JP2007038485A - Continuous molding method for thin-walled molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for obtaining a thin-walled molding having a good appearance and good mechanical properties in good production efficiency. <P>SOLUTION: The continuous molding method for the thin-walled molding includes a process in which a resin composition containing a polyarylene sulfide, after being melt-kneaded in an extruder, is extruded continuously from a molding die, a process for cooling the extruded material so that it can be taken up, and a process in which the cooled material is held for 0.2-5 min in an atmosphere of 130-190°C while its shape is kept to be crystallized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a continuous molding method for thin-walled molded products using a resin composition containing polyarylene sulfide (PAS) as a raw material.

  PAS is a highly crystalline thermoplastic resin with excellent heat resistance, chemical resistance, flame retardancy, rigidity, etc. Generally, PAS molded products are manufactured by injection molding, cutting, etc. ing.

  The injection molding method is suitable for mass production of articles and materials for which injection molding conditions have been fully studied, and the cutting method is the precision of structures and dimensions that are difficult to manufacture by the injection molding method when producing in small quantities. In the case of producing parts, it is suitable for preliminary production of mass production by an injection molding method or trial production in the previous stage.

  However, for example, in the case of thin-walled tube molded products, when molded by the injection molding method, due to the high fluidity characteristic of PAS, resin enters the mating surfaces of the dies, and burrs are generated. There is a problem that the mold life is shortened because it must be injected. Therefore, as a result of such problems, molding thin-walled tubes by injection molding is not suitable for mass production.

For this reason, it is desired to apply the continuous extrusion method to mass-produce thin-walled products that are difficult to achieve by the injection molding method or the cutting method.
Japanese Examined Patent Publication No. 6-55400 Japanese Patent No. 2522683 JP-A-9-39076

  In Patent Document 1, crystallization treatment (heat setting) can be performed at 150 to 260 ° C. for 0.3 to 100 hours with respect to the tubular molded article that has undergone the heating and melt extrusion process, the sizing process, the take-up and cutting processes. It is disclosed. However, since the entire manufacturing time including the crystallization process takes too long, the production efficiency is poor and the demand for mass production cannot be sufficiently met.

  In Patent Document 2, the PAS is extruded from a slit-shaped die, cooled and solidified into a sheet shape, then preheated, and subsequently passed between a heating roll and a pinch roll, continuously pressed in a linear shape, and heat-treated, A method of crystallization is disclosed. However, a cooling and solidifying step is necessary, and the production line is lengthened accordingly, which is not sufficient in terms of manufacturing time and manufacturing cost.

  Patent Document 3 uses an extrusion machine including an extrusion die having a sizing die for cooling and a crystallization die for heating, and extrudes a crystalline resin to form a resin molded body. An extrusion method is disclosed. However, as described in the examples, it is a method for forming a thick product such as a round bar, and is not suitable as a method for manufacturing a thin product.

  The subject of this invention is providing the continuous molding method of a thin molded product which can mass-produce a thin molded product continuously using the resin composition containing PAS which is crystalline resin.

As a means for solving the problems, the present invention
A process of continuously extruding from a molding die after melt-kneading a resin composition containing PAS in an extruder,
A step of cooling the extrudate to a level where it can be taken out, and a step of crystallizing the cooled extrudate by holding it in an atmosphere of 130 to 190 ° C. for 0.2 to 5 minutes while retaining its shape. The present invention provides a continuous molding method for thin molded products.

  The continuous molding method of the present invention is a method in which, as in Patent Document 1, once a molded product is obtained, crystallization treatment is not performed again, but continuous molding is performed by an in-line method. The continuous molding method of the present invention is suitable for production of thin molded products such as sheets, films, and tubes.

  According to the continuous molding method of the present invention, even when a resin composition containing PAS is used as a raw material, it can be crystallized in a short time by an in-line method, so that a thin molded product can be stably mass-produced. be able to.

  Hereinafter, the continuous molding method of the thin molded article of the present invention will be described for each process. In the following, one step can be separated into two or more as necessary, two or more steps can be combined into one, and a known step can be added.

  The first step is a step of continuously extruding from a molding die after melt-kneading a resin composition containing PAS with an extruder.

