JP2013144380A - Laminate tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate tube that has excellent flexibility and chemical resistance, has a high mechanical strength, and has excellent detachability between respective parts of an inner surface thereof so that the respective parts of the inner surface are prevented from adhering to each other.SOLUTION: A laminate tube includes: an outer layer formed of an elastomer; and an inner layer that is provided inside the outer layer and formed of a polytetrafluoroethylene porous membrane obtained by drawing a non-baked polytetrafluoroethylene body or half-baked polytetrafluoroethylene body.

Description

The present invention relates to a laminated tube.

In order to control the flow of fluids used in fields such as pharmaceuticals, foods, medicines, and chemistry, pinch valves and roller pumps that have the property of hardly contaminating fluids and being difficult to accumulate liquids are used. Since chemicals and the like flow as fluids in the rubber tube, the rubber tube is required to have chemical resistance.

The pinch valve controls the fluid flow by opening and closing the flow path by crushing the rubber tube. The roller pump pumps out the fluid in the rubber tube by crushing the rubber tube with a roller. For this reason, in the pinch valve and the roller pump, the inner surfaces of the rubber tubes are repeatedly in close contact with each other. When the operation of the pinch valve or the roller pump is stopped, the inner surfaces of the rubber tubes are left in close contact with each other. Therefore, depending on the material used to form the rubber tube, the peelability after the inner surfaces are in close contact with each other is poor. Sometimes. Further, since the pressure is repeatedly applied to the rubber tube, the rubber tube is torn or the layers are separated when the rubber tube is a laminate.

In order to solve these problems, in Patent Document 1, the inner surface (inner layer) is composed of a fluororesin layer, and an elastic layer (outer layer) is formed outside the fluororesin layer. An intermediate layer composed of a porous fluororesin (such as porous polytetrafluoroethylene) and an elastic body filling the pores of the porous fluororesin is formed between the inner layer and the elastic layer (outer layer). A laminated type in which an inner fluororesin layer and an intermediate porous fluororesin are bonded (particularly heat-sealed), and an outer elastic layer and an intermediate elastic body are bonded Elastic tubes have been proposed.

Patent Document 2 proposes a fluorine-based elastic tube in which an amorphous perfluoro resin film having a thickness of 1 μm or less is provided on the inner surface of an elastic hollow body made of a fluorine-based polymer.

JP 2008-30471 A International Publication No. 2010/101108 Pamphlet

The present invention provides a laminated tube that is excellent in flexibility and chemical resistance, has high mechanical strength, is excellent in peelability between inner surfaces, and is difficult to adhere to inner surfaces.

The present invention comprises an outer layer formed from an elastomer, and an inner layer provided inside the outer layer and formed from a polytetrafluoroethylene porous membrane obtained by stretching a non-fired or semi-fired polytetrafluoroethylene. It is the laminated tube characterized by the above-mentioned.

In the laminated tube, it is preferable that the outer layer and the inner layer are directly bonded.

It is preferable that the polytetrafluoroethylene porous membrane is a polytetrafluoroethylene porous membrane extended in a biaxial direction.

The elastomer is preferably a fluorine-containing elastomer.

The porosity of the polytetrafluoroethylene porous membrane is preferably 40 to 99%.

The thickness of the polytetrafluoroethylene porous membrane is preferably 5 to 150 μm.

The present invention relates to the above-described method for producing a laminated tube, the step (1) of winding a polytetrafluoroethylene porous film around a core material, and the polytetrafluoroethylene porous film wound around the core material on the polytetrafluoroethylene porous film. A step (2) of obtaining an intermediate molded product by crosslinking and heating the elastomer by coating and heating, and a step (3) of extracting a core wire from the intermediate molded product to obtain a laminated tube. It is also a manufacturing method.

The present invention is also a pinch valve including the above-described laminated tube.

The present invention is also a roller pump including the laminated tube described above.

