FIELD OF THE INVENTION

[0001] The present application relates to a binder, a formulation for coating wood- containing substrates comprising the binder, a method for making the binder, a method for making the formulation, a method for treating the wood-containing substrate with the binder or formulation, and to the treated wood-containing substrate as such.

BACKGROUND OF THE INVENTION

[0002] In addition to provision of aesthetic appearance, wood coatings are designed to protect the wood from weathering due to environmental influence, e.g. by preventing rapid water take-up or loss of moisture, or reduction of shrinking and swelling which can cause cracking within the wood. Weathering of wood can be caused by UV and visible light radiation, moisture and wind. In particular, the surface of wood is usually negatively affected by weathering.

[0003] Wood coating formulations protecting particularly the surface of wood from weathering are commonly known and widely available. Such formulations usually consist of the following components: resin or binder, solvent (organic solvent or water), filler (usually calcium carbonate), optionally pigments and other additives like wetting agents, defoamers, biocides or rheological modifiers. The binder or resin is usually present in an amount of about 15 to 35 wt% in the wood coating formulation. The binder or resin provides adhesion, gloss and water repellent properties to the wood and also fixes the other components, like for example the pigment to each other and to the wood. [0004] Drawbacks of known wood coating formulations are low water resistance and low

UV light radiation resistance properties. Moreover, said known wood coating formulations in general allow for a low filler content such as up to 65 wt% at the most only. This may unfavorably prolong the drying time of the coating when wood is coated with a respective formulation.

OBJECTS OF THE INVENTION

[0005] It is an object of the present application to provide a wood coating formulation which overcomes the drawbacks of the known wood coating formulations.

SUMMARY OF THE INVENTION

[0006] The invention relates to the following items:

1. Binder comprising at least components (A), (B1 ), optionally (B2), and (C):

(A) a polymer comprising at least the following monomer units:

(A1 ) at least one monomer comprising styrene units;

(A2) at least one monomer comprising acrylic acid ester units; (A3) at least one monomer comprising acrylic acid units;

(A4) at least one olefinic monomer comprising amine groups; and (A5) at least one olefinic surfactant;

(B1 ) at least one ionic surfactant; and (B2) optionally at least one non-ionic surfactant; and (C) water.

2. Binder according to item 1 , wherein polymer (A) comprises at least the following monomer units:

30.0 to 50.0 % by weight of monomer (A1 ); 45.0 to 60.0 % by weight of monomer (A2); 0.1 to 8.0 % by weight of monomer (A3);

0.1 to 8.0 % by weight of monomer (A4);

0.1 to 7.0 % by weight of monomer (A5); based on the total amount of (A) (= 100 % by weight). 3. Binder according to item 1 or 2, wherein polymer (A) comprises at least the following monomer units:

35.0 to 47.0 % by weight of monomer (A1 );

47.0 to 57.0 % by weight of monomer (A2);

0.5 to 7.0 % by weight of monomer (A3); 0.2 to 7.0 % by weight of monomer (A4);

0.2 to 5.0 % by weight of monomer (A5); based on the total amount of (A) (= 100 % by weight).

4. Binder according to at least one of the preceding items, wherein component (B1) is selected from a group consisting of: salts of fatty acids, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, alkylsulfonates, fatty alcohol sulfates such as sodium lauryl sulfate, alkylether sulfates such as sodium dodecyl poly(oxyethylene) sulfate.

5. Binder according to at least one of the preceding items, wherein component (B2) is selected from a group consisting of: polyalkylene oxide carboxylic acid esters, ethoxylated fatty alcohols, poloxamers, and alkyl polysaccharides.

6. Binder according to at least one of the preceding items, wherein the binder comprises from

40 to 60 % by weight of (A); 0.1 to 5.0 % by weight of (B1);

0.0 to 5.0 % by weight of (B2)

35 to 70 % by weight of (C); based on the total amount of the binder (= 100 % by weight). 7. Binder according to at least one of the preceding items, wherein the binder further comprises a compound (D):

(D) a compound comprising a silane group, preferably wherein the compound is an epoxy silane.

8. Binder according to item 7, wherein compound (D) is present in an amount of from 0.1 to 2 % by weight or 0.2 to 1.0 % by weight or from 0.3 to 1 % by weight based on the total amount of polymer (A) (= 100 % by weight).

9. Formulation for coating wood-containing substrates, wherein the formulation comprises at least one or more binders according to at least one of the preceding items 1 to 8, and a pigment, preferably a white pigment, and a filler, and optionally at least one additive selected from the group consisting of dispersing agents and thickeners, or two or more thereof.

