GB2085466A - Propellant-active carrier system for water-based paints - Google Patents

Abstract

A single phase liquid propellant- active carrier composition comprises, to a total of 100% by weight, (a) 20 to 75% by weight of a propellant comprising dimethyl ether and from 0 to 50% by weight of the dimethyl ether of another liquid propellant; (b) 10 to 50% by weight of water; and (c) 0.1 to 45% by weight of at least one polar water-soluble organic solvent; the composition, together with any gaseous propellant present, exerting a vapour pressure within the pressurized container in the range of 30 to 85 psig at 70 DEG F. A water-based aerosol paint composition comprises (a) 6 to 25% by weight of at least one water-dilutable film-forming polymer and (b) 92 to 75% by weight of such a carrier composition.

Description

SPECIFICATION Propellant-active carrier system for water-based paints The present invention relates to aerosol paint compositions, and in particular to a novel propellant-active carrier system therefor.

Aerosol paint compositions are well known but have used volatile organic solvents as the carrier for the film-forming polymer. Toxicity and flammability problems arise from the use of such organic solvents and governmental regulatory authorities are moving towards severe restrictions on the use of organic solvents in such compositions.

In prior United States patent application Serial No. 097,152 filed November 23, 1979, the disclosure of which is incorporated herein by reference, (British Pat. App. 7939434), there is described a water-based aerosol paint formulation which satisfactorily produces a high gloss and excellent durability paint film on a substrate surface. The compositions defined therein are restricted to a narrow range of film-forming polymers.

It has now surprisingly been found that a novel single phase propellant-active carrier composition can be utilized to form satisfactory spray-applied films based on a wide variety of water-dilutable film-forming polymers, which may be in solution form or emulsified form.

The novel propellant composition of the invention consists essentially of: (a) about 20 to about 75% by weight of a propellant comprising dimethyl ether and from 0 to about 50% by weight of the dimethyl ether of another liquid propellant; (b) about 10 to about 50% by weight of water; (c) about 0. 1 to about 45% by weight of at least one water-soluble polar organic solvent.

The proportions of the components total 100% and are sufficient to provide a single phase. The composition, together with auxiliary gaseous propellants, if present, exerts a vapor pressure in a pressurized aerosol dispensing container in the range of about 30 to about 85 psig at about 20"C (70oF).

In a preferred embodiment of the invention, the novel propellant composition consists essentially of: (a) about 20 to about 75% by weight of dimethyl ether; (b) about 10 to about 50% by weight of water; (c) about 1 to about 30% by weight of at least one aliphatic monohydric alcohol of the formula: R-OH wherein R is an unsubstituted straight or branched chain alkyl group containing from 1 to 6 carbon atoms; and (d) about 1 to about 15% by weight of at least one water-soluble organic coalescing solvent.

The proportions of the components total 100% and are sufficient to provide a single phase.

While the present invention is primarily directed to the provision of aerosol paint compositions, nevertheless the propellant-active carrier composition may be used for the spray dispensing of a variety of other active components, such as, in hair sprays and deodorants.

The essential components of the propellant composition of this invention are dimethyl ether, water, and at least one water-soluble polar organic solvent. Dimethyl ether is a colorless, odorless, stable molar liquid with a boiling point of - 25"C and a vapor pressure of 4.2 bar at 20"C.

It has been previously suggested to use this liquid as a propellant. U.S. Patent No.

1,800,156 discloses the use of dimethyl ether alone as the propellant for a large variety of materials and paints are mentioned. U.S. Patent No. 3,207,386 discloses the utilization of a combination of dimethyl ether and water as a propellant for a wide variety of products including paints, the proportions being chosen to provide a homogeneous solution of the dimethyl ether and water as the propellant and this restriction results in a composition consisting of 5 to 35% by weight of dimethyl ether and 95 to 65% by weight of water. No other solvent or propellant components are used in this prior art composition.

In the present invention, the dimethyl ether is used in a combination with water and at least one water-soluble polar organic solvent, preferably a mixture of an alcohol and a water-soluble organic coalescing solvent, to provide a single phase propellant-active carrier composition for a water-dilutable film-forming polymer which is in aqueous solution or aqueous emulsion form, and hence the present invention involves quite a different application of the dimethyl ether in different proportions for a different purpose.

