JPH0585189B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is directed to polytetrafluoroethylene (hereinafter referred to as
The invention relates to a flexible tube made of PTFE (PTFE) that is radiopaque. [Prior art] Various types of plastic tubes, such as nylon and urethane, have been used as tubes for endoscopes. There were problems with the appearance of wrinkles. To solve these problems, the inner and outer layers are made of expanded PTFE with open pores.
A three-layer tube in which the intermediate layer is made of an airtight material has already been proposed (Japanese Patent Laid-Open No. 53-422). Although this tube solved most of the problems mentioned above, it had the disadvantage that its position could not be confirmed by X-rays when using an endoscope because it was transparent to X-rays. On the other hand, for medical tubes inserted into the human body such as endoscopes and catheters, it is already common practice to provide them with X-ray contrast properties in order to confirm their position. For example, Japanese Patent Publication No. 47-49394 describes a catheter in which an X-ray opaque agent is added to a melt-extruded fluororesin. Also, JP-A-57-
Japanese Patent No. 55152 discloses a medical tube having a three-layer structure using the cast method, in which the intermediate layer has X-ray contrast properties. However, since these tubes are all constructed from solid materials, they suffer from the flexibility and bending problems discussed above. [Problems to be solved by the invention] In view of the problems of conventional medical tubes as described above, a tube that has X-ray contrast properties and has excellent flexibility, flexibility, kink resistance, and wrinkle resistance. The challenge for this industry was to create medical tubes with a high degree of compatibility. [Means for Solving the Problems] As a result of studies to solve the above problems, the present inventors have developed an X-ray contrast agent fine powder with an average particle size of 10 μm or less.
20-70% by weight and 30-80% by weight of PTFE, which has a porous microstructure in which many micronodules are interconnected by fibrils and many voids are formed between them, and has X-ray contrast. A flexible tube consisting of a material in which most of the agent is contained in the micronodules, or an airtight material layer or an airtight material layer and a large number of micronodules interconnected by fibrils on the inside and/or outside of this tube. The inventors discovered that a flexible tube provided with a PTFE layer having a porous microstructure with a large number of voids formed therein could meet the above objectives, and completed the present invention. . The main material of the flexible tube of the present invention, the X-ray opaque PTFE having the above-mentioned porous microstructure, is produced as follows. First, as an X-ray contrast agent, inorganic powders conventionally used for this purpose, such as barium sulfate,
Fine powder of bismuth oxide, bismuth nitrate, bismuth carbonate, nickel powder, etc., with an average particle size of 10 μm or less,
Preferably, one with a diameter of 3 μm or less, particularly 1 μm or less is prepared. This is because if the average particle size is 10 μm or more, workability in the next molding step is significantly inhibited. This X
The linear contrast agent powder is dispersed in water, mixed with a surfactant if necessary, and then added to the PTFE dispersion and stirred and mixed. In the process of stirring and mixing,
PTFE microparticles precipitate around the contrast agent microparticles, gel, and precipitate. This process leading to gelation is called co-coagulation. Addition of a small amount of acid or alkali at the end of this co-coagulation promotes precipitation. Once precipitation is complete, decant the supernatant and remove the resulting PTFE.
and X-ray contrast agent are dried. Through this co-coagulation method, it is possible to mix 20% by weight or more of X-ray contrast agent into PTFE, and there is no major problem in appearance even after the next molding process. A molded product is obtained. The content of X-ray contrast agent in this mixture is 20-70% of the total weight of the mixture.
%, preferably 40-60%. If it is less than 20%, sufficient X-ray contrast performance cannot be obtained, and if it is more than 70%, moldability deteriorates and problems such as the X-ray contrast agent coming off from the molded product occur. The mixture obtained as described above can be used as a conventional
It is molded according to the molding method of a mixture (also called paste) of PTFE fine powder and liquid lubricant.
That is, a mixture of an X-ray contrast agent and PTFE is mixed with a liquid lubricant (e.g., solvent naphtha, liquid hydrocarbon such as white oil, petroleum ether, etc.) at about 80%
A preform is made from the mixture in a weight ratio of 20, and the preform is extruded into a tube or sheet using a ram extruder. Although sheet-like molded products have a certain degree of strength, they cannot be used in the stretching process as they are, so their strength increases when they are rolled with rolls to a thickness of about 1/2 to 1/10. The liquid lubricant is removed from the tube-like or sheet-like molded product thus obtained by extraction or heating and volatilization. In addition,
Molded articles without liquid lubricant removal can also be used in the subsequent drawing step, but the results are poor. The tube-shaped or sheet-shaped PTFE molded product containing the X-ray contrast agent obtained as described above was
It is stretched in at least one direction while being heated to a temperature below .degree. C., preferably below the melting point of PTFE.
