HK1116819A - Aqueous coating compositions based on polyurethane dispersions - Google Patents

Description

Aqueous coating composition based on polyurethane dispersions

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from german application DE 102006046650.0 filed on 29/9/2006 according to 35u.s.c. § 119(a) - (d).

Technical Field

The invention relates to water-dilutable, hydroxy-functional polyurethanes containing amide structural units, to a process for their preparation, to aqueous coating compositions prepared from the polyurethanes, and to their use for coating substrates.

Background

In recent years, in the passenger car industry, plastics have been increasingly used in interior decoration for weight reduction. Because of aesthetic and technical requirements, plastic parts in automobiles usually require coatings in order to protect the plastic from external influences, such as sunlight and chemicals, thermal radiation and mechanical contact, in order to obtain a certain chromaticity and color effect, in order to mask defects of the plastic surface, or in order to produce a pleasant feel (touch) to the plastic surface. In order to improve the tactile properties of plastic parts for automobile interiors, so-called soft-feel paints have been increasingly used in recent years. For purposes of the present invention, a "soft feel effect" refers to a particular tactile sensation (feel) that the coated surface has. Such a tactile sensation may be described using words such as "velvet-like", "soft", "rubber-like" and "warm", however, for example, painted automobile body surfaces or unpainted polymeric sheets or plexiglas or similar sheets or plexiglas coated with conventional clear or top coat coatings feel cool and smooth.

For example, aqueous soft-feel coatings based on polyurethane chemistry are disclosed in EP-A0669352. These coatings not only have an excellent soft feel effect, but also produce coatings with high stability and protective effect on plastic substrates.

The requirements imposed on soft-feel coatings for automotive interior parts during the intervening period, in particular in terms of resistance to creams for skin protection and skin care (e.g. sun creams or lotions), have increased to such an extent that they are not at all possible with the coatings of the prior art, or can only be achieved with a reduced soft-feel effect.

There is still a need to find aqueous coating compositions which have good resistance, in particular to creams for skin protection and skin care, and at the same time have outstanding soft-feel effects.

Surprisingly, it has now been found that water-dilutable, hydroxyl-functional polyurethanes which comprise amide structural units are suitable for producing coatings having the following properties: has excellent tolerance to cream (such as sunscreen cream or sunscreen lotion) for skin protection and skin care, and simultaneously has outstanding soft feeling effect.

U.S. Pat. No. 3, 5780559 discloses film-forming polyurethanes which contain terminal amide groups and can be crosslinked using melamine resins. The acid resistance and hardness of the coating are very high. However, the polyurethane disclosed in this patent is not suitable for use in aqueous systems. Furthermore, the described film-forming polymers are not suitable for use in automotive interior parts, since the temperatures required for this crosslinking cannot be used for the plastics which are customarily used in automotive interior parts.

U.S. Pat. No. 3, 2002/0068789 discloses aqueous dispersions of polyurethanes containing amide groups, but the dispersions likewise do not have the structure according to the invention. The dispersion is capable of reacting with a cross-linking agent that is reactive with amide groups. One-component, heat-curable systems are obtained which can be used in particular as OEM coatings in the passenger car industry.

It is therefore an object of the present invention to provide a suitable polyurethane component which, when combined with an isocyanate crosslinker, produces a coating composition having a soft-feel effect, while being particularly resistant to creams used for skin protection and skin care, in particular sunscreen creams.

This object is achieved by the water-dilutable polyurethanes according to the invention.

Disclosure of Invention

The present invention provides water-dilutable, hydroxyl-functional polyurethanes comprising structural units of the general formula (I):

wherein the content of the first and second substances,

R₁is an aliphatic or cycloaliphatic radical having from 2 to 18 carbon atoms,

R₂is an aliphatic group having 3 to 5 carbon atoms.

Detailed Description

The polyurethanes of the invention have an amide group content, calculated as (CO) NH, of from 2.0 to 20% by weight, preferably from 2.0 to 15% by weight, more preferably from 3.0 to 10% by weight.

Preferred water-dilutable, hydroxyl-functional polyurethanes contain as synthesis components:

A1)25 to 80 wt.%, preferably 30 to 60 wt.%, of at least one amide group-containing polyol, molecular weight M_nIs the temperature of 314-,

A2)0 to 60% by weight, preferably 10 to 50% by weight, of at least one polyol selected from polyesters, polycarbonates or polyethers, having a number average molecular weight M_nIs 400-6000Da,

A3)0 to 20 wt.%, preferably 1 to 15 wt.%, of at least one low molecular weight polyol having at least two hydroxyl groups, a number average molecular weight of 62 to 400Da,

A4) from 2 to 10% by weight, preferably from 3 to 8% by weight, of at least one compound having at least two groups reactive toward isocyanate groups and at least one group capable of anion formation,

A5) from 5% to 50% by weight, preferably from 8% to 30% by weight, of one or more polyisocyanates,

the sum of components A1) to A5) is 100%.

