JPH0312591B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention does not contain carcinogenic substances and does not cause discoloration or
This invention relates to a coating composition for iron pipes for obtaining a coating film that does not easily cause cracks and the like. <Conventional technology> Tar epoxy resin paints, which are inexpensive and have excellent rust prevention, water resistance, and chemical resistance, have been widely used in this type of technical field as paints for iron pipes such as water pipes and gas pipes. It was used. <Problems to be Solved by the Invention> However, tar, that is, coal tar pitch, contains a polyhex component, which contains carcinogenic substances. There was a desire to develop a paint to replace paint. However, since there was no alternative paint that was inexpensive and had excellent film performance, we had no choice but to use tar epoxy resin paint, even though we were aware of the drawbacks mentioned above. was the actual situation. In addition, tar epoxy resin paints often turn brown or crack when exposed to strong ultraviolet rays during the drying process of the paint film within one week in the summer. It was necessary to apply an alkyd resin paint or the like again. In view of the current situation, the inventors of the present invention have conducted intensive research to find a product that does not contain carcinogenic substances, is inexpensive, is resistant to discoloration, cracks, etc., and has excellent rust prevention, water resistance, chemical resistance, etc. They discovered a coating composition for iron pipes that can provide a coating film equivalent to that of tar-epoxy resin coatings, and completed the present invention. <Means for Solving the Problems> That is, the present invention comprises: (i) 100 parts by weight of an epoxy resin having an epoxy equivalent of 150 to 1000 and an epoxy curing agent having at least two or more epoxy groups in one molecule; (ii) Gilsonite 50-200 parts by weight (iii) Petroleum resin with a number average molecular weight of 2000 or less
Contains a coating film-forming component consisting of 20 to 180 parts by weight and (iv) 10 to 70 parts by weight of xylene resin, and further contains mineral fillers such as extender pigments, antirust pigments, and coloring pigments, various additives, etc. The present invention also relates to a coating composition for iron pipes which is dissolved in a suitable organic solvent. In the present invention, the epoxy resin includes:
Epoxy resins conventionally used in tar epoxy resin paints can be used. Moreover, the epoxy equivalent is preferably about 150 to 1000. If the epoxy equivalent is less than about 150, the paint film will remain sticky and have poor drying properties, and if it exceeds about 1000, it will be difficult to dissolve in solvents, and it will be necessary to use a large amount of solvent, resulting in a low paint solid content. Become. In other words, commercially available products include Epicote 828,
834, 836, 1001, DX-255 (trade names manufactured by Ciel Chemical), Araldite GY-260 (trade names manufactured by Ciba Geigy), DER330, 331, 337 (trade names manufactured by Dow Chemical) ), Epicron 800
Bisphenol type epoxy resins such as DEN431 and DEN438 (product names manufactured by Dow Chemical Company); Araldite CT-508 (product names manufactured by Ciba Geigy); Typical examples include polyglycol type epoxy resins such as Epiklon 200 and Epiclon 400 (all trade names manufactured by Dainippon Ink and Chemicals). As the epoxy curing agent, compounds commonly used as curing agents for epoxy resins can be used. Examples include aliphatic polyamines, modified aliphatic polyamines, polyamide amines, aromatic polyamines, and modified aromatic polyamines. The mixing ratio of epoxy resin and epoxy curing agent is arbitrarily determined depending on the type of both, but usually (active hydrogen equivalent of curing agent / epoxy equivalent of epoxy resin)
When the value of is in the range of 0.5 to 1.0, the original performance of the epoxy resin can be exhibited. Next, "Gilsonite" used in the present invention has a high softening point produced from natural ore veins.
It is a dark brown hydrocarbon compound with low sulfur and ash content. Typical composition is carbon as the main component
75-86%, hydrogen content 8-15%, nitrogen content 1.5-5%,
It contains 1 to 2% oxygen and 4% or less ash, and its properties include an average molecular weight of about 1300 to 1800, a hardness (moh's scale) of about 2, a penetration rate (25°C) of about 2, and a specific gravity of 1.03 to 1.03. 1.06, softening degree 130-190℃. In the present invention, gilsonite is mainly used to improve rust prevention. In addition, because of its high softening point and hardness, it does not have the same stickiness as petroleum-based asphalt, and it also contains almost no carcinogenic substances. The mixing ratio of Gilsonite is 100% of the epoxy resin and 100% of the epoxy curing agent.
