JPS6219638B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing corrosion of metal products, and particularly to a method of preventing corrosion of metal products using anticorrosion tape. In recent years, there has been a significant increase in the installation of pipelines such as large-capacity power transmission cables, as well as fluid transportation for oil, gas, water, etc., and as most of them are laid underground, buried metal products are becoming increasingly popular. In particular, the problem of corrosion of steel pipes is an important issue. In order to protect buried metal products over a long period of time, it is known to use the cathodic protection method, which is an active protection method, and at the same time, to prevent corrosion by installing a partition wall on the surface of the metal product to isolate it from the outside air. In particular, anticorrosive materials with high electrical insulation properties are required. Conventionally, coatings made of bituminous substances mainly made of asphalt have been relied upon as such anti-corrosion materials, but in recent years, with the remarkable development of the polymer chemical industry, coatings made of plastics are being put into practical use. but,
All of these coatings are thermoplastic, and have the disadvantage that they soften at high temperatures, become vulnerable to physical impact and break, or lose adhesion to metals, causing the coating to shift. . In other words, in pipelines for transporting fluids such as petroleum and heavy oil, there is a tendency to pressurize and heat the fluid to reduce its viscosity and improve transport efficiency. The drawback is that it is limited to temperatures below ℃. Conventionally, in order to improve this drawback, a method has been proposed in which the outer surface of the tube is coated with an unvulcanized rubber or semi-vulcanized rubber sheet and vulcanized using the heat of the supply pipe, but the sheet (unvulcanized rubber sheet) itself Since a vulcanizing agent is blended into the material, vulcanization progresses gradually during storage before construction, resulting in poor adhesion to metal during construction, making it difficult to obtain an integrated anticorrosion layer. In other words, it lacked long-term storage stability before construction. An object of the present invention is to provide a novel method for preventing corrosion of metal products using an anticorrosion tape that overcomes the above-mentioned drawbacks. The present invention provides a base material selected from the group consisting of a crosslinked rubber sheet, a crosslinked plastic sheet, and a crosslinked stretched plastic sheet on the surface of a metal product.
100 parts by weight of halogenated butyl rubber alone or a mixture of halogenated butyl rubber and ethylene propylene terpolymer and 20 to 20 parts of polyisobutylene resin
When protecting a metal product from corrosion by overlapping layers of anticorrosion tape made by pasting an adhesive compound containing 80 parts by weight as an adhesive layer to form an anticorrosion layer, the surface of the metal product is coated with halogen in advance. After applying an undercoat containing a vulcanizing agent capable of vulcanizing butyl rubber, the anticorrosive tape is wrapped in layers and the adhesive layer of the anticorrosive tape is vulcanized by the vulcanizing agent contained in the undercoat. It is characterized by In the present invention, the undercoat applied to the surface of the metal product has excellent adhesion to the metal surface and contains a vulcanizing agent capable of vulcanizing halogenated butyl rubber, so the undercoat layer is applied to the surface of the metal product. Corrosion protection with excellent heat resistance is achieved by wrapping the tape in layers immediately after application and before the solvent in the primer evaporates, and vulcanizing the adhesive layer of the tape with the vulcanizing agent in the primer. A coating can be obtained. In other words, if the vulcanizing agent for the tape adhesive is added to the primer and the tape is wrapped in layers before the solvent evaporates, the vulcanizing agent in the primer will migrate to the adhesive layer and become integrated with the tape during installation. It is characterized by vulcanizing the adhesive and vulcanizing it gradually after installation. Incidentally, if the material is heated at this time, vulcanization will proceed in a shorter time, and a corrosion-resistant layer with excellent heat resistance can be formed. Examples of the vulcanizing agent contained in the undercoat used in the present invention include alkylphenol resins, brominated alkylphenol resins, and the like. Among the anticorrosion tapes used in the present invention, examples of the base material used include crosslinked vinyl chloride sheets, crosslinked synthetic rubber sheets, and crosslinked stretched polyethylene sheets. The adhesive layer is mainly composed of halogenated butyl rubber, which has extremely low permeability to gases such as air and has a fast vulcanization rate, and polyisoptylene resin, which has strong adhesiveness.The halogenated butyl rubber is chlorinated butyl rubber. (For example, trade name: Etsuobutyl HT, manufactured by Etsuso Kagaku Co., Ltd.), brominated butyl rubber (For example, trade name: Hycar 2202, manufactured by Gritsudoritsu Co., Ltd., trade name: Polyservomobutyl X2, manufactured by Polycer Co., Ltd.), etc. . In addition, ethylene propylene terpolymer (EPT) can be mixed with halogenated butyl rubber to improve electrical insulation. EPT includes, for example, product name: Nordel 1070 (manufactured by Dupont), product name: Mitsui EPT.
(manufactured by Mitsui Petrochemical Co., Ltd.), product name: Esplen 501
(manufactured by Sumitomo Chemical Co., Ltd.), etc. Further, examples of the polyisobutylene resin include, for example, the product name: Vistanex LMMH (manufactured by Etsuo Kagaku Co., Ltd.), and the product name: Opanol B-10 (manufactured by Padeissier Alinin Co., Ltd.). In addition, a filler, a plasticizer, an anti-aging agent, etc. can be added to the adhesive layer as required. The reason for limiting the amount of polyisobutylene resin to 100 parts by weight of halogenated butyl rubber or a mixture of halogenated butyl rubber and EPT in the adhesive layer is that less than 20 parts by weight results in poor adhesiveness;
This is because if it exceeds 80 parts by weight, calendering properties will be poor and thermal deformation will increase. The upper limit of the amount of EPT that can be blended into halogenated butyl rubber is 50
% or less, because if it exceeds 50%, the crosslink density decreases. The present invention will be explained with reference to the following examples and comparative examples. Example 1 and Comparative Example 1 After irradiating a 0.5 mm thick polyethylene sheet with an electron beam at a dose of 10 Mrad, it was stretched to a thickness of 0.45 mm using a stretching device.
A base sheet was obtained by stretching to a length of mm. The adhesive layer is made of brominated butyl rubber (product name:
Polycerpromobutyl X2) 50 parts by weight, ethylene propylene terpolymer (Product name: Mitsui)
EPT1045) 50 parts by weight, polyisobutylene resin (product name: Vitanex LMMH) 30 parts by weight, talc (manufactured by Kunimine Chemical Industry Co., Ltd.) 30 parts by weight, process oil (product name: Komolex No. 2, Nippon Oil) (KK)
25 parts by weight, carbon black (product name: Asahi)
70, manufactured by Asahi Carbon Co., Ltd.) 2 parts by weight and anti-aging agent (trade name: Nokuratsuku 200, manufactured by Ouchi Shinko Chemical Co., Ltd.) 1 part
The adhesive compound obtained by kneading parts by weight with an open roll was laminated to the above base sheet with a thickness of 0.4 mm using a calender roll, and cut into a tape shape to obtain an anticorrosive tape. The primer to be applied to the surface of metal products is 5 parts by weight of acrylic rubber (trade name: Toracron PS-250, manufactured by Toa Paint Co., Ltd.), zinc white (trade name: Zinc white 1)
1 part by weight of stearic acid (manufactured by Nippon Oil & Fats Co., Ltd.), and 2 parts by weight of carbon black (trade name: Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) in an open roll. This was mixed with 8 parts by weight of alkylphenol resin (trade name: Tatsuki Roll 201, manufactured by Sumitomo Chemical Co., Ltd.) and toluene (Nippon Oil Co., Ltd.).
Co., Ltd.) and a rubber volatile oil (Nippon Oil Co., Ltd.) were added thereto, and the mixture was dissolved to a concentration of about 300 cp at 25° C. using a B-type viscometer. After polishing with #240 sandpaper and cleaning the surface by wiping with toluene, the above-mentioned primer was applied to a thickness of 100 μm. Immediately thereafter, the above-mentioned anti-corrosion tape was wrapped in layers and left at room temperature for 24 hours. . Next, this iron plate was immersed in hot water at 100°C, taken out after one month, and the 180° peeling adhesive strength was measured at room temperature, 85°C, and 105°C. For comparison, PLICOFLEX Primer No. 105 and PLICOFLEX Primer No. 245 were used as a commercially available primer and polyester anticorrosion tape, respectively.
A similar test was conducted using a hand roll type (USA). The results of these tests are shown in Table 1. Further, in the same manner as described above, immediately after applying the above-mentioned primer to a steel pipe having an inner diameter of 75 mmφ, the anti-corrosion tape obtained as described above was wrapped in layers and left at room temperature for 24 hours. Next, this steel pipe was placed in a sandy area 1m below the ground with 95°C warm water circulating inside it.
After burying it for several months, take it out and measure its appearance and insulation resistance with a megger (simple insulation resistance tester (1000V,
2000MΩ), manufactured by Yokogawa Electric Corporation). For comparison, similar tests were conducted using the commercially available primer and polyethylene anticorrosion tape described above. These results are shown in Table 2.

