WO2016178244A2

WO2016178244A2 - Water borne cross linked and hydrophobic shellac-pu-acrylic hybrid for glossy enamel and wood finish

Info

Publication number: WO2016178244A2
Application number: PCT/IN2016/000118
Authority: WO
Inventors: Sisir Kumar Mandal; Kiran Kumar NEHETE
Original assignee: Asian Paints Ltd.
Priority date: 2015-05-05
Filing date: 2016-05-05
Publication date: 2016-11-10
Also published as: WO2016178244A3

Abstract

A shellac polymer hybrid is provided and a process thereof comprising a polymeric reaction product which is urethanised, malenised and/or oelfinised modified shellac with modified hydroxyl value including grafted polymer cross linked with shellac, said polymer hybrid having modified solid levels and favouring increased water and solvent retention. Said hybrid is provided as aqueous solutions and dispersions of cross linkable shellac-polyurethane-polymer hybrid and a high gloss coating formulations attained thereof, which polymer hybrid dries fast with good mechanical properties and gloss retention. Advantageously, the increased solid level of the dispersion favours application by brush without sagging in addition to the advantage of application by ragging wherein reducing the hydroxyl group content of shellac increases the water and solvent resistance to a significant extent.

Description

TITLE: WATER BORNE CROSS LINKED AND HYDROPHOBIC SH ELLAC-PU- ACRYLIC HYBRID FOR GLOSSY ENAMEL AND WOOD FINISH

FIELD OF THE INVENTION

The present invention relates to an shellac polymer hybrid as aqueous solutions or dispersions of cross linkable shellac-polyurethane-polymer hybrid and a high gloss coating compositions attained thereof comprising polymeric reaction product of natural or processed malenised or oelfinised shellac involving at least one cross linkable monomer, an isocyanate and at least one amine, which polymer hybrid dries fast with good mechanical properties and gloss retention. Advantageously, the increased solid level of the dispersion favours application by brush without sagging in addition to the advantage of application by ragging wherein reducing the hydroxyl groupcontent of shellac increases the water and solvent resistance to a significant extent. The present invention also provides a facile process to attain the hybrid and the resulting dispersion whereby the conversion of hydroxy group of shellac of the polymeric product by way of the process of the present invention enables enhancement of the molecular weight of the shellac to attainbetter film mechanical properties and water resistance.

BACKGROU ND ART

Shellac is an excretion of an insect of the type female lac insect Kerria Lacca normally employed for cosmetic, Drug, food and wood coatings applications. The major strains of shellac available in India are Kushmi and Rangini. Purified wax free shellac is having molecular weight about 1000 containing units of -OH and - COOH functional groups together with olefinic and aldehyde function as unsaturation in the molecule. The composition of shellac varies from source to source and process to process. Bleached shellac may or may not contain any olefinic function. However, decolorized shellac by treatment with mild bleaching agents or carbon powder or bed may retain the olefinic and other functionalities most. Though there are controversies about the true composition of shellac, the composition contains esters or acids from the group consisting of aleuritic acid, shellolic acid isomers, butolic acid, jalaric acid isomers and wax. In the market bleached and unbleached or free shellac containing wax are available with different colours and reactivities. Manufacturer's of dewaxed bleached shellac supplies shellac flakes and powders with variable acid value, iodine value and hydroxyl value. Most commercial dewaxed and bleached shellac having acid number in the range 65-90, hydroxyl value 180-420 but there are manufacturers where acid value is as high as 150 mg KOH/gm and hydroxyl value as low as 200 mg KOH/gm. Shellac containing low acid value and high hydroxyl values are normally unstable and undergoes polymerization under ambient conditions over long time in anhydrous condition and maximize above 100 Deg C whereas Shellac having high acid value and low hydroxyl value are normally stable which can be processed at high temperature even under anhydrous conditions.

Commonly known French polish has high level of solvent increasing the risk for the applicator as well as the environment. The solid level of the normal French polish is less than < 15 % due to the solubility limit. Precipitation by evaporation of the solvent during application posses application problem in the later coats. The filling of wood grains on edges or near to the edges are poor due to low solid content. Gloss retention after application is an issue due to the reorganisation of the shellac polymer over time. The number of coats required in order to get good gloss is unacceptably high increasing the labour cost.

Shellac solutions or dispersions on an aqueous basis are known DE 19734548 Al, US3061563, US6302950 using a highly acidic solution having pH below 4.2 preferably 2-4.2. Under this conditions the ester bonds of shellac opens up and the molecularity may be destroyed over long time storage thereby affecting overall performance of the coating.- Highly acidic solution prevents the appplication by ragging with bare hands especially in Indian market where poor income consumers prefer to have it.

Commercial water thinable products are available in the brand name of ultraseal, marcoat and emcoat and are easy to operate but the coating film suffers from water and solvent resistance though the mechanical properties and sheen are not fully affected .There is neither any prevalent state of the art teaching on the coating film of Ultraseal, marcoat and emcoat that can be top coated with 2K PU or with harsher acid catalysed melamine aminoresin top coat, nor there is any teaching on grain filling using powder at lesser number of coats. Further gloss retention becomes challenging when water based systems are used and it is difficult to achieve good wet look and hardness of the polymer film with retention of gloss.

US 5567438 teaches the preparation of aqueous shellac by reacting with alkali and further processing in acid and amine to give shellac film in presence of plasticiser., The sodium salt or any organic ionic salt attracts water very fast due to hygroscopic nature and reduces the protection against water.

US 2928797 discloses a wax composition consisting of component polymer derived from olefinic monomer at various level and shellac in soluble form. The wax in shellac normally destroys gloss due to refractive index difference and the absorption of water. The patent does not use isocyanate as a cross linker to provide good water resistance and mechanical properties with good top coatability with polyurethanes. Wax has detrimental effects on the top coating with melamines.

JP 2007197529 A 20070809 discloses coatings that comprised of a range of polymer dispersion including shellac for a anticorrosive coatings without shellac being bound in a polymer. Such coatings are unlikely to have cross linking to get a good mechanical properties and top coatability with polyurethanes because polyurethane compatible backbone originating from isocyanate is non-existent.

DE 3931237 Al 19900621 discloses an aqueous polyurethane dispersion at higher quantities which tends to dry slow raising grains resulting in poor finish. Shellac being free and lack of cross linking during film formation results into gloss loss over a period of time. This also may suffer from mechanical hardness and top coatability with melamine due to the lack of cross linking. SU 704973 A119791225 describes a composition of coating using a polymer that does not cross link which may lead to lifting of top coating with melamine or polyurethanes.

