USE OF SURFACTANT FORMULATIONS COMPRISING LONG-CHAIN ALCOHOLS IN AQUEOUS POLYURETHANE DISPERSIONS

Abstract

The use of surfactant formulations comprising long-chain alcohols as additives in aqueous polymer dispersions for production of porous polymer coatings, preferably for production of porous polyurethane coatings, is described.

Claims

1-13. (canceled)

14: A process for producing a porous polymer coating, the process comprising: a) providing a mixture comprising at least one aqueous polymer dispersion, a surfactant formulation comprising at least one interface-active foam stabilizer and at least one long-chain alcohol, and optionally, at least one further formulation component, b) foaming the mixture to give a wet foam, c) optionally, adding at least one thickener to adjust the viscosity of the wet foam, d) applying a coating of the wet foam to a suitable carrier, and e) drying the coating.

15: The process according to claim 14, wherein the at least one long-chain alcohol comprises an alcohol with the general formula (I)
R.sup.1OHFormula (I), wherein R.sup.1 is a monovalent aliphatic or aromatic, saturated or unsaturated, linear or branched hydrocarbyl radical having 12 to 40 carbon atoms.

16: The process according to claim 14, wherein the at least one long-chain alcohol is selected from the group consisting of lauryl alcohol (1-dodecanol), myristyl alcohol (1-tetradecanol), cetyl alcohol (1-hexadecanol), margaryl alcohol (1-heptadecanol), stearyl alcohol (1-octadecanol), arachidyl alcohol (1-eicosanol), behenyl alcohol (1-docosanol), lignoceryl alcohol (1-tetracosanol), ceryl alcohol (1-hexacosanol), montanyl alcohol (1-octacosanol), melissyl alcohol (1-triacontanol), palmitoleyl alcohol (cis-9-hexadecen-1-ol), oleyl alcohol (cis-9-octadecen-1-ol), elaidyl alcohol (trans-9-octadecen-1-ol), respective structural isomers of the same empirical formulae, and mixtures of these substances.

17: The process according to claim 14, wherein the at least one long-chain alcohol is selected from the group consisting of cetyl alcohol, stearyl alcohol, behenyl alcohol, and mixtures of these substances.

18: The process according to claim 14, wherein the at least one long-chain alcohol is a branched primary or secondary alcohol.

19: The process according to claim 14, wherein the at least one long-chain alcohol is a Guerbet alcohol or a branched secondary alcohol formed by paraffin oxidation by the Bashkirov method.

20: The process according to claim 14, wherein the at least one interface-active foam stabilizer and the at least one long-chain alcohol are pre-formulated.

21: The process according to claim 14, wherein the at least one interface-active foam stabilizer is selected from the group consisting of amphoteric surfactants and betaines, amidopropyl betaines, amphoacetates, anionic surfactants, alkyl or alkylaryl sulfosuccinates, sulfosuccinamates, sulfates, sulfonates, phosphates, citrates, carboxylic salts, nonionic surfactants, polyol ethers, polyol esters, and mixtures of these substances.

22: The process according to claim 14, wherein the at least one interface-active foam stabilizer is selected from the group consisting of polyol ethers, polyol esters, alkyl phosphates, alkyl citrates, and mixtures of these substances.

23: The process according to claim 14, wherein the at least one interface-active foam stabilizer is an alkyl phosphate, an alkyl citrate, or a mixture thereof.

24: The process according to claim 23, wherein the alkyl phosphate is a phosphoric ester of a long-chain alcohol having at least 12 carbon atoms; and wherein the alkyl citrate is a citric ester of a long-chain alcohol having at least 12 carbon atoms.

25: The process according to claim 23, wherein the alkyl phosphate is a phosphoric ester of a long-chain alcohol having a degree of esterification in the range of 1-2.5; and wherein the alkyl citrate is a citric ester of a long-chain alcohol having a degree of esterification in the range of 1-2.6.

26: The process according to claim 14, wherein the surfactant formulation comprises at least one further surfactant.