  A well-known thing can be used for an extrusion molding machine. The melt kneading temperature is a temperature equal to or higher than the melting point of PAS, and the shape of the molding die is selected according to the shape of the target thin molded product.

  The second step is a step of cooling the extruded product to such an extent that it can be taken up. Since the extruded product extruded from the forming die in the first step is in a molten state, it can be taken up by a roll or a sizing die installed after the forming die (the shape of the extruded product is maintained in the subsequent process) Cool to the extent possible).

  If the extrudate is a sheet or film, apply the method of cooling the roll that is extruded first from the forming die, and if the extrudate is a tube, apply the method of cooling the inlet of the sizing die. can do. In the case of a method using a sizing die, the tube is attached to the inner surface of the sizing and inflated by sucking outward with a vacuum pump (that is, by utilizing the pressure difference between the inside and outside of the sizing die). It is preferable to keep the shape.

  In this step, for example, when the temperature of the extruded product immediately after being extruded from the forming die is 300 ° C., it is cooled to about 30 to 150 ° C.

  The third step is a step of crystallizing the extruded product after cooling. In this step, the extruded product is heated and crystallized under predetermined conditions while maintaining the shape during extrusion.

  The heating conditions for crystallization are 130 to 190 ° C. for 0.2 to 5 minutes, preferably 140 to 180 ° C. for 0.4 to 3 minutes.

  When the extrudate is a sheet or film, a method of contacting with a roll heated to a predetermined temperature is applied. When the extrudate is a tube, a method of passing through a sizing die heated to a predetermined temperature is applied. .

  In the third step, the extruded product that has been crystallized is cut into a predetermined length. In addition, you may extend | stretch before and after cutting as needed.

  The thin molded product obtained by the continuous molding method of the present invention is, for example, a sheet or film or a tube, and preferably has a thickness in the range of 10 to 2000 μm, more preferably 50 to 1000 μm, still more preferably. The thing of 100-500 micrometers can be obtained.

  As the resin composition containing PAS used in the continuous molding method of the present invention, the following can be used.

  The PAS contained in the resin composition contains a repeating unit: —Ar—S— (wherein Ar represents an arylene group) as a main structural unit.

  Arylene groups include p-phenylene group, m-phenylene group, o-phenylene group, substituted phenylene group, p, p'-diphenylenesulfone group, p, p'-biphenylene group, p, p'-diphenylene ether. Group, p, p′-diphenylenecarbonyl group, naphthalene group and the like.

  The PAS may be a homopolymer obtained from any one of the above-described monomers, or a copolymer obtained from two or more monomers.

  Examples of the homopolymer include poly p-phenylene sulfide (PPS), and linear PPS is particularly preferable.

  As the copolymer, a copolymer of a structural unit containing a p-phenylene group and a structural unit containing another arylene group (preferably m-phenylene group) can be mentioned, but in terms of moldability, heat resistance, and mechanical properties. Therefore, the proportion of the structural unit containing a p-phenylene group is preferably 60 mol% or more, more preferably 70 mol% or more. The copolymer may be a random bond or a block bond, but a block bond is preferred from the viewpoint of heat resistance and mechanical properties.

The PAS is preferably linear, but may include a branched structure or a crosslinked structure, a modified product having various substituents introduced therein, or a mixture thereof. When PAS is used as a single product or mixed, the melt viscosity is preferably 10 to 1000 Pa · s (a numerical value measured by a test method of ISO 11443 at 310 ° C. and a shear rate of 1000 sec ⁻¹ ). PAS is preferably deionized after polymerization to reduce the content of alkali metals such as chlorine and sodium to a certain limit or less (500 ppm or less for chlorine and 200 ppm or less for alkali metal).

  Examples of mixing two or more types of PAS to obtain physical properties according to the purpose include those with different viscosities from the viewpoint of improving fluidity, and viewpoints of improving moldability (improving productivity) In addition, a mixture of linear PAS and PAS having a branched or crosslinked structure (melt viscosity is 50 to 500 Pa · s; numerical value measured by the above method) can be given.

