METHOD OF APPLYING A TOP LAYER OF A FLOOR

The present invention relates to a method of applying a top layer of a floor using a levelling compound comprising an inorganic binder, a flow agent, and a colourant wherein the levelling compound is mixed with water to form a slurry which is subsequently applied to form a levelled layer.

Levelling compounds are free-flowing compounds based on inorganic binders, such as calcium sulfate or cement. Commercially available in powder form, these products are mixed with water to form a slurry which is usually poured or pumped onto a floor, where it levels out and hardens to form a smooth levelled floor surface.

EP 0 884 291 A1 discloses the use of a pigmented levelling compound to form a top layer of a floor which does not need to be covered further. To obtain sufficient mechanical strength and wear resistance, such pigmented levelling compounds are based on cementitious binder systems. Such cementitious systems have a relatively high shrinkage and are susceptible to crack formation.

Levelling compounds based on calcium sulfate, e.g. as disclosed in DE 101 59 337 A, can be used to form lightweight constructions. However, these calcium sulfate based levelling compounds are typically used for layers supporting floor coverings, such as textile carpeting, PVC carpeting, linoleum or parquet.

WO 96/24561 discloses fly ash based compounds which may optionally comprise hydratable gypsum. The use of a pigment is also mentioned. The mixtures are used to make floor underlayments, which serve to carry further floor coverings. The fly ash is used to improve quick setting and high early compressive strength, which is required for use as a floor underlayment, since

further layers must be applied on it. The gypsum content of the binder system is below 90 %.

WO 03/082766 discloses flooring compounds based on beta calcined calcium sulfate, optionally comprising colourants. The compounds are used for subfloors and floor underlayments.

It is the object of the invention to provide a method for applying a top layer of a floor without shrink effects or crack formation and with good mechanical properties, allowing direct use as a top floor layer without additional floor covering.

The object of the invention is achieved by a method of applying a top layer of a floor using a levelling compound comprising an inorganic binder, a flow agent, and a colourant, wherein the levelling compound is mixed with water to form a slurry which is subsequently applied to form a levelled layer, characterized in that a binder with a calcium sulfate content of at least 90 % by weight is used and in that a transparent top coat is applied on the levelled layer using a coating composition comprising an organic binder.

Contrary to expectation, it was found that pigments still allow the formulation of compounds with a high calcium sulfate content and a sufficient self-levelling flow. The floors obtained with the levelling compounds according to the invention can be homogeneously coloured and can be used directly without further floor covering.

The top floor is finished by applying a transparent top coat comprising an organic binder on the cured layer of the levelling compound. Such a transparent top coat can for example be made using a transparent oil finishing, a transparent wax finishing, a reaction resin based transparent finishing, e.g. epoxy resin or polyurethane resin, transparent alkyd lacquers, or a dispersion

based film-forming finishing. Suitable polyurethane resins are for example aqueous dispersions of polyurethanes, for instance based on a carbonyl - hydrazine crosslinking system, such as Neopac® E125 available from DSM Neoresins. Water or solvent borne oxidatively drying fatty acid modified polyurethanes can also be used. Suitable oil finishings can for example be based on linseed oil or tung oil. A suitable transparent top coat can for example be prepared by using HP-oil in combination with HP Hartwachs, both of IRSA, Germany. A commercially available suitable epxoxy system is EP 700 E of KLB Kδtztal. Suitable examples of aqueous two component polyurethane systems are Coelan® 2K PU and Altramex® 7600 Polytec.

The amount of water to be mixed with the dry levelling compound generally is in the order of 10 - 40 wt.%, e.g., between 20 and 32 wt.%. These amounts of water are not sufficient to reduce the viscosity sufficiently to obtain a self- levelling compound. Therefore, flow agents are used. Generally, these flow agents are polymeric resins used in concentrations of up to about 5 wt.%, e.g., about 0.05 - about 2 wt.% of the dry composition of the levelling compound. Suitable examples of flow agents are melamine formaline sulfonates, lignine sulfonates, beta naphthalene sulfonic acid aldehyde condensation products, polyalkylallyl sulfonates, casein, polycarboxylates, acrylic copolymers, alkylnaphthalene sulfonates, and alkylnaphthalene sulfonic acid formaline condensation product salts.

