JPH07314520A - Thick extrusion molding and production therefor - Google Patents

Abstract

PURPOSE:To enhance the moldability of an extrusion molded item having specified thickness by employing polyphenylene sulfide having specified crystallization temperature, melt viscosity, and shearing rate dependency thereof. CONSTITUTION:An item having thickness of 10mm or above is extrusion molded of polyphenylene sulfide or a composition thereof wherein the ratio of melt viscosities (shearing rate dependency of melt viscosity) for the shearing rate of 200/sec and 1200/sec at 310 deg.C is 2.2-3.0, the melt viscosity for the shearing rate of 1200/sec at 310 deg.C is 500-2000Pa.s, and the crystallization temperature is 160-205 deg.C. The polyphenylene sulfide is a homopolymer or a copolymer containing phenylene sulfide as a principal compositional unit by 50wt.% or more, preferably 70wt.% or more, in the repeating unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded thick-walled molded product made of polyphenylene sulfide and a process for producing the same.

[Prior art]

Polyphenylene sulfide is a highly crystalline thermoplastic resin excellent in heat resistance, chemical resistance, flame retardancy, rigidity and the like. Polyphenylene sulfide molded products are manufactured by injection molding method, cutting method, etc. Among them, the injection molding method is suitable for mass production of articles and materials for which injection molding conditions have been sufficiently examined. There is. On the other hand, when the cutting method is used for small-scale production, when manufacturing precision articles with a specific structure or specific dimensions that are difficult to manufacture by injection molding, or for trial production in the preliminary or previous stage of mass production by injection molding. For example, the round bar or flat plate molding for cutting is obtained by the extrusion molding method.

However, when a round bar or flat plate extruded product having a wall thickness of 10 mm or more is produced, there is a problem that many fine cracks and voids occur in the center of many round bar or flat plate molded products. . With such a defect in the center,
There is a risk of producing a machined product containing this defect, and minute cracks in the center gradually develop toward the surface of the round bar or flat plate molded product during storage or transportation of the round bar or flat plate molded product. There are problems such as cases.

Therefore, in order to overcome the drawbacks of the extrusion moldability of polyphenylene sulfide and the physical properties of the extruded product, various molding methods have been studied. For example, Japanese Patent Application Laid-Open No. 52-11256 proposes to solve the above-mentioned problems by applying a back pressure from the outside of the die to perform extrusion molding.

Further, in JP-A-64-8028, a core made of a heat-resistant material is supplied to a crosshead of an extruder, polyphenylene sulfide is extrusion-coated on the core, and after cooling, the core is extracted and cracked. It is disclosed that a machined product made of hollow polyphenylene sulfide having no voids can be produced.

However, none of these known methods is complicated in molding work and inferior in productivity, and does not improve melt extrusion moldability of polyphenylene sulfide itself or physical properties of a molded product.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is to form a polyphenylene sulfide of 10 mm, which has few cracks and voids inside the molded article, has excellent strength characteristics such as impact strength and bending strength, and has excellent melt extrusion moldability. An object of the present invention is to provide an extruded wall thickness molded product having the above wall thickness and a method for producing the same.

[0008]

Means for Solving the Problems The present invention has been earnestly studied to solve the problems of the prior art, and as a result, by using polyphenylene sulfide which specifies shear rate dependence of melt viscosity, crystallization temperature and melt viscosity. Excellent in molding processability of thick-walled extrudates having a wall thickness of 10 mm or more,
At the same time, it is based on the finding that a molded product having few cracks and voids inside and improved strength characteristics such as impact strength can be obtained.

Thus, according to the invention, a melt viscosity at 310 ° C. and a shear rate of 200 / sec of 310 ° C. and a shear rate of 1
The ratio to the melt viscosity at 200 / sec (hereinafter, this ratio is referred to as "shear rate dependence of melt viscosity") is 2.2 to 3.
0, 310 ° C., melt viscosity at shear rate of 1200 / sec of 500 to 2000 Pa · s, crystallization temperature of 160 to
An extruded thick-walled molded article having a wall thickness of 10 mm or more, which is made of polyphenylene sulfide at 205 ° C. or a composition thereof, is provided.

