HK1181795B - Polyarylene sulfide having excellent processability and preparation method thereof - Google Patents

Abstract

The present invention relates to a polyarylene sulfide in which a ratio of a peak area of a polymer chain of a second polyarylene sulfide, having a molecular weight equal to or lower than the maximum peak molecular weight, to a peak area of a polymer chain of a first polyarylene sulfide, having a molecular weight equal to or higher than the maximum peak molecular weight, is 1.3 or less in the molecular weight distribution of the polyarylene sulfide as measured by gel permeation chromatography using polystyrene as a standard. The present invention also relates to a method for preparing the polyarylene sulfide. The polyarylene sulfide of the present invention has excellent formability, generates no burrs or the like, and can be well-formed into products which require high molding accuracy.

Description

Polyarylene sulfide having excellent processability and method for preparing the same

Technical Field

The present invention relates to polyarylene sulfide (PAS) which exhibits excellent processability and does not generate burrs (flashes) or the like and can satisfactorily mold a product requiring high molding accuracy, and a method for preparing the same.

Background

Polyarylene sulfide, a typical engineering plastic, has been recently in great demand as a material for high temperature and corrosive environments and electronic products due to its excellent heat resistance, chemical resistance, flame resistance and electrical insulation. Polyarylene sulfides are mainly used for computer parts, automobile parts, protective coatings against corrosive chemicals, chemical-resistant industrial fabrics, and the like.

The only polyarylene sulfide commercially available is polyphenylene sulfide (hereinafter referred to as PPS). The current commercial synthesis method for PPS involves the reaction of p-dichlorobenzene (hereinafter, referred to as pDCB) and sodium sulfide in a polar organic solvent such as N-methylpyrrolidone. This method is known as the Macallum method and is based on U.S. Pat. nos. 2,513,188 and 2,583,941. While some other types of useful polar solvents have been proposed in the commercial production of PPS, one of the major uses is N-methylpyrrolidone. The PPS production process is generally carried out using a dichloroaromatic compound as a reactant, and sodium chloride is produced as a by-product.

Meanwhile, PPS obtained in the Macallum process generally has high fluidity and thus can be molded even at low pressure. Therefore, it is known to have high workability. However, when PPS is used to form products requiring high precision or having a flat shape, such as various computer parts or electronic products, burrs (burrs) are generated on the molded product, and thus there is a limitation in application thereof to the production of precision parts.

Detailed Description

Technical purpose

An object of the present invention is to provide a polyarylene sulfide that exhibits excellent processability and does not generate burrs or the like, and can satisfactorily mold a product requiring high molding accuracy.

It is another object of the present invention to provide a method for preparing polyarylene sulfide.

It is still another object of the present invention to provide a molded article, film, sheet or fabric composed of polyarylene sulfide.

Technical scheme

The present invention provides polyarylene sulfide in which a ratio of a peak area of a polymer chain of a second polyarylene sulfide having a lower molecular weight than a maximum peak molecular weight to a peak area of a polymer chain of a first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight is 1.3 or less in a molecular weight distribution of the polyarylene sulfide as measured by gel permeation chromatography using polystyrene as a standard.

Further, the present invention provides a method for preparing the polyarylene sulfide, comprising the steps of: polymerizing reactants including a diiodo aromatic compound and a sulfur compound, and additionally adding 0.01 to 30 parts by weight, preferably 0.1 to 20 parts by weight, more preferably 1.0 to 15 parts by weight of the sulfur compound based on 100 parts by weight of the sulfur compound included in the reactants while maintaining the polymerization step.

In addition, the present invention provides a product manufactured by molding the polyarylene sulfide.

Hereinafter, polyarylene sulfide, a method of preparing polyarylene sulfide, and a product manufactured by molding polyarylene sulfide according to embodiments of the present invention will be described in detail.

According to one embodiment, the present invention provides a polyarylene sulfide in which a ratio of a peak area of a polymer chain of a second polyarylene sulfide having a lower molecular weight than a maximum peak molecular weight to a peak area of a polymer chain of a first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight is 1.3 or less in a molecular weight distribution of the polyarylene sulfide as measured by gel permeation chromatography using polystyrene as a standard.

The present inventors have made many attempts to develop polyarylene sulfide that exhibits excellent processability and does not generate burrs or the like, and can satisfactorily mold a product requiring high molding accuracy, thereby completing the present invention.

When computer parts or electronic products requiring high molding accuracy are molded using conventional polyarylene sulfide, there is a problem in that: the polyarylene sulfide having high fluidity flows out through gaps in a casting for molding to generate burrs around the molded article. That is, an additional method should be performed to remove the burr, which complicates the molding process. In addition, there is a concern that molding defects of products are caused by generation of burrs.