The laminated tube of the present invention is excellent in flexibility and chemical resistance, has high mechanical strength, is excellent in peelability between inner surfaces, and is difficult to adhere to inner surfaces.

It is sectional drawing which shows one Embodiment of the laminated tube of this invention. It is sectional drawing which shows one Embodiment of the pinch valve of this invention. It is a top view which shows one Embodiment of the roller pump of this invention. It is sectional drawing which shows typically the evaluation method used in the Example.

Hereinafter, the present invention will be specifically described.

FIG. 1 is a cross-sectional view showing an embodiment of the laminated tube of the present invention. The laminated tube 10 of the present invention includes an outer layer 11 and an inner layer 12. The outer layer 11 is made of an elastomer, and gives flexibility and mechanical strength to the laminated tube. The inner layer 12 is formed of a polytetrafluoroethylene porous film and imparts chemical resistance to the inner surface of the laminated tube 10, so that deterioration of the laminated tube 10 is suppressed even when chemicals are circulated in the laminated tube 10. . Furthermore, since the polytetrafluoroethylene porous film imparts peelability to the inner surface of the laminated tube 10, even if the laminated tube 10 is crushed and the inner surfaces are in close contact with each other, the polytetrafluoroethylene porous membrane is easily separated if released from the press, Even if the inner surfaces are in close contact with each other for a long time, they do not stick. From this viewpoint, it is preferable that the polytetrafluoroethylene porous membrane is located in the innermost layer of the laminated tube and constitutes the inner surface of the laminated tube.

Each configuration will be described in detail below.

1. Elastomer The elastomer that can be used in the outer layer of the laminated tube of the present invention is not particularly limited as long as it has been conventionally used in a tube, but a fluorine-containing elastomer is preferably used from the viewpoint of chemical resistance. By forming the outer layer with a fluorine-containing elastomer, the outer layer does not deteriorate even if chemicals flowing through the laminated tube pass through the inner polytetrafluoroethylene porous membrane and reach the outer layer. Examples of the fluorine-containing elastomer include fluororubber, thermoplastic fluororubber, and rubber compositions containing these fluororubbers. The rubber composition can be prepared by mixing components such as a crosslinking agent and a crosslinking agent using an ordinary elastomer processing machine, for example, an open roll, a Banbury mixer, a kneader and the like. In addition, it can be prepared by a method using a closed mixer.

Examples of the fluoro rubber include non-perfluoro fluoro rubber and perfluoro fluoro rubber, and perfluoro fluoro rubber is particularly preferably used.

Non-perfluorofluororubbers include vinylidene fluoride (VdF) fluororubber, tetrafluoroethylene (TFE) / propylene fluororubber, tetrafluoroethylene (TFE) / propylene / vinylidene fluoride (VdF) fluororubber, ethylene / Hexafluoropropylene (HFP) fluorine rubber, Ethylene / Hexafluoropropylene (HFP) / Vinylidene fluoride (VdF) fluorine rubber, Ethylene / Hexafluoropropylene (HFP) / Tetrafluoroethylene (TFE) fluorine rubber, Fluoro Examples thereof include silicone-based fluororubber, fluorophosphazene-based fluororubber, and the like, which can be used alone or in any combination as long as the effects of the present invention are not impaired. As the non-perfluorofluororubber, VdF fluororubber is preferable, and VdF / hexafluoropropylene fluororubber is more preferable.

Examples of the perfluorofluororubber include TFE / perfluoro (alkyl vinyl ether) (PAVE) / a fluorine-containing elastomer composed of a monomer that provides a crosslinking site. The composition of TFE / PAVE is preferably 50 to 90/10 to 50 (mol%), more preferably 50 to 80/20 to 50 (mol%), and still more preferably 55 to 70/30 to 45 (mol%). The monomer that gives a crosslinking site is preferably 0 to 5 mol%, more preferably 0 to 2 mol%, based on the total amount of TFE and PAVE. When the composition is out of the range, the properties as a rubber elastic body are lost, and the properties tend to be similar to those of a resin.

