JPH041799B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a lubricant for metal drawing, which has particularly good stability during storage and use, and has excellent lubrication performance, and can be easily removed after processing. This relates to the same lubricant that can be used as a lubricant. [Prior Art] When performing cold working (rolling, extrusion, drawing, etc.) on metal pipes such as steel pipes, various methods are used to improve the quality of processed products and suppress tool wear (prevention of seizure). Lubricants are used. However, known lubricants cannot be said to satisfy all required properties such as lubrication performance, ease of removal after processing, and low pollution of waste fluid. For example, in relatively light processing, plastic processing oils such as metal soap, mineral oil, animal/vegetable oil, esters, extreme pressure oil, or mixtures thereof are used; Even if machining oil is used, the metal contact area between the pipe to be machined and the tool increases, resulting in significant damage to the tool and the product. Other lubrication methods that are becoming commonly used include:
A chemical conversion film is formed on the surface of the metal pipe material in advance,
It is also known to improve the lubricating performance by using chemical metal soap coating agents. Such chemical conversion coatings include phosphate coating (applied to ordinary steel, low alloy steel, etc.),
Aluminum fluoride coatings (applicable to Al or Al-based alloys) and oxalate coatings (applicable to stainless steel, etc.) are known, and with this method, there is no chemical formation between the pipe to be processed and the chemical metal soap coating. Since the coating is interposed and these are chemically integrated, the lubricating coating exhibits extremely strong adhesion and exhibits sufficient lubrication function even when the processing rate is increased. [Problems to be Solved by the Invention] However, this chemical conversion film lubrication method has the following problems. (a) For example, when using oxalate, ferrous oxalate is formed on the surface layer of the workpiece due to a chemical reaction, and in order to remove this, not only degreasing but also pickling is essential. (b) The lubrication treatment is complicated and the stability of the treatment effect is also somewhat low. Furthermore, long-term control is difficult, often resulting in unstable quality. (c) Because a large amount of waste liquid is generated during chemical conversion treatment and pickling treatment,
These purification treatments require a great deal of equipment and labor. (d) With highly corrosion-resistant materials, chemical conversion treatment itself is difficult and a uniform chemical conversion film cannot be formed, making it impossible to perform high-precision processing. To address these drawbacks of chemical conversion film lubrication, there are methods to physically attach the lubricant, but for example, at 30°C,
When using a high viscosity oil of 10,000 to 100,000 cst, other problems arise such as poor workability and difficulty in removing it after processing. Furthermore, in the above method, since the lubrication performance improves in proportion to the increase in viscosity, workability and processing performance exhibit a mutually contradictory relationship, and it cannot be said that it is substantially superior to the above-mentioned chemical conversion film lubrication method. As a method to improve this, a lubricant in which a highly viscous lubricating resin component is dissolved in a low boiling point organic solvent has been proposed, but since the solvent evaporates during use, it is difficult to control the concentration. In addition, because the solvent evaporates quickly, drying progresses too much during the draining process, leading to uneven film thickness, and this uneven deposit is pushed between the die and the workpiece, causing the uneven film thickness. There is a serious drawback that it is further encouraged. In addition, the use of most organic solvents is regulated by law from the viewpoint of toxicity and fire danger, and there are health problems in that they cannot be used unless special equipment and measures are taken. In other words, chemical film lubrication methods are difficult to apply to materials with strong corrosion resistance, and pollution countermeasures are required, and oil-based simple lubricants cannot withstand advanced processing of stainless steel, titanium, zirconium, etc. Increasing the viscosity impairs workability and degreasing properties, while solvent-based solvents have their own disadvantages, such as health problems and the tendency to cause defects such as non-uniform film thickness. The present inventors focused on the above circumstances, and developed a lubricant that is a one-component lubrication system that departs from the conventional system, has good lubricity, and is easy to remove after processing, and has previously filed a patent application for this lubricant. Gansho 59-196193). However, some problems remain in this technique as well. In other words, the uneven thickness of the lubricating film obtained through the dip coating and drying steps cannot be eliminated unless operations such as rotation are applied during drying. It is likely to be locally pushed into the surface and cause significant unevenness on the surface of the workpiece. Therefore, these methods are effective for products with large surface roughness and do not cause serious problems for general pipes, rods, shapes, etc., but they are not suitable for objects that require precision processing. . Therefore, the present inventors conducted research to further improve the above technology, and as a result, they developed a new lubricant that is particularly suitable for drawing processes and does not have the above drawbacks, and completed the present invention. . [Means for Solving the Problems] The lubricant for drawing metal tubes according to the present invention is a butyl acrylate ester having a resin acid value of 10 to 40 and a glass transition temperature of -10 to 20°C. −
It consists of an emulsion containing a methacrylic acid methyl ester copolymer and an aqueous dispersion of metal soap, or the resin has an acid value of 10 to 40 and a glass transition temperature of 5 to 30.
