JP2012176607A - Rotational molding method of polyphenylene sulfide and rotationally molded article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotational molding method for obtaining a rotationally molded article at low temperatures and in a short time compared with a conventional rotational molding method, by solving the following problems: a long time and high temperature are required for polymerizing cyclic polyphenylene sulfide, in obtaining PPS resin of high molecular weight by polymerizing the cyclic polyphenylene sulfide in a rotational molding machine by heating, and a rotationally molded article obtained by the method.SOLUTION: In the rotational molding method, cyclic polyphenylene sulfide is heated and polymerized while being rotated in a mold in the presence of a transition metal compound. The transition metal compound is a 0 valent transition metal compound or a low valent iron compound, and is preferably heated in the presence of 0.001-20 mol% with respect to sulfur atoms in cyclic polyphenylene sulfide. The heating temperature is preferably from the melting point of cyclic polyphenylene sulfide to 400°C, and the heating time is preferably from 1 to 120 minutes.

Description

  The present invention relates to rotational molding of polyphenylene sulfide. More specifically, the present invention is characterized in that cyclic polyphenylene sulfide is heated and polymerized in the presence of a transition metal compound while rotating in a mold. It is an object of the present invention to provide a rotational molding method excellent in productivity and a rotational molded body obtained by the method, which can produce a rotational molded body at a low temperature for a short time.

  Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) has excellent heat resistance, barrier properties, chemical resistance, electrical insulation properties, moisture and heat resistance, flame resistance, non-elution of impurities, non-permeability, and dimensional stability. It is a resin having properties suitable as an engineering plastic. In addition, it can be molded into various molded parts, films, sheets, fibers, etc. by melt molding methods such as injection molding, extrusion molding, etc., and it has heat resistance and chemical resistance such as various electric / electronic parts, machine parts and automobile parts. Widely used in various required fields. In particular, a polyphenylene sulfide resin molded body formed by rotational molding using powder is attracting attention for its application to chemicals, fuel-related containers and the like utilizing the above-mentioned excellent characteristics.

  In the rotational molding method, powdered thermoplastic resin is charged into the mold cavity and heated in a furnace while rotating the mold uniaxially, biaxially or obliquely, and the mold inner wall is evenly distributed. After forming the resin melt layer, the molded body is manufactured by cooling the mold to solidify the resin layer, and opening the mold to take out the molded body. In particular, according to the present molding method, it is possible to mold even a large molded body that is difficult to produce by conventional melt molding processing methods such as blow molding, vacuum molding, and injection molding, and other molding methods cannot be molded. It is possible to produce a molded body having a possible complicated shape, and further, unlike a conventional molding method, it is possible to produce a molded body having no anisotropy, uneven thickness, and uneven thickness. In addition, when a metal container is used as the mold, it is possible to obtain a container in which a resin layer is lined on the inner surface of the mold container. The latter method using a metal container has a feature that a lining product having a stable film thickness can be obtained as a rotational lining technique as compared with a normal powder lining method.

  Patent Document 1 describes rotational molding using a PPS resin. However, even if a PPS resin obtained by the present technology is used, the workability by rotational molding is extremely poor, and the mechanical strength of the obtained molded body is further reduced. The impact resistance had a problem at a practical level.

  Patent Document 2 discloses a PPS resin-made container obtained by powder molding of a linear PPS resin, specifically, biaxial rotational molding. The present technology discloses that a rotational molded body is obtained by using a linear PPS powder having a specific particle size distribution and having a melt viscosity of 1500 to 10000 poise (150 to 1000 Pa · s). However, workability by rotational molding is still insufficient. In particular, since the melt viscosity is high, a problem that the mold cannot be filled with the molten polymer frequently occurs in the temperature range of 300 to 340 ° C., which is the molding temperature of PPS. Therefore, it was necessary to mold under high-speed rotation conditions in order to further increase the molding temperature to lower the melt viscosity or to form a uniform resin melt layer on the inner wall of the mold. In the rotational molding, the PPS resin itself is thermally decomposed to generate a large amount of gas, resulting in frequent voids in the resulting rotational molded body, poor surface smoothness, uneven thickness, and mechanical properties of the molded product. There was a problem that decreased.

Patent Document 3 also discloses a method of powder molding, that is, rotational molding, of a mixed powder of linear, branched, and thermally cross-linked PPS having a specific particle size distribution, and Patent Document 4 discloses a specific melt viscosity. Specifically, a rotational molding method using a linear PPS powder having a melt viscosity of 20 to 350 Pa · s at 310 ° C. under a high speed condition of a shear rate of 1200 sec ⁻¹ has been disclosed. It had the same problem as Patent Document 2.

  Furthermore, Patent Document 5 discloses a method in which PPS having a melt viscosity of 150 poise or higher (15 Pa · s or higher) that is not thermally crosslinked is heat-treated under reduced pressure in a solid state to increase the melt viscosity and then rotationally molded. Has been.

Patent Document 6 discloses a method in which PPS resin pellets having a melt viscosity of 50 to 1500 Pa · s measured at 310 ° C. and a shear rate of 1200 sec ⁻¹ are pulverized and rotationally molded using PPS particles having a specific particle size distribution. Has been. These inventions are mainly intended to improve the chemical resistance and toughness of containers obtained by rotational molding, and a rotational molding method using a high molecular weight PPS resin is disclosed. In order to improve the rotational processability of the high molecular weight PPS, it is a technology in which the rotational moldability is improved by controlling the particle size distribution of the PPS resin particles. When the molecular weight PPS resin is used, there is a problem that the polymer has a high melt viscosity, so that the processability by rotational molding itself is low and the productivity is poor.

  As described above, the methods described in Patent Documents 1 to 6 use PPS resin obtained by a conventional method, control the particle size distribution, improve fluidity and liquid transportability, and improve rotational moldability. However, in order to further improve the fluidity of the PPS resin itself, further improve the rotational molding processability, and improve the quality of the resulting rotational molded body, it is necessary to further reduce the viscosity. Met. Although a method of reducing melt viscosity using low molecular weight PPS is common, although this method tends to improve rotational moldability, the mechanical properties and chemical resistance inherent to PPS resin are accompanied by the reduction in molecular weight. There was a problem that it was reduced. That is, the improvement in rotational moldability according to the prior art and the improvement in the quality of rotational molded products made of PPS resin compositions are contradictory, and a drastic improvement method has been desired for many years with respect to rotational molding of PPS resins.

  Patent Document 7 is a polymer material that is completely different from the PPS resin of the present invention, but ω-lactam, which is a raw material of nylon 6, is injected into a mold together with an anionic polymerization initiator, and the anion is quickly formed in the mold. It is disclosed to polymerize to obtain a hollow molded article. However, this technique is effective only when producing a rotationally molded article made of nylon 6 obtained by anionic polymerization of ω-lactam. Since the polymerization method of the PPS resin is completely different from that of nylon 6, it is naturally impossible to manufacture a PPS resin rotational molded product by this technique. Further, the molded product of nylon 6 has an essential problem derived from the chemical structure of the material, which is inferior in heat resistance and chemical resistance as compared with PPS resin.

  Similarly, Patent Documents 8 and 9 report that a polyester having a high degree of polymerization can be obtained in a short time by heating a cyclic polyester oligomer in the presence of a catalyst. Although this patent document does not disclose a technique relating to rotational molding, it discloses a technique capable of rapidly polymerizing polyester. However, similar to Patent Document 7, this technique is an effective method only for the polymerization of polyester resin, and is completely different from the polymerization method for PPS resin, so that this technique is not applicable to the production of PPS resin rotational molded products. It was impossible.

  As a technique for solving these problems in the prior art and improving the rotational moldability of PPS resin, Patent Document 10 discloses polymerization of cyclic polyphenylene sulfide, which is a precursor of low-viscosity PPS resin, by heating in a rotary molding machine. And a method of obtaining a high molecular weight PPS resin is disclosed. This method improves rotational moldability, and can obtain a molded article having excellent surface smoothness, uniformity of thickness, and mechanical properties. However, in order to obtain a high molecular weight PPS resin from cyclic polyphenylene sulfide, There were problems such as taking a long time.

  As a method for solving the problem that it takes a high temperature and a long time to obtain the PPS resin, various catalyst components (ionic compounds and radical generation) that accelerate the polymerization when the cyclic polyphenylene sulfide is polymerized by heating. A method using a compound having a function is known.

  Patent Documents 11 and 12 disclose a method using, as an ionic compound, for example, a sulfur alkali metal salt such as a sodium salt of thiophenol, and a Lewis acid such as a metal halide such as copper (II) chloride as a catalyst. ing.

  Patent Document 13 discloses a compound capable of generating a sulfur radical by heating, for example, as a compound having radical generating ability, and specifically discloses a compound containing a disulfide bond.

  Although these patent documents do not disclose a method for producing a rotationally molded product, even if these methods are used, it takes a high temperature and a long time to sufficiently react cyclic polyphenylene sulfide to obtain PPS. Therefore, it has been difficult to apply these polymerization techniques to rotational molding.

  Thus, in a method of polymerizing a cyclic polyphenylene sulfide, which is a precursor of a PPS resin, by heating in a rotary molding machine to obtain a high molecular weight PPS resin, it is more suitable for practical use at a low temperature in a short time. There has been a demand for the creation of a rotational molding method in which polymerization in the machine proceeds and a high-quality PPS resin molded article with high rotational moldability can be obtained.

Japanese Patent Application Laid-Open No. 61-7332 (text description, page 5, lower right, lines 6 to 13) JP-A-4-267113 (Claims) JP-A-7-62240 (Claims) JP-A-8-258064 (Claims) JP-A-7-165933 (claim) JP 2002-88162 (Claims) JP-A-10-287743 (claim) Japanese Patent Laid-Open No. 2002-265576 (Claims) Japanese Patent Laid-Open No. 2002-308969 (Claims) JP 2008-200906 (Claims) Japanese Patent No. 3216228 (pages 7 to 10) Japanese Patent No. 3141459 (pages 5-6) US Pat. No. 5,869,599 (pages 27-28)

  The present invention solves the disadvantage that a high temperature and a long time are required for polymerization of cyclic polyphenylene sulfide in a method of polymerizing cyclic polyphenylene sulfide by heating in a rotary molding machine to obtain a high molecular weight PPS resin. An object of the present invention is to provide a rotational molding method capable of obtaining a rotational molded body at a low temperature in a short time with respect to the molding method, and a rotational molded body obtained by the method.

