JP2009280794A - Processing method of polyphenylene sulfide resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyphenylene sulfide resin which has excellent melt flowability and molding stability, with which contamination of the mold in molding scarcely occurs, and further with which a filler-reinforced resin composition with excellent toughness is obtained. <P>SOLUTION: The processing method of the polyphenylene sulfide resin is characterized in that the polyphenylene sulfide resin, with a property of its melt flow rate (measured according to ASTM D-1238-70 at 315.5°C and under load of 5,000 g) exceeding 500 g/10 min, is heat treated within a temperature range of 210°C or higher and lower than the melting point of the polyphenylene sulfide resin while allowing an inert gas with oxygen concentration of 2 vol% or less pass through the polyphenylene sulfide resin of 1g at a rate of 0.2 mL/min or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is to obtain a polyphenylene sulfide resin that is excellent in melt fluidity and molding stability, hardly generates mold fouling during molding, and can obtain a filler-reinforced resin composition excellent in toughness. It relates to a processing method.

  Polyphenylene sulfide (hereinafter abbreviated as PPS) resin has suitable properties as engineering plastics such as excellent heat resistance, barrier properties, chemical resistance, electrical insulation properties, and heat and humidity resistance, and is suitable for injection molding and extrusion molding. It is mainly used for various electric / electronic parts, machine parts, automobile parts, films, fibers and so on.

  However, since the PPS resin has a high melting point, the melt processing temperature is high, so that volatile components are easily generated during the melt processing. In particular, PPS resins that require electrical insulation, such as electrical and electronic parts, are subjected to acid treatment in order to reduce the metal content. Such PPS resins generate significant volatile components and may cause molding defects due to mold contamination or mold vent clogging, and reduction of volatile components is strongly desired. Such volatile components can be reduced by heat-treating the PPS resin at a temperature below the melting point, but excessive heat-treatment causes problems such as an excessive increase in melt viscosity and deterioration of moldability due to the formation of a gelled product. The present invention has been found that the volatile component is greatly reduced without significantly increasing the melt viscosity by performing a heat treatment while allowing an inert gas to flow through the PPS resin under specific conditions.

  Heat treatment of PPS resin has been performed for some time. For example, Patent Document 1 discloses that a PPS resin is treated at a temperature of 200 ° C. or higher in an inert atmosphere, and further cured in an oxidizing atmosphere to have a melt viscosity of 5000 poise (500 Pa · s) (300 ° C., shear rate). 200 / sec) or more is disclosed. However, when converted into a melt flow rate, 5000 poise is less than 100 g / 10 min. Since the PPS resin has a melt viscosity that is too high, the fluidity during injection molding is significantly deteriorated. Not suitable for injection molding. The PPS resin disclosed in the patent has a relatively high degree of thermal oxidation treatment, and if the degree of thermal oxidation treatment is too large, the gas reduction effect is saturated, but the melt fluidity is lowered.

  Patent Document 2 discloses a method for curing a PPS resin in a gas-phase oxidizing atmosphere to increase mechanical strength, but does not describe reducing volatile components, and has excellent melt fluidity. There is no description about the compatibility between low-volatile components and low volatile components.

  Patent Document 3 discloses a method for heating and dissolving in an organic solvent as a method for reducing the volatile components of PPS resin, but it is necessary to volatilize and remove a relatively high boiling point solvent. It was disadvantageous both economically and unrealistically.

JP-A-4-339830 (Claims) JP-A-1-121327 (Claims) JP-A-6-172530 (Claims)

  The present invention is a PPS resin capable of obtaining a filler-reinforced resin composition that is relatively inexpensive, excellent in melt fluidity and molding stability, hardly causes mold contamination during molding, and has excellent toughness. This has been achieved as a result of studying to obtain the above.

  Accordingly, the present inventors have studied to solve the above problems, and as a result, polyphenylene sulfide having a melt flow rate (measured at a temperature of 315.5 ° C. and a load of 5000 g according to ASTM D-1238-70) exceeding 500 g / 10 min. Heat treatment in a temperature range of 210 ° C. or higher and lower than the melting point of the polyphenylene sulfide resin while flowing an inert gas having an oxygen concentration of 2% by volume or more to 0.2 g / min or more with respect to 1 g of resin, The present inventors have found a method for treating a PPS resin that is excellent in molding stability, hardly causes mold fouling during molding, and can obtain a filler-reinforced resin composition having excellent toughness, and has reached the present invention.

That is, the present invention is as follows.
1. An inert gas having an oxygen concentration of 2% by volume or less with respect to 1 g of polyphenylene sulfide resin having a melt flow rate (according to ASTM D-1238-70, measured at a temperature of 315.5 ° C. and a load of 5000 g) exceeding 500 g / 10 minutes. In a temperature range of 210 ° C. or higher and lower than the melting point of the polyphenylene sulfide resin, with a flow rate of 0.2 mL / min or more.
2. 2. The method for treating a polyphenylene sulfide resin according to 1, wherein the inert gas contains at least one gas selected from nitrogen, carbon dioxide, water vapor, and a rare gas as a main component.
3. The method for treating a polyphenylene sulfide resin according to 1 or 2, wherein the flow rate of the inert gas is 10 L / min or less with respect to 1 g of the polyphenylene sulfide resin.
4. The method for treating a polyphenylene sulfide resin according to any one of 1 to 3, wherein the heat treatment is performed at a temperature of 210 ° C. or higher and lower than 270 ° C.
5. 5. The method for treating a polyphenylene sulfide resin according to any one of 1 to 4, wherein the polyphenylene sulfide resin is a polyphenylene sulfide resin recovered by a flash method.
6). A method for treating a polyphenylene sulfide resin, comprising subjecting the polyphenylene sulfide resin to an acid treatment and then performing the heat treatment according to any one of 1 to 5.
7). A method for treating a polyphenylene sulfide resin, comprising subjecting the polyphenylene sulfide resin to a hydrothermal treatment at 80 to 250 ° C., followed by an acid treatment, and further performing a heat treatment according to any one of 1 to 5.

  According to the present invention, it is possible to obtain a PPS resin that is excellent in melt fluidity and molding stability, hardly generates mold stains during molding, and can obtain a filler-reinforced resin composition excellent in toughness.

  Hereinafter, embodiments of the present invention will be described in detail.

  The PPS resin obtained by the treatment method of the present invention is a polymer having a repeating unit represented by the following structural formula (I),

From the viewpoint of heat resistance, a polymer containing 70 mol% or more, more preferably 90 mol% or more of a polymer containing a repeating unit represented by the above structural formula is preferred. Moreover, about 30 mol% or less of the repeating unit of the PPS resin may be composed of a repeating unit having the following structure.

  The PPS resin obtained by the treatment method of the present invention has a gas generation amount of 0.3% by weight or less when heated and melted at 320 ° C. for 2 hours under vacuum, preferably 0.28% by weight or less. Preferably it is 0.22% by weight or less. If the amount of gas generated after the heat treatment exceeds 0.3% by weight, volatile components adhering to the mold and the mold vent portion increase, and transfer defects and gas burns are liable to occur. The lower limit of the amount of gas generated after heat treatment is not particularly limited. However, if the heat treatment time is long until the gas generation amount is reduced, it is economically disadvantageous, and a gelled product is generated due to the prolonged heat treatment time. It becomes easy and may become a cause of causing a molding defect.

