JPH0579100B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to curing of particulate polyphenylene sulfide (hereinafter referred to as PPS). More specifically, the present invention relates to a method of curing PPS with less uneven curing. [Prior Art and Problems] Normally, since PPS has a low melt viscosity, it is hardened to increase its viscosity to a desired viscosity range before being subjected to molding. In this case, curing is generally done by heating particulate PPS at a temperature below the melting point of PPS in an oxygen-containing atmosphere.
For example, a method using a forced heating air circulation dryer as described in U.S. Pat. No. 3,354,129, a method using a fluidized bed as described in U.S. Pat. No. 3,793,256, and a method using a fixed heating mixer in a container with double spiral stirring blades as in U.S. Pat. No. 3,717,620. This is done using a hardening method. However, these curing methods have various problems and cannot be said to be industrially advantageous. In other words, in the method using a forced heating air circulation type dryer, a wide temperature distribution occurs inside the machine, and
There is also a difference in oxygen concentration between the surface and inside of the PPS particle layer, making uniform curing difficult. Furthermore, when using a fluidized bed, the temperature within the bed can be maintained uniformly by increasing the air flow rate, but the scattering of powder increases and the yield decreases, which is not practical. Furthermore, in the curing method using a heating mixer fixed to a container with double spiral stirring blades, the particulate PPS is pressed against the inner wall of the container, so the shear stress generated between the stirring blades and the container wall causes agglomeration of PPS particles and A phenomenon of adhesion and solidification occurs, causing problems such as uneven curing due to local heating, a decrease in yield due to adhesion, and difficulty in removing the wall adhesion layer. [Means for Solving the Problems] In view of the above problems, the inventors of the present invention have conducted intensive studies, and have solved the above problems by using a container rotating type heating device equipped with a gas introduction section and a gas exhaust section. We have found that this problem can be solved, leading to the present invention. That is, the present invention relates to a PPS curing method in which particulate polyphenylene sulfide (hereinafter abbreviated as PPS) is heated to below the melting point of PPS to thicken it to a desired viscosity range. The present invention provides a method for curing PPS, which is characterized by curing using a container rotating type heating device equipped with a container. The PPS used in the present invention has the general formula

It contains 70 mol% or more of the structural unit represented by the formula. PPS polymerization methods include polymerizing p-dichlorobenzene in the presence of sulfur and sodium carbonate, or polymerizing sodium sulfide, sodium hydrosulfide and sodium hydroxide, hydrogen sulfide and sodium hydroxide, or sodium aminoalkanoalkaline in a polar solvent. Examples include methods of polymerization in the presence of ate, self-condensation of p-chlorothiophenol, etc.
A suitable method is to react sodium sulfide with p-dichlorobenzene in an amide solvent such as N-methylpyrrolidone or dimethylacetamide or a sulfonic solvent such as sulfolane. At this time, in order to adjust the degree of polymerization, it is a preferable method to add an alkali metal salt of carboxylic acid or sulfonic acid, or to add alkali hydroxide. As a copolymer component, if it is less than 30 mol%, it is a meta bond.

[Formula] Ortho bond

【formula】 ether bond

[Formula] Sulfone bond

[Formula] biphenyl join

[Formula] Carbonyl bond If

[Formula] Substituted phenyl sulfide bond

[Formula] where R represents an alkyl group, a nitro group, a phenyl group, an alkoxy group, a carboxylic acid group or a metal base of a carboxylic acid), trifunctional bond