10. Formulation according to item 9, wherein the formulation comprises from

10 to 40 % by weight, preferably from 20 to 30 % by weight of at least one binder according to at least one of the claims 1 to 9; 60 to 90 % by weight of a filler selected from the group consisting of: earth alkali metal salt of a carbonate, sulfate, phosphate, clay and kaolin, preferably calcium carbonate, or two or more thereof; based on the total amount of the formulation (= 100 % by weight). Method of making a binder as defined in at least one of items 1 to 8 comprising: emulsion polymerization of compounds (A1) to (A5) in presence of compounds (B1), optionally compound (B2), and compound (C). Method of making a formulation as defined in item 9 or 10 comprising: mixing a binder as defined in any one of items 1 to 8, a pigment, preferably a white pigment, and a filler. Method of treating a wood-containing substrate, comprising at least step (S1) followed by steps (S2) and (S3):

(51) contacting a wood-containing substrate with the formulation defined in at least one of the items 9 to 10; or contacting a wood-containing substrate with the formulation made according to item 12; or contacting a wood-containing substrate with the binder as defined in at least one of the items 1 to 8; or contacting a wood-containing substrate with the binder made according to item 11 ;

(52) heat-treatment of the wood-containing substrate obtained after step (S1), preferably at a temperature of 40 to 100 °C, or 50 to 80 °C, or 50 to 60 °C; and (S3) finishing the wood-containing substrate obtained after step (S2). Wood-containing substrate comprising at least a binder as defined in at least one of the items 1 to 8; or wood-containing substrate comprising at least a formulation as defined in at least one of the items 9 to 10; or wood-containing substrate treated by the method according to item 13.

[0007] The binder according to the invention has the advantage that the amount of filler present in a wood coating formulation prepared therefrom can be increased up to 75 % by weight based on the total weight of the formulation according to the invention. This advantageously provides for a binder formulation having a beneficial drying time in wood coated with a respectively prepared wood coating formulation. Moreover, the wood coating formulation according to the invention provides for excellent water resistance and resistance against sun radiation.

DETAILED DESCRIPTION OF THE INVENTION

[0008] First aspect: Binder according to the invention

[0009] In a first aspect, the invention relates to a binder comprising a polymer (A), component (B1 ), optionally component (B2), and component (C):

(A) a polymer comprising at least the following monomer units:

(A1 ) at least one monomer comprising styrene units;

(A2) at least one monomer comprising acrylate ester units;

(A3) at least one monomer comprising acrylic acid units;

(A4) at least one olefinic monomer comprising amine groups; and (A5) at least one olefinic surfactant;

(B1 ) at least one ionic surfactant;

(B2) optionally at least one non-ionic surfactant; and (C) water. [0010] Component (A)

[0011] According to the invention, the binder comprises a polymer (A).

[0012] Polymer (A) is the reaction product obtained in a polymerization reaction of monomers (A1 ) to (A5).

[0013] Thus, component (A) is a polymer which comprises moieties derived from at least monomers (A1 ) to (A5).

[0014] In another embodiment, component (A) is a polymer which consists of moieties derived from at least monomers (A1 ) to (A5).

[0015] Monomer (A1 )

[0016] According to the invention, monomer (A1 ) is a monomer comprising styrene units.

[0017] In a preferred embodiment, monomer (A1) consists of styrene units.

[0018] The amount of monomer (A1) present in polymer (A) is at least 30.0 % by weight and at most 50.0 % by weight, or at least 31 % by weight and at most 49.0 % by weight, or at least 32 % by weight and at most 48.0 % by weight, or at least 35 % by weight and at most 47.0 % by weight, or at least 36 % by weight and at most 45.0 % by weight, or at least 38.0 % by weight and at most 44.0 % by weight based on the total amount of component (A) (=100 % by weight).

[0019] Monomer (A2)

[0020] According to the invention, monomer (A2) is a monomer comprising acrylic acid ester units, i.e. acrylate units.

[0021] In a preferred embodiment, monomer (A2) consists of acrylic acid ester units. [0022] The term “acrylic acid ester units” encompasses the term “methacrylic acid ester units”. Thus, the term “(meth)acrylic acid ester unit” encompasses both an acrylic acid ester as well as a methacrylic acid ester or another ester substituted in a-position of the acid moiety.

[0023] In one embodiment, monomer (A2) is an acrylic acid ester CH ₂ =CR ³ COO-R ² wherein R ² represents a residue, i.e. the alcohol moiety of the ester, containing preferably from 1 to 40 carbon atoms.

[0024] In one embodiment, R ² is a branched or unbranched or cyclic Ci to C40 alkyl group that may be saturated or unsaturated.

[0025] In a preferred embodiment, R ² is selected from a branched or unbranched or cyclic C ₂ to C ₂ o alkyl group, preferably from a C to C10 alkyl group.

[0026] In one embodiment, R ³ is selected from the group consisting of H, CH ₃ , or C ₂ H .

[0027] In a preferred embodiment, R ³ is H and R ² is a C4-10 alkyl group. [0028] The polymer may comprise different monomer units (A2).

[0029] The amount of monomer (A2) present in component (A) is at least 45.0 % by weight and at most 60.0 % by weight, or at least 46.0% by weight and at most 59.0% by weight, or at least 47% by weight and at most 57.0% by weight, or at least 48% by weight and at most 56.0 % by weight, or at least 46% by weight and at most 55.0% by weight, or at least 50.0 % by weight and at most 54.0 % by weight based on the total amount of component (A) (=100% by weight).