  The gas generation amount means the amount of an adhesive component in which the gas that volatilizes when the PPS resin is heated and melted under vacuum is cooled and liquefied or solidified, and is a glass in which the PPS resin is vacuum-sealed. It is measured by heating the ampule in a tubular furnace. As the shape of the glass ampule, the abdomen is 100 mm × 25 mm, the neck is 255 mm × 12 mm, and the wall thickness is 1 mm. As a specific measurement method, only the barrel of a glass ampoule in which PPS resin is vacuum-sealed is inserted into a 320 ° C. tubular furnace and heated for 2 hours, so that it becomes volatile at the neck of the ampule not heated by the tubular furnace. The gas is cooled and adheres. After the neck is cut out and weighed, the adhering gas is dissolved in chloroform and removed. The neck is then dried and weighed again. The amount of gas generated is determined from the difference in weight between the neck of the ampoule before and after removing the gas.

  The PPS resin obtained by the treatment method of the present invention preferably has a melt flow rate (measured at a temperature of 315.5 ° C. and a load of 5000 g in accordance with ASTM D-1238-70) exceeding 500 g / 10 minutes. When the melt flow rate is 500 g / 10 min or less, the melt fluidity of the PPS resin composition is remarkably deteriorated and the molding becomes unstable particularly when the filler is used with a high filling, which is not preferable. Although there is no restriction | limiting in particular about the upper limit of the melt viscosity of PPS resin obtained by the processing method of this invention, From a viewpoint of obtaining resin (composition) which has the intensity | strength which can be used practically, 1 Pa * s (300 degreeC, shear rate 1000 / Seconds) or more.

  The present invention is a method for treating a PPS resin, characterized in that heat treatment is performed while flowing an inert gas having an oxygen concentration of 2% by volume or less to 0.2 g / min or more with respect to 1 g of the PPS resin. The PPS resin before the heat treatment essential in the present invention may be obtained by any method. Therefore, a commercially available PPS resin can be used, and it is produced by polymerizing monomers as described below. You can also

  Below, the method to manufacture PPS resin before performing the essential heat processing of this invention is described. First, the contents of the polyhalogenated aromatic compound, sulfidizing agent, polymerization solvent, molecular weight regulator, polymerization aid and polymerization stabilizer used will be described.

[Polyhalogenated aromatic compounds]
A polyhalogenated aromatic compound refers to a compound having two or more halogen atoms in one molecule. Specific examples include p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,4-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, hexa Polyhalogenated aromas such as chlorobenzene, 2,5-dichlorotoluene, 2,5-dichloro-p-xylene, 1,4-dibromobenzene, 1,4-diiodobenzene, 1-methoxy-2,5-dichlorobenzene Group compounds, and preferably p-dichlorobenzene is used. Further, it is possible to combine two or more different polyhalogenated aromatic compounds into a copolymer, but it is preferable to use a p-dihalogenated aromatic compound as a main component.

  The amount of the polyhalogenated aromatic compound used is 0.9 to 2.0 mol, preferably 0.95 to 1.5 mol, per mol of the sulfidizing agent, from the viewpoint of obtaining a PPS resin having a viscosity suitable for processing. More preferably, the range of 1.005 to 1.2 mol can be exemplified.

[Sulfiding agent]
Examples of the sulfiding agent include alkali metal sulfides, alkali metal hydrosulfides, and hydrogen sulfide.

  Specific examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide and a mixture of two or more of these, and sodium sulfide is preferably used. These alkali metal sulfides can be used as hydrates or aqueous mixtures or in the form of anhydrides.

  Specific examples of the alkali metal hydrosulfide include, for example, sodium hydrosulfide, potassium hydrosulfide, lithium hydrosulfide, rubidium hydrosulfide, cesium hydrosulfide and a mixture of two or more of these. Preferably used. These alkali metal hydrosulfides can be used as hydrates or aqueous mixtures or in the form of anhydrides.

  A sulfidizing agent prepared in situ in a reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide can also be used. Further, a sulfidizing agent can be prepared from alkali metal hydrosulfide and alkali metal hydroxide, and transferred to a polymerization tank for use.

  Alternatively, a sulfidizing agent prepared in situ in a reaction system from an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide and hydrogen sulfide can also be used. Further, a sulfidizing agent can be prepared from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide, and transferred to a polymerization tank for use.

  The amount of the sulfidizing agent charged means a residual amount obtained by subtracting the loss from the actual charged amount when a partial loss of the sulfiding agent occurs before the start of the polymerization reaction due to dehydration operation or the like.

  An alkali metal hydroxide and / or an alkaline earth metal hydroxide can be used in combination with the sulfidizing agent. Specific examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and a mixture of two or more thereof. Specific examples of the metal hydroxide include, for example, calcium hydroxide, strontium hydroxide, barium hydroxide, and sodium hydroxide is preferably used.

  When an alkali metal hydrosulfide is used as the sulfiding agent, it is particularly preferable to use an alkali metal hydroxide at the same time, but the amount used is 0.95 to 1. A range of 20 mol, preferably 1.00 to 1.15 mol, more preferably 1.005 to 1.100 mol can be exemplified.

[Polymerization solvent]
It is preferable to use an organic polar solvent as the polymerization solvent. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, caprolactams such as N-methyl-ε-caprolactam, and 1,3-dimethyl-2-imidazolide. Non-, N, N-dimethylacetamide, N, N-dimethylformamide, hexamethylphosphoric acid triamide, dimethyl sulfone, tetramethylene sulfoxide and the like, and mixtures thereof, and the like are all included. It is preferably used because of its high reaction stability. Of these, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) is particularly preferably used.

  The amount of the organic polar solvent used is selected in the range of 2.0 to 10 mol, preferably 2.25 to 6.0 mol, more preferably 2.5 to 5.5 mol per mol of the sulfidizing agent. .

[Molecular weight regulator]
A monohalogen compound (not necessarily an aromatic compound) is used in combination with the polyhalogenated aromatic compound in order to form a terminal of the PPS resin to be produced or to adjust a polymerization reaction or a molecular weight. Can do.

[Polymerization aid]
In order to obtain a PPS resin having a relatively high degree of polymerization in a shorter time, it is also one of preferred embodiments to use a polymerization aid. Here, the polymerization assistant means a substance having an action of increasing the viscosity of the obtained PPS resin. Specific examples of such polymerization aids include, for example, organic carboxylates, water, alkali metal chlorides, organic sulfonates, alkali metal sulfates, alkaline earth metal oxides, alkali metal phosphates and alkaline earths. Metal phosphates and the like. These may be used alone or in combination of two or more. Of these, organic carboxylates and / or water are preferably used.

  Among the organic carboxylates, alkali metal carboxylates are preferable. The alkali metal carboxylate is a general formula R (COOM) n (wherein R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, an alkylaryl group, or an arylalkyl group. Is an alkali metal selected from lithium, sodium, potassium, rubidium and cesium, where n is an integer of 1 to 3). Alkali metal carboxylates can also be used as hydrates, anhydrides or aqueous solutions. Specific examples of the alkali metal carboxylate include, for example, lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium valerate, sodium benzoate, sodium phenylacetate, potassium p-toluate, and mixtures thereof. Can be mentioned.

  The alkali metal carboxylate is an organic acid and one or more compounds selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates, and are allowed to react by adding approximately equal chemical equivalents. You may form by. Among the alkali metal carboxylates, lithium salts are highly soluble in the reaction system and have a large auxiliary effect, but are expensive, and potassium, rubidium and cesium salts are insufficiently soluble in the reaction system. Therefore, sodium acetate, which is inexpensive and has an appropriate solubility in the polymerization system, is most preferably used.

