JPS6334121A - Method of lining of inner peripheral surface of hollow tubular body - Google Patents

Abstract

PURPOSE:To realize a simple and low cost lining, in which the adhesion property between a sheet having an ultra-high-molecular-weight polyethylene layer and a hollow tubular body is excellent and the wall thickness of a lining layer of which can be freely controlled, by a method wherein a sheet having the ultra-high-molecular-weight polyethylene layer is wound round a heat resisting core and, after that, inserted onto the inner surface of the hollow tubular body, integrally welded by heating and, after cooling, the core is removed. CONSTITUTION:A sheet having an ultra-high-molecular-weight polyethylene layer is wound round a heat resisting core so as to overlap its end parts to themselves. The heat resisting core must have an outer diameter smaller than the inner siameter of a hollow tubular body and at the same time a thermal expansion coefficient larger than that of the hollow tubular body. Next, the heat resisting core, round which the sheet is wound, is inserted in the hollow tubular body and, after that, heated up to a temperature exceeding the melting point of ultra-high-molecular-weight polyethylene, preferably a temperature within the range of about 140-280 deg.C so as to thermoweld the sheet having the ultra-high-molecular-weight polyethylene layer to the hollow tubular body in order to integrate both of them. The hollow tubular body with the integrated sheet having the ultra-high-molecular-weight polyethylene layer as a lining layer is cooled down together with the heat resisting core. Because the heat resisting core contracts itself by cooling, the core can be easily removed so as to manufacture a hollow tubular body with the lining layer onto its inner peripheral surface.

Description

[Detailed description of the invention] [Industrial application field] The present invention has high melt viscosity, excellent abrasion resistance and impact resistance,
Katsu a! The present invention relates to a method of lining the inner surface of a hollow tubular body such as a vibrator using ultra-high molecular weight polyethylene with a small number of abrasions.

[Prior art] X8 polymer polyethylene has better abrasion resistance, impact resistance, chemical resistance, and
self! 21 Despite having excellent properties such as lubricity and stress cracking resistance, it has not yet been widely used because it is difficult to mold.

In other words, ultra-high molecular weight polyethylene has a very high melt viscosity and poor melt fluidity, so it cannot be molded using conventional general molding methods, so it can be molded into round bars using special methods such as ram extrusion, forging, and press molding. , sheets, pipes, etc. are manufactured by forming plate-shaped bodies and performing secondary processing such as cutting.

When coating the inner surface of pipes, ultra-high molecular weight polyethylene has poor fluidity, so unlike conventional low-, medium-, and high-density polyethylene and polypropylene, steel pipes are preheated and coated with low-, medium-, and high-density polyethylene and polypropylene powder. Powder coating methods such as powder fluidized dipping and electrostatic coating, which coat the inner and outer surfaces of steel pipes by immersing them in a fluidized bed, cannot be performed.

On the other hand, a method of inserting an ultra-high polymer m-polyethylene pipe obtained through secondary processing into a pipe such as a steel pipe via an adhesive may be considered, but the adhesion between the pipe and the ultra-high-molecular polyethylene pipe is insufficient, and the It cannot be integrated into a tight inner lining pipe. Furthermore, since it is a secondary processed product, it is difficult to reduce the thickness of the lining layer made of ultra-high molecular weight polyethylene, and the cost is also high.

[Problems to be Solved by Chewing] The present invention has been made to solve the above-mentioned problems of the conventional art. It is an object of the present invention to provide a method for lining the internal surface of a hollow tubular body using ultra-high molecular weight polyethylene, which is inexpensive and allows the thickness of the lining layer to be adjusted arbitrarily.

[Means for Solving the Problems] That is, the present invention provides a film or sheet having at least an ultra-high polymer polyethylene layer having a coefficient of thermal expansion smaller than the inner diameter of the hollow tubular body and larger than that of the hollow tubular body. Wrap it around the heat-resistant core so that its ends overlap,
After inserting this into the inner surface of the hollow tubular body, it is heated above the melting point of the ultra-high molecular weight polyethylene to fuse and integrate it, and after cooling, the heat-resistant core is extracted from the inner circumferential surface of the hollow tubular body. This is the lining method.

In the present invention, a film or sheet having at least an ultra-high molecular weight polyethylene layer is used. The ultra-high molecular weight polyethylene used here is a polyethylene homopolymer,
Ethylene and small amounts of α-olefins, such as propylene,
Butene-1, hexene-1,4-methyl pentene-1
, including copolymers with octene-1, etc., and 13
It is preferable that the intrinsic viscosity in a 5° C. decalin solution is 8 or more because it has excellent abrasion resistance and impact resistance.

