JPS6237066B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating composition for corrosion prevention, coloring, and anti-slip on the surfaces of so-called galvanized steel towers, such as power transmission towers and microwave towers, which are coated with galvanized steel, particularly hot-dip galvanized coatings. Conventionally, galvanizing has been applied as a long-term corrosion protection method for steel materials and steel products, and it is well known that large structures such as power transmission towers and microwave towers are coated with hot-dip galvanizing. It is as follows. This corrosion prevention method is far superior to general paint coating methods, but as air and water pollution has progressed recently, zinc has been depleted significantly, and the long-term corrosion prevention effect is no longer as good as before. The current situation is that we cannot expect much. In order to make the long-term corrosion protection inherent in galvanized plating effective, it is necessary to have an organic coating on the galvanized surface to prevent contact with anti-corrosion factors such as water and the atmosphere. As structures have recently become larger in size, there has been a strong demand for colored and aesthetically pleasing structures for reasons of necessity as aviation beacons or from the aesthetic point of view of harmonizing with the environment. For the reasons mentioned above, oil-based paints or synthetic resin-based paints are currently applied to galvanized surfaces. However, this type of paint has the disadvantage that the paint film peels off or separates from the surface of the galvanized layer at an early stage, and is not always satisfactory. Furthermore, as structures become larger, it becomes difficult to repaint for maintenance, so long-term durability and
From the viewpoint of color retention, the use of tar epoxy resin paints, unsaturated polyester resin paints, or synthetic resin paints such as epoxy resin enamels and polyurethane resin enamels is being considered. However, all of these had poor adhesion. On the other hand, it is common for people to go up and down power transmission towers for maintenance and inspection purposes, but because the coating film obtained from conventional paint compositions is smooth, it is easy to slip when going up and down, which is a big problem. It was hot. The present invention aims to eliminate or improve the drawbacks of conventional paints as described above, and has excellent adhesion to galvanized power transmission towers.
The object is to provide a coating composition with excellent anti-slip properties. That is, the present invention provides (a) a resin composition consisting of 99 to 60% by weight of an epoxy resin containing at least two or more epoxy groups at the end and 1 to 40% by weight of a polyvinyl butyral resin...100 parts by weight, ( b) At least one compound selected from oxyacids and metal oxides
...1 to 250 parts by weight, and (c) aggregate ...10 to 500 parts by weight, relating to a coating composition for power transmission towers. The epoxy resin used in the present invention consists of a mixture of an epoxy resin containing at least two or more epoxy groups at the end and a crosslinking agent that chemically reacts with the epoxy resin. Examples of the epoxy resin include linear bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol type epoxy resin, polyphenol type epoxy resin, aliphatic type epoxy resin, aromatic type epoxy resin, and cycloaliphatic type epoxy resin. resin,
There are ether ester type epoxy resins, etc., and commercially available product names include Epicote (trade name manufactured by Ciel Chemical), Epiclon (trade name manufactured by Dainippon Ink and Chemicals), Araldite (trade name manufactured by Ciba-Geigy), etc. is cited as a representative example. These are not limited to the use of only one type, but it is also possible to use two or more types in combination to bring out the characteristics of each. The crosslinking agent used in the composition of the present invention has a group that reacts with the epoxy group or hydroxyl group contained in the epoxy resin molecule, and is commonly used as a crosslinking agent for epoxy resins. Either is fine. For example, aliphatic or aromatic polyamines such as diethylenetriamine, triethylenetetramine, metaxylylenediamine, metaphenylenediamine, heterocyclic diamine, dimethylaminomethylphenol,
Tris(dimethylaminomethyl)phenol, secondary and tertiary amines such as piperidine, polyamide resins, amino compounds such as amine adducts (generally known as amine adducts), tolylene diisocyanate, hexamethylene diisocyanate, etc. In addition to isocyanate compounds (including blocked isocyanates), examples include phenolic resins, acid anhydrides, melamine resins, urea resins, etc.
Since the object of the present invention is generally large steel materials, the chemical reaction between the epoxy resin and the crosslinking agent proceeds at room temperature or forced drying, and the amino compounds that involve the chemical reaction with the epoxy group are the most suitable. preferable. The feature of the present invention is that, as described below, the oxygen-hydrochloric acid and/or metal oxide contained in the composition chemically reacts with the galvanized surface and imparts adhesion to the coating film. However, especially when phosphates are used in combination with other oxysaccharides and/or metal oxides, chelate bonds are formed between phosphoric acid and hydroxyl groups in epoxy resins and polyvinyl butyral resins via metal ions. Therefore, the effect of imparting strong adhesion can be obtained. Therefore,
When a crosslinking agent is mixed into the mixture of the epoxy resin and polyvinyl butyral resin of the present invention, if the crosslinking agent is of a nature that involves a chemical reaction with the hydroxyl group in the resin composition, the crosslinking agent for the resin composition is used. It is preferable to adjust the amount to an equivalent amount or less so that hydroxyl groups in the resin composition molecules remain. The polyvinyl butyral resin used in the present invention has an average degree of polymerization of 250 to 2000, preferably 250 to 2000.
1000, degree of butyralization 57-75 mol%, preferably
It is 57-70 mol%. The mixing ratio of the epoxy resin and polyvinyl butyral resin is 99-60% by weight of the epoxy resin and 1-40% by weight of the polyvinyl butyral resin, preferably 95-80% by weight of the former and 5-20% by weight of the latter. In the present invention,
The purpose of using polyvinyl butyral resin is to further promote the chelate bond with the phosphate contained in the composition, to give the coating film long-term flexibility, and to strengthen the adhesion to the galvanized surface. It is for the purpose of The adhesion of coatings to active non-ferrous metal surfaces such as galvanized metal is not as good as that of steel surfaces, and especially with epoxy resins, the coating hardness increases as the crosslinking density increases due to the progress of chemical reactions. On the other hand, the flexibility decreases and the adhesion strength gradually decreases, but the combination of polyvinyl butyral resin, which is a polymeric and thermoplastic resin, as in the present invention, is extremely effective in alleviating the aforementioned coating film deterioration. It is. The effect of adding polyvinyl butyral resin as described above increases as the amount added increases, but if the amount exceeds the range for the epoxy resin, it may cause a decrease in the water resistance of the coating film, deterioration of painting workability, etc. Undesirable. The oxyacids used in the present invention include chromic acid, phosphoric acid (including condensed phosphoric acid), boric acid, molybdic acid, phosphomolybdic acid, silicomolybdic