JPH064300B2 - Manufacturing method of synthetic resin tube - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a synthetic resin tube having a relatively small diameter, which is used for various applications such as medical equipment, analytical equipment, and electrical equipment. .

[Conventional technology]

Conventionally, as a method for manufacturing a synthetic resin tube of this type, there is one disclosed in Japanese Patent Publication No. 56-44809.

This synthetic resin tube manufacturing method, after forming a heat-fusible resin film on the metal linear body, a heat-resistant resin coating is applied on it to form a baking film, and at least this coated linear body is formed. The metal linear body is stretched above the yield point of the metal linear body to lose the adhesion of the resin coating to the linear body, and then the metal linear body is pulled out.

[Problems to be Solved by the Invention]

However, in this manufacturing method, in the case of a combination of the metal linear body and the resin coating having good adhesion, there is a drawback that it is difficult to smoothly pull out the metal linear body, and the pulling out can be performed. Even if it does, distortion remains in the synthetic resin tube, and there is the inconvenience that the distortion must be eliminated by applying heat treatment.

For this reason, in the above-mentioned prior invention, a release agent such as silicone oil is applied to the surface of the metal linear body in advance.

However, in the case of a metal linear body coated with a release agent, it becomes difficult to apply the synthetic resin coating evenly in the next step, and a coating film of uniform thickness, and thus synthetic resin coating of uniform thickness There is a problem that the tube cannot be obtained.

In addition, the synthetic resin tube obtained by such a manufacturing method has a smooth inner surface. Therefore, when the insert is inserted into this tube, if the surfaces of the insert are smooth, the surfaces of the two stick to each other, and the insert cannot be inserted smoothly.

[Means for Solving the Problems]

In the present invention, a coating consisting of a silicone resin and an inorganic powder is applied on a metal linear body and baked to form a primary coating film, and then one or more synthetic resin coating materials are coated on the primary coating film. After coating and baking once or more to form a secondary coating film to obtain a coated linear body, bending is applied to the coated linear body to improve the adhesion between the secondary coating film and the primary coating film. The above problem was solved by removing the secondary coating film from the primary coating film by giving an elongation below the yield point to the metal linear body, and then removing the secondary coating film.

Hereinafter, the present invention will be described in detail.

FIG. 1 shows an example of a synthetic resin tube obtained by using the production method of the present invention. In the figure, reference numeral 1 indicates a synthetic resin tube obtained by using the production method of the present invention (hereinafter, simply referred to as a tube. It is abbreviated as.). The tube 1 has a two-layer structure including an inner layer 2 and an outer layer 3. Inner layer 2
A large number of fine protrusions 4 having a protrusion height of 0.01 to 100 μm, preferably 0.01 μm to 20 μm are formed on the inner surface thereof. An outer layer 3 is integrally provided on the inner layer 2.
The inner layer 2 and the outer layer 3 are made of polyimide, polyamideimide polyesterimide, polyesteramideimide,
Polyester, polyurethane, polyvinyl formal,
Polyvinyl butyral, polyethylene terephthalate,
It is made of synthetic resin such as phenoxy or polysulfone, and the inner layer 2 and the outer layer 3 are generally made of the same kind of synthetic resin. The tube 1 of this example has a double structure of the inner layer 2 and the outer layer 3, but naturally, it may have a single structure made of one kind of synthetic resin, and three or more layers having different kinds of synthetic resins may be used. The structure of the inner layer 2 made of polyimide and the outer layer 3 made of polyamide-imide can be used to obtain a tube having excellent heat resistance and abrasion resistance. The number of layers can be changed appropriately. Next, a method of manufacturing the tube 1 as shown in FIG. 1 using the manufacturing method of the present invention will be described.

First, a metal linear body made of a metal such as copper, aluminum, gold or silver is prepared. The metal linear body is not limited to have a circular cross-sectional shape, and may have a cross-sectional shape such as a square, rectangular, hexagonal, triangular or elliptical cross section.

Next, a coating consisting of a silicone resin and an inorganic powder is applied to the surface of the metal linear body and baked using an enamel baking oven or the like to form a primary coating film. The silicone resin here is not particularly limited, but methyl silicone, phenylmethyl silicone, phenyl silicone, etc. are used, and those having an elongation after baking of at least 30% or more are preferable. As the inorganic powder, calcium carbonate, silica, talc, clay, titanium oxide, gypsum, mica, iron oxide, diatomaceous earth, volcanic ash and the like are used, and the particle size thereof is in the range of 0.01 to 20 μm. To be elected. The ratio of the silicone resin to the inorganic powder in the paint is about 10 to 1000 parts by weight with respect to 100 parts by weight of the silicone resin. Further, in addition to aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, polyhydric alcohol derivatives such as ethylene glycol monoethyl ether, benzyl alcohol, and polar solvents such as N-methyl-pyrrolidone are used as solvents for this paint. The added one is used. This polar solvent causes aggregation, precipitation, and
It is blended so as to be uniformly dispersed in the paint without causing gelation or the like. The solid content of the silicone resin and the inorganic powder in the paint is about 30 to 80%.

The coating of this coating material on the metal linear body is performed by using an ordinary enamel coating die or the like. The thickness of the primary coating film after baking is preferably about 10 to 30 μm. And
Therefore, fine irregularities are formed on the outer surface of the primary coating film due to the presence of the inorganic powder and the polar solvent, and the surface is made non-adhesive or difficult to adhere due to the silicone resin.

