GB2112012A - Replenishment composition for cleaning aluminium surfaces - Google Patents

Abstract

A temperature stable, aqueous acidic replenishment composition comprises water, mineral acid and 10 to 20% of a mixture of polyalkylene glycol-abietic acid surfactant and polyalkylene glycol-hydrocarbon surfactant. This replenishment composition is used for replenishment of a treatment solution by which aluminium surfaces are cleaned comprising water, mineral acid and the two surfactants.

Description

SPECIFICATION Replenishment for aluminium cleaners During cold forming of aluminium an organic lubricant is generally applied to the aluminium surfaces to facilitate the forming operation. A residue of the lubricant remains on the surface after forming is completed and must be removed in a cleaning operation for some uses of the aluminium.

There is described in US Patent Specification No. 3,969,135 a cleaner that is effective for this purpose even when used at low temperatures. The cleaner is an aqueous acidic cleaning composition containing a polyalkylene glycol-abietic acid surfactant and a polyalkylene glycol-hydrocarbon surfactant. The composition also preferably contains fluoride.

Prolonged use of the composition results in depletion of active ingredients in it, and the consequential need for replenishment of the active ingredients.

If a cleaner or other treatment composition is to be replenished it can of course be replenished by adding the individual ingredients, as necessary, to the treatment composition. Replenishment by addition of a single composition containing all the necessary replenishment chemicals in fixed proportions is conducted in some processes for treating surfaces but it is liable to incur some difficulties in practice. One difficulty is that it may be difficult to determine a suitable fixed ratio of components such as to maintain the desired relative concentrations of the ingredients in the treatment solution. Even if the desired fixed proportions can be determined a further difficulty can arise in providing the replenishment chemicals in the form of a stable homogeneous coposition.If the composition is not sufficiently stable and homogeneous it will settle out during storage to such an extent that it is difficult to achieve uniform replenishment of the treatment solution.

These problems occur particularly in the replenishment of solutions such as those described in US Patent Specification No.

3,969,135.

The invention is based in part on the discovery that it is possible to maintain the desired concentrations of treatment solution such as those described in that patent by replenishment with a replenishment composition containing a fixed ratio of surfactants and, if present, of surfactants to fluoride. It is also based in part on the discovery that although such single replenishment compositions are liable to be unstable and non-homogeneous during storage it is possible to provide stable homogeneous replenishment compositions containing all the ingredients necessary for replenishment of the treatment solutions described in US Patent No.

3,969,135.

According to the invention an aqueous acidic replenishment composition suitable for replenishment of the treatment solutions described in US Patent No.3,969,135 comprises water, mineral acid and a mixture of polyalkylene glycol-hydrocarbon surfactant and polyalkylene glycol-abietic acid surfactant and this composition can be a homogeneous temperature stable composition if the total surfactant concentration is between 10 and 20% by weight.

Thus it is possible in the invention to formulate a replenishment composition that provides, in a single package, suitable replenishment for maintaining a working solution as described in US Patent Specification No.3,969,135 and yet which can be stored and shipped under con?ercial conditions. By saying that the composition is a homogeneous temperature stable corriposition we mean that it remains substantially homogeneous during the normal variations of temperature that are liable to be incurred during shipping and storage of the replenishment composition.By saying that it remains substantially homogeneous under these conditions we mean that preferably there is no significant phase separation during storage or, if there is any phase separation during storage, it is of a nature such that it is very easy to restore the composition to a homogeneous state prior to use.

The invention includes not only the replenishment composition but also methods of cleaning aluminium, as described in US Patent Specification No. 3,969,135, in which the cleaning solution is replenished with the onepackage replenisher of the invention, the rates of cleaning and replenishment being such that the concentrations of the active ingredients in the cleaning solution is maintained substantially constant. Preferably the concentration of each surfactant in the treatment solution is maintained at from 0.05 to 0.21 % by weight. It is preferred that the treatment solution, and therefore also the replenishment, contains fluoride and preferably the effective fluoride concentration in the working solution is maintained at from 0.001 to 0.01% by weight.

The polyalkylene glycol-hydrocarbon surfactant may be represented by the following general formula R(OR')nOH wherein R is an alkyl or alkylaryl group of 8-22 carbon atoms; R' is a divalent radical selected from ethyl, propyl and combinations thereof and n is an integer from 7 to 22. Commercially available surfactants believed to fall within the above general formula include Triton CF-1 0 available from the Rohm and Haas Co., Antarox LF-330, Antarox BL-330, and Igepal CA 630 from the CAF Corporation,Trycol LF-1 from Emery Industries, Inc. and Plurafac D-25 from BASF \1Klyandotte Corp.These surfactants contain both alkyl and alkylaryl R groups, ethoxy and propoxy R' groups with n values ranging from 8 to 1 6.

