JP2001064399A - Preparation of liquid crystalline polyester microsphere - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily preparing process for liquid crystalline polyester micropheres. SOLUTION: This process comprises either the melt kneading of a thermoplastic resin composition which has a continuous phase of the thermoplastic resin (A) and a disperse phase of a liquid crystalline polyester (B), then the extruding from a nozzle and the taking-off at a taking-off rate of less than 3.0 times the resin discharge rate to thereby mold it in a strand shape, and the cutting to give it as pellets, or the melt kneading of the thermoplastic resin composition, then the discharging as lumps; then the immersing of the pellets or the lumps in a solvent which dissolves component (A) but does not dissolve component (B), consequently the dissolving and removing of component (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a liquid crystal polyester microsphere.

[0002]

2. Description of the Related Art Microspheres made of a resin such as a thermoplastic resin or a thermosetting resin are coated on the surface of a sliding material because they are not rusted and light like metal.
It is useful for spacers for liquid crystal displays, raw materials for fine powder molding, fillers for thermoplastic and thermosetting resins, fillers for paints, and electronic materials for lubricating materials. Has more dimensional stability, heat resistance,
There is a demand from the market for microspheres of thermoplastic resin having excellent chemical resistance.

[0003] Since liquid crystal polyester is excellent in mechanical strength, dimensional stability, heat resistance, and chemical resistance, the molded article is supposed to be used under corrosive conditions such as acid and alkali, high temperature conditions and high stress. It is said to be far superior to molded articles made of other resins in applications where

However, liquid crystal polyesters have a property that rigid molecules are easily aligned in a long axis direction and are easily oriented to a high degree. It has been difficult to obtain microspheres by methods such as suspension polymerization, uniform droplet polymerization, emulsion polymerization, and two-step swelling polymerization, which are known as methods for producing microspheres composed of molecules. . Also,
The method of mechanically pulverizing molded products and pellets of the liquid crystal polyester is not practical such that fibrous fibrils of the liquid crystal polyester are generated and become bulky. , Resulting in only heterogeneous polyhedral particles.

[0005] Japanese Patent Publication No. 6-102731 discloses that liquid crystal polyester is added to polyethylene terephthalate in 10 to 3 times.
A method is described in which 0% by weight is blended, melted and formed into a sheet, and the polyethylene terephthalate in the sheet is dissolved and removed with a special solvent to produce a liquid crystal polyester microsphere. However, since this method involves a complicated process of forming a sheet, and sometimes it is difficult to handle the obtained sheet when immersing it in a solvent, a simpler manufacturing method is required. Had been. In addition, a fibrous liquid crystalline polyester was sometimes obtained by this method.

[0006]

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a simple method for producing liquid crystal polyester microspheres.

[0007]

According to the present invention, a thermoplastic resin composition having a thermoplastic resin (A) as a continuous phase and a liquid crystal polyester (B) as a dispersed phase is melt-kneaded and then extruded from a nozzle to discharge the resin. It is taken up at a take-up speed of less than 3.0 times the speed, formed into a strand, and then cut into pellets, or the thermoplastic resin composition is melt-kneaded and taken out as a lump, and the (A) is dissolved. However, the present invention relates to a method for producing a liquid crystal polyester microsphere, in which the (A) is dissolved and removed by immersing the lump or the pellet in a solvent that does not dissolve the (B).

[0008]

Next, the present invention will be described in more detail. The thermoplastic resin (A) used in the present invention is soluble in a solvent such as water, an organic solvent, an acid or an alkali, and the solvent used for dissolving the same dissolves the liquid crystal polyester (B). If not, we are not particular about the molecular structure. Specific examples of combinations of a thermoplastic resin (A) and a solvent that dissolves the same but do not dissolve the liquid crystal polyester (B) include, for example, polyphenylene ether and chloroform, polycarbonate and chloroform, polystyrene and chloroform, and polyether sulfone. And NMP
And the like, but are not limited to these.

