EP1727870A1

EP1727870A1 - Reactive coalescent agents

Info

Publication number: EP1727870A1
Application number: EP05731348A
Authority: EP
Inventors: Janne Hulkko; Salme Koskimies; Kari Rissanen; Marian Marttina; Reetta KYLÄKOSKI; Mia LÖIJA; Leena Paajanen
Original assignee: Valtion Teknillinen Tutkimuskeskus
Current assignee: Valtion Teknillinen Tutkimuskeskus
Priority date: 2004-03-22
Filing date: 2005-03-22
Publication date: 2006-12-06
Also published as: FI20040430A; WO2005089549A1; FI20040430A0; FI116844B; WO2005090501A1; EP1727425A1

Abstract

The present invention relates to reactive coalescent agents, particularly to aliphatic epoxide esters and ethers, as well as cycloaliphatic epoxide esters, methods of the production thereof, and to their use in coating compositions, especially in coating compositions, from which only low amounts of volatile organic compounds are released. The invention is also directed to a method for accelerating the curing of a coating composition.

Description

REACTIVE COALESCENT AGENTS

Field of the Invention

The present invention relates to reactive coalescent agents, particularly aliphatic epoxides with polar groups, and to their use in coating compositions, especially in coating compositions, from which low amounts of volatile organic compounds are released. The invention is also directed to a method for accelerating the curing of a coating composition.

Prior Art

Dispersions of polymers are used as binders in aqueous paints, or latex paints. The properties of these polymer dispersions depend on the glass transition temperature (T_g) of the polymer. A relatively hard or at least a non-tacky surface is often a desirable paint property. To attain such properties, the glass transition temperature of the polymer should typically be rather high, or the polymer should be cross- linked. Because coalescence of a polymer is dependent on the glass transition temperature thereof, coalescent agents are generally added to latex paints for film forming at low or moderate temperatures.

Coalescent agents are often organic solvents that evaporate to the environment as the paint dries and cures, thus causing odour, occupational safety and pollution problems. Accordingly, traditional coalescing agents contribute to the increase of volatile organic compounds (VOC) in the environment and to total emissions from paints, which are also restricted by legislation.

WO 00/44836 discloses paint compositions wherein glycidyl ethers and glycidyl esters are used as coalescent agents. Cycloaliphatic epoxide esters without R bridge in formula II are known from publications Wu, S., Soucek, M.D.; Oligomerization Mechanism of Cyclohexene Oxide, Polymer 39 (1998) 3583 - 3586 and Mark, H., Encyclopedia of Polymer Science and Engineering, Epoxy Resins, Vol. 6. John Wiley & Sons, USA 1986, 32-382.

An object for the development of coalescent agents is to introduce on the market substitutes therefore not belonging to VOC component class. However, a drawback of several widely used non-volatile or slowly evaporating components is their inherent plasticizing property causing slow build-up of the paint film hardness, and accordingly, the paint film may even remain soft. Thus, the development is at present focused on reactive coalescent agents, which not only decrease the film forming temperature but also react to become an integral part of the coating film, thus minimizing emissions.

Due to structures of known reactive compounds of the prior art, the effect thereof on reducing film-forming temperatures is often very weak compared to normal volatile, or to so-called no-VOC coalescent agents. In addition to the reactive compounds, also traditional coalescent agents must be used to reach film-forming temperatures required in paint applications.

Objects of the Invention

An object of the invention is to provide novel aliphatic epoxides containing polar groups, preferably ether or ester groups.

Another object of the invention is the use of aliphatic epoxides containing polar groups, preferably ether or ester groups, in coating compositions as coalescent agents and/or as reactive diluents. Still another object of the invention is to provide coating compositions comprising aliphatic epoxides containing polar groups, preferably ether or ester groups.

Further, an object of the invention is to provide a method for producing aliphatic epoxides containing polar groups, preferably ether or ester groups.

Still an object of the invention is to provide a method for accelerating the curing of coating compositions.

Characteristic features of the aliphatic epoxides of the invention containing polar groups, the use thereof in coating compositions as coalescent agents and/or as reactive diluents, the coating compositions comprising such epoxides, and the method for producing aliphatic epoxides containing polar groups are presented in the appended claims.

Summary of the Invention

According to the invention, an ether or ester of an ethylenically unsaturated or saturated alcohol containing 2 - 20 carbon atoms with an ethylenically unsatu- rated alcohol or a carboxylic acid, all double bonds or at least part of the double bonds of said ether or ester being oxidized to give epoxy groups, may be used as a coalescent agent and/or as reactive diluents in aqueous or solvent-based coating compositions.

Detailed Description of the Invention

It was surprisingly found that the problems of the known solutions of prior art may be eliminated or at least substantially reduced by the procedure of the invention. The invention is based on the finding that aliphatic epoxides containing a hydrocarbon residue, preferably a large hydrocarbon residue, including linear aliphatic, branhed aliphatic and cycloaliphatic epoxide ethers and epoxide esters, provide excellent coalescent properties, and further, that they may readily be dispersed in water and solvents, the solubility thereof in binder polymers present in the coating being good and they act well as reactive diluents. This is due to particularly suitable molecular sizes, the presence of polar groups, and high boiling points of above 200 °C.

According to the invention, one or more ether(s) or ester(s) of an ethylenically unsaturated or saturated alcohol containing 2 - 20 carbon atoms with an ethylenically unsaturated alcohol or a carboxylic acid, all double bonds or at least part of the double bonds of said ether or ester being oxidized to give epoxy groups, are used as coalescent agents in coating compositions based on water or solvents. Said compounds contain no glycidyl groups. Such compounds may totally or partly be substituted for present coalescent agents, particularly for reactive coalescent agents and reactive diluents in coating compositions. Curing of coating film may be significantly accelerated using these agents.

The invention is now illustrated in more detail with the following description and finally by means of some examples.

According to the invention, aliphatic epoxides, which may be linear aliphatic epoxide compounds, branched aliphatic epoxide compounds or cycloaliphatic epoxide compounds, containing or more epoxy group are used as coalescent agents in coating compositions.

