GB2298433A

GB2298433A - Cleaning composition

Info

Publication number: GB2298433A
Application number: GB9503462A
Authority: GB
Inventors: Thomas Wee Sun Lee
Original assignee: Exxon Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 1995-02-22
Filing date: 1995-02-22
Publication date: 1996-09-04
Also published as: GB9503462D0

Abstract

A cleaning composition for electronic components and metal parts comprises (i) at least 90 parts by volume of a hydrocarbon-containing fluid containing not less than 99% by weight, based on the total weight of the fluid, of a mixture of paraffinic and naphthenic hydrocarbons selected from C8 to C15 paraffinic and naphthenic hydrocarbons; and (ii) at most 10 parts by volume of an alkyl acetate in which the alkyl group is a linear or branched saturated alkyl having from 6 to 8 carbon atoms; ```the composition being substantially free of any halogen-containing compound. The alkyl acetate may be selected from hexyl acetate, heptyl acetate and mixtures thereof.

Description

Cleaning composition and its use The present invention relates to fluid cleaning compositions and their use. In particular, the invention is concerned with cleaning compositions for use, for example, in cleaning soiled metal and precision parts.

As cleaning solvents for removal of grease and oil from metal parts and silicone oil and adhesive residues from precision parts there have previously been used chlorinated solvents, for example, l,l,l,-trichloroethane and 1,1,2,-trichloroethylene, together with alkaiine surfactants. After application of the solvent and surfactant the substrate is rinsed in water. Another cleaning solvent that has been used previously is kerosene. l,l,l,-Trichloroethane is, however, known to be an ozone-depleting substance, and 1,1,2,-trichloroethylene and kerosene are considered harmful to human health. In consequence, considerable care must be taken in the handling, storage and disposal of those solvents, and their usage is subject to stringent regulations related to environmental control.

There is a need for a cleaning composition that, whilst having the advantageous cleaning properties of the previously used solvent systems, is less toxic than the kerosene and 112-trichloroethylene previously used and does not have the detrimental effect on the ozone layer that is associated with those solvents.

WO93/13246 (Exxon) describes a cleaning composition comprising a mixture of a hydrocarbon fraction and an alcohol.

WO91/06690 (Henkel) describes a cleaning composition comprising a mixture of one or more aliphatic hydrocarbons with one or more organic compounds having one or more polar groups. The organic compound with the polar group may be an ester. The only ester specifically mentioned is ethyl acetate, although there is no specific disclosure of any composition including that compound.

Japanese Patent Specification No. 05-140593 describes a cleaning composition for precision parts, for example, for cleaning machine, electronic or electrical parts, containing a hydrogenated olefin oligomer and, optionally, a compound selected from alcohols, esters and ethers having 3 to 18 carbon atoms, compounds of the general formula R-OCnH2n OH (in which n may be an integer of 1 to 4), surfactants and aprotic solvents. The olefin oligomer is obtained by polymerisation of an olefin having up to ten carbon atoms and hydrogenating the polymerisation product so obtained.

It has been found that a particularly effective cleaning composition may be obtained by mixing a hydrocarbon mixture containing paraffinic and naphthenic hydrocarbons with an alkyl acetate in which the alkyl group has from six to eight carbon atoms.

The invention provides a cleaning composition, especially one suitable for cleaning articles, comprising (i) at least 90 parts by volume of a hydrocarboncontaining fluid containing not less than 99% by weight, based on the total weight of the fluid, of a mixture of paraffinic and naphthenic hydrocarbons selected from C8 to C15 paraffinic and naphthenic hydrocarbons; and (ii) at most 10 parts by volume of an alkyl acetate in which the alkyl group is a linear or branched alkyl group having from 6 to 8 carbon atoms; the composition being substantially free of any halogen-containing compound.

Advantageously the composition comprises from 90 to 99 parts of component (i) and from 1 to 10 parts of component (ii).

The composition of the invention is able to clean effectively metal parts contaminated with cutting oil, stamping oil, lubricant oil and other greasy contaminants that typically adhere to metal parts during manufacturing. It is also able to clean effectively precision parts used in the electronics industry, for example, leadframes and condensers, contaminated with light grease, silicone oil, adhesive substances and fingerprints.

