GB2244493A - Non-flammable foaming aerosol cleaners - Google Patents

Abstract

A non-flammable aqueous aerosol foaming cleaner composition having a pH of 8 or below comprises polar solvent, non-polar solvent, foaming surfactant, and both hydrocarbon and chlorodifluoromethane propellants, the weight ratio of hydrocarbon propellant to chlorodifluoromethane propellant being less than 1:1.

Description

NON-FLAMMABLE FOAMING AEROSOL CLEANERS The present invention relates to foaming aerosol cleaners, and provides a non-flammable aqueous aerosol foaming cleaner composition having a pH of 8 or below and comprising polar solvent, non-polar solvent, foaming surfactant, and both hydrocarbon and chlorodifluo m methane propellants, the weight ratio of hydrocarbon propellant to chloroctfluoromethane propellant being less than 1:1. Chlorodifluoromethane propellant is also referred to herein as P22.

The cleaning composition according to the invention can include one or mDre other ingredients, selected for example from foam stabilizers (e.g. carboxy.methylcelluloses, especially those of medium density and medium molecular weight), inhibitors of corrosion of aerosol tinplate cans (e.g. sodium nitrite, sodium dihydrogen phosphate, sodium lauryl sarcosinate), bacterial inhibitors (e.g.

glutaraldehyde), and antistatic and bacteriocidal agents (e.g.

quarternary ammonium compounds, zwitterions etc.).

Water may be the sole polar solvent, but other such solvent is preferably present. Suitable polar solvents (in addition to water) for use in the invention include water-miscible alcohols e.g. isopropanol. Suitable non-polar solvents include hydrocarbons, e.g. kerosene. The preferred surfactants for use in compositions according to the invention are low surface tension surfactants, especially sulphosuccinates and sarcosinates. A preferred foam stabilizer for use in the invention is =rboxymethyl cellulose, e.g. the commercial material Blanose 7MD. Suitable hydrocarbon propellants are alkanes such as butane and propane and mixtures thereof - e.g. an n-biitane/propane/isobutane mixture; different alkane mixtures (for example of 30, 40, or 70 psig, etc.) can be used as desired.

A preferred range of compositions according to the invention is summarised in the following Table. The weight ratio of P22 to hydrocarbon propellant in all cases is over 1:1.

SABLE 1 Most Preferred Preferred Preferred Range Component Combined Range wt.% wt.% Range wt.% 3.5 - 5.0 up to 30 Polar solvent [e.g. 'PA, ) other alcohols) ) up to 1.0 - 4.0 up to 30 Non-polar solvent ) 30 [e.g. hydrocarbon) 1.0 up to 20 Low surface tension foaming surfactant 0.05 0 to 5 Antistatic agent [e.g.

quaternary; nonionic] 0.3 0 to 1 Foam stabilizer [e.g.

carboxymethyl cellulose] 0.1 0 to 1 Perfume 3.5 up to 20 P22 ) up to 0.1 - 3.0 up to 20 Hydrocarbon [preferably alkane) propellant ) 20 Balance 50 - 95 Water The aerosol foaming cleaner compOsitions according to the invention employ ozone friendly propellant and have excellent foaming characteristics to give a non-flannxfible/self- extinguishing foam. The conpositions can have excellent cleaning properties to give no smear and low residue on cleaned surfaces. The foaming action gives increased contact time for dissolving or reacting with dirt, and lifts dirt fram crevices to allow it to be transferred to a receiver, the dirt removal being enhanced by the mix of polar and non-polar solvents.

P22 when used alone tends to give only weak watery foams.

Foaming products using a P22/butane mixture have been proposed for various purposes (see Aerosol Age, Feb.1986, pages 32 to 34 and 59), but these all have a weight ratio of butane to P22 of 3:2, and the resulting foams can be ignited to give a selfsustaining flame. The present invention identifies formulations with propellant mixes giving excellent cleaning foam which is either non-flammable or self-extinguishing.

In this context "flammability" is defined not on the basis of ignition during discharge (BSMA Test methods 2, 5, 7), or according to EEC regulations ( > , 40% of propellants + solvents with Flash Point 1000C), but by the practical test (very strict) of applying a match to the foam during its collapse and recording if the gas flashed or showed self-propagating flame (collapse of the foam).

For comparison a gas mixture richer in butane than a P22 to Butane weight ratio of 94:6 will show sustained ignition (Chapter 14, Handbook of Aerosol Technology) so long as oxygen or air is not restricted.

The cleaning compOsitions according to the invention are suited for cleaning any "hard" surface - e.g. as cccputer cleaning products and flux removers for printed circuit boards, but can also be applied to soft surfaces such as upholstery, clothing etc.

The invention is illustrated by the following Examples, in which compositions A to L were prepared as set out in Table 2, and were then tested for foam character and flammability.

