JPH0565543B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a polyphenylene sulfide resin composition for injection molding which has excellent melt molding processability, and more specifically, during melt molding processing such as melt kneading and injection molding. This invention relates to a polyphenylene sulfide resin composition for injection molding, which has extremely low corrosion resistance to metals such as extruders, injection molding machines, and molds, and can provide molded products with excellent mechanical properties such as impact resistance. . <Prior art> Polyphenylene sulfide resin (hereinafter abbreviated as PPS resin) is known as a thermoplastic engineering plastic with excellent heat resistance, chemical resistance, flame retardance, and dimensional stability. Widely used in electrical/electronic parts, automobile parts, precision mechanical parts, etc. However, due to its high heat resistance, PPS resin requires high melt-molding processing temperatures, and corrosive gases containing sulfur, such as sulfur dioxide gas and hydrogen sulfide gas, which are thought to be generated from PPS resin melted at high temperatures, may cause metal parts of molding equipment to There is a problem in that the metal inserts of molded electrical parts such as switches and connectors are susceptible to corrosion. Several methods have been disclosed so far for reducing the metal corrosivity of PPS resins, such as adding carbonates or hydroxides of alkali metals such as lithium carbonate, sodium carbonate, and sodium hydroxide. Method (U.S. Patent No. 4017450)
Examples include a method of adding hydrotalcite (US Pat. No. 4,529,769), and a method of adding zinc oxide (Japanese Patent Application Laid-open No. 181408/1983). <Problem to be solved by the invention> However, although the above-mentioned conventional techniques have been recognized to have the effect of improving the metal corrosiveness of PPS resin, they each have their own drawbacks, and a completely satisfactory corrosion recipe has not yet been established. In other words, alkali metal carbonates or hydroxides have high water solubility, so they are added to PPS.
If a resin molded product is placed under high temperature and high humidity, these additives may leach out and contaminate the surrounding area, or the insulation properties of PPS resin may deteriorate. Furthermore, PPS
Another problem is that the impact resistance of the resin is greatly impaired, and this reduction in impact resistance is particularly noticeable when a linear PPS resin is used. Originally, the greatest feature of linear PPS resin was its excellent impact resistance.
The disadvantage of alkali metal carbonates or hydroxides is that they significantly impair this characteristic. Furthermore, the above-mentioned hydrotalcite and zinc oxide similarly have the disadvantage of significantly lowering the impact resistance of PPS resin. Therefore, the present inventors have developed a corrosion protection method for PPS resin that does not impair the impact resistance of PPS resin, does not cause deterioration of insulation or contaminate the surroundings even under high temperature and high humidity usage conditions, and has a sufficient corrosion prevention effect. As a result of intensive studies with the objective of obtaining such particles, it was discovered that all of the above-mentioned problems could be solved by blending a specific amount of calcium carbonate having a specific particle size, and the present invention was achieved. <Means for Solving the Problems> That is, the present invention consists of 100 parts by weight of PPS resin, 10 to 300 parts by weight of fibrous or non-fibrous reinforcing material, and 0.1 to 0.1 to 0.5 μm of fine particle calcium carbonate with an average particle size of 0.5 μm or less.
For injection molding, characterized in that it consists of 5 parts by weight.
A PPS resin composition is provided. What is the structural formula of the PPS resin used in the present invention?

It is a polymer containing 70 mol % or more, more preferably 90 mol % or more of the repeating unit represented by the formula. If the repeating unit is less than 70 mol %, heat resistance will be impaired, so it is not preferable. Furthermore, less than 30 mol% of the repeating units in the PPS resin can be composed of repeating units having the following structural formula, etc.

