JPS61275334A - Optically isotropic film - Google Patents

Abstract

PURPOSE:To improve the solvent resistance, surface smoothness, optical isotropy, transparency, etc., of an optically isotropic film, by forming it from a resin obtained from a specified hydroxyl group and/or amino group-containing compound and a specified isocyanate group-containing compound. CONSTITUTION:A film formed from an urethane bond and/or urea bond- containing resin obtained by a reaction between a compound (a) having at least two hydroxyl and/or amino groups in the molecule and a compound (b) having at least two isocyanate groups. Examples of compounds having hydroxyl groups among components (a) include polyethylene glycol, bisphenol A and glycerin, and examples of compounds having amino groups among them include diaminobiphenyl and ethylenediamine. Examples of components (b) include 2,4-tolylene diisocyanate and 4,4'-diphenylmethane diisocyanate.

Description

[Detailed description of the invention] The present invention relates to an optically isotropic film made of fat.

[Conventional technology]

In recent years, calculators, digital watches, pocket computers, etc. have become increasingly smaller, and as a result, it has become necessary to make liquid crystal display cells thinner. Conventional.

Glass plates with excellent chemical resistance, rigidity, heat resistance, liquid crystal resistance, and optical isotropy have been used in liquid crystal display cells, but glass plates have poor flexibility and break easily, causing cell damage. There are limits to thinning. Therefore, plastic films are being considered as a substitute for glass. Examples include films made of thermoplastic resins such as hard polyvinyl chloride, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, and polyether sulfone. but.

Since these thermoplastic films are usually formed by extrusion, they have the disadvantage of being poor in surface smoothness and optical isotropy. Additionally, thermoplastic resins generally have poor solvent resistance.

On the other hand, by using the casting method, high molecular weight phenoxy ether resin is cross-linked with incyanate groups, etc.
A film with excellent chemical resistance and optical isotropy has been developed (Japanese Unexamined Patent Publication No. 154753/1983). However, high molecular weight phenoxy ether resins are difficult to dissolve, and a large amount of organic solvent is required to obtain a solution with a viscosity suitable for casting, which increases production costs and is not practical.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a film that has improved solvent resistance, surface smoothness, optical isotropy, transparency, etc., which are disadvantages of conventional thermoplastic films.

[Means for solving problems]

As a result of intensive studies to solve the above problems, the present inventors have discovered that a compound with a weight average molecular weight of 5000 or less that has at least two or more hydroxyl groups and/or an amino group in the molecule, and a compound that has at least two or more hydroxyl groups and/or amino groups in the molecule and a If a compound having an isocyanate group is used, a resin film having urethane bonds and/or urea bonds can be formed without solvent or with a relatively small amount of solvent, and the resulting film has excellent properties such as solvent resistance, surface smoothness, rigidity, The present invention was achieved based on the discovery that it has excellent transparency and optical isotropy.

That is, 1 the present invention is directed to at least one compound having a weight average molecular weight of 5, which has two or more hydroxyl groups and/or amino groups in the molecule.
000 or less and a compound having at least two or more incyanate groups, characterized by solvent resistance, rigidity, surface smoothness, and transparency. It is an optically isotropic film with excellent properties such as:

The optically isotropic film made of a resin having a urethane bond and/or a urea bond in the present invention contains a compound having a weight average molecular weight of 5,000 or less and having at least two or more hydroxyl groups and/or amino groups in the molecule; It is obtained by reacting a compound having two or more isocyanate groups with a compound having two or more isocyanate groups.

Examples of compounds having two or more hydroxyl groups in the molecule and having a weight average molecular weight of 5,000 or less include polyethylene glycol and polypropylene glycol.

catechol, regulcil, todro+/n, 4°4'
-Hydroxyphenylmethane, bisphenol A, glycerin, trimethylolpropa/, hexanetriol, trimethylolethane, trinotyrolpropta/, pentaerythritol, 2,3°-tetrahydroxy-1-
Other examples include pentanol, rilubitoll, and sucrose. Also.

A polyether polyol with a hydroxyl group at the end.