Among them, the heat resistance at the time of melt-kneading the thermoplastic resin (A) and the liquid crystal polyester (B), the availability of the thermoplastic resin (A), the availability of the solvent, the versatility, In terms of cost, the thermoplastic resin (A) is preferably polycarbonate or polyphenylene ether, and the solvent in that case is preferably chloroform. Polycarbonate is more preferably polycarbonate (bisphenol A type), and polyphenylene ether is more preferably poly (2,6-
Dimethylphenylene ether).

The liquid crystal polyester (B) used in the present invention
Is a polyester called a thermotropic liquid crystal polymer. Specifically, (1) A compound obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. (2) Those obtained by reacting a combination of different aromatic hydroxycarboxylic acids. (3) A compound obtained by reacting an aromatic dicarboxylic acid with a nucleus-substituted aromatic diol. (4) Those obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as polyethylene terephthalate. And those which form an anisotropic melt at a temperature of 400 ° C. or lower are preferred. When a higher heat resistance is required as the liquid crystal polyester microspheres of the present invention, the liquid crystal polyester of the above (1) is particularly preferable. In addition, instead of these aromatic dicarboxylic acids, aromatic diols and aromatic hydroxycarboxylic acids, their ester derivatives may be used.

The repeating structural units of the liquid crystalline polyester include the following repeating structural units derived from an aromatic dicarboxylic acid, the following repeating structural units derived from an aromatic diol,
Examples of the repeating structural unit derived from an aromatic hydroxycarboxylic acid include, but are not limited to, these.

A repeating structural unit derived from an aromatic dicarboxylic acid:

[0013]

A repeating structural unit derived from an aromatic diol:

[0015]

A repeating structural unit derived from an aromatic hydroxycarboxylic acid:

A liquid crystal polyester which is particularly preferred from the balance of heat resistance, mechanical properties and workability is And more preferably at least 30 mol% or more of such a repeating structural unit. Specifically, the combination of repeating structural units is preferably any one of the following (I) to (VI).

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

The method for producing the liquid crystal polyesters (I) to (VI) is described in, for example, JP-B-47-47870.
JP-B-63-3888, JP-B-63-3891, JP-B-56-18016, JP-A-2-51
No. 523, etc. Of these, a combination of (I), (II) or (IV) is preferable, and a combination of (I) or (II) is more preferable.

In the present invention, in the field where high heat resistance is required, a liquid crystal polyester may be composed of 30 to 80 mol% of the following repeating unit (a ') and 0 to 10 mol% of the repeating unit (b'). A liquid crystal polyester having a unit (c ′) of 10 to 25 mol% and a repeating unit (d ′) of 10 to 35 mol% is preferably used.

[0026] (In the formula, Ar is a divalent aromatic group.)

In the field where the liquid crystal polyester microspheres of the present invention require easy disposal such as incineration after use from the viewpoint of environmental problems, the preferred combinations of the fields required in each of the fields mentioned above are included. In particular, a liquid crystal polyester formed of a combination of only carbon, hydrogen, and oxygen is particularly preferably used.

The thermoplastic resin composition of the present invention preferably contains the thermoplastic resin (A) in an amount of 70.0 to 99.9% by weight, more preferably 85.0 to 95.0% by weight, and further preferably 90.9% by weight. 0 to 95.0% by weight, and 30.0 to 0.1% by weight of the liquid crystal polyester (B), more preferably 15.0 to 5.0% by weight, and further preferably 10.
It is a thermoplastic resin composition containing 0 to 5.0% by weight. If the content of the component (A) is less than 70.0% by weight, the dispersion particle size of the component (B) in the melt of the composition may become large or continuous, which is not preferable. If component (A) exceeds 99.9% by weight, it may be difficult to dissolve the melt of the composition and recover component (B), which is not preferable. Also, depending on the conditions of the melt-kneading, the component (B)
When the composition ratio of is large, the average particle size of the finally obtained liquid crystal polyester microspheres becomes large, and when the composition ratio of component (B) is small, the average particle size of the finally obtained liquid crystal polyester microspheres becomes It tends to be smaller.

