JPS60199635A - Screw-shaped plastic molding and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a lightweight screw-shaped plastic molding anticorrosive, chemical resistant and electrically insulating with a high strength by crosslinking polyamide with a disintegrating polymer with the irradiation of radiation to lower hygroscopicity. CONSTITUTION:Polyamide (nylon or the like) and a disintegrating polymer (poly- 4-ethylene fluoride or the like) are mixed evenly in the form of a pellet or powder and for example, non-organic reinforcing fiber such as glass fiber and carbon fiber, a filling agent and various additives such as a treating agent for improving the adhesivity with fiber are added thereto as required. Such a plastic material undergoes an injection molding and extrusion molding in the shape of a bolt, for instance, and molded into a mere cylindrical material and rolled to mold a thread. When the threaded molding is irradiated with radiation, the main chain of the disintegrating polymer is cut off and the molding is crosslinked with an amide group to inhibit the water absorptibity of the molding resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a reinforced plastic thread-shaped molded article mainly composed of a crosslinked polymer and a method for producing the same.

(Conventional technology) Examples of thread-shaped molded objects such as bolts include 2.

Metal bolts have been known for a long time. This is manufactured by the rolling method, which has the fastest production speed for thread processing. Although metal bolts are manufactured with high productivity, they have the fatal disadvantage of being heavy and prone to rust. In contrast, bolts are being produced that are made from plastic, which is lightweight and has excellent corrosion resistance. However, generally vinyl chloride,
Bolts made by injection molding thermoplastic resins such as polycarbonate have low strength and can only be used for specific purposes such as decoration. Among thermoplastic resins, hard vinyl chloride, polyamide, and the like are relatively hard. In particular, polyamides such as nylon 6, nylon 6.6°, and nylon MXD6 are engineering plastics that have excellent properties such as toughness, self-lubricity, oil resistance, and chemical resistance. When reinforcing fibers such as glass fibers are added, even better reinforcing effects can be achieved. Therefore, a high quality bolt with the above properties is obtained.

However, polyamide has high water absorption, and when it comes into contact with water, acids, or bases, the hydrogen bonds between amide bonds are broken, resulting in a significant decrease in strength. Dimensions also change.

Therefore, thread-shaped molded bodies made using polyamide cannot be said to have sufficient dimensional accuracy and strength.

The following measures can be considered to improve these properties of polyamide. ■Mixing hydrophobic resin. ■ Forming a hydrophobic film such as Teflon or polymethyl methacrylate on the surface of polyamide. ■Increase the crystallinity of polyamide. Even if the measure (2) is taken, the polyamide and the hydrophobic polymer are not mixed completely uniformly, and an interface is formed between the two, resulting in a decrease in mechanical strength. No improvement in water resistance was observed. In method (2), the adhesion between the hydrophobic resin coating and the polyamide base material is poor, and the coating is easily peeled off. When method (2) is used, a certain degree of effect is observed on both the strength and water absorption of the material, but it is still insufficient when producing thread-shaped molded bodies such as bolts.

(Object of 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, electrical insulation properties, and high strength, and a method for manufacturing the same. Another object of the present invention is to provide a plastic screw-shaped molded article whose strength does not decrease and its dimensions do not change even when it comes into contact with water, acids, bases, etc., and a method for manufacturing the same.

(Structure of the Invention) The plastic screw-shaped molded article of the present invention is mainly composed of a resin composition containing a crosslinked polymer obtained from a polyamide and a collapsible polymer, thereby achieving the above object. Furthermore, the method for producing a plastic thread-shaped molded body of the present invention includes a step of molding a plastic material mainly containing polyamide and a collapsible polymer to obtain a molded body.
and a step of irradiating the molded body with radiation, thereby achieving the above object. The term "thread-shaped molded body" as used in the present invention refers to a molded body having threads made of a resin composition obtained by irradiating a plastic molded body with radiation and crosslinking the molded body. Specifically, Bolt and Nando's.

The polyamide used in the present invention includes nylon 6, nylon 6/6, which is commonly used as a thermoplastic resin. Nylon 12. There are resins that have an amide bond in their main chain, such as nylon MXD6. The collapsible polymer of the present invention is a polymer that has the property that the carbon-carbon bonds in the main chain are severed when irradiated with radioactivity. It is preferred that the G-value for collapse of the collapsible polymer exceeds the G-value for crosslinking. Such collapsible polymers include fluororesins such as poly-4-fluoroethylene, poly-4-fluoroethylene/ethylene copolymer, polyvinylidene fluoride, polypropylene, and polyisobutylene. Two or more types of disintegrating polymers and polyamides can also be used as a mixture. The disintegrating polymer is contained in an amount of 1 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the polyamide.

If it is too small, the resulting molded product will have poor water resistance, and if it is too large, its strength will be reduced.

The above-mentioned polyamide and collapsible polymer are uniformly mixed in the form of pellets or powder, and further, if necessary, inorganic reinforcing fibers are added. Examples of inorganic reinforcing fibers include glass fiber, carbon fiber, boron fiber, and silicon carbide fiber. It is also possible to use a mixture of two or more of these fibers. There are no particular restrictions on the length of the fibers, as long as they can be sufficiently kneaded and dispersed with the polyamide. Furthermore, if necessary,
A treatment agent that improves adhesion with fillers and fibers.

