KR101791283B1 - Aqueous anionic polyurethane dispersions - Google Patents

Abstract

Certain hydrophobic polyol-based aqueous anionic polyurethane dispersions are useful as encapsulants for the coating of hard surfaces such as metals, plastics, glass and wood and provide coatings with excellent durability, adhesion, hydrolysis resistance and alkali / acid resistance and hardness do.

Description

Aqueous Anionic Polyurethane Dispersions {AQUEOUS ANIONIC POLYURETHANE DISPERSIONS}

The present disclosure relates to aqueous anionic polyurethane dispersions based on certain hydrophobic polyols and their use as filming agents for the coating of rigid surfaces such as metals, plastics, glass and wood.

The aqueous dispersions herein provide coatings having excellent durability, adhesion, hydrolysis resistance and alkali / acid resistance and hardness.

The surface of manufactured articles made of many articles of manufacture, such as leather, plastic, wood, glass and metal, may be made more homogeneous, or for the purpose of preventing from time or wear by the atmosphere and / , Soft or rough texture, color, and the like.

Usually these effects are obtained through application (coating) of the coating polymer, of which the solvent-borne polyurethane is presently known and appreciated in the coating field, among the many different coating polymers, because they have excellent chemical and empirical properties Can be calculated.

Aqueous dispersions of polyurethanes have also recently gained an important role because of the increased interest in the environment and, in particular, by regulatory policies that lower the emission of low volatile organic compounds in the workplace.

When polyurethanes in the form of aqueous dispersions are contemplated for coating, some problems arise due to the fact that their water dispersibility requires the inclusion of hydrophilic segments which inherently reduces membrane durability and hydrolytic stability.

It is known in the art to introduce unsaturated groups into the polyurethane which can cause crosslinking in the membrane and consequently improve the chemical resistance of the coating, which unfortunately necessitates the conditions of strong oxidizing conditions for the yellowing and crosslinking of the membrane, Are the disadvantages associated with the presence of unsaturated groups in the urethane.

US 2003/0191273 describes the use of aqueous dispersions of polyurethanes based on fatty acid alganamide as a coating composition; The coatings produced from these dispersions are said to have good pendulum hardness, good heelmark resistance and high gloss.

US 2008/0194757 describes water dispersed polyurethane compositions containing a nourishing compound having a long chain alkyl group as a polyisocyanate component; The composition is said to provide a coating film excellent in adhesion, water resistance, weather resistance, corrosion resistance, water repellency and oil repellency.

Surprisingly, an aqueous dispersion of anionic polyurethane which can obtain a durable film having excellent adhesion, chemical resistance and hardness on a hard substrate by incorporating the specific hydrophobic polyol obtained by the reaction of fatty alcohol and aromatic diglycidyl ether into polyurethane Can now be obtained.

The present invention relates to a process for the preparation of a neutralized anionic prepolymer which is prepared by reacting one or more aliphatic, cycloaliphatic or aromatic polyisocyanates with a polyol mixture (P) comprising: a neutralized anionic prepolymer containing carboxyl groups of 5 to 125 meq / To provide an aqueous dispersion containing from 20 to 50% by weight of an anionic polyurethane obtained by extending to polyamines:

I) alcohol ROH wherein R is a branched or linear, saturated C ₄ -C ₃₀ , preferably C ₆ -C ₂₂ alkyl chain, or R is branched or linear, saturated C ₄ -C ₁₀ alkylphenyl (I), which is obtained by reacting an aromatic diglycidyl ether of the following formula (I) with a hydroxyl number of 350 to 40 (mg KOH / g), one or more hydrophobic groups having an average molar hydroxyl functionality of 2 to 3 4 to 90% by weight of polyol:

(I)

(I)

In the formula, R ₁ is the following radical (i)

(i)

(i)

Wherein R ₂ and R ₃ are each independently methyl (Me), ethyl (Et), or hydrogen (H); or

R ₁ is phenylene optionally substituted with one or more alkyl groups, preferably a methyl group; or

R ₁ is biphenylene optionally substituted with one or more alkyl groups, preferably a methyl group; or

R < _{1 >} is the radical (ii)

(ii)

(ii)

being.

