GB2406097A - A water-based polymer coating composition - Google Patents

Abstract

A water-based polymer coating composition comprising a polymer resin, water and dispersants, the improvement wherein: the dispersant system is multifunctional, based on natural carbohydrates in an amount effective to produce pigmented mill bases; and the coating composition further utilizes as binder terpene (co)polymer resin emulsion derived from renewable and sustainable sources. Preferably the dispersant is based on natural carbohydrates selected from, but not limited to the group comprising, galactans, particularly galactomannans (carrageenan, guar gum, xanthan gum, acacia gum, tragacanth or water soluble alginates), whether singly or, more especially as synergistic mixtures.

Description

1 2406097

COATING COMPOSITIONS

TECHNICAL FIEED

This invention relates to coating compositions and in particular to coating compositions which reduce the reliance upon petrochemical and highly synthetic materials. Coating compositions are described, for example, in Paint Handbook (Harold B. Crawford & Beatrice E. Eckes eds., 1981)

BACKGROUND TO THE INVENTION

Both legislative and marketplace developments are pushing forward the desire to reduce the environmental burden associated with the production and use of modem coating materials. Health issues are now of concern relating to the inherent toxicology and the chemistries of coating materials. There is also an emphasis on the coating /substrate dynamics being able to provide for breathability and microporosity (issues of humidity control and 'sick building' syndrome). .

The conventional coatings industry has for instance moved to reduce organic solvents in aqueous compositions bringing some safety and health benefits. However the resulting coating compositions are still based upon synthetic petrochemical and highly environmentally burdensome materials; for example vinyl/acrylic polymers, titanium dioxide pigments and biocides. It is desirable to remove or reduce these components whilst producing a coating which exhibits good technical properties such as block resistance, adhesion and tensile properties. It is also required that a coating should be readily applied and retain it's original properties and not degrade, for instance, under the action of ultra violet ('UV') light, humidity, temperature fluctuation and cleaning. Furthermore the ingredients should be compatible with current manufacturing equipment and formulating practice.

Conventional aqueous coating compositions may contain upwards of twenty components which are generally identified by function.

For example, in addition to a resin or resins (also called latexes or binders), an aqueous coating composition may have: pigments dispersants surfactants (such as wetting agents, de-foamers, and anti-foamer), extenders, anti settling agents, rheology modifiers including thickeners, coalescing solvents, plasticizers, water, glycols, catalysts, biocides, cross linkers, and colorants. - he .

Many of the components discussed above used to formulate conventional waterborne coatings have adverse ecological significance. bee

. For example small amounts of volatile organic compounds ('VOC's); some : . colorants are dispersed with glycols and solvents, additives such as catalysts & rheology control agents are carried in solvent and glycols are present in many commercial surfactants, biocides, de-foamers, etc. Apart from VOC's other issues arise, for example plasticizers (including chemicals from the phthalate, adipate, and benzoate families) are indicated as endocrine modulators; at high levels, they have a deleterious effects upon the aquatic environment.

Latex binders and dispersant polymers are typically based upon acrylic and vinyl/styrene monomers many of which are carcinogenic.

Surfactants, thickeners and protective colloids are often products of alkoxylation (usually with ethylene oxide a highly dangerous carcinogen) and are implicated as oestrogen mimics. Ethylene oxide is both flammable and highly reactive.

Acute exposures to ethylene oxide gas can result in respiratory irritation and lung injury, headache, nausea, vomiting, diarrhoea, shortness of breath, and cyanosis.

Chronic exposure has been associated with the occurrence of cancer, reproductive effects, mutagenic changes, neurotoxicity, and sensitization.

Pigments such as organic dyes are highly synthetic and often derived from toxic compounds such as amines.

Titanium dioxide white pigment in particular is synthesized by a highly energy intensive process and involves toxic intermediates.

Even benign materials such as fillers including talc, calcium carbonate, diatomaceous earth, mica, kaolin, barium sulphate, magnesium carbonate, vermiculite, graphite, alumina, and silica have mining and transportation impacts.

