Patent Description:
Water-based and energy-curable polymers were merged over the years with the development of novel energy-curable polyurethane dispersions (often called UV-PUDs). These products re-combine in one single basket the substantial benefits of their parent technologies and boost coating sustainability to the next level of requirements. They respond to the environmental regulations due to their waterborne nature and their low level of volatile organic compounds. Their minimum film formation temperature (MFFT) is low and does not require the use of additional coalescing solvents that contribute to an increased air emission.

Most of the UV-PUDs on the market are still based on raw materials that are coming from fossil resources. To obtain more environmental-friendly compounds, petrochemical resources are replaced by natural raw materials. Biobased compounds, or compounds based on raw materials from renewable sources, are materials that are composed of biomass and that can be continually replenished by short- to medium-term regeneration. Biomass is a material of biological origin excluding material embedded in geological formations and/or fossilized; very often it is related to plants.

Besides their strong contribution to circularity, the use of bio-polymers is providing a significant material carbon footprint reduction that can be expressed in g CO<NUM> per kg of polymer. There is a big concern about the massive increase of greenhouse gas in the atmosphere (particularly carbon dioxide from human transformation of fossil resources - that takes about one million years to be re-stored in earth). The usage of renewable carbon addresses the cycle imbalance with a neutral carbon footprint proposition, considering that the CO<NUM> released in the atmosphere is coming from the same quantity of CO<NUM> fixation by plants during their photo-synthesis.

Some UV PUDs having biobased raw materials are already present on the market. However, it is desirable to obtain UV PUDs with a very high biogenic carbon content conferring strong sustainable properties and that are able to provide good coating performances with a high durability and an increased sustainability impact. Furthermore, it is desirable to use safer raw materials by e.g. avoiding the use of tin catalyst, bisphenol A or alkoxylated alkyl phenol emulsifiers, to obtain a more sustainable UV-PUD.

Therefore, it is an object of the invention to obtain biobased UV-PUDs to solve some or all of the problems mentioned herein.

The applicant has now surprisingly found aqueous energy curable polyurethanes having high biogenic carbon content that are able to provide coatings with good performances such as nail scratch resistance and solvent resistance, while preserving a low MFFT and a low VOC.

Accordingly, a first aspect of the invention is related to an aqueous bio-based energy-curable polyurethane composition comprising:.

A second aspect of the invention is related to a process for making an aqueous bio-based energy-curable polyurethane composition comprising the steps of.

In another aspect, present invention relates to a coating, ink or overprint varnish prepared from the aqueous bio-based energy-curable polyurethane composition.

In yet another aspect, present invention relates to a method for coating or printing a surface with the aqueous bio-based energy-curable polyurethane composition, comprising the steps of:.

As used herein, the phrase "biobased compounds" or "biogenic compounds" or "compounds with carbon-content from natural or renewable resources" or "compounds having a biogenic carbon content" or " compounds having biocarbon content" can be used interchangeably and all refer to compounds sourced from or made from natural renewable resources, such as, for example, bio-mass or plant-based sources.

The use of biobased compounds can be detected by virtue of the presence of 14C carbon atoms. Carbon can be available as a mixture of <NUM> isotopes (12C, 13C and 14C). Fossil raw materials contain a neglectable percentage of 14C isotope due to relatively short radioactive decay (half-time being <NUM>,<NUM> years) as opposed to renewable raw materials that incorporate carbon from carbon dioxide in the atmosphere via the photosynthesis. This new carbon is delivering a higher and defined percentage of 14C isotope at a given moment in time as a consequence of cosmic rays in the upper atmosphere. The amount of 14C relative to 12C in view of the total amount of carbon indicates the percentage of biogenic carbon in the sample, from zero to <NUM>%.

Currently, there exists at least two different techniques for measuring the 14C content of a sample (i) by liquid scintillation counting or (ii) by mass spectrometry in which the sample is transformed in CO<NUM> and then reduced to graphite for analysis in the mass spectrometer to separate the 14C atoms from the 12C atoms and determine their ratio. All these methods for measuring the 14C content of substances are clearly described in the American standards ASTM D <NUM> or ASTM D <NUM> as well as in the European standards EN <NUM> or EN <NUM>.

The values of the biobased carbon content according to his invention are measured using the accelerated mass spectrometry protocol described in the standard ASTM D <NUM>.

According to this invention, when is mentioned that a compound has e.g. at least 20wt% biocarbon, this means that <NUM> wt% carbon is from biobased origin in view of the total carbon content.

In the frame of this invention, the aqueous bio-based energy-curable polyurethane composition can also be biodegradable and/or compostable and/or biocompatible. Biodegradability is the ability of the material, either as such or after energy curing, to be decomposed in smaller molecules (like water, carbon dioxide, methane and biomass) as a result of the interaction with natural microorganisms (like bacteria, algae or fungi) present in the biotope.

Compostability is the ability of the material, either as such or after energy curing, to be used in compost, i.e. to be assimilated in the aerobic biological process converting organic waste in a stabilized decayed material used for fertilizing and conditioning land.

Biocompatibility is the ability of the material, either as such or after energy curing, to be compatible with living tissue. Biocompatible materials do not produce a toxic or immunological response when exposed to human or animal body or bodily fluids and can be used as (or part of) implants, protheses or any other functional substitute in a living body.

Products can be tested for biodegradability and compostability. For instance, those products featuring the "OK compost industrial" label from TUV AUSTRIA are guaranteed as biodegradable in an industrial composting plant according to the harmonized EN <NUM>: <NUM> standard. Similarly, the "OK biodegradable" label can be attributed to soil, water and marine environments based on specific test protocols. As used herein, "ethylenically unsaturated compound" refers to a compound comprising a polymerizable ethylenically unsaturated group. By polymerizable ethylenically unsaturated group is meant a carbon-carbon double bond which under influence of an initiator and/or irradiation, eventually in the presence of a photoinitiator, can undergo radical polymerization. The polymerizable ethylenically unsaturated groups are generally chosen from (meth)acrylic groups, preferably (meth)acrylic groups, most preferably acrylic groups. In the present invention, the term "(meth)acrylic" is to be understood as to encompass both acrylic and methacrylic groups present on compounds either separately or as mixtures thereof. By "containing essentially of" is meant to designate in particular that the sum of the weight percentages of these compounds accounts for at least <NUM>% by weight, preferably at least <NUM>% by weight, more preferably at least <NUM>% by weight up to <NUM>% by weight.

As used herein an "alcohol" means both a monool and a polyol. A "monool or mono-alcohol" refers to a compound comprising one hydroxyl group (OH); a "polyol" refers to a compound comprising at least two hydroxyl (OH) groups.

The aqueous bio-based energy curably composition comprising a polyurethane pre-polymer (A) and optionally an ethylenically unsaturated compound (B), can be an aqueous dispersion, i.e. solid particles in water, or an aqueous emulsion, i.e. liquid droplets in water. It can also coexist as a mixture between a dispersion and an emulsion.

The aqueous bio-based energy curably compositions contain at least <NUM> meq of polymerizable ethylenically unsaturated groups per total weight in g of the composition. Preferably the number of polymerizable ethylenically unsaturated groups is at least <NUM> meq, more preferably at least <NUM> meq, even more preferably at least <NUM> meq, most preferably at least <NUM> meq/g of polymerizable ethylenically unsaturated groups per total weight in g of the composition.

The amount of ethylenically unsaturated groups per total weight is calculated from the known composition of the polymer (bill of material). It usually refers to the amount of (meth)acrylic acid or glycidyl(meth)acrylate present in the overall polymer composition. It can also be measured by titration. It is expressed in meq of unsaturations per g of polymer composition.

The aqueous bio-based energy curably composition of the invention generally have a total solids content of from about <NUM> to <NUM> wt%, preferably from about <NUM> to <NUM> wt%, most preferably from about <NUM> to <NUM> wt%.

The aqueous bio-based energy curably composition has typically a viscosity measured at <NUM> of <NUM> to <NUM>,<NUM> mPa s, preferably <NUM> to <NUM> mPa s, most preferably <NUM> to <NUM> mPa. s; a pH value of <NUM> to <NUM>, preferably of <NUM> to <NUM>, an average particle size of about <NUM> to <NUM>, preferably <NUM> to <NUM>, most preferably <NUM> to <NUM>.