That is, the present invention is as follows.
(1) A rotational molding method characterized by heat polymerizing cyclic polyphenylene sulfide while rotating in a mold in the presence of a transition metal compound.
(2) The rotational molding method according to the above (1), wherein the transition metal compound is a zero-valent transition metal compound.
(3) The rotational molding method as described in (2) above, wherein the zero-valent transition metal compound is a compound containing a metal of Group 8 to Group 11 and Period 4 to 6 of the periodic table.
(4) The rotational molding method according to the above (1), wherein the transition metal compound is a low-valent iron compound.
(5) The rotational molding method according to (4), wherein the low-valent iron compound is a II-valent iron compound.
(6) The transition metal compound is heated and polymerized in the presence of 0.001 to 20 mol% with respect to the sulfur atom in the cyclic polyphenylene sulfide, as described in any one of (1) to (5) above Rotational molding method.
(7) The rotation according to any one of (1) to (6) above, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 400 ° C. Molding method.
(8) The rotation according to any one of (1) to (6) above, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 300 ° C. Molding method.
(9) The rotation according to any one of (1) to (6) above, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 270 ° C. Molding method.
(10) The rotation according to any one of (1) to (6) above, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 260 ° C. Molding method.
(11) The rotational molding method as described in any one of (1) to (10) above, wherein the heating time for heat polymerization while rotating in the mold is 1 minute or more and 120 minutes or less.
(12) The rotational molding method as described in any one of (1) to (10) above, wherein the heating time for heat polymerization while rotating in the mold is from 1 minute to 30 minutes.
(13) The rotational molding method according to any one of (1) to (12) above, wherein the repeating number (m) in the following formula contained in the cyclic polyphenylene sulfide is 4 to 50.

  The present invention is a rotational molding method characterized in that cyclic polyphenylene sulfide is heated and polymerized while rotating in a mold in the presence of a transition metal compound.

According to the present invention, it is possible to provide a PPS rotational molding method with excellent productivity and a rotational molded body obtained by the method, which can obtain a molded body at a low temperature and in a short time compared to the conventional method. it can.

It is the schematic of the small rotation molding apparatus used in the Example.

  Hereinafter, the present invention will be described in detail. First, the cyclic polyphenylene sulfide used in the present invention will be described.

<Cyclic polyphenylene sulfide>
The cyclic polyphenylene sulfide in the PPS rotational molding method of the present invention has a repeating unit represented by the following structural formula (A) as a main structural unit, preferably the following general formula (B) containing 80 mol% or more of the repeating unit. A compound containing at least 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more is preferable.

  In the cyclic compound of the formula (B) in the cyclic polyphenylene sulfide, it is also possible to constitute less than 20 mol% of the repeating unit with a repeating unit of the formula: — (Ar—S) —. The repeating unit or the like may be included at random, may be included as a block, or may be any mixture thereof. Ar includes units represented by the following formulas (C) to (M) and the like.

(R1 and R2 are substituents selected from hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an arylene group having 6 to 24 carbon atoms, and a halogen group, and R1 and R2 May be the same or different)

Although there is no restriction | limiting in particular in the repeating number m in the said (B) formula contained in cyclic polyphenylene sulfide, 4-50 are preferable, 4-25 are more preferable, and 4-15 can be illustrated as a still more preferable range. As will be described later, it is preferable that the rotational molding characterized in that the cyclic polyphenylene sulfide is heated and polymerized while rotating in a mold at a temperature not lower than the temperature at which the cyclic polyphenylene sulfide is melted. Since the melting temperature of polyphenylene sulfide tends to increase, it is advantageous to set m in the above range from the viewpoint that the thermal polymerization of cyclic polyphenylene sulfide can be performed at a lower temperature.
Further, the cyclic compound of the formula (B) contained in the cyclic polyphenylene sulfide may be either a single compound having a single repeating number or a mixture of cyclic compounds having different repeating numbers. A mixture of cyclic compounds having a tendency to have a lower melt solution temperature than a single compound having a single number of repetitions, and is characterized in that the rotational molding temperature (heat polymerization temperature in the present invention) can be lowered, and different repetitions. By using a cyclic compound having a number, the fluidity, flow uniformity, liquid feeding property, etc. during rotation molding are particularly excellent, that is, it is possible to form a uniform resin melt layer on the inner wall of the mold. This can be easily and uniformly filled with cyclic polyphenylene sulfide in the mold when the rotational polymerization temperature of the present invention is low, and even when the thermal polymerization temperature is low, The characteristic is that the polymerization of the cyclic polyphenylene sulfide proceeds rapidly.

  There are no particular limitations on the ratio of the different repeating numbers m in the mixture of cyclic compounds having different repeating numbers contained in the cyclic polyphenylene sulfide, but in order to exhibit the effects of the present invention, the (B) The content of the cyclic compound of m = 6 in the formula (B) relative to the total amount of the cyclic compound of the formula is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 30% by weight or less. 20% by weight or less is more preferable, and 10% by weight or less is still more preferable (in addition, the content of the cyclic compound of m = 6 is obtained from the following formula. Cyclic compound (weight) of m = 6 / ( Total amount of cyclic compound (weight) × 100) The cyclic compound (cyclohexa (p-phenylene sulfide)) of m = 6 has a high melting point of 348 ° C. and is considered to be easily crystallized. From the viewpoint of enabling the production of a rotational molded body at a lower temperature than the conventional rotational molding method, which is a clear objective, in the cyclic polyphenylene sulfide of the present invention, in particular, m = It is preferable that the content of the cyclic compound 6 is in the above-mentioned range.

  In addition, since cyclic compounds having m of 7 or less tend to have low reactivity, it is advantageous to use a cyclic compound having m of 8 or more as a main component from the viewpoint of easily obtaining polyphenylene sulfide in a short time. Become. However, in a mixture of cyclic compounds having different numbers of repetitions, when m of the cyclic compound contained in the cyclic polyphenylene sulfide increases and when the amount of the cyclic compound having a large m increases, the melting temperature of the cyclic polyphenylene sulfide is increased. And the rotational molding temperature (heat polymerization temperature in the present invention) tends to increase. Therefore, in order to solve the problem of the present invention that enables the production of a rotational molded body at a lower temperature than the conventional rotational molding method, it is advantageous to include a cyclic compound having m of 7 or less.

  As a preferred composition of the mixture of the cyclic compound of the formula (B) having a different number of repetitions in the cyclic polyphenylene sulfide, the total amount of the cyclic compound of the formula (B) contained in the cyclic polyphenylene sulfide is m. Is preferably 5% or more, more preferably 7% or more, and even more preferably 10% or more. Further, the cyclic compounds having m of 6 or 7 are each preferably contained in an amount of 5% or more, more preferably 7% or more based on the total amount of the cyclic compound of the formula (B). Cyclic polyphenylene sulfide containing a cyclic compound with m of 5 is preferable because the melting temperature tends to be low, and cyclic polyphenylene sulfide having the above composition containing cyclic compounds with m of 5 to 7 is more molten. It is more preferable because the solution temperature tends to be low.

  Here, the content of the cyclic compound having a different repeating number m with respect to the total amount of the cyclic compound of the formula (B) in the cyclic polyphenylene sulfide is determined by high performance liquid chromatography using a cyclic polyphenylene sulfide equipped with a UV detector. It can be determined as the ratio of the peak area attributed to a single cyclic compound having the desired m number to the total peak area attributed to the cyclic compound of formula (B) when the components are divided by chromatography. In addition, the qualitative characteristics of each peak divided into components by this high performance liquid chromatography can be obtained by separating each peak by preparative liquid chromatography and performing an absorption spectrum or mass analysis in infrared spectroscopic analysis.

  In the cyclic polyphenylene sulfide, the component other than the cyclic compound of the formula (B) is particularly preferably a polyarylene sulfide oligomer. Here, the polyarylene sulfide oligomer is a linear homo-oligomer or co-oligomer having a repeating unit of the formula, — (Ar—S) —, as a main constituent unit, preferably containing 80 mol% or more of the repeating unit. . Ar includes units represented by the above formulas (C) to (M) and the like, and among these, the formula (C) is particularly preferable. The polyarylene sulfide oligomer can contain a small amount of branching units or crosslinking units represented by the following formulas (N) to (P) as long as these repeating units are the main constituent units. The amount of copolymerization of these branched units or cross-linked units is preferably in the range of 0 to 1 mol% with respect to 1 mol of-(Ar-S)-units. Further, the polyarylene sulfide oligomer may be any of a random copolymer, a block copolymer and a mixture thereof containing the above repeating unit.

  Typical examples thereof include polyphenylene sulfide oligomers, polyphenylene sulfide sulfone oligomers, polyphenylene sulfide ketone oligomers, random copolymers, block copolymers, and mixtures thereof. Particularly preferred polyarylene sulfide oligomers include polyphenylene sulfide oligomers containing 80 mol% or more, particularly 90 mol% or more of p-phenylene sulfide units as the main structural unit of the polymer.

  Examples of the molecular weight of the polyarylene sulfide oligomer include those having a molecular weight lower than that of polyphenylene sulfide obtained by rotational molding. Specifically, the weight average molecular weight is preferably less than 10,000.

  The amount of the polyarylene sulfide oligomer contained in the cyclic polyphenylene sulfide is particularly preferably smaller than that of the cyclic compound of the formula (B) contained in the cyclic polyphenylene sulfide. That is, the weight ratio of the cyclic compound (B) to the polyarylene sulfide oligomer in the cyclic polyphenylene sulfide (cyclic compound of the formula (B) / polyarylene sulfide oligomer) is preferably more than 1. 2.3 The above is more preferable, 4 or more is further preferable, and 9 or more is even more preferable. By using such a cyclic polyphenylene sulfide, it is possible to easily obtain a polyphenylene sulfide having a weight average molecular weight of 10,000 or more. Therefore, the weight average molecular weight of the PPS resin obtained by the rotational molding method of the present invention tends to increase as the weight ratio of the cyclic compound of the formula (B) to the polyarylene sulfide oligomer in the cyclic polyphenylene sulfide increases. Therefore, there is no particular upper limit to this weight ratio, but in order to obtain a cyclic polyphenylene sulfide having a weight ratio exceeding 100, it is necessary to significantly reduce the polyarylene sulfide oligomer content in the cyclic polyphenylene sulfide. This takes a lot of effort. According to the rotational molding method of the present invention, it is possible to easily obtain a PPS resin having a weight average molecular weight of 10,000 or more even when a cyclic polyphenylene sulfide having a weight ratio of 100 or less is used.

