JP2007023132A - Liquid crystalline polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystalline polyester excellent in heat resistance, flame retardancy, and melt-molding properties. <P>SOLUTION: This liquid crystalline polyester comprises a component (1) which is represented by a mixture of 1,4-cyclooctylphosphonyl-1,4-benzenediol and 1,5-cyclooctylphosphonyl-1,4-benzenediol, a component (2) expressed by: -OC-Ar<SP>1</SP>-CO-, and a component (3) expressed by: -O-Ar<SP>2</SP>-CO-, wherein a mol ratio of the component (1) to the component (2) is substantially unity, a mol ratio of the component (1) to the component (3) is in a range of 5/95 to 95/5, and Ar<SP>1</SP>and Ar<SP>2</SP>are each a bivalent aromatic group, may be identical to or different from each other, and may each have a substituent in its aromatic ring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystalline copolyester excellent in heat resistance, flame retardancy and melt moldability.

  Conventionally, aromatic polyesters are known as heat resistant polymers. However, most of the aromatic polyesters are difficult to process and have limited applications.

  In general, aromatic polyesters are said to be excellent in flame retardancy, but the critical oxygen index described later is about 40 at most, and it is difficult to say that they are sufficiently flame retardant. The melt viscosity is high, and at the same time, it is extremely inconvenient because it must be processed at high temperature and pressure. In addition, exposure to high temperatures for a long time is not advantageous from the standpoint of polyester degradation, and is economically disadvantageous.

  Therefore, much attention has been paid to the development of liquid crystalline aromatic polyesters excellent in heat resistance, flame retardancy and melt processability, and many proposals have been made.

  For example, the specific polyester-containing aromatic diols, aromatic dicarboxylic acids and copolyesters from aromatic hydroxycarboxylic acids described in Patent Document 1 and Patent Document 2 have excellent heat resistance and flame retardancy and good melt processability Has been found to be. However, these copolyesters are still insufficient in heat resistance, and therefore copolyesters having higher heat resistance, excellent flame retardancy and melt processability have been demanded.

Japanese Patent Laid-Open No. 62-174228 Japanese Patent Publication No. 8-13880

  Under such circumstances, an object of the present invention is to provide a liquid crystalline polyester having excellent flame retardancy and melt moldability and higher heat resistance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that liquid crystallinity excellent in heat resistance, flame retardancy, and melt moldability when a specific amount of a structural unit represented by the following structural formula (1) is contained. The present invention was completed by finding a copolyester.

  The present invention achieves the above object, and the gist thereof is as follows.

  It is mainly composed of structural units represented by the following structural formulas (1) to (3), the molar ratio of (1) and (2) is substantially equal, and the molar ratio of (1) and (3) is 5/95. Liquid crystalline polyester in the range of ~ 95/5.

—OC—Ar ¹ —CO— (2)
—O—Ar ² —CO— (3)
[In the above structural formulas (1) to (3), A ¹ and A ² are alkyl groups or alkoxy groups, and may be the same group or different groups. Ar ¹ and Ar ² are divalent aromatic groups, which may be the same group or different groups, and the aromatic ring may have a substituent. ]

  According to the present invention, a novel liquid crystalline polyester having excellent physical properties as a heat-resistant and flame-retardant polymer is provided, and this polyester is used for applications requiring high heat resistance and flame retardancy. It is useful as a material for film, fiber and molding.

  Hereinafter, the present invention will be described in detail.

  The first structural unit constituting the polyester in the present invention is a phosphorus-containing aromatic diol residue represented by the structural formula (1).

  Specific examples of the phosphorus-containing aromatic diol residue include 1,4-cyclohexylphosphonyl-1,4-benzenediol, 1,4-cyclopeptyl-phosphonyl-1,4-benzenediol, and 1,4-cyclooctylphospho. Nyl-1,4-benzenediol, 1,4-cyclononylphosphonyl-1,4-benzenediol, 1,3-cyclohexylphosphonyl-1,4-benzenediol, 1,3-cyclopeptyl-phosphonyl-1, Examples include 4-benzenediol, 1,5-cyclooctylphosphonyl-1,4-benzenediol, 1,5-cyclononylphosphonyl-1,4-benzenediol, and mixtures thereof. -Cyclooctylphosphonyl-1,4-benzenediol and 1,5-cyclooctylphosphonyl-1,4-ben About 50:50 mixture of Njioru are sold under the trade name "CPHO-HQ" from Nippon Chemical Industrial Co., Ltd., is suitable industrially easily available.