The gist is that it consists of an emulsion containing an acrylic acid butyl ester-methacrylic acid methyl ester copolymer at a temperature of 0.degree. C., an aqueous dispersion of butyl maleate and a metal soap. [Function] The present inventors set the above-mentioned chemical film lubrication method with lubrication performance as the target standard, and developed a method that has the same adhesion and slipperiness as this method and does not have the drawbacks pointed out earlier. In order to develop a lubricant for drawing processes, we investigated the lubrication performance of a large number of compounds. As a result, we felt that the butyl acrylate-methyl methacrylate copolymer could be a better lubricant than other resins. In other words, this copolymer has good affinity for metals, exhibits excellent adhesion, and has good slip properties.
After the treatment, it can be easily removed with an alkaline solution (for example, an aqueous solution of sodium orthosilicate). However, it has become clear that the above-mentioned copolymers do not always exhibit good performance no matter what they are. Therefore, from the viewpoint that it is necessary to characterize a copolymer that can reliably exhibit such performance, we conducted experiments to clarify the specifications of the copolymer suitable for the present invention, and found that the glass transition temperature was - It has been confirmed that those in the range of 10 to 20°C exhibit excellent performance (see Japanese Patent Application No. 1983-1961). However, copolymers with a glass transition temperature of less than -10°C have poor lubrication performance and tend to seize during cold working and damage the machined surface, whereas copolymers with a glass transition temperature of less than 20°C Although the lubrication performance itself is good, the lubricant film tends to cause intrusion.
The surface accuracy of the processed surface is reduced. Furthermore, the present inventors have determined that the relationship between the blending ratios of the copolymer emulsion and the fatty acid ester emulsion shown in Japanese Patent Application No. 59-196193 (see Figure 1) shows that the copolymer emulsion 50
% or less and 50% or more of fatty acid ester, tube seizure occurs but no indentation occurs at all, and they came up with the idea of using a metal soap with better lubricity in place of the fatty acid ester. Various stearates such as Ca, Al, Zn, Li, and Ba are known as metal soaps, but the types of metal soaps that can be applied to the present invention are not limited in any way;
Select one or more species and use as an aqueous dispersion. In addition, the acid value of the above-mentioned copolymer has a large effect on the lubrication performance and ease of removal after treatment, and the results of confirmation experiments have revealed that a value in the range of 10 to 40 should be used. . However, copolymers with an acid value of less than 10 lack hydrophilicity and are difficult to remove with alkaline water (e.g. sodium orthosilicate aqueous solution) after treatment, while copolymers with an acid value of more than 40 emulsify the resin. In addition to poor stability, the emulsion exhibits thixotropic properties and becomes gel-like, making it unsuitable as a lubricant. Next, we investigated the form of the above copolymer and found that an aqueous emulsion is optimal. In other words, if it is an aqueous emulsion, there is no danger of health problems or ignition caused by volatile vapors, unlike organic solvent types, and it can be easily removed by washing with alkaline water after treatment. can be mixed as appropriate. In emulsification, the stability of the emulsion can be further enhanced by using a small amount of lower alcohol (such as isopropyl alcohol) together with water.
The concentration of the copolymer in the emulsion is not particularly limited, but considering handleability, lubrication performance, etc., the most preferable concentration is about 20 to 60% by weight (more preferably 30 to 60% by weight).