JP 51063828 A 19760602. Emulsion polymerisation involves surfactants and the surfactant usually destroys the gloss. Surfactant also has detrimental effects on the top coating with melamine and polyurethane.

New developments in the finishing of pigskin By Leibengrub, G. A. From Kozhevenno-Obuvnaya Promyshlennost (1972), 14(1), 50-2 describes the use of emulsion containing surfactants that may have detrimental effects on gloss. Significant whitening observed during application with emulsion blend and is a known fact.

US 3061563 discloses the resin where the shellac acrylic co-polymer lacking cross linking monomer and cross linking with amine or hydrazide to form a intractable polymer film for a compatible top coating with melamine and polyurethane.

While it is apparent from the prevailing state of the art that the same neither suggests nor addresses the issue of water resistance, solvent resistance, stability in aqueous medium of a polymeric product involving shellac to also have compability with melamine or PU (polyurethane) as top coat to favour multiple coats having high thickness retaining high gloss, it is thus the need of the day to attain a product and a process thereof that would circumvent the above said problems such the broad range of shellac available in the market can be converted and made stable in aqueous medium and gloss retention in water based systems can be achieved together with good wet look and hardness of the polymer film.

OBJECTS OF THE INVENTION

It is thus the primary object of the present invention to provide for a shellac- polymer hybrid and dispersions/ coatings comprising the same having improved water and solvent resistance as compared to pure shellac and hybrids known. It is another object of the present invention to provide for said shellac-polymer hybrid and dispersions/ coatings comprising the same that would involve suitable grafting of the cross linkers to provide mechanical strength that would allow lower solvent/waterpenetration, faster drying and retention of gloss.

It is yet another object of the present invention to provide for shellac-polymer hybrid that is hydrophobised for better storage stability and water repellency.

It is another object of the present invention to provide for shellac-polymer hybrid and dispersions thereof that would be compatible with polyurethane and melamines as top coat to provide for multilayer coats of high thickness with the retention of high gloss without wrinklings.

It is yet another object of the present invention to provide for said hybrid and dispersions thereof with high solid levels whereby the number of coats can be reduced to a significant extent to thereby reduce the labour and time.

It is another object of the present invention to provide for a said hybrid and dispersions thereof that would be brushable without sagging and would also dry fast to thus reduce labour cost.

It is yet another object of the present invention to provide for said hybrid dispersions/ coating compositions comprising the same which in involving reduced level of solvents would improve the wellness in the application area .

It is another object of the invention to provide suitable hybrid dispersion with amine or amidoamine cross linking with the backbone to give better wetlook and retention of gloss after drying in addition to urethanation.

It is another object of the present invention to provide for said dispersions/coating that can be pigmented to give stained coating or primer or top coating for better hiding and colour choice and can be applied on metal, wood, masonry and concrete plasters.

It is stiir another object of the present invention to provide for a facile process for attaining the hybrid and the resulting dispersion whereby the conversion of hydroxy group of shellac of the polymeric product would enable enhancement of the molecular weight of the shellac to attain better film properties and water resistance and would also aid in achieving compatibility with the polyurethane and melamines as top coat to provide for multilayer coats.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention there is provided a shellac polymer hybrid comprising a polymeric reaction product which is urethanised, malenised and/or oelfinised modified shellac with modified hydroxy! value including grafted polymer cross linked with shellac, said polymer hybrid having modified solid levels and favouring increased water and solvent retention.

Preferably said shellac polymer hybrid comprising a polymeric product having functional cross linkable isocyanate based backbone including urethanised, malenised and/or oelfinised shellac grafted with polymer involving at least one olefinic monomer having at least one cross linkable monomer and crosslinked with amine cross-linker.

More preferably said shellac polymer hybrid comprises a polymeric product of monomers, malenised and/or oelfinised shellac, isocyanate, and at least one amine cross-linker.

According to another preferred aspect of the present invention there is provided a shellac hybrid wherein said monomers involve at least one olefinic monomer and at least one cross linkable monomer. Preferably in said shellac hybrid said malenised and/or oelfinised shellac comprises olefinic anhydride modified shellac said olefinic anhydride selected from the group of maleic anhydride, polyisobutylene maleic anhydride, copolymer of maleic anhydride with olefins and acryloyl or methacryloyl anhydride having at least one double bond in it; and wherein said olefinic monomer for grafting are selected from the group of acrylic acid, acrylic esters, acrylic amides, acrylc nitriles, styrene, vinyl acetate, acetoacetate ethyl methacrylate and vinyl versatate(VEOVA); and wherein said cross linking monomer is selected from the group of diacetone acrylamide (DAAM) or aceto acetate ethyl methacrylate (AAEM) or combinations thereof; and wherein said isocyanate is selected from the group of aliphatic or aromatic isocyanate including water dispersible isocyanates or its pre-polymer derivative containing at least two isocyanate groups in the molecule preferaby said isocyanates being selected from the group of hexamethylene diisocyanate or its di or trifunctional isocyanurate, isophorone diisocyanate/ or its cyanurates, toluuene diisocyanate, methylenediphenyldiisocyanate.

More preferably, said shellac hybrid comprise malenised and/or oelfinised shellac including neutral groups as modified hydroxyl groups having 30-70% reduced hydroxyl value preferably reduced by at least 40% enabling increased water and solvent resistance and better film properties.

According to another preferred aspect of the present invention there is provided said shellac hybrid as aqueous solutions or dispersions having compatibility with curable melamine or polyurethane (PU) as top coats including top coats selected from the group of thermosetting commercial melamine amino resins or polyurethane systems based on isocyanate and polyol.

Preferably said shellac hybrid is provided as a polymeric dispersion having increased polymer solid levels in the range of 20-50% for direct application by brush without sagging and polymer solid levels the range of 5% to 30% for application by ragging and provides for better film properties that dries fast with good mechanical properties and gloss retention. According to another aspect of the present invention there is provided a process for manufacturing shellac hybrid comprising the steps of:

chemically converting hydroxyl groups of shellac including selectively by malenising and/or olefinsing shellac;

urethanisation in solvent medium; followed by,

chemically grafting thus urethanised, malenised and/or oelfinised modified shellac with a polymer and further cross linking with amine to provide a polymeric reaction product involving said modified shellac with modified solid levels and hydroxyl value.