Examples of amide group-containing polyols which are suitable as component A1) are polyester polyols which are synthesized from diols, (if appropriate) triols and tetraols and dicarboxylic acids, (if appropriate) tricarboxylic acids and tetracarboxylic acids or hydroxycarboxylic acids or lactones. In order to prepare the polyester polyols, it is also possible to use the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols in place of the free polycarboxylic acids.

Examples of suitable diols are ethylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, butane-1, 3-diol, butane-1, 4-diol, hexane-1, 6-diol and isomers, neopentyl glycol, preference being given to the last three compounds mentioned. Examples of polyols which may also be used here if appropriate are trimethylolpropane, glycerol, erythritol, pentaerythritol or trishydroxyethyl isocyanate.

Examples of suitable dicarboxylic acids include: phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid and possible anhydrides thereof. Thus, for the purposes of the present invention, anhydrides are included in the expression "acid". Monocarboxylic acids, such as benzoic acid and caproic acid, may also be used, provided that the average OH functionality of the polyol is ≧ 2. Preference is given to saturated fatty acids or aromatic acids, such as adipic acid, phthalic acid, hexahydro-and tetrahydrophthalic acid or isophthalic acid. Relatively small amounts of polycarboxylic acids, such as trimellitic acid, can be used if appropriate.

Examples of hydroxycarboxylic acids having terminal hydroxyl groups which can be used as coreactants in the preparation of the polyester polyols are hydroxycaproic acid and hydroxybutyric acid. Suitable lactones are, for example, caprolactone, butyrolactone, and homologs thereof.

However, it is essential to the invention that one or more polyol components containing amide groups be used in the preparation of the polyurethanes of the invention. Suitable amide group-containing polyols can be obtained by reacting polyamines with lactones. Preferred polyamines are aliphatic diamines, such as ethylenediamine, 1, 6-hexamethylenediamine, 2-methyl-1, 5-diaminopentane (Dytek)^®A, DuPont/Bad Homburg), isomers of 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), piperazine, 1, 4-diaminocyclohexane or bis (4-aminocyclohexyl) methane, and mixtures thereof, and Laromin ® C260(4, 4 '-diamino-3, 3' -dimethylcyclohexylmethane, BASFAG, germany). Suitable lactones are all lactones, in particular epsilon-caprolactone, which are obtainable on an industrial scale.

The polyurethane of the present invention preferably comprises the reaction product of a compound selected from the group consisting of: 1, 6-hexanediamine, 2-methyl-1, 5-diaminopentane, 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), isomers of bis (4-aminocyclohexyl) methane, and mixtures thereof. Typically in this case at least 1, preferably 1-5, more preferably 1 epsilon caprolactone molecule is added per amine group of the amine.

The reaction products of the diamines described later with epsilon-caprolactone, which do not require further reaction, can be used directly as synthesis component A1).

In another preferred embodiment, an amide group-containing polyol component may be used as a synthesis component for forming the amide group-containing polyester polyol suitable for component a 1).

Component A1) comprises structural units of the general formula (I), the amide groups of which areThe content is at least 7.5% by weight, preferably at least 9% by weight, calculated as (CO) NH. Number average molecular weight M of amide group-containing polyol A1)_nIs 314-.

Number average molecular weights M of the polyester polyols which can be used as component A2)_nIs 400-6000Da, preferably 600-3000Da, more preferably 1500-2200 Da; they have a hydroxyl number of from 20 to 400 mg KOH/g, preferably from 50 to 200 mg KOH/g, more preferably from 80 to 160 mg KOH/g, and an OH functionality of from 1.5 to 3.5, preferably from 1.8 to 2.7, more preferably from 1.95 to 2.5.

Very suitable examples are the customary polycondensation products of diols, if appropriate polyols and diacids, if appropriate polycarboxylic acids or hydroxycarboxylic acids or lactones, as already mentioned under A1).

Also suitable as polyol components are homopolymers or copolymers of lactones, preferably obtained by addition reaction of lactones or lactone mixtures (e.g. γ -butyrolactone,. epsilon. -caprolactone and/or methyl-. epsilon. -caprolactone) with suitable starter molecules having a functionality of equal to or greater than 2 (e.g. the low molecular weight polyols mentioned in the synthesis components of the polyester polyols mentioned above).

Also suitable as component A2) are hydroxyl-containing polycarbonates, obtainable, for example, by reacting carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate, diethyl carbonate or phosgene with polyhydric alcohols, preferably diols. Suitable such diols include, for example, butane-1, 4-diol and hexane-1, 6-diol, as well as lactone-modified diols. Particularly preferred as component A2) are polycarbonate polyols having a hydroxyl number of from 20 to 172 mg KOH/g, more preferably from 28 to 112 mg KOH/g, and an average functionality of from 1.6 to 3, preferably from 1.9 to 2.3, more preferably from 1.95 to 2.

