Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Sulfurized compound of indeterminate structure – which is a...
Reexamination Certificate
2001-06-15
2002-07-02
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Sulfurized compound of indeterminate structure, which is a...
C508S331000, C072S042000
Reexamination Certificate
active
06413917
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a water-soluble extreme-pressure additive and its production method.
BACKGROUND ART
Various oil agents have conventionally been used to prepare liquids for cutting or grinding metal, and water-soluble oil agents have been used particularly preferably due the advantages resulting from using water for their medium, namely cooling effects, incombustibility, economics and low level of environmental contamination. However, water-soluble oil agents have problems in terms of their metal machining performance such as decreased finished surface accuracy and tool service life due to insufficient load resistance and insufficient friction reducing effects and other factors relating to lubricating performance. Moreover, they also have problems characteristic of water-soluble oil agents such as foaming during use, rust formation, decay and foul odor. Various improvements have been attempted in the past to remedy these characteristic problems.
In order to impart greater load resistance, extreme-pressure additives that are virtually insoluble in water are used, examples of which include emulsion-type oil agents in which a chlorine-based extreme-pressure additive such as chlorinated paraffin or chlorinated fatty acid ester, or as described in Japanese Unexamined Patent Application, First Publication No. Hei 7-157793, a sulfur-based extreme-pressure additive such as a sulfurized resin, sulfurized olefin or dialkylpolysulfide, is dispersed in water using a large amount of surfactant. However, the extreme-pressure performance of emulsion-type oil agents is inadequate, management of liquid in the emulsion state is bothersome, and there are environmental problems including contamination by the oil component due to breakdown of the emulsion and the need to wash machined products with solvent and so forth.
Attempts have also been made to produce soluble oil agents using sulfurized, long-chain unsaturated fatty acid salts like the alkanol amine salt of sulfurized oleic acid as examples of solubilization with a sulfur-based extreme-pressure additive. However, although extreme-pressure performance is high, this has disadvantages including difficulty in achieving complete solubilization unless a surfactant is used, potent odor and violent foaming.
Soluble oil agents using other extreme-pressure additives include the use of di-(2-hydroxyethyl)disulfide as described in U.S. Pat. No. 4,250,046, the use of an alkanol amine salt of 3-mercaptopropionic disulfide described in Japanese Unexamined Patent Application, First Publication No. Sho 63-284294, and the use of an alkanol amine salt of alkylthiopropionic acid described in Japanese Unexamined Patent Application, First Publication No. Hei 5-43886. However, none of these are adequate for improving extreme-pressure performance and lubricating performance.
Examples of soluble oil agents not containing sulfur include the alkaline metal or amine salt of a condensation product of ricinoleic acid described in Japanese Examined Patent Application, Second Publication No. Sho 60-49677 and Japanese Examined Patent Application, Second Publication No. Hei 2-5799, and the alkaline metal salt or amine salt of a condensation product of a hydroxy long-chain fatty acid described in Japanese Unexamined Patent Application, First Publication No. Hei 7-97590. Both of these offer excellent odor, defoaming property, decay resistance and rust prevention. However, they have the disadvantage of extreme-pressure performance being considerably low as compared with sulfur-based extreme-pressure additives.
DISCLOSURE OF THE INVENTION
In consideration of the actual circumstances as described above, the object of the present invention is to provide an extreme-pressure additive having excellent load resistance and lubricating performance while also having satisfactory odor, defoaming property and rust prevention.
As a result of conducting various studies to achieve this object, the inventors of the present invention found that, instead of using for the extreme-pressure additive the condensation product of a hydroxy-unsaturated fatty acid itself, by crosslinking the unsaturated double bonds within the molecule with sulfur to introduce a sulfur-crosslinked structure into the molecule, and forming the salt of a sulfurized, condensed hydroxy-unsaturated fatty acid, an extreme-pressure additive can be obtained having excellent performance.
In addition, it was also found that in the case of using ricinoleic acid for the hydroxy-unsaturated fatty acid, a salt of condensed ricinoleic acid, having a sulfur-crosslinked structure in its molecule resulting from reacting ricinoleic acid with sulfur and hydrogen sulfide at a comparatively low temperature, has the best characteristics as a water-soluble extreme-pressure additive, namely excellent load resistance, lubricating performance, complete solubility, odor, defoaming property and rust prevention, thereby leading to completion of the present invention.
Namely, the present invention is an extreme-pressure additive comprising the salt of a condensation product of a sulfurized hydroxy-unsaturated fatty acid having a specific sulfur content, specific color and specific acid number.
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, typical examples of salts of condensation products of sulfurized hydroxy-unsaturated fatty acids include those having all of the following compositions in terms of chemical structure:
(X) the hydroxy-unsaturated fatty acid has a condensed structure (ester bond);
(Y) the hydroxy-unsaturated fatty acid has a sulfur-crosslinked structure in which a sulfur atom is added to a carbon-carbon unsaturated double bond within the molecule based on a hydroxy-unsaturated fatty acid; and,
(Z) a carboxyl group based on a hydroxy-unsaturated fatty acid has a salt structure and is contained in the molecule of the condensation product.
Furthermore, a hydroxy-unsaturated fatty acid refers to that having a hydroxyl group, carbon-carbon unsaturated double bond and carboxyl group within its molecule.
Although the salt of the condensation product of the sulfurized hydroxy-unsaturated fatty acid may be obtained by reacting in any order, it is preferable that the condensation product of a sulfurized hydroxy-unsaturated fatty acid be obtained first, followed by its conversion to a salt. In the obtaining of the condensation product of the sulfurized hydroxy-unsaturated fatty acid of the previous stage, the hydroxy-unsaturated fatty acid may be sulfurized while condensing followed by the introduction of an ester bond structure and sulfur-crosslinked structure into its molecule.
This method is preferable because it is able to improve productivity as a result of having few production steps and so forth, while also allowing a sulfur-crosslinked structure to be easily introduced into the molecule.
In addition, as an example of a specific method, hydroxy-unsaturated fatty acid, sulfur and hydrogen sulfide are condensed together with sulfurizing the hydroxy-unsaturated fatty acid in the presence of a catalyst as necessary while heating and applying pressure at a comparatively low temperature.
This method is preferable since controlling the reaction, including the sulfur content and so forth, is easier, the resulting product is colored less and there is less odor. It is preferable to select the reaction temperature to be higher than 100° C. but not higher than 150° C., and the reaction time to be within the range of 1-20 hours. Since this method can be carried out at a comparative low pressure and comparative low temperature, it is also preferable since the amount of energy consumed per unit production volume can be reduced, and the reaction can be carried out in a reaction vessel having ordinary pressure resistance.
Although the acid value of the condensation product of the sulfurized hydroxy-unsaturated fatty acid is 80-200 mg KOH/g, and particularly 100-160 mg KOH/g, this is preferable in that it offers both excellent lubricating performance and stable water solubility without using a surfacta
Ibi Kazumasa
Yamada Shigeru
Armstrong Westerman & Hattori, LLP
Dainippon Ink and Chemicals Inc.
McAvoy Ellen M.
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