JPH0567720B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to electrolytic cleaning compositions, and sometimes to cleaning compositions for electrolytically cleaning cold worked steel materials at high current densities. [Prior art] During cold working in the steel manufacturing process, for example, when cold rolling is performed to produce cold rolled steel, cold rolling oil is used to cool and lubricate the steel material by using cold rolling oil to remove the heat generated during working. It is often passed through rolling oil.
In this case, it is natural that highly lubricating rolling oil, which is contaminated with dust and iron powder and whose main ingredients are animal fat or mineral oil, remains on the surface of the cold-worked steel material. If these oil stains are not completely removed by electrolytic cleaning before annealing the steel material, the high temperature during annealing will cause these oil stains to thermally decompose and turn into carbon and carbide, causing damage to plating, painting, etc. This will adversely affect surface treatment in subsequent processing. Traditionally, alkalis have the property of saponifying fats such as grease and oil and turning them into water-soluble soaps, so they can decompose esters and other fatty organic substances, and have been widely used for metal cleaning. In particular, the sodium hydroxide or calcium contained therein has high electrical conductivity and saponifiable properties, so they are obtained as essential components for electrolytic cleaning compositions. Secondly, although there is a theory that silicates have a negative effect on plating processing, they are effective emulsifiers and deflocculants for fats, and they are also effective buffers under strong basic conditions. Because of its excellent action, it is added as one of the main components of electrolytic cleaning compositions. According to literature, it is known that sodium orthosilicate is the most widely used for cleaning steel materials. Furthermore, it is well known that in order to efficiently remove oil stains from the surface of steel materials, a surfactant is added to lower the surface and interfacial tension. However, the selection of surfactant has a negative impact on the effectiveness of electrolytic cleaning.
It has a big impact. Mixed nonionic surfactants with anionic surfactants are often used for immersion cleaning and spray cleaning, but mixed nonionic surfactants cannot be used for electrolytic cleaning. unknown until now. On the other hand, high current density generates a large amount of hydrogen gas and oxygen gas, which causes the cleaning solution containing a surfactant to become foamy, reducing the conductivity of the cleaning solution or electrolytic cleaning. Since there is a possibility of reducing efficiency, the selection of the type and composition of surfactants can be considered to be the pillar of electrolytic cleaning technology. Furthermore, in order to soften clean water,
Chelating agents are sometimes added to conventional electrolytic cleaning compositions to tightly confine metal ions.
Commonly used chelating agents include sodium gluconate, trisodium nitrotriacetate, and EDTA. This is because these are said to be able to particularly improve the effectiveness of electrolytic cleaning. Finally, although hexamethylenetetramine has traditionally been used as an inhibitor in pickling with hydrochloric acid or sulfuric acid as the main ingredients, it has not been known until now to use hexamethylenetetramine as a component of electrolytic cleaners. [Problems to be Solved by the Invention] As described above, electrolytically cleaning cold-worked steel materials at high current density is certainly a unique technology, and the present invention has developed a novel idea while referring to the above-mentioned prior art. It was finally completed after repeated experiments. That is, an object of the present invention is to provide a cleaning composition that is effective for electrolytic cleaning of cold-worked steel materials. Another object of the present invention is to provide an electrolytic cleaning composition that exhibits an electrolytic cleaning effect at high current density without adding much antifoaming agent or the like. Furthermore, the present invention also aims to reduce the problem of mutual adhesion and scratching of stacked steel sheets or wound coils. Furthermore, another object of the present invention is to provide a cleaning composition that can suppress the generation of overvoltage so as not to waste electricity in electrolytic cleaning. [Means for Solving the Problems] In order to achieve the above object, the electrolytic cleaning composition of the present invention contains at least one hydroxide selected from the group consisting of sodium hydroxide and calcium hydroxide. , a silicate, and a nonionic surfactant, the nonionic surfactant being composed of a lauryl polyethylene glycol ether containing a large portion containing an average of 10 moles of ethylene oxide and a small portion containing an average of 1 mole of ethylene oxide. and nonylphenyl polyethylene glycol ether. The silicate is preferably an orthosilicate selected from sodium orthosilicate and calcium orthosilicate. In particular, the following formulations may be mentioned as the composition of the present invention. That is, hydroxide 20-60% by weight, orthosilicate 20-60% by weight, nonionic surfactant 0.1-20% by weight. Further, according to the present invention, in the above composition, 1-20
