JP2002060494A - Method for manufacturing thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a thermoplastic resin which has a high melt tension, can be molded in a wide temperature range, excels in moldability and exhibits liquid crystallininity on melting, and a molded product obtained by using the resulting thermoplastic resin. SOLUTION: The method for manufacturing the thermoplastic resin which exhibits liquid crystallinity on melting comprises melting a thermoplastic resin which exhibits liquid crystallinity on melting, then solidifying the molten product, and subjecting the thermoplastic resin having a volume of the solidified product of 1 mm3 to 50,000 mm3 to heat treatment in an inert gas atmosphere at a temperature of not higher than the flow temperature of the solidified product. The flow temperature is a temperature ( deg.C) at which the melt viscosity of the resin, measured by a capillary rheometer, shows 48,000 P when the resin having been molten by heating at a heat-up rate of 40 deg.C/minute is extruded through a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 100 kgf/cm2. The molded product is obtained by molding the thermoplastic resin to be obtained by the above method by hot pressing, injection molding, extrusion, melt spinning, calendering or rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin exhibiting liquid crystallinity when melted, and a molded article using the thermoplastic resin obtained by the method.

[0002]

2. Description of the Related Art In recent years, films made from various polymers have become indispensable in daily life. For example, various films such as a high strength film, a high elasticity film, an oxygen barrier film, a conductive film, a heat resistant film, and a light barrier film have been developed. Above all, films having an oxygen barrier property or a water vapor barrier property are permeating our lives as packaging materials regardless of whether they are for industrial use or for consumer use.

Generally, liquid crystal polymers are characterized in that molecules are oriented in a molten state by strong intermolecular interaction. Therefore, in addition to the well-known properties of liquid crystal polymers such as high strength, high elastic modulus, and high heat resistance, liquid crystal polymers have strong intermolecular interactions and molecular orientations.
Industrialization as a film material having functions such as gas barrier properties has been expected.

However, unlike liquid crystal polymers such as polypropylene, polyethylene, and polyethylene terephthalate, liquid crystal polymers do not entangle even in a molten state due to their rigid molecules, and the molecular chains are remarkably oriented in the flow direction. It exhibits a behavior in which the viscosity suddenly decreases, or a behavior in which the melt viscosity rapidly decreases due to a rise in temperature. Therefore, for example, at the time of molding such as film molding, extrusion molding, blow molding, it is extremely difficult to maintain a certain level of tension necessary for molding in a molten state,
Further, since the molecules are oriented, it is difficult to balance the performance in the vertical and horizontal directions. In extreme cases, the molecules may be torn in the molecular orientation direction. Therefore, there is a problem in molding the liquid crystal polymer because the temperature range for stable molding is narrow. In particular, it has become a major problem when a liquid crystal polymer is put to practical use in fields such as film molding and blow molding. Therefore, a film utilizing the function of the liquid crystal polymer has not yet been put to practical use.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a thermoplastic resin which has a high melt tension, can be molded in a wide temperature range, has excellent workability, and exhibits liquid crystallinity when melted. It is an object of the present invention to provide a molded article using a thermoplastic resin, particularly a film or a bottle.

[0006]

Means for Solving the Problems The present inventors have intensively studied the improvement of the processability of a thermoplastic resin exhibiting liquid crystallinity when melted, and have found that when the resin once melted is heated again under specific conditions, it is obtained. The thermoplastic resin obtained has a high melt tension and has been found to be moldable in a wide temperature range, and has completed the present invention.

