JPS5949464B2 - flexible tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to flexible tubes, and more particularly to flexible multilayer tubes for use in small bend radii.

Tubes used in applications where they are bent or repeatedly bent at substantially small bending radii, such as piping within and/or between small fluid (gas and/or liquid) control equipment, medical and industrial applications The various conduits and channel tubes in endoscopes are mainly flexible, flexible, and free from kicks, collapses, and wrinkles on the tube wall even when bent at a small radius, and smoothness. It is required that the inner wall surface has good resistance.

However, among the various conventionally known tubes, there is no known tube that does not kick, collapse, or wrinkle the surface when bent to about 10 times its own diameter (R).
Furthermore, even if there is no kicking or crushing when bending to the extent of IOR, in order to bend to such a small diameter, it is necessary to apply a large O force or to take special measures such as heating or pressurization. .

Furthermore, in conventional multi-layered tubes, the purpose of multi-layering is to improve the pressure resistance of the tube, and to improve bendability, flexibility, kick resistance at small radius, bendability, etc.5 Therefore, there are no known multilayer tubes suitable for such applications.
However, in the above-mentioned applications, there are very high requirements for the flexibility, softness (or ease of bending), kick resistance, and wrinkle resistance of the tube. From this point of view, the inventors of the present invention have conducted various studies to solve the various problems related to tubes used in the above-mentioned applications. It far exceeds conventional tubes in terms of properties such as bending under force), heat resistance, chemical resistance, non-adhesiveness (less adhesion of other substances to the inner and outer surfaces), lubricity, and light weight. An ideal flexible tube has been created.

That is, according to the present invention, an inner layer of polytetrafluoroethylene having a porous microstructure in which a large number of micronodules are interconnected by fibrils, and an airtight material provided on the outside of the inner layer are used. The flexible tube is characterized by comprising an intermediate layer formed thereon, and an outer layer provided outside the intermediate layer and made of the same material as the inner layer.

The materials used as the inner and outer layers of the flexible tube of the present invention have a large number of micronodules that form fine fibers (fifurles).
A polytetrafluoroethylene having a porous microstructure interconnected by polytetrafluoroethylene, in which numerous voids are formed between these micronodules and microfibers, and the porous structure as a whole has continuous pores. It is.

Polytetrafluoroethylene (hereinafter referred to as PTFE) may include inorganic additives that can be extracted into it, such as silicates, carbonates, metals, metal oxides, sodium chloride, ammonium chloride, etc., or organic powders such as tetrafluoroethylene. Copolymer of ethylene and hexafluoropropylene (
(hereinafter referred to as FEP), powders such as starch, sugar, etc. can also be used. Next, the material of the intermediate layer may be any material suitable for imparting airtightness and/or watertightness, such as a plastic material such as a thin plastic [for example, FEP. ．． PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl pinylether), fluorine, rubber, etc.], metal materials such as metal foil having an adhesive plastic layer, etc. are used. A typical method for manufacturing PTFE sheets and tubes having the porous microstructure from PTFE will now be described in detail.

The production of the crystalline polymer material having the porous microstructure from PTFE is described, for example, in Japanese Patent Publication No. 48-44664, Japanese Patent Application Laid-open No. 7284-1984, or Japanese Patent Application Laid-Open No. 1983-1989.
This is carried out according to the method described in Japanese Patent No. 22881 and the like.

That is, a liquid lubricant (for example, solvent naphtha, hydrocarbon oil such as white oil, petroleum ether, etc.) is added to and mixed with PTFE fine powder (or PTFE dispersion condensate) (mixing ratio PTFE:liquid lubricant -80:20). death,
Alternatively, a preform is made from this by adding a small amount of organic or inorganic additives, and the preform is extruded into a sheet or tube shape using a ram extruder. Roll it to make a molded product. It is possible to remove the liquid lubricant from this molded product, but the result is not good.Next, in an unsintered state (below 327°C), it is about 1.2 to 15 times larger in the longitudinal direction. Stretch. Next, the drawn product is subjected to internal strain at a temperature higher than the melting point or slightly lower than the melting point, preferably 200 to 390°C.
Manufactured by heat setting. The thus obtained PTFE with a porous microstructure exhibits softness, flexibility,
It is highly heat resistant, chemical resistant, water repellent, non-adhesive, slippery, repellent, elastic recovery, etc., and usually has a wall thickness of 0.
05-3.5V1t1 especially 0.

