ORGANIC FILM FORMING COMPOSITION

Abstract: A storage stable, room-temperature curable coating composition for wood finishing is described, which is based on a cross-linking system which does not give rise to formaldehyde emission and which comprises, in water or in one or more organic solvents whereof at least one is a mono-functional alcohol combined with a dearomatised paraffin, polymers containing active hydrogen pendant groups, compounds functionalized from carbonyl groups containing compounds, which compounds are hydrates and/or acetals of linear aliphatic or aromatic di- and/or polyaldehydes containing an even number of carbon atoms, but at least 2 carbon atoms in the backbone connecting the carbonyl groups, presented as at least dimers and trimers in cyclic form, acetalated with mono-alcohols selected from ethanol, propanol, butanol, as such and/or modified with hydrogen functional binders selected from polyesters, cellulose derivatives, acrylics or modified polyesters, silica, and a catalyst selected from strong acids and salts thereof.

Description: ORGANIC FILM FORMING COMPOSITION The present invention relates to film forming compositions based on acetal chemistry for use in lacquers and paints, especially in wood finishing coatings without giving rise to additional yellowing from the crosslinking agent, which is free from formaldehyde. The composition is storage stable and is highly reactive at room temperature with or without the presence of any acid catalyst in conditions that do not require any further addition of an amino-formaldehyde resin. The composition uses as crosshnker cyclic dimers and trimers acetals derived from aliphatic linear or aromatic di-aldehydes having an even number of atoms in the backbone chain connecting the two aldehyde groups and mono-alcohols. The compositions according to the instant invention may be presented both as solvent borne systems and as water borne systems. The present invention relates to a coating system non-penetrating on porous substrate which gives at least 30% reduced solvent emission compared to the formulations now in service when used as a solvent borne system and practically free from any solvent emission without any risk for fibre swelling when presented as a water borne system. Prior art Increasing concern regarding the formaldehyde emission during either the curing process or as long term emission by wood coated surfaces has initiated the development of formaldehyde free systems. Acid curing systems are defined as crosslinkable lacquers, which contain as reactive crosshnker an amino resin of melamine/ urea/ guanidine-formaldehyde type, which gives rise to formaldehyde emission. All acid curing systems as defined above give rise to formaldehyde emission when drying at a level of 0.1-0.2mg/ lOOg wet lacquer according to the NIF-method (cf Article No. 3-82, November 1982) from Scandinavian Paint and Printing Ink Research Institute, a value which is interesting from the point of view of safety regulations. Further, the use of an acid curing system on a particle board based on an acid curing glue containing as a buffer NH4CI gives rise of dichlor- dimethyl ether. Different approaches have been made to improve the quality of the amino resins to comply with the request of a low formaldehyde emission during the curing process as well as the long term emission. Different systems have previously been proposed, exclusively related to solvent borne formulations, viz. • acetalated acrylic resin crosslinked with a polyhydroxyl containing monomer which is described in US Pat. 4,663,410, and EP 0 201 693 • poly-hydroxylated resin based on polyvinylalcohol and poly-vinyl-acetate which is sprayed with a second component containing a diacetal which is described in US Pat. 4,655,841 • a poly-hydroxylpolymer, a hexaalkoxy methylolmelamine and a polyacetal and acid catalyst, which is described in US Pat. 5,155,170. Furthermore, it is usual to use polyurethane based systems comprising a crosshnker such as high molecular weight polyisocyanate in combination with hydroxyl functional polyesters or polyacrylates as an alternative in formaldehyde free system. However, the presence of free isocyanate groups give rise to environmentally dangerous products by