It is desirable to add % by weight of hexamethylenetetramine. Furthermore, according to the invention, it is desirable to also add 1-20% by weight of a chelating agent into the composition. As the chelating agent, sodium gluconate, trisodium nitrilotriacetate or a combination thereof can be used. [Function] The present invention not only effectively removes oil stains by using the above-mentioned nonionic surfactant and its characteristic blending ratio, but also significantly suppresses foaming of the cleaning liquid, reducing the need for adding antifoaming agents. can do. The addition of sodium orthosilicate and calcium orthosilicate can not only improve the service life of the electrolytic cleaning solution by exerting emulsification and deagglomeration buffering effects, but also prevent adhesion to other steel materials on the surface of electrolytically cleaned steel materials. A thin silicon dioxide film can be formed on the surface of the protective film and the steel material to prevent them from scratching each other. Moreover, by adding the above-mentioned hexamethylenetetramine, the generation of overvoltage can be suppressed. In addition, by adding the above-mentioned chelating agent, it is possible to shield calcium, magnesium, and heavy metal ions from coming into contact with orthosilicate and stearate formed by saponification. It is possible to suppress the formation of floating scum and grime that have a large adverse effect on the electrolytic cleaning solution and the electrical conductivity of steel materials. [Examples] Examples of the present invention will be described below. 150 kilograms of sodium hydroxide, 200 kilograms of sodium orthosilicate, 100 kilograms of sodium gluconate, 100 kilograms of trisodium nitrilotriacetate, and 100 kilograms of a compound with the molecular formula C ₁₂ H ₂₅ -O-(CH ₂ CH ₂ O) ₁₀ −H
Lauryl polyethylene glycol ether, represented by , and 10 kilograms have a molecular formula of C ₉ H ₁₉ −
nonylphenyl polyethylene glycol ether represented by C ₆ H ₄ -O-(CH ₂ CH ₂ O)-H, and 10
kilograms of hexamethylenetetramine to form a base composition. This basic composition was poured into a circulating water tank and 21,663 kg of water was added to make a 3% by weight basic cleaning solution. This basic cleaning solution was used to clean the cold rolled coil material during production at the brush scrubbing stage, and then poured into a high current density clean water tank to prepare an electrolytic cleaning solution. In the electrolytic cleaning stage, the cold rolled coil material to be cleaned was used as a cathode, and another steel material was used as an inert anode. During electrolytic cleaning, a large amount of gas is generated from the surface of the cold-rolled coil material of the cathode, which not only blows away floating particles and water scale but also prevents their adhesion, and also stirs the cleaning solution to keep it fresh. It was also possible to contact it with a cleaning solution. Furthermore, after a predetermined period of time, no deposits were deposited on the surface of the steel material used as the anode, unlike in conventional electrolytic cleaning methods. This is believed to be the effect of hexamethylenetetramine. This effect effectively suppressed the occurrence of overvoltage. The effect of adding hexamethylenetetramine will be described in detail later. Moreover, the above lauryl polyethylene glycol ether C ₁₂ H ₂₅ −O−(CH ₂ CH ₂ O) ₁₀ − as a surfactant.
The combination of H with nonylphenyl polyethylene glycol ether also deserves attention. It has been found that such surfactants and proportions not only have a high degree of cleaning power, but also significantly reduce foaming, allowing the dosage of antifoam agent to be reduced during practice. The effect of blending this surfactant will be explained in more detail later. The used cleaning solution is collected in a circulating water tank, and when it is to be used again, the consumed amount must be fully replenished in advance. Next, the electrolytically cleaned cold rolled coil material was washed twice in a hot water bath and then dried. When we evaluated the cleanliness of the dried coil material by measuring the percentage of its surface that could be wetted by water in a water drainage test, we were able to confirm that the cleanliness was better than required. According to field experiments, when electrolytically cleaning 1 ton of cold-rolled coil material, it is sufficient to add 0.367 kg of the base composition and 0.018 kg of antifoaming agent. In addition, the tendency of overvoltage to occur on the anode is very slow, so the operating time can be extended to 172 hours, which not only makes the work more convenient, but also saves a lot of power consumption. . Furthermore, the silicon dioxide film covering the surface of the cold-rolled coil material can also avoid sticking and scratching problems in the coil material. To confirm the properties of the above-mentioned nonionic surfactant obtained by combining lauryl polyethylene glycol ether, which contains mostly 10 moles of ethylene oxide on average, and noniphenyl polyethylene glycol ether, which contains a small portion of 1 mole of ethylene oxide on average. For this purpose, two types of electrolytic compositions, CTY410 and CTY412, were prepared. CTY412 was formulated like the base composition above, except without the addition of hexamethylenetetramine. This CTY41
A considerable amount of water was added to No. 2 to prepare a 3% by weight electrolytic cleaning solution. CTY410 is the above CTY412
However, nonylphenyl polyethylene glycol ether was not added.
CTY410 was also prepared in a 3% by weight electrolytic cleaning solution. That is, adding 0.01% by weight of nonylphenyl polyethylene glycol ether to a CTY410 cleaning solution results in a CTY412 cleaning solution. Next, CTY4 according to the method of ASTMD1173
The foaming properties of cleaning solutions of No. 12 and CTY410 were tested. Shown in the subtable are the respective lather heights.

