JP3146659B2 - Liquid crystalline polyester and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel liquid crystalline polyester and a method for producing the same. The liquid crystalline polyester of the present invention has an elastic modulus and strength not only in the resin flow direction (MD) but also in the direction perpendicular to the flow direction (TD), even without the addition of fillers such as glass fiber and carbon fiber. Is high, the coefficient of linear expansion in the MD and TD directions is small, and further, the anisotropy of those values is small.

[0002]

2. Description of the Related Art Many polymers have been developed and marketed as thermotropic liquid crystalline polymers. However, these liquid crystalline polymers are:
Fibers with high modulus of elasticity are given, but in the case of three-dimensional molded products such as injection molded articles, the molecular chains are highly oriented in the direction of flow of the polymer, so that the modulus of elasticity in the direction of flow is high, but is perpendicular to the direction of flow The elastic modulus in various directions is as low as that of other general (non-liquid crystalline) polymers, and therefore must be reinforced by the addition of glass fiber (GF) or carbon fiber (CF). Things are happening.

[0003]

However, when GF or CF is added, the impact strength is reduced or the surface roughness is deteriorated. In addition, since inorganic compounds are used, problems arise in selection during recycling. Therefore, attempts have been made to develop a single liquid crystalline polymer having a high elastic modulus in both the flow direction (MD direction) and the direction perpendicular to the flow direction (TD direction) of the polymer.

For example, as a wholly aromatic polyester, JP-A-59-124925 and JP-A-61-19627 are known.
JP-A-1-261418, JP-A-2-64123
And JP-A-3-188124. In addition, a polyfunctional component is copolymerized with a wholly aromatic polyester to obtain M
As an attempt to improve the physical properties in both D and TD directions,
27428, JP-A-2-238052, JP-A-3-
No. 152123, JP-A-152124, JP-A-3-
No. 168213. Also, Japanese Patent Application Laid-Open No. 2-53819
JP-A-3-47829 attempts to reduce anisotropy by introducing an optically active group.

However, these are: 1) low strength in both MD and TD directions; 2) low impact strength; 3) low flowability, which is a characteristic of liquid crystal polymers; 4) very high melting points, unless they are at a very high temperature. Molding is not possible. 5) The conventional vertical polymerization apparatus for producing polyester has a serious problem that it hardens or cannot be pulled out of the bottom of the kettle.

[0006] When a liquid crystal polymer is used for materials such as automobile materials and electric and electronic parts, it is required to have a heat resistance of 150-150.
It suffices that the molding temperature is 300 ° C., and it is considered that molding at 280 to 350 ° C. is preferable. In addition, it is considered that it is indispensable to be able to produce with a conventional vertical polymerization apparatus using a heat medium.

[0007]

Accordingly, as a result of intensive studies to solve all the problems 1) to 5), the liquid crystal having a specific composition and a specific composition ratio has a high elastic modulus in both the MD and TD directions. It has been surprisingly found that all of the above problems are solved by using a water-soluble polyester, and the present invention has been reached. That is, the gist of the present invention is a structural unit represented by the following formulas (1) to (4).

[0008]

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[0009] (1), (2), (3),
(4) The number of moles of the residue is [1], [2],
Assuming [3] and [4],

[0010]

0.8 <[1] / ([2] + [3] + [4]) ≦ 1.2 (I) 0.5 ≦ [2] / ([2] + [3] + [ 4]) ≦ 0.90 (II) 0.05 ≦ [3] / ([2] + [3] + [4]) ≦ 0.45 (III) 0.05 ≦ [4] / ([2] + [3] + [4]) ≦ 0.45 (IV), and a liquid crystalline polyester characterized by having a melt viscosity of 50 to 5000 poise at 320 ° C. and a shear rate of 10 ³ sec ^-1. Compounds represented by formulas (5) to (8),

[0011]

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Acetylation by reacting acetic anhydride with acetic anhydride, and then performing polycondensation at 325 ° C. or lower under reduced pressure. Hereinafter, the present invention will be described in more detail.

First, the ratio of (2) will be described.
0.5 ≦ [2] / ([2] + [3] + [4]) ≦ 0.9
It is. [2] / ([2] + [3] + [4]) <0.5
In the case of (1), the modulus of elasticity in both the MD and TD directions becomes low, which is not preferable. [2] / ([2] + [3] +
[4])> 0.9 is not preferable because polymerization at 325 ° C. or lower causes solidification and the polymer cannot be pulled out from under the polymerization vessel. Further, the elastic modulus in the TD direction becomes low. A more preferred range is 0.6 ≦
[2] / ([2] + [3] + [4]) ≦ 0.90.

