JPH05156279A - Aqueous lubricant for cold plastic processing of metal - Google Patents

Abstract

PURPOSE:To obtain the subject lubricant comprising a specific metallic soap and an alkali metal salt of a specific unsaturated fatty acid in a specific ratio, extremely reducing an amount of dust produced and retention of lubricant in tools, having excellent maintenance of environment. CONSTITUTION:The objective lubricant comprising (A) a metallic soap composed of an alkali metal salt of 8-22C saturated fatty acid and (B) an alkali metal salt of 8-22C unsaturated fatty acid in a ratio of 5-25wt.%, preferably 10-20wt.% component B based on the components A+B. The lubricant is preferably mixed with a water-soluble film-forming polymer such as PVA.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous lubricant before cold plastic working of metal. Usually, when a metal surface is lubricated, a phosphate treatment is performed as a pretreatment, and then the water-based lubricant of the present invention is applied.

[0002]

2. Description of the Related Art Conventionally, when cold working is performed, a metal surface is lubricated with soap or a similar substance. In general, a phosphate film treatment is performed as a pretreatment process of lubrication treatment with soap. As the soap, an aqueous solution of sodium stearate is generally used. It reacts with zinc phosphate to produce zinc stearate.

On the metal surface treated with such a lubricant, there is a thin film of soap that is easily peeled off, so that a part of the soap film peels off and becomes dust during cold plastic working. It may stick to the tool. Dust generation is environmentally unfavorable. Further, if the lubricant adheres to the tool, it causes mold clogging and the dimensional accuracy of the molded product deteriorates. Therefore, it has become necessary to use a soap lubricant that produces less dust and adheres less to the tool. It is an object of the present invention to develop a lubricant that meets these requirements.

In the English abstract of European Patent Application No. 0301120, A: (A ₁ ) 0.2 to 1.8% (wt%) of polyvinyl alcohol and / or (A ₂ ) said vinyl alcohol with an oxidizing agent Derivatives of polyvinyl alcohol produced by the treatment (in addition to the -OH group, one or more of keto group, carboxyl group, ionic group of carboxylate, and one or more of aldehyde group, keto group and conjugated olefin group). B) (B ₁ ) at least 65% is ₁ to 45% of a water-insoluble fatty acid salt having 16 carbon atoms and (B ₂ ) 0 to 0% of a water-soluble alkali metal soap. 15%, C: 1-6% of borate having (C ₁ ) glass forming action and / or 1-6% of borate of (C ₂ ) (A ₁ ) and / or (A ₂ ), D: 0 to 1% of surfactant 1 The lubricant composition for metal surface treatment containing more than is disclosed.

[0005] The German abstract of German Patent Application No. 257359 describes in the English abstract 1-45% of alkaline earth metal soaps, 0.2-1.8% of polyvinyl alcohol and 4-6% of alkali metal borates. , And the balance consists of water for cold forming lubricants of metals.

[0006] German Patent Application No. 256,804 discloses in English the metal cold-working lubricant consisting of a water-dispersible insoluble soap, a glass-forming inorganic additive, polyvinyl alcohol, and a surfactant. At 0.2
~ 3% is a polyvinyl alcohol derivative modified with an oxidizing agent, and a lubricant having a keto group, a carboxyl group or a carboxylate group in the composition is disclosed.

In the English abstract of Russian Patent Application No. SU-279841, 25-50% oleic acid, 5-10% stearic acid, 15-20% linoleic acid, and 5-10% dihydroxystearic acid, triglycerides and A lubricant for cold plastic working of a metal comprising an alkali metal soap which is an ester of the acid is described.

None of these East Germany, Russia, and European patent applications discloses anything effective in reducing dust generation.

