JPS6189031A - Plastic screwlike molding - Google Patents

Abstract

PURPOSE:To obtain a plastic screwlike molding that is reinforced highly with reinforcing fibers, and is lightweight, corrosion-resistant, chemical-resistant and electrically insulative, by making said body of a resin composition that consists of a polyphenylene sulfide resin and inorganic reinforcing fiber and has a specified melt viscosity. CONSTITUTION:PPS resin includes crystalline linear high polymer molecules having a structure shown at the equation wherein (n) is a natural number and is excellent in heat resistance. The melt viscosity is to be 1X10<4>-10<6> poises at 300 deg.C and a shear rate of 10<2>/sec. The reinforcing fiber that will be contained in the composition may be inorganic or organic and will be mixed with the thermoplastic resin in a mixer such as a supermixer, and the composition is kneaded and molded by an extruder or the like into a cylindrical stock. In the process of forming threads on the stock, use is made of a thread rolling machine such as a flat die thread rolling machine, a round die thread rolling machine, etc. that will be usually used in forming metal screws.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a plastic screw-shaped molded article, particularly a lightweight plastic screw highly reinforced with single-reinforcement fibers and having corrosion resistance, chemical resistance, and electrical insulation properties. The present invention relates to a shaped molded article.

(Prior Art) Metal bolts are conventionally known as bolts. This is manufactured using the rolling method, which has the fastest production speed. Although metal bolts are made with such high productivity, they have the fatal disadvantage of being heavy and prone to rust. On the other hand, plastic bolts that are lightweight and have excellent corrosion resistance are already in practical use. However, plastic materials to which rolling can be applied are limited to non-fiber reinforced plastic materials such as hard vinyl chloride resin. This is because fiber-reinforced plastic materials have high strength, but have poor plastic deformability, and cannot be threaded by thread rolling, which requires plastic deformability. Even if this is forcibly rolled, the threads will not form a normal triangular shape, and the top of the triangle will become two threads, or a crank will occur in the threads. Therefore, not only does it have low strength and cannot be used as a screw, but it also absorbs water and chemicals through cracks, resulting in a decrease in chemical resistance.

On the other hand, bolts made by injection molding of resins such as vinyl chloride and polycarbonate have poor dimensional accuracy;
Bad for reinforcing fiber orientation. Therefore.

Bolts have low strength and can only be used for specific purposes such as decoration.

On the other hand, polyphenylene sulfide resin and its inorganic fiber reinforcement have an elastic modulus exceeding 1 xlO' kg/cffl, so they are promising as an alternative material for metal bolts, have excellent chemical resistance, and are heat resistant compared to thermoplastic resins. It has the advantage of high temperature.

However, it has a fatal drawback that it is not suitable for rolling processing because the reinforcing effect with fibers is small and it is brittle.

(Problems to be Solved by the Invention) An object of the present invention is to provide a plastic screw-shaped molded article that is lightweight, has corrosion resistance, chemical resistance, and electrical insulation properties, and is highly reinforced with reinforcing fibers. be. Another object of the present invention is to provide a high-strength plastic thread-shaped molded product by rolling, which is the most economical method for thread processing.

(Means for Solving the Problems) The plastic screw-shaped molded article of the present invention is mainly made of polyphenylene sulfide resin and inorganic reinforcing fibers.
The resin composition has a melt viscosity of 1×10 4 to 1×10 4 poise at a shear rate of 10”/sec at 0° C., thereby achieving the above object.

Polyphenylene sulfide (P
PS) Resins include 2, for example, Rydon BR-31,
There are Rydon P-4, Rydon P-6, etc. (both trade names, manufactured by @Philips Oil).

This is a crystalline chain polymer with a simple structure as shown below, and in an inert atmosphere, even at 100°C,
% of the polymer remains, the better the heat resistance is. The resin has excellent flame retardancy, chemical resistance, and dimensional stability: n is a natural number.The heat resistance of Rydon BR-31 is 1. For example, the heat distortion temperature is 260℃, and the UL temperature index is 200-240℃.
is displayed. Furthermore, it does not contain flame retardants and its flame retardancy is indicated by UL94 and V-015V. 2
There is no solvent that can dissolve it at temperatures below 00°C, and it has excellent chemical resistance. Regarding dimensional stability, this resin product has a high degree of crystallinity, and although it is a thermoplastic resin, it exhibits excellent dimensional stability, low water absorption, and excellent creep resistance. Mechanical strength and.

It also has excellent rigidity over a wide temperature range.

Furthermore, it has good fluidity and can be injection molded like general engineering plastics, giving it excellent moldability.

In order for the cylindrical or cylindrical material made of the resin composition of the present invention to be properly rolled, the melt viscosity of the resin material must be adjusted to a predetermined range before being formed into a cylindrical or cylindrical shape. It is necessary to expand the average molecular weight of the material.The melt viscosity is
sec, 1 x 104 to 1 x 106 poise, preferably 1.5 XIO' to 2 x 10' poise. If the viscosity is too low, the material obtained by molding will become brittle, and cracks will occur when the material is subjected to rolling processing. If the viscosity is too high, moldability will be significantly reduced.

Since the above-mentioned Rydon BR-31 as the polyphenylene sulfide resin of the present invention has a melt viscosity within the above-mentioned appropriate range, it can be subjected to the molding/rolling process without being subjected to thickening treatment. As polyphenylene sulfide resin,
When other resin grades such as Rydon P-4 and Rydon P-6 are used, the melt viscosity is adjusted by applying a thickening treatment such as heating in the presence of an enzyme to adjust the molecular weight distribution before molding. It is necessary to keep it within the above range.