handling, exposure as well as when disposing of residual products. Attempts to obtain formaldehyde free water borne systems based on self crosslinkable polymer emulsions/dispersions often require the presence of a metal like Zn or/and Zr. Attempts to reduce the formaldehyde emission from lacquers comprise inter alia the use of additives reacting with formaldehyde such as ethylene-urea, peroxides, organic sulphites, acetyl-acetone modified resins, cf. EP 0 043 036, which reduces the emission to about 0.1 mg/m 3 . The emission values in this specification and claims have been determined according to The European Standard prepared by the Technical Committee CEN/TC 112. Description of the invention The present invention relates to coating compositions with low formaldehyde emission practically well below the normal background emission and which is at most 0.005 mg/m 3 or no emission at all and certainly free from any emission of di- chlor-di-methylene-ether. The coating compositions as a solvent borne system according to the invention are based on essentially formaldehyde free crosslinking system comprising, in two or more organic solvents whereof at least one is a monofunctional alcohol and one is an aliphatic hydrocarbon, polymers containing active hydrogen, compounds functionalized from linear aliphatic or aromatic di- carbonyl compounds with even number of carbon atoms in the backbone connecting the two functional groups presented as cyclic oligomers, at least dimers and/or trimers with or without any help of a catalyst selected from strong acids and salts thereof.. The present invention more specifically relates to a storage stable, room temperature curable coating composition for wood finishing, non-penetrating into porous substrates, free from iso-cyanates and metal chelates, based on a crosslinking system which does not give rise to formaldehyde emission and which comprises, in water or in two or more organic solvents whereof at least one is a mono-functional alcohol and one is an aliphatic hydrocarbon, polymers having active hydrogen functional groups; compounds functionalized from aliphatic linear or aromatic di-aldehydes containing an even number of carbon atoms, at least two carbon atoms, in the chain connecting the carbonyl groups, which compounds are acetals with mono-alcohols in a molar ratio of 1 to 1, presented as cyclic dimers and trimers of di-, and/or poly-aldehydes selected from glyoxal, succin-aldehyde, adipic-aldehyde, octandial, phtal-aldehyde, terephtal-aldehyde, as such or/ and modified with binders containing pendant hydrogen functional groups selected from polyesters, cellulose derivatives, acrylics, or modified polyesters; and optionally a catalyst selected from strong acids and salts thereof. The organic film forming composition according to the present invention comprises the reaction between hydrogen active pendant groups of the binder and carbonyl functionalized groups of a cyclic oligomer, at least as dimer and/or trimer in a equiv./ equiv. ratio in the range of 0.3-2, preferably 1-1.2 in solvent borne systems and 2-10 in water borne systems depending on the minimum film forming temperature of the anionic dispersion. The polymers containing active hydrogen comprise: • hydroxyl groups -OH • primary and secondary amino groups -NH2, -NH and/or amide-groups-CO-NH- • acetylacetone groups -CH2-CO-CH2-CO-CH3 or enolisable aldehyde groups. The essential formaldehyde free crosslinking system according to the present invention contains oligomer compounds, at least cyclic dimers and trimers, functionalized from carbonyl derivatives, in the form of semi-acetal, acetal, ketal and/ or hydrated groups. In this specification and in the claims the expression compound functionalized from a carbonyl containing compound refers to all these types of carbonyl derivatives. Optionally, the third component in the crosslinking system, according to the present invention, is a catalyst, selected from strong acids, i.e. p-TSA, H2SO4, H3PO4 and derivatives, HC1, in protic solvents such as methanol, n-propylalcohol, i-propylalcohol, n-butanol, i-butanol, sec-butanol, or similar and mixtures thereof. The hydroxyl functional polymers with active hydrogen which can be used in the crosslinking system according to the present invention includes such polymers, presented as organic solvent solution or as water anionic dispersion, as: 1) Conventional cellulose derivatives such as: • nitro-cellulose containing approximately 2-4 hydroxyl groups/ kg and nitrogen at a level of 11.5-12.5%, and an elementary molecular weight of 263.7 • cellulose aceto-butyrate with at least one hydroxyl group per unit anhydrous glucose. • cellulose aceto-propionate with at least one hydroxyl group per unit anhydrous glucose • cellulose ethers, methyl or ethyl, with at least one hydroxyl group per unit anhydrous glucose. 