【table】

[Table] As is clear from Tables 1 and 2, the performance of the anticorrosion coating layer obtained by the method of the present invention was significantly superior to that of the conventional method. In addition, since the anticorrosive tape used in the method of the present invention does not contain a vulcanizing agent, it has excellent long-term storage stability before use. It has excellent storage stability, and the adhesive layer of the anticorrosive tape is safely vulcanized by the heat generated when metal products are used after construction, such as when operating pipelines, providing stable corrosion protection for long periods of time even at high temperatures. Therefore, the practical value of the present invention is extremely large.

Claims (1)

[Scope of Claims] 1. On the surface of a metal product, halogenated butylgol alone or a combination of halogenated butyl rubber and ethylene propylene terpolymer is applied to a base material selected from the group consisting of a crosslinked rubber sheet, a crosslinked plastic sheet, and a crosslinked stretched plastic sheet. Metal products are protected against corrosion by wrapping an anti-corrosion tape made of an adhesive layer laminated with an adhesive compound mainly composed of 100 parts by weight of a mixture and 20 to 80 parts by weight of a polyisobutylene resin to form an anti-corrosion layer. In this process, an undercoat containing a vulcanizing agent capable of vulcanizing halogenated butyl rubber is applied to the surface of the metal product in advance, and then the above anti-corrosion tape is wrapped in layers to coat the vulcanizing agent contained in the coating. Therefore, a method for preventing corrosion of metal products, which comprises vulcanizing the adhesive layer of the anticorrosion tape.