  The upper limit value of the molecular weight of the cyclic polyphenylene sulfide used in the rotational molding method of the present invention is preferably 10,000 or less, preferably 5,000 or less, more preferably 3,000 or less in terms of weight average molecular weight, while the lower limit value is The weight average molecular weight is preferably 300 or more, preferably 400 or more, and more preferably 500 or more.

The cyclic polyphenylene sulfide used in the rotational molding of the present invention preferably has a melt viscosity of 0.1 Pa · s or less, preferably 0.05 Pa · s or less, more preferably, measured at 300 ° C. and a shear rate of 2 sec ⁻¹ . 0.03 Pa · s or less. If the melt viscosity is greater than 0.1 Pa · s, the fluidity when obtaining a large-sized rotary molded product is lowered, thereby reducing the liquid transportability, and filling into the mold becomes insufficient, It causes bubbles, cracks and uneven thickness.

<Transition metal compounds>
In the present invention, rotational molding of cyclic polyphenylene sulfide is performed in the presence of various transition metal compounds. As the transition metal compound, a zero-valent transition metal compound or a low-valent iron compound is preferably used. Although the principle of promoting polymerization by transition metal compounds is not clear at this time, transition metal compounds that can take various electronic states and have higher electron density are coordinated or bonded to the carbon-sulfur bond sites of cyclic polyphenylene sulfide. The zero-valent transition metal compound or the low-valent iron compound having such characteristics is preferable as the polymerization catalyst.

  As a conventional technique, when cyclic polyphenylene sulfide is polymerized by heating, for example, an alkali metal salt of sulfur such as a sodium salt of thiophenol, or a chloride that is an electrophilic compound that generates a cation. Although methods using copper (II) or disulfide bond-containing compounds that generate radicals when heated as a catalyst component are also disclosed, cyclic polyphenylene sulfide can be sufficiently reacted even if these methods are used. In order to obtain PPS, high temperature and a long time were required, and the rotational moldability was insufficient. Furthermore, since it takes a high temperature and a long time to obtain PPS by these conventional techniques, it tends to contain unreacted cyclic polyphenylene sulfide, and the molecular weight of the obtained PPS tends to be low. There was a tendency that mechanical properties, chemical resistance, and the like were difficult to obtain, and the quality of the rotational molded product was insufficient.

  On the other hand, if a transition metal compound in the present invention, in particular, a zero-valent transition metal compound or a low-valent iron compound having a high electron density is used, the polymerization can proceed in a mold molding machine at a low temperature in a short time. It is possible to obtain a rotationally-molded article with high rotational moldability and good quality having, for example, mechanical characteristics and chemical resistance, which are the original characteristics of PPS.

<Zerovalent transition metal compound>
In the present invention, various zero-valent transition metal compounds are used as a polymerization catalyst for promoting the polymerization of cyclic polyphenylene sulfide in a rotary molding machine. As the zero-valent transition metal, metals of Groups 8 to 11 and Periods 4 to 6 of the periodic table are preferably used. For example, nickel, palladium, platinum, iron, ruthenium, rhodium, copper, silver, and gold can be exemplified as the metal species. Various complexes are suitable as the zero-valent transition metal compound. For example, triphenylphosphine, tri-t-butylphosphine, tricyclohexylphosphine, 1,2-bis (diphenylphosphino) ethane, 1 , 1'-bis (diphenylphosphino) ferrocene, dibenzylideneacetone, dimethoxydibenzylideneacetone, cyclooctadiene, and carbonyl complexes. Specifically, bis (dibenzylideneacetone) palladium, tris (dibenzylideneacetone) dipalladium, tetrakis (triphenylphosphine) palladium, bis (tri-t-butylphosphine) palladium, bis [1,2-bis (diphenylphosphine) Fino) ethane] palladium, bis (tricyclohexylphosphine) palladium, [P, P′-1,3-bis (di-i-propylphosphino) propane] [P-1,3-bis (di-i-propyl) Phosphino) propane] palladium, 1,3-bis (2,6-di-i-propylphenyl) imidazol-2-ylidene (1,4-naphthoquinone) palladium dimer, 1,3-bis (2,4 , 6-Trimethylphenyl) imidazol-2-ylidene (1,4-naphthoquinone) palladium dimer, bi (3,5,3 ′, 5′-dimethoxydibenzylideneacetone) palladium, bis (tri-t-butylphosphine) platinum, tetrakis (triphenylphosphine) platinum, tetrakis (trifluorophosphine) platinum, ethylenebis (triphenyl) Phosphine) platinum, platinum-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane complex, tetrakis (triphenylphosphine) nickel, tetrakis (triphenylphosphite) nickel, bis (1,5-cyclooctadiene) nickel, dodecacarbonyl triiron, pentacarbonyl iron, dodecacarbonyl tetrarhodium, hexadecacarbonyl hexarhodium, dodecacarbonyl triruthenium and the like can be exemplified. These polymerization catalysts may be used alone or in combination of two or more.

  These polymerization catalysts may be added with a zero-valent transition metal compound as described above, or may form a zero-valent transition metal compound in the system. Here, in order to form a zero-valent transition metal compound in the system as in the latter case, a transition metal compound such as a transition metal salt and a compound serving as a ligand are added to form a transition metal complex in the system. And a method of adding a complex formed of a transition metal compound such as a transition metal salt and a compound serving as a ligand. Examples of transition metal compounds and ligands used in the present invention and complexes formed of transition metal compounds and ligands are given below. Examples of the transition metal compound for forming a zero-valent transition metal compound in the system include acetates and halides of various transition metals. Examples of the transition metal species include nickel, palladium, platinum, iron, ruthenium, rhodium, copper, silver, gold acetate, halide and the like, specifically nickel acetate, nickel chloride, nickel bromide. , Nickel iodide, nickel sulfide, palladium acetate, palladium chloride, palladium bromide, palladium iodide, palladium sulfide, platinum chloride, platinum bromide, iron acetate, iron chloride, iron bromide, iron iodide, ruthenium acetate, chloride Examples include ruthenium, ruthenium bromide, rhodium acetate, rhodium chloride, rhodium bromide, copper acetate, copper chloride, copper bromide, silver acetate, silver chloride, silver bromide, gold acetate, gold chloride, and gold bromide. Moreover, as a ligand added simultaneously in order to form a zerovalent transition metal compound in the system, if a cyclic polyphenylene sulfide and a transition metal compound are heated, a zerovalent transition metal is generated. Although not particularly limited, basic compounds are preferable, and examples thereof include triphenylphosphine, tri-t-butylphosphine, tricyclohexylphosphine, 1,2-bis (diphenylphosphino) ethane, 1,1′-bis (diphenylphosphino). ) Ferrocene, dibenzylideneacetone, sodium carbonate, ethylenediamine and the like. Moreover, as a complex formed with the compound used as a transition metal compound and a ligand, the complex which consists of the above various transition metal salts and a ligand is mentioned. Specifically, bis (triphenylphosphine) palladium diacetate, bis (triphenylphosphine) palladium dichloride, [1,2-bis (diphenylphosphino) ethane] palladium dichloride, [1,1′-bis (diphenylphosphine) Fino) ferrocene] palladium dichloride, dichloro (1,5′-cyclooctadiene) palladium, bis (ethylenediamine) palladium dichloride, bis (triphenylphosphine) nickel dichloride, [1,2-bis (diphenylphosphino) ethane] nickel Examples include dichloride, [1,1′-bis (diphenylphosphino) ferrocene] nickel dichloride, dichloro (1,5′-cyclooctadiene) platinum and the like. These polymerization catalysts and ligands may be used alone or in combination of two or more.

  The concentration of the polymerization catalyst used varies depending on the molecular weight of the target PPS resin and the type of the polymerization catalyst, but is usually 0.001 to 20 mol%, preferably 0.005, based on the sulfur atom in the cyclic polyphenylene sulfide. ˜15 mol%, more preferably 0.01 to 10 mol%. If it is 0.001 mol% or more, the cyclic polyphenylene sulfide sufficiently reacts to obtain a PPS resin, and if it is 20 mol% or less, it has excellent properties in terms of thickness unevenness and mechanical properties of the finally obtained rotational molded product. A PPS resin can be obtained.

  The valence state of the transition metal compound can be grasped by X-ray absorption fine structure (XAFS) analysis. Transition metal compound used as a catalyst in the present invention or a cyclic polyphenylene sulfide containing a transition metal compound or a PPS resin containing a transition metal compound is irradiated with X-rays, and the peak value of the absorption coefficient when the absorption spectrum is normalized Can be grasped by comparing.

  For example, when evaluating the valence of a palladium compound, it is effective to compare the absorption spectrum of the L3 end X-ray absorption near edge structure (XANES), and the X-ray energy is 3173 eV as a reference, 3163 to 3168 eV. This can be determined by comparing the peak maximum value of the absorption coefficient when the average absorption coefficient in the range of 0 and 3191 to 3200 eV is normalized to 1. In the example of palladium, the peak value of the absorption coefficient when normalized with a zero-valent palladium compound tends to be smaller than the divalent palladium compound, and further, the effect of promoting the polymerization of cyclic polyphenylene sulfide The transition metal compound having a larger value tends to have a smaller peak maximum value. The reason for this is presumed that the absorption spectrum for XANES corresponds to the transition of core electrons to empty orbitals, and the absorption peak intensity is affected by the electron density of d orbitals.

  In order for the palladium compound to promote the polymerization of cyclic polyphenylene sulfide, the peak maximum value of the absorption coefficient when normalized is preferably 6 or less, more preferably 4 or less, still more preferably 3 or less, Within this range, polymerization of cyclic polyphenylene sulfide can be promoted.