The first group of the present aliphatic epoxide coalescent agents is formed of linear aliphatic epoxides and branched aliphatic epoxides and the second group is formed of cycloaliphatic epoxides.

The first group consists of aliphatic epoxide compounds that may be aliphatic ethers or esters. In aliphatic ethers, the alcohol residue derived from a linear or branched monohydric alcohol, diol, triol, tetraol, or pentol with 2 - 20 carbon at- oms forms one or more ether group(s) with a linear or branched, saturated or ethylenically unsaturated alkyl halide.

Respectively, alcohol residues of aliphatic esters derived from a linear or bran- ched monohydric alcohol, diol, triol, tetraol, or pentol with 2 - 20 carbon atoms form one or more ester group(s) with a linear or branched, saturated or ethylenically unsaturated carboxylic acid.

The general Formula I below shows the structure of the aliphatic linear and branched epoxide compounds,

O R R²C — CR³R⁴ (I)

wherein R¹ and R³ independently represent either hydrogen or a linear or branched, ethylenically unsaturated or saturated Cι-Cι₆ hydrocarbon, further, one or both of R¹ and R³ may contain one or more epoxy group(s), preferably R¹ and R³ represent H 1 "\ or a Cι-C₈ hydrocarbon, particularly preferably R and R represent H or a Cι-C₆ hydrocarbon;

R² and R⁴ independently represent either hydrogen or a linear or branched, ethylenically unsaturated or saturated Cι-C₂o hydrocarbon, or ~(CH₂)_n-COOR⁵ or - (CH₂)_m-OR⁶, wherein the groups R⁵ and R⁶ independently represent a linear or branched, ethylenically unsaturated or saturated C₄-Cι₆ hydrocarbon optionally having one or more epoxy group(s) or ester group(s), preferably the groups R⁵ and R⁶ represent C -Cιo hydrocarbons, particularly preferably the groups R⁵ and R⁶ represent C -C₈ hydrocarbons, and further, R² and R⁴ preferably represent H or C -Cιs hydrocarbons, n being from 0 to 14 and m being from 2 to 14, preferably n = 2 - 10 and m = 2 - 10, and particularly preferably, R² and R⁴ each represent H or a C -Cιo hydrocarbon. According to the invention, said aliphatic linear and branched epoxide compounds may have from 1 to 6, preferably from 2 to 4 epoxy groups. The epoxy groups originate from the oxidation of the double bonds present in alcohol and/or carboxylic acid residues of the ethers and esters. Aliphatic ether and ester derivatives from di- and polyols may also be di-, tri-, tetra-, or pentaethers and -esters. Carboxylic acid residues of the ester derivatives may be derived from linear or branched mono- or polybasic carboxylic acids with 2 - 20, preferably with 4 - 18 carbon atoms. Polybasic acids give mono-, di-, tri- etc. esters. Said esters may also comprise mixed esters.

The second group of the present coalescent agents is formed by cycloaliphatic epoxides. In cycloaliphatic epoxide esters, the alcohol residue is derived from a linear or branched, mono- or polyhydric alcohol with 2 - 20 carbon atoms. The alcohol residue may also be derived from an oligo- or polyether formed from two or more diols.

Carboxylic acid residues of cycloaliphatic epoxide esters originate from a Diels- Alder reaction between a diene and a dienophile having a carboxylic group. Cycloaliphatic epoxide esters may have from 1 to 4 epoxy groups obtained by oxydation of the double bonds in alcohol and/or carboxylic acid residues. Said esters may also have ether groups derived from a diene.

The general Formula II below shows the structure of cycloaliphatic epoxide esters

wherein R⁷ represents -O-, -CH₂-, or -CH₂CH₂-;

R represents hydrogen, or a linear or branched, ethylenically unsaturated or saturated C₂-C₂o hydrocarbon that may have one or more epoxy group(s) and/or ether group(s), R⁸ preferably representing a C₂-Cιo hydrocarbon, and particularly pref- erably R representing a C₂-C₆ hydrocarbon.

R⁹ represents either hydrogen or a methyl group; and

k = 0 or l.

Exemplary aliphatic epoxide esters from monohydric alcohols of the invention include 2-methylpentyl-9,10-epoxydecanoate and 2-methyl-(oxiranyl)methyl- 9,10-epoxydecanoate, whereas epoxide esters derived from dihydroxy alcohols are exemplified by 2-butyl-2-ethylpropyl-l,3-di(9,10-epoxyoctadecanoate), 2,2- dimethylpropyl-l,3-di(9,10-epoxydecanoate), and ethyleneglycol di(2,3-epoxy- propanoate).

Cycloaliphatic epoxide esters of the invention include diethyleneglycol di(5,6- epoxy-2-norbornane carboxylate), and neopentylglycol di(5,6-epoxy-2-norbor- nane carboxylate).

Ethyleneglycol di(2,3-epoxypropanoate), 2-butyl-2-ethylpropyl- 1 ,3-di(9, 10- epoxyoctadecanoate), 2,2-dimethylpropyl-l,3-di(9,10-epoxydecanoate), 2- methylpentyl-9,10-epoxydecanoate, and diethyleneglycol di(5,6-epoxy-2- norbornane carboxylate) are novel compounds.

2-methylpentyl-9,10-epoxydecanoate, 2-methyl-(oxiranyl)methyl-9,10-epoxy- decanoate, 2,2-dimethylpropyl-l,3-di(9,10-epoxydecanoate), and diethyleneglycol di(5,6-epoxy-2-norbornane carboxylate) are preferable coalescent agents. Novel epoxide compounds of the invention with the epoxide in a non-glycidyl position are prepared by oxidizing a double bond.

Aliphatic linear and branched epoxide ethers of the invention may be produced using the following synthesis comprising two steps, the first step comprising ether formation followed by epoxidation in the second step.

In the first step, or Williamson ether synthesis, an alkyl halide is allowed to react with an alcohol. Said etherification is carried out in a basic medium, preferably in the presence of potassium hydroxide. In the reaction system, toluene, DMSO, DMF, or THF may serve as the solvent of the organic phase. Etherification is conveniently carried out at normal atmospheric pressures, and at temperatures ranging from 0 to 80 °C. The reaction is preferably carried out at temperatures above 25 °C. The product is recovered from the organic phase by extraction, filtration, and vacuum distillation. Typically, the molar ratio of the alkyl halide to the hy- droxyl groups of the alcohol reactant is from 1.0 to 1.1 fold.