II) from 1 to 10% by weight of at least one anionic or potentially anionic polyol having at least two groups reactive with isocyanate groups and at least one carboxyl or carboxylate group;

III) 0 to 95% by weight of at least one linear polycarbonate diol having a molecular weight of 500 to 3,000;

IV) 0 to 95% by weight of at least one linear polyester diol having a molecular weight of 500 to 4,000;

V) from 0 to 95% by weight of at least one polyoxyalkylene diol selected from poly (oxypropylene) glycol and poly (oxytetramethylene) glycol,

Wherein the polyisocyanate and polyol mixture (P) is a) a ratio of the sum of all reactive -OH groups of the isocyanate group NCO of the polyisocyanate and the polyol mixture (P) of 1.2 to 2.3.

According to another aspect, the present invention relates to the use of the above-described aqueous anionic polyurethane dispersions used for the preparation of coating compositions.

The aqueous dispersions herein provide coatings having excellent durability, adhesion, hydrolysis resistance and alkali / acid resistance and hardness.

In one embodiment, the sum of components I), II), III), IV) and V) is at least 95% by weight of the polyol mixture, the polyol mixture having a molecular weight of less than 1,000 and containing at least two hydroxyl groups Further 0 to 5% by weight of other non-ionic polyols; Examples of such non-ionic polyols that may be used include glycerol, pentaerythritol, neopentyl glycol, butanediol, 1,4-cyclohexanedimethanol, trimethylol propane and its derivatives such as propoxylated trimethylol propane, Polybutadiene and polyester polyols.

In a preferred form of this embodiment, the sum of components I), II), III), IV) and V) is 100% by weight of the polyol mixture (P) of the prepolymer; A more preferred embodiment is that the sum of components I), II), III) and IV) is 100% by weight of the polyol mixture.

The hydrophobic polyol I) does not contain an epoxy group and preferably represents a polyol mixture of 5 to 75% by weight.

Advantageously, in the aromatic diglycidyl ether of formula (I), R ₁ is a radical (i) and R ₂ and R ₃ are methyl groups.

The polyisocyanates which can be used have an average -NCO functionality of from 2.0 to 2.3 and are preferably aliphatic or cycloaliphatic.

Examples of useful polyisocyanates are 4,4'-dicyclohexyl-methane-diisocyanate, 1-isocyanato-3- (isocyanatomethyl) -3,5,5-trimethylcyclohexane (or isophorone Isophoronediisocyanate), tetramethylene diisocyanate, hexamethylene diisocyanate, and mixtures thereof.

Most preferred polyisocyanates are 4,4'-dicyclohexyl-methane-diisocyanate, 1-isocyanate-3-isocyanate-methyl-3,5,5-trimethylcyclohexane (or isophorone diisocyanate) and hexamethylene diisocyanate , And mixtures thereof.

 Polyisocyanates having an average -NCO functionality higher than 2 include partially trimerization of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and mixtures thereof, biurethration ), Urethanization or allophanation, or by mixing the above-mentioned diisocyanates with their trimerization, buretization, urethanation or allophanization products.

The component II) of the polyol mixture (P) is preferably a carboxylic acid substituted at the 2-position by two hydroxymethyl groups such as dimethylolpropanoic acid, dimethylolbutanoic acid or mixtures thereof.

The amount of component II) in the polyol mixture is selected to obtain a prepolymer containing 5 to 125 meq / 100 g of a dry substance of -COOH groups; The best results are obtained when this value is 20 to 60.

Component III) of the polyol mixture (P) is a reaction product of a de-alcohol condensation reaction of a low molecular weight diol and a dialkyl carbonate, a de-phenol condensation reaction of a low molecular weight diol and a diphenyl carbonate, Or a polycarbonate obtained by a de-glycol condensation reaction of a low molecular weight diol with an alkylene carbonate or a dialkyl carbonate.

Examples of low molecular weight diols are 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, 3-methyl-1,5- pentanediol, neopentyl glycol, diethylene glycol , 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and the like. Examples of dialkyl carbonates include dimethyl carbonate and diethyl carbonate. An example of a dialkylene carbonate is diethylene carbonate. An example of a particularly preferable polycarbonate diol is a poly (hexamethylene carbonate) diol obtained by a condensation reaction of 1,6-hexanediol with a dialkyl carbonate.

The polycarbonate diol preferably has a number average molecular weight of 800 to 2,000.

Component IV) of the polyol mixture (P) can be selected from acids, esters, anhydrides or polyesters obtained from the reaction of an acyl halide with a glycol.

