AU663796B2 - Gelling compositions for stripping and cleaning - Google Patents

Description

AUSTRALIA

Patents Act 1990 6 6 COMPLETE SPECIFICATION For a Standard Patent

ORIGINAL

TO BE COMPLETED BY APPLICANT Name of Applicants: ctual Inventors:* Actual Inventors: ANTHONY MATHEW LONCAR, GREGORY DONALD DAVIES and THOMAS BROUGH

GREGORY

BROUGH

DONALD DAVIES and THOMAS 4 *4 *-i 4 4444 .4*4 4*44 Address for Service: WRAY ASSOCIATES, Primary Industry House, Terrace, Perth, Western Australia, 6000.

239 Adelaide Attorney code: WR Invention Title: "Gelling Compositions for Cleaning" Stripping and Details of Associated Patent Application: No: 35409/89 The following statement is a full description of this invention, including the best method of performing it known to me:- 1 'r1 Ir -2- GELLING COMPOSITIONS FOR STRIPPING AND CLEANING Technical Field THIS INVENTION relates to chemical compositions for use as paint, oil or grease removers, cleaning agents, and other related applications.

Background Art In many applications where chemicals are used to clean, strip or otherwise act S upon a surface, the effectiveness of the action of the chemicals is very much dependent upon contact between the chemicals and the surface.

In particular, with paint stripping compositions comprised of chlorinated hydrocarbons or aqueous caustic solutions, the use of these compositions is effective only on substantially horizontal surfaces because of the low viscosity.

Add.!tionally, any such solution is effective only for the duration that the solvent component remains unevaporated on the surface being acted upon. When S. evapoiration occurs, a further application of the paint stripping composition is o necessary to effectively continue the paint stripping operation. Further, due to o 00 the low viscosity of these compositions, it is difficult to confine their action to a particular portion of a surface which is required to be stripped or cleaned.

West German Patent Specification Number 3338027 discloses the use of potato flour as a thickening agent for a paint stripping composition. The disadvantage of this type of thickened paint stripping composition, although being an improvement over non thickened aqueous caustic compositions, is that it is still subject to running on substantially vertical surfaces and is still subject to loss of effectiveness due to evaporation of the solvent from the 7 N composition, the thickening agent not .ubstantially slowing the rate of -3evaporation compared with similar aqueous caustic paint strippers which are not thickened.

It is an object of the present invention to provide a chemical composition which exhibits improved adhesive and solvent retention properties for use in stripping and cleaning applications.

According to one aspect of the present invention there is provided a stripping and cleaning composition of gel-like consistency comprising a caustic aikaline solution and a substantially aqueous-insoluble aqueous absorbent synthetic polymeric substance in the form of an acrylamide polymer, the composition being formed by absorption of the caustic alkaline solution by the synthetic S polymeric substance. One suitable polymeric substance is that marketed in SAustralia under the trade mark AGROSOKE, by Chemical Discoveries S.A..

@0 Suitable synthetic polymeric substances other than AGROSOKE include: a cross-linked acrylamide or methacrylamide polymer.

a cross-linked copolymer of acrylamide or methacrylamide and acrylic acid or methacrylic acid.

0 0 S* a cross-linked acrylamide or methacrylamide polymer and a copolymer of acrylamide and acrylic acid.

AGROSOKE is a granular composition usually sold as anhydrous spheres having an average diameter of approximately 3-4mm. AGROSOKE is believed to comprise a polymer of acrylamide cross-linked with methylene bisacrylamide or a co-polymer of acrylamide and acrylic acid (or acrylate) cross- "inked with methylene bis-acrylamide, and a co-polymer of acrylamide and acrylic acid (or acrylate), and such as disclosed in US Specification No 4,579,578 and Canadian Specification No. 1200943 which are directed to polymers of this type.

The acrylamide, and acrylamide/acrylate polymers are water soluble and are known as thickening agents. However on incorporating a suitable cross-linking component these polymers become insoluble in water yet are capable of absorbing water to form an aqueously insoluble gel. AGROSOKE is such a polymer. Depending on the degree of cross-linking, the cross-linked polymers may absorb up to 30 times or more their volume in water or aqueous media.

The proprietary substance AGROSOKE has been found to exhibit relative stability, with respect to decomposition, at alkaline pH.

The known application for AGROSOKE is for absorbing water for agricultural and horticultural use as a growing medium as described fundamentally in US4579578.

The cross-linked polymer and cross-linked copolymer are as substantially described in Canadian Patent Specification Number 1200943. The preferred cross-linking agent of said cross-linked polymers is methylenebisacrylamide which is present in proportion of up to 10% by weight of the other monomer component(s) of the polymer.

*0 The cross-linked acrylamide or methacrylamide polymer which further includes a copolymer of acrylamide and acrylic acid, with the weight ratio of acrylamide 00* and acrylic acid in this copolymer preferably being 7:3, is as substantially described in US4579578.