27: The process according to claim 26, wherein the at least one further surfactant is selected from the group consisting of fatty acid amides, ethylene oxide-propylene oxide block copolymers, amine oxides, quaternary ammonium surfactants, amphoacetates, ammonium and/or alkali metal salts of fatty acids, silicone-based surfactants, trisiloxane surfactants, polyethersiloxanes, and mixtures of these substances.

28: The process according to claim 14, wherein the at least one aqueous polymer dispersion is selected from the group consisting of polystyrene dispersions, polybutadiene dispersions, poly(meth)acrylate dispersions, polyvinyl ester dispersions, and polyurethane dispersions, and wherein a solids content of the at least one aqueous polymer dispersion is in the range of 20-70% by weight, based on an overall dispersion.

29: The process according to claim 14, wherein the at least one aqueous polymer dispersion is a polyurethane dispersion.

30: The process according to claim 29, wherein a solids content of the at least one aqueous polymer dispersion is in the range of 20-70% by weight, based on an overall dispersion.

31: The process according to claim 14, wherein a total concentration of the at least one interface-active foam stabilizer and the at least one long-chain alcohol in the mixture is in the range of 0.2-20% by weight.

32: A porous polymer coating, produced from the process according to claim 14.

Description

EXAMPLES

[0065] Substances: [0066] SYNTEGRA YS:3000: MDI (methyl diphenyl diisocyanate)-based polyurethane dispersion from DOW. As a result of the process for preparing it, the product contains 1-3% by weight of the anionic cosurfactant sodium dodecylbenzenesulfonate (CAS: 25155-30-0). [0067] IMPRANIL DLU: aliphatic polycarbonate ester-polyether-polyurethane dispersion from Covestro [0068] REGEL WX 151: aqueous polyurethane dispersion from Cromogenia [0069] CROMELASTIC PC 287 PRG: aqueous polyurethane dispersion from Cromogenia [0070] STOKAL STA: ammonium stearate (about 30% in H.sub.2O) from Bozetto [0071] STOKAL SR: tallow fat-based sodium sulfosuccinamate (about 35% in H.sub.2O) from Bozetto [0072] Sodium dodecylbenzenesulfonate (LAS; CAS: 25155-30-0) was sourced from Sigma Aldrich. This is a standard cosurfactant used for production of aqueous polyurethane dispersions. [0073] ECO Pigment Black: aqueous pigment dispersion (black) from Cromogenia. [0074] TEGOWET 250: polyethersiloxane-based levelling additive from Evonik Industries AG. [0075] ORTEGOL PV 301: polyurethane-based associative thickener from Evonik Industries AG. [0076] REGEL TH 27: isocyanate-based levelling additive from Cromogenia [0077] Polyglycerol-3 stearate: Prepared by reaction of 103.3 g of polyglycerolOHN=1124 mg [0078] KOH/g, Mw=240 g/molwith 155.0 g of technical grade stearic acid. [0079] Stearyl citrate: Foaming aid, prepared by the reaction of stearyl alcohol (95%, 275.2 g, 1.02 mol, 2.1 eq.) with citric acid (anhydrous, 93.10 g, 0.485 mol, 1.0 eq.). [0080] Stearyl phosphate: Foaming aid, prepared by the reaction of stearyl alcohol (95%, 178.7 g, 0,661 mol) with P.sub.4O.sub.10 (21.31 g, 0.0751 mol).

[0081] Viscosity Measurements:

[0082] All viscosity measurements were conducted with a Brookfield viscometer, LVTD, equipped with an LV-4 spindle, at a constant rotation speed of 12 rpm. For the viscosity measurements, the samples were transferred into a 100 ml jar into which the measurement spindle was immersed to a defined depth. The display of a constant viscometer measurement was always awaited.

Example 1: Blending of Surfactant Formulations According to the Invention

[0083] For foaming experiments, the surfactant formulations described in Table 1 were used. All surfactant formulations were homogenized at 80 C. The surfactant formulations comprising stearyl phosphate and stearyl citrate (1, 2, 4 and 5) were neutralized to pH=7 with KOH after blending. Surfactant formulations 1-3 are inventive formulations comprising a long-chain alcohol, whereas surfactant formulations 4-6 were used for comparative purposes.