In one embodiment the aqueous bio-based energy-curable polyurethane composition has a biocarbon content of more than <NUM>%, preferably above <NUM>%, more preferably above <NUM>%, even more preferably above <NUM>%, most preferably above <NUM>%, the most preferably above <NUM>% by weight of the total carbon content of the polyurethane composition. At least compounds (Aiii) and (Aiv) have a biocarbon content of at least <NUM>% by weight. It is preferred that also the other compounds used for making the polyurethane pre -polymer (A) have a biocarbon content of at least <NUM>% by weight. Also the optional ethylenically unsaturated compound (B) has a biocarbon content of more than <NUM>% by weight.

The aqueous bio-based energy curable composition according to this invention has a material carbon footprint reduction of at least <NUM> CO<NUM>/g, preferably at least <NUM> CO<NUM>/kg, more preferably at least <NUM> CO<NUM>/Kg, most preferably at least <NUM> CO<NUM>/Kg the most preferably at least <NUM> CO<NUM>/Kg.

The aqueous bio-based energy curable composition according to this invention has a low MFFT, preferably a MFFT of between <NUM> and <NUM>, more preferably between <NUM> and <NUM>, most preferably between <NUM> and <NUM>.

The weight average molecular weight (Mw) of the polyurethane pre-polymer (A) of the invention preferably is below <NUM>,<NUM> Daltons, typically below <NUM>,<NUM> Daltons, more typically below <NUM>,<NUM> Daltons. In general the weight average molecular weight (Mw) is at least <NUM> Daltons, usually at least <NUM>,<NUM> Daltons, typically at least <NUM>,<NUM> Daltons. Molecular weights typically are determined by gel permeation chromatography (GPC) using polystyrene standards covering the measurement range. Samples are typically dissolved in tetrahydrofuran prior to filtration and injection into the chromatographic column.

The following paragraphs describe embodiments of the different compounds that can be used for making the pre-polymer A.

By polyisocyanate compounds (Ai) is meant to designate organic compounds comprising at least two isocyanate groups. Preferably, the polyisocyanate compound comprises not more than three isocyanate groups. The polyisocyanate compound (Ai) is most preferably a di-isocyanate.

The polyisocyanate compound is generally selected from aliphatic, cycloaliphatic, aromatic and/or heterocyclic polyisocyanates or combinations thereof.

Examples of aliphatic and cycloaliphatic polyisocyanates are <NUM>,<NUM>-diisocyanatohexane (HDI), <NUM>,<NUM>'-methylene bis[<NUM>-isocyanatocyclohexane] (H12MDI), <NUM>-isocyanato-<NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexane (isophorone diisocyanate, IPDI) and <NUM>,<NUM>-diisocyanatomethyl cyclohexane (H6XDI). Aliphatic polyisocyanates containing more than two isocyanate groups are for example the cyclic derivatives of above mentioned diisocyanates like <NUM>,<NUM>-diisocyanatohexane biuret and isocyanurate.

Examples of aromatic polyisocyanates are <NUM>,<NUM>-toluene diisocyanate (TDI), <NUM>,<NUM>'-methylenebis[<NUM>-isocyanatobenzene] (MDI), m-xylilene diisocyanate (XDI), tetramethylxylilene diisocyanate (TMXDI), <NUM>,<NUM>-naphtalene diisocyanate (NDI), <NUM>,<NUM>'-dibenzyl diisocyanate (DBDI), tolidine diisocyanate (TODI) and <NUM>,<NUM>-phenylene diisocyanate (PPDI).

The polyisocyanate is preferably selected from aliphatic and cycloaliphatic polyisocyanates. An example hereof is <NUM>,<NUM>'-methylene bis[<NUM>-isocyanatocyclohexane] (H12MDI).

Most preferably, the polyisocyanate (Ai) is biobased having a biocarbon content of more than <NUM>% by weight. A preferred biobased polyisocyanate (Ai) that is used is pentane diisocyanate or a derivative from pentane diisocyanate. The derivative from pentane diisocyanate can be a trimerization or oligomerization product of pentane diisocyanate like an isocyanurate, a biuret, an allophanate or an oligomer, all straight or partially blocked.

Examples of such polyisocynate (Ai) based on biobased pentane diisocyanates and already on the market are Desmodur® ECO N <NUM>, Stabio® D-370N or Stabio® D-376N. Another example of polyisocyanate (Ai) is Tolonate™ X FLO <NUM>.

Preferably, the polyisocyanate (Ai) is provided from the partial reaction of an alcohol compound (Aia) having on average one hydroxyl function per molecule with a polyisocyanate (Aib). The alcohol compound (Aia) comprises preferably a biobased content of more than 20wt%. A preferred polyisocyanate (Aib) that is used is based on biobased pentane diisocyanate. The most preferred polyisocyanate (Aib) is Desmodur® ECO N <NUM>, Stabio® D-370N or Stabio® D-376N.

The alcohol compound (Aia) is most preferably used to decrease the functionality of the polyisocyanate to a level of two isocyanate functionalities per molecule prior to the reaction with (Aii), (Aiii), (Aiv) and if present (Av) and (Avi). The alcohol compound (Aia) has on average one hydroxyl function per molecule and can be a primary, secondary or tertiary alcohol. The structure of (Aia) is R-OH, wherein the group R can be aliphatic, cycloaliphatic or aromatic.

Preferably, the alcohol compound (Aia) is biobased having a renewable carbon content of more than 20wt %. Preferred examples of such biobased alcohol compounds (Aia) are bio-based methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, decanol, undecanol, dodecanol or octadecanol.

The amount of polyisocyanate compound (Ai) used for the synthesis of the polyurethane prepolymer (A) is generally in the range of from <NUM> to 60wt% of the polyurethane prepolymer (A), preferably from <NUM> to 50wt% and more preferably from <NUM> to 40wt%.

The hydrophilic compound (Aii) contains at least one reactive group capable to react with an isocyanate and which is capable to render the polyurethane pre-polymer A dispersible in an aqueous medium either directly or after the reaction with an organic or inorganic neutralizing agent to provide a salt therefrom.

The hydrophilic compound (Aii) is generally a mono-alcohol or a polyol comprising a functional group that can exhibit an ionic or non-ionic hydrophilic nature. Preferably it is a polyol containing one or more anionic salt groups, such as carboxylate, sulfonate and phosphonate salt groups or acid groups which may be converted to an anionic salt group, such as carboxylic acid, sulfonic acid or phosphonic acid groups. Preferred are hydroxycarboxylic acids represented by the general formula (HO)xR(COOH)y, wherein R represents a straight or branched hydrocarbon residue having <NUM> to <NUM> carbon atoms, preferably <NUM> to <NUM> carbon atoms, and x and y independently are integers from <NUM> to <NUM>. Examples of these hydroxycarboxylic acids include biobased citric acid, malic acid, glycolic acid, lactic acid and tartaric acid. Another example is biobased <NUM>,<NUM> dihydroxyhexadecanoic acid. The preferred hydroxycarboxylic acids are the α,α-dimethylolalkanoic acids, wherein x=<NUM> and y=<NUM> in the above general formula, such as for example, <NUM>,<NUM>-dimethylolpropionic acid and <NUM>,<NUM>-dimethylolbutanoic acid. The most preferred is <NUM>,<NUM>-dimethylolpropionic acid. The hydrophilic compound (Aii) can be a nonionic component selected from hydroxylated polyethyleneoxide polymers or hydroxylated polyethyleneoxide-co-polypropyleneoxide bloc copolymers, which are preferably biobased. An example of such hydroxylated polyethyleneoxide polymers is YMER® N120.

Preferably, the hydrophilic compound (Aii) has a biocarbon content of more than <NUM>% by weight in view of the total carbon content of compound (Aii).

The amount of hydrophilic compound (Aii) used for the synthesis of the polyurethane pre-polymer (A) is generally in the range from <NUM> to 30wt% in view of the total weight of the polyurethane pre-polymer (A), preferably of from <NUM> to <NUM>% by weight, most preferably from <NUM> to <NUM>% by weight.

By ethylenically unsaturated compound (Aiii) containing essentially one reactive group capable to react with an isocyanate is meant to designate in the present invention compounds comprising at least one unsaturated function, such as acrylic or methacrylic group, and one nucleophilic function capable of reacting with an isocyanate, preferably a hydroxyl group. Preferred are (meth)acryloyl mono-hydroxy compounds, more particularly poly(meth)acryloyl mono-hydroxy compounds. Acrylates are particularly preferred. Allylic groups are an option.