A suitable amount is 50 to 200 parts by weight. In addition,
If the proportion of Gilsonite exceeds the above range, the paint tends to thicken, requiring the use of a large amount of organic solvent, which lowers the solid content of the paint and makes the paint film brittle. Therefore, it is undesirable. On the other hand, if the blending ratio is less than the above range, drying properties will deteriorate, which is not preferable. Next, the petroleum resin used in the present invention is an aliphatic petroleum resin in which a conjugated diene of _C5 fraction such as cyclopentadiene and 1,3-pentadiene is partially cyclopolymerized; a heavy oil by-product of petroleum naphtha cracking. Aromatic petroleum resin made by polymerizing C ₉ fractions such as styrene derivatives and indene; Copolymer petroleum resin made by copolymerizing the C ₅ fraction and C ₉ fraction; Aromatic petroleum resin made from hydrogen It is a low molecular weight polymer with a number average molecular weight of about 500 to 2000, such as an alicyclic petroleum resin obtained by polymerizing the added resin or dicyclopentadiene. In addition,
If the molecular weight is higher than the above upper limit, the flexibility etc. of the coating film will decrease, which is not preferable. In the present invention, by blending an appropriate amount of petroleum resin into the paint, the poor compatibility between gilsonite and epoxy resin can be overcome, and as a result, it becomes possible to form a paint. Furthermore, when a large amount of gilsonite is used in a paint, the viscosity tends to increase, but by blending the petroleum resin, the viscosity of the paint can be appropriately lowered and the drying properties of the paint film can be improved. The appropriate blending ratio of the petroleum resin is 20 to 180 parts by weight based on 100 parts by weight of the epoxy resin and epoxy curing agent. If the proportion of the petroleum resin exceeds the above range, there will be a drawback that the coating film will have poor flexibility and become brittle. On the other hand, if the blending ratio is less than the above range, the above-mentioned effects cannot be obtained, which is also not preferable. Next, the xylene resin used in the present invention is mainly a reaction product of meta-xylene and formaldehyde, and has an average molecular weight of about 300 to 600, a reactive group equivalent of about 180 to 300, an oxygen content of 8 to 15% by weight, A viscosity (50°C) of 80 to 600 cps is suitable. When this is used, compatibility with gilsonite, epoxy resins, and petroleum resins is improved. In the present invention, the xylene resin improves the flexibility of the coating film, improves impact resistance and flexibility, and in addition, the terminal methylol group of the xylene resin has high reactivity with the epoxy curing agent. It also has the effect of increasing coating film hardness. The mixing ratio of the xylene resin is approximately 10 to 70 parts by weight per 100 parts by weight of the epoxy resin and epoxy curing agent.
Parts by weight are appropriate. It should be noted that if the blending ratio of the xylene resin is too much than the above range, the drying properties of the coating film will be poor and tackiness will remain, which is not preferable. On the other hand, if the blending ratio is less than the above range, the coating film tends to lose its flexibility and become brittle, which is also not preferred. The coating composition of the present invention contains the above-mentioned coating film-forming components as essential components. Other coating film-forming components include rust-preventive pigments such as zinc phosphate and aluminum phosphate to increase coating hardness and anti-corrosion properties; extender pigments such as talc and calcium carbonate; coloring pigments such as carbon black, etc. It is desirable to blend 30 to 50% by weight of the pigment in the solid content of the paint.
It is also desirable to incorporate a small amount of additives such as anti-sagging agents and leveling agents. The coating composition of the present invention further contains an appropriate amount of an organic solvent such as toluene, xylene, methyl ethyl ketone, butanol, etc. to the above coating film forming components, and preferably has a coating viscosity of #4 and a coating viscosity of 20.