  The amount used in the case of using these polymerization aids is usually in the range of 0.01 mol to 0.7 mol with respect to 1 mol of the charged alkali metal sulfide, and 0.1 to 0.1 in terms of obtaining a higher degree of polymerization. The range of 0.6 mol is preferable, and the range of 0.2 to 0.5 mol is more preferable.

  The use of water as a polymerization aid is one of the effective means for obtaining a resin composition in which fluidity and high toughness are highly balanced. In that case, the addition amount is usually in the range of 0.5 mol to 15 mol with respect to 1 mol of the charged alkali metal sulfide, and in the sense of obtaining a higher degree of polymerization, the range of 0.6 to 10 mol is preferable. The range of 1-5 mol is more preferable.

  There is no particular designation as to the timing of addition of these polymerization aids, which may be added at any time during the previous step, polymerization start, polymerization in the middle to be described later, or may be added in multiple times. When using an alkali metal carboxylate as a polymerization aid, it is more preferable to add it at the start of the previous step or at the start of the polymerization from the viewpoint of easy addition. When water is used as a polymerization aid, it is effective to add the polyhalogenated aromatic compound during the polymerization reaction after charging.

[Polymerization stabilizer]
A polymerization stabilizer can also be used to stabilize the polymerization reaction system and prevent side reactions. The polymerization stabilizer contributes to stabilization of the polymerization reaction system and suppresses undesirable side reactions. One measure of the side reaction is the generation of thiophenol, and the addition of a polymerization stabilizer can suppress the generation of thiophenol. Specific examples of the polymerization stabilizer include compounds such as alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, and alkaline earth metal carbonates. Among these, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide are preferable. Since the alkali metal carboxylate described above also acts as a polymerization stabilizer, it is one of the polymerization stabilizers used in the present invention. In addition, when an alkali metal hydrosulfide is used as a sulfidizing agent, it has been described above that it is particularly preferable to use an alkali metal hydroxide at the same time. Oxides can also be polymerization stabilizers.

  These polymerization stabilizers can be used alone or in combination of two or more. The polymerization stabilizer is usually in a proportion of 0.02 to 0.2 mol, preferably 0.03 to 0.1 mol, more preferably 0.04 to 0.09 mol, relative to 1 mol of the charged alkali metal sulfide. Is preferably used. If this ratio is small, the stabilizing effect is insufficient. Conversely, if it is too much, it is economically disadvantageous and the polymer yield tends to decrease.

  The addition timing of the polymerization stabilizer is not particularly specified, and may be added at any time during the previous step, at the start of polymerization, or during the polymerization described later, or may be added in multiple times. It is more preferable to add at the start of the process or at the start of polymerization from the viewpoint of easy addition.

  Next, the pre-process, the polymerization reaction process, and the recovery process will be specifically described in order.

[pre-process]
The sulfidizing agent is usually used in the form of a hydrate, but before adding the polyhalogenated aromatic compound, the temperature of the mixture containing the organic polar solvent and the sulfidizing agent is increased, and excess water is removed from the system. It is preferable to remove it. In addition, when water is removed excessively by this operation, it is preferable to add and replenish the deficient water.

  Further, as described above, an alkali metal sulfide prepared from an alkali metal hydrosulfide and an alkali metal hydroxide in situ in the reaction system or in a tank different from the polymerization tank is also used as the sulfidizing agent. be able to. Although there is no particular limitation on this method, desirably an alkali metal hydrosulfide and an alkali metal hydroxide are added to the organic polar solvent in an inert gas atmosphere at a temperature ranging from room temperature to 150 ° C., preferably from room temperature to 100 ° C. In addition, there is a method in which the temperature is raised to at least 150 ° C. or more, preferably 180 to 260 ° C. under normal pressure or reduced pressure, and water is distilled off. A polymerization aid may be added at this stage. Moreover, in order to accelerate | stimulate distillation of a water | moisture content, you may react by adding toluene etc.

  The amount of water in the polymerization system in the polymerization reaction is preferably 0.5 to 10.0 moles per mole of the charged sulfidizing agent. Here, the amount of water in the polymerization system is an amount obtained by subtracting the amount of water removed from the polymerization system from the amount of water charged in the polymerization system. In addition, the water to be charged may be in any form such as water, an aqueous solution, and crystal water.

[Polymerization reaction step]
It is preferable to produce a PPS resin granule by reacting a sulfidizing agent and a polyhalogenated aromatic compound in an organic polar solvent within a temperature range of 200 ° C. or higher and lower than 290 ° C.

  When starting the polymerization reaction step, the sulfidizing agent and the polyhalogenated aromatic compound are added to the organic polar solvent in an inert gas atmosphere at a temperature ranging from room temperature to 220 ° C, preferably 100 to 220 ° C. A polymerization aid may be added at this stage. The order in which these raw materials are charged may be out of order or may be simultaneous.

  The mixture is usually heated to a temperature in the range of 200 ° C to 290 ° C. Although there is no restriction | limiting in particular in a temperature increase rate, Usually, the speed of 0.01-5 degreeC / min is selected, and the range of 0.1-3 degreeC / min is more preferable.

  In general, the temperature is finally raised to a temperature of 250 to 290 ° C., and the reaction is usually carried out at that temperature for 0.25 to 50 hours, preferably 0.5 to 20 hours.

  In the stage before reaching the final temperature, for example, a method of reacting at 200 to 260 ° C. for a certain time and then raising the temperature to 270 to 290 ° C. is effective in obtaining a higher degree of polymerization. Under the present circumstances, as reaction time in 200 to 260 degreeC, the range of 0.25 to 20 hours is normally selected, Preferably the range of 0.25 to 10 hours is selected.

  In order to obtain a polymer having a higher degree of polymerization, it is effective to perform polymerization in a plurality of stages. When the polymerization is performed in a plurality of stages, it is effective that the conversion of the polyhalogenated aromatic compound in the system at 245 ° C. reaches 40 mol% or more, preferably 60 mol%.

[Recovery process]
After completion of the polymerization, a solid is recovered from the polymerization reaction product containing a polymer, a solvent and the like.

The most preferable method for recovering the PPS resin is to perform under a rapid cooling condition, and one preferable method for this recovery method is a flash method. In the flash method, the polymerization reaction product is flushed from a high-temperature and high-pressure state (usually 250 ° C. or higher, 8 kg / cm ² or higher) into an atmosphere of normal pressure or reduced pressure, and simultaneously with solvent recovery, the polymer is made into a granular form. This is a recovery method, and the term “flush” here means that a polymerization reaction product is ejected from a nozzle. Specific examples of the atmosphere to be flushed include nitrogen or water vapor at normal pressure, and the temperature is usually selected from the range of 150 ° C to 250 ° C.

  The flash method is a recovery method that is excellent in economic efficiency because it can recover the solids simultaneously with the recovery of the solvent and the recovery time can be relatively short. In this recovery method, an ionic compound typified by Na or an organic low-polymerization product (oligomer) tends to be easily taken into the polymer during the solidification process. Therefore, when recovering by a flash method, it is preferable to wash with water, and it is particularly preferable to wash with water just before the hot water treatment.

  However, the recovery method of the PPS resin used in the treatment method of the present invention is not limited to the flash method. If it is a method satisfying the requirements of the present invention, it is not easy to use a method (quenching method) of slow cooling to recover the particulate polymer. However, in view of economy and performance, it is more preferable to use the PPS resin recovered by the flash method in the treatment method of the present invention.