The ratio (3) can be described as follows: 0.05 ≦
[3] / ([2] + [3] + [4]) ≦ 0.45. In the case of [3] / ([2] + [3] + [4]) <0.05, it is not preferable because the fluidity decreases and the moldability deteriorates. If [3] / ([2] + [3] + [4])> 0.45, the modulus of elasticity in the MD and TD directions decreases, which is not preferable. A more preferred range is 0.05 ≦ [3] /
([2] + [3] + [4]) ≦ 0.20.

The ratio of (4) is described as follows: 0.05 ≦
[4] / ([2] + [3] + [4]) ≦ 0.45. When [4] / ([2] + [3] + [4]) <0.05, the elastic modulus in the TD direction decreases, which is not preferable.
When [4] / ([2] + [3] + [4])> 0.45, the modulus of elasticity in the MD and TD directions decreases, and the heat resistance decreases, which is not preferable. A more preferred range is 0.05
≤ [4] / ([2] + [3] + [4]) ≤0.20.

The ratio of [1] to [2] + [3] + [4] is 0.8 or more and 1.2 or less from the viewpoint of increasing the degree of polymerization. Preferably it is 0.9 or more and 1.1 or less, more preferably 0.95 or more and 1.05 or less. When improving the hydrolysis resistance, [1] / ([2] + [3] +
[4]) is preferably more than 1.0 and 1.2 or less, and preferably 0.8 or more and less than 1.0 when the terminal is blocked.

The liquid crystalline polyester of the present invention contains, in addition to the above structural units, hydroquinone, chlorohydroquinone, phenylhydroquinone, t-butylhydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 2,6 Dihydroxy compounds such as -dihydroxynaphthalene and 2,7-dihydroxynaphthalene, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4 ' -Dicarboxylic acid, 4,
Dicarboxylic acids such as 4'-dicarboxydiphenyl ether, isophthalic acid, 2,2'-diphenylcarboxylic acid, 3,3'-diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, p-hydroxybenzoic acid, m
Structural units introduced by oxycarboxylic acids such as -hydroxybenzoic acid, 2,6-hydroxynaphthoic acid, 3-chloro-4-hydroxybenzoic acid, p-aminobenzoic acid, p-phenylenediamine and acyl compounds thereof May be contained as a small copolymerization component as long as the effects of the present invention are not impaired.

The liquid crystalline polyester of the present invention can be produced according to a conventional polyester polycondensation method. For example, there are an interfacial polymerization method, a solution polymerization method, a melt polymerization method and the like, but the melt polymerization method is preferred because the degree of polymerization is easily improved and the production can be performed at the lowest cost.

As the melt polymerization method, 1) a method for producing an acetate compound from an acid compound by deacetic acid polycondensation reaction 2) a reaction between a phenolic compound and an acid compound by adding acetic anhydride and then a deacetic acid polycondensation reaction 3) A method of producing from a phenolic compound and a phenyl ester compound of an acid by a dephenol polycondensation reaction, and the like. In the present invention, the polycondensation is carried out at 325 ° C. or lower using the method 2). Is preferred. This is a major feature of the present invention in that it can be produced by a conventional vertical polymerization apparatus for producing polyester and can be mass-produced at low cost.

The production method will be described in more detail. As a raw material, 2-methylhydroquinone (formula (5));
Terephthalic acid (the above formula (6)), naphthalene-2,6-
Dicarboxylic acid (the above formula (7)), naphthalene-1,4-
A dicarboxylic acid (formula (8) above) is used. These may be charged at once, or only the dihydroxy compound (5) may be charged first. (5), (6),
The moles of (7) and (8) are [5], [6],
Assuming [7] and [8], the charging ratio is

[0021]

[Equation 3] 0.8 ≦ [5] / ([6] + [7] + [8]) ≦ 1.2 0.5 ≦ [6] / ([6] + [7] + [8]) ≦ 0.90 0.05 ≦ [7] / ([6] + [7] + [8]) ≦ 0.45 0.05 ≦ [8] / ([6] + [7] + [8]) It is preferable to keep the ratio of ≦ 0.45. Most preferably,

[0022]

## EQU4 ## 1.0 ≦ [5] / ([6] + [7] + [8]) ≦ 1.2 0.6 ≦ [6] / ([6] + [7] + [8]) ≦ 0.90 0.05 ≦ [7] / ([6] + [7] + [8]) ≦ 0.20 0.05 ≦ [8] / ([6] + [7] + [8]) ≤0.20.

