NEW SYSTEMS FOR PRIMING AND ADHESION OF FLOORING

Abstract

The present invention relates to a layer structure comprising primer layers based on polyacrylate primers (AG) and compositions based on silane-modified polymers (KS), and to a method of bonding floor coverings on treated bases.

Claims

1. A layer structure comprising at least one primer layer (G) obtained from a polyacrylate primer (AG), wherein the polyacrylate primer (AG) is in the form of an aqueous polymer dispersion, wherein the aqueous polymer dispersion contains water-dispersed polymer particles and is produced by free-radical polymerization of monomers comprising a) at least 50 percent by weight, based on a total amount of monomers a) to d), of at least one monomer comprising C.sub.1- to C.sub.20-alkyl acrylates, C.sub.1- to C.sub.20-alkyl methacrylates, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinylaromatics having up to 20 carbon atoms, vinyl halides, vinyl ethers of alcohols containing 1 to 10 carbon atoms, aliphatic hydrocarbons having 2 to 8 carbon atoms and one or two double bonds, or mixtures of these monomers, and b) at least 0.1 percent by weight, based on the total amount of monomers a) to d), of at least one monomer having at least one acid group or mixtures of these monomers, and c) at least 0.1 to 5 percent by weight, based on the total amount of monomers a) to d), of at least one ethylenically unsaturated compound having at least one functional group comprising a keto group or an aldehyde groups wherein the aqueous polymer dispersion, in addition to the water-dispersed polymer particles, contains at least one compound AH having at least two functional groups that can enter into a crosslinking reaction with the keto groups or with the aldehyde groups, wherein the molar ratio of the functional groups in compound AH that are reactive with keto groups or with aldehyde groups to the keto and aldehyde groups in monomer b) is 1:10 to 2:1; d) optionally further monomers and at least one curable composition based on silane-modified polymers (KS) applied to the primer layer (G), wherein the silane-modified polymers have at least one end group of the general formula (I)
-A.sub.n-R—SiVYZ   (I) in which A is a divalent binding group containing at least one heteroatom, R is a divalent hydrocarbyl radical having 1-12 carbon atoms, V, Y, Z are substituents on the silicon atom that are independently C.sub.1-C.sub.8-alkoxy or C.sub.1-C.sub.8-acyloxy groups, where at least one of the V, Y, or Z radicals is a C.sub.1-C.sub.8-alkoxy or C.sub.1-C.sub.8-acyloxy group, and n is 0 or 1.

2. The layer structure as claimed in claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG), wherein the polyacrylate primer (AG) is in the form of an aqueous polymer dispersion, wherein the aqueous polymer dispersion contains water-dispersed polymer particles and is produced by free-radical polymerization of monomers comprising a) 50 to 90 percent by weight, based on the total amount of monomers a) to d), of at least one monomer comprising methyl methacrylate, methyl acrylate, butyl acrylate, n-butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, n-hexyl acrylate, n-octyl acrylate, hexyl acrylate, octyl acrylate, benzyl (meth)acrylate, isobutyl acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, vinyl laurate, vinyl stearate, vinyl propionate, vinyl versatate, vinyl acetate, vinyltoluene, alpha- and para-methylstyrene, styrene, alpha-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, vinyl chloride, vinylidene chloride, vinyl methyl ether, vinyl isobutyl ether or mixtures of these monomers, and b) 0.5 to 5 percent by weight, based on the total amount of monomers a) to d), of at least one monomer having at least one acid group comprising alpha,beta-monoethylenically unsaturated mono- and dicarboxylic acids, monoesters of alpha,beta-monoethylenically unsaturated dicarboxylic acids, the anhydrides of the aforementioned alpha,beta-monoethylenically unsaturated carboxylic acids or ethylenically unsaturated sulfonic acids, phosphonic acids or dihydrogenphosphates, water-soluble salts thereof, or mixtures of these monomers, and c) 0.2 to 5 percent by weight, based on the total amount of monomers a) to d), of at least one ethylenically unsaturated compound having at least one functional group comprising a keto group or an aldehyde group, comprising acrolein, methacrolein, vinyl alkyl ketones having 1 to 20 carbon atoms, formylstyrene, alkyl (meth)acrylates having one or two keto or aldehyde groups, or one aldehyde and one keto group, in the alkyl radical, where the alkyl radical preferably comprises 3 to 10 carbon atoms in total, or N-oxoalkyl(meth)acrylam ides of the formula R.sub.6—C(═O)—R.sub.7—NH—C(═O)—CR.sub.8═CH.sub.2 where R.sub.6 and R.sub.8 are independently hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms, and R7 is a hydrocarbyl group having 2 to 15 carbon atoms, wherein the aqueous polymer dispersion, in addition to the water-dispersed polymer particles, contains at least one compound AH having at least two functional groups that can enter into a crosslinking reaction with the keto groups or with the aldehyde groups, comprising oxalic dihydrazide, malonic dihydrazide, succinic dihydrazide, carbodihydrazide, glutaric dihydrazide, adipic dihydrazide, sebacic dihydrazide, maleic dihydrazide, fumaric dihydrazide, itaconic dihydrazide, isophthalic dihydrazide, ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimines, partly hydrolyzed polyvinylformamides, ethylene oxide and propylene oxide adducts of amines, cyclohexanediamine, or xylylenediamine, where the molar ratio of the functional groups in compound AH that are reactive with keto groups or with aldehyde groups to the keto and aldehyde groups in monomer b) is 1:10 to 2:1, d) optionally further monomers d) having a proportion of 5 to 15 percent by weight, based on the total amount of monomers a) to d), comprising acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, phenyloxyethylglycol mono(meth)acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 2-am inoethyl (meth)acrylate, tert-butylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, vinyl, allyl or methallyl glycidyl ethers or glycidyl (meth)acrylate, butanediol di(meth)acrylate, allyl methacrylate or hydroxyalkyl (meth)acrylates having 1 to 10 carbon atoms in the alkyl group, and at least one curable composition based on silane-modified polymers (KS) applied to the primer layer (G), wherein the silane-modified polymers have at least one end group of the general formula (I) in which A is an oxygen atom or an —NR′— group in which R′ is a hydrogen atom or an alkyl or aryl radical having 1 to 12 carbon atoms, amide, carbamate, urea, imino, carboxylate, carbamoyl, amidino, carbonate, sulfonate or sulfinate group, R is a divalent hydrocarbyl radical having 1-6 carbon atoms, V, Y, Z are substituents on the silicon atom and are each independently a methyl, ethyl, methoxy or ethoxy group, where at least one of the V, Y or Z radicals is a methoxy or ethoxy group, n is 0 or 1.