  The second structural unit constituting the polyester is an aromatic dicarboxylic acid residue represented by the structural formula (2).

  Specific examples of the aromatic dicarboxylic acid include terephthalic acid (TPA), isophthalic acid (IPA), 4,4′-dicarboxydiphenyl, 2,6-naphthalenedicarboxylic acid, etc., and TPA and IPA are particularly preferable. It is appropriate to use TPA and IPA in a molar ratio of 100/0 to 0/100, preferably 100/0 to 50/50, and most preferably 100/0 to 70/30.

  The third structural unit constituting the polyester is an aromatic hydroxycarboxylic acid residue represented by the structural formula (3).

  Specific examples of the aromatic hydroxycarboxylic acid include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 3-phenyl-4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, and the like. Benzoic acid is preferred.

  The structural units (1) and (2) must be substantially equimolar, and if this requirement is not satisfied, a polyester having a high degree of polymerization cannot be obtained. The molar ratio between the structural units (1) and (3) is 5/95 to 95/5, preferably 10/90 to 80/20, and most preferably 15/85 to 50/50. If the molar ratio between the structural units (1) and (3) is less than 5/95, the flame retardancy is not improved, which is not preferable. On the other hand, if it is larger than 95/5, liquid crystal properties cannot be obtained, which is not preferable.

  The polyester of the present invention exhibits liquid crystallinity. Here, the liquid crystallinity is a property that when a solid polymer is heated under a polarizing microscope, the amount of transmitted light changes when the polymer melts.

  The polyester of the present invention is a polyester that has a flow initiation temperature of usually 330 ° C. or less and is easy to mold.

  The polyester of the present invention preferably has an intrinsic viscosity [η] of 0.5 or more, more preferably 0.6 to 5.0, optimally from the viewpoint of heat resistance and various physical and chemical properties. Is 0.7-3.0. If [η] is greater than 5.0, the melt viscosity becomes too high, and the moldability and fluidity may be impaired, which is not preferable.

  In the polyester of the present invention, a curing agent, various additives, pigments such as titanium oxide, zinc white, and carbon black, dyes, polyester resins, urethane resins, olefin resins, acrylics, as long as the effects are not impaired. Resins, alkyd resins, cellulose derivatives and the like can be blended. The polyester of the present invention can be blended with additives such as a pigment dispersant, an ultraviolet absorber, a release agent, a pigment dispersant, and a lubricant as necessary.

  Next, the manufacturing method of polyester of this invention is demonstrated.

  The polyester of the present invention can be produced according to a conventional method. For example, all monomer components and acetic anhydride are acetylated at 120 to 150 ° C. in an inert atmosphere, followed by esterification at 200 to 300 ° C., and further under normal pressure or reduced pressure, preferably 1. Examples thereof include a method in which a polyester resin is obtained by reacting at a temperature of 280 ° C. or higher for about 10 to 120 minutes under a high reduced pressure of 3 hectopascals or less and proceeding a polycondensation reaction until a desired molecular weight is reached.

  In the production of polyester, a polycondensation catalyst is usually used. As the polycondensation catalyst, one or more compounds selected from various metal compounds or organic sulfonic acid compounds can be used. .

    Hereinafter, the present invention will be described in more detail by way of examples.

    In addition, the measuring methods, such as a characteristic value in an example, are as follows.

(1) Elemental analysis
^It calculated | required from < ¹ > H-NMR analysis (The product made by a Varian, 300MHz).

(2) Intrinsic viscosity [η]
It calculated | required from the solution viscosity measured at 20 degreeC in the mixed solvent of phenol / 1,1,2,2-tetrachloroethane = 6/4 (mass ratio).

(3) Glass transition point Using 10 mg of polyester as a sample, using a DSC (Differential Scanning Calorimetry) apparatus (DSC7 manufactured by PerkinElmer Co., Ltd.), measurement was performed at a temperature increase rate of 10 ° C./min, and the resulting temperature increase curve An intermediate value of two bending point temperatures derived from the glass transition in the middle was determined, and this was taken as the glass transition temperature (Tg). Tg is preferably 160 ° C. or higher.