The low molecular weight polyols a3) used for the synthesis of polyurethane resins generally have the effect of hardening and/or branching the polymer chains and generally have a number average molecular weight of between 62 and 400Da, preferably between 62 and 200 Da. Suitable polyols may contain aliphatic, cycloaliphatic or aromatic groups. Low molecular weight polyols having up to about 20 carbon atoms per molecule which may be mentioned are, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 3-butanediol, cyclohexanediol, 1, 4-cyclohexanedimethanol, 1, 6-hexanediol, hydroquinone dihydroxyethyl ether, bisphenol A (2, 2-bis (4-hydroxyphenyl) propane), hydrogenated bisphenol A (2, 2-bis (4-hydroxycyclohexyl) propane) and mixtures thereof, and trimethylolpropane, glycerol or pentaerythritol. It is also possible to use ester diols, such as delta-hydroxybutyl-epsilon-hydroxyhexanoate, omega-hydroxyhexyl-gamma-hydroxybutyrate, beta-hydroxyethyladipate or di (beta-hydroxyethyl) terephthalate, alpha-hydroxy-n-hydroxy-hexanoate, alpha-hydroxy-n-hydroxyhexanoate, alpha-hydroxyhexyl-gamma-hydroxybutyrate, alpha-hydroxy-ethyl-adipate or alpha-hydroxy-n-hydroxy-ethyl-terephthalate,

Ionic or potentially ionic compounds suitable as component a4) are, for example, dihydroxycarboxylic acids, diaminocarboxylic acids, dihydroxysulfonic acids, diaminosulfonic acids and their salts, such as 2- (2-aminoethylamino) ethanesulfonic acid, ethylenediamine-propyl-or-butylsulfonic acid, 1, 2-or 1, 3-propylenediamine- β -ethanesulfonic acid, 3, 5-diaminobenzoic acid and the hydrophilic agents from example 1 of EP-a 0916647, and their alkali metal salts and/or ammonium salts; adducts of sodium bisulfite and but-2-ene-1, 4-diol, 2-butenediol and NaHSO₃As hydrophilic synthesis component(s) (for example as described in DE-A2446440 (pages 5 to 9, formulae 1 to 111)). Preferred ionic or potentially ionic compounds A4) are those having carboxylic acid or carboxylate groups. Preferred ionic compounds A4) are dihydroxycarboxylic acids, in particular alpha, alpha-dimethylolalkanoic acids, such as 2, 2-dimethylolacetic acid, 2-dimethylolpropionic acid, 2-dimethylolbutyric acid, 2-dimethylolpentanoic acid or dihydroxysuccinic acid. Particularly preferred are 2, 2-dimethylolpropionic acid and 2, 2-dimethylolbutyric acid.

Suitable polyisocyanates of component A5) are the aromatic, araliphatic, aliphatic or cycloaliphatic polyisocyanates known to the person skilled in the art, which preferably have an isocyanate functionality of > 2 and may also contain iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, urea, oxadiazinetrione, oxazolidinone, acylurea and/or carbodiimide structures. These polyisocyanates can be used individually or in any desired mixtures with one another.

Examples of suitable polyisocyanates are 1, 6-Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), 2, 4-and/or 2, 4, 4-trimethyl-1, 6-hexamethylene diisocyanate, the isomeric dicyclohexylmethane 4, 4' -diisocyanates or mixtures thereof, 4-isocyanatomethyl-1, 8-octanediisocyanate and 1, 4-cyclohexyl diisocyanate, 1, 4-phenylene diisocyanate, 2, 4-and/or 2, 6-toluene diisocyanate, isomers of diphenylmethane diisocyanate (MDI), or a derivative based on the above diisocyanate and having an uretdione, isocyanurate, urethane, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structure and having two or more isocyanate groups.

Preferred polyisocyanates or polyisocyanate mixtures of the above-mentioned kind are those which contain exclusively isocyanate groups which are linked to aliphatic and/or cycloaliphatic groups. Particularly preferred are 1, 6-hexamethylene diisocyanate, isophorone diisocyanate, isomers of dicyclohexylmethane 4, 4' -diisocyanate, and mixtures thereof.

The water-dilutable polyurethanes of the invention are prepared by methods known in principle. For example, it can be prepared by the following steps: first of all, an isocyanate-functional prepolymer is prepared from one or more compounds of component a5) and components a1) to a4) and then, in a second reaction step, is reacted with one of the compounds of a1) to a4), preferably A3) and a4), in a nonaqueous medium to give an OH-functional polyurethane. Alternatively, the water-dilutable polyurethanes of the invention are prepared by reacting the components A1) -A5) in the corresponding molar amounts in a nonaqueous medium to form OH-containing polyurethane resins directly, as described in EP-A0427028, page 4, line 54 to page 5, line 1.