Useful for the preparation of said polyester are, for example, maleic acid, succinic acid, adipic acid, suberic acid, sebacic acid, phthalic acid, terephthalic acid and isophthalic acid and possibly their corresponding acyl halides, anhydrides and esters.

Examples of suitable glycols include ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,2-propanediol, neopentyl glycol, tetramethyleneglycol, diethylene glycol, 1,6-hexanediol, - pentanediol; Substituted alkylene glycols such as 2,2-dimethyl-1,3-propanediol; 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, and cyclic glycols such as aromatic glycols; These glycols react with a compound capable of forming an ester bond with an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or with an alkyl ester of a lower molecular weight alcohol to form a polymer having a relatively low molecular weight, preferably a melting point of less than about 80 & .

Hydroxyl terminated polycaprolactones may also be used.

The polyester diol preferably has a number average molecular weight of 800 to 3,000.

In a preferred embodiment, the polyester diol is selected from among adipic acid and / or polyester based on phthalic acid and 1,6-hexanediol, ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol or mixtures thereof do.

According to a preferred embodiment, the polyol of the mixture (P) is free of units derived from poly (oxyethylene) glycol.

An aqueous dispersion of an anionic polyurethane of the present invention comprises i) reacting a polyisocyanate with a polyol mixture (P) in a ratio as defined above; ii) dispersing the obtained prepolymer in water; iii) adding a polyamine (chain extender) to the dispersion thus obtained and allowing the reaction to occur until all the isocyanate groups have disappeared.

Step i) is preferably carried out in the presence of an organic solvent or an organic solvent mixture at a temperature of from 40 to 110 캜; However, the use of a hydrophobic polyol I) reduces the viscosity of the reaction mixture, and thus advantageously reduces the amount of solvent required in the synthesis and the overall consumption of the VOC. Suitable solvents include conventional solvents such as N-methylpyrrolidone, N-ethylpyrrolidone, dipropylene glycol dimethyl ether, ethyl acetate, butyl acetate, ethylene glycol monomethyl or monoethyl ether acetate, 1-methoxypropyl 2 -Acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, especially a mixture of aromatic compounds, dimethyl carbonate, diethylcarbamate, [Beta] -profiolactone, [gamma] -butyrolactone, [epsilon] -caprolactone, such as carbonic esters such as benzoate, 1,2-ethylene carbonate and 1,2- Lactone and [Epsilon] -methyl caprolactone, and also lactones such as propylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate and Such as N-methylcaprolactam, or any desired mixture of such solvents. Preferred solvents are N-ethylpyrrolidone and dipropylene glycol dimethyl ether.

The prepolymer obtained at the end of step i) is reacted with a tertiary amine such as N-alkyl morpholine, trialkylamine, dialkylalkanolamine, alkyldialkanolamine, trialkanolamine, And mixtures thereof.

Triethylamine, dimethylethanolamine and N-methylmorpholine are particularly suitable for this category.

Neutralization can be carried out during the last stage of the reaction step i), during the dispersion of the prepolymer in an anhydrous environment or in subsequent water (step ii).

Step ii) is carried out under mechanical stirring, optionally in the presence of an emulsifier, by pouring the prepolymer into water or vice versa.

Emulsifiers may be selected from nonionic, anionic and cationic surfactants; Preferably, the emulsifier is a nonionic surfactant.

The polyamines of step iii) are preferably tertiary and secondary aliphatic diamines.

It is possible to use a mixture of polyamines in step iii).

Examples of suitable polyamines include hydrazine, ethylenediamine, piperazine, 1,5-pentanediamine, 1,6-dihexanediamine, isophoronediamine, diethylenetriamine, 2- 4'-methylene-bis-cyclohexylamine.

The temperature and duration of step iii) and the amount of polyamine are determined so as to obtain a fine, stable and uniform polyurethane dispersion to discharge the free-NCO groups present in the prepolymer, as is known in the art.

The organic solvent which may be present may be removed during step iii) or by the end of step iii) by distillation.

Step iii) of the process of the present invention can be carried out by percolating the polyamine into a dispersion of the prepolymer held under agitation at a temperature of less than 40 ° C.

점도는 일반적으로 50 내지 2,000 mPa·s로 이루어진다.The anionic < RTI ID = 0.0 > polyurethane < / RTI >

The viscosity is generally comprised between 50 and 2,000 mPa · s.