In the second step, an oxidation of the double bonds present in the ether to give epoxy groups may be achieved by allowing the ethylenically unsaturated ether to react with m-chloroperbenzoic acid, or with peracetic acid. Preferable solvents include ethers and halogenated hydrocarbons. Also a solution of peracetic acid in acetic acid, and perbenzoic acid may also used to selectively oxidize the double bonds. Epoxidation is preferably carried out by reacting an ethylenically unsaturated ether with m-chloroperbenzoic acid, dichloromethane serving as the solvent. The reaction is allowed to proceed at 20 - 35 °C at least for 1 hour until the yield of the epoxide ether is at least 80 %, typically at least over 90 %. Preferably, the molar ratio of the peracid to the double bonds of the ether reactant is from 1.1 to 1.3. The product is suitably recovered by washing the reaction mixture with sodium bisulfite solution, water, and a basic solution, and further by separating the organic layer and evaporating to dryness. Terminal double bonds may be oxidized to give epoxy groups using aqueous hydrogen peroxide in a biphasic system, methyltrioxorhenium serving as the catalyst and 3-cyanopyridine or pyrazole serving as the phase transfer agent of the catalyst. Ethers or chlorinated hydrocarbons, preferably dichloromethane, may be used as solvents. The reaction is allowed to proceed for instance at 20 - 30 °C for at least 6 hours until the yield of the epoxide is at least 80 %, typically at least 85 %. Preferably, the molar ratio of hydrogen peroxide to the reacting double bonds of the ether is from 1.5 to 3.0 fold. The amount of the catalyst used is preferably from 0.3 to 0.7 % by moles, the amount of 3-cyanopyridine being from 7 to 13 % by moles. The reaction is terminated by adding to the reaction mixture ice and a catalytic amount of manganese dioxide. The product may suitably be recovered from the mixture by extracting with organic solvents, preferably with dichloromethane, by concentrating to give an oil, by precipitating the 3-cyanopyridine N- oxide formed in the reaction with hexane, by filtration and evaporation to dryness.

Aliphatic linear and branched epoxide esters of the invention may be produced using the following synthesis comprising two steps, the first step comprising es- terification followed by epoxidation in the second step.

In the first step, the reaction temperature for the actual esterification varies typically from 110 to 190 °C, more suitably from 120 to 170 °C. The reaction is carried out at normal atmospheric pressures. Relative to the esterifying agent, about 0.1 - 10 % by moles of a catalyst may be used for the esterification. Suitable esterification catalysts include p-toluene sulfonic acid, benzene sulfonic acid, sulfu- ric acid, tin and zinc salts or oxides, and titanates. Suitable transesterification catalysts include alkali metal alkoxides such as potassium or sodium alkoxides, sulfu- ric acid, hydrochloric acid, and acidic ion exchange resins.

According to a preferable embodiment, the esterification is achieved by reacting a saturated or ethylenically unsaturated carboxylic acid having a straight or branched chain and having from 2 to 20 carbon atoms, with a saturated or ethyleni- cally unsaturated mono- or polyhydric alcohol having a straight or branched chain and having from 2 to 20 carbon atoms. Toluene or xylene may be used for removing water formed in the reaction. Toluene or xylene serving as the solvent, a typical temperature range during the reaction is about from 120 to 150 °C. Then the reaction is allowed to proceed at least for 2 hours at said temperature, while water being formed in the reaction is removed to a separate intermediary device for water collection until the ester yield is at least 90 %, typically at least 97 %. Typically, the molar ratio of the carboxylic acid to the hydroxyl groups of the alcohol reactant is from 1.0 to 1.1 fold. As an esterification catalyst, p-toluene sulfonic acid is preferably used in an amount from 0.5 to 1.0 % by moles relative to the amount of the compound to be esterified. The product is suitably recovered by washing the catalyst and the excessive acid from the reaction mixture with a basic solution, and then by separating the organic layer and evaporating to dryness.

In the second step, the oxidation of the double bonds present in the ester to form epoxy groups may be carried out in an analogous way described above for the ethers.

Cycloaliphatic epoxide esters of the invention may be prepared at least with the two methods described in the following.

Cycloaliphatic epoxide esters may be produced by reacting a diene such as cyclo- pentadiene or furane with a (meth)acrylate ester such as methyl, ethyl or butyl (meth)acrylate in the first step. In the second step, the Diels-Alder product is transesterified in a single step or an ester group is hydrolyzed to give a carboxylic acid group followed by preparation of an acid chloride from the acid. In the third step, the acid chloride is allowed to react with an alcohol, for instance with di- ethylene glycol or neopentyl glycol. In the final step, the double bonds present in the ester are oxidized for instance with m-chloroperbenzoic acid or peracetic acid to form epoxy groups. Cycloaliphatic diesters of the invention may also be prepared with the following method.

Cycloaliphatic diesters may be prepared by allowing one of the above dienes to react with a di(meth)acrylate ester such as with ethyleneglycol dimethacrylate, di(ethyleneglycol)dimethacrylate or di(ethyleneglycol)diacrylate in the first step, followed by oxidation of the double bonds present in the cycloaliphatic ester to form epoxy groups in the second step.

A catalyst used in the first step of a preferable embodiment, preferably aluminium chloride, lithium perchlorate, or diethyl aluminum chloride, is suspended in a solvent, preferably to toluene, or dichloromethane. The reaction may also be carried out thermally without any catalyst. An acrylate ester, preferably methyl acrylate, followed by the diene dissolved to the reaction solvent, preferably freshly cracked cyclopentadiene is added to the suspension. The reaction is allowed to proceed at a temperature ranging from -80 to +30 °C, preferably from 0 to 20 °C for at least 30 minutes, then the catalyst is washed with water from the reaction mixture, followed by separation of the organic layer and evaporation thereof to dryness. The product may be further purified by distillation. It has surprisingly been found that for instance the methyl ester of 5-norbornene 2-carboxylic acid may be produced with high yields (typically at least 75 %) and in an highly pure form (purity over 99 %).