Japanese Unexamined Patent Publication (Kokai) No. 57-40200 discloses a solution of 2 to 5% of an emulsion of a copolymer of ethylene and vinyl acetate as a countermeasure against peeling of a lubricant layer which occurs during cold plastic working. It is stated that it is alleviated by adding a solution of lime soap consisting of quicklime, metal soap, aluminum stearate, and water, or a solution of borax and water. It is stated that the quicklime in the product of the invention has an action of destroying the reaction-generated lubricating layer.

[0010]

When the fatty acid soap composition of the present invention is applied to a metal surface and cold plastic working is performed, dust generation and lubricant adhesion to a tool are significantly reduced. The soap component in the lubricant composition of the present invention comprises an alkali metal salt (A) of a saturated fatty acid and an alkali metal salt (B) of an unsaturated fatty acid.
Is mixed at a ratio of (B) / (A) + (B) at a maximum of 25% by weight. Even if the ratio of the alkali metal salt of unsaturated fatty acid is less than about 2.5% by weight, the generation of dust and the reduction of the amount of the lubricant adhered to the tool can be improved to some extent. Yes, and more preferably about 10-15 or 10-20%.
Alkali metal salts include sodium, potassium, or lithium salts, with sodium salts being more preferred.

The fatty acid used this time has 8 to 22 carbon atoms, regardless of whether it is saturated or unsaturated. The preferred fatty acid has 16 to 20 carbon atoms, more preferably 18 carbon atoms. belongs to. Therefore, it is most preferred to use the saturated fatty acid sodium stearate and the unsaturated fatty acid sodium oleate.

In summary, the product of the present invention is a water-based lubricant for cold metal plastic working, which reduces sticking of the lubricant to the tool and has a saturated carbon number of 8 to 22 (more preferably 18). Alkali metal salt of fatty acid (A) and carbon number 8-22
(More preferably 18) alkali metal salt (B) of unsaturated fatty acid is contained, and the ratio of (B) / (A) + (B) is 25% at maximum (preferably 5 to 22%, more preferably Is a fatty acid soap consisting of a mixture of 10 to 15 or 10 to 20%).

The fatty acid soap of the present invention is soluble in water.
It is also called reactive soap. The reason is
When performing cold plastic working of metal, before applying the lubricant composition
It reacts with the zinc phosphate coating used as pretreatment
Is. A typical reactive saturated fatty acid soap is C₁₈
Sodium stearate, which is commercially available as soap, is
The composition is 95% or more of sodium stearate, C
₁₆Less than 3% fatty acids, C ₁₅And C₁₇Mixed fatty acid with 1% not
I'm full. Sodium stearate concentration is less than this
It is possible to use low grade chemicals, but it is not preferable.
Yes.

The concentration of the lubricant of the present invention used is 5 to 150 g.
It is preferably in the range of / l. More preferably, the minimum is 10 or 16 g / l and the maximum is 60 or 70 g / l.

The lubricant solution of the present invention is preferably free of insoluble soaps such as alkaline earth metal salts of fatty acids and other polyvalent metal ion salts. Such insoluble soaps will contain no more than 1%, or 0.8,0.
5, more preferably 0.1% by weight so that the amount becomes less.

The amount of dust generated in the soap lubricant film and the amount of sticking to the tool can be reduced by adding a water-soluble film-forming polymer to the aqueous lubricant solution without deteriorating the lubricity. This is due to co-applicant Kulongowski, 1990.
It is described in more detail in U.S. Patent Application No. 551982, filed 12 May.

The water-soluble film-forming polymer used is 2-20%, preferably 5-15%, more preferably 6-8%, based on the water-soluble salt of the fatty acid used in the lubricant solution. % By weight.

The water-soluble film-forming polymer used in the present invention is polyvinyl alcohol (hereinafter referred to as "PV
A)), poly-2-ethyl-2-oxazolene (hereinafter "PBO"), polyvinylpyrrolidone (hereinafter "PVP"), and a copolymer of vinyl acetate and ethylene (hereinafter "EVA"). It is preferable that it is selected from the group consisting of Among this group, PVA is the most preferable, and among the types of PVA, it is prepared by hydrolyzing polyvinyl acetate, and the residual acetic acid group is 11 to 13
% Is preferable.