(4) Flow start temperature Using a flow tester (CFT-500 type manufactured by Shimadzu Corporation), a die having a diameter of 0.5 mm and a length of 2.0 mm, a load of 9.8 MPa (100 kgf / cm ² ), and an initial temperature of 200 The temperature was increased from 10 ° C. at a rate of temperature increase of 10 ° C./minute, and the temperature (Tf) at which the polymer began to flow out of the die was obtained. When Tf was 300 ° C. or higher, it was judged that there was heat resistance.
(5) Flame retardance Based on JIS K7201 standard, LOI (limit oxygen index) was measured about the sample of thickness of 1/16 inch. When the LOI was 50 or more, it was judged to be flame retardant.
(6) Liquid crystallinity It confirmed with the Leitz polarizing microscope with a hot stage. When a polymer in a solid state was subjected to temperature under a polarizing microscope, the change in the amount of transmitted light when the polymer melted was indicated as ◯ when the liquid crystallinity was present, and the case where it did not change was indicated as ×.

Example 1
To the reaction apparatus, CPHO-HQ, TPA, 4-hydroxybenzoic acid (POB) and acetic anhydride (Ac ₂ O) manufactured by Nippon Chemical Industry Co., Ltd. were charged in a molar ratio of 30: 30: 70: 156 as a catalyst. 4 × 10 ⁻⁴ mol of tin octylate was added to 1 mol of the ester bond of the produced polyester (theoretical amount), and the mixture was reacted in a nitrogen atmosphere at 140 ° C. for 2 hours while mixing. This reaction product was further reacted under normal pressure at 200 ° C. for 2 hours and further at 280 ° C. for 2 hours. Thereafter, the reaction was carried out under reduced pressure and elevated temperature, and finally the reaction was carried out under reduced pressure of 320 ° C. and 1.3 hectopascal or less for 2 hours to obtain a polyester of [η] 1.5.

  The obtained polyester was a liquid crystalline polyester having a Tg of 175 ° C. and a Tf of 312 ° C. and high heat resistance.

  The infrared absorption spectrum of this liquid crystalline polyester is shown in FIG.

  The results of elemental analysis of this polyester by NMR measurement are as follows: C = 68.0% (theoretical value 68.0%), H = 4.5% (theoretical value 4.5%), O = 22.9% (Theoretical value 22.9%) and P = 4.6% (theoretical value 4.6%).

Examples 2 to 5, Comparative Examples 1 and 2
In Example 1, polyester was obtained by performing the same operation as Example 1 except having changed the ratio of CPHO-HQ, TPA (IPA), and POB as shown in Table 1.

Examples 1 to 5 are all liquid crystalline polyesters having Tg of 160 ° C. or higher, Tf of 300 ° C. or higher, heat resistance, LOI of 50 or higher, flame retardancy, and excellent melt moldability. there were.

  On the other hand, each comparative example had the following problems.

  In Comparative Example 1, since no POB was contained, liquid crystallinity was not shown, Tf was drastically lowered, and heat resistance was lowered.

  In Comparative Example 2, since no CPHO-HQ was contained, no improvement in flame retardancy was observed.

2 is an infrared absorption spectrum of the liquid crystalline polyester produced in Example 1.

Claims (5)

It is mainly composed of structural units represented by the following structural formulas (1) to (3), the molar ratio of (1) and (2) is substantially equal, and the molar ratio of (1) and (3) is 5/95. Liquid crystalline polyester in the range of ~ 95/5.
—OC—Ar ¹ —CO— (2)
—O—Ar ² —CO— (3)
[In the above structural formulas (1) to (3), A ¹ and A ² are alkyl groups or alkoxy groups, and may be the same group or different groups. Ar ¹ and Ar ² are divalent aromatic groups, which may be the same group or different groups, and the aromatic ring may have a substituent. ]   The liquid crystalline polyester according to claim 1, having an intrinsic viscosity of 0.5 or more.   The liquid crystalline polyester according to claim 1, which has a melting start temperature of 300 ° C or higher.   The liquid crystalline polyester according to claim 1, having a glass transition point of 160 ° C or higher. The liquid crystalline polyester according to claim 1, having a limiting oxygen index of 50 or more.