  Specifically, the peak maximum is 6.32 for divalent palladium chloride that does not promote polymerization of cyclic polyphenylene sulfide, zero-valent tris (dibenzylideneacetone) dipalladium that promotes polymerization of cyclic polyphenylene sulfide, and Tetrakis (triphenylphosphine) palladium and bis [1,2-bis (diphenylphosphino) ethane] palladium are 3.43, 2.99 and 2.07, respectively.

<Low-valent iron compound>
In the present invention, various low-valent iron compounds are used as a polymerization catalyst for promoting the polymerization of cyclic polyphenylene sulfide in a rotary molding machine. It is known that an iron atom can theoretically take a valence state of -II, -I, 0, I, II, III, IV, V, and VI. The iron compound having a valence of -II to II. The low-valent iron compound described here means that the valence of the iron compound in the reaction system is -II to II when polymerizing cyclic polyphenylene sulfide by heating in a rotary molding machine. .

  The iron compound used as a polymerization catalyst in the present invention is a low-valent iron compound and is an electron-donating polymerization catalyst, and thus, for example, conventionally known, used when polymerizing cyclic polyphenylene sulfide by heating, It is considered to be different from compounds that generate cations and compounds that act electrophilically.

  Examples of the low-valent iron compound include iron compounds having a valence of −II to II. From the viewpoint of stability of the iron compound, ease of handling, availability, and the like, As the iron compound, zero-valent, I-valent, and II-valent iron compounds are preferably used, and among them, the II-valent iron compound is particularly preferable.

  As the divalent iron compound, various iron compounds are suitable, and examples thereof include divalent iron halides, acetates, sulfates, phosphates, ferrocene compounds, and the like. Specific examples include iron chloride, iron bromide, iron iodide, iron fluoride, iron acetate, iron sulfate, iron phosphate, iron nitrate, iron sulfide, iron methoxide, phthalocyanine iron, ferrocene, and the like. Among these, from the viewpoint of uniformly dispersing the iron compound in the cyclic polyphenylene sulfide, an iron halide having good dispersibility in the cyclic polyphenylene sulfide is preferable. From the viewpoint of economy and the characteristics of the obtained polyphenylene sulfide. Therefore, iron chloride is more preferable. Examples of the characteristics of the polyphenylene sulfide described here include solubility in 1-chloronaphthalene. When the preferred low-valent iron compound of the present invention is used, there is a tendency to obtain a polyphenylene sulfide having a small insoluble part in 1-chloronaphthalene, preferably having no insoluble part. This is a desirable characteristic from the viewpoint of obtaining characteristics such as high mechanical strength of the rotational molded product.

  Various iron compounds are suitable as the I-valent iron compound, and specific examples include cyclopentadienyl iron dicarbonyl dimer, 1,10-phenanthroline iron sulfate complex, and the like.

  Various iron compounds are suitable as the zero-valent iron compound, and specific examples include dodecacarbonyl triiron and pentacarbonyl iron.

  These polymerization catalysts may be used alone or in combination of two or more.

  These polymerization catalysts may be added with a low-valent iron compound as described above, or a low-valent iron compound may be formed in the system from a high-valent iron compound having a valence of III or higher. Here, in order to form a low-valent iron compound in the system as in the latter, a method of forming a low-valent iron compound from a high-valent iron compound by heating, a high-valent iron compound to cyclic polyphenylene sulfide, Examples thereof include a method of forming a low-valent iron compound in the system by adding a compound having reducibility to a high-valent iron compound as a promoter. Examples of the method for forming a low-valent iron compound from a high-valent iron compound by heating include a method for forming a low-valent iron compound by heating a high-valent iron halide compound. Here, when heating the high-valent iron halide compound, it is presumed that a low-valent iron compound is formed by elimination of a part of the halogen constituting the high-valent iron halide compound.

  The lower limit of the heating temperature for forming the low-valent iron compound from the high-valent iron compound by heating differs depending on the type of polymerization catalyst, the pressure in the heating system, the heating time, etc., and therefore cannot be uniquely indicated. However, it is possible to estimate the heating temperature at which a low-valent iron compound can be formed from the tendency of weight reduction obtained from thermogravimetric analysis of polymerization catalysts or the tendency of change in calorie obtained from analysis with a differential scanning calorimeter, for example. It is.

  Also, the upper limit of the heating temperature also varies depending on the type of polymerization catalyst, the pressure in the heating system, the heating time, etc., and therefore cannot be uniquely indicated, but may be below the temperature at which the polymerization catalyst volatilizes during heating. preferable.

  The low-valent iron compound may be formed in advance from the high-valent iron compound by heating and then raised to the rotational molding temperature, or may be formed from the high-valent iron compound at the time of rotational molding by heating to the rotational molding temperature. You may let them.

  Examples of the high-valent iron compound and promoter used in the present invention are given below. Various iron compounds are suitable as the high-valent iron compound for forming the low-valent iron compound in the system. For example, iron chloride, iron bromide, iron fluoride, citrate as the III-valent iron compound. Examples thereof include iron oxide, iron nitrate, iron sulfate, iron acetylacetonate, iron benzoylacetonate diethyldithiocarbamate, iron ethoxide, iron isopropoxide, and iron acrylate. Among these, from the viewpoint of uniformly dispersing the iron compound in the cyclic polyphenylene sulfide, an iron halide having good dispersibility in the cyclic polyphenylene sulfide is preferable. From the viewpoint of economy and the characteristics of the obtained polyphenylene sulfide. Therefore, iron chloride is more preferable. Examples of the characteristics of the polyphenylene sulfide described here include solubility in 1-chloronaphthalene. When the preferred low-valent iron compound of the present invention is used, there is a tendency to obtain a polyphenylene sulfide having a small insoluble part in 1-chloronaphthalene, preferably having no insoluble part. This is a desirable characteristic as polyphenylene sulfide from the viewpoint of obtaining characteristics such as high mechanical strength of a rotationally molded product.

  The co-catalyst added simultaneously to form the low-valent iron compound in the system is a low-valent iron compound that reacts with the high-valent iron compound when the cyclic polyphenylene sulfide and the high-valent iron compound are heated. Although it will not specifically limit if it produces | generates, The compound which has various organic and inorganic reducibility is preferable, for example, copper (I) chloride, tin (II) chloride, titanium (III) chloride, ethylenediamine, N, N Examples include '-dimethylethylenediamine, triphenylphosphine, tri-t-butylphosphine, tricyclohexylphosphine, 1,2-bis (diphenylphosphino) ethane, and the like. Among these, copper (I) chloride, tin (II) chloride, and titanium (III) chloride are preferable, and copper (I) and tin (II) chloride that can be safely handled in a solid state are more preferable.

  These polymerization catalysts and cocatalysts may be used alone or in combination of two or more.

  The concentration of the polymerization catalyst used varies depending on the molecular weight of the target PPS resin and the type of the polymerization catalyst, but is usually 0.001 to 20 mol%, preferably 0.005, based on the sulfur atom in the cyclic polyphenylene sulfide. ˜15 mol%, more preferably 0.01 to 10 mol%. If it is 0.001 mol% or more, the cyclic polyphenylene sulfide sufficiently reacts to obtain a PPS resin, and if it is 20 mol% or less, it has excellent properties in terms of thickness unevenness and mechanical properties of the finally obtained rotational molded product. A PPS resin can be obtained.

  The valence state of the iron compound in the reaction system and the structure near the iron atom can be grasped by X-ray absorption fine structure (XAFS) analysis. The iron compound used as a catalyst in the present invention, the cyclic polyphenylene sulfide containing the iron compound, or the polyphenylene sulfide containing the iron compound is irradiated with X-rays, and the shape of the absorption spectrum is compared to compare the value of the iron compound. The number state and the structure near the iron atom can be grasped.

  When evaluating the valence of iron compounds, it is effective to compare the absorption spectra for the X-ray absorption near edge structure (XANES) at the K end, and it is possible to make a judgment by comparing the energy at which the spectrum rises and the spectrum shape. is there. The spectrum obtained by measuring the II-valent iron compound compared to the spectrum obtained by measuring the III-valent iron compound, and further the spectrum obtained by measuring the zero-valent iron compound, the rising of the main peak is on the lower energy side. Tend to be. Specifically, in the case of iron (III) chloride, which is a trivalent iron compound, iron oxide (III), etc., the rise of the main peak is around 7120 eV, and iron (II) chloride, iron chloride (II) which is a divalent iron compound. II) The rise of the main peak is observed in the vicinity of 7110 to 7115 eV in tetrahydrate and the like, and the shoulder structure is observed in the spectrum from around 7110 eV in iron metal (0) that is a zerovalent iron compound. Further, the spectrum obtained by measuring the II-valent iron compound has a tendency that the peak top position of the main peak is on the lower energy side as compared with the spectrum obtained by measuring the III-valent iron compound. Specifically, the peak top of the main peak is observed in the vicinity of 7128-7139 eV in the case of the III-valent iron compound, and in the vicinity of 7120-7128 eV in the case of the II-valent iron compound, and more specifically, it is a III-valent iron compound. It is around 7128-7134 eV for iron (III) chloride, about 7132 eV for iron (III) oxide, about 7120 eV for iron (II) chloride, which is a divalent iron compound, and 7123 eV for iron (II) chloride tetrahydrate. A peak top of the main peak is observed in the vicinity.

  Moreover, when evaluating the structure of the iron compound near the iron atom, it is effective to compare the radial distribution functions obtained from the K-edge broad X-ray absorption fine structure (EXAFS), and the distance at which the peak is observed is determined. Judgment is possible by comparison. In iron metal (0), peaks attributed to the Fe—Fe bond are observed around 0.22 nm and 0.44 nm. In iron (III) chloride, a peak attributed to Fe—Cl bond is around 0.16 to 0.17 nm, and in iron (II) chloride, a peak attributed to Fe—Cl bond is around 0.21 nm. ) In the tetrahydrate, a peak due to the Fe—Cl bond is observed in the vicinity of 0.16 to 0.17 nm, and a sub-peak considered to be another Fe—Cl bond is also observed in the vicinity of 0.21 nm. In iron (III) oxide, a peak attributed to the Fe—O bond is observed near 0.15 to 0.17 nm, and a peak attributed to the Fe—Fe bond or the like is observed near 0.26 to 0.33 nm.

  That is, by comparing the spectrum obtained during X-ray absorption fine structure (XAFS) analysis of the reaction product or the reaction product with the spectra of various iron compounds, the valence state of the iron compound and the structure near the iron atom can be grasped. Is possible.