2) Hydroxyl functional polymers: • oil-free polyester with a hydroxyl functionality in the range of 25mg KOH/g up to 950mg KOH/g, suitably 35mg KOH/g up to 650mg KOH/g • synthetic fatty acids with a hydroxyl functionality of 25mg KOH/g up to 800 mg KOH/g, suitably 35mg KOH/g up to 260mg KOH/g, • acrylic or vinyl polymers and/ or copolymers with a hydroxyl functionality of 25mg KOHg up to 1275mg KOH/g, preferably 25-200mg KOH/g, • aqueous anionic polymer dispersions based on acrylic/methacrylic/styrene copolymers having a hydroxyl functionality of approx. lOOmgKOH/g and a pH value of 1.5-2.4 • aqueous anionic dispersions based on hydroxyl functional polyesters, alkyds, and cellulose derivatives • oxirane-free epoxy resins containing hydroxyl functional groups having a molecular weight of 800-6000, as such, and/ or as epoxy esters with fatty vegetable oils and/ or amino-adducts, • hydroxyl functional aldehyde and/ or ketone resins with a melting point of 75-170°C and an average hydroxyl functionality between 50 and HOmg KOH/g • rosin derivatives esterified with polyols like glycerol, penthaerythritol having a melting point of 90-130°C and a hydroxyl number of at least 80mgKOH/g. 3) Polymers containing amino/ amide groups obtained by condensation of dimer fatty acids with di-amines and/ or by blocking in part or completely the hydroxyl/ carboxyl functionality of the previously described polymers with mono- or/ and di-isocyanate compounds such as phenyl-isocyanate, cyclohexyl-isocyanate, TDI, MDI etc. 4) Polymers containing acetylacetone functional groups and/ or enolisable aldehyde groups as described above with t-butyl-acetylacetone. Such polymers as described above having hydroxyl functionality and/ or amino/ amide functionality and/ or acetylacetone or enolisable aldehyde groups are used to crosslink with carbonyl functional compounds presented at least as cyclic dimers and trimers containing at least two carbonyl groups presented as hydrates or acetals. Examples of typical reactions involved in this crosslinking process used in the present invention are illustrated in reaction scheme l)-3) wherein the general formula of the carbonyl derivative is: ( I ) and (II) I (CH2)n I ( I ) RiO - CH - O O - CH - OR3 I \ / I I / \ I R2O - CH - O O - CH - OR4 ( II ) 1) polymer-OH+ (I) +HO-polymer^ polymer-0-CRιR2-0-polymer 2) polymer-NH2 + ( I ) + 2HN-polymer-^polymer-NH-CRιR2-HN-polymer 3) polymerOCH2-CO-CH2-CO-CH3+(I)-^polymerOCH2-CCRιR2-CO-CH3 where: n=0, 2,4,6, Rl=H, C n.H 2+l ,n =0,1,2,3, R2=Η, C n.H 2+l ,n =0,l-2,3. , HSi2θ 5 R3=polymerbackbone, -(CnH2n)-0-R4, n=o,ι,2,3, R4=polymerbackbone,Rι ,R2 The compound functionalized from a carbonyl containing compound shall contain an even number of carbon atoms, at least 2 carbon atoms, and at least one group functionalized from carbonyl selected so that the boiling point at the carbonyl derivative is at least 21°C. The highest derivative in the series is a polyacetal which has a maximum carbonyl functionality of 450mg KOH/g and a molecular weight of 20 000. The carbonyl derivative is presented as dimer and/or trimer and there is in a molar ratio of 1.0-1.5 M/0.2-1.2M water/0.5-2.0M alcohol functionalised. The organic solvent mixture to be used must always contain a monofunctional alcohol and an aliphatic hydrocarbon. Other components of the solvent mixture if several organic solvents are used can be selected from esters, alcohols and glycol ethers. For thixotropy and suspension stability the use of colloidal silica ( fumed silica ) is recommended in combination with a wetting agent selected from poly- hydroxy-carboxylic acid amides that prohibits the particle agglomeration