It can also be seen that when the soap solution of the present invention is added as a component to a fatty acid soap formulation together with a water soluble film forming polymer, corrosion of the coated metal is increased. This corrosion can be avoided by adding a corrosion inhibitor to the mixture. The use of corrosion inhibitors is preferred when using film-forming polymers. The preferable amount of the corrosion inhibitor is 0.9 to 8.6, preferably 1 to 7, and more preferably 2 to 5 weight of the amount of the water-soluble fatty acid salt having 8 to 22 carbon atoms used in the lubricant solution. %. Corrosion inhibitors include alkali metal nitrites, organic amines, amine borates (a
min borates), organic carboxylic acids, aromatic sulfonic acids and their water-soluble salts, water-soluble salts of boric acid, alkanolamides, and imidazolines. The most preferred corrosion inhibitor is sodium nitrite. The Babcock number of the aqueous soap solution of the present invention is preferably 0.5 to 5, more preferably 2 to 3.5.
Is.

The solution of the present invention was prepared according to Nus et al.
Complexing agents may be included, as disclosed in US Pat. No. 4,199,381, issued Apr. 22, 1990. The complexing agent may be any substance known in the art, such as ethylenediaminetetraacetic acid (hereinafter referred to as "EDTA") and a salt thereof, n
-Hydroxyethylenediamine triacetic acid (hereinafter "NEDT
A ") and its salts, diethylenetriaminepentaacetic acid and its salts, and diethanolglycine.

When the alkalinity of the lubricant solution is high, the phosphate coating layer is easily peeled off, the amount of dust generated is increased, and the adhesion between the coating and the tool is reduced. Therefore, it is desirable that the pH of the lubricant solution of the present invention does not exceed 11, preferably 10.6, and more preferably 9.6. The most preferable condition is a free acidity of 0.3.
~ 0.6.

Another embodiment of the present invention is a concentrate composition, which is mixed with water as a raw material,
The lubricant composition of the present invention can be adjusted. In general, solid concentrates containing relatively small amounts of water (less than 40% by weight) are preferred for economics of shipment. In order to solubilize the concentrate to an appropriate amount as the reactive soap content and form the lubricant solution of the present invention, the temperature of water must usually be raised to 85 ° C or higher. As mentioned above, the concentration of the lubricant solution is
5-150 g / l, minimum 10-16 g / l, maximum about 60-70 g / l.

The method of practicing the present invention can be carried out by contacting the optimal phosphated metal surface with the lubricant of the present invention, as described above.

An ideal lubrication process is one in which the reacted lubricant is uniform and the weight of the reactive lubricant film is high, and the by-product which inhibits the reaction between the phosphate film component and the lubricant solution is a lubricant. This is to prevent mixing in the solution and remove the phosphate film existing on the metal surface even if mixed in the lubricant solution. In fact, known lubricant solutions do not provide such ideal lubrication. The baths referred to in the prior art as preferred compositions are those which maximize the ratio of reacted lubricant weight to reduced phosphate coating weight. That is, the ratio of the reacted lubricant weight to the unreacted lubricant weight is considered to be an optimum value. In the present invention, the amount of reacted lubricant is not as important as it is in the prior art solutions, but it is important that the ratio of reacted lubricant to unreacted lubricant is less than conventional. Therefore, the lubricity that can be plastically worked is obtained. However, in order to obtain high lubricity, it is necessary to obtain a lubricant weight of at least 3 g / m ^{2 with} the product of the present invention.

The temperature of the lubricant solution in the process of the invention,
And the contact time between the lubricant solution and the phosphated surface is in the range of conditions used in the prior art. For example,
Usually, the temperature is preferably 70 to 90 ° C, more preferably 76 to 87 ° C. The treatment time is preferably 1 to 10 minutes, more preferably 3 to 7 minutes.