The urethanization reaction or prepolymer preparation is generally carried out at temperatures of from 30 ℃ to 140 ℃ depending on the reactivity of the isocyanate used. In order to accelerate the urethanization reaction, catalysts known to the person skilled in the art which accelerate the NCO-OH reaction can be used. Examples of the catalyst are tertiary amines such as triethylamine, organotin compounds such as dibutyltin oxide, dibutyltin dilaurate or tin bis (2-ethylhexanoate), or other organometallic compounds.

The urethanization reaction may also be carried out in the presence of a solvent which is inert towards isocyanates. Particularly suitable solvents for this purpose are water-compatible solvents, such as ethers, ketones and esters, and also N-methyl-or N-ethylpyrrolidone. A suitable amount of solvent is not more than 30% by weight, preferably not more than 25% by weight, more preferably not more than 10% by weight, based in each case on the total weight of polyurethane resin and solvent. The polyisocyanate may be added to the solution of the remaining components.

The acid groups incorporated into the polyurethane resin by component a4) can be at least partially neutralized. Particularly suitable for neutralization are tertiary amines, examples being trialkylamines having from 1 to 12, preferably from 1 to 6, carbon atoms per alkyl group. Examples are trimethylamine, triethylamine, methyldiethylamine, tripropylamine and diisopropylethylamine. The alkyl radicals may also bear hydroxyl groups, for example, such as dialkylmonoalkanolamines, alkyldialkanolamines and trialkanolamines. An example is dimethylethanolamine, preferably used as neutralizing agent. If appropriate, it is also possible to use inorganic bases as neutralizing agents, for example ammonia or sodium hydroxide or potassium hydroxide. The neutralizing agent is generally used in a molar ratio of from 0.3: 1 to 1.6: 1, preferably from 0.5: 1 to 1.3: 1, to the acid groups of the prepolymer.

The COOH groups can be neutralized before, during or after the carbamation reaction. The neutralization step is preferably carried out after the carbamation reaction, generally between room temperature and 120 c, preferably between 60 and 100 c. It is also possible to provide the water reducible polyurethane resin in a non-neutralized form, the neutralization being carried out only when preparing the aqueous coating composition, for example when the water reducible polyurethane of the present invention is incorporated into a substantially OH free polyurethane dispersion.

The water-reducible polyurethane resin of the present inventionNumber average molecular weight M of_nIs 1000-30000Da, preferably 1500-10000Da, the acid value is 10-80, preferably 15-40, the OH value is 15-650 mg KOH/g, preferably 30-125 mg KOH/g.

The polyurethane resin of the present invention can be used in the form of an aqueous dispersion and a water-dilutable organic solution. In the latter case, the solids content of the water-dilutable polyurethanes is from 50 to 90% by weight, preferably from 70 to 90% by weight, more preferably from 75 to 90% by weight. The remainder of 100% by weight consists of solvents of the abovementioned kind and, if appropriate, auxiliaries and additives customary in coatings.

The present invention accordingly provides organic solutions comprising the water-dilutable, hydroxyl-functional polyurethanes according to the invention with a solids content of from 50% to 90% by weight, the remainder of 100% by weight consisting of organic solvents and, if appropriate, auxiliaries and additives customary in coatings.

In the case where it is desired that the polyurethane resin of the present invention is in the form of an aqueous dispersion, it is easily converted into a stable aqueous dispersion by adding water or introducing them into water after at least partially neutralizing the carboxylic acid groups with the above-mentioned neutralizing agent. The aqueous dispersion has a solids content of 35 to 70 wt.%, preferably 40 to 65 wt.%, more preferably 50 to 60 wt.%.

The invention also provides dispersions comprising the water-dilutable, hydroxyl-functional polyurethanes of the invention with a solids content of the water-dilutable polyurethanes of from 35 to 70% by weight, the remainder of the 100% by weight consisting of water, organic solvents, if appropriate, and auxiliaries and additives, if appropriate, customary in coatings.

The water reducible polyurethanes of the present invention may be processed into aqueous coating compositions. The present invention therefore also provides polyurethane resins comprising a polyurethane resin according to the invention and at least one crosslinker, preferably a polyisocyanate crosslinker, more preferably a polyisocyanate crosslinker having free isocyanate groups.

Examples of suitable crosslinkers are polyisocyanate crosslinkers, amide and amine-formaldehyde resins, phenolic resins, aldehyde resins and ketone resins, such as phenol-formaldehyde resins, resol resins, furan resins, urea resins, urethane (carbamate ester) resins, triazine resins, melamine resins, benzoguanamine resins, cyanamide resins or aniline resins.

Preferably used crosslinkers are polyisocyanates having free and/or blocked isocyanate groups. Preferred are crosslinker resins based on isophorone diisocyanate, 1, 6-hexamethylene diisocyanate or bis (4-isocyanatocyclohexane) methane or mixtures thereof with unblocked isocyanate groups and modified polyisocyanates of the above-mentioned type having uretdione, isocyanurate, urethane, allophanate, biuret, carbodiimide, iminooxadiazinedione and/or oxadiazinetrione structures.