[0030] Monomer (A3)

[0031] According to the invention, monomer (A3) is a monomer comprising acrylic acid units. [0032] In a preferred embodiment, monomer (A3) consists of acrylic acid units.

[0033] The term “acrylic acid” encompasses the term “methacrylic acid”. Thus, the term “(meth)acrylic acid” encompasses both an acrylic acid as well as a methacrylic acid or another acrylic acid substituted in a-position of the acid moiety.

[0034] In one embodiment, monomer (A3) is CH ₂ =CR ³ COOH, wherein R ³ is selected from the group consisting of H, CH ₃ , or C ₂ H ₅ .

[0035] Polymer (A) may comprise different monomer units (A3).

[0036] In a preferred embodiment, monomer (A3) is methacrylic acid.

[0037] The amount of monomer (A3) present in component (A) is at least 0.1 % by weight and at most 8.0 % by weight, or at least 0.5% by weight and at most 7.0% by weight, or at least 0.7% by weight and at most 6.0 % by weight, or at least 1.0 % by weight and at most 5.0 % by weight based on the total amount of component (A) (=100% by weight).

[0038] Monomer (A4)

[0039] According to the invention, monomer (A4) is an olefinic monomer containing an amine group.

[0040] In a preferred embodiment, monomer (A4) is the esterification product of an acrylic acid with an alcohol comprising an amino group.

[0041] In one embodiment, (A4) is the esterification product of acrylic acid with HO- (CH ₂ )n-N(C-i-6)2, wherein n is an integer of from 2 to 6, i.e.

CH ₂ =CR ³ C(0)0-(CH ₂ ) _n -N(Cr ₆ )2, wherein R ³ and n have the meaning as defined above. [0042] In one embodiment, monomer (A4) is selected from diethylaminoethyl methacrylate or dimethylaminoethyl methacrylate or t-butylaminoethyl methacrylate.

[0043] The amount of monomer (A4) present in component (A) is at least 0.1 % by weight and at most 8.0 % by weight, or at least 0.2% by weight and at most 7.0% by weight, or at least 0.3% by weight and at most 6.0 % by weight, or at least 0.4 % by weight and at most 5.0 % by weight, or at least 0.5 % by weight and at most 4.5 % by weight based on the total amount of component (A) (=100% by weight).

[0044] Monomer (A5)

[0045] According to the invention, monomer (A5) is an olefinic surfactant.

[0046] The term “olefinic surfactant” is synonymously used with the term “reactive surfactant”.

[0047] As is known in the art, a reactive surfactant contains a polymerizable olefinic moiety that can participate in free-radical emulsion polymerization reactions. When used in an emulsion polymerization, at least a fraction of the surfactant molecules is irreversibly bound to the emulsion polymer chains and droplets.

[0048] Reactive surfactants typically consist of three moieties: a hydrophobic moiety; a hydrophilic moiety; and a polymerizable moiety, usually comprising an olefinic double bond.

[0049] Reactive surfactants are known in the art.

[0050] In one embodiment, the reactive surfactant is selected from the group consisting of: vinyl sulfonic acid, methallyl sulfonic acid or a salt thereof, allyloxy hydroxypropyl sulfonic acid or a salt thereof, allyl methoxy triethylene glycol ether, sulfopropyl acrylate, vinyl phosphate or a salt thereof, monosodium ethylsulfonate monododecyl maleate, sorbitol acrylate, sorbitol methacrylate, perfluoroheptoxy poly(propyloxy) methacrylate, phenoxyl poly(ethyleneoxy acrylate, phenoxyl poly(ethyleneoxy) methacrylate, nonyl phenoxy poly(ethyleneoxy)crotanate, nonylphenoxy poly(ethyleneoxy)fumarate, nonyl phenoxy poly(ethyleneoxy)acrylate, nonylphenoxy poly(ethyleneoxy)methacrylate, mono dodecyl maleate, and allylsulfosuccinate derivatives. [0051] Vinyl sulfonic acid as monomer unit (A5) is preferred.

[0052] The amount of monomer (A5) present in component (A) is at least 0.1 % by weight and at most 7.0 % by weight, or at least 0.2% by weight and at most 5.0% by weight, or at least 0.3% by weight and at most 4.0 % by weight, or at least 0.4 % by weight and at most 3.0 % by weight, or at least 0.5 % by weight and at most 2.5 % by weight based on the total amount of component (A) (=100% by weight).

[0053] In one embodiment, component (A) comprises or consists of, i.e. the polymer is obtained by polymerization of following monomer units:

30.0 to 50.0 % by weight of monomer (A1 );

45.0 to 60.0 % by weight of monomer (A2);

0.1 to 8.0 % by weight of monomer (A3);

0.1 to 8.0 % by weight of monomer (A4); and 0.1 to 7.0 % by weight of monomer (A5); based on the total amount of (A) (= 100 % by weight).

[0054] Preferably, component (A) comprises or consists of, i.e. is obtained by polymerization of the following monomer units:

35.0 to 47.0 % by weight of monomer (A1 );

47.0 to 57.0 % by weight of monomer (A2);

0.5 to 7.0 % by weight of monomer (A3);

0.2 to 7.0 % by weight of monomer (A4); 0.2 to 5.0 % by weight of monomer (A5); based on the total amount of (A) (= 100 % by weight).

[0055] In a still more preferred embodiment, component (A) comprises or consists of, i.e. is obtained by polymerization of the following monomer units:

36.0 to 45.0 % by weight of monomer (A1 );

46.0 to 55.0 % by weight of monomer (A2);

0.7 to 6.0 % by weight of monomer (A3); 0.4 to 5.0 % by weight of monomer (A4);

0.2 to 3.0 % by weight of monomer (A5); based on the total amount of (A) (= 100 % by weight).

[0056] Component (B1)

[0057] Component (B1) is at least one ionic surfactant.

[0058] Ionic surfactants are known in the art.

[0059] In one embodiment, component (B1) is selected from the group consisting of: salts of fatty acids, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, alkylsulfonates, fatty alcohol sulfates such as sodium lauryl sulfate, alkylether sulfates such as sodium dodecyl poly(oxyethylene) sulfate.

[0060] In a preferred embodiment, the anionic surfactant is an alkali salt of sulfuric acid esterified with a fatty alcohol or fatty alcohol ethoxylate or propoxylate, i.e. a fatty alcohol sulfate or an alkylether sulfate. [0061] The term “alkali salt of sulfuric acid esterified with a fatty alcohol or fatty alcohol ethoxylate or propoxylate, i.e. a fatty alcohol sulfate or an alkylether sulfate” encompasses the following formulas, wherein the cation preferably is a sodium cation:

[0062] CH ₃ -(CH ₂ ) _lO-16 (0-C ₂ H ₄ )o- ₂₅ OS0 ₃ ! or CH3-(CH2) _lO -16 (0-C3H6)o-25 OSO ₃ . [0063] In a preferred embodiment, said alkyl ether sulfate contains from 1 to 5 O-C2H4 respectively 0-C ₃ H ₆ units.

[0064] An example of an alkali alkylether sulfate is sodium dodecyl polyoxyethylene sulfate (sodium laureth sulfate; CAS no 9004-82-4).

[0065] Component (B1) is present in the binder according to the invention in an amount of from 0.1 to 5.0 % by weight or 0.2 to 3 % by weight or 0.3 to 2 % by weight based on the total amount of the binder (= 100 % by weight).

[0066] Component (B2) (optional)

[0067] Component (B2) is at least one non-ionic surfactant.

[0068] Non-ionic surfactants are known in the art.

[0069] In one embodiment, component (B2) is selected from the group consisting of: polyalkylene oxide carboxylic acid esters, ethoxylated fatty alcohols, poloxamers, and alkyl polysaccharides.

[0070] Prefered non-ionioc surfactants are ethoxylated fatty alcohols.

[0071] Component (B2) is present in the binder according to the invention in an amount of from 0.0 % to 5 % by weight or from 0.1 % to 4 % by weight or from 0.2 % to 3 % by weight or from 0.3 % to 2 % by weight based on the total amount of the binder (= 100 % by weight). [0072] Component (C)

[0073] The binder according to the invention is based on water (component (C)), i.e. comprises water. This, however, does not exclude the presence of organic solvents.

[0074] Thus, in one embodiment, the binder according to the invention is based on water or on water and an organic solvent.

[0075] The term “based on water or on water and an organic solvent” encompasses solutions, emulsions and dispersions of the solid and/or liquid compounds contained in the binder in water solvent. The terms “solutions”, “emulsions” and “dispersions” are used interchangeably. [0076] The term “water” encompasses distilled water as well as pipe water.

[0077] The term “organic solvent” preferably encompasses solvents which are miscible with water or are partially water soluble. Preferred organic water miscible solvents are C-. 2 alcohols, glycols such as ethylene glycol and propylene glycol, dipropylene glycol or polyethylene glycols, amides such as N-methylformamide and N,N-dimethylformamide. [0078] Partially water soluble solvents are also suitable. Preferred organic solvents are dipropylene glycol dimethylether, methoxy propyl acetate, methoxy butyl acetate (butoxyl), and methoxy methyl butyl acetate.

[0079] Preferably, the binder according to the invention is mainly based on water. The term “mainly” means that the amount of organic solvent is less than 50 % by weight, based on the total weight of water and organic solvent (= 100 % by weight). In a preferred embodiment, the amount of organic solvent is less than 40 % by weight; more preferred less than 30 % by weight, still more preferred less than 20 % by weight, still more preferred less than 10 % by weight. In one embodiment, the binder does not contain an organic solvent. [0080] The binder according to the invention may contain from 35 % to 90 % by weight water or water and an organic solvent based on the total amount of the binder (= 100 % by weight).

[0081] In a preferred embodiment, the binder contains from 35 to 65 % by weight or from 35 to 70 % by weight water, based on the total amount of the binder (= 100 % by weight).

