JP4912620B2 - Polyarylene sulfide resin composition and injection molded article - Google Patents

Description

  The present invention relates to a polyarylene sulfide resin composition capable of providing a polyarylene sulfide resin molded product in which sink generation is suppressed.

  Polyarylene sulfide (hereinafter abbreviated as PAS) resin represented by polyphenylene sulfide (hereinafter abbreviated as PPS) resin has high heat resistance, mechanical properties, chemical resistance, dimensional stability, and flame retardancy. For this reason, it is widely used for electrical / electronic equipment parts materials, automotive equipment parts materials, chemical equipment parts materials, and the like. In general, PAS resin is known as a material having a small molding shrinkage ratio and good dimensional accuracy. However, as the performance and integration of each part such as electric / electronic equipment or automobile equipment increases, The demand for dimensional accuracy is increasing.

  In particular, in molded products having ribs provided to prevent warpage deformation and to reinforce mechanical strength, even the PAS resin with good dimensional accuracy has a sink (on the surface of the molded product). ), The flatness of the molded product is deteriorated. When the flatness is deteriorated, it is not preferable because a slight dullness occurs when assembling a highly integrated small component. In order to manufacture precision parts that require high performance, it is important to improve flatness (sink).

As a conventional method for solving this problem, an attempt is made to improve the molding method or the material surface. As a molding technique, for example, an injection compression molding method or the like is known (for example, Patent Document 1). However, this method cannot be carried out with a conventional injection molding machine as it is, and there is a drawback in that it is difficult to introduce it as a general-purpose technique due to a problem of cost increase such as remodeling. In addition, sink marks derived from the material itself cannot be completely eliminated. On the other hand, from the viewpoint of materials, a method of blending white mica (Patent Document 2) and a method of blending an ethylene ionomer resin and an epoxy resin (Patent Document 3) are known. However, according to the study by the present inventors, these methods have problems such as insufficient sink suppression ability with respect to market demands, or mechanical properties are lowered.
JP 2000-187177 A JP-A-4-72356 JP-A-5-345328

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a PAS resin injection molded product excellent in flatness in which generation of sink marks is suppressed even in a molded product having ribs.

  In light of the above-mentioned problems, the present inventors have intensively studied to obtain a PAS resin injection-molded product excellent in the effect of suppressing the occurrence of sink marks. As a result, the present inventors have a substantially linear shape having a certain amount of Na content and resin pH. When a PAS resin is used and an inorganic filler containing a fibrous reinforcing agent having a flat cross-sectional shape as a main component is blended, the generation of sink marks is suppressed, and a PAS resin composition having high mechanical strength is obtained. As a result, the present invention was completed.

That is, the present invention
(A) with respect to 100 parts by weight of a substantially linear polyarylene sulfide resin having a Na content of 500-1500 ppm and a resin pH of 7.0-12.0,
(B) It has a flat cross-sectional shape in which the ratio of the long axis (longest straight line distance in the cross section) and the short diameter (long straight line and longest straight line distance in the right direction) between 1.3 and 10 is perpendicular to the length direction. A polyarylene sulfide resin composition comprising 10 to 400 parts by weight of an inorganic filler mainly composed of a fibrous reinforcing agent (B-1).

  Hereinafter, the constituent components of the resin material of the present invention will be described in detail. The PAS resin as the component (A) used in the present invention is mainly composed of — (Ar—S) — (wherein Ar is an arylene group) as a repeating unit. Examples of the arylene group include p-phenylene group, m-phenylene group, o-phenylene group, substituted phenylene group, p, p′-diphenylene sulfone group, p, p′-biphenylene group, p, p′-diphenylene. An ether group, p, p′-diphenylenecarbonyl group, naphthalene group and the like can be used. In this case, among the arylene sulfide groups composed of the above-mentioned arylene groups, in addition to a polymer using the same repeating unit, that is, a copolymer containing a different repeating unit from the viewpoint of processability of the composition in addition to a homopolymer. May be preferred.