After charging them all at once or after charging only the dihydroxy compound (5), a predetermined amount of acetic anhydride is charged and acetylation is performed at 100 to 170 ° C.
The acetylation reaction is performed for 5 minutes to 3 hours, preferably 20 minutes to
Perform for 1.5 hours. The amount of acetic anhydride (this

[9]
Is preferably used in the same amount or about 1.5 times the amount of the starting hydroxy group. That is,

[0024]

[Expression 5] 1.0 ≦

[9] / 2 × [5] ≦ 1.5. When only the dihydroxy compound (5) is charged first, the dicarboxylic acids ((6) and (6) and (6) are acetylated or after the acetylation is completed, or during the next temperature increase or after the temperature increase is completed, that is, before the pressure reduction is started. 7) and (8)) are prepared.

After the completion of the temperature rise, before the start of the decompression, it is 270-325.
Aging at normal pressure for about 10 minutes to 2 hours at about ° C is preferable in order to match the charge ratio with the polymer ratio. Thereafter, the polymerization is carried out by raising the temperature.
The polymerization is preferably carried out at a temperature of from 275 to 325 ° C. Most preferably, it is 300 to 320 ° C. There is an advantage that the resulting polymer can be polymerized at a low temperature despite its high heat resistance. The polymerization is carried out under reduced pressure.
The pressure is gradually reduced from 60 mmHg to 1 mmHg, and the time required for the pressure reduction is 30 minutes or more, preferably 60 minutes or more. In particular, it is important to gradually reduce the pressure from 30 mmHg to 1 mmHg.

The reaction can be carried out without a catalyst, and if necessary, carried out in the presence of a catalyst. As the catalyst to be used, a transesterification catalyst, a polycondensation catalyst, an acylation catalyst, a decarboxylic acid catalyst or the like is used, and these may be mixed. Preferred catalysts are Ti (OBu) ₄ ,
BuSnOOH, Sn (OAc) ₂ , Sb ₂ O ₃ , Fe
(Acac) ₃ , Zn (OAc) ₂ , Co (OA
c) ₂ , NaOAc, KOAc and the like. The amount used is 5 to 5000 ppm, preferably 50 to 5000 ppm, based on the polymer.

The polymerization time may be within 10 hours, but is preferably within 7 hours. Most preferably, it is within 1 to 4 hours. This polymerization has not only the advantage that it can be carried out at a low temperature, but also a great advantage that it can be easily pulled out even at a lower temperature, and does not cause any trouble at the time of withdrawal. Therefore, there is a great feature that a conventional vertical polymerization apparatus can be used. Another advantage is that the final polymer can be produced only by the melt polymerization method.

The conventional vertical polymerization apparatus for producing polyester is described in, for example, Fiber Handbook (raw material edition), p808, FIGS.
And the like. Of course, in the present invention, a horizontal kneader-type reaction apparatus may be used, or solid-state polymerization may be performed after melt polymerization to further increase the degree of polymerization. Further, the liquid crystalline polyester of the present invention exhibits optical anisotropy in the molten phase. In particular, when the melting is started, the solid portion almost disappears just by slightly increasing the temperature from the melting start temperature, and almost all of the liquid crystal state can be obtained, so that the fluidity is much better than that of the conventional polyester. Therefore, it has good moldability and can be subjected to general melt molding such as extrusion molding, injection molding, and compression molding, and can be processed into molded articles, films, fibers, and the like.

As for the melt viscosity, the polyester of the present invention generally has a low melt viscosity because it exhibits liquid crystallinity. For example, the melt viscosity at 103 ° C. and 10 ³ sec ^-1 is 5
It is 0 to 5000 poise, preferably 50 to 3000 poise, and more preferably 100 to 2500 poise.
Most preferably, it is 200 to 2000 poise. The polyester of the present invention has particularly large characteristics when formed into a molded product. That is: 1) The elastic modulus in both MD and TD directions is large. 2) High strength in both MD and TD directions. 3) High impact strength. 4) Since the fluidity is high, it is possible to manufacture an extremely thin molded product.