Preferably in said process for manufacturing shellac hybrid the same comprises the steps of chemically converting hydroxyl groups of shellac by olefinsing shellac, and optionally malenising, urethanisation in solvent medium followed by chemically grafting shellac with a polymer by reacting with olefinic monomers including at least one cross linkable monomer and neutralizing with at least one amine cross linker also aiding further cross linking of the polymer thus attained to yield a polymeric product based dispersion having increased solid levels.

According to another preferred aspect of the present invention there is provided a process for manufacturing shellac hybrid comprising the steps of:

a) solubilizing natural or processed shellac in a non-aqueous solvent, reacting with an isocyanate and optionally olefinic anhydride before or after urethanisation followed by grafting a polymer by reacting with olefinic monomers having at least one cross linkable monomer at temperature range 30-150 Deg C in presence of a free' radical initiator followed by neutralizing with amine and dispersing the amine polymer adduct in water;

b) adding a polyfunctional amine cross linker to the said dispersion before or after neutralization for cross linking with the functional backbone of the polymer and optionally adding a preservative to obtain therefrom said cross-linked shellac hybrid as a dispersion.

Preferably in said process for manufacturing shellac hybrid said shellac is natural or processed selected from the group of seed lac, shellac flakes, bleached shellac with or without wax and wherein said non-aqueous solvent for solubilizing shellac is selected from the group of alcohol, ketone, organo ester, organo nitrile, glycolether at the concentration of 1% to 50% by weight of the dispersion.

Preferably in said process for manufacturing shellac hybrid said isocyanate is used in the concentration range 0.1% to 50% by weight of shellac and wherein hydroxy group of the bleached shellac is reacted with isocyanate in the temperature range 50 Deg C to 120 Deg C, more preferable, at 70-90 Deg C .

According to another preferred aspect of the present invention there is provided a process for manufacturing shellac hybrid wherein the shellac is optionally reacted with olefinic anhydride at the levels of 0.1% to 20% by weight of shellac in the temperature ranging from 50-120 Deg C preferably in the temperature range of 80-100 Deg C and wherein said shellac is reacted with at least one cross linkable olefinic monomer at the levels of 0.1% to 20% by weight of monomers used.

According to yet another preferred aspect of the present invention in said process said neutralizing agent is chosen from the group of aliphatic or aromatic amines of the type ammonia, morpholine, trialkylamine, alkylethanol amine such as dimethylethanol amine, aniline, imidazole, polyamine containing at least two nitrogen atom and wherein said amine cross linkers are selected from the group of polyamidoamine, phenalkamine, cycloaliphatic amine, aromatic and aliphatic di and polyamine, more, preferably polyamidoamine or phenalkamine; and wherein said preservatives like anti termite, anti-insect and a . biocide are added in an amount sufficient for its efficacy.

According to another aspect of the present invention there is provided a paint formulation suitable for application as a primer or top coat including

shellac polymer hybrid comprising a polymeric reaction, product which is urethanised, malenised and/or oelfinised modified shellac with modified molecular weight including grafted polymer cross linked with shellac, said polymer hybrid having modified solid levels and favouring increased water and solvent retention optionally in combination with anyone or more of pigment, surface active and dispersing agents, extender and additives as non-volatile coating composition suitable for application on a substrate as primer or a top coat.

Preferably in said paint formulation the shellac polymer hybrid constitutes shellac based binder and said formulation comprises shellac solution at the levels of 5% to 70% by weight of the non-volatile coating and wherein the pigment volume ratio varies from 5% to 75% by weight of paint.

More preferably said paint formulation is provided for application as water dispersion having 5-40% solid levels and involving water as dispersing medium.

DETAILED DESCRIPTION OF THE INVENTION

As discussed hereinbefore the present invention provides for aqueous solutions or dispersions of broad varities of shellac including bleached shellac comprising cross-linkable shellac-polyurethane-polymer hybrid and a high gloss coating compositions attained thereof comprising polymeric reaction product of natural or processed malenised or oelfinised shellac involving at least one cross linkable monomer, an isocyanate and at least one amine, which polymer hybrid dries fast with good mechanical properties and gloss retention.

Advantageously, due to the increased solid level of the dispersion the same can be directly applied with much lessser foaming tendency by brush without sagging in addition to the advantage of application by ragging wherein reduced hydroxyl group content of shellac increases the water and solvent resistance to a significant extent.

More advantageously, the present invention also provides a facile process to attain said hybrid and the resulting dispersion whereby the conversion of hydroxy group of shellac of the polymeric product enables enhancement of the molecular weight of the shellac to attain better film properties, top coatability and water resistance. The process of the present invention involves chemically converting hydroxyl groups of shellac for example malenising or olefininising the shellac followed by urethanisation in solvent medium and chemically grafting shellac with olefinic monomers including cross linkable monomers and neutralising with combination of amines enables further cross linking of the polymer thus attained with amines to give a polymeric product based dispersion that dries fast with good mechanical properties and gloss retention. The solid level gets increased to such a level that the dispersion can be directly applied by brush without sagging in addition to the advantage of application by ragging.

While the conversion of hydroxyl group of the shellac to a neutral group increases the water and solvent resistance thus necessitating the reduction of -OH content of the shellac to a significant extent, the same is accomplished in a manner such that the molecular weight of the shellac is also enhanced to get better film properties and water resistance by way of the process of the present invention. Together with the above, the process of the present invention also allows maleanisation or olefinisation so as to increase the versatility of shellac grade ensuring on one hand a compatible polymer in the resulting dispersion to be compatible with melamine or PU (polyurethane) top coat and on other hand reduces the hydroxyl groups in the end polymer therey providing water and solvent resistance. The incorporation of acrylics was found to be necessary to reduce the overall cost of the lacker since shellac is very expensive.

Cross linkable backbone of the polymer is provided in order to achieve a fair amount of cross linking during the film formation for a faster drying system. This not only helps to give harder film but also increases the compatibility with melamine or PU (polyurethane) top coat.

Special amine additives are chosen for partial neutralisation of the dispersion and also to provide monomer for cross linking with functional backbone of the polymer. Such lacker can be directly used as sealer or sanding selaer for wood which can be co-mixed with silica, silicates, carbonates, metal oxides or pigments as extenders.

Such lackers can be pigmented with coloured pigments or Ti0₂ or mixed with other additives to get a primer or a top coating with high gloss and can be applied on metal or masonry or concrete surface.

