Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Specific organic component
Reexamination Certificate
2003-10-22
2004-06-01
Hardee, John R (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Specific organic component
C510S415000, C252S067000
Reexamination Certificate
active
06743765
ABSTRACT:
The invention relates to compositions comprising 1,1,1,3,3-penta-fluorobutane and to their use, for example, as solvents, in particular for drying or degreasing, or as refrigerants.
International agreements aimed at protecting the stratospheric ozone layer require that the use of chlorofluorocarbons (CFCs) and hydrochloro-fluorocarbons (HCFCs) be gradually reduced or even stopped. Compounds of this type are used, inter alia, as solvents or as refrigerants. CFC-113, for example, is used as a solvent for degreasing or cleaning surfaces. More recently, HCFC-141b has been used for these applications. The latter compound is also used with surfactants, in drying agents. CFC-11 and HCFC-123 are used, for example, as refrigerants in turbocompressors.
It is known practice to use 1,1,1,3,3-pentafluorobutane (HFC-365 mfc) as a replacement product which respects the ozone layer in applications as a solvent. However, the use of 1,1,1,3,3-pentafluorobutane requires precautions in order to take account of the flammable nature of the product. It has been proposed to use 1,1,1,3,3-pentafluorobutane in compositions with a specific surfactant and pentafluoropropanol or tridecafluorooctanol (EP-A 863 194). However, these compositions have the drawback of being limited as regards the polarity of the possible mixtures. This limits their capacity to dissolve surfactants. Furthermore, with pentafluoropropanol, increased solubility in semi-aqueous media should be expected, which is unacceptable for certain applications. The high boiling point of the fluoro alcohols used also leads to an enrichment in HFC-365 mfc in the gas phase which makes the vapours flammable. Consequently, the compositions proposed should not be used in drying machines.
The invention is directed towards overcoming these problems.
A subject of the invention is thus compositions comprising 1,1,1,3,3-pentafluorobutane (HFC-365 mfc) and more than 5% by weight of at least one non-flammable fluoro compound selected from perfluorocarbons, hydro-fluorocarbons comprising more than 3 carbon atoms, fluoroamines and fluoro ethers.
It has been found, surprisingly, that the compositions according to the invention have good properties as regards their flammability and good technical properties for a wide range of applications. 1,1,1,3,3-Pentafluorobutane has the particular advantage of being miscible with non-flammable fluoro compounds and of being compatible with additives or solvents usually used in applications such as those mentioned above.
The expressions “non-flammable fluoro compound” and “non-flammable composition” are intended to denote any compound or composition which does not have a determined flash point according to ISO standard 1523.
The non-flammable hydrofluorocarbons (HFCs) and perfluorocarbons used in the compositions according to the invention can be linear, branched or cyclic and generally contain 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Among the hydrofluorocarbons, those comprising at least 5 carbon atoms are suitable for use. 1,1,1,2,3,4,4,5,5,5-Decafluoropentane (HFC-43-10mee) is particularly preferred. Among the perfluorocarbons, those comprising at least 5 carbon atoms are suitable for use. Perfluoropentane and perfluorohexane are preferred. Perfluoropentane and perfluorohexane are usually used in the form of technical mixtures of isomers, as sold, for example, by 3M under the respective names PF5050 for perfluoropentane and PF5060 for perfluorohexane.
The non-flammable fluoro ethers and fluoroamines which can be used in the compositions according to the invention can be linear, branched or cyclic and generally contain 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Among the fluoro ethers, those comprising at least 4 carbon atoms are suitable for use. Perfluorobutyl methyl ether is particularly preferred. Among the fluoroamines, those comprising at least 4 carbon atoms are suitable for use. Perfluorotriethylamine is particularly preferred.
Generally, the non-flammable fluoro compounds have a boiling point at 101.3 kPa of greater than or equal to 15° C. Preferably, the boiling point is greater than or equal to 20° C. Generally, the boiling point is less than or equal to 130° C. at 101.3 kPa. Usually, the boiling point is less than or equal to 100° C. Preferably the boiling point is less than or equal to 85° C.
The F/H numerical ratio (number of fluorine atoms in the molecule divided by the number of hydrogen atoms in the molecule) of the non-flammable fluoro compounds is greater than 2. An F/H numerical ratio of greater than or equal to 2.5 is suitable. Preferably, the F/H numerical ratio is greater than or equal to 3.
The amount of non-flammable fluoro compounds is greater than 5% by weight relative to the mixture consisting of 1,1,1,3,3-pentafluorobutane and non-flammable fluoro compounds. Usually, an amount of greater than or equal to 10% by weight is used. An amount of greater than or equal to 20% by weight is preferred. An amount of greater than or equal to 25% by weight is suitable for use. An amount of greater than or equal to 30% by weight gives good results. In a particularly preferred manner, the effective amount of non-flammable fluoro compound used is that which makes the composition non-flammable, i.e. the composition has no determined flash point according to ISO standard 1523. Generally, the amount of non-flammable fluoro compounds in the compositions according to the invention is not more than 90% by weight.
Preferred compositions according to the invention comprise, as non-flammable compound, at least perfluoropentane, perfluorohexane, perfluorobutyl methyl ether or a mixture thereof A preferred variant of the compositions according to the invention relates to compositions comprising 1,1,1,3,3-penta-fluorobutane and at least one perfluorocarbon in proportions in which they form an azeotrope or a pseudo-azeotrope.
Basically, the thermodynamic state of a fluid is defined by four inter-dependent variables: the pressure (P), the temperature (T), the composition of the liquid phase (X) and the composition of the gas phase (Y). A true azeotrope is a specific system of 2 or more components for which, at a given temperature and a given pressure, the composition of the liquid phase X is exactly equal to the composition of the gas phase Y. A pseudo-azeotrope is a system of 2 or more components for which, at a given temperature and a given pressure, X is substantially equal to Y. In practice, this means that the constituents of such azeotropic and pseudo-azeotropic systems cannot be readily separated by distillation and consequently there is no enrichment in flammable compound in the gas phase.
For the purposes of the present invention, the expression “pseudo-azeotropic mixture” means a mixture of two constituents whose boiling point (at a given pressure) differs from the boiling point of the true azeotrope by a maximum of 0.5° C. Mixtures whose boiling point differs from the boiling point of the true azeotrope by a maximum of 0.2° C. are preferred. Mixtures whose boiling point differs from the boiling point of the true azeotrope by a maximum of 0.1° C. are particularly preferred.
1,1,1,3,3-Pentafluorobutane and perfluoropentane form a binary azeotrope or pseudo-azeotrope when their mixture contains from 50 to 87% by weight approximately of perfluoropentane. Binary compositions containing from 50 to 70% by weight approximately of perfluoropentane are preferred. Binary compositions containing from 50 to 60% by weight approximately are particularly preferred. Binary compositions containing from 65 to 80% by weight approximately of perfluoropentane are also preferred. Binary compositions containing from 70 to 78% by weight approximately are particularly preferred. At a pressure of 100.1±0.2 kPa, the binary composition consisting essentially of about 26% by weight of 1,1,1,3,3-pentafluorobutane and about 74% by weight of perfluoropentane constitutes a true azeotrope whose boiling point is about 24.4° C.
1,1,1,3,3-Pentafluorobutane and perfluorohexane form a binary azeotrope or pseudo-azeotrope when their mixture contains
Barthelemy Pierre
Dournel Pierre
Connolly Bove & Lodge & Hutz LLP
Hardee John R
Solvay ( Societe Anonyme)
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