Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2001-02-09
2002-06-04
Kopec, Mark (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S408000, C510S177000, C510S410000, C134S026000
Reexamination Certificate
active
06399562
ABSTRACT:
The present invention relates to azeotropic or near azeotropic compositions based on hydrofluoropolyethers (HFPE) to be used as substituents of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC 113).
More specifically the present invention relates to azeotropic or near azeotropic mixtures characterized by zero ODP (Ozono Depletion Potential) values or anyway lower than 0.027, by low GWP (Global Warming Potential) and VOC (Volatile Organic Compounds) values to be used as detergent and drying agents in substitution of CFC 113.
As known, CFC 113 has widely been used as solvent and/or drying agent for industrial applications requiring the removal of organic substances (greases, waxes, oils, resins) and/or water from solid surfaces of various nature (metal, glass surfaces, plastics or composites).
For example, CFC 113 has been commonly used for the removal of oils and/or abrasives from metal surfaces of mechanical parts characterized by complex shapes, for the cleaning of high precision metal components, for the removal of water traces from valuables and from components of high quality systems previously washed with aqueous mediums.
In particular in the electronics field, CFC 113 has been used for the removal of organic products and of moisture traces present on the surface of printed circuits characterized by a high density of hardly washable components and for which an high reliability is required.
The removal processes of contaminants from solid surfaces (metals, plastics, glass) are carried out by techniques which involve the solvent action in liquid phase (cold or hot) and/or by the vapour action; in this case the article is exposed to the fluid vapours at its boiling temperature. The vapours by condensing on the cold article surface achieve the solvent and cleaning action.
In all the mentioned applications CFC 113 has often been used also in combination with organic compounds of various nature in order to improve the solvent performances of the product itself. In particular, azeotropic or near azeotropic mixtures which had the advantage to avoid fractionations during the industrial steps of use, manufacture and recovery of the exhausted solvent, have widely been used. Azeotropic or near azeotropic mixtures, as known, are characterized by a composition of the liquid phase substantially equal to the vapour phase composition, they behave, therefore, as a pure compound with the advantage to positively utilize the different properties of the components of the mixture.
CFC 113 is characterized by particular chemical-physical properties so to be advantageously used in the previously described field and it allows, furthermore, a simple, cheap and safe use since it is stable, non flammable and non toxic.
CFCs and specifically CFC 113 have, however, the drawback to have a high ODP, wherefore, their production and commercialization have been banned since 1995.
The need was felt to have alternative products able to replace CFC 113 for the mentioned applications environment friendly.
To this purpose, in the solvent field, the use of alternative systems based on aqueous solutions, of non halogenated organic solvents and of hydrohalogenated solvents of the HCFC type has been suggested. These alternatives have however several drawbacks.
In particular it happens that the articles with microhollows, with capillary holes and surface irregularities, are insufficiently washed due to the relatively high water surface tension, also in the presence of surfactants.
The water removal rate is very low and when it is not completely removed it can cause corrosion phenomena of the metal articles previously washed. Therefore such surfaces must be suitably dried after being washed.
Hydrocarbons, alcohols or other non halogenated organic solvents, due to their high flammability, have not a generalized use and require however great investments to avoid the fire and explosion risk in the plants using them.
Besides, these solvents are an atmospheric pollution source since, when they are exposed to the sun light in the presence of nitrogen oxides, they undergo oxidative degradation phenomena, with formation of the so called “oxidizing smog” ozone-rich. Because of this negative characteristic these products are classified as VOC (Volatile Organic Compound).
Hydrohalogenated solvents represent a class of products more similar to CFC 113, they give lower use complications and allow more generalized applications with respect to the above mentioned alternative systems.
HCFC 141b, which has been and is one of the most valid substituents for these applications, has however the drawback to be moderately flammable and above all to be characterized by an ODP value equal to 0.11 (CFC 11=1) and therefore it has been subjected to use limitations and rules in favour of products having a lower or zero ODP.
The need was felt to have available alternative products able to further limit or to definitively overcome the above mentioned environmental and safety problems and able to allow a simpler and generalized use as solvent-cleaning agents.
The use of non toxic solvents having a low environmental impact, formed by hydrofluoropolyethers and compositions thereof having limited concentrations of polar substances selected among alcohols, ketones and ethers as described in the European patent application EP 805,199, is known in the removal of oils, greases, waxes, etc. from surfaces.
In connection with what described in the prior art the need was felt to have available valid alternatives to CFC 113.
It was in fact necessary to have available products able to remove oily substances in a substantially similar way to CFC 113, i.e. by partial or total solubilization of the substances to be removed, therefore differently from pure or additived hydrofluoropolyethers, in order to guarantee a more accurate and quicker cleaning of the articles having complex shapes and microhollows, with considerable advantages in terms of efficiency and economic saving of the cleaning operation.
Besides, products having chemical-physical properties more similar to CFC 113 allow the recovery of the existing plants without implying substantial modifications of the same and they allow to maintain practically unchanged the various operating steps of the article cleaning process.
Finally, the need was evident to limit or remove the environmental and safety problems typical of the conventional solvents (hydrocarbons, HCFC), and to reduce the costs of the cleaning operations deriving from the use of pure or additived HFPEs, as above described, since as it is known these products are obtained by complex and expensive processes.
The Applicant has unexpectedly found mixtures based on hydrofluoropolyethers (HFPE) having an azeotropic or near azeotropic behaviour, characterized by chemical-physical properties such as to be suitable as substitutes of CFC 113, and by an environmental impact expressed in terms of ODP lower than 0.027 and low GWP and VOC values.
The compositions of the present invention are able to meet the previously mentioned requirements, they can easily be used at acceptable costs with results almost similar to CFC 113, without implying substantial modifications to the various operating steps, in the respect and protection of the environment.
An object of the present invention are therefore azeotropic or near azeotropic compositions, based on 1-difluoromethoxy-1,1,2,2-tetrafluoroethyl difluoromethyl ether, to be used as CFC 113 substitutes having a low environmental impact, essentially consisting of:
composition
% by weight
general
preferred
I)
1-difluoromethoxy
15-99
25-97
1,1,2,2-tetrafluoroethyl
difluoromethyl ether
(HCF
2
OCF
2
CF
2
OCF
2
H);
isopentane
85-1
3-75
II)
1-difluoromethoxy
25-99
30-97
1,1,2,2-tetrafluoroethyl
difluoromethyl ether
(HCF
2
OCF
2
CF
2
OCF
2
H);
methyl-acetate
75-1
3-70
III)
1-difluoromethoxy
35-99
38-97
1,1,2,2-tetrafluoroethyl
difluoromethyl ether
(HCF
2
OCF
2
CF
2
OCF
2
H);
1-bromo-propane
65-1
62-3
More specifically the azeotropic compositions, which show an absolute minimum or maximum
Basile Giampiero
Musso Ezio
Visca Mario
Arent Fox Kintner Plotkin & Kahn
Ausimont S.p.A.
Kopec Mark
Webb Gregory E.
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