WO2001062816A1

WO2001062816A1 - Water-dispersible isocyanates used in the production of ultraphobic coatings

Info

Publication number: WO2001062816A1
Application number: PCT/EP2001/001393
Authority: WO
Inventors: Karsten Reihs; Daniel-Gordon Duff; Bernhard Jansen; Dieter RÜHLE; Juan GONZÁLEZ-BLANCO
Original assignee: Sunyx Surface Nanotechnologies Gmbh
Priority date: 2000-02-22
Filing date: 2001-02-09
Publication date: 2001-08-30
Also published as: EP1265939A1; EP1274806A1; WO2001062863A1; AU2001246427A1; AU2001248311A1

Abstract

The invention relates to ultrahydrophobic lacquers that are producible from aqueous lacquer dispersions.

Description

Water-dispersible isocyanates for the production of ultraphobic coatings

The present invention relates to water-dispersible isocyanates for the production of ultraphobic coatings.

Ultraphobic coatings are characterized by the fact that the contact angle of a drop of a liquid, usually water, lying on the surface is significantly more than 90 ° and that the roll angle does not exceed 10 °. The roll angle here is understood to be the angle of inclination of a basically planar but structured surface with respect to the horizontal, at which a standing

Water droplets with a volume of 10 μl are moved due to gravity when the surface is inclined.

Ultraphobic surfaces with a contact angle »90 ° and a roll angle <10 ° have a very high technical benefit because they e.g. with water but also with

Oil are not wettable. In this way, materials can be protected against the weather. Dirt particles adhere very poorly to these surfaces, and these surfaces are also self-cleaning. Self-cleaning is understood here to mean the ability of the surface to easily release dirt or dust particles adhering to the surface to liquids that flow over the surface.

There has been no shortage of attempts to provide such hydrophobic and oleophobic surfaces. It is already known to produce ultrahydrophobic coatings by using appropriate polymers in organic

Solvents applied dissolved (see Sasaki et. Al., Chem. Lett (1998) 4, 293, and JP-A (092799056 A2). However, such a procedure has the disadvantage that organic solvents have to be used, which is a complex Require reprocessing to avoid environmental pollution. The object of the present invention was therefore to provide an aqueous coating system which leads to ultra-hydrophobic coatings.

According to the invention, this is achieved by providing mixtures consisting of:

I) 0.1 to 50% by weight of one or more water-dispersible isocyanates obtainable by reaction of:

a) polyisocyanates of structure (I): Q [NCO] _n , (I)

in which n means: a number greater than or equal to 2,

b) monofunctional polyethers of structure (II): R, - [OR ₂ ] _m -OH (II) in which:

Ri: an alkyl radical of one to four carbon atoms,

R ₂ : An alkyl radical of the structure: - CHX- CHY-, in which X and Y are methyl and / or ethyl radicals or hydrogen with the proviso; that one of the substituents X and Y should always mean hydrogen,

m: a number between 3 and 25,

c) fluorinated alcohols of the general formula (III)

(CH _3. _M F _m ) - (CH _2-y F _y ) _z - (CH ₂ ) _n -OH, (III),

in the m for the number 1, 2 or 3,

y for the number 1 or 2,

z for an integer from 3 to 29, preferably 5 to 19, and

n for 0 or the number 1, 2, 3 or 4, preferably 1 or 2,

stand.

such as

d) optionally other auxiliaries and additives.

II) 1 to 80% by weight, preferably 10 to 50% by weight, of a dispersible, particulate material with a particle size in the range from 5 to 10 ⁶ nm, preferably from 10 to 10 ³ nm, preferably of inorganic material, particularly preferably from an oxide, hydrated oxide or nitrite of silicon, aluminum, titanium, zircon, cerium, tungsten, bismuth, boron, chromium, cobalt, nickel, iron, zinc, tin, tantalum and / or niobium, and

m) paint auxiliaries and water,

the amounts adding up to 100% by weight.

The present invention furthermore relates to the subject matter

A process for the preparation of a mixture according to claim 1, characterized in that it is obtainable by combination:

I) water-dispersible isocyanates, II) fine particulate materials and

III) Paint auxiliaries and water.

a) The following can be used as polyisocyanates of structure (I): aliphatic, cycloaliphatic, araliphatic, or aromatic isocyanates of NCO-

Functionality from 1.8 to 4.2. Preference is given to using polyisocyanates which have isocyanurate (and optionally also in a mixture with the uretdione) and / or allophanate and / or biuret and / or oxadiazine structures and, in a manner known per se, by appropriate “modification” from aliphatic, Cycloaliphatic, araliphatic or aromatic diisocyanates are accessible.