<Addition of transition metal compound>
The polymerization catalyst may be added as it is, but it is preferable that the polymerization catalyst is added to the cyclic polyphenylene sulfide and then uniformly dispersed. Examples of the uniform dispersion method include a mechanical dispersion method and a solvent dispersion method. Specific examples of the mechanical dispersion method include a pulverizer, a stirrer, a mixer, a shaker, and a method using a mortar. Specific examples of the method of dispersing using a solvent include a method of dissolving or dispersing cyclic polyphenylene sulfide in an appropriate solvent, adding a predetermined amount of a polymerization catalyst thereto, and then removing the solvent. In addition, when the polymerization catalyst is dispersed, when the polymerization catalyst is a solid, it is preferable that the average particle size of the polymerization catalyst is 1 mm or less because more uniform dispersion is possible.

  Furthermore, when adding the iron compound, it is preferable to add it under conditions that do not contain moisture. The preferable amount of water contained in the gas phase in contact with the cyclic polyphenylene sulfide and the iron compound to be added is 1% by weight or less, more preferably 0.5% by weight or less, and further preferably 0.1% by weight or less. It is even more preferable not to contain substantially. The molar ratio of the amount of water contained in the cyclic polyphenylene sulfide, the amount of water contained in the polymerization catalyst, and the total amount of water contained as a hydrate in the polymerization catalyst to the added polymerization catalyst is preferably 9 or less. It is preferably 6 or less, more preferably 3 or less, still more preferably 1 or less, and even more preferably 0.1 or less, and still more preferably contains substantially no water. If it is below this moisture content, side reactions, such as an oxidation reaction and a hydrolysis reaction of a low-valent iron compound, can be prevented.

  For this reason, the form of the iron compound to be added is preferably an anhydride rather than a hydrate. In addition, when adding an iron compound, an iron compound and a desiccant may be added together in order to prevent moisture from being contained in the cyclic polyphenylene sulfide and the iron compound. There are metals, neutral desiccants, basic desiccants, acidic desiccants, etc. as desiccants, but it is important that no oxidizing substances be present in the system in order to prevent oxidation of low-valent iron compounds. Therefore, a neutral desiccant and a basic desiccant are preferable. Specific examples of these desiccants include calcium chloride, aluminum oxide, calcium sulfate, magnesium sulfate, and sodium sulfate as neutral desiccants, and potassium carbonate, calcium oxide, barium oxide, and the like as basic desiccants. Of these, calcium chloride and aluminum oxide, which have a relatively large moisture absorption capacity and are easy to handle, are preferable. In addition, when adding an iron compound and a desiccant together, the water content contained in the cyclic polyphenylene sulfide, the water content contained in the polymerization catalyst, and the total amount of water molecules contained as hydrates in the polymerization catalyst. Does not include the amount of water dehydrated by the desiccant.

  The water content can be quantified by the Karl Fischer method. The amount of water contained in the gas phase in contact with the cyclic polyphenylene sulfide and the iron compound to be added can also be calculated from the temperature and relative humidity of the gas phase. In addition, the amount of water contained in the cyclic polyphenylene sulfide and the amount of water contained in the polymerization catalyst can be quantified by using an infrared moisture meter or gas chromatography, and the cyclic polyphenylene sulfide, the polymerization catalyst. Can be obtained from the change in weight before and after heating when heating at a temperature of about 100 to 110 ° C.

  It is preferable to add the iron compound in a non-oxidizing atmosphere. Here, the non-oxidizing atmosphere is an atmosphere in which the oxygen concentration in the gas phase in contact with the cyclic polyphenylene sulfide and the iron compound to be added is 5% by volume or less, preferably 2% by volume or less, more preferably substantially free of oxygen, That is, it indicates an atmosphere of an inert gas such as nitrogen, helium, or argon, and among these, a nitrogen atmosphere is particularly preferable from the viewpoint of economy and ease of handling. Moreover, when adding the said iron compound, it is preferable to add on the conditions which do not contain an oxidizing substance. Here, not containing an oxidizing substance means that the molar ratio of the oxidizing substance contained in the cyclic polyphenylene sulfide to the added polymerization catalyst is 1 or less, preferably 0.5 or less, more preferably 0.1 or less, Even more preferably, it refers to containing substantially no oxidizing substance. The oxidizing substance refers to a substance that oxidizes the polymerization catalyst and changes it to a compound having no catalytic activity, for example, iron (III) oxide. For example, oxygen, organic peroxide, inorganic A peroxide etc. are mentioned. Under such conditions, side reactions such as an oxidation reaction of the low-valent iron compound can be prevented.

<Rotational molding method of cyclic polyphenylene sulfide>
Next, the rotational molding method using cyclic polyphenylene sulfide performed in the presence of a transition metal compound according to the present invention will be described.

  The present invention is characterized by rotationally molding cyclic polyphenylene sulfide by heat polymerization in the presence of a transition metal compound while rotating in a molding die. That is, a normal rotational molding method manufactures a molded body by rotating a resin melt generated by melting a high molecular weight resin in a molding die and forming a resin melt layer on the inner wall of the die. In the present invention, cyclic polyphenylene sulfide, which is a raw material for a high molecular weight resin, is heated and polymerized in the presence of a transition metal compound while rotating in a molding die, whereby a mixed melt of cyclic polyphenylene sulfide and transition metal compound is obtained. Can be formed on the inner wall of the mold to increase the molecular weight in the molten state, and at the same time, the resin melt layer can be formed while maintaining the molten state in the molding mold, thereby rotating the resin. A molded body is manufactured.

  Here, the cyclic polyphenylene sulfide (cyclic polyphenylene sulfide mixture) to which the transition metal compound is added can be fed into a closed mold while the cyclic polyphenylene sulfide mixture remains in a powder state. Alternatively, it is possible to heat the cyclic polyphenylene sulfide mixture to a temperature at which it becomes a molten state and supply it in a molten state into a closed mold, but supply the cyclic polyphenylene sulfide mixture in a molten state. May cause uneven thickness due to high molecular weight during supply, so when supplying in the melt state, supply of cyclic polyphenylene sulfide in the melt state and supply of the transition metal compound. It is preferable to carry out in two steps.

  The heat polymerization temperature (that is, the rotational molding temperature) is preferably a temperature at which the cyclic polyphenylene sulfide melts, and there is no particular limitation as long as it is such a temperature condition, but the heat polymerization temperature is melted by the cyclic polyphenylene sulfide. Above the melting temperature, it becomes easy to form a uniform resin layer in the mold, and the cyclic polyphenylene sulfide tends to be sufficiently converted to PPS.

  Note that the temperature at which the cyclic polyphenylene sulfide melts varies depending on the composition and molecular weight of the cyclic polyphenylene sulfide and the environment during heating, and therefore cannot be uniquely indicated. It is possible to grasp the melting solution temperature by analyzing with a mold calorimeter. However, in general, there is a range of melting and melting temperatures, and even when the melting point is exceeded, there is a tendency for the endotherm accompanying melting to continue. Therefore, in order to melt uniformly, the heating polymerization temperature must be equal to or higher than the melting point of cyclic polyphenylene sulfide. The temperature is preferably 10 ° C. or more higher than the melting point of the cyclic polyphenylene sulfide, more preferably 20 ° C. or more.

  The melting point can be measured with a differential scanning calorimeter.

  Although it depends on the content of the formula (B) having different m contained in the cyclic polyphenylene sulfide, the lower limit of the heat polymerization temperature can be exemplified by 180 ° C. or higher, preferably 200 ° C. or higher, more preferably 220. More than 240 degreeC, More preferably, it is 240 degreeC or more. In this temperature range, the cyclic polyphenylene sulfide is melted and dissolved, and a rotational molded body can be obtained in a short time. On the other hand, if the temperature is too high, undesirable side reactions such as cross-linking reactions and decomposition reactions between cyclic polyphenylene sulfide, between PPS generated by heating, and between PPS and cyclic polyphenylene sulfide tend to occur. In addition, since the properties of the obtained PPS resin may be deteriorated, it is desirable to avoid a temperature at which such an undesirable side reaction is remarkably generated. As an upper limit of heating temperature, 400 degrees C or less can be illustrated, Preferably it is 350 degrees C or less. Furthermore, according to the preferred rotational molding method of the present invention, the heating polymerization temperature can be carried out at 320 ° C. or less, preferably 300 ° C. or less, more preferably 270 ° C. or less, and even more preferably 260 ° C. or less. It is also possible to adopt a heat polymerization temperature. Below such temperature, there is a tendency that adverse effects on the properties of the resulting PPS resin due to undesirable side reactions can be suppressed.

  As a rotation method, uniaxial or simultaneous biaxial rotation or oblique rotation can be given in the horizontal and vertical directions. Further, the rotational speed at the time of rotational molding is not particularly limited, but usually 1 to 100 rpm is preferable. Within this range, the cyclic polyphenylene sulfide mixture can be uniformly attached to the inner wall of the mold, and can be melted and polymerized.

  The atmosphere during the conversion of the cyclic polyphenylene sulfide mixture into a high polymerization degree by heating in the molding die is preferably a non-oxidizing atmosphere. The non-oxidizing atmosphere is an atmosphere in which the oxygen concentration in the gas phase in contact with the cyclic polyphenylene sulfide mixture is 5% by volume or less, preferably 2% by volume or less, and more preferably substantially free of oxygen, that is, nitrogen, helium, argon, etc. In particular, a nitrogen atmosphere is preferable from the viewpoint of economy and ease of handling. When performed under such conditions, side reactions such as oxidation of the transition metal compound as a polymerization catalyst can be prevented, and further, between cyclic polyphenylene sulfide, between PPS produced by heating, and between PPS and cyclic polyphenylene sulfide. Therefore, the occurrence of undesirable side reactions such as crosslinking reaction and decomposition reaction tends to be suppressed.

  Heating of the cyclic polyphenylene sulfide mixture in the molding die is not limited to atmospheric pressure as long as it is in a non-oxidizing atmosphere, and it is also preferably performed under pressurized conditions. The pressurized condition means that the inside of the system in which the reaction is carried out is higher than atmospheric pressure, and there is no particular upper limit, but it is preferably 0.2 MPa or less from the viewpoint of easy handling of the reaction apparatus. When heating is performed under a pressurized condition, it is preferable in that the polymerization catalyst tends to hardly evaporate during heating.

