JPH0414059B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a plastic rolled body such as a plastic bolt, and in particular to a plastic rolled body highly reinforced with ceramic whiskers and a method for manufacturing the same. (Prior Art) Well-known metal bolts made from resin are usually manufactured by the rolling method, which has the fastest production speed for thread processing. Although metal bolts are manufactured with such high productivity, they have the fatal disadvantage of being heavy and prone to rust. In contrast, bolts are manufactured using plastic, which is lightweight and has excellent corrosion resistance. For example, Japanese Patent Publication No. 48-9477 discloses a fiber-reinforced plastic bolt that is made of a thermosetting resin but also 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. This bolt has threads formed by cutting, so
The reinforcing fibers are cut and a notch effect occurs on the threads, making it impossible to obtain sufficient thread strength. (Object of the Invention) An object of the present invention is to provide a plastic rolled body that is lightweight, has corrosion resistance, chemical resistance, and electrical insulation properties, and is highly reinforced with a reinforcing material. Another object of the present invention is to provide a method for manufacturing a plastic rolled body such as the above-mentioned plastic bolt by the most economical thread rolling process. (Structure of the Invention) The plastic rolled body of the present invention is composed of a plastic material mainly composed of a thermoplastic resin, and has ceramic whiskers dispersed at least in the surface layer, thereby achieving the above object. Furthermore, the method for producing a rolled plastic body of the present invention includes rolling a cylindrical material made of a plastic material mainly composed of a thermoplastic resin and having ceramic whiskers dispersed in at least the surface layer to form a thread. , thereby achieving the above objective. In the present invention, the plastic rolled body also includes a rod-shaped body having a male thread on its outer surface and a tubular body having a female thread on its inner surface. The ceramic whisker used in the present invention is a fine powder of an inorganic substance exhibiting needle-like crystals. Examples of the inorganic materials include potassium titanate and boron oxide, and two or more kinds can be used in combination. This ceramic whisker has a diameter of 0.1
~3 μm, with a length of 5-50 μm. As the thermoplastic resin, resins that can be melt-molded such as polyethylene terephthalate, polycarbonate, polypropylene, and nylon are used. The plastic material mainly consists of this thermoplastic resin, and reinforcing fibers other than the ceramic whiskers are added as necessary. Examples of the reinforcing fibers include inorganic fibers such as glass fiber, carbon fiber, boron fiber, and silicon carbide fiber, and organic fibers such as aramid fiber. It is also possible to use a mixture of two or more of these fibers. Fibers usually have a diameter of several μm to several tens of μm, and a length of several tens of μm to several 100 μm.
It is m. The amount of reinforcing fiber mixed is selected depending on the strength of the bolt to be obtained, but is usually 50% by volume.
It is as follows. If it exceeds this value, the reinforcing effect will actually decrease, making it difficult to perform rolling. For the purpose of improving the adhesion between the reinforcing fibers and the thermoplastic resin, various additives such as processing agents, flame retardants, and antioxidants may be added as necessary. Plastic materials are thus prepared by adding the other reinforcing fibers and various additives to the thermoplastic resin, if necessary. This is further melted and mixed with ceramic whiskers to form the desired cylindrical material. The plastic material and the ceramic whisker are melted and mixed by extrusion molding, injection molding, or the like to form a cylindrical material. The diameter of this cylindrical material is preferably approximately an intermediate value between the thread diameter and the root diameter of the finally obtained thread. When ceramic whiskers are contained only in the surface layer, as shown in FIG.
Multi-layer molding is carried out using two extruders 1 and 2 and a crosshead die 3. When the extruded product 5 obtained through the cooling mold 4 is cut into appropriate lengths, a multilayer cylindrical material 8 shown in FIG. 2a is obtained. This laminated cylindrical material 8 has an inner layer 7 and a surface layer 6,
Ceramic whiskers are dispersed in at least the surface layer 6. When one extruder 2 is stopped and molding is performed only with the other extruder 1, a single-layer cylindrical material 10 shown in FIG. 2b is obtained. In this case, the ceramic whiskers are distributed over the entire area of the cylindrical material 8. The thickness of the surface layer 6 in FIG. 2a is at least half the height of the thread of the screw to be obtained. Ceramic whiskers are contained in an amount of 2 to 50% by volume, preferably 4 to 40% by volume, in the portion dispersed in the plastic material. If it is less than 2% by volume, the plastic deformability will be poor, and if it is more than 50% by volume, the cylindrical material to be formed will become brittle. In either case, a sufficiently strong thread cannot be formed. As described above, since ceramic whiskers are extremely strong fine fibers, the synthetic resin layer in which they are mixed and dispersed is easily plastically deformed by rolling processing, and the ceramic whiskers themselves are easily deformed by the deformation force during processing. It will orient itself along the deformation without breaking even if it is bent. Therefore, the resulting thread has significantly superior strength. Additionally, ceramic whiskers have the effect of reducing frictional resistance on the threaded surface.
The reusability of the bolt is also improved. The rolling method employed in the thread processing of the present invention does not need to be special, and two-roll rolling machines, three-roll rolling machines, flat die rolling machines, etc. that are commonly used for thread forming processing of metal screws can be used. used. These have metal rolls or plates with thread grooves machined into their surfaces. When these rolls or plates are placed facing each other, a cylindrical material is held between them, and pressed while rotating in the case of a roll rolling machine or while vibrating relative to each other in the case of a flat die rolling machine, a thread is formed. A rolled bolt 11 as shown in is obtained. (Example) The present invention will be described below with reference to Examples. Example 1 100 parts by volume of polycarbonate were charged to a first extruder. On the other hand, the second extruder contains polycarbonate
100 parts by volume (hereinafter, parts indicate parts by volume) and 2 parts of potassium titanate fiber (manufactured by Otsuka Chemical Co., Ltd.: Teismo) were charged. The kneaded material from the first extruder is supplied to the center of the crosshead die, and the kneaded material from the second extruder is supplied to the circumference of this crosshead die, so that the inner layer has a diameter of 8 mm and a surface layer has a thickness of 0.5 mm. A cylindrical material of mm was obtained. This cylindrical material was rolled using an M10 bolt rolling die to obtain a bolt with a length of 60 mm. The shape of the thread of the obtained bolt was observed and the tensile strength was measured. The results are shown in Table 1. Example 2 Same as Example 1 except that 4 parts of potassium titanate fibers were used. Example 3 Same as Example 1 except that 10 parts of potassium titanate fibers were used. Example 4 The same as Example 3 except that the diameter of the inner layer of the cylindrical material was 7.4 mm, and the thickness of the surface layer was 0.8 mm. Example 5 Same as Example 3 except that polyethylene terephthalate was used instead of polycarbonate. Example 6 Same as Example 3 except that nylon 6.6 was used instead of polycarbonate. Example 7 The same as Example 3 except that 10 parts of potassium titanate fibers were charged together with polycarbonate into the first extruder. Example 8 The same as Example 3 except that 30 parts of glass fiber (diameter 13 μm, length 3 mm) was charged together with polycarbonate into the first extruder. Example 9 100 parts of polycarbonate, 30 parts of glass fiber and 10 parts of potassium titanate were charged into a first extruder,
A cylindrical material with a diameter of 9 mm was obtained without using the second extruder. Thereafter, bolts were manufactured and tested in the same manner as in Example 1. Example 10 Same as Example 9 except that potassium titanate was changed to 50 parts. Comparative Example 1 A cylindrical material having a diameter of 9 mm was obtained using only polycarbonate. Thereafter, bolts were manufactured and tested in the same manner as in Example 1. Comparative Example 2 A cylindrical material with a diameter of 9 mm was obtained using only polyethylene terephthalate. Thereafter, bolts were manufactured and tested in the same manner as in Example 1. Comparative Example 3 A cylindrical material with a diameter of 9 mm was obtained using only nylon 6.6. Thereafter, bolts were manufactured and tested in the same manner as in Example 1. Comparative Example 4 Same as Example 1 except that 1 part of potassium titanate fiber was used. Comparative Example 5 The same as Example 2 except that the diameter of the inner layer of the cylindrical material was 8.4 mm and the thickness of the surface layer was 0.3 mm. Comparative Example 6 A cylindrical material with a diameter of 9 mm was obtained using 100 parts of polycarbonate and 60 parts of potassium titanate fiber. Thereafter, bolts were manufactured and tested in the same manner as in Example 1.