Polyester polyols and basic polyols can also be used as long as they have a weight average molecular weight of 5,000 or less.

Examples of polyether polyols having a hydroxyl group at the terminal include those obtained by addition polymerization with a compound containing a cyclic ether group such as ethylene oxide, propylene oxide, or tetrahydrofuran using the compound having the hydroxyl group as an initiator. Examples of polyester polyols having a hydroxyl group at the terminal include those obtained by ester polymerization of a metal compound having a hydroxyl group and a dicarboxylic acid. As a dicarboxylic acid.

Examples include malonic acid, succinic acid, geltaric acid, sheric acid, sebacic acid, dimerized sulfuric acid, maleic acid, adipic acid, phthalic acid, and oxalic acid. Examples of basic polyols having a hydroxyl group at the terminal include addition with a compound having a cyclic ether group using an amine such as ethylenediamine, benzenesulfonamide, 2-aminoethanol, N-methyljetanolamine, or diethylenetriamine as an initiator. Examples include those obtained by polymerization.

Examples of compounds having a weight average molecular weight of 5,000 or less and having two or more amine groups in one molecule include diaminopiphenyl, 2,4-pyridinediamine, ethylenediamine, and diethylenetriamine.

1.6.12-dodecanetriamine, 1,6.11-labcantriamine, 1.5.10-decanetriamine,
Examples include 1,5,9-nonanetriamine, 2,4-tolylene diamine, metaxylylene diamine, 1゜5-s7tylene diamine, 4,4'-diphenylmethanediamine, and condensed amines represented by the following formula. It will be done.

(In the formula, n is 0 to 36.) If the molecular weight exceeds 5000, the viscosity will be high when used as a film, and good casting will not be possible as it is, and a large amount of solvent will be required. Undesirable.

Examples of compounds having two or more isocyanate groups in the molecule include 2.4-tolylene diisocyanate, 4.
4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate.

Examples include hexamethylene diisocyanate, metaxylylene diisocyanate, dianisidine diisocyanate, tridene diisocyanate, 2,6-ditucyanate mercaproate, inphorone diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenylisocyanate, polymeric isocyanate, etc. . Further, adducts (modified products) obtained by reacting the above-mentioned incyanate group-containing compound with water or the aforementioned compounds having a hydroxyl group and/or a slight amino group can also be used.

In general, for combinations of compounds having a hydroxyl group and/or amino group and compounds having an incyanate group, when either one has trifunctional or higher functionality, the crosslinking density is high, and various physical properties such as solvent resistance and rigidity are is more preferable because it improves the crosslinking density.Also, if the density of aromatic rings in the resin having urethane bonds and/or urea bonds is increased by using a compound having an aromatic ring in one molecule in addition to these functional groups, the crosslinking density can be lowered ( However, it is possible to improve the rigidity.

The compounding ratio of a compound having a hydroxyl group and/or an amino group to a compound having an incyanate group is such that the ratio of the incyanate group to the hydroxyl group and/or amino group is 1:
It is desirable that the range is from 1.2 to i:o,s. Outside this range, a decrease in stiffness is seen.

Furthermore, if the reaction rate is slow, it is preferable to add a catalyst. As the catalyst, a typical catalyst for thermosetting urethane can be used. For example, triethylamine, triethylenediamine, stannath octoate, cyphthyl-tin di-2-ethylhquinoate, diptyl-tin-dilaurate, lead octylate, potassium oleate, tetra(2-ethylhexyl) titanate, stannic chloride, stannous chloride. Examples include diiron, d-s7thenate, and cobalt 2-ethylhexoate.

In forming the optically isotropic film of the present invention, addition of a small amount of solvent is unnecessary or sufficient. Usable solvents include hydrocarbons and esters.

Examples include ketone solvents, ether solvents, and mixed solvents thereof. Preferably, the raw material monomer is easily dissolved;
In addition, the use of a solvent with a slow evaporation rate results in less foaming during heat curing, resulting in a better film. Examples include toluene, xylene, cellosolve acetate, dimethylformamide, and the like.

