JPS6056619B2 - Flexible tube and method for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flexible tube, and more particularly relates to an improvement in a flexible tube having internal lubricity and having the outer surface of a porous tube coated with polytetrafluoroethylene (hereinafter abbreviated as PTFE). It is something.

Porous tubes made of PTFE have extremely excellent heat resistance and chemical resistance, and also exhibit unique surface properties such as an extremely small coefficient of friction and water repellency. Upper, porous 4 upper - beware A,
LLL゛→μ, |1■! ■lJ7-↓As it has characteristics completely different from non-porous tubes, its use is opening up in a wide variety of fields.

Although this porous nature is advantageous for applications where the purpose is the permeation of gas or liquid, conversely, permeation of fluid may hinder the use of the tube. Furthermore, when the tube is bent to a small diameter, buckling occurs, often making it impossible to maintain the cylindrical shape, and tearing in the tube axis direction may also occur, which poses an obstacle to the practical use of porous PTFE tubes. There is. The present invention solves these problems by providing a flexible tube having a structure in which fibers are spirally arranged on the outer surface of a porous PTFE tube, and an elastomer coating is bonded to the outer surface of the structure. It is something.

In the flexible tube of the present invention, the elastomer coating is P
The purpose is to provide airtightness without losing the flexibility of the TFE porous tube, and the spirally arranged fibers are oriented so that they do not easily buckle even when the tube is bent to a small diameter. This also has the purpose of preventing the tube from tearing in the axial direction. In addition, since the inner surface of the flexible tube of the present invention is formed solely of porous PTFE, the surface friction coefficient is very small and the sliding property is good. It also has the advantage that the coating does not peel off even if the tube is bent repeatedly because it penetrates into the porous space on the outer surface of the tube and is physically firmly bonded. These are also features of the present invention. In order to manufacture the PTF'E porous tube used for the purpose of the present invention, the method described in Japanese Patent Publication No. 13560/1984 can basically be used.

First, a liquid lubricant is mixed with the 100 FE unsintered powder and extruded into a tube using a ram extruder. The tube is stretched in at least one axis with or without removing the liquid lubricant from the tube. A porous PTFE tube with improved strength can be obtained by sintering and fixing the elongated structure heated above the sintering temperature of 32 rc in a heat shrinkage-prevented state. Here, the state of preventing heat shrinkage includes not only a state where shrinkage is completely prevented but also a state where some shrinkage is allowed. This PTFE porous tube has a fine fibrous structure consisting of very thin fibers and nodes interconnected by the fibers, and the fiber diameter and length, the size of the nodes, and their number vary depending on the stretching. Since they can be changed depending on the sintering conditions, the pore diameter and porosity of the resulting porous body can also be freely determined. Therefore, the flexibility varies, so a tube with appropriate porosity may be selected depending on the purpose. Next, fibers are provided in a spiral on the outer surface of the PTFE porous tube.

The fiber for this purpose is 32, which is the sintering temperature of PTFE.
Materials that can be heat set at temperatures below 7°C are suitable. Examples of such materials include fluororesin, polyester, polyamide, polypropylene, polyethylene, polyvinylidene chloride, polyvinyl chloride, and polyurethane. Examples of fluororesins include:
Examples include polytetrafluoroethylene, polytrifluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, and copolymers thereof. As a copolymer. Examples include copolymers of tetrafluoroethylene and vinylidene fluoride, hexafluoropropylene, perfluoroalkyl vinyl ether, ethylene, etc., and copolymers of chlorotrifluoroethylene and ethylene. The shape of the fibers may be either monofilament or multifilament; however, for the purpose of the present invention, better results are usually obtained by using monofilament. Also, the thickness of the fiber is PTF.
E is selected depending on the diameter and wall thickness of the porous tube, but P
If the TFE porous tube has a relatively small inner diameter of 1 mm or less, it is often sufficient to use a tube with a diameter equal to or smaller than the wall thickness. When winding this fiber spirally around the outer surface of the PTF'E porous tube, there is a method of spirally winding it with a certain gap between the fibers.
This is advantageous because the bonding of the elastomer coating in the subsequent process becomes strong. The PT'FE porous tube, which has fibers spirally arranged on its outer surface, is then heat set by heating the fibers to a temperature below 327°C.The heat setting temperature is set at an appropriate temperature below the melting point of the fiber material. It is sufficient to maintain the tube at a temperature that is within the range of 0.5 to 100 m.The heat setting time is usually sufficient for a few minutes to several tens of minutes.An elastomer coating is then bonded to the outer surface of the structure thus obtained.