Various additives such as flame retardants and antioxidants may be added.

The plastic material prepared in this way.

It is formed into a threaded molded body such as a bolt or nut by an appropriate means. For example, plastic materials are
It is molded into a bolt using a regular molding machine such as bolt-shaped injection molding or extrusion molding. Alternatively, it is formed into a cylindrical material using an injection molding machine or an extrusion molding machine that molds a simple cylindrical material, and the resulting cylindrical material is rolled to form a threaded thread.

The rolling method does not need to be special; a round die rolling machine is usually used for thread-shaping processing of metal screws.

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

When this threaded molded article is irradiated with radiation, the main chain of the collapsible polymer is cut, and a crosslinking reaction similarly proceeds between the collapsible polymer and the polyamide. Since the amide groups of the polyamide are crosslinked by this reaction, the water absorption of the resulting thread-shaped molded resin is suppressed. Furthermore, since the resin has a network structure, the mechanical strength of the resulting thread-shaped molded product is not impaired. As the radiation, gamma rays and electron beams are preferable.

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

To 100 parts by weight of nylon 6.6 (Nyalamine manufactured by Toshi Co., Ltd.) as a polyamide, 1 part by weight of 4-fluorinated ethylene/ethylene copolymer as a collapsible polymer and 101 parts by weight of glass fiber were added and melted and mixed. A cylindrical material with a diameter of 8.7 fl was molded using an extrusion molding machine. This was rolled to form a thread, and then 2.5 Mrad of gamma rays was irradiated. The tensile strength of the obtained bolt was measured. This bolt was immersed in hot water at 60° C. for 168 hours, and the water absorption rate was calculated from the change in weight. Furthermore, the tensile strength after immersion was measured. The respective values are shown in Table 1.

Example 2 The same as Example 1 except that 5 parts by weight of the 4-fluorinated ethylene/ethylene copolymer and 105 parts by weight of glass fiber were used.

10 parts by weight of 4-fluorinated ethylene/ethylene copolymer,
Example 1 except that 110 parts by weight of glass fiber was used.
It is similar to

Daishiran↓ 20 parts by weight of 4-fluorinated ethylene/ethylene copolymer,
Example 1 except that 120 parts by weight of glass fiber was used.
It is similar to

30 parts by weight of Ohata isolated 4-fluorinated ethylene/ethylene copolymer;
Example 1 except that 130 parts by weight of glass fiber was used.
It is similar to

50 parts by weight of Daito Jiko 4-fluorinated ethylene/ethylene copolymer,
Example 1 except that 150 parts by weight of glass fiber was used.
It is similar to

The procedure was the same as in Example 4 except that vinylidene fluoride was used as the disintegrating polymer.

Otsuki Bakugou The same procedure as Example 4 was used except that polyisobutylene was used as the disintegrating polymer.

The procedure was the same as in Example 4 except that polypropylene was used as the disintegrating polymer.

The procedure was the same as in Example 1 except that the 4-fluorinated ethylene/ethylene copolymer was not used and 100 parts by weight of glass fiber was used. The results are shown in Table 2. The results of the comparative examples are all shown in Table 2 below.

60 parts by weight of 几M3LL 4-fluorinated ethylene/ethylene copolymer,
Example 1 except that 160 parts by weight of glass fiber was used.
It is similar to

The procedure was the same as in Example 1 except that the main gamma ray was not irradiated.

The procedure was the same as in Example 2 except that γ-rays were not irradiated.

Comparison Example 3 was the same as Example 3 except that γ-rays were not irradiated.

Comparison 1 Same as Example 4 except that γ-rays were not irradiated.

The procedure was the same as in Example 5 except that the Hokkai Tanko gamma rays were not irradiated.

Example 6 is the same as Example 6, except that the sample was not irradiated with gamma rays.

(The following is a blank space) (Effects of the Invention) According to the present invention, as described above, since the polyamide and the collapsible polymer are crosslinked by radiation irradiation, the hygroscopicity of the thread-shaped molded product obtained is extremely low.

The same applies to acids and alkalis. therefore.

Even when this molded body comes into contact with water, acid, or alkali, its strength does not decrease and not even a single dimensional change occurs. The thread-shaped molded body has all the characteristics that plastics generally have, such as being lightweight and highly corrosion resistant. This molded body can also be obtained by the most economical rolling method.

that's all Applicant: Sekisui Chemical Co., Ltd.

Claims (1)

[Scope of Claims] 1. A plastic screw-shaped molded article made of a resin composition containing a crosslinked polymer obtained mainly from polyamide and a collapsible polymer. 2. The molded article according to claim 1, wherein the collapsible polymer is contained in a proportion of 1 to 50 parts by weight based on 100 parts by weight of the polyamide. 3. The molded article according to claim 1, wherein the resin composition contains inorganic reinforcing fibers. 4. The molded body according to claim 1, wherein the screw-shaped molded body is a bolt or a nand. 5. A method for producing a plastic screw-shaped molded body, which includes the steps of molding a plastic material mainly containing polyamide and a collapsible polymer to obtain a molded body, and irradiating the molded body with radiation. 6. The method according to claim 5, wherein the collapsible polymer is contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the polyamide. 7. The method according to claim 5, wherein the resin composition contains inorganic reinforcing fibers. 8. The method according to claim 5, wherein the threaded molded body is a bolt or a slot.