In the preparation of the coating compositions, anionic polyurethane foams are used to further improve their coating performance, such as film forming ability, and to prevent "orange peel" or "fish-eyes" The dispersion may be mixed with a crosslinking agent, a binder, preferably an acrylic binder, and / or other additives.

Examples of additives that may be added to the coating composition include leveling agents, wetting agents, leveling agents, fillers, pigments, waxes, surfactants, thickeners, coalescing agents, rust inhibitors, , And so on.

 The anionic polyurethanes of the aqueous dispersions of the present invention can also be prepared by reacting the anionic polyurethane of the present invention with all of those known to those skilled in the art such as hydrodispersible polyisocyanates, blocked polyisocyanates, polyaziridines, carbodiimides, epoxy silanes and melamines. Can be crosslinked with a crosslinking agent.

The crosslinking agent is generally added in an amount of 1 to 10% by dry weight of the dispersion.

Cross-linking agents can be used to enhance the mechanical and chemical properties of the membrane.

The film-forming anionic polyurethane aqueous dispersions and coating compositions containing the same of the present invention can be applied to a wide range of substrates such as plastics (e.g. polycarbonate, ABS and PVC), wood, glass, and metals (e.g. aluminum, steel, GA, GL, GI, and EGI).

및 아이패드(i-Pads)

와 같은 전자 제품, 코일 코팅을 위한, 컴퓨터 케이스 및 텔레비젼 케이스와 같은 금속 표면에 사용될 수 있다.The material coated with the film obtained from the aqueous dispersion of the present invention can be used for the interior side of an automobile door or in an automobile interior, mobile phone, i-Pods,

And i-Pads

, For metal coatings, for electronic coatings, for coatings, for computer coatings and television cases.

In the following examples, the synthesis of hydrophobic polyols according to the invention and the preparation of aqueous dispersions are reported.

The particle size of the dispersion was measured by Laser Correlation Spectroscopy (LCS) using a Coulter N4 Plus instrument at 25 ° C and 90 ° at each temperature.

Example

The following materials as listed below were used in the examples described hereinafter.

Polyol 1: polyester diol, adipate-phthalate of 1,6-hexanediol, molecular weight, 1,000 g / mol

Polyol 2: polycarbonate diol, poly (hexamethylene carbonate) diol, molecular weight 1000 g / mol

H-polyol 5: cocodiethanolamide, molecular weight 213 g / mol

H-polyol 6: oleyldiethanolamide, molecular weight 269.7 g / mol

DGEBA: diglycidyl ether of bisphenol A, molecular weight of 380 g / mol

DMPA: dimethylol propanoic acid, molecular weight 134.2 g / mol

Alcohol C6: n-hexanol, molecular weight 102 g / mol

Alcohol C12: n-dodecanol, molecular weight 186 g / mol

Alcohol C20: linear C20 monoalcohol, molecular weight 298 g / mol

NMP: N-methyl-pyrrolidone,

NEP: N-ethyl-pyrrolidone

IPDI: isophorone diisocyanate, molecular weight 222 g / mol

HMDI: 4,4'-dicyclohexyl-methane-diisocyanate, molecular weight 262 g / mol

TEA: triethylamine, molecular weight 101.15 g / mol

DEA: diethanolamine, molecular weight 105.14 g / mol

HH: hydrated hydrazine, 24.36% aqueous solution, molecular weight 32.04 g / mol

ADD: Wetting agent Byk346

Example  1.1-1.3

Examples 1.1-1.3 describe the preparation procedure of DGEBA based hydrophobic polyols.

Example  1.1

Synthesis of H-polyol 1

140.6 g (1.363 mol) of alcohol C6 are charged in a reactor equipped with a thermometer, a stirrer and a condenser under a nitrogen atmosphere and heated to 65 ° C. 0.40 g of 40% KOH are added at 65 DEG C with stirring.

259.4 g (0.682 mol) of DGEBA are then added and the reaction mixture is heated and held at 120 캜 for about 4 hours until the entire epoxy group disappears.

The titration of the epoxy groups is determined in this and all other embodiments in accordance with norm ASTM D1652-04.

Once complete epoxy conversion has been reached, the reaction mixture is cooled to 80 DEG C and 0.35 g of 85% phosphoric acid is added to give polyol H-polyol 1 (molecular weight 586 g / mol). The OH-number is 191 mg KOH / g.

