslinked resin cured material layer (3) is usually 2 to 100 μm.
m, preferably in the range of 5 μm to 50 μm.

Laminated sheet (4) An air-permeable resin layer (2) is provided on at least one surface of the above-mentioned optically isotropic base material sheet layer (1) by a casting method, and is further cast on the air-permeable resin layer (2). The laminated sheet (4) is obtained by providing the crosslinked resin cured material layer (3) according to (1).

Therefore, the configuration of the laminated sheet (4) is as follows: the optically isotropic substrate sheet layer (1) / the air-permeable resin layer (2) / the crosslinked resin cured material layer (3), or the crosslinked resin cured material layer (3). ) / Air-permeable resin layer (2)
/ Photo-isotropic base sheet layer (1) / Air-permeable resin layer (2)
/ Crosslinked resin cured material layer (3).

The laminated sheet (4) having the above configuration typically has a water-based or alcohol-based anchor coat layer (ac) formed on one side of the optically isotropic substrate sheet layer (1) if necessary, and then has After casting a solution or dispersion of a gas-permeable resin from the above, drying it to form a gas-permeable resin layer (2), and then casting a solution or dispersion of a cross-linkable resin composition thereon. , Dried and cured to form a crosslinked resin cured material layer (3). When obtaining the laminated sheet (4) having the above configuration, each layer is similarly formed on the opposite surface of the optically isotropic substrate sheet layer (1).

As another method different from the above-mentioned laminating method, an air-permeable resin layer (2) is previously formed on a heat-resistant film such as a polyester film, and a cured cross-linkable resin layer (3) is further formed thereon. Next, the laminate of (2) / (3) is peeled off from the heat-resistant film, and one side or both sides of the optically isotropic substrate sheet layer (1) is bonded to the air-permeable resin layer (2) side with an adhesive. It is also possible to adopt a method of bonding by using.

The interface between the air-permeable resin layer (2) and the cured cross-linkable resin layer (3) is not sufficient to provide an adhesive layer. That is, if the crosslinked resin cured material layer (3) is formed of a phenoxy ether type crosslinked polymer and the gas permeable resin layer (2) is formed of a vinyl alcohol-based resin, the crosslinked resin cured material layer (3) This is because the cross-linking agent used in the formation also reacts with the functional group of the air-permeable resin layer (2), so that strong adhesion between the two layers is achieved.

Photo-isotropic laminate The photo-isotropic laminate of the present invention comprises two or more laminated sheets (4) obtained as described above, and a cured cross-linkable resin layer (3) formed with both outermost layers. It is configured to be adhered via an adhesive layer (ad).

That is, the laminated sheet (4) is bonded to the adhesive layer (a
If two pieces are pasted through d) When two sheets of the laminated sheet (4) are adhered via the adhesive layer (ad), Becomes

As the adhesive for forming the adhesive layer (ad), urethane-based adhesive, polyester-based adhesive, polyamide-based adhesive,
A curable resin adhesive such as an acrylic adhesive or an epoxy adhesive is used. In particular, it is preferable to use an adhesive capable of providing stiffness, such as an epoxy-based adhesive, and an ultraviolet-curable adhesive, which hardly causes bubbles to enter upon curing. In addition, as the adhesive for forming the adhesive layer (ad), a tacky adhesive or a pressure-sensitive adhesive is used, which initially has tackiness and changes into an adhesive over time to achieve permanent adhesion. You can also.

In the above (i), as the adhesive for forming the adhesive layer (ad), an adhesive using a solvent that does not affect the optically isotropic substrate sheet layer (1) is used. (I
In the case of i), since the crosslinked resin cured material layer (3) has resistance to most solvents, it is not necessary to pay particular attention.

Applications The optically isotropic laminate of the present invention is useful as an electrode substrate for a liquid crystal display panel, and can also be used for various recording devices, display devices, and the like.

In these applications, ITO and other transparent electrodes are provided on the surface of the optically isotropic laminate. For the formation of the transparent electrode, a vacuum deposition method, a sputtering method, an ion plating method, a metal spraying method, a metal plating method, a chemical vapor deposition method, a spray method, or the like is employed.

Functions and Effects of the Invention The optically isotropic laminate of the present invention having the above-described configuration is hardly curled because symmetry is maintained.

The crosslinked resin cured product layer (3), which is the outermost layer, has excellent scratch resistance, high hardness, good chemical resistance, and adheres to transparent electrodes such as ITO without special treatment. The sex is excellent.