[0082] Preferably, the binder according to the invention comprises or consists of

40 to 60 % by weight of (A);

0.1 to 5.0 % by weight of (B1);

0.0 to 5.0 % by weight of (B2)

35 to 70 % by weight of (C); based on the total amount of the binder (=100 % by weight).

[0083] According to the invention, as disclosed below, the binder is prepared by emulsion polymerization of components (A1) to (A5).

[0084] In one embodiment, the binder is prepared by emulsion polymerization in presence of one or more further additives. Suitable additives are known in the art. [0085] In one embodiment, the binder further comprises a compound (D):

(D) a compound comprising a silane group.

[0086] Compound (D) may act as an adhesion promoter.

[0087] Compound (D) may be present in an amount of from 0.1 to 2 % by weight or 0.2 to 1.0 % by weight or from 0.3 to 1 % by weight based on the total amount of polymer (A) (= 100 % by weight).

[0088] In a preferred embodiment, compound (D) is an epoxysilane. [0089] Suitable epoxy-functional silanes for use in the present invention include silanes having the formula

R ₁ Si(R ₂ ) _3-n (OR ₃ )„ wherein n is 1 , 2, or 3, Ri is alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, or phenylalkyl, wherein the Ri group contains at least one epoxy group, each R ₂ is independently hydrogen, alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, phenylalkyl, or a silane oligomer, wherein each R ₂ group can optionally include OR ₃ groups or epoxy functionality. Each R ₃ group is independently hydrogen, alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, or phenylalkyl.

[0090] The term “alkyl” as used in connection with the above silane encompasses Cr C20 alkyl, the term “cycloalkyl” encompasses C1-C20 cycloalkyl, and the term “alkenyl” encompasses C1-C20 alkenyl.

[0091] Exemplary epoxy-functional silanes include 2-(3,4-epoxycyclohexyl)- ethyltrimethoxysilane), 3-glycidoxypropyltrimethoxysilane, 3- glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3- glycidoxypropylmethyldiethoxysilane, 3-glycidylpropyl triethoxysilane.

[0092] Further additives which may be present are selected from biocides and defoamers. Suitable products are known in the art.

[0093] Second aspect: Formulation according to the invention

[0094] In a second aspect, the invention relates to a formulation for coating wood- containing substrates.

[0095] The formulation according to the invention comprises at least one or more binders according to the invention as defined in the first aspect. [0096] The formulation according to the invention has the advantage that although significantly higher amounts of a filler are present in the formulation according to the invention nevertheless the anchorage on the wood-containing substrate is good. Further, the formulation according to the invention has the advantage of providing an improved water resistance and UV light resistance to the therewith treated wood-containing substrate. Also, the formulation according to the invention has the advantage that re emulsification after water immersion is increased to 10 to 12 h.

[0097] In particular, the increased water resistance has to be mentioned. The usual market products normally resist to re-emulsification no longer than 20 min as is shown in the examples. This enhanced property enables the formulation according to the invention to be used both indoor as well as outdoor.

[0098] The present invention provides a new styrene-acrylic dispersion with a controlled particle size with a high solids content of at least 50 %, excellent storage stability and filler acceptance to be used in wood coating formulations to render smoothness and excellent water resistance on the final finishing.

[0099] Particle size is measured by DLS (Dynamic Light Scattering) technique.

[00100] Preferably, the binder has a particle size of from 150 to 250 nm such as 200 nm. The particle size distribution is commonly monomodal around 200 nm.

[00101] The solids content is measured by placing a sample in an oven at a temperature of 105 °C until a steady mass is obtained.

[00102] The amount of binder according to the invention present in the formulation according to the invention is at least 10 % by weight and at most 40 % by weight, or at least 10 % by weight and at most 35 % by weight, or at least 20 % by weight and at most 30 % by weight, based on the total amount of the formulation according to the invention (=100 % by weight). [00103] Specifically, in the fourth aspect, the invention relates to a formulation for coating wood-containing substrates wherein the formulation comprises at least one or more binders as defined in the first aspect, and a pigment.

[00104] In a further preferred embodiment, the formulation comprises at least one or more binders as defined in the first aspect, a pigment, and a filler.

[00105] Pigments

[00106] Basically, any pigment may be incorporated in the binder.

[00107] In a preferred embodiment, the pigment is a white pigment.

[00108] In a preferred embodiment, the white pigment is PO2.

[00109] In one embodiment, the amount of a pigment in the binder ranges from 5 to 10 % by weight, based on the total amount of binder (= 100 % by weight).

[00110] Fillers

[00111] In one embodiment, fillers are selected from inorganic salts which are not soluble in the binder such as sulfates, phosphates and carbonates, wherein the cation preferably is selected from earth alkali metals such as calcium.

[00112] In a preferred embodiment, the filler is calcium carbonate.

[00113] In another embodiment, the filler is selected from the group consisting of clay or kaolin.