On the other side, so-called natural paints often utilize natural materials with limitations in technical properties or processing constraints and the so-called environmentally friendly water based binders such as alkyd (oil modified polyester) resins have petrochemical components such as phthalates & isophthalates, . trimethylolpropane, pentaerythritol. ... I.

Other more natural coatings are, for example, based upon natural vegetable oils such . as linseed oil which is prone to W degradation and concomitant yellowing. They . a.

require considerable specialist art in manufacture technique and processing. Natural materials such as waxes, shellac, copal and dammar resins are dissolved in organic solvents as intermediate steps to produce water-borne emulsions, natural glues (oligoproteins) such as casein are also used; they are low in molecular weight and poor in mechanical properties compared to high-polymer materials.

Following from the above brief discussion it is apparent that there is a need (to place it no higher) to reduce or eliminate non- renewable high environmental impact materials from aqueous coating compositions without effecting the overall technical properties of the wet coating or end-use performance or its ease of production.

Modern synthetic emulsion paint may be identified by classes of components. Water- based polymer coating compositions are for example described in Technology of Paints, Varnishes and Lacquers, Robert E. Krieger Publishing Co., Huntington, New York, 1974, Water-based polymer coating compositions comprise pigments (organic or inorganic) extender fillers, latex binder and additives known in the art.

Pigments and fillers are non-petrochemical minerals.

Binders and additives are mostly derived from synthetic organic chemistry and include, but are not limited to: levelling, rheology, and flow control agents such as silicones, fluorocarbons, urethanes, or cellulosics.

Curing agents such as multifunctional iso-cyanates, carbonates, epoxides, or multifunctional acrylates.

Reactive coalescing aids such as those described in U.S. Pat. No. 5,349, 026. I.. .

Flatting agents. e..

I

: Pigment wetting and dispersing agents and surfactants.

2 Ultraviolet (UV) absorbers & stabilizers. ee..

Tinting pigments.

De-foaming and anti-foaming agents.

Anti-settling, anti-sag and bodying agents; anti-skinning agents.

Anti-flooding and anti-floating agents; fungicides and mildewicides; corrosion inhibitors; thickening agents.

Plasticizers.

Reactive plasticizers.

Drying agents.

Catalysts.

Specific examples of such additives can be found in Raw Materials Index, (published by the National Paint & Coatings Association, 1500 Rhode Island Avenue, NW, Washington, D.C. 20005).

Current emulsion paints have pigmentation based upon titanium dioxide as opacifying and whitening agent. Production of this material is highly energy intensive and involves either toxic and corrosive sulphates or chlorides as manufacturing intermediates. The mining and extraction of raw Illmenite ore material has extensive environmental impact.

Colorants may be minerals and oxides of low environmental impact but most typically are synthetic organic dye type pigments and synthetic micro crystals.

Synthetic latexes are well known and can be made by emulsion polymerization techniques: for example styrene-butadiene or ABS copolymers, acrylate resins, polyvinyl acetate, from polymerization of ethylenically unsaturated monomers such as acrylonitrile, butadiene, styrene, methyl methacrylate, vinyl acetate, vinyl 2- ethylhexanoate, vinyl versatate, acrylic acid and it's esters (e.g. butylacrylate, 2hydroxyethyl acrylate), methacrylic acid & esters ( e.g. methylmethacrlyate, glycidyl methacrylate) and the like.

Current so-called best practice modern environmentally friendly emulsion paints avoid aryl residues such as alkyl phenols, giving alkylphenolethoxylate -free status.

Preferred anionic surfactant would be for instance sodium lauryldiglycol sulphate and non-ionic surfactant would be the ethoxylation products of lauryl alcohol, oleyl alcohol, stearyl alcohol or mixtures of these 'natural bases'. They do, however, still contain a large proportion of synthetic components.

Protective colloids include partially and fully hydrolyzed polyvinyl alcohol, hydroxyethyl cellulose, hydroxymethyl cellulose, ethylhydroxyethyl cellulose, carboxymethyl cellulose, ethoxylated starch derivatives, polyacrylic acid, alkali metal polyacrylates, polyacrylamide, poly(methyl vinyl ether/maleic anhydride), and polyvinylpyrolidone. Again although these components contain material of vegetal origin and are so regarded as 'environmental' by the industry, they still include a high proportion of petrochemical feedstock and synthetic processing.