Next, a synthetic resin coating material is applied on this primary coating film and baked to form a secondary coating film. As the synthetic resin coating used here, a synthetic resin coating such as polyimide, polyamide imide, polyester imide, polyester amide imide, polyester, polyurethane, polyvinyl formal, polyvinyl butyral, polyethylene terephthalate, phenoxy or polysulfone is used. The formation of this secondary coating film is performed by coating and baking the synthetic resin coating material one or more times to obtain a desired thickness. At this time, it is not limited to using the same synthetic resin coating material, but it is different. A synthetic resin paint can also be used. Similarly, the synthetic resin coating is applied using an enamel coating die, and an enamel baking furnace is used for baking.

Thus, a coated linear body having a resin coating composed of the primary coating film and the secondary coating film is obtained.

Next, the coated linear body is bent to reduce the adhesion between the primary coating film and the secondary coating film. The bending means is not particularly limited as long as it bends the covered linear body, but it is convenient to use a straightener or the like used for correcting a small bending tendency of the conductive wire.

Since the surface of the primary coating film is non-adhesive or difficult to adhere due to the bending, the adhesion between the primary coating film and the secondary coating film is considerably reduced.

Next, the secondary coating film is formed by making a cut in the circumferential direction at every predetermined length of the secondary coating film of the coated linear body in which the adhesion between the primary coating film and the secondary coating film is reduced. After cutting only the wire, the metal linear body is stretched below its yield point, the secondary coating film is peeled from the primary coating film, and the secondary coating film, that is, the tube is attached with the primary coating film. Remove from the metal filament. By making a cut in this secondary coating film, it is possible to prevent excessive elongation from being applied to the secondary coating film at the time of stretching the metal linear body in the next step.

As a method of giving elongation to the metal linear body below its yield point, for example, a method of lightly drawing the coated linear body through a drawing die or a method of drawing the coated linear body between compression rolls or the coated linear body A method is used in which both ends are wound around different bobbins an appropriate number of times, and the bobbin is rotated at different rotational speeds.One end of a fixed-length coated wire is fixed and the other end is simply pulled. Can also be adopted. About 1 to 20% is sufficient as the amount of elongation given to the metal linear body, and it is usually in the range of 2 to 10%. The reason why the secondary coating film peels off from the primary coating film due to such low elongation is that the adhesion between the secondary coating film and the primary coating film is lowered in the previous bending imparting step. .

According to such a manufacturing method, since only a slight elongation acts on the obtained tube, that is, the secondary coating film, there is no strain in the tube. Further, the fine projections on the surface of the primary coating film are transferred, and the fine projections are also formed on the inner surface of the tube. Further, since the primary coating film is formed between the metal linear body and the secondary coating film which becomes the tube, metal powder or the like does not adhere to the inner surface of the tube. Further, the fine protrusions on the surface of the primary coating film improve the wettability of the synthetic resin coating material that forms the secondary coating film, and the secondary coating film having a uniform thickness, that is, the tube is obtained. Furthermore, since the metal linear body to which the primary coating film adheres has a small elongation of several percent, it can be reused as it is.

〔The invention's effect〕

As described above, when a synthetic resin tube is manufactured by using the synthetic resin tube manufacturing method of the present invention, the synthetic resin coating film has a laminated structure in which one or more layers or two or more layers are laminated, and the inner surface thereof is A synthetic resin tube having fine protrusions is obtained. Such a synthetic resin tube,
When inserting an object such as a large number of optical fibers into the tube, it can be inserted very smoothly.
Further, by selecting the synthetic resin coating film, it is possible to appropriately obtain a wide range of properties (mechanical properties, thermal properties, electrical properties, etc.).

Further, the method for producing a synthetic resin tube according to the present invention comprises applying a coating material comprising a silicone resin and an inorganic powder onto a metal linear body and baking it to form a primary coating film, and then forming a primary coating film on the primary coating film. After coating one or more kinds of synthetic resin coatings on the above once and baking to form a secondary coating film to obtain a coated linear body, the coated linear body is bent to form a secondary coating film. The adhesiveness with the primary coating film is lost, and then the linear coating is stretched below its yield point to separate the secondary coating film from the primary coating film, and then the secondary coating film is extracted. Therefore, it is possible to obtain a synthetic resin tube having a uniform thickness, no residual strain, no adhesion of foreign matter such as metal powder, and fine protrusions formed on the inner surface.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a synthetic resin tube obtained by using the manufacturing method of the present invention. 1 ... Synthetic resin tube, 2 ... Inner layer, 3 ... Outer layer,
4 ... Fine protrusions.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location // B29L 23:22 4F (72) Inventor Shigeru Amano 9-1 Futabacho, Numazu City, Shizuoka Prefecture Fujikura Electric Wire Co., Ltd. Company Numazu Factory (56) Reference JP-A-60-220726 (JP, A) JP-A-62-163513 (JP, A) Actual development Sho-63-17511 (JP, U)

Claims (1)

[Claims] 1. A linear coating material comprising a silicone resin and an inorganic powder is applied onto a metal linear body and baked to form a primary coating film. Then, one or more synthetic resin coating materials are formed on the primary coating film. 1
After coating and baking more than once to form a secondary coating film to obtain a coated linear body, bend the coated linear body to lose the adhesion between the secondary coating film and the primary coating film. A method for producing a synthetic resin tube, characterized in that the secondary coating film is removed after the secondary coating film is peeled off from the primary coating film by giving an elongation below the yield point to the metal linear body, and then pulling the secondary coating film.