[Formula] etc. may be contained as long as it does not significantly affect the crystallinity of the polymer, but preferably the copolymerization component is
It is preferably 10 mol% or less. In particular, when trifunctional or more functional phenyl, biphenyl, naphthyl sulfide bonds, etc. are selected for copolymerization, the amount is preferably 3 mol% or less, more preferably 1 mol% or less. As a specific method for producing such PPS, for example,
(1) Reaction of halogen-substituted aromatic compounds with alkali sulfides (see U.S. Patent No. 2,513,188, Japanese Patent Publication No. 44-27671 and Japanese Patent Publication No. 45-3368), (2) Alkali catalysts or copper salts of thiophenols, etc. (3) Condensation reaction of aromatic compounds with sulfur chloride in the presence of a Lewis acid catalyst (see US Pat. No. 3,274,165 and British Patent No. 1,160,660).
46-27255 and Belgian Patent No. 29437)
(4)Special Publications Showa 52-12240, Special Publications Showa 54-8719, Special Publications Showa 53
-25588, JP 57-334, JP 55-43139,
Examples include methods for producing high molecular weight PPS described in USP4350810, USP4324886, and the like. In the present invention, it is also possible to mix and use cured PPS with the uncured PPS as required. There are no particular restrictions on the particle size or bulk density range of the particulate PPS used in the present invention, but from the viewpoint of workability or kettle yield (the amount of PPS charged per kettle volume), the particle size is limited to several numbers. Micron or higher, its bulk density is
0.20 g/cm ³ or more is preferable. The container rotating type heating device equipped with a gas introduction section and a gas exhaust section according to the present invention uniformly mixes and heats the particulate PPS in the container body, and prevents forces such as compressive shear from acting on the particulate PPS. First, there are no particular restrictions on the direction of the shape rotation axis or the heating method as long as it does not stay in a specific part. For example, "Latest Powder Process Technology Collection" - Basic Technology Edition - Published by Industrial Technology Center Co., Ltd., pages 108 to 112 10.2 Classification of mixers, 10.3 Mixer descriptions Various container rotary mixers have heating parts, A device equipped with a gas introduction section and a gas exhaust section is used. These container rotary mixers include cylindrical mixers, double cone mixers, regular cubic mixers, twin cylindrical mixers, etc. as described in the above-mentioned literature. Heating methods include heating the container wall by external heating through heat medium circulation, heating the container contents and atmosphere by introducing heated gas, and incorporating a heating element or energy ray irradiation device, either singly or in combination. can be used.
The gas introduction part and the gas exhaust part in the present invention are not limited to any type as long as they can be applied to a container rotary mixer. For example, one or more types of gas transport equipment such as a reciprocating compressor, centrifugal blower, axial flow blower, rotary compressor, and blower, or a vacuum pump and vacuum generating equipment may be installed in the gas introduction hole or the gas exhaust hole, if necessary. Depending on the gas exhaust hole side, install a dust collector such as gravity dust collector, inertial dust collector, centrifugal dust collector, filter dust collector, electric dust collector, washing dust collector, etc., a buff-full plate, a drain pot, etc. on the gas intake hole side. A heater, gas compression cylinder, etc. can be attached to the side. The suction and exhaust capacity of the container rotating heating device used in the present invention must be at least (0.2% of the container internal volume)/min, preferably (1% of the container internal volume)/min or more. If the suction and exhaust capacity is small, curing will be slow and the time required for curing will increase significantly. In addition to these, it is also possible to use a rotary dryer.
In addition, from the viewpoint of preventing scattering of powder, the exhaust hole at the connection part between the gas exhaust part and the container ^should be
For example, when the average particle size is 20 μm, the [intake/exhaust rate (/min)] is preferably selected to be 0.1 (×10 ⁻³ min/cm) or more. A specific example of the container rotation type heating device that can be used in the present invention is shown in FIG. In the apparatus shown in this figure, particulate PPS is heated to below its melting point in a rotary container 1, at which time an oxygen-containing gas is introduced from a gas introduction line 9 (gas introduction part), and at the same time a gas discharge line equipped with a filter 8 is introduced. Gas is exhausted from line 10 (gas exhaust section). In the present invention, in order to carry out the curing reaction of the particulate PPS smoothly and uniformly, the rotation speed of the container is set in the range of 0.1 to 100 RPM, preferably 0.2 to 40 RPM, and the particulate PPS powder is added to the container. Body loading rate is 50%
It should be below, preferably 45% or less. If the rotation speed is too low, the powder will not be mixed sufficiently, and if it is too high, the powder will rotate together, resulting in uneven curing. Also, if the powder charging rate is too large, the mixing of the powder becomes non-uniform, resulting in uneven curing, and the scattering of the powder from the exhaust hole becomes large, which is not preferable. The curing method of the present invention is carried out by heating powdered PPS in an oxygen-containing atmosphere at a temperature below the melting point of PPS until a desired melt viscosity range is reached. Curing of PPS requires an oxygen-containing atmosphere, and for example, oxygen, air, and a mixture of these and an inert gas such as nitrogen are used. In the curing method of the present invention, heating must be performed at a temperature below the melting point of PPS, preferably within a range of 5 to 100°C below the melting point. If the heating temperature is too high, the PPS particles tend to fuse together, resulting in significantly increased particle size or adhesion to the container wall, which is undesirable. On the other hand, if the heating temperature is too low, curing takes a long time and is not economical. Also, the heating time is generally 10
It usually takes 1 hour to 1 day.
In addition, the PPS curing in the present invention is performed when the PPS melt flow rate (measured according to ASTM 1238-70, measurement temperature 315.6°C, load 5 kg, unit g/10 minutes) is 1 to 1.