In an embodiment of the present invention a process for making an aqueous dispersion of cross linkable shellac-polyurethane-polymer hybrid and a high gloss coating system is provided comprising the steps of a. Solubilising natural or processed shellac in a non-aqueous solvent, reacting with an isocyanate and optionally olefinic anhydride before or after followed by grafting a polymer by reacting with olefinic monomers having at least one cross linkable monomer at temperature range 30-150 Deg C in presence of a free radical initiator followed by neutralizing with amine and dispersing the amine polymer adduct into water.

b. By adding an po!yfunctional amine cross linker to the said dispersion before or after neutralization and optionally adding preservatives.

c. Applying the above dispersion over substrate by multiple thin coating layer and optionally applying a curable melamine composition or polyurethane as top coat,

Or

Making a suitable primer or top coat composition by mixing the above binder with pigment, extender and additives and applying on the substrate as primer or as top coat.

According to another preferred aspect of said process, said non-aqueous solvent is selected from the group of alkoxy alkyl acetate or secondary hydroxyl containing organic solvent. Preferably, said solvent is selected from the group of methoxypropyl acetate, isopropanol, t-butanol, dimethylcarbonate, diethyl carbonate, butylacetate, methylethyl ketone, methylisobutylketone, methylamylketone and the like.

Shellac can be selected from the group of bleached, shellac, seed lac, lemon grade shellac flakes available commercially with or without wax in it. The wax content of the shellac should be less if it is intended to be used as glossy top coat.

More preferably, said isocyanate is chosen from the group of aromatic and aliphatic isocyanates or its derivatives and prepoiymer having isocyanate value ranging from 5-50 gm/equivalent wherein the isocyanates are selected from the group of isophorone diisocyanate, hexamethylenediisocyanate, toluene diisocyanate isomers, methylene diphenylisocyanate, diisocyanurates of isocyanate, tri or polyisocyanurate of isocyanates, water dispersible isocyanate prepoiymer. Preferred isocyanate is water dispersible isocyanate to make a stable dispersion under storage conditions.

The reaction can be carried out in the temperature range 50-120 deg C, more, preferably in the range of 70-90 Deg C ensuring that isopronanol. hydroxyl groups are not reacted adversely. The isocyanate can be added before or after malenisation, even before neutralization of the reaction mass., Addition is preferred before polymerization with other monomers.

According to another preferred aspect of the process of the present invention the optional olefinic anhydride are selected from the group of maleic anhydride, polyisobutylenemaleic anhydride, co-polymer of maleic anhydride with olefins and acryloylor methacryloylanhydride having at least one double bond in it.

Preferably, in said process the monomer is selected from the group of olefins monomers having at least one unsaturated double bond for polymerization. Monomers can be selected from the group of acylic acid, acrylic esters, acrylic amides, vinyls and styrene. The acrylics are selected from the group of acrylic acid or amide such as methacrylic acid, butylacrylate, t-butylmethacrylate, ethylhexylacrylate, diacetone acrylamide, acetoacetatoethylmethacrylate (AAEM) . Vinyl monomers can be selected from the group of vinyl acetate, vinyl versatate (VEOVA). The concentration of the monomer may vary from 10% to 50% in order to reduce the cost of the final resin. More preferably the monomer concentration range from 20-30% looking at the final product performance and the dispersion stability of the resin under storage specially at low temperature. Acrylic acid or methacrylic acid demands depends on the dispersibility of the final resin. At high molecular Weight of the polymer requires more addition of acrylic acid. The concentration range from 0.1% to 4% preferably 0.4-1.5% by weight of shellac. All acrylic monomers can be polymerized at temperature ranging 50- 140 DegC depending on the type of initiator. The high temperature resin in many cases are not stable due to shellac's instability at high temperature. The preferred polymerization temperature range from 50-120 DegC. The temperature of the reaction depends on the type of initiator used. Shellac having high acid value and low hydroxyl value can be operated at high temperature.

Preferably said free radical initiators are selected from the group of azoisobutyronitrile and the like and the group of peroxides or peroxybenzoates. The peroxide initiator can be selected from alkylhydroperoxie or dialkyl peroxide. t-Butylperoxibenzoate, di-t-butylperoxide and the like.

According to another preferred aspect of the process of the present invention said amine neutralizer is selected from the group of ammonia, alkylamine, N- dimethylethanolamine, N-monomethylethanolamine, ethanolamine,morpholine, N-methylmorpholine and the like.

Said cross linker is selected from the group of amine hardener. Examples of amine cross linkers that can be used include, but are not limited to aliphatic amines, modified aliphatic amines, cycloaliphatic amines, modified cycloaliphatic amines, amidoamines, polyamide, aromatic amines, and the like. Di and polyfunctional amines such as adipic dihydrazide, polyamidoamine, phenalkamine, ethylene diamine, diethylenetriamine, triethylenetetramine, isophorone diamine, diaminocyclohexane,- 4,4'-diaminodiphenylmethane, 4,4'- diaminodiphenylsulfone, dicyandiamide, 1,3-diaminobenzene, 2,4- diaminotoiuene, 2,6-diaminotoluene, 4,4'-diamino-diphenyl methane, 2,4,4'- triamino-diphenyl ether, 2,6-diamino naphthalene, 4,4'-bis-methylene diphenylamine and polyether amine such as commercial Jeffamine. Jeffamine can be selected from polyether diamines and polyether triamines available from Huntsman.

Advantageously, said attained aqueous dispersion/coating compositions can be applied by ragging, brushing, rolling and spraying.

Said coating compositions of the present invention can be top coated with acid catalyzed melamine, Urea formaldehyde resin, 2K polyurethane system and can also be pigmented with colourants, Ti0₂, stainers and additives wherein said additives are selected from the group of wetting agent, dispersing agent, flow additive, defoamers, rheology modifier and optionally a biocide and fire retardant.

The melamine top coating composition is made by melamine in solvent and adding commercially available acid catalyst and melamine in solvent and sprayed on the top of the coating in order to achieve mechanical and aesthetic performance.

The objectives and advantageous attributes of the present invention attained are further exemplified in the non-limiting examples below based on the preparation and application of an aqueous dispersion of an acrylic/ shellac copolymer in presence of a suitable cross linker.

After the shellac is added in a solvent it is generally preferred to heat the solvent to 60-120 Deg C and the -OH blocking agents like maleic acid or acrylic anhydride acrylic are reacted under exothermic reaction. Further blocking with isocyanate is performed in order to get more cross linked urethenised shellac under similar exothermic conditions. The final adduct is now ready for further polymerization using free radical initiator using olefinic monomers selected from the group of styrene, acrylics and optionally other vinyl monomer. Special monomer containing heteroatom can also be used.