The preferred cross-linking agent of this cross- linked acrylamide or 'inethacrylamide polymer is methylenebisacrylamide which is present in the 1 cross-linked polymer in proportion of up to 10% by weight. US4579578 describes an ideal range for weight of methylene bis-acrylamide as lying between 1% and with the lower levels of methylene bis-acrylamide resulting in cross-linked polymers which tend to be stickier. As the weight of methylene bis-acrylamide increases toward 10%, the cross-linked polymer tends to become less water absorbent.

Preferably said methylene bis-acrylamide is present in the cross-linked polymer in proportion of up to 5% by weight.

Preferably said methylene bis-acrylamide is present in the cross-linked polymer in proportion of up to 3% by weight.

The uncross-linked co-polymer included with this synthetic polymeric substance, being water soluble, acts as a binder to give improved adhesion.

Such a binder may be employed with any of the insoluble cross-linked polymers. The example of a binder given in US4579578 is described as a 70/30 acrylamide/acrylic acid polymer.

S. Preferably said synthetic polymeric substance is divided into a plurality of particles.

Preferably the particle size of said plurality of particles is between 50 and 200 microns.

Preferably the alkaline component of said aqueous alkaline solution is one of sodium hydroxide or potassium hydroxide.

Preferably said chemical composition further incorporates a component a selected from the following:- -6a compound containing an ammonium group a compound containing an amine group an organic solvent a mixture of the above Preferably said organic solvent is one of methylene chloride, acetone or methyl ethyl ketone.

Preferably said compound is one of urea or an ammonium compound such as ammonium nitrate.

6*

S

Preferably the quantity of said organic solvent used is up to 20% by volume.

Preferably the quantity of said compound used is up to 25% by weight of the weight of said alkaline component.

Modes for Carrying Out the Invention The invention will be better understood by reference to the following specific examples: Example 1 a Thirty grams of AGROSOKE polymer granules ground to a powder of particle size 100 to 125 microns were slowly added to a hot solution of eighty grams of sodium hydroxide dissolved in one litre of water, whilst stirring.

-7- The mixture was stirred thoroughly every ten minutes to ensure that the polymer remained evenly dispersed within the solution. Absorption of the solution was complete in one hour.

During the absorption of the solution, and afterwards, the gel released ammonia in small quantities. This is thought to improve its properties as a paint stripper, broadening its range of application to different types of paints, when compared with caustic soda paint strippers. The ammonia is believed to be formed by slow attack of hydroxide ions methacrylamide and acrylamide groups within the polymer. The attack is not believed to be significant enough to break down the polymer and destroy its gelling properties, but is significant enough to enhance the paint and grease stripping properties of the composition.

The resulting chemical composition was found to have the following attributes:it spread easily on a surface to be stripped or cleaned and exhibited good adhesive properties in so far as that it did not run on or detach from veitical, overhead, or substantially inclined surfaces; it exhibited an initial delayed acting effect which increased the handling safety; *e S it exhibited improved solvent retaining characteristics, when compared with non-polymeric thickened aqueous alkaline stripping and cleaning compositions or solvent based strippers or cleaners, which resulted in an extension of the time that the gel remained effective when in contact with the surface; if the composition dried out due to being employed in extremes of temperature, low humidity or over a long period of time, it was reactivated simply by wetting, whereupon it continued to operate.

The chemical composition was found to be particularly suited for use in difficult applications such as the removal of graffiti from porous surfaces.

The effectiveness of the composition in difficult applications was improved further by the addition of 20g of a compound containing ammonium or amine groups such as urea or ammonium nitrate. These were added to the composition, prior to application to a surface, in crystalline or aqueous form. It is believed that the resultant reaction with the alkali releases ammonia into the aqueous medium within the gel which improves the effectiveness of the gel. A suitable amount to add was found to be approximately 25% by weight of the weight of the caustic alkali used in the 00b@ composition.

•oe• Removal of certain coatings from surfaces, such as polyurethane paints was found to be aided by the addition of an organic solvent such as methylene chloride, acetone, or methyl ethyl ketone to the gel, in amount of up to 20% by volume.

Example 2 o The second example of the invention is directed toward a chemical composition for stripping paints and grease from surfaces in environments of high relative humidity or of low evapotranspiration. This example is produced in substantially the same manner as the first example except that the thirty grams of AGROSOKE polymer granules were ground to a smaller powder of a particle Ssize of approximately 50 to 75 microns. The resulting chemical composition was faster acting in its stripping and cleaning properties, but its water retention properties were diminished when compared with the first example; hence its suitability for indoor applications, or high relative humidity applications.

In further embodiments, organic solvents such as acetone or methyl ethyl ketone are utilised instead of methylene chloride depending on the application.