The stretching ratio is approximately 1.2 to 20 times. This stretching does not significantly reduce the cross-sectional area of the material, but increases its dimension in the direction of stretching, so that the resulting product is inevitably voided and porous. If the temperature during stretching is higher than the melting point of PTFE, the stretched molded product will be fired, although to a lesser extent, but if the temperature is lower than the melting point of PTFE, it will be unfired. The incompletely fired or unfired expanded PTFE tube or sheet obtained in this manner is maintained in the stretched state and heated to a temperature above the melting point of PTFE to further increase the degree of firing, thereby improving dimensional stability and strength. The degree of firing is proportional to the firing temperature and time, so depending on the purpose, if it is a finished product, it is fired completely, and if it is an intermediate product (to be further processed), it is fired completely. Bake to the extent that it is easy to bake. The thickness of the tube thus obtained is approximately 0.1 to 2 mm, the outer diameter can be adjusted within a maximum range of approximately 30 mm, and the thickness of the sheet is approximately 0.02 to 2 mm.
mm, the width can be adjusted up to about 1m depending on the thickness. The open-pore porous PTFE containing the X-ray contrast agent stretched in this way has a large number of micronodules connected to each other by a large number of fibrils (fine fibers), and a number of micronodules are bonded to each other by a number of fibrils. It has a porous microstructure with continuous voids (micropores). Surprisingly, most of the X-ray contrast agent is contained in the micronodule portion, and almost no X-ray contrast agent is contained in the fibrillar portion. Therefore, the mechanical properties of this material are not significantly different from open-cell porous PTFE without X-ray contrast agent. For example, fibril length is 0.1~500μ, porosity
The tensile strength decreases by 25 to 90% as the content of the X-ray contrast agent increases, but the decrease is no more than about 10%, and the flexibility, flexibility, elasticity, and elastic recovery are abundant. Although the above fired expanded PTFE tube can be applied to an endoscope as is, this tube can also be used as an expanded PTFE tube containing the unfired or incompletely fired X-ray contrast agent obtained as described above. By slitting a porous PTFE sheet into tape, wrapping it uniformly around a metal rod, heating it to a temperature higher than the melting point of PTFE to integrate it, and then removing the metal rod. It can also be produced by a combination of these methods. Furthermore, if the tube wall needs to be airtight in order to pass gas through the tube, a layer of airtight material is provided on the inside and/or outside of the tube. The airtight material layer has a thickness sufficient to prevent the fluid flowing inside the tube from permeating the tube wall (for example, about 5 to 1000 μm),
Moreover, a soft and flexible plastic material or a laminated material of plastic and metal is used. For example, fluororesins such as FEP (a copolymer of tetrafluoroethylene and hexafluoropropylene) and PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether), fluororubber, polyurethane, polyimide, polyester, and nylon. , polyvinyl chloride, polyethylene, or a laminate of these and metals. These airtight material layers can be provided on the inside and/or outside of the tube by any suitable method, such as applying and drying the airtight material as a liquid, extruding it, or applying it as a heat-shrinkable tube. This can be done by a method. Moreover, the thickness of the airtight layer can be determined depending on flexibility requirements. Furthermore, for applications where it is undesirable for this layer of airtight material to be exposed on the inside and/or outside of the tube, for example to increase lubricity for inserting forceps into the tube, to suppress exudates, If it is desired to increase chemical resistance without sacrificing flexibility, a large number of micronodules are bonded to each other by fibrils on the exposed airtight material layer, and a large number of voids are formed between them. A PTFE layer having a porous microstructure may also be provided. Such an open-cell porous PTFE layer does not necessarily need to contain an X-ray contrast agent. Does not contain this X-ray contrast agent
A method for manufacturing sheets and tubes having the above-mentioned porous microstructure from PTFE is described, for example, in Japanese Patent Publication No. 48
This is carried out according to the method described in Japanese Patent Application Laid-open No. 44664, Japanese Patent Application Laid-open No. 46-7284, or Japanese Patent Application Laid-Open No. 50-22881. i.e. PTFE fine powder (or
Add and mix a liquid lubricant (e.g. solvent naphtha, hydrocarbon oil such as white oil, petroleum ether, etc.) to (PTFE dispersion condensate) (mixing ratio PTFE:liquid lubricant = 80:20), or add a small amount to this. A preform is made from the material to which organic or inorganic additives are added, and the preform is extruded into a sheet or tube shape using a ram extruder, and the sheet is rolled as necessary to form a molded product. Create. The liquid lubricant is removed from this molded product (it is not necessary to remove it, but the result is not good), and then it is stretched in the longitudinal direction by about 1.2 to 20 times in an unsintered state (below 327°C). . Next, a sheet or tube is produced by heating the stretched product in a stretched state at a temperature higher than or slightly lower than the melting point, preferably 200 to 390°C. The thus obtained PTFE sheet or tube, which does not contain an X-ray contrast agent and has the above-mentioned porous microstructure, has flexibility, flexibility, heat resistance, chemical resistance,
It is highly water repellent, non-adhesive, slippery, stretchable, and has elastic recovery power, and usually has a wall thickness of 0.05 to 3.5.
