JPS60199634A - Screw-shaped plastic molding with film containing fluorine and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a lightweight, anticorrosive, chemical resistant and electrically insulating screw-shaped plastic molding with a protective and reinforcing film on the surface thereof by forming a waterproof film containing fluorine on the surface of a resin material mainly composed of polyamide. CONSTITUTION:Inorganic reinforcing fiber such s glass fiber and carbon fiber, filling agent and various additives such as a treating agent for improving the adhesivity with fiber are added to polyamide such as nylons 6 and 6 as required. Such a plastic material is formed into a cylinder by injection molding, extrusion molding or the like and rolled to form a thread. Then, the screw-shaped molding thus obtained is brought into contact with a fluorine gas to react with the polyamide to obtain a firm water resistant film containing fluorine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technology, Field) The present invention relates to a reinforced plastic screw-shaped molded article having a water-resistant fluorine-containing coating on its surface 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 using the rolling method, which has the fastest production speed. Although metal bolts are made with high productivity,9 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. Japanese Patent Publication No. 48-9477 discloses a fiber-reinforced plastic bolt that is made of a thermosetting resin but contains reinforcing fibers such as glass. However, the material of the bolt disclosed herein is a unidirectionally reinforced material, and does not have sufficient strength as a bolt subjected to multiaxial stress. Since the threads of this bolt are formed by cutting, one of the reinforcing fibers is cut and a notch effect occurs in the threads, making it impossible to obtain sufficient thread strength.

By the way, when rolling a plastic cylindrical body to form a bolt, the plastic materials to which rolling can be applied are limited to hard vinyl chloride resin, polyamide, and the like. In particular, polyamides such as nylon 6, nylon 6.6, and nylon MX06 are engineering plastics that are tough and have excellent properties such as self-lubricating properties, 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.

(Object of the Invention) The 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 has a protective and reinforcing film on its surface, and a method for manufacturing the same. be. 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. Still another object of the present invention is to provide a method for producing the above-mentioned high-strength plastic thread-shaped molded body by rolling, which is the most economical method for thread processing.

(Structure of the Invention) The plastic screw-shaped molded article of the present invention is made of a plastic material mainly composed of polyamide and has a water-resistant fluorine-containing film on two surfaces, thereby achieving the above object.

Furthermore, the method for producing a plastic screw-shaped molded body of the present invention includes contacting a screw-shaped molded body obtained by rolling a cylindrical material made of a plastic material mainly composed of polyamide with fluorine gas; The above objective is achieved.

The polyamide used in the present invention includes nylon 6, nylon 6/6, which is commonly used as a thermoplastic resin. Examples include nylon MXD6. Inorganic reinforcing fibers are added to this polyamide as necessary. 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 is no particular limit to the length of the fibers, as long as they can be sufficiently kneaded and dispersed with the polyamide.

If necessary, filler is added to the polyamide.

Various additives may be added, such as processing agents, flame retardants, and antioxidants to improve adhesion to fibers. Plastic materials prepared in this way can be used for injection molding.

It is molded into a cylindrical material using a regular molding machine such as extrusion molding. This cylindrical material is rolled to form a thread. The rolling method used in the present invention does not need to be special, and rolling machines such as a round die rolling machine and a flat die rolling machine that are commonly used for internal thread forming of metal screws can be applied.

When the screw-shaped molded product thus obtained is brought into contact with fluorine gas, the fluorine gas reacts with the polyamide to form a fluorine-containing film. When the thread-shaped molded body is, for example, a bolt, (a) 6 at room temperature in a 10% fluorine gas atmosphere.
A strong water-resistant fluorine-containing film can be obtained by allowing the film to stand for 0 minutes or (b) for 120 minutes at 80° C. in a 2% fluorine gas atmosphere.

The concentration of fluorine gas, the temperature and time of contact with fluorine gas are appropriately selected depending on the material and size of the thread-shaped molded body. The concentration of fluorine gas is adjusted by adding an inert gas (usually nitrogen gas). If the concentration of fluorine gas is too high or the contact time is too long, the main chain of the polyamide may be severed.

Moreover, fluorine gas penetrates into the resin.

When reinforcing fibers are contained, the adhesion strength between the two reinforcing fibers and the polyamide decreases, making it impossible to obtain a bolt with the desired strength.

It is preferable that the fluorine gas concentration C (%) 3 reaction temperature T (''C) and reaction time t (minutes) satisfy the following formula.

300<C-e'・t<2000 where e is a natural number.

When carried out under conditions satisfying such a formula, a fluorine-containing polyamide layer with a thickness of 0.5 to 10 μm is formed on the surface of the polyamide. When using MIO bolts, the original strength can be maintained and the water absorption rate can be reduced to 20-70%.