In the second step, the free carboxylic acid is produced by hydrolyzing the ester preferably with a NaOH solution (5 - 15 %), typically at 40 - 70 °C at least for 30 minutes until the ester layer has completely disappeared. The product is recovered by acidifying the basic solution with for instance hydrochloric acid solution, by separating the acid layer formed, washing and evaporating to dryness. Acid chloride is prepared by further dissolving the free acid to an organic solvent such as dichloromethane and by adding oxalyl chloride and N,N-dimethylformamide to the solution. Also thionyl chloride may be used to produce the acid chloride. The mixture is agitated at 0 - 30 °C at least for one hour until the yield of the acid chloride is no less than 85 %. The product is recovered from the reaction mixture by evaporation of the solvent, and the excessive oxalyl chloride. The amount of oxalyl chloride is preferably 3 - 7 times the amount of the carboxylic groups of the acid, the amount of N,N-dimethyl formamide being 0 - 1.0 times the amount of oxalyl chloride.

In the third step, the mono- or diester is prepared by adding the acid chloride to a mixture of a mono- or dialcohol, e.g. diethyleneglycol, and pyridine. The reaction is allowed to take place at 10 - 30 °C for at least two hours until the ester yield is no less than 90 %, normally at least 95 %. The product is recovered by extracting the reaction mixture with dichloromethane, washing the organic phase, drying and evaporating to dryness. Both pyridine and alcohol are preferably used in amounts of 1.0 molar equivalents relative to the acid chloride.

In the final step, the double bonds present in the ester are oxidized to give epoxy groups. This epoxydation is preferably carried out by reacting the ethylenically unsaturated ester with peracetic acid while dichloromethane serves as the solvent. The reaction is suitably carried out at 10 - 35 °C for at least two hours until the epoxide ester yield is no less than 90 %, typically at least over 95 %. The molar ratio of the peracid to the double bonds in the ester reactant is from 1.1 to 1.6 fold. The product is recovered by washing the reaction mixture with water and a basic solution followed by separation of the organic layer and evaporation thereof to dryness. It has surprisingly been found that for instance diethyleneglycol di(5,6- epoxy-2-norbomane carboxylate) may be produced with a very high yield (yield more than 96 %) in an highly pure form (purity over 94 %).

Acids suitable for the production of the esters of the invention generally include saturated or ethylenically unsaturated mono- or dicarboxylic acids having a straight or branched chain and from 2 to 20, preferably 4 - 18 carbon atoms. Acids particularly suitable as starting materials of aliphatic epoxide esters used in coating compositions include fatty acids such as oleic acid, linolenic acid, and linolic acid, natural oils such as tall oil, linseed oil, and rapeseed oil, acrylic acid, methacrylic acid, adipic acid, fumaric acid, maleic acid, succinic acid, glutaric acid, 9-decenoic acid, 6-heptenoic acid, 2-, 3- and 4-pentenoic acids, crotonic acid, vinyl acetic acid, 2-hexenoic acid, and 2-ethyl-2-hexenoic acid.

Alcohols suitable for the invention that may be used to produce epoxide ethers and esters include the following monohydric alcohols, diols and triols. Alcohols suitable for the present purpose include saturated or ethylenically unsaturated mo- nohydric alcohols, diols and triols having a straight or branched chain and from 2 to 20 carbon atoms. Alcohols particularly suitable as starting materials of aliphatic epoxide esters used in coating compositions may be exemplified by such monohydric alcohols as crotyl alcohol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2- methyl-1-pentanol, isopentanol, 1-hexanol, 2-ethylhexanol, 2-ethyl-2-hexen-l-ol, 1-heptanol, 1-octanol, such diols as 2-ethyl-l,3-hexanediol, ethylene glycol, di- ethylene glycol, neopentyl glycol, 2-butyl-2-ethyl-l,3-propane diol, methylpro- pane diol, 1,4-butane diol, 1,6-hexane diol, 1,2- and 1,3-propane diols, and 1,2-, 1,3-, and 1,4-butane diols, and such triols as trimethylol ethane, trimethylol propane, and among pentaols, pentaerythritol. Alcohols suitable for the invention that may be used to produce cycloaliphatic epoxide esters are for instance above monohydric alcohols and diols.

Alkyl halides suitable in the invention for producing ethers include 4-bromo-l- butene, and 5-bromo-l-pentene.

Suitable dienes for producing cycloaliphatic epoxide compounds of the invention include cyclopentadiene, furane, and 1,3-cyclohexadiene.

Dienophiles preferable for the invention include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Aliphatic and cycloaliphatic epoxide derivatives may be used for producing various compositions. They may for instance be added to aqueous or solvent-based dispersions containing binders as well as additives and excipients known as such. It is particularly preferable to produce aqueous dispersions. Binders known for latex paints such as polyvinyl acetates, polyacrylates, and copolymers thereof may serve as binders.

Generally, polyvinyl acetates and polyacrylates consist of polymers of ethylenically unsaturated monomeric units preferably produced using emulsion polymeri- zation technique. Said monomers are typically selected from a group consisting of vinyl acetate, vinyl alcohol, ethylene, propylene, butadiene, styrene, acryl nitrile, itaconic acid, maleic acid, fumaric acid, acrylic and methacrylic acids, and branched or linear Cι-C₉ esters, particularly C₂-C₈ esters thereof. Typical useful esters of (meth)acrylic acid include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, butyl acrylate, butyl methacrylate. The polymer may also comprise monomers having several reactive groups. Typical reactive groups present in the monomers include hydroxyl groups (e.g. hydroxy ethyl (meth)acrylate), amine gropus, car- bonyl groups (e.g. diacetone acrylate, diacetone acrylamide, acrolein, acetoace- toxy ethyl methacrylate), urea groups, and epoxide groups (e.g. glycidyl methacrylate). It is also possible to use other monomers, typical examples of which include acryl amide and derivatives thereof (e.g. N-methylol acrylamide and N-isobutoxy methyl acrylamide, and various compounds having more than one double bond, such as divinyl benzene. Binders that may be dispersed in water, exemplified by various water-soluble polymers such as polyvinyl alcohol (PVA), starch, carboxy methyl cellulose (CMC), and hydroxy ethyl cellulose, may also be used.

In addition to above compounds, also alkyd resins may be used as binders. They normally include condensation products of a bivalent polyol and a fatty acid or a natural oil. The aliphatic epoxide compounds of the invention may be used in coating compositions including paint, varnish, joint mortar, filler mortar, mortar, and adhesive compositions, preferably in aqueous compositions, and particularly preferably in compositions based on latexes, for instance in paints containing a binder that forms a film after the coating has dried. The amount of the polymer dispersion serving as a binder in the coating composition typically varies between 20 % and 80 %. Suitable binders include e.g. polyacrylate latexes wherein styrene is polymerized with one or more acrylate or methacrylate monomer(s). Such latexes are represented by carboxy functional styrene-acrylate latexes such as styrene- methylmethacrylate or styrene-butyl acrylate latexes. Examples of preferable monomer combinations include styrene-butyl (meth)acrylate-(meth)acrylic acid, styrene-2-ethylhexyl (meth)acrylate-(meth)acrylic acid, methyl (meth)acrylate- butyl (meth)acrylate-(meth)acrylic acid, and methyl (meth)acrylate-butyl (meth)acrylate-hydroxy ethyl (meth)acrylate. The use of the coalescent agents of the invention in combination with styrene-butyl acrylate-(meth)acrylic acid and a commercially available styrene-acrylate-latex (Dispersion A) is described in Example 5 below.

The polymer typically comprises from 20 to 80 %, preferably from 40 to 60 % of the dispersion. In addition to the polymer and water, the polymer dispersions typically contain one or more surface- active agent(s), preserving agents, antifoam agents, and agents for pH control, for instance aqueous ammonia. Dispersing and thickening agents may be mentioned as other possible additives and excipients.

Coating compositions contain reactive coalescent agents of the invention in amounts varying between about 0.01 and 20 %, preferably 0.1 and 15 %, by weight. The coalescent agent in the coating composition may consist of the epoxide compound of the invention alone, a mixture of such epoxide compounds, or a mixture of the epoxides and conventional coalescent agents. In general, the epox- ide compounds comprise at least 20 % by weight, preferably at least 50 % of the total amount of the coalescent agents present. Moreover, it was found out that the aliphatic epoxides according to the invention can also act as efficient reactive diluents in coating compositions.

The present aliphatic epoxide derivatives are preferably used in combination with known coalescent agents of the prior art or mixtures thereof having a boiling point of at least 250 °C at normal atmospheric pressure. Conventional coalescent agents include e.g. phenyl ethers of ethyleneglycol, monoisobutyrate of 2,2,4-trimethyl- 1,3-pentanediol (for instance Texanol®), n-butylether acetate of diethyleneglycol, as well as mono-n-butylether of dipropyleneglycol, and mono-n-butylether of trip- ropyleneglycol (Dowanol DPnB® and Dowanol TPnB®, respectively).

The present epoxide derivatives are capable of significantly accelerating the development of hardness of coating compositions alone or in combination with known coalescent agents. According to the solvent resistance test, at least 90 % of the final hardness of the film may be attained within 24 hours at room temperature, and even in a shorter period of time at elevated temperatures if the coalescent agents of the composition comprise at least 20 %, preferably at least 50 % of the epoxide derivatives of the invention.

For the stability of present coalescent agents and for the use of the coating compositions, it is preferable that the pH value of the coating compositions is neutral, slightly basic or acidic, more preferably neutral or slightly acidic. The pH value of the coating composition is more preferably less than about 8.5, most preferably below 8.0.

The compounds of the invention may be used for producing both 1 -component and 2-component coatings wherein the other component is added only prior to the use of the coating composition In the examples, the present coalescent agents are compared with commercially available products. In coating compositions, the epoxide compounds of Examples 1 - 4 have a lowering effect on the film forming temperature. As may be seen from the Table 1, the VOC indexes of all epoxide compounds produced are at least higher than 1500, usually higher than 2000, and accordingly, due to low volatilities, the use thereof is safer that that of traditional reactive coalescent agents, and moreover, they are not classified as VOC compounds. Table 1 VOC indexes of the compounds prepared in Examples 2 - 4

^a VOC index RI = 1000* (t_a/tα ), wherein t_a represents the retention time of the epoxide compound analyzed, and tα is the retention time of tetradecane used as the internal standard.

The resistance of the coating films to solvents was clearly higher, especially at elevated temperatures in cases where reactive coalescent agents were added to acrylate dispersions. On the basis of the results from a MEK abrasion test, the present epoxide compounds have a clearly beneficial influence on cross-linking of the polymer, and accordingly, on the development of hardness.

Considerable advantages are attained with the present invention. Thus, with the coalescent agents of the invention, a good dispersion is provided in coating com- positions, probably due to the weakly polar ether bond or the more polar ester bond. Surprisingly, several of the compounds also have mould inhibiting action. Also, due to the relatively large hydrocarbon group of the ether or ester, the novel coalescent agents lower the film forming temperature more effectively compared to the normally used siloxanes or epoxide compounds. Due to low volatilities of the compounds, they may be used in so-called no- VOC applications, particularly if the boiling points of the compounds are above 200 °C. In addition, due to the reactive epoxy groups present in the compounds, the coalescent agents may react to become an integral part of the coating film, thus lowering total emissions, and further, the hardness of the coating film may build up favourably owing to cross- linking reactions. Moreover, since most of the compounds are bifunctional, curing, or cross-linking, will be more efficient than in case of monofunctional compounds.

With the compounds of the present invention, curing of the film may be accelerated to attain at least 70 % of the final hardness already within about 24 hours. Present epoxide compounds may be used in combination with known coalescent agents.

The invention will now be illustrated with following Examples without, however, wishing to limit the scope thereof.