Examples of PAVE in this case include perfluoro (methyl vinyl ether) and perfluoro (propyl vinyl ether), and these can be used alone or in any combination within a range not impairing the effects of the present invention. .

The outer layer may contain various fillers used for ordinary elastomers. Examples of the filler include carbon black, silica, metal oxide, metal hydroxide, carbonate, silicate, sulfate, resin powder, glass powder, inorganic fiber, whisker, and pigment.

The outer layer may contain usual additives contained in the elastomer, for example, processing aids, plasticizers, colorants and the like, if necessary.

2. Polytetrafluoroethylene porous membrane The polytetrafluoroethylene porous membrane used for the inner layer of the laminated tube of the present invention is obtained by stretching an unfired or semi-fired product of polytetrafluoroethylene (hereinafter also referred to as PTFE). It is a porous membrane (hereinafter also referred to as PTFE porous membrane). When simply laminating PTFE, thin film processing of PTFE is difficult and there is a limit to thin film processing, and the flexibility of the laminated tube is impaired. However, according to the configuration of the present invention, such a problem is solved. The

The PTFE is a polymer having a fibrillation property and a non-melt processability. The PTFE includes not only a homopolymer of tetrafluoroethylene but also a copolymer of tetrafluoroethylene and other monomers capable of copolymerization not exceeding 2% by weight.

The PTFE porous membrane may contain a filler. As the filler, fillers such as carbon black, fibers such as carbon fiber and glass fiber, whiskers, and metal oxide are preferable from the viewpoint of enhancing the strength and durability of the film.

The PTFE porous membrane is obtained by extruding a raw mixture of unfired or semi-fired PTFE fine powder as a raw material and an extrusion aid such as naphtha and then rolling it to obtain a sheet-like extrudate. It is obtained by a step, a step of removing the extrusion aid by heating or extracting the obtained rolled product with a solvent such as trichloroethane or trichlorethylene, and a step of stretching the rolled product not containing the extrusion aid.

In the step of removing the extrusion aid, when it is removed by heating, the heating temperature can be appropriately selected depending on the extrusion aid, but is preferably 200 to 300 ° C. It is particularly preferable to heat at around 250 ° C. If the temperature exceeds 300 ° C., especially 327 ° C., which is the melting point of PTFE, there is a tendency to be fired.

The PTFE porous membrane is preferably a PTFE porous membrane obtained by stretching a rolled product containing no extrusion aid in the biaxial direction. The PTFE porous membrane stretched in the biaxial direction can be obtained by setting the stretching direction in the stretching step to the biaxial direction. Biaxial stretching (biaxial stretching) may be sequential biaxial stretching or simultaneous biaxial stretching. Moreover, you may pre-heat at about 300 degreeC before extending | stretching. The draw ratio is preferably 20 to 500 magnification, more preferably 30 to 300 magnification, and even more preferably 50 to 200 magnification, from the viewpoint that the intended basis weight and porosity can be obtained. The draw ratio is obtained by multiplying the draw ratio in the longitudinal direction and the draw ratio in the transverse direction.

The porosity of the PTFE porous membrane is preferably 40% or more, and more preferably 60% or more from the viewpoint of good adhesion to the mating base material at the time of composite. Further, the porosity of the PTFE porous membrane is preferably 99% or less, and more preferably 97% or less, from the viewpoint that the handleability during processing is good.

The thickness of the PTFE porous membrane is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more from the viewpoint that the porous membrane does not break and is excellent in moldability. Further, it is preferably 150 μm or less, more preferably 100 μm or less, still more preferably 70 μm or less, and particularly preferably 50 μm or less, from the viewpoint of flexibility of the porous film and the absence of a large step in the overlapping portion.

The basis weight of the membrane in which the porosity and thickness of the PTFE porous membrane are in a preferable range is 200 g / m ² or less, and more preferably 50 g / m ² or less. Moreover, 0.5 g / m < ² > or more is preferable and 1.0 g / m < ² > or more is more preferable from the point that the porous film does not break and is excellent in moldability.