[Heat treatment process]
Next, the heat treatment of the PPS resin, which is an essential requirement of the present invention, will be described in detail.

  The method for treating a PPS resin of the present invention includes, for example, a PPS resin obtained through the polymerization reaction step and the recovery step, and an inert gas having an oxygen concentration of 2% by volume or less of 0.2 mL / It is essential to heat-treat while circulating for more than a minute, and it is preferable to include an acid treatment step before the heat-treating step. Furthermore, it is more preferable to include a step of hydrothermal treatment before the step of acid treatment. In addition, a step of washing with an organic solvent may be included before the step of acid treatment or the step of hydrothermal treatment, or a step of thermal oxidation treatment after the heat treatment may be included.

  The heating device for heat treatment of the present invention may be a normal hot air dryer or a heating device with a rotary or stirring blade, but for efficient and uniform treatment, a rotary or stirring blade is used. It is more preferable to use the heating device. The number of rotations is not particularly limited, but it is preferable that the PPS resin does not adhere and is not scattered. In the rotary apparatus, 1 to 100 rpm can be exemplified as a preferred range, and in the stirring type heating apparatus, 3 to 1000 rpm can be exemplified as a preferred range.

  The heat treatment in the present invention is essential to be performed while flowing an inert gas having an oxygen concentration of 2% by volume or less to 0.2 g / min or more with respect to 1 g of PPS resin, but the flow rate is 0.5 mL / min. It is preferable to circulate at least 1 minute, more preferably 1 mL / minute or more. A gas flow rate of less than 0.2 mL / min is not preferable because it is difficult to reduce volatile components, and a flow rate of more than 10 L / min is not preferable because loss due to scattering of PPS resin becomes significant. The flow rate of the inert gas shown here is based on the volume in the standard state.

  The oxygen concentration is essential to be 2% by volume or less, preferably 1.5% by volume or less, more preferably 1% by volume or less. When the oxygen concentration is larger than 2% by volume, it is difficult to suppress the oxidation reaction of the PPS resin, and the melt viscosity of the PPS resin increases before the volatile components are reduced, which is preferable because the fluidity is remarkably lowered. Absent.

  The inert gas in the present invention is not particularly limited as long as it does not have the ability to oxidize the PPS resin, but examples thereof include a gas mainly composed of nitrogen, carbon dioxide, water vapor, rare gas, and the like. A gas containing 90% by volume or more of these inert gases is preferable. Examples of the rare gas include helium, neon, argon, and krypton. Of these, nitrogen, carbon dioxide, water vapor, helium, and argon are preferable, and nitrogen, carbon dioxide, and water vapor are particularly preferable. In addition, in order to suppress the oxidation of the PPS resin, it is also possible to obtain the same effect as that in which the oxygen concentration is 2% by volume or less by reducing the pressure in the system and setting the oxygen partial pressure to 20 mmHg or less.

  Moreover, although the heat processing temperature of this invention is essential below 210 degreeC-melting | fusing point of PPS resin, 210-270 degreeC is preferable, More preferably, it is 220-260 degreeC. When heat treatment is performed at a temperature equal to or higher than the melting point of the PPS resin, the crosslinking reaction of the PPS resin due to thermal decomposition proceeds and the melt viscosity of the PPS resin rapidly increases, which is not preferable because the control becomes difficult and the fluidity is remarkably lowered. . On the other hand, when the temperature is less than 210 ° C., the reduction of volatile components is not sufficient, which is not preferable.

  Examples of the heat treatment time include 0.2 to 50 hours, more preferably 0.5 to 10 hours, and further preferably 1 to 5 hours. If the treatment time is less than 0.2 hours, it is difficult to sufficiently reduce volatile components, and if the treatment time exceeds 50 hours, the crosslinking reaction due to thermal decomposition proceeds and the fluidity decreases. It is not preferable.

  The PPS resin in the present invention must have a melt flow rate (measured at a temperature of 315.5 ° C. and a load of 5000 g according to ASTM D-1238-70) exceeding 500 g / 10 minutes before heat treatment. is there. When the melt flow rate is 500 g / 10 min or less, the melt flow rate of the PPS resin obtained after the heat treatment is also 500 g / 10 min or less, and the melt flowability of the PPS resin composition particularly when the filler is used with a high filling. Is undesirably deteriorated and the molding becomes unstable. The upper limit of the melt viscosity of the PPS resin is not particularly limited, but the use of a PPS resin that is 1 Pa · s (300 ° C., shear rate 1000 / sec) or more after heat treatment has strength to withstand practical use. It is preferable from the viewpoint of obtaining a resin (composition). In particular, in the heat treatment method of the present invention, the melt viscosity before and after the heat treatment does not change so much, so that there is an advantage that the PPS resin before the heat treatment can be easily designed in accordance with the melt viscosity of the target PPS resin.

[Post-treatment process and acid treatment]
The PPS resin in the present invention is preferable because the metal content is reduced by performing an acid treatment before the heat treatment, and volatile components are easily reduced during the heat treatment. Below, the method of an acid treatment process is explained in full detail.

  The acid used for the acid treatment is not particularly limited as long as it does not have an action of decomposing the PPS resin, and examples thereof include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propyl acid. Are more preferably used, but those which decompose and degrade PPS resins such as nitric acid are not preferred.

  The water when using the aqueous acid solution is preferably distilled water or deionized water. The acid aqueous solution preferably has a pH of 1 to 7, more preferably a pH of 2 to 4. A pH higher than 7 is not preferable because the metal content of the PPS resin increases, and a pH lower than 1 is not preferable because the volatile components of the PPS resin increase.

  As the acid treatment method, it is preferable to immerse the PPS resin in an acid or an aqueous solution of the acid in a nitrogen atmosphere, and it is possible to appropriately stir and heat as necessary. The temperature at the time of heating is preferably 80 to 250 ° C, more preferably 120 to 200 ° C, and further preferably 150 to 200 ° C. If it is less than 80 degreeC, the acid treatment effect is small, metal content increases, and if it exceeds 250 degreeC, since a pressure will become high too much, it is not preferable on safety. Moreover, it is preferable that pH at the time of processing by immersing a PPS resin in the aqueous solution of acid will be less than 8 by acid treatment, and pH 2-8 is more preferable. A pH higher than 8 is not preferable because the metal content of the obtained PPS resin increases.

  The time for the acid treatment is preferably a time at which the reaction between the PPS resin and the acid is sufficiently equilibrated, preferably 2 to 24 hours when treated at 80 ° C., and 0.01 to 5 hours when treated at 200 ° C. preferable.

  The ratio of the PPS resin to the acid or the aqueous solution of the acid in the acid treatment is preferably performed in a state where the PPS resin is sufficiently immersed in the acid or the aqueous solution of the acid. 0.5-500L of aqueous solution is preferable, 1-100L is more preferable, and 2.5-20L is further more preferable. If the acid or the aqueous solution of the acid is less than 0.5 L with respect to 500 g of the PPS resin, the PPS resin is not sufficiently immersed in the aqueous solution, resulting in poor cleaning and an increase in the metal content of the PPS resin. Moreover, when the acid or the aqueous solution of the acid exceeds 500 L with respect to 500 g of the PPS resin, the amount of the solution with respect to the PPS resin is excessively large and the production efficiency is remarkably lowered.