Examples

Example 1

Preparation of 2-butyl-2-ethylpropyl-l,3-di(9,10-epoxyoctadecanoate)

0.169 mol (27.4 g) of 2-butyl-2-ethyl-l,3-propanediol and 0.354 mol (100 g) of oleic acid were dissolved in toluene. The mixture was heated to 80 °C, and 1.69 mmol (325 mg) of p-toluenesulfonic acid was added thereto. The mixture was refluxed for 6 h at 130 - 140 °C, while removing water formed in the reaction using toluene to an intermediary device for water collection. Toluene was removed by vacuum distillation and the raw product was dissolved in ethyl acetate. Organic phase was washed with sodium bicarbonate solution, water, and saturated sodium chloride solution. Organic phase was separated, dried with Drierite, fil- tered and concentrated to dryness. The yield was 113.4 g (98 %). H and C NMR spectra showed that the product was a relatively pure ester.

178 mmol (43.88 g) 70 % m-chloroperbenzoic acid dissolved in 700 ml of di- chloromethane was added to 80.7 mmol (55.7 g) of the ester obtained above in 90 minutes by dropwise addition. After this addition, the mixture was intensely agitated for 4 hours. During and after the addition, the temperature was maintained at 23 - 30 °C. The reaction mixture was washed with sodium bisulfite solution, water, sodium bicarbonate solution, water, and saturated sodium chloride solution. Organic phase was separated, dried with Drierite, filtered and concentrated to dryness. The yield was 46.02 g (79 %). 1H and ¹³C NMR spectra showed that the product was relatively pure 2-butyl-2-ethylpropyl di(9,10-epoxyoctadecanoate). Example 2

Preparation of 2,2-dimethylpropyl-l,3-di(9,10-epoxydecanoate)

0.135 mol (14.0 g) of 2,2-dimethyl-l,3-propanediol and 0.282 mol (51.1 g) of 9- decenoic acid were dissolved in toluene. The mixture was heated to 80 °C, and 1.35 mmol (256 mg) of p-toluenesulfonic acid was added thereto. The mixture was refluxed for 5 h at 120 - 125 °C, while removing water formed in the reaction using toluene to an intermediary device for water collection. Toluene was removed by vacuum distillation and the crude product was dissolved in ethyl acetate. Organic phase was washed with sodium bicarbonate solution, water, and saturated sodium chloride solution. Organic phase was separated, dried and concentrated to dryness. The yield was 52.8 g (96 %), the purity being 94 % (GC).

73.4 mmol (30.0 g) of the ester obtained above, 14.7 mmol (1.53 g) of 3- cyanopyridine, and 0.734 mmol (183 mg) of methyltrioxorhenium were dissolved in 60 ml of dichloromethane. 294 mmol (30.0 ml) of 30 % aqueous hydrogen peroxide was added to the solution in 20 minutes. The temperature of the mixture was maintained at 22 - 25 °C using a water bath. The biphasic reaction was allowed to proceed for 23 hours at 22 - 24 °C while intensively agitating the mixture. 15 g of crushed ice and 20 g of MnO were added to the mixture followed by agitation until no more oxygen was liberated. The layers were separated, followed by extraction of the aqueous phase with dichloromethane, drying of the organic phase with Drierite, filtration and concentration with vacuum distillation to give an oil. Hexane was added to the crude product and the precipitate formed was filtered off. Filtrate was concentrated to dryness, giving yellow oily residue. For colour removal, the oil (30.8 g) was dissolved in 500 ml of hexane, and then 20 g of silica was added. The mixture was agitated for 20 minutes, filtered, followed by concentration to dryness. The residue was a colourless oil. The yield was 26.3 g (81 ), the purity being 84 % (GC).

Example 3

Preparation of 2-methylpentyl-9,10-epoxydecanoate

The synthesis comprising two steps was carried out as in Example 2 using in the esterification 129 mmol (13.2 g) of 2-methyl-l-pentanol, 135 mmol (23.0 g) of 9- decenoic acid as starting materials, 1.29 mmol (245 mg) of p-toluenesulfonic acid as the catalyst, and 15 ml of toluene as the solvent. The yield was 31.5 g (96 %), the purity being 94 % (GC).

Production of epoxide was carried out as in Example 2 using 124 mmol (31.5 g) of the ethylenically unsaturated ester from the above step, 12.4 mmol (1.29 g) of 3-cyanopyridine, 0.622 mmol (155 mg) of methyltrioxorhenium, 248 mmol (25.3 ml) of 3 % aqueous hydrogen peroxide as starting materials, and 70 ml of dichloromethane as the solvent. The yield was 28,4 g (85 %), the purity being 93 % (GC). Example 4

Preparation of diethyleneglycol di(5,6-epoxy-2-norbornane carboxylate)

pyr ne

0.510 mol (68.0 g) of anhydrous aluminium chloride was suspended in 660 ml of toluene. 0.600 mol (51.7 g) of methyl acrylate was added to the suspension. The mixture was agitated until aluminium chloride was completely dissolved. 0.600 mol (39.7 g) of freshly cracked cyclopentadiene dissolved in 340 ml of toluene was added to the solution in 45 minutes. The reaction mixture was agitated at room temperature for 90 minutes, followed by pouring in water. The toluene layer was washed with water, dried with anhydrous sodium sulfate, filtered and concentrated to dryness in vacuum. The 5-norbornene-2-carboxylic acid methyl ester obtained as the product was purified by vacuum distillation using a Vigreux col- umn. The yield was 66.3 g (74 %), the purity being 99 % (GC).

The 5-norbornene-2-carboxylic acid was prepared by mixing 164 mmol (25.0 g) of the methyl ester with 85 g of 10 % NaOH solution at 60 °C until the ester layer disappeared. Further, the solution was cooled, washed with diethyl ether and pou- red to 235 ml of 1 M hydrochloric acid at 60 - 70 °C while agitating. The acid layer formed was separated, dissolved in ethyl acetate, washed with water, dried with anhydrous sodium sulfate, filtered and concentrated to dryness in vacuum. The yield was 18.2 g (80 %). 1H and ¹³C NMR spectra showed that the product was a relatively pure 5-norbornene-2-carboxylic acid. 132 mmol (18.2 g) of the acid was dissolved in 480 ml of dichloromethane, and the mixture was added with 2.66 mmol (0.205 ml) of N,N-dimethyl formamide, and 665 mmol (57.0 ml) of oxalyl chloride dropwise in 1 hour. The mixture was agitated at room temperature for 1.5 hours. The solvent and the oxalyl chloride excess was removed by evaporation at reduced pressure, giving a brownish oil as the residue. The yield was 18.1 g (88 %).