The polyalkylene glycol-abietic acid surfactant may be represented by the general formula A(R'O)nH wherein R' and n are as defined above and A is the abietic acid radical. Commercially available surfactants are Surfactant AR 1 50 supplied by Hercules, Inc. and Pegosperse 700-TO supplied by Glyco Chemicals, Inc. Both of these commerically available surfactants serve as source of an abietic acid ester containing approximately 14 to 16 moles of ethoxylation.

Although the surfactants preferably have the formulae given above optionally substituted derivatives of these may be used and can still be considered to be polyalkylene glycol-hydrocarbon and polyalkylene glycol-abietic acid surfactants respectively. Thus the final hydroxy group in either or both of these surfactants can be replaced by a chloride substituent, and alkyl or aryl substitutions may also be made. The resultant compounds can still properly be defined as polyalkylene glycolhydrocarbon or polyalkylene glycol-abietic acid surfactants.

In order that the replenishment composition is stable each class of surfactant should be present in an amount sufficient to provide a total surfactant concentration of substantially 10 to 20% by weight. Preferably the amount is between 10 and 20% but amounts outside this range can be tolerated provided they do not result in destabilisation of the composition. Preferably these surfactants are present in substantially equal proportions (e.g. in amounts by weight of from 2:1 to 1:2 and preferably in amounts of about 1:1 by weight) but different amounts can be used provided that there is always an effective amount of each of the surfactants present in the replenishment.

The replenishment preferably comprises fluoride which is preferably present in an amount of at least about 2% by weight, generally from about 2% to about 15% by weight. The fluoride may be provided by materials such as those recommended in US Patent Specification No.

3,969,135 but preferably it is provided as a simple fluoride, most preferably hydrofluoric acid.

The composition must contain mineral acid, often phosphoric acid and/or sulphuric acid. The amount of acid is preferably sufficient to provide an acidic pH in the replenishment composition of less than 0. When the mineral acid is phosphoric acid or sulphuric acid or a mixture thereof a concentration of 25 to 50% by weight is generally suitable.

The following is an example of the invention.

An acidic aqueous replenisher was prepared by mixing the following ingredients: Material Parts by Weight Water 40.48 Sulphuric acid 660Be (96 wt. %) 38.4 Trycol LF1 7.32 Surfactant AR-i 50 7.32 70% HF 6.48 100.00 The replenisher is stable for an extended period of time at 1200F and can be used as replenishment for the process of Example 1 of US Patent No. 3,969,135 operated using the fourth composition listed in Example 2 of that patent.

Claims (8)

1. A homogeneous, temperature stable, aqueous acidic replenishment composition comprising water, mineral acid and substantially 10 to 20% by weight of a mixture of polyalkylene glycolabietic acid surfactant and polyalkylene glycolhydrocarbon surfactant.

2. A composition according to claim 1 additionally containing fluoride.

3. A composition according to claim 2 in which the amount of mineral acid is sufficient to give a pH below 0 and the amount of fluoride is substantially 2 to 15% by weight.

4. A composition according to any preceding claim in which the mineral acid is selected from sulphuric acid and phosphoric acid.

5. A composition according to any preceding claim in which the concentration of mineral acid is from 25 to 50% by weight.

6. A composition according to any preceding claim in which the polyalkylene glycolhydrocarbon surfactant has the general formula: R(OR')nOH and the polyalkylene glycol-abietic acid surfactant has the general formula: A(R'O)H wherein R is an alkyl or alkylaryi group of 8-22 carbon atoms; R' is a divalent radical selected from ethylene, propylene and combinations thereof; each n is an integer from 7 to 22; and A is the abietic acid radical.

7. A composition according to any preceding claim in which the polyalkylene glycolhydrocarbon surfactant and the polyalkylene glycol-abietic acid surfactant are present in substantially equal proportions.

8. A method of cleaning aluminium surfaces comprising contacting the surface with a treatment solution comprising water, mineral acid, polyalkylene glycol-abietic acid surfactant and polyalkylene glycol-hydrocarbon surfactant and optionally fluoride, and during use maintaining the concentration of the active ingredients in the treatment solution substantially constant by replenishment of the solution by addition of a composition according to any preceding claim.