3. The layer structure as claimed in claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG), wherein the polyacrylate primer (AG) has a proportion of solvents within the scope of TRGS 610, January 2011 edition, section 2.5, of less than 1%.

4. The layer structure as claimed in claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG), wherein the polyacrylate primer (AG) comprises a polyurethane dispersion having a minimum film formation temperature (measured on a film-forming bench with a temperature gradient, DIN ISO 2115:2001-04) of less than 5° C.

5. The layer structure as claimed in claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG), wherein the polyacrylate primer (AG) comprises further compounds X3Y3 that can react with reactive groups present in the aqueous polymer dispersion, comprising compounds containing carbodiimide groups (carbodiimide crosslinkers) that can react with carboxylic acid groups present in the polymer dispersion.

6. The layer structure as claimed in claim 1, wherein the primer layer (G) is obtained by storage of the aqueous layer produced using the polyacrylate primer (AG) for 1 to 72 hours.

7. A layer system comprising the layer structure of claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG) and at least one curable composition based on silane-modified polymers (KS) applied thereto.

8. A layer system comprising the layer structure of claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG) and at least one curable composition based on silane-modified polymers (KS) applied thereto, and substrate bonded thereto, for example floor covering.

9. A method of bonding floor coverings to pretreated bases using the layer structure of claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG) as pretreatment and at least one curable composition based on silane-modified polymers (KS) as adhesive.

10. The method as claimed in claim 9, wherein the polyacrylate primer (AG) is applied in one layer.

11. The method as claimed in claim 9, wherein a polyacrylate primer (AG) is first applied to a base and a floor covering is subsequently bonded to the base thus pretreated with at least one curable composition based on silane-modified polymers (KS), wherein the curable composition based on silane-modified polymers (KS) is applied between 1-72 h after the application of the polyacrylate primer.

12. A layer system comprising a base, at least one primer layer (G) obtained from a polyacrylate primer (AG), at least one curable composition based on silane-modified polymers (KS) applied thereto and floor covering bonded thereto, wherein the polyacrylate primer (AG) corresponds to one of the polyacrylate primers (AG) of claim 1, and the curable composition based on silane-modified polymers (KS) corresponds to the compositions based on silane-modified polymers (KS) of claim 1.

13. A method of sealing joins between 2 substrates using the layer structures specified in claim 1, comprising at least one primer layer (G) obtained from a polyacrylate primer (AG) as pretreatment and at least one curable composition based on silane-modified polymers (KS) as sealing compound.