The shellac is pre-reacted with maieic or acrylic anhydride and isocyanates to get an adduct with reduced hydroxyl groups and increased carboxylic groups at a temperature ranging from 50-120 Deg C preferably at 80-100 Deg C. The malenisation of hydroxyl group of the shellac leaves an option to further grafting with olefinic monomer. After malenisation the reaction with isocyanate can be performed at temperature preferably at 60-100deg C to get urethenised shellac. In the preceding exercise, the hydroxyl groups of the shellacs are partially blocked reducing the hydroxyl number together with the creation of carboxylic functionalities with a view to increase the dispersion stability of the aqueous acrylated or styrenated acrylic shellac.

The hydroxyl group is pre-reacted with anhydrides of di carboxylic acids or acrylic acid. Maieic or malic anhydride is preferred looking at the cost of the reagent. The amount incorporated by weight may vary in the ranges from 0.2tol0.0 % with respect to shellac weight, the amount, which is sufficient enough to give desired properties and stability of the binder in aqueous medium. Shellac has varying degree of hydroxyl group depending on the source and geographical location. Overall hydroxyl groups of the shellac are reduced both by addition of anhydride and isocyanate. The amount is adjusted in such a way that the water resistance of the coating is acceptable and the dispersion of the polymer does not get affected when water is used as dispersing medium. The anhydride is reacted with shellac solution at temperature ranging from 60 to 120 deg C, preferably at 60-90 deg C to get complete conversion.

The amount by weight of isocyanates may vary from 0.1% to 30% and more, preferably at 0.5% to 20% by weight of shellac used. They are selected from the group or di and polyisocyanate for example triisocyanurate of MDI, TDI, IPDI, HDI and many variants as mentioned elsewhere having isocyanate value starting from 5 to 50%. Isocyanate can be added pre-and post free radical polymerization to get similar effect. Water dispersible isocycnate is preferred in order to get the dispersion more stable. In the preceding paragraph the reaction of shellac with isocyanate or maleic acid gives higher molecular weight polymer leaving an option to further increasing the polymer molecular weight by subsequent polymerization with olefinic monomers by free radical reaction. The free radical reaction can be carried out by using low temperature or high temperature initiator for example, AIBN (azo-iso- butyronitrile) can be used at low temperature and DTBP (di-t-butyl peroxide) or TBPB (t-butylperoxybenzoate) can be used at a temperature as high as 120-140 Deg C.

The monomers are added with stirring by continuous or semi continuous manner containing the free radical initiator. A small amount of free radical initiator can be added onto shellac adduct before the olefinic monomers are added and also at post polymerization, a Chaser catalyst for example, t-butylhydroperoxide is added and reacted for some time followed by redox catalyst to ensure complete polymerization in the presence of reducing agent. An excess of initiator can also be used to completely react the monomer giving less odoured product since monomer give unacceptable odour. In most cases addition of chaser catalyst is not required because the residual monomers can be vacuum stripped or purged with gas before water addition. The solvent level of the polymer hybrid after neutralization step can be distilled under vacuum in order to reduce the volatile organic components to a desired value. The VOC level of the resin can be reduced to below < 15 g/L. The distilled solvent can be recycled if desired in order to reduce the cost of the product. Higher amount of solvent gives better processing ability of shellac having larger sizes especially flakes and lumps.

Many examples of such reducing agents are known. Agents such as hydrazine or a soluble sulfite, including hydrosulfites, sulfoxalates, thiosulfates, sulfites, and bisulfites can be . used. Examples of these are sodium hydrosulfite, sodium metabisulfite, potassium sulfite, zinc formaldehyde-sulfoxalate, and calcium bisulfite. Redox systems may be activated by the presence of a small amount of polyvalent metal ions. Ferrous ions are commonly and effectively thus used, a few parts per million being sufficient. The peroxide catalyst may also be activated by the presence of a tertiary amine which is soluble in the reaction medium, such as dimethylethanolamine or triethanolamine and polyamines such as diethylenetriamine, triethylenetetramine, N-N-dimethyl-p-toluidine and tetraethylenepentamine and the like.

The monomer may contain acrylic acid where maleic anhydride cannot be incorporated in the shellac. The incorporation of maleic anhydride is determined depending on the presence of water in shellac. Too high level of water in shellac affects the coupling reaction with maleic anhydride, in that case, acrylic acid is incorporated in the monomer mixture.

As polymerization catalyst, there may be used one or more peroxides which are known to act as free-radical. Hence, it is preferred to use an organic peroxide as the initiator. Typical organic peroxides include benzoyl peroxide, tert-butyl hydroperoxide, cumene peroxide, tetralin peroxide, acetyl peroxide, caproyl peroxide, di-t-butylperoxide, tert-butyl perbenzoate, tert-butyl diperphthalate and the like. The preferred catalyst is di-t-butylperoxide because the polymerization reaction can be performed at temperature range 120-140 Deg C. The usual range is 0.01% to 3% of catalyst with reference to the weight of the monomer mixture. The preferred range is from 0.05% to 0.8%, while the range of 0.1% to 1.25% is usually workable.

The shellac copolymers of the present invention are those formed of a mixture of 5 to 80% by weight of shellac, 50 to 80% by weight of olefinic monomer comprising esters and amides of acrylic acid with an alcohol having from 1 to 18 carbon atoms, preferably an alkanol having from 1 to 6 carbon atoms, e.g., methanol, ethanol, n-propanol, isopropanol,hexanol, t-butanol and n-butanol, methacrylonitrile including ethylated and methylated acrylics for example ethyl hexyl acrylate. Styrene can be used as one of the co-monomer in a quantities from 1% to 20%. The special monomer like DAAM (diacetone acrylamide), AAEM (acetoacetatoethylmethacrylate) are co-polymersed in a level not less than 1%. The higher level is 20% by weight with respect to the total monomers used.