Namely, the present invention is a thermoplastic resin which is (1) was melted thermoplastic resin exhibiting liquid crystallinity when melted, solidified, the volume of the resulting solidified product is 1mm ³ ~50000mm ^3, The present invention relates to a method for producing a thermoplastic resin exhibiting liquid crystallinity when melted by performing a heat treatment at a temperature equal to or lower than a flow temperature of the solidified product in an inert gas atmosphere. Here, the flow temperature is measured by a capillary rheometer, and the resin heated and melted at a heating rate of 4 ° C./min is subjected to 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 . Further, the present invention provides [2] a method of melting a thermoplastic resin exhibiting liquid crystallinity upon melting and then solidifying the resulting solidified product, and pulverizing the obtained solidified product. The volume of the pulverized solidified product is 1 mm ^{3 to} 50,000 mm ³ . The present invention relates to a method for producing a thermoplastic resin exhibiting liquid crystallinity when melted by heat treatment at a temperature not higher than the flow temperature defined in [1] of the solidified product under an inert gas atmosphere under an inert gas atmosphere. is there. Further, the present invention provides [3] a thermoplastic resin exhibiting liquid crystallinity upon melting obtained by the method for producing a thermoplastic resin according to the above [1] or [2], by a hot press molding method, an injection molding method, or an extrusion molding method. The present invention relates to a molded article formed by a molding method, a melt spinning molding method, a calendar molding method or a roll molding method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a thermoplastic resin exhibiting liquid crystallinity upon melting according to the present invention comprises the steps of: first melting a thermoplastic resin exhibiting liquid crystallinity upon melting, then solidifying the resin; There the thermoplastic resin is a 1mm ³ ~50000mm ^3, under an inert gas atmosphere, characterized by heat treatment at flow temperature or lower. The obtained solidified product was pulverized, and the volume of the pulverized solidified product was 1 mm ³ to 50 mm.
It may be 000 mm ³ . Here, the flow temperature is measured by a capillary rheometer, and a resin heated and melted at a heating rate of 4 ° C./min is passed through a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 100 kgf / cm ^2. The temperature (° C.) at which the melt viscosity shows 48,000 poise when extruded. Once melted used in the present invention,
The volume of the solidified thermoplastic resin exhibiting liquid crystallinity when heat-treated is 1 to 50000 mm ³ , preferably 1 to 1000 mm ³ . Here, the thermoplastic resin substantially shows a lump. For example,
Outline, sphere, cylinder, cuboid, cone, ellipse, square pyramid,
It refers to things that have a triangular pyramid shape. When the volume of the mass exceeds 50,000 mm ³ , it is difficult to uniformly raise the temperature between the surface layer and the inside, and the polymerization rate is different, so that the molecular weight distribution is widened and the moldability may be reduced. is there. In addition, unreacted substances may remain and cause foaming or gas generation.

It is necessary to select a heating rate during the heat treatment so that the temperature is uniformly increased between the bulk surface layer of the aromatic liquid crystalline polyester resin and the inside. In addition, the heat treatment is preferably performed at a temperature equal to or lower than the flowing temperature so that the lump is not fused, and the heating time is preferably 1 minute to 24 hours.
Time, more preferably 5 minutes to 12 hours.

[0010] In order to further improve the homogeneity of the thermoplastic resin, melt kneading may be performed before supply to a molding machine. Like the conventional aromatic polyester resin, the thermoplastic resin of the present invention tends to have a lower flow temperature after melt-kneading than that before melt-kneading.

The inert gas is preferably selected from nitrogen, helium, argon and carbon dioxide, more preferably nitrogen. In the presence of air, especially oxygen,
The liquid crystalline aromatic polyester resin is oxidized at a high temperature, and is liable to be deteriorated in physical properties and colored, which is not preferable.

As a heat treatment apparatus, a known dryer,
A reactor, a heating mixer, an electric furnace, or the like can be used, but from the viewpoint of the above, a gas-flow-type device having a high airtightness is preferable.

In the present invention, the flow temperature (FT1) of the thermoplastic resin exhibiting liquid crystallinity upon melting after the heat treatment is:
It is preferably at least 3 ° C. higher than the flow temperature (FT2) before the heat treatment, more preferably at least 5 ° C. [F
When [T1−FT2] is less than 3 ° C., the moldability may not be improved. Further, when the FT1 is 350 ° C. or higher, the processing temperature may exceed 400 ° C., and molding may be difficult.

In order to improve the moldability of the thermoplastic resin exhibiting liquid crystallinity upon melting obtained in the present invention, a temperature higher than the flow temperature of the thermoplastic resin exhibiting liquid crystallinity upon melting after heat treatment by 40 ° C. or more is required. Is preferably 0.3 g or more, more preferably 0.5 g or more, larger than that before the heat treatment. If it is less than 0.3 g, the moldability may not be improved. The melt tension after the heat treatment is preferably from 4.0 g to 30.0 g, and more preferably from 8.0 g to 25.0 g. A wide temperature range where the melt tension is 4.0 or more and 30.0 g or less is preferable because a wide range of processing temperature at which a good film can be obtained and excellent workability are obtained. When the value of the melt tension is less than 4.0 g, the stable film formation temperature range may be narrowed in inflation film formation. When the value of the melt tension is larger than 30.0 g, a uniform film may not be obtained.