The term "burr (burr)" means that the molten resin leaked from the coated surface of the casting adheres to the molded article in the form of a film. These burrs may be generated due to injection conditions such as excessively high injection pressure, casting defects, or the like, or may be generated mainly due to excessively high fluidity of the resin. Throughout this specification, a burr is defined as being caused by the latter problem.

Meanwhile, the term "number average molecular weight" throughout the present specification is defined as an average molecular weight of polyarylene sulfide in a molecular weight distribution curve of polyarylene sulfide as measured by GPC using polystyrene as a standard, which is calculated by the following formula 1, unless otherwise specified.

[ formula 1]

Herein, w represents the total weight of the subject polyarylene sulfide, Mi represents the molecular weight of polymer chains of the specific polyarylene sulfide included in the subject polyarylene sulfide, and Ni represents the number of moles of polymer chains having the molecular weight of Mi among the polymer chains of the polyarylene sulfide included in the subject polyarylene sulfide.

In addition, the term "maximum peak point" or "maximum peak molecular weight" throughout the present specification is defined as a molecular weight of a polymer chain showing a maximum voltage (voltage expressed by microvolts measured by an RI detector when a molecular weight distribution is measured by gel permeation chromatography) in a target polyarylene sulfide in a molecular weight distribution curve of the polyarylene sulfide as measured by Gel Permeation Chromatography (GPC) using polystyrene as a standard.

Meanwhile, the present inventors can prepare polyarylene sulfide by the aforementioned method, in which the ratio of the peak area of the polymer chain of the second polyarylene sulfide having a lower molecular weight than the maximum peak molecular weight (i.e., the polymer chain having a longer retention time based on the maximum peak point in the molecular weight distribution curve measured by gel permeation chromatography (hereinafter, referred to as GPC)) to the peak area of the polymer chain of the first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight (i.e., the polymer chain having a shorter retention time based on the maximum peak point in the molecular weight distribution curve measured by GPC) is within the same range as in the molecular weight distribution of polyarylene sulfide as measured by GPC using polystyrene as a standard. In particular, the present inventors found that polyarylene sulfide having a non-excessive content of polymer chains having a molecular weight lower than the maximum peak molecular weight and showing a molecular weight distribution curve similar to that of a unimodal normal distribution curve shows excellent processability and does not generate burrs or the like, so that a product requiring high molding accuracy is satisfactorily molded, thereby completing the present invention.

In the polyarylene sulfide according to one embodiment of the present invention, in a molecular weight distribution of the polyarylene sulfide as measured by gel permeation chromatography using polystyrene as a standard, a ratio of a peak area of a polymer chain of the second polyarylene sulfide having a lower molecular weight than a maximum peak molecular weight to a peak area of a polymer chain of the first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight is 1.3 or less.

In the molecular weight distribution of the polyarylene sulfide, a ratio of a peak area of a polymer chain of the second polyarylene sulfide having a lower molecular weight than the maximum peak molecular weight to a peak area of a polymer chain of the first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight has a lowest limit value of 1 or more, and thus the ratio of the peak area of the polymer chain of the second polyarylene sulfide having a lower molecular weight than the maximum peak molecular weight is the same as or higher than the ratio of the peak area of the polymer chain of the first polyarylene sulfide.

Meanwhile, molecular weight distribution curves of polyarylene sulfide according to an embodiment of the present invention are shown in fig. 1 and 2. As shown in fig. 1 and 2, the molecular weight distribution was found to be similar to a normal distribution curve. The polyarylene sulfide according to the above embodiment exhibits a single peak in a molecular weight distribution curve similar to a normal distribution curve.

The experimental results of the present inventors have shown that the polyarylene sulfide having such a molecular weight distribution characteristic has appropriate flowability to exhibit processability equal to or higher than previously known processability, and can be used to satisfactorily form products requiring high precision or having a planar shape without generating burrs (flashes) or the like during molding of the polyarylene sulfide.

Since the contents of the polymer chain of the first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight and the polymer chain of the second polyarylene sulfide having a lower molecular weight than the maximum peak molecular weight are almost the same in the polyarylene sulfide, the flowability of the polyarylene sulfide can be optimized, and the amount of burrs (flashes) generated during molding due to excessively high flowability can also be minimized.

Therefore, the polyarylene sulfide according to this embodiment exhibits excellent processability and does not generate burrs or the like, and can be used to satisfactorily form various electronic products requiring high precision.

The polyarylene sulfide according to the above embodiment exhibits a molecular weight distribution curve similar to a normal distribution curve. More specifically, in the molecular weight distribution of the polyarylene sulfide as measured by GPC using polystyrene as a standard, the ratio of the peak area of the polymer chain of the second polyarylene sulfide to the peak area of the polymer chain of the first polyarylene sulfide may be 1.2 or less, and more preferably 1.1 or less.