【formula】

【formula】

[Formula] PPS resin is generally a polymer with a relatively small molecular weight obtained by the production method typified by Japanese Patent Publication No. 1982-3368, and a polymer obtained by the production method typified by the production method typified by Japanese Patent Publication No. 52-12240. There are polymers that are generally linear and have relatively high molecular weight.
In the polymer obtained by the method described in the publication,
After polymerization, it is possible to increase the degree of polymerization and use it by heating in an oxygen atmosphere or by adding a crosslinking agent such as peroxide and heating. Although it is possible to use PPS resin, it is preferable to use a substantially linear and relatively high molecular weight PPS resin injection molded product with excellent strength and impact resistance.
Preferably, PPS resin is used. The melt viscosity of the PPS resin used in the present invention is not particularly limited as long as it can be kneaded with the reinforcing material and fine particle calcium carbonate, but it is usually 100 to 10,000 poise, preferably 500 to 5,000 poise (320°C, shear rate 10 ³ /sec) is used. In the present invention, the fibrous or non-fibrous reinforcing material is blended in an amount of 10 to 300 parts by weight per 100 parts by weight of the PPS resin for the purpose of improving the heat resistance and strength of the PPS resin. Examples of such fibrous reinforcing agents include inorganic fibers such as glass fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, and metal fibers, and carbon fibers. Examples of non-fibrous reinforcing agents include wollastenite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, silicates such as alumina silicate, alumina, silicon chloride, magnesium oxide, zirconium oxide, and titanium oxide. Metal compounds, carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and barium sulfate, glass beads,
Examples include boron nitride, silicon carbide, and silica, and these may be hollow. Two or more of these reinforcing agents can be used in combination, and if necessary, they can be pretreated with coupling agents such as silane and titanium before use. In the present invention, it is extremely important to use a specific amount of fine calcium carbonate having a specific particle size as a metal corrosion inhibitor for PPS resin. This is because by using calcium carbonate within the above particle size and addition amount ranges, it is possible to effectively prevent metal corrosion without impairing the impact resistance of the PPS resin. In the above-mentioned US Pat. No. 4,017,450, as a comparative example, it is stated that calcium carbonate has a certain degree of anticorrosive effect, but there is no mention of the particle size of the calcium carbonate used, and the present invention There is also no suggestion that a significantly improved anticorrosive effect can be obtained by using a specific calcium carbonate having an extremely small particle size. Calcium carbonate, which is commonly used, has a particle size of about 1 to 5 μm.
With such a particle size, the desired effect of the present invention cannot be obtained. Furthermore, when the above-mentioned general-purpose calcium carbonate is used as a plastic filler, the blending amount is 5% by weight or more, and even when such a large amount is blended, the effects of the present invention cannot be obtained. The fine particle calcium carbonate used in the present invention is calcium carbonate having an average particle size of 0.5 μm or less, preferably 0.3 μm or less. Examples of such calcium carbonate include fine precipitated calcium carbonate synthesized by chemical production methods such as soluble chlorination method, carbonation method, and lime milk soda method. For example, using the commercially available products shown in the following table. be able to.