Examples of elastomers for this purpose include fluorine rubber, silicone rubber, epichlorohydrin rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, butyl rubber, chloroprene rubber, cis-butadiene rubber,
Examples include synthetic rubbers such as isprene rubber, urethane rubber, polysulfide rubber, acrylic rubber, and propylene oxide rubber, and natural rubber. From these elastomers, one having appropriate characteristics may be selected depending on the intended use. For example, when low gas permeability is required, fluororubber, epichlorohydrin rubber, etc. are suitable. Normally, elastomers are used after being crosslinked, but crosslinking is also preferred in the present invention. The case where the elastomer of the coating material is fluororubber will be described in detail below, but the same is essentially the case when other elastomers are selected.

Examples of fluororubber include vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and tetrafluoroethylene-propylene copolymer. In the case of crosslinking, an acid acceptor, a crosslinking agent, and, if necessary, a filler and a processing aid may be added to the fluororubber compound. Examples of acid acceptors include magnesium oxide, calcium oxide, and lead monoxide; examples of crosslinking agents include aliphatic polyamine derivatives, organic peroxides, and isocyanates; examples of fillers include carbon black and barium sulfate. Examples of processing aids include fluorinated silicone oil. A typical blending example is 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer, 0 to 4 parts by weight of carbon black, 15 parts by weight of magnesium oxide, and 0.5 to 3 parts by weight of aliphatic polyamine derivative. It is a mixture of parts. It is suitable to coat the outer surface of the PTFE porous tube spirally arranged on the fibers by applying a solution of a fluororubber compound.

The solvent for fluororubber includes ketones, esters, etc., and if necessary, diluents such as aliphatic or aromatic hydrocarbons, alcohols, etc. can be used in combination to make the solution viscosity suitable for coating. . A solution of the fluororubber compound is applied to the outer surface of the tube and the solvent is dried to form a coating. In the case of fluororubber, crosslinking is achieved by heating in air or steam, forming a coating with excellent heat resistance and chemical resistance. The bond between the porous PTFE tube and the elastomer coating is physically strong because a portion of the elastomer penetrates into the porous spaces on the outer surface of the porous tube. As detailed above,
The flexible tube of the present invention is suitable for use in inserting or passing other objects into its lumen, and can be used as various medical tubes.

It is particularly suitable for endoscope tubes, various surgical tubes, and dental tubes. In particular, fluororubber, silicone rubber, urethane rubber, acrylic rubber, natural rubber, etc. are suitable as the covering material elastomer for medical tubes. Furthermore, since the flexible tube of the present invention has excellent electrical insulation properties, it can also be used as an insulating tube. The present invention will be explained in more detail below with reference to Examples, but the scope of the present invention is not limited thereby.

Example PTFE fine powder, Polyflon F-10.4E
(Manufactured by Daikin Industries) Add 2 parts of liquid lubricant Deobase to 10 parts of filtration, mix uniformly, pressurize and preform, then use a ram extruder to form a tube with an inner diameter of 3.0Tn and an outer diameter of 4.5T0n. It was pushed out.

This tube was immersed in trichlorethylene to extract and remove the liquid lubricant, and then stretched 200% in the tube axis direction while being heated to about 250°C. This stretched tube was heated to 350° C. while reducing pressure from the outer surface of the tube to expand its diameter, and at the same time, it was further stretched by 200% in the tube axis direction. Sintering was accomplished at the same time. The resulting tube has an inner diameter of 5.
0Wr! PTFE with an outer diameter of 5.35 mm and a porosity of 87%.
It was a porous tube with a very thin wall and high flexibility, but its ability to maintain the cylindrical shape of the tube was poor. 5.079 for this PTFE porous tube! Insert a stainless steel rod with a diameter of 1T1r on the outer surface and polyamide (61 nylon) monofilament (manufactured by Toray) with a diameter of 0.1.
It was wound spirally at intervals of n and then heated to 150° C. for 10 minutes to heat set.

On the other hand, fluororubber Daiel G-501 (manufactured by Daikin Industries)
For 10 parts of filtration, 15 parts by weight of magnesium oxide Kiyowa Mag MA-40 (manufactured by Kyowa Chemical Industry) and 2 parts of MT carbon black were mixed and kneaded with a roll, followed by 1.5 parts of hexamethylene diamine carbamate. Parts by weight were added and dissolved in methyl ethyl ketone to prepare a 22% solution.

Claims (1)

[Scope of Claims] 1. A flexible tube having a structure in which fibers are spirally provided on the outer surface of a polytetrafluoroethylene porous tube, and an elastomer coating is further bonded to the outer surface of the structure. 2. A flexible tube according to claim 1, characterized in that the fibers are made of a material that can be heat set at a temperature of 327° C. or less. 3. Fibers are wound helically around the outer surface of a polytetrafluoroethylene porous tube, the fibers are then heated to a temperature of 327° C. or less, and then the fibers are heat set, and an elastomer compound solution or liquid is applied to the outer surface of the structure. A method for producing a flexible tube, comprising applying an elastomer compound and drying it.