In this regard, the polymer chains of the first polyarylene sulfide have a molecular weight of 12,000 to 900,000, and the polymer chains of the second polyarylene sulfide have a molecular weight of 330 to 80,000.

Such polyarylene sulfide may have a number average molecular weight of 3,000 to 100,000 and a maximum peak molecular weight of 12,000 to 60,000. The number average molecular weight may also preferably be 3,000 to 100,000, more preferably 3,000 to 50,000, and most preferably 5,000 to 30,000.

In addition, the polyarylene sulfide may have a polydispersity index of 2.0 to 4.0, which is defined as a ratio of a weight average molecular weight to a number average molecular weight, which represents a relatively uniform distribution.

The polyarylene sulfide having the above number average molecular weight and/or polydispersity index may be applied to various products according to the molecular weight or melt viscosity.

Meanwhile, the polyarylene sulfide according to the above embodiment exhibits excellent thermal stability, and its melting point (Tm) is preferably 265 to 320 ℃, more preferably 268 to 290 ℃, and even more preferably 270 to 285 ℃. Due to the high melting point (Tm), the polyarylene sulfide of the present invention exhibits excellent properties such as high strength and enhanced heat resistance when used as an engineering plastic.

In addition, the polyarylene sulfide according to the above embodiment exhibits excellent flowability. Specifically, when the polyarylene sulfide according to the above embodiment is melted in an injection machine and then at 1500kgf/cm²Maximum injection pressure of (3), injection volume of 20ml, respective injection speeds of 30mm/s, 30mm/s and 25mm/s, 1450kgf/cm²Has a length of 40cm or more and thus exhibits excellent flowability when injected in the injection machine under the conditions of injection pressure of 320 c and injection temperature, the injection-molded product having a spiral mold having a longitudinal section with a semicircular flow path having a diameter of 6mm and a maximum height of 2.6mm and a cross section with a spiral flow path having a length of 150 mm. The injection molded product may have a length of 50cm or more, and more preferably 60cm or more. Therefore, it is advantageous in that an additional molding process can be easily performed due to appropriate fluidity.

Meanwhile, some resins having excellent flowability may generate a large amount of burrs, which requires an additional method of removing the generated burrs. Therefore, the molding method becomes complicated, and burrs are generated which may cause molding defects of the product. The polyarylene sulfide according to the above embodiment of the present invention shows a burr generation weight ratio, defined as an amount of generated burrs to a weight of an injection molded product injected in the above screw injection machine, of 1% by weight or less, and thus almost no burrs are generated.

The polyarylene sulfide does not generate burrs (burrs) during molding of computer parts or electronic products requiring high precision, and thus it can be used for molding products requiring high precision.

In the polyarylene sulfide according to the above embodiment, the amount of the disulfide repeating unit included in the polymer may be 3% by weight or less based on the total weight of the polyarylene sulfide.

This generation can be attributed to exchange reactions of sulfur-containing compounds additionally injected during the polymerization.

In another aspect, another embodiment of the present invention provides a method for preparing polyarylene sulfide, including the steps of: polymerizing reactants including a diiodo aromatic compound and a sulfur compound, and further adding 0.01 to 30 parts by weight of the sulfur compound based on 100 parts by weight of the sulfur compound included in the reactants while maintaining the polymerization step.

In the above-mentioned production method, further addition of a trace amount of a sulfur-containing compound during the reaction may result in formation of disulfide bonds in the polymer. The disulfide bond continuously causes an equilibrium reaction with the polymer chains included in the polyarylene sulfide, a sulfur exchange reaction to equalize the molecular weights of the polymer chains included in the polyarylene sulfide. In particular, the equilibration reaction, the sulfur exchange reaction, may equalize the degree of polymerization of all reactants and thus prevent the formation of polyarylene sulfide polymer chains having excessively high or excessively low molecular weights. Therefore, polyarylene sulfide having the above molecular weight distribution can be prepared.

The amount of the sulfur compound further added during the polymerization step may be within the above range, and is preferably 0.1 to 20 parts by weight, and more preferably 1.0 to 15 parts by weight, based on 100 parts by weight of the sulfur compound included in the initial reactants.