The dimethyl ether constitutes about 20 to about 75% by weight of the propellant-active carrier composition, preferably about 25 to about 40% by weight, typically about 40% by weight. Although the presence of conventional liquid propellants and other organic solvents, such as, aliphatic hydrocarbons and fluorinated hydrocarbons, often introduces instability to the system and hence dimethyl ether is preferred to be the sole propellant, under some circumstances there may be present in the composition up to about 50% by weight of the dimethyl ether of another liquid propellant.

A gaseous phase propellant, such as, nitrogen, carbon dioxide or nitrous oxide, may be used to enhance the propellant effect of the dimethyl ether or combination of dimethyl ether and other liquid propellant.

Another essential component of the propellant composition of the invention is water. This component is present in a concentration of about 10 to about 50% by weight, preferably about 20 to about 35% by weight, typically about 30% by weight.

In a preferred embodiment of the invention, a water-soluble lower aliphatic monohydric alcohol also is used in the composition. The monohydric alcohols used in this invention are those having the formula: R-OH wherein R is an unsubstituted straight or branched chain alkyl group containing from 1 to 6 carbon atoms. Examples of suitable monohydric alcohols are methanol, ethanol, n-propanol, iso-propanol and n-butanol, preferably ethanol or iso-propanol.

The concentration of the monohydric alcohol used in the compositions of this invention may vary widely from about 1 to about 30% by weight, preferably about 5 to about 20% by weight, typically about 15% by weight.

In a preferred embodiment of the invention, a water-soluble organic coalescing solvent is present along with the alcohol. A coalescing organic solvent is one which assists in film formation and which acts as an agent to render the polymer water-soluble.

The coalescing solvent may be any water-soluble polar organic solvent. Such materials include glycol ethers, esters, ketones and certain modified alcohols and may have a boiling point in the range of about 365 to about 572of. (about 185 to about 300"C). Suitable solvents include lower monoalkyl ethers of ethylene or propylene glycol, such as, propylene glycol methyl ether and propylene glycol methyl ethyl ether, diacetone alcohol and ester alcohols.

The coalescing solvent is present in an amount of from about 1 to about 15% by weight, preferably about 5 to about 10% by weight, typically about 6% by weight. The combination of the monohydric alcohol and coalescing solvent is present in an amount of about 2 to about 30% by weight and, in combination with the chosen proportions of dimethyl ether and water forms a single phase composition which is suitable for dissolving or suspending the active components to be dispensed.

In many instances, both an alcohol and a coalescing solvent are required. However, certain resins providing the film-forming component of the composition may be utilized when one or the other of these components is absent.

In the broadest aspect of the invention, therefore, the composition contains at least one watersoluble polar organic solvent to achieve coupling of the organic and aqueous phases to ensure a single-phase active carrier propellant composition. The concentration of the at least one polar organic solvent may vary widely, from about 0.1 to about 45% by weight.

The propellant-active carrier composition of the invention exerts a vapor pressure when packaged in a pressurized container sufficient to effect dispensing of the contents of the container. Generally, the vapor pressure is in the range of about 30 to about 85 psig at 20"C (70"F) and preferably about 40 to about 60 psig.

The dimethyl ether constitutes the main propellant component of the composition. The water provides the primary solvent and/or suspension phase for the active components, which include a film-forming polymer in the case of an aerosol paint. The water-soluble organic solvents mainly act as solvents for the propellant and the water, so that there results a substantially single phase mixture of components, which resists separation into separate liquid phases on standing. A single phase propellant-active carrier composition enables active components to be readily and efficiently dispensed from the aerosol container.

The propellant-active carrier composition of this invention has particular utility in the provision of aerosol water-based paint compositions. Such compositions comprise the single-phase propellant-active carrier composition and a filmforming polymer dissolved and/or suspended therein. Pigments also may be included to impart pigmentation to the sprayed film.

Such water-based aerosol paints generally comprise about 6 to about 25% by weight, preferably about 1 2 to about 20% by weight, of the film-forming polymers and about 92 to about 75% by weight, preferably about 88 to about 80% by weight, of propellant-active carrier and, optional components, such as, pigments, surfactants, stabilizers, antifoam agents and plasticizers, as discussed in more detail below.