Note that the thread-shaped molded body mentioned here refers to bolts, nuts, etc. that have threads.

(Example) The present invention will be described below with reference to Examples.

50 parts by weight of glass fibers (diameter 13 μm, length 30) were mixed with Daitachi Masudo nylon 6.6 resin (manufactured by Toshi Co., Ltd.: Amilan) and molded into an extruded rod having a diameter of 9 cranes using an extrusion molding machine.

This was cut to a length of 8CI11 to obtain 85 cylindrical materials. This cylindrical material was subjected to threading using a rolling machine equipped with an MIO threading die. Obtained MIO
Five of the bolts were placed in a cylinder with an inner diameter of 5 cm and a length of 15 cm. Fluorine gas diluted to 10% by weight with nitrogen was contacted for about 60 minutes at about 20°C. The gas flow rate is 65ml/min for fluorine gas and 800ml/min for nitrogen gas.
It was 1.7m3n. The resulting bolts had an average weight increase of 0.12%. After this bolt was immersed in hot water at 60° C. for 168 hours, the amount of water absorbed was measured. Attach nuts to both ends of the bolt after soaking to meet JIS B-
A tensile test was conducted according to the test method of No. 1051, and the breaking strength was measured.

The water absorption amount and tensile strength are the average values of five samples shown in the table below. Furthermore, the values of C and eW ·t are also shown in the table below.

The concentration of fluorine gas is 4.1% (flow rate of fluorine gas: 25%).
It is the same as Example 1 except that it was set as m 12 /min, ).

Example 3 Fluorine gas concentration was 23% (fluorine gas flow rate: 180
It is the same as Example 1 except that mβ/min, ) was used.

The procedure was the same as in Example 1 except that the Oarashi dish reaction time was 120 minutes.

Dry plate 1 Same as Example 1 except that the reaction time was 25 minutes.

Reaction temperature: 80°C 2: Reaction time: 120 minutes, fluorine gas concentration: 2% (fluorine gas flow rate = 12 m Il/mi
It is the same as Example 1 except that it is set to n.

Lost Storm 1 Fluorine gas concentration 4.1% (Fluorine gas flow rate 25 m)
This is the same as in Example 6 except that A'/win, ).

The concentration of fluorine gas was set to 0.67% (fluorine gas flow rate 4
It is the same as Example 6 except that m It /#+in, ).

Extraction 1 Same as Example 6 except that the reaction time was 240 minutes.

Example 10 Same as Example 6 except that the reaction time was 40 minutes.

The concentration of fluorine gas in Su 11 is 2% (flow velocity of fluorine gas: 12 m!
It is the same as Example 1 except that it is set to /min, ).

■ Reduce the concentration of fluorine gas to 30% (flow rate of fluorine gas = 250
It is the same as Example 1 except that mβ/min, ) was used.

The procedure was the same as in Example 1 except that the reaction time was 240 minutes.

Daiarashimasu U Same as Example 1 except that the reaction time was 10 minutes.

The procedure was the same as in Example 1 except that the reaction temperature was 80°C.

Stop comparison ■ Top rolled bolts were subjected to each test as they were without contacting with fluorine gas. The rolled bolt was dried, its weight was measured, and the amount of water contained in the rolled bolt was calculated. The value is shown in the water absorption section of the table below.

The fork-rolled port was immersed in hot water at 60° C. for 168 hours without contacting with fluorine gas, and the water content was measured. Furthermore, this was subjected to a tensile test. The results are shown in the table below.

(The following is a blank space) (Effects of the Invention) According to the present invention, since the surface of the thread-shaped molded body mainly made of polyamide is fluorinated, its hygroscopicity is extremely low. The same applies to acids and alkalis.

Therefore, even if this molded body comes into contact with water, acid, or alkali, the strength will not decrease and not even a single dimensional change will occur. The thread-shaped molded body has all the characteristics inherent in plastic materials, such as being lightweight and having high corrosion resistance. This molded body can be obtained by the most economical rolling method.

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

Claims (1)

[Claims] 1. Made of plastic material mainly composed of polyamide 2.
A plastic screw-shaped molded product with a water-resistant fluorine-containing film on its surface. 2. The molded article according to claim 1, wherein the plastic material contains inorganic reinforcing fibers. 3. A method for manufacturing a plastic screw-shaped molded body having a fluorine-containing film, which includes contacting a screw-shaped molded body obtained by rolling a cylindrical material made of a plastic material mainly composed of polyamide with fluorine gas. 4. The method according to claim 3, wherein the plastic material contains inorganic reinforcing fibers.