In order to prevent bleeding of water and aggregate separation, one or more thickeners can be used. Suitable examples of thickeners are cellulose ethers such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, ethylhydroxy- methyl cellulose, ethylhydroxyethyl cellulose, and carboxymethyl cellulose, polyacrylamide polyethylene oxide, polyvinyl alcohol, casein, starch ether, sulfonic organic polymers, xanthan gum, guar gum or polysaccharide. The amount of thickener generally is below 5 wt.%, e.g., between 0.01 and 1.0 wt.% of the dry composition.

Addtionally, use can be made of one or more defoamers, which can for instance be based on a polyol, a glycol, a fatty acid ester, silicones, siloxanes, ethylene oxide or propylene oxide, alkoxy polymers or mineral oils. The amount of defoamer generally is below 1 wt.%, e.g. between 0.05 - 0.8 wt.% of the dry composition.

The used colourant can be a dye or an organic or inorganic pigment or mixtures of organic and/or inorganic pigments and/or dyes. Effect pigments, such as metallic or pearlescent pigments or colour shift pigments, can also be used. The pigments can for example be in the powder or granular form or in the liquid or paste form.

The pigment content in the levelling compound is within the following range: 0.01 - 10 wt.% of the dry levelling compound, preferably 0.1 - 2 wt.% of the dry levelling compound.

Suitable organic colour pigments are for example monoazo pigments: C.I Pigment Brown 25; C.I. Pigment Orange 5, 13, 36, 38, 64, and 67; C.I. Pigment Red 1 , 2, 3, 4, 5, 8, 9, 12, 17, 22, 23, 31 , 48:1 , 48:2, 48:3, 48:4, 49, 49:1 , 51 :1 , 52:1 , 52:2, 53, 53:1 , 53:3, 57:1 , 58:2, 58:4, 63, 112, 146, 148, 170, 175, 184, 185, 187, 191 :1 , 208, 210, 245, 247, and 251 ; C.I. Pigment Yellow 1 , 3, 62, 65, 73, 74, 97, 120, 151 , 154, 168, 181 , 183, and 191 ; C.I. Pigment Violet 32; disazo pigments: C.I. Pigment Orange 16, 34, 44, and 72; C.I. Pigment Yellow 12, 13, 14, 16, 17, 81 , 83, 106, 113, 126, 127, 155, 174, 176, and 188; disazo condensation C.I. Pigment Yellow 93, 95, and 128; further pigments: C.I. Pigment Red 144, 166, 214, 220, 221 , 242, and 262; C.I. Pigment Brown 23 and 41 ; anthanthrone pigments: C.I. Pigment Red 168; anthraquinone pigments: C.I. Pigment Yellow 147, 177, and 199; C.I. Pigment Violet 31 ; anthrapyrimidine pigments: C.I. Pigment Yellow 108; quinacridone pigments: C.I. Pigment Orange 48 and 49; C.I. Pigment Red 122, 202, 206, and 209; C.I.