  It is also preferable to heat the cyclic polyphenylene sulfide mixture in the molding die under reduced pressure conditions. Moreover, when it carries out under pressure reduction conditions, it is preferable to make it the pressure reduction conditions after making the atmosphere in a reaction system once non-oxidizing atmosphere. The reduced pressure condition means that the reaction system is lower than the atmospheric pressure, and the upper limit is preferably 50 kPa or less, more preferably 20 kPa or less, and even more preferably 10 kPa or less. An example of the lower limit is 0.1 kPa or more, and 0.2 kPa or more is more preferable. When the decompression condition is at least the preferred lower limit, the cyclic compound of the formula (B) having a low molecular weight contained in the cyclic polyphenylene sulfide is less likely to be volatilized, whereas when it is less than the preferred upper limit, undesirable side reactions such as a crosslinking reaction tend not to occur. There can be obtained a PPS resin having excellent characteristics in terms of thickness unevenness and mechanical properties of the finally obtained rotational molded product, conditions such as heat polymerization temperature, transition metal compound used, ligand, Depending on the cocatalyst species, it is preferable that these components are set within a pressure range that is not lost from the reaction system by vaporization or sublimation.

  In addition, when using a low-valent iron compound as a polymerization catalyst, it is preferable to heat the cyclic polyphenylene sulfide mixture in the molding die under conditions that do not contain moisture. The preferable amount of water contained in the gas phase in contact with the cyclic polyphenylene sulfide and the iron compound to be added is 1% by weight or less, more preferably 0.5% by weight or less, and further preferably 0.1% by weight or less. It is even more preferable not to contain substantially. The molar ratio of the amount of water contained in the cyclic polyphenylene sulfide, the amount of water contained in the polymerization catalyst, and the total amount of water contained as a hydrate in the polymerization catalyst to the added polymerization catalyst is preferably 9 or less. It is preferably 6 or less, more preferably 3 or less, still more preferably 1 or less, and even more preferably 0.1 or less, and still more preferably contains substantially no water. If it is below this moisture content, side reactions, such as an oxidation reaction and a hydrolysis reaction of a low-valent iron compound, can be prevented.

  The water content can be quantified by the Karl Fischer method. The amount of water contained in the gas phase in contact with the cyclic polyphenylene sulfide and the iron compound to be added can also be calculated from the temperature and relative humidity of the gas phase. In addition, the amount of water contained in the cyclic polyphenylene sulfide and the amount of water contained in the polymerization catalyst can be quantified by using an infrared moisture meter or gas chromatography, and the cyclic polyphenylene sulfide, the polymerization catalyst. Can be obtained from the change in weight before and after heating when heating at a temperature of about 100 to 110 ° C.

  Various polymerization characteristics such as the content and the number of repetitions (m) of the cyclic compound of the formula (B) in the cyclic polyphenylene sulfide and the number of repetitions in the cyclic polyphenylene sulfide used, and the type of polymerization catalyst used. Moreover, since it differs depending on conditions such as the heating polymerization temperature, it cannot be uniformly defined, but it is preferable to set so that the above-mentioned undesirable side reaction does not occur as much as possible. Examples of the heat polymerization time include 1 minute to 180 minutes, preferably 1 minute to 150 minutes, and more preferably 1 minute to 120 minutes. According to the preferred rotational molding method of the present invention, heating in the molding die can be performed in 120 minutes or less. Examples of the heating time include 120 minutes or less, further 60 minutes or less, 30 minutes or less, 20 minutes or less, and 10 minutes or less. In 1 minute or longer, the cyclic polyphenylene sulfide is sufficiently converted to PPS, and in 180 minutes or less, the rotational molding process time is short, the productivity is high, and it is possible to suppress the adverse effect on the properties of PPS obtained by an undesirable side reaction. It is in.

  According to the method of the present invention, a high-molecular weight PPS rotational molded body can be obtained by heat polymerization while rotating a cyclic polyphenylene sulfide mixture in a molding die. As a preferable chemical structure of the PPS, the repeating unit represented by the structural formula (A) is a main constituent unit, preferably the repeating unit is 70 mol% or more, more preferably 80 mol% or more, and still more preferably 90 A homopolymer or copolymer containing at least mol%. When the repeating unit is 70 mol% or more, the heat resistance, chemical resistance, and mechanical properties inherent to the PPS resin are obtained, which is preferable.

  Moreover, PPS can also comprise less than 30 mol% of the repeating units with a repeating unit of formula, — (Ar—S) —, etc., and the repeating units may be included randomly or in blocks. Or any of their mixtures. Ar includes units represented by the formulas (C) to (M).

  Furthermore, as long as the repeating unit represented by the structural formula (A) is a main structural unit, the PPS can contain a small amount of branch units or crosslinking units represented by the formulas (N) to (P). The copolymerization amount of these branch units or cross-linking units is preferably in the range of 0 to 1 mol% with respect to 1 mol of the unit of the structural formula (A). Further, the PPS in the present invention may be any of a random copolymer, a block copolymer and a mixture thereof containing the above repeating unit.

  In the rotational molding method of the present invention, the preferable range of the conversion ratio of cyclic polyphenylene sulfide to PPS varies depending on the molecular weight of PPS, but cannot be uniquely determined, but is preferably 70% or more, preferably 80% or more. Is more preferable, and 90% or more is more preferable. When the conversion rate is 70% or more, it is possible to obtain a rotational molded body having excellent mechanical strength and original characteristics of the PPS resin.

  The preferable range of the molecular weight of PPS obtained by this method cannot be uniquely determined because it varies depending on the conversion ratio of cyclic polyphenylene sulfide to PPS. However, the mechanical properties of the finally obtained rotary molded article and the PPS resin Also from the viewpoint of maintaining the original characteristics, the weight average molecular weight (Mw) is 10,000 or more, preferably 15,000 or more, more preferably 17,000 or more, still more preferably 20,000 or more, and even more preferably 25. 30,000 or more, still more preferably 30,000 or more. When the weight average molecular weight is 10,000 or more, the mechanical strength of the obtained rotational molded article is high, and the original characteristics of the PPS resin can be obtained. The upper limit of the weight average molecular weight is not particularly limited, but it can be exemplified as a preferable range of less than 1,000,000, more preferably less than 500,000, still more preferably less than 200,000. It is possible to obtain a rotational molded body having strength and characteristics inherent to the PPS resin.

  The PPS obtained by the rotational molding method of the present invention has a feature that the molecular weight distribution is broad, that is, the degree of dispersion expressed by the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) is narrow. The dispersity of PPS obtained by the production method of the present invention is preferably 2.5 or less, more preferably 2.3 or less, further preferably 2.1 or less, and even more preferably 2.0 or less. When the degree of dispersion is 2.5 or less, the amount of low-molecular components contained in PPS tends to decrease, which is an improvement in the mechanical properties of the rotational molded product, reduction in the amount of gas generated when heated, and contact with a solvent. It tends to be a factor such as a reduction in the amount of eluted components. The weight average molecular weight and number average molecular weight can be determined using, for example, SEC (size exclusion chromatography) equipped with a differential refractive index detector.

  In this way, after heating and polymerizing while rotating in the molding die to increase the molecular weight, the resin layer is solidified by cooling while rotating the die, then the mold is opened and the molded product is taken out Thus, a rotational molded body made of PPS resin can be manufactured.

<Other ingredients>
In the cyclic polyphenylene sulfide of the present invention, a fibrous and / or non-fibrous filler can be further blended as necessary within a range not impairing the effects of the present invention. The blending amount can be blended in the range of up to 400 parts by weight with respect to 100 parts by weight of cyclic polyphenylene sulfide. In terms of obtaining higher mechanical properties, dimensional stability, etc., cyclic polyphenylene sulfide 100 It is preferable to blend 0.1 to 350 parts by weight of fibrous and / or non-fibrous filler with respect to parts by weight.

  As the fibrous and / or non-fibrous filler blended as necessary in the present invention, glass fiber, carbon fiber, potassium titanate whisker, zinc oxide whisker, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, Fibrous filler such as stone fiber, metal fiber, wollastonite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, alumina silicate, etc., alumina, silicon oxide, magnesium oxide, zirconium oxide, oxidation Metal compounds such as titanium and iron oxide, carbonates such as calcium carbonate, magnesium carbonate and dolomite, sulfates such as calcium sulfate and barium sulfate, glass beads, ceramic beads, boron nitride, silicon carbide, calcium phosphate and silica Non-fibrous fillers such as May be I, it is also possible to further combination of these fillers 2 or more. Further, it is more preferable to use these fibrous and / or non-fibrous fillers after pretreatment with a silane or titanate coupling agent in view of mechanical strength.

  In the cyclic polyphenylene sulfide of the present invention, the antioxidant, heat stabilizer, lubricant, plasticizer, crystal nucleating agent, ultraviolet light inhibitor, colorant, flame retardant and the like are used as long as the effects of the present invention are not impaired. Additives can be added. In addition, the PPS resin composition of the present invention is within the range that does not impair the effects of the present invention. Polyamide, polyphenylene oxide, polysulfone, tetrafluoropolyethylene, polyetherimide, polyamideimide, polyimide, polycarbonate, polyethersulfone, polyetherketone , Polyether ether ketone, epoxy resin, phenol resin, polyethylene, polystyrene, polypropylene, ABS resin, polyester, polyamide elastomer, polyester elastomer and the like may be included.

  Furthermore, the cyclic polyphenylene sulfide of the present invention has a γ-glycidoxypropyltrimethoxysilane, γ-glycolyl group for the purpose of improving mechanical strength and moldability such as burrs, etc. within a range not impairing the effects of the present invention. Sidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureido Propyltrimethoxysilane and γ- (2-ureidoethyl) aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanate Natopropylme Distearate silane, .gamma.-isocyanatopropyl ethyl dimethoxy silane, .gamma.-isocyanatopropyl ethyldiethoxysilane, may be added to the organic silane compound such as .gamma.-isocyanatopropyl trichlorosilane.

  The method for mixing the various additives described above is not particularly limited. For example, cyclic polyphenylene sulfide and other additives as necessary may be blended in advance, or after blending, a single or twin screw extruder. It can be heated and melt-mixed with a mixer such as a Banbury mixer.

