JP3103638B2 - Polymer liquid crystal polyurethane and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel thermotropic liquid crystal polyurethane (hereinafter abbreviated as liquid crystal polyurethane).

[0002]

2. Description of the Related Art Since liquid crystalline polymer materials can be used in various fields as industrial materials, many attempts have recently been made to impart high functionality such as high strength and high elastic modulus. Thermotropic liquid crystal polymers have attracted attention as polymer materials that can be highly oriented, but can be broadly classified into two types. One is a main chain type liquid crystal polymer for the purpose of high strength and high elastic modulus, and the other is a side chain type liquid crystal polymer which can be applied to a recording material. Many of them relate to polyamides, polyesters and vinyl polymers, and very little research has been done on liquid crystal polyurethanes.
For example, Polymer Polymer Collection, Vol. 43, No. 5, p. 311-314 (198
6). And Macromolecules, 22 , 1467 (1989). Research on liquid crystal polyurethane is described.

The liquid crystal polyurethanes described in and are polycondensation-type polymers containing a mesogen having a rigid structure and a flexible spacer in the main chain. Discloses a thermotropic liquid crystal polyurethane having a relatively low molecular weight. The intrinsic viscosity of the polymer is about 0.2 dl / g, which is not a satisfactory value. Especially 4,4'-di (2
It has been reported that the reaction of (hydroxyethoxy) biphenyl with 1,4-phenylene diisocyanate resulted in precipitation of the product during the course of the reaction, which was insoluble in organic solvents. Also, for the first time, a high-molecular liquid crystal polyurethane is described. Specifically, a biphenyl group as the central core, as a spacer, -O- (CH _{2) m} - chain, each containing, using 4,4'-bis (6-hydroxy-hexyloxy) biphenyl as the diol component, 2, Liquid crystal polyurethane is synthesized by polyaddition reaction with 4-toluene diisocyanate. However, polyurethane having an intrinsic viscosity of 0.32 dl / g has liquid crystallinity, but has an intrinsic viscosity of 0.57 d / g.
It has been reported that clear liquid crystal properties cannot be seen in polyurethanes in the high molecular range of about l / g. These phenomena can be explained by interpreting that as the molecular weight of the polymer increases, the main chain of the polyurethane molecule bends, so that the intermolecular arrangement due to the interaction of mesogen groups weakens.

Incidentally, polyurethane is a urethane bond -NHCO
A polymer containing O- as a repeating unit, generally formed by a polyaddition reaction between a diol component and a diisocyanate component to form a foam, a paint, an adhesive, an elastomer,
It is an important industrial material used as a material such as synthetic leather.

[0005]

An object of the present invention is to provide a polyurethane obtained by a polyaddition reaction between a diol component and a diisocyanate component, which has a thermotropic liquid crystal property even in a certain polymer region or more. To develop a high-molecular liquid crystal polyurethane having excellent thermal and mechanical properties.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that bis (ω-hydroxyalkyleneoxy) biphenyl and 1,4-phenylene diisocyanate compound are used as raw materials. It has been found that the obtained polyurethane has thermotropic liquid crystallinity even in the polymer region. In addition, the present inventors have found that they have superior thermal properties, in particular, as compared with the polyurethane obtained using 2,5-toluene diisocyanate previously disclosed in JP-A-3-03045. That is, the present invention provides a repeating unit represented by the following general formula [I] (Formula 4)

[0007]

Embedded image (Wherein, m represents an integer of 3 to 20).
Further, the following formula [II] (Chem. 5)

[0008]

Embedded image (Wherein m represents an integer of 3 to 20) and bis (ω-hydroxyalkyleneoxy) biphenyl represented by the following formula [III] (Formula 6) and 1,4-phenylene diisocyanate

[0009]

Embedded image And a method for producing a liquid crystalline high molecular weight polyurethane represented by the formula [I].

The diol component used in the present invention has the formula [I
Bis (ω-hydroxyalkyleneoxy) biphenyl represented by the formula (I): 4,4′-biphenol and ω-bromo-1
-A compound obtained by reaction with hydroxyamylcan or the like. The compound represented by the formula [II] is specifically a compound wherein m of the methylene chain is 3 to 20, and 4,4 ′
-Bis (ω-hydroxypropyloxy) biphenyl,
4,4'-bis (ω-hydroxybutyloxy) biphenyl, 4,4'-bis (ω-hydroxypentyloxy) biphenyl, 4,4'-bis (ω-hydroxyhexyloxy)
Biphenyl, 4,4'-bis (ω-hydroxyheptyloxy) biphenyl, 4,4'-bis (ω-hydroxyoctyloxy) biphenyl, 4,4'-bis (ω-hydroxynonyloxy) biphenyl, 4,4 '-Bis (ω-hydroxydecyloxy) biphenyl, 4,4'-bis (ω-hydroxyundecyloxy) biphenyl, 4,4'-bis (ω-hydroxydodecyloxy) biphenyl, 4,4'-bis ( ω-
(Hydroxytridecyloxy) biphenyl, 4,4'-bis
(ω-hydroxytetradecyloxy) biphenyl, 4,
4'-bis (ω-hydroxypentadecyloxy) biphenyl, 4,4'-bis (ω-hydroxyhexadecyloxy)
Biphenyl, 4,4'-bis (ω-hydroxyheptadecyloxy) biphenyl, 4,4'-bis (ω-hydroxyoctadecyloxy) biphenyl, 4,4'-bis (ω-hydroxynonadecyloxy) biphenyl, 4 , 4'-bis (ω-
(Hydroxyeicosyloxy) biphenyl and the like.