The hydrocarbon-containing fluid is advantageously a hydrocarbon distillation fraction having a distillation boiling range at atmospheric pressure of which the lower limit is preferably not less than 150to and the upper limit is preferably not greater than 250or. For example, the hydrocarbon-containing fluid may have a boiling range of 160"C to 240"C. The hydrocarbon distillation fraction may be, for example, a distillation fraction obtained by distillation of petroleum, which may optionally have been subjected to further treatment, for example, hydrogenation.

The distillation boiling range of the mixture of the hydrocarbon-containing fluid and the acetate component advantageously has a lower limit of not less than 140"C at atmospheric pressure. The distillation boiling range of the said mixture advantageously has an upper limit of not greater than 275"C at atmospheric pressure. The kauri-butanol value of the mixture is advantageously from 25 to 32.

The hydrocarbon-containing fluid may be a mixture of paraffinic and naphthenic hydrocarbons with 0.5 to 2 parts by volume of normal and iso-paraffins per part by volume of naphthenes. Preferably, the hydrocarboncontaining fluid is a mixture of paraffinic and naphthenic hydrocarbons having 20-35 volume % of normal paraffins, 20-35 volume % iso-paraffins and 35-55 volume % of naphthenes. This combination of hydrocarbons ensures good solvation effect on hydrocarbon-based grease and oil contaminants.

The composition may contain not exceeding 1% by weight of aromatics based on the combined aromatics and hydrocarbons content. Advantageously, the cleaning composition comprises not more than Sppm of halogen in terms of weight.

The acetate component is advantageously selected from hexyl acetate, heptyl acetate, and mixtures thereof.

The or each said acetate may be present in two or more isomeric forms. The combination of the relatively polar alkyl acetates with the relatively non-polar hydrocarbons provides advantageous cleaning properties for soilcontaining metal parts and precision parts.

The present invention further provides a method of cleaning articles, comprising treating an article with a cleaning composition comprising (i) at least 90 parts by volume of a hydrocarboncontaining fluid containing not less than 99% by weight, based on the total weight of the fluid, of a mixture of paraffinic and naphthenic hydrocarbons selected from C8 to C15 paraffinic and naphthenic hydrocarbons; and (ii) at most 10 parts by volume of an alkyl acetate in which the alkyl group is a linear or branched saturated alkyl having from 6 to 8 carbon atoms; the said composition being substantially free of any halogen-containing compound.

The articles to be cleaned may be immersed in said cleaning composition. The temperature of said cleaning composition is advantageously from 25"C to 70"C. The article is advantageously kept immersed in the composition for from 1 to 10 minutes. The effectiveness of cleaning may, if desired, be.enhanced by agitating the cleaning composition, for example, by stirring or ultrasonic means. The cleaning composition may be applied to the articles by spraying.

Following application of the composition to the article, the cleaning composition is permitted to drain from the article and the article is dried, for example, by subjecting it to a stream of hot air. Optionally, the article may be contacted with a detergent solution and rinsed with water to remove the detergent solution before drying.

The solvent mixture of the invention enables use of the halogen-substituted organic compounds to be avoided whilst nevertheless giving high quality cleaning.

Further, the mixture has low toxicity and a high flash point, ranging from, for example, 45"C to 85"C, so that it is relatively safe to use and special handling procedures are unnecessary.

The following Examples illustrate the invention.

Examples 1 to 8 A cleaning composition was prepared by mixing 99 volume % of a hydrocarbon mixture consisting essentially of C8 to C15 hydrocarbons (20 to 30% of which were normal paraffins, 20 to 35% of which were iso paraffins and 35 to 55% of which were naphthenic compounds) with 1 volume % of an acetate mixture containing heptyl acetate and hexyl acetate.

Contaminated metal parts and electronic components were immersed in a bath of the cleaning composition, the temperature of the cleaning composition being 25"C, and the composition being subjected to ultrasonic agitation during immersion. After removal from the bath each part or component was dried by subjecting it to a stream of air at 35"C for 60 seconds.