Accordingly, automotive materials (for example, horizontal outer plates as well as vertical outer plates), precision molded products, thin molded products, information material components such as compact disks and floppy disks, and electronic material components such as connectors and IC sockets. And the like. Further, at the time of molding, for the copolymerized polyester of the present invention, glass fibers, fibers such as carbon fibers,
Fillers and additives such as talc, mica, calcium carbonate, fillers, nucleating agents, pigments, antioxidants, lubricants, other stabilizers, flame retardants, etc. Can also be given.

It is also possible to create a composition having both the characteristics of the other polymer and the advantages of the copolymerized polyester of the present invention by blending or alloying with another polymer.

[0032]

Next, the present invention will be described in more detail, but the present invention is not limited to the following examples unless it exceeds the gist. The melt viscosity in the examples was measured using a flow tester manufactured by Shimadzu Corporation at a shear rate of 1000 sec ^-1 and a cylinder nozzle length / diameter of 2.
0 was used. The optical anisotropy (liquid crystal properties) was observed using a polarizing microscope equipped with a hot stage. Molding was performed using a 0.1 oz injection molding machine manufactured by Nippon Steel Corporation to produce molded pieces.

The following three types of test pieces were molded. (1) To measure the anisotropy of the mechanical properties of the polymer,
40mm (length) x 6mm (width) for performing bending test
A test piece of × 1 mm (thickness) was formed in both the injection direction (MD) and the direction perpendicular to it (TD). (2) A 20 mm × 20 mm × 1.5 mm flat plate was formed. One of these injection molded products is 20 mm parallel to the flow direction.
× 2 mm × 1.5 mm, and one was cut to 20 mm × 2 mm × 1.5 mm perpendicular to the flowing direction. (3) A test piece for measuring impact resistance was prepared.

The MD for the obtained test piece (1), TD directions of the flexural modulus, flexural strength was measured using the Orientec Co. Tensilon, also the emission direction dynamic elastic modulus E _'MD and The dynamic elastic modulus E ′ _TD in a direction perpendicular to the direction was measured at 110 Hz and 23 ° C. using a vibron (Leo Vibron DV-III type manufactured by Orientec). For (2), only E ′ _MD and E ′ _TD were measured.

As a measurement of heat resistance, a Vicat softening temperature was measured. Vicat softening temperature is determined by Toyo Seiki's automatic HDT
Using the measuring device, the sample is the temperature at which the needle penetrates 1 mm at a heating rate of 50 ° C./hour using the above-mentioned 0.1 oz molded piece. . The solder resistance was determined by immersing the 0.1 oz molded piece in a 260 ° C. solder bath for 10 seconds and visually observing the appearance.

<Example 1> A 2-methylhydroquinone 4 was added to a glass polymerization tube equipped with a stirring blade, a nitrogen inlet, and a vacuum port.
7.7 g (0.385 mol), 38.4 g of terephthalic acid
(0.231 mol), naphthalene-2,6-dicarboxylic acid, 16.6 g (0.077 mol), naphthalene-1,
After 16.6 g (0.077 mol) of 4-dicarboxylic acid was charged and the inside of the system was set to a nitrogen atmosphere by nitrogen-vacuum substitution, 98.2 g (0.963 mol) of acetic anhydride was further added. Next, the temperature was raised to 140 ° C. while stirring the system, and 1
It was kept at 140 ° C. for a time. Then 1 hour and 40 minutes 3
After the temperature was raised to 00 ° C and aged at 300 ° C for 30 minutes, the temperature was further raised to 320 ° C. When the temperature reached 320 ° C., the pressure reduction was started.

The pressure is reduced to 10 mmHg in the first hour, and then reduced from 10 mmHg to 0.3 mm over 1.5 hours.
However, the polymerization was terminated at 5 mmHg because the torque was sufficiently increased. Thereafter, the mixture was allowed to stand, the pressure was restored, and the polymer was extracted from the bottom of the polymerization tube. The withdrawal property was very good. The melting behavior of this polymer at 320 ° C. and its mechanical properties were investigated at 320 ° C. Table 1 shows the results. It was found that the elastic modulus and strength in both MD and TD directions were very large. Also, the Izod impact strength was large. FIG. 1 shows the infrared absorption spectrum of this polymer.

<Example 2> The procedure of Example 1 was repeated except that the composition was the same as that of Example 1 and only the composition ratio was changed as follows.

[0039]

[Table 1] Each physical property value is shown in Table 1.

<Comparative Example 1> The procedure of Example 1 was repeated, except that the composition was the same as that of Example 1 and only the composition ratio was changed as follows.

[0041]

[Table 2] Each physical property value is shown in Table 1.