Other variables were investigated but had relatively little effect. Further, there was no difference in the amount of dust generated and the amount of the lubricant adhered to the tool between the case where the drying was performed at room temperature for 10 to 15 minutes and the case where the drying was performed at 121 ° C. for 10 to 15 minutes. In addition, the level of phosphate coating weight is such that the number of grams per square meter is 10.8 to 21.6 (“g / m ² ”).
However, there was no clear difference in the amount of dust generation and the adhesiveness of the lubricant to the tool. Phosphate film weight 3g / m
^{When the} amount is reduced to ² , the amount of dust generated and the amount of lubricant adhered to the tool are slightly increased. Therefore, it is preferable that the phosphate coating weight exceeds this value.

[0027]

EXAMPLES In order to specifically describe the present invention, examples and comparative examples will be described below.

The temperature of the lubricant solution is maintained at 79 ° C., the phosphate-treated sample plate is immersed in this solution for 5 minutes, then 8
Dry for 15 minutes in an oven maintained at 8-99 ° C. The sample plate was 0.1% C cold-rolled steel, subjected to alkali cleaning and sulfuric acid cleaning, and subjected to phosphate treatment using (Bonderite ^™ , manufactured by Henkel Corp. (Michigan, USA)). Two types of Bonderite ^™ were used and the solution was maintained at a total acid value of 35 points, but there was no difference in the results as shown below. (In this example, the point is defined as the number of ml of 0.1N NaOH solution required for titrating a 5 ml sample of the above-mentioned phosphate treatment solution to the end point of phenolphthalene.) The phosphate coating weight is The number of grams per square meter of the surface (hereinafter "g / m ² ") for all sample plates
It was 12).

The free acid content of the lubricant solution was measured by the following method. (Free acid) 200 ml of a solution having 0.2% by weight of phenolphthalein in isopropyl alcohol
Pour into a ml beaker and measure with a graduated Erlenmeyer flask or pipette and add to it a 10 ml sample of the hot lubricant solution. Heat the mixture in a beaker to a boil for at least 1 minute. Remove from heat source and immediately titrate with 0.1 N NaOH solution if the sample solution is clear rather than pink in color, while the solution is still hot, until a faint pink color. The ml of solution required for titration is the "point" number of free acid. If the solution is already pink after boiling,
Instead, titrate with 0.1 N sulfuric acid solution until the pink color disappears. The number of ml of acid required in this case is the "point" number of free alkalinity.

The Babcock number of the lubricant solution was measured by the following method. (Babcock number) 10 ml of a solution of 0.2% by weight phenolphthalene in 2-propanol (isopropyl alcohol) is poured into a 50 ml beaker, then exactly 10 ml of the hot lubricant solution is weighed, added to this, Mix and heat to a boil. Whatsman (Wha
tman) 541 Filter paper with high speed filter paper, such as 541 filter paper, and put in a calibrated Babcock test bottle. The beaker and filter paper are then washed with 10 ml of a solution containing 0.2% by weight of phenolphthalene in 2-propanol which has been heated before use. Discard the filter paper and immerse the Babcock test bottle in a boiling water bath for at least 30 minutes to volatilize any 2-propanol. Then, 20 m of 50% by weight sulfuric acid solution
Add 1 to Babcock bottle. Shake the bottle well to mix the contents and heat in a boiling water bath until a clear oil layer forms on top of the liquid in the bottle. Hot water is added if necessary so that the top and bottom of the top oil layer are at the graduated portion of the bottle. The difference in the corresponding scales at the top and bottom of the top oil layer is the Babcock number for this sample. This Babcock number corresponds to the volume% of the oily substance obtained by acidifying a 10 ml sample of the lubricant solution. Each Babcock unit corresponds to 2% by volume of fatty acids in the lubricant solution.
The position of the top and bottom of the oil layer should be read while the bottle is immersed in boiling water to avoid errors due to rapid cooling when the bottle is removed from the bath.

