JPH0813880B2 - Liquid crystalline block copolyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystalline block copolyester having improved toughness, heat resistance, flame retardancy, mechanical properties, and melt moldability.

(Prior Art) Conventionally, an aromatic polyester has been known as a heat-resistant polymer. However, most of aromatic polyesters are difficult to process, and their applications are limited.

Further, aromatic polyesters are generally said to have excellent flame retardance, but at the limiting oxygen index described below,
It is about 40, and it is difficult to say that it has sufficient flame retardancy.
Since it has a very high melting point and a high melt viscosity at the same time, it is extremely inconvenient because it must be processed at high temperature and high pressure. Further, long-term exposure to high temperatures is not a good idea from the viewpoint of polyester decomposition and is economically disadvantageous.

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

The present inventors have previously found that a specific phosphorus-containing aromatic diol,
We have found and proposed that copolyesters derived from aromatic dicarboxylic acids and aromatic hydroxycarboxylic acids have excellent heat resistance and flame retardancy, as well as good melt processability (JP-A-62-174228).

However, this copolyester has the drawbacks of low elongation and insufficient toughness.

(Problems to be Solved by the Invention) The present invention provides a liquid crystalline block copolyester which is improved in toughness of such an aromatic copolyester and is excellent in heat resistance, flame retardancy, mechanical properties and melt moldability. Is what you are trying to do.

(Means for Solving Problems) The present invention achieves the above object, and the gist thereof is as follows.
It is as follows.

Mainly composed of structural units represented by the following structural formulas, and the molar ratio of each structural unit is substantially the same as and, and and are 5/95/95/5. A block composed of polyester A and a block composed of polyester B which is mainly composed of a repeating unit represented by the following structural formula and which does not exhibit thermotropic liquid crystallinity by itself. A block composed of polyester A and a block composed of polyester B. A thermotropic liquid crystalline block copolyester with a weight ratio of 25/75 to 95/5 and an intrinsic viscosity of 0.5 or more.

-OC-Ar ² -CO- -O-Ar ³ -CO- -ORO-OC-Ar ⁴ -CO- [In the formula, Ar ¹ is a trivalent aromatic group, Ar ² , Ar ³ and Ar ⁴
Represents a divalent aromatic group, and R represents an alkylene group having 2 to 4 carbon atoms and / or a divalent aromatic group. However, the aromatic ring may have a substituent. The block copolyester of the present invention is a polyester that exhibits thermotropic liquid crystallinity and has a flow starting temperature of usually 300 ° C. or lower, which is very easy to mold, although it varies depending on the composition.

The thermotropic liquid crystallinity referred to in the present invention refers to the property that molecules of polyester are regularly arranged in one direction in the melt phase to form a liquid crystal called a nematic phase. It can be confirmed by technology.

The block copolyester of the present invention is a thermotropic liquid crystalline block copolyester composed of a block composed of polyester A which exhibits thermotropic liquid crystallinity alone and a block composed of polyester B which does not exhibit thermotropic liquid crystallinity alone. .

The first constitutional unit constituting the polyester A in the present invention is a phosphorus-containing aromatic diol residue represented by the above structural formula.

As the Ar ¹ in the structural formula, a benzene ring and a naphthalene ring are preferable, and the hydrogen atom of the aromatic ring in the structural formula is an alkyl group having 1 to 20 carbon atoms, an alkoxy group, an aryl group having 6 to 20 carbon atoms, or an allyloxy group. Alternatively, it may be substituted with a halogen atom.

Specific examples of the phosphorus-containing aromatic diol include compounds represented by the following structural formulas (a) to (d), and the compound (a) is particularly preferably used.

The second constitutional unit constituting the polyester A is an aromatic dicarboxylic acid residue represented by the above structural formula.

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

The third constitutional unit constituting the polyester A is an aromatic hydroxycarboxylic acid residue represented by the above structural formula.

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, but especially 4-hydroxybenzoic acid. Benzoic acid is preferred.

In the polyester A, it is necessary that the constitutional units and the constitutional units are substantially equimolar, and unless this requirement is satisfied, a block copolyester having a high degree of polymerization cannot be obtained. The molar ratio with the constitutional unit is 5/95 to 95/5, preferably 10/90 to 70/30, and most preferably 20/80 to 50/50.
If it is out of this range, various mechanical properties such as Izod impact strength of the obtained block copolyester will be deteriorated.

Next, the polyester B in the present invention has a repeating unit represented by the above structural formula and is a polyester composed of a diol component and an aromatic dicarboxylic acid component.

Specific examples of the diol include ethylene glycol, 1,4
-Butanediol, 2-butene-1,4-diol, hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, 2,2-bis (4'-hydroxyphenyl) propane,
Examples thereof include bis (4-hydroxyphenyl) methane and bis (4-hydroxyphenyl) ether, with ethylene glycol and 2,2-bis (4'-hydroxyphenyl) propane being particularly preferred.