  By rotational molding of the cyclic polyphenylene sulfide of the present invention, a rotational molded body having excellent characteristics can be obtained at a low temperature and in a short time compared to the conventional rotational molding method, and the rotational moldability is dramatically improved. improves.

  The rotational molded body of the present invention may be a metallic container lined with a resin layer on the inner surface, or may be coated with other types of resin layers on the outside or inside of the molded product. The resin layer may be provided before the rotational molding of the present invention or may be provided after the rotational molding of the present invention.

  The rotational molded body thus obtained has the characteristics of PPS resin, such as heat resistance, barrier properties, chemical resistance, electrical insulation properties, moisture and heat resistance, flame resistance, impurity non-eluting properties, water permeability, dimensions. Because of its excellent stability, it can be used for transportation of kerosene, gasoline, etc., oil tanks for automobiles, automobiles, etc., oil storage containers for gasoline tanks, etc. For example, it can be suitably used in the field of various containers used in the manufacturing process of semiconductor elements and liquid crystal display elements.

  The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting.

<Measurement of conversion>
The conversion of cyclic polyphenylene sulfide to PPS was calculated by the following method using high performance liquid chromatography (HPLC).

About 10 mg of a product obtained by heating cyclic polyphenylene sulfide was dissolved in about 5 g of 1-chloronaphthalene at 250 ° C. A precipitate formed upon cooling to room temperature. The 1-chloronaphthalene insoluble component was filtered using a membrane filter having a pore size of 0.45 μm to obtain a 1-chloronaphthalene soluble component. The amount of unreacted cyclic polyphenylene sulfide was quantified by HPLC measurement of the obtained soluble component, and the conversion rate of cyclic polyphenylene sulfide to PPS was calculated. The measurement conditions for HPLC are shown below.
Apparatus: Shimadzu Corporation LC-10Avp series Column: Mightysil RP-18 GP150-4.6 (5 μm)
Detector: Photodiode array detector (UV = 270 nm).

<Molecular weight measurement>
The molecular weights of PPS and cyclic polyphenylene sulfide were calculated in terms of polystyrene by gel permeation chromatography (GPC) which is a type of size exclusion chromatography (SEC). The measurement conditions for GPC are shown below.
Equipment: Senshu Science SSC-7100
Column name: Senshu Science GPC3506
Eluent: 1-chloronaphthalene detector: differential refractive index detector Column temperature: 210 ° C
Pre-constant temperature: 250 ° C
Pump bath temperature: 50 ° C
Detector temperature: 210 ° C
Flow rate: 1.0 mL / min
Sample injection amount: 300 μL (slurry: about 0.2% by weight).

<Measurement of X-ray absorption fine structure (XAFS)>
The X-ray absorption fine structure of the transition metal compound was measured under the following conditions.
Experimental Facility: High Energy Accelerator Research Organization Synchrotron Radiation Research Facility Spectrometer: Si (111) 2 crystal spectrometer Absorption edge: Pd-L3 (3180 eV) absorption edge, Fe K (7113 eV) Absorption edge detector: Ion chamber and Lytle detector.
Analysis conditions (Pd): E0: 3173.0 eV, pre-edge range: -10 to -5 eV, normalization range: 18 to 27 eV.

<Measurement of melting point>
The melting point of cyclic polyphenylene sulfide was measured under the following conditions. In addition, the sample used the fine granule of 2 mm or less.
Device: DSC7 manufactured by PerkinElmer
Measurement atmosphere: Sample preparation weight under nitrogen stream: Approximately 10 mg
Measurement conditions (a) Hold for 1 minute at a program temperature of 50 ° C. (b) Increase the temperature from the program temperature of 50 ° C. to 400 ° C. (Temperature increase rate: 20 ° C./min).

<Rotational molding>
FIG. 1 shows a schematic diagram of a rotary molding machine used in Examples and Comparative Examples of the present invention. As shown in FIG. 1, 200 g of the cyclic polyphenylene sulfide powder of the present invention was placed in a cylindrical mold 1 having an inner diameter of 70 mm and a length of 150 mm of a rotary molding apparatus, and the atmosphere was replaced with nitrogen by a nitrogen flow. The mold 1 was previously set to a heating polymerization temperature and heated. The mold 1 is supported by a rotating shaft 2 and is rotated horizontally by a motor 3. The mold 1 was placed in the heating furnace 4 after the raw materials were charged in a powder state. The heating furnace 4 was previously set to the heating polymerization temperature of the cyclic polyphenylene sulfide. Then, it heat-polymerized for predetermined time, rotating in the heating furnace 4 at the rotation speed of 30 rpm. The time at this time is defined as the heat polymerization time. Then, after heating the heating furnace 4 to 200 degreeC and stopping rotation, the metal mold | die 1 was taken out from the heating furnace 4, and water-cooled. Thereafter, the molded product was taken out after cooling to room temperature.

Reference Example 1 (Preparation of cyclic polyphenylene sulfide)
In an autoclave equipped with a stirrer, 42.7% sodium hydrosulfide 82.7 kg (700 mol), 96% sodium hydroxide 29.6 kg (710 mol), N-methyl-2-pyrrolidone (NMP) 114.4 kg (1156) Mol), 17.2 kg (210 mol) of sodium acetate, and 105 kg of ion-exchanged water, gradually heated to about 240 ° C. over about 3 hours while flowing nitrogen at normal pressure, and 148 kg of water and After distilling 2.8 kg of NMP, the reaction vessel was cooled to 160 ° C. In addition, 0.02 mol of hydrogen sulfide per 1 mol of the sulfur component charged during this liquid removal operation was scattered out of the system.

  Next, 103 kg (703 mol) of p-dichlorobenzene and 90.0 kg (910 mol) of NMP were added, and the reaction vessel was sealed under nitrogen gas. While stirring at 240 rpm, the temperature was raised to 270 ° C. at a rate of 0.6 ° C./min and held at this temperature for 140 minutes. While 12.6 kg (700 mol) of water was injected over 15 minutes, it was cooled to 250 ° C. at a rate of 1.3 ° C./min. Thereafter, the slurry was cooled to 220 ° C. at a rate of 0.4 ° C./min, and then rapidly cooled to near room temperature to obtain a slurry (A). This slurry (A) was diluted with 200 kg of NMP to obtain a slurry (B).

  100 kg of slurry (B) heated to 80 ° C. is filtered through a sieve (80 mesh, mesh opening 0.175 mm), granular PPS resin containing the slurry as a mesh-on component, and about 75 kg of slurry (C) as a filtrate component. Obtained.

  Of the obtained slurry (C), 50 kg was charged into a devolatilizer and replaced with nitrogen, and then treated at 100 to 150 ° C. under reduced pressure for 1.5 hours, and then treated at 150 ° C. for 1 hour in a vacuum dryer. To obtain a solid.

  After adding 60 kg of ion-exchanged water (1.2 times the amount of slurry (C)) to this solid, it was stirred at 70 ° C. for 30 minutes to make a slurry again. Radiolite # 800S (manufactured by Showa Chemical Industry Co., Ltd.) 150 g of ion-exchanged water dispersed in 150 g of the dispersion liquid is filtered by suction with a filter having an aperture of 10 to 16 μm. The slurry was used for solid-liquid separation. To the obtained brown cake, 60 kg of ion exchanged water was added and stirred at 70 ° C. for 30 minutes to make a slurry again. Similarly, after suction filtration, vacuum drying was performed at 70 ° C. for 5 hours to obtain 700 g of a dry solid.

  700 g of the obtained dry solid was brought into contact with a solvent by stirring at a bath temperature of about 30 ° C. for 5 hours using 16.8 kg of chloroform as a solvent. Subsequently, filtration was performed to obtain an extract. About 14 kg of chloroform was distilled off from this extract, and this was slowly added dropwise to 35 kg of methanol over about 10 minutes while stirring. After completion of dropping, stirring was continued for about 15 minutes. The precipitate was collected by suction filtration with a filter having an opening of 10 to 16 μm, and the resulting white cake was vacuum dried at 70 ° C. for 3 hours to obtain 210 g of a white powder. The yield of white powder was 31% based on the polyphenylene sulfide mixture used.

  From the absorption spectrum in the infrared spectroscopic analysis of this white powder, it was confirmed that the white powder was a compound composed of phenylene sulfide units. In addition, this white powder is composed mainly of p-phenylene sulfide units based on mass spectral analysis of components separated by high performance liquid chromatography (same as the measurement of conversion rate) and molecular weight information by MALDI-TOF-MS. About 12%, about 12%, and about 27% of cyclic compounds having 5, 6 and 7 repeating units as weight units, and about 43% of cyclic compounds having 8 to 12 repeating units, respectively. It was found to be a cyclic polyphenylene sulfide containing. In the measurement of the melting point, a main peak of endotherm was observed at 214 ° C.

Example 1
The powder obtained by mixing 1 mol% of tris (dibenzylideneacetone) dipalladium with respect to the sulfur atom in the cyclic polyphenylene sulfide was mixed with the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance at the same temperature as the heating polymerization temperature ( The product was placed in a mold heated to 300 ° C. and polymerized by heating in a rotary molding machine at 300 ° C. for 10 minutes at a rotation speed of 30 rpm, thereby obtaining a cylindrical rotational molded product having an inner diameter of 70 mm and a length of 150 mm.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 87%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 44,100 and a dispersity of 1.9. It was. As a result of X-ray absorption fine structure analysis of tris (dibenzylideneacetone) dipalladium, the peak maximum value of the absorption coefficient near the X-ray absorption edge after normalization was 3.43. According to the present invention, it was possible to obtain a rotational molded body by heating in a short time of 10 minutes under the condition of a heating polymerization temperature of 300 ° C.

Example 2
A powder obtained by mixing 2 mol% of iron (III) chloride with respect to sulfur atoms in the cyclic polyphenylene sulfide in the air in the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance is the same temperature as the heating polymerization temperature. It was put in a mold heated to (300 ° C.) and polymerized by heating in a rotary molding machine at 300 ° C. for 10 minutes at a rotation speed of 30 rpm, thereby obtaining a cylindrical rotational molded product having an inner diameter of 70 mm and a length of 150 mm.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 79%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the PPS component in the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide.