MODERN COATING METHODOLOGIES

The following general examples of the type readily provided by raw material suppliers serve to illustrate current coatings and illustrate their large synthetic & petrochemical content.

,., A conventional formulating approach would be to produce a mill base pigment dispersion or grinding stage using a high speed disperser. This would then be diluted; or 'let down' with polymer latex binder at lower speed. The methodology is a applicable to both laboratory and full-scale manufacture.

Example 1. Typical Interior Vinyl Matt Paint.

55% PVC (pigment volume concentration) ca 55% solids content.

Mill-Base or Pigment Dispersion.

Water 715g Thickener Natrosol Plus (RTM) (Aqualon) 12g i Biocide Kathon LX (RTM) 1.5% (Rohm & Haas) 5g Water Softener Tetron (RTM) KTPP (Rhodia) 5g AntiFoam Byk (RTM) 034 (Byk Chemie) 12g Dispersants Tamol (RTM) 731 25% (Rohm & Haas) 39g Surfactant Surfynol (RTM) 465 (Air Products) 15g Dissolve above to form aqueous solution, add pigments with high speed stirring.

White Pigment Titanium Dioxide TI-PURE (RTM) R-900 (DuPont) 455g Extenders Huber (RTM) 70C (DuPont) 292g Beaverwhite (RTM) 325 (Imerys) 260g Duramite (RTM) (Imerys) 325g.

Let down at slow speed stir Water 300g Neutraliser ( pH adjust) 20% aq. Sodium Carbonate 70g Defoamers Byk (RTM)035 (BykChemie) 5g Surfynol (RTM) 104E (Air Products) 12g Binder Vinyl Latex e.g. VV575 (SynthomerLtd) 1000g Opacifying latex Rhopaque (RTM) OP 62 LO (36.5%) (Rohm & Haas) 240g Rheology modifiers Polyphobe (RTM) 107 (25%) (Union Carbide) 12g . Polyphobe (RTM) 102 (25%) (Union Carbide) 66g ë I..e Example 2 45% PVC 55% solids white exterior flat house paint with zinc oxide e.

. Pigment Grinding Stage Dispersing Media Water 98g Propylene Glycol 59g Water Softener Tetron (RTM) KTPP (Rhodia) 5g AntiFoam Byk (RTM) 034 (Byk Chemie) 12g Dispersants Sodium poly(meth)acrylate copolymer -Colloid 226 (Rhodia) 10g Surfactants Triton (RTM) CF-10 (Dow Chemical) 3g White Pigment Titanium Dioxide Ti-Pure R-902 [DuPont) 225g Zinc Oxide Eagle (RTM) 417W (Eagle Zinc) 25g Extenders Calcined china clay Optiwhite (RTM) (Burgess) 50g Aluminosilicate(Zeolite) Minex (RTM)4 (Unimin) 145g Thickener Cellosize (RTM) QP-4400 HEC 2.5% aq Sol (Dow Chemical) 123g Attagel (RTM) 50 (Engelhard) 5g Biocide AMP-95 (RTM) (Angus) lg Let Down Neutraliser ( pH adjust) 28% Aq. Ammonium Hydroxide Solution 2g Binder NeoCAR Acrylic Latex (Dow Chemical) 378g Coalescing Solvent Ucar Filmer (RTM) IBT (Dow Chemical) 20g Mildewcide Skane (RTM) M -8 (Rohm & Haas) lg Rheology Control Colloid (RTM) 643 (Rhodia) 2g Cellosize (RTM) QP-4400 2.5% aq. Solution 43g It will be seen that these recipes include many complex synthetic materials but are relatively robust and produce effective easy-to-use coatings. . ..e