1-2.0tIU1t1 Porosity 30-90%, especially 60
~80%, average pore size 0.01-20μ, especially 1-5μ,
Gurley number one (cross section of 6.45d is 12.7mm H'
The time required for 100 cc of air to permeate under the pressure of 0.01 to 5000 seconds, water leak pressure 0.1 to 1.5 K
1fI/d.

These properties can be varied over a wide range by adjusting manufacturing conditions, making it easy to obtain materials suitable for the purpose. The intermediate layer provided between the inner layer and the outer layer, such as a thin plastic or metal foil with a plastic layer, is then of sufficient thickness 5 to prevent the fluid flowing within the tube from permeating the tube wall. ~200μ, especially 10
˜100μ and is soft and flexible, such as a plastic material layer or a metal foil with a plastic layer.

Examples of such plastic materials include FEPl.
Fluororesins such as tetrafluoroethylene-fluoroalkyl vinyl ether copolymer (PFA), fluororubber, polyurethane, polyimide, polystil, nylon, polyvinyl chloride, polyethylene or metal foils are coated with films of these plastics or of the above materials. Examples include those with a liquid-resistant adhesive layer. In order to provide an intermediate layer of a thin plastic or metal foil with a plastic layer on the outside of the inner layer of PTFE with the above-mentioned porous microstructure, and an outer layer having the same material as the inner layer on the outside of the intermediate layer, first, a tube-shaped wrapping around the inner layer a thin plastic tape of said intermediate layer material or a metal foil with a plastic layer in the absence or presence of an adhesive;
The intermediate layer is formed by applying or extruding the liquid plastic, or by covering the plastic with a heat-shrinkable tube and heating it.

Next, a tape-shaped porous material obtained from a sheet made of the same material as the inner layer is wound around the outer side of the intermediate layer on the inner layer obtained in this way, or a tube-shaped porous material made of the same material as the inner layer is wrapped around the intermediate layer. Cover with quality material to form the outer layer. The thickness of this outer layer can be freely varied depending on the thickness of the inner layer and/or the desired use of the tube, and is generally preferably from 0.05 to 4 mm, particularly from 0.2 to 2 mm. Good.

The thickness ratio of the inner layer is preferably 1:(0.7 to 1.3), and it is particularly preferable that the inner layer and the outer layer have the same thickness.
However, when a flexible coating such as fluororubber is used as the intermediate layer, the thickness of the outer layer can be adjusted in the same manner as described above, but it may be thinner, particularly about 0.1 to 1 mm. The inner layer/outer layer thickness ratio may be about 1/(0.1 to 1).

The three layers thus obtained are heated at a temperature of generally 200 to 300°C, particularly 30°C, at which the middle layer plastic melts.
When heated to 30 to 390°C, the intermediate layer flows to some extent, and the melt enters the micropores on the outer surface of the inner layer and the inner surface of the outer layer.At the same time, the outer layer also contracts appropriately, and when these are cooled, the intermediate layer flows. The plastic of the layers solidifies and flows into the pores, acting as anchors, resulting in a tube in which the three layers are uniformly integrated.

Furthermore, by bonding each layer with an adhesive, a tube in which the three layers of the inner layer, intermediate layer, and outer layer are integrated can be obtained, and in this case, the adhesive may be bonded depending on the properties of the adhesive used. In addition, depending on the case, it is also possible to have a structure of four or more layers, such as repeating the above-mentioned structure of one inner layer and one outer layer.

In the flexible tube of the present invention as described above, due to the above structure, the intermediate layer is thin and located almost in the middle of the tube wall thickness, so that it is located at the minimum point of stress when the tube is bent. Since it is not stretched or compressed, wrinkles and kicks are less likely to occur, which helps to keep the tube airtight or watertight for a long period of time without damage.

However, when applying an intermediate layer of a very flexible coating such as fluororubber, the ratio of the thicknesses of the inner layer and the outer layer may be slightly uneven as described above.