of the mentioned silica. The water borne composition may optionally contain a small amount of hydrophobic fumed silica. The molar ratio between the mono-functional alcohol and the acetyl functionality shall be in the range of from 1 : 1 to 10: 1. The catalysts used in the composition according to the present invention are strong acids in accordance with the desired network polymer and/ or the starting point formulation, i.e. the functional groups involved in the curing process, but when an aqueous anionic dispersion is used no catalyst is required at a pH range of 1.1 up to 2.5. The acid catalyst when required shall be used in such an amount that equiv. H+/equiv. HC=0 ratio is at most 0.2, preferably 0.001-0.05 (suitably about 0.02). In the formulations it is suitable to use hydrogen active (from binder) to carbonyl (from carbonyl derivatives) in such amounts that the ratio in the sealer lacquer from 0.3 to 1, preferably 0.6-0.8 and in the top lacquer from 0.5 to 2.0, preferably 0.8-1.2. In a suitable embodiment of the coating composition according to the present invention it also combines a condensation reaction between a polyacetal reactive compound and a hydrogen active oligomer selected from polymers modified with unsaturated fatty acids of vegetable, animal and synthetic origin capable to crosslink through an air-drying mechanism, optionally but not recommended, catalysed by metal ions such as Co, Fe, Mn, Zr, in no other form than acetyl- acetonates at a level of 0.01-0.1 % based on non- volatile content of composition. In an another suitable embodiment of the coating composition according to the present invention the composition comprises a crosslinking system based on solvent borne cellulose derivatives, a carbonyl derivative where the active species are stabilised by means of a strong acid which is also catalyst in further reaction with H-active functional polymers whereby improved resistance against discoloration is obtained. The composition of the present invention may be modified by the addition of additives and ingredients which normally are added to paint and lacquer compositions such as conventional amount of fillers, pigments, reinforcing agents, mar, slip and flow control agents, flattening agents, levelling agents etc., selected so as to be compatible with the system. The surface active additives should be carefully selected from those which are not containing functional groups such as hydroxyl, amino/amido, poly-ether. The compositions of the present invention can be applied to wood, plastic and metal substrates as such or in combination with other sealers or top coats. The composition according to the present invention has an emitted (form)aldehyde level within 24 hours of less than 0.01mg/m 3 experimentally detected 0.002- 0.004 mg/m 3 of the most volatile carbonyl compound. A cured sealer made by the composition according to the present invention provides a coating surface which is not dissolved by any usual top layer used in the wood finishing industry. The carbonyl derivatives used in the composition according to the present invention are liquids at room temperature and have a boiling temperature higher than 60°C, a viscosity of 53-62" DIN cup 4 mm and a density of 1.11±0.005 g/cm 3 . The composition according to the present invention provides a high built finishing on wood surfaces and has a non-volatile content of about 30-50% at room temperature and at application viscosity. The finishing coating according to the present invention exhibits very good properties that impart recoatability, sandability, stain and chemical resistance without any aldehyde emission caused by the coating, all of which properties mean that the coating composition is superior to both classic acid curing systems and polyurethane systems not least for environmental reasons. The following comparison with characteristic acid curing systems according to the prior art, polyurethane based systems according to the prior art and water borne systems according to the prior art which is presented below clearly shows that the composition according to the present invention must be regarded as an important advance in the paint industry. Examples The constituents of the composition of the present invention