After polymersation the mixture is treated with both types of amines, one such amines can be of normal or tertiary amines used for neutralizing the carboxylated polymer. The level is so chosen that the PH of the medium can be adjusted from 6.5 - 9.5, preferably at 8.5-9.5. Amine of low odour is chosen such that the final product can be applied with ease. In addition to neutralization, hardener amines are also added to get better drying and recoatability with meiamine. The hardener amine arechosen from the group comprising of polyetheramine, adepic dihydrazide, polyamines like polyamidoamine and phenalkamines and the like as mentioned elsewhere. Renewable polyamines are used in order to give flexibility in the polymer and also gloss retention. Such amines can be selected from the group of fatty amidoamines or fattyamines.The hardener having two functional groups are required, however, polyfunctional hardeners are preferred in order to get the top coatability and hardness with retention of gloss. The weight , per cent may vary from 0.5% to 20 % depending on the mar resistance required and the recoatability is performed. The preferred level of hardeners may vary from 2- 10% by weight of the entire system.

Copolymerization is best accomplished at 85 deg C when AIBN is used and >120 Deg C when DTBP or TBPB is used as the initiator in non aqueous medium. A preferred range is either 60-90 or 120 to 140 deg C, although slightly lower and somewhat higher temperatures are permissible. After most of the monomers have been converted to grafted polymer followed by using chaser catalyst at around 80deg C though higher temperature can be used for completion. Then chaser catalyst can be added to minimize the monomer content. In the process of polymerization here described aqueous dispersion of a mixture of the defined polymerizab!e monomers is stirred and treated with a redox system starting between about 30 C. and about 40 C. About 0.01% to 1% of a peroxidic catalyst based on the weight of the monomers used is usually an effective amount at the start and the required amount of reducing substance, hydrosulfite, sulfite metabisulfite, or the equivalent for this system, may be of the same order or somewhat more by weight when inter polymerization starts.

After the complete polymerization the temperature is reduced to 75-85 DegC and neutralization reaction and cross linking reaction with amine and hardener can be performed . The temperature is then reduced to 50-60 Deg C and water is added to maintain the PH of the medium at 7.0-8.5 while stirring. The preferred PH is 7.5-8.5 where drying becomes much faster and a good dispersion with water stability can be obtained. The polymerization process can be carried out in batch mode or continuously adding monomer reactive mixture in order to get good molecular weight distribution with high solid and gel free dispersion.

The temperature of the mixture rises, usually rather rapidly. Care is taken to keep the temperature of the mixture below the levels at which coagulation might occur.

Amounts of monomers are supplied to bring the content of dispersed interpolymer to 20% to 80% of the total dispersion, preferably30% to 60%. When these monomers are volatile, they can be reduced or removed by steam distillation or stripping under reduced pressure, if so desired in order to reduce the odour of the mixture.

With the attainment of desired interpolymer content in good yield, with or without removal of residual monomers, the dispersion is cooled, cooling to a range of 50 to 30 C. being generally satisfactory.

It is not necessary to add any dispersing or stabilizing agent. Shellac is sufficient enough to hold interaction with the continuous medium and stabilize the dispersion of its own without requiring much of other solvents.

The solvent for shellac dissolution was chosen from the group consisting alkoxyalkyl acetate such as methoxypropyl acetate, ethoxypropyl acetate, alkyl acetate like utyl acetate. Secondary alcohol can be chosen such as isopropanol, t- butanol and the like. The preferred solvents are methoxypropyl acetate or isopropanol. Ketonic solvents can be chosen from MIBK, MEK, methylamylketone and the like. The solvent content in the dispersion may vary from 2%-40% depending on the viscosity required. The solvent can be evaporated after the final polymer or dispersion is made and can be used for recycling. The level of solvent can be made as minimum as possible because shellac itself is a good dispersing agent.

The 'grafted polymer shellac dispersion can be applied on metal, wood or other surfaces directly or it can be mixed with thermosetting melamine system to get a clear coat at temperature in the range 120-150 Deg C.

The copolymer-resin dispersions may be applied for coating or sealer on various substrates to produce a clear sandable coat that can be used for top coating with melamine or 2K PL). The dispersion can also be applied on pretreated wood or metal surface usually treated with silicates, marble powder, zinc oxide or stearate powder before shellac coat to impregnate the pigments or sanding agents along with sealing of the wood surface. The purpose or pretreatment could be for a sanding efficiency or provide opacity or stain/colour onto the surface of the substrate.

The aqueous dispersions or solutions of the present invention may be pigmented or fillers may be introduced for special purposes. Examples of suitable pigments which may be, included in an amount up to 100% by weight of the copolymer blend include titanium dioxide, carbon black, iron oxide, phthalocyanine blues and greens; metal oxides, hydroxides, sulfides, sulfates, silicates, and chromates; organic maroons, aluminum flake, bronze powders, pearl essence, and various fillers or extenders such as talc, barytes, china clay, and diatomaceous earth. The amount of the filler may vary in the range 10% to 75% of the total dispersion depending on the type of applications.

The clear or pigmented copolymer dispersions or solutions may be applied to numerous other substrates including POP, acrylic putty, leather, wood, glass, masonry, such as brick, concrete block, cement, asbestos cements, ceramics, wall-covering and floor-covering materials, such as linoleum, vinyl tile, and felt- base materials. The dispersion can be premixed with alkyd or acrylated alkyd dispersion in order to get a glossy stable enamel. The alkyd can be chemically crosslinked with shellac dispersion by reaction with isocyanate, polycarbodiimide, aziridine and the like.

DAAM -ADH (ADH, adipic acid dihydrazide) or AAEM cross linker are used to get a chemically bound good hybrid polymer for suitable glossy water borne enamel and can be applied on most other substrates with gloss retention. The polymer has cross linkable site like DAAM and AAEM suitable for reacting with amine hardener to form a cross linked polymer during film formation. The cross linking polymer reduces the solvent penetration when top coated with melamine or PU without lifting. The cross linked polymer has higher gloss with better gloss retention than normal shellac. Amine hardeners like ADH or polyamidoamine not only helps to increase the gloss retention but also the hardness and wet look when applied on wood surface.