  These acid treatments are performed by a method in which a predetermined amount of PPS resin is added to a predetermined amount of water and acid, and the mixture is heated and stirred in a pressure vessel, or a method of continuously performing acid treatment. In particular, when a treatment involving heating is performed, it is preferably performed in an inert gas atmosphere such as nitrogen. As a method for separating the aqueous solution and the PPS resin from the treatment solution after the acid treatment, filtration using a sieve or a filter is simple, and methods such as natural filtration, pressure filtration, vacuum filtration, and centrifugal filtration can be exemplified. In order to remove the acid and impurities remaining on the surface of the PPS resin separated from the treatment liquid, it is preferable to wash several times with water or warm water. Examples of the cleaning method include a method of filtering while applying water to the PPS resin on the filtration device, and a method of separating the aqueous solution and the PPS resin by a method such as filtering again after putting the separated PPS resin into prepared water. it can. The water used for washing is preferably distilled water or deionized water.

[Post-treatment process and hot water treatment]
In the present invention, it is more preferable to perform the hydrothermal treatment before the acid treatment step, and the method is as follows. The water used for the hot water treatment in the present invention is preferably distilled water or deionized water, but an alkali metal hydroxide or the like may be added so that the pH after the hot water treatment becomes alkaline. In particular, if the pH during the hydrothermal treatment is 10 or more, it is preferable because the removal rate of impurities having carboxylic acid ends is increased and volatile components are easily reduced during the heat treatment. The hot water treatment temperature is preferably 80 to 250 ° C, more preferably 120 to 200 ° C, and further preferably 150 to 200 ° C. If it is less than 80 ° C., the hydrothermal treatment effect is small, and the amount of gas that volatilizes increases. If it exceeds 250 ° C., the pressure becomes too high, which is not preferable for safety. It is preferable to perform the hot water treatment before the acid treatment step because the metal content can be reduced by the hot water treatment and the volatile components are easily reduced during the heat treatment.

  The time for the hot water treatment is preferably a time sufficient for extraction treatment with PPS resin and hot water, preferably 2 to 24 hours when treated at 80 ° C., and 0.01 to 5 hours when treated at 200 ° C. Is preferred.

  The ratio of the PPS resin and water in the hot water treatment is preferably treated in a state in which the PPS resin is sufficiently immersed in water, preferably 0.5 to 500 L of water, and 1 to 100 L with respect to 500 g of PPS resin. Is more preferable, and 2.5 to 20 L is more preferable. When the amount of water is less than 0.5 L with respect to 500 g of the PPS resin, the PPS resin is not sufficiently immersed in water, resulting in poor cleaning and an increase in the amount of gas that volatilizes, which is not preferable. Further, if the amount of water exceeds 500 L with respect to 500 g of the PPS resin, the amount of water with respect to the PPS resin is excessively large, and the production efficiency is remarkably lowered.

  There are no particular restrictions on the operation of these hot water treatments, and a predetermined amount of PPS resin is charged into a predetermined amount of water and heated / stirred in a pressure vessel, or a continuous hot water treatment method is performed. However, it is preferable to carry out in an inert gas atmosphere such as nitrogen. There is no particular limitation on the method for separating the aqueous solution and the PPS resin from the treatment solution after the hot water treatment, but filtration using a sieve or a filter is simple, and methods such as natural filtration, pressure filtration, vacuum filtration, centrifugal filtration, etc. Can be illustrated. In order to remove impurities remaining on the surface of the PPS resin separated from the treatment liquid, it is preferable to wash several times with water or warm water. There is no particular limitation on the washing method, but the aqueous solution and the PPS resin can be filtered using a method in which water is applied to the PPS resin on the filtration device, or a method in which the separated PPS resin is poured into prepared water and then filtered again. The method of isolate | separating can be illustrated. The water used for washing is preferably distilled water or deionized water.

  Moreover, since the decomposition of the PPS end groups during these acid treatments and hot water treatments is not preferable, it is desirable that the acid treatments and hot water treatments be performed under an inert atmosphere. Examples of the inert atmosphere include nitrogen, helium, and argon, but a nitrogen atmosphere is preferable from the viewpoint of economy.

[Post-treatment process and organic solvent cleaning]
In the present invention, a step of washing with an organic solvent may be included before the step of acid treatment or the step of hydrothermal treatment, and the method is as follows. The organic solvent used for washing the PPS resin in the present invention is not particularly limited as long as it does not have an action of decomposing the PPS resin. For example, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1, 3 -Nitrogen-containing polar solvents such as dimethylimidazolidinone, hexamethylphosphoramide, piperazinones, sulfoxide-sulfon solvents such as dimethyl sulfoxide, dimethyl sulfone, sulfolane, ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, acetophenone, Ether solvents such as dimethyl ether, dipropyl ether, dioxane, tetrahydrofuran, chloroform, methylene chloride, trichloroethylene, ethylene dichloride, perchlorethylene, monochloroethane, dichloroethane, teto Halogen solvents such as chloroethane, perchlorethane, chlorobenzene, alcohol / phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, polypropylene glycol, and benzene, Examples thereof include aromatic hydrocarbon solvents such as toluene and xylene. Among these organic solvents, use of N-methyl-2-pyrrolidone, acetone, dimethylformamide, chloroform and the like is particularly preferable. These organic solvents are used alone or in combination of two or more.

  As a method of washing with an organic solvent, there is a method of immersing a PPS resin in an organic solvent, and if necessary, stirring or heating can be appropriately performed. There is no restriction | limiting in particular about the washing | cleaning temperature at the time of wash | cleaning PPS resin with an organic solvent, Arbitrary temperature of about normal temperature-about 300 degreeC can be selected. Although the cleaning efficiency tends to increase as the cleaning temperature increases, a sufficient effect is usually obtained at a cleaning temperature of room temperature to 150 ° C. It is also possible to wash under pressure in a pressure vessel at a temperature above the boiling point of the organic solvent. In particular, when a treatment involving heating is performed, it is preferably performed in an inert gas atmosphere such as nitrogen. There is no particular limitation on the cleaning time. Depending on the cleaning conditions, in the case of batch-type cleaning, a sufficient effect can be obtained usually by cleaning for 5 minutes or more. It is also possible to wash in a continuous manner.

  These acid treatment, hot water treatment or washing with an organic solvent can be carried out by appropriately combining them, but the order is preferably organic solvent washing, hot water treatment and acid treatment in this order. A sufficient effect can be obtained by acid treatment alone.

[Post-processing and thermal oxidation]
After performing the heat treatment in the present invention, it is possible to perform a thermal oxidation treatment to further increase the melt viscosity of the PPS resin. The method is described below.

  The heating device for the thermal oxidation treatment may be a normal hot air dryer or a heating device with a rotary or stirring blade. However, for efficient and uniform processing, a heating device with a rotary or stirring blade is used. More preferably, a heating device is used. The oxygen concentration in the atmosphere during the thermal oxidation treatment is preferably 2% by volume or more, and more preferably 8% by volume or more. Although there is no restriction | limiting in particular in the upper limit of oxygen concentration, About 50 volume% is a limit for safe operation, and 25 volume% or less is more preferable. The thermal oxidation treatment temperature is preferably 160 to 270 ° C, more preferably 160 to 220 ° C. If the thermal oxidation treatment is performed at a temperature higher than 270 ° C., the thermal oxidation treatment proceeds rapidly, which is not preferable because the control becomes difficult. On the other hand, when the temperature is lower than 160 ° C., the progress of the thermal oxidation treatment is remarkably slow, which is not preferable. Examples of the treatment time include 0.2 to 50 hours, more preferably 0.5 to 10 hours, and further preferably 1 to 5 hours. If the treatment time is less than 0.2 hours, it is not preferable because sufficient thermal oxidation treatment cannot be performed. If the treatment time exceeds 50 hours, the crosslinking reaction by the thermal oxidation treatment proceeds and the fluidity decreases, and at the same time, molding stability This is not preferable because the properties are lowered.