On the other hand, the inner and outer layers have a marshmallow-like fifrill structure, so when they are stretched in the length direction, the fifrills elongate, and when they are contracted, they fit into the voids, so the expansion and compression cause The strain that causes wrinkles that occurs is absorbed within the layer, so that wrinkles do not occur in the curved portion of the tube, and strain that causes kicks does not occur.

Furthermore, the flexibility of the tube, which has the inner and outer layers of the fibril structure, is extremely high, so the force required for bending is extremely small (less than 140 for a solid FEP tube of the same size, but with the minimum bending radius of FEP). (compare). Thus, the flexible tube of the present invention solves all of the drawbacks associated with the conventional products mentioned above, and also saves piping space by being lightweight and has a small curved diameter, and allows piping without the need for joints. It has the following characteristics: it can transport corrosive fluids, the contents do not stick to the inner wall of the tube, the tube has good insulation, there is no exudation from the tube, and it can be bent with a small force. be.

The flexible tube of the present invention is very useful as, for example, a tube for collecting gas to be detected in a gas sensor, a tube for transporting various liquids, a channel tube in an endoscope, and the like.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these.

Example 1 JP-A-46-728 with inner diameter 2.8 mm and wall thickness 0.35 mm
PTF having a porous microstructure in which a large number of micronodules are interconnected by fine fibers obtained by the method described in Publication No. 4
E-tube (stretching ratio 1.6 times, product name GOre-Te
x) (7) Two overlapping layers of FEP film with a thickness of 12 μm and a width of 12 wires are placed around the periphery (1 layer for each layer).

2 laps), and the outer side is further thickened from 0.17 to 0.1
A tape obtained from a PTFE sheet having a porous microstructure in which a large number of micronodules obtained by the method described in the above publication are interconnected by microfibers and having a width of 8Im and 24.5mm is wound (2 wraps). )do.

The thus obtained three-layer tube was heated at about 380° C. for about 1.5 minutes to melt the middle layer and fuse the layers together. The three-layer tube obtained in this way is extremely flexible, and even when bent to a diameter eight times its own diameter (R), it will not kick.
No crushing or wrinkles occurred on the inner surface.

In addition, the flexibility force [when a tube sample with a length of 80U is bent to 12R with a finger and a tension gauge, the gauge reading at a point 15~11Jlt from the end of the curved semicircle (diameter 24mm)] is 70'. It was hot. Furthermore, the curve of 12R is 10
Even after repeating this process ,000 times, there was no separation between the layers, and airtightness was maintained at a pressure of 1 instant/Cl. For comparison, the bending radius of each tube of 10 cm is 5.5 to determine the flexibility and kicking conditions for tubes of similar dimensions.
d and 3.

Table 1 shows the results measured with 5Cff1.

As is clear from Table 1, it is clear that the tube of Example 1 can be bent to a small radius with a small force.

Also, comparable extruded FEP tubes required a very large force to bend, or exhibited a tendency to kick when the bending radius was reduced. The three-layer tube obtained in Example 1 is 15cm long x 25cm wide x 15cm high! When used as a connecting pipe between a sensor in a gas detector and a suction pump, it was found that it could be easily installed in a narrow space, and it was also easier to connect the extruded fluororesin tube, which had less flexibility than conventionally used as a corrosion-resistant tube. The joints that were needed in the past are no longer necessary.

In addition, this tube was airtight and had no gas leakage, even though continuous porosity material was used for the inner and outer layers. Furthermore, when the tube of Example 1 was used as a tube for collecting gas to be detected in the gas sensor, it was lightweight and highly flexible, making it much easier to use than conventional tubes.

Example 2 PTF obtained in the same manner as described in Example 1 as inner layer
E tube (inner diameter 2.8WtR1 wall thickness 0.3511t1
1. A FEP heat-shrinkable tube with an inner diameter of 411!11 and a wall thickness of 0.15g1 is placed on the outside of the 160% stretching ratio (trade name: GOre-Tex), and this is heated to about 200°C to shrink to form a two-layer tube, and the outside Additionally, a PTFE tube (inner diameter 3) was obtained in the same manner as described in Example 1.

91U! , wall thickness 0. .