50% by weight). The object of the present invention is achieved by mixing the above copolymer emulsion with an aqueous dispersion of various metal soaps and using the mixture as a lubricant. If an appropriate amount of butyl ester is used in combination, the adhesion of the lubricant to metal pipes, etc. can be improved, and a lubricant that does not easily peel off due to a light impact can be realized. [Examples] Example 1 Ca stearate is used as the metal soap. However, since it is difficult to mix in powder form, an aqueous dispersion with a concentration of 40% by weight was prepared. In addition, various copolymer emulsions with different glass transition temperatures (Tg) were prepared by varying the copolymerization ratio of butyl acrylate and methyl methacrylate. It is created by mixing with a dispersion liquid in various proportions, and the stability, adhesion,
The lubrication performance during drawing was investigated. The above copolymer was emulsified using water and isopropyl alcohol, and its nonvolatile content was 30%. However, the adhesion of SUS304 seamless pipe [22〓× ^2.2t × ^100l
(mm)] After dipping and applying lubricant, keep it horizontal at 100℃
Create a test piece (tube) by force drying with hot air at 3 m ² /min for 30 minutes, and apply a mild or strong impact.
Alternatively, adhesion was determined by scratching with a fingernail. In addition, the pull-out test was conducted on SUS304 seamless pipe [22〓×
2.2 ^t (mm)] using a floating plug, 17〓
This is a comparison of the condition of the plug when it was pulled out to a size of ×1.4 ^t (mm), the damage on the tube surface, and the condition of the plug. The results are shown in Table 1 (1) to (5), and when the aqueous dispersion of Ca stearate (metallic soap) is 70% or more and the copolymer emulsion is 30% or less,
Good results were obtained with no indentation and no burning. However, as a result of the glass transition temperature (Tg), the lower it is, the worse the lubricity becomes, and conversely, the higher it is, the worse the adhesion is. Therefore, the practical range of glass transition temperature (Tg) is about -10 to 20°C. However, in this example, there was a general tendency for the adhesion to be weak, and it would peel off even with a light impact, and this tendency was particularly noticeable at the retaining part at the bottom of the inner surface of the tube.
The problem remained. The evaluation criteria for stability, adhesion and pull-out tests are as follows. (Stability) ××...Creaming due to coalescence of emulsions ×...Rapid change in viscosity (increase) △...Caking of precipitate ○...Mild precipitation (redispersion possible) ◎...No change ( Adhesion) ××...The entire surface peels off with a mild impact or the retaining part falls off when left vertically ×...The entire retaining part peels off with a mild impact or the coating breaks due to hand rubbing △...The retaining part peels off with a strong impact The entire part peels off or the paint film breaks with a fingernail. ○... Part of the retaining part peels off due to strong impact. ◎... No retaining part peels off due to strong impact (plug condition) ××... Severe seizure ×... Slightly Seizing occurs △...Cloudy is visible ○...No abnormality (flaws on tube surface) ××...Serious seizure ×...Slightly seizing occurs △...Metallic luster due to lack of oil film ○... ...Metallic luster in some parts ◎...Uniform lubricant film is observed (indentation) ××...Large indentation due to lubricant film ×...Local strong indentation △...Light local indentation ○ ...There is slight indentation in some parts ◎...No indentation observed at all

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[Table] In Table 1 (1), lubricants No. 7 and 8 are representative lubricants related to the earlier application (Japanese Patent Application No. 1987-196193) and are also shown as comparative examples. A linear saturated fatty acid ester emulsion having the composition and a copolymer emulsion having a glass transition temperature (Tg) of 13°C are mixed in the following proportions. Straight-chain saturated fatty acid ester emulsion Number of carbons: 16 Melting point: 63°C (before esterification) Surfactant: Polyoxyalkyl ethylene ether, 4.5% by weight Fatty acid ester concentration: 9% by weight Lubricant No. 7 Tg13℃ copolymer emulsion...70% by weight Above fatty acid ester emulsion...30% by weight Lubricant No.8 Tg13℃ copolymer emulsion...60% by weight Above fatty acid ester emulsion...40% by weight % Example 2 As mentioned above, Example 1 had the problem of weak adhesion in general, and in order to improve this, a method other than manipulating the copolymerization ratio of butyl acrylate and methyl methacrylate was used. In order to improve the adhesion, we devised a method of mixing a plasticizer into the copolymer emulsion. Examples of plasticizers include dibutyl maleate, methyl maleate, and alcoholic solvents, but dibutyl maleate is the best in terms of flammability, toxicity, and odor. As in Example 1, copolymer emulsions with different glass transition temperatures (Tg) were mixed by volume (Tg, -10°C, 5°C, 13°C, 30°C, 37°C).