The thermoplastic resins which exhibit optical anisotropy when melted and which are used in the present invention are variously known as liquid crystalline polymers, and include, for example, wholly aromatic or semi-aromatic polyesters, polyesterimides and polyesters. Examples include amides and resin compositions containing them. In the present invention, a liquid crystal polyester or a composition using the liquid crystal polyester as one component is preferably used as the liquid crystal polymer.

The liquid crystal polyester referred to here is a polyester called a thermotropic liquid crystal polymer.
Specifically, (1) a product obtained by reacting a combination of different aromatic hydroxycarboxylic acids, and (2) a product obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. And (3) a polyester obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as (1) or (2) or (4) in which a benzene ring or a naphthalene ring is nucleus-substituted by a halogen, an alkyl group, or the like. , Etc., and 40
Those which form an anisotropic melt at a temperature of 0 ° C. or lower are preferred.

Examples of the repeating structural unit of the liquid crystal polyester include the following repeating structural units derived from an aromatic hydroxycarboxylic acid, the following repeating structural units derived from an aromatic diol, and the following repeating structural units derived from an aromatic dicarboxylic acid. However, the present invention is not limited to these.

A repeating structural unit derived from an aromatic hydroxycarboxylic acid:

A repeating structural unit derived from an aromatic diol:

[0020]

A repeating structural unit derived from an aromatic dicarboxylic acid:

[0022]

A liquid crystal polyester which is particularly preferred in view of the balance between mechanical properties and processability is one in which the repeating unit (A) contains 25 to 80 mol% of the entire repeating unit constituting the polymer, and more preferably 30 to 75 mol% Mol%. If the amount is less than 25 mol% or more than 80 mol%, the processing temperature exceeds 400 ° C., which is not preferable in view of workability.

The method for producing the film made of such a liquid crystal polyester is not particularly limited.
For example, a T-die method of extruding and winding a molten resin from a T-die, an inflation film forming method of extruding a molten resin into a cylindrical shape from an extruder provided with an annular die, and cooling and winding the same, a hot press method, or a calendar or a roll. Molding method.

The method for producing the hollow molded article made of such a liquid crystal polyester is not particularly limited, and includes, for example, a blow molding method. The shape of the obtained hollow molded article is particularly a bottle, a gasoline tank, or the like. Tanks, pipes, hollow containers and the like.

[0026]

The present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention. In addition, each physical property was measured by the method shown below. [Measurement Method of Physical Properties] Fluid temperature (FT): an index representing the melt fluidity, which is measured by a capillary rheometer (CFT500, a high-grade flow tester manufactured by Shimadzu Corporation), and measured at a rate of 4 ° C./min. 100 g of the sample resin (approximately 2 g)
When extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of kg / cm ² , the melt viscosity was 48,000.
It was expressed as a temperature (° C.) indicating poise (corresponding to 4800 Pa · S).

Optical anisotropy: The optical anisotropy of the sample resin in the molten state was determined by measuring the particle size of 25 placed on the heating stage.
The sample resin powder having a particle size of 0 μm or less was heated under polarized light at a rate of 25 ° C./min, and visually observed or the amount of transmitted light was recorded on an XY recorder.

Melt tension test: About 10 g of a sample was charged using a Capillograph 1B (manufactured by Toyo Seiki Seisaku-sho, Ltd.), and the inner diameter of the capillary was 2.095 m.
m, length 8.0 mm, inner diameter of the piston to be extruded 10 mm,
At a piston extrusion speed of 5.0 mm / min, the sample was taken up in a thread shape while being automatically accelerated by a variable speed winder, and the tension (melt tension) at the time of cutting was measured.