Particular preference is given to using low-viscosity polyisocyanates of the abovementioned kind which are modified, where appropriate, hydrophilically. The hydrophilization of polyisocyanates can be carried out, for example, by reaction with stoichiometric amounts of monoalcohols, hydrophilic polyether alcohols. The preparation of such hydrophilicized polyisocyanates is described, for example, in EP-A0540985 (page 3, line 55 to page 4, line 5). Also very suitable are the polyisocyanates containing allophanate groups described in EP-A959087 (page 3, lines 39 to 51), which are prepared by reacting low-monomer polyisocyanates with polyethylene glycol polyether alcohols under allophanatization conditions. Also suitable are water-dispersible polyisocyanate mixtures based on triisocyanatononane as described in DE-A10007821 (page 2, line 66 to page 3, line 5) and polyisocyanates hydrophilically modified with ionic groups (sulfonate, phosphate) as described in DE-A10024624 (page 3, lines 13 to 33).

The viscosity of these isocyanates at 23 ℃ is generally 200-. These isocyanates may be used as a mixture with a small amount of an inert solvent, if desired, to reduce the viscosity to within the stated range. Triisocyanatononane may also be used, alone or as a mixture, as a crosslinker component.

The aqueous coating compositions thus obtained, comprising the polyurethanes of the invention, are suitable for use in all fields where stringent requirements are placed on the surface quality/resistance of films to which aqueous paints and coating systems are applied, such as coatings on mineral building material surfaces, lacquers and seals on wood and wood-based materials, coatings on metal surfaces (metal coatings), coatings and paints for asphalt or bitumen finishes, paints and seals on various plastic surfaces (plastic coatings) and high-gloss varnishes. However, the coatings of the invention are particularly useful for producing soft-feel coatings, and are able to guarantee high solvent resistance, while also having high resistance (in the sunscreen test), particularly to sunscreens. Such coatings are preferably used for coating plastics or wood, curing usually taking place at temperatures from room temperature to 130 ℃.

Aqueous coating compositions comprising the water reducible polyurethanes of the present invention are typically used in one-coat finishes or in clearcoats or topcoats (top coats) for multicoat structures.

The coatings can be produced by a number of spray methods, including air pressure spraying, airless spraying or electrostatic spraying, using a one-component spray device or, if appropriate, a two-component spray device. However, paints and coatings comprising the binder dispersions of the invention may also be applied by other methods, for example by brushing, rolling or knife coating.

Examples

All percentages are by weight unless otherwise indicated.

To DIN 53019 at 40 seconds^-1Viscosity measurements were performed using a Paar-Physica MRC 51 cone plate viscometer (Anton Paar, Stuttgart, Germany).

The average particle size was measured using laser correlation spectroscopy (Zetasizer ® 1000, Malvern Instruments, Herrenberg, germany).

Hydroxyl value (OH-N): the unit is mg KOH/g; measured according to DIN 53240.

Acid value (A-N): the unit is mg KOH/g; measured according to DIN ISO 3682. Raw materials:

acemantt ® OK 412: deluss (Frankfurt, Degussa)

Aquacer ® 535: wax emulsion (Byk Chemie, Wesel)

Bayblend ® T65: based on Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS)

Amorphous thermoplastic polymer blends (Bayer MaterialScience,

Leverkusen)

bayferrox ® 318M: pigment (Lanxess AG, Leverkusen)

Bayhydrol ® PR 650: 50% aqueous aliphatic polyurethane resin Dispersion (Bayer)

MaterialScience，Leverkusen)

Bayhydrol ® PT 355: 55% aqueous aliphatic hydroxy-functional polyester-polyurethane dispersion, OH content

Is 1.5% (solid) (Bayer MaterialScience, Leverkusen)

Bayhydur ® 3100: hydrophilically modified aliphatic polyisocyanates (Bayer MaterialScience,

Leverkusen)

byk ® 348: wetting agent (Byk Chemie, Wesel)

Desmophen ® C1200: linear aliphatic polycarbonate-polyester, OH-N ═ 56 (Bayer)

MaterialScience，Leverkusen)

Desmorapid ® SO: a urethanization catalyst (Bayer MaterialScience,

Leverkusen)

Entsch-Kamer DNE: defoaming agent (K.Obermayer, Bad Berlebburg)

PACM ® 20: isomer mixture of bis (4-aminocyclohexyl) methane (DuPont, Bad)

Homburg)

Pergopak ® M3: filler matting agent (Martinswerk, B ergheim)

Silitin ® Z86: filler (Hoffrnann & S ö hne, Neuburg)

Talc IT Extra: filler (Norwegian Talc, Frankfurt)

Tego ® Wet KL 245: wetting agent (50% in water; Tego Chemie, Essen)

Example 1: diol containing amide group

To a5 liter reaction vessel equipped with a stirrer, heating mantle, thermometer, distillation column and nitrogen inlet was added 460 grams of epsilon-caprolactone and the initial charge was heated to 140 ℃ under a nitrogen flow of 10-12 liters/hour. 420 grams of PACM ® 20 were then added dropwise at a rate such that the temperature did not exceed 160 deg.C. Stirring was continued for 4 hours at 140 ℃. The reaction mixture was cooled to room temperature to obtain a diamine diol as a transparent viscous resin.

