JPH0586982B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a polyphenylene sulfide resin composition having antistatic properties. <Prior art> JP-A-59-96142 discloses a moldable resin composition prepared by mixing and kneading carbon black, graphite, and a non-conductive filler with a thermoplastic resin or thermosetting resin as a conductive resin composition. known by. <Problems to be Solved by the Invention> When this technique is applied to polyphenylene sulfide, a resin composition having a volume resistivity of 10 ³ to ^{10 10} Ω·cm can be obtained. However, no matter how much the above technology is applied to polyphenylene sulfide, injection molding fluidity and mechanical strength are significantly reduced due to carbon black, and dimensional stability is reduced due to non-uniform dispersion and orientation of reinforcing materials. For example, it has been difficult to obtain precision injection molded parts required for the heart of optical/magnetic application equipment. The present invention provides an injection molded product that has high antistatic properties, maintains a level of injection moldability and high mechanical strength of polyphenylene sulfide resin that could not be obtained with conventional technology, and has high dimensional stability. The object of the present invention is to provide a polyphenylene sulfide resin composition that provides the following properties. <Means for solving the problems> The objects of the present invention are (a) polyphenylene sulfide resin of 25 to 75% by weight, (b) DBP oil absorption of 400ml/100g
Above, and the total amount of nickel and vanadium is
Conductive carbon black 0.5-3.5 below 200ppm
% by weight, (c) 2 to 18% by weight of natural flaky graphite, (d) one or a mixture of two or more selected from carbonates, sulfates, phosphates, silicates of calcium, magnesium, barium, talc, and mica. Achieved by a polyphenylene sulfide resin composition containing 5 to 40% by weight of an inorganic filler consisting of It was done. The polyphenylene sulfide resin (hereinafter abbreviated as PPS) targeted by the present invention includes poly(para-
phenylene sulfide), poly(meta-phenylene sulfide), poly(para-phenylene sulfide + meta-phenylene sulfide), and the like. These PPSs themselves are well known and readily available on the market. The content of these PPSs needs to be 25% by weight or more in order to maintain the mechanical strength of the PPS composition. On the other hand, the upper limit of PPS is 75% by weight due to the provision of antistatic properties, dimensional stability, etc. by other components of the present invention.
becomes. Next, as the carbon black used in the present invention, a conductive carbon black with a DBP oil absorption of 400 ml/100 g or more and a total content of nickel and vanadium of 200 ppm or less is used, but such carbon black is a PPS composition. When incorporated into carbon black, it provides higher conductivity or antistatic properties than conventional carbon black. Note that DBP oil absorption means oil absorption measured according to the method specified in ASTM-D2414-79. When the DBP oil absorption amount of carbon black is less than 400ml/100g, a large amount of carbon black must be added to obtain a PPS composition with high antistatic properties, which will affect the moldability and mechanical properties of the final composition. This is not preferable because the strength is impaired. Regarding carbon black, which is the subject of the present invention, there is no particular upper limit to the DBP oil absorption, but for manufacturing reasons, it is usually 750
ml/100g or less is preferably used. Furthermore, the total amount of nickel and vanadium contained in the carbon black of the present invention must be 200 ppm or less, and it is particularly preferable that the vanadium content is 80 ppm or less and the nickel content is 40 ppm or less. If this total amount exceeds 200 ppm, PPS will be affected by heavy metal ions, the dispersibility of carbon black will deteriorate, and the moldability of the composition will deteriorate significantly. The amount of carbon black added must be in the range of 0.5 to 3.5% by weight, and further 0.7% by weight.