The melting point of 4,4′-bis (ω-hydroxyalkyloxy) biphenyls tends to decrease as the number of methylene chains increases.
It is preferable to use diols represented by Nos. To 15 as a raw material of the liquid crystal polyurethane. The bis (ω-hydroxyalkyleneoxy) biphenyl represented by the formula [II] is not necessarily reacted with only one kind, but may be reacted with two or more kinds as needed. Also, the formula (II)
In the compound represented by the unsubstituted biphenyl group -CH ₃ group, -O
A method of lowering the melting point of the target polymer by introducing a CH ₃ group, halogen, or the like can be considered.
The object was achieved by changing the number of methylene chains represented by the formula [II]. These are general phenomena observed also in thermotropic polyester and the like.

Further, 1,4-phenylenediisocyanate represented by the formula [II] is a compound which can easily have a high orientation from the viewpoint of a steric structure, and is a compound which can impart high functionality such as heat resistance. . 1,4-Phenylene diisocyanate can be produced according to the method described in Ann., 562, 75 (1948).

The present inventors have proposed formulas [II] and [III] as means for solving the problems of the liquid crystal polyurethane described above.
The compound represented by formula (1) is subjected to a polyaddition reaction, thereby enabling the synthesis of a polyurethane exhibiting liquid crystallinity even in a polymer region. As a method for synthesizing the high-molecular liquid crystalline polyurethane of the present invention, a 1,4-phenylenediisocyanate represented by the formula [III] and a diol component represented by the formula [II] are used in a ratio of 0.8: 1.
The reaction is carried out in a proportion corresponding to an NCO / OH equivalent ratio of from 1.2 to 1.2: 1, preferably in a proportion corresponding to an NCO / OH equivalent ratio of 0.9: 1 to 1.1: 1, more preferably using an equivalent of starting material. However, it is not limited to these. In the case of the polyaddition reaction, if necessary, a general urethanization catalyst such as dibutyltin dilaurate can be added. Further, the polymerization reaction is preferably performed in the presence of a suitable solvent, for example, a polar solvent such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, tetramethylurea, anisole, dioxane, or a mixture of these solvents. The reaction temperature is 20 to 200 ° C, preferably 60 to 160 ° C. The reaction is usually completed in about 4 to 24 hours.

After the completion of the reaction, the reaction product is cooled, and then the reaction is stopped by adding a ketone such as acetone, an ether such as diethyl ether, or a diluting solvent such as methanol, and the reaction product is precipitated. The liquid crystal polyurethane is obtained by collecting and separating the liquid crystal polyurethane. The liquid crystal polyurethane is separated by a purification method such as a reprecipitation method or a column separation to separate unreacted substances and the like. Thereafter, the polymer liquid crystal polyurethane of the present invention is obtained by drying. The intrinsic viscosity [η] of the solvent-soluble polyurethane thus obtained is about 0.5
It is in the range of ~ 0.7 dl / g.

Next, for the purpose of grasping the physical properties of the polyurethane, various studies were conducted on the polymer synthesized according to the above-mentioned method by wide-angle X-ray diffraction, differential scanning calorimetry and the like. As a result, once the polymer synthesized according to the method described above was made into an isotropic fluid and allowed to cool to a solid state, and then subjected to wide-angle X-ray diffraction at room temperature, a clear peak was observed. The polymer was found to be quite crystalline. In addition, as a result of performing differential scanning calorimetry (hereinafter abbreviated as DSC), an endothermic peak (abbreviated as T _m ) corresponding to melting was obtained for each of the polymers during the heating process.
It was found that an endothermic peak (abbreviated as T _i ) based on the transition to the isotropic fluid phase appeared, and an exothermic peak appeared during crystallization from the isotropic fluid state in the temperature decreasing process. Of these transition states, melting and endothermic phenomena can also be observed with a polarizing microscope.
From these results, all polymers show mesophases,
It became clear that it was a thermotropic liquid crystal polyurethane. It is also surprising that the liquid crystal polyurethane of the present invention has an extremely high intrinsic viscosity [η].

[0016]

EXAMPLES The present invention will be described more specifically with reference examples and examples. However, the present invention is not limited to these specific examples. Reference Example 1 Synthesis of 4,4′-bis (ω-hydroxyalkyleneoxy) biphenyls 4,4′-bis (ω-hydroxyalkyleneoxy) biphenyl (D) having 3, 5, 6, 8, and 11 methylene groups
HPRB, DHPEB, DHHB, DHOB and DHU
B) was synthesized as shown in the formula [a].