The following non-limiting examples further illustrate the present invention. Example 1 :

In a 4 necked 1 L round bottom glass reactor equipped with a reflux condenser, a thermometer and a stirrer was added 11.68 gm of dewaxed bleached shellac (having acid value of 150 mg KOH/gm, hydroxyl value ranging 200-220 mg KOH/gm and iodine value of 6-26), methoxypropylacetate 7.3 gm (or isopropylalcohol) and maleic anhydride 2.92 gm and heated to 100 DegC with stirring. Then a trifunctional isocyanate, Essaqua XL-600 (iso value 20.6) was added and reacted for 30 minutes during which an exotherm of around 13 deg C was observed. The temperature was further raised to 140 Deg C. In another round bottom flask a mixture of styrene (5.84 gm), diacetoneacrylamide (4.38 gm), t-BMA (1.48 gm) and tertiarybutylperoxibenzoate (TBPB, 0.23 gm) was made with stirring and then the mixture was drop wise added to the first reactor for a period of 4 hrs at a steady rate and kept under stirring for additional 1 hr for the completion of the reaction. To ensure maximum conversion of the monomer and to obtain a good odour an oxidative chaser catalyst (t- butylperoxibenzoate, TBPB) was used and kept for 30 min. The resulting mixture then was cooled to 75 Deg C and reacted with a mixture of Replamide 326 (polyamidoamine) (1.02 gm), methoxypropylacetate (0.87 gm) and dimethyl ethanolamine (2.04 gm) and stirred for 30 min followed by addition of adipic dihydrazide 2.19 gm mixed with 10 ml of water and stirred for a further period of 30 min. The final reaction mixture was diluted to solid content 30-35% by adding 50-60 gms of water and then cooled to 40 Deg C followed by filtration through 250 mess size cloth and stored in a closed container. The solid level of the water dispersion was 30% by weight.

The resin was further diluted to 15% solid and applied on wood by ragging which coating showed good gloss. The dried film was top coated with amino resin without blister or wrinkles on the surface. Hydroxy value of the shellac in the above process gets reduced by 30-70%, preferably by at least 40% and higher (value in a typical example reduces from 93 mg KOH/gm to 57 or 35). Acid value does not have much significance and can be provided even by monomers and if the stated hydroxyl values are not reached the water resistance becomes poor.

Example 2 (comparative) :

The reaction was carried out without isocyanate addition and its post processing. The resin was diluted and applied on a wood surface. Then it was top coated with melamine aminoresin. The surface of the top coat got cracked and was not acceptable.

Example 3 (comparative) :

The Example 1 was carried out without Replamide 326 (polyamidoamine) . The Top coating was unsuccessful due to lifting. The gloss retention was poor.

Example 4 (comparative) : without maleic anhydride

In a 1L flat bottomed glass reactor equipped with a reflux condenser, a thermometer and a stirrer was added de-waxed bleach shellac ( 17.63 gm), Methoxy propyl acetate (17.63 gm) and the mixture was stirred while raising the temperature to 80 Deg C. Then a mixture of styrene (1.76 gm), diacetone acrylamide (1.32 gm), t-butylmethacrylate (0.88 gm), ^{^}methylacrylic acid (0.17gm) andazoisobutyronitrile (AIBN, 0.07 gm) was added slowlyto the reactor for a period of 4 hrs and stirred for a further period of 1 hr for the completion of the reaction. Then the reaction mixture was cooled to 50-60 Deg C and Essaqua XL-600 (0.52gm)was added during which time a mild reaction isotherm was observed. The reaction mixture was held for 60 min followed by addition of a mixture of liquor ammonia 20 % (7.05 gm). After stirring for 30 mirt. water (52.97gm) .Optionally the solvent level of the reaction mixture can be reduced to desired level by applying a vacuum distillation and can be recycled in the next batch. The resulting mixture was then cooled to 40 Deg C with stirring during which time the adipic acid hydrazide gets fully dissolved. The cooled reaction mixture thus obtained was filtered through 250 Mesh size filter cloth and stored in closed container. The solid level was 22.03%.

The solid was diluted with water to 15% and applied on wood surface by ragging. After drying top coating with amino resin was done. A number of wrinkles though fewer was observed on the surface with slightly whitish colour.

Example 5 :

A wood panel was taken and the surface of the wood was sanded with sand paper. Then took 50 grams of the material ( from Example 1 ) from above and diluted to 20% solid level and applied by ragging or brushing on a wood panel as thin coating multiple times till the grains of the wood are not seen. The panel was kept for drying for 2 days. The gloss level at 85 Deg was 85-90. The water resistance was good without blanching when a drop of water was placed on the panel compared to solvent based wood coating. During applications red and pink pigments available from the market specifically used for wood sealer, were also applied and the coating was applied over the powder giving a smooth finish.

Example 6 :

A paint was made by using material, first mill base prepared by Ti02 ( 18 parts), propylene glycol( 1 parts), Ethylene glycol (1 gram), dipentene (1.3), BYK 199 ( 1.5 parts), synperonic A9 (0.4 parts), defoamer Dapro DF 4164 (0.2parts), Coapur 817 thickener ( 1 parts), Kathone LX (0.5), silane 187(0.2 parts) parts, water 20 parts, and 5 parts of resin from Example 1 in a high speed disperser and after achieving grinding more than 6 on hegman gauze, charge 49.9 parts from Example 1. The paint was diluted by 30-40% water addition and applied on glass plates or wall. The coating had excellent gloss >75-80 at 20 deg and found to have good water resistance and good flow-leveling.

It is thus possible by way of the present invention to provide for shellac-polymer hybrid and dispersions/ coatings comprising the same with improved water and solvent resistance as compared to pure shellac and hybrids known, which in involving chemically converted shellac by malenising or olefininising the shellac followed by urethanisation in solvent mediumand chemically grafting shellac with olefinic monomers including cross linkable monomers and neutralising with combination of amines to further enable cross linking of polymer with amines provides a dispersion of shellac-polymer hybrid that dries fast with good mechanical properties and gloss retention. Advantageously, the solid level is increased to such a level such that the dispersion can be directly applied by brush without sagging in addition to the advantage of application by ragging. Thus the present invention addresses the requirement of providing shellac-polymer hybrid and dispersions/ coatings comprising the same that is water resistance, solvent resistance, stable in aqueous medium and yet is compatible with melamine or PU as top coating to thus facilitate a multicoat of high thickness retaining high gloss. Further gloss retention becomes challenging when water based systems are used and it is difficult to achieve good wet look and hardness of the polymer film with retention of good gloss which the shellac-polymer hybrid and dispersions/ coatings comprising the same of the present invention circumvents, The: disperson being high solid and water being solvent the ragging or brushing can fill the edges of the wood substrate giving advantage over solvent based French polish.

Claims

We Cla im :

1. A shellac polymer hybrid comprising a polymeric reaction product which is urethanised, malenised and/or oelfinised modified shellac with modified hydroxyl value including grafted polymer cross linked with shellac, said polymer hybrid having modified solid levels and favouring increased water and solvent retention.