NATURAL PAINTS

.. In contrast to the foregoing current coatings the so-called technical 'natural' paints are recipes' (rarely disclosed) involving convoluted manufacturing processes with high degrees of subjective feel and qualitative assessments which do not necessarily lend . themselves to a modem quality oriented mass production. ..DTD: Example 3 Non-Toxic White Milk paint -Liquid or Semi-Liquid (USP 20020170463 In this recipe the components are made separately and combined in the approximate ratio to material often described in such terms as 'a nice double cream texture' "Vehicle" 25% Kaolin Slurry, 10% Pigment, Dispersion 65% . Component 1"Vehicle" Casein Milk Protein 18.37% Potassium sorbate 0.50% Amino MethylPropanol (AMP95) 1.91% Water 76.61 % Urea 2.61 % Component2-Kaolin Slurry Kaolin 45.14% "Vehicle" 27.03% AMP95 0.50% Potassium Sorbate 0.50% Water 26.83% Component 3 -Pigment Dispersion "Vehicle" 21.72% Water 10.00% . .. Potassium Sorbate 0.40% a Chalk 25.82% ale. Titanium Dioxide 42.70 . . It can be readily seen even this simple non-technical paint contains not only synthetic . titanium dioxide but also petrochemicals such as AMP-95, and urea which are often . non-natural in origin.

Example 4 30% PVC Natural Mid-Sheen (Eggshell! Paint An indicative recipe for a so-called technical natural emulsion satin paint would involve formation of pigment dispersion within the oil/resin components of the paint and emulsification of that oil/pigment phase into water IN OIL EMULSION FORM.

Solvents and heat ARE OFTEN required to attain mobility of the oil phase in order to emulsify it.

Oil Phase Preparation.

Mix the following to a homogenous solution.

Wetting Agents Potassium Oleate 50% aq. soft soap 200g Turkey Red Oil 100g Binders Dammar Resin 60% in "Solvent" (Citrus Oil / Ethanol / Safflower Oil mixture) 1000g Linseed Oil 400g Colophonium Glycerol ester 66% in "Solvent" 300g Lime Hardened Colophonium 60% in "Solvent" 50g Neutralisation Powdered Ammonia (Ammonium Carbonate) 50g Millbase Preparation.

Disperse/grind in the pigments & fillers Pigment TiO: 600g Mildewcide ZnO 400g Extender Chalk 600g PH Buffer Borax 5g ë Pigment Dispersant Soya Lecithin 10g ë hi. Water-in-Oil emulsion Preparation.

High speed mix.

Stabiliser (water coupling dispersant) Casein 20% aq (inc NHCOa) 500g Preservatives Lavender & Thyme Oil 10g Thickener Methyl Cellulose 30 % aq. solution 200g Inversion Process Letdown Water in aliquots 6200g - until change in viscosity indicates "oil-in-water" emulsion.

As stated earlier there is considerable practical know-how and specialist techniques needed for the production of natural paints of these types and a great deal of skill in the art.

The following raw materials are, according to the German Association for Natural Colors Quality Standards, typical renewable materials of plant or animal origin, but often entail at least high energy processing. They include conventional materials stretched to fit the designated criteria for example Titanium Dioxide-claimed as non-toxic essential whitener by industry with little environmental issues if produced by the 'Sulfate Process'. However this can hardly be described as a renewable material.

Methyl cellulose -synthetic ether from reaction using methylene chloride, but deemed acceptable as it is a non-ethoxylated product.

Colorants tend to be metal oxides and mineral earth pigments but also include those synthetic oxides and other materials general to the industry.

Other materials (e.g. sulfated castor oil) are 'produced in simple chemical processes free of toxicity issues'. Nevertheless but can raise their own environmental issues, and are often of limited technical capability quite apart from semantics involved in definitions of 'sustainability' and 'renewability'.DISCLOSURE OF INVENTION ë :.: According to the present invention there is provided a coating composition embodied as a water-based polymer coating composition comprising a polymer resin, water and . -.

at least one dispersant, the dispersant being multifunctional, based on natural .e carbohydrates in an amount effective to produce pigmented mill bases; and the coating composition further utilizes a polyterpene resin emulsion derived from p- menthadienes.

According to a first preferred version of the present invention the dispersant is based on natural carbohydrates including one or more selected from, but not limited to, the group comprising, galactans, particularly galactomannans (carrageenan, guar gum, xanthan gum, acacia gum, tragacanth or water soluble alginates), whether singly or, more especially as synergistic mixtures. Typically thickening and rheology control is achieved with the above natural carbohydrates without recourse to additional materials.