The air-permeable resin layer (2) has excellent oxygen barrier properties and, when used as an electrode substrate for a liquid crystal display panel, greatly contributes to extending the life of the enclosed liquid crystal.

The crosslinked resin cured product layer (3) alone is brittle, and the air-permeable resin layer (2) alone may have moisture permeability by itself. However, since both layers are laminated in an adjacent state, the crosslinked resin The brittleness of the cured product layer (3) is compensated by the gas-permeable resin layer (2), and the moisture permeability of the gas-permeable resin layer (2) is compensated by the crosslinked resin cured material layer (3).

Since the optically isotropic laminate of the present invention has a configuration in which a plurality of laminated sheets (4) are adhered, the optically isotropic substrate sheet layer (1) having a small thickness and a small retardation value is used. Also, after attachment, it becomes thicker and more rigid, and obtains higher rigidity while keeping the retardation value smaller than when one thick optically isotropic substrate sheet layer (1) is used. be able to. Moreover, the adhesive layer (ad) to which the laminated sheet (4) is adhered can be selected from those having stiffness, so that the rigidity is further improved.

Therefore, when the optically isotropic laminate of the present invention is used as an electrode substrate for a liquid crystal display panel, the retardation value is small even for a large panel, and it has rigidity. There is no problem such as generation of a ring. In other words, performance comparable to that of a glass substrate can be obtained while utilizing the lightness and workability of the plastic substrate.

EXAMPLES Next, the present invention will be further described with reference to examples. Hereinafter, "parts" refers to parts by weight.

Example 1 FIG. 1 is a sectional view showing an example of the optically isotropic laminate of the present invention.

50μ thickness as an example of the optically isotropic substrate sheet layer (1)
m, an aqueous polyester urethane anchor coating agent was coated on one side of a polyarylene ester film having a retardation value of 9 nm, and then dried to form an anchor coat layer (ac) having a thickness of 2 μm.

Then, from above the anchor coat layer (ac), 20 parts of an ethylene-vinyl alcohol copolymer having an ethylene content of 32 mol%, 45 parts of water, 45 parts of n-propanol and methylolated melamine (Sumitec manufactured by Sumitomo Chemical Co., Ltd.) M-
3) A resin solution having a composition of 4 parts was cast and passed through a dryer at a temperature of 110 ° C. to be dried. This gives a thickness of 12
An air-permeable resin layer (2) having a thickness of μm was formed.

Next, from above the gas-permeable resin layer (2), 40 parts of a phenoxy ether resin, 40 parts of methyl ethyl ketone, 20 parts of cellosolve acetate, and a 75% by weight solution of an adduct of tolylene diisocyanate and trimethylolpropane (Nippon Polyurethane Co., Ltd.) After casting a resin solution having a composition of 40 parts and drying at 80 ° C. for 4 minutes,
By heating at 0 ° C. for 20 minutes, a crosslinked resin cured material layer (3) having a thickness of 10 μm was formed.

As a result, a laminated sheet (4) having the configuration of (1) / (ac) / (2) / (3) was obtained. The thickness of this laminated sheet (4) was 74 μm, and the retardation value was 8 nm.

An epoxy resin adhesive is applied to the (1) side of the laminated sheet (4) and dried to form an adhesive layer (ad) having a slight tack, and then the adhesive layer (a) is formed.
The (1) side of another laminated sheet (4) was press-bonded to the d) side, and then heated and cured.

Thereby, (3) / (2) / (ac) / (1) / (a
d) / (1) / (ac) / (2) / (3) was obtained. The thickness of this optically isotropic laminate is 158 μm, the retardation value is 16 nm, the visible light transmittance is 87%, and the oxygen transmittance (measured according to ASTM D-1434-75) is 0.1 cc / 24 hr · m ^2. -The pencil hardness of atm and the surface was 2H. The compressive strength (measured in accordance with JIS P 8126 “Testing method for compressive strength of paperboard”) as a measure of rigidity was 16.2 kgf.

Next, on the surface of one of the crosslinked resin cured product layers (3) of the above-mentioned optically isotropic laminate, a transparent electrode having a thickness of 500 ° made of ITO was formed by a sputtering method. The adhesion of the ITO layer was good even though no treatment was performed on the crosslinked resin cured material layer (3).

Example 2 FIG. 2 is a sectional view showing another example of the optically isotropic laminate of the present invention.