Pigment Violet 19; quinophthalone pigments: C.I. Pigment Yellow 138; diketopyrrolopyrrole pigments: C.I. Pigment Orange 71 , 73, and 81 ; C.I. Pigment Red 254, 255, 264, 270, and 272; dioxazine pigments: C.I. Pigment Violet 23 and 37; C.I. Pigment Blue 80; flavanthrone pigments: C.I. Pigment Yellow 24; indanthrone pigments: C.I. Pigment Blue 60 and 64; isoindoline pigments: C.I. Pigments Orange 61 and 69; C.I. Pigment Red 260; C.I. Pigment Yellow 139 and 185; isoindolinone pigments: C.I. Pigment Yellow 109, 110, and 173; isoviolanthrone pigments: C.I. Pigment Violet 31 ; metal complex pigments: C.I. Pigment Red 257; C.I. Pigment Yellow 117, 129, 150, 153, and 177; C.I. Pigment Green 8; perinone pigments: C.I. Pigment Orange 43; C.I. Pigment Red 194; perylene pigments: C.I. Pigment Black 31 and 32; C.I. Pigment Red 123, 149, 178, 179, 190, and 224; C.I. Pigment Violet 29; phthalocyanine pigments: C.I. Pigment Blue 15, 15:1 , 15:2, 15:3, 15:4,15:6, and 16; C.I. Pigment Green 7 and 36; pyranthrone pigments: C.I. Pigment Orange 51 ; C.I. Pigment Red 216; pyrazolo quinazolone pigments: C.I. Pigment Orange 67; C.I. Pigment Red 251 ; thioindigo pigments: C.I. Pigment Red 88 and 181 ; C.I. Pigment Violet 38; tharylcarbonium pigments: C.I. Pigment Blue 1 , 61 and 62; C.I. Pigment Green 1 ; C.I. Pigment Red 81 , 81 :1 , and 169; C.I. Pigment Violet 1 , 2, 3, and 27; C.I. Pigment Black 1 (aniline black); C.I. Pigment Yellow 101 (aldazine yellow); C.I. Pigment Brown 22.

Examples of suitable inorganic colour pigments are: white pigments: titanium dioxide (C.I. Pigment White 6), zinc white, pigment grade zinc oxide; zinc sulfide, lithopone; black pigments: iron oxide black (C.I. Pigment Black 11 ), iron manganese black, spinel black (C.I. Pigment Black 27); carbon black (C.I. Pigment Black 7); chromatic pigments: chromium oxide, chromium oxide hydrate green; chrome green (C.I. Pigment Green 48); cobalt green (C.I. Pigment Green 50); ultramarine green; cobalt blue (C.I. Pigment Blue 28 and 36; C.I. Pigment Blue 72); ultramarine blue; manganese blue; ultramarine violet; cobalt violet; manganese violet; red iron oxide (C.I. Pigment Red 101 ); cadmium sulfoselenide (C.I. Pigment Red 108); cerium sulfide (C.I. Pigment

Red 265); molybdate red (C.I. Pigment Red 104); ultramarine red; brown iron oxide (C.I. Pigment Brown 6 and 7), mixed brown, spinel phases and corundum phases (C.I. Pigment Brown 29, 31 , 33, 34, 35, 37, 39, and 40), chromium titanium yellow (C.I. Pigment Brown 24), chrome orange; cerium sulfide (C.I. Pigment Orange 75); yellow iron oxide (C.I. Pigment Yellow 42); nickel titanium yellow (C.I. Pigment Yellow 53; C.I. Pigment Yellow 157, 158, 159, 160, 161 , 162, 163, 164, and 189); chromium titanium yellow; spinel phases (C.I. Pigment Yellow 119); cadmium sulfide and cadmium zinc sulfide (C.I. Pigment Yellow 37 and 35); chrome yellow (C.I. Pigment Yellow 34); bismuth vanadate (C.I. Pigment Yellow 184).

To obtain a good distribution of the colourants, the colourant can be a pigment which is pre-treated with at least one dispersant and optionally a surfactant.

Pigment concentrates in powder form are for instance disclosed in WO 03/064540, WO 03/066743, and WO 04/000903. Preferably, these pre-treated pigments are used in finely divided powder form or the granular form, for instance having average particle sizes from 0.1 to 5 micrometers. Generally, such easily dispersible pigment powders are referred to as "stir-in" pigments. Suitable commercially available stir-in pigments are for example X-Fast black 0066 (colour index pigment black 7/77266): Carbon black, X-Fast yellow: Arylid yellow and other X-Fast types.