By ethylenically unsaturated compound (Aiv) containing at least two reactive group capable to react with isocyanate groups is meant to designate in the present invention compounds comprising at least one unsaturated function such as acrylic or methacrylic group and at least two nucleophilic functions capable of reacting with an isocyanate, preferably hydroxyl groups. Preferred are (meth)acryloyl poly-hydroxy compounds, more particularly poly(meth)acryloyl poly-hydroxy compounds. Acrylates are particularly preferred. Allylic groups are an option.

According to this invention the ethylenically unsaturated compound (Aiii) and (Aiv) are biobased and each comprise at least 20wt% of biocarbon content, preferably at least 25wt%, more preferably at least 40wt%, most preferably at least 60w% and the most preferably at least 80w%.

The ethylenically unsaturated compound (Aiii) and (Aiv) and/or (B) is obtainable by reacting a compound comprising at least one ethylenically unsaturated function with a reactive biobased compound to form the ethylenically unsaturated compound (Aiii) having essentially one nucleophilic function capable of reacting with an isocyanate, to form the ethylenically unsaturated compound (Aiv) having at least two nucleophilic functions capable of reacting with an isocyanate or to form the ethylenically unsaturated compound (B) having no having nucleophilic functions capable of reacting with an isocyanate. Also the compound comprising at least one unsaturated function can be biobased. Preferably the reactive biobased compound is a hydroxyl or an epoxy compound.

The compound comprising at least one ethylenically unsaturated function can be a carboxylic acid or an ester thereof or an ethylenically unsaturated epoxide.

The reaction is typically a direct esterification reaction. When an ester of the ethylenically unsaturated carboxylic acid compound is used, then the reaction is a transesterification reaction.

Preferably, the ethylenically unsaturated carboxylic acid compound is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, aconitic acid, or a mixture thereof.

Preferably, the ethylenically unsaturated epoxide is a glycidyl(meth)acrylate.

The reactive biobased compounds are preferably selected from the group consisting of organic oils or organic oil derivatives, carboxylic acid compounds, fatty acids and derivatives, fatty acid dimers and derivatives, and biobased polyols and derivatives thereof.

Biobased polyols can be aliphatic, cycloaliphatic or aromatic polyols. They include fatty alcohols, fatty alcohol dimers, carbohydrates, sugar alcohols and derivatives thereof. Examples of other types of biobased polyols are rosin polyols, (poly)farnesene polyols, (poly)alkylene glycols and (poly)alkylene polyols. Other biobased polyols can also be trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol. Examples of (poly)alkylene glycols are diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol.

Biobased polyol derivatives are preferably glycolide, lactide, lactone, poly(alkyleneoxide), such as poly(ethyleneoxide) or poly(propyleneoxide) derivatives of the polyols. An example therefrom is sorbitol poly(propyleneoxide).

The organic oil or the organic oil derivative is preferably a biobased epoxidized oil, that is preferably selected from the group consisting of epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized coconut oil, epoxidized corn oil, epoxidized cottonseed oil, epoxidized olive oil, epoxidized palm oil, epoxidized peanut oil, epoxidized sunflower oil, epoxidized safflower oil, epoxidized tall oil, epoxidized cashew shell oil, or a biobased epoxidized fatty acid thereof. Typically the biobased epoxidized oil is reacted with an ethylenically unsaturated molecule bearing at least one carboxylic acid, like (meth)acrylic acid.

Preferably, the organic oil derivative is a cardanol derivatives. Known examples are epoxidized cardanol derivatives like for example Cardolite® Ultralite <NUM> or Cardolite® NC 514SG. An example of other biobased polyol derivative is are epoxidized rosins like for example Altamer® RTE. Other substitutes for these organic oil derivatives are for instance glycidyl esters of versatic acid, like Cardura® E10P, or biobased epoxyfunctional polyethers based on glycerol, like Araldite® DY-S.

The biobased fatty acid or fatty acid dimer are preferably biobased aliphatic, cycloaliphatic or aromatic carboxylic acid compounds. Examples are monocarboxylic fatty acids such as butanoic acid, hexanoic acid, octanoic acid, decanoic acid and poly-carboxylic fatty acids such as butanedioic acid, pentanedioic acid, hexanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, dodecanedioic acid.

Suitable biobased carboxylic acid compounds preferably contain more than one carboxylic acid. Examples thereof are maleic acid, fumaric acid, glutaconic acid, phtalic acid, isophtalic acid, terephtalic acid, citric acid or trimesic acid.

The biobased fatty acid or fatty acid dimer can be a saturated fatty acid such as butyric acid, lauric acid, palmitic acid, stearic acid; mono-unsaturated fatty acid like oleic acid; or polyunsaturated fatty acid like linoleic acid.

The biobased fatty acid dimer is obtained from the above fatty acids, in particular from the mono-unsaturated fatty acids such as oleic acid.

A particular type of biobased fatty acid derivative or fatty acid dimer derivative is a fatty alcohol or a fatty alcohol dimer that can be obtained directly from the chemical transformation of the parent fatty acid or fatty acid dimer. They can also be formed by the reaction of a fatty acid or a fatty acid dimer with a polyol such as a biobased polyol. Preferred polyols are trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol.

Preferably, the biobased ethylenically unsaturated compound (Aiii) (Aiv) and (B) based on fatty acid or fatty acid derivatives are made by reacting a fatty acid or fatty acid dimer with a polyol in the presence of acrylic acid and methacrylic acid. A person skilled in the art knows which stoichiometry to use to provide the required hydroxyl functionality of the compounds (Aiii) or (Aiv).

The biobased fatty acid or fatty acid dimer can also react with an ethylenically unsaturated molecule bearing at least one epoxy group. An example of this molecule is glycidyl methacrylate. For instance, lauric acid can react stoichiometrically with glycidyl methacrylate or with Cardolite <NUM> to provide an unsaturated compound (Aiii). Alternatively, the C36 dimer of stearic acid can react stoichiometrically with glycidyl methacrylate or with Cardolite <NUM> to provide an unsaturated compound (Aiv).

Itaconic acid can react stoichiometrically with glycidyl methacrylate or with Cardolite <NUM> to provide an unsaturated compound (Aiv).

Citric acid can partially or totally react with glycidyl methacrylate or with Cardolite <NUM> to provide an unsaturated compound (Aiv); if there is one or several remaining carboxylic acids on the molecule, it is also an example of compound (Aii).

Alternatively <NUM>,<NUM> dihydroxyhexadecanoic acid can partially or totally react with glycidyl methacrylate or with Cardolite <NUM> to provide an unsaturated compound (Aiv); if there is one or several remaining carboxylic acids on the molecule, it is also an example of compound (Aii).

Biobased sugar alcohol or derivatives can be ethylene glycol, glycerol, diglycerol, triglycerol, erythritol, arabitol, sorbitol and their glycolide derivatives, lactide derivatives, lactone derivatives, poly(alkyleneoxide) derivatives. Other examples of biobased sugar alcohol derivatives are isosorbide, isomannide, isoidide.

Carbohydrates (or saccharides) can be polyhydroxy biobased compounds that include sugars, starch and cellulose. The saccharides can be divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides with the lower molecular weight are referred to sugars and are preferred in the frame of this invention. Examples of monosaccharides include glucose, galactose, fructose and xylose. Examples of disaccharides include sucrose, lactose, maltose, isomaltulose and trehalose. Examples of oligosaccharides include maltodextrin, raffinose and stachyose. Examples of polysaccharides include glycogen, cellulose, hemicellulose, pectins, amylose, amylopectin and starches as well as their derivates including the bio-transformation of these products in bio-reactors in the presence of enzymes.

The ethylenically unsaturated compound (Aiii) has as amount of reactive groups capable to react with an isocyanate, also called nucleophilic function, or functionality of essentially <NUM>. The nucleophilic function is preferably a hydroxyl group.

Examples of such compounds are hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate, hydroxyethyl(meth)acrylamide, isosorbide mono(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, trimethylolpropane di(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, glycerol (poly)propoxylate di(meth)acrylate, diglycerol (poly)propoxylate tri(meth)acrylate, sorbitol (poly)propoxylate penta(meth)acrylate. Another example is hydroxyethyl acrylate (poly) lactide.

