JPH06329749A - Liquid crystal polyurethane - Google Patents

Abstract

PURPOSE:To obtain a polyurethane which shows a liquid crystalline phase at the decomposition temperature or below by adopting a specified molecular structure having a biphenyl skeleton or a naphthalene skeleton. CONSTITUTION:The title polyurethane is one comprising repeating units of formula I wherein R<1> is lower methylene or a group of formula III; R<2> is lower methylene; and n is an integer of 1-50 and having a molecular weight of 5000-200000 or one comprising repeating units of formula II wherein R<3> is lower methylene; and R<2> and n are defined as in formula I, and having a molecular weight of 5000-200000.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to liquid crystalline polyurethanes.

[0002]

BACKGROUND OF THE INVENTION Polyurethane is widely used as a transparent conductive film, an organic semiconductor, an organic superconductor, a light and heat sensitive material in the electric and electronic industries, and in the fields of paints, fibers, synthetic leather and the like. In general, polyurethanes having functionality, especially those exhibiting liquid crystallinity, have been found, but due to high liquid crystal transition temperature or small liquid crystal temperature range, thermal decomposition occurs during melt processing. Or, it was not equipped with a function that can be used.

When a certain organic crystal is melted, it is called a liquid crystal that does not immediately become a liquid from the crystal but becomes a turbid liquid and then becomes a liquid only when heated. Liquid crystals used in electrical and electronic materials have optical properties (scattering, refraction interference, etc.), which are easily affected by electric and magnetic fields, have a wide liquid crystal temperature range, and have chemical properties. It is required to have stable stability.

However, most of the liquid crystal compounds industrially used to date are monomolecular compounds, and a chemically stable and rigid polymer liquid crystal polyurethane has not been known yet.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel polyurethane having a rigid and chemically stable biphenyl skeleton or naphthalene skeleton which exhibits a liquid crystal at a decomposition temperature or lower.

The polyurethanes of the present invention have the general formula

[0007]

[Chemical 3]

Polyurethanes having a repeating unit represented by the formula and having a molecular weight in the range of 5,000 to 200,000, and general formulas

[0009]

[Chemical 4]

Polyurethanes having a repeating unit represented by and having a molecular weight in the range of 5,000 to 200,000.

Polyurethanes represented by the above general formula (1) are represented by the formula

[0012]

[Chemical 5]

4,4'-bis (hydroxymethyl) biphenyl (hereinafter referred to as "BHB") represented by the general formula OCN-R ¹ -NCO (4) (wherein R ¹ is the same as above). Diisocyanates and α, ω represented by the general formula HO (R ² O) nH (5) (wherein R ² and n are the same as above).
-Produced by reacting a dihydroxy compound. Further, the polyurethanes represented by the above general formula (1) are represented by the formula

[0014]

[Chemical 6]

2,6-bis (hydroxymethyl) naphthalene represented by (BHN), diisocyanates represented by the general formula (4) and α, ω represented by the general formula (5). -Produced by reacting a dihydroxy compound.

Examples of the diisocyanates of the general formula (4) include ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate and hexamethylene diisocyanate (hereinafter referred to as "HDI"). ,), Peptamethylene diisocyanate, octamethylene diisocyanate,
2,4'-toluylene diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate (hereinafter "DDI"), 1,5-naphthalene diisocyanate (hereinafter "NDI"), etc. Can be mentioned.

As the α, ω-dihydroxy compound of the general formula (5), conventionally known compounds can be widely used. For example, polymers such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol have hydroxyl groups at both ends. A compound can be mentioned.

The proportions of BHB or BHN, diisocyanates and α, ω-dihydroxy compound used are not particularly limited, but are usually BHB or BHN1.
About 2 moles of diisocyanates relative to moles, α, ω
-It is preferable to use about 1 mol of the dihydroxy compound. The reaction is usually performed in a suitable solvent. Here, as the solvent, for example, toluene, benzene, o-dichlorobenzene, dimethylformamide, or the like may be used, but the above α, ω-dihydroxy compound may also be used as the solvent. The reaction is usually completed in about 2 to 48 hours under a temperature condition of about 80 to 300 ° C.

The polyurethanes represented by the general formulas (1) and (2) of the present invention thus produced are
It is isolated and purified by a conventional means such as a reprecipitation method.

[0020]

According to the present invention, there is provided a polyurethane having a rigid and chemically stable biphenyl skeleton or naphthalene skeleton, which exhibits liquid crystal.

[0021]

EXAMPLES The present invention will be further clarified with reference to the following examples.

Example 1 Polytetramethylene glycol-100 (Hodogaya Chemical Co., Ltd., PTG-100, average molecular weight Mn = 876)
1 mmol and 1 mmol of BHB were placed in a 20 ml three-necked flask, the atmosphere was replaced with nitrogen, and the mixture was heated to 200 ° C. with stirring to make the mixture uniform. Next, after cooling to room temperature and adding 1.025 mmol of DDI, the solvent o-dichlorobenzene 5 was added.
ml was added, and the atmosphere was replaced with nitrogen, followed by stirring at 180 ° C. After the solution in the reactor became uniform, 1.025 mmol of DDI was further added, the atmosphere was replaced with nitrogen, and the mixture was stirred at 180 ° C. for 24 hours. After the reaction was completed, the product was precipitated and purified using a large amount of methanol. The yield was 85%.

The polyurethane thus obtained (DDI-
The physical properties of BHB-PTG-100) are as follows.

Tm (liquid crystal transition temperature): 230 ° C. Ti (isotropic liquefying temperature): 292 ° C. Viscosity [η] (dl / g, 30 ° C. in dimethylformamide): 0.27 IR (film, cm ^{− 1} ): 3300 (-NH-), 2
950,1450,770 (-CH ₂ -), 1730
(C = O), 1590,800,440 ( -C 6 H
₄ -), 1520,1370,1240 (-CONH
_{-), 1100 (-CH 2 -O} -CH 2 - with) Example 2-13 corresponding appropriate starting materials, and treated in the same manner as in Example 1 to obtain a polymer shown in Table 1. The yield, Tm (° C.), Ti (° C.) and viscosity of the polymer are also shown in Table 1.

[0025]

[Table 1]

Claims (2)

[Claims] 1. A general formula: And has a molecular weight of 5,000 to 2
Polyurethanes in the range of 00000. 2. A general formula: And has a molecular weight of 5,000 to 2
Polyurethanes in the range of 00000.