2. A shellac polymer hybrid comprising a polymeric reaction product having functional cross linkable isocyanate based backbone including urethanised, malenised and/or oelfinised shellac grafted with polymer involving at least one olefinic monomer having at least one cross linkable monomer and crosslinked with amine cross-linker.

3. A shellac polymer hybrid as claimed in claim anyone of claims 1 or 2 comprising a polymeric product of monomers, malenised and/or oelfinised shellac, isocyanate, and at least one amine cross-linker.

4. A shellac hybrid as claimed in anyone of claims 1-3 wherein said monomers involves at least one olefinic monomer and at least one cross linkable monomer.

5. A shellac hybrid as claimed in anyone of claims 1-4 wherein said malenised and/or oelfinised shellac comprises olefinic anhydride modified shellac said olefinic anhydride selected from the group of maleic anhydride, polyisobutylene maleic anhydride, co-polymer of maleic anhydride with olefins and acryloyl or methacryloyl anhydride having at least^J one double bond in it; and wherein said olefinic monomer for grafting are selected from the group of acrylic acid, acrylic esters, acrylic amides, acrylc nitriles, styrene, vinyl acetate, acetoacetate ethyl methacrylate and vinyl versatate(VEOVA) ; and wherein said cross linking monomer is selected from the group of diacetone acrylamide (DAAM) or aceto acetate ethyl methacrylate (AAEM) or combinations thereof; and wherein said isocyanate is selected from the group of aliphatic or aromatic isocyanate including water dispersible isocyanates or its pre-polymer derivative containing at least two isocyanate groups in the molecule preferaby said isocyanates being selected from the group of hexamethylene diisocyanate or its di or trifunctional isocyanurate, isophorone diisocyanate/ or its cyanurates, toluuene diisocyanate, methylenediphenyldiisocyanate.

8. A shellac hybrid as claimed in anyone of claims 1-7 comprise malenised and/or oelfinised shellac including neutral groups as modified hydroxyl groups having 30-70% reduced hydroxyl value preferably reduced by at least 40% enabling increased water and solvent resistance and better film properties.

9. A shellac hybrid as claimed in anyone of claims 1-8 as aqueous solutions or dispersions having compatibility with curable melamine or polyurethane (PU) as top coats including top coats selected from the group of thermosetting commercial melamine amino resins or polyurethane systems based on isocyanate and polyol.

10. A shellac hybrid as claimed in anyone of claims 1-9 as a polymeric dispersion having increased polymer solid levels in the range of 20-50% for direct application by brush without sagging and polymer solid levels the range of 5% to 30% for application by ragging and provides for better film properties that dries fast with good mechanical properties and gloss retention.

11. A process for manufacturing shellac hybrid as claimed in anyone of claims 1- 10 comprising the steps of:

urethanisation in solvent medium; followed by,

12. A process for manufacturing shellac hybrid as claimed in claim 11 comprising the steps of chemically converting hydroxyl groups of shellac by olefinsing shellac, and optionally malenising, urethanisation in solvent medium followed by chemically grafting shellac with a polymer by reacting with olefinic monomers including at least one cross linkable monomer and neutralizing with at least one amine cross linker also aiding further cross linking of the polymer thus attained to yield a polymeric product based dispersion having increased solid levels.

13. A process for manufacturing shellac hybrid as claimed in anyone of claims 11 and 12 comprising the steps of:

a) solubilizing natural or processed shellac in a non-aqueous solvent, reacting with an isocyanate and optionally olefinic anhydride before or after urethanisation followed by grafting a polymer by reacting with olefinic monomers having at least one cross linkable monomer at temperature range 30-150 Deg C in presence of a free radical initiator followed by neutralizing with amine and dispersing the amine polymer adduct in water; b) adding a polyfunctional amine cross linker to the said dispersion before or after neutralization for crosslinking with the functional backbone of the polymer and optionally adding a preservative to obtain therefrom said cross-linked shellac hybrid as a dispersion.

14. A process for manufacturing shellac hybrid as claimed in anyone of claims claim 11 -13 wherein said shellac is natural or processes shellac selected from the group of seed lac, shellac flakes, bleached shellac with or without wax and wherein said non-aqueous solvent for solubilizing shellac is selected from the group of alcohol, ketone, organo ester, organo nitrile, glycolether at the concentration of 1% to 50% by weight of the dispersion.

15. A process for manufacturing shellac hybrid as claimed in anyone of claims claim 11-14 wherein said isocyanate is used in the concentration range 0.1% to 50% by weight of shellac and wherein hydoxy group of the bleached shellac is reacted with isocyanate in the temperature range 50 Deg C to 120 Deg C, more preferable, at 70-90 Deg C .

16. A process for- manufacturing shellac hybrid as claimed in anyone of claims claim 11-15 wherein the shellac is optionally reacted with olefinic anhydride at the levels of 0.1% to 20% by weight of shellac in the temperature ranging from 50-120 Deg C preferably in the temperature range of 80- 100 Deg C and wherein said shellac is reacted with at least one cross linkable olefinic monomer at the levels of 0.1% to 20% by weight of monomers used.

17. A process for manufacturing shellac hybrid as claimed in anyone of claims 11-16 wherein said neutralizing agent is chosen from the group of aliphatic or aromatic amines of the type ammonia, morpholine, trialkylamine, alkylethanol amine such as dimethylethanol amine, aniline, imidazole, polyamine containing at least two nitrogen atom and wherein said amine cross linkers are selected from the group of polyamidoamine, phenalkamine, cycloaliphatic amine, aromatic and aliphatic di and polyamine, more, preferably polyamidoamine or phenalkamine; and wherein said preservatives like anti termite, anti-insect and a biocide are added in an amount sufficient for its efficacy.

18. A paint formulation suitable for application as a primer or top coat including shellac polymer hybrid comprising a polymeric reaction product which is urethanised, malenised and/or oelfinised modified shellac with modified molecular weight including grafted polymer cross linked with shellac, said polymer hybrid having modified solid levels and favouring increased water and solvent retention optionally in combination with anyone or more of pigment, surface active and dispersing agents, extender and additives as non-volatile coating composition suitable for application on a substrate as primer or a top coat.

19. A paint formulation as claimed in claim 18 wherein the shellac polymer hybrid constitutes shellac based binder and said formulation comprises shellac solution at the levels of 5% to 70% by weight of the non-volatile coating and wherein the pigment volume ratio varies from 5% to 75% by weight of paint.

20. A paint formulation as claimed in anyone of claims 18 or 19 for application as water dispersion having 5-40% solid levels and involving water as dispersing medium.