~1.9% by weight is preferred. If the amount of carbon black added is less than 0.5% by weight, it will be difficult to impart antistatic properties to the final PPS composition, which is not preferable. On the other hand, if it exceeds 3.5% by weight, it becomes difficult to maintain sufficient mechanical strength of the final PPS composition, which is not preferable. Next, the graphite used in the present invention needs to be natural scaly graphite. Graphite as an industrial material is generally divided into artificial graphite, which is made by graphitizing coke, tar, pitch, etc. at high temperatures, and natural graphite. Furthermore, natural graphite is classified into scaly graphite and earthy graphite depending on the production area. The present inventors have discovered that a particular type of graphite, natural flaky graphite, is particularly excellent for the following reasons. (1) Provides higher antistatic effect than artificial graphite and earthy graphite. (2) Since it has the highest effect of increasing the dispersion of the conductive carbon black applied to the present invention, it significantly reduces the reduction in moldability and mechanical strength caused by the addition of carbon black. In the present invention, the particle size of natural flaky graphite is not particularly limited, but the average particle size determined by microscopic measurement is 0.8.
~12μ is relatively preferred. Further, the concentration of the graphite added must be in the range of 2 to 18% by weight. If the amount is less than 2% by weight, it is difficult not only to obtain the effect of increasing the antistatic property of the graphite itself, but also to sufficiently increase the dispersibility of the conductive carbon black. On the other hand, if the amount of conductive carbon black exceeds 18% by weight, the graphite itself will provide sufficiently high antistatic properties even if the content is less than 0.5% by weight, but the influence of orientation during injection molding will increase, resulting in dimensional stability of the molded product. This is not preferable because it reduces the quality of the product. This effect appears, for example, in the form of a larger difference in the linear expansion coefficient of the molded product between the flow direction of the resin composition and the direction perpendicular to the flow, impairing the practical value of precision molded products that require high dimensional accuracy. Furthermore, the total amount of conductive carbon black and natural flaky graphite, which are the object of the present invention, must be in the range of 4 to 20% by weight. When the total amount is less than 4% by weight, if the proportion of carbon black is small, the antistatic property is insufficient, and if the proportion of carbon black is large, even if the antistatic property is sufficient, the graphite If the amount is too small, the dispersibility of the conductive carbon black will be poor, and injection moldability and mechanical strength will be significantly impaired. Moreover, if the total amount exceeds 20% by weight, the adverse effects of orientation during injection molding will increase, and the mechanical strength level of the molded product will also decrease significantly, which is not preferable. Next, as the fourth component of the resin composition of the present invention,
Calcium, magnesium, barium carbonates,
5 to 40% by weight of an inorganic filler consisting of one or a mixture of two or more selected from sulfates, phosphates, silicates, talc, and mica is required. In the resin composition of the present invention, such an inorganic filler is necessary in order to impart high dimensional stability to the injection molded article. In addition, such inorganic fillers have the effect of enhancing the antistatic effect of conductive carbon black and graphite, and are also useful in terms of increasing rigidity and heat resistance. The amount of these inorganic fillers added must be determined appropriately depending on the required performance, but is generally 5 to 40% by weight.