TPA and IPA are preferred as the aromatic dicarboxylic acid.

In the block copolyester of the present invention, the weight ratio of the polyester A block to the polyester B block is 25/75 to 95/5, preferably 50/50 to 90/10, most preferably 60/40 to 80/20. If the proportion of the polyester A deviates from this range, the flame retardancy and melt moldability become poor. If the proportion of polyester A becomes large, the molded product warps or the toughness improving effect becomes insufficient.

Components other than the above may be copolymerized within a range that does not impair the effects of the block copolyester of the present invention.

The block copolyester of the present invention has an intrinsic viscosity [η]
Is required to be 0.5 or more, preferably 0.6 to 10.0,
The optimum value is 0.7 to 3.0. When [η] is less than 0.5, various physical, mechanical and chemical properties such as heat resistance are poor. If [η] is larger than 10.0, the melt viscosity becomes too high and the moldability and fluidity are impaired, which is not preferable in some cases.

Next, the method for producing the block copolyester of the present invention will be described.

The block copolyester of the present invention is prepared by separately charging polyester A and polyester B prepared by a conventional method into a reactor, and applying them under normal pressure or reduced pressure, preferably 10 Torr or less, and most preferably 1 Torr or less under high reduced pressure. It is obtained by reacting at 280 ° C or higher, preferably 280 to 320 ° C, optimally 300 to 320 ° C for 5 minutes or longer, preferably 10 to 120 minutes, optimally 15 to 60 minutes.

At this time, it is necessary to properly set the [η] of the polyester A and the polyester B used in the reaction.

That is, [η] of polyester A is 0.5 to 4.0, preferably 1.0 to 3.0, optimally 1.2 to 2.5, and [η] of polyester B is 0.3 to 2.0, preferably 0.5 to 1.8,
The optimum value is 0.8 to 1.5. When [η] of polyester A and polyester B is too small, various mechanical properties such as Izod impact strength of the obtained block copolyester are inferior, and when [η] is too large, compatibility of both polyesters is poor. As a result, a uniform block copolyester cannot be obtained.

A polycondensation catalyst is usually used in the production of polyester A and polyester B. As the polycondensation catalyst, one or more compounds selected from various metal compounds or organic sulfonic acid compounds are used. Can be used.

(Examples) Next, the present invention will be described in more detail with reference to Examples.

The method of measuring the characteristic values in the examples is as follows.

Intrinsic viscosity [η] It was calculated from the solution viscosity measured at 20 ° C in a mixed solvent such as phenol / ethane tetrachloride by weight.

Glass transition point Tg The temperature was measured with a differential scanning calorimeter (DSC-2 type manufactured by Perkin Elmer) at a temperature rising rate of 20 ° C / min.

Flow starting temperature Tf Using a flow tester (CFT-500 type manufactured by Shimadzu Corporation),
A die with a diameter of 0.5 mm and a length of 2.0 mm, with a load of 100 kg / cm ² ,
The temperature was raised from the initial temperature of 200 ° C at a rate of 10 ° C / min.
It was determined as the temperature at which the polymer started to flow out of the die.

Izod impact strength Measured with a notch at a thickness of 1/8 inch in accordance with IZ ASTM D256 standard. (Unit: kgf · cm / cm) Tensile strength and elongation at break Measured at a thickness of 1/8 inch according to ASTM D638 standard.

Flame retardant LOI Based on JIS K7201 standard, LOI (Limited Oxygen Index) was measured for a 1/16 inch thick sample.

The thermotropic liquid crystal is equipped with a hot stage
Confirmed with a Leitz polarization microscope.

Example 1 Production of Polyester A A reactor was charged with a phosphorus compound (PHQ), TPA,
IPA, 4-hydroxybenzoic acid (4HBA) and acetic anhydride (Ac ₂
O) in a molar ratio of 43: 36.5: 6.5: 57: 170, and dimethyltin maleate as a catalyst was added in an amount of 4 × 10 ^-4 mol per 1 mol of the ester bond of the produced polyester,
The reaction was performed under a nitrogen atmosphere at atmospheric pressure and 140 ° C. for 2 hours while mixing. The reaction product was further reacted under normal pressure at 200 ° C. for 2 hours and further at 280 ° C. for 2 hours. After that, the reaction was carried out under reduced pressure and temperature, and finally the reaction was carried out at 320 ° C. under reduced pressure of 1 Torr or less for 2 hours to obtain a thermotropic liquid crystalline copolyester of [η] 1.5.

(This copolyester is referred to as [A].) Production of polyester B Molar ratio of 1. in the esterification reactor in which bis- (β-hydroxyethyl) terephthalate and its low polymer are present.
A slurry of 6: 1 ethylene glycol and terephthalic acid was continuously supplied, and the residence time was 6 hours under normal pressure at 255 ° C.
An esterification reaction was performed to obtain an esterification product with a reaction rate of 95%.