The propellant-active carrier composition is quite versatile and is effective to permit the spray application of a wide variety of film-forming polymers onto a substrate surface to form a continuous film of excellent durability, including high flexibility retention. Depending on the nature of the polymer and the other components of the formulation, the films may be of high gloss, medium gloss, low gloss or flat.

Aerosol compositions formulated using the propellant-active carrier system of the composition are preferably substantially non-flammable, as tested according to standard flammability tests for aerosols. For example, the spray blows out a candle.

The film-forming polymer may be any water-dilutable polymer, including water-soluble polymers and water-dilutable emulsified polymers, which is capable of spray application to form a continuous film on a substrate surface. Many classes of polymer may be employed, including acrylic resins, alkyds, epoxy esters and polyvinyl copolymers.

Acrylic resins are thermoplastic or thermosetting polymers or copolymers of acrylic acid, methacrylic acid, esters of these acids, or acrylonitrile. Such resins may be modified by the presence of an aromatic monovinylidene compound, usually, styrene. Acrylic resins generally have molecular weights in the range of about 100,000 to about 1,000,000.

One example of an acrylic resin which is suitable for the formulation of a water-based aerosol paint composition in accordance with this invention is available from Rohm and Haas Inc., under the designation "W.L. 91". Another example is the resin available from Reichold Chemicals under the designation "90-587 Resin".

Alkyd resins are made by combining dibasic acids or their anhydrides, usually phthalic anhydride, with a polyhydric alcohol, such as glycerol. Alkyd resins often are modified by natural drying oils, such as, linseed oil, soya oil and safflower oil, in concentrations of 30 to 60% by weight.

Examples of alkyd resins which are suitable for the formulation of a water-based aerosol paint composition in accordance with this invention are available from Ashland Oil Inc., under the Trademark "AROLON" such as those designated "580" and "585".

Epoxy ester resins are resins containing a reactive epoxy group and derived from polyols and epoxy-group containing compounds. Other comonomers, such as, styrene may be copolymerized. These resins may be modified by natural drying oils in the same manner as alkyd resins.

An example of an epoxy resin which may be used is sold by Reichold Chemicals under the designation "38-690".

Polyvinyl copolymers are formed by copolymerizing vinyl chloride or vinyl acetate with copolymerizable monomers. One example of such a material suitable for the formulation of a water-based aerosol paint composition in accordance with this invention is available from B.F.

Goodrich Company under the designation "514H".

Mixtures of two or more resins or resin types may be used in the aerosol water-based paint formulations of this invention.

As mentioned above, an optional component which may be present in the paint composition is a pigment for pigmentation of the film formed on spraying the composition onto a substrate surface. When employed, up to about 15% by weight of the total composition of the pigment may be used, preferably about 5 to about 15% by weight of pigment.

When such pigment is present, the quantity of polymer used is generally towards the lower end of the range recited above. When such pigment is omitted and a clear film is required, then quantities of polymer towards the higher end of the range are used.

The presence of the pigment usually requires the presence of added surfactant to ensure suspension of the pigment in the liquid vehicle. Some surfactant may be present with the filmforming polymer, if the latter is in emulsion form, but the quantity involved usually is insufficient to effect suitable suspension of added pigment.

The overall quantity of surfactant present in the composition should be sufficient to maintain solids in suspension and usually varies up to about 3% by weight of the composition.

A pH stabilizer may also be present in the composition to provide an overall pH value greater than about 7.2 and up to about 10 to assist in inhibition of corrosion of the conventional pressurized metal container in which the paint composition is located for spray application.

Suitable pH stabilizer materials include morpholine, ammonia and triethanolamine. This component may be present in an amount of up to about 2% by weight of the total composition.

An antifoam agent may be included to alter the surface tension of the composition to permit ready release of dissolved gases upon spraying of the composition onto the substrate surface and to c6unteract the detergent effect of the surfactants present in the composition. A non-ionic blend of mineral oils and silica derivatives has been found to be suitable for use for defoaming.

