Compositions – Heat-exchange – low-freezing or pour point – or high boiling... – Organic components
Reexamination Certificate
1995-06-13
2002-03-26
Medley, Margaret (Department: 1714)
Compositions
Heat-exchange, low-freezing or pour point, or high boiling...
Organic components
C252S078100, C252S079000, C508S466000, C508S469000, C508S473000, C508S474000, C508S485000, C508S486000
Reexamination Certificate
active
06361711
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flame retardant hydraulic oil to be used in rolling mills, die casting machines and the like in the field of the steel making industry and the nonferrous metal industry and in hydraulic instruments and the like in the construction industry. More particularly, it relates to a flame retardant hydraulic oil excellent in the flame retardancy, heat stability and oxidative stability, unaccompanied by the dangers of pinhole fire at sites of use and giving rise to no environmental contamination.
2. Description of the Related Arts
Generally, it is essential that the flame retardant hydraulic oils have the following characteristics:
(1) the oils are excellent in viscosity-temperature properties to ensure the transmission of pressure and power,
(2) the oils have appropriate viscosities to minimize the loss of pressure and power,
(3) the oils are excellent in the heat stability, oxidative stability and lubricity to provide the longer service life,
(4) the oils are excellent in the demulsibility to protect from the possible mixture of water, and
(5) the oils have flash points high enough not to permit the continuous burning even if the oils are ignited, since it is quite likely that the oils are used where there are the high risks of fire.
As these flame retardant hydraulic oils, there have been conventionally used those of emulsion series, those of water-glycol series, those of phosphoric acid ester series, those of fatty acid ester series and the like.
However, the hydraulic oils of emulsion series and those of water-glycol series are low in heat stability, oxidative stability, and lubricity or are difficult to dispose of with waste water.
Furthermore, the hydraulic oils of phosphoric acid ester series have shortcomings in that their viscosity-temperature properties and hydrolytic resistance are deficient, the oils are responsible for the deterioration of seal materials and the exfoliation of coats. Also it is difficult to dispose of waste oils containing such hydraulic oils by burning.
On the other hand, the hydraulic oils of fatty acid ester series are good on the above-mentioned points, having found their application in wide segments of market. But these oils are deficient in the fire resistance and flame retardancy. Various studies have been conducted in an attempt to overcome these problems incidental to the hydraulic oils of fatty acid ester series. In fact, the technique covering the flame retardant oils of fatty acid ester series has been disclosed, for example in Japanese Patent Applications Laid Open No. 18467/1980, No. 226096/1984, No. 125598/1988, No. 214795/1990 and No. 21697/ 1991.
However, all of flame retardant hydraulic oils disclosed in said patent applications have the flame retardancy defined only in terms of flash point. The most important problem of flame retardant hydraulic oils is accidents to be caused by pinhole fire. Specifically, the flame retardant hydraulic oils should have the properties that the oils are hard to catch fire even if the oils are erupted from pinholes and, even in the case of catching fire, do not permit it to develop into the continuous burning if the source of fire is removed. These properties cannot be obtained merely by having the high flash points.
The present inventors have taken note of the properties of continuous burning and conducted the studies by spraying and burning various flame retardant oils under high pressure. The studies have resulted in finding that conventional flame retardant oils of fatty acid ester series (particularly the fatty acid esters made of the oleic acid only) do not have the sufficiently satisfactory flame retardancy, although these oils are highly spoken of as flame retardant.
Thus, the present inventors have made the further intensive studies with a view to developing a flame retardant hydraulic oil of fatty acid ester series free from the properties of continuous burning and excellent in the heat stability, oxidative stability and fluidity. As the results, it has been found that the desired flame retardant hydraulic oil can be obtained by incorporating a fatty acid ester which is formed by reacting a specific polyol with an oleic acid and a isostearic acid or with the oleic acid, the isostearic acid and another monocarboxylic acid in a specific ratio. The present invention has been completed on the basis of this finding.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a flame retardant hydraulic oil containing a hydraulic base oil comprising as the essential component a synthetic ester, which is a product formed by reacting (A) at least one polyol selected from the group consisting of neopentyl glycol, 2,2-dimethyl-3-hydroxypropyl-2′,2′-dimethyl-3′-hydroxypropionate, glycerin and trimethylolpropane with (B) a carboxylic acid comprising 15 to 85% by mole of oleic acid based on the total carboxylic acid and 15 to 85% by mole of isostearic acid based on the total carboxylic acid or a carboxylic acid obtained by incorporating into said carboxylic acid 85% by mole or less of monocarboxylic acid having 6 to 22 carbon atoms (provided that the oleic acids and isostearic acids are excluded) based on the total carboxylic acid, said synthetic ester having a kinematic viscosity of 40 to 80 cSt at 40° C. and a flash point of 290° C. or higher.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in greater detail hereinafter:
The flame retardant hydraulic oils of the present invention use a hydraulic base oil comprising a fatty acid ester as the essential component. The fatty acid esters of the present invention are a synthetic ester obtained by reacting a polyol of Component (A) with an oleic acid and an isostearic acid of Component (B), or by reacting a polyol of Component (A) with an oleic acid, isostearic acid and a monocarboxylic acid having 6 to 22 carbon atoms (provided that oleic acids and isostearic acids are excluded) of Component (B).
The polyols of Component (A), which are used in the reaction to form the synthetic esters are at least one polyol selected from the group consisting of neopentyl glycol, 2,2-dimethyl-3-hydroxypropyl-2′,2′-dimethyl-3′-hydroxypropionate, glycerin and trimethylolpropane. These polyols can be used singly or in their two or more mixture.
On the other hand, the carboxylic acids of Component (B) which are used in the reaction to form the synthetic esters are a carboxylic acid comprising an oleic acid and an isostearic acid as the essential component and further preferably a monocarboxylic acid having 6 to 22 carbon atoms, provided that the oleic acids and isostearic acids are excluded.
Upon their esterification with the polyols of Component (A), the carboxylic acids of Component (B) comprise the oleic acids in a ratio of 15 to 85% by mole to the total carboxylic acid, the isostearic acid in a ratio of 15 to 85% by mole to the total carboxylic acid and the monocarboxylic acid having 6 to 22 carbon atoms in a ratio of 85% by mole or less, preferably 70% by mole or less to the total carboxylic acid, if said monocarboxylic acids are put to use.
If the ratio of the oleic acids in the carboxylic acids is less than 15% by mole, the low fluidity would undesirably result. If it is more than 85% by mole, the flame retardancy would be undesirably deficient. Furthermore, if the ratio of the isostearic acids is less than 15% by mole, the flame retardancy would be undesirably deficient. If it is more than 85% by mole, the fluidity would be undesirably at a low side.
The monocarboxylic acids having 6 to 22 carbon atoms are not particularly limited. Their examples include a straight chain saturated fatty acid such as caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachic acid and behenic acid; a straight chain unsaturated fatty acid suc
Abe Kazuaki
Iwata Mitsuhiro
Seiki Hiromichi
Antonelli Terry Stout & Kraus LLP
Idemitsu Kosan Co. Ltd.
Medley Margaret
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