Amide group content (based on CONH): 19.6% by weight

Practice ofExample 2: diol containing amide group

To a5 liter reaction vessel equipped with a stirrer, heating mantle, thermometer, distillation column and nitrogen inlet was added 460 grams of epsilon-caprolactone and the initial charge was heated to 140 ℃ under a nitrogen flow of 10-12 liters/hour. Then, 340 g of 1-amino-3, 3, 5-trimethyl-5-aminoethylcyclohexane (isophoronediamine) were added dropwise at such a rate that the temperature did not exceed 160 ℃. Stirring was continued for 4 hours at 140 ℃. The reaction mixture was cooled to room temperature to obtain a diamine diol as a transparent viscous resin.

Amide group content (based on CONH): 21.5% by weight

Example 3: polyester diol containing amide group

A5 liter reaction vessel equipped with a stirrer, heating mantle, thermometer, distillation column and nitrogen inlet was charged with 970 grams of epsilon-caprolactone and 893 grams of PACM ® 20, and the initial charge was melted at 120 ℃ under a nitrogen flow of 10-12 liters/hour. Stirring was then carried out and the temperature was increased to 140 ℃ over 2 hours. The mixture was stirred at 140 ℃ for 6 hours. 252 g of phthalic anhydride, 994 g of adipic acid, 1034 g of hexane-1, 6-diol and 133 g of neopentyl glycol were then added and the reaction mixture was heated to 220 ℃ over 8 hours. It was kept at 220 ℃ until the acid value (A-N) was reduced to 3 or less. Thus, a high-viscosity transparent polyester resin having an A-N value of 2.7 and an OH-N value of 176 was obtained.

Amide group content (based on CONH): 9.1% by weight

Example 4: polyester diol containing amide group

To a5 liter reaction vessel equipped with a stirrer, heating mantle, thermometer, distillation column and nitrogen inlet was charged 1797 grams of epsilon-caprolactone and 1656 grams of PACM ® 20, and the initial charge was melted at 120 deg.C under a nitrogen flow of 10-12 liters/hour. Stirring was then carried out and the temperature was increased to 140 ℃ over 2 hours. The mixture was stirred at 140 ℃ for 6 hours. 156 g of phthalic anhydride, 614 g of adipic acid, 366 g of hexane-1, 6-diol and 82 g of neopentyl glycol were then added and the reaction mixture was heated to 220 ℃ over 8 hours. It was kept at 220 ℃ until the acid value (A-N) was reduced to 3 or less. Thus, a high-viscosity transparent polyester resin having an A-N value of 2.5 and an OH-N value of 165 was obtained.

Amide group content (based on CONH): 15.0% by weight

Example 5: the polyurethanes of the invention

To a5 liter reaction vessel equipped with cooling, heating and stirring means, 570 grams Desmophen ® C1200, 585 grams amido-functional polyester from example 3, 60 grams dimethylolpropionic acid and 45 grams trimethylolpropane were added under a nitrogen atmosphere and the initial charge was heated to 130 ℃ and homogenized for 30 minutes. Cooled to 80 ℃ and 1.1 g Desmorapid ® SO and 240 g 1, 6-hexamethylene diisocyanate were added with vigorous stirring. The temperature of the mixture was raised to 140 ℃ by the heat evolved by the reaction. This temperature is maintained until no more isocyanate groups are detected.

The resulting polyurethane was then cooled to 90-100 deg.C, 19 grams of dimethylethanolamine was added and dispersed with 1230 grams of water at room temperature. The resulting dispersion had a solids content of 55 wt% (based on resin solids), OH-N of 53 and A-N of 18.1.

Amide group content (based on CONH): 3.5% by weight

Example 6: the polyurethanes of the invention

1084 g of the amido-functional polyester from example 3, 60 g of dimethylolpropionic acid and 45 g of trimethylolpropane are introduced, under a nitrogen atmosphere, into a5 l reaction vessel equipped with a cooling, heating and stirring device, and the initial charge is heated to 130 ℃ and homogenized for 30 minutes. Cooled to 80 ℃ and 1.1 g Desmorapid ® SO and 310 g 1, 6-hexamethylene diisocyanate were added with vigorous stirring. The temperature of the mixture was raised to 140 ℃ by the heat evolved by the reaction. This temperature is maintained until no more isocyanate groups are detected.