According to a second preferred version of the present invention the dispersant is free of conventional anionic, cationic, amphoteric or nonionic surfactants as stabilizers and dispersion aids.

According to a third preferred version of the present invention or of any preceding preferred version thereof surfactants when present in the composition function additionally as coalescents and open-time modifiers and are natural fatty acid and simple sugar derivatives such as potassium oleate, sorbitan monoalkylates, alkyl glycosides and poly glycosides According to a fourth preferred version of the present invention or of any preceding preferred version thereof the resin polymer resin emulsion is derived from terpenes such as p-menthadienes. Typically the resin polymer resin emulsion is derived from e d- limonene, pinenes and rosins. Preferably the resin polymer resin emulsion is derived as single components or blends of the above components. ë

According to a fifth preferred version of the present invention or of any preceding preferred version thereof includes a pigment which is mineral in origin. Typically ' pigmentation is achieved by use of zinc sulfide and/or zinc oxide based pigments 1 1.

l e which are multifunctional, combining pigmentation with preservative properties.

Preferably the pigmentation is achieved by use of mineral and metal oxide pigments selected from, but not limited to, a group including so-called earth pigments, metal oxides (including natural and/or synthetics iron oxides) and eg ultramarines, etc. According to a sixth preferred version of the present invention or of any preceding preferred version thereof the composition is substantively free of further conventional additives selected from solvents, levelling agents, rheology modifiers, flow promoters, coalescing aids, flatting agents, ultraviolet absorbers, ultra violet light stabilizers, anti- settling agents, anti-sag agents, bodying agents, fungicides, mildewcides, thickening agents and plasticizers.

The present invention is broadly concerned with the provision of an environmentally acceptable and renewable water-based polymer coating composition comprising multi-functional materials fulfilling the roles of polymer resin binder, dispersant i /thickener/macro-surfactant and biostat pigmentation. Significant amounts of petrochemical materials are eliminated in comparison with existing conventional coatings..

It has been discovered that natural carbohydrates can be employed at levels similar to those used with modem conventional synthetic dispersants and surfactants. They also provide a standard thickening function in the coating, thus eliminating a number of components from industry standard formulations. In addition they hold (release less quickly) water in the coating film so negating the necessity for additives such as rheology modifiers, flow promoters, open -time solvents, etc. The hydrocolloids of this invention also act synergistically in their thickening mechanism reducing overall amounts as compared to conventional synthetic celluloses. These carbohydrates are of . the types more generally encountered in the food industry and could include alginates, pectinates, galactans, chitins and the like. :

A class of resins not general to conventional decorative architectural coatings has been found based upon citrus and pine tree oils i.e. terpenes such as abietic acids (rosin), pinenes, dipentene and limonene. These materials are supplied as polymer emulsions in usual form and are used in conventional let down manner.They can have low yellowing properties and can be copolymers of the usual range of synthetic monomers giving the broad range of film properties desired in a modem coating. For the purposes of this invention natural pure polyterpenoids are preferred allowing the balance of such properties of film formation, ultra violet resistance (yellowing), hardness & elasticity The main white mineral pigments used in the coatings of this invention are preferably based upon zinc sulfide, which combines opacifying and filler properties and also has a preserving effect. The synthetic product as used in the invention also has intrinsic ecological advantages in that it is produced from waste stream products from titanium dioxide manufacture.

Extenders, when employed, are polyvesiculated beads so as to introduce additional air-voiding into the film and enhance microporosity. This allows breathability in formulations of lower than malt (critical) pigment volume content. Such materials include natural or calcined diatomaceous earths or calcined China Clays (Kaolin). I These ingredients enable a coating to be produced in a conventional manner, which has a significantly reduced content of material derived from petrochemical sources and lower embodied energy.

These materials can be used to formulate paints especially environmentally acceptable high solids coatings across the spectrum of sheen and PVC typical of gloss, satin and . mall paints according to the general practice of the industry. It is noted that coatings should be taken to include not only paints but also stains and clear lacquers. They are A. also fully compatible with conventional paint industry materials allowing their use alongside those materials in a multipurpose paint manufacturing plant. They are

intermix stable'. c..