are blended together with methods conventional within the paint and lacquer industry. The invention is illustrated by means of the following examples, wherein the preparation of the organic film forming formulation embodies different crosslinking systems in accordance with the present invention. The following lacquers were produced according to the instant invention using conventional blending and agitation methods. All these systems involve chemical reactions such as these previously described catalysed by acids or in certain cases by alkalis. The coating compositions were applied on wood or glass panels by means of an applicator in a thickness of between 80 and 150μm wet and dried 24h at room temperature. Example 1 Parts by weight Butyl acetate 9.015 Dearomatised paraffin(bp.150- 190°C) 5.000 Etyl acetate 5.500 Ethanol 6.798 Nitro-cellulose/ 65%EtOH (11.1 % N) type E510 8.959 Alkyd resin 53.230 • 70%o in butyl acetate • OH=170mgKOH/g, • Oil content 49%, • type of oil -vegetable oil Flattening agent (silica) 2.500 Crosshnker (cyclic dimer and trimer of glyoxal, IM glyoxal/ IM 8.700 EtOH, 5%by weight hydrophilic silica) Leveling agent (silicone type ) 0.298 100.000 Catalyst 2-etylhexyl acid phosphate 0.232 Ethanol 4.750 Butyl acetate 5.018 10.000 The lacquer has the following parameters: Non- volatile content 50% Kόenig hardness after 24 h 100 Aldehyde emission after 24h <0.005mg/m 3 Pot life at 23.3°C >72h Example 2 Parts by weight Butyl acetate 11.395 Ethanol 6.498 Nitro-cellulose (E510, 11.1 % N, 65%EtOH) 8.954 Oil free polyester 53.230 • 75%o in Butyl acetate, • modified with 45% iso-nonan acid, • functionality OH 165mgKOH/g Crosslinker( 1 M glyoxal, 1 M n-butanol, cyclic dimer/trimer) 10.440 Flattening agent (polyethylene wax type) 2.000 Levelling agent (silicon type) 0.200 Dearomatised paraffin (bp.95- 110°C) 7.283 100.000 Catalyst Phosphoric acid 0.300 p-TSA 3.300 Ethanol 6.400 10.000 The lacquer has the following characteristics Pot life at 23.3°C Higher than 48 h Aldehyde emission after 24 h <0.01 mg/m 3 Non-volatile content at spray viscosity 35-40% Koenig hardness 70-80 Example 3 Parts by weight Butyl acetate 21.200 Dearomatised paraffin (bp. 150-190°C) 14.600 Wetting agent (silicon type ) 0.200 Talc mono mix 2.000 Flattening agent (wax type ) 0.400 Flattening agent (silica type) 1.000 Nitro-cellulose ( E510 type, 11.1 %N, 65%n-butanol) 13.400 Alkyd resin 23.700 • 75%o in butyl acetate • hydroxyl functionality 170 mg/g , • tall oil content 57% Levelling agent (silicon type ) 0.500 Ethanol 8.600 Ethyl acetate 14.400 100.000 Crosshnker Alkyd resin 15.000 • 75%o in ethanol • hydroxyl functionality 175mg/g , • tall oil 53% p-TSA 3.300 Crosshnker (cyclic dimer/trimer, 1 Mglyoxal/ 1 M EtOH) 6.700 25.000 The lacquer has the following characteristics Pot life at 23.3°C >48h Aldehyde emission after 24 h, mg/m 3 <0.005 Example 4 Parts by weight Alkyd resin 20.970 • 75%> in butyl acetate • hydroxyl functionality 150-175 mg/g • oilcontent 51 -57% tall oil Nitro-cellulose E400 type (65%butanol) 6.648 Butyl acetate 13.872 Wetting agent (silicon type ) 0.100 Wetting agent (polyamide type ) 0.180 Butyl acetate 14.000 Bentone 0.600 Fumed silica (hydrophilic type ) 1.800 Talc 10.300 English kaolin 9.200 77.670 After dispersion let down with Butyl acetate 7.000 Dearomatised paraffin 5.000 Crosshnker (IM glyoxal/ IM n-butanol, cyclic dimer and trimer ) 3.860 Phosphoric acid 0.070 p-TSA 0.200 Butanol 6.200 100.000 The clear surfacer as above has one year storage stability and is intended for electrostatic spraying. The clear surfacer gives no rise of aldehyde emission and has a very good sandability and recoatability. Example 5 Parts by weight Butyl acetate 36.380 Flattening agent 0.270 Talc 1.330 Wetting agent, polyamide type 0.270 Nitro-cellulose,E400 )65% n-butanol) 9.670 Alkyd resin 30.610 • 75%in butyl acetate, • hydroxyl functionality 155 mg/g Fumed silica, hydrophilic type 0.800 p-TSA 0.230 Phosphoric acid 0.070 Levelling agent, silicon type 0.340 Crosshnker (IM glyoxal/ IM n-butanol, cyclic dimer and trimer) 5.340 n-butanol 8.550 Dearomatised paraffin 5.340 100.000 The clear coating system has following parameters: Non- volatile content 35 % Storage stability at room temperature 1 year Kόenig hardness