Example  1.2

Synthesis of H-polyol 2

186.0 g (1 mol) of alcohol C12 are charged to the reactor according to the procedure of Example 1.1 and heated to 70 DEG C, followed by 0.75 g of 40% KOH.

190.0 g (0.5 mol) of DGEBA are then added and the reaction mixture is heated to 120 < 0 > C and held until the epoxy disappears (about 4 hours).

The reaction mixture is then cooled to 80 DEG C and 0.65 g of 85% phosphoric acid is added to give the polyol H-polyol 2 (molecular weight 752 g / mol). The OH-number is 149 mg KOH / g.

Example  1.3

Synthesis of H-polyol 3

326.0 g (1 mol) of alcohol C20 are charged to the reactor according to the procedure of Example 1.1 and heated to 100 DEG C, followed by the addition of 0.80 g of 40% KOH.

190.0 g (0.5 mol) of DGEBA are then added and the reaction mixture is heated to 130 < 0 > C and held until the epoxy disappears (about 12 hours).

The reaction mixture is then cooled to 120 DEG C and 0.80 g of 85% phosphoric acid is added to give the polyol H-polyol 3. The OH-number is 108 mg KOH / g.

Example  1.4

Synthesis of H-polyol 4

Describes the preparation of an IPDI-based hydrophobic polyol (H-polyol 4) according to the prior art.

135.1 g of Alcohol C6, 432.0 g of NEP are charged in a reactor equipped with a thermometer, a stirrer and a condenser, under a nitrogen atmosphere and at room temperature.

293.9 g of IPDI are added under agitation after homogenization of the mixture at about 40 占 폚 for about 30 minutes.

The reaction mixture is then heated to 80 DEG C and the reaction is carried out at 90 DEG C until the content of NCO groups in the prepolymer is 6.45%.

Titration of residual isocyanate groups was determined in this and all other examples according to standard method ASTM D2572.

The prepolymer is cooled to 80 DEG C and 138.8 g of DEA are slowly added under stirring.

The obtained polyol (H-polyol 4) has a solid residue content of 75 wt% (molecular weight 429.7). The OH-number is 261 mg KOH / g.

Example  2.1

Preparation of the aqueous dispersion according to the invention

138.7 g of polyol 2 and 26.6 g of H-polyol 1, 20.9 g of DMPA and 80 g of NMP are charged to the reactor according to Example 1.1. 155.6 g of HMDI is added at 40 DEG C with homogenization of the mixture for approximately 30 minutes followed by stirring.

The reaction mixture is then heated and held at 60 DEG C for 30 minutes.

The reaction is carried out at 95-100 ° C. until the content of NCO groups in the prepolymer is equal to the theoretical value of 5.07% (approximately 1 hour).

The prepolymer is then cooled to approximately 75 캜 and 14.9 g of the neutralizing agent TEA are added with stirring.

After about 10 minutes and at an internal temperature of 65 DEG C, the prepolymer is dispersed in demineralized water under strong agitation at a temperature below 35 DEG C. The elongation is carried out by adding 47.8 g of diamine HH (24.36% aqueous solution), as described in Table 1, at a temperature of less than 35 ° C.

The wetting agent ADD was added to the resulting polyurethane dispersion, which was then filtered through a 150 [mu] m canvas to a solid residue content of 35% by weight. The resulting dispersion appears to be clear and stable.

Example  2.2-2.4

Preparation of other aqueous dispersions according to the invention

The procedure described in Example 2.1 was carried out by changing to the components shown in Table 1 (amounts are reported in grams).

Example  2.5 ( Comparative Example )

The procedure described in Example 2.1 was carried out with the ingredients listed in Table 1 without the use of hydrophobic polyols.

Example  2.6-2.10 ( Comparative Example )

Preparation of other aqueous dispersions according to the prior art

A detailed list of ingredients and their amounts is set forth in Table 1. Polyol 1 or polyol 2 and H-polyol 4, H-polyol 5 or H-polyol 6, DMPA and NMP are charged in a reactor equipped with a thermometer, a stirrer and a condenser under a nitrogen atmosphere and at room temperature.

HMDI is added at 40 DEG C with homogenization of the mixture for about 30 minutes followed by stirring.

The reaction mixture is then heated and held at 60 DEG C for 30 minutes.