Such pre-treated pigments can for example be coated with at least one nonionic surface-active additive based on polyethers. Especially polyethylene oxides and polypropylene oxides are useful. These can be obtained by the polyaddition of said alkylene oxides to saturated or unsaturated aliphatic and aromatic alcohols and aliphatic amines, in which case they are reacted with ethylene oxide first and then with propylene oxide or with propylene oxide first and then with ethylene oxide. Suitable aliphatic alcohols generally contain from 6 to 26 carbon atoms, preferably from 8 to 18 carbon atoms. Examples are octanol, nonanol,

decanol, isodecanol, undecanol, dodecanol, 2-butyloctanol, tridecanol, isotridecanol, tetradecanol, pentadecanol, hexadecanol, 2- hexyldecanol, heptadecanol, octadecanol, 2-heptylundecanol, 2-octyldecanol, 2- nonyltridecanol, 2-decyltetradecanol, oleyl alcohol, and 9-octadecenol, and also mixtures of these alcohols such as C13/C15 and C16/C18 alcohols. Of particular interest are the fatty alcohols obtained from natural raw materials by fat hydrolysis and reduction and the synthetic fatty alcohols from the oxo process. The alkylene oxide adducts with these alcohols typically have average molecular weights Mn from 400 to 2,000. Useful examples of aromatic alcohols are naphthol and C1-C4-alkyl derivatives thereof, in particular phenol and its C1-C12-alkyl derivatives, such as hexyl phenol, heptyl phenol, octyl phenol, nonyl phenol, isononyl phenol, undecyl phenol, dodecyl phenol, di- and tributyl phenol, and dinonyl phenol. Useful aliphatic amines correspond to the above- mentioned aliphatic alcohols. Alkylene oxide adducts with at least bifunctional amines and alcohols are particularly useful. The at least bifunctional amines preferably have from two to five amine groups and conform in particular to the formula H2N-(R-NR1 )n-H (R: C2-C6-alkylene; R1 : hydrogen or C1-C6-alkyl; n: 1-5). Specific examples are ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, 1 ,3-propylene diamine, dipropylene triamine, 3-amino-1-ethyleneaminopropane, hexamethylene diamine, dihexamethylene triamine, 1 ,6-bis(3-aminopropylamino) hexane, and N- methyldipropylene triamine, of which hexamethylene diamine and diethylene triamine are more preferred and ethylene diamine is most preferred. These amines are preferably reacted first with propylene oxide and then with ethylene oxide. The ethylene oxide content of the block copolymers typically is about 10- 90 wt. %. The block copolymers based on polyamines generally have average molecular weights Mn from 1 ,000 to 40,000 and preferably from 1 ,500 to 30,000. The at least bifunctional alcohols preferably have from two to five hydroxyl groups. Examples are C2-C6- alkylene glycols and the corresponding di- and polyalkylene glycols, such as ethylene glycol, 1 ,2-propylene glycol, 1 ,3- propylene glycol, 1 ,2-butylene glycol, 1 ,4-butylene glycol, 1 ,6-hexylene glycol,

dipropylene glycol, and polyethylene glycol, glycerol, and pentaerythritol, of which ethylene glycol and polyethylene glycol are more preferred and propylene glycol and dipropylene glycol are most preferred. Particularly preferred alkylene oxide adducts with at least bifunctional alcohols have a central polypropylene oxide block, i.e. are based on a propylene glycol or polypropylene glycol which is initially reacted with further propylene oxide and then with ethylene oxide. The ethylene oxide content of the block copolymers typically is in the range of from 10 to 90 wt. %. The block copolymers based on polyhydric alcohols generally have average molecular weights Mn from 1 ,000 to 20,000 and preferably from 1 ,000 to 15,000.

The pigment granules can for example comprise 60 to 90 wt.%, preferably from 70 to 85 wt.% of pigments and from 10 to 40% of the dispersants. They are advantageously obtainable by wet-comminuting the pigment in aqueous suspension in the presence of some or all of the nonionic dispersant and then spray-granulating the suspension.

The levelling compound can also comprise a polymeric dispersion powder, such as spray-dried dispersion powders of homopolymers or copolymers of vinyl acetate, vinyl versatate, and/or vinyl laurate. Commercially available examples of such dispersion powders are Vinnapas RE 523Z and Vinnapas RE 5011 L of Wacker and FL 2201 , FL 2211 , and FL 3200 and LDM 2021 P and DM 1140P of Elotex, and PAV 333 of Rhodia. The amount of polymeric dispersion powder generally is between 0.1 - 12 wt.%, e.g. between 0.4 - 8 wt.%, of the dry composition.

