HU188863B - Process for increasing corrosion resistance and insulating capability of structural units - Google Patents

Abstract

Engineering structures are covered with flexible film using adhesives contg. in aq. dispersion cationic polymers or polymer analogous materials to increase the corrosion resistance and insulating capacity of the structure. The treatment can be applied during construction or when faults develop.

Description

The present invention relates to a process for enhancing the corrosion resistance and insulating properties of structural members by combining the structural members with a flexible film and employing aqueous adhesive dispersions comprising cationic polymers and / or polymer analogous materials.

In practice, the pipes or containers used for transporting and storing liquids, gases, or containers. the elements of the various supporting structures are made of metal or concrete. To ensure that these metal structures provide adequate insulation and insulation. to withstand the chemical effects of transported, stored, or ambient media, they must either be made from alloys of high-weight alloys or have special, and therefore costly, polymer-based coating systems on their surfaces. In addition, the durability of the latter is rather limited, most of them require special equipment and surface preparation, which in practice is very difficult to provide, and in the case of damage to the protective layer most repairs are not possible, only a complete coating replacement. Made of concrete or. For reinforced concrete structures, the proper insulation and / or corrosion resistance of the concrete is provided by special formulations for chemical application of concrete, additional reinforcement and special coatings. Cracks and cladding due to movement of concrete structures require frequent and costly repairs.

Thus, the elimination of expensive structural elements, the economical production of pipes and containers with adequate insulation and corrosion resistance and retaining structures remain a formidable social need.

Completed metal or concrete pipe or sewer networks for design inaccuracies, corrosive and / or abrasive effects, traffic vibrations, soil subsidence, external flooding, etc. as a result, sealing of pipes, duct sections, and material continuity defects may result in loss of sealing. some of the water, sewage and fluids to be discharged into the sewerage network may be discharged outside the pipeline and, in the case of underground pipelines, into the soil. Liquid spills can cause environmental pollution, loss of material, risk of accident, groundwater contamination of pipes laid in the ground, or different drainages. The latter may further damage the stability of the network and may even cause the entire network and installed facilities, eg. also the destruction of roads and buildings. This phenomenon can be particularly problematic due to its specific soil mechanical and chemical properties in loess soils.

Several methods have been developed to repair sewer networks. For example, thixotropic materials, typically clay minerals such as bentonite, are pressed into the sewer. On the one hand, this method is only relevant for overhead lines. On the other hand, the thixotropic suspension pressed into the channel fills the leached cavities through the gaps in the channel, but it hardens, but its insulating capacity depends largely on the soil structure, the size of the cavities, the bottom and the groundwater conditions outside the channel.

In situ polymerization is also used to insulate the seals due to material continuity defects in the pipe joints: the pipeline is filled with an appropriate prepolymerizate or pre-condensate and the final molecular size in the pipe itself, preferably fitted with a film. The disadvantage of this method is that it requires complicated, special tools and reaction conditions, and it also results in significant material loss. The material loss, on the one hand, is due to the fact that the tube must be completely filled without bubbles. With real tubes, bubbles on the wall, especially on the top surface of the tube, are difficult to eliminate.

On the other hand, the loss of material means that large quantities of valuable material can leak through the gaps and cracks. And sealing major pipe gaps so that the pipe can be filled in half can mean additional costs - e.g. finding, exploring, etc. which may call into question the economics of applying the method instead of laying a new pipeline.

A further problem may be that the protective layer thus formed is rigid: it may rupture again for new mechanical effects.

For containers that have lost their sealing capacity (liquid barrier) or corrosion resistance, the original casing is repaired or replaced, but this usually does not work because it is again malfunctioning due to physical and mechanical effects. More recently, especially in food storage applications, the use of multi-layer mesh reinforced resin insulation, which is expensive, labor-intensive, and requires a particular technological discipline, is appropriate.

The idea of coating the structural members of pipes, tanks, holders with flexible materials resistant to mechanical and chemical effects was also raised. For some liners, it is sufficient to fix the applied film by some mechanical method. However, for a significant part of the storage facilities, e.g. in which there is mixing, or in the case of pipes, several meters long or even not straight, only a flexible film can be used in combination with their structural material. Likewise, repairing finished pipelines, which are often under construction, sometimes under construction, sometimes on complex trails, can only be accomplished by providing the correct bond strength.

In the course of solving the problems of the urban rainwater drainage system, we have set the goal of bonding the flexible foil drawn into the drainage system to the concrete elements.

The problem during the work was that we could not clean and dry the canal so that different, eg. polyvinyl chloride, polyethylene, polypropylene, polyurethane and the like. solvent-based or cross-linking adhesives capable of bonding base films to 2188 863. In practice, the aqueous polymer dispersions which adhere to the concrete that has been cleaned do not glue the films.

In our adhesive experiments, it has been surprisingly found that when the aqueous medium based polymer-based adhesive dispersion contained cationic polymers and / or polymer analogues, the surface of both aqueous concrete and plastic-based flexible films would be well bonded. , so they could be combined with such glue.