The coating weight of the sample and the associated property values are
It is defined and measured as follows. W1: Weight of the phosphate-treated sample plate (in grams) W2: Weight after dipping the W1 sample plate in the lubricant solution (in grams) W3: Weight after washing the W2 sample plate with water (Grams) Water wash: Soak the sample plate in boiling deionized water for 3 minutes. The amount of water is at least 4. per square centimeter of the sample plate.
Sufficiently set the volume to 3 ml. Remove the sample plate, immerse it in boiling water of similar volume and rinse for 3 minutes. After rinsing, the sample plate is taken out, dried in an oven, cooled to room temperature and weighed. W4: Weight of the sample plate after washing the sample plate of W3 with a solvent. Solvent cleaning: Soak the sample plate with Soxhley,
Or load into a similar extractor. The lubricant reacted with phosphate is extracted with a condensate consisting of a mixture that is vigorously refluxed for at least 30 minutes. The composition of this mixture is 55 wt% isopropyl alcohol, 32 wt% n-heptane,
The rest is 2-ethoxyethanol. Remove the sample plate, cool it to room temperature, and weigh it. W5: Weight after removing the film from the sample plate of W4 with chromic acid (in grams) Chromic acid cleaning: Dissolve 800 g of chromic anhydride in water, and
Adjust to liters. The solution is heated to 82 ° C. Immerse the sample plate for 5 minutes, remove it, and rinse it quickly with cold water. Then it is dried and weighed. A) Amount of film reduced by reaction: (W1-W4) / surface area B) Amount of unreacted lubricant: (W2-W3) / surface area C) Amount of reacted lubricant: (W3-W4) / surface area D) Remaining Coating amount: (W4-W5) / surface area E) Total lubricant amount: unreacted lubricant + reacted lubricant The surface area is measured in square meters.

The tendency of the lubricant coated samples to corrode is measured according to ASTM Standard Method D-2247-87. The results were measured according to the following scale. (Evaluation symbol) (Corrosion area%) R100 R9.5 <10 R9 10 <20 R8 20 ~ <30 R7 30 ~ <60 R6 60 ~ <80 R5 80-100 The amount of red and white corrosion of the test sample was measured. It was visually observed.

The dust generation was evaluated by the following procedure. A square dark velvet fabric, 6.5 centimeters (cm) on each side, was laid on the dry lubricant-coated sample board to be tested. The sample plate was 1.5 cm long and the square velvet fabric was placed in the upper half of the middle of the panel. A cylindrical weight having a mass of 1 kilogram and a diameter of 5 cm was placed in the middle of a square velvet dough. The dough was pulled all the way along the rest of the panel. During this time, the weight stopped at the same position. The light-colored dust caused by the lubricant coating by the pulling operation in the lateral direction was easily visible because the dark-colored velvet cloth was used as the background. The amount of such dust generated was evaluated on a scale of 1-10. 1 shows a state in which no dust is visible, and 10 shows a state in which the dust entirely covers the velvet area in the circular area on which the weight was riding during the pulling operation of the panel.

The ease of withdrawal is based on the Detroit Telecommunications Machinery Company (Detroit Te) of Detroit, Michigan.
"LUB" model pull-out tester manufactured by Sting Machine Company). 1 /
A 2-inch die was used with a tightening force of 91 kg increments up to 2718 kg. The pull-out force is continuously read from the instrument of the machine, and regarding the extent of the amount of lubricant adhered to the tool, the state of the tool when pulled out with the "LUB" model pull-out tester is on a scale of 1-10. evaluated. 1
Indicates a state where there is no adherence to the tool, and 10 indicates a state where the adherence of the lubricant to the tool is severe.