A range of is required. If it is less than 5% by weight, the dimensional stabilizing effect will be poor, and if it exceeds 40% by weight, it will be difficult to maintain mechanical strength. Further, the particle size of such an inorganic filler is not particularly limited, but in most cases, an average particle size of 50 μm or less is suitable. Furthermore, of course, in the resin composition of the present invention, other appropriate fillers and heat stabilizers may be added in addition to the above four components to strengthen, suppress thermal expansion, increase sliding properties, improve heat resistance, etc. It is also possible to provide effects such as increased dimensional stability. The filler that can be added is not particularly limited, but fibrous materials and solid fine powders with excellent heat resistance are effective. As the fiber material, those having excellent heat resistance and durability, such as glass fiber, carbon fiber, steel fiber, brass fiber, and potassium titanate whisker, are used. In addition, solid fine powders include colloidal silica, quartz powder, tungsten disulfide, molybdenum disulfide, boron nitride,
Ferrite powder, magnetite powder, etc. are used. Among these fillers, carbon fibers, steel fibers, and brass fibers have the effect of reducing conductive carbon black and graphite within the addition range of the present invention from the viewpoint of antistatic properties. In addition, in small amounts, polysulfone, polyethersulfone, polyallylsulfone, polyarylate, polyamideimide, polyetherimide, aromatic polyester resin, polyetheretherketone, etc. may be added to the resin composition of the present invention. A known thermoplastic polymer may be used in combination. The resin composition of the present invention can be obtained by mixing and kneading the component raw materials described above. Kneading can be done by the usual methods, such as drum-type kneading using a Banbury mixer or the like, followed by pulverization, or dry blending using a Henschel mixer, followed by continuous kneading and extrusion using an extruder to form pellets, or pulverizing. A method of forming irregularly shaped particles can be adopted. <Example> Next, an example will be described in detail. The methods for measuring volume resistivity, tap screw strength, and isotropy of thermal expansion coefficient described in Examples and Comparative Examples are as follows. (1) Volume resistivity Measured using a Takeda Riken TR6877 Computing Digital Multimeter on an injection molded disk with a diameter of 40 mm and a thickness of 3 mm at a surface load of 5 Kg/cm ² and an atmosphere of 23°C and 60% RH. do. (2) Tapping screw strength First, a pilot hole with a diameter of 1.5 mm was drilled in the center of the test piece, which was injection molded into a rectangular column with a length of 60 mm, a width of 12 mm, and a thickness of 6 mm, using a tabletop tapping machine (KRT-10 type manufactured by Kira Iron Works) in the thickness direction. Drill with a straight shank drill needle of mm (standard JIS B4301/PCS10), then drill with a diameter of 2.0 mm.
Tap with a standard M2 x 0.4 tapping needle. Screw a Phillips M2 x 4 type screw into the obtained screw hole with a torque driver (Tohnichi 10FTD type), and calculate the torque required to destroy the thread on the test piece side (torque when the screw becomes loose). Measure. (3) Isotropy of linear expansion coefficient Size 30 injection molded with a film gate mold
Cross section 3mm from the center of a mm square, 3mm thick flat plate
Cut out a square prism with a length of 16 mm in the flow direction of the resin and in a direction perpendicular to the flow. (One test piece was made from one flat plate.) The coefficient of linear expansion in the length direction of this test piece was measured using a thermomechanical analysis device (TMA) manufactured by Rigaku Denki at a heating rate of 1°K/min and a measurement temperature. Range 30-80
Measure at ℃. The isotropy of the coefficient of linear expansion is expressed as the difference between the coefficient of linear expansion in the flow direction of the resin and the coefficient of linear expansion in the direction perpendicular to the flow, and it is determined that the smaller this difference is, the greater the dimensional stability is. Example 1 PPS powder (Ryton P-6, manufactured by Phillips Petroleum) 2.5Kg and DBP oil absorption 480ml/
100g, nickel content 15ppm, vanadium content 50ppm
Conductive carbon black (manufactured by Lion Akzo, EC-DJ600) 0.15Kg and natural scale graphite (CP,
0.65 kg (manufactured by Nippon Graphite Industries), 3.4 kg of calcium carbonate powder (KSS-1000, manufactured by Kinpei Mining Co., Ltd.), and 3.45 kg of glass fiber (chopped strand, TN-101, manufactured by Nippon Glass Electric) were mixed in 10 drum tumblers of 50.
After uniformly mixing for a minute, the mixture was kneaded and extruded using a 45 m/mφ twin-screw extruder (PCM-45, manufactured by Ikegai Iron Works) at a cylinder temperature of 323°C and a screw rotation speed of 80 rpm, and then hot cut into pellets. The obtained pellets were heated to a cylinder temperature of 318°C using a 75TON injection molding machine (Sycap, manufactured by Sumitomo Heavy Industries).