Optionally, the levelling compound may comprise up to 9 wt.% of cement, for instance aluminous cement or Portland cement or mixtures.

Optionally, at least a part of the calcium sulfate is alpha hemihydrate calcium sulfate. Additionally, the calcium sulfate can comprise beta hemihydrate calcium

sulfate, calcium sulfate dihydrate, and/or calcium sulfate anhydrite, such as anhydrite II. Additionally, calcium sulfate types such as phosphogypsum and/or fluorogypsum can also be used. Preferably, the calcium sulfate of the levelling compound comprises an alpha hemihydrate calcium sulfate content of at least 70 wt.% of the dry calcium sulfate, e.g. at least 95 wt.%.

If so desired, the levelling compound may also comprise fibres, for instance multifilic or monofilic fibres. Suitable fibres are for example polyacrylonitrile fibres, polyamide fibres, polyester fibres, polyimide fibres, carbon fibres or glass fibres.

The levelling compound can also comprise fillers, such as calcium carbonate fillers or quartz sand. The filler content may be as high as 80 wt.% of the dry compound, if so desired.

Such levelling compounds can be applied upon a substrate. The levelling compound is mixed with a pigment and with water to form a slurry, which is subsequently applied on the substrate to form a levelled layer, cured by hydration reaction of the calcium sulfate. The pigments are added to the dry compound, which is subsequently mixed with water or, alternatively, the pigments are added to the water, which is subsequently mixed with the levelling compound.

The invention is further illustrated by the following examples.

Examples

For comparison purposes, cement based floor levelling compounds were prepared as shown in Table 1.

Table 1 - Reference examples

Five examples were prepared based on calcium sulfate alpha hemihydrate, as shown in Table 2

Table 2

The compounds were mixed with 24 wt.% water, calculated on the dry composition. The levelling behaviour was tested on a PE foil with the flow diameter test according to DIN EN 12706 using a cylinder of 203 ml. The gel time was measured on the fresh mortar, which was spread on a PE foil. The slurries were applied in a 10 ^* 40 ^* 160 mm steel mould and after 28 days the cured prisms were tested for shrinkage (pr EN 13872). Further, the slurries were applied in a 40 ^* 40 ^* 160 mm steel mould and after 28 days the cured prisms were tested for flexural strength and compression strength (pr EN 13851 ) and abrasion (DIN EN 12808-2). The tensile adhesion strength on a

concrete slab was tested after three days (pr EN 13408). The tests were carried out as shown in Table 3, together with the results.

Table 3

Storage

Parameter time unit Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5

Shrinkage 28 d mm/m 0.2 0.2 0.2 0.1 0.2

Flexural Strength 28 d N/mm ² 10 12 13 13 14

Compressive Strength 28 d N/mm ² 39 42 44 43 46

Abrasion 28 d mm ³ 490 310 340 300 370

Tensile Adhesion Strength (on concrete slab) 3 d N/mm ² 1.6 2.1 2.2 1.9 2.0

Flow Diameter cm 24 32 32 32 32

Gel Time min 5 25 24 25 28

Cement based Reference examples 1 and 2 gave high shrinkage, resulting in high risk of cracks. As can be seen in Table 3, Examples 2 - 5, which used stir- in pigments (XFast®), gave improved application properties and longer working times. All Examples were perfect in terms of low shrinkage, high mechanical performance, and final homogenous optical aspects.

The application of the top coat was done after curing of the levelled layer. The top coating was done in 2 layers. The first layer was applied 18 hours after levelling. The following top coats were used:

1. High Performace Oil (HP oil) from lsra in combination with high performace wax (HP wax)

2. Polytec 2-K PU (water based) from Avendris

3. Epoxy finish (water based) from KLB Kδtztal 4. 2-K PU (water based) from Coelan

The top coats were applied with a metal trowel or with a roller. The second layer was applied four hours after the first layer.

Twelve days after the application of the second top coat layers, the abrasion resistance was very good. Particularly the two component systems showed very good resistance against penetration of liquid such as coffee. No penetration was observed after 12 hours.