Further, the ratio of the melt viscosity at 310 ° C. and the shear rate of 200 / sec to the melt viscosity at 310 ° C. and the shear rate of 1200 / sec is 2.2 to 3.0, and 310 ° C. and the shear rate of 1200. / Sec melt viscosity is 500-2000P
a · s, polyphenylene sulfide having a crystallization temperature of 160 to 205 ° C. or a composition thereof is once melted to a melting point or higher, then lowered to below the melting point in a die, and then extrusion molded to obtain a wall thickness of 10 mm or more. A method for producing an extruded thick-walled molded article is provided. Hereinafter, the present invention will be described in detail.

The polyphenylene sulfide used in the present invention contains phenylene sulfide as a main constitutional unit of a polymer in an amount of 50% by mass or more, preferably 7% by weight in a repeating unit.
It is a homopolymer or a copolymer containing 0% by mass or more. The polyphenylene sulfide used in the present invention has a shear viscosity dependence of melt viscosity of 2.2 to 3.0, preferably 2.25 to 2.9. If the melt viscosity has a shear rate dependency of less than 2.2, elasticity during melt extrusion is insufficient, die swell is reduced, shape retention is poor, and moldability is poor. On the other hand, if the shear viscosity dependence of the melt viscosity exceeds 3.0, the elasticity at the time of melting becomes too large, the die swell becomes large, and the dimensional accuracy of the molded product decreases, which is not preferable.

The polyphenylene sulfide used in the present invention has a crystallization temperature of 160 to 205 ° C., preferably 165 to 200 ° C. Here, the crystallization temperature means that polyphenylene sulfide is used under a nitrogen stream for 3
Amorphous sheet 10 mg prepared by preheating at 20 ° C. for 2 minutes, pressurizing for 1 minute, and then rapidly cooling was used, and a differential scanning calorimeter (DSC) (using "DSC-30" manufactured by METTLER CORPORATION) was used for nitrogen flow. It is the exothermic peak temperature that appears on the chart when cooled at a cooling rate of 10 ° C / min from 340 ° C in the middle. If the crystallization temperature exceeds 205 ° C., the rate of crystallization and solidification in the cooling process after flowing out from the die becomes too high during melt extrusion molding, and a large number of fine particles are formed inside the molded product having a wall thickness of 10 mm or more. This is because cracks and voids are generated undesirably. On the other hand, if the crystallization temperature is lower than 160 ° C., only the crystallinity of which is lowered can be obtained, and the product is deformed during the heat treatment after molding, and a molded product having an excellent appearance cannot be obtained.

The polyphenylene sulfide used in the present invention has a melt viscosity of 500 to 2000 Pa · s, preferably 6 when measured at 310 ° C. and a shear rate of 1200 / sec.
00 to 1900 Pa · s, more preferably 700 to 18
00 Pa · s is used. Melt viscosity is L / D = 10mm / 1m by Capirograph (manufactured by Toyo Seiki Co., Ltd.)
It is obtained using the m nozzle. Melt viscosity is 50
This is because if it is less than 0 Pa · s, sufficient impact resistance and strength characteristics of the molded product cannot be obtained. On the other hand, 2000 Pa · s
This is because if it exceeds the range, the fluidity is small and the melt moldability is deteriorated, which is not preferable. The polyphenylene sulfide satisfying the above-mentioned various conditions is disclosed in, for example, Japanese Patent Publication No. 57-334, and has at least 1 halogen-substituted group of 3 or more per molecule.
Japanese Patent Publication No. 63-337 using various polyhaloaromatic compounds
It can be produced by the method described in Japanese Patent Publication No. 75, etc.