The time for further adding the sulfur compound during the polymerization is not limited as long as the polymerization proceeds. Preferably, when the polymerization is carried out by 50 to 99%, a sulfur compound may be further added. Meanwhile, the phrase "when polymerization is performed by 50 to 99% is defined as" when 50 to 99% by weight of diiodo aromatic compound of reactants is reacted and consumed "throughout the present specification unless otherwise specified. If the addition is performed at that time, the molecular weight distribution of the polyarylene sulfide may be close to the normal distribution, and more particularly, in the molecular weight distribution of the polyarylene sulfide as measured by gel permeation chromatography using polystyrene as a standard, the ratio of the peak area of the polymer chain of the second polyarylene sulfide having a molecular weight lower than the maximum peak molecular weight to the peak area of the polymer chain of the first polyarylene sulfide having a molecular weight higher than the maximum peak molecular weight is 1.3 or less. In addition, the step of further adding the sulfur compound may be carried out once or, as the case may be, once or more, that is, in a plurality of steps during the polymerization. In this case, the total amount of the sulfur compound added in the plurality of steps may preferably be 0.01 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, and even more preferably 1.0 to 15 parts by weight, based on 100 parts by weight of the sulfur compound included in the reactants.

Meanwhile, in the step of further adding the sulfur compound in the preparation method, a polymerization terminator may be additionally added together with the sulfur compound, and the content of the added polymerization terminator may preferably be 0.01 to 10 parts by weight based on 100 parts by weight of the diiodo aromatic compound. If the content of the polymerization terminator is less than 0.01 parts by weight, the added polymerization terminator has little effect. If the content of the polymerization terminator is more than 10 parts by weight, it is possible to prepare polyarylene sulfide having excessively low molecular weight.

In this regard, the composition of the polymerization terminator is not particularly limited as long as it is capable of terminating the polymerization by removing iodine groups included in the polymer to be polymerized. Preferably, the polymerization terminator may be one or more selected from the group consisting of: diphenyl sulfide, diphenyl ether, biphenyl, benzophenone, diphenyl sulfide, phenylene ether, biphenyl, benzophenone, monoiodo aryl compound, benzothiazole sulfenamide, thiuram, dithiocarbamate and diphenyl disulfide. More preferably, the polymerization terminator may be one or more selected from the group consisting of: iodobiphenyl, iodophenol, iodoaniline, iodobenzophenone, 2-mercaptobenzothiazole, 2' -dithiobisbenzothiazole, N-cyclohexylbenzothiazole-2-sulfenamide, 2-morpholinothiabenzothiazole, N-dicyclohexyl-2-benzothiazolesulfenamide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate and diphenyldisulfide.

Increasingly preferably, the polymerization terminator may be diphenyl sulfide, diphenyl ether or biphenyl, and the functional group between the phenyl groups of these polymerization terminators functions as an electron donor to improve polymerization reactivity.

If the step of further adding the sulfur compound during the polymerization step is carried out one or more times, the polymerization terminator may be added once in the first addition step of the sulfur compound and, as the case may be, at each of the steps of further adding the sulfur compound.

The diiodo aromatic compound useful for the above polymerization of polyarylene sulfide may be one or more selected from the group consisting of: diiodobenzene (DIB), diiodonaphthalene, diiodobiphenyl, diiodobisphenol and diiodobenzophenone, but is not limited thereto. The diiodo aromatic compound may also be any of these diiodo aromatic compounds having an alkyl or sulfone substituent, or an aryl compound containing an oxygen or nitrogen atom. Depending on the position of the iodine substituent, diiodo aromatic compounds can uniquely form different kinds of isomers of diiodo compounds. The most preferred isomers of diiodo compounds are those having iodine substituents symmetrically located at the longest distance from each other on both ends of the molecule, such as pDIB, 2, 6-diiodonaphthalene or p, p' -diiodobiphenyl.

Useful sulfur-containing compounds are not particularly limited in their form. Generally, the sulfur is present as a ring octasulfide (S8) in the form of a ring consisting of 8 sulfur atoms. However, the sulfur-containing compound may be any kind of solid sulfur commercially available.

The diiodo aromatic compound may be added in an amount of 0.9 mole or more relative to the sulfur-containing compound. The content of the sulfur compound is preferably 15 to 30% by weight relative to the weight of the polyarylene sulfide prepared by polymerization of the diiodo aromatic compound and the sulfur compound. The sulfur compound content within the above range ultimately produces polyarylene sulfide having enhanced heat resistance and chemical resistance as well as excellent characteristics in terms of physical strength.

The conditions of the polymerization reaction are not limited as long as the reactants including the diiodo aromatic compound, the sulfur compound and the polymerization terminator are capable of initiating polymerization under these conditions. Preferably, the polymerization reaction can be initiated under conditions of elevated temperature and reduced pressure. In this case, the temperature and pressure conditions are controlled to allow the polymerization reaction to be under initial reaction conditions of a temperature of 180 to 250 ℃ and a pressure of 50 to 450 torr, and then under final reaction conditions of an elevated temperature of 270 to 350 ℃ and a reduced pressure of 0.001 to 20 for 1 to 30 hours.