The film or sheet used in the present invention may be a single layer of ultra-high molecular weight polyethylene, or may be a multilayered product by laminating a base material layer thereon. Further, an adhesive layer may be provided between the ultra-high molecular weight polyethylene layer and the base layer.

Furthermore, in the present invention, an adhesive layer may be provided on the outer periphery of the film or sheet in order to improve the adhesion between the film or sheet containing at least ultra-high molecular weight polyethylene and the hollow tubular body.

In the present invention, the film or sheet forming the ultra-high molecular weight polyethylene layer (hereinafter simply referred to as a sheet) refers to a press sheet obtained by press molding, a cylindrical material obtained by extrusion molding, injection molding, forging molding, etc. Not only skive sheets etc. made by cutting are used, but also porous sheets (films) are used.

The above-mentioned porous sheet is a sheet in which particles of ultra-high molecular weight polyethylene are partially fused to each other on the surface and have voids. There are various ways to make this porous sheet.
It is not particularly limited. Among these, it is particularly preferable to introduce the ultra-high molecular weight polyethylene powder between rolling rolls or heating rolls, and at a molding temperature of 140 to 250.
This is a preformed porous sheet obtained by fusing the powder at a temperature within the range of .degree. That is, as described in JP-A No. 60-46215, ultra-high molecular weight polyethylene powder is supplied between at least two rolls rotating in opposite directions, and the molding temperature is 1.
It is a porous sheet in which the powders are fused together at a temperature of 40 to 250°C. This preformed porous sheet is made of ultra-high molecular weight polyethylene particles loosely bonded to each other, and although it has inferior tensile strength and elongation at break compared to fully densified sheets, it has the advantage of being able to be manufactured continuously at low cost. It is used as a preforming sheet for secondary processing.

The thickness of the sheet that forms the ultra-high molecular weight polyethylene layer is not particularly limited, but if it is too thick, there will be a large step when it is rolled, and if it is too thin, it may be necessary to wind it many times to achieve the desired thickness. times are required. Therefore, it is usually 25 μm to 500 μl, especially 100 μl to 300 μl.
Preferably, the range is .

In the present invention, as described above, other base material layers are wound around the outer periphery of a single-layer ultra-high molecular weight polyethylene sheet via an adhesive layer if necessary, or a multi-layered sheet is used in advance. It is also possible to form multiple layers of molecular weight polyethylene sheets. Examples of the base material used here include thermoplastic resins of the same or different types such as polyethylene, polypropylene, polyamide, polyester, and polystyrene, rubbers such as synthetic rubber and natural rubber, cloth, gold foil such as aluminum foil, etc. It will be done.

The adhesive layer provided between these base material layers and the ultra-high molecular weight polyethylene layer, or the adhesive layer provided on the outer periphery of the above-mentioned film or sheet, is usually an epoxy adhesive,
It is preferable to use a conventional adhesive such as a urethane adhesive, a polyolefin resin modified with an unsaturated carboxylic acid such as acrylic acid or maleic anhydride, or a derivative thereof.

Furthermore, the hollow tubular body as used in the present invention refers to joints such as straight pipes, deformed pipes, cheeses, elbows, etc. made of iron, steel, stainless steel, etc.

The heat-resistant core used in the present invention is not particularly limited, as long as it has a larger thermal expansion coefficient than the hollow tubular body described above and has heat resistance higher than the heating temperature.

Examples of these materials include metals such as cast iron, steel, copper, brass, aluminum, and nickel, synthetic resins such as tetrafluoroethylene resin, and composite materials thereof. Further, when metal is used for the core, the surface may be coated with fluorine or other resin to make it slippery during extraction.

The manufacturing method of the present invention will be described in detail below.

In the manufacturing method of the present invention, first, a sheet having at least an ultra-high molecular weight polyethylene layer is wound around a heat-resistant core so that the ends thereof overlap.

Since this heat-resistant core uses the wound sheet as the lining layer of the hollow tubular body, it needs to be smaller than the inner diameter of the hollow tubular body. It is necessary that the coefficient of thermal expansion is larger than that of the material.

Next, a heat-resistant core wound with a sheet having at least a superpolymer polyethylene layer is inserted into the hollow tubular body,
Above the melting point of ultra-high molecular weight polyethylene, preferably 140
The sheet having the ultra-high molecular weight polyethylene layer is thermally fused to the hollow tubular body by heating in a range of about 280°C to 280°C, and the two are integrated. The above heating temperature should be above the melting point and within a range that does not cause thermal decomposition, but considering thermal deterioration during heating,
A temperature of 0°C or lower is particularly desirable.