This is carried out to about 2000, preferably 50 to 500. The PPS obtained by the curing method of the present invention can contain an arbitrary filler in an amount of 70% by weight or less in the composition in order to improve performance as an engineering plastic such as strength, heat resistance, and dimensional stability. . Specifically, fillers include glass fiber, carbon fiber, potassium titanate, asbestos,
Fibrous reinforcement such as silicon carbide, ceramic fiber, metal fiber, silicon nitride, barium sulfate, calcium sulfate, kaolin, clay, pyrophyllide,
Bentonite, sericite, zeolite, mica, mica, nephelinsinite, talc, atalbalzite, wollastonite, RMF, ferrite, calcium silicate, calcium carbonate, magnesium carbonate, doronite, antimony trioxide,
Examples include inorganic fillers such as zinc oxide, titanium oxide, magnesium oxide, iron oxide, molybdenum dioxide, graphite, gypsum, glass beads, glass balloons, and quartz powder, and organic reinforcing agents such as aramid fibers. When adding these reinforcements or fillers,
Known silane coupling agents can be used. In addition, PPS obtained by the curing method of the present invention
are polyphenylene oxide, polyarylate, polyamide, polybutylene terephthalate,
Thermoplastic resins such as polyetheretherketone and polyimide, epoxy resins such as novolac type epoxy resins, polyolefins such as polyethylene and polypropylene, α-olefin copolymers such as maleic acid-modified polypropylene, or nylon.
11/ Thermoplastic elastomer SBR such as polyether polyamide elastomer, hydrogenated SBR, etc. can be contained. Preparation of the composition of PPS obtained according to the present invention consists of:
This is possible using various known methods. For example, the raw materials may be uniformly mixed in advance using a mixer such as a tumbler or Henschel mixer, fed to a single or twin screw extruder, melted and kneaded at 230 to 400°C, and then pelletized. I can do it. (Effects of the Invention) The curing method of the present invention cures particulate PPS using an improved container rotating heating device, which greatly overcomes the problems of conventional methods in terms of curing uniformity and yield. This is of great industrial significance. PPS obtained by the curing method of the present invention can be used not only for injection molded products or compression molded products such as electrical and electronic parts, but also for extrusion molded products such as fibers, sheets, films, tubes, etc. It can be used for blow molded products, transfer molded products, etc. (Example) Next, the present invention will be specifically explained using examples. Example 1 Melt flow rate (hereinafter abbreviated as MFR) 4000
4.5 kg of particulate PPS was charged into a 30-container rotating double circular heating device equipped with a gas introduction device, a gas exhaust device, and a heat medium circulation jacket. Next, the container was started to rotate at a rotational speed of 3 RPM, the heating medium was circulated through the jacket, and the temperature of the heating medium was raised from room temperature to 260° C. in 1.5 hours. Air heated to 260℃ 6
temperature of the heating medium while being introduced into the container at a flow rate of /min.
Heated at 255°C for 7 hours. The air was then switched to nitrogen and cooled to 100° C. for 2 hours. After cooling to room temperature, the contents were taken out. Immediately before removal, samples were taken from each position shown in the table, and the MFR was measured. The results are shown in the table. Comparative Example 1 Curing was carried out in the same manner as in Example 1, except that a normal device in which a gas introduction device was not installed in the container rotation type heating device was used. From the table, it can be seen that without a gas introduction device, curing is significantly delayed and cannot be used for curing. Comparative Example 2 1.0 kg of the same particulate PPS as in Example 1 was charged into a 10-vessel fixed heating mixer (vertical type) equipped with a double helical stirring blade. Rotation of the stirring blade was started at 60 RPM, the heat medium was circulated through the jacket, and the temperature of the heat medium was raised from room temperature to 255°C in 1.5 hours. Air heated to 255°C was introduced from the bottom of the apparatus at a flow rate of 2/min, and heated at 255°C for 7 hours. The air was then switched to nitrogen and cooled to 100° C. for 2 hours.
After cooling to room temperature, the contents were taken out. A hard adhesive layer of PPS is formed in the gap between the container wall and the stirring blade.
The yield also decreased. The results are shown in the table. Comparative Example 3 15 kg of the same particulate PPS as in Example 1 was charged into a fluidized bed having a fluidized bed area of 0.15 m ² . When the wind speed of the hot air at 460°C was 0.09 m/sec or less, a part of the powder did not fluidize and melted to form a lump. On the other hand, if the wind speed is higher than 0.10 m/sec, the powder will scatter more and the bag filter will be easily clogged.
m/sec, MFR after 7 hours was 800 g/10 minutes, and the curing speed was slow. Comparative Example 4 The same particulate PPS as in Example 1 was put into a 30 x 20 cm stainless steel vat to a thickness of 2 cm, and
It was left standing at 260°C for 7 hours in a stage-type forced heating air circulation dryer, and the MFR of the upper, middle, and lower stages, and the MFR of the surface layer and lower layer of the middle stage were measured. It can be seen from the table that the curing unevenness is large.

【table】 [Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a container rotating type heating device equipped with a gas introduction section and a gas exhaust section used when carrying out the method of the present invention. 1... Rotating container, 2... Heat medium jacket, 3
... Heat medium inlet line, 4 ... Heat medium outlet line, 5
...Rotary joint, 6...Bearing, 7...
Container lid, 8... Filter, 9... Gas introduction line, 10... Gas discharge line, 11... Bush, 12... Teflon seal, 13... Drive gear, 14... Motor and transmission, 15... ...Drive chain, 16...Strut, 17...Thermometer, 18
... Rheometer, 19 ... Heater, 20 ... Air pump, 21 ... Filter, 22 ... Switching valve,
23...Nitrogen gas line, 24...Air line,
25...liquid distillate, 26...filter.

Claims (1)

[Claims] 1 In a polyphenylene sulfide curing method in which particulate polyphenylene sulfide is heated to below the melting point of PPS and thickened to a desired viscosity range,
A method for curing polyphenylene sulfide, which is characterized by curing using a container rotating heating device equipped with a gas introduction section and a gas exhaust section.