The esterified product was transferred to a polycondensation reaction tank, and 2 × 10 ^-4 mol of antimony trioxide was added as a catalyst to 1 mol of the acid component, and the pressure was gradually reduced. A condensation reaction was performed to obtain polyethylene terephthalate with [η] 0.71.

(This polyester is referred to as [B].) Production of block copolyester [A] and [B] obtained by the above method are mixed in a weight ratio of 7
Mixing in a molten state at a temperature of 320 ° C at a ratio of 0:30,
The pressure was reduced to 0.5 torr in 10 minutes, and then the transesterification reaction was performed in the molten state for 30 minutes to obtain a block copolyester.

The block copolyester obtained was a thermotropic liquid crystalline block copolyester having good color tone and having the characteristic values shown in Table 1.

The infrared absorption spectrum of this block copolyester is shown in FIG.

The results of elemental analysis of this block copolyester were C = 67.4% (theoretical value 67.5%), H = 3.49% (theoretical value 3.54%).
%), P = 3.89% (theoretical value 3.84%).

Examples 2 to 7 Example 1 was repeated except that the ratio of [A] and [B] and the reaction time were changed as shown in Table 1.
Similarly to the above, a thermotropic liquid crystalline block copolyester having a good color tone was obtained.

 The characteristic values of the obtained copolyester are shown in Table 1.

Comparative Example An amorphous block copolyester was obtained in the same manner as in Example 1 except that the ratio of [A] and [B] was changed as shown in Table 1.

The characteristic values of the obtained block copolyester are shown in Table 1.

Examples 8 to 11 Thermotropic liquid crystallinity having a good color tone was obtained in the same manner as in Example 1 except that the charged molar ratio of the raw materials when producing the polyester A was changed as shown in Table 2. A block copolyester was obtained.

The characteristic values of the obtained block copolyester are shown in Table 2.

Examples 12 to 14 In Example 1, when polyester A was produced, P
A thermotropic liquid crystalline block copolyester having a good color tone was obtained in the same manner as in Example 1 except that the phosphorus compounds of the above formulas (b) to (d) were used instead of HQ.

The characteristic values of the obtained block copolyester are shown in Table 3.

Example 15 2,2-bis (4'-hydroxyphenyl) propane, TP
A, IPA, and Ac ₂ O were used in a molar ratio of 100: 50: 50: 220 in the same manner as in the production method of polyester A in Example 1, and the aromatic fragrance of [η] 0.7 showing no liquid crystallinity. A tricopolyester was obtained.

Using the copolyester in place of [B] in Example 1, a thermotropic liquid crystalline block copolyester having a good color tone was obtained in the same manner as in Example 1.

 The characteristic values of this block copolyester are shown below.

 [Η]: 1.22, Tg: 188 ℃, Tf: 278 ℃, IZ: 30.4, Tensile strength: 167MPa, Elongation: 19%, LOI: 57.

(Effects of the Invention) According to the present invention, a novel block copolyester having the following excellent physical properties as a heat-resistant and flame-retardant polymer is provided. Films used in applications requiring flammability,
It is useful as a fiber and material for molding.

(1) Since it has a specific phosphorus-containing structural unit in its side chain,
Not only does it not decompose even when used at high temperatures, but it also has a high degree of flame retardancy when formed into molded products.

(2) Since it is a thermotropic liquid crystalline block copolyester composed of a block composed of a polyester which exhibits thermotropic liquid crystallinity by itself and a block composed of a polyester which does not exhibit thermotropic liquid crystallinity by itself, a proper flow initiation It exhibits temperature, has excellent melt moldability, and has moderate elongation and improved toughness.

[Brief description of drawings]

FIG. 1 is a diagram showing an infrared absorption spectrum of the block copolyester obtained in Example 1.

Claims (1)

[Claims] 1. A thermostat composed mainly of structural units represented by the following structural formulas, wherein the molar ratios of the structural units are substantially equal to and, and and are 5/95 to 95/5. A block composed of a polyester A having a tropic liquid crystallinity and a block composed of a polyester B which is mainly composed of a repeating unit represented by the following structural formula and does not exhibit a thermotropic liquid crystallinity by itself, and a block composed of a polyester A. A thermotropic liquid crystalline block copolyester having a weight ratio of 25/75 to 95/5 with a block composed of polyester B and an intrinsic viscosity of 0.5 or more. -OC-Ar ² -CO- -O-Ar ³ -CO- -ORO-OC-Ar ⁴ -CO- [In the formula, Ar ¹ is a trivalent aromatic group, Ar ² , Ar ³ and Ar ⁴
Represents a divalent aromatic group, and R represents an alkylene group having 2 to 4 carbon atoms and / or a divalent aromatic group. However, the aromatic ring may have a substituent. ]