The diester was prepared by adding 115 mmol (18.0 g) of the acid chloride from the previous step to a mixture of diethylene glycol (57.5 mmol, 6.10 g) and pyri- dine (115 mmol, 9.09 g) at room temperature. The mixture was agitated at room temperature for 4 hours, followed by the addition of 150 ml of dichloromethane and 100 ml of water to the mixture. The organic layer was further washed with water, sodium bicarbonate solution and hydrochloric acid solution, followed by drying with anhydrous sodium sulfate. The mixture was filtered and concentrated to dryness to give a yellow oil as the residue. The yield was 18.9 g (95 %). 1H and ¹³C NMR spectra showed that the product mainly consisted of a diester.

Diethyleneglycol di(5,6-epoxy-2-norbornane carboxylate) was prepared by dissolving 54.5 mmol (18.9 g) of the diester from the above step to 260 ml of di- chloromethane. Further, 15.3 mmol (2.08 g) of sodium acetate trihydrate was dissolved in 39 % solution of peracetic acid in acetic acid (153 mmol, 29.8 g). The mixture was added dropwise to the diester solution in 30 minutes. The reaction mixture was agitated for 4 hours at room temperature. After the agitation, the reaction mixture was washed with water and sodium bicarbonate solution. The or- ganic phase was dried with anhydrous sodium sulfate, filtered and concentrated to dryness to give pale yellow oily diethyleneglycol di(5,6-epoxy-2-norbomane carboxylate) as the resiue. The yield was 19.8 g (96 %), the purity being 94 % (GC). The structure of the product was confirmed with 1H and ¹³C NMR spectra. Example 5

Use of the prepared epoxide derivatives as reactive coalescent agents in aqueous compositions

Performance of the coalescent agents prepared in Examples 1 - 4 was tested by preparing mixtures of a commercially available styrene-acrylate-latex (Dispersion A) mixed with 6 % by weight of epoxide esters. Table 2 below shows the influence of the epoxide derivatives prepared in Examples 2 - 4 on the minimum film forming temperature of the Dispersion A in comparison to commercially available non-reactive coalescent agents, butyldiglycol acetate (BDGA) and butylglycol (BG). MFFT of dispersion A = 16 °C. The reactive coalescent agent was added 6 % by weight. The minimum film forming temperature (MFFT) was measured according to the standard ASTM 2354/86 using a Coesfeld Gradient Plate- Thermostair device.

Table 2

The performance of the coalescent agent prepared in Example 2 in paint mixtures was further tested by preparing a mixture of a commercially available styrene- acrylate-latex (Dispersion A) with 6 % by weight of a reactive coalescent agent. A mixture was also prepared from a poly(styrene-co-n-butyl acrylate-co-methacrylic acid)latex by adding thereto a reactive coalescent agent in an equimolar amount, relative to carboxylic acid groups. A commercially available coalescent agent, butyl diglycol acetate, served as control. Table 3 below shows the influence of the reactive coalescent agent prepared in Example 2 on the solvent resistance of two different dispersions (MEK abrasion test, ASTM D 4752) in comparison to a commercially available coalescent agent.

Table 3

^a poly(styrene-co-n-butyl acrylate-co-methacrylic acid), indicated as % by weight, relative to dry weight. A (reactive) coalescent agent added in an equimolar amount. h Coalescent agent in an amount of 6 % by weight.

Claims

1. Use of one or more aliphatic epoxide(s) in coating compositions, characterized in that the aliphatic epoxide is an aliphatic linear or branched epoxide ester or epoxide ether of the general formula I or a cycloaliphatic epoxide ester of the general formula II, wherein in formula I

O R R C — CR³R⁴ (I)

R¹ and R³ independently represent either hydrogen or a linear or branched, ethylenically unsaturated or saturated Ci-Ciβ hydrocarbon, further, one or both of R¹ and R may contain one or more epoxy group(s);

R² and R independently represent either hydrogen or a linear or branched, ethy- lenically unsaturated or saturated Cι-C₂o hydrocarbon, or -(CH₂)_n-COOR⁵ or -(CH₂)_m-OR groups, wherein the groups R and R independently represent a linear or branched, ethylenically unsaturated or saturated C₄-Cι₆ hydrocarbon optionally having one or more ester group(s) or epoxy group(s), and n = 0 - 14 and m = 2 - 14; and

wherein in formula II

R⁷ represents -0-, -CH₂-, or -CH₂CH₂-;

R represents hydrogen, or a linear or branched, ethylenically unsaturated or saturated C₂-C₂o hydrocarbon that may have one or more ether group(s); R⁹ represents either hydrogen or a methyl group; and

k = 0 or 1.

1 T

2. Use according to Claim 1, characterized in that the groups R and R are each H or a Cι-C₈ hydrocarbon, preferably H or a Cι-C₆ hydrocarbon, and group R⁸ represents a C -Cιo hydrocarbon, R⁸ preferably representing a C₂-C₆ hydrocarbon.

3. Use according to Claim 1 or 2, characterized in that the groups R⁵ and R⁶ are C -Cιo hydrocarbons and the groups R² and R⁴ are H or C -Cι₈ hydrocarbons, preferably R⁵ and R⁶ are C₄-C₈ hydrocarbons and R² and R⁴ are H or C -Cιo.

4. Use according to any one of Claims 1 - 3, characterized in that n = 2 - 10 and m = 2 - 10.

5. Use according to any one of Claims 1 - 4, characterized in that the aliphatic epoxide ester or epoxide ether of formula I contains from 1 to 6, preferably from 2 to 4 epoxy groups.