3. Production Method The laminated tube of the present invention can be produced, for example, by the following method. That is, a step (1) of winding a PTFE porous film around a core material, and coating the PTFE porous film wound around the core material with an uncrosslinked elastomer and heating to crosslink the elastomer, thereby forming an intermediate molded product. A step (2) of obtaining a laminated tube by drawing a core material from the intermediate molded product. This manufacturing method is also one aspect of the present invention.

As the core material that can be used in the step (1), a core material made of metal, ceramic, resin, or the like can be used. The core material may be rod-shaped or cylindrical. The method of winding the PTFE porous film around the core material is not particularly limited as long as the porous film is wound without a gap, and for example, it can be wound in a spiral shape. It may be wound so as to overlap several times perpendicular to the longitudinal direction, and according to these methods, the thickness of the inner layer can be adjusted by the number of times of winding.

In the step (2), as a method of coating the uncrosslinked elastomer, a method of extruding the elastomer onto the PTFE porous membrane, an uncrosslinked elastomer processed into a sheet on the core material wound with the PTFE porous membrane is used. Examples thereof include a winding method, a method in which a core material around which a PTFE porous membrane is wound is placed in a mold, and an elastomer is filled around the PTFE porous membrane.

The conditions for crosslinking the elastomer in the step (2) can be appropriately determined depending on the type of elastomer, the type of crosslinking agent, and the like. The crosslinking of the elastomer can be usually carried out by performing primary crosslinking at a temperature of 100 to 200 ° C. for 5 to 60 minutes and further performing secondary crosslinking as necessary. In addition, as a crosslinking method, not only a conventionally used method such as press crosslinking or steam crosslinking, but also under normal pressure, increased pressure, reduced pressure, or in air, under any conditions. The reaction can be performed.

The extraction of the core material from the intermediate molded product in the step (3) can be performed by a method of twisting the intermediate molded product and the core material or blowing air into the gap between the intermediate molded product and the core material.

The present invention is also a pinch valve including the above-described laminated tube. FIG. 2 is a sectional view showing an embodiment of the pinch valve of the present invention. The pinch valve 20 includes a main body 22 and a pinch element 21 slidably engaged with a hole provided in the main body 22. A laminated tube 24 is mounted in the groove of the main body 22, and both ends of the laminated tube 24 are connected to the connecting body 23, and connected to piping for connecting to other devices via the connecting body 23. The laminated tube 24 is crushed by the sandwiching element 21 and the flow of fluid in the laminated tube 24 is blocked. When the pressing of the pinch element 21 is released, the fluid in the laminated tube 24 resumes circulation. It is also possible to control the flow rate by pressing the pinching element 21. As described above, the pinch valve controls the flow rate by repeatedly opening and closing the laminated tube 24. Further, when the circulation is stopped, the state in which the laminated tube 24 is closed is continued, so that the inner surfaces of the laminated tube 24 are maintained in contact with each other. Since the laminated tube of the present invention has the above-described configuration, it does not deteriorate or stick even when used in a pinch valve.

This invention is also a roller pump provided with the above-mentioned laminated tube. FIG. 3 is a plan view showing an embodiment of the roller pump of the present invention. As shown in FIG. 3, the roller pump 30 includes a housing 31, a roller holder 34 that is rotationally driven by a motor, and a roller 33 attached to the roller holder 34. A laminated tube 32 is mounted between the inner wall of the housing 31 and the outer periphery of the roller holder 34. When the roller holder 34 starts rotating, the roller 33 moves in the rotation direction of the roller holder 34 while crushing the laminated tube 32, and sends out the fluid in the laminated tube 32. Therefore, the laminated tube 32 attached to the roller pump 30 is repeatedly opened and closed. When the rotation of the roller holder 34 is stopped, the laminated tube 32 is left closed at the stop position of the roller 33, and the inner surfaces of the laminated tube 32 are maintained in contact with each other. Since the laminated tube of the present invention has the above-described configuration, it does not deteriorate or stick even when used in a roller pump.

Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

Production Example 1 (Production of biaxially stretched film)
The endothermic peak on the crystal melting diagram when the number average molecular weight is 5.8 million and the differential scanning calorimeter (DSC) has a heating rate of 10 ° C./min is 345 ° C. and does not show a shoulder near 330 ° C. and contains a comonomer. First prepared PTFE fine powder. 25 parts by weight of hydrocarbon oil (“Isopar M” manufactured by ExxonMobil) as an extrusion aid is added to 100 parts by weight of the PTFE fine powder, and a round bar paste is extruded by an extruder having a cylinder inner diameter of 130 mm and an extrusion die of 16 mm. This was calendered at a speed of 28 m / min with a calender roll heated to 70 ° C. to obtain a tape. This tape was passed through a hot air drying oven at 250 ° C. to remove the extrusion aid, and a PTFE green tape having an average thickness of 200 μm and an average width of 180 mm was produced.
This unfired tape is first stretched 5 times in the longitudinal direction at a stretching temperature of 300 ° C. and a stretching speed of 200% / second using a biaxial stretching machine, and then in the transverse direction at a stretching temperature of 200 ° C. and a stretching speed of 50% / second. After stretching 5 times, fix it with a frame so that the film does not shrink, put it in an oven at 350 ° C. for 3 minutes, heat fix it, biaxial stretching with thickness 60 μm, porosity 93%, basis weight 10 g / m ² A membrane was obtained.

Production Example 2 (Production of biaxially stretched membrane)
A biaxially stretched film having a thickness of 10 μm, a porosity of 96%, and a basis weight of 0.9 g / m ² is obtained in the same manner as in Production Example 1 except that the green tape is stretched 10 times in the longitudinal direction and 30 times in the transverse direction. It was.

Production Example 3 (Preparation of binary fluororubber)
Fluororubber (Daikin Kogyo Co., Ltd. Daiel G-751), Carbon Black (Cancarb Corp. Thermax N-990), Magnesium Oxide (Kyowa Chemical Industry Co., Ltd. MA-150), and Calcium Hydroxide (Omi Chemical Co., Ltd.) CALDIC # 2000) was mixed with an open roll at a weight ratio of 100/20/3/6 (parts by weight), and then processed into a sheet having a thickness of 1 mm.

Example 1
The biaxially stretched membrane of Production Example 1 is wrapped around a core material having an outer diameter of 4 mm three times, and the fluororubber obtained in Production Example 3 is further wound about 4 times, and then placed in a mold. Primary vulcanization was carried out at 10 ° C. for 10 minutes. Thereafter, the core material was taken out from the mold, and subjected to secondary vulcanization at 230 ° C. for 24 hours in an electric oven to obtain a tube having an inner diameter of about 4 mm, an outer diameter of about 10 mm, and a length of about 100 mm.

Example 2
A tube was obtained in the same manner as in Example 1 except that the biaxially stretched membrane of Production Example 1 was wound 6 times around a core material having an outer diameter of 4 mm.

Example 3
A tube was obtained in the same manner as in Example 1 except that the biaxially stretched membrane of Production Example 1 was wound 12 times around a core material having an outer diameter of 4 mm.

Example 4
A tube was obtained in the same manner as in Example 1 except that the biaxially stretched membrane of Production Example 2 was used instead of the biaxially stretched membrane of Production Example 1.

Example 5
A tube was obtained in the same manner as in Example 2 except that the biaxially stretched membrane of Production Example 2 was used instead of the biaxially stretched membrane of Production Example 1.

Example 6
A tube was obtained in the same manner as in Example 3 except that the biaxially stretched membrane of Production Example 2 was used instead of the biaxially stretched membrane of Production Example 1.