14. The method as claimed in claim 13, wherein a polyacrylate primer (AG) is first applied to at least one of the two surfaces of a join formed by 2 substrates and at least one curable composition based on silane-modified polymers (KS) as sealing compound is subsequently introduced into the join, wherein the curable composition based on silane-modified polymers (KS) is introduced between 1-72 h after the application of the polyacrylate primer to the surface(s) of the join.

15. A layer system comprising 2 substrates, at least one primer layer (G1) obtained from a polyacrylate primer (AG) on a side of a first substrate that faces the a second substrate and optionally at least one primer layer (G2) obtained from a polyacrylate primer (AG) on a side of the second substrate that faces the first substrate, and at least one curable composition based on silane-modified polymers (KS) disposed between the primer layer G1 and the second substrate or primer layer G2, wherein the polyacrylate primer (AG) corresponds to one of the polyacrylate primers (AG) described in claim 1 and the curable composition based on silane-modified polymers (KS) corresponds to one of the compositions based on silane-modified polymers (KS) described in claim 1.

16. A kit of parts comprising the polyacrylate primers (AG) or primer layers (G) and the curable compositions based on silane-modified polymers (KS) specified in claim 1.

Description

EXAMPLES 1-5

[0264] The lap shear strengths were ascertained using the primers AG1-AG5 and the curable composition KS1. All primers based on dispersions from experiments V2-V4 that contain either no compound AH or no monomer c), in the case of a wait time of only 4 h prior to adhesive application, lead to inadequate bonding results and to poor bond strengths as a result. Only in the case of combination of monomer c) and compound AH) was cohesive failure of the adhesive and sufficient bond strength achieved. Moreover, no softening of the primer AG1 resulting from plasticizer migration from the adhesive into the marginal regions was observed.

TABLE-US-00002 BSP 1 BSP 2 BSP 3 BSP 4 BSP 5 Primer AG1 AG2 AG3 AG4 AG5 Failure in the lap shear test K A A A K Lap shear strength [N/mm2] 2.4 1.2 0.9 1.4 2.4 A: adhesive failure (no adhesion between primer and adhesive) K: cohesive failure (adhesion between primer and adhesive)

EXAMPLES 2-5: COMPARATIVE EXAMPLES

EXAMPLE 1a

(Inventive)

[0265] 5 g of an aqueous dispersion of a hydrophilically modified, polyfunctional carbodiimide (water content 60%, —N═C═N— content 1%, Desmodur® XP 2802, Covestro Deutschland AG) was added to 100 g of primer AG1. The mixture obtained was used as primer analogously to examples 1-5, with a wait time of 4 h in one case and of 24 h in another. In both cases, a lap shear strength of 2.5 N/mm2 with cohesive failure of the adhesive was ascertained in the lap shear test.

[0266] EXAMPLE 6

(Comparative)

[0267] By way of comparison, the experiments were repeated without application of primer to the wood. Both beechwood test specimens were thus not pretreated. Predominantly cohesive failure was observed with a lap shear strength of 3.0 N/mm2.

EXAMPLE 7

(Comparative)

[0268] Analogously to example 6, test specimens without primer that had been produced and stored in a comparable manner, in the case of bonding with a noninventive composition based on a curing polyvinylacetate dispersion with aluminum chloride metal salt crosslinker, achieved a lap shear strength of 11.75 N/mm.sup.2 (adherend failure). In the case of an analogous experiment with the inventive primer AG1 and with wait time 4 h, by contrast, only a lap shear strength of 7 N/mm.sup.2 was attained, with observation of adhesive failure.

[0269] In combination with this noninventive adhesive, the priming of the invention severely reduced the lap shear strength of the system. This was not observed in the case of the layer structure composed of primer of the invention and curing composition of the invention.

[0270] Example 7 shows that the selection of the curable composition (KS) in layer structure with the inventive primer AG is not trivial since, when the primer AG is used with a noninventive adhesive, the result is a distinct reduction in overall strength in the system compared to the unprimed system, and it is then not possible to fully exploit the performance capacity of the adhesive.

EXAMPLE 8

(Comparative)

[0271] Analogously to example 6, test specimens without primer that had been produced and stored in a comparable manner, in the case of bonding with a noninventive composition based on a curing 2K epoxy resin adhesive (Araldite 2011|50 ml twin cartridge with ZMS), achieved a lap shear strength of 13 N/mm.sup.2 (adherend failure). In the case of an analogous experiment with the inventive primer AG1 and with wait time 4 h, by contrast, only a lap shear strength of 7 N/mm.sup.2 was attained, with observation of adhesive failure.