It should be appreciated that the scope of the present invention is not limited to the particular embodiments described herein, and that the quantities of components of the chemical composition can be varied, and powder size can be varied.

s e S* 0 55 0 ft

Claims (23)

1. A stripping and cleaning composition of gel-like consistency comprising a caustic alkaline solution and a substantially aqueous-insoluble aqueous absorbent synthetic polymeric substance in the form of an acrylamide polymer, said composition formed by absorption of the caustic alkaline solution by the synthetic polymeric substance.

2. A composition as claimed in claim 1 wherein said synthetic polymeric substance comprises a cross-linked acrylamide polymer.

3. A composition as claimed in claim 1 wherein said synthetic polymeric substance comprises a cross-linked methacrylamide polymer.

4. A composition as claimed in claim 1 wherein said synthetic polymeric substance comprises a cross-linked co-polymer of acrylamide and acrylic acid.

5. A composition as claimed in claim 1 wherein said synthetic polymeric sibstance comprises a cross-linked co-polymer of methacrylamide and acrylic acid.

6. A composition as claimed in claim 4 or claim 5 wherein said acrylic acid constituent comprises approximately 30% of the weight of the cross-linked co- polymer.

7. A composition as claimed in claim 1 wherein said synthetic polymeric substance comprises a cross-linked co-polymer of methacrylamide and methacrylic acid.

8. A composition as claimed in claim 1 wherein said synthetic polymeric substance comprises a cross-linked co-polymer of acrylamide and methacrylic acid. .1 -11

9. A composition as claimed in claim 7 or claim 8 wherein said methacrylic acid constituent comprises approximately 30% of the weight of said cross-linked co-polymer.

A composition as claimed in any one of the preceding claims wherein said synthetic polymeric substance is cross-linked with methylene bis-acrylamide.

11. A composition as claimed in claim 10 wherein said synthetic polymeric substance is cross-linked with up to 10% by weight of methylene bis-acrylamide.

12. A composition as claimed in claim 10 wherein said synthetic polymeric substance is cross-linKed with up to 5% by weight of methylene bis-acrylamide. 10

13. A composition as claimed in claim 10 wherein said synthetic polymeric substance is cross-linked with up to 3% by weight of methylene bis-acrylamide.

14. A composition as claimed in any one of the preceding claims wherein said synthetic polymeric substance has a dried granular particle size lying between S.. fifty microns and two hundred microns.

15 15. A composition as claimed in any one of the preceding claims also S* comprising a binder, said binder being a water soluble compound adapted to thicken and impart adhesive properties to said composition.

16. A composition as claimed in claim 15, wherein said binder is a water soluble polymeric substance.

17. A composition as claimed in claim 16 wherein said water soluble polymeric substance comprises a water soluble co-polymer of acrylamide and acrylic acid.

18. A composition as claimed in claim 16 wherein said water soluble Sco-polymer comprises 30% acrylic acid by weight. -12-

19. A composition as claimed in any one of the preceding claims which further includes up to 0.5 parts by weight of a compound containing amine or ammonium groups.

A composition as claimed in claim 19 wherein said compound is urea or ammonium nitrate.

21. A composition as claimed in any one of the preceding claims wherein said gel is formed by reacting between two and four parts by weight of a solid caustic alkali dissolved in between twenty and forty parts of water to form said aqueous solution, with one part by weight of said synthetic polymeric substance. 0S

22. A stripping and cleaning composition based on an aqueously insoluble and aqueosly absorbent polymeric substance, substantially as described herein.

23. A stripping and cleaning composition comprising an aqueously insoluble 0@*S gel formed by absorbing an aqueous caustic alkaline solution in a synthetic polymeric substance substantially as herein defined. *0 Anthony Mathew LONCAR. Gregory Donald DAVIES Thomas BROUGH Applicant Ot 0 Dated this TWENTY FIFTH day of AUGUST 1995. Wray Associates Perth, Western Australia Patent Attorneys for the Applicant ABSTRACT A chemical composition for stripp:ng and cleaning surfaces of grease, paint and the like. The chemical composition com- prising a synthetic water absorbant and swellable polymeric substance for absort'ing a solution of a stripping and cleaning agent The synthetic polymeric substance may be a product marketed in Australia under the trade mark "AG ROSOKE", a crosslinked acrylamide or methacrylamide polymer, a crosslinked acrylamide or methacrylamide polymer and a copolymer of acrylamide and acrylic acid, or a crosslinked copolymer of acrylamide or methacrylamide and acrylic acid or methacrylic acid. The stripping and cleaning agent is an aqueous solution of a caustic alkali such as sudiurij hydroxide which may be optionally enhanced by ad- ding components such as ammonium compounds, compounds containing amine groups and organic solvents at the appropriate time depending upon; the intented application. 0 *too 0 0* 0 0 000 0SO, t0 Of r