The ethylenically unsaturated compound (Aiv), has as amount of reactive groups capable to react with an isocyanate, also called nucleophilic function, or functionality of at least <NUM>, preferably from <NUM> to <NUM> per compound, most preferably <NUM> per compound. The nucleophilic function is preferably a hydroxyl group.

Examples of such compounds are pentaerythritol di(meth)acrylate, dipentaerythritol tetra(meth)acrylate, trimethylolpropane (meth)acrylate, ditrimethylolpropane di(meth)acrylate, glycerol propoxylate (meth)acrylate, diglycerol propoxylate di(meth)acrylate, sorbitol propoxylate tetra(meth)acrylate.

It is possible that compounds (Aiii), A(iv) and (B) are obtained from lignin as biobased raw material precursor, after chemical transformation and functionalization required in the frame of this invention.

The desired functionality of (Aiii) and (Aiv) are obtained by controlling the process and the right stoichiometric ratios of the compound comprising at least one ethylenically unsaturated function and the reactive biobased compounds.

In one embodiment the amount of reactive groups isocyanate reactive groups of the ethylenically unsaturated compound (Aiv) can be controlled by reacting a portion of the isocyanate reactive group with a blocking compound capable to react with a isocyanate reactive groups and optionally to generate another functionality to the molecule. Such blocking compound is preferably a cyclic anhydride which generates a carboxylic acid group. Succinic and maleic anhydrides are particularly preferred.

This way it is possible to control the nucleophilic functionality of compounds (Aiii) or (Aiv) and it also possible to obtain a polyurethane polymer A with the desired molecular weight and amount branching without risk of gel formation.

In a particular embodiment, the biobased ethylenically unsaturated compound (Aiii) or (Aiv) and (B) is obtainable by.

In this embodiment the anhydride is preferably a cyclic anhydrides and is preferably a succinic anhydride of a maleic anhydride.

In one embodiment the ethylenically unsaturated compound (Aiii) has a hydroxyl number of between <NUM> and <NUM> mgKOH/g - such as between <NUM>- <NUM> KOH/g.

In one embodiment the ethylenically unsaturated compound (Aiv) has a hydroxyl number of between <NUM> and <NUM> mgKOH/g - such as between <NUM>- <NUM> KOH/g.

Preferably, compound (Aiii) and /or (Aiv) bears from <NUM> to <NUM> ethylenically unsaturated groups per molecule.

In one embodiment, the aqueous biobased energy curable polyurethane composition comprises at least one ethylenically unsaturated compound (B) different from (Aiii) and (Aiv) having no reactive group capable to react with an isocyanate the fully ethylenically unsaturated compounds (B) different from (Aiii) and (Aiv). This product is usually added to the ethylenically unsaturated polyurethane pre-polymer (A) to provide additional desired properties.

It is also possible that during the esterification reaction leading to compounds (Aiii) and (Aiv), the reaction mixture at equilibrium contains a portion in which all the reactive groups capable to react with an isocyanate, are reacted with the ethylenically unsaturated acid and are no more capable to react with an isocyanate group. These reaction products are also constituting the at least one ethylenically unsaturated compounds (B) different from (Aiii) and (Aiv) having no reactive group capable to react with an isocyanate.

In another embodiment, compound (B) can also be a biobased urethane acrylate different from prepolymer (A). A suitable biobased urethane acrylate can for instance be obtained by the full stoichiometric reaction between Desmodur® ECO N <NUM> and Cardolite® NX7202 or between Desmodur® ECO N <NUM>, Cardolite® NX7202 and <NUM>-ethyl-<NUM>,<NUM>-hexanediol.

The compound (B) can alternatively be added to the aqueous bio-based energy curable polyurethane composition, as such or as a separately-prepared emulsion.

The amount of compound (Aiii) generally is from <NUM> to <NUM> % by weight of the polyurethane prepolymer (A), preferably of from <NUM> to <NUM> % by weight.

The amount of compound (Aiv) generally is from <NUM> to <NUM> % by weight of the polyurethane prepolymer (A), preferably of from <NUM> to <NUM>% by weight.

The amount of compound (B) generally is from <NUM> to <NUM>% by weight of the polyurethane composition, preferably <NUM> to <NUM>%.

The ethylenically unsaturated compound (Aiv) is prepared with from <NUM>-40wt% of bisphenol A, preferably from <NUM>-<NUM> wt% bisphenol A, most preferably without using bisphenol A. Bisphenol A is a common compound used as starting material for UV curable (meth)acrylate compositions, typically as bisphenol A diglycidyl ether diacrylate. Due to the health and the environmental pressure in relation with the toxicology and ecotoxicity of bisphenol A, its usage is avoided. Instead safer substitutes, like acrylates bases on butanediol diglycidyl ether, vanilin diglycidyl ether, isosorbide diglycidyl ether, hexanediol diglycidylether, cyclohexanedimethanol diglycidylether or heterocyclic epoxy compounds such as triglycidyl isocyanurate or other similar alternatives can be used.

From a polymer architecture standpoint, the compounds (Aiii) introduce terminal ethylenically unsaturation on the pre-polymer (A) and function as the capping molecules of the pre-polymer (A). The compounds (Aiv) having at least <NUM> hydroxyl groups provide chain extension and / or chain branching with lateral ethylenically unsaturations. Only the combination of both type of biobased compounds guarantees a higher level of ethylenically unsaturations resulting in a performant coating and complemented with the highest level of bio-carbon in the polymer providing the highest carbon footprint reduction as a result.

In some embodiments, the aqueous bio-based curable polyurethane composition comprising the polyurethane pre-polymer (A), may further be obtained from the reaction of compounds (Ai), (Aii), (Aiii), (Aiv) and (Av).

The mono-alcohol or polyol (Av) is different from (Ai), (Aii), (Aiii) or (Aiv) and has a biocarbon content of more than <NUM>% by weight, preferably more than <NUM> % by weight, even more preferably more than <NUM>% by weight, most preferably more than <NUM>% by weight, the most preferably more than <NUM>% by weight and contains at least one reactive group capable to react with an isocyanate. Preferably, a polyol is used comprising at least two hydroxyl groups.

The mono-alcohol (Av) can be methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tertio-butanol, pentanol, hexanol, heptanol, octanol, decanol, dodecanol, terpineol.

Preferably, compound (Av) is a polyol selected from the group consisting of an aliphatic, cycloaliphatic or aromatic diol or polyol, a biobased sugar, a biobased sugar alcohol, a fatty alcohol or a fatty alcohol dimer, a polycarbonate polyol, a polyester polyol, a polyether polyol, a polyacrylate polyol or mixtures thereof.

Preferably, the biobased sugar alcohol or derivate is an ethylene glycol, glycerol, diglycerol, erythritol, arabitol, sorbitol, isosorbide, isomannide, isoidide.

Compound (Av) can be derived from vegetable oils or starch.

Compound (Av) can also be a monoalcohol or a polyol that is (poly)ethoxylated or (poly)propoxylated, or a (poly)lactone or a (poly)lactide derivative.

Compound (Av) can be an aliphatic or cycloaliphatic diol or polyol like <NUM>,<NUM>-ethylene glycol, <NUM>,<NUM>-propane diol, <NUM>,<NUM>-butane diol, <NUM>,<NUM>-pentane diol, <NUM>,<NUM>-hexane diol, heptane diol, octane diol, nonane diol, decane diol, dodecane diol, cyclohexane dimethanol. It can be also diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, tetrapropyleneglycol, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythrytol.

Compound (Av) can be a polyester polyol having preferably a number average molecular weight of at least <NUM> Daltons and preferably not exceeding <NUM> Daltons, most preferably not exceeding <NUM> Daltons. The polyester polyol may also contain residual vinylic unsaturations suitable for oxidative air-drying.