~60 seconds. The coating composition of the present invention is a two-component coating, and contains the above-mentioned epoxy resin and xylene resin in the main component, and an epoxy curing agent in the curing agent component. The component may be blended into either the main agent or the curing component. However, it is mainly blended into the main ingredient. In the present invention, the coating material can be produced by any known method such as kneading in a roll mill, pebble mill, ball mill, etc., but it is particularly preferable to use a closed ball mill because it can prevent volatilization of the solvent. Incidentally, the method of painting the iron pipe can be carried out in substantially the same manner as the conventional tar epoxy resin paint. That is, after surface treatment, a dry film thickness of 80 μm is applied using airless spray, air spray, brush, etc.
The above coating is preferably applied to a thickness of about 100 to 200μ, and then allowed to air dry. In addition, depending on the case, the iron water pipe may be preheated to 60 to 90°C, or may be force-dried after painting. <Effects of the Invention> The coating composition for iron pipes of the present invention has rust prevention, water resistance, and chemical resistance comparable to tar epoxy resin coatings that have been widely used in the past, and is superior to tar epoxy resin coatings. There are no drawbacks such as the poor working environment during painting, no elution of carcinogenic substances from the paint film, and no discoloration or cracking of the paint film in the summer. Therefore, the coating composition for iron pipes of the present invention does not need to be repainted (repaired) before shipping.
Furthermore, even in winter, the handling time is 8.
It takes less than an hour and has great practical value. The present invention will be explained in more detail below using Examples. In the examples, "parts" and "%" are expressed on a weight basis. Example 1 Bisphenol type epoxy resin [“Epicote #1001” (trade name manufactured by Ciel Chemical Co., Ltd.); Epoxy equivalent
475, NV100%] 77 parts, Gilsonite 110 parts, aliphatic petroleum resin ["Escolets 3102" (trade name manufactured by Etsuo Chemical Co., Ltd.); average molecular weight approximately 550, NV100%]
94.3 parts, xylene resin ["Nicanol LLL" (trade name manufactured by Mitsubishi Gas Chemical Co., Ltd.); average molecular weight 340, reactive group equivalent weight 275, NV 100%] 25 parts, talc 330 parts, anti-sagging agent 14 parts, xylene 249 parts, 45 parts of toluol,
40 parts of methyl ethyl ketone was kneaded in a pot mill to prepare a main ingredient. In addition, polyamide resin solution (active hydrogen equivalent 450,
A curing agent component was prepared by mixing 600 parts of NV65%), 100 parts of isobutanol, and 300 parts of triol in a disper. 90 parts of the base component thus obtained and 10 parts of the curing agent component were mixed to prepare a paint. Degreased and polished mild steel plate (70 x 150 x 0.8
mm) to a dry film thickness of 200μ,
It was dried at 20°C for one week. Thickening properties and stability of the resulting cure; semi-curing properties of the coating film, bending resistance, impact resistance, adhesion, discoloration, water resistance, salt spray resistance, soda resistance, sulfuric acid resistance,
Various crack resistance tests were carried out and the results were as shown in Table 1. Example 2 Bisphenol type epoxy resin [“DER661” (trade name manufactured by Dow Chemical Company); epoxy equivalent 475,
NV100%] 113 parts, Gilsonite 100 parts, aliphatic petroleum resin ["Quinton 1525L" (trade name manufactured by Zeon Corporation); average molecular weight 1500, NV100%] 89 parts,
25 parts of xylene resin "Nikanor LLL", talc
183 parts, calcium carbonate 90 parts, carbon black 7 parts, aluminum phosphate pigment 30 parts, anti-sagging agent
30 parts of anti-scalding agent, 14 parts of xylene, 250 parts of xylene, 50 parts of toluene, and 20 parts of methyl ethyl ketone were kneaded in a pot mill to prepare a main component. Also, amine adduct solution (active hydrogen equivalent: 336, NV55%)
A curing agent component was prepared by mixing 647 parts of isobutanol, 100 parts of isobutanol, and 253 parts of toluene in a disper. 90 parts of the base component thus obtained and 10 parts of the curing agent component were mixed to prepare a paint. Thereafter, in the same manner as in Example 1, it was applied to a polished mild steel plate, dried, and various tests were conducted. Example 3 Bisphenol type epoxy resin [“Epicote #828” (trade name manufactured by Ciel Chemical Co., Ltd.); Epoxy equivalent
