JPH02196858A - Polyphenylene sulfide composition for injection molding - Google Patents

Abstract

PURPOSE:To obtain the subject composition giving molded article having excellent impact resistance without generating metal corrosion of mold, etc., in melt molding process by mixing (non) fibrous reinforcing material and particulate calcium carbonate. CONSTITUTION:100 pts.wt. polyphenylene sulfide is mixed with 10-300 pts.wt. (non) fibrous reinforcing material and 0.1-5 pts.wt. particulate calcium carbonate having <=0.5mum, preferably <=0.3mum average particle diameter. Polyphenylene sulfide resin of linear-chain structure having 100-10000 poise melt viscosity at 320 deg.C is used.

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 to melt molding such as melt kneading and injection molding. This invention relates to a polyphenylene sulfide resin composition for injection molding that has extremely low corrosion resistance to metals such as extruders, injection molding machines, and molds during processing, and can provide molded products with excellent mechanical properties such as impact resistance. be.

<Prior art> Polyphenylene sulfide resin (hereinafter abbreviated as PP5ll resin) is known as a thermoplastic engineering plastic with excellent heat resistance, chemical resistance, flame retardance, and dimensional stability. It is widely used in applications such as parts, automobile parts, and precision machine parts.

However, due to its high heat resistance, PPS resin requires a high melt-molding processing temperature, and corrosive gases containing sulfur, such as sulfur dioxide gas and hydrogen sulfide gas, which are thought to be generated from PPS resin that does not melt at high temperatures, may 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. Pat. No. 4,017,450), method of adding hydrotalcite (U.S. Pat. No. 4,529,769)
and method of adding zinc oxide (JP-A-59-'181
408).

<Problems to be Solved by the Invention> However, although the above-mentioned conventional techniques have the effect of improving the metal corrosion resistance of PPS resin, they each have drawbacks, and a completely satisfactory anticorrosion formulation has not yet been established.

In other words, alkali metal carbonates or hydroxides have high water solubility, so if a PPS resin molded product containing them is placed under high temperature and high humidity, these additives will elute and contaminate the surrounding area, causing PPS This has the disadvantage that the insulation properties of the resin decrease.

Furthermore, there is also the problem that the impact resistance of PPS resin is greatly impaired, and this decrease in impact resistance is especially true for linear PP resins.
This is noticeable when S resin is used. Originally, the greatest feature of linear PPS resin is its excellent impact resistance, and the drawback of alkali metal carbonates or hydroxides, which significantly impair this feature, is serious.

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 did not impair the impact resistance of PPS resin.
As a result of our intensive research into finding a method for preventing corrosion of PPS resin that does not degrade insulation or contaminate the surroundings even under conditions of use under high temperature and high humidity conditions, and has a sufficient corrosion prevention effect, we have developed calcium carbonate with a specific particle size. It has been discovered that all of the above problems can be solved by blending a specific amount of the following, and the present invention has been 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 5 parts of fine calcium carbonate having an average particle size of 0.5 μm or less. The present invention provides a PPS resin composition for injection molding, characterized in that it consists of parts by weight.

The PPS resin used in the present invention is a polymer containing the structural formula 1% or more, more preferably 90% by mole or more, and if the repeating unit is less than 70% by mole, 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.

PPS resins are generally made of a polymer with relatively low molecular weight obtained by the production method typified by Japanese Patent Publication No. 45-3368, and a substantially linear polymer obtained by the production method typified by Japanese Patent Publication No. 52-12240. In the case of the polymer obtained by the method described in the above-mentioned Japanese Patent Publication No. 45-3368, after polymerization, it can be heated in an oxygen atmosphere or treated with peroxide, etc. It is also possible to increase the degree of polymerization by adding a crosslinking agent and heating, and in the present invention, it is possible to use PPS resin obtained by any method, but Substantially linear and relatively high molecular weight PPS is preferred in that superior PPS resin injection molded products can be obtained.
Preferably, 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 and a shear rate of 103/sec).

In the present invention, the fibrous or non-fibrous reinforcement is PPS.
PPS is used to improve the heat resistance and strength of resin.
It is blended in a proportion of 10 to 300 parts by weight per 100 parts by weight of the resin.

Such fibrous reinforcing agents include glass fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber,
Examples include inorganic fibers such as gypsum fibers and metal fibers, and carbon fibers.

Examples of non-fibrous reinforcing agents include silicates such as wollastenite, sericite, kaolin, mica, clay bentonite, asbestos, talc, and alumina silicate, and metals such as alumina, silicon chloride, magnesium oxide, zirconium oxide, and titanium oxide. Examples include compounds, carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and barium sulfate, glass beads, boron nitride, silicon carbide, and silica, and these may be hollow.

