JPH08157718A - Polyarylene sulfide resin composition - Google Patents

Abstract

PURPOSE: To obtain a PAS resin composition having low molding shrinkage and excellent moldability and therefore suited for e.g. insert molding. CONSTITUTION: This resin composition comprises 100 pts.wt. high-molecular- weight polyarylene sulfide obtained by heating a polyarylene sulfide produced by reacting an alkali metal sulfide with a dihaloaromatic compound in an organic amide solvent, condensing a part of the vapor phase in the reactor by cooling the vapor phase during the reaction, and returning the condensate to the liquid phase in a gas phase oxidizing atmosphere and 10-300 pts.wt. potassium titanate whiskers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyarylene sulfide resin composition having a small shrinkage rate and suitable for insert molding and the like.

[0002]

2. Description of the Related Art Conventionally, as a plastic for insert molding, for example, polybutylene terephthalate (PB) is used.
T) was used. However, from the viewpoint of practicality, there is a drawback that mechanical strength such as rigidity and impact resistance is poor.

In view of the current situation, polyphenylene sulfide (PPS) containing glass fiber is used in place of the above plastics. However, these have a large shrinkage ratio during molding and are inferior in moldability.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a polyarylene sulfide (hereinafter sometimes abbreviated as PAS) resin composition having a small shrinkage factor during molding and excellent moldability.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, a PAS produced by reacting an alkali metal sulfide with a dihaloaromatic compound in an organic amide solvent and cooling the gas phase portion of the reaction vessel during the reaction is obtained by further heat treatment. The present inventors have found that by adding a predetermined amount of potassium titanate whiskers to high molecular weight PAS, the shrinkage rate of PAS can be reduced and the moldability can be significantly improved, and the present invention has been completed.

That is, according to the present invention, (A) an alkali sulfide is reacted with a dihaloaromatic compound in an organic amide solvent, and the gas phase portion of the reaction vessel is cooled during the reaction. Polyarylene sulfide (a) produced by condensing a part of the gas phase inside and refluxing it to the liquid phase
Is a polyarylene sulfide resin composition containing 100 parts by weight of a high molecular weight polyarylene sulfide obtained by heat treatment in a gas-phase oxidizing atmosphere and 10 to 300 parts by weight of (B) potassium titanate whiskers.

As a method for producing PAS (a) by cooling a gas phase portion of the reaction can of the present invention to condense a part of the gas phase in the reaction can and refluxing it to a liquid phase, The method described in Kaihei 5-222196 can be used.

The refluxed liquid has a high water content compared to the liquid phase bulk due to the vapor pressure difference between water and the amide solvent.
This reflux liquid having a high water content forms a layer having a high water content on the reaction solution. As a result, the residual alkali metal sulfide (for example, Na ₂ S), alkali metal halide (for example, NaCl), oligomer and the like are contained in a large amount in the layer. In the conventional method, at a high temperature of 230 ° C. or higher, when the generated PAS and the raw materials such as Na ₂ S and by-products are uniformly mixed, not only high-molecular-weight PAS cannot be obtained but Depolymerization of PAS also occurred, and thiophenol by-product was observed. However, in the present invention, by positively cooling the gas phase portion of the reaction vessel and returning a large amount of water-rich reflux liquid to the upper portion of the liquid phase, the above-mentioned inconvenient phenomenon can be avoided and the reaction is inhibited. Of high molecular weight PA
It seems that S can be obtained. However, the present invention is not limited only to the effects due to the above-mentioned phenomenon, and high-molecular weight PAS can be obtained by various influences caused by cooling the gas phase portion.

In the present invention, it is not necessary to add water during the reaction unlike the conventional method. However, the addition of water is not excluded at all. However, some of the advantages of the present invention are lost if the operation of adding water is performed. Therefore, preferably, the total water content in the polymerization reaction system is constant throughout the reaction.