Table 1 As shown in Table 1, the cleaning solution of CTY412 contains a small amount of nonylphenyl polyethylene glycol ether, so the foaming height is lower, ie, the tendency to foam is weaker. Then, the effect of hexamethylenetetramine on suppressing the generation of overvoltage to the anode is shown in Table 2 below.
is shown. As shown in Table 2, in order to simulate the electrolytic cleaning solution used for 3 days in the above electrolytic cleaning work,
A conditioning solution was prepared by adding ferrite ions at a concentration of 70 ppm. Nine types of samples were prepared based on this control solution and tested for overvoltage generation and anodic deposit precipitation.

[Table] Table 2 shows that hexamethylenetetramine can suppress the deposition of deposits on the anode that cause overvoltage. Other pickling inhibitors, e.g. Table 2
2-butyne-1,4-diol, 2-mercaptobenzothiazole, and cyclohexylamine, shown in , have also been tested, but their effectiveness is not as good as that of examethylenetetramine. The mechanism by which hexamethylenetetramine suppresses the precipitation of deposits is not yet fully understood, but it is thought to be due to its high molecular weight and electron donor properties on the surface of steel. Another reason may be that hexamethylenetetramine is not easily oxidized. [Effects of the Invention] As described above, by using the electrolytic cleaning composition of the present invention, cold-worked steel materials can be effectively cleaned at high current density, and the addition of antifoaming agents can be reduced. . In addition, it is possible to reduce the occurrence of adhesion and scratches between steel materials, and the power consumption can be used effectively.

Claims (1)

[Claims] 1. 20 to 60% by weight of at least one hydroxide selected from the group consisting of sodium hydroxide and calcium hydroxide, 20 to 60% by weight of a silicate, and a nonionic surfactant. 0.1 to 20% by weight of the nonionic surfactant, the majority of which is lauryl polyethylene glycol ether containing an average of 10 moles of ethylene oxide, and a minor portion of nonylphenyl polyethylene glycol containing an average of 1 mole of ethylene oxide. An electrolytic cleaning composition for cold-worked steel, characterized by comprising ether. 2. The electrolytic cleaning composition according to claim 1, wherein the silicate is an orthosilicate selected from the group consisting of sodium orthosilicate and calcium orthosilicate. 3 The weight ratio of the lauryl polyethylene glycol ether containing an average of 10 moles of ethylene oxide and the nonylphenyl polyethylene glycol ether containing an average of 1 mole of ethylene oxide is 9 to 10:1.
The electrolytic cleaning composition according to claim 1. 4 20 to 60% by weight of at least one hydroxide selected from the group consisting of sodium hydroxide and calcium hydroxide, 20 to 60% by weight of a silicate, and 0.1 to 20% by weight of a nonionic surfactant. The nonionic surfactant contains a large portion of lauryl polyethylene glycol ether containing an average of 10 moles of ethylene oxide and a small portion of an average of 1 mole of ethylene oxide.
An electrolytic cleaning composition for cold-worked steel, characterized in that it is made of nonylphenyl polyethylene glycol ether containing mol of ethylene oxide, and further contains hexamethylenetetramine. 5. The electrolytic cleaning composition according to claim 4, wherein the silicate is an orthosilicate selected from the group consisting of sodium orthosilicate and calcium orthosilicate. 6 The weight ratio of lauryl polyethylene glycol ether containing an average of 10 moles of ethylene oxide and nonylphenyl polyethylene glycol ether containing an average of 1 mole of ethylene oxide is 9 to 10:1.
The electrolytic cleaning composition according to claim 4 or 5. 7. The electrolytic cleaning composition according to any one of claims 4 to 6, wherein the composition ratio of the hexamethylenetetramine is 1 to 20% by weight. 8 20 to 60% by weight of at least one hydroxide selected from the group consisting of sodium hydroxide and calcium hydroxide, 20 to 60% by weight of a silicate, and 0.1 to 20% by weight of a nonionic surfactant. The nonionic surfactant contains a large portion of lauryl polyethylene glycol ether containing an average of 10 moles of ethylene oxide and a small portion of an average of 1 mole of ethylene oxide.
1. An electrolytic cleaning composition for cold-worked steel, characterized in that it is made of nonylphenyl polyethylene glycol ether containing moles of ethylene oxide, and further contains hexamethylenetetramine and a chelating agent. 9. Claim 8, wherein the weight ratio of lauryl polyethylene glycol ether containing an average of 10 moles of ethylene oxide to nonylphenyl polyethylene glycol ether containing an average of 1 mole of ethylene oxide is 9 to 10:1. Electrolytic cleaning composition. 10. The electrolytic cleaning composition according to claim 8 or 9, wherein the composition ratio of the hexamethylenetetramine is 1 to 20% by weight. 11 The composition ratio of the chelating agent is 1 to 10
Claims 8 to 10 which are weight %
The electrolytic cleaning composition according to any one of Items 1 to 9. 12. The electrolytic cleaning composition of claim 11, wherein the chelating agent is selected from the group consisting of sodium gluconate, sodium nitrilotriacetate, and blends thereof.