  As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 27,200 and a dispersity of 2.4. It was. According to the present invention, it was possible to obtain a rotational molded body by heating in a short time of 10 minutes under the condition of a heating polymerization temperature of 300 ° C.

  Moreover, the XAFS measurement using PPS which cut off the plane part from the molded article was performed, and the valence state of the iron compound and the structure near the iron atom were analyzed. As a result, in the absorption spectrum relating to XANES, a main peak is observed at the same position as that of iron (II) chloride although the shape is different. In the radial distribution function, iron (III) chloride and iron (II) chloride are around 0.16 nm. A main peak considered to have the same characteristics as tetrahydrate, and a sub-peak considered to have the same characteristics as iron (II) chloride and iron (II) chloride tetrahydrate were observed around 0.21 nm. From this, it was confirmed that iron (II) chloride, which is a II-valent iron compound, is present together with a III-valent iron compound, and iron (II) having a low valence is converted from iron (III) chloride in the system at the time of rotational molding. It was found that the component was produced.

Comparative Example 1
The cyclic polyphenylene sulfide powder obtained in Reference Example 1 is put in a mold heated in advance to the same temperature (300 ° C.) as the heating polymerization temperature, and is kept at 300 ° C. for 10 minutes at 30 rpm in a rotary molding machine. Although heat polymerization was performed, the molded product was brittle and could not be taken out from the mold.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the flat surface portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 11%. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 25,000 and a dispersity of 1.8. It was. When a polymerization catalyst for accelerating the polymerization of cyclic polyphenylene sulfide is not added, the conversion of cyclic polyphenylene sulfide to PPS is insufficient under the conditions of a heating polymerization temperature of 300 ° C. and a heating polymerization time of 10 minutes. I found it impossible.

Comparative Example 2
A powder obtained by mixing 1 mol% of a sodium salt of thiophenol with respect to the sulfur atom in the cyclic polyphenylene sulfide in the cyclic polyphenylene sulfide obtained in Reference Example 1 is the same temperature (300 ° C.) as the heating polymerization temperature in advance. Was heated and polymerized in a rotary molding machine at 300 ° C. for 10 minutes at a rotation speed of 30 rpm, but the molded product was brittle and could not be removed from the mold.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the flat surface portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 11%. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 16,500 and a dispersity of 1.8. It was. Even when a sodium salt of thiophenol is used, the conversion of cyclic polyphenylene sulfide to PPS is insufficient under the conditions of a heating polymerization temperature of 300 ° C. and a heating polymerization time of 10 minutes, and the resulting PPS has a low weight average molecular weight, It was found that a rotational molded body could not be obtained.

Comparative Example 3
A powder obtained by mixing 1 mol% of 2,2′-dithiobisbenzothiazole with respect to the sulfur atom in the cyclic polyphenylene sulfide in the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance is the same temperature as the heating polymerization temperature. Although it put into the metal mold | die heated to (300 degreeC) and heat-polymerized in a rotary molding machine at 300 rpm for 10 minutes and the rotation speed of 30 rpm, the molded article was fragile and could not be taken out from a metal mold | die.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 16%. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 14,700 and a dispersity of 1.7. It was. 2,2′-dithiobisbenzothiazole accelerates the polymerization of cyclic polyphenylene sulfide, but its effect is insufficient. Even when 2,2′-dithiobisbenzothiazole is used, the heat polymerization temperature is 300 ° C. It was found that under the condition of time 10 minutes, the conversion of cyclic polyphenylene sulfide to PPS was insufficient, the weight average molecular weight of the obtained PPS was low, and a rotational molded body could not be obtained.

Example 3
The powder obtained by mixing 1 mol% of tris (dibenzylideneacetone) dipalladium with respect to the sulfur atom in the cyclic polyphenylene sulfide was mixed with the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance at the same temperature as the heating polymerization temperature ( The sample was placed in a mold heated to 260 ° C. and polymerized by heating in a rotary molding machine at 260 ° C. for 10 minutes at a rotation speed of 30 rpm, thereby obtaining a cylindrical rotational molded product having an inner diameter of 70 mm and a length of 150 mm.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the flat surface portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 81%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 49,500 and a dispersity of 1.8. It was. According to the present invention, it was possible to obtain a rotational molded body by heating in a short time of only 10 minutes even under a low temperature condition of a heating polymerization temperature of 260 ° C.

Example 4
The powder obtained by mixing 1 mol% of tris (dibenzylideneacetone) dipalladium with respect to the sulfur atom in the cyclic polyphenylene sulfide was mixed with the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance at the same temperature as the heating polymerization temperature ( It was placed in a mold heated to 300 ° C. and polymerized by heating in a rotary molding machine at 300 ° C. for 30 minutes at a rotation speed of 30 rpm to obtain a cylindrical rotational molded product having an inner diameter of 70 mm and a length of 150 mm.

  The characteristics of the molded product are shown in Table 1. As a result of the conversion rate measurement using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 88%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 44,700 and a dispersity of 2.0. It was. From a comparison with Example 1, it was found that a rotational molded body having a higher conversion of cyclic polyphenylene sulfide to PPS can be obtained by setting the heat polymerization time to 10 minutes to 30 minutes.

Example 5
A powder obtained by mixing 2 mol% of iron (III) chloride with respect to sulfur atoms in the cyclic polyphenylene sulfide in the air in the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance is the same temperature as the heating polymerization temperature. It was put in a mold heated to (300 ° C.) and polymerized by heating in a rotary molding machine at 300 ° C. for 30 minutes at a rotation speed of 30 rpm, thereby obtaining a cylindrical rotational molded product having an inner diameter of 70 mm and a length of 150 mm.

  The characteristics of the molded product are shown in Table 1. As a result of measuring the conversion rate using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 86%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the PPS component in the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 27,500 and a dispersity of 2.4. It was. From a comparison with Example 2, it was found that a rotational molded body having a higher conversion ratio of cyclic polyphenylene sulfide to PPS can be obtained by setting the heat polymerization time to 10 minutes to 30 minutes.

Example 6
The powder obtained by mixing 1 mol% of tris (dibenzylideneacetone) dipalladium with respect to the sulfur atom in the cyclic polyphenylene sulfide was mixed with the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance at the same temperature as the heating polymerization temperature ( It was placed in a mold heated to 300 ° C. and polymerized by heating in a rotary molding machine at 300 ° C. for 60 minutes at a rotation speed of 30 rpm to obtain a cylindrical rotational molded product having an inner diameter of 70 mm and a length of 150 mm.

  The characteristics of the molded product are shown in Table 1. As a result of the measurement of the conversion rate using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 90%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 42,200 and a dispersity of 1.9. It was. From a comparison with Example 1 and Example 4, it was found that it is possible to obtain a rotational molded body having a higher conversion ratio of cyclic polyphenylene sulfide to PPS by setting the heat polymerization time to 60 minutes. .

Example 7
A powder obtained by mixing 2 mol% of iron (III) chloride with respect to sulfur atoms in the cyclic polyphenylene sulfide in the air in the cyclic polyphenylene sulfide obtained in Reference Example 1 in advance is the same temperature as the heating polymerization temperature. A cylindrical rotary molded product having an inner diameter of 70 mm and a length of 150 mm was obtained by placing in a mold heated to (300 ° C.) and heating and polymerizing in a rotary molding machine at 300 ° C. for 60 minutes at a rotation speed of 30 rpm.

  The characteristics of the molded product are shown in Table 1. As a result of the conversion rate measurement using PPS obtained by cutting out the planar portion from the molded product, it was found that the conversion rate of cyclic polyphenylene sulfide to PPS was 94%. In addition, it confirmed from the absorption spectrum in an infrared spectroscopic analysis that a molded article is PPS. Further, it was found that the PPS component in the molded article was soluble in 1-chloronaphthalene at 250 ° C., and there were few branch units or crosslinking units of polyphenylene sulfide. As a result of GPC measurement, a peak derived from cyclic polyphenylene sulfide and a peak of the produced polymer (PPS) were confirmed, and it was found that the obtained PPS had a weight average molecular weight of 27,800 and a dispersity of 2.4. It was. From a comparison with Example 2 and Example 5, it was found that a rotational molded body having a higher conversion ratio of cyclic polyphenylene sulfide to PPS can be obtained by setting the heat polymerization time to 60 minutes. .

1 Cylindrical mold 2 Rotating shaft 3 Motor 4 Heating furnace

  As described above, a rotational molding method in which the rotational moldability is dramatically improved by heating and polymerizing cyclic polyphenylene sulfide while rotating in a mold in the presence of a transition metal compound, and the rotational molding obtained by the method. Provide the body.

Claims (13)

A rotational molding method comprising heat polymerizing cyclic polyphenylene sulfide while rotating in a mold in the presence of a transition metal compound. The rotational molding method according to claim 1, wherein the transition metal compound is a zero-valent transition metal compound. 3. The rotational molding method according to claim 2, wherein the zero-valent transition metal compound is a compound containing a metal in groups 8 to 11 and 4 to 6 in the periodic table. The rotational molding method according to claim 1, wherein the transition metal compound is a low-valent iron compound. The rotational molding method according to claim 4, wherein the low-valent iron compound is a II-valent iron compound. The rotational molding method according to any one of claims 1 to 5, wherein the transition metal compound is heated and polymerized in the presence of 0.001 to 20 mol% with respect to a sulfur atom in the cyclic polyphenylene sulfide. The rotational molding method according to any one of claims 1 to 6, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 400 ° C. The rotational molding method according to any one of claims 1 to 6, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 300 ° C. The rotational molding method according to any one of claims 1 to 6, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 270 ° C. The rotational molding method according to any one of claims 1 to 6, wherein the heating temperature at the time of heat polymerization while rotating in the mold is not lower than the melting point of the cyclic polyphenylene sulfide and not higher than 260 ° C. The rotation molding method according to any one of claims 1 to 10, wherein a heating time for heat polymerization while rotating in a mold is 1 minute or more and 120 minutes or less. The rotation molding method according to any one of claims 1 to 10, wherein a heating time for heat polymerization while rotating in the mold is 1 minute or more and 30 minutes or less. The rotational molding method according to any one of claims 1 to 12, wherein a repeating number (m) in the following formula contained in the cyclic polyphenylene sulfide is 4 to 50.

Images