Essentially, modification products of hexamethylene diisocyanate and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane are preferred in a mixture with their higher molecular weight homologs obtained during the modification with an isocyanate content of 17 to 25% by weight. Particular preference is given to the corresponding isocyanurates obtainable by the trimerization reaction which is known per se and having an average NCO functionality of 3.2 to 4.2, and to the trimeric polyisocyanates which are essentially biuret structures and which are accessible by appropriate processes.

b) Polyether alcohols of structure (II) are monohydric polyalkylene oxide polyether alcohols having a statistical average of 2 to 70, preferably 2 to 60, polyalkylene oxide units, as are obtainable in a manner known per se by alkoxylation of suitable starter molecules.

Any monohydric alcohols in the molecular weight range from 32 to 150 g / mol can be used as starter molecules to produce these polyalkylene oxide polyether alcohols. Monofunctional aliphatic alcohols having 1 to 4 carbon atoms are preferably used as starter molecules. applies. The use of methanol or ethylene glycol ethonomethyl ether is particularly preferred. Alkylene oxides suitable for the alkoxylation reaction are, in particular, ethylene oxide, propylene oxide and butylene oxide, which can be used in the alkoxylation reaction in any order or in a mixture.

Less preferred are the polyalkylene oxide polyester ethers which are not described by the structure (II) and which are formed by reacting aliphatic dicarboxylic acids having 2 to 8 carbon atoms or their esters or acid chlorides with polyethers from the group of the polyethylene glycols, polypropylene glycols or their mixed polyether forms or simple mixtures both are accessible and have an average molecular weight below 10,000 g / mol, preferably below 3000 g / mol, and are terminated by hydroxyl functions.

Particularly suitable fluorinated aliphatic alcohols of structure (III) are fluorinated aliphatic alcohols with C ₄ -C ₃₄ , preferably C -C ₂₂ , particularly preferred fluorinated alcohols are those of the general formula (in)

(CH _3-m F _m ) - (CH _2-y F _y ) _z - (CH ₂ ) _n -OH (TU),

in the

m for the number 1, 2 or 3,

y for the number 1 or 2,

z for an integer from 3 to 29, preferably 5 to 19, and

n stands for 0 or the number 1, 2, 3 or 4, preferably 1 or 2. e) The auxiliaries and additives e) which may be present are, for example, catalysts or stabilizers known per se in polyurethane chemistry for the water-dispersible polyisocyanate preparations

A particulate material with a particle size in the range from 5 to 10 ⁶ nm, preferably from 10 to 10 ³ nm, is dispersed as component II in the mixtures according to the invention. The particle size is determined by light scattering or electron microscopy. This particulate material is preferably made from inorganic material, particularly preferably from an oxide, hydrated oxide or nitrite of silicon, aluminum, titanium, zircon, cerium, tungsten, bismuth, boron, chromium, cobalt, nickel, iron, zinc, tin, tantalum and / or niobium. The particles are preferably spherical. The particle surface is preferably rough, the depth of the unevenness preferably being more than 5% of the particle diameter, particularly preferably more than 20% of the particle diameter. The roughness can also be generated by agglomeration of primary particles into a larger particle group of 2 ... 1000 particles. The extraction of such particles is known to the person skilled in the art, and their production can be carried out, for example, in accordance with EP-A-0 599 136. They are marketed under the name Aerosile.

Is it also possible to use particulate material made of polymers, built up from monomers of component A, such as. B. polystyrene, and component B.

To produce the water-dispersible isocyanates I) according to the invention, components a), b), c) and optionally also d) can be combined in any order and allowed to react. It is preferred to introduce the isocyanate and add the other components in accordance with the reaction. The proportions (always 100% in total) are as follows: a) polyisocyanates of structure (I): 50 to 85% by weight b) mono-functional polyethers of structure (II): 10 to 35% by weight c) compounds of structure (ffl): 3 to 35% by weight ,

The quantitative ratio is designed by the person skilled in the art in such a way that

the water-dispersibility of the preparation is guaranteed, and the water-dispersible isocyanate contains sufficient isocyanate groups to crosslink to form a film.

To prepare the mixtures according to the invention from components I, LT and III, the particulate material II can be introduced directly into the aqueous isocyanate dispersion, preferably stirred in, or added dispersed in water to the already existing dispersion of the water-dispersible isocyanate.

The polymer dispersions according to the invention can contain customary paint auxiliaