WO2000040662A1 - Coating compositions - Google Patents

Abstract

A coating composition comprising: (a) a copolymer obtained by vinyl polymerisation of: i) at least one ethylenically unsaturated monomer; and ii) at least one (alkyl)acrylate ester of formula A-Z-B wherein: Z is a saccharide group, A is a group of formula (I), wherein X can be absent or is a group OR' in which R' is a C1-8 alkylidene, phenylidene or benzylidene group, Y is an optional spacing group, R is H or C1-4 alkyl, and B is H or a C1-8 alkyl, phenyl or benzyl group; the groups A and B being substituted in any order on a primary hydroxyl position of the saccharide group and the glycosidic position of the saccharide group; (b) a cross-linker for the hydroxy groups of the saccharide group; and (c) a solvent or diluent.

Description

COATING COMPOSITIONS

The present invention relates to coating compositions which are obtainable from cheap and renewable starting materials, in particular materials which can be used as replacement for petroleum derived products.

Coating compositions comprising a solution or dispersion of a copolymer and a crosslinker in a solvent or diluent are known. They find application in a wide variety of uses, for example as paints, for example decorative or household paints or paints for vehicles such as refmish paints. The film-forming polymer is usually prepared from monomers derived from petroleum. It is desired to replace these monomers with monomers derivable from renewable sources.

Conventional coating compositions, for example those used in vehicle refmish coatings, have a relatively short pot life after they are formed, typically of a few hours. It would also be desirable to provide a coating composition which has a longer pot life. It would additionally be desirable to provide a coating composition which can cure more quickly and/or which can provide a coating with a greater final hardness.

We have found a coating composition which includes a polymer formed at least in part from monomers obtainable from renewable sources. The properties can easily be tuned to provide one or more of the above advantages as desired. This coating composition comprising a copolymer comprises units derived from a sugar having acrylic or alkylacrylic groups attached.

The present invention accordingly provides a coating composition comprising:

(a) a copolymer obtained by vinyl polymerisation of:

i) at least one ethylenically unsaturated monomer; and

ii) at least one (alkyl)acrylate ester of formula:

A-Z-B

wherein:

Z is a saccharide group,

A is a group of formula

R

-X -O - C -Y -C = CH₂

II

O

wherein X can be absent or is a group OR' in which R' is a Cι_-8 alkylidene, phenylidene or benzylidene group, Y is an optional spacing group, R is H or C alkyl, and B is H or a Cι_-8 alkyl, phenyl or benzyl group; the groups A and B being substituted in any order on a primary hydroxyl position of the saccharide group and the glycosidic position of the saccharide group;

(b) a crosslinker for the hydroxy groups of the saccharide group; and

(c) a solvent or diluent.

The present invention also provides a multi-component pack, for example a two- or three- component pack, suitable for forming a coating composition as defined above which comprises, in one component, the copolymer and a diluent and, in a second component, the crosslinker and optionally a diluent.

The present invention additionally provides the use of a copolymer as defined above in the preparation of a coating composition.

The present invention further provides a substrate coated with a cured coating composition as defined above.

The present invention yet further provides a process for preparing a coating composition as defined above which comprises mixing together the copolymer, crosslinker and solvent.

The copolymer which is present in the coating composition of the invention is derived from at least one ethylenically unsaturated monomer and at least one (alkyl)acrylate ester as defined above.

The ethylenically unsaturated monomer may be a functional monomer other than the (alkyl)acrylate ester of a glycoside, or a non-functional monomer. The monomer must have a carbon-carbon double bond and may, if desired, contain other groups.

Functional monomers are, for example, hydroxyl functional vinyl or (meth)acrylic monomers. An example of a hydroxyl vinyl monomer is vinyl alcohol. Examples of hydroxyl functional acrylic monomers are hydroxy containing esters of acrylic or methacrylic acid such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

Other examples of suitable hydroxyl functional acrylic monomers are the reaction products of glycidyl (meth)acrylate with mono-carboxylic acid, such as versatic acid or the reaction products of (meth)acrylic acid with glycidyl functional compounds such as Cardura E10 (trade mark of Shell).

Non-functional monomers do not have functional groups which will react with the crosslinker. Examples of non-functional monomers are alkyl esters of (meth)acrylic acid, and non-functional vinyl monomers. Examples of suitable alkyl esters of (meth)acrylic acid are C_M2 alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and n-butyl (meth)acrylate. Examples of non-functional vinyl monomers are styrene and alpha-methyl styrene, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, isobutyl (meth) acrylate, ethyl hexyl (meth)acrylate, and lauryl (meth)acrylate. Preferred non-functional monomers include styrene, alpha-methyl styrene, methyl methacrylate, butyl (meth)acrylate, tertiary butyl (meth)acrylate, and isobornyl (meth)acrylate.

Preferred copolymers comprise 5 to 50 wt% of styrene or alpha-methyl styrene based on the total weight of the copolymer, more preferably 15 to 30 wt%, most preferably 18 to 25 wt%.

One class of preferred copolymers comprises 10 to 60 wt% methyl (meth)acrylate and 10 to 60 wt% butyl (meth)acrylate. A further class of preferred polymers comprises 10 to 50 wt% isobornyl (meth)acrylate and 10 to 50 wt% tertiary butyl (meth)acrylate. A yet further class of preferred polymer comprising 10 to 50 wt% isobornyl (meth)acrylate, and 10 to 50 wt% ethyl hexyl (meth)acrylate or lauryl (meth)acrylate.

It is also possible to include certain monomers which carry functional groups other than hydroxyl groups, such as carboxylic acid groups, amine groups and epoxy groups. An example of a monomer having a carboxylic acid group is (meth)acrylic acid. An example of a monomer having an amine group is tertiary butyl aminoethyl (meth)acrylate. An example of a monomer having an epoxy group is glycidyl (meth)acrylate.

It is also possible to react certain functional groups in the polymer with other compounds so as to modify the polymer. For example, acid groups on the polymer can be reacted with glycidyl functional compounds such as the glycidyl ester of a tertiary carboxylic acid, for example a C_8-12 carboxylic acid such as versatic acid (available as Cardura E from Shell). Epoxy groups on the polymer can, for example, be reacted with an acid functional compound for example a tertiary carboxylic acid such as versatic acid.

In the (alkyl)acrylate ester of a glycoside of formula A-Z-B, Z is a saccharide group. The group Z may be a monosaccharide, disaccharide or polysaccharide group, but is preferably a monosaccharide group. Examples of saccharide groups are glucose, galactose, mannose, fructose, sucrose, lactose, maltose, trehalose and raffinose. Generally Z is a glucose or galactose group. The groups A and B are substituted on a primary hydroxyl position and the glycosidic position of the saccharide ring. This means that when the group A is substituted on a primary hydroxyl position, the group B is on the glycosidic position and vice versa.

The group A is substituted on a primary hydroxyl position of the saccharide group or the glycosidic position, preferably a primary hydroxyl position. When it is on the glycosidic position there is only one such position in any saccharide group, even if it is a disaccharide or polysaccharide. When it is on a primary hydroxyl position, it is not attached directly to the ring of the saccharide group but rather to a hydroxyl position on the pendent alkyl group. For a monosaccharide such as glucose there is only one possible primary hydroxyl position for the group A. However, in disaccharides and polysaccharides there can be more than one primary hydroxyl position. In this case, the group A may be substituted on any one of these. For a disaccharide or polysaccharide, the group A may be attached to the same or different saccharide ring as the group B. The saccharide group is mono-substituted by the group A, but there may be present a small amount of di-substituted component, for example up to about 3% to 5% by weight, so long as this does not undesirably affect the properties of the coating composition.

When the group A is on the glycosidic position, the group X is preferably OR' in which R' is preferably a C₂-s alkylidene group, most preferably a C_2- alkylidene group, for example -CH₂-CH₂-, -CH₂-CH₂-CH₂- -CH₂-CH2-CH₂-CH₂ -, or -CH(CH₂)CH₂- . The group X is preferably absent when the group A is on a primary hydroxyl position, that is, the group

R

- O - C -Y- C = CH₂

II o

is preferably directly attached to a primary hydroxyl position.

In the group A the group R is H or C1 alkyl. The alkyl group may be methyl, ethyl, propyl or butyl, and may be straight-chained or branched. Preferably it is H or methyl. In the group A, the group Y is preferably absent, that is, the group A is preferably

R

-X -O - C -C = CH₂

II

O

When Y is a spacing group, it can for example be a group derived from any hydroxy acid or amino acid, aliphatic or aromatic, for example the reaction product of α,α-dimethyl meta-isopropenyl benzyl isocyanate (TMI) and a fatty acid, of formula;

-(CH₂)n-O CO.NH.CH(CH₃)₂

in which n is 8 to 20 and wh oere any of the carbon atoms in the (CH₂)_n chain can be subtiuted with C_2- alkyl groups.

The group B is substituted on the glycosidic position of the saccharide group or a primary hydroxyl position, preferably the glycosidic position. When it is on a primary hydroxyl position, it is not attached directly to the ring of the saccharide group but rather to a hydroxide position on a pendent alkyl group. For a monosaccharide such as glucose there is only one possible primary hydroxyl position for the group B. However, in disaccharides and polysaccharides there may be more than one primary hydroxyl position. The group B may be substituted on any one of these groups. For a disaccharide or polysaccharide, the group B may be attached to the same or different saccharide ring as the group A. The saccharide group is mono-substituted by the group B, but there may be present a small amount of di-substituted component, for example up to about 3% to 5% by weight, so long as this does not undesirably affect the properties of the coating composition. When B is in the glycosidic position, there is only one such position in any saccharide group, even if it is a disaccharide or polysaccharide. When the group B is an alkyl group it is preferably a C_2-5 alkyl group, for example ethyl, propyl, butyl or pentyl. The alkyl group may be straight chained, branched or cyclic. The alkyl, phenyl or benzyl group may be substituted, for example by a halogen atom such as chlorine.

The (alkyl)acrylate ester of a saccharide may be prepared by, for example, the method of De Goede et al, Biocatalysis, 1994, Vol 9, ppl45-155 or the method of US-A-5,474,915. If it is desired to use a saccharide in which the group B is other than hydrogen, such a saccharide can be prepared by direct acetalisation of the saccharide with the appropriate alcohol under proton catalysis. For example an acidic ion-exchange resin such as DOWEX 50WX2-100 (trademark) may be used. The reactants may simply be heated together, for example at reflux, to complete the reaction. After the reaction the catalyst is removed together with unreacted components. The alkyl glycoside may, if desired, be purified, for example by recrystallisation or by column chromatography. However, no purification is necessary for the next step.

For example, a non-reducing alkyl glycoside may be prepared by mixing 100 parts of a reducing saccharide in a reactor containing from 500 to 1500 parts of a desired alcohol, preferably from 800 to 1200 parts, and more preferably from 900 to 1100 parts. A strongly acidic ion-exchange resin (preferably from 3 to 15 wt% relative to the mass of saccharide, more preferably from 5 to 10 wt%) is then added to the mixture. DOWEX 50WX2-100 is preferred, but other strongly acidic resins known by those skilled in the art may be used.

The reactants may be simply heated together, for example at reflux, to complete the reaction. Efficient mixing is used for total conversion of the saccharide to alkyl glycoside. Stirring can be effected using ordinary stirring device such as a propeller or blade mixer, magnetic stirrer or homomixer. At the end of the reaction, the catalyst can be recovered by filtration and may be reused. Excess unreacted alcohol may be evaporated off to yield the alkyl glycoside, which can be purified by silica gel chromatography or any other method of separation known by those skilled in the art. However, the thus-prepared alkyl glycoside can be used for the next step without purification.

The next step comprises reacting the saccharide or alkyl glycoside with a compound capable of providing an acrylate ester or (alkyl)acrylate ester group.

The alkyl glycoside may be acrylated with an acrylating compound having the general formula:

CH₂ = CR - CO - OR" wherein R is selected from the group consisting of hydrogen or C alkyl, and mixtures thereof, and OR" is a leaving group. For example a transesterification reaction can be used with an alkyl acrylate or alkyl (alkyl)acrylate such as an alkyl methacrylate, in which the alkyl groups generally contain from 1 to 4 carbon atoms. A preferred acrylating agent is methyl acrylate.

To assist in the transesterification reaction a lipase may be used, for example a lipase from Candida antartica, especially Candida antartica B (sp 435). The lipase may be immobilised. A suitable lipase is NOVOZYME 435 (trademark) available from Novo-Nordisk.

The sugar is preferably acrylated with the acrylating agent in a solvent-free process, wherein the acrylating agent is also used as the solvent for the reaction. If required, a substantially non-aqueous, organic solvent in which the non-reducing sugar and acrylating agent are soluble (i.e. at least to an amount of 10 mmol/litre and preferably 100 mmol/litre) and in which the hydrolytic enzyme is active may be used. Preferred solvents are pyridine, t-butyl methyl ether, t-butanol and t-amyl alcohol. The most preferred solvent is t-butanol.

A molecular sieve such as a zeolite may also be present in the reaction mixture to drive the reaction by absorption of the alcohol byproduct.

Preferably, the saccharide or glycoside is acrylated in the presence of a compound which inhibits the premature polymerisation of the acrylating agent. Suitable inhibitors include 2,6-di-tert-butyl-4methylphenol or hydroquinone. The preferred inhibitor is hydroquinone.

The saccharide or alkyl glycoside and acrylating agent may be mixed in the presence of the hydrolytic enzyme and, optionally, the inhibitor, preferably in a solvent-free process, at a temperature of 15°C to 90°C, preferably 30°C to 60°C, for a time sufficient to permit acrylation. The saccharide or glycoside and acrylating agent are generally mixed in at least a 1 : 1 molar ratio, with an excess of acrylating agent being preferred.

The resulting acrylated saccharide has the following formula :

O S - O - C - CR = CH₂ wherein S is an alkyl glycoside or saccharide, and R is hydrogen or C₁ alkyl, and mixtures thereof.

After the reaction has progressed to a suitable extent the lipase and molecular sieve may be removed and the desired product purified, if desired, by conventional means, for example by silica gel chromatography. In order to assist in the purification and to assist in any recycling of the lipase and/or molecular sieve, it is possible to use the lipase and/or molecular sieve in a porous container rather like a teabag. To remove the lipase or molecular sieve the "teabag" is simply taken out of the reaction medium.

The acrylated saccharide or glycoside is then copolymerised by free-radical polymerisation. Typically, the sugar acrylate monomer is dissolved in an ethylenically unsaturated comonomer or a mixture thereof in a vessel other than the polymerisation vessel. The sugar acrylate-containing copolymer can be prepared by conventional means. For example it can be produced by contacting the appropriate monomer(s) including any chain transfer agent with a polymerisation initiator at a temperature at which polymerisation occurs. For example, the comonomer mixture can be slowly fed into a solution of initiator held at the polymerisation temperature, or the initiator can be fed into a solvent at the polymerisation temperature simultaneously with the comonomer mixture.

The amount of free-radical initiator is preferably 0.05 to 5 wt%, more preferably 1 to 4.5 wt%, relative to the mass of comonomer. Suitable initiators are azo initiators such as 2,2'-azobis (2-methylbutyronitrile) or peroxy initiators such as benzoyl peroxide, di-tert- amyl peroxide or butylperoxy-2-ethyl hexanoate. The copolymer may be prepared so that it is dissolved in the solvent, and can be incorporated into coating formulations without requirement for recovery prior to use.

When water is the diluent, the copolymer can be prepared so that it is dispersed in water. Preferred initiators in this case are mixtures of potassium persulfate and hydrogen peroxide, for example mixed in equal amounts. An ammonium persulfate initiator is also preferably used. The prepared polymers may be incorporated into coating formulations without requirement for recovery prior to use.

The copolymer may also contain other units, for example up to 5 wt% of a chain transfer agent. The chain transfer agent is used to adjust the molecular weight and the reactivity of the copolymer. Examples of chain transfer agents are mercaptans, for instance alkyl mercaptans such as octyl mercaptan or dodecyl mercaptan, hydroxy alkyl mercaptans such as mercapto ethanol and mercaptoalkanoic acids such as 3-mercapto propionic acid.

Preferred chain transfer agents are octyl mercaptans and 3-mercapto propionic acid. Units derived from mercapto alkanoic acids give rise to acid groups on the polymer and it is preferred that these acid groups are reacted with glycidyl functional compounds. Suitable glycidyl functional compounds are glycidyl esters of tertiary aliphatic carboxylic acids, particularly C_8-ι₂ tertiary carboxylic acid such as Cardura E (trademark).

Multi-functional chain transfer agents such as pentaerythritol-tetra-mercapto- propionate may also be used.

The (alkyl)acrylate ester of a glycoside preferably makes up 5 to 50 wt% of the copolymer, more preferably 20 to 30 wt%.

The copolymer desirably has a weight-average molecular weight (Mw) of at least 1,000, preferably from 3,000 to 2,000,000. For a solution polymer the molecular weight is preferably from 5,000 to 20,000, even more preferably from 7,000 to 15,000. For a latex it is preferably above 100,000. The OH value of the copolymer when used in solution is generally from 1 to 5 mol/kg, preferably from 2 to 3 mol/kg. When the copolymer is used in a latex the OH value is generally from 0.1 to 1 mol/kg, preferably from 0.2 to 0.5 mol/kg.

The acid value is preferably 5 to 1 OOmg KOH/g, more preferably 60 to 70 mg KOH/g. The Tg of the solution polymer is preferably -20 to 100°C, more preferably 0 to 80°C, even more preferably 20 to 60°C. For a latex the Tg of the polymer is preferably -5 to 40°C, more preferably 5 to 30°C.

The crosslinker may be any crosslinker which is capable of crosslinking the hydroxy groups of the saccharide groups Z under the conditions in which the coating composition is to be cured. Appropriate crosslinkers are well known to those skilled in the art. The crosslinker may be, for example a metal chelating agent, or a polyisocyanate, which may be blocked or unblocked. The crosslinker may also be an epoxy, benzoguanamine, glycouril or formaldehyde resin, such as a urea formaldehyde, melamine formaldehyde or phenol formaldehyde resin or a hydroxy alkylamide, carbodiimide, or dialdehyde resin.

Polyisocyanates are well-known crosslinkers in the coating art. Polyisocyanates are compounds having at least two isocyanate groups per molecule preferably an average of 2 to 5 isocyanate groups per molecule, more preferably 2.5 to 4 isocyanate groups per molecule. The polyisocyanate may be, for example, a diisocyanate or triisocyanate. The isocyanate groups may be blocked or unblocked. Suitable diisocyanates are aliphatic or aromatic diisocyanates. Examples of suitable aliphatic diisocyanates are hexamethylene diisocyanate and isophorone diisocyanate and meta tetramethylxylene diisocyanate (TMXDI). Examples of suitable aromatic diisocyanates are toluene diisocyanate and 4,4'- diphenyl methane diisocyanate. Other suitable polyisocyanates include the isocyanate trimers, biurets, allophanates and uretdiones of diisocyanates such as those described above as well as the reaction products of these diisocyanates with polyols. Polyols are compounds having two or more hydroxy groups per molecule. Suitable polyols include trimethylol propane, glycerol and pentaerythritol. Many such polyisocyanates are commercially available, for example those sold under the Desmodur trademark from Bayer and the Tolonate trademark from Rhodia.

The polyisocyanate crosslinkers are preferably used in an amount such that the ratio of isocyanate groups on the polyisocyanate to the number of hydroxyl groups on the polymer is from 0.5:1 to 1.4:1, more preferably 0.6:1 to 1.1 :1.

The solvent or diluent may be any solvent or diluent which is capable of dissolving or dispersing the copolymer and crosslinker and which can be removed under the conditions in which the coating composition is cured. Appropriate solvents and diluents are well known to those skilled in the art. The solvent or diluent may be aqueous or non-aqueous. For example it could be an aqueous or non-aqueous diluent, and the copolymer may be dispersed therein, for example to form a latex or emulsified polymer. It could also be an aqueous or non-aqueous solvent, and the copolymer may be dissolved therein to form a solution. A suitable non-aqueous solvent is a volatile organic solvent. It can be, for example, an aliphatic or aromatic hydrocarbon such as Solvesso 100 (trademark), toluene or xylene, an alcohol such as butanol or isopropanol, an ester such as butyl acetate or ethyl acetate, a ketone such as acetone, methyl isobutyl ketone, methyl amyl ketone, or methyl isoamyl ketone, an ether alcohol such as propylene glycol monomethyl ether or an ether ester such as propylene glycol monomethyl ether acetate, or a mixture of any of these.

The non-volatile component excluding pigment (i.e. everything except the solvent and pigment) of the coating composition generally comprises from 5 to 80 wt%, preferably from 30 to 75 wt%, and more preferably from 60 to 70 wt% of the copolymer, and from 20 to 60 wt%, preferably from 25 to 50 wt%, more preferably from 30 to 40 wt% of the crosslinker. The coating composition preferably comprises from 15 to 95 wt%, more preferably from 30 to 85 wt%, of the non- volatile component excluding the pigment.

The coating composition may also contain one or more other components generally used in the art of coating compositions such as pigments, coalescing agents, other film-forming substances, reactive diluents, plasticisers, extenders, UV stabilisers, flow aids, wetting aids and catalysts for the crosslinking reaction.

By use of appropriate amounts of the crosslinking catalyst it is possible to control the pot life and curing rate of the composition. Use of lower levels of catalyst will increase the pot life, whereas use of higher levels of catalyst will increase the curing rate (and shorten the pot life). Using the copolymer used in the present invention enables a coating composition to be obtained which has either a longer pot life or an increased rate of attainment of hardness and other useful properties as compared with conventional film forming copolymers.

The amount of catalyst is preferably lxl 0^"4 to 1 wt%, preferably 0.01 to 0.1 wt%, relative to the total weight of the composition. Increased pot life can generally be achieved at amounts up to 0.1 wt%. Increased cure rate can generally be achieved at amounts of from 0.1 wt% to 1 wt%. The catalyst used depends on the crosslinker and examples are well known in the art. For polyisocyanate the catalyst may be, for example, dibutyl tin dilaurate or diacetate. For a melamine formaldehyde resin it is, for example, paratoluene sulfonic acid. For epoxy it is, for example, a strong Lewis acid or tertiary amine such as triethylamine.

The coating composition of the present invention may be prepared by mixing the components together. Generally, when the crosslinker is an unblocked polyisocyanate, the composition is made by mixing the polyisocyanate, optionally in solution in an organic solvent, with the other components shortly before use. This reduces problems associated with the relatively short pot life of the final compositions.

If the coating composition of the present invention is not storage stable over time, it may be presented as a multi-component pack intended for mixing prior to use. One component may comprise the copolymer in a diluent and the second component may comprise a crosslinker. The second component may also comprise a diluent although this is not necessary. The diluents may be the same or different. The two components are simply mixed before use by any method known to those skilled in the art.

A wide variety of substrates may be coated by the coating composition of the present invention by conventional means such as brushing, roller-coating, spraying or dipping.

Suitable substrates include metals such as steel and aluminium, wood, plastic and glass.

The composition finds particular use in all aspects of the coating of vehicles such as automobiles, including application of primer or surfacer coats, base coats and clear coats.

The composition can also be applied on a suitable base coat or undercoat, for example as a top coat. The layers may be applied wet-on-wet, i.e. where a second coat is applied without curing or completely drying the previous coat. The coated substrate can be dried under ambient or elevated temperatures to allow simultaneous curing of both coats.

The layer can be cured either by allowing the solvent or diluent to evaporate at room temperature or by heating, for example to 150°C for 3 to 20 minutes, or 50 to 70°C for 5 to 60 minutes. The layer can also be force dried by the use of enhanced airflow over the surface of the film from the spray gun, or from an Aquadry (trademark) unit, or from any other suitable equipment, at either ambient or elevated temperatures.

The present invention will now be further described with reference to the following Examples. EXAMPLES

Preparation Example 1

1. Preparation of Alkyl Glycosides (AGs).

Method 1

Ml.l : Preparation of AGl: α-D-glucose (200g) was mixed with ethanol (1.5 litre) and a strongly acidic ion-exchange resin Dowex 50WX2-100 (60g) in a 2 litre three neck round bottomed flask fitted with a condenser, a temperature controller, and an overhead stirrer. The reaction mixture was stirred at the reflux temperature of ethanol (78°C), and the transformation of glucose to (α+β)l-O-ethyl glucopyranoside was monitored by TLC and Gas Chromatography (GC). GC analysis showed that the reaction was complete after 4h. The Dowex resin was then filtered off, and unreacted ethanol was removed in vacuo, yielding (α+β)l-O-ethyl glucopyranoside (confirmed by TLC, GC, and ^I3C NMR analysis) as a slightly yellowish thick oil (230g, -100% yield).

The following range of AGs was produced according to the procedure of Method 1 , except for the following modifications.

M1.2 : Preparation of AG2:

n-propanol was used (1.5 litre), reflux temperature = 97°C, GC and ¹³C NMR analysis showed the formation of (α+β)l-O-propyl glucopyranoside.

M1.3 : Preparation of AG3:

n-butanol was used (1.51itre), reflux temperature = 118°C, GC and ¹³C NMR analysis showed the formation of (α+β) 1-O-butyl glucopyranoside.

M1.4 : Preparation of AG4:

D-galactose was reacted (200g) with ethanol (1.51itre), reflux temperature = 78°C, GC and

1 ^" C C aannaallyyssiiss sshhooww<ed the formation of (α+β)l-O-ethyl galactopyranoside + (α+β)l-O-ethyl galactofuranoside Preparation Example 2

Method 2

2. Enzymatic Formation of Alkyl Glycoside Acrylate Esters (AGAEs).

M2.1 : Formation of AGAE1:

AGl (200g) was dissolved in t-amyl alcohol (700 ml) in a three-neck round bottomed flask fitted with a condenser, a temperature controller, and an overhead stirrer. The temperature was adjusted to 50°C. Methyl acrylate (650 ml), Novozyme 435, immobilised lipase from Candida Antarctica (10g), a few crystals of polymerisation inhibitor (BHT), and freshly activated 4 A (0.4nm) molecular sieves (200g) were then added to the mixture which was stirred at 50°C for 48h. The progress of the reaction was monitored by GC analysis which showed about 50% conversion after 2 days. At this stage the reaction was stopped by filtering off lipase and sieves, and a crude oil was recovered after evaporation in vacuo of excess solvents (purity : 50% desired product + 50% unreacted starting material). Purification was performed by selective solvent extraction of the product. The crude oil was dissolved in a saturated solution of NaCl + H₂O (150ml), and the esterified product was selectively extracted from the aqueous phase with ethyl acetate (4x200ml). The organic phase was centrifuged and dried over MgSO₄. The desired (α+β)l- O-ethyl-6-O-acryloyl glucopyranoside was obtained as a slightly yellowish oil (90g, 35% overall yield) after evaporation of ethyl acetate in vacuo. Composition of final oil : (GC) 95% (5% unreacted (α+β)l-O-ethyl glucopyranoside). The purity of the final product was estimated sufficient for further use in copolymers. A small portion of mixture was further purified by column chromatography on silica gel (eluent : 95/5 CHCl₃/MeOH).¹³C NMR showed the formation of (α+β)l-O-ethyl-6-O-acryloyl glucopyranoside.

The following range of AGAEs was produced according to the procedure of Method 2, except for the following modifications.

M2.2 : Formation of AGAE4:

AG4 was used (200g); 40% conversion obtained after 48 hours. Purification by selective solvent extraction: crude oil dissolved in saturated aqueous solution of NaCl (300ml), washed with ethyl acetate (4x500ml); product yielded as crystals + oil mixture (60g, 25%); final oil composition : 96% desired (α+β) 1-O-ethyl- 6-O-acryloyl galactoside, 4% unreacted substrate.

¹³C NMR and GC analysis showed the formation of (α+β)l-O-ethyl-6-O-acryloyl galactopyranoside + (α+β)l-O-ethyl-6-O-acryloyl galactofuranoside.

M2.3 : Formation of AGAE5 :

AG2 (150g) was reacted with vinyl methacrylate ( 151 g) in t-BuOH (11); 90% conversion obtained after 10 hours; crude oil composition : 90% desired (α+β)l-O-propyl-6-O-acryloyl glucopyranoside, 9% unreacted substrate, <1% diester; product yielded as slightly yellowish oil (140g, 75%).

¹³C NMR showed the formation of (α+β)l-O-propyl-6-O-methacryloyl glucopyranoside.

M2.4 : Formation of AGAE6 :

A mixture of α- and β- 1-O-methyl glucopyranoside was prepared (15g, 2/1 ratio α/β); 75%) conversion after 6 days; purification by triturating crude oil with large volumes of n-hexane; product yielded as slightly yellowish oil (lOg, 60%); final oil composition : 90% desired (α+β)l-O-methyl-6-O-acryloyl glucopyranoside, 8% unreacted substrate, <2% diester.

¹³C NMR showed the formation of (α+β)l-O-methyl-6-O-acryloyl glucopyranoside.

Method 3:

M3.1 : Formation of AGAE2:

AG2 (lOOg) was dissolved in methyl acrylate (1 litre) in a 2 litre stoppered conical flask.

Novozyme 435 (50g), freshly activated 4A (0.4nm) molecular sieves (lOOg) and a few crystals of polymerisation inhibitor (BHT) were subsequently added, and the reaction was vigorously shaken at 50°C in an incubator. Progress of the reaction was monitored by GC, which showed that 90%) conversion was achieved after 20 hours. The reaction was stopped at this stage by filtering off both sieves and lipase. After evaporation of the excess methyl acrylate in vacuo, a yellowish oil was recovered (lOOg, 70%o).

Crude oil composition : 92%> (α+β)l-O-propyl-6-O-acryloyl glucopyranoside, 8% unreacted substrate, <1% diester. The purity of the final product was estimated to be sufficient for further use in copolymers. A small portion of mixture was further purified by column chromatography on silica gel (eluent : 95/5 CHCl₃/MeOH).

¹³C NMR showed the formation of (α+β)l-O-propyl-6-O-acryloyl glucopyranoside.

The following AGAE was produced according to Method 3, except for the following modifications.

M3.2 : Formation of AGAE3 :

AG3 was used (lOOg); 95% conversion obtained after 20 hours; crude product composition : 95%o (α+β)l-O-butyl-6-O-acryloyl glucopyranoside, 4%> unreacted substrate, <1% diester. Product yielded as slightly yellowish oil (100g, 80%).^I3C NMR showed the formation of (α+β)l-O-butyl-6-O-acryloyl glucopyranoside.

The natures of the Alkyl Glycoside Acrylate Esters and their synthetic methods are summarised in Table 1 :

Table 1

Preparation Example 3

Copolymers

3. Synthesis of AGAE Copolymers (AGAECOs)

Method 4

M4 : Synthesis of solution copolymer Comparative Example CE1

A mixture of comonomers containing butyl acrylate (BA) (66.9g, 22.3% w/w), methyl methacrylate (MMA) (95. lg, 31.7% w/w), styrene (St) (60g, 20% w/w) and hydroxy ethyl methacrylate (HEMA) (78g, 26% w/w) as well as a polymerisation initiator 2,2 azobis (2-methyl butyro nitrile) (VAZO 67, 3g, 1% w/w to monomer amount) was premixed thoroughly in a beaker. The mixture was added slowly by a peristatic pump over 3 hours (25g/15min) into a 11 polymerisation vessel fitted with a condenser, a temperature controller, and an overhead stirrer, containing the solvent (methyl isoamyl ketone, 200g) at reflux temperature (145°C). At the end of the feed process, the solution was kept at 145°C for 1 hour, while total monomer conversion was ensured by three late additions of initiator (0.3g) every 20 minutes. The heat source was subsequently removed, and the polymer was recovered as a slightly viscous solution.

Copolymers (# 1,7-11,15 Table 2) were prepared according to method 4.

Copolymers (# 2-6,12-14 Table 2) were prepared according to method 4, but with butyl acetate (reflux temperature = 125°C) in lieu of methyl iso-amyl ketone.

AGAE3 was also copolymerised by emulsion polymerisation (AGAECO 9), as exemplified by method 5.

Method 5

M5 : Water (400g) and Synperonic NP10 (6g, 6% w/w to total monomer charge) were mixed together in a polymerisation vessel fitted with a condenser, a temperature controller, a nitrogen inlet and an overhead stirrer, and were stirred at 60°C for 30 minutes. A mixture of MMA + BA (5g, 50%/50% w/w) was added and the mixture was stirred at 80°C for 30 minutes. Ammonium persulfate (O.lg) was subsequently added, and the reaction was stirred at 80°C for a further 30 minutes. The comonomer mixture [MMA + BA (80g, 50%/50% w/w) + AGAE3 (15g)] and the initiator ammonium persulphate (2g) were then added slowly over 3 hours by a peristatic pump. Total monomer conversion was ensured by one late addition of ammonium persulphate (0. Ig). The copolymer was recovered as a white dispersion.

Copolymer CE 7 was prepared according to method 5, but with HEM A in lieu of AGAE3.

The compounds produced are summarised in Tables 2 and 3. In all cases the copolymer also contained 20% w/w styrene.

Notes: HEMA - hydroxy ethyl methacrylate

HiPMa - hydroxy isopropyl methacrylate

BA - butyl acrylate

MMA - methyl methacrylate

AA - acrylic acid POM - n-octyl mercaptan

Table 3

Example 1

4. Formulation of Coatings and Investigation of their Performance

4.1 Evaluation of Clearcoats

Coatings Preparation 1

CP1 : Copolymer 5.72g, 35%o NV in butyl acetate, (# 1,9 Table 2) was mixed with catalyst dibutyl tin dilaurate (DBTDL, 20%) NV in butyl acetate, 0.252g) in screw-top vials, and various amounts of crosslinker (Des.N3390, 35%) NV in butyl acetate) were added to the mixture in each vial so as to obtain fixed OH/NCO ratios (1/0.75, 1/1, 1/1.25, 1/1.5). The mixture was vigorously agitated manually, and films were cast on glass panels using a 200μm block spreader. The glass panels were thoroughly cleaned with acetone prior to casting films, in order to avoid any surface tension interactions that might result in film shrinkage. Films were cured at 60°C for 30 minutes, and were allowed to cool to room temperature prior to measurements. The solvent resistance of clearcoats was assessed by rubbing the films with a methyl ethyl ketone (MEK)-impregnated rag until the film degraded. The maximum number of rubs was fixed at 200. The results are presented in Tables 4 and 5.

Table 4; Evaluation of Copolymer AGAECO 3 ( # 9 Table 2)

Table 5; Evaluation of Copolymer CE1 (# 1 Table 2)

These results clearly show that better film properties are obtained with the copolymer containing a sugar acrylate (AGAECO 3) than with copolymer based on HEMA (CE 1).

Example 2

4.2 Solvent Resistance of Copolymers Containing Different Sugar Acrylate Monomers

CP 2 : Copolymers [(5.72g, 35% NV in butyl acetate, (#1, 7-11 Table 2)] were mixed with catalyst (DBTDL, 20% NV in butyl acetate, 0.252g) in a screw-top vial, and Des.N3390 (2.4g, 35%NV in butyl acetate) was added to the mixture which was vigorously agitated manually. Films were cast on glass panels using a 200 μm block spreader. The glass panels were thoroughly cleaned with acetone prior to casting films, in order to avoid any surface tension interactions that might result in film shrinkage. Films were cured at 60°C for 30 minutes, and were allowed to cool to room temperature prior to evaluation. The results are presented in Table 6.

Table 6

These results clearly show that copolymers based on sugar acrylates have better solvent resistance than the copolymer containing HEMA. They also show that sugar acrylates performed differently depending at least in part on the nature of the aglycon chain, the copolymer containing AGAE1 (# 3 Table 6) giving the best performance.

Example 3

4.3 Investigation of Coatings Based on 2K Refmish Systems

The curing conditions were those typically used for high solids two pack systems for the refmish car market. The formulation is shown in Table 7.

Table 7

4.3.1 Pot-Life Analysis of Coating Systems Prepared According to Table 7

The coating composition described in Table 7 was scaled up to 130g according to the method described in Coatings Preparation 7 (see paragraph 4.3.3), and the pot-life of resulting mixtures was measured using a British Standard B4 flow cup. The cup was filled up and emptied at 15 minutes intervals, and the time taken for emptying the cup was determined in seconds, thus giving an indication of the viscosity development of the mixture. The results are presented in Table 8.

Table 8

The limit for acceptable pot-life is generally fixed by professional sprayers at from 25 to 40 or 50 seconds B4 cup for at least 2 hours, for reasons of ease of sprayability. The composition comprising the sugar acrylate-based copolymer functionalised at 3 moles OH/kg (# 4 Table 8) is the least viscous, with a final viscosity of 28 seconds after 2 hours. This proved to be significantly superior to that of compositions comprising comparative copolymers synthesised at 2 moles OH/Kg (# 1,2 Table 8), with the HEMA-based copolymer (# 1 Table 8) having the highest viscosity rise, gelling after 1 hour. The pot-life of the hydroxy isopropyl methacrylate (HiPMA)-based copolymer functionalised at 3 moles OH/Kg (# 3 table 8) was also found unacceptable for refmish applications, with the 40s limit attained 1 h after mixing.

This clearly showed that the incorporation of sugar acrylates into a polyol results in a system with lower viscosity/longer pot-life properties than the corresponding comparative polyols.

The gel -times of coating systems described in paragraph 4.3.1 were also recorded. A coating based on a sugar acrylate-contaimng copolymer functionalised at 3 moles OH/kg (# 4 Table 8) possessed a significantly longer gel-time than comparative copolymers. A gel time of greater than 16 hours was displayed. In comparison, copolymer based on HiPMa also functionalised at 3 moles OH/kg (# 3 Table 8) displayed a gel-time of lh45s.

This clearly shows that gel-time measurements are in good accordance with pot-life experiments, with coating systems based on sugar acrylates possessing longer gel-times than corresponding comparative polyols.

Example 4

4.3.2 Comparative Film Properties of Mixtures with Similar Fast Cure Routes

Pot-life experiments indicated that copolymers based either on HiPMa or sugar acrylates reacted with isocyanate at different rates. The experiments described below were aimed at normalising the rates of isocyanate crosslinking, by catalysing the crosslinking reactions with different amounts of tin (IV) catalyst, thereby adjusting the pot-lifes of coating mixtures. The experiments were carried out with copolymers based on HiPMa and sugar acrylates of identical functionality (# 13,14 Table 2 and # 5,6 Table 2). The results are presented in Tables 9 and 10.

Coatings Preparations 3 to 6

CP 3 : Pack 1 was prepared by mixing resin (AGAECO 7, 3.54g, 50% NV) with butyl acetate (0.46g) and DBTDL 2 (lg). Pack 2 was prepared by mixing Des. N3390 (1.38g) with butyl acetate (0.62g). Pack 2 was added to pack 1, and the mixture was allowed to settle after being vigorously agitated, prior to casting onto glass panels using a 200 μm block spreader. The glass panels were thoroughly cleaned with acetone prior to casting films, in order to avoid any surface tension interactions that might result in film shrinkage. The films were cured at 60°C for 1/2 hour, and measurements were taken at regular intervals after the films were allowed to cool to room temperature. Film hardness was measured by swinging a pendulum (Erichsen Pendulum) on the film surface and counting the number of swings taken over a specified angle (6°). Film solvent resistance was measured in MEK rubs, similarly as described in Example 1 - preparation CP 1.

CP 4 : The method described in CP3 was followed for the crosslinking of copolymer AGAECO 8 (# 14 Table 2).

CP 5 : Coating based on copolymer CE 5 (# 5 Table 2) was prepared according to the method described in CP3, with the reactivity adjusted to that of copolymer based on AGAECO 7 by using DBTDL 0.2% .

CP 6 : Coating based on copolymer CE 6 (# 6 Table 2) was prepared according to the method described in CP3, with the reactivity adjusted to that of copolymer based on AGAECO 8 by using DBTDL 1% .

Table 9; Comparative film hardness development after cure

Table 10

Comparative film solvent resistance

These results clearly showed that when made to react at the same rate, coating compositions based on sugar acrylates (CP 3 and CP 4) generated better film properties than corresponding HiPMa-based preparations. These experiments also showed that films of acceptable hardness and solvent resistance were obtained 1 hour after cure.

These coatings were also investigated for their printfree and dust-free times.

Print-free test : finger pressed on the film surface, positive if no fingerprint left.

Dust-free test : dust spread on film surface, positive if all dust brushed off surface.

The results are presented in Tables 11 and 12.

Table 11

Print-free test

Table 12; Dust-free test

These results clearly showed that films of compositions CP 3 and CP 4 were handleable 15 minutes after cure as compared to films of compositions CP 5 and CP 6.

Example 5

4.3.3 Film Properties of Coating Compositions Based on Refinish 2K Systems

These experiments were aimed at comparing the film properties of systems based on refinish 2K curing conditions, where the catalyst levels were kept constant, i.e. with reactivities not normalised.

Coatings Preparation 7

CP 7 : The acrylic resin was diluted to 50%> NV (in the case of resins synthesised at 70%> NV) with butyl acetate in a screw-cap vial. Pack 1 was prepared by mixing 3.54g of copolymer of Table 13 (50% NV) with butyl acetate (0.46g) and DBTDL 1% (0.2g). Pack 2 was prepared by mixing Des. N3390 (1.38g) with butyl acetate (0.62g). Pack 2 was added to pack 1 , and the mixture was allowed to settle after being vigorously agitated, prior to casting onto glass panels using a 200 μm block spreader. The glass panels were thoroughly cleaned with acetone prior to casting films, in order to avoid any surface tension interactions that might result in film shrinkage. The films were cured at 60°C for 30 minutes, and measurements were taken at regular intervals after films were allowed to cool to room temperature. The film hardness was measured as described in CP 3 (Example 4). Film solvent resistance was measured in MEK rubs, similarly as described in preparation CP 1 (Example 1) The results are presented in Tables 13 and 14. Table 13; Film Hardness Development after Cure

Table 14; Film Solvent Resistance Development after Cure

Coating systems based on copolymers functionalised at 3 moles OH/kg (# 3 and 4 Tables 13 and 14) exhibited comparable film properties, whereas the film properties of coating systems based on copolymers functionalised at 2 moles OH kg were slightly better for the HiPMa-based system (# 1 Tables 13 and 14). In parallel, it was shown that coatings based on sugar acrylates possessed significantly longer pot-lifes than HiPMa-based coatings.

These results showed that replacement of HiPMa by sugar acrylates at constant functionality resulted in film properties comparable to those of Comparative Examples, but also resulted in significant pot-life increase. Furthermore, # 4 could also be compared to # 1 as the latter was quite similar to a current commercially available formulation. In this case, replacement of the HiPMa-containing copolymer functionalised at 2 moles OH/kg by a sugar acrylate based copolymer functionalised at 3 moles OH/kg resulted in slightly better film properties while also giving significantly longer pot-life.

Example 6

4.3.4 Water Resistance of Films Prepared According to Preparation Method 7

Films prepared according to Coatings Preparation 7 were cast on metallic panels, cured at 60°C for 1/2 hour, and allowed to stand for 7 days at room temperature before being immersed in a tank containing water at 40°C. This test was aimed at assessing the water resistance of clearcoats, which would pass this test if they remained unaffected by water for 10 days. The results are presented in Table 15.

Table 15

These results clearly showed that all films based on sugar acrylate copolymers (regardless of molecular weights or functionality) remained unaffected for 10 days when immersed in water at 40°C, and were better than coatings based on HEMA (# 1 Table 15).

Example 7

4.4 Sugar Acrylates in Express Clearcoats

This example compares the film properties of systems based on Express Refinish 2K Clearcoats. Express clearcoats have been developed with a view of reducing the low-bake cure time from 30 minutes to 20 minutes, therefore giving the customer valuable cost benefits.

The comparative example is the commercially available Express 2K Clearcoat with pack 1 being PI 90-643 HS clearcoat obtainable from ICI Autocolor and being based on an acrylic polyol prepared at 2 moles OH/kg and with pack 2 being P210-852 HS Express Hardener obtainable from ICI Autocolor and containing a crosslinker. This comparative example will be referred to as the "standard" from this point.

The aim is to introduce copolymers containing sugar acrylates in place of the resin used in the standard, and show the benefits obtained by the new formulation. The experiments described below aimed to normalise the rates of isocyanate crosslinking, by catalysing the crosslinking reactions with different amounts of tin (IV) catalyst, thereby adjusting the pot life of the sugar acrylate-containing coating mixtures to that of the standard.

Coatings Preparation 8

CP 8 : The standard was prepared according to the product datasheet instructions, and as conventionally followed by end-users of this formulation. The standard system was obtained by mixing pre-made Pack 1 (6g) with pre-made Pack 2 (3g) and organic diluent (1.2g) in a screw-capped vial.

Samples containing sugar acrylate copolymers were prepared according to the following methods :

Coatings Preparations 9 and 10

CP 9 : Pack 1 was prepared by mixing resin (AGAECO 7, # 13 Table 2-, 4.71g, 50% NV) with butyl acetate (0.6 lg) and dibutyl tin diacetate (DBTDA 2%>, 1.33g). Pack 2 was prepared by mixing the crosslinkers Des.N3390 (1.39g, 90% NV) with Des.Z 4370 (0.44g, 70%) NV) both obtainable from Bayer AG and butyl acetate (0.82g). Pack 2 was added to pack 1 , and the mixture was allowed to settle after being vigorously agitated, prior to casting onto glass panels using a 200 μm block spreader. The glass panels were thoroughly cleaned with acetone prior to casting the films, in order to avoid any surface tension interactions that might result in film shrinkage.

CP 10 : The method described in CP 9 was followed for the crosslinking of copolymer AGAECO 8 (#14 Table 2), and with 1.6g DBTDA 1%.

Different curing schemes were selected to compare the properties of films cast from the various coating preparations : low-bake cure (60°C) was performed for either 20, 10 and 5 minutes, and the starting time for film investigations was chosen to be immediately after films were removed from the oven. In another method, the films were cured at room temperature, and in this case the starting time was chosen to be immediately after the films were cast.

Films were investigated for their hardness development after having been allowed to cool to room temperature if cured under low-bake conditions. The film hardness was measured using the Erichsen Pendulum according to the method described in paragraph 4.3.2. in Example 4. For selected cases, the film solvent resistance was measured in MEK rubs, similarly as described in Example 1 - preparation CP 1.

Table 16 : hardness development of films cured at low-bake for 20 minutes

Table 17 : hardness development of films cured at lowbake for 10 minutes

Table 18 : film properties of films cured at low-bake for 5 minutes

Table 19 : film properties of air-cured films

When cured under standard Express 2K clearcoat conditions (60°C for 20 min), films containing copolymers based on sugar acrylate displayed significantly improved hardness development as compared to the commercial standard. Films twice as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 2 moles OH/kg after lh, whereas films nearly 4 times as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 3 moles OH/kg after 1 hour.

The low-bake cure time was decreased by half (60°C for 10 min), and under these conditions, significantly improved film hardness development was displayed by copolymers containing sugar acrylates. Films twice as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 2 moles OH/kg after 1 hour, whereas films 3 times as hard were obtained for the formulation containing the sugar acrylatebased copolymer at 3 moles OH/kg after 1 hour.

Attempts to decrease low-bake cure time to a quarter of the standard time (60°C for 5 min) also proved to be highly successful, as films twice as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 2 moles OH/kg after 1 hour, whereas films 3 times as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 3 moles OH kg after 1 hour.

Similar benefits were obtained when films were cured at ambient temperature, as films 3 times as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 2 moles OH/kg after 3 hours, whereas films nearly 6 times as hard were obtained for the formulation containing the sugar acrylate-based copolymer at 3 moles OH/kg after 3 hours.

In order to prove that the benefits obtained for film hardness were not due to the contribution of the Tg of the polymer, solvent resistance was also measured in the case of films cured for either 5 min or air-cured. These results clearly showed that the film hardness development benefits were due to crosslinking, as proved by differences in solvent resistance between the standard system and films based on sugar acrylate - containing copolymers.

The films were also investigated for their print-free and dust-free times, as described in paragraph 4.3.2. in Example 4.

Table 20 : Print-free and Dust-free tests

These results clearly show that coating compositions based on the sugar aery late-containing copolymers have print-free and dust-free times which are significantly shorter than those of the standard systems.

Example 8

4.5 Film Properties of Coatings Based on Latex Copolymers (Table 3)

Coatings Preparation 11 : Latex Copolymer Crosslinked with Glyoxal

CP 11 : Copolymer AGAECO 9 (4g, 20% NV in water) was mixed with glyoxal (0.2g, 40%) NV in water), p-TSA (0.1 g, 10% in water) in a screw-top vial, and the mixture was vigorously shaken manually. Films were cast onto glass panels using a 200 μm block spreader and were cured at 60°C for 30 minutes. The glass panels were thoroughly cleaned with acetone prior to casting films, in order to avoid any surface tension interactions that might result in film shrinkage. CP 12 : Coating based on copolymer CE 7 (# 1 Table 3) was prepared according to the method described for Coating Preparation 11.

The films were investigated for their solvent resistance (MEK rubs-Table 21) and water resistance (Water rubs-Table 22; Water spot-Table 23) lh after cure.

Table 21

These results clearly showed that films obtained from the sugar acrylate latex possess significantly better properties than those based on the HiPMa-containing latex. Water resistance tests indicated that crosslinking with glyoxal was significantly better when performed with the sugar acrylate copolymer than with the HiPMa-based counterpart.

Example 9

Preparation of monomer glucose ethyl methacrylate ( GEMA )

A mixture of methyl glucoside (195 g), hydroxyethyl methacrylate (340 g), p-Toluene sulfonic acid ( 8g) and hydroquinone (12 g) was stirred and heated at 90C for 2.5 hrs under a vacuum of 0.8 bars and the reaction by-product methanol was removed by distillation. The end point is reached when the solution becomes clear. This results in a solution of glucose ethyl methacrylate in HEMA, the OH value of the mixture being

10.1 moles OH/ Kg . Preparation of Solution polymer containing GEMA

A mixture of comonomers containing butyl acrylate (BA) (lOOg, 9.43 % w/w), isobornyl methacrylate (IBOMA) (400g, 37.74% w/w), styrene (St) (300g, 28.3% w/w) and acrylic acid AA (10g,0.94 %), monomer glucose ethyl methacrylate in Hema (GEMA) (250g, 23.58%) w/w) as well as a polymerisation initiator benzoyl peroxide (BzP(50%), 40g) to monomer amount), water ( 200g) was premixed thoroughly in a beaker and kept stirring. The mixture was added slowly by a peristaltic pump over 3 hours into a 31 polymerisation vessel containing 1000 g butyl acetate, fitted with a Dean Stark apparatus containing the butyl acetate (200g) fitted with a condenser, a temperature controller, and an overhead stirrer, at reflux temperature (120°C) water being removed continually during the polymerisation. At the end of the feed process, the solution was kept at 120°C for 1 hour, while total monomer conversion was ensured by one late addition of initiator (10 g) and held for 1 hr. The heat source was subsequently removed, and the polymer was recovered after filtration, as a slightly viscous solution.

This results in a polymer with OHV 2.39 OH/ Kg nv.

Comparative clearcoat compositions

The above polymer was compared with a commercial polymer, ex ICI Autocolor, of OHV - 2.35 moles OH/Kg nv.

Formulations

Results

The clearcoats were applied on glass at 200 microns wet and baked in an oven for 5 mins at 60°C.

Summary

The data proves that glucose ethyl methacrylate contributes to substantially longer pot life while giving better film properties.

Claims

1. A coating composition comprising:

(a) a copolymer obtained by vinyl polymerisation of:

i) at least one ethylenically unsaturated monomer; and

ii) at least one (alkyl)acrylate ester of formula:

A-Z-B

wherein:

Z is a saccharide group,

A is a group of formula

R

- X - O - C -Y - C = CH₂

II O

wherein X can be absent or is a group OR' in which R' is a Cj- alkylidene, phenylidene or benzylidene group, Y is an optional spacing group, R is H or C alkyl, and B is H or a Cι_-8 alkyl, phenyl or benzyl group; the groups

A and B being substituted in any order on a primary hydroxyl position of the saccharide group and the glycosidic position of the saccharide group;

(b) a crosslinker for the hydroxy groups of the saccharide group; and

(c) a solvent or diluent.

2. A composition according to claim 1 in which A is on a primary hydroxyl position of the saccharide group and the group B is on the glycosidic position.

3. A composition as claimed in claim 2 in which X is absent.

4. A composition as claimed in claim 1 in which A is on the glycosidic position of the saccharide group and B is on a primary hydroxyl position, and X is OR' in which R'is C_2-4 alkylidene.

5. A composition according to claim 1 wherein the copolymer has a molecular weight of from 1 ,000 to 2,000,000.

6. A composition according to any one of the preceding claims wherein B is a C _-5 alkyl group.

7. A composition according to any one of the preceding claims wherein the solvent or diluent is an aqueous diluent and the copolymer is dispersed therein to form a latex or emulsified polymer.

8. A composition according to any one of claims 1 to 6 wherein the solvent or diluent is a non-aqueous diluent and the copolymer is dispersed therein.

9. A composition according to any one of claims 1 to 6 wherein the solvent or diluent is a solvent and the copolymer is dissolved therein to form a solution.

10. A composition according to any one of the preceding claims wherein the crosslinker is a metal chelating agent, a polyisocyanate, epoxy or a urea formaldehyde, melamine formaldehyde, phenol formaldehyde, benzoguanamine, carbodiimide, dialdehyde or glycouril resin.

11. A composition according to claim 10 wherein the crosslinker is a polyisocyanate having an average of 2.5 to 4 isocyanate groups per molecule.

12. A multi-component pack suitable for forming a coating composition as defined in any one of claims 1 to 11 which comprises, in one component, the copolymer and a diluent and, in a second component, the crosslinker.

13. A process of coating comprising applying a layer of a composition according to claim 1 to a substrate and causing or allowing the layer to cure.

14. A substrate coated with a cured coating composition as defined in any one of claims 1 to 11.

15. A process for preparing a coating composition as defined in any one of claims 1 to 11 which comprises mixing together the copolymer, crosslinker and solvent.