Example 1 A basic lubricant solution was prepared by first adding 154 parts by weight of a 50% aqueous sodium hydroxide solution to 35 parts of water.
It was adjusted by mixing 9 parts by weight and heating the solution to about 75 ° C. High quality industrial chemical grade sodium stearate containing> 95% C ₁₈ fatty acids, <3% C ₁₆ fatty acids, and <1% combined C ₁₅ and C ₁₇ from this melt tank under agitation in this mixture. 526 parts by weight were added. While adding the fatty acid, 5 parts by weight of pine oil was added to the mixture from another container. The temperature of this mixture was maintained with continued mixing until about 45 parts by weight of water were lost by evaporation. The mixture was then allowed to cool, forming a friable solid product containing about 57% by weight sodium salt of a fatty acid.

To prepare the following basic lubricant solution:
The sodium stearate concentrate prepared as described above was dissolved in water at a temperature in the range of 74-94 ° C. The bath volume is 60 to 90 g / l as shown in Table 1.
Oleic acid and NaOH were added to this liquid to obtain a mixture of sodium stearate soap and Bolecock soap of about 2-3 with oleic acid soap. Next, the amount of dust generated and the amount of lubricant adhered to the tool were evaluated. Lubricant composition in Table 1, Table 2
The measurement results of the amount of lubricant adhered, the amount of dust generated, and the amount of lubricant adhered to the tool are shown in.

[0037]

[Table 1]

[0038]

[Table 2]

As can be seen from the above description, the total amount of dust generation and the amount of lubricant adhered to the tool decrease as the amount of sodium oleate (B) increases, and the amount of sodium stearate (A) increases. ) Amount of B / A + B
It can be seen that the ratio of about 5% or more to about 22% is the most preferable. Considering the total fatty acid soap amount, the most preferable result is obtained when the total soap concentration is less than 80 g / l and the concentration is about 10 to 22% by weight.

(Embodiment 2) In this embodiment, the pull-out property is "LUB" mo at a tightening force of up to 2718 kg.
It was measured with a del pullout tester. The pull-out force can be read directly from the instrument of the machine in units of kg.

In a first lubrication test using a 1/2 inch die, an aqueous solution of 75 g / l sodium stearate as described above is applied to the phosphated metal. 75 g with addition of 7.5 g / l oleic acid and sufficient sodium hydroxide to neutralize this oleic acid
/ L of sodium stearate was compared. The dust generation evaluation point of sodium stearate was 10, the dust generation evaluation point of the lubricant obtained by adding oleic acid to stearic acid, and the evaluation point of the amount of the lubricant adhered to the tool were 5. The withdrawal force in kg unit and the tightening force were as shown in Table 3.

[0042]

[Table 3]

Example 3 In this example, another lubrication test was performed on a phosphate-coated metal with a 1/2 inch die using the above aqueous solution of sodium stearate. I went with the board. There are two sets of samples,
One set used an old solution of sodium stearate previously used at a level of 90 g / l and compared it with old sodium stearate supplemented with 5.6 g / l sodium oleate. The second set used freshly prepared sodium stearate at a level of 90 g / l and compared with sodium stearate supplemented with 5.6 g / l sodium oleate. The dust generation evaluation point of the old stearate and the evaluation point of the amount of the lubricant attached to the tool were 7, and the old solution to which sodium oleate was added was 3. The freshly adjusted sodium stearate dust generation rate and the amount of lubricant adhered to the tool have a score of 10, while the freshly adjusted sodium stearate added sodium oleate has a score of 3 each. Met. All liquids had a Babcock number of 3.

[0044]

[Table 4]

From the above description, it is understood that the addition of sodium oleate to the stearate lubricant composition improves the evaluation point of dust generation and the evaluation point of the amount of lubricant adhered to the tool. From Table 4, a significant improvement in pull-out was observed for older lubricants.

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Claims (1)

[Claims] 1. A metal soap containing an alkali metal salt of a saturated fatty acid having 8 to 22 carbon atoms (A) and an alkali metal salt of an unsaturated fatty acid having 8 to 22 carbon atoms (B), The water-based lubricant for cold plastic working of metal, wherein the amount of the alkali metal salt (B) is 5 to 25% (wt%) with respect to the metal soap ((A) + (B)).