SEB;CE 2

RawMaterial/wt. X A 8 C D E F G H I J K L Isopropanol 3.7 3.7 3.7 3.7 3.7 3.7 4.8 4.8 4.8 4.8 4.8 4.8 Odorless kerosene 3.7 3.7 3.7 3.7 3.7 3.7 1.0 1.0 1.0 1.0 1.0 1.0 Lankropol K02(1) 0.9 0.9 0.9 0.9 0.9 0.9 - - - - Crodasinic sL30(2) - - - - - - 0.9 0.9 0.9 0.9 0.9 0.9 Empigen BAC - - - - - - 0.05 0.05 0.05 0.05 0.05 0.05 Cyanstat SN50(4) 0.05 0.05 0.05 0.05 0.05 0.05 - - - - - Perfume 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Dymel 22(5) 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 SHAP 40(63 - 0.5 1.0 2.0 3.5 5.3 - 0.5 1.0 2.0 3.5 5.3 Water + foam rtabiliser (7) (1) Sodium dioctyl sulpho succinate - (Lankro/Harcross Chemicals) (2) Sodium lauryl sarconisate - Croda Chemicals (3) proprietary Quaternary ammonium (antibacterial/antistat) - Marchon Chemicals (4) Proprietary Quaternary ammonium (antibacterial/antistat) - Ciba Geigy (5) Dymel 22 - chlorodifluoromethane from Dupont ltd.

(6) Butane/Propane blend - Shell (7) The water based foam stabiliser blend consists of: Function Deminwater 99.45 solvent Blanose 7MD(8) 0.30 foam stabiliser Sodium Nitrite 0.10 corrosion inhibitor (aerosol can) Lankropol K02(1) 0.10 wetting agent (dispersion of Blanose in water) Ucarcide 250(9) 0.05 preservative 100.00 (8) Medium density/MW Carboxymethyl cellulose - Hercules Inc.

(9) 507 > soln. Glutaraldehyde.

Foam Character/Flammability Tests a) Foam character was determined by spraying for 3 secs from a distance of 6 inches on to a vertical surface (metal) at 200C and observing the time for the foam to run by 1 cm. If the foam ran whilst spraying this was noted as instantaneous.

b) Flammability was determined by discharging foam (as above) on to a horizontal surface and bringing a strong ignition source (lighted match) into direct contact with the surface of the foam both immediately after spraying and after 30 seconds (total foam break was typically less than 90 seconds). This simulates flame or extreme static spark ignition.

Results are given in Table 3. Note all these products are non flammable according to BAMA or EEC guidelines. None of the products could be ignited by electrostatic spark (eg. gas lighter).

TABLE 3 Alkane Formulation P22 Foam character Foam run Flammability Comment ratio time (secs) 10 sec 30 sec *FCL300 creamy 10 .i # self sustaining A 0 watery 0 x x P22 alone B 1:7 creamy 4 x x non-flamm C 1:3.5 creamy 7 x x non-flamm D 2:3.5 creamy 10 x x non-flamm E 1:1 creamy 20 V V self sustaining F 3:2 creamy 16 # # self sustaining G ta IO watery 0 x x P22 alone H 1:7 creamy 3 x x I 1:3.5 creamy 6 x # not sustained J 2:3.5 creamy 11 x '/ not sustained K 1:1 creamy 25 # '/ self sustaining L 3::2 creamy 30 # # self sustaining * 100% butane propelled product.

The desirable and allowable proportions of propellants and non-aqeous solvents in compositions according to the invention depend: at least partially on the identities of the particular materials used. Thus the preferred maximum of 30 wt.% total non-aqueous solvent indicated in Table 1, although fairly broadly applicable, might be too high for non-flammability with certain solvents. For non-flammability it is best to choose solvents and propellants and/or to restrict the amounts used so that the composition flashpoint is over 1000C and/or so that the total propellant/non-aqueous solvent content is below 40 wt.%, e.g.below 30 wt.%. In our nost preferred compositions this total content is much lower under 20 wt.%, e.g. about 10 wt.%.

Claims (10)

CLAIMS:

1. A non-flammable aqueous aerosol foaming cleaner composition having a pH of 8 or below and ooniorising polar solvent, non-polar solvent, foaming surfactant, and both hydrocarbon and chlorodifluoromethane propellants, the weight ratio of hydrocarbon propellant to chlorodifluoramethane propellant being less than 1:1.

2. A composition according to claim 1 wherein the polar solvent consists of water.

3. A composition according to claim 1 containing by weight up to 30% of solvent other than water, up to 20% of surfactant, 0 to 1% of foam stabilizer, up to 20% or chloro difluormethane/hydrocarbon propellant, and from 50 to 95% of water.

4. A composition according to claim 3 containing by weight from 3.5 to 5% of polar solvent other than water, from 1 to 4% of non-polar solvent, about 1% of surfactant, about 0.3% of foam stabilizer, about 3.5 wt.% of chlorodif luoramethane, and up to 3 wt.% of hydrocarbon propellant, the balance being substantially all water.

5. A composition according to any preceding claim containing one or more additional ingredients selected from foam stabilizers, corrosion inhibitors, bacterial inhibitors, antistatic and bacteriocidal agents, perfumess, and preservatives.

6. A composition according to any preceding claim wherein the polar solvent comprises water and alcohol, e.g.

isopropanol.

7. A composition according to any preceding claim wherein the non-polar solvent camprises one or more hydrocarbons.

8. A composition according to any preceding claim wherein the surfactant is selected fram sulphosuccinates and sarcosinates.

9. A composition according to any preceding claim conta:alng foam stabilizer oamprising carboxymethyl cellulose.

10. A composition according to any preceding claim wherein the hydrocarbon propellant is selected from butane and propane.