The gas phase portion of the reactor can be cooled by external cooling or internal cooling, and can be performed by a cooling means known per se. For example, a method of flowing a cooling medium into an internal coil installed in the upper part of the reaction can, a method of flowing a cooling medium into an external coil or jacket wound around the upper part of the outside of the reaction can, and a reflux condenser installed in the upper part of the reaction can are used. The method may be such as sprinkling water or blowing gas (air, nitrogen, etc.) on the upper part of the outside of the reaction can. Any method is effective as long as it has the effect of increasing the reflux amount in the can. May be used. If the outside air temperature is relatively low (for example, room temperature), it is also possible to perform appropriate cooling by removing the heat insulating material conventionally provided on the upper part of the reaction can. In the case of external cooling, water condensed on the reactor wall surface
The amide-based solvent mixture enters the liquid phase along the wall of the reaction vessel. Thus, the water-rich mixture pools on top of the liquid phase,
Keep the water content there relatively high. For internal cooling,
The mixture condensed on the cooling surface likewise travels along the surface of the cooling device or the wall of the reaction vessel into the liquid phase.

On the other hand, the temperature of the liquid phase bulk is maintained at a predetermined constant temperature or controlled according to a predetermined temperature profile. 230 to 275 for constant temperature
It is preferable to carry out the reaction at a temperature of ° C for 0.1 to 20 hours. More preferably, the temperature is 240 to 265 ° C. and the time is 1 to 6 hours. To obtain higher molecular weight PAS, it is preferable to use a reaction temperature profile of two or more steps. This 2
When carrying out the stepwise operation, the first step is preferably carried out at a temperature of 195 to 240 ° C. If the temperature is low, the reaction rate is too slow, which is not practical. If the temperature is higher than 240 ° C., the reaction rate is too fast, PAS having a sufficiently high molecular weight cannot be obtained, and the side reaction rate remarkably increases. The end of the first stage is
Dihalo aromatic compound residual rate in the polymerization reaction system is 1 mol% to 40
It is preferable to carry out at a time of mol% and a molecular weight in the range of 3,000 to 20,000. More preferably, the residual ratio of the dihalo-aromatic compound in the polymerization reaction system is 2 mol% to 15 mol% and the molecular weight is 5,000 to 15,000. Residual rate is 40 mol%
When it is more than 1, the side reaction such as depolymerization is likely to occur in the second step reaction, while when it is less than 1 mol%, the high molecular weight P is finally obtained.
It is difficult to get AS. Thereafter, the temperature is raised, and the reaction in the final stage is preferably carried out at a reaction temperature of 240 to 270 ° C. for 1 to 10 hours. PAS with sufficiently high molecular weight at low temperature
At a temperature higher than 270 ° C., side reactions such as depolymerization are likely to occur, making it difficult to stably obtain a high molecular weight product.

As an actual operation, first, dehydration or water addition is carried out in an inert gas atmosphere, if necessary, so that the amount of water in the alkali metal sulfide in the amide solvent becomes a predetermined amount. The water content is preferably alkali metal sulfide 1
The amount is 0.5 to 2.5 mol, especially 0.8 to 1.2 mol per mol. If it exceeds the above range, the reaction rate becomes small,
Moreover, the amount of by-products such as phenol increases in the filtrate after the reaction, and the degree of polymerization does not increase. If the amount is less than the above range, the reaction rate is too fast to obtain a sufficiently high molecular weight product.

In the case of the one-step reaction at a constant temperature, the cooling of the gas phase portion during the reaction is preferably performed from the start of the reaction, but it must be performed at least during the temperature increase of 250 ° C. or less. In the multi-stage reaction, it is preferable to perform cooling from the first-stage reaction, but it is preferable to perform cooling at the latest after the completion of the first-stage reaction. Regarding the degree of cooling effect, the pressure inside the reaction vessel is usually the most suitable index. The absolute value of the pressure varies depending on the characteristics of the reaction vessel, the stirring state, the water content in the system, the molar ratio of the dihalo aromatic compound to the alkali metal sulfide, and the like. However, as compared with the case of not cooling under the same reaction conditions, if the reactor pressure is decreased, the amount of reflux liquid is increased, which means that the temperature at the reaction solution gas-liquid interface is decreased. It is considered that the degree of relative decrease indicates the degree of separation between the layer having a high water content and the layer having no water content. Therefore, it is preferable to cool the reactor so that the internal pressure of the reactor becomes lower than that in the case where no cooling is performed. The degree of cooling can be appropriately set by those skilled in the art according to the equipment used, operating conditions, and the like.