[00114] The amount of filler present in the formulation according to the invention can be up to 75 % by weight, or up to 74 % by weight, or up to 73 % by weight, or up to 72 % by weight up to 75 % by weight, based on the total weight of the formulation according to the invention (= 100 % by weight). [00115] The formulation may further contain dispersing agents and thickeners. Suitable compounds are known in the art.

[00116] Third aspect: Method of making the binder according to the invention

[00117] In a third aspect, the invention relates to a method of making the binder according to the invention.

[00118] The method of making the binder according to the invention is an emulsion polymerization.

[00119] According to the invention, the method comprises emulsion polymerization of compounds (A1) to (A5) in presence of compounds (B1), optionally compound (B2), and compound (C) as defined in the first aspect.

[00120] Emulsion polymerization is a well-known technique for producing polymers. Typically, monomers are polymerized in aqueous medium under the influence of an initiator such as a persulfate, and in the presence of a suitable surfactant. The surfactant may be a non-ionic, an anionic or a cationic surfactant. Stabilizers such as polyvinyl alcohol and other water-soluble polymers may be added in order to promote emulsion polymerization. Other ingredients include chain transfer agents, buffering agents, and inert salts. Preservatives may be added to products sold as liquid dispersions to retard bacterial growth. These are usually added after polymerization.

[00121] There are essentially three options for conducting emulsion polymerization:

[00122] In a first option, in a dosage type, a small amount of initiator and monomers, usually in an amount of 5 to 10 % by weight, are heated up before the initial reaction temperature is reached. After onset of the reaction, the rest of initiator and monomers are metered. However, the reaction may also be performed such that a small amount of the initiator in water is provided in a reactor, and monomers and the remainder of the initiator are separately and simultaneously metered into the reactor. [00123] In a second option, in a semi-batch type, an aqueous phase is charged with initiator and about 50 % by weight of the monomers. After polymerization of this amount, the remainder is metered by dosage, or, after cooling down again, in a batch-wise manner.

[00124] In a third option, in a batch type, the whole amount of initiator and monomers are charged, and the reaction is started by heating up. Subsequently, the reaction heat is removed using e.g. a heat exchanger.

[00125] For safety reasons, frequently, in emulsion polymerizations, the dosage type is preferred, i.e., a minor portion of the initiator is provided in water, and subsequently separated feeds of a pre-emulsion of the monomers and surfactants and the major portion of the initiator are slowly and simultaneously but separately added in order to provide a controlled reaction.

[00126] Without being bound by theory it is believed that the polymerization reaction takes place in micelles in which the monomer droplet is stabilized by surfactants. The surfactants, usually an anionic or a combination of an anionic and nonionic surfactant. Anionic surfactants provide shear stability to prevent loss due to coagulation. Nonionic surfactants provide electrolyte or chemical stability to the growing latex particles

[00127] Reactive surfactants (A5) act in emulsion polymerization both as a surfactant and as a co-monomer. Usually, emulsion stabilization is their main objective, and the ability of copolymerization is an extra advantage.

[00128] Reactive surfactants have the ability to covalently bind to the dispersed phase. As a result they cannot be displaced from the interface as easily as traditional surfac tants, which are only physically bonded.

[00129] Reactive surfactants surfactant simply builds into polymer structure and does not remain in reaction mixture. In this way, it prevents migration of the surfactant (“non- migratory” surfactant) to the interface (polymer/air and polymer/substrate) in films formed of the latex. It results in better properties of the coating and reduces water sensitivity, it also improves adhesion and gloss.

[00130] In a preferred embodiment, the binder according to the invention is prepared by polymerizing monomers (A1) to (A5), thus forming component (A), in water or water and an organic solvent (C) and in the presence of component (B1 ), and optionally component (B2).

[00131] In a preferred embodiment, prior to polymerization, a mixture of monomers (A1) to (A5), component (B1), and optionally (B2), in water or water and an organic solvent (C) is homogenized. This method is exemplarily explained below:

[00132] A stable monomer pre-emulsion is prepared by adding monomers (A1) to (A5) to the vigorously stirred aqueous phase. This process involves emulsification of the relatively hydrophobic free-radically polymerizable, ethylenically unsaturated monomers in water by an oil-in-water surfactant (B1) and optionally (B2).

[00133] In one embodiment, the initial reactor charge is heated to 65 °C - 75 °C. When the temperature is reached part of the pre-emulsion, usually 3 % to 10 % by weight of the pre-emulsion is added to the reactor.

[00134] When this first charge has polymerized, the remainder of the monomer pre emulsion is gradually added over a period of 3 to 5 hours. The initiator solution is added simultaneously via separate line.

[00135] The most common water-soluble initiators used are potassium, sodium and ammonium salts of persulfates. Next in line, are the water-soluble azo compounds, especially those with an ionic group, such as 2,2’-azobis(2- amidinopropane)dihydrochloride. [00136] The amount of initiator employed may be in the range of from 0.1 to 2.0 % by weight, based on the mixture of the monomer (A1) to (A5) (= 100 % by weight), preferably 0.1 to 1.5 % by weight.