As a method for producing the liquid crystal polyester resin composition of the present invention, a known method can be used. From an industrial point of view, a method in which each component of the above composition is melt-kneaded in a molten state is preferred. For the melt kneading, kneading apparatuses such as a single-screw or twin-screw extruder and various kneaders which are generally used can be used. In particular, a biaxial high kneader is preferred.

At the time of melt-kneading, it is preferable that the cylinder set temperature of the kneading apparatus is set to a temperature higher than the flow start temperature of the component (B). Cylinder set temperature is component (B)
If the temperature is lower than the flow start temperature of the component (B), the component (B) is not sufficiently melted, and dispersion failure may occur. Here, the flow start temperature is measured using a capillary rheometer (for example, Shimadzu Flow Tester CFT-500 manufactured by Shimadzu Corporation), and the thermoplastic resin heated and melted at a heating rate of 4 ° C./min is Under a load of 100 kgf / cm ² ,
When extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, the temperature (° C.) at which the melt viscosity shows 48,000 poise.

At the time of melt kneading, each component may be uniformly mixed in advance with a device such as a tumbler or a Henschel mixer, or if necessary, mixing may be omitted, and each component may be separately measured in a melt kneading device. A supply method can also be used.

In the present invention, first, the thermoplastic resin composition is melt-kneaded, extruded from a nozzle, drawn at a take-up speed less than 3.0 times the resin discharge speed, formed into a strand, and then cut. Pellets or
Alternatively, the thermoplastic resin composition is melt-kneaded and then taken out as a lump.

More specifically, when the thermoplastic resin composition is taken out as a lump, for example, the thermoplastic resin composition is melt-kneaded using a single-screw or twin-screw extruder or the like without a nozzle or the like at the tip, and then the mixture is not formed into a strand. Take out as. At that time, it is preferable that a shear rate exceeding 1000 sec ⁻¹ is not applied when the melt is discharged. If the ratio exceeds the above range, the component (B) in the molten composition becomes fibrous, and the ratio of the average particle major axis to the average particle minor axis may exceed 10, which is not preferable.

In the case of forming pellets, for example, the thermoplastic resin composition is melt-kneaded using a single-screw or twin-screw extruder or the like, and then extruded from a nozzle attached to the tip thereof, and is 3.0 times the resin discharge speed. At a take-off speed of less than, for example, it is taken up by a commercially available strand cutter to form a strand, and then cut by the strand cutter or the like to form pellets. 2. The take-up speed is the resin discharge speed.
If it is more than 0 times, the component (B) is stretched in the strand and becomes fibrous, and the ratio of the average particle major axis to the average particle minor axis may exceed 10, which is not preferable.
The take-up speed in this case is more preferably less than 2.5 times the resin discharge speed. Further, when the thermoplastic resin composition is melt-kneaded and then extruded from a nozzle, 1000 s
It is preferable to extrude from the nozzle at a shear rate of ec ^-1 or less.

In the present invention, the pellet or lump obtained as described above is immersed in a solvent that dissolves (A) but does not dissolve (B), thereby dissolving and removing (A). At this time, it is preferable that the solvent is evaporated and then cooled and recovered from the viewpoint of environmental problems and cost. From the easiness of this step, pellets are preferable to lump as a shape that can be obtained after melt-kneading the thermoplastic resin composition.

The thus obtained microspheres of the component (B) are sufficiently washed with the used solvent and then isolated by filtering through a desired filter. At that time, although not sufficient, the size of the particles can be made uniform. For example, when only a microsphere having a size of 30 μm or less is required, first, the solution is filtered with a filter that allows particles of 40 μm or less to pass, and the filtrate is recovered. Next, the filtrate was added to 2
The microspheres remaining on the filter can be collected by passing through a filter through which particles of 0 μm or less pass.

The component (B) thus obtained is
After sufficiently washing with the used solvent, the microspheres can be separated and collected by a centrifuge.

The microsphere of the present invention can be used alone, or it can be used by coating it on another thermoplastic resin film or dispersing it in a solvent or liquid.

[0039]

The microspheres of the present invention have rigidity, heat resistance,
Because of good chemical resistance and dimensional stability,
It can be used in a wide range of industries such as a spacer used by being dispersed during melting and a surface coating agent for preventing adhesion between metal surfaces.

[0040]

EXAMPLES The present invention will be described below with reference to examples, but these are merely examples, and the present invention is not limited to these examples.

(1) Thermoplastic resin of component (A) Commercially available polycarbonate manufactured by Sumitomo Dow KK
CALIBRE 200-4 was used. Hereinafter, the thermoplastic resin is abbreviated as A-1.

(2) Liquid crystal polyester of component (B) 8.3 kg (60 mol) of p-acetoxybenzoic acid, 2.49 kg (15 mol) of terephthalic acid, 0.4 g of isophthalic acid.
83 kg (5 mol) and 5.45 kg (20.2 mol) of 4,4′-diacetoxydiphenyl were charged into a polymerization vessel having a comb-shaped stirring blade, and the temperature was increased while stirring under a nitrogen gas atmosphere, and the temperature was raised to 330 ° C. for 1 hour. Polymerized for hours. During this time, polymerization was carried out under strong stirring while liquefying and collecting and removing acetic acid gas produced as a by-product in a cooling tube. After that, the system was gradually cooled to 200
The polymer obtained at ℃ was taken out of the system. The obtained polymer was pulverized with a hammer mill manufactured by Hosokawa Micron Co., Ltd. to obtain particles of 2.5 mm or less. This was further treated in a rotary kiln under a nitrogen gas atmosphere at 280 ° C. for 3 hours to obtain a particulate wholly aromatic polyester having a flow start temperature of 324 ° C. and comprising the following repeating structural units. Here, the flow start temperature is defined as a value obtained by using a Shimadzu Flow Tester Model CFT-500 manufactured by Shimadzu Corporation at a heating rate of 4 ° C./min to melt a resin under a load of 100 kgf / c.
The temperature (° C.) at which the melt viscosity shows 48,000 poise when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under m ² . Hereinafter, the liquid crystal polyester is abbreviated as B-1. This polymer showed optical anisotropy at 340 ° C. or more under pressure. The repeating structural units of the liquid crystal polyester B-1 are as follows.

[0043]

(3) Scanning Electron Microscope Photograph The obtained fine particles are dried and then attached to a conductive tape.
It was observed after gold deposition.

Example 1 A-1 92% by weight, B-1
Nippon Steel Corporation TEX-
Using a 30 type twin screw extruder, set cylinder temperature 335
The composition was obtained by performing melt-kneading at 150 ° C. and a screw rotation speed of 150 rpm. It was extruded from a circular nozzle, the discharge speed was 3.0 m / min, and the take-up speed was 6.0 m / min using a pelletizer manufactured by Tanabe Plastics Co., Ltd., and pelletized at the same time. Pellets 10 of this composition
g was put into chloroform heated to 60 ° C. in a 2 L flask, and stirred for 1 hour to dissolve the polycarbonate. Collect insoluble components by decantation,
Well washed with 250 cc of chloroform. Wash 3
I did it. The insoluble component was dispersed in methanol, filtered through a 20 μm filter, the sample on the filter (hereinafter abbreviated as “sample 1”) was collected, dried, gold-deposited, and observed with an electron microscope. 2
Spindle-shaped particles of about 0 to 60 μm were observed. The electron micrograph is shown in FIG. Next, the filtrate obtained above was filtered with a 7 μm Teflon filter, and the filtrate was further filtered with a 2 μm Teflon filter. A sample on the filter (hereinafter abbreviated as “sample 2”) was collected, dried, gold-deposited, and observed with an electron microscope.
Spherical particles having a particle size of 2 to 5 μm were observed. An electron micrograph is shown in FIG.