The organic amide solvent used here is PA
Known for S polymerization, for example N-methylpyrrolidone (NMP), N, N-dimethylformamide,
N, N-dimethylacetamide, N-methylcaprolactam, etc., and mixtures thereof can be used, with NMP being preferred. They all have a lower vapor pressure than water.

Alkali metal sulfides are also known, for example lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide and mixtures thereof. These hydrates and aqueous solutions may be used. Further, hydrosulfides and hydrates corresponding to these can be used after being neutralized with the corresponding hydroxides.
Inexpensive sodium sulfide is preferred.

The dihaloaromatic compound is, for example, Japanese Patent Publication No.
It can be selected from those described in JP-A-5-3368, but is preferably p-dichlorobenzene. Further, a copolymer can be obtained by using a small amount (20 mol% or less) of one or more kinds of para, meta or orthodihalo compounds of diphenyl ether, diphenyl sulfone or biphenyl. For example, m-dichlorobenzene, o-dichlorobenzene,
p, p'-dichlorodiphenyl ether, m, p'-dichlorodiphenyl ether, m, m'-dichlorodiphenyl ether, p, p'-dichlorodiphenyl sulfone, m, p'-dichlorodiphenyl sulfone, m, m '
-Dichlorodiphenyl sulfone, p, p'-dichlorobiphenyl, m, p'-dichlorobiphenyl, m, m'-
It is dichlorobiphenyl.

In order to increase the molecular weight of PAS,
For example, 1,3,5-trichlorobenzene, 1,2,4-
A polyhalo compound such as trichlorobenzene can also be used in a concentration of preferably 5 mol% or less based on the total amount of para and metadihalo aromatic compounds.

Further, as a small amount of other additives, a terminal terminating agent and a monohalogenated compound as a modifier can be used in combination.

The PAS (a) thus obtained is separated from by-products by a post-treatment method known to those skilled in the art.

In the present invention, it is preferable that the PAS (a) obtained as described above is further acid-treated. The acid treatment is preferably carried out at a temperature of 100 ° C. or lower, particularly preferably 40 to 80 ° C. If the temperature exceeds the above upper limit, the PAS molecular weight after acid treatment decreases, which is not preferable. On the other hand, if the temperature is lower than 40 ° C., the remaining inorganic salt is deposited to reduce the fluidity of the slurry and hinder the continuous treatment process, which is not preferable. The concentration of the acid solution used for the acid treatment is preferably 0.01 to
It is 5.0% by weight. The pH of the acid solution is preferably 4.0 to 5.0 after the acid treatment. By adopting the above concentration and pH, the P
Most of -SNa and -COONa ends in AS are -S
Can be converted to H and -COOH ends,
It is preferable because it can prevent corrosion of plant equipment and the like. The time required for the acid treatment depends on the acid treatment temperature and the concentration of the acid solution, but it is preferably 5 minutes or longer, particularly preferably 10 minutes or longer. Below the above, -SN in PAS
It is not preferable because the a and -COONa terminals cannot be sufficiently converted to -SH and -COOH terminals. For the acid treatment, for example, acetic acid, formic acid, oxalic acid, phthalic acid, hydrochloric acid, phosphoric acid, sulfuric acid, sulfuric acid, nitric acid, boric acid, carbonic acid, etc. are used, and acetic acid is particularly preferable. By carrying out the treatment, sodium as an impurity in PAS can be reduced. By performing the above-mentioned acid treatment, the shrinkage rate of the resin composition at the time of molding can be further reduced.

Next, PAS (ii) is heat-treated in a gas phase oxidizing atmosphere. The heat treatment can be carried out by a known method. The temperature for the heat treatment is preferably 100 to 280 ° C., particularly preferably 170 to 250.
° C. If the temperature is below the above range, the time required for heat treatment will increase, and if it exceeds the above range, the treated P
It is not preferable because the thermal stability of AS during melting is poor. The time required for the thermal oxidation treatment depends on the above heating temperature or the desired PAS melt viscosity, but is preferably 0.5.
-25 hours, particularly preferably 5-20 hours. If the time is less than the above range, high molecular weight PAS cannot be obtained,
If the amount exceeds the above range, generation of microgels in the treated PAS increases, which is not preferable.