The formation of the anchor coat (ac), the air-permeable resin layer (2), and the cured cross-linkable resin layer (3) on the optically isotropic substrate sheet layer (1) is performed on both sides of the optically isotropic substrate sheet layer (1). Example 1 was repeated except that the test was performed for (3) /
A laminated sheet (4) having a configuration of (2) / (ac) / (1) / (ac) / (2) / (3) was obtained. The thickness of this laminated sheet (4) was 105 μm, and the retardation value was 9 nm.

An epoxy resin-based adhesive is applied to one side of the laminated sheet (4) and dried to form an adhesive layer (ad) having a slight tack, and then another sheet is provided on the adhesive layer (ad) side. The laminate sheet (4) was pressed and heated and cured.

Thereby, an optically isotropic laminate having the configuration of (4) / (ad) / (4) was obtained. This optically isotropic laminate has a thickness of 230 μm, a retardation value of 18 nm, a visible light transmittance of 85%, and a compressive strength (JIS P 8126) which is a measure of rigidity.
It was 24.5 kg f.

Comparative Example 1 The formation of the anchor coat layer (ac), the air-permeable resin layer (2), and the cured cross-linkable resin layer (3) on the optically isotropic base material sheet layer (1) was performed using the optically isotropic base material sheet layer (1). Example 2 was repeated except that the measurement was performed on both sides of (3)
A laminate having a configuration of (2) / (ac) / (1) / (ac) / (2) / (3) was obtained. However, the optically isotropic substrate sheet layer (1) has a thickness of 110 μm and a retardation value of 4
A 7 nm polyarylene ester film was used.

This laminate has a thickness of 162 μm and a retardation of 4
3 nm, the visible light transmittance was 85%, and the compressive strength (JIS P 8126) as a measure of rigidity was 12.3 kgf.

Comparative Example 2 As an optically isotropic base material sheet layer (1), a thickness of 180 μm,
Comparative Example 1 was repeated except that a polyarylene ester film having a retardation value of 72 nm was used.

The obtained laminate had a thickness of 240 μm, a retardation value of 68 nm, a visible light transmittance of 85%, and a compressive strength (JIS P 8126) as a measure of rigidity of 20.6 kgf.

Example 3 Example 1 was repeated, except that a polycarbonate film having a thickness of 60 μm and a retardation value of 12 nm was used as the optically isotropic substrate sheet layer (1), and a phenoxy ether resin which had been Br-modified was used as the phenoxy ether resin. Sheet (4) was obtained. The thickness of this laminated sheet (4) is 10
7 μm, and the retardation value was 7 nm.

An adhesive layer (ad) is formed by applying an epoxy acrylate resin-based ultraviolet curable adhesive to one side of the laminated sheet (4), and another laminated sheet (4) is formed on the adhesive layer (ad) side. ) Was pressed, and then irradiated with ultraviolet light from a high-pressure mercury lamp.

Thereby, (3) / (2) / (ac) / (1) / (a
d) / (1) / (ac) / (2) / (3) was obtained. This optically isotropic laminate has a thickness of 220 μm, a retardation of 13 nm, a visible light transmittance of 85%, and a compressive strength (JIS P 8126) which is a measure of rigidity.
It was 27.8 kg f.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the optically isotropic laminate of the present invention. FIG. 2 is a sectional view showing another example of the optically isotropic laminate of the present invention. (1) ... optically isotropic base material sheet layer, (2) ... air-permeable resin layer, (3) ... crosslinked resin cured material layer, (4) ... laminated sheet, (ad) ... adhesive Layer, (ac) ... anchor coat layer

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takashi Yamada 1-4-16 Nihonbashi Bakurocho, Chuo-ku, Tokyo Inside Fujimori Industry Co., Ltd. (56) References JP-A-1-50022 (JP, A) JP-A-Hei 1-50001 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1333

Claims (3)

(57) [Claims] An air-permeable resin layer (2) is provided on at least one surface of a photo-isotropic substrate sheet layer (1) having a retardation value of 20 nm or less by a casting method. )) Two or more laminated sheets (4) provided with a crosslinked resin cured product layer (3) formed by a casting method,
An optically isotropic laminate having a configuration in which a cured crosslinkable resin layer (3) is attached via an adhesive layer (ad) so as to be both outermost layers. 2. The optically isotropic laminate according to claim 1, wherein the adhesive layer (ad) is a layer of a curable resin adhesive. 3. The photoisotropic laminate according to claim 1, wherein the adhesive layer (ad) is a layer of an ultraviolet-curable resin adhesive.