  If necessary, the resin composition can be blended with an amount and type of thermoplasticity within a range that can solve the problems of the present invention. Such a thermoplastic resin preferably has a melting point lower than that of PAS, and is an olefin polymer or copolymer mainly composed of polyolefin such as polyethylene, polypropylene or a modified polymer thereof; nylon 6, nylon 66, other Polyamide polymer or copolymer; Polyester polymer or copolymer mainly composed of polyethylene terephthalate, polybutylene terephthalate, etc .; Liquid crystalline polyester polymer; Styrene polymer such as polystyrene, polyacrylonitrile, ABS; Polyalkyl acrylate And acrylic polymers such as polycarbonate, polyphenylene oxide, polyacetal and the like. Two or more of these thermoplastic resins can be used.

  The resin composition may contain one or more selected from granular, fibrous or flaky (plate-like) fillers according to the properties required for the thin molded article.

  Examples of the fibrous filler include glass fiber, carbon fiber, silica fiber, silica / alumina fiber, zirconium fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, copper, Examples thereof include fibers such as brass, and among these, glass fibers and carbon fibers are preferable.

  The fibrous filler preferably has an average fiber length of 1 to 800 μm, more preferably 5 to 600 μm. When the product within the above range is used, the dimensional stability of the thin molded product is improved and the appearance is also improved. The average fiber length is determined by a counting method (a method of observing with a scanning electron microscope and measuring the size of the filler).

  Granular fillers include carbon black, graphite, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, iron oxide, titanium oxide Metal oxides such as alumina, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, silicon carbide, silicon nitride, boron nitride, various metal powders Etc.

  The granular filler preferably has an average particle diameter of 1 to 800 μm, more preferably 5 to 600 μm. When the product within the above range is used, the dimensional stability of the thin molded product is improved and the appearance is also improved. The average particle diameter is determined by a counting method (a method of observing with a scanning electron microscope and measuring the size of the filler).

  Examples of the flaky filler include mica, glass flakes and various metal foils.

  The flaky filler preferably has an average maximum length of 1 to 800 μm, more preferably 5 to 600 μm. When the product within the above range is used, the dimensional stability of the thin molded product is improved and the appearance is also improved. The average maximum length is obtained by a counting method (a method of observing with a scanning electron microscope and measuring the size of the filler).

  As necessary, these fillers may be prepared by adhering hypophosphorous acid or a salt thereof to the surface, or may be converged by using a sizing agent. Compounds, isocyanate compounds, silane compounds, titanate compounds) that have been surface-treated may be used.

  1-200 mass parts is preferable with respect to 100 mass parts of polyarylene sulfide, as for the compounding quantity of these fillers, 5-100 mass parts is more preferable, and 10-50 mass parts is still more preferable.

  In addition to the filler, an organic filler can be supplementarily blended as necessary. As the organic filler, a high melting point fibrous or powdery polymer such as fluororesin and aromatic polyamide can be used.

  In the resin composition, various additives such as pigments, ultraviolet absorbers, antioxidants, heat stabilizers, lubricants, flame retardants, mold release agents, and other known additives are used depending on the use of the thin molded product. An agent can be blended.

  The thin-walled molded product obtained by applying the continuous molding method of the present invention can be used for applications that require heat resistance, chemical resistance, and flame retardancy.

Examples 1-5
In Table 1, when linear PPS resin, carbon black, silica, and potassium titanate fiber are used in combination, the mixture is preliminarily mixed for 5 minutes in a ratio shown in Table 1, and then the cylinder diameter is 45 mm. Using a twin screw extruder (with a vent) manufactured, melt extrusion at a cylinder temperature of 320 ° C. and a screw rotation speed of 250 rpm was made into pellets.

  Next, a spider die was attached to a VS40-25 type extruder manufactured by Ikegai Co., Ltd., and the PPS resin composition was melt extruded into a tube shape while the cylinder temperature was raised to 270 to 310 ° C. In Examples other than Example 1, a PPS resin composition was prepared by dry blending Fortron 0220A9 and the above pellets in advance.

  The extrudate is sent to a sizing die (having a water-cooled cooling device at the inlet), the extrudate is cooled to about 30 to 150 ° C., and then heated under the conditions shown in Table 1, The treatment was performed. In addition, in the inside of the sizing die, the tube was attached to the inner surface of the sizing and inflated by sucking outward with a vacuum pump, and the shape was retained. After the crystallization treatment, the tube was cut into an appropriate length to obtain a tube-shaped thin molded product.