6. Use according to any one of Claims 1 - 5, characterized in that the aliphatic epoxide ester or epoxide ether of formula I is ethyleneglycol di(2,3- epoxypropanoate), 2-butyl-2-ethylpropyl- 1 ,3-di(9, 10-epoxyoctadecanoate), 2,2- dimethylpropyl-l,3-di(9,10-epoxydecanoate), 2-methylpentyl-9,10-epoxydeca- noate, or 2-methyl-(oxiranyl)methyl-9,10-epoxydecanoate and the cycloaliphatic epoxide esterof formula II is diethyleneglycol di(5,6-epoxy-2-norbornane carboxylate), or neopentylglycol di(5,6-epoxy-2-norbornane carboxylate).

7. Use according to any one of Claims 1 - 6 in combination with known coalescent agents.

8. Use according to any one of Claims 1 - 7, characterized in that the coating composition is a paint, varnish, joint mortar, filler mortar, mortar or adhesive composition, preferably an aqueous composition and particularly preferably a composition based on latex.

9. Use according to any one of Claims 1 - 8, characterized in that the aliphatic epoxide compounds are used as coalescent agents and/or reactive diluents.

10. Coating composition, characterized in that the coating composition it is an aqueous or solvent-based composition comprising from 0.01 to 20 % by weight, preferably from 0.1 to 15 % by weight of one or more an aliphatic epoxide, which is an aliphatic linear or branched epoxide ester or epoxide ether of the general formula I or a cycloaliphatic epoxide ester of the general formula II, wherein in formula I

O R R²C — CR³R⁴ (I)

R¹ and R³ independently represent either hydrogen or a linear or branched, ethylenically unsaturated or saturated Cι-Cι₆ hydrocarbon, further, one or both of R¹ and R³ may contain one or more epoxy group(s);

9 ά.

R and R independently represent either hydrogen or a linear or branched, ethylenically unsaturated or saturated Cι-C₂o hydrocarbon, or -(CH )_n-COOR⁵ or -(CH₂)_m-OR⁶ groups, wherein the groups R⁵ and R⁶ independently represent a linear or branched, ethylenically unsaturated or saturated C₄-Cι₆ hydrocarbon optionally having one or more ester group(s) or epoxy group(s), and n = 0 - 14 and m = 2 - 14; and

wherein in formula II

R⁷ represents -O-, -CH₂-, or -CH₂CH₂-;

R⁸ represents hydrogen, or a linear or branched, ethylenically unsaturated or saturated C₂-C o hydrocarbon that may have one or more ether group(s);

R⁹ represents either hydrogen or a methyl group; and

k = 0 or l.

11. Coating composition according to Claim 10, characterized in that groups R¹ and R³ are each H or a Cι-C₈ hydrocarbon, preferably H or a Cι-C₆ hydrocarbon groups, and group R⁸ is a C -Cιo hydrocarbon, R⁸ preferably representing a C₂-C₆ hydrocarbon.

12. Coating composition according to Claim 10 or 11, characterized in that groups R⁵ and R⁶ are C -Cι₀ hydrocarbons and groups R² and R⁴ are H or C₄-Cι₈ hydrocarbons and preferably groups R⁵ and R⁶ are C₄-C₈ hydrocarbons and R² and R⁴ are H or C₄-C 10-

13. Coating composition according to any one of Claims 10 - 12, characterized in that n= 2 - 10 and m = 2 - 10.

14. Coating composition according to any one of Claims 10 - 13, characterized in that the aliphatic epoxide ester or epoxide ether of formula I contains from 1 to 6, preferably from 2 to 4 epoxy groups.

15. Coating composition according to any one of Claims 10 - 14, characterized in that the aliphatic epoxide ester of formula I is ethyleneglycol di(2,3- epoxypropanoate), 2-butyl-2-ethylpropyl-l,3-di(9,10-epoxyoctadecanoate), 2,2- dimethylpropyl-l,3-di(9,10-epoxydecanoate), 2-methylpentyl-9,10-epoxydeca- noate or 2-methyl-(oxiranyl)methyl-9,10-epoxy decanoate, and the cycloaliphatic epoxide ester of formula II is diethyleneglycol di(5,6-epoxy-2-norbornane carboxylate) or neopentylglycol di(5,6-epoxy-2-norbornane carboxylate).

16. Coating composition according to any one of Claims 10 - 15, characterized in that the coating compositions additionally contains known coalescent agents.

17. Coating composition according to any one of Claims 10 - 16, characterized in that the pH value of the coating composition is less than about 8.5, preferably less than 8.0.

18. Coating composition according to any one of Claims 10 - 17, characterized in that the coating composition is paint, varnish, joint mortal-, filler mortar, mortar or adhesive composition, preferably an aqueous composition and particularly preferably a composition based on latex.

19. Ethyleneglycol di(2,3-epoxypropanoate)

20. 2-Butyl~2-ethylpropyl- 1 ,3-di(9, 10-epoxyoctadecanoate)

21. 2,2-Dimethylpropyl- 1 ,3-di(9, 10-epoxydecanoate)

22. 2-Methylpentyl-9, 10-epoxydeca-noate

23. Diethyleneglycol di(5,6-epoxy-2-norbornane carboxylate)

24. Method for producing a compound according to any of claims 19 - 22, characterized in that in the first step of the method, an esterification is carried out by reacting a saturated or ethylenically unsaturated carboxylic acid having a straight or branched chain with a saturated or ethylenically unsaturated mono- or polyhy- dric alcohol having a straight or branched chain, followed in the second step by an oxidation of the double bonds present in the ester to give epoxy groups by reacting the ethylenically unsaturated ester with m-chloroperbenzoic acid, hydrogen peroxide or peracetic acid.

25. Method for producinga compound of claim 23, characterized in that in the first step, a diene is reacted with a (meth)acrylate ester, in the second step, the product is transesterified in a single phase, or the ester group is hydrolyzed to give a carboxylic acid group, and then an acid chloride is prepared from said acid, in the third step, the acid chloride is reacted with an alcohol, and in the final step, the double bonds present in the ester are oxidized to give epoxy groups, or cycloaliphatic diesters are produced by reacting a diene in the first step with a di(meth)acrylate ester, followed by oxidation of the double bonds in the second step to give epoxy groups.