The above heat treatment is preferably carried out in a gas phase oxidizing atmosphere of an oxygen containing gas such as air, pure oxygen or the like or a mixture of these with any suitable inert gas. Examples of the inert gas include water vapor, nitrogen, carbon dioxide and the like, or a mixture thereof. The concentration of oxygen in the oxygen-containing gas is preferably 0.5 to 50% by volume, particularly preferably 10 to 25% by volume. When the oxygen concentration exceeds the above range, the radical generation amount increases, the viscosity at the time of melting becomes remarkable, and the hue becomes dark, which is not preferable. When the oxygen concentration is less than the above range, the thermal oxidation rate becomes slow, which is not preferable.

The apparatus for performing the heat treatment of the present invention may be a batch type or a continuous type, and a known apparatus can be used. For example, in a closed container equipped with a stirrer, PA
A device for contacting S with an oxygen-containing gas can be mentioned, and a fluidized bed thermal oxidation treatment device equipped with a stirrer is preferably used. By using the device, the temperature distribution in the tank can be narrowed. As a result, the thermal oxidation can be promoted and the non-uniform molecular weight can be prevented.

The component (B) potassium titanate whiskers can be obtained, for example, by the general formula K ₂ O.n (TiO ₂ ) or K ₂ O.
_{· N (TiO 2) · 1/2} (H 2 O) ( wherein, n 2
It represents a single crystal fiber. For example, 4-potassium titanate fiber, 6-potassium titanate fiber, 8-potassium titanate fiber, etc. may be mentioned, and these may be used alone or in a mixture of two or more. The potassium titanate whiskers have an average fiber diameter of preferably 2.0 μm or less, particularly preferably 0.3 to 1.5 μm,
The average fiber length is preferably 5 to 50 μm, particularly preferably 5 to 20 μm, and the aspect ratio is preferably 200 or less, particularly preferably 5 to 70. These potassium titanate whiskers are vinyl silane, epoxy silane,
It may be surface-treated with one or more silane coupling agents such as aminosilane and mercaptosilane.

In the resin composition of the present invention, the component (A)
10 to 300 parts by weight of the component (B) with respect to 100 parts by weight,
Preferably 20 to 100 parts by weight are blended. Ingredient (B)
Is less than the above range, the shrinkage rate of the resin composition increases and the moldability deteriorates. If it exceeds the above range, mechanical strength such as rigidity and impact resistance is lowered.

The resin composition of the present invention may contain conventional additives within a range that does not impair the object of the invention. For example, silica as an inorganic filler, alumina, talc, mica, kaolin, clay, silica-alumina, titanium oxide, calcium carbonate, calcium silicate, calcium phosphate, calcium sulfate, magnesium carbonate, magnesium oxide, magnesium phosphate, silicon nitride, Granules such as glass, hydrotalcite, zirconium oxide,
A powdery or scale-like material or a fibrous material such as glass fiber, carbon fiber, mica ceramic fiber or the like can be blended. These inorganic fillers can be used alone or in combination of two or more. Further, these inorganic fillers may be treated with a silane coupling agent or a titanate coupling agent. From the viewpoint of melt processability, the blending ratio of the filler is preferably 30% by weight or less in the resin composition. Further, if necessary, an antioxidant, a heat stabilizer, a lubricant, a release agent, a colorant, etc. It is also possible to add the additive of.

The method of mixing the above components is not particularly limited. A generally widely used method, for example, a method of mixing each component with a mixer such as a Henschel mixer can be used.

The resin composition of the present invention is usually melt-kneaded in an extruder and pelletized, and then, for example, injection-molded or compression-molded into a desired shape. It is preferably used for insert molding.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0030]

[Examples] In the examples, the shrinkage was measured by measuring the dimension (X ₂ ) in the resin flow direction and the dimension (Y ₂ ) in the direction perpendicular to the direction for each test piece, and using the following formula, MD shrinkage The rate and TD shrinkage were calculated and evaluated. Where X ₁ and Y ₁
Indicates the inner dimension of the mold in the resin flow direction and the inner dimension of the mold in the direction perpendicular to the resin flow direction, respectively.