°C) was prepared, and a 40% by weight aqueous dispersion of dibutyl maleate and Ca stearate was blended in the proportions shown in Table 2 (1) to (5), and the stability and adhesion of the resulting lubricant were evaluated. Examined. The evaluation criteria for stability and adhesion are the same as in Example 1.

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[Table] As a result, we found that the copolymer emulsions with low glass transition temperatures (Tg - 10°C) shown in Table 2 (1) were blended with dibutyl maleate (lubricants No. 1 to 1).
4, 6-9, 11-14) were too soft and blocking was observed. This blocking becomes a problem when a plurality of raw tubes are tied together and dried. On the other hand, copolymer emulsions with a high glass transition temperature (Tg 5°C or higher) generally have good stability and adhesion, but if the glass transition temperature is too high (Tg 37°C or higher), the adhesion is poor. A tendency for deterioration was observed [see Table 2 (5)]. However, overall, it is judged that the adhesion is considerably improved, and there is no practical problem when the glass transition temperature (Tg) is in the range of 5 to 30°C. This is due to the action of maleic acid dibutyl ester as a plasticizer, which lowers the glass transition temperature (Tg) of the copolymer to approximately -10 to 20°C. It is thought that good adhesion will be exhibited even if the amount is relatively high. The amount of maleic acid dibutyl ester blended is 50 parts by weight per 100 parts by weight of the copolymer emulsion.
~20 parts by weight is good. Example 3 Next, the present inventors selected a compounding composition that was judged to have good adhesion in Example 2, and examined the lubrication performance by a pull-out test. The results are shown in Tables 3 (1) to (3). However, Table 3 (1) is replaced by Table 2 (2), and Table 3 (2) is replaced by Table 2 (3).
In addition, Table 3 (3) corresponds to Table 2 (4). For example, if lubricant No. 3 in Table 2 (2) is used, lubricant No. 2-(2) in Table 3 (1) is used.
-3. The same applies to Table 3 (2) and (3). The pull-out test method and its evaluation criteria are the same as in Example 1.

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[Table] As is clear from Table 3 (1) to (3), there was no indentation or baking in all cases, and the compound containing dibutyl maleate was more effective than in Example 1. was gotten. Example 4 Furthermore, the present inventors investigated the lubrication performance of metal soaps other than Ca stearate using a method similar to the above-mentioned pullout test. The compounding ratio is shown in Table 2 (3) for lubricant No.
8 was used as the standard. Lubricant No. 8 is a butyl acrylate/methyl methacrylate copolymer with a glass transition temperature (Tg) of 13°C, a total acid value (KOHmg/g) of 20, and a weight average molecular weight of 37,600, mixed with water and a small amount of isopropyl. It is a lubricant that is emulsified and dispersed in an alcohol mixed solvent and has a non-volatile concentration of 39% by weight. The evaluation criteria for the condition of the tube were the same as those in Example 1, and the evaluation criteria for film persistence (residual coating film) were as follows. (Survivability of film) △...Evenly thin remaining film ○...Uniform remaining film ◎...Film remains completely In addition, all of the prepared lubricants are stable even under strong impacts, do not peel off at all, and have no adhesive properties. It was good and warm.

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[Table] As a result, it was found that the use of metallic soap of Ca stearate was optimal. That is, Li stearate,
Since Ba has a high practical temperature, there is a large amount of film remaining after pulling out, but the maximum pullout load is high.On the contrary, Al stearate and Zn, which have a low softening temperature, have a low maximum pullout load but only a small amount of film remaining. Furthermore, since Zn stearate has a large specific gravity, a large amount of precipitation occurs. However, there is no practical problem with any of the metal soaps, and two or more types may be used in combination. Example 5 The present inventors investigated the relationship between the drying time after dip coating and the lubricity by drawing out as a means of evaluating the improvement of lubrication properties. The lubricants used were Lubricant No. 8 (conventional product) in Table 1 (1) and Lubricant No. 8 in Table 2 (3).
belongs to. However, for the pullout test, a floating plug of SUS304 seamless pipe [22〓×2.2 ^t (mm)] was used. Each side is pulled out in the following three types of extraction modes. (Pull-out mode) 17〓×2.0 ^t (mm) (section reduction rate 31.1%) 17〓×1.7 ^t (mm) (section reduction rate 40.3%) 17〓×1.4 ^t (mm) (section reduction rate 49.8%) The drying conditions are as follows. (Drying conditions) After dipping the metal pipe in lubricant, keep the pipe horizontal.
