JP2014025166A - Method for manufacturing polyphenylene sulfide fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PPS fiber capable of being produced at a low cost and having excellent production stability without impairing excellent properties such as heat resistance, chemical resistance, flame retardancy and the like possessed by PPS.SOLUTION: The polyphenylene sulfide fiber is obtained by core-sheath composite spinning using a polyphenylene sulfide resin obtained by the flash method as a core component and a polyphenylene sulfide resin obtained by the quench method as a sheath component. A method for manufacturing the polyphenylene sulfide fiber includes core-sheath composite spinning using a polyphenylene sulfide resin obtained by the flash method as a core component and a polyphenylene sulfide resin obtained by the quench method as a sheath component.

Description

The present invention relates to a method for producing polyphenylene sulfide fibers used in nonwoven fabrics such as felt for bag filters, and can be produced at low cost, and has excellent strength, heat resistance, chemical resistance, and flame retardancy. The present invention relates to a fiber manufacturing method.

Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) has attracted attention as an electrical / electronic device member and an automotive device member by taking advantage of its excellent heat resistance, chemical resistance and flame retardancy. Further, it can be molded into various molded parts, films, sheets, fibers and the like by injection molding, extrusion molding, etc., and is widely used in fields requiring heat resistance, chemical resistance and flame retardancy. However, since the PPS resin has a high melting point, the melt processing temperature and the use temperature are high, so that volatile components are likely to be generated. In particular, in the flash method PPS, generation of volatile component gas is remarkable. For this reason, in the melt spinning process, there is a problem that a volatile component causes the spinneret to become dirty, resulting in an increase in the amount of work and a thread breakage.

  It is said that the cause of the contamination of the die is oligomers, and many proposals have been made to suppress the generation of oligomers. It has been practiced to remove oligomers or react with polymers by thermally oxidizing PPS resin. For example, the PPS resin has a non-Newtonian coefficient n of 1.5 to 2.1 in a range of polymer viscosity of 5000 to 16000 poise (500 to 1600 Pa · s) (310 ° C., shear rate of 200 / sec). An extrusion-molded product obtained by curing and melt-extruding this is disclosed (see Patent Document 1). In addition, a method for providing PPS fibers excellent in handleability and workability by subjecting PPS having a spinnable viscosity to a relatively light thermal oxidation treatment is disclosed (Patent Document 2).

  Moreover, generation | occurrence | production of an oligomer can be suppressed by lowering | hanging the processing temperature of PPS. As a method of lowering the processing temperature of PPS, a method of adding an oligomeric ester (Patent Document 3), a method of adding a monomeric carboxylic acid ester (Patent Document 4), and a method of adding another thioether (Patent Document 5). ), A method of adding a specific aromatic phosphate (Patent Document 6), a method of adding a polyalkylene glycol (Patent Document 7), a method of melt-kneading 0.1 to 8% by weight of a polyalkylene terephthalate resin (Patent Document 6) Reference 8) is shown.

  However, in any method, it is not sufficient to suppress the generation of oligomers, and it is difficult to improve the spinnability as long as single component melt spinning is performed using the resin obtained by the flash method. . Moreover, since many impurities were contained compared with PPS polymerized by the quench method, there was a problem that the tensile strength was lowered. On the other hand, the quench method PPS resin usually used in the production of PPS fibers has a longer process time than the flash method PPS, and further complicated processes such as washing and solvent recovery, resulting in an increase in cost.

Japanese Patent Laid-Open No. 63-207827 JP 2006-336140 A JP 62-45654 A JP-A-62-230848 JP-A-62-230849 JP-A-1-225660 JP-A-4-103661 JP 2010-144267 A

  An object of the present invention is to provide a PPS fiber which is low in cost and excellent in production stability without impairing excellent properties such as heat resistance, chemical resistance and flame retardancy of PPS.

  The above problem is solved by a method for producing polyphenylene sulfide fibers in which the core component is made of flash polyphenylene sulfide resin, the sheath component is made of quench polyphenylene sulfide resin, and core-sheath composite spinning is performed.

  It is possible to provide a method for producing PPS fibers excellent in heat stability, chemical resistance, flame retardancy, etc. at low cost and in production stability.