after 24 h 70 Example 6 Parts by weight Acrylic anionic dispersion 58.000 • 43-47% non-volatile content • hydroxyl functionality lOOmgKOH/g solid resin • pHl.2-2.4 • viscosity at 23°C 17-23 mPas • particle size 0.2μm • minimum film forming temperature 60°C Defoamer (paraffin type 10% in water) 5.000 Flattening agent 35% in water anionic type wax 2.000 Flattening agent, hydrophobic silica type 2.000 Water 18.000 Crosshnker (1 Mglyoxal/ IM n-butanol, cyclic dimer and 14.600 trimer ) 100.000 The organic film forming composition requires no further coalescence solvent and has the following parameters: Non-volatile content 44% Viscosity, DIN cup4 mm 16-20" Acetone resistance after 24 h Unmodified surface Acetone resistance after 72 h Unmodified surface Storage stability at room temperature 1 year Example 7 Parts by weight Acrylic anionic dispersion 61.550 45% non-volatile content hydroxyl functionality 100-150mgKOH/g pH 1.2-2.4 viscosity at 23°C 17-23 mPas particle size 0.2μm minimum film forming temperature 35°C Defoamer (paraffin type 10 % in water ) 5.000 Flattening agent 35 % in water , anionic type wax 2.000 Flattening agent, hydrophobic silica 2.000 Water 18.000 Crosshnker (IM glyoxal/ IM n-butanol cyclic dimer and 11.450 trimer ) 100.000 The organic film forming composition requires no further coalescence solvent and has the following parameters Non- volatile content 43% Viscosity, DIN cup 4mm 16-20" Acetone resistance after 24 h Unmodified surface Acetone resistance after 72 h Unmodified surface Storage stability at room temperature 1 year Example 8 Parts by weight Acrylic anionic dispersion 72.400 • 43-47% non-volatile content • hydroxyl functionality lOOmgKOH/g solid resin • pHl.2-2.4 • viscosity at 23°C 17-23 mPas • particle size 0.2μm • minimum film forming temperature 60°C Defoamer (paraffin type 10 % in water 5.000 Flattening agent 35 % in water , anionic type wax 2.000 Flattening agent, hydrophobic silica type 2.000 Water 9.000 Crosshnker (0.363Mglyoxal/0.289M water/0.348M 4.600 butanol ) Butylglycol 5.000 100.000 The organic film forming composition has the following parameters Non-volatile content 42% Viscosity, DIN cup 4mm 18-25 " Acetone resistance after 24 h Unmodified surface Acetone resistance after 72 h Unmodified surface Storage stability at room temperature 1 year Example 9 Parts by weight Ethanol 0.270 Flattening agent , wax 1.330 Wetting agent, polyamide type 0.270 Nitro-cellulose, A500 (65% EtOH) 9.670 Alkyd resin 30.600 • 75%in EtOH, • acid number 25mgKOH/g, • hydroxyl functionality 155mgKOH/g, • oil length 53%, tall oil Fumed silica, hydrophilic type 0.800 Flattening agent, silica 0.800 p-TSA 0.230 Phosphoric acid 0.070 Levelling agent, silicone type 0.340 Crosshnker (IM glyoxal/ IM n-butanol, cyclic dimer and trimer) 5.340 Butanol 8.550 Dearomatised paraffin 15.340 100.000 The coating clear system has the following parameters Non-volatile content 35% Storage stability at room temperature 1 year Koenig hardness after 24 h 70 Example 10 Parts by weight Water 8.3754 Thickener (polyurethane type ) 1.3068 Bentone 0.2376 Wetting agent (acrylic type ) 0.7722 Water 15.5628 Micro talc 13.7214 Kaolin 9.0882 Titanium dioxide 10.3356 Butylglycol 1.0000 Acrylic anionic dispersion 32.1000 45%o non- volatile content hydroxyl functionality 100-150mgKOH/g pH 1.2-2.4 viscosity at 23°C 17-23 mPas particle size 0.2μm minimum film forming temperature 35°C Crosshnker ( 1 M glyoxal/ 1 M n-butanol ) 7.5000 100.0000 The surfacer has the following parameters Storage stability at room temperature 1 year Sandability lh after application Very good Recoatability lh after application with water borne top paint Very good with solvent borne aromaticfree top paint Very good