[00137] Typically, the reaction temperature is maintained at a temperature lower than 95 °C throughout the course of the reaction. Preferred is a reaction temperature between 50 °C and 95 °C, more preferably between 60 °C and 90 °C.

[00138] The process for the emulsion polymerization generally ends, for example after the optional post-heating, after a polymerization of up to 99 % of the monomers, based on the total weight, particularly preferably after up to 99.5 % of the monomers, based on the total weight.

[00139] At the end of the polymerization process, a milky fluid termed “latex, synthetic latex or polymer dispersion” is obtained. Latex is defined as colloidal dispersion of polymer particles in an aqueous medium.

[00140] In one embodiment, the emulsion polymerization may be carried out according to the following protocol:

[00141] Reactor Preparation [00142] The aqueous phase is prepared in the solution vessel. Process water is charged to the vessel and emulsifier or protective colloid (in solid or liquid form) is added through the manhole. Afterwards the vessel is heated to 70-80 °C via jacket and/or by direct steam injection to dissolve the products in water.

[00143] Pre-emulsion [00144] The monomers (according to product type) are either charged from storage tanks or (in case of small quantities) from drums to the pre-emulsion vessel. After addition of water and emulsifiers, an aqueous water-monomer emulsion is created with a fast running agitator.

[00145] Initiator Solution

[00146] An aqueous initiator solution is prepared by common methods. The initiator is added either to the top of the reactor during addition of monomers with the pre-emulsion stream.

[00147] Polymerization - Main Reaction

[00148] The content of the reactor is heated to about 60-85 °C to start polymerization. The reaction itself is running at temperatures from 70 to almost 90 °C at ambient pressure.

[00149] The heat of polymerization has to be removed either by condensation of the boiling azeotropic mixture of monomers and water in the reflux condenser or/and with jacket/half coil cooling.

[00150] After polymerization is finished (4 to 8 hours), usually a post reaction at slightly higher temperature is carried out to reduce residual monomer content. To some grades a redox system is added at lower temperatures for further reduction of residual monomer content.

[00151] After the batch is cooled down to a certain temperature (depending on the product), the batch is transferred by compressed air or a positive displacement pump through a coarse filter into one of two adjusting vessels.

[00152] Final Adjustments

[00153] In the adjusting vessels the cooling is continued and the properties of the finished products (such as solid content, viscosity, pH value, etc.) are adjusted according to the specifications. [00154] Filtration and Packaging

[00155] After final analysis the adjusted product is transferred with a positive displacement pump or compressed air through a fine filter to finished good storage tanks or filling station.

[00156] Fourth aspect: Method of making the formulation according to the invention

[00157] In a fourth aspect, the invention relates to a method of making the formulation according to the invention as defined in the second aspect.

[00158] In one embodiment, the binder according to the invention is mixed with a pigment dispersion comprising a suitable pigment such as PO2, optionally in presence of a dispersing agent and/or a thickener such as an acrylic thickener. Suitable products are known in the art.

[00159] For application, this formulation may be further modified by adding a further pigment or filler such as a calcium carbonate.

[00160] Fifth aspect: Use of the binder according to the invention and use of the formulation according to the invention

[00161] In a fifth aspect the invention relates to the use of the binder according to the invention as defined in the first aspect and use of the formulation according to the invention as defined in the second aspect. In particular, this aspect relates to a method of treating a wood-containing substrate comprising at least step (S1) followed by step (S2) and (S3).

[00162] Step (S1) relates to contacting a wood-containing substrate with the formulation according to the invention; or contacting a wood-containing substrate with the formulation made according to the fourth aspect of the invention; or contacting a wood-containing substrate with the binder according to the invention; or contacting a wood-containing substrate with the binder made according third aspect of the invention.

[00163] The term “wood-containing substrate” as used within the context of the present application is to be understood as substrate comprising or consisting of wood. The term further encompasses substrates comprising or consisting of timber. The term “ timber ” as used within the context of the present application is to be understood in that timber has already been subjected to some kinds of physical or chemical treatments, such as drying procedures, sawing procedures, pressing procedures or the like. This means that the term “wood” as used within the context of the present application refers to subjects comprising or essentially consisting of cellulose and hemicelluloses, and lignin. The wood-containing substrate can comprise, in addition to wood, further components, like glue. The wood-containing substrate can be designed as solid wood or as wood- containing composite, wherein the wood-containing composite can be fiber-based, particle-based, or veneer-based. In particular, if the wood-containing substrate is designed as wood-containing composite which is fiber-based, particle-based, or veneer- based, further components such as glue can be present.

[00164] The contacting of the wood-containing substrate may be carried out by generally customary methods, such as dunking or dipping the substrate into the formulation according to the invention or the binder according to the invention, or by spraying the formulation according to the invention or the binder according to the invention onto a wood-containing substrate, or by brush application or sponge application or via a forced application or by an extraction method.

[00165] In a preferred embodiment, the wood is coated through an extruder machine. The machine is equipped with a hard steel gesso box for extruding gesso on molding.