If desired, the molded product of the present invention may contain various optional components other than polyphenylene sulfide that can be mixed. An example thereof is an inorganic filler.
Examples of the inorganic filler include silica, alumina, talc, mica, kaolin, clay, silica-alumina, titanium oxide, calcium carbonate, calcium silicate, calcium phosphate, calcium sulfate, magnesium carbonate, magnesium oxide, magnesium phosphate, silicon nitride, Glass,
Granular, powdery or scaly ones such as hydrotalcite and zirconium oxide, or fibrous ones such as glass fibers, potassium titanate fibers, carbon fibers and mica ceramic fibers can be blended. These inorganic fillers can be used alone or in combination of two or more. Further, these inorganic fillers may be treated with a silane coupling agent or a titanate coupling agent. The mixing ratio of the filler is usually 70% by mass or less from the viewpoint of melt processability.

Another example of the optional component is a thermoplastic resin other than polyphenylene sulfide, which has a melting temperature range of polyphenylene sulfide, usually 200 to 38.
Examples thereof include those that are unlikely to undergo thermal decomposition at 0 ° C.
For example, polyamide, polyetheretherketone, polysulfone, polyethersulfone, polyphenylene ether, polycarbonate, polyalkylene terephthalate, polyolefin, polystyrene, ABS resin, polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene copolymer, etc. alone, Alternatively, two or more kinds can be combined and compounded. The blending ratio of these thermoplastic resins is usually 40% by mass or less in view of heat resistance, corrosion resistance, chemical resistance, flame retardancy and the like.

Further examples of the optional component include various additives such as an antioxidant, a heat stabilizer, a lubricant, a release agent and a coloring agent. The method of mixing the above components is
The method is not particularly limited, and a generally widely used method, for example, a method of mixing each component with a mixer such as a Henschel mixer can be used.

In order to obtain the molded product of the present invention, a method of molding a powder of polyphenylene sulfide and a mixture optionally contained therein by using a melt extrusion molding machine as it is, or after melt-molding the powder into pellets in advance, A method of molding with a melt extruder can be used. In the present invention, when molding with a melt extrusion molding machine, after melting the polyphenylene sulfide once above the melting point of polyphenylene sulfide in the die, after lowering the melting point of polyphenylene sulfide in the die, then extruded from the die A method of forming a molded product having a wall thickness of 10 mm or more is adopted. In this way, an extruded thick-walled molded product is obtained, which is suitably used for thick-walled round bars, flat plates and the like.

Needless to say, the wall thickness means, for example, the diameter of a round bar, the short diameter of an elliptic cylinder shaped product, and the so-called thickness of a flat plate. In particular, the thickness of 12 mm or more, more preferably 15 mm or more can make the superiority to the prior art clearer. The upper limit of the wall thickness of the molded product is not particularly limited as long as it can be extruded, but it is usually within 1 m, preferably within 50 cm.

[0019]

[Examples] The measurement methods for the physical properties shown in Examples and Comparative Examples and not mentioned above are shown below. [Melting point] Polyphenylene sulfide under nitrogen stream, 3
Amorphous sheet 10 mg prepared by preheating at 20 ° C. for 2 minutes, pressurizing for 1 minute, and then rapidly cooling was used, and a differential scanning calorimeter (DSC) (using "DSC-30" manufactured by METTLER CORPORATION) was used for nitrogen flow. It is the endothermic peak temperature associated with melting that appears on the chart when the temperature is raised at a heating rate of 10 ° C./min.

[Impact strength] The impact strength of the round bar molded product was measured by cutting a test piece measuring 3.2 mm x 12.7 mm x 127 mm from the center of the round bar, and according to ASTM D-256, there was no notch. It was measured at.

[Bending Strength] The bending strength of the round bar molded product was measured according to ASTM D by cutting a test piece having a size of 3.2 mm × 12.7 mm × 127 mm from the center of the round bar.
-790.

Example 1 Hydrous sodium sulfide (water content 5)
372 kg of N-methylpyrrolidone and 827 kg of N-methylpyrrolidone were charged to a polymerization vessel, and 141.4 kg of water was distilled out together with 53.4 mol of hydrogen sulfide while gradually raising the temperature to about 203 ° C. under a nitrogen atmosphere. It was Next, 322.5 kg of p-dichlorobenzene, 0.799 kg of 1,2,4-trichlorobenzene and 246 kg of NMP were added.
Polymerization was carried out at 0 ° C. for 5 hours. Then, 96.7 kg of water was added, the temperature was raised to 255 ° C., polymerization was performed for 5 hours, and then 24 hours was further added.
Polymerization was continued at 5 ° C for 5 hours.

The reaction mixture obtained was opened to 150 μm.
After sieving with a (100 mesh) screen, the granular polymer was separated, washed with methanol three times and washed with water three times respectively, dehydrated and dried to obtain a polymer (melting point: 284 ° C.). Cylinder temperature is 300 ℃ using this polymer
Then, the die temperature was set to 250 ° C. and a round bar molded product having a diameter of 30 mm was extrusion molded. The performance of the round bar is shown in Table 1 together with the polymer properties.

[0024]

[Table 1]

[Example 2] In the same manner as in Example 1, water-containing sodium sulfide and N-methylpyrrolidone were charged into a polymerization vessel and gradually heated to about 203 ° C under a nitrogen atmosphere while 37.9 mol of 140.4 kg of water was distilled off together with hydrogen sulfide. Then p-dichlorobenzene 321.7k
g, 1,2,4-trichlorobenzene (0.797 kg) and N-methylpyrrolidone (255 kg) were mixed to supply 2
Polymerization was carried out at 20 ° C. for 5 hours. Next, 97.4 kg of water was added, the temperature was raised to 255 ° C., polymerization was performed for 5 hours, and then 2 more
The polymerization was continued at 45 ° C for 5 hours. Then, post-treatment was carried out in the same manner as in Example 1 to obtain a polymer (melting point: 283 ° C.).
Using this polymer, a round bar was molded in the same manner as in Example 1. The results are shown in Table 1.

[Example 3] In the same manner as in Example 1, water-containing sodium sulfide and N-methylpyrrolidone were charged into a polymerization vessel, and the temperature was gradually raised to about 203 ° C under nitrogen atmosphere. 143.2 kg of water was distilled off together with hydrogen sulfide. Then p-dichlorobenzene 319.0k
g, 1,2,4-trichlorobenzene (0.808 kg) and N-methylpyrrolidone (243 kg) are mixed to supply 2
Polymerization was carried out at 20 ° C. for 5 hours. Next, water 96.6kg
Was added, the temperature was raised to 255 ° C., polymerization was carried out for 5 hours, and then the polymerization was continued at 245 ° C. for 5 hours. Then, post-treatment was carried out in the same manner as in Example 1 to obtain a polymer (melting point: 283 ° C.). Using this polymer, a round bar was molded in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1] Hydrous sodium sulfide (Na ₂
S.5H ₂ O) 20 mol and N-methylpyrrolidone 1
1.0 kg was charged into a polymerization vessel and gradually heated to about 200 ° C. under a nitrogen atmosphere to distill 1.27 kg of water, 1.57 kg of N-methylpyrrolidone and 0.46 mol of hydrogen sulfide. Next, 19.73 mol of p-dichlorobenzene and 3.2 kg of N-methylpyrrolidone were added and polymerization was carried out at 210 ° C. for 9 hours. Next, water was added to the polymerization system so that the coexisting water of the polymerization system had a water / sodium sulfide molar ratio of 4.7, and polymerization was carried out at 260 ° C. for 5 hours, and then at 245 ° C. for 3 hours.
Polymerized for hours. Then, post-treatment was carried out in the same manner as in Example 1 to obtain a polymer (melting point: 285 ° C.). The properties of the polymer were as shown in Table 1. A round bar was molded using this polymer in the same manner as in Example 1. The performance of the obtained molded product was as shown in Table 1.