The polyester polyol can be reaction of a polyol, such as the polyols describe above, with a polycarboxylic acid, preferably dicarboxylic acids. The polycarboxylic acids which may be used for the formation of these polyester polyols may be aliphatic, cycloaliphatic, aromatic and/or heterocyclic. Particular preferred dicarboxylic acids are succinic acid, adipic acid, tartaric acid, lactic acid, glycolic acid, fumaric acid, maleic acid, itaconic acid, citric acid, citraconic acid, mesaconic acid, glutaric acid, trimellitic acid, trimesic acid, pyromellitic acid, phthalic acid, terephthalic acid and importantly fatty acid dimers. Other polycarboxylic acids can be used, among them cyclic esters (like gama-butyrolactone or epsilon-caprolactone), cyclic diesters (like glycolide or lactide) or cyclic anhydride (like phthalic anhydride or maleic anhydride). In a particular case of the usage of a polyester polyol, polyhydroxyalkanoates (PHA) can be used. PHA's are polyesters produced by numerous microorganisms, including bacteria, and implying a large range of different monomers. Carbohydrates and vegetable oils are generally used as raw materials for the fermentation leading to PHA's. These polyesters can present some crystallinity and are biodegradable and compostable. They have usually a good water resistance and are thermal- and UV-stable. Hydroxylated derivates suitable in the frame of this invention can for instance be obtained by further transesterification of the polyesters.

In another particular case of the usage of a polyester polyol, linear or branched polylactic acids and derivates therefrom presenting residual hydroxyl groups can be used. Polylactic acids are bio-polymers that find increasing usage in the industry.

In still another case of the usage of a polyester polyol, linear or branched polymers made from <NUM>,<NUM> dihydroxyhexadecanoic acid and typically derived from cutin are also considered.

Hydroxylated derivatives of PHA and polylactic acid can also be acrylated as compound (Aiii) and/or (Aiv) in the frame of this invention.

Compound (Av) can be a polycarbonate polyol having preferably a number average molecular weight of at least <NUM> Daltons and not exceeding <NUM> Daltons, most preferably not exceeding <NUM> Daltons. Examples of polycarbonate polyols are therefore reaction products of a polyol with phosgene, dialkylcarbonates such as dimethycarbonate, with diarylcarbonates such as diphenylcarbonate or with cyclic carbonates such as ethylene and/or propylene carbonate.

Compound (Av) can be a polyether polyol having preferably a number average molecular weight of at least <NUM> Daltons and not exceeding <NUM> Daltons, most preferably not exceeding <NUM> Daltons. Examples of polyether polyol are polyethylene glycol, polypropylene glycol, polytetramethylene glycol as well as random or bloc copolymers therefrom.

Compound (Av) can also be a polyacrylate polyol having preferably a number average molecular weight of at least <NUM> Daltons and not exceeding <NUM> Daltons, most preferably not exceeding <NUM> Daltons. It can include those polymers prepared by the (living) radical polymerization of (meth)acrylic and/or (meth)acrylamide monomers for instance initiated by a hydroxylated thermal radical initiator in the presence of an hydroxylated chain transfer agent, such as <NUM>-mercaptoethanol. Compound (Av) can also be a polyamide polyol.

It is possible that compound (Av) is obtained from lignin as biobased raw material precursor, after chemical transformation and functionalization required in the frame of this invention.

Preferred compounds (Av) are polyester polyols and polycarbonate polyols.

The mono-alcohol can be selected between methanol, ethanol, propanol, isopropanol, butanol, tert-butanol, pentanol, hexanol, cyclohexanol, heptanol, octanol, decanol, dodecanol and the like.

The total amount of polyol (Av) in the polyurethane prepolymer (A) is usually of from <NUM> to <NUM> % by weight of the polyurethane prepolymer (A), preferably of from <NUM> to <NUM> % by weight, most preferably of from <NUM> to <NUM> % by weight.

In some embodiments, the aqueous bio-based curable polyurethane composition is comprising the polyurethane pre-polymer (A) that may be obtained from the reaction of compounds (Ai), (Aii), (Aiii), (Aiv), optionally (Av), and (Avi).

Preferably the mono or polyamine compound (Avi) is an aliphatic, cycloaliphatic or aromatic amine, diamine or polyamine.

Compound (Avi) comprises active amino groups capable of making a chain capping or a chain extension from the remaining isocyanate end-groups of the pre-polymer. The chain extender is suitably a water-soluble aliphatic, alicyclic, aromatic or heterocyclic primary or secondary polyamine having up to <NUM>, preferably up to <NUM> carbon atoms. It can also be hydrazine. The total amount of compound (Avi) used is generally calculated according to the amount of residual isocyanate groups present in the polyurethane prepolymer. The ratio of isocyanate groups in the prepolymer to the amine groups in the chain extender (Avi) during the chain extension is generally in the range of from about <NUM>:<NUM> to about <NUM>:<NUM>, preferably from about <NUM>:<NUM> to about <NUM>:<NUM> on an equivalent basis. This ratio is more preferably <NUM>:<NUM> in order to obtain a fully reacted polyurethane polymer with no residual isocyanate groups.

The polyamine used for chain extension has preferably an average functionality of <NUM> to <NUM>, more preferably <NUM> to <NUM>. The preferred polyamine has an average functionality of <NUM>. Examples of such chain extenders (Avi) useful herein comprise hydrazine, piperazine, ethylene diamine, <NUM>,<NUM>-propylene diamine, <NUM>,<NUM>-propylene diamine, <NUM>,<NUM>-butanediamine, <NUM>,<NUM>-pentanediamine, <NUM>-methyl-pentanediamine, <NUM>,<NUM>-hexanediamine, <NUM>,<NUM>-heptanediamine, <NUM>,<NUM>-octanediamine, <NUM>,<NUM>-nonanediamine, <NUM>,<NUM>-decanediamine, <NUM>,<NUM>-dodecanediamine, isophorone diamine, m-xylilene diamine, bis(<NUM>-aminocyclohexyl)methane, polyoxyethylene amines and polyoxypropylene amines (e.g. Jeffamines from TEXACO), as well as mixtures thereof.

The amine used for chain capping has a functionality of <NUM>. Examples of such amines are methylamine, dimethylamine, propylamine, isopropylamine, dipropylamine, diisopropylamine, butylamine, dibutylamine, isobutylamine, diisobutylamine, tert-butylamine, di-tert-butylamine, pentylamine, dipentylamine, hexylamine, dihexylamine, benzylamine, dibenzylamine.

In another embodiment of the invention, the amine (Avi) can bear an additional functionality like is the case with natural amino acids like glycine, alanine or lysine. Another example is the N-(<NUM>-sulfopropyl) polypropyleneglycoldiamine, sodium salt (Poly-EPS from Rashig).

Preferably the mono-amine or polyamine (Avi) is biobased and comprises a biocarbon content of at least <NUM> wt%, preferably at least <NUM> wt%, more preferably at least <NUM> w%, most preferably at least <NUM>%.

An example of such biobased mono-amine or polyamines is <NUM>,<NUM>-pentanediamine. Another example is Priamine <NUM> from Croda.

Preferably no chain extender compound (Avi) is used.

Another aspect of the invention is related to a process for making an aqueous bio-based energy-curable polyurethane composition according to the invention, obtainable by a process comprising the steps of.

The formation of the unsaturated polyurethane in step (a) can be done in a solvent. The solvent is then removed after step (d) by stripping the solvent under vacuum at moderate temperature below <NUM>.

In case the ethylenically unsaturated polyurethane pre-polymer is made using polyol (Av), then (Av) is added in step (a) to react with compounds (Ai), (Aii), (Aiii) and (Aiv).

In case the ethylenically unsaturated polyurethane pre-polymer is made using polyamine (Avi), then (Avi) can be added in step (a) to react with compounds (Ai), (Aii), (Aiii) and (Aiv) and optionally (Av).

The process can further comprise the step of the reaction with a neutralizing agent (Step b). This can be done so that the hydrophilic groups provided by compound (Aii) are converted into anionic salts.

The process can be done by reacting a stoichiometric excess of the isocyanate groups present in compound (Ai) with the isocyanate reactive groups present in compounds (Aii), (Aiii), (Aiv) and if present (Av) and (Avi).

The reactants from step (a) are generally used in proportions corresponding to an equivalent ratio of isocyanate groups provided by compound (Ai) to isocyanate reactive groups provided by compounds (Aii), (Aiii), and (Aiv) and optional (Av) and/or (Avi) in the reaction mixture, whereby the equivalent ratio is between <NUM>:<NUM> to <NUM>:<NUM>, preferably from about <NUM>:<NUM> to <NUM>:<NUM>, most preferably <NUM>:<NUM>.

In case further chain capping or chain elongation occurs, the residual isocyanates can then be reacted with the optional compound (Avi).

The reaction is made preferably under substantially anhydrous conditions and at a temperature between <NUM> and <NUM>, more preferably between <NUM> and <NUM>, until the reaction between the isocyanate groups and the isocyanate-reactive groups is substantially complete. The isocyanate content can be followed by the back titration with an amine, usually dibutylamine.

The reaction may be facilitated by the addition of <NUM> to <NUM>%, preferably <NUM> to <NUM>%, by weight of a solvent in order to reduce the viscosity of the pre-polymer and avoid side reactions leading to undesired branching or gel formation. It is preferentially water-soluble with a low boiling water temperature (<<NUM>). The solvent is preferably acetone or methylethylketone.

It is common to use catalysts to accelerate the reaction of the isocyanates with the isocyanate reactive groups. Bismuth neodecanoate is preferred over dibutyltin dilaurate. Often specific inhibitors are added in order to prevent that ethylenically unsaturated groups would already react during the reaction and lead to a gel. Butylhydroxytoluene is preferred over butylhydroxyanisole, hydroquinone monomethyl ether and hydroquinone. A person skilled in the art is well aware of the type of catalysts and inhibitors that can be used to facilitate the reaction.

It is possible in the frame of this invention to use a sequential process during which compound (Ai) and/or compounds (Aiv), (Aii), (Aiii), (Av) and (Avi) are added sequentially and/or incrementally in two or several portions, or with a continuous feed. The reason for this is a better control on the exothermicity of the reaction, especially when no solvent is present. Another advantage is to control the architecture and molecular weight distribution of the polymer in a favorable way for instance to limit the viscosity.

In a special embodiment of the reaction, the remaining free isocyanate groups provided by the reaction of compound (Ai) to (Avi) are reacted intentionally to give allophanate and/or biurets groups. This provides molecular weight increase and chain branching which can be favorable for the final performance of the polymer dispersion.

The pre-polymer obtained after the reaction of (Ai), (Aii), (Aiii), (Aiv), (Av) and (Avi) if present, is first neutralized (if appropriate) and then dispersed in an aqueous medium by adding the pre-polymer into water or reversely by adding water to the pre-polymer. If compounds (B) are present, these are typically present in the pre-polymer before the neutralization and the dispersion steps. Usually this dispersion proceeds under high sheer mixing.

When the dispersion requires the preliminary neutralization of the hydrophilic groups provided by compound (Aii), such as the carboxylic acid, sulfonic acid or phosphonic acid groups into anionic salts, this is preferably done by adding an organic or inorganic neutralizing agent to the pre-polymer or the water. Suitable neutralizing agents include volatile organic tertiary amines such as trimethylamine, triethylamine, triisopropylamine, tributylamine, N,N-dimethylcyclohexylamine, N,N-dimethylaniline, N-methylmorpholine, N-ethylmorpholine, N-methylpiperazine, N-methylpyrrolidine and N-methylpiperidine. Triethylamine is preferred. Suitable neutralizing agents include non-volatile inorganic bases comprising monovalent metal cations, preferably alkali metals such as lithium, sodium and potassium and anions such as hydroxides, hydrides, carbonates and bicarbonates that do not remain in the dispersion as such. Sodium hydroxide is preferred.

The total amount of these neutralizing agents can be calculated according to the total amount of acid groups to be neutralized. The molar ratio between the acid group and the neutralization agent is from <NUM>:<NUM> to <NUM>:<NUM>, preferably <NUM>:<NUM> to <NUM>:<NUM>, most preferably <NUM>:<NUM> to <NUM>:<NUM>. Generally a stoichiometric ratio of about <NUM>:<NUM> is used unless the buffer obtained from the partial neutralization of the week acid with a strong base is required.

Optionally, a further compound (Avi) is added comprising active amino groups capable of making a chain extension or a chain capping of the remaining isocyanate end-groups of the pre-polymer. This is generally done in the aqueous phase at a temperature between <NUM> and <NUM>, preferably between <NUM> to <NUM>. Water can act as chain extender after natural hydrolysis of the free isocyanates into the corresponding amines and consecutive chain extension with other remaining isocyanates to provide ureas.

The total amount of compound (Avi) used is generally calculated according to the amount of residual isocyanate groups present in the polyurethane prepolymer. The ratio of isocyanate groups in the prepolymer to the amine groups in the chain extender (Avi) during the chain extension is generally in the range of from about <NUM>:<NUM> to about <NUM>:<NUM>, preferably from about <NUM>:<NUM> to about <NUM>:<NUM> on an equivalent basis. This ratio is more preferably <NUM>:<NUM> in order to obtain a fully reacted polyurethane polymer with no residual isocyanate groups.

In general, after the formation of the dispersion of the pre-polymer and when it contains a volatile solvent with a boiling point of below <NUM>, the polymer dispersion is stripped. This is usually done under reduced pressure and at a temperature between <NUM> and <NUM>, preferably <NUM> to <NUM>. Additional water is added to compensate the possible water loss during stripping and fix the desired solid content of the dispersion.

The aqueous bio-based energy-curable polyurethane composition according to the invention provides a coating after film formation and complete evaporation of the water, followed by ultraviolet light (UV) radiation curing or electron beam (EB) radiation curing. The radiation-curable compositions according to the present invention are preferably curable by ultraviolet irradiation in the presence of a photoinitiator.

The coating has a high biocarbon content with a highly desirable material carbon footprint reduction and circularity impact. Particularly, the bio-based energy-curable polyurethane composition according to the invention provides a hard coating with a high performance level for the protection and embellishment of a large range of substrates. Between others, it provides an excellent adhesion associated to good optical properties like transparency, clarity, haze and gloss. It also has excellent mechanical and chemical resistance properties.

The present invention therefore also relates to the use of the compositions for making inks, varnishes or coatings and to a process for making inks, varnishes or coatings wherein a composition as described above is used. Digital printing (inkjet inks) and 3D printing are also particularly relevant to the invention.

The coating, ink or overprint varnish prepared from a composition according to the invention can further comprise additives such as photo-initiators, thermal crosslinkers, wetting and leveling agents, rheology modifiers, defoamers, waxes, colorants, pigments or inorganic fillers.

In the frame of this invention, it is particularly suitable to use a biobased additive. A relevant example is the use of Bayhydur ECO <NUM>-<NUM> as a water-dispersible biobased polyisocyanate thermal crosslinker for <NUM> dual curing.

The polyurethane composition can also contain any other polymer dispersions or emulsions different from the invention. Preferably, these polymer dispersions or emulsions are bio-based and contain a bio-carbon content superior to <NUM>%, preferably superior to <NUM>%, more preferably superior to <NUM>%, most preferably superior to <NUM>%. The most preferably, these polymer dispersions or emulsions are containing ethylenically unsaturated functionalities like (meth)acrylate groups.

It is for instance advantageous to add a bio-based waterborne emulsion based on the previously described natural epoxidized oil or natural epoxidized fatty acid. Epoxidized soybean oil is preferred. It is partially or fully reacted with (meth)acrylic acid to obtain an ethylenically unsaturated alcohol or polyol after the opening of the epoxy ring. The hydroxyl groups are partially or fully reacted with an anhydride to obtain an ethylenically unsaturated compound with at least one carboxylic acid functional group. The anhydride is preferably succinic anhydride. The product is then partially or fully neutralized with an organic or inorganic base. Sodium hydroxide is preferred. It is finally optionally mixed with an emulsifier. Nonionic bloc copolymer emulsifiers with an HLB value above <NUM> are preferred, more preferably above <NUM>, even more preferably above <NUM>, most preferably above <NUM>, the most preferably above <NUM>. When water is added to the product under high-shear agitation at ambient or moderate temperature, a stable emulsion is obtained with a solid content between <NUM>% and <NUM>% and with a low droplet size below <NUM>, typically below <NUM>.

The invention is also related to a method for coating a surface with the composition as described above comprising the steps of:.

In particular, a low-energy ultraviolet light (LED lamp) can be used advantageously. The ultraviolet light can also be provided by an excimer lamp to provide curing delivering desirable surface patterns and optical properties including low gloss.