When the polymerization reaction is carried out under conditions of elevated temperature and reduced pressure, the product is excellent in terms of thermal stability, and when remelted for recovery, the rate of change in melt viscosity, defined as the change in melt viscosity after heat treatment relative to the initial melt viscosity of the resin, is 0 or higher, and thus the mechanical properties are equal to or higher than those before recovery.

The method for preparing polyarylene sulfide according to the above embodiment may further include the step of melt-mixing the diiodo aromatic compound, the sulfur compound and the polymerization terminator before the polymerization step. The above polymerization step is a melt polymerization step carried out in the absence of an organic solvent. For melt polymerization, reactants including diiodo aromatic compounds are melt-mixed in advance and then polymerized.

Although the melt mixing conditions are not limited as long as all of the above reactants can be melt mixed under these conditions, it is preferably at a temperature of 160 to 400 ℃, more preferably 170 to 350 ℃ and most preferably 250 to 320 ℃.

By performing the melt mixing step prior to polymerization, melt polymerization can be more easily performed.

In the method of preparing polyarylene sulfide according to the above embodiment, polymerization may be performed in the presence of a nitrobenzene catalyst. When the melt mixing step is performed prior to the polymerization reaction, the catalyst may be added in the melt mixing step. In the polymerization reaction, it was found that polyarylene sulfide polymerized in the presence of a nitrobenzene-based catalyst has a higher melting point than polyarylene sulfide polymerized in the absence of a catalyst. When polyarylene sulfide having a low melting point is used, the product has a problem in heat resistance. Therefore, for the preparation of polyarylene sulfide having good heat resistance, the polymerization reaction may be performed in the presence of a nitrobenzene-based catalyst. The nitrobenzene-based catalyst can be exemplified by, but not limited to, 1, 3-diiodo-4-nitrobenzene, 1-iodo-4-nitrobenzene, and the like.

In the polyarylene sulfide prepared by the above method, in a molecular weight distribution of the polyarylene sulfide as measured by GPC using polystyrene as a standard, a ratio of a peak area of a polymer chain of the second polyarylene sulfide having a molecular weight lower than the maximum peak molecular weight to a peak area of a polymer chain of the first polyarylene sulfide having a molecular weight higher than the maximum peak molecular weight is 1.3 or less.

In addition, the content difference of the polymer chains of the first and second polyarylene sulfides, the maximum peak molecular weight, the molecular weights of the polymer chains of the first and second polyarylene sulfides, the number average molecular weight, the polydispersity index defined as the ratio of the weight average molecular weight to the number average molecular weight, and the melting point of the polyarylene sulfide prepared by the above-described method are the same as those mentioned in the above-described embodiments.

Meanwhile, still another embodiment of the present invention provides a product manufactured by molding polyarylene sulfide.

The product may be a molded article, film, sheet or fabric. In particular, if the product is a molded article, it may be a molded article for a connector, an electronic molded article, a material for covering an electrical micro-wire, an ultra-thin film molded article, or the like, which requires high molding accuracy.

The polyarylene sulfide of the present invention may be processed into any kind of molded article by injection molding or extrusion molding. Examples of the molded product may include an injection molded product, an extrusion molded product, or a blow molded product.

With respect to injection molding, in terms of crystallization, the molding temperature is preferably 30 ℃ or higher, more preferably 60 ℃ or higher, and even more preferably 80 ℃ or higher; and preferably 150 c or less, more preferably 140 c or less, and even more preferably 130 c or less in terms of deformation of the test substance. These molded articles are useful for electric/electronic parts, building parts, automobile parts, mechanical parts, daily goods, and the like.

The film or sheet may be prepared in the form of any kind of film, for example, a non-oriented film, a uniaxially or biaxially oriented film or sheet. The fabric may be prepared in any kind of fabric form, such as non-oriented, oriented or super-oriented fabric, and may be used as a woven, knitted, non-woven (spunbond, meltblown or cotton), rope, net or the like.

Advantageous effects of the invention

The present invention provides a polyarylene sulfide (PAS) which exhibits excellent processability and does not generate burrs or the like, and can satisfactorily mold a product requiring high molding accuracy, and a molded article using the same.

Brief Description of Drawings

FIG. 1 shows a molecular weight distribution curve of polyarylene sulfide according to example 4; and

FIG. 2 shows a molecular weight distribution curve of polyarylene sulfide according to example 7.

Details of the practice of the invention

The present invention will be described in more detail with reference to the following examples. However, these examples are for illustrative purposes only, and the present invention is not intended to be limited by these examples. Herein, the polyarylene sulfide is described as "PAS".

[ example ] PAS polymerization

1. PAS polymerization of example 1

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Four hours after the start of the polymerization, 0.5g of sulfur was added and the polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had an m.v. of 914 poise and a Tm of 281 ℃.