When an antifoam agent is present, quantities up to about 2% by weight of the total composition may be used, preferably about 0.4% by weight.

Another component which may be added to the aerosol paint composition is a plasticizer to promote flexibility. Any one of a wide range of plasticizers may be used, for example, dioctyl phthalate. The plasticizer may be present in an amount of up to about 2% by weight of the total composition, preferably about 1 % by weight.

The aerosol water-based paint compositions provided in accordance with this invention, therefore, are characterized by a pH of about 7.2 to about 10, preferably about 7.4 to about 7.9, and consist essentially of: about 6 to about 25 wt.% of at least one water-dilutable film-forming polymer (calculated as the non-volatile content thereof), about 20 to about 60 wt.% of a propellant comprising dimethyl ether and from 0 to about 50 wt.% of the dimethyl ether of another liquid propellant, about 10 to about 40 wt.% of water, about 0.1 to about 30 wt.% of at least one water-soluble polar organic solvent, O to about 3 wt.% of at least one surfactant, O to about 1 5 wt.% of at least one pigment, O to about 1 wt.% of at least one pH stabilizer, O to about 2 wt.% of at least one antifoam agent, and O to about 2 wt.% of at least one plasticizer.

The dimethyl ether, water and polar solvent are present in the composition in proportions to provide a single phase propellant-active carrier system in which the remainder of the components are dissolved or suspended.

Preferably, the composition contains, as the polar organic solvent component: about 1 to about 20 wt.% of at least one aliphatic monohydric alcohol containing from 1 to 6 carbon atoms, and about 1 to about 10 wt.% of at least one water-soluble organic coalescing solvent.

The aerosol water-based paint composition, which is formulated as described above using the propellant-active carrier system of the invention, may be sprayed onto a substrate surface without foaming occurring and the pigmented or unpigmented continuous film touch dries rapidly, usually in about 1 5 to 30 minutes, and exhibits complete water resistance in an acceptable period of time, usually in about 3 to 5 hours.

The invention is illustrated by the following Examples: Examples 1 to 14 A number of aerosol water-based paint formulations were prepared using various film-forming polymers and pigments and packaged in aerosol cans. The films were sprayed onto substrate surfaces. In each case, a continuous film was formed which was dry to the touch in 30 minutes, exhibited water resistance within 3 hours of application and had a salt spray resistance (ASTM test B117) of more than 50 hours.

The following are the formulations: Example 1-Red oxide primer-Mixed acrylic-epoxy resin Component wt.% WL91 Resin t1) 3.6 38-690 Resin (2) 14.5 Water 13.25 Isopropyl alcohol 15.0 Butylcellosolve 4.0 Texanol 0.7 Red Oxide pigment 5.0 Driers-Mn 6%, Co 6% 0.25 L47 5(2) 0.2 Triethanolamine 1.0 Dioctyl phthalate 0.5 Or41 2(4, 2.0 Dimethyl ether 40.0 Total 100.0 Notes: (1) Acrylic resin made by Rohm and Haas; (2) Epoxy resin made by Reichold Chemicals; (3) Defoamer-Dow Chemicals; (4) Silica flattening agent.

Example 2-Blue-Acrylic resin Component wt.% WL91 Resin 22.0 Water 10.0 Isopropyl alcohol 15.0 Butylcellosolve 4.5 Texanol 0.7 White pigment 2.3 Blue pigment 4.6 L475 0.2 5% NH4OH 0.2 Dioctyl phthalate 0.2 Dimethyl ether 40.0 Total 100.0 Examples 3 to 7 Formulations similar to Example 2 were prepared using WL91 as the resin with differing pigments, as follows:: Example 3 - White Example 4 - Red Example 5 - Green Example 6 - Black Example 7 - Orange Example 8-Flat black-Acrylic resin Component wt.% WL91 Resin 21.8 Water 9.5 Isopropyl alcohol 15.0 Butylcellosolve 4.5 Texanol 0.7 Black pigment 5.0 L475 0.4 5% NH4OH 0.5 Dioctyl phthalate 0.5 OK412 2.0 Triton X-45"' 0.1 Dimethyl ether 40.0 Total 100.0 Note: (1) Rohm a Haas non-ionic surfactant Example 9-Fire orange fluorescent-Acrylic resin Component wt.% 90-587 Resin (1) 15.0 Water 12.7 Isopropyl alcohol 15.0 Butylcellosolve 4.0 Fire orange pigment 11.7 L475 0.2 NH4OH (conc.) 1.3 Triton X 405(2) 0.1 Dimethyl ether 40.0 Tonal 100.0 Notes: (1) Reichold Chemicals acrylic resin; (2) Rohm 8 Haas non ironic surfactant.