Typically in an aqueous make-up dispersants, thickeners, open-time and coalescing solvents and rheology modifiers are replaced by natural hydrocolloid galactan carbohydrates...DTD: The binder is typically a polyterpene directly analogous to modem synthetics latexes and produced by conventional polymerization techniques. It's advantage arises in it's conventional properties in a polymer derived from renewable monomers such as the p-menthadienes (pine & citrus oils) The pigmentation is such that opacity and filling properties can be achieved within a single component that also doubles as a biostat, enabling conventional paint biocides to be disregarded in the formulation. The minerals used also control pH removing necessity for additional neutralization.

Other conventional additives can be used with the materials as exemplified in this invention as in general modem coating formulating practice, but in accordance with the ethical precepts of minimum environmental impact they should be of minimal synthetic content and processing.

So, preferred components would be for instance the so-called sugar surfactants (sorbitol esters or alkyl glycosides), and mineral oil or alcohol antifoams. Coloured pigments would be minerallic and natural where possible.

An exemplary embodiment of the present invention will now be described. It is part of a general principle to minimise the burdens of packaging and transport so it is .ce formulated to have high solids and high PVC content. The materials used must have the appropriate colloidal properties (particle size and shape) to be able to accommodate this approach cees. J.

: ' Example (80% PVC Malt Paint, 70 % Solids) e. )e . . Mill-Base Dispersing medium Water 400g Dispersant/Thickener/Rheology Control Carrageenan 4g & Xanthan Gum 4g Antifoam Dispelair(RTM) CF269 7g Open-Time Surfactant/Coalescent Sorbitol monoOleate 15g Pigment/Filler/Biostat Lithopone 60% 600g Let Down Proprietary polyterpene/Rosin emulsion 300g At first glance this appears a much simpler looking formulation with less ingredients and easy make-up, but this belies the multifunctional roles of the ingredients, even to the extent that the whole colloidal system acts synergistically.

One intention of this invention is to combine and balance good available modem materials with renewable and sustainable natural materials to produce hybrids having the lowest adverse environmental impact coupled with high technical performance.

This has led to the development of a formulating practice wherein components providing multiple functions are sought. They will possess a low petrochemical content, have low toxicity in their manufacture and in their own right, and have as low an energy burden as possible. These materials must then have additional features such as ease of manufacture together with appropriate technical and aesthetic properties to be fitfor-use by the modem consumer.

In contrast to the types of conventional compounds outlined earlier the types of ingredients favoured in the present invention are more typically used in the food and . . cosmetic industries. They include natural hydrocolloids, the most favoured being the galactopyranoses e.g. alginates, agar and like seaweed extracts and the galacto . mannans for example acacia (gum arable), carob (locust bean gum) ghatti, karaya, guar, maniac, tragacanth, xanthan, yacca. An indication of the properties and synergistic benefits obtained in correct use of these materials can be found in "The . Handbook of Hydrocolloids", G Phillips & PA Williams, Woodhead Publishing Ltd Aug 1999.

Surfactants perform as stabilising and wetting agents, but additionally function as coalescing aids and act to retard the speed of water evaporation from the film allowing 'open-time'. In order to meet the ethos behind this invention the surfactants are drawn from such categories as simple alkali fatty acid soaps e.g. potassium oleate, low impact processed materials e.g. sulfated castor oil 'Turkey Red Oil', sugar surfactants such as the sorbitol esters, alkylpolyglycosides and the like.

Pigments for the purposes of the present invention are of the type generally used in the industry (but are not limited to them). The exclusion of products derived from titanium dioxide, synthetic rutiles and organic petrochemistry arise from consideration of their poor environmental profiles, extreme energy costs in production and toxicity of starting and/or in-process intermediates. They may be used conventionally with the dispersant systems and binders of this invention with no technical deficit but little ecological benefit would accrue. Synthetic minerals and metal oxides are used when a natural material has properties insufficient to assure quality and fitness for the designated use.