The method for forming the optically isotropic film of the present invention is as follows.

A conventionally known casting method is used. That is,
A compound having a hydroxyl group and/or an amino group and a compound having an incyanate group are continuously weighed, defoamed and mixed, and then coated on a release-treated substrate to a thickness of 10 to 500 μm and cured by heating.

Examples of the substrate include metal plates, polyethylene terephthalate films, and polypropylene films.

Examples of coating methods include methods using a bar coater, doctor coater, reverse coater, extrusion coater, kiss coater, and the like.

□ As for heat curing conditions, heating at 60 to 200°C for 6 to 120 minutes is sufficient, but it is preferable to adjust the temperature to 80 to 150°C for 6 to 20 minutes by adding a catalyst. preferable. moreover.

At the beginning of heat curing, the temperature is 40-100℃, and at the end of heat curing, the temperature is 1
It is preferable to set the temperature gradient so that the temperature is between 20 and 200°C, since this prevents foaming.

If the curing speed is slow, touch the film surface with your finger until it has cured to the extent that no mold remains.

It is also possible to wind up the film continuously or to post-cure by cutting the film and placing it in one layer at room temperature or above room temperature until sufficient rigidity and chemical resistance are achieved.

Also, residual solvent in the film lengthens the post-curing time.

Therefore, it is more preferable to form a film without a solvent or to post-cure under reduced pressure.

Since the compound having a hydroxyl group and/or amine 7 group used in the present invention has a weight average molecular weight of 5,000 or less, it generally has a low viscosity (there is no need to dilute it with a solvent during casting. Since the molecular weight is low even when the molecular weight is required, it is sufficient to add a small amount of solvent, and it is possible to provide a film that is cheaper than the casting method of high molecular weight raw materials, which requires a large amount of solvent to be added.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the measured values in Examples and Comparative Examples were measured by the following method.

(1) Glass transition temperature Rheopipron DDV-2-E manufactured by Toyo Baldwin Co., Ltd.
Using A, the imaginary elasticity was measured at 110 Hz, and the peak temperature was taken as the glass transition temperature.

(2) Birefringence (optical isotropy) The retardation value R of the sample was measured using a precision strain meter 5VP-30 manufactured by Toshiba.

(3) Chemical resistance The film was immersed in various inorganic and organic chemicals (see Table 1) for 5 minutes, and the solubility and shape change of the film were visually observed. ○: No change, ×: Dissolution or whitening.

(4) Liquid Crystal Resistance Liquid crystal ZLI-1132 manufactured by Merck & Co., Ltd. was applied to the surface of the film and left at room temperature for one week to observe changes in the shape of the film. O: No change, X: Dissolution or whitening.

(5) Transparency A haze meter TC-H3 manufactured by Tokyo Denshoku ■ was used.

The total light transmittance of the sample was measured.

Example 1 Biuret-modified product of hexamethylene diisocyanate (
NPI100 manufactured by Mitsui Toatsu Chemical, Incyanate content 2
3% 1 molecular weight 540) 59.3F.

Addition polymer product of pentaerythritol and polypropylene oxide (Mitsui Nisso Tsureta 7 @ JMPE450゜KOH
Value: 4501 Weight average molecular weight: 748) 40.7f, Selonlupu Acetate 25. OF, 0.15y of lead octylate with a lead content of 40% by weight as a catalyst, and silicone oil (YF3910 manufactured by Toshiba Silicone ■) as a leveling agent.
) 11 was mixed and cast onto a polyethylene terephthalate film treated with silicone (mold release treatment) so that the film thickness after drying was 100 μmK, and cured for 9 minutes in a curing oven with a temperature gradient set from 60°C to 130°C. After that, it was continuously wound up and left in a constant temperature bath set at 45° C. for 48 hours, and then cured. Table 1 shows the physical properties of the obtained film.