mm, especially 0.1~2.0mm, porosity 30~90%, especially 60~
80%, average pore size 0.01-20μ, especially 1-5μ, Gurley number ( ^6.45cm2 cross section under 12.7mmHg pressure)
Time required for 100cc of air to pass through) 0.01~
5000 seconds, water leakage pressure is 0.1-1.5Kg/ ^cm2 . These properties can be achieved by adjusting the manufacturing conditions.
Since it can be varied over a wide range, it is easy to obtain a material that is suitable for the purpose. To provide an X-ray contrast agent-free PTFE layer with the above-mentioned porous microstructure on top of a layer of gas-tight material inside the tube, the tube of this material is first placed over a metal rod or wrapped with tape. a porous material on which a layer of air-tight material is applied, extruded, or wrapped with tape, without baking or baking, and further contains an X-ray contrast agent thereon;
This is done by wrapping PTFE tape and heating it to integrate the whole. Also, it does not contain an X-ray contrast agent that has a porous microstructure on the outer airtight material layer of the tube containing the X-ray contrast agent described above.
To provide the PTFE layer, a metal rod is passed through the tube and a porous material containing no X-ray contrast agent having the above-mentioned porous microstructure is placed on top of the layer of airtight material.
All you have to do is wrap the PTFE tape, fix it, and heat it to integrate it. In addition, the above two methods can be used to provide a porous PTFE layer containing no X-ray contrast agent and having the above-mentioned porous microstructure on the inside and outside of a flexible tube having airtight material layers on the inside and outside. This can be done by appropriately combining the following. In order to integrate the gas-tight material layer and the porous PTFE layer without X-ray contrast agent with the porous microstructure described above, the temperature at which the plastic of the gas-tight material layer melts, generally 200 to 400 °C, in particular 330 °C
When heated to ~390°C, the gas-tight material layer will flow somewhat and the melt will have the above-mentioned porous microstructure.
It penetrates into the pores of porous PTFE that does not contain a radiographic contrast agent, and after cooling, it solidifies and becomes integrated due to the anchor effect. In addition, when the flexible tube of the present invention is composed of multiple layers as described above, a PTFE layer containing an X-ray contrast agent and a PTFE layer not containing an X-ray contrast agent having the above-mentioned porous microstructure are combined. The wall thickness ratio is 1:
(0.3 to 1.3), especially when the same level is used, there are fewer problems such as flexibility and generation of wrinkles. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 After dispersing 4 kg of barium sulfate (manufactured by Kishida Chemical Co., Ltd.) with an average particle size of 0.7 μm in 25 kg of water, PTFE was added to this.
Dispersion was added in an amount to give a solid content of 6 kg, and the barium sulfate and PTFE were co-coagulated by stirring and mixing. After the coagulation was completed, the supernatant liquid was poured off, and the resulting coagulate was heated at 120°C for 2 days. The mixture was heated and dried to obtain a granular mixed powder of 40% barium sulfate and 60% PTFE. 25 parts by weight of petroleum naphtha is mixed with 100 parts by weight of this mixed powder, extruded into a tube shape with an inner diameter of 3 mm and a wall thickness of 0.4 mm in the same manner as the normal PTFE paste extrusion molding method, and the petroleum naphtha is removed by heating. After that, it was stretched 1.5 times in the longitudinal direction, and then heated to 370℃ while maintaining the stretched state to make the inner diameter 2.8
A stretched PTFE tube having a wall thickness of 0.35 mm and containing 40% by weight of an X-ray contrast agent was obtained. The tube thus obtained did not exhibit kinks, collapse, or wrinkles even when bent to 15R. Moreover, the watertightness was also extremely good. Furthermore, when this tube was taken in an X-ray photograph, it appeared gray, confirming the X-ray contrast property. Example 2 After dispersing 4 kg of barium sulfate (manufactured by Kishida Chemical Co., Ltd.) with an average particle size of 0.7 μm in 25 kg of water, PTFE dispersion was added in an amount to give a solid content of 6 kg, and the mixture was stirred and mixed to dissolve barium sulfate and PTFE. After co-coagulation, the supernatant liquid was poured off, and the resulting coagulate was heated and dried at 120°C for 2 days to dissolve barium sulfate 40.