  As the homopolymer, those having a repeating unit of a p-phenylene sulfide group using a p-phenylene group as an arylene group are particularly preferably used. As the copolymer, among the arylene sulfide groups comprising the above-mentioned arylene groups, two or more different combinations can be used, and among them, a combination containing a p-phenylene sulfide group and an m-phenylene sulfide group is particularly preferably used. It is done. Among these, those containing 70 mol% or more, preferably 80 mol% or more of p-phenylene sulfide groups are suitable from the viewpoint of physical properties such as heat resistance, moldability and mechanical properties.

Further, among these PAS resins, a high molecular weight polymer having a substantially linear structure obtained by condensation polymerization from a monomer mainly composed of a bifunctional halogen aromatic compound can be particularly preferably used. The melt viscosity of the (A) PAS resin is preferably 5 to 500 Pa · s (310 ° C., shear rate 1200 sec ⁻¹ ), particularly preferably 10 to 300 Pa · s.

  An excessively low melt viscosity is not preferable because the mechanical strength is not sufficient. On the other hand, when the melt viscosity exceeds 500 Pa · s, the flowability of the resin composition is poor at the time of injection molding, and the molding operation becomes difficult, which is not preferable.

  The (A) PAS resin used in the present invention is required to have a Na content of 500 to 1500 ppm in the resin. If the Na content is too small, a sufficient sink suppression effect cannot be obtained, and if it is too large, the crystallization speed will be remarkably slow, resulting in a longer molding cycle time in injection molding, which is not preferable for production.

  Further, (A) the pH of the resin in the PAS resin needs to be 7.0 to 12.0. If the pH of the resin is too low, the amount of acidic corrosive gas generated at the time of molding increases, and if it is too high, the crystallization speed is remarkably slow, so the molding cycle time in injection molding becomes longer, which is preferable for production. Absent.

  Such a PAS resin used in the present invention does not depend on the production method as long as the Na content is 500 to 1500 ppm and the pH of the resin is 7.0 to 12.0. The method obtained by the washing | cleaning method demonstrated in (1) is mentioned.

  That is, after the polymerization is completed, the reaction mixture is cooled to near room temperature, the contents are passed through a 100 mesh screen, the particulate polymer is filtered, and then washed 2-4 times with acetone and 4-8 times with ion-exchanged water. The above-mentioned polymer can be obtained by performing. When washing with an organic solvent such as acetone is insufficient, impurities (organic compounds and oligomers) in the polymer increase, which is undesirable in terms of the quality of the PAS resin, and excessive washing with an organic solvent causes an increase in cost. Moreover, if the washing with ion-exchanged water is insufficient, the Na content increases, and conversely, if the washing is excessive, the Na content becomes too small. The water used for washing is preferably ion-exchanged water or distilled water. Use of water with many impurities is not preferable because the pH of the resin does not fall within a predetermined range.

  Next, the fibrous reinforcing agent (B-1) having a flat cross-sectional shape, which is the main component of the inorganic filler (B) used in the present invention, is a general cross-sectional shape having a substantially circular cross section. Unlike a fibrous reinforcing agent, it is a fibrous reinforcing agent characterized by having a flat cross-sectional shape, which is extremely effective for achieving both excellent anti-sinking ability and high mechanical strength. It is.

  (B-1) has a ratio of the long axis (longest straight line distance in the cross section) perpendicular to the length direction to the short diameter (longest straight line distance in the right direction) of 1.3 to 10, preferably 1.5 to 5. In particular, a fibrous reinforcing agent having a flat cross-sectional shape in between is an elliptical shape, an elliptical shape, a semicircular shape, an eyebrows shape, a rectangular shape, or a similar shape thereof. When this (B-1) is used, the shrinkage during molding and the linear expansion coefficient of the molded product are less different from the flow direction and the direction perpendicular to the flow direction (anisotropy). A high molded article can be obtained.

  In addition, the fibrous reinforcing agent (B-1) having a flat cross section has a large specific surface area, improved adhesion between the fiber and the PAS resin, and better mechanical properties such as bending strength and rigidity. Show. From this point, a fibrous reinforcing agent having an eyebrow-shaped cross-sectional shape having a depression at the center is more preferable. When the ratio of the major axis to the minor axis is less than 1.3, there is no effect of suppressing sink, and when the ratio exceeds 10, the production itself is difficult.