The resulting polyurethane was then cooled to 90-100 deg.C, 19 grams of dimethylethanolamine was added and dispersed with 1045 grams of water at room temperature. The resulting dispersion had a solids content of 59 wt% (based on resin solids), OH-N of 50 and A-N of 18.8.

Amide group content (based on CONH): 6.8% by weight

Example 7: the polyurethanes of the invention

To a5 liter reaction vessel equipped with cooling, heating and stirring means, 570 grams Desmophen ® C1200, 585 grams amido-functional polyester from example 4, 60 grams dimethylolpropionic acid and 45 grams trimethylolpropane were added under a nitrogen atmosphere and the initial charge was heated to 130 ℃ and homogenized for 30 minutes. Cooled to 80 ℃ and 1.1 g Desmorapid ® SO and 240 g 1, 6-hexamethylene diisocyanate were added with vigorous stirring. The temperature of the mixture was raised to 140 ℃ by the heat evolved by the reaction. This temperature is maintained until no more isocyanate groups are detected.

The polyurethane obtained is then cooled to 90-100 ℃ and 19 g dimethylethanolamine are added and dispersed at room temperature with 1160 g water. The resulting dispersion had a solids content of 55 wt% (based on resin solids), OH-N of 46 and A-N of 18.1.

Amide group content (based on CONH): 5.9% by weight

Example 8: the polyurethanes of the invention

To a5 liter reaction vessel equipped with cooling, heating and stirring means, 570 grams Desmophen ® C1200, 585 grams of the amido-functional diol from example 1, 60 grams dimethylolpropionic acid and 45 grams trimethylolpropane were added under a nitrogen atmosphere and the initial charge was heated to 130 ℃ and homogenized for 30 minutes. Cooled to 80 ℃ and 1.1 g Desmorapid ® SO and 240 g 1, 6-hexamethylene diisocyanate were added with vigorous stirring. The temperature of the mixture was raised to 140 ℃ by the heat evolved by the reaction.

This temperature is maintained until no more isocyanate groups are detected. The polyurethane obtained is then cooled to 90-100 ℃ and 19 g dimethylethanolamine are added and dispersed at room temperature with 1160 g water. The resulting dispersion had a solids content of 54 wt% (based on resin solids), an OH-N of 72.5 and an A-N of 18.1.

Amide group content (based on CONH): 7.6% by weight

Application examples

Formula composition of 2-component soft-feel paint

Examples		9	10	11	12
						Example 5	Component 1	62.3	-	-	-
Example 6	-	68.1	-	-
					Example 7	-		-	65.8	-
Bayhydrol®PT 355	-	-	-	72.7
					Bayhydrol®PR 650	Component 2		80.0	80.0	80.0	80.0
Entsch*umer DNE 01	Additive agent	0.6	0.6	0.6			0.5
					Tego ® Wet KL 245, 50% in water	0.9		0.9	0.9	0.9
Byk®348		1.4	1.4	1.4			1.4
					Aquacer®535	4.0		4.0	4.0	4.0
Sillitin®Z 86		14.0	13.9	13.9			13.9
					Talc IT extra	11.2		11.1	11.1	11.1
Bayferrox®318		37.3	37.1	37.1			36.9
					Acematt®OK 412	7.5		7.4	7.4	7.4
Water, demineralizationOf a nature		40.0	57.1	49.3			40.0
					Bayhydur ® 3100, 75% in MPA	Component 3		17.7	17.0	17.0	16.5

Dispersion of soft feel coating：

To produce the coating, the binders shown in table 1 (components 1 and 2) were dispersed with the additives shown in table 1 and demineralized water in the amounts shown in table 1 in a ball mill (bead mill) to give an aqueous millbase (millbase). After standing at room temperature for 16 hours, a solution of 75% strength of the polyisocyanate crosslinker Bayhydur ® 3100 in methoxypropyl acetate (components, in the amounts indicated in table 1) was added to the millbase using a dissolver.

The coating thus obtained was applied by spraying to a flat surface (dry film thickness 40-50 μm), after flash evaporation for 10 minutes at 55% relative atmospheric humidity, dried at 80 ℃ for 30 minutes and then at 60 ℃ for 16 hours.

This gives a uniform matt coating with an outstanding soft feel effect which can be described as velvety smooth.

Measurement of solvent resistance

To determine the solvent resistance, the soft feel effect coatings of table 1 were applied to glass and dried as described. For testing purposes, a cotton pad soaked with solvent was placed on the coating. In the case of low boiling solvents, the cotton pad is also covered with a watch glass. After 1 minute of contact, evaluation was performed. The cotton pad was removed and the remaining solvent was wiped off using a fibrous cloth. The test area was then immediately evaluated by observation and scratching with a fingernail (evaluation results are below).