TABLE-US-00001 TABLE 1 Composition of surfactant blends used hereinafter: Surfactant Surfactant Surfactant Surfactant Surfactant Surfactant 1 2 3 4 5 6 Stearyl 20.0 g 24.0 g phosphate Stearyl 20.0 g 24.0 g citrate Polyglycerol- 18.33 g 22.0 g 3 stearate Cetearyl 1.66 g 2 g sulfate Stearyl 4 g 4 g 4 g alcohol Water 76.0 g 76.0 g 76.0 g 76.0 g 76.0 g 76.0 g

Example 2: Foaming Tests

[0084] To test the efficacy of the additive combination according to the invention, a series of foaming experiments was conducted. For this purpose, in a first step, the IMPRANIL DLU polyurethane dispersion from Covestro was used. The foam stabilizers used were the inventive surfactant formulations 1-3 (see table 1) and a combination of the two surfactants Stokal STA (ammonium stearate) and Stokal SR (sodium sulfosuccinamate) as comparison. Table 2 gives an overview of the compositions of the respective experiments.

[0085] All foaming experiments were conducted manually. For this purpose, polyurethane dispersion and surfactant were first placed in a 500 ml plastic cup and homogenized with a dissolver equipped with a disperser disc (diameter=6 cm) at 1000 rpm for 3 min. For foaming of the mixtures, the shear rate was then increased to 2000 rpm, ensuring that the dissolver disc was always immersed into the dispersion to a sufficient degree that a proper vortex formed. At this speed, the mixtures were foamed to a volume of about 425 ml. The mixture was then sheared at 1000 rpm for a further 15 minutes. In this step, the dissolver disc was immersed sufficiently deeply into the mixtures that no further air was introduced into the system, but the complete volume was still in motion.

TABLE-US-00002 TABLE 2 Overview of foam formulations: #1 #2 #3 #4 IMPRANIL DLU 150 g 150 g 150 g 150 g Surfactant 1 4 g Surfactant 2 4 g Surfactant 3 4 g Stokal STA 2 g Stokal SR 2 g Wet foam viscosity [mPa s] 7100 7400 7900 4000

[0086] In all cases, fine homogeneous foams were obtained at the end of this foaming operation. It was noticeable that the foams which had been produced with inventive surfactants 1 and 2 had a higher viscosity (see Table 2). The foams were coated onto a siliconized polyester film with the aid of a film applicator (AB3220 from TQC) equipped with an applicator frame (coat thickness=800 m) and then dried at 60 C. for 5 min and at 120 C. for a further 5 min.

[0087] Compared to sample #4, the dried inventive samples #1-#3 featured a more homogeneous macroscopic appearance and a more velvety feel. In electron microscopy studies, moreover, it was possible to ascertain a finer pore structure.

Example 3: Improved Cosurfactant Compatibility

[0088] To test the cosurfactant compatibility of the surfactant formulations according to the invention, a further series of foaming experiments was conducted. For this purpose, in a first step, the SYNTEGRA YS:3000 polyurethane dispersion was used. This contains 1-3% by weight of the anionic cosurfactant sodium dodecylbenzenesulfonate (CAS: 25155-30-0). The surfactants used in these experiments were the surfactant formulations 1 and 2, and 4 and 5, listed in Table 1. Table 3 gives an overview of the composition of the foam formulations.

TABLE-US-00003 TABLE 3 Overview of foam formulations: #5 #6 #7 #8 SYNTEGRA YS 3000 150 g 150 g 150 g 150 g Surfactant 1 4 g Surfactant 2 4 g Surfactant 4 4 g Surfactant 5 4 g

[0089] On the basis of these formulations, foam coatings were produced by the method described in Example 2. It was noticeable here that samples #7 and #8 produced with comparative surfactants 4 and 5 had a much coarser and less homogeneous foam structure. After the foam coating had dried, it was also possible to observe clear cracks in the foam structure, which is a pointer to inadequate stabilization of the foam. Samples #5 and #6 produced with the inventive surfactant formulations, by contrast, again showed an extremely fine-cell and homogeneous foam structure. They were also free of drying cracks.

[0090] In addition, a further series of foaming experiments was conducted, in which the actually cosurfactant-free IMPRANIL DLU system was deliberately additized with sodium dodecylbenzenesulfonate, a common cosurfactant for PUD stabilization as already described.