Example 1 [Before heating] 1250.7 g of 4-hydroxybenzoic acid
(9.06 mol), 6-hydroxy-2-naphthoic acid 5
68.8 g (3.02 mol) and 135 parts of acetic anhydride
5.7 g (13.3 mol) was charged into a polymerization tank having a squirrel-type stirring blade, and after acetylation (150 ° C., about 3 hours under reflux) under a nitrogen atmosphere, the temperature was raised and polymerized at 320 ° C. for about 45 minutes. Was. During this time, the by-produced acetic acid gas was liquefied and collected in a cooling tube, and polymerized while removing and removing the polymer. The same operation was repeated three times, and the obtained solidified polyester was reduced to a size of about 3 to 5 cm square. This was placed in an aluminum tray, charged in a nitrogen atmosphere furnace, and treated at 240 ° C. for 5 hours under a nitrogen atmosphere. The mixture was melt-kneaded at a screw rotation speed of 150 rpm to obtain aromatic liquid crystalline polyester pellets having an FT of 257 ° C. and a volume of about 24 mm ³ . Hereinafter, the liquid crystal polyester is abbreviated as X-1. This polymer exhibited optical anisotropy under pressure. 300 ° C. (FT +
(At 43 ° C.) was 3.5 g.

[After heating] X-1 was placed in an aluminum tray and charged in a nitrogen atmosphere furnace at 260 ° C. in a nitrogen atmosphere.
After 2 hours, melt kneading is performed with a PCM-30 twin screw extruder manufactured by Ikegai Kihan Co., Ltd. at a die head setting temperature of 300 ° C. and a screw rotation speed of 150 rpm, and the FT is 266.
C. to obtain aromatic liquid crystalline polyester pellets. Hereinafter, the liquid crystal polyester is abbreviated as Y-1. 3 of the pellet
Melt tension at 09 ° C. (FT + 43 ° C.)
5.5 g at 314 ° C. (FT + 48 ° C.).
It was 4 g. At 304 ° C. (FT + 38 ° C.)
Could not measure.

[Evaluation] A 30 mmφ twin screw extruder was installed on a Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho, Ltd.). At several 150 revolutions, the set temperature of the cylinder and die head was 280 ° C on average, and the take-up speed was 10 to 40m.
/ Min was changed to perform film formation. Table 1 shows the results. ○ indicates that the inflation valve was stable and the sample could be continuously collected in a film form for a certain period of time, and × indicates that the inflation valve was not stable and continuous sampling was difficult, or the film appearance was good. Indicates that there was no. Die head temperature is 265 ℃
A film could be formed at a temperature of up to 280 ° C., and a thin film having a thickness of 10 μm or less was stably obtained in these temperature ranges.

Comparative Example 1 The melt tension of X-1 at 300 ° C. (FT + 43 ° C.) was 3.5 g. 295 ° C (FT +
38 ° C). 305 ° C (FT + 48
C), the melt tension was 1 g or less, which was too low to measure. An attempt was made to form a film of X-1 under the same conditions as in Example 1, but a film of about 10 μm could not be stably obtained. Only under the limited conditions shown in Table 2, a film having a thickness of about 20 μm was barely obtained. A film could be formed at a die head temperature of 270 ° C to 280 ° C, and a thin film of 10 µm or less was obtained in a very narrow temperature range of only around 270 ° C.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

According to the present invention, the thermoplastic resin exhibiting liquid crystallinity when melted has a high melt tension, can be molded in a wide temperature range, and has excellent workability. In this way, various molded articles can be easily obtained by using the thermoplastic resin, and thus have great industrial value. In particular, a film melt-extruded from an aromatic liquid crystalline polyester has a good film appearance and can be formed into a thin film. The film can be used as a gas barrier layer of a single-layer film or a multilayer film with another thermoplastic resin, and can be used for various packaging applications such as food packaging, medicine packaging, cosmetic packaging, and electronic material packaging. Further, it can be used as various molded articles such as blow molded articles, injection molded articles, hot press molded articles, calenders and roll molded articles, which are excellent in gas barrier properties and used for various containers.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 67:04 C08L 67:04 (72) Inventor Yoshitaka Obe 6 Kitahara, Tsukuba, Ibaraki Prefecture Sumitomo Chemical Co., Ltd. F term (reference) 4F070 AA48 AB09 AB15 BA02 BA04 BB08 4F071 AA48 AF35A AH04 AH05 BA01 BB04 BB05 BB06 BC01 BC04 4F201 AA27 AG01 BA04 BC03 BC12 BC15 BC21 BN01 BN08