[Table] PPS when the particle size of calcium carbonate exceeds 0.5μm
This is undesirable because the corrosion resistance and impact resistance of the resin composition become obvious. Further, the amount of fine particle calcium carbonate added is 0.1 to 5 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of PPS resin.
It is selected from the range of 0.2 to 3 parts by weight. The amount added
If the amount is less than 0.1 part by weight, the anticorrosion effect will be insufficient.
On the other hand, if it exceeds 5 parts by weight, the strength of the PPS resin composition
This is not preferred because impact resistance decreases. The method for producing the composition of the present invention is not particularly limited, and a general method can be used. For example, after mixing the components together using a ribbon vane mixer, a drum-type rotary mixer at room temperature,
It can be produced by melt-kneading using a single-screw or twin-screw extruder, kneader, or the like, and pelletizing the resultant mixture. The melt-kneading temperature is preferably 280° C. or higher in order to sufficiently melt the PPS resin, and 340° C. or lower in order to prevent thermal deterioration and gelation of the PPS resin. <Examples> The present invention will be specifically described below with reference to Examples. Note that parts in the examples are based on weight. The tensile strength, flexural strength, flexural modulus and Izot impact strength in this example were each measured according to the following methods. Tensile strength: ASTM-D638 Bending strength: ASTM-D790 Flexural modulus: ASTM-D790 Izot impact strength: ASTM-D256 In addition, the metal corrosion test in the example was conducted using PPS resin composition pellets and S-55C metal. After the rod was sealed in a glass tube and heat treated under the following conditions, the corrosion state of the metal rod was visually determined. Metal rod material: S55C Heat treatment conditions: Temperature: 320°C Time: 16 hours Reference example 1 (Polymerization of PPS resin) In an autoclave, 3.26 kg of sodium sulfide (25 moles, containing 40% crystal water), 4 g of sodium hydroxide,
1.36 kg (approximately 10 mol) of sodium acetate trihydrate and 7.9 kg of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) were charged, and the mixture was gradually heated to 205 kg while stirring.
The temperature was raised to ℃, and about 1.5 kg of distilled water containing 1.36 kg of water was removed. Add 3.75 Kg (approximately 25.5 mol) of 1,4-dichlorobenzene and 2 Kg of NMP to the residual mixture,
Heated at 265°C for 4 hours. The reaction product was washed 5 times with hot water at 70°C and dried under reduced pressure at 80°C for 24 hours to obtain a melt viscosity of approximately 2500 poise (320°C, shear rate 1000 sec ^-1 ).
About 2 kg of substantially linear powdered PPS resin was obtained. The same operation was repeated and used in Examples. Examples 1 to 4, Comparative Example 1 After dry blending the PPS resin powder of Reference Example 1, glass fiber, and fine particle calcium carbonate with the composition shown in Table 1, the mixture was fed to a 40 mmφ single screw extruder set at 290 to 320°C. , and melt-kneaded to obtain a PPS resin composition pellet. This pellet is heated to a cylinder temperature of 280
The sample was supplied to an injection molding machine set at ~320°C and a mold temperature of 150°C, and a test piece was molded. Next, the metal corrosion test and physical properties of the resin composition were measured and the results are shown in Table 1. As is clear from Table 1, the mechanical properties of the composition of the example of the present invention are the same as those of Comparative Example 1, which does not contain particulate calcium carbonate (there is no deterioration in physical properties due to the addition), and Excellent anti-corrosion effect on metals. Comparative Examples 2-3 The same procedure as in Example 1 was carried out except that lithium carbonate or zinc oxide was used instead of fine particle calcium carbonate. The results are shown in Table 1. Comparative Example 4, 5 Average particle size 4.0 μ instead of fine particle calcium carbonate
The same procedure as in Example 1 was carried out except that calcium carbonate of 1.0 μm and 1.0 μm was used. The results are shown in Table 1, and it is clear that the physical properties are significantly reduced and the anticorrosive effect is also inferior compared to the examples of the present invention. Comparative Example 6 Kneading, molding, and evaluation were carried out in exactly the same manner as in Example 1, except that the amount of finely divided calcium carbonate added was 10 parts by weight. The results are shown in Table 1, and although the anticorrosion effect was sufficient, the mechanical strength and impact resistance were significantly reduced.

[Table] <Effects of the Invention> The polyphenylene sulfide resin composition of the present invention has an excellent anticorrosive effect on extruders, injection molding machines, molds, etc., and also reduces the defective product rate due to corrosion of insert metal parts. Not only can this method greatly improve the properties of the molded product, but it can also provide molded products with excellent mechanical properties such as impact resistance.

Claims (1)

[Claims] 1. 100 parts by weight of polyphenylene sulfide resin,
10 to 300 parts by weight of fibrous or non-fibrous reinforcing material and particulate calcium carbonate with an average particle size of 0.5 μm or less
A polyphenylene sulfide resin composition for injection molding, comprising 0.1 to 5 parts by weight. 2. The polyphenylene sulfide resin for injection molding according to claim 1, wherein the polyphenylene sulfide resin has a melt viscosity of 100 to 10,000 poise at 320°C and has a substantially linear structure. Rensulfide resin composition.