[0091] Also used in these experiments were the surfactant formulations 1 and 2, and 4 and 5, listed in Table 1. Table 4 gives an overview of the composition of the foam formulations.

TABLE-US-00004 TABLE 4 Overview of foam formulations: #9 #10 #11 #12 IMPRANIL DLU 150 g 150 g 150 g 150 g Sodium 1.5 g 1.5 g 1.5 g 1.5 g dodecylbenzenesulfonate Surfactant 1 4 g Surfactant 2 4 g Surfactant 4 4 g Surfactant 5 4 g

[0092] Here too, foam coatings were produced by the method described above. It was again noticeable here that the samples #11 and #12 produced with comparative surfactants 4 and 5 had drying cracks and a much coarser cell structure, whereas the inventive samples #9 and #10 again showed a fine and homogeneous cell structure and were free of defects. Virtually no difference from the analogous, cosurfactant-free samples #1 and #2 (see Example 2) was observable here. These experiments thus demonstrate the distinct improvement in cosurfactant compatibility of the surfactant formulations according to the invention.

Example 4: Migration Tests

[0093] To assess the surface migration of the surfactants according to the invention, imitation leather materials were produced by the method that follows. First of all, a topcoat coating was applied to a siliconized polyester film (layer thickness 100 m). This was then dried at 100 C. for 3 minutes. Subsequently, a foam layer was coated onto the dried topcoat layer (layer thickness 800 m) and dried at 60 C. for 5 minutes and at 120 C. for 5 minutes. In a last step, an aqueous adhesive layer (layer thickness 100 m) was coated onto the dried foam layer, and then a textile carrier was laminated onto the still-moist adhesive layer. The finished laminate was dried again at 120 C. for 5 minutes and then detached from the polyester film.

[0094] All coating and drying operations were performed here with a Labcoater LIFE-S from Mathis AG. Topcoat and adhesive layer were formulated here in accordance with the compositions listed in Table 5; the foam layers used were the foam formulations listed in Table 2, which were foamed by the method described in Example 2.

[0095] For assessment of surfactant migration, the imitation leather samples, after production, were placed into water at 100 C. for 30 minutes and then dried at room temperature overnight. After this treatment, the comparative sample produced from the Stokal STA/SR surfactants (foam formulation #4, Table 2) had distinctly visible white spots on the surface of the imitation leather, whereas this surface discoloration was not observed in the case of the samples produced with the surfactants according to the invention (foam formulation #1, #2 and #3, Table 2).

TABLE-US-00005 TABLE 5 Topcoat and adhesive formulation for production of imitation leather materials: Topcoat Adhesive CROMELASTIC PC 287 100 g PRG REGEL WX 151 100 g ECO Pigment Black 10 g 5 g TEGOWET 250 0.2 g 0.2 g REGEL TH 27 6 g 6 g ORTEGOL PV 301 7 g 5 g

Example 5: Improved Foaming Rate

[0096] The foaming rate was assessed by conducting a last series of foaming experiments with Impranil DLU, a PU dispersion. For this purpose, the two surfactant mixtures 3 and 6 (Table 1) were used. Table 6 gives an overview of the composition of the foam formulations.

TABLE-US-00006 TABLE 6 Overview of foam formulations: #13 #14 IMPRANIL DLU 150 g 150 g Surfactant 3 4 g Surfactant 6 4 g Time until a foam volume 2 min 20 sec 5 min 35 sec of 425 ml was attained

[0097] The foam formulations were foamed by the method described in Example 2, but with the difference that the foaming operation was conducted at a reduced speed of 1200 rpm. It was observed here that the foam formulation containing the inventive surfactant blend 3 (experiment #13) attained the target volume of 425 ml much more quickly than the comparative sample #14 comprising the inventive surfactant 6. In both cases, fine-cell foams were obtained at the end of the foaming operation. These were coated onto a release paper in a last step after the method described in Example 2, and dried. In both cases, it was possible here to obtain homogeneous foam coatings that had no drying defects at all after drying. The reduced foaming time achieved by means of the surfactant blend according to the invention consequently had no adverse effect at all on the quality of the foam obtained.