%, a granular mixed powder of 60% PTFE was obtained. 25 parts by weight of petroleum naphtha was mixed with 100 parts by weight of this mixed powder, and a sheet with a thickness of 100 μm and a width of 120 mm was obtained by a normal PTFE paste extrusion method. This sheet was further stretched three times in the longitudinal direction under heating at 250°C to obtain a sheet having a porous microstructure with a porosity of 85%. A tape with a width of 20 mm was made from this sheet. Separately, a porous microstructure with an inner diameter of 2.8 mm and a wall thickness of 0.35 mm is obtained by the method described in JP-A-46-7284, in which a large number of micro nodules are bonded to each other by fibrils (fine fibers). Two overlapping layers of FEP film with a thickness of 12 μm and a width of 12 mm (each layer has 1.2 wraps) were placed around a PTFE tube (stretching ratio: 1.6 times, trade name: Gore Tex), and the outside was further wrapped in the above method. Contains 40% by weight of the obtained barium sulfate,
It has a porous microstructure in which many micronodules are connected to each other by fibrils.
Winding tape obtained from PTFE sheet (2 wraps)
do. The three-layer tube thus obtained was heated to about 380°C.
The intermediate layer was melted by heating for 1.5 minutes, and each layer was fused and integrated. The three-layer tube thus obtained was extremely flexible, and even when bent to a diameter eight times the self diameter (R), no kink, collapse, or wrinkles occurred on the inner surface. Also flexible capacity [length 80mm
tube specimens with fingers and tension cages.
Curved to 12R, from the edge of the curved semicircle (diameter 24mm)
The gauge reading at 15mm was 70g. Furthermore, even after repeating 12R bending 10,000 times, there was no interlayer separation at all, and airtightness was maintained at a pressure of 1 Kg/cm ² . Furthermore, when this tube was taken in an X-ray photograph, the tube part appeared clearly gray. For comparison, Table 1 shows the results of measuring the flexibility and kink of tubes with similar dimensions at bending radii of 5.5 cm and 3.3 cm for each tube with a length of 10 cm.

[Front] Tanchuyu
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〔Effect of the invention〕

The flexible tube of the present invention is made of open-cell porous PTFE, the main component of which contains an X-ray contrast agent.
Therefore, it has X-ray contrast properties, and microscopically it has a porous microstructure in which many voids are formed between many micronodules and fibrils that interconnect them three-dimensionally. Most of the X-ray contrast agent is contained in the micronodules, and very little in the fibrils, so it has a marshmallow-like appearance.When stretched, the fibrils stretch, and when contracted, they enter the voids, so they cannot be stretched or compressed. The strain caused by this is absorbed by the tube wall at the curved portion, making wrinkles and kinks less likely to occur. Also,
The flexible tube of the present invention has mostly fibrils.
Made from PTFE, it has high tensile strength, and the porosity can be adjusted over a wide range by changing the stretching ratio.If the stretching ratio is increased, it is surprisingly lightweight, highly flexible, and can be bent to a small diameter with extremely little force. can be done. Furthermore, the flexible tube of the present invention overcomes all of the above-mentioned drawbacks associated with conventional products. Such a flexible tube of the present invention is not only suitable as a tube for an endoscope, which is the main purpose, but also has a light weight and a small bending radius.
It is excellent for saving piping space, shortening piping length, and transporting corrosive fluids as a variety of piping, and if an airtight layer is added to it, it can transport gases and low surface tension liquids, and an expanded PTFE layer can be installed. It is excellent for transporting ultra-clean liquids (no exudates from pipe walls) or for medical purposes.

Claims (1)

[Claims] 1. X-ray contrast agent fine powder with an average particle size of 10 μm or less 20~
70% by weight and 30-80% by weight of polytetrafluoroethylene having a porous microstructure in which many micronodules are interconnected by fibrils and many voids are formed therebetween, and A flexible tube having X-ray contrast properties, characterized in that most of the radio contrast agent is contained in the micronodules. 2 X-ray contrast agent fine powder with an average particle size of 10 μm or less 20~
70% by weight and 30-80% by weight of polytetrafluoroethylene having a porous microstructure in which many micronodules are interconnected by fibrils and many voids are formed therebetween, and An airtight material layer or an airtight material layer and a large number of micronodules are formed by fibrils on the inside and/or outside of the flexible tube having X-ray contrast properties, in which most of the radiographic contrast agent is contained in the micronodules. 1. A flexible tube having X-ray contrast properties, characterized in that it is provided with polytetrafluoroethylene layers having a porous microstructure that are bonded to each other and have a large number of voids formed therebetween.