2. PAS polymerization of example 2

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. 4 hours after the start of the polymerization, 0.5g of sulfur was added and 5 hours after the start of the polymerization, 0.5g of sulfur was further added. Then, polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had an m.v. of 751 poise and a Tm of 282 ℃.

3. PAS polymerization of example 3

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Four hours after the start of the polymerization, 0.5g of sulfur was added and 5 hours after the start of the polymerization, 0.5g of sulfur was further added, and then 6 hours after the start of the polymerization, 0.5g of sulfur was further added. Then, polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had an m.v. of 1465 poise and a Tm of 281 ℃.

4. PAS polymerization of example 4

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Five hours after the start of the polymerization, 0.5g of sulfur was added and the polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had an m.v. of 1659 poise and a Tm of 281 ℃.

5. PAS polymerization of example 5

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Five hours after the start of the polymerization, 0.5g of sulfur was added and 6 hours after the start of the polymerization, 0.5g of sulfur was further added. Then, polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had a m.v. of 2660 poise and a Tm of 280 ℃.

6. PAS polymerization of example 6

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Five hours after the start of the polymerization, 0.5g of sulfur was added and 6 hours after the start of the polymerization, 0.5g of sulfur was further added, and then 7 hours after the start of the polymerization, 0.5g of sulfur was further added. Then, polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had an m.v. of 2473 poise and a Tm of 281 ℃.

7. PAS polymerization of example 7

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Six hours after the start of the polymerization, 0.5g of sulfur was added and the polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had an m.v. of 1610 poise and a Tm of 281 ℃.

8. PAS polymerization of example 8

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Six hours after the start of the polymerization, 0.5g of sulfur was added and 7 hours after the start of the polymerization, 0.5g of sulfur was further added. Then, polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had a m.v. of 2530 poise and a Tm of 280 ℃.

9. PAS polymerization of example 9

Reactants comprising 400g of diiodo aromatic compound, p-diiodobenzene, 34g of crystalline sulfur and 1.0g of 1, 3-diiodo-4-nitrobenzene were melt mixed at 180 ℃. The molten mixture is polymerized at an elevated temperature from 180 ℃ to 340 ℃ and a reduced pressure from atmospheric to 10 torr. Six hours after the start of the polymerization, 0.5g of sulfur was added and 7 hours after the start of the polymerization, 0.5g of sulfur was further added, and subsequently 8 hours after the start of the polymerization, 0.5g of sulfur was further added. Then, polymerization was further carried out for 1 hour to obtain a polymer.

The resulting polymer had a m.v. of 2622 poise and a Tm of 280 ℃.

The reactants of the polymerization reaction of the above example and the amounts thereof added, the amounts of the sulfur compound further added during the polymerization, and the addition time are shown in the following table 1. During the polymerization of these examples, a polymerization terminator was added together with sulfur at the first addition of the amount of sulfur shown in Table 1 below.

Comparative example PAS polymerization

1. PAS polymerization of comparative example 1

PAS made from cellophane filaments was prepared. The polymer produced had a melt viscosity of 2103 poise (hereinafter abbreviated as m.v.) and a melting point (hereinafter abbreviated as Tm) of 282 ℃.

2. PAS polymerization of comparative example 2

Prepare PAS from Fortron (0205P4 grade). The polymer prepared had a m.v. of 628 poise and a Tm of 282 ℃.

3. PAS polymerization of comparative example 3

PAS from Deyang was prepared. The polymer prepared had a m.v. of 2443 poise and a Tm of 282 ℃.

Experimental example property measurement of PAS of comparative example and example

1. Molecular weight analysis

The sample to be analyzed was dissolved in 1-chloronaphthalene at a concentration of 1 wt% for 6 hours at 210 deg.c, and then measured at 210 deg.c using polystyrene as a standard. At this time, "Pl gel 220" was used as a molecular weight measuring instrument GPC, an RI detector was used as a detector, and PLgel 5 μm Mixed-D x 3EA was used as a column. The flow rate was 1ml/min and PL Gel was used as a pump. 5ml of solvent and 0.01g of sample were injected for measurement.

2. Calculation of molecular weight distribution

Molecular weight distributions were analyzed by GPC measurement results of examples and comparative examples, and the maximum peak molecular weight, the number average molecular weight, the content of the polymer chain of the first PAS, that is, the peak area of the polymer chain having a higher molecular weight than the maximum peak molecular weight (that is, having a shorter retention time based on the maximum peak point of polyarylene sulfide), and the content of the polymer chain of the second PAS, that is, the peak area of the polymer chain having a lower molecular weight than the maximum peak molecular weight (that is, having a longer retention time based on the maximum peak point of polyarylene sulfide) are shown in table 2 below.