Cover with 35tt0 and heat the whole to about 380℃ for about 1 hour.

They were heated and bent for 5 minutes to integrate and form a three-layer tube.

The tube thus obtained did not exhibit kicks, crushing, or wrinkles even when bent to 15R.

Moreover, the watertightness was also extremely good. When the tube of Example 2 was used as a tube for transporting pure water for rinsing in IC chips and CMOS semiconductor processing, a tube for transporting aqueous solution for pharmaceutical manufacturing, and a tube for transporting culture solution for microorganisms, in each case. However, there was no contamination of the transferred liquid by the tube material, and due to its flexibility, there was no kick, making it extremely easy to use, long life, easy maintenance, and cleaning by pickling and water washing.

Example 3 A PTFE tube (stretching rate 160
%, product name: GOre-Tex), and wrap 2 wraps of FEP film with a thickness of 12 μm and a width of 9 layers, and then wrap the outside with an additional thickness of 0.20 WI! A PTFE tape having a width of 18 mm and obtained in the same manner as described in Example 1 (stretching ratio: 3
The tube thus obtained was fired at about 380° C. for about 1.5 minutes to melt the middle layer and obtain a three-layer tube.

The tube obtained in this way is highly flexible, and even when bent to a minimum bending radius of 5R, no kicking, crushing, or wrinkles on the inner and outer surfaces occur at all, and even after repeated bending in 12 cases. The tube remained airtight.

The flexible force used to break it was 40 tons. On the other hand, the flexibility of a cross-linked polyethylene tube of the same size conventionally commonly used as a channel tube was approximately 200 f at a bending radius of 20R.

The bending properties of an endoscope incorporating the tube of Example 3 as a channel tube within the endoscope were significantly improved compared to an endoscope of the same size using a crosslinked polyethylene tube as the channel tube.

In other words, the flexibility required for bending is extremely small, making it possible to reverse view of the cardia of the stomach and to pass through tortuous passages such as the sigmoid colon. The channel tube of Example 3 has a smooth inner surface, and there are no inner wrinkles or collapse of the tube cross section even when it is bent. The forceps can be pulled out very smoothly.

Example 4 Inner diameter 2.8mm, wall thickness 0.

A PTFE tube (stretching ratio: 1.6 times A fluororubber coating layer is formed around the material (trade name: GOre-Tex). The composition used for forming this layer is 100 parts by weight of fluororubber, 15 parts by weight of acid acceptor (MgO), and 30 parts by weight of carbon black, and a 17% solution of methyl ethyl ketone is used. It was added. To form the fluororubber layer, the PTFE tube is immersed in the liquid and a fluororubber coating is applied;
Dry it. The thickness of the dried fluororubber coating layer is about 25P. Next, two wraps of porous PTFE tape having the same dimensions as in Example 1 and a specific gravity of 1.3 were wound around the soil of the tube coated as described above.

The three-layer tube thus obtained was heated to about 1.5 cm at about 380C.
Heat for 1 minute to melt the intermediate layer and integrate the layers. The three-layer tube thus obtained has almost the same excellent properties as the tube of Example 3, and its flexibility strength is about 5
Even after repeating 12R bending at 0t 50,000 times, there was no interlayer peeling at all.

Claims (1)

[Claims] 1. An inner layer of polytetrafluoroethylene having a porous microstructure in which a large number of micronodules are interconnected by fine fibers, and an intermediate layer formed of an airtight material provided outside the inner layer. , and an outer layer made of the same material as the inner layer provided outside the intermediate layer. 2 The ratio of the inner layer thickness to the outer layer thickness is 1: (0.7 to 1.
3) The flexible tube according to claim 1. 3. The flexible tube according to claim 1 or 2, wherein the material of the intermediate layer is a soft and flexible plastic material. 4. The flexible tube according to claim 1 or 2, wherein the material of the intermediate layer is a metal material having a plastic layer. 5. Claims 1 to 4 in which the inner layer, intermediate layer, and outer layer are integrated by melting the intermediate layer material.
The flexible tube according to any of paragraphs. 6. The flexible tube according to any one of claims 1 to 4, wherein the inner layer, intermediate layer, and outer layer are integrated by adhesive.