Example 10-Red oxide primer-Alkyd-Acrylic resin mixture Component wt.% WL91 Resin 18.00 Arolon 585 i 5.75 Water 15.03 Isopropyl alcohol 1 5.00 Butylcellosolve 4.50 Texanol 0.70 Red oxide pigment 8.00 L475 0.40 5% NH4OH 0.02 Dioctyl phthalate 0.50 OK412 2.00 Triton X100 0.10 Dimethyl ether 30.00 Total 100.00 Note: (1) Ashland Oil alkyd resin Example 1 1-Blue-Alkyd resin Component wt.% Arolon 580 (') 27.0 Arolon 585 (2) 10.2 Water 8.8 Isopropyl alcohol 7.7 Butylcellosolve 2.3 Blue pigment 2.1 White pigment 1.1 Drier 0.3 L475 0.2 5% NH4OH 0.1 Triton X100 0.3 Dimethyl ether 40.0 Total 100.0 Note: (1) and (2) Alkyd resins made by Ashland Oil Example 12-Red Oxide primer-Epoxy resin In the formulation of Example 1, the WL91 resin was replaced wholly by an increased amount of 38-690 resin to provide 18.1 wt.% of such resin in the resulting formulation.

Example l3cIear-PVC resin Component wt.% 415H Resin1 25.0 Water 24.7 Isopropyl alcohol 15.0 Butylcellosolve 5.0 L475 0.2 5% Ammonia 0.1 Dimethyl ether 30.0 Total 100.0 Note: (1) Carboxy modified polyvinyl chloride terpolymer made by B.F. Goodrich.

Example 14 Component wt.% Styrenated epoxy ester") 13.0 Water 31.0 White tinter < 2) 1 3.5 Driers (Cu naphthenate 6%, Mn naphthenate 6%) 0.2 Active 8 0.1 Concentrated ammonia 1.0 Byk 020 (defoamer) 0.2 Byk 351 (flow agent) 1.0 Dimethyl ether 40.0 Total 100.00 Notes: (1) 453V8 by C.P.V.---comprises 70% solids and 30% Butylcellosolve (2) Tinter comprises: Styrenated epoxy ester 23.5 Concentrated ammonia 1.5 Water 15.0 TiO2 60.0 100.0 In summary of this disclosure, the present invention, therefore, provides a novel propellantactive carrier composition useful for the spray application of water-based paints to substrate surfaces. Modifications are possible within the scope of this invention.

Claims (23)

1. A single phase liquid propellant-active carrier composition suitable for the spray application of an active ingredient from a pressurized container onto a substrate surface, comprising, to a total of 100% by weight, (a) 20 to 75% by weight of a propellant comprising dimethyl ether and from 0 to 50% by weight of the dimethyl ether of another liquid propellant; (b) 10 to 50% by weight of water; and (c) 0.1 to 45% by weight of at least one polar water-soluble organic solvent; the composition, together with any gaseous propellant present, exerting a vapor pressure within the pressurized container in the range of 30 to 85 psig at 70"F.

2. A composition as claimed in claim 1, in which the polar organic solvent comprises at least one aliphatic monohydric alcohol of the formula: R-OH in which R is an unsubstituted straight or branched chain alkyl group containing from 1 to 6 carbon atoms.

3. A composition as claimed in claim 1, in which the polar organic solvent is a lower monoalkyl ester of ethylene or propylene glycol, diacetone alcohol, a ketone or an ester alcohol.

4. A composition as claimed in claim 1, in which the polar organic solvent comprises a mixture of at least one aliphatic monohydric alcohol of the formula: R-OH in which R is an unsubstituted straight or branched chain alkyl group containing from 1 to 6 carbon atoms and a different water-soluble polar organic solvent.