The timing of heating also varies depending on the size of the hollow tubular body and the heat-resistant core, the number of turns of the sheet having the ultra-high molecular weight polyethylene layer, etc., but it is sufficient as long as it is sufficient for thermal fusion. In general, the heating method is particularly 1. The method is not limited to II, and general methods such as a method of circulating a heating medium from inside the heat-resistant core or a method of heating from the outside with a band heater or the like may be used.

The hollow tubular body whose inner peripheral surface lining layer is the sheet having the integrally fixed ultra-high molecular weight polyethylene layer is cooled together with the heat-resistant core body. Since the heat-resistant core has a larger coefficient of thermal expansion than the hollow tubular body, it is manufactured by shrinking when cooled and easily being extracted.

The hollow tubular body thus obtained has a lining layer of a sheet having an ultra-high molecular weight polyethylene layer with excellent abrasion resistance and sliding properties on its inner surface.
It is useful as a pipe for transporting grains such as wheat, powder such as coal and sand, slurry, etc.

In the present invention, thermoplastic resins such as high, medium, and low density polyethylene, polypropylene, polyamide, polyester, polystyrene, polyvinyl chloride, thermosetting resins such as epoxy resins, phenol resins, etc. are used within the scope of the invention. In addition to synthetic resins and synthetic rubber, customary additives such as inorganic or organic fillers, antioxidants, ultraviolet inhibitors, crosslinking agents, dyes, nucleating agents, antistatic agents, and pigments are added to ultra-high molecular weight polyethylene. There is no problem even if an appropriate amount is blended.

[Example] Example 1 Ultra-high molecular weight polyethylene with a thickness of 100 μm and a width of 300 shoes (trade name: Bidayou Taffetalex, manufactured by Nippon Petrochemical Co., Ltd.)
The film was attached to a core made of polytetrafluoroethylene (PTFE) with an outer diameter of 45mm (thermal expansion coefficient of 10xlO-5/''C).
) is wrapped 23 times, and the outer circumference is further wrapped to a thickness of 100 mm.
A film of μ acid-modified polyolefin resin (trade name: 8 stone N Polymer L 5050, Nippon Petrochemical Co., Ltd.'tJ) was wound once, and the outer end was fixed. x 10-5/°C), set in an electric heating furnace, and heated at 220°C for 20 minutes. PTFE after cooling! The J core was extracted and a strong lining layer of ultra-high molecular weight polyethylene could be provided on the inner peripheral surface of the iron pipe.

[Effects of the Invention] Ultra-high molecular weight polyethylene has poor processability and is difficult to mold by conventional extrusion molding, injection molding, etc. It is difficult to apply powder coating methods to coat the inner surface of pipes, and even when a secondary processed product of ultra-high molecular weight polyethylene is inserted into a hollow tubular body such as a pipe, it is difficult to thin the lining layer or There are problems in terms of adhesion, etc.

On the other hand, according to the lining method of the present invention, these drawbacks can be overcome, the lining can be performed easily and inexpensively, and the lining can be performed easily and inexpensively, and the thickness of the lining layer can be adjusted arbitrarily.

Therefore, the present invention is suitably used as a method for lining the inner surface of a hollow tubular body such as a pipe.

Claims (1)

[Scope of Claims] 1. A film or sheet having at least an ultra-high molecular weight polyethylene layer is attached to a heat-resistant core having an inner diameter smaller than the inner diameter of the hollow tubular body and a coefficient of thermal expansion larger than that of the hollow tubular body at the end thereof. are wound so that they overlap and are inserted into the inner surface of the hollow tubular body, and then heated above the melting point of the ultra-high molecular weight polyethylene to fuse and integrate it, and after cooling, the heat-resistant core body is extracted. A method for lining the inner surface of a hollow tubular body. 2. The method for lining a circumferential surface of a hollow tubular body according to claim 1, wherein an adhesive layer is provided on the outer periphery of the film or sheet. 3. The method for lining the inner surface of a hollow tubular body according to claim 1 or 2, wherein the film or sheet is a multilayered body comprising an ultra-high molecular weight polyethylene layer and a base material layer. 4. The method for lining the internal surface of a hollow tubular body according to claim 3, wherein the ultra-high molecular weight polyethylene layer and the base material layer are laminated with an adhesive layer interposed therebetween. 5. The method for lining the inner surface of a hollow tubular body according to any one of claims 1 to 4, wherein the ultra-high molecular weight polyethylene has an intrinsic viscosity of 8 or more in a decalin solution at 135°C. 6. The method for lining the inner surface of a hollow tubular body according to any one of claims 1 to 5, wherein the film or sheet forming the ultra-high molecular weight polyethylene layer is porous.