℃, mold temperature 140℃, injection pressure 1000Kg/ ^cm3 , volume resistivity test piece (diameter 40mm, thickness 3
mm disk), No. 1 dumbbell (ASTM-D-638), tap screw strength measurement test piece (60 mm x 12 mm x 6 mm square column), linear expansion coefficient measurement test piece (30 mm x 30 mm x 3 mm,
A square plate) is molded, and the volume resistivity (Rv) is measured as antistatic property, the tensile strength (TS) is measured as strength,
and tap screw strength (SSD), and linear expansion coefficient isotropy (ELE) was measured as a measure of dimensional stability. As shown in Table 1, the obtained composition has practically acceptable molding fluidity, and the average value of Rv is 6×10 ⁴ Ω・
cm, variation range (n=50) 3×10 ⁴ to 8
×10 ⁴ is sufficiently uniform for practical use, TS700Kg/cm ² ,
It exhibited an SSD of 3.7 kg·cm and an ELE of 0.01×10 ^-5 /°C, indicating excellent antistatic properties and sufficient strength and dimensional stability as a molding material. Examples 2 and 3 In Example 1, compositions were obtained by changing the amount of PPS, the amount of calcium carbonate added, and the amount of glass fiber added as shown in Table 1, and the compositions were tested in the same manner as in Example 1. As the results are shown in Table 1, all of them were sufficient as molding materials. Comparative Example 1 When the PPS blending amount was changed to 2.0Kg, calcium carbonate 3.7Kg, and glass fiber 3.65Kg in Example 1,
As shown in Table 1, the strength level was low and it was insufficient as a molding material. Comparative Example 2 In Example 1, the composition was changed to 8.0 kg of PPS, 0.7 kg of calcium carbonate, and 0.65 kg of glass fiber, and as shown in Table 1, the range of variation in Rv was large, the strength level was low, and Due to the large ELE, the dimensional stability was poor and the material had little practical value as a molding material. Example 4 PPS powder (Ryton P-4, manufactured by Phillips Petroleum) 5.0Kg and DBP oil absorption 420ml/
100g, nickel content 40ppm, vanadium content 140ppm
0.2 kg of conductive carbon black, 0.5 kg of natural scale graphite (CSP, manufactured by Nippon Graphite Industries), and 2.2 kg of fine powder of calcium sulfate dihydrate (manufactured by Hanui Chemicals).
and 2.15 kg of glass fiber (Glasron chopped strand CS-06-MA-497, manufactured by Asahi Fiberglass Co., Ltd.) were uniformly mixed in a 50 mm drum tumbler for 10 minutes, and then kneaded under the same conditions as in Example 1. Extrusion, molding, and evaluation were performed. As the results are shown in Table 1, the obtained composition had excellent antistatic properties, high strength level and dimensional stability, and was of high practical value. Comparative Example 3 In Example 4, conductive carbon black
The mixture was kneaded and extruded in the same manner as in Example 4, except that the DBP oil absorption was changed to 350 ml/100 g, and each test piece was molded and measured. As the results are shown in Table 1, although antistatic properties were observed, the variation was large and unsatisfactory for practical use. Comparative Example 4 A test was carried out in the same manner as in Example 4, except that the total amount of nickel and vanadium in the conductive carbon black was changed to 300 ppm. Display the results -
As shown in No. 1, the dispersibility of carbon black was poor, resulting in poor molding fluidity, large variations in volume resistivity, and low tensile strength and dimensional stability. Example 5 In Example 1, the amount of PPS added was changed to 4.5Kg, the amount of conductive carbon black added was changed to 0.05Kg, the amount of calcium carbonate added was changed from 3.4Kg to 2.0Kg of talc (MST, manufactured by Takehara Chemical), and the amount of glass fiber added was changed to 2.95Kg. The test was conducted in the same manner as in Example 1 except for the following. The evaluation results are shown in Table-1. Although the antistatic property was somewhat low, it was within the practical range due to little variation, and the strength level and dimensional stability were sufficient. Example 6 In Example 5, conductive carbon black was used.