acid, tungstic acid, phosphotungstic acid, and silicotungstic acid. It is a salt consisting of various metals. For example, strontium chromate, calcium chromate, lead chromate, zinc chromate, zinc chromate, zinc molybdate, calcium molybdate, zinc tungstate, calcium tungstate, magnesium tungstate, zinc phosphate, lead pyrophosphate, lead orthophosphate, Lead metaphosphate, aluminum phosphate, tin orthophosphate, tin pyrophosphate, tin oxyphosphate, zinc tetraborate, zinc metaborate, lead metaborate, lead tetraborate, barium metaborate, etc. can be used. The metal oxides used in the present invention are oxides of chromium, molybdenum, tungsten, manganese, etc. For example, chromium trioxide, molybdenum trioxide, tungsten trioxide, manganese dioxide, etc. can be used. These oxyacid salts and metal oxides described above can be used alone or in a mixture in any proportion. In particular, when the above-mentioned phosphate is used as an oxysalt component in combination with other oxysalts and/or metal oxides, the phosphoric acid generated by its hydrolysis can be used as an oxysalt component and/or the metal in the metal oxides. Since it is thought that a chelate compound is formed between the hydroxyl groups in the epoxy resin and the polyvinyl butyral resin via ions, its use is most preferable. The amount of the oxyacid salt and/or metal oxide used in the present invention varies greatly in reactivity to the galvanized surface, corrosion resistance, etc. 1 to 250 parts by weight, preferably 5 to 150 parts by weight, per 100 parts by weight of the resin composition mixed with butyral resin.
Parts by weight. As mentioned above, in the present invention, when phosphate is used as an essential component in combination with other oxysaccharides and/or metal oxides other than phosphate, the effects of the present invention can be further enhanced. However, it is preferable that the mixing ratio of phosphate and other oxyacid salts and/or metal oxides is about 95 to 30% by weight: 5 to 70% by weight. In the above, if the amount of the oxyacid salt and/or metal oxide is less than 1 part by weight, the effect of forming a chemical conversion film and the effect of forming a chelate on the galvanized surface cannot be expected. On the other hand, if the amount is more than 250 parts by weight, it is not preferable because it tends to impair the adhesion of the coating film to galvanizing. As described above, the present invention uses a resin composition consisting of an epoxy resin and a polyvinyl butyral resin, as well as an oxyacid salt and/or a metal oxide as essential components, and has a synergistic effect on galvanized surfaces. It imparts even stronger adhesion, and by using aggregate in combination, the anti-slip effect on the surface of the coating can be further improved. Examples of the aggregate used in the present invention include those commonly called aggregates such as sand, gravel, silica sand, emery, and glass beads, and these can be used alone or in combination of two or more. . This component imparts a suitable level to the surface of the coating layer and enhances the anti-slip effect. The aggregate component is used in an amount of 10 to 500 parts by weight, preferably 50 to 300 parts by weight, based on 100 parts by weight of the composition comprising the epoxy resin and polyvinyl butyral resin. In the above range, if the amount used exceeds 500 parts by weight, the roughness of the coating film surface will be too large, and there will be a tendency for foaming when overcoating, and the adhesion of the coating film will decrease, resulting in adverse effects. If the amount is less than 10 parts by weight,
It has no effect of imparting roughness to the surface of the coating film, and has no anti-slip effect at all. As described above, the present invention provides a composition in which a resin composition and at least one component selected from an oxyacid salt and a metal oxide are present in the above-mentioned quantitative ratios, thereby making it strong against the surface of a galvanized coating. It is possible to obtain a coating film that has good adhesion and maintains its effect for a long period of time, and the effect of the aggregate component imparts an anti-slip effect to the coating film surface. In the present invention, the above-described components are essential, but other resins that are compatible with the coating composition may also be added within a range that does not impair the object of the present invention. Furthermore, if desired, zinc powder,
Rust-preventing pigments such as lead compounds, extender pigments such as talc and silica, color pigments such as iron oxide, carbon black, and titanium oxide, anti-settling agents, anti-sagging agents, bituminous substances such as asphalt, tar, pitch, and surfactants. agent,
Additives such as surface conditioners, coupling agents, chelate compounds, solvents, etc. for further promoting the adhesion of the coating film can be added. When an organic solvent other than water is used as a solvent in the present invention, at least one alcoholic solvent is used to assist in elution or hydrolysis of metal ions of oxyacid salts and metal oxides in the composition. Alternatively, it is preferable that the composition contains approximately 3% by weight or less of water based on the solvent. The coating composition comprising the above-mentioned components of the present invention is applied to a galvanized surface by a known method such as a brush, spray, roller, spatula, trowel, etc. to obtain a dry film thickness of about 10 to 1000 microns, A coating film having the above effects can be obtained by causing a chemical reaction between the epoxy resin and the crosslinking agent and curing the coating film under conditions necessary for drying the coating film.
Therefore, depending on the use and purpose of the steel tower, for example, polyurethane resin paint, epoxy resin paint, chlorinated rubber paint, vinyl chloride resin paint, etc. can be applied in any color to a thickness that does not lose the anti-slip effect of the present invention. It is possible to apply an overcoat, or to apply the composition of the present invention after previously applying an epoxy resin-based or polyurethane resin-based primer. The coating film obtained from the coating composition of the present invention exhibits strong durability against long-term exposure, and has stable adhesion over a long period of time without peeling or detaching in a short period of time as in the case of conventional coatings. It has an anti-slip effect. Next, specific effects of the present invention will be shown by examples.
In addition, "part" or "%" in Examples and Comparative Examples means "part by weight" or "% by weight". Example 1 Epoxy equivalent 450-500 and epoxy equivalent 230-270
An epoxy resin obtained by mixing the epoxy resin and the crosslinking agent in an equivalent ratio using a linear bisphenol type epoxy resin consisting of a 1:1 mixture of epoxy resins and a polyamide resin with an active hydrogen equivalent of 130 as a crosslinking agent. A coating composition having the composition shown in Table 1 was prepared by combining a resin composition and a polyvinyl butyral resin having an average degree of polymerization of about 260 and a degree of butyralization of 60 mol%. For comparison, a coating composition other than the one according to the invention was also prepared in the same manner. The resulting composition is mixed with methyl isobutyl ketone:n-butyl alcohol as needed.
Using a mixed solvent of 1:1 (weight ratio), the viscosity was adjusted to be suitable for brush painting, and the coating was applied to the hot-dip galvanized surface to a dry film thickness of 250 microns to obtain a coating layer, and then heated at 20°C. After drying for 7 days under conditions of 75% RH, it was subjected to a comparative test.