Example 7
A perfluoro fluororubber (DAI-EL PERFLO GA-55, Daikin Industries, Ltd.) obtained by winding the biaxially stretched film of Production Example 1 around a core material having an outer diameter of 4 mm three times and further processing into a sheet shape having a thickness of 1 mm. The product was wound about 4 times, then placed in a mold and subjected to primary vulcanization at 160 ° C. for 10 minutes. Thereafter, the core material was taken out from the mold and subjected to secondary vulcanization at 180 ° C. for 4 hours in an electric oven to obtain a tube having an inner diameter of about 4 mm, an outer diameter of about 10 mm, and a length of about 100 mm.

Example 8
A tube was obtained in the same manner as in Example 7, except that the biaxially stretched membrane of Production Example 1 was wound 6 times around a core material having an outer diameter of 4 mm.

Example 9
A tube was obtained in the same manner as in Example 7 except that the biaxially stretched membrane of Production Example 1 was wound 12 times around a core material having an outer diameter of 4 mm.

Example 10
A tube was obtained in the same manner as in Example 7 except that the biaxially stretched membrane of Production Example 2 was used instead of the biaxially stretched membrane of Production Example 1.

Example 11
A tube was obtained in the same manner as in Example 8, except that the biaxially stretched membrane of Production Example 2 was used instead of the biaxially stretched membrane of Production Example 1.

Example 12
A tube was obtained in the same manner as in Example 9 except that the biaxially stretched membrane of Production Example 2 was used instead of the biaxially stretched membrane of Production Example 1.

Comparative Example 1
A tube was obtained in the same manner as in Example 1 except that the fluororubber obtained in Production Example 3 was wound directly around the core material. (Fluoro rubber tube with no stretched film on the inner surface)

Comparative Example 2
A tube was obtained in the same manner as in Example 7 except that perfluorofluororubber processed into a sheet having a thickness of 1 mm was directly wound around the core material. (Perfluoro fluororubber tube with no stretched film on the inner surface)

Each numerical value of the examples was measured by the following method.
As shown in FIG. 4, a load of 15 kg is applied to the center of the tube using a jig, the tube is left closed for 24 hours in a closed state, the load is removed, and the state of fixation of the inner surface of the tube is observed. Moreover, after removing the load, the peeling time until the closed state is released is measured. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 10 Laminated tube 11 Outer layer 12 Inner layer 20 Pinch valve 21 Pinch 22 Main body 23 Connection body 24 Laminated tube 30 Roller pump 31 Housing 32 Laminated tube 33 Roller 34 Roller holder

Claims (9)

An outer layer formed from an elastomer;
An inner layer formed from a polytetrafluoroethylene porous film provided on the inner side of the outer layer and obtained by stretching a non-fired or semi-fired body of polytetrafluoroethylene;
A laminated tube comprising: The laminated tube according to claim 1, wherein the outer layer and the inner layer are directly bonded. The laminated tube according to claim 1 or 2, wherein the polytetrafluoroethylene porous membrane is a polytetrafluoroethylene porous membrane stretched in a biaxial direction. The laminated tube according to claim 1, 2 or 3, wherein the elastomer is a fluorine-containing elastomer. The laminated tube according to claim 1, 2, 3, or 4, wherein the porosity of the polytetrafluoroethylene porous membrane is 40 to 99%. The laminated tube according to claim 1, 2, 3, 4, or 5, wherein the polytetrafluoroethylene porous membrane has a thickness of 5 to 150 µm. Step (1) of winding a polytetrafluoroethylene porous film around the core material;
A step (2) of obtaining an intermediate molded product by crosslinking the elastomer on the polytetrafluoroethylene porous membrane wound around the core material and coating and heating the uncrosslinked elastomer;
A step (3) of extracting a core material from the intermediate molded product to obtain a laminated tube;
The manufacturing method of the laminated tube of Claim 1, 2, 3, 4, 5 or 6 characterized by the above-mentioned. A pinch valve comprising the laminated tube according to claim 1, 2, 3, 4, 5 or 6. A roller pump comprising the laminated tube according to claim 1, 2, 3, 4, 5 or 6.

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