Alternatively, the curing mechanism can also be partially or totally a thermal curing in the presence of thermal initiators well known in the state of the art, typically peroxide- or azo- compounds with a suitable half-time of decomposition at curing temperature.

The compositions according to the invention are particularly suitable for making coatings for wood furniture and plastic resilient flooring.

The examples which will follow illustrate the invention without limiting it.

IPDI = Desmodur® I, isophorone diisocyanate from Covestro. Product is used as a reactant.

HDI = Desmodur® H, hexane diisocyanate from Covestro. Product is used as a reactant.

N7300 = Desmodur® ECO N7300, biobased pentane diisocyanate trimer from Covestro. Product is used as a reactant.

MOD1071 = biobased acrylated polyester diol with IOH ~<NUM> KOH/g which is obtained by the reaction of an epoxidized soybean oil having an oxirane oxygen content of ~<NUM>% with acrylic acid and succinic anhydride. Product is used as a reactant.

MOD1010 = biobased acrylated polyether diol with IOH ~<NUM> KOH/g which is obtained by the reaction of bisphenol A diglycidylether diacrylate with acrylic acid. Product is used as a reactant.

MOD450 = biobased acrylated polyester alcohol with IOH ~<NUM> KOH/g which is obtained by the reaction of a fatty acid dimer having AV ~<NUM> mgKOH/g with pentaerythritol and acrylic acid. Product is used as a reactant.

MOD706 = biobased acrylated polyester alcohol with IOH ~<NUM> KOH/g which is obtained by the reaction of glycerol propoxylate having IOH ~<NUM> mgKOH/g with acrylic acid. Product is used as a reactant.

MOD767 = biobased acrylated polyester alcohol with IOH ~<NUM> KOH/g which is obtained by the reaction of hydroxyethyl acrylate with lactide. Product is used as a reactant.

AE532 = biobased methacrylated ether alcohol with IOH ~<NUM> KOH/g which is obtained by the reaction of glycidyl methacrylate with lauric acid. Product is used as a reactant.

NX7202 = Cardolite® GX7202 from Cardolite. Biobased cardanol-derived acrylated nono-alcohol with IOH ~<NUM> KOH/g. Product is used as a reactant.

NX7216 = Cardolite® NX7202 from Cardolite. Biobased cardanol-derived acrylated diol with IOH ~<NUM> KOH/g. Product is used as a reactant.

NX9201 = Cardolite® NX9201 from Cardolite. Biobased cardanol-derived polyether diol with IOH ~<NUM> KOH/g. Product is used as a reactant.

DMPA = dimethylolpropionic acid from Perstorp. Product is used as a reactant. BUTOH = biobased butanol from Green Biologics. Product is used as a reactant. N120 = Ymer® N120, polyethyleneglycol diol with IOH = <NUM> KOH/g from Perstorp. Product is used as a reactant.

PDA = <NUM>,<NUM> propylene diamine from Lanxess. Product is used as a reactant.

BHT = butylate hydroxyl toluene from Merisol. Product used as a radical inhibitor. BiND = Valikat® Bi <NUM>, bismuth neodecanoate from Umicore. Product is used as a catalyst.

TEA = triethylamine from Arkema. Product is used as a neutralizer.

NaOH <NUM>% = sodium hydroxide as a <NUM>% solution in water from Brenntag. Product is used as a neutralizer.

SR4485 = Acticide® SR4485, water-based biocide composition from Thor. Product is used as a biocide.

ACE = acetone available from Brenntag. Product is used as a process solvent.

Charge reactor with <NUM> of ACE; <NUM> of MOD1071; <NUM> of DMPA; <NUM> of MOD450; <NUM> of MOD706; <NUM> of BHT and <NUM> of BiND. Mix the products at ambient temperature and under an agitation of <NUM> rpm. Heat the reactor jacket to <NUM> and start air-sparging at a level of <NUM> liters/kg/hour. Add five shots of <NUM> of IPDI, each shot being followed by <NUM> hour of reaction under reflux with the reactor jacket maintained at <NUM>. After the last maturation step, keep the reaction at reflux until the I(NCO) is reaching a plateau at ~<NUM> meq/g. Cool down the reaction mixture to <NUM> and stop air-sparging. Add <NUM> of TEA to the reactor and increase stirring at <NUM> rpm for <NUM> minutes. Charge a separate dispersion vessel with <NUM> of H2O at ambient temperature and mix with a stirrer at a speed of <NUM> rpm. Transfer the pre-polymer solution in acetone at <NUM> into the dispersion vessel during a period of <NUM> minutes to make the polymer dispersion. Decrease the agitation to <NUM> rpm while heating the reactor jacket to <NUM>. Increase progressively the vacuum to <NUM> mbar with the aid of a vacuum pump while preventing excessive foam formation. Continue the solvent stripping for about <NUM> hours until the ACE level is measured below <NUM>%. Cool the reactor below <NUM>. Add <NUM> of SR4485 together with some additional H2O to adjust the solid content at a target of ~<NUM>% solid material. When completely homogenous, drum-off the reactor over a <NUM> micron sieve. The isocyanate content I(NCO) in the prepolymer reaction mixture was measured using a dibutylamine back-titration method and is expressed in meq/g. The following examples were prepared according to the adapted process of Example <NUM> and their detailed weight composition refer to the table <NUM>.

Modification of Example <NUM> using neutralization with NaOH <NUM>%.

Modification of Example <NUM> where MOD706 is replaced by NX7202.

Modification of Example <NUM> where MOD706 is replaced by MOD767.

Modification of Example <NUM> where MOD706 is replaced by AE532.

Modification of Example <NUM> where DMPA is partly replaced by N120.

Modification of Example <NUM> where MOD1071 is replaced by NX7216.

Modification of Example <NUM> where IPDI is partly replaced by N7300 and BUTOH; chain extension from the reaction of residual isocyanates with PDA added to the fresh dispersion.

BAYHYDROL® ECO UV <NUM> as biobased market reference from Covestro with <NUM>% bio-carbon.

UCECOAT® <NUM> as biobased market reference from allnex with ~<NUM>% bio-carbon. This product is taken as an internal benchmark for an entry-performance in clear coat applications.

UCECOAT® <NUM> as biobased market reference from allnex with ~<NUM>% bio-carbon. This product is taken as an internal benchmark for high-end performance in clear coat or pigmented applications.

UCECOAT® <NUM> as biobased market reference from allnex with ~<NUM>% bio-carbon. This resin is made based on Aiv type of compound comprising more than <NUM> % Bisphenol A. This product targets a high-end performance level with a significant amount of bio-carbon inside and a strong sustainability positioning.

Modification of Example <NUM> where MOD1070 is replaced by MOD1010 and IPDI is partly replaced by N7300 and BUTOH. This resin is made based on compounds comprising BPA.

Modification of Example <NUM> where MOD1070 is replaced by NX9201.

Modification of Example <NUM> where MOD1070 is replaced by NX9201 and IPDI is partly replaced by N7300 and BUTOH.

Modification of Example <NUM> where MOD1070 is replaced by NX9201; MOD706 is replaced by NX7202; IPDI is partly replaced by HDI; TEA is replaced by NaOH <NUM>%.

The solids content of the aqueous polymer composition was measured by gravimetry after drying <NUM> the dispersion during <NUM> at <NUM>. It is expressed in %.

The viscosity of the aqueous polymer composition was measured at <NUM> with a cone and plate viscosimeter ref. Anton Paar MCR <NUM>. It is expressed in mPa.

The pH of the aqueous polymer composition was measured according to DIN EN ISO <NUM>.

The average particle size of the aqueous polymer composition was measured by Dynamic Light Scattering equipment ref. Malvern Particle Analyzer Processor type <NUM>/4600SM. It is expressed in nm.

The minimum film formation temperature (MFFT) of the aqueous polymer composition was measured by applying a thin wet coating on a automatic gradient-heated metal plate ref. Rhopoint MFFT <NUM> covering the desired temperature range. It is expressed in °C. A low value (<<NUM>) is desirable so that no coalescing agent (increasing VOC) is required to make a good homogenous film.

The aqueous resins described as examples of the invention were formulated with <NUM> % of Omnirad®<NUM> (photo-initiator) and <NUM>% of Additol® VXW <NUM> pre-diluted at <NUM>% in water (thickener) before application. In the case of BAYHYDROL® ECO UV <NUM>, an additional quantity of <NUM>% butyl cellosolve or <NUM>,<NUM>-propanediol (co-solvent) and <NUM>% BYK® <NUM> (wetting agent) was required in order to get a coating with suitable film formation and quality.