[Usage]
Thus, the PPS resin obtained by the treatment method of the present invention is excellent in heat resistance, chemical resistance, flame retardancy, electrical properties and mechanical properties, and can be applied to injection molded products, films, sheets, fibers and the like. Although possible, it is suitably applied particularly to injection molding applications.

  In order to obtain the effect of the present invention, it is preferable to use 100% of the PPS resin obtained by the treatment method of the present invention to form a molded product, but if necessary, blend with a PPS resin that does not satisfy the above conditions. It does not exclude things. The blend ratio can be appropriately selected as necessary, such as blending 75 to 25% (for example, 75%, 50%, 25%) of the PPS resin obtained by the treatment method of the present invention.

  In addition, other resins can be added to the PPS resin obtained by the treatment method of the present invention as long as the effects of the present invention are not impaired. For example, the flexibility and impact resistance can be further improved by adding a small amount of a highly flexible thermoplastic resin. However, if this amount exceeds 50% by weight of the total composition, the original characteristics of the PPS resin are impaired, and in particular, addition of 30% by weight or less is preferably used. Specific examples of thermoplastic resins include epoxy group-containing olefin copolymers, other olefin resins, polyamide resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyphenylene ether resins, polysulfone resins, polyallyl sulfone resins, polyketones. Resin, polyetherimide resin, polyarylate resin, liquid crystal polymer, polyethersulfone resin, polyetherketone resin, polythioetherketone resin, polyetheretherketone resin, polyimide resin, polyamideimide resin, tetrafluoropolyethylene resin, etc. Can be mentioned.

  Moreover, the following compounds can be added for the purpose of modification. Coupling agents such as isocyanate compounds, organosilane compounds, organotitanate compounds, organoborane compounds, epoxy compounds, polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, organophosphorus compounds, etc. , Talc, kaolin, organophosphorus compounds, crystal nucleating agents such as polyetheretherketone, montanic acid waxes, metal soaps such as lithium stearate and aluminum stearate, ethylenediamine / stearic acid / sebacic acid polycondensates, silicone compounds Other additives such as mold release agents such as hypophosphites, lubricants, UV inhibitors, colorants, foaming agents and the like can be blended. If any of the above compounds exceeds 20% by weight of the total composition, the original properties of the PPS resin are impaired, and therefore it is not preferred, and 10% by weight or less, more preferably 1% by weight or less is added.

  The PPS resin obtained by the treatment method of the present invention has at least one selected from an epoxy group, an amino group, an isocyanate group, a hydroxyl group, a mercapto group, and a ureido group for the purpose of improving mechanical strength, toughness and the like. You may add the alkoxysilane which has a seed | species functional group. Specific examples of such compounds include epoxy group-containing alkoxysilanes such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. Compounds, mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ- (2-ureidoethyl) ) Ureido group-containing alkoxysilane compounds such as aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, Isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, γ-isocyanatopropyltrichlorosilane, γ- (2- Amino group-containing alkoxysilane compounds such as aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-hydroxypropyltrimethoxysilane, γ- Examples thereof include a hydroxyl group-containing alkoxysilane compound such as hydroxypropyltriethoxysilane.

  A suitable addition amount of the silane compound is selected in a range of 0.05 to 5 parts by weight with respect to 100 parts by weight of the PPS resin.

  The PPS resin obtained by the treatment method of the present invention can be used by blending a filler as long as the effects of the present invention are not impaired. Specific examples of such fillers include glass fiber, carbon fiber, basalt fiber, potassium titanate whisker, zinc oxide whisker, calcium carbonate whisker, wollastonite whisker, aluminum borate whisker, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber. , Fibrous fillers such as asbestos fiber, stone fiber, metal fibers, or silicates such as talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, alumina silicate, oxidation Metal compounds such as silicon, magnesium oxide, alumina, zirconium oxide, titanium oxide and iron oxide, carbonates such as calcium carbonate, magnesium carbonate and dolomite, sulfates such as calcium sulfate and barium sulfate, calcium hydroxide Non-fibrous fillers such as hydroxides such as magnesium hydroxide and aluminum hydroxide, glass beads, glass flakes, glass powder, ceramic beads, carbon nanotubes, fullerene, boron nitride, silicon carbide, carbon black and silica, graphite These may be hollow, and two or more of these fillers may be used in combination. These fillers may be used after pretreatment with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, and an epoxy compound.

  The amount of the inorganic filler is usually preferably in the range of 0.0001 to 500 parts by weight and more preferably in the range of 0.001 to 400 parts by weight with respect to 100 parts by weight of the PPS resin. The content of the inorganic filler can be appropriately changed depending on the application from the balance of strength, rigidity, and other characteristics.

  The kneading machine is a method of kneading at a processing temperature of the melting peak temperature of the PPS resin +5 to 60 ° C. by supplying it to a generally known melt kneader such as a single-screw, twin-screw extruder, Banbury mixer, kneader, and mixing roll. Can be cited as a representative example. When using the auxiliary materials, the mixing order of the raw materials is not particularly limited, and a method in which all raw materials are blended and then melt-kneaded by the above method, a part of the raw materials are melt-kneaded by the above method, and the remaining ingredients are further mixed. Using any method, such as a method of blending raw materials and melt-kneading, or a method of mixing a part of raw materials and mixing the remaining raw materials using a side feeder during melt-kneading with a single-screw or twin-screw extruder Also good. As for the small amount additive component, other components can be kneaded by the above-mentioned method and pelletized, then added before molding and used for molding.

  The PPS resin (composition) of the present invention thus obtained is particularly suitable for injection molding applications, and specific applications include, for example, sensors, LED lamps, connectors, sockets, resistors, relay cases, switches. , Coil bobbins, capacitors, variable capacitor cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductor encapsulated parts, liquid crystals Electrical / electronic parts such as display parts, FDD carriage, FDD chassis, motor brush holder, parabolic antenna, computer-related parts; VTR parts, TV parts, irons, hair dryers, rice cooker parts, microwave oven parts, acoustics Parts, o Audio equipment parts such as DIO, laser discs, compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, household electrical appliance parts, office computer related parts, telephone related parts, Machine-related parts such as facsimile-related parts, copier-related parts, cleaning jigs, motor parts, lighters, typewriters, etc .: optical equipment such as microscopes, binoculars, cameras, watches, precision machine-related parts; Water faucet tops, mixing faucets, pump parts, pipe joints, water volume control valves, relief valves, hot water temperature sensors, water volume sensors, water meter housings and other water-related parts; valve alternator terminals, alternator connectors, IC regulators, light dials Poten for Various valves such as ohmmeter base, exhaust gas valve, various pipes related to fuel, exhaust system, intake system, air intake nozzle snorkel, intake manifold, fuel pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, cooling Water sensor, oil temperature sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake pad wear sensor, thermostat base for air conditioner, heating hot air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, Wiper motor related parts, distributor, starter switch, starter relay, transmission wire , Window washer nozzle, air conditioner panel switch board, coil for fuel-related electromagnetic valve, connector for fuse, horn terminal, electrical component insulation plate, step motor rotor, lamp socket, lamp reflector, lamp housing, brake piston, solenoid bobbin, engine Automotive and vehicle-related parts such as oil filters, ignition device cases, vehicle speed sensors, cable liners, engine control unit cases, engine driver unit cases, condenser cases, motor insulation materials, hybrid car control system parts cases, and other various applications It can be illustrated.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

  In the following examples, material characteristics were measured by the following method.