[Table] Example 2 Linear bisphenol type epoxy resin with epoxy equivalent of 900 to 1000 and active hydrogen equivalent as crosslinking agent
An epoxy resin composition obtained by mixing an epoxy resin and a crosslinking agent in an equivalent ratio using a polyamide resin of 150, an average degree of polymerization of about 600, and a degree of butyralization.
A coating composition having the composition shown in Table 2 was prepared by combining 72 mol% of polyvinyl butyral resin. For comparison, a coating composition other than the one according to the invention was also prepared in the same manner. Each of the obtained compositions was mixed with methyl isobutyl ketone:butyl alcohol=1:1 as needed.
Using a mixed solvent consisting of (weight ratio), adjust the viscosity to be suitable for brush coating work, and apply it to the hot-dip galvanized surface with a brush to a dry film thickness of 200 microns.
After drying for 7 days at 20° C. and 75% RH, it was subjected to a comparative test.

[Table] Comparative experiment 1 Invention samples No. 1 to 4 obtained as described above
In order to test the adhesion of the coating film to the initial galvanized surface using the test specimens of comparative samples No. 1 to 7, we used a cutter knife to cut the coating film vertically at 3 mm intervals reaching the galvanized surface. Insert cutting lines that cross at right angles to the 11 horizontal lines of the book to form 100 squares. Next, cellophane tape is pressed onto the squares, the cellophane tape is instantly peeled off, and the number of remaining squares is expressed as a percentage. On the other hand, using another specimen, two cutting lines reaching the galvanized surface diagonally crossing in the center of the specimen were made, and the specimen was exposed outdoors for three years. After three years have elapsed, the paint film surface is observed to confirm the presence or absence of paint film defects and abnormalities, and then the remaining paint film of the same specimen is treated with the same procedure as the initial adhesion test, and the judgment method is performed. The adhesion quality after long-term exposure is determined by: The results obtained are shown in Table 3.