Next, as the cross-sectional area of the fibrous reinforcing agent (B-1) having a flat cross-sectional shape used in the present invention becomes large, a sufficient reinforcing effect cannot be obtained. Are difficult to handle, and there are problems in handling. Therefore, the cross-sectional area of the fibrous reinforcing agent in the present invention is 2 × 10 ⁻⁵ to 8 × 10 ⁻³ mm ² , preferably 8 × 10 ⁻⁵ to 8 × 10 ⁻⁴ mm ² .

  Next, the length of the fibrous reinforcing agent (B-1) having a flat cross-sectional shape used in the present invention is arbitrary, but considering the mechanical properties, molding processability, etc. of the molded product, The average fiber length is preferably 50 to 1000 μm. In addition, hollow fibers can be used as the fibrous reinforcing agent (B-1) for the purpose of reducing the specific gravity of the resin composition.

  Examples of such fibrous reinforcing agents (B-1) include glass fibers, carbon fibers, zinc oxide fibers, titanium oxide fibers, wollastonite, asbestos fibers and other mineral fibers, boron fibers, zirconia fibers, silica fibers, silica -Alumina fiber, zirconia fiber, boron nitride fiber, stainless steel fiber, copper fiber, polyamide fiber, high molecular weight polyethylene fiber, aramid fiber, polyester fiber, fluorine fiber, etc. are mentioned, preferably glass fiber is used. In addition, two or more kinds of fibrous reinforcing agents (B-1) can be mixed and used for the purpose of improving mechanical properties, improving slidability, and imparting conductivity.

  In using these fibrous reinforcing agents (B-1), it is desirable to use a sizing agent or a surface treatment agent if necessary. Examples of this are functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds. These compounds may be used after being subjected to surface treatment or convergence treatment in advance, or may be added at the same time as material preparation.

  For example, in the case of glass fiber, the fibrous reinforcing agent (B-1) having such a flat cross section is an appropriate oval, elliptical, rectangular, slit-like or the like as a bushing used for discharging molten glass. It is prepared by spinning using a nozzle having a hole shape. Also prepared by spinning molten glass from a plurality of adjacent nozzles having various cross-sectional shapes (including circular cross-sections), and joining the spun molten glass into a single filament it can. Carbon fibers and the like can also be prepared using the same method.

  Furthermore, the inorganic filler (B) of the present invention is mainly composed of the fibrous reinforcing agent (B-1) having the above-mentioned flat cross-sectional shape, and improves mechanical strength, heat resistance, and dimensional stability. Therefore, a fibrous and / or non-fibrous inorganic filler (B-2) other than the fibrous reinforcing agent (B-1) having a flat cross-sectional shape may be contained. The type of fibrous and / or non-fibrous inorganic filler (B-2) other than (B-1) is not particularly limited, but blending is often preferred in order to obtain sufficient mechanical strength. .

  Here, in (B) the inorganic filler, the main component is the fibrous reinforcing agent (B-1) having a flat cross-sectional shape. In the inorganic filler (B), (B-1) is 50% by weight. This means that it is preferably 55 to 80% by weight.

  As the inorganic filler (B-2), for example, light calcium carbonate, heavy or finely divided calcium carbonate, calcium carbonate such as special calcium-based filler; calcined clay such as nepheline, feldspar fine powder, montmorillonite, bentonite, Clay (aluminum silicate powder) such as silane modified clay; talc; silica (silicon dioxide) powder such as fused silica and crystalline silica; silicic acid-containing compounds such as diatomaceous earth and silica sand; pumice powder, pumice balloon, slate powder, mica powder, etc. Pulverized natural minerals; alumina-containing compounds such as alumina, alumina colloid (alumina sol), alumina white, aluminum sulfate; minerals such as barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, graphite (graphite); glass beads, Glass fillers such as glass flakes and expanded glass beads; Sphere, volcanic glass hollow body, synthetic inorganic hollow body, single crystal potassium titanate, carbon nanotube, carbon hollow sphere, carbon 64 fullerene, anthracite powder, artificial cryolite, titanium oxide, magnesium oxide, basic Examples include magnesium, dolomite, potassium titanate, calcium sulfite, mica, asbestos, calcium silicate, aluminum powder, and molybdenum sulfide.