190, NV100%] 40 parts, bisphenol type epoxy resin "Epicote #1001" 40 parts, Gilsonite
130 parts, aliphatic petroleum resin "Quinton 1525L"
110 parts, 25 parts of xylene resin "Nikanor LLL",
A base ingredient was prepared by mixing 271 parts of xylol in a disper. Also, amine duct solution (active hydrogen equivalent 221,
A tar curing agent component was prepared by mixing 520 parts of NV70%) and 160 parts of xylene in a disper. 90 parts of the base component thus obtained and 10 parts of the curing agent component were mixed to prepare a paint. Thereafter, in the same manner as in Example 1, it was applied to a polished mild steel plate, dried, and various tests were conducted. Comparative Example 1 A paint was prepared in the same manner as in Example 1 except that the xylene resin was omitted, and it was applied to a polished mild steel plate, dried, and various tests were conducted. Comparative Example 2 A paint was prepared in the same manner as in Example 1 except that the petroleum resin was omitted and the amount of gilsonite was increased by the same amount, and the paint was applied to a polished mild steel plate, dried, and various tests were conducted. Comparative Example 3 The same base ingredients as in Example 1 were used except that 230 parts of gilsonite and 400 parts of xylene were used as the base ingredients, and 114 parts of the base ingredient and a curing agent component were used.
A paint was prepared by mixing 10 parts. The coating was applied to a polished mild steel plate in the same manner, dried, and various tests were conducted. Comparative Example 4 In Example 2, petroleum resin was used as the main component.
270 parts and xylene at 278 parts, the same base ingredients were used, 115 parts of the base ingredient and 10 parts of the curing agent.
A paint was prepared by mixing the two parts. Thereafter, various tests were conducted by applying the coating to a polished mild steel plate and drying it in the same manner. Comparative Example 5 A paint was prepared by using the same base ingredients as in Example 2 except that 110 parts of the xylene resin was used as the base ingredient, and by mixing 98 parts of the base ingredient and 10 parts of the curing agent component. Thereafter, various tests were conducted by applying the coating to a polished mild steel plate and drying it in the same manner. Comparative Example 6 260 parts of coal tar pitch, 75 parts of bisphenol type epoxy resin "Epicote #1001", talc
250 parts, calcium carbonate 100 parts, anti-sagging agent 18 parts,
The main ingredient consists of 110 parts of toluene, 90 parts of methyl ethyl ketone, 140 parts of amine adduct solution (active hydrogen equivalent: 336, NV 55%), 100 parts of isobutanol,
A curing agent component consisting of 760 parts of toluol (100;
10) to prepare a conventional tar epoxy resin paint. Thereafter, it was applied to a polished mild steel plate and dried in the same manner as in Example 1, and various tests were conducted.

【table】

[Table] As is clear from Table 1, the coating composition of the present invention had excellent coating film performance and passed the test for use on iron pipes. On the other hand, in Comparative Example 1, which did not contain xylene resin, the coating film lacked flexibility and had poor bending resistance and impact resistance. On the contrary, in Comparative Example 5 in which the xylene resin was contained in excess, the coating film remained weldable. Furthermore, in Comparative Example 2, which did not contain petroleum resin, the stability of the coating material was poor and the coating film performance was also poor. On the other hand, in Comparative Example 4 in which the petroleum resin was excessive, the coating film lacked flexibility and had poor bending resistance and impact resistance. In addition, in Comparative Example 3 with excess gilsonite, the paint thickened and the coating workability was poor. Furthermore, conventional tar epoxy resin paints not only contain carcinogenic substances, but also caused discoloration and cracks in the paint film during exposure tests in the summer.

Claims (1)

[Scope of Claims] 1 (i) 100 parts by weight of an epoxy resin and epoxy curing agent having an epoxy equivalent of 150 to 1000 and having at least two or more epoxy groups in one molecule (ii) 50 to 200 parts by weight of gilsonite (iii) ) Petroleum resin with a number average molecular weight of 2000 or less
20 to 180 parts by weight (iv) A coating composition for iron pipes, comprising a coating film-forming component consisting of 10 to 70 parts by weight of xylene resin.