The processing temperature for this varies depending on the thickness of the raw resin, but usually it is 250°C for 2 to 20 hours or 350°C.
Approximately 0.5 to 3 hours is appropriate.

If this heat treatment is performed after molding, the decomposed gas generated during thickening will leave bubbles in the molding material, making it impossible to produce a thread-shaped product with high strength.

Examples of reinforcing fibers constituting the resin composition together with the polyphenylene sulfide resin include 7.

Inorganic fibers such as glass fiber, carbon fiber, boron fiber, silicon carbide fiber; and
There are organic fibers such as aramid fibers. It is also possible to use a mixture of two or more of these fibers. There are no particular restrictions on the thickness and length of the fibers, as long as they can be dispersed in a thermoplastic resin molded into a columnar or cylindrical material. Usually, its diameter is several μm-
It is several tens of μm. Regarding the length, when long fibers are used, continuous long fibers are used, and when short fibers are used, chopped fibers cut into lengths of several ml to about 50 mm are used. These reinforcing fibers are mixed with a thermoplastic resin using a mixer such as a super mixer, and then kneaded and molded using an extruder or the like to form a cylindrical material.

The rolling method for rolling this cylindrical material to form threads does not need to be special, and a round die rolling machine is commonly used for forming threads on metal screws.

A rolling machine such as a flat die rolling machine can be applied.

(Example) The present invention will be explained below using examples.

Rydon P- as polyphenylene sulfide resin
4C@Philips Petroleum) was used.

This was heat-treated at 250° C. for 12 hours in a hot air dryer, and 60% by weight was triblended with 40% by weight of glass fiber, and formed into a round bar with a diameter of 9.0 mm using an extruder.

This was cut into a length of 10 cm to obtain a cylindrical material. J
Threads were formed on the cylindrical material using a two-roll rolling machine equipped with IS MloXl, 5 dies. The melt viscosity of the above raw material resin was determined as follows: Using a broken piece of the round bar obtained above, the apparent viscosity at 300°C was measured using a flow tester (CFT-500 manufactured by Shimadzu Corporation) by changing the load. Measure it.

Plot the apparent viscosity and apparent shear rate on a logarithmic graph, find the regression line using the least squares method, and calculate 102/SeC.
Calculate by interpolating the melt viscosity at . Also.

The tensile strength of the bolt obtained was determined by injection molding using two homogeneous resins as follows:
A hexagonal NAND base material with a height of 12 m and an inner diameter of 8.7 mm is formed, and this is cut with an MIO screw tap to obtain a MIO size nut. The above-mentioned bolt of the present invention was attached to this NAND, and the tensile strength was measured by the following test method. Measurements are the average of 5 volts each.

Tensile test: Attach nuts to both ends of the bolt.

The distance between the two nuts was 7011I. The nuts at both ends of the bolt were pulled using an autograph (15-5000 manufactured by Shimadzu Corporation) at a tensile speed of 5 mm/min, and the maximum load immediately before the bolt was broken was measured and determined as the tensile strength.

Example 2 The same as Example 1 except that the heat treatment time was 24 hours.

Error 2 The procedure was the same as in Example 1 except that the main heat treatment time was 6 hours.

The procedure was the same as in Example 1, except that the heat treatment temperature of the Daiseban soil was 350°C, the treatment time was 1 hour, and the resin was pulverized.

Failure to open l The same as Example 2 except that Rydon P-6 (@Philips Petroleum) was used as the resin.

Bloodless charcoal i This was the same as Example 1 except that Rydon BR-31 (@Philips Petroleum) was used as the resin, no heat treatment was performed, and no glass fiber was added.

Comparative Example 1 Same as Example 1 except that no heat treatment was performed.

Comparative Example 2 The same as Example 1 except that the heat treatment time was 48 hours.

Comparative Example 3 The same as Comparative Example 1 except that after being formed into a round bar, it was heat treated at 250°C for 12 hours.

Comparative Example 4 MI by injection molding using Rydon BR-31 resin
A bolt of O was formed.

The above results are shown in the table below.

(Effects of the Invention) According to the method of the present invention, a rod-shaped molded article made of polyphenylene oxide resin that is highly reinforced with glass fibers and has high strength and high fastening force can be obtained. Moreover, this thread-shaped molded body is manufactured by rolling, which is the most economical method for thread processing. Although the resin used is a thermoplastic resin, polyphenylene sulfide is strong and can withstand large plastic deformation during rolling because it has an expanded average molecular weight and has a melt viscosity within a specific range. This is because a cylindrical material was molded using resin and then rolled. This thread-shaped molded body is lightweight, corrosion resistant and
It also has the inherent characteristics of polyphenylene sulfide resin, such as chemical resistance, heat resistance, and electrical insulation properties. The thread-shaped molded body thus obtained is particularly useful for structural fastening.

that's all

Claims (1)

[Claims] 1. Mainly composed of polyphenylene sulfide resin and inorganic reinforcing fibers, shear rate at 300°C: 10^2/sec
．． A plastic screw-shaped molded article made of a resin composition having a melt viscosity of 1 x 10^4 to 1 x 10^6 poise. 2. The plastic screw-shaped molded article according to claim 1, wherein the columnar or cylindrical molded article of the resin composition is subjected to a rolling process.