The method proved to be suitable for metal, e.g. iron or aluminum surfaces with polymeric films 1.

The practical application and further details of the process we have found are illustrated in the following examples.

Example 1 (Comparative)

A special pvc film was applied to both sides of the synthetic woven substrate. Two 100 x 100 mm pieces were cut out of this and applied with an adhesive dispersion of 50% active ingredient based on polyvinyl alcohol stabilized with polyvinyl acetate (200 g / m ² ). One foil was glued with one 50 x 50 x 50 mm concrete cube and the other with 50 x 50 mm fluting corrugated board. After 24 hours, the corrugated board had little mechanical effect on the film, and on the vertical film the weight of the concrete cube, ₃ g, could not be retained.

Example 5

The procedure of Example 1, A, 1 was to apply an aqueous pvc dispersion to one side of the synthetic, looped carrier. The glue contained 1% cationic polyacrylamide as a stabilizer and 0.25% cetylpyridinium chloride. The adhesion was good on both the treated and tissue sides of the film.

Example 6

Example 1 except that the flexible film was polyethylene, polypropylene, and the like. polyurethane (the latter applied to a synthetic crocheted fabric) was used. The adhesive used as a stabilizer is 1.5% cationic polyamide amine, respectively. 0.5% polyethyleneimine and 1.5% dodecyltrimethylammonium bromide as an additive. Bonding was appropriate for each polymer film used.

Example 7

Example 1 except that aluminum and carbon steel sheets were used instead of polymer films. 70 g / m ² of adhesive containing 0.1% dodecylpyridinium chloride was applied to these adhesive-coated sheets with 50 * 50 mm polyvinyl chloride or. polyurethane films were glued. After 24 hours, a significant force of 0.35 kg / 10 mm was required to peel the film.

Example 2

Example 1 except that 1% cetyltrimethylammonium bromide was added to the adhesive dispersion. In this case, the weight of the concrete cube was retained by gluing, and when the corrugated sheet was peeled off, a layer of paper remained on the film 45.

Example 3 (Comparative)

Example 1 except that the carrier was a natural loop and the adhesive was based on a copolymer of vinyl acetate-acrylic acid ester stabilized with carboxymethylcellulose.

The bond strength according to Example 1 was bad 55.

Example 4

Example 3 except that 3% cationic starch was added as a stabilizer in the adhesive dispersion. Similar to Example 2, the adhesive strength was good.

Example 8

In Example 2, the adhesive was in one case 0.75% stearylamidoethyl diethylmethylammonium sulfate and in another case 2.0% oleic acid amidoethyl diethylammonium chloride, in the third case, 0.5% cetyl pyridinium chloride and 0.75% fatty alkyl triethylammonium chloride. The gluing was suitable as in Example 2.

The examples presented show that aqueous dispersion adhesives containing cationic polymers and / or polymer analogues well associate a wide variety of flexible films with important structural elements.

Depending on the application and the need for use, the flexible film may also be partially glued, but especially in the case of liquid barrier and corrosion protection, it is advisable to glue over the entire surface so that minor leakage defects can be localized and detrimental or negligible. This is an important requirement especially for food pushers.

It is advisable to pre-assemble the flexible foil to the largest size, which is still air-tight and water-tight at the factory.

188,863

The prefabricated bag liner, made to exact dimensions, must be pressed against the surface of the element until the adhesive has set.

The least labor-intensive task is to inflate the bag, which is made air-tight at the factory or on-site, by means of a valve or airlock, after the installation and adjustment of the critical points. The internal overpressure is determined in such a way that it cannot damage the bag or the element and is maintained until the adhesive has set. The greatest advantage of this method is that the bag-like liner takes on the regular or irregular shape of the tube or container and ensures that the liner is maintained at all points on the surface.

Claims (4)

Claims CLAIMS 1. A method of enhancing the corrosion resistance and insulating properties of structural members by combining the structural members with a flexible film and employing aqueous adhesive dispersions containing 0.1 to 3.5% of cationic polymers and / or polymer analogs. Process according to claim 1, characterized in that the flexible films are preferably polyvinyl chloride, polyethylene, polypropylene, polyurethane films, optionally natural and / or 5 reinforced artificial or woven inserts. The process according to claim 1 or 2, wherein the cationic polymer and / or the polymer analogue material is preferably a quaternary alkyl 0 ammonium salts, e.g. dodecyl, hexadecyl - trimethyl - ammonium chloride, bromide, sulfate, stearyl - amido - ethyl - diethyl - methyl - ammonium - sulfate, oleic acid - amido - ethyl - diethyl - ammonium chloride, fatty alkyl - triethyl - ammonium - chloride and / or alkyl ¹⁵ - pyridinium salts such as. dodecyl, hexadecylpyridinium chloride, bromide, sulfate additives, as cationic polymers e.g. cationic starch, polyacrylamide, polyethyleneimine, polyamide amine are used. A method according to any one of claims 1, 2, 3, characterized in that the prefabricated flexible foil liner is made air-tight after being partially or completely pre-assembled and maintained therein with an airtight substance until the adhesive is set.