Favoured binders for this invention are pine and citrus oil derivatives typically terpene & rosin (co)polymers produced as emulsions. In addition, as subsidiary binders and modifiers the so-called environmentally friendly resins such as long oil alkyd emulsions, castor oil polyurethanes or acrylates and like materials could be included in the formulations. Once more, no technical issues arise in their use; indeed the usual benefits accrue with high specification materials such as polyurethanes, but a slightly higher environmental impact arises. ë .

:: It is also noted that the gamut of conventional 'additives' of the industry such as plastic pigments (Rhopaque), rheology modifiers/thickeners, coalescants, biocides etc ë can also be incorporated with materials of the invention, but with consequent decrease ..

in environmental profile.

Broadly the present invention relates to water- based polymer coating composition substantially comprising polymer resins, water, dispersants, and pigments. The proposed composition has a substantially reduced content of petrochemical derived organic compounds from which it follows that the proposed compositions have a low environmental impact. As a further improvement there is a reduction in overall synthetic content in the coatings of this invention when compared with conventional coatings. The components making up the compositions of the present invention aremultipurpose in operation and so remove other materials from the recipes. The materials of this invention offer improvements over water-based natural resin compositions in that their properties, ease of manufacture and formulation practice are akin to conventional industry standards. ë ë A. I. *.. ë.e

ale.... . en.. ...

Claims (13)

1 A water-based polymer coating composition comprising a polymer resin, water and dispersants, the improvement wherein: the dispersant system is multifunctional, based on natural carbohydrates in an amount effective to produce pigmented mill bases; and the coating composition further utilizes resin emulsions derived from terpenes.

2 A water-based polymer coating composition as claimed in Claim 1, wherein the dispersant is based on natural carbohydrates selected from, but not limited to the group comprising, galactans, particularly galactomannans (carrageenan, guar gum, xanthan gum, acacia gum, tragacanth or water soluble alginates), whether singly or, more especially as synergistic mixtures.

3 A water-based polymer coating composition as claimed in Claim 2 wherein thickening and rheology control is achieved with the above natural carbohydrates without recourse to additional materials.

4 A water-based polymer coating composition as claimed in any preceding claim A. wherein the dispersant system is free of conventional anionic, cationic, amphoteric or non-ionic surfactants as stabilizers and dispersion aids. e.e

, .

5 A water-based polymer coating composition as claimed in any preceding claim :. wherein surfactants when present in the formulation additionally function as coalescents and open-time modifiers and are natural fatty acid and simple .

sugar derivatives such as potassium oleate, sorbitan alkylates, alkylglycosides .

and polyglycosides.

6 A water-based polymer coating composition as claimed in any preceding claims wherein the resin polymer resin emulsion is derived from terpenes such as the p-menthadienes, abietic acid and it's derivatives.

7 A water-based polymer coating composition as claimed in Claim 6, wherein the resin polymer resin emulsion is derived from monomers including d-limonene, a- & p-pinenes and rosin/rosin esters either purely as polyterpenes or as copolymers in conjunction with the conventional comonomers of the adhesive and coatings industries.

8 A water-based polymer coating composition as claimed in Claim 6 or Claim 7, wherein the resin (co)polymer resin emulsion is derived as single components or blends of the above components.

9 A water-based polymer coating composition as claimed in any preceding claim including a pigment which is mineral in origin or an organic dye based pigment.

A water-based polymer composition as claimed in Claim 9, wherein the use of zinc sulphide and/or zinc oxide combines pigmentation with preservative properties.

11 A water-based polymer composition as claimed in Claim 6, wherein colouration is achieved by use of non toxic mineral and metal oxide pigments selected from, but not being limited to, a group including socalled earth . .

: .. pigments (e.g. ochres, timbers), metal oxides ( eg natural and/or synthetic iron A. . oxides), Ultramarines, Chrome(III)Oxide Greens, etc. - .

12 A water-based polymer composition as claimed in any preceding claim and : substantively free of further conventional additives selected from solvents, levelling agents, rheology modifiers, flow promoters, coalescing aids, flatting ...

agents, ultraviolet absorbers, ultra violet light stabilizers, antisettling agents, ..

anti-sag agents, bodying agents, fungicides, mildewcides, thickening agents and plasticizers.

13 A water based polymer composition as herein before described by way of an exemplary embodiment.