Meanwhile, molecular weight distribution curves of polyarylene sulfide according to example 4 and PAS according to example 7 are shown in fig. 1 and 2, respectively. As shown in FIGS. 1 and 2, the molecular weight distribution curve of the polyarylene sulfide according to these examples is a unimodal distribution curve and is similar to a normal distribution curve. The maximum peaks in fig. 1 and 2 represent values of retention time before correcting molecular weight using polystyrene as a standard.

3. Melt viscosity analysis

In analyzing physical properties of the polymers prepared according to comparative examples and examples, melt viscosity (hereinafter abbreviated as m.v.) was measured at 300 ℃ using a rotary disc viscometer. When measured by frequency sweep, the angular frequency was measured at 0.6 to 500rad/s, and the viscosity at 1.84 was defined as the melt viscosity. These values are shown in table 3.

4. Measurement of melting Point (Tm)

The melting point was measured using a Differential Scanning Calorimeter (DSC) by increasing the temperature from 30 ℃ to 320 ℃ at a rate of 10 ℃/min, then decreasing the temperature to 30 ℃, and then increasing the temperature from 30 ℃ to 320 ℃ again at a rate of 10 ℃/min. The measured values are shown in table 3.

5. Analysis of the wt% of disulfide

A small amount of sample (about 2mg) was burned at 1000 ℃ using AQF (Automatic Quick Furnace) and sulfur gas was captured and ionized using an absorption solution (hydrogen peroxide). Then, sulfur ions were separated from the column by IC (ion chromatography), and a sulfur ion standard (K) was used₂SO4) to quantify the sulfur content. The difference between the measured sulfur content and the theoretical sulfur content was calculated as disulfide, and the results are shown in table 3.

6. Measurement of the flowability of the Polymer (spiral test)

To measure the flowability of the polymerized polymer, a frequently used screw test was carried out. To perform this test, all polymer samples extruded from the polymerization reactor were cut into the form of pellets having a diameter of 1-2 mm and a length of 2-4, and the maximum injection pressure, injection volume, injection speed, injection pressure, and holding pressure inside the syringe (holding pressure) were maintained constant. The injection temperature was fixed at 320 ℃ on a bucket basis. Specifically, polyarylene sulfide according to these examples and comparative examples was melted in a syringe and then at 1500kgf/cm²Maximum injection pressure of (3), injection volume of 20ml, respective injection speeds of 30mm/s, 30mm/s and 25mm/s, 1450kgf/cm²Is injected at an injection pressure of 320 ℃, and an injection temperature of 320 ℃, the injection machine having a spiral mold having a longitudinal section with a semicircular flow path having a diameter of 6mm and a maximum height of 2.6mm, and a cross section with a spiral flow path having a length of 150 mm. Then, the final length of the injection molded product separated from the spiral casting was measured, and the measured values are as shown in table 3. In the following table 3, the final length of the injection-molded product is described as "length of injection-molded product".

7. Measurement of burr generation after production of molded article

Meanwhile, the above spiral test was performed using the polymers of these comparative examples and examples, and the amount of burrs was determined by the weight measured after cutting off a thin portion between the front-side disc and the rear-side disc, in addition to the body shape of the mold used in the spiral test, and is shown in table 3 below.

The amount of burr generation to the weight of the injection-molded product separated from the casting in the screw test was defined as "burr generation weight ratio" shown in table 3 below.

[ Table 1]

^(Note)The time for further addition of S and the time for termination of the reaction were based on the time for initiation of the reaction.

[ Table 2]

[ Table 3]

As shown in tables 2 and 3, in the molecular weight distribution of PAS as measured by GPC using polystyrene as a standard, the ratio of the peak area of the polymer chain of the second PAS to the peak area of the polymer chain of the first PAS in PAS according to the example of the present invention was 1.3 or less, and the injection-molded product had a length of 40cm or more, thereby showing excellent flowability and processability. In addition, no or a slight amount of burrs were generated.

In particular, all PAS of these examples showed a burr generation weight ratio of 1% or less, defined by the amount of burr generation as compared to the weight of the injection molded product in the screw test, indicating enhanced flowability and minimal burr generation.

In contrast, in the PASs of the comparative example, the peak area ratio of the polymer chains of the first and second PASs was 1.4 or more, and the content of the polymer chains having a relatively low molecular weight was too high. Therefore, the length of the injection-molded product is similar to or slightly higher than that of the present invention, but the burr generation amount is much more than 60 times that of the PAS according to the embodiment of the present invention. The results of examples and comparative examples show that the polyarylene sulfide according to the present invention and the preparation method thereof are expected to be widely used for manufacturing precision molded parts requiring high molding accuracy.