5. A composition as claimed in claim 1 in which the polar organic solvent comprises 1 to 30% by weight of the total composition of at least one aliphatic monohydric alcohol of the formula: R-OH wherein R is an unsubstituted straight or branched chain alkyl group containing from 1 to 6 carbon atoms, and 1 to 15% by weight of the total composition of at least one water-soluble polar organic coalescing solvent.

6. A composition as claimed in claim 5, in which the monohydric alcohol is ethanol or isopropanol.

7. A composition as claimed in claim 5 or 6, in which the coalescing solvent is a lower monoalkyl ester of ethylene or propylene glycol, diacetone alcohol or an ester alcohol.

8. A single phase liquid propellant-active carrier composition substantially as hereinbefore described with reference to any one of the Examples.

9. A water-based aerosol paint composition suitable for spray application from a pressurized container to a substrate surface and air drying to a continuous film thereon, comprising: (a) 6 to 25% by weight of at least one water-dilutable film-forming polymer, and (b) 92 to 75% by weight of a propellant-active carrier composition as claimed in any one of claims 1 to 8.

10. A composition as claimed in claim 9, in which the film-forming polymer is present in an amount of from 1 2 to 20% by weight and the propellant-active carrier composition is present in an amount of 88 to 80% by weight.

11. A composition as claimed in claim 9 which has a pH of 7.2 to 10 and which consists essentially of (a) 6 to 25 wt.% of at least one water-dilutable film-forming polymer; (b) 20 to 60 wt.% of a propellant comprising dimethyl ether and from 0 to 50% by weight of the dimethyl ether of another liquid propellant; (c) 10 to 40 wt.% of water; (d) 0.1 to 30 wt.% of at least one water-soluble polar organic solvent; (e) O to 3 wt.% of at least one surfactant; (f) O to 1 5 wt.% of at least one pigment; (g) O to 1 wt.% of at least one pH stabilizer; (h) O to 2 wt.% of at least one antifoam agent; and (i) O to 2 wt.% of at least one plasticizer, the propellant, water and polar organic agent being present in proportions to provide a single phase propellant-active carrier composition in which the remainder of the components of the composition are dissolved or suspended, the composition, together with any gaseous propellant present, exerting a vapor pressure within the pressurized container in the range of 30 to 85 psig at 70"F.

1 2. A composition as claimed in claim 11, in which component (c) comprises 1 to 20 wt.% of the total composition of at least one aliphatic monohydric alcohol of the formula: R-OH wherein R is an unsubstituted straight or branched chain alkyl group containing 1 to 6 carbon atoms and 1 to 1 Owt.% of the total composition of at least one water-soluble polar organic coalescing solvent.

1 3. A composition as claimed in claim 12, in which the monohydric alcohol is present in an amount of 5 to 20% by weight.

14. A composition as claimed in claim 1 2 or 13, in which the alcohol is ethanol or isopropanol.

1 5. A composition as claimed in any one of claims 1 2 to 14, in which the coalescing solvent is present in an amount of 5 to 10% by weight.

1 6. A composition as claimed in any one of claims 11 to 15, in which the dimethyl ether is present in an amount of 20 to 40% by weight.

1 7. A composition as claimed in any one of claims 11 to 16, in which the water is present in an amount of 20 to 35% by weight.

18. A composition as claimed in any one of claims 11 to 17, wherein the pH is 7.4 to 7.9.

1 9. A composition as claimed in any one of claims 11 to 18, in which the continuous film is pigmented and the at least one pigment is present in the composition in an amount of 5 to 1 5 wt.%.

20. A composition as claimed in any one of claims 9 to 19, in which the film-forming polymer is a water-soluble resin.

21. A composition as claimed in any one of claims 9 to 19, in which the film-forming polymer is a water-dilutable emulsified resin.

22. A composition as claimed in any one of claims 9 to 21, in which the film-forming polymer is an acrylic resin, an alkyd, an epoxy ester or a polyvinyl copolymer.

23. A water-based aerosol paint composition substantially as hereinbefore described with reference to any one of the Examples.