Comparative Example 1
A tube-shaped thin molded article was obtained in the same manner as in Examples 1 to 5, except that the sizing die was passed without heating.

Comparative Example 2
A tube-shaped thin molded article was obtained in the same manner as in Examples 1 to 5, except that a water-cooled sizing die (not heated) was passed.

Comparative Examples 3 and 4
A tube-shaped thin molded article was obtained in the same manner as in Examples 1 to 5 except that the crystallization treatment was performed under the conditions shown in Table 1.

Comparative Example 5
The tube-shaped thin molded product obtained in Comparative Example 2 was subjected to crystallization treatment at 150 ° C. for 10 minutes.

(Extrudability and appearance)
After extruding from the extruder, it was judged whether or not the take-up could be performed smoothly. The appearance was determined by visually observing the appearance of the molded product, and the appearance was smooth and free from wrinkles and holes.

(Confirmation of crystallization)
Using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation, the temperature was raised by 10 ° C. per minute from 20 ° C. to 150 ° C., and the presence or absence of a crystallization peak was confirmed.
○: Crystallization is progressing (no crystallization peak appears).
X: Crystallization has not progressed (crystallization peak appears).

(Measurement of heat resistance)
When the thin-walled molded product is placed in an oven at 130 ° C. and left for 10 minutes with no load, heat resistance is good (○) when deformation cannot be confirmed visually, and heat resistance when deformation is confirmed visually. The property was poor (x).

Details of each component shown in Table 1 are as follows.
・ Fortron 0220A9: PPS, manufactured by Polyplastics Co., Ltd., viscosity 500 Pa · s
・ Linear PPS resin: Polyplastics Co., Ltd., viscosity 50 Pa · s
Glass fiber: trade name REF-160, manufactured by Nippon Sheet Glass Co., Ltd., average fiber length 160 μm
Silica :: trade name Microid ML-369, manufactured by Toyo Seikan Chemical Co., Ltd., average particle size 5.0 μm
-Potassium titanate fiber: Trade name Tismo N, manufactured by Otsuka Chemical Co., Ltd., average fiber length of 15 μm

  In Examples 1 to 5, extrusion moldability and appearance were good, sufficient crystallization treatment was performed, and heat resistance or mechanical properties were also good. In addition, take-off property was inferior that thickness was outside the range of the lower limit and upper limit of 10-2000 micrometers.

  In Comparative Example 1, since cooling and crystallization treatment were not performed, it was difficult to pick up and the product appearance was poor. In Comparative Example 2, although cooled, the heat resistance or mechanical properties were inferior because the crystallization treatment was not sufficiently performed.

  In Comparative Example 3, since the temperature of the crystallization treatment was too high, it was difficult to take up and crystallization was not possible. In Comparative Example 4, since the time for the crystallization treatment was too short, the take-up property and the product appearance were good, but since the crystallization treatment was not sufficiently performed, the heat resistance or mechanical properties were inferior.

In Comparative Example 5, although the heat resistance or mechanical properties of the product were good, the crystallization treatment was performed by outline, so that the production efficiency was poor.

Claims (4)

A step of continuously extruding from a molding die after melt-kneading a resin composition containing polyarylene sulfide in an extruder,
A step of cooling the extrudate to a level where it can be taken out, and a step of crystallizing the cooled extrudate by holding it in an atmosphere of 130 to 190 ° C. for 0.2 to 5 minutes while retaining its shape. , Continuous molding method for thin molded products.   The resin composition containing polyarylene sulfide is polyarylene sulfide, a fibrous filler having an average fiber length of 1 to 800 μm, a granular filler having an average particle diameter of 1 to 800 μm, and an average maximum length of 1 to 800 μm. The method for continuously forming a thin-walled molded article according to claim 1, comprising a material selected from flaky fillers.   The method for continuously forming a thin molded article according to claim 1 or 2, wherein the content of the granular filler, the fibrous filler, or the flaky filler is 1 to 200 parts by mass with respect to 100 parts by mass of the polyarylene sulfide. The method for continuously forming a thin molded product according to any one of claims 1 to 3, wherein the thickness of the thin molded product is 10 to 2000 µm.