Claims (20)

1. A polyarylene sulfide having a number average molecular weight of 3,000 to 100,000, wherein a ratio of a peak area of a polymer chain of a second polyarylene sulfide having a lower molecular weight than a maximum peak molecular weight to a peak area of a polymer chain of a first polyarylene sulfide having a higher molecular weight than the maximum peak molecular weight is 1.3 or less in a molecular weight distribution of the polyarylene sulfide measured by gel permeation chromatography using polystyrene as a standard, and the maximum peak molecular weight is 12,000 to 60,000.

2. The polyarylene sulfide according to claim 1, wherein a ratio of a peak area of a polymer chain of the second polyarylene sulfide to a peak area of a polymer chain of the first polyarylene sulfide is 1.2 or less.

3. The polyarylene sulfide according to claim 1, wherein a ratio of a peak area of a polymer chain of the second polyarylene sulfide to a peak area of a polymer chain of the first polyarylene sulfide is 1.1 or less.

4. The polyarylene sulfide according to claim 1, wherein polymer chains of the first polyarylene sulfide have a molecular weight of 12,000 to 900,000, and polymer chains of the second polyarylene sulfide have a molecular weight of 330 to 80,000.

5. The polyarylene sulfide according to claim 1, wherein a polydispersity index defined as a ratio of a weight average molecular weight to a number average molecular weight is 2.0 to 4.0.

6. The polyarylene sulfide according to claim 1, wherein the melting point is 265 ℃ to 320 ℃.

7. The polyarylene sulfide according to claim 1, wherein the polyarylene sulfide is melted in an injection machine and then at 1500kgf/cm²Maximum injection pressure of (3), injection volume of 20ml, respective injection speeds of 30mm/s and 25mm/s, 1450kgf/cm²Has a length of 40cm or more when injected in the injection machine under the conditions of injection pressure of 320 ℃, injection temperature of 320 ℃, the injection machine having a spiral mold having a longitudinal section with a semicircular flow path having a diameter of 6mm and a maximum height of 2.6mm, and a cross section with a spiral flow path having a length of 150 mm.

8. The polyarylene sulfide according to claim 7, wherein a burr generation weight ratio, which is defined as an amount of burr generation to a weight of the injection-molded product, is 1% by weight or less.

9. The polyarylene sulfide according to claim 1, wherein an amount of disulfide repeating units included in the polyarylene sulfide is 3% by weight or less based on the total weight of polyarylene sulfide.

10. A method of preparing the polyarylene sulfide of claim 1, comprising the steps of:

polymerizing reactants comprising a diiodo aromatic compound and a sulfur-containing compound; and

while maintaining the polymerization step, 0.01 to 30 parts by weight of the sulfur-containing compound based on 100 parts by weight of the sulfur-containing compound included in the reactants is further added.

11. The method of claim 10, wherein the sulfur-containing compound is further added when the polymerization proceeds from 50% to 99%.

12. The method of claim 10, wherein the step of further adding the sulfur-containing compound during the step of polymerizing is performed one or more times.

13. The method according to claim 10, wherein in the step of further adding the sulfur compound, 0.01 to 10 parts by weight of a polymerization terminator based on 100 parts by weight of the diiodo aromatic compound included in the reactant is additionally added together with the sulfur compound.

14. The method of claim 10, wherein the diiodo aromatic compound content in the reactant is 0.9 mole or more relative to the sulfur-containing compound.

15. The method of claim 13, wherein the polymerization terminator is one or more selected from the group consisting of: iodobiphenyl, iodophenol, iodoaniline, iodobenzophenone, 2-mercaptobenzothiazole, 2' -dithiobisbenzothiazole, N-cyclohexylbenzothiazole-2-sulfenamide, 2-morpholinothiabenzothiazole, N-dicyclohexylbenzothiazole-2-sulfenamide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate and diphenyldisulfide.

16. The method of claim 10, wherein the diiodo aromatic compound is one or more selected from the group consisting of: diiodobenzene, diiodonaphthalene, diiodobiphenyl and diiodobenzophenone.

17. The process of claim 10, wherein the polymerization reaction is carried out under initial reaction conditions of a temperature of 180 ℃ to 250 ℃ and a pressure of 50 to 450 torr, followed by a final reaction conditions of an elevated temperature of 270 ℃ to 350 ℃ and a reduced pressure of 0.001 to 20 torr for 1 to 30 hours.

18. The method of claim 10, further comprising the step of melt mixing reactants comprising the diiodo aromatic compound and the sulfur-containing compound prior to the step of polymerizing.

19. The process of claim 10, wherein the polymerization reaction is carried out in the presence of a nitrobenzene-based catalyst.

20. A resin molded product manufactured by molding the polyarylene sulfide according to any one of claims 1 to 9.