The amount of unsaturations in calculated from the bill of materials and refers to the amount of acrylic acid or glycidyl methacrylate present in the polymer. It is expressed in meq/g of the polymer composition.

In the case of Example R1, this information is not available and a titration was used. The titration protocol typically involves the reaction of the activated double bond with morpholine using an aza-Michael addition and followed by the reaction of the excess of morpholine with acetic anhydride (with formation of the amide derivative and acetic acid) and the dual titration of the acetic acid with sodium hydroxide and the tertiary amine with hydrochloric acid.

The product is applied as a 50µ wet layer on Leneta® sheet and dried for <NUM> at <NUM>. After cooling and stabilization at <NUM>, the residual tack of the coating is measured by pressing the finger on the coating and assessing the ease to separate the finger without adherence; it is expressed in a scale from <NUM>-<NUM> (<NUM> = no tack).

The gloss of the coating is assessed after application with a Meyer bar of a 50µ wet layer on white Leneta sheet followed by drying during <NUM> at <NUM> and UV curing at <NUM> W/cm Hg lamp with <NUM>/min conveyer speed. It is measured with a BYK Gardner Micro TRI-gloss gloss-meter in accordance with DIN-<NUM> standard with a light incidence of <NUM>°. A high gloss value is desirable to provide good aesthetics of the coated substrates.

The yellowing of the coating is assessed after application with a Meyer bar of a 50µ wet layer on white Leneta sheet followed by drying during <NUM> at <NUM> and UV curing at <NUM> W/cm Hg lamp with <NUM>/min conveyer speed. The yellowing (b value) is measured using a colorimeter before curing and one hour after curing. The difference in coloration (delta b) is reported. A low yellowing value protects the good aesthetics of the coated substrates.

The stain resistance of the coating is assessed after application with a Meyer bar of a 50µ wet layer on white Leneta sheet followed by drying during <NUM> at <NUM> and UV curing at <NUM> W/cm Hg lamp with <NUM>/min conveyer speed. Stains are applied using a black alcohol marker ref. N70 as well as glass microfiber filter pieces saturated with a test substance placed in contact of the coating during <NUM> hours. The test substances used are mustard, coffee, eosine, isobetadine, <NUM>% ammonia and <NUM>% ethanol. The stains are washed with a couple of rubs using a tissue saturated with water or isopropanol. The remaining stains are assessed visually using a <NUM>-<NUM> scale, <NUM> = no residual stain. A high stain resistance is expected to provide the best coating protection against any household product spillage.

The solvent resistance of the coating is assessed after application with a Meyer bar of a 50µ wet layer on white Leneta sheet followed by drying during <NUM> at <NUM> and UV curing at <NUM> W/cm Hg lamp with <NUM>/min conveyer speed. It is evaluated with acetone double rubs using a cotton rag saturated with the solvent until the coating is being removed. One double rub is equal to a forward and backward stroke. The reported value is the number of double rubs required to break through the cured coating composition. A high solvent resistance is expected to provide the best coating protection against any household product spillage.

The method measures the surface hardness of a wet coating of 120µ applied on glass plate. The coating is dried for <NUM> minute at <NUM> and finally cured under an UV- Hg lamp of <NUM> W/cm at <NUM>/min. The coated samples are stabilized during <NUM> hours in a conditioned room (<NUM> and <NUM>% humidity) and the Persoz pendulum hardness is determined at <NUM> different places on the surface. The mean value is calculated and expressed in seconds. A high Persoz hardness is expected to provide the best coating protection against any storehouse or household deterioration.

The nail scratch resistance of the coating is assessed after application with a Meyer bar of a 120µ wet layer on sanded white melamine board and followed by water evaporation for <NUM>' at <NUM> followed by UV curing using a 80W/cm Hg lamp at a conveyer speed of <NUM>/min. The test is performed after <NUM> hours in a conditioned room (<NUM> at <NUM>% humidity) by pressing firmly the nail with a linear movement on the coating and assessing the visual mark or damage resulting from an adhesion loss using a <NUM>-<NUM> scale, <NUM> = no visible mark or damage. A high nail scratch resistance is expected to provide the best coating protection against any storehouse or household deterioration.

The pencil hardness of the coating is assessed after application with a Meyer bar of a 120µ wet layer on sanded white melamine board and followed by water evaporation for <NUM>' at <NUM> followed by UV curing using a 80W/cm Hg lamp at a conveyer speed of <NUM>/min. The test is performed after <NUM> hours in a conditioned room (<NUM> at <NUM>% humidity) by scratching the cured coating with sharp pencils of increasing hardness using a dedicated metallic holder that fixes the right angle and the uniform pressure applied. The test result is reported as the pencil hardness above which the coating is clearly being damaged. The pencil hardness scale goes from soft to hard as 9B - 8B - 7B - 6B - 5B - 4B - 3B - 2B - 1B - HB - F - <NUM> - <NUM> - <NUM> - <NUM> - <NUM> - <NUM> - <NUM> - <NUM> - <NUM>. A high coating hardness is expected to provide the best coating protection against any storehouse or household deterioration.

The biogenic carbon content (%) was determined using ASTM D6866 standard. The sample was dried and transformed catalytically at elevated temperature into graphite, providing the total carbon content of the sample (%). The C14 / C12 isotope ratio of the graphite was measured using accelerated mass spectroscopy and then transposed into biogenic carbon content (%) using a standard of modern oxalic acid as a reference.

The biogenic carbon content is then further transposed into material carbon footprint reduction (g CO<NUM>/kg) corresponding to the equivalent savings of CO<NUM> released in the atmosphere and assuming the neutrality proposition from equivalent atmospheric CO<NUM> uptake during plant photosynthesis. Material carbon footprint reduction is used as a quantified sustainability performance of the biopolymer; a high value indicates a stronger sustainability impact.

Table <NUM> shows for each of the examples whether the compounds used to make the aqueous bio-based energy-curable polyurethane comprises biocarbon content.

Table <NUM> a and b describe for each example and reference example (except for those that are commercially available) the amount of each compound used.

Table <NUM> a and b show the product characteristics of each example. It is clear that the biobased polyurethane R1 has a high MFFT which is imposing the usage of coalescing agents in order to obtain an acceptable coating quality during application.

Table 4a and b show the coating characteristics and the performances of the examples and the reference examples. It is clear from the table that the coating made with aqueous biobased polyurethane according to invention provides good to excellent coating performances. Especially results on the nail scratch resistance, and acetone double rubs are surprisingly good.

Claim 1:
An aqueous bio-based energy-curable polyurethane composition comprising:
at least one ethylenically unsaturated polyurethane pre-polymer (A) obtained from the reaction of:
• at least one aliphatic, cycloaliphatic or aromatic polyisocyanate compound (Ai),
• at least one hydrophilic compound (Aii) containing at least one reactive group capable to react with an isocyanate and which is capable to render the polyurethane pre-polymer dispersible in an aqueous medium either directly or after the reaction with an organic or inorganic neutralizing agent to provide a salt therefrom,
• at least one ethylenically unsaturated compound (Aiii), containing essentially one reactive group capable to react with an isocyanate,
• at least one ethylenically unsaturated compound (Aiv), containing at least two reactive groups capable to react with an isocyanate,
optionally, at least one ethylenically unsaturated compound (B) different from (Aiii) and (Aiv) having no reactive group capable to react with an isocyanate,
wherein the ethylenically unsaturated compounds (Aiii), (Aiv) and (B) have each a biocarbon content of more than <NUM>% by weight of total carbon content of the compound, and are obtained by reacting an ethylenically unsaturated compound with a compound derived from biobased sources, whereby the biocarbon content is determined using ASTM D6866 standard;
wherein the ethylenically unsaturated compounds (Aiv) is prepared with from <NUM>-40wt% bisphenol A; preferably without bisphenol A; and
wherein said composition comprises a total amount of polymerizable ethylenically unsaturated groups of at least <NUM> meq/g expressed per total weight of polyurethane composition, preferably at least 1meq/g, more preferably at least 2meq/g, even more preferably at least 3meq/g and the most preferably at least 4meq/g.