  Examples of the fibrous inorganic filler include glass fiber, asbestos fiber, carbon fiber, silica fiber, silica / alumina fiber, potassium titanate fiber, boron fiber, carbon fiber, and silicon carbide fiber.

  These inorganic fillers (B-2) may be used as a mixture of two or more thereof for the purpose of improving dimensional accuracy and improving mechanical properties. Of the inorganic fillers (B-2), for the fibrous inorganic fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary, as described above.

  The amount of the component (B) is 10 to 400 parts by weight, preferably 40 to 250 parts by weight, with respect to 100 parts by weight of the PAS resin as the component (A). When the blending amount of the component (B) is too small, the original excellent mechanical strength of the filler-reinforced PAS resin composition cannot be obtained, and when it is too large, there is a problem that processability such as fluidity is lowered.

  In the present invention, (C) a thermoplastic elastomer can be used in combination as appropriate in order to further improve the occurrence of sink marks.

  (C) Examples of thermoplastic elastomers include polyolefin elastomers, polyester elastomers, fluorine elastomers, silicone elastomers, butadiene elastomers, polyamide elastomers, polystyrene elastomers, urethane elastomers, and various types of particles with a cross-linked structure at the center. An elastomer etc. are mentioned and 1 type (s) or 2 or more types can be used.

  (C) The thermoplastic elastomer is preferably a polyolefin-based elastomer, and particularly preferably an olefin-based copolymer mainly composed of an α-olefin and a glycidyl ester of an α, β-unsaturated acid. In addition, polyolefin elastomers obtained by copolymerizing various graft copolymers with a main component composed of an α-olefin and a glycidyl ester of α, β-unsaturated acid are also preferably used.

  (C) The amount of the thermoplastic elastomer is 1 to 25 parts by weight, preferably 1 to 15 parts by weight, more preferably 1 to 8 parts by weight, based on 100 parts by weight of the (A) polyarylene sulfide resin. . If it is less than 1 part by weight, the effect of improving sink generation is not sufficient, and if it exceeds 25 parts by weight, there is a problem that the mold deposit that adheres to the mold during molding increases.

  Further, in the PAS resin composition of the present invention, an amorphous resin (D) having a relatively high heat resistance is added in an amount of 5 to 50 parts by weight per 100 parts by weight of the component (A) for the purpose of further improving sink generation. Partial blending can also be performed. Examples of such an amorphous resin (D) include polyphenylene ether, polyarylate, polysulfone, polyethersulfone, polyetherimide, polycarbonate, cyclic olefin-based resins, and copolymers or functional groups of these amorphous resins. Examples include modified polymers.

  Moreover, the silane compound can be mix | blended with the PAS resin composition of this invention in order to improve a burr | flash etc. in the range which does not impair the effect of this invention. Examples of the silane compound include various types such as vinyl silane, methacryloxy silane, epoxy silane, amino silane, mercapto silane, etc., for example, vinyl trichlorosilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, Examples include γ-aminopropyltriethoxysilane, γ-mercaptotrimethoxysilane, and the like, but are not limited thereto.

  In addition, the PAS resin composition used in the present invention can be supplemented with a small amount of other thermoplastic resin components in addition to the above components depending on the purpose. Any other thermoplastic resin may be used as long as it is stable at high temperatures.

  Further, the PAS resin composition used in the present invention is generally known to be added to thermoplastic resins and thermosetting resins, that is, flame retardants, dyes and pigments, in order to impart desired properties according to the purpose. And other colorants, lubricants, crystallization accelerators, crystal nucleating agents, various antioxidants, heat stabilizers, weathering stabilizers, and the like can be blended according to the required performance.

  The resin composition of the injection molded product used in the present invention can be prepared by equipment and method generally used for preparing a synthetic resin composition. In general, after mixing necessary components, it can be melt-kneaded using a single-screw or twin-screw extruder and extruded to form pellets for molding. It is also a preferred method to melt-extrude the resin component and add and blend the fibrous inorganic filler in the middle.