Claims: Claims 1. An organic film forming composition , non penetrating on porous substrates that may be presented as either a solvent borne system or as a water borne system based on a crosslinking system derived from linear aliphatic or aromatic di- and poly- aldehydes having an even number of carbon atoms in the backbone chain connecting the two aldehyde groups, presented as cyclic dimers and/or trimers hydrates and/or acetals with mono-alcohols such as methanol, ethanol,n-propanol, iso-propanol, n-butanol, sec-butanol, isobutanol. 2. A room-temperature curable coating composition non penetrating on porous substrate, preferably, but not exclusively, for wood finishing, based on a crosslinking system which does not give rise to formaldehyde emission and which comprises as a solvent borne system, in two or more organic solvents, whereof at least one is a monofunctional alcohol and one is an dearomatised aliphatic hydrocarbon, polymeric compounds containing active hydrogen compounds functionalized from linear aliphatic or aromatic di-aldehydes with an even number of carbon atoms which are hydrates and/ or acetals of mono- alcohols and /or hydrogen functional binders selected from polyesters, cellulose derivatives, acrylics, or modified polyesters; and optionally a catalyst selected from strong acids and salts thereof. 3. A room-temperature curable coating composition non penetrating on porous substrate, preferably, but not exclusively, for wood finishing, based on a crosslinking system which does not give rise to formaldehyde emission and which comprises as a water borne system, compounds functionalized from linear aliphatic or aromatic dialdehydes with an even number of carbon atoms in the chain connecting the two aldehyde groups which are cyclic at least dimerised and trimerised hydrates and/ or acetals of mono-alcohols and /or hydrogen functional binders selected from polyesters, cellulose derivatives, acrylics, or modified polyesters presented as water anionic dispersions with or without any help of a catalyst selected from strong acids and salts thereof. 4. A coating composition according to claim 1, which does not give rise to any kind of aldehyde emission during the drying process when the carbonyl derivative used is an acetal functionalized carbonyl group provided by a di- aldehyde containing an even number of carbon atoms presented as cyclic derivative in at least dimer and trimer form, optionally functionalised with water in the molar ratio of 1 to 0.8 aldehyde /water and respectively acetalated in a molar ratio of 1/0.9-1 aldehyde/mono alcohol, selected from glyoxal, succin-aldehyde, adipic-aldehyde, octandial, phtalaldehyde, terephtalaldehyde. 5. A coating composition according to any of the preceding claims, in which the crosslinking system comprises an equivalent of active hydrogen per equivalent functionalized carbonyl group in the range of 0.3-7, preferably 1.0-1.2 for solvent borne systems and 3-7 for water borne systems. A coating composition according to any of the preceding claims characterised in that the compound functionalized from a carbonyl compound is derived from a di- or polyfunctional aldehyde with an even number of carbon atoms presented as cyclic dimers and /or trimers in a low molecular weight monofunctional alcohol or combination thereof in a molar ratio of 1-1.5/1-1.2. 7. A coating composition according to claim 2, characterised in that the molar ratio between the monofunctional alcohol and the acetal and/ or ketal functionality shall be in the range of from 2:1 to 10:1 and the weight ratio mono-alcohol/dearomatised paraffin is 1/0.5-1.5 in the delivery form. 8. A coating composition according to claim 1 that when presented as a water borne system eventually does not further require any other solvent either as coalescence solvent or for further stabilisation of the formulation, and the fullness of the film as well as the reactivity is controlled through the ratio of acetalisation of the di-aldehyde. 9. A coating composition according to any of the preceding claims characterised in that it as polymer with active hydrogen includes one or several polymers selected from polyesters, aldehyde resins, acrylic homo-polymers and copolymers, oxirane free epoxy resins and/ or derivatives, cellulose derivatives containing hydrogen active groups, acetylacetone groups or any mixture thereof presented as solutions in organic solvents such as esters, alcohols, paraffin hydrocarbons as such or as mixture thereof or as water borne anionic dispersions or emulsions. 