[0017]

Embedded image

DHOB will be described as a typical synthesis example. Sodium hydroxide (5.6 g, 0.140 mol) was dissolved in ethanol (80 ml), and 4,4'-biphenol (6.5
g, 0.035 mol) was added with stirring. After refluxing for 1 hour, 8-bromo-1-octanol (29.3 g,
(0.140 mol) was slowly added dropwise, and the reaction mixture was refluxed with stirring for 24 hours. After completion of the reaction, the content was cooled and put into water to form a precipitate, and the precipitate was filtered and washed with water. The crude product was purified by recrystallization three times from isopropanol in the case of DHPRB and DHPEB and from ethanol and DMF (3: 1) in the case of DHHB, DHOB and DHUB. The results of the synthesis are shown in Table 1 (Table 1).

[0019]

[Table 1]

Reference Example 2 Synthesis of 4,4'-bis (4-hydroxybutyleneoxy) biphenyl (DHBB) 4,4'-bis (4-hydroxybutyleneoxy) biphenyl (DHBB) was 4-chloro-1-butanol The compound was synthesized according to the route shown in formulas (b) to (d) (Chem. 8).

[0021]

Embedded image

3,4-dihydro-2-pyran (63 g, 0.78 mol)
Was cooled to 0 ° C. to give 4-chloro-1-butanol (50 g, 0.46
mol) and concentrated hydrochloric acid (0.5 ml) at room temperature.
Stirred for 20 hours. To this reaction solution was added sodium carbonate (5 g).
Was added, and the mixture was neutralized and filtered. The reaction product is distilled under reduced pressure.
(bp 108-109 ° C / 8 Torr). 63% yield
(56.0 g). 4,4 '-(Tetrahydro-2-pyranyloxybutyloxy) biphenyl is 4- (tetrahydro-2-
(Pyranyloxy) -1-chlorobutane (56.06 g, 0.29 mol)
And 4,4'-biphenyldiol (27.1 g, 0.145 mol) in the same manner as in the synthesis of DHOB. 45% yield
(32.3 g). This product (32.0 g, 0.064 mol) was dissolved in hot methanol, concentrated sulfuric acid (5 ml) was added, and the mixture was stirred under reflux for 0.5 hour. The reaction was cooled, the precipitate was filtered, and the resulting crude product was washed with ethanol followed by water and finally purified by recrystallization from isopropanol.

Example 1 In a 100 ml three-necked round bottom flask equipped with a reflux tube, 4,4'-bis (ω-hydroxyhexyloxy) biphenyl (DHH) was added.
B) 1.415 g (3.663 mmol), 1,4-phenylene diisocyanate (1,4-PDI) 0.586 g (3.663 mmol) and 15 ml of anhydrous DMF as a solvent were added thereto.
The reaction was performed at 80 ° C. for 20 hours. After the reaction, DMF is added to the product.
30 ml was added and the mixture was poured into 150 ml of methanol to obtain a precipitate. The resulting precipitate was thoroughly washed with methanol,
It was dried under reduced pressure at 70 ° C. for 24 hours. The structure of the obtained polymer is
As a result of analysis by ¹ H-NMR and infrared spectrum, 1,4-PDI
And DHHB as a reaction product. The thermal and liquid crystal properties were examined by DSC and polarizing microscope, and the melting point of the polymer during the heating process was determined.
(Hereinafter abbreviated as _Tm ) and the transition point to the isotropic fluid phase (hereinafter referred to as _Tm ).
T _i abbreviated) it was found that each is in a 237 ° C. and 251 ° C.. In the cooling process, an exothermic peak due to crystallization was measured at 221 ° C. Further, once the isotropic fluid was allowed to cool to a solid state and then measured at room temperature by a wide-angle X-ray diffraction method, 2θ = 18.5
Clear diffraction peaks were observed at °, 22.5 ° and 25.5 °. Further, it was found that the liquid crystal polyurethane had a crystallinity of 78% and was extremely rich in crystallinity.

Examples 2 to 6 In the same manner as in Example 1, 1,4-PDI and 4,4′-bis (ω-
(Hydroxyalkyleneoxy) biphenyl derivative. Table 2 (Table 2) and Table 3 (Table 3) show the synthesis conditions of the obtained polyurethane and various physical properties as a high-molecular liquid crystal polyurethane.

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

The polyurethane obtained according to the present invention is a polyurethane having liquid crystallinity containing a mesogen having good orientation. From this, in addition to the polyurethane resin modifying material, alone or as a composition, film, fiber,
It is easy to mold and process into various forms such as thin films.
A wide range of modification is possible by applying a general modification method for a polymer substance such as copolymerization, blending with other components, or alloying.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 18 / 32,18 / 76 C09K 19/38

Claims (2)

(57) [Claims] [Claim 1] The following general formula [I] (Chemical formula 1) (Wherein, m represents an integer of 3 to 20). 2. The following formula [II] (Chem. 2) (Wherein m represents an integer of 3 to 20) and a bis (ω-hydroxyalkyleneoxy) biphenyl represented by the following formula [III]: 2. The method for producing a liquid crystal polymerized polyurethane having liquid crystallinity according to claim 1, wherein 1,4-phenylene diisocyanate represented by the following formula is reacted.