The test was carried out in the same manner as in Example 5, except that the amount of glass fiber was changed to 0.35 kg and 2.65 kg. As shown in Table 1, the obtained composition had excellent antistatic properties and dimensional stability, and had no practical problems in molding fluidity and strength. Comparative Example 6 A test was carried out in the same manner as in Example 5, except that the amount of conductive carbon black added was changed to 0.40 kg and the amount of glass fiber added was changed to 2.60 kg. As a result, the molding fluidity was poor and the strength was extremely low. It was hot. Example 7 In Example 1, the amount of PPS added was 4.5Kg, the amount of conductive carbon black added was 0.10Kg, the amount of graphite added was 1.0Kg, and calcium carbonate 3.4Kg was mixed with mica (Susolide Mica 325-HK, Marietta Resource Interchanger). The test was conducted in the same manner as in Example 1, except that the glass fiber content was changed to 1.4 kg (manufactured by Nacional) and 3.0 kg. As shown in Table 1, the moldability, antistatic properties, strength, and dimensional stability were sufficiently satisfactory as a molding material. Comparative Examples 7 and 8 Example 7 except that the type of graphite was changed to natural clay (AP, manufactured by Nippon Graphite Industries) or artificial graphite powder (pulverized SEG-RH round bar manufactured by Nippon Carbon). The results are shown in Table 1.
Shown below. All of the compositions had low antistatic properties and insufficient dimensional stability as compositions for precision molding in view of the isotropy of linear expansion coefficients. Example 8 In Example 5, the amount of conductive carbon black added was 0.25Kg, the amount of graphite added was 0.20Kg, talc was 2.0Kg, calcium phosphate (Daisan) (manufactured by Hanui Chemical Co., Ltd.) fine powder 1.6Kg, and glass fiber was added. The test was conducted in the same manner as in Example 5, except that the weight was changed to 3.45Kg. As shown in Table 1, the obtained composition had excellent antistatic properties, tap screw strength, and dimensional stability, and also had molding fluidity and tensile strength that were suitable for practical use. Example 9 In Example 5, the amount of conductive carbon black added was 0.20Kg, the amount of graphite added was 1.8Kg, and talc was 2.0Kg.
Magnesium carbonate (basic) (manufactured by Hanui Chemicals)
1.6Kg of powder, 1.90Kg of glass fiber,
The test was carried out in the same manner as in Example 5, except for the following changes.
As shown in Table 1, the obtained composition had an excellent balance of physical properties and was sufficient as a molding material. Comparative Example 9 Same as Example 8 except that the graphite content was changed to 0.15Kg and the glass fiber content was changed to 3.50Kg.
It was carried out in the same way. As a result, as shown in Table 1, due to the poor dispersibility of the conductive carbon black, the volume resistivity value varied greatly and the dimensional stability was also insufficient. Comparative Example 10 The same procedure as in Example 9 was carried out except that the amount of conductive carbon black added was changed to 0.10 kg and the amount of graphite added was changed to 1.9 kg. Although the obtained composition had good fluidity, it was unsatisfactory as a molding material because of its low linear expansion coefficient isotropy. Example 10 In Example 1, 2.5 kg of PPS powder was added to 4.5 kg of a 70:30 mixture of Ryton P-6 and Ryton V-1,
Added graphite amount to 0.25Kg, calcium carbonate powder 3.4
Kg to barium carbonate powder (manufactured by Hanui Chemicals) 2.10Kg
The test was conducted in the same manner as in Example 1, except that the amount of glass fiber blended was changed to 3.0 kg. As shown in Table 1, the obtained composition was satisfactory as a molding material. Example 11 In Example 10, the amount of conductive carbon black added (B) was set to 0.20Kg, the amount of graphite added (C) was set to 1.8Kg, and barium carbonate powder 2.10Kg was added to magnesium sulfate anhydride (manufactured by Hanui Chemicals). Same as the example except that the powder content was changed to 1.50Kg and the glass fiber content was changed to 2.0Kg.