The following table illustrates the cleaning effect of the cleaning composition for various metal parts and precision parts each containing different types of grease and oil. The % clean determines the percentage of grease or oil content removed from the parts upon cleaning. It also indicates the cleaning property of the cleaning composition. To determine the cleaning efficiency (% clean) the grease or oil remaining on the parts after cleaning was compared with the grease or oil present on the parts before cleaning. That was done by repeatedly extracting the grease or oil using a mixture of isooctane and alcohol and comparing the UV absorbance of the liquid extracts of the parts which had been cleaned with that of extracts from parts which had not been cleaned.

Table EXAMPLE PART SOIL. CONDITIONS %CLEAN 1 metal films stamping 25"C, 5 min 98% oil 2 aluminium parts cutting 25"C, 2 min 99% oil 3 steel screws lub oil 25 C 5 min 95% 4 steel camtops lub oil 25"C, 5 min 92% 5 steel I-locks lub oil 25"C, 5 min 99% 6 leadframes silicone 25 C, 5 min 99% 7 leadframes adhesive 25 C, 10 min 99% 8 top-covers silicone 25 C, 5 min 98%

Claims

1. A composition for cleaning articles comprising (i) at least 90 parts by volume of a hydrocarboncontaining fluid containing not less than 99% by weight, based on the total weight of the fluid, of a mixture of paraffinic and naphthenic hydrocarbons selected from C8 to C15 paraffinic and naphthenic hydrocarbons; and (ii) at most 10 parts by volume of an alkyl acetate in which the alkyl group is a linear or branched saturated alkyl having from 6 to 8 carbon atoms; the composition being substantially free of any halogen-containing compound.

2. A composition as claimed in claim 1, in which the hydrocarbon-containing fluid is a petroleum distillation fraction having a distillation boiling range of which the lower limit is not less than 150by.

3. A composition as claimed in claim 1 or claim 2, in which the hydrocarbon-containing fluid is a petroleum distillation fraction having a distillation boiling range of which the upper limit is not greater than 250to.

4. A composition as claimed in any of claims 1 to 3, having a distillation boiling range of which the lower limit is not less than 140"C at atmospheric pressure.

5. A composition as claimed in any of claims 1 to 4, having a distillation boiling range of which the upper limit is not greater than 275"C at atmospheric pressure.

6. A composition as claimed in any of claims 1 to 5, having a kauri-butanol value of from 25 to 32.

7. A composition as claimed in any of claims 1 to 6, in which the alkyl acetate is selected from hexyl acetate, heptyl acetate and mixtures thereof.

8. A composition as claimed in any of claims 1 to 7, which comprises from 90 to 99 parts of component (i) and from 1 to 10 parts of component (ii).

9. A cleaning composition substantially as described in Examples 1 to 8 herein.

10. A method of cleaning an article, comprising treating an article with a cleaning composition comprising (i) at least 90 parts by volume of a hydrogen-containing fluid containing not less than 99% by weight, based on the total weight of the fluid, of a mixture of paraffinic and naphthenic hydrocarbons selected from C8 to C15 paraffinic and naphthenic hydrocarbons; and (ii) at most 10 parts by volume of an alkyl acetate in which the alkyl group is a linear or branched saturated alkyl having from 6 to 8 carbon atoms; said composition being substantially free of any halogen-containing compound.

11. A method as claimed in claim 10, in which the article is immersed in said cleaning composition.

12. A method as claimed in claim 11, in which the article is kept immersed in said cleaning composition for from 1 to 10 minutes.

13. A method as claimed in any of claims 10 to 12, in which the temperature of said cleaning composition is from 25"C to 70"C.

14. A method as claimed in any of claims 10 to 13, in which the cleaning composition is a composition according to any of claims 2 to 9.

15. A method as claimed in any one of claims 10 to 14, in which the article is an electronic component.

16. A method of cleaning an article substantially as described in any one of Examples 1 to 8 herein.

17. The use of a composition according to any one of claims 1 to 9 to remove hydrocarbon-based contaminants from metal or precision parts.