Examples		EtAc	MPA	Xylene	EtOH	SB	H2O
								9	Example 5	2	0	0	1	1	0
10	Example 6	3	1	1	1	1	0
								11	Example 7	3	1	1	0	1	0
12	Bayhydrol®PT 355	4	3	3	2	2	2

EtAc ═ ethyl acetate, MPA ═ methoxypropyl acetate, EtOH ═ ethanol, SB ═ premium gasoline rating

0 has no change and no damage

1 Trace change (swelling ring very weak, only in the light through reflection can be seen, with the nail feel can not be softened)

2 slight change (swelling ring visible under light, nail scratch visible)

3 obvious change (complete swelling ring can be seen very clearly, nail scratches are visible and softening can be felt)

4 Severe change (complete swelling ring can be observed very clearly, nail scratch can reach the substrate, become sticky)

5 failure (coating surface cracking/failure).

The coatings of examples 9-11 containing amido-functional polyurethane resins clearly have better solvent resistance than the standard (example 12).

Determination of resistance to creaming

To determine solvent resistance, the soft feel coatings shown in Table 1 were applied to Bayblend ® T65 test pieces and dried as described above.

Approximately 1 ml each of the test media (Coppertone Waterbabies SPF30 water repellent, manufacturer: Schering-Plough health Care Products Inc.; Delial Plus Vitamin SF30 water repellent, manufacturer: L' Oreal Deutschland GmbH, 40474 Dusseldorf Kamill Hand & Nail Crel, manufacturer: Burnus10 GmbH, 40474 Dusseldorf) was applied to the soft feel coating in a metal ring of 2 cm diameter. After 1 hour of contact at 80 ℃, the cream (creams) was wiped off with cotton cloth and the degree of damage was visually evaluated according to the following criteria.

Evaluation of

Examples		CoppertoneWaterbabies SPF30 water repellent	Delial PlusViamin SF30 water proofing	Kamill ClassicHand&NailCream
					9	Example 5	3	3	3
10	Example 6	3	3	3
					11	Example 7	3	3	3
12	Bayhydrol®PT 355	4	4	4

Evaluation:

1-No change

2-temporary damage

3-leaving speckle/loss of gloss/color change

4-softening

5-foaming/separating from substrate

6-crushing

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (12)

1. A water-dilutable, hydroxyl-functional polyurethane comprising at least one structural unit of the general formula (I):

wherein the content of the first and second substances,

R₁is an aliphatic or cycloaliphatic radical having from 2 to 18 carbon atoms,

R₂is an aliphatic group having 3 to 5 carbon atoms.

2. The water reducible hydroxyl functional polyurethane of claim 1 having an amide group content of from 2.0 wt.% to 20 wt.% calculated as (CO) NH.

3. The water reducible hydroxyl functional polyurethane of claim 1, wherein the polyurethane is the reaction product of:

A1)25 to 80% by weight of at least one amide group-containing polyol having a number average molecular weight M_nIs the temperature of 314-,

A2)0 to 60% by weight of at least one polyol from the group of polyesters, polycarbonates or polyethers, having a number-average molecular weight M_nIs 400-6000Da,

A3)0 to 20% by weight of at least one low molecular weight polyol having at least two hydroxyl groups and a number average molecular weight of 62 to 400Da,

A4) from 2 to 10% by weight of at least one compound having at least two groups reactive toward isocyanate groups and at least one group capable of forming anions,

A5)5 to 50% by weight of a polyisocyanate,

the sum of components A1) to A5) is 100%.

4. The water reducible hydroxyl functional polyurethane of claim 1 wherein component a1) comprises the reaction product of a) and b), wherein a) is one or more compounds selected from the group consisting of: isomers of 1, 6-hexanediamine, 2-methyl-1, 5-diaminopentane, 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), bis (4-aminocyclohexyl) methane, and mixtures thereof; b) is epsilon-caprolactone.

5. The water reducible hydroxyl functional polyurethane of claim 1 wherein component a1) is an amide group containing polyester polyol.

6. The water-dilutable, hydroxyl-functional polyurethane according to claim 1 wherein component A1) comprises structural units of the general formula (I) and the amide group content of component A1) is at least 7.5% by weight, calculated as (CO) NH.

7. An organic solution comprising the water-dilutable, hydroxyl-functional polyurethane according to claim 1, wherein the solids content of the water-dilutable polyurethane is from 50 to 90% by weight, the remainder of 100% by weight comprising organic solvents and optionally auxiliaries and additives.

8. A dispersion comprising the water-dilutable, hydroxyl-functional polyurethane according to claim 1, wherein the solids content of the water-dilutable polyurethane is from 35 to 70% by weight, the remainder of 100% by weight comprising water, organic solvents and optionally auxiliaries and additives.

9. An aqueous coating composition comprising the dispersion of claim 8 and at least one crosslinker.

10. The aqueous coating composition of claim 9, wherein the crosslinker is a polyisocyanate.

11. The aqueous coating composition of claim 10, wherein the polyisocyanate is in an unblocked form.

12. A multilayer coating composition having a clear coat or top coat material comprising the water reducible hydroxyl functional polyurethane of claim 1 as the uppermost layer.