Example 2 Biuret-modified product of 2.4-tolylene diisocyanate (P49-75-8 manufactured by Mitsui Toatsu Chemical Co., Ltd., incyanate content 12% 1 molecular weight 700) 66.2f, addition polymerized product of bisphenol A and propylene oxide ( Mitsui Toatsu Chemical ■KB300.OH value 3151 Weight average molecular weight 35
7) 33.8y, cellosolve acetate 45. (1. Lead octylate (lead content 40% by weight) 0.9F and silicone oil i, op were mixed and a film was obtained in the same manner as in Example 1. Post-curing was performed at 100°C for 1 hour. .Table-1 shows various physical properties.

Example 3 Biuret modified product of hexamethylene diisocyanate
NPIloo"31.9F, addition polymer product of bisphenol A and propylene oxide" K B500"31,
sg, lead octylate 0.29 and silicone oil 1
．． A film was obtained in the same manner as in Example 1. Post-curing was performed at 100° C. for 1 hour. Table 1 shows various physical properties.

Example 4 “Biuret modified product of hexamethylene diisocyanate”
NPlloo"64.6f, 4.4'-diaminodiphenylmethane (amine group content 16.1% by weight 1 molecular weight 19
8) 35.4F, xylene 50.09 and silicone oil 1. A film was obtained in the same manner as in Example 1. Post-curing was carried out at 100°C for 1 hour. Table 1 shows the physical properties of Example 5: Biuret-modified product of hexamethylene diisocyanate.
NP1100”85.6F, 2-aminoethanol (O
H value 720, amino group content 26.3% by weight, molecular weight 61
) 14.4F, lead octylate (lead content 40% by weight) o,
sy and 1.0 y of silicone oil were mixed, and a film was obtained in the same manner as in Example 1. Post-curing is 10
The test was carried out at 0°C for 1 hour. Table 1c shows various physical properties.

Comparative Examples 1 and 2 Properties of a commercially available hard polyvinyl chloride film and a polycarbonate film (thickness 100 μm each) were measured in the same manner and are shown in Table 1. It is inferior to the urethane film of the present invention in terms of birefringence, transparency, and chemical resistance.

Comparative Example 3 “Biuret modified product of hexamethylene diisocyanate”
NPIloo"15.6'!, Pentaeris,
Addition polymerization product of propylene oxide to lid and -ru.
(KOH value 56.11 weight average molecular weight 6000) 84
．． 4g, Cellosolve Acetate 25, Of! As a catalyst, 0.15 g of lead octylate having a lead content of 40% by weight and 1.09 g of silicone oil were mixed, and a film was formed in the same manner as in Example 1. However, due to its high viscosity, the surface was rough, and birefringence and transparency were significantly lost. Post-curing was carried out at 45° C. for 48 hours. Table 1 shows various physical properties. However, it is less transparent.

No chemical resistance tests were performed.

Comparative Example 4 Biuret-modified product 15.6F of hexamethylene diisocyanate used in Comparative Example 3, addition polymerization product of propylene oxide to pentaerythritol 84, tg, lead octylate o with a lead content of 40% by weight as a catalyst, 15f, silicone When cellosolve acetate was added to a mixture of 1.0 g of oil until a viscosity comparable to that of Example 1 was obtained, 200 f was required. A film was formed using this solution in the same manner as in Example 1.

The obtained film had no problems in birefringence etc. as in Example 1, but it had a residual solvent amount of 10% and was sticky.
It was not practical.

〔Effect of the invention〕

The optically isotropic film of the present invention is made of a resin having urethane bonds and/or urea bonds.

It has superior optical isotropy and solvent resistance compared to conventional films made of thermoplastic resin, and is hardly affected by solutions in adhesives when assembled into liquid crystal cells, etc.

Furthermore, since the film is formed from relatively low molecular weight monomers, there is no need to add a solvent, or a small amount is sufficient, and production can be done at low cost.

Claims (1)

[Claims] 1. Urethane bonds and/or obtained by the reaction of a compound with a weight average molecular weight of 5000 or less having at least two or more hydroxyl groups and/or amino groups in the molecule and a compound having at least two or more isocyanate groups in the molecule An optically isotropic film comprising a resin having a urea bonding group.