Tested in the same manner as in 10. As shown in Table 1, the obtained composition had excellent antistatic properties, and had no problems in strength level and dimensional stability. Comparative Example 11 In Example 10, the amount of conductive carbon black added (B) was set to 0.050Kg, and the amount of graphite added (C) was set to 0.20Kg ((B)
+(C)0.25Kg), barium carbonate powder to 2.25Kg,
The test was carried out in the same manner as in Example 10, except for the following changes.
The resulting composition had insufficient antistatic properties as shown in Table 1. Comparative Example 12 Same as Example 11 except that the amount of conductive carbon black added (B) was changed to 0.30Kg ((B) + (C) 2.1Kg) and the magnesium sulfate powder was changed to 1.40Kg. carried out. As shown in Table 1, the obtained composition had excellent antistatic properties, but had low strength levels and dimensional stability, and was unsatisfactory as a molding material. Examples 12 to 16 In Example 10, the amount of graphite added was 0.65 kg, and as the fourth component, barium sulfate powder (Example 12) powdered from Hani Chemical Co., Ltd. and magnesium phosphate (Daiichi) powder (Implementation) were used. Example 13), barium (meth) phosphate powder (Example 14), calcium silicate powder (Example 15), magnesium silicate powder (Example
Add glass fiber to 1.20Kg of any of 16).
The test was conducted in the same manner as in Example 10, except that the weight was changed to 2.5 kg. As shown in Table 1, all of the obtained compositions had well-balanced physical properties and were sufficient as injection molding materials. Example 17 Same as Example 1 except that the amount of PPS added was changed to 5.5Kg, the amount of graphite added was changed to 0.65Kg, the amount of calcium carbonate powder added was changed to 0.50Kg, and the amount of glass fiber added was changed to 3.2Kg. When carried out in the same manner as in Example 1, the obtained composition had an excellent balance of physical properties and was satisfactory as a molding material, as shown in Table 1. Ta. Comparative Example 13 In Example 17, the amount of calcium carbonate added was
The test was conducted in the same manner as in Example 17, except that the amount of glass fiber was changed to 0.30Kg and 3.4Kg.
As shown in Table 1, the dimensional stability was poor and it was unsatisfactory as a molding material. Example 18 In Example 1, the amount of PPS added was 3.5Kg, the amount of graphite added was 0.65Kg, and the amount of calcium carbonate added was changed to 3.5Kg.
The test was carried out in the same manner as in Example 1 except that the amount of glass fiber was changed to 4.0Kg and the amount of glass fiber blended to 1.7Kg. Table-1
As shown in Figure 2, the obtained composition was particularly excellent in antistatic properties, tap screw strength, and dimensional stability, and was preferred as a molding material. Comparative Example 14 In Example 18, the amount of calcium carbonate added was
The test was conducted in the same manner as in Example 18, except that the amount of glass fiber was changed to 4.5Kg and the glass fiber content was changed to 1.2Kg.
As shown in Table 1, the strength level was insufficient as a molding material.

【table】

[Table] *: Indicates conditions outside the scope of the present invention.
<Effects of the Invention> According to the present invention, it is possible to obtain a PPS composition that has high antistatic properties and excellent dimensional stability while minimizing deterioration in the molding fluidity and mechanical strength inherent in PPS. Unlike the case of the heat-resistant antistatic resin composition, it is possible to provide a composition that is particularly excellent as a material for precision injection molding. Therefore, the PPS resin composition of the present invention can be applied to various uses. For example, VTR, video disc,
It can be used in many fields, including molding materials for various mechanical parts that require antistatic properties in optical/magnetic application equipment such as compact disks.

Claims (1)

[Claims] 1 (a) Polyphenylene sulfide resin 25~
75% by weight (b) Conductive carbon black with DBP oil absorption of 400ml/100g or more and total nickel and vanadium content of 200ppm or less 0.5 to 3.5% by weight (c) Natural scaly graphite 2 to 18% by weight (d) (b ) and (c) the total amount of ingredients is 4~
A polyphenylene sulfide resin composition characterized by having a content of 20% by weight.