The reaction is carried out at 95-100 DEG C until the content of NCO groups in the prepolymer is equal to the theoretical value (approximately 1 hour).

The prepolymer is then cooled to approximately < RTI ID = 0.0 > 75 C < / RTI > and the neutralizing agent TEA is added with stirring.

After about 10 minutes and at an internal temperature of 65 < 0 > C, the prepolymer is dispersed in demineralized water under strong stirring at a temperature below 35 < 0 > C. The extrusion is carried out by adding a chain extender HH as described in Table 1 at a temperature below 35 < 0 > C.

The wetting agent ADD was added to the resulting polyurethane dispersion, which was then filtered through a 150 [mu] m canvas to a solid residue content of 35% by weight. The resulting dispersion appears to be clear and stable.

apply Example

The application examples show a comparison between the dispersion of the prior art and the coating treatment results carried out using the two dispersions according to the invention.

The mechanical, physical and chemical properties of glass or metal substrates coated with polyurethane dispersions were compared.

The contact angle on the coated aluminum substrate is measured using a Pocket Goniometer PGX. An integrated pump delivers droplets accurately in 0.5 μl steps and the built-in camera captures a drop of image to determine the static contact angle at the 'equilibrium'.

Example 2.1 2.2 2.3 2.4 2.5 ^* 2.6 ^* 2.7 ^* 2.8 ^* 2.9 ^* 2.10 ^* Polyol 1 - 134.4 - 130.4 124.9 - 144.4 - - - Polyol 2 138.7 - 134.6 - 43.6 148.6 - 131.0 147.0 146.7 H-polyol 1 26.6 27.5 - - - - - - - - H-polyol 2 - - 33.1 34.3 - - - - - - H-polyol 5 - - - - - 10.3 10.8 18.2 - - H-polyol 6 - - - - - - - - 13.1 - H-polyol 4 - - - - - - - - 31.1  DMPA 20.9 20.8 20.8 20.9 20.8 20.8 20.8 20.8 20.8 21.6  NMP 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0 80.0  HMDI 155.6 158.7 153.0 156.1 152.5 162.6 165.2 170.5 160.4 157.5  TEA 14.9 14.9 15.7 14.9 14.9 14.9 14.9 15.7 15.6 16.3  HH 47.8 48.7 49.1 47.9 46.8 49.6 50.7 54.7 51.4 50.5  ADD 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0  water 514.6 513.8 512.8 514.5 515.4 513.1 512.1 508.0 510.8 495.3 Particle diameter (nm) 55 54 32 55 63 43 45 30 65 40

^* Comparative Example

The hardness of the film was determined on a glass substrate according to the standard method ASTM D4366-95 (Standard Test Method for Hardness of Organic Coating by Pendulum Damping Test).

The hydrolysis resistance and ethanol resistance of the membrane were determined on glass by the standard method UNI EN 12720 (surface resistance to cold liquid).

Chemical resistance (NaOH, HCl) was determined by evaluation of the coated glass specimens after immersion in alkali or acid solution (1% NaOH or 5% HCl) for 2 minutes at a temperature of 55 ° C. The results are displayed in the following scale: 0 = worst, coating failure, 5 = best, no effect.

Adhesion on metal substrates (aluminum and electro-galvanized steel) was determined by standard method ASTM D3359-09 (standard test method for measuring adhesion by tape test). The results are displayed in the following scale: 0 = worst, coating failure, 5 = best, no effect.

The results are reported in Table 2.

It can be seen that the contact angle of Example 2.4 was significantly increased compared to all others that the coating was more hydrophobic.

The substrates coated with the dispersions of Examples 2.2 and 2.4 show that their ethanolicity is 6-7 times better than those produced without the use of hydrophobic polyols and even more so than prior art dispersions.

The H ₂ O (hydrolysis) resistance of the coating according to the invention is favorable.

Example 2.2 2.4 2.5 ^* 2.6 ^* 2.7 ^* 2.8 ^* 2.10 ^* Contact angle (°) 66.4 85.5 70.6 66.2 67.1 59.4 65.3 EtOH Property (min) 25 30 4 2 2 One One My H ₂ O property (minute) 120 50 30 60 30 10 240 Hardness
Koenig (seconds) 143 113 108 150 141 190 130 Adhesion
(Aluminum A36) ^** 5 5 One 0 0 0 0 Adhesion (EGI) 5 5 3 0 0 0 0 NaOH resistance 5 4 2 3 3 3 3 My HCl property 4 3 3 2 2 2 2

^* Comparative Example

^** Wet condition: The panel was immersed in water for 4 hours and the adhesion test was carried out within 2 minutes after the extraction.