[Gas generation amount]
3 g of PPS resin was weighed into a glass ampoule having an abdomen of 100 mm × 25 mm, a neck of 255 mm × 12 mm, and a wall thickness of 1 mm, followed by vacuum sealing. Only the barrel of this glass ampoule was inserted into a ceramic electric tubular furnace ARF-30K manufactured by Asahi Rika Seisakusho and heated at 320 ° C. for 2 hours. After the ampoule was taken out, the neck of the ampoule that was not heated by the tubular furnace and was attached with volatile gas was cut out with a file and weighed. Next, the adhering gas was dissolved and removed with 5 g of chloroform, dried for 1 hour in a glass dryer at 60 ° C., and then weighed again. The difference in weight between the neck of the ampoule before and after removing the gas was defined as the amount of gas generated (% by weight).

[Melt flow rate (MFR)]
The measurement temperature was 315.5 ° C. and the load was 5000 g, and the measurement was performed according to ASTM-D1238-70. However, a low-viscosity product having an MFR exceeding 1000 g / 10 min is too high in fluidity, so that measurement with this measurement method is difficult. The PPS resin having a low melt viscosity (for example, Examples 3 to 9) was measured for melt viscosity by the following capillograph. The melt viscosity of the PPS resin measured with MFR = 500 g / 10 min was about 80 Pa · s (300 ° C., shear rate 1000 / sec). When there is no significant difference in the degree of cross-linking, etc., and there is no significant difference in the shear rate and temperature dependence of the melt viscosity, when the melt viscosity of the PPS resin is lower than 80 Pa · s, this indicates that the MFR exceeds 500 g / 10 min. Yes.

[Melt viscosity]
Using a Capillograph 1C manufactured by Toyo Seiki Co., Ltd., melt viscosity was measured at 300 ° C. using a die having a hole length of 10.00 mm and a hole diameter of 0.50 mm.

[Molding stability]
After dry blending 100 parts by weight of PPS resin and 67 parts by weight of glass fiber (ECS03TN-103 / P manufactured by Nippon Electric Glass Co., Ltd.), TEX30α type twin screw extruder manufactured by Nippon Steel Works (L / D = 45.5) The temperature was set so that the cylinder discharge resin temperature was 320 ° C. at a screw rotation speed of 300 rpm, melt kneaded, and pelletized with a strand cutter. The pellets dried at 120 ° C. overnight were subjected to a FANUC ROBOSHOT α-30i injection molding machine (manufactured by FANUC), injection speed 300 mm / second, injection pressure 40 MPa, cylinder set temperature 300 ° C., mold temperature 150 ° C., injection A rod-shaped product (width 12.7 mm, thickness 0.5 mm, side gate 0.5 mm × 5.0 mm) under the conditions of time 1 second, cooling time 20 seconds, screw rotation speed 100 rpm, back pressure 1 MPa, suck back 10 mm Continuous molding was performed, and the length of the molded product was measured as the rod flow length. After discarding the first 20 shots, the difference between the maximum and the minimum of the 100-shot rod flow length is obtained, and the difference between the maximum and the minimum of the 100-shot average rod flow length is 5% or less. "Excellent (A)", 5% to 10% of "Good (B)", and more than 10% were "Inferior (x)".

[Mold dirt]
After dry blending 100 parts by weight of PPS resin and 67 parts by weight of glass fiber (ECS03TN-103 / P manufactured by Nippon Electric Glass Co., Ltd.), a TEX30α type twin screw extruder (L / D = 45.5) manufactured by Nippon Steel Works The temperature was set so that the cylinder discharge resin temperature was 320 ° C. at a screw rotation speed of 300 rpm, melt kneaded, and pelletized with a strand cutter. Pellets dried overnight at 120 ° C. were continuously used 100 times with 80 mm × 80 mm × 2.0 mm thick test pieces at a resin temperature of 300 ° C. and a mold temperature of 150 ° C. using an injection molding machine UH1000 (manufactured by Nissei Plastic Industry Co., Ltd.). Molding was performed, and the discoloration state of the mold surface was visually confirmed to be “no discoloration (◯)”, “with discoloration (Δ)”, and “remarkably discoloration (×)”.

[Izod impact test]
After dry blending 100 parts by weight of PPS resin, 100 parts by weight of glass fiber (ECS03TN-103 / P manufactured by Nippon Electric Glass Co., Ltd.) and 133 parts by weight of calcium carbonate (KSS-1000 manufactured by Kinhei Mining Co., Ltd.), Nippon Steel Works Using a TEX30α type twin screw extruder (L / D = 45.5), the temperature was set so that the resin temperature at the cylinder was 320 ° C. at a screw rotation speed of 300 rpm, melt kneading, and pelletizing with a strand cutter. The pellets dried overnight at 120 ° C. were injection-molded with an Izod impact test piece at a resin temperature of 300 ° C. and a mold temperature of 150 ° C. using an injection molding machine UH1000 (manufactured by Nissei Plastic Industry Co., Ltd.). / 8, with notch) impact strength (based on ASTM D-256: measurement temperature 23 ° C.) was measured.

[Reference Example 1] Preparation of PPS-1 In an autoclave with a stirrer and a valve at the bottom, 8267.4 g (70.0 mol) of 47.5% sodium hydrosulfide and 2925.0 g (70. 2 mol), 13860.0 g (140.0 mol) of N-methyl-2-pyrrolidone (NMP), 1894.2 g (23.1 mol) of sodium acetate, and 10500.0 g of ion-exchanged water, and nitrogen at normal pressure The mixture was gradually heated to 240 ° C. over about 3 hours while distilling through water, and after distilling out 14772.1 g of water and 280.0 g of NMP, the reaction vessel was cooled to 160 ° C. The residual water content in the system per 1 mol of the charged alkali metal sulfide was 1.08 mol including the water consumed for the hydrolysis of NMP. The amount of hydrogen sulfide scattered was 0.023 mol per mol of the alkali metal sulfide charged.

  Next, 10466.7 g (72.4 mol) of p-dichlorobenzene (p-DCB) and 6444.9 g (65.1 mol) of NMP were added, the reaction vessel was sealed under nitrogen gas, and stirred at 240 rpm. The temperature was raised from 200 ° C. to 270 ° C. at a rate of 0.6 ° C./min and held at 270 ° C. for 70 minutes. The extraction valve at the bottom of the autoclave was opened, and the contents were flushed into a vessel equipped with a stirrer over 15 minutes while being pressurized with nitrogen, and stirred for a while at 250 ° C. to remove most of NMP.

  The obtained solid and 53 liters of ion-exchanged water were placed in an autoclave equipped with a stirrer, washed at 70 ° C. for 30 minutes, and then suction filtered through a glass filter having a pore size of 10 to 16 μm. Next, 60 liters of ion-exchanged water heated to 70 ° C. was poured into a glass filter having a pore size of 10 to 16 μm, and suction filtered to obtain a PPS-1 cake.