  The injection-molded product comprising the PAS resin composition of the present invention exhibits extremely good performance as each part of electric / electronic equipment or automobile equipment. Particularly, it is suitable for a molded article having ribs provided for preventing warpage deformation and reinforcing mechanical strength, which has been difficult to satisfy the higher requirements for the suppression of occurrence of sink marks.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

In addition, the specific substance of each component used by the Example and the comparative example is as follows.
・ (A) Polyphenylene sulfide (PPS) resin
(A-1)
A 20 L autoclave was charged with 5700 g of NMP (N-methyl-2-pyrrolidone) and replaced with nitrogen gas, and the temperature was raised to 100 ° C. over about 1 hour while stirring at a rotation speed of 250 rpm. After reaching 100 ° C., 1170 g of a NaOH aqueous solution having a concentration of 74.7% by weight, 1990 g of an aqueous sulfur source solution (including NaSH = 21.8 mol and Na ₂ S = 0.50 mol), and NMP 1000 g were added and gradually increased to 200 ° C. over about 2 hours. Then, 945 g of water, 1590 g of NMP, and 0.31 mol of hydrogen sulfide were discharged out of the system.

  After the dehydration step, the mixture was cooled to 170 ° C., and 3459 g of p-dichlorobenzene, 2800 g of NMP, 133 g of water, and 23 g of NaOH having a concentration of 97% by weight were added. Subsequently, while stirring at a rotational speed of 250 rpm of the stirrer, the temperature was raised to 180 ° C. over 30 minutes, and further between 180 ° C. and 220 ° C. over 60 minutes. After reacting at that temperature for 60 minutes, the temperature was raised to 230 ° C. over 30 minutes, and the reaction was carried out at 230 ° C. for 90 minutes to perform pre-stage polymerization.

  Immediately after completion of the pre-polymerization, the rotation speed of the stirrer was increased to 400 rpm, and 340 g of water was injected. After water injection, the temperature was raised to 260 ° C. over 1 hour, and the reaction was carried out at that temperature for 5 hours to carry out post polymerization.

After completion of the post-polymerization, the reaction mixture is cooled to near room temperature, the contents are passed through a 100 mesh screen, the particulate polymer is filtered off, then washed with acetone three times and then with ion-exchanged water five times. A washed granular polymer was obtained. The granular polymer was dried at 105 ° C. for 13 hours. The granular polymer thus obtained had a melt viscosity (310 ° C., shear rate of 1200 sec ⁻¹ ) of 25 Pa · s, a resin pH of 10.8, and an Na content of 800 ppm.
(A-2)
Perform the same polymerization as (A-1), filter the particulate polymer, wash with acetone three times, wash with water three times, and then wash with 0.3% acetic acid, then wash with water four times. Obtained. The granular polymer was dried at 105 ° C. for 13 hours. The granular polymer thus obtained had a melt viscosity (310 ° C., shear rate of 1200 sec ⁻¹ ) of 20 Pa · s, resin pH 6.5, and Na content of 50 ppm.
・ (B) Inorganic filler
(B-1): Glass fiber having a flat cross-sectional shape
(B-1-1)
Cross-sectional shape: eyebrows, major axis 24 μm, minor axis 12 μm, major axis / minor axis ratio 2 (manufactured by Nittobo Co., Ltd., CSH-3PA)
(B-1-2)
Cross-sectional shape: oval, major axis 24 μm, minor axis 6 μm, major axis / minor axis ratio 4 (manufactured by Nittobo Co., Ltd., CS-3PF)
(B-2); Fibrous and / or non-fibrous inorganic fillers other than (B-1)
(B-2-1)
Glass fiber (major axis 10 μm, major axis / minor axis ratio 1, chopped strand, manufactured by Asahi Fiber Glass Co., Ltd., CS03JAFT636)
(B-2-2)
Glass flake (manufactured by Nippon Sheet Glass Co., Ltd., Micro Glass Flaker REFG-108)
(B-2-3)
White mica (Yamaguchi Mica Kogyo Co., Ltd., Micalet 21PU (11))
・ (C) Thermoplastic elastomer
(C-1)
Ethylene / 1-octene copolymer (DuPont Dow Elastomer Co., Ltd., Engage 8440)
(C-2)
Copolymer obtained by grafting methyl methacrylate / butyl acrylate copolymer to ethylene / glycidyl methacrylate copolymer (Nippon Yushi Co., Ltd., Modiper A4300)
・ (D) Amorphous resin Cyclic olefin resin (Ticona, Topas 6017)
The measurement methods for evaluating physical properties shown in the following examples are as follows.
[Measurement of Na content]
Concentrated sulfuric acid (15 ml) was added to 1 g of sample, and 5 ml of 35% H ₂ O ₂ was further added to the boiled portion. The decomposition solution was diluted with water, and the Na content was quantified with an ICP emission spectroscopic analyzer.
[Measurement of resin pH]
At room temperature (15-25 ° C), 6 g of sample, 15 ml of acetone and 30 ml of purified water (manufactured by Kanto Chemical Co., Inc.) are placed in a flask, shaken for 30 minutes using a shaker, and filtered through a separatory funnel. did. The pH of the supernatant was measured with a pH meter.
[Measurement of bending strength]
A test piece (width 10 mm, thickness 4 mm) according to ISO 3167 was molded and measured according to ISO 178.
[Measure sink]
The molded product of the specific shape shown in Fig. 1 is molded with an injection molding machine (mold temperature 150 ° C), and the rib (1) sink mark (maximum value) on the back side is measured with a surface roughness / contour shape measuring machine (Corporation ) Manufactured by Mitutoyo Corporation).
Examples 1-9, Comparative Examples 1-9
As shown in Tables 1-2, each raw material component (components (A), (B), (C), (D)) is mixed for 5 minutes with a Henschel mixer, and this is a twin screw extruder with a cylinder temperature of 320 ° C. (However, if the component (B) is glass fiber (B-1-1), (B-1-2), (B-2-1), it is added separately from the side feed part of the extruder) Melting and kneading was carried out at a resin temperature of 350 ° C. in a twin screw extruder to produce pellets of the resin composition, and the above physical properties were evaluated. The results are shown in Tables 1-2.