Moreover, the substrates coated with the dispersions of Examples 2.2 and 2.4 exhibit good hardness and good adhesion as compared to those prepared with the prior art dispersions on both aluminum and steel substrates.

Considering the acid resistance / alkali resistance, the coatings made with the dispersions of the present invention appear to be better or equivalent than the coatings of the prior art.

Claims (10)

I) alcohol ROH wherein R is a branched or linear, saturated C ₄ -C ₃₀ alkyl chain or R is branched or linear, saturated C ₄ -C ₁₀ alkylphenyl radical, From 4 to 90% by weight of at least one hydrophobic polyol having a hydroxyl number of from 350 to 40, an average molar hydroxy functionality of from 2 to 3, obtained by reacting an aromatic diglycidyl ether of

(I)
Wherein R < ₁ > is the following radical (i)

(i)
And R ₂ and R ₃ are each independently methyl (Me), ethyl (Et) or hydrogen (H);
Or R &_lt; ₁ > is phenylene;
Or R < ₁ > is biphenylene;
Or R < ₁ > is the following radical (ii);
(ii)
II) 1 to 10% by weight of at least one anionic or potentially anionic polyol having at least two groups reactive with isocyanate groups and at least one carboxyl or carboxylate group;
III) 0 to 95% by weight of at least one linear polycarbonate diol having a number average molecular weight of 500 to 3,000;
IV) 0 to 95% by weight of at least one linear polyester diol having a number average molecular weight of 500 to 4,000;
V) from 0 to 95% by weight of at least one polyoxyalkylene diol selected from poly (oxypropylene) glycol and poly (oxytetramethylene) glycol,
As a prepolymer prepared by reacting at least one aliphatic, cycloaliphatic or aromatic polyisocyanate with a polyol mixture (P) containing 5 to 125 meq / 100 g of a neutralized anionic prepolymer containing a carboxyl group of a dry substance, By weight of an anionic polyurethane which is obtained by elongation of 20 to 50% by weight of anionic polyurethane,
Wherein the polyisocyanate and the polyol mixture (P) have a) a ratio of the sum of the isocyanate group NCO of the polyisocyanate and the total reactive -OH group of the polyol mixture (P) in the ratio of 1.2 to 2.3. The process according to claim 1 wherein the sum of components I), II), III), IV) and V) is at least 95% by weight of the polyol mixture,
From 0 to 5% by weight of other non-ionic polyols having a molecular weight of less than 1,000 and containing at least two hydroxyl groups. The aqueous dispersion of claim 2, wherein the sum of components I), II), III), IV) and V) is 100% by weight of the polyol mixture (P) of the prepolymer. 4. The aqueous dispersion of claim 3, wherein the sum of components I), II), III) and IV) is 100% by weight of the polyol mixture. The process according to claim 1, wherein the polyol mixture (P) comprises the at least one hydrophobic polyol I) obtained by the reaction of alcohol ROH wherein R is a branched or linear, saturated C ₆ -C ₂₂ alkyl chain, wherein R ₁ An aqueous dispersion of the following radical (i):

(i). The aqueous dispersion according to claim 5, wherein R ₂ and R ₃ are methyl groups (Me). The aqueous dispersion of claim 1, wherein the neutralized anionic prepolymer is prepared from at least one aliphatic or cycloaliphatic polyisocyanate having an average -NCO functionality of from 2.0 to 2.3. The method according to claim 1,
Component II) of the polyol mixture (P) is dimethylolpropanoic acid, dimethylolbutanoic acid or mixtures thereof;
Component III) of the polyol mixture (P) is a poly (hexamethylene carbonate) diol having a number average molecular weight of 800 to 2,000;
Component IV) of the polyol mixture (P) is based on adipic acid and / or phthalic acid and 1,6-hexanediol, ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, ≪ / RTI > and a number average molecular weight of from 3,000 to 3,000.
Aqueous dispersion. The aqueous dispersion according to any one of claims 1 to 8, wherein the polyol of the mixture (P) does not contain units derived from poly (oxyethylene) glycol. A coating composition comprising the aqueous dispersion according to any one of claims 1 to 8.