[0031]

MD contraction rate (%) = [(X ₁ −X ₂ ) / X ₁ ] × 100

[0032]

TD shrinkage (%) = [(Y ₁ −Y ₂ ) / Y ₁ ] × 100 Melt viscosity V ₆ is calculated by Shimadzu Flow Tester CFT-
Using 500 A, 320 ° C., load 20 kgf / cm ² ,
It is a viscosity (poise) measured after holding for 6 minutes at L / D = 10.

[0033]

Polymerization Example 1 523.1 kg of flaky sodium sulfide (60.8% by weight Na ₂ S) was placed in a 4 m ³ autoclave.
Then, 1200 kg of N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) was charged. With stirring under a nitrogen stream, the temperature was raised to 204 ° C., and 126.3 kg of water was distilled off. Then, seal the autoclave 180
After cooling to ℃, p-dichlorobenzene (hereinafter p-D
597.2 kg and NMP40
I charged 0 kg. 1 at a liquid temperature of 150 ° C using nitrogen gas
The temperature was started by pressurizing to kg / cm ² G. Liquid temperature 220
While stirring at 3 ° C. for 3 hours, a cooling medium of 20 ° C. was flowed around the coil wound around the upper part of the autoclave to cool it. After that, the temperature was raised, the liquid temperature was stirred at 260 ° C. for 3 hours, the temperature was then lowered, and the cooling of the upper part of the autoclave was stopped. During cooling of the upper part of the autoclave, the liquid temperature was kept constant so as not to drop. The maximum pressure during the reaction is 8.81 kg / cm ² G
Met.

The obtained slurry was repeatedly filtered and washed with warm water by a conventional method and dried at 130 ° C. for about 4 hours in a hot air circulation dryer to obtain a white powdery intermediate product.

Next, the above intermediate product was charged into a 5 m ³ thermal oxidation treatment apparatus and stirred at a tank temperature of 220 ° C. for 4 hours.
Then, it cooled and obtained the product. Obtained product (P-1)
The melt viscosity V ₆ thereof was 1,500 poise.

[0036]

Polymerization Example 2 524.8 kg of flaky sodium sulfide (60.6 wt% Na ₂ S) was placed in a 4 m ³ autoclave.
And 1200 kg of NMP was charged. The temperature was raised to 204 ° C. with stirring under a nitrogen stream to distill 125.4 kg of water. After that, the autoclave was sealed and cooled to 180 ° C, p-DCB596.0kg and NMP400k.
I charged g. 1kg with liquid temperature of 150 ℃ using nitrogen gas
The pressure was increased to / cm ² G and the temperature rise was started. Liquid temperature is 220 ℃
From that point, water was sprinkled with a water sprinkler attached outside the upper part of the autoclave to cool the upper part of the autoclave. Thereafter, the temperature was raised to bring the liquid temperature to 260 ° C., and then the mixture was stirred at that temperature for 2 hours. Next, the temperature was lowered and the cooling of the upper part of the autoclave was stopped. During cooling of the upper part of the autoclave, the liquid temperature was kept constant so as not to drop. The maximum pressure during the reaction was 8.74 kg / cm ² G.

The obtained slurry is filtered by a conventional method,
Washing with warm water was performed twice. Resin product obtained (about 50% by weight of water
2400 kg of water and 4.0 kg of acetic acid are added to
The mixture was stirred at 50 ° C for 30 minutes. The pH after stirring was 4.6. The resin was filtered off, 2400 kg of water was added, the mixture was stirred for 30 minutes and then filtered, which was repeated 5 times.

The product was dried in a hot air circulation dryer at 130 ° C. for about 4 hours to obtain a white powdery intermediate product.

Next, the above intermediate product was charged into a 5 m ³ thermal oxidation treatment apparatus and stirred at a tank temperature of 220 ° C. for 9.5 hours. Then, it cooled and obtained the product. Obtained product (P-
The melt viscosity V ₆ of 2) was 3,280 poise.