10. A coating composition according to claim 2 characterised in that the catalyst is a strong acid selected from HC1, H3PO4, phosphoric acid alkyl derivatives, H2SO4 and /or alkyl or aryl derivatives like p-toluene sulphonic acid and/or salts thereof acting in a mixture of solvents with lower polarity due to the presence of an dearomatised paraffin where the ratio by weight between the ester solvent and the dearomatised paraffin is 0.8-1.0 / 1.0-0.8 at the application form. l l.A coating composition according to claim 2, characterised in that the second solvent is an dearomatised aliphatic hydrocarbon with a boiling point within the range of 85-130°C up to 150-190°C, having a precipitating effect on the pre- condensed polymers of the organic film forming composition when the high volatile solvents are released and hence the control of the fullness of the layer . 12. A coating composition according to claim 1, characterised in that the crosslinking agent is a poly-acetal functionalized compound obtained by a condensation reaction between a di-aldehyde with an even number of carbon atoms and an oligomer with poly-hydroxyl functionality in which the ratio between di-aldehyde and OH equivalent is at least 1 mole di-aldehyde to 1 hydroxyl functional group, thereby forming pendant acetal groups. 13. A coating composition according to any of the preceding claims which has a high non-volatile content of about 30-50% at the delivery form, a long pot life and storage stability, and gives a crosslinked product with excellent sandability and recoatability giving no risk of formaldehyde or di-chlor-di methylene-ether emission. 14. A solvent borne coating composition according to any of the preceding claims that is not penetrating into a porous substrate such as wood due to the pre- condensation effect in the presence of the paraffinic hydrocarbon, and therefor gives a reduction of at least 30%o solvent release at the same optical impression given by the used one pack or two pack solvent-borne systems. 15. A water borne coating composition according to any of the preceding claims that is not penetrating into a porous substrate such as wood due to the high pre- condensation degree of the highly reactive cyclic dimers/trimers acetals derived from di-aldehydes with an even number of carbon atoms in the molecule on the surface of the anionic dispersion particles. 16. A coating composition according to any of the preceding claims where the presence of acetalated compounds derived from di-carbonyl derivatives such as aldehydes having an even number of carbon atoms does not require further addition of fungicides and/or preservatives. 17. A solvent borne coating composition according to any of the preceding claims where the fullness of the dried film can be controlled by the variation of the ratio between cellulose derivatives and the amount of the crosshnker expressed as di-aldehyde in the interval 2.47-8.45 parts by weight dried cellulose derivatives / 0.20-0.35 moles of di-aldehyde. 18. A water borne coating composition according to any of the preceding claims where the fullness of the dried film and the resistance to acetone is controlled through the ratio between the polymer (as solid resin) and the cyclic crosshnker in the range of 1.5-3 /l . 19. An organic film forming composition according to any of the preceding claims where, when an alkyd is used, the solvent resistance of the crosslinked film is controlled by the ratio between the oil content of the alkyd and the number of equivalents of carbonyl derivative, preferably 10-14%) oil content from the alkyd on total composition / 0.2-0.35 carbonyl equivalent for a formulation having approximate 40%o non- volatile content. 20. An organic film forming composition according to any of the preceding claims, based on cyclic dimers and trimers derived from acetalated polymerised di- aldehydes with an even number of carbon atoms, where as a tixotropic agent a hydrophilic silica type optionally is used in the range of 0.2-2.8%) on total formulation, without any adverse effects like agglomeration when an wetting additive selected from polyhydroxylcarboxylic acid amide or poly-amide modified poly-siloxanes is involved, where the acetalated cyclic crosshnker is in a weight ratio with the colloidal silica of at most 2: 1.

Inventors: MANEA MIRCEA MIHAI, MANEA, MIRCEA, MIHAI
Applicants: WEDEVAAG FAERG AB
Application year: 1998
Main classification: C09D161
IPC codes: C08F8, C08L59, C08L67, C09D159, C09D163, C09D167