It is a figure which shows the molded article of the specific shape which has the rib used for the measurement of sink marks in the Example.

Claims (7)

(A) Linear polyarylene sulfide having a melt viscosity (310 ° C., shear rate 1200 sec ⁻¹ ) of 5 to 500 Pa · s, an Na content of 500 to 1500 ppm, and a resin pH of 7.0 to 12.0 For 100 parts by weight of resin,
(B) It has a flat cross-sectional shape in which the ratio of the long axis (longest straight line distance in the cross section) and the short diameter (long straight line and longest straight line distance in the right direction) between 1.3 and 10 is perpendicular to the length direction. 67 to 250 parts by weight of an inorganic filler mainly composed of a fibrous reinforcing agent (B-1),
(C) Thermoplastic elastomer which is one or a mixture of two or more selected from olefin copolymers and olefin copolymers based on glycidyl esters of α-olefins and α, β-unsaturated acids A polyarylene sulfide resin composition comprising 7 to 25 parts by weight .   The polyarylene sulfide resin composition according to claim 1, wherein the fibrous reinforcing agent (B-1) having a flat cross-sectional shape is a glass fiber.   The polyarylene sulfide according to claim 1 or 2, wherein a cross-sectional shape of the fibrous reinforcing agent (B-1) having a flat cross-sectional shape is an oval, an ellipse, a semicircle, an eyebrow, a rectangle or a similar shape thereof. Resin composition. The inorganic filler (B) whose main component is the fibrous reinforcing agent (B-1) having a flat cross-sectional shape is a fibrous form other than the fibrous reinforcing agent (B-1) having a flat cross-sectional shape and / or The polyarylene sulfide resin composition according to any one of claims 1 to 3 , which contains a non-fibrous inorganic filler (B-2). Further, with respect to 100 parts by weight of the polyarylene sulfide resin (A), polyphenylene ether, polyarylate, polysulfone, polyethersulfone, polyetherimide, polycarbonate, cyclic olefin resin, and a copolymer of these amorphous resins or The polyarylene sulfide resin composition according to any one of claims 1 to 4 , comprising 5 to 50 parts by weight of an amorphous resin (D) selected from a polymer modified with a functional group. An injection-molded article obtained by using the polyarylene sulfide resin composition according to any one of claims 1 to 5 . The injection-molded article according to claim 6 , wherein the molded article has ribs.

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