【table】

[Table] (Effects of the Invention) According to the present invention, ceramic whiskers are dispersed in at least the surface layer of the cylindrical material made of plastic material, so that it can be rolled regardless of the type of thermoplastic resin. It is easy to form threads by forming, and the resulting threads have excellent strength. Thread forming is highly productive through rolling, so thread-shaped molded bodies such as bolts can be produced economically. Moreover, the thread shape of the obtained plastic rolled body is good, and the top of the thread does not form two threads or crack or break. Since the ceramic whiskers are oriented along the direction of rolling without being cut during rolling, the strength of the thread is high and the thread surface has good sliding properties. Moreover, it has all the characteristics inherent to plastic materials, such as being lightweight and highly corrosion resistant.

[Brief explanation of drawings]

Fig. 1 is a front view of essential parts showing an example of an extruder used in the present invention, Fig. 2a is a partial perspective view showing an example of a formed laminated cylindrical material, and Fig. 2b is a formed monolayer FIG. 3 is a partial perspective view showing an example of a cylindrical material, and FIG. 3 is a partial perspective view of an example of a rolled bolt. 1, 2...Extruder, 3...Crosshead die,
5...Extrusion molded product, 6...Surface layer of multilayer cylindrical material, 7...Inner layer of multilayer cylindrical material, 8...Multilayer cylindrical material, 10...Single layer cylindrical material, 11... ...Rolled bolt.

Claims (1)

[Scope of Claims] 1. A rolled plastic body made of a plastic material mainly composed of a thermoplastic resin and having ceramic whiskers dispersed in at least its surface layer. 2. The rolled body according to claim 1, wherein the plastic material contains ceramic whiskers as well as other reinforcing fibers. 3. The rolled article according to claim 2, wherein the other reinforcing fiber is at least one of glass fiber, carbon fiber, boron fiber, silicon carbide fiber, and aramid fiber. 4. A method for manufacturing a plastic rolled body, which includes rolling a cylindrical material made of a plastic material mainly composed of a thermoplastic resin and having ceramic whiskers dispersed in at least the surface layer to form a thread. 5. The method of claim 4, wherein the plastic material contains ceramic whiskers as well as other reinforcing fibers. 6. The method according to claim 5, wherein the other reinforcing fiber is at least one of glass fiber, carbon fiber, boron fiber, silicon carbide fiber, and aramid fiber.