<Comparative Example 2> A product was produced according to Example 1 of JP-A-59-124925. That is, a raw material having the following composition was charged into a polymerization tube, stirred at 290 ° C. under a nitrogen atmosphere for 1 hour, then reduced to 0.5 mmHg and stirred for 30 minutes to obtain a polymer.

[0043]

[Table 3] Physical properties are shown in Table 1.

<Comparative Example 3> A product was produced according to the example of JP-A-61-19627. That is, a raw material having the composition shown below was charged into a polymerization tube, and was heated at 150 ° C. under a nitrogen atmosphere for 30 minutes.
Then, the mixture was heated to 280 ° C. and reduced to 0.5 mmHg to obtain a polymer.

[0045]

[Table 4] The polymer could not be withdrawn from the bottom of the kettle (it could not be withdrawn from the bottom of the kettle when similarly prepared at 325 ° C). 325 ° C, shear rate 10 ²
The melt viscosity at sec ^-1 was 2.5 × 10 ⁴ poise, and the melt viscosity at a shear rate of 10 ³ sec ^-1 was 8000 poise, which was very high. Table 1 shows the physical property values.

<Comparative Example 4> A product was produced according to Example 2 of JP-A-1-261418. That is, raw materials having the following compositions were charged into a polymerization tube, heated to 330 ° C. and reacted for 2 hours under a nitrogen atmosphere, and then heated to 380 ° C. and depressurized to obtain a polymer.

[0047]

[Table 5] The melt viscosity of this polymer at 377 ° C. is a shear stress of 10
It was as high as 2600 poise at ³ sec ^-1 . Table 1 shows the physical property values. In addition, when an experiment for producing the present polymer at 325 ° C. or lower was separately performed, the polymer was solidified.

Comparative Example 5 A commercially available liquid crystalline polyester (molded using Vectra A950, manufactured by Polyplastics Co., Ltd.) molding temperature 300 ° C.)
The physical properties are shown in Table 1.

<Comparative Example 6> Based on Example 1 of JP-B-56-18016.

[0050]

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Then, the mixture was charged so as to have a molar ratio of 40/60, and the mixture was placed under a nitrogen atmosphere and then stirred at 275 ° C. for 60 minutes.
The pressure was further reduced to 0.5 mmHg to obtain a polymer. The physical properties are shown in Table 1. The molding was performed at 275 ° C.

[0052]

[Table 6]

[0053]

According to the above data, when the composition and composition ratio of the present invention are used, it can be mass-produced because it has a feature that it can be manufactured without any trouble by a conventional manufacturing apparatus at 325 ° C. or lower. Further, since the melt viscosity is low, the moldability is excellent, and particularly, a thin molded article can be molded.

Further, the molded article is characterized by high elastic modulus and strength in both MD and TD directions and high Izod impact strength. In addition, it has features of excellent fluidity and excellent heat resistance. Therefore, it is very useful for products such as molding materials and films. In particular, molding materials include automotive materials (for example, outer panels), electric and electronic parts, thin molded products,
It is suitable as a precision molded product. Needless to say, it is also suitable as a uniaxially oriented product such as a fiber.

Further, the liquid crystalline polyester of the present invention can be melt-polymerized at 325 ° C. or lower in a conventional type vertical polymerization apparatus, and can be widely used because it can be easily removed from the bottom of the kettle. Also have.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a polymer obtained in Example 1 of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 63/00-63/91 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A structural unit represented by the following formulas (1) to (4): When the number of moles of (1), (2), (3) and (4) is [1] [2] [3] [4], respectively: 0.8 ≦ [1] / ([2] + [3] + [4]) ≦ 1.2 (I) 0.5 ≦ [2] / ([2] + [3] + [4]) ≦ 0.90 (II) 0.05 ≦ [3 ] / ([2] + [3] + [4]) ≦ 0.45 (III) 0.05 ≦ [4] / ([2] + [3] + [4]) ≦ 0.45 (IV) And a melt viscosity at 320 ° C. and a shear stress of 10 ³ sec ⁻¹ is 50 to 5000 poise. 2. Compounds represented by the following formulas (5) to (8): 2. The method for producing a liquid crystalline polyester according to claim 1, wherein the polycondensation is carried out at a temperature of 325 ° C. or lower when the polycondensation is carried out under reduced pressure after the acetylation is carried out by reacting the compound with acetic anhydride. . 3. An injection-molded article comprising the liquid crystalline polyester according to claim 1.