IE51595B1

IE51595B1 - Propellant-active carrier system for water-based paints

Info

Publication number: IE51595B1
Application number: IE2226/81A
Authority: IE
Original assignee: Ccl Ind Inc
Priority date: 1980-09-30
Filing date: 1981-09-24
Publication date: 1987-01-21
Also published as: CH648586A5; DE3138298A1; PT73751A; MX159291A; FR2500471B1; AU548700B2; AU7576781A; IT8124240A0; BR8106291A; NZ198482A; FR2500471A1; GR75009B; DE3138298C2; IT1139625B; BE890564A; PT73751B; ATA417581A; IE812226L; AT392076B; SE8105703L

Abstract

A single-phase propellant vehicle composition using dimethyl ether, water, water-soluble polar organic solvents, preferably mixtures of aliphatic alcohols and water-soluble polar organic flow-improving solvents, is proposed for use in water-based aerosol surface-coating compositions, in which a wide range of film-forming polymers may be present.

Description

The present invention relates to aerosol paint compositions.

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 U.K. Patent Specification No. 2,036,063, there is described a water-based aerosol paint formulation which satisfactorily produces a high gloss and excellentdurability paint film on a substrate surface. The compositions defined therein are restricted to a narrow range of emulsified film-forming polymers, along with broadly described propellants.

It has now surprisingly been found that water-soluble film-forming polymers may be formulated into water-based aerosol paint compositions by using a unique single phase composition of dimethyl ether, water and at least one water-soluble polar organic solvent. In accordance with the present invention, there is provided a water-based aerosol paint composition suitable for spray application from a pressurized container onto a substrate surface and air drying to a continuous film thereon, which comprises (a) 6 to 25% by weight of at least one water-soluble film-forming polymer dissolved in (b) 92 to 75% by weight of a single phase propellant-active carrier 3o composition, which composition comprises, to a total of 100% by weight of the single phase composition, (1) 20 to 75% by weight of a propellant which is dimethyl ether, (2) 10 to 50% by weight of water, and (3, 0.1 to 45% by weight of at least one water-soluble polar organic solvent.

The essential components of the single phase composition in which the water-soluble film-former is dissolved 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 an aerosol 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 cf 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 cne 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 the water-soluble film-forming polymer component cf the composition, 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 20 to 75% by weight of the propellant-active carrier composition, preferably 25 to 40% by weight, typically 40% by weight.

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

Another essential component of the propellant composition of the invention is water. This component is present in a concentration cf 10 to 5C% by weight, S159S preferably 20 to 35% by weight, typically 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 1 to 30% by weight, preferably 5 to 20% by weight, typically 15% by weight. i3 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 572°F (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 1 to 15% by weight, preferably 5 to 10% by weight, typically 6% by weight. The combination of the monohydric alcohol and coalescing solvent is present in an amount of 2 to 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 the film-forming polymer 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 water-soluble polar organic solvent to achieve coupling of the organic and aqueous phases to ensure a single-phase active carrier propellant composition in which the film-forming polymer is dissolved. 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 200 to 600 KPa at 20cC (70’F) and preferably 275 to 425 KPa.

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

The water-based aerosol paints of this invention comprise 6 to 25% by weight, preferably 12 to 20% by weight, of the film-forming polymers and 92 to 75% by weight, preferably 88 to 80% by weight of the single phase . propellant-active carrier composition and, optional components, such as, pigments, surfactants, stabilizers, antifoam agents and plasticizers, as discussed in more detail below.

The single phase propellant-active carrier composition is quite versatile and is effective to permit the spray application of a wide variety of water-soluble 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 formulations, 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-soluble polymer 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 43 monovinylidene compound, usually, styrene. Acrylic resins generally have molecular weights in the range of 100,000 to 1,000,000.

Alkyd resins are made by combining dibasic acids cr their anhydrides, usually phthalic anhydrid, 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 •j5 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 15% by weight of the total composition of the pigment may be used, preferably 5 to 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. The overall quantity of surfactant present in the composition should be sufficient to maintain solids in suspension and usually varies up to 3% by weight of the composition.

A pH stabilizer may also be present in the composition to provide an overall pH value greater than 7.2 and up to 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 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 counteract 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 2% by weight of the total composition may be used, preferably 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 2% by weight of the total composition, preferably 1% by weight.