These reinforcing agents can be used in combination of two or more,
If necessary, it can be used after being pretreated with a silane-based or titanium-based coupling agent.

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, it is stated as a comparative example that calcium carbonate has a certain degree of anticorrosion effect, but
There is no mention of the particle size of the calcium carbonate used, and there is no suggestion that a significantly improved anticorrosive effect can be obtained by using a specific calcium carbonate with an extremely small particle size as in the present invention. Not yet.

Generally used calcium carbonate has a particle size of 1~
The particle size is approximately 5 μm, and it is not possible to obtain the desired effect of the present invention with such a particle size.In addition, when using the general-purpose calcium carbonate mentioned above as a filler for plastics, it is necessary to use it in an amount of 5% by weight or more. 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.

If the particle size of calcium carbonate exceeds 0.5 μm, it is not preferable because the corrosion resistance and impact resistance of the PPS resin composition will deteriorate.

In addition, the amount of fine particle calcium carbonate added is 10% of PPS resin.
0.1 to 5 parts by weight, preferably 0.2 parts by weight
-3 parts by weight. If the amount added is less than 0.1 parts by weight, the anticorrosion effect will be insufficient, and if it exceeds 5 parts by weight, the strength and impact resistance of the PPS resin composition will decrease, which is not preferable.

The method for producing the composition of the present invention is not particularly limited, and a general method can be used. For example, it can be manufactured by mixing the components together at room temperature using a ribbon blade mixer or a drum-type rotary mixer, then melt-kneading them using a single-screw extruder or kneader, and then pelletizing the mixture. can.

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. In addition,
Parts in between are based on weight.

The tensile strength, flexural strength, flexural modulus and Izod impact strength in this example were each measured according to the following methods.

Tensile strength: ASTiVI-D 638 Bending strength: AS
TM-D790 Flexural modulus: ASTM-D790 Izot/impact strength: ASTM-D256 In addition, during the metal corrosion test, PPS resin composition pellets and S-5
A 5C metal rod was sealed in a glass tube and heat treated under the following conditions, and then the corrosion state of the metal rod was visually determined.

Metal rod material: 555C 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 mol, containing 40% crystal water), 4 g of sodium hydroxide, and 3.26 kg of sodium acetate were placed in an autoclave. 1.36 kg (approximately 10 moles) of hydrate and 7.9 kg of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) were charged, and the temperature was gradually raised to 205°C while stirring, and 1.36 kg of water was added. Approximately 1.51 g of distillate water was removed. 1,4-dichlorobenzene 3.7 in the residual mixture
5 kg < 25.5 mol) and 2 kg of NMP,
Heated at 65°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 give a melt viscosity of about 2.500 poise (320°C, shear rate 1.00
0 s-1) substantially linear powdered PPS resin approximately 2k
I got g.

The same operation was repeated and used in Examples.

Examples 1 to 4, Comparative Example 1 After tri-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 supplied to a 40 mm diameter single screw extruder set at 290 to 320°C, and melt-kneaded to obtain PPS resin composition pellets. The pellets were supplied to an injection molding machine set at a cylinder temperature of 280 to 320°C and a mold temperature of 150°C to mold a test piece.

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 has an excellent anticorrosion effect on metals.

Comparative Examples 2-3 The same procedure as in Example 1 was conducted 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 The same procedure as in Example 1 was carried out except that calcium carbonate having an average particle size of 4.0 μm and 1.0 μm was used instead of finely divided calcium carbonate.

The results are shown in Table 1, and it is clear that the physical properties are greatly reduced by addition and the anticorrosion effect is also inferior compared to the examples of the present invention.

Comparative Example 6 Kneading, molding, and evaluation were carried out in 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 the anticorrosion effect was sufficient, but the mechanical strength and impact resistance were significantly reduced.

<Effects of the Invention> The polyphenylene sulfide resin composition of the present invention has an excellent effect of preventing corrosion of extruders, injection molding machines, molds, etc., and also greatly improves the rate of defective products due to corrosion of insert metal parts. In addition to this, it is also possible to provide molded products with excellent mechanical properties such as impact resistance.

Patent application Daitoshi Co., Ltd.

Claims (2)

[Claims] (1) 100 parts by weight of polyphenylene sulfide resin, 10 to 300 parts by weight of fibrous or non-fibrous reinforcing material, and 0.1 particulate calcium carbonate with an average particle size of 0.5 μm or less
5 parts by weight of a polyphenylene sulfide resin composition for injection molding. (2) The 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. Polyphenylene sulfide resin composition for use.