[Reference Example 2] Preparation of PPS-2 18000 g of PPS-1 cake and 40 liters of ion-exchanged water were charged into an autoclave equipped with a stirrer, and the inside of the autoclave was replaced with nitrogen. And subjected to hot water treatment. After cooling the autoclave, the contents were suction filtered with a glass filter having a pore size of 10 to 16 μm. The pH of the filtrate was 10. Next, 60 liters of ion exchange water heated to 70 ° C. was poured into a glass filter, and suction filtered to obtain a cake. The obtained cake, 40 liters of ion-exchanged water, and 700 g of acetic acid were charged into an autoclave equipped with a stirrer, and the inside of the autoclave was replaced with nitrogen. After cooling the autoclave, the contents were filtered through a glass filter having a pore size of 10 to 16 μm. The pH of the filtrate was 4. Next, 60 liters of ion exchange water heated to 70 ° C. was poured into a glass filter, and suction filtered to obtain a cake. The obtained cake was dried at 120 ° C. for 4 hours under a nitrogen stream to obtain PPS-2 powder. The MFR of the obtained PPS-2 was 695 g / 10 min.

[Reference Example 3] Preparation of PPS-3 PPS-3 powder was obtained in the same manner as Reference Example 2, except that 43 g of acetic acid was used instead of 700 g of acetic acid. The pH of the filtrate after the acid treatment was 7. The MFR of the obtained PPS-3 was 684 g / 10 min.

Reference Example 4 Preparation of PPS-4 A cake of PPS-4 was obtained in the same manner as Reference Example 1 except that sodium acetate was not added during the polymerization.

[Reference Example 5] Preparation of PPS-5 A PPS-5 powder was obtained in the same manner as in Reference Example 2 except that a PPS-4 cake was used instead of the PPS-1 cake. The MFR of the obtained PPS-5 was 1000 g / 10 min or more.

[Reference Example 6] Preparation of PPS-6 A powder of PPS-6 was obtained in the same manner as Reference Example 5 except that 43 g of acetic acid was used instead of 700 g of acetic acid. The pH of the filtrate after the acid treatment was 7. The obtained PPS-6 had an MFR of 1000 g / 10 min or more.

[Example 1]
1400 g of PPS-2 powder was put into a dryer equipped with a stirrer, 11.2 L / min of nitrogen (8 mL / g-PPS · min) was introduced into the dryer, and heat treatment was performed at 240 ° C. for 4 hours (rotation speed: 9 rpm). A PPS powder having a gas generation amount of 0.16% by weight and MFR of 619 g / 10 min was obtained.

[Comparative Examples 1 and 2]
After putting 1400 g of PPS-2 powder in a dryer equipped with a stirrer and replacing with nitrogen, heat treatment was performed at 240 ° C. for 4 hours and 8 hours.

[Comparative Example 3]
As in Example 1, the heat treatment temperature was changed to 200 ° C. A PPS powder having a gas generation amount of 0.31% by weight and MFR of 468 g / 10 min was obtained.

[Example 2]
2000 g of PPS-3 powder was put into a dryer equipped with a stirrer, and 1000 mL / min of nitrogen (0.5 mL / g-PPS · min) was introduced into the dryer, followed by heat treatment at 210 ° C. for 13 hours. A PPS powder having a gas generation amount of 0.17% by weight and MFR of 556 g / 10 min was obtained.

[Comparative Example 4]
PPS-3 powder 2000g was put into a dryer with a stirrer, air 524mL / min and nitrogen 476mL / min (total flow rate 0.5mL / g-PPS · min) were introduced into the dryer and heat treated at 210 ° C for 2 hours. Went. A PPS powder having a gas generation amount of 0.19% by weight and MFR of 474 g / 10 min was obtained.

  In Comparative Example 1, it can be seen that since the flow rate of nitrogen gas is insufficient, the volatile components are not sufficiently reduced, and good results cannot be obtained for mold contamination. Further, in Comparative Example 2, since the flow rate of nitrogen gas was insufficient, volatile components could not be reduced while maintaining good fluidity, resulting in poor molding stability.

  In Comparative Example 3, since the temperature was low, volatile components were not sufficiently reduced, and both molding stability and mold contamination were inferior.

  In Comparative Example 4, since oxidizing gas was used, good fluidity was maintained and volatile components could not be reduced, resulting in poor molding stability.

[Comparison with Izod impact test]
Further, with respect to Example 1, Comparative Example 1, and Comparative Example 4, an Izod impact test was also conducted. When the heat treatment was performed while flowing nitrogen (Example 1), the mechanical strength was as high as 58 J / m, but when the heat treatment was performed without flowing (Comparative Example 1), 18 J / m and 11% oxygen were used. In the case of heat treatment (Comparative Example 4), the mechanical strength was as low as 21 J / m, and it was found that heat treatment while circulating an inert gas was effective in improving toughness.

[Examples 3 to 7]
1800 g of PPS-5 powder was put in a dryer equipped with a stirrer, and 14.4 L / min of nitrogen (8 mL / g-PPS · min) was introduced into the dryer, and heat treatment was performed under the conditions shown in Table 2.

[Example 8]
1500 g of PPS-5 powder was put into a drier equipped with a stirrer, nitrogen 4.5 L / min (3 mL / g-PPS · min) was introduced into the drier, and heat treatment was performed at 240 ° C. for 3 hours. A PPS powder having a gas generation amount of 0.19% by weight and an MFR of 500 g / 10 min or more was obtained.

[Example 9]
2000 g of PPS-6 powder was placed in a dryer equipped with a stirrer, and 1000 mL / min of nitrogen (0.5 mL / g-PPS · min) was introduced into the dryer, followed by heat treatment at 210 ° C. for 4 hours. A PPS powder having a gas generation amount of 0.26 wt% and an MFR of 500 g / 10 min or more was obtained.

  It can be seen that by using the PPS powders obtained in Examples 3 to 9, it is possible to obtain a PPS resin excellent in molding stability and having little mold contamination.

  According to the present invention, it is possible to obtain a PPS resin that is excellent in melt fluidity and molding stability, hardly generates mold stains during molding, and can obtain a filler-reinforced resin composition excellent in toughness.

Claims (7)

An inert gas having an oxygen concentration of 2% by volume or less with respect to 1 g of polyphenylene sulfide resin having a melt flow rate (according to ASTM D-1238-70, measured at a temperature of 315.5 ° C. and a load of 5000 g) exceeding 500 g / 10 minutes. In a temperature range of 210 ° C. or higher and lower than the melting point of the polyphenylene sulfide resin, with a flow rate of 0.2 mL / min or more. 2. The method for treating a polyphenylene sulfide resin according to claim 1, wherein the inert gas contains at least one gas selected from nitrogen, carbon dioxide, water vapor and rare gas as a main component. The method for treating a polyphenylene sulfide resin according to claim 1 or 2, wherein the flow rate of the inert gas is 10 L / min or less with respect to 1 g of the polyphenylene sulfide resin. The method for treating a polyphenylene sulfide resin according to any one of claims 1 to 3, wherein the heat treatment is performed at a temperature of 210 ° C or higher and lower than 270 ° C. The method for treating a polyphenylene sulfide resin according to any one of claims 1 to 4, wherein the polyphenylene sulfide resin is a polyphenylene sulfide resin recovered by a flash method. A method for treating a polyphenylene sulfide resin, comprising subjecting the polyphenylene sulfide resin to an acid treatment and then performing the heat treatment according to any one of claims 1 to 5. A method for treating a polyphenylene sulfide resin, comprising subjecting the polyphenylene sulfide resin to hydrothermal treatment at 80 to 250 ° C, followed by acid treatment, and further performing the heat treatment according to any one of claims 1 to 5.