Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-05-13
2001-07-24
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S200000, C510S241000, C510S365000, C510S437000, C510S505000, C134S038000, C134S040000, C134S042000
Reexamination Certificate
active
06265367
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable
The present invention relates to methods of cleaning coated surfaces, to compositions suitable for use in the methods, and to methods of preparing the compositions.
Hard surfaces with a coating are used in a variety of situations where they can become soiled. Some coatings are hard by nature and are resistant to abrasion and solvents. Thus, vitreous enamel coatings on cooking stoves can be cleaned with abrasives or with a variety of solvents having a strong dissolving action on oils and grease. However, in the domestic and office environment many surfaces coated with varnishes and paints become soiled, with cigarette smoke or other air-borne contaminants, and with grease and food debris. The resulting soil can be difficult to remove.
A harsh abrasive cleaner will damage many surface coatings, as will many solvents. Indeed, some solvents and mixtures of solvents are used in paint stripping liquids. The use of organic solvents may also not be acceptable in the domestic or office environment if high concentrations of solvent vapor are produced.
It is desirable to be able to use a single cleaning product on various types of paints and varnishes found around the home. However, water-based paint systems are highly susceptible to damage from aqueous or solvent based cleaners. Oil-based paints are more robust. Much of the discoloration of oil-based paints occurs as a result of deterioration of the pigment close to the film surface. We have found that this can be treated with a mildly abrasive product. However, the incorporation of abrasives into liquid systems gives rise to problems if a homogeneous liquid is to be obtained.
It can therefore be seen that there is a need for a liquid composition which provides effective cleaning of painted and varnished surfaces without damaging the paint or varnish. It is desirable for such a liquid composition to remain homogeneous under normal storage conditions, in order to prevent important ingredients settling out so as to avoid the formation of liquid phases having insufficient or excess activity.
BRIEF SUMMARY OF THE INVENTION
One aspect of the present invention provides a method of cleaning a coated surface having a strippable surface coating. One brings the surface into contact with a liquid cleaning composition that has:
a) an ester solvent that has a Hansen solubility parameter in the range 9.5 to 11 which is present in an amount which is 3.0% to 7.2% by weight based on total weight of composition,
b) a surfactant system in an amount in the range 3.5% to 7.5% by weight of active material based on the total weight of composition, the system having a natural soap and a nonionic surfactant,
c) an abrasive in an amount which is 0.5% to 4.0% by weight based on total weight of composition, and
d) at least 70 % by weight of water based on total weight of composition.
According to a further aspect of the present invention there is provided the above liquid cleaning composition.
In another aspect there is provided a process for preparing a liquid cleaning composition suitable for cleaning strippable surface coatings. It includes the successive steps of forming a natural soap at an elevated temperature in an aqueous medium by reaction of a fatty acid derivative with an alkali; adding in any sequence the ester solvent and a nonionic surfactant; and producing a stable dispersion of abrasive particles in the aqueous medium by adding abrasive particles at a controlled rate to the aqueous medium with agitation while allowing the liquid to cool from the elevated temperature. The amounts of ingredients are selected to yield a liquid cleaning composition as described above.
The method of cleaning can be applied to surfaces coated with strippable surface coatings. By “strippable” surface coating we mean a coating which is removed or softened when left in contact with methylene cloride. In this regard most paints and varnishes applied in situ in homes and offices are strippable.
The composition may be applied to the surface to be cleaned by spraying, and may be removed from the surface subsequently by rinsing with water. Preferably the composition is applied to the surface to be cleaned by bringing an absorbent solid article (e.g. a sponge or a cloth) containing the composition into contact with the surface. Also preferably, manual pressure is applied to the absorbent solid during the application of the composition to the surface.
The ester solvent has a Hansen solubility parameter in the range 9.5 to 11, preferably 9.8 to 10.2. Hansen solubility parameter is a well-known method of characterizing solvents. It is discussed in Kirk-Othmer Encyclopedia of Chemical Technology, suppl. Vol.; 2nd Edition, 1971, p.889ff. Methods for determining the solubility parameters are given in ASTM D3132-84.
The ester solvent may be a single ester or a mixture of esters. Preferably the ester is a dialkyl (e.g. dimethyl) ester of a low molecular weight dibasic organic acid, e.g. having a molecular weight of from 60 to 250. It is particularly preferred to use dimethyl esters of glutaric, succinic, and adipic acids, in particular a mixture of the above acids in the weight ratio 3:2:1.
The ester solvent is present in the formulation in an amount in the range 3.0% to 7.2% by weight based on the weight of total composition. The composition preferably contains an additional organic solvent which may be a terpene or a glycol ether and may be in an amount in the range 0.5% to 2.5% by weight based on total weight of composition.
Examples of terpenes suitable for use in the present invention are d-limonene, orange terpenes. Examples of glycol ethers suitable for use in the present invention are propylene glycol methyl ether, dipropylene glycol methyl ether. Examples of glycol ethers are those sold under the trade names “Dowanol P” and “Dowanol E” by the Dow Chemical Company. The “P” series glycol ethers are derived from propylene glycol and the “E” series glycol ethers are derived from ethylene glycol.
The quantity of the terpene or glycol ether solvent is in the range 0.5% to 2.5% by weight based on the total weight of the composition, preferably 1.0 to 2.0% by weight. The composition contains a surfactant system in an amount in the range 3.5% to 7.5% by weight based on total weight of composition. Commercially available surfactant often contain inactive material and the weight percentages given above are based on active material in the product as sold. The surfactant system contains a natural soap and a nonionic surfactant. Preferably it also contains an alkyl sulphate.
The natural soap may be an alkali metal, ammonium or polyalkyl ethanolamine salt of a naturally occurring fatty acid. Such soaps may be obtained by the hydrolysis of naturally occurring fatty acid triglycerides (e.g. coconut oil or tallow) with caustic soda or caustic potash and neutralization of the fatty acids released by hydrolysis. It may be formed in situ in the composition by including appropriate amounts of triglyceride and alkali in the composition.
The nonionic surfactant may for example be an ethoxylate of a linear alkanol. Preferably the alkanol has an average chain length in the range 9-11. It preferably contains an ether chain corresponding to reaction with 2 to 11, e.g. 3, molecules of ethylene oxide per molecule of alkanol.
The alkyl sulphate surfactant, if present, preferably has a carbon chain with an average chain length of from 10 to 18 carbon atoms, more preferably 10 to 14 carbon atoms. The alkyl chain is preferably a straight chain derived from natural sources. The alkyl sulphate salt is preferably a sodium, potassium, ammonium or an alkanolamine salt.
The natural soap is preferably the main component of the surfactant system. Thus the surfactant system preferably contains at least 4 parts of soap per part of nonionic surfactant by weight, more preferably at least 3 parts per part of nonionic surfactant by weight. The nonionic surfactant is preferably present in an amount not greater than 3 parts by weight per part by weight of alkyl su
Adat Balvinder
Callaghan Ian C.
Freeman Judith Ann
Gupta Yogendra N.
S. C. Johnson & Son Inc.
Webb Gregory E.
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