It was forced to dry with warm air at 100℃ and 3m ² /min. Note that when the drying time is 0 minutes, the sample was pulled out without drying. The results are shown in Table 5 (1) and (2). Table 5 (1) shows the case when lubricant No. 8 (conventional product) from Table 1 (1) is used, and Table 5 (2) shows the case when lubricant No. 8 (conventional product) from Table 2 (3) is used. (Product of the present invention) was used.

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[Table] As is clear from Tables 5 (1) and (2), it is understood that the products of the present invention have better lubricity than conventional products, with no indentation even during short drying times. This suggests that it can be applied without drying, especially for processing with a low area reduction rate. Example 6 As mentioned above, the acid value of the copolymer has a large influence on the ease of removing the residual film after processing. The present inventors used lubricant No. 8 in Table 1 (1) (hereinafter referred to as A) and lubricant No. 8 in Table 2 (2) (hereinafter referred to as B), and A test piece (before drawing) and a test piece after drawing, which were prepared in the same manner as in the elasticity test, were immersed in a 3% by weight solution of sodium orthosilicate to investigate the ease of removing the lubricant. As mentioned above, lubricants A and B both use copolymers having a glass transition temperature (Tg) of 13°C, a total acid value (KOHmg/g) of 20, and a weight average molecular weight of 37,600. The evaluation criteria for ease of removal are as follows. (Easy to remove) ××...No falling off ×...No falling off of the retaining part △...Moderate amount of remaining of the retaining part ○...Slight remaining of the retaining part ◎...Complete degreasing The results are shown in Table 6. As shown in Table 6, it is understood that the products of the present invention are comparable to the conventional products in terms of ease of removal.

[Table] [Effects of the Invention] The present invention is configured as described above, but the key point is to use a butyl acrylate-methyl methacrylate copolymer emulsion having a specified resin acid value and glass transition temperature, or The emulsion with a specified blending ratio of the copolymer emulsion and dibutyl maleate is used as the main ingredient, and a mixed solution is prepared by mixing an aqueous dispersion of one or more types of stearate metal soaps. By using it as a lubricant, benefits such as those listed below can be enjoyed. (1) Since it is not a type that uses chemical reactions like chemical conversion treatment, it is easy to remove after processing. Moreover, since pickling baths, salt baths, etc. are not required, equipment costs are also reduced. (2) Compared to the previous application (Japanese Patent Application No. 59-196193), the indentation caused by uneven coating during coating and drying has been eliminated, and the lubricity is comparable to that, providing stable performance. have (3) Since it can be provided as a one-component type, lubrication is easy (simply immerse the workpiece in this lubricant and dry it). In addition, the drying time can be shortened compared to the conventional resin-coated type, and it can be used without much drying in the case of low processing. (4) It is useful from the standpoint of pollution prevention, as it does not contain substances harmful to the human body or the environment, and does not generate waste liquid. (5) Since it provides a lubricating effect by physically attaching it, it can be applied to all metals. (6) No problem occurs even if the oxide film formed during annealing of the workpiece metal is subjected to lubrication treatment, drawing, or rolling without removing it. (7) It can be used not only for pipe processing, but also for wire processing and plate drawing processing.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the copolymerization ratio of butyl acrylate and methyl methacrylate and glass transition temperature.

Claims (1)

[Claims] 1. Acrylic acid butyl ester having a resin acid value of 10 to 40 and a glass transition temperature of -10 to 20°C.
A lubricant for metal drawing, characterized by comprising an emulsion containing a methacrylic acid methyl ester copolymer and an aqueous dispersion of metal soap. 2. From an emulsion containing an acrylic acid butyl ester-methacrylic acid methyl ester copolymer having a resin acid value of 10 to 40 and a glass transition temperature of 5 to 30°C, an aqueous dispersion of butyl maleate and a metal soap. A lubricant for metal drawing.