  Hereinafter, the present invention will be described in detail.

  The fiber used in the present invention is a fiber having a core-sheath structure, and a flash PPS resin is used for the core and a quench PPS resin is used for the sheath.

  The use of flash PPS resin in the core reduces costs, and the use of quench PPS resin in the sheath reduces volatile component gases and impurities that cause spinnability, resulting in production stability. Excellent PPS fiber can be produced.

  The core / sheath ratio is preferably core / sheath = 30/70 to 80/20 (weight ratio). More preferably, 30/70 to 70/30 (weight ratio) is preferable. This is because the cost merit expected when the core portion is less than 20% by weight cannot be obtained, and when it exceeds 80% by weight, the spinnability is deteriorated and the tensile strength is lowered. This is because volatile component gases and impurities increase as the proportion of the flash component PPS resin of the core component increases.

  The PPS resin used in the present invention is a polymer having a repeating unit represented by the following structural formula. From the viewpoint of heat resistance, the polymer containing the repeating unit represented by the following structural formula is 70 mol% or more, more preferably 90%. What contains more than mol% is preferable.

  From the viewpoint of heat resistance, a polymer containing 70 mol% or more, particularly 90 mol% or more of the repeating unit represented by the above structural formula is preferable. Moreover, PPS resin can comprise less than 30 mol% of the repeating units with repeating units having the following structural formula.

  It is considered that the low molecular weight compound contained in the PPS resin volatilizes at the time of spinning, thereby causing the base stain and thread breakage. These compounds can be extracted with chloroform.

  When the amount of chloroform extracted is 0.5 to 4% by weight, the PPS resin is preferable because the effect of suppressing the contamination of the die is large. When the amount of chloroform extraction exceeds 4% by weight, the generation of low molecular weight compounds cannot be suppressed, and the base becomes dirty, causing yarn breakage and the like.

  The manufacturing method of the PPS resin of this invention can be manufactured by the well-known method performed in order of a pre-process, a polymerization reaction process, and a collection process.

  The method for producing a PPS resin of the present invention includes a step of recovering a solid from a polymerization reaction product containing a polymer, a solvent and the like after the completion of the polymerization. In the PPS resin used in the present invention, any method can be used. The amount of chloroform extracted from the PPS resin varies depending on whether the recovery is performed.

In the flash method, the polymerization reaction product is flushed from a high temperature and high pressure (usually 250 ° C. or more, 8 kg / cm ² or more) into an atmosphere of normal pressure or reduced pressure, and the polymer is recovered in the form of powder simultaneously with the solvent recovery. Here, flush means that the polymerization reaction product is ejected from a nozzle. Specifically, for example, nitrogen or water vapor at normal pressure is raised as the atmosphere to be flushed, and the temperature is usually selected in 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, ionic compounds typified by Na and low molecular compounds tend to be left in the polymer during the solidification process, and the chloroform extraction amount is 0.5 to 6% by weight.

  On the other hand, the quench method is a method in which the polymerization reaction product is gradually cooled while being crystallized, and then the solid is recovered by filtration. In the case of this method, since it is gradually cooled, it takes longer than the flash method, and the productivity tends to be slightly lower. Moreover, the process of isolate | separating an organic solvent and solid content is needed separately. However, since it is probably excluded from the particles during the crystallization process, it is relatively easy to remove residual ionic compounds and organic low-polymerization products from the collected solids and to perform ion exchange. The amount is 0.5 to 4% by weight.

  For this reason, the flash method PPS resin can be used for the core portion to reduce costs, and the quench method PPS resin can be used for the sheath portion to reduce volatile component gases and impurities that cause deterioration of spinnability. It becomes possible. This is because the sheath part has a greater influence on the fiber properties than the core part.

  The flash method PPS resin and quench method PPS resin used in the present invention are preferably those that have been produced through a recovery step and then subjected to acid treatment, hot water treatment or washing with an organic solvent.

  The acid treatment is as follows. The acid used for the acid treatment of 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, and examples thereof include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonic acid, and propyl acid. Among them, acetic acid and hydrochloric acid are more preferably used, but those that decompose and deteriorate the PPS resin such as nitric acid are not preferable.

  As a method for acid treatment, there is a method of immersing a PPS resin in an acid or an aqueous solution of an acid, and stirring or heating can be appropriately performed as necessary. For example, when acetic acid is used, a sufficient effect can be obtained by immersing the PPS resin powder in an aqueous pH 4 solution heated to 80 to 200 ° C. and stirring for 30 minutes. The acid-treated PPS resin needs to be washed several times with water or warm water in order to physically remove the remaining acid or salt. The water used for washing is preferably distilled water or deionized water in the sense that the effect of chemical modification based on acid treatment is not impaired.

  When performing hot water treatment, it is as follows. That is, when the PPS resin used in the present invention is treated with hot water, the temperature of the hot water is preferably 100 ° C. or higher. The water used is preferably distilled water or deionized water in order to express the preferable chemical modification effect of the PPS resin by the hot water washing of the present invention. The operation of the hot water treatment is usually performed by putting a predetermined amount of PPS resin into a predetermined amount of water and stirring with heating in a pressure vessel. The ratio of the PPS resin to water is preferably high in water, but usually a bath ratio of 200 or less PPS resin is selected for 1 L of water.

  Further, since the decomposition of the terminal group is not preferable, the treatment atmosphere is preferably an inert atmosphere in order to avoid this. Further, the PPS resin after the hot water treatment operation is preferably washed several times with warm water in order to remove remaining components.

  When washing with an organic solvent, it is as follows. That is, 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-methylpyrrolidone, 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, dimethyl ether , Ether solvents such as dipropyl ether, dioxane, tetrahydrofuran, chloroform, methylene chloride, trichloroethylene, ethylene dichloride, perchlorethylene, monochloroethane, dichloroethane, Halogen solvents such as trachlorethane, perchlorethane, chlorobenzene, alcohol / phenol solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, polypropylene glycol and the like Aromatic hydrocarbon solvents such as benzene, toluene, xylene and the like can be mentioned. Among these organic solvents, use of N-methylpyrrolidone, acetone, dimethylformamide, chloroform and the like is particularly preferable. These organic solvents are used alone or in a mixture of two or more.

  As a cleaning method using an organic solvent, there is a method of immersing a PPS resin in an organic solvent, and it is possible to appropriately stir or heat as necessary.

  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. 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, heat treatment, or washing with an organic solvent can be combined with each other to have the desired amount of chloroform extracted.

  The PPS resin used in the present invention can also be used after increasing the molecular weight by heating in an oxygen atmosphere after completion of polymerization and a crosslinking treatment by overheating with addition of a crosslinking agent such as peroxide.

  When the dry heat treatment is performed for the purpose of increasing the molecular weight by thermal oxidation crosslinking, the temperature is preferably 160 to 260 ° C, and more preferably 170 to 250 ° C. The oxygen concentration is preferably 5% by volume or more, 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. The treatment time is preferably 1 to 100 hours, more preferably 2 to 50 hours, and even more preferably 3 to 25 hours. The heat treatment apparatus may be a normal hot air drier or a heating apparatus with a rotary type or a stirring blade. However, for efficient and more uniform treatment, a heating apparatus with a rotary type or a stirring blade may be used. More preferably it is used.

  In addition, it is possible to carry out a dry heat treatment for the purpose of suppressing thermal oxidative crosslinking and removing volatilization. The temperature is preferably 130 to 250 ° C, and more preferably 160 to 250 ° C. In this case, the oxygen concentration is preferably less than 5% by volume, and more preferably less than 2% by volume. The treatment time is preferably 0.5 to 50 hours, more preferably 1 to 20 hours, and still more preferably 1 to 10 hours. The heat treatment apparatus may be a normal hot air drier or a heating apparatus with a rotary type or a stirring blade. However, for efficient and more uniform treatment, a heating apparatus with a rotary type or a stirring blade may be used. More preferably it is used.

  The shape of the PPS resin used in the present invention is not particularly limited. When the shape of the obtained PPS resin is granular or powder, it may be used as it is. Moreover, after making into the shape of flakes and a pellet once, you may use.

Next, a method for obtaining PPS pellets with reduced high-boiling volatile components will be described. First, the solidified PPS powder is melted at a temperature of less than 350 ° C. under reduced pressure to be pelletized. More specifically, the solidified PPS powder is melted at a temperature of less than 350 ° C., usually in a temperature range of 285 to 340 ° C. while being vacuum-treated using an extruder, preferably a biaxial extruder. The area is 3.14 to 50.24 mm. Pellets are obtained by extruding from ^two holes and cutting to a length of about 0.5 to 6 mm. The vacuum treatment is performed by depressurizing the inside of the extruder cylinder to 0.2 to 1.5 kPa, preferably 0.2 to 1.3 kPa, more preferably about 0.2 to 0.65 kPa. The pellets thus obtained are dried under reduced pressure, so-called vacuum drying. In vacuum drying, the vacuum drying time for setting the atmospheric temperature to a relatively low temperature of 130 to 170 ° C. is preferably 4 hours or more, and the degree of decompression, the so-called vacuum degree is 0.01 to 1.3 kPa. It is good to do. In addition, vacuum drying of pellets is preferably a batch type, and if the amount of pellets to be dried is too large, volatile components cannot be sufficiently removed.

  If the pellets are vacuum dried at too high a temperature, the PPS resin undergoes oxidative cross-linking and other problems such as thickening will occur. By performing the treatment at a relatively low temperature for a long time, the high boiling point volatile components are removed and the PPS resin is modified. Can be prevented. The longer the drying time, the more effective, but when the time exceeds a certain time, the reduction range of volatile components having a high boiling point becomes smaller, so it can be determined by looking at the economic effect, and is practically within 24 hours. It is good to do.

  The present invention is characterized in that core-sheath composite spinning is performed using a flash PPS resin as a core component and a sheath PPS resin as a sheath component.

  By setting it as such a composition, the fiber excellent in heat resistance, chemical-resistance, and a flame retardance can be obtained, obtaining the cost merit by flash method PPS resin. This is because the sheath component has a greater influence on the fiber properties than the core component.

  The PPS fiber having a core-sheath structure in the present invention can be obtained by a conventional composite melt spinning method using the above-described resin.

  Next, the manufacturing method of the PPS fiber of this invention is demonstrated. First, PPS powder or PPS pellets are melted, the melted PPS is spun from the spinneret, and undrawn yarn is collected preferably at a take-up speed of 800 m / min or more, and then the undrawn yarn is more than 3 times, preferably Is hot-drawn at a draw ratio of 3 to 4 times.

  As the melt spinning machine, generally, a pressure / melter type spinning machine or a monoaxial or biaxial extruder type spinning machine is used. In the spinning process, in order to prevent gelation due to thickening, it is preferable to melt in a nitrogen atmosphere and discharge from the die. The yarn discharged from the die is usually cooled by cooling air after spinning at a wind speed of 5 to 100 m / min, imparted with an appropriate amount of oil as a converging agent, and taken up as undrawn yarn.

  If the take-up speed is less than 800 m / min, the orientation of the undrawn yarn is not advanced, and the structure of the undrawn yarn may become unstable. In addition, the spinning production capacity is too small, which increases the cost. When the take-up speed is set to 800 m / min or more, the orientation proceeds to some extent, so that it becomes easy to obtain the short fiber having the high tensile strength as described above.

  The hot stretching is usually performed in warm water having a temperature of 90 to 98 ° C., and a stretching ratio of 3 to 4 times is employed. Here, as the PPS pellets, if the above-mentioned one having a small amount of volatile gas components is used, stable spinning with little yarn breakage and yarn unevenness can be performed, and a uniform undrawn yarn can be obtained. It becomes possible to perform heat stretching at a magnification 6% or more higher than the natural stretching ratio.

  Next, the yarn relaxed after the constant length heat treatment is crimped and heat-set in a crimper such as a stuffing box type crimper filled with steam at a temperature of 180 ° C. or higher, preferably 200 ° C. or higher and 240 ° C. or lower. Subsequently, an oil agent is applied as necessary, and then cut into a predetermined length to obtain PPS short fibers. The properties of the obtained yarn are not particularly limited, but usually the single yarn fineness is 0.5 to 10.0 dtex, the strength is 2.0 cN / dtex or more, preferably 3.0 cN / dtex or more, more preferably 3.1 cN / Although it is not less than dtex and the upper limit of the strength is not particularly limited, a fiber having usually 10.0 cN / dtex or less, an elongation of 10 to 100%, and a dry heat shrinkage of 0 to 20.0% is obtained.

  The present invention will be specifically described below with reference to examples. In the following examples, material characteristics were measured by the following method.

(1) Chloroform extraction amount 10 g of PPS resin was weighed on a cylindrical filter paper, and Soxhlet extraction (bath temperature 120 ° C., 5 hours) was performed with 200 mL of chloroform. After extraction, chloroform was removed, and the residual amount was weighed and calculated per polymer weight.

(2) Spinnability The number of yarn breaks per spindle at a spinning time of 0 to 12 hours and 12 to 24 hours was counted. There are various causes for the number of thread breaks, but the number of thread breaks increased in 12 to 24 hours compared to 0 to 12 hours is due to thread breakage due to the contamination of the base. Spinnability was evaluated as ○ when the spinning time was 12 hours and the number of yarn breakage per spindle was less than 2 times, Δ when 2-3 times, and × when 4 times or more.

(3) Tensile strength The tensile strength of the fiber was measured according to the method of JIS L-1015 (2010 revision) -7.7.

<Example 1>
Using a flash PPS resin with a chloroform extraction amount of 3% by weight as the core component and a quench PPS resin with a chloroform extraction amount of 0.7% by weight as the sheath component, the core-sheath ratio is 50/50, and the melting temperature is Extrusion was performed at 330 ° C., single hole discharge rate = 0.5 g / min, and spinning was performed at 850 m / min. Thereafter, the total fineness was 1,000,00 dtex, the draw ratio was 3.4, the draw temperature was 100 ° C., and after drying, it was cut to 51 mm to obtain a core-sheath type composite fiber having a strength = 4.6 cN / dtex. The results of spinning and the physical properties of the yarn are shown in Table 1.

<Example 2>
Using a flash method PPS resin with a chloroform extraction amount of 3% by weight as the core component and a quench method PPS resin with a chloroform extraction amount of 0.7% by weight as the sheath component, the core-sheath ratio is 70/30, and the melting temperature is Extrusion was performed at 330 ° C., single hole discharge rate = 0.5 g / min, and spinning was performed at 850 m / min. Thereafter, the total fineness was 1,000,00 dtex, the draw ratio was 3.4, the draw temperature was 100 ° C., and after drying, cut to 51 mm to obtain a core-sheath type composite fiber having a strength of 4.3 cN / dtex. The results of spinning and the physical properties of the yarn are shown in Table 1.

<Example 3>
A flash method PPS resin having a chloroform extraction amount of 5% by weight as a core component, a quench method PPS resin having a chloroform extraction amount of 3% by weight as a sheath component, a core-sheath ratio of 50/50, and a melting temperature of 330 ° C. And extruding at a single hole discharge rate of 0.5 g / min and spinning at 850 m / min. Thereafter, the total fineness was 1,000,00 dtex, the draw ratio was 3.4, the draw temperature was 100 ° C., and after drying, cut to 51 mm to obtain a PPS fiber having a strength = 3.7 cN / dtex. The results of spinning and the physical properties of the yarn are shown in Table 1.

<Comparative Example 1>
Using a flash PPS resin with a chloroform extraction amount of 5% by weight, the melting temperature was 330 ° C., extrusion was performed at a single hole discharge rate of 0.5 g / min, and spinning was performed at 850 m / min. Thereafter, the total fineness was 1,000,00 dtex, the draw ratio was 3.4, the draw temperature was 100 ° C., and after drying, it was cut to 51 mm to obtain a PPS fiber having a strength = 3.5 cN / dtex. The results of spinning and the physical properties of the yarn are shown in Table 1. The number of yarn breaks 12 to 24 hours after the start of spinning was 4, and the spinnability was poor.

Claims (2)

A method for producing a polyphenylene sulfide fiber, characterized in that the core component comprises a flash polyphenylene sulfide resin, the sheath component comprises a quench polyphenylene sulfide resin, and core-sheath composite spinning. The method for producing polyphenylene sulfide fibers according to claim 1, wherein the amount of chloroform extracted from the polyphenylene sulfide resin of the sheath component is 0.5 to 4% by weight.