[Table] Comparative Experiment 2 Samples No. 1 to 4 of the present invention obtained as described above
and comparative samples No. 1 to 7 using test pieces 0.5 x 5 x 5 cm
Place a rubber plate with a shaped hook on the surface of the specimen, and then place a 1 kg weight on the surface of the rubber plate. Attach a spring scale to the hook of the rubber plate, pull the spring scale in a direction parallel to the specimen, and measure the force when the rubber plate starts to move.
Read from the scale of the spring scale as Kg/25cm ² . The results obtained are shown in Table 4.

[Table] Comparative Experiment 3 The obtained composition was adjusted to a viscosity suitable for brush painting using a mixed solvent consisting of methyl isobutyl ketone and n-butyl alcohol = 1:1 (weight ratio) as necessary, and melted. After coating the galvanized surface to a dry film thickness of 500 microns to obtain a coating layer, it was dried for 7 days at 20° C. and 75% RH. Using the specimens of the present invention and comparative samples obtained as described above, a 0.5 x 5 x 5 cm rubber plate was placed on the surface of the test piece, and a 500 g weight was placed on the surface of the rubber plate. While lifting one end of the specimen at a speed of 1 m/min, the specimen was tilted and the angle at which the rubber plate began to move was determined. The results obtained are shown in Table-5. Comparative Experiment 4 The specimen from Comparative Experiment 3 was immersed in water and pulled up to make the coating surface wet, and the same operation as above was performed to read the starting angle of movement of the rubber plate on the wet surface. The results obtained are shown in Table-5. Comparative Experiment 5 For arbitrary coloring, commercially available polyurethane resin enamel was applied with a brush to a coating thickness of 30 microns on the surface of the specimen obtained by the same procedure as Comparative Experiment 3.
It was dried for 7 days at 20°C and 75% RH.
Using the specimen obtained as described above, the angle at which the movement started was determined by the same operation as in Comparative Experiment 3. Comparative Experiment 6 A specimen obtained using the same procedure as Comparative Experiment 3 was
The coating film was subjected to an abrasion resistance test. The test was conducted according to the method of ASTM-D-968, and the amount of quicksand until the paint film was damaged and the material surface appeared was expressed as: The results obtained are shown in Table-5.

[Table] It is clear from the comparative experiment results Tables 3 to 5 that the coating layer obtained from the coating composition of the present invention was
The effect of imparting adhesion to galvanized surfaces is very excellent. Therefore, the corrosion-proofing effect and long-term adhesion of the coating film are excellent, making it possible to protect the galvanized surface for a long period of time. In addition, it has excellent wear resistance and various anti-slip effects, making it extremely effective in ensuring safety when going up and down steel towers for maintenance and inspection.

Claims (1)

[Scope of Claims] 1 (a) A resin composition consisting of 99 to 60% by weight of an epoxy resin containing at least two or more epoxy groups at the end and 1 to 40% by weight of a polyvinyl butyral resin...100 parts by weight, (b ) At least one compound selected from oxyacid salts and metal oxides
... 1 to 250 parts by weight, and (c) aggregate ... 10 to 500 parts by weight. A coating composition for power transmission towers. 2. At least one compound selected from the oxyacid salts and metal oxides has a phosphate as an essential component, and at least one compound selected from the oxyacid salts and metal oxides other than the phosphates. The coating composition for power transmission towers according to claim 1, which is a mixture comprising the above components.