The aerosol water-based paint compositions provided in accordance with this invention, therefore, generally have a pH of 7.2 to 10, preferably 7.4 to 7.9, and consist essentially of 6 to 25 wt.% of at least one water-soluble film-forming polymer (calculated as the non-volatile content thereof); 20 to 60 wt.% of dimethyl ether; 10 to 40 wt.% of water; 0.1 to 30 wt.% of at least one water-soluble polar organic solvent; 0 to 3 wt.% of at least one surfactant; 0 to 15 wt.% of at least one pigment; 0 to 1 wt.% of at least one pH stabilizer; 0 to 2 wt.% of at least one antifoam agent; and 0 to 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 1 to 20 wt.% of at least one aliphatic monohydric alcohol containing from 1 to 6 carbon atoms, and 1 to 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 15 to 30 minutes, and exhibits complete water resistance in an acceptable period of time, usually in 3 to 5 hours.

The invention is illustrated by the following Examples: Examples 1 and 2 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 - Fire orange fluorescent - Acrylic resin Component _wt. % 90-587 Resin(1) Water Isopropyl alcohol Butyl CELLOSOLVE(3) Fire orange pigment L475 NH4OH (cone.) TRITON(3> X 405(2) Dimethyl ether .0 12.7 15.0 4.0 11.7 0.2 1.3 0.1 40.0 Total 100.0 Notes: (1) An oil-modified acrylic resir. manufactured by Reichold Chemicals Limited (2) Rohm & Haas nonionic surfactant (3) Registered Trade Marks. 51S95 ΙΟ Example 2 - Blue - Alkyd resin Component wt.S Arolon 580(1) 27.0 Arolon 585 ^’ 10.2 Water 8.8 Isopropyl alcohol 7.7 Butyl Cellosolve 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) Oil-modified alkyd resins made by Ashland Oil.

In summary of this disclosure, the present invention, therefore, provides a novel water-based 2Q paint composition useful for spray application to substrate surfaces. Modifications are possible within the scope of this invention.

Claims

1. A water-based aerosol paint composition suitable for spray application from a pressurized container onto a substrate surface and air drying to a continuous film thereon, which comprises (a) 6 to 25% by weight of at least one water-soluble film-forming polymer dissolved in (b) 92 to 75% by weight of a single phase propellant-active carrier composition, which composition comprises, to a total of 100% by weight of the single phase composition, (1) 20 to 75% by weight of a propellant which is dimethyl ether, (2) 10 to 50% by weight of water, and (3) 0.1 to 45% by weight of at least one watersoluble polar organic solvent.

2. A composition as claimed in claim 1, in which component (3) comprises (a) 1 to 30% by weight of the total composition of at least one 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 (b) 1 to 15% by weight of the total composition of at least one watersoluble organic coalescing solvent.

3. A composition as claimed in claim 2, in which the monohydric alcohol is ethanol or propanol and the watersoluble coalescing solvent is a lower alkyl ether or ethylene or propylene glycol, diacetone alcohol, a ketone cr an ester alcohol.

4. A composition as claimed in any one of claims 1 to 3, in which the propellant-active carrier composition is present in an amount of 88 to 80 wt.% and the film-forming polymer is present in an amount from 12 to 20% by weight.

5. A composition as claimed in any one of claims 1 to 4, including at least one additional paint-forming component which is up to 15 wt.% of at least one pigment, up to 3 wt.% of at least one surfactant, up to 1 wt.% of at least one pH stabilizer, up to 2 wt.% of at least one antifoam agent and up to 2 wt.% of at least one plasticizer.

6. A composition as claimed in any one of claims 1 to 5, in which, based on the overall weight of the composition, dimethyl ether is present in an amount of 20 to 40% by weight, water is present in an amount of 20 to 35% by weight, monohydric alcohol is present in an amount of 5 to 20% by weight, and coalescing solvent is present in an amount cf 5 to 10% by weight.

7. A compositin as claimed in any one oi claims 1 to 6, in wh-ich the film-forming water soluble polymer is an acrylic resin, an alkyd, an epoxy ester or a polyvinyl copolymer.

8. A composition as claimed in claim 7, in which the 5 film-forming water-soluble polymer is an oil-modified alkyd resin.

9. A composition as claimed in any one of claims 1 to 8 having a pH of 7.4 to 7.9.

10. A water-based aerosol paint composition substantially 10 as hereinbefore described with reference to any one of the Examples.