Claims (12)

[Claims] 1. A thermoplastic resin exhibiting liquid crystallinity upon melting is melted and then solidified, and the volume of the obtained solidified product is 1 mm.
^A method for producing a thermoplastic resin exhibiting liquid crystallinity upon melting, comprising heating a thermoplastic resin having a size of ³ to 50,000 mm3 at a temperature equal to or lower than a flow temperature of the solidified product in an inert gas atmosphere. Here, the flow temperature is measured by a capillary rheometer, and the resin heated and melted at a heating rate of 4 ° C./min, under a load of 100 kgf / cm ² and an inner diameter of 1 m
m, a temperature (° C.) at which the melt viscosity shows 48,000 poise when extruded from a nozzle having a length of 10 mm. Wherein after melting the thermoplastic resin exhibiting liquid crystallinity when melted, solidified, and grinding the resulting solidified product, the thermoplastic volume of milled solidified product is 1mm ³ ~50000mm ³ A method for producing a thermoplastic resin exhibiting liquid crystallinity upon melting, wherein the resin is subjected to a heat treatment in an inert gas atmosphere at a temperature equal to or lower than the flow temperature of the solidified product as defined in claim 1. 3. The method for producing a thermoplastic resin according to claim 1, wherein the heat treatment time is 1 minute or more and 24 hours or less. 4. The heat treatment according to claim 1, wherein the flow temperature of the thermoplastic resin exhibiting liquid crystallinity upon melting after the heat treatment is higher than that before the heat treatment by 3 ° C. or more. A method for producing a plastic resin. 5. The maximum value of the melt tension measured at a temperature higher by at least 25 ° C. than the flow temperature of a thermoplastic resin exhibiting liquid crystallinity upon melting after heat treatment becomes 0.3 g or more larger than that before heat treatment. 5. The method according to claim 1, wherein
The method for producing a thermoplastic resin according to any one of the above. Here, the melt tension is the inside diameter of the capillary of 2.095 m
m, length 8.0 mm, inner diameter of the piston to be extruded 10 mm,
It refers to the tension (g) when the sample is taken up in the form of a thread while being automatically accelerated by a variable speed winder at a piston extrusion speed of 5.0 mm / min and cut. 6. The melt tension measured at a temperature 25 ° C. or more higher than the flow temperature of a thermoplastic resin exhibiting optical anisotropy at the time of melting after heat treatment is 4.0 g or more and 30.0 g or less. The method for producing a thermoplastic resin according to claim 1. 7. A thermoplastic resin exhibiting optical anisotropy when melted comprises the following repeating unit (A) in an amount of 25% of the entire repeating unit.
The method for producing a thermoplastic resin according to any one of claims 1 to 6, wherein the content of the thermoplastic resin is from 80 to 80 mol%. 8. The thermoplastic resin exhibiting optical anisotropy upon melting is an aromatic liquid crystalline polyester comprising two or more aromatic hydroxycarboxylic acid units, wherein the repeating unit (A) according to claim 5 is used. 25 to 80 mol% of the entire repeating unit, and the following repeating unit (B) is 20% of the entire repeating unit.
The method for producing a thermoplastic resin according to any one of claims 1 to 6, wherein the content of the thermoplastic resin is from 75 to 75 mol%. 9. A thermoplastic resin having optical anisotropy upon melting is an aromatic liquid crystalline polyester comprising an aromatic dicarboxylic acid unit, an aromatic diol unit and an aromatic hydroxycarboxylic acid unit. Item 7. The method for producing a thermoplastic resin according to any one of Items 1 to 6. 10. A thermoplastic resin exhibiting liquid crystallinity upon melting obtained by the method for producing a thermoplastic resin according to any one of claims 1 to 9, wherein the thermoplastic resin is subjected to hot press molding, injection molding, extrusion molding, and melting. A molded article formed by a spin molding method, a calendar molding method or a roll molding method. 11. The molded article according to claim 10, wherein the molded article is a film. 12. The molded article according to claim 10, wherein the molded article is a hollow molded article.