[00166] Step (S2) relates to a heat-treatment of the wood-containing substrate obtained after step (S1), preferably at a temperature of 40 to 100 °C, or 50 to 80 °C, or 50 to 60 °C, or wherein the material is dried with the use of an oven in a temperature of 55-70 °C. [00167] Step (S3) relates to the finishing of the wood-containing substrate obtained after steps (S1) and (S2) such as a sanding process.

[00168] A wood-containing substrate treated with formulation according to the invention or the binder according to the invention has improved UV light resistance, water resistance, but at the same time a glossy and smooth finishing. With the possibility of accepting a higher amount of filler in the coating preparation, it was observed a better coverage, including hiding natural defects of wood such as knots.

[00169] Sixth aspect: Wood-containing substrate

[00170] The sixth aspect of the invention relates to a wood-containing substrate comprising at least a binder according to the invention. The sixth aspect further relates to a wood-containing substrate comprising at least a formulation according to the invention. The sixth aspect also relates to a wood-containing substrate treated by the methods according to the fifth aspect of the invention.

EXAMPLES

[00171] Example 1 : Preparation of the binder according to the invention

[00172] A pre-emulsion vessel was charged with 2200 liters of water. A solution of 45 kg sodium lauryl ether sulfate (2EO) 27 % in 90 liters water was added under stirring. Then 2,476 kg of styrene, 2,322 kg of butyl acrylate and 103 kg of methacrylic acid were added and the pre-emulsion was homogenized. Finally, 51 kg of 2-dimethylaminoethyl methacrylate and 206 kg of sodium vinyl sulfonate were added.

[00173] A reaction vessel was charged with 1.330 kg of demineralized water. To the reaction vessel 55 kg sodium lauryl ether sulfate (2EO) was added. The reactor was heated up to 73-75 °C. Subsequently, 475 kg of the pre-emulsion previously prepared were added. The temperature was adjusted to 70-72 °C. [00174] 13.7 kg of ammonium persulfate were dissolved in 340 kg of demineralized water.

[00175] The pre-emulsion and the initiator solution were metered separately but simultaneously within a time period of about 4 hours to the stirred content of the reaction vessel while the temperature was kept in a range of from 83 to 87 °C. Subsequently, it was stirred for another hour.

[00176] The reaction mixture was cooled down to 80 °C.

[00177] Subsequently, another initiator solution of 7.1 kg of ammonium persulfate in 160 liters water was added.

[00178] The reaction was cooled down to 35 °C and terminated. [00179] Finally, 31.6 kg of an epoxy silane in 90 liters water were added as well as a biocide and defoamer to adjust to the final specification. Water was added in order to adjust the solids content to about 50 % by weight, based omn the total amount of the composition. [00180] Example 2: Coating Application

[00181] A coating formulation according to the invention made with the polymer defined in Example 1 was prepared by mixing 90 % by weight binder from Example 1 with 10 % by weight of a pigment dispersion based on T1O2 such that the final composition had a solids content of 50 % by weight, based on the total amount of the suspension. The suspension was further adjusted to a solids content of 70 % by weight by admixing calcium carbonate.

[00182] The formulation was applied on wood using an appropriate equipment resulting in a coating thickness of 0.3 to 0.6 mm. After this application step, the material was dried with the use of an oven at a temperature of from 55 - 70 °C for a period of from 3 to 7 minutes. Subsequently, the coated wood was subjected to sanding.

[00183] Example 3: Immersion test

[00184] Wood coated with a commercially available wood-coating composition and wood coated with the formulation from Example 2 were immersed for a period of 10 hours in water. The wood coated with the commercially available formulation showed re emulsification, contrary to the wood coated with the formulation according to the invention.

[00185] Example 4: Water Absorption - Karsten Tube test

[00186] The Karsten Tube Penetration Test is a simple test for measuring the degree or water penetration into materials. The test consists of a glass tube filled with water, bonded to the test material with plastiline. Water pressure is then exerted on the surface. A graduated scale indicates, over time, the amount or water penetrated into the surface.

[00187] After 3 days of the coating process, a Karsten tube was placed on the substrate and the tube was filled with water. During a period of 72 h the water penetration was measured and reported. The commercial product was completely re-emulsified after 72 hours test and the product according to invention showed a water absorption of < 0,5 ml in the same period.

[00188] Example 5: QUV Test

[00189] The QUV test procedure simulates long-term outdoor exposure to sunlight, rain, and dew by exposing materials to alternating cycles of UV-A or UV-B light and moisture at controlled elevated temperatures.

[00190] These tests were carried out in a QUV equipment during 72 hours at a temperature of 60 °C. During this period, it was alternated cycles of UV-B light (4 hours) and water condensation cycles (4 hours):

[00191] In the table, L ^* indicates lightness, a ^* is the red/green coordinate, and b ^* is the yellow/blue coordinate in the CIE LAB color system.

[00192] After 72 hours in QUV test, the commercial product showed a higher level of yellowing compared to the formulation according to invention.