[0040]

[Comparative Polymerization Example] 523.1 kg of flaky sodium sulfide (60.8 wt% Na ₂ S) and 1200 kg of NMP were charged into a 4 m ³ autoclave. The temperature was raised to 204 ° C. with stirring under a nitrogen stream, and 124.3 kg of water was distilled off. Then, the autoclave was closed and cooled to 180 ° C., and 614.4 kg of p-DCB and 400 kg of NMP were charged. 1 kg / c at a liquid temperature of 150 ° C using nitrogen gas
Pressurization to m ² G was started to raise the temperature. When the liquid temperature reached 255 ° C, the temperature was stopped and the mixture was stirred for 2 hours. Next, the temperature was lowered to 200 ° C. over 1.5 hours. Maximum pressure during reaction is 1
It was 0.31 kg / cm ² G.

The obtained slurry was repeatedly filtered and washed with warm water by a conventional method and dried at 130 ° C. for about 4 hours in a hot air circulation dryer to obtain a white powdery intermediate product.

Next, the above intermediate product was charged into a 5 m ³ thermal oxidation treatment apparatus and stirred at a tank temperature of 220 ° C. for 25 hours. Then, it cooled and obtained the product. Obtained product (P-
The melt viscosity V ₆ of C1) was 2,890 poise.

[0043]

Examples 1 to 6 and Comparative Examples 1 to 5 With respect to 100 parts by weight of PPS obtained as described above, the amounts (parts by weight) of potassium titanate whiskers (average fiber diameter 1.0 μm) shown in Table 1 were obtained. , Average fiber length 10 μm, aspect ratio 10,
Tibrex, trademark, manufactured by Kawatetsu Mining Co., Ltd.),
Then, using a 35 mmφ twin-screw extruder, melt kneading was performed at a temperature of 320 ° C. to prepare pellets. From the obtained pellets, the cylinder temperature was set to 320 ° C. and the mold temperature was set to 130 ° C., the internal dimension of the mold was 80 mm (X ₁ ) and 80 mm in width
Using a (Y ₁ ) injection molding machine, a test piece having a thickness of 3 mm was prepared and each shrinkage rate was measured.

The above results are shown in Table 1.

[0045]

[Table 1] In Examples 1 to 4, the compounding amount of the component (B) was changed within the range of the present invention. When the blending amount was increased, the shrinkage rate was decreased. Examples 5 and 6 use PPS treated with acetic acid. The shrinkage rates were all good. On the other hand, in Comparative Examples 1 and 2, the blending amount of the component (B) is less than the range of the present invention. The shrinkage rate of each is extremely large. In Comparative Examples 3 to 5, PPS produced without cooling the gas phase portion of the reaction can was used, and the blending amount of the component (B) was the same as in Examples 1 to 3, respectively. In each case, the shrinkage rate is higher than that of each example.

[0046]

INDUSTRIAL APPLICABILITY The present invention provides a PAS resin composition having a small shrinkage factor during molding and excellent moldability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kanichi Kido 3-1, Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Tonen Kagaku Co., Ltd. Technology Development Center

Claims (3)

[Claims] 1. A gas phase in a reaction can by reacting an alkali metal sulfide with a dihaloaromatic compound in an organic amide solvent (A) and cooling a gas phase part of the reaction can during the reaction. 100 parts by weight of a high molecular weight polyarylene sulfide obtained by heat-treating a polyarylene sulfide (a) produced by condensing a part of the mixture and refluxing it in a liquid phase, and (B ) A polyarylene sulfide resin composition containing 10 to 300 parts by weight of potassium titanate whiskers. 2. The (B) potassium titanate whiskers,
The resin composition according to claim 1, which is contained in an amount of 20 to 100 parts by weight. 3. The high-molecular-weight polyarylene sulfide (A) further comprises a polyarylene sulfide (a) of 0.0
The resin composition according to claim 1 or 2, which is obtained by performing an acid treatment with an acid solution having a concentration of 1 to 5.0% by weight at a temperature of 100 ° C or lower, and then performing a heat treatment in a gas phase oxidizing atmosphere. Stuff.