[Comparative Example 1] The take-up speed was 12.0 m /
The obtained insoluble components were observed in the same manner as in Example 1 except that the amount was changed to min. As a result, only those in which the fibers were entangled were obtained. An electron micrograph is shown in FIG.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of the liquid crystal polyester microspheres (sample 1) obtained in Example 1.

FIG. 2 is an electron micrograph of the liquid crystal polyester microspheres (sample 2) obtained in Example 1.

FIG. 3 is an electron micrograph of the liquid crystal polyester microsphere obtained in Comparative Example 1.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B29K 101: 12 (72) Inventor Motonobu Furuta 6 Kitahara, Tsukuba-shi, Ibaraki F-term (Reference) 4F070 AA48 DA60 DC07 DC11 4F074 AA65 AA66 AA68 AA70 AA77 AA97 AB00 CB03 CB17 CB28 CC02X CC04X CC22X CC37X 4F201 AA24 AA27 AA28 AA32.

Claims (10)

[Claims] 1. A thermoplastic resin composition comprising a thermoplastic resin (A) as a continuous phase and a liquid crystal polyester (B) as a disperse phase is melt-kneaded and then extruded from a nozzle at a speed less than 3.0 times the resin discharge speed. It is taken up at a take-up speed to form a strand and then cut to form pellets, or the thermoplastic resin composition is melt-kneaded and taken out as a lump to dissolve (A) but dissolve (B) (A) is dissolved and removed by immersing the pellet or the lump in a solvent that is not used. 2. A thermoplastic resin composition comprising a thermoplastic resin (A) as a continuous phase and a liquid crystal polyester (B) as a disperse phase is melt-kneaded and then extruded from a nozzle to take off less than 3.0 times the resin discharge speed. It is taken up at a speed, formed into a strand shape, and then cut into pellets.
Wherein the pellet is immersed in a solvent that does not dissolve (B) but dissolves (B), thereby dissolving and removing the (A). 3. The method according to claim 2, wherein when the thermoplastic resin composition is melt-kneaded and then extruded from a nozzle, the composition is extruded from the nozzle at a shear rate of 1000 sec ^-1 or less. 4. The liquid crystal according to claim 1, wherein the temperature at which the thermoplastic resin composition is melt-kneaded is higher than the flow start temperature of the liquid crystal polyester (B). A method for producing a polyester microsphere. Here, the flow start temperature is measured using a capillary rheometer (for example, Shimadzu Flow Tester CFT-500 manufactured by Shimadzu Corporation), and the thermoplastic resin heated and melted at a heating rate of 4 ° C./min is Under a load of 100 kgf / cm ² ,
When extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, the temperature (° C.) at which the melt viscosity shows 48,000 poise. 5. A thermoplastic resin comprising the thermoplastic resin (A) in an amount of 70.0 to 99.9% by weight and the liquid crystal polyester (B) in an amount of 30.0 to 0.1% by weight. The method for producing a liquid crystal polyester microsphere according to any one of claims 1 to 4, which is a composition. 6. The method for producing liquid crystalline polyester microspheres according to claim 1, wherein the thermoplastic resin (A) is polycarbonate or polyphenylene ether. 7. The method according to claim 6, wherein the solvent that dissolves the thermoplastic resin (A) but does not dissolve the liquid crystal polyester (B) is chloroform. 8. The process for producing a liquid crystalline polyester microsphere according to claim 1, wherein the liquid crystalline polyester (B) contains at least 30 mol% of the following repeating structural units. . 9. The liquid crystal polyester (B) according to claim 1, which is obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. The method for producing the liquid crystal polyester microspheres according to the above. 10. The liquid crystal polyester microspheres according to claim 1, wherein the liquid crystal polyester (B) is obtained by reacting a combination of different aromatic hydroxycarboxylic acids. How to make the body.