[Comparative Example 2] Hydrous sodium sulfide (purity: 4
6.03%) 373 kg and N-methylpyrrolidone 80
Charge 0 kg into a polymerization can, and gradually increase it to about 20 in a nitrogen atmosphere.
An N-methylpyrrolidone solution containing 142 kg of water was distilled off while the temperature was raised to 3 ° C. Next, 318 kg of p-dichlorobenzene and 0.3 of 1,2,4-trichlorobenzene.
A mixed solution of 93 kg and 255 kg of N-methylpyrrolidone was supplied to carry out polymerization at 220 ° C. for 5 hours. Then water 94
After adding kg, heating to 255 ° C. and polymerizing for 5 hours,
Further, the polymerization was continued at 245 ° C. for 5.5 hours. afterwards,
Post-treatment was carried out in the same manner as in Example 1 to give a polymer (melting point: 2
84 ° C.) was obtained. The properties of the polymer were as shown in Table 1. A round bar was molded using this polymer in the same manner as in Example 1. The performance of the obtained molded product was as shown in Table 1.

[Comparative Example 3] Hydrous sodium sulfide (purity: 4
6.4%) 370 kg and N-methylpyrrolidone 800
After charging kg to a polymerization can, gradually increase it to about 203 in a nitrogen atmosphere.
While raising the temperature to 0 ° C., an N-methylpyrrolidone solution containing 144 kg of water was distilled off, 4 kg of water was then added, and then a mixed solution of 320 kg of p-dichlorobenzene and 280 kg of N-methylpyrrolidone was supplied to obtain 220 Polymerization was carried out at ℃ for 4 hours. Further add 110 kg of water, 26
The temperature was raised to 0 ° C. and the polymerization was continued for 5 hours. The obtained reaction mixture is sieved with a screen having an opening of 150 μm (100 mesh) to separate the granular polymer, washed with methanol,
It was washed with water to obtain a polymer slurry. Then 2% by mass
Dipping in ammonium chloride aqueous solution at 40 ℃
After being treated for 30 minutes with water, washed with water and dried to obtain a polymer (melting point: 285 ° C.). The properties of the polymer were as shown in Table 1. A round bar was molded using this polymer in the same manner as in Example 1. Many fine voids were formed in the center of the obtained molded product, and a test piece for measuring impact strength and bending strength could not be obtained.

[0030]

The extruded thick-walled molded product having a wall thickness of 10 mm or more has few cracks and voids, is excellent in impact resistance, strength characteristics and the like, and is also excellent in melt extrusion moldability.
It is particularly suitable for round bars and flat plates.

Claims (10)

[Claims] 1. The ratio of the melt viscosity at 310 ° C. and a shear rate of 200 / sec to the melt viscosity at 310 ° C. and a shear rate of 1200 / sec is 2.2 to 3.0, and at 310 ° C. and a shear rate of 1200. / Sec melt viscosity is 500-2000Pa
An extruded thick-walled molded product having a wall thickness of 10 mm or more, which is made of polyphenylene sulfide having a crystallization temperature of 160 to 205 ° C. or a composition thereof. 2. The extruded wall thickness molded article according to claim 1, which is a round bar for cutting. 3. The extruded wall thickness molded article according to claim 1, wherein the extruded wall thickness molded article is a flat plate molded article. 4. A wall thickness of 12 mm or more.
Extruded wall thickness molded product. 5. The extruded wall thickness molding according to claim 4, which has a wall thickness of 15 mm or more. 6. The ratio of melt viscosity at 310 ° C., shear rate 200 / sec to melt viscosity at 310 ° C., shear rate 1200 / sec is 2.2-3.0, 310 ° C., shear rate 1200. / Sec melt viscosity is 500-2000Pa
s, a polyphenylene sulfide having a crystallization temperature of 160 to 205 ° C. or a composition thereof is once melted to a melting point or higher, then brought to a temperature lower than the melting point in a die, and then extrusion-molded.
A method for producing an extruded thick molded product having a wall thickness of 0 mm or more. 7. The method for producing an extruded thick molded product according to claim 6, wherein the extruded thick molded product is a round bar for cutting. 8. The method for producing an extruded thick wall molded article according to claim 6, wherein the extruded thick wall molded article is a flat plate molded article. 9. The wall thickness of 12 to 12 mm or more.
1. A method for producing an extruded wall thickness molded article. 10. The method for producing an extruded wall thickness molded article according to claim 9, wherein the wall thickness is 15 mm or more.