[0272] The priming of the invention here severely reduced the lap shear strength of the system. This was not observed in the case of the layer structure composed of primer of the invention and curing composition of the invention.

[0273] Example 8 shows that the selection of the curable composition (KS) in layer structure with the inventive primer AG is not trivial since, when the primer AG is used with a noninventive adhesive, the result is a distinct reduction in overall strength in the system compared to the unprimed system, and it is then not possible to fully exploit the performance capacity of the adhesive.

EXAMPLE 9

Test of Tensile Bonding Capacity of Primer AG1, AG5 and SIKA PRIMER MR FAST

[0274] Production and Storage of the Test Specimens:

[0275] The tensile bonding capacity of primer AG1 on a previously soaked concrete slab was compared with that of priming based on SIKA PRIMER MR FAST (aqueous, two-component epoxy resin primer, from Sika).

[0276] The test specimen used was the top face of Stelcon Ferubin 30×30×3 cm hard concrete slabs, BTE Stelcon Deutschland GmbH, Philippsburger Str. 4 , 76726 Germersheim.

[0277] These were stored under standard conditions at 23 degrees Celsius and 50% relative humidity for 28 d, then the top face was brushed with 5% citric acid solution in water and, after a contact time of 20 min, freed of any adhering cement slurries with a brush under running water. Subsequently, the slab was stored in water for 7 d, taken out of the water and set upright, such that water adhering to the surface was able to run off.

[0278] AG1 was then applied to the surface of the slabs thus prepared directly after production in a Speedmixer by means of a roller (Moltopren roller) at coat weight about 200 g/m.sup.2. Thereafter, the primed slabs were stored with their reverse side on plastic sheets at 23 degrees Celsius and 50% relative humidity for 16 h.

[0279] To create a uniform layer thickness, the primed slabs were coated with a self-leveling 2-component polyurethane coating (NCO/OH index=1.05/1) based on Setathane D 1150 (castor oil-based branched polyol, from Nuplex, hydroxyl content to DIN 53 240/2 about 4.7% by weight)/Desmodur VL (aromatic polyisocyanate based on diphenylmethane diisocyanate, isocyanate group content to ISO 11909:2007 31.5%), with layer thickness about 1.5 mm. Thereafter, the slabs were again placed with their reverse side on plastic sheets for 24 h.

[0280] On one series of slabs (series A), the tensile bonding capacity test was conducted immediately thereafter. A further series (series B) is placed in a water basin by the reverse side such that the water surface runs about 1 cm below the primer and stored in this way at 23 degrees Celsius and 50% relative humidity for 28 d.

[0281] Slabs were primed and stored in an analogous manner, except that the AG1 primer was now replaced by SIKA® PRIMER MR FAST (aqueous, 2-component epoxy resin primer, from Sika), produced according to the manufacturer's instructions (mixing ratio of components A:B 2.8/1.4 parts by weight).

[0282] Ascertaining Facial Pull-Off Strength:

[0283] Facial pull-off strength was ascertained with the HP 850 adhesion test system.

[0284] 3 drill cores having a diameter of about 5 cm and depth about 5 mm were machined into the top face of the slabs produced and stored as above. The distance between the edges of the drill cores was greater than 4 cm. The bonding face was ground with abrasive paper, freed of dust and degreased with acetone. The test specimens that had been cleaned beforehand (round, diameter 50 mm) were bonded on with the 2K epoxy resin adhesive Metallon FL (Sichelwerke GmbH) in a uniform thin layer with lateral rotation, ensuring that any adhesive that swelled out did not get into the machined groove and was removed if necessary.

[0285] After storage at 23 degrees Celsius and 50% relative humidity for 24 h, facial pull-off strength was ascertained and calculated as follows:

[0286] Dimension of tear-off force=N/mm.sup.2

[0287] Area of the 50 mm die=1964 mm.sup.2

[0288] Value read off=kN

[0289] 1 kN=1000 N

[0290] Tensile bond strength=tear-off force [N]:area [mm.sup.2]

TABLE-US-00003 TABLE 8 Tensile bond strengths of the primer before and after storage SIKA ® PRIMER MR FAST Primer AG1 Series A 3.6 (fracture in 2.8 (fracture in concrete) concrete) Series B 3.1 (fracture 2.6 (fracture between between concrete concrete and primer) and primer)

[0291] As shown by table 8, the adhesive bond strength of primer AG1 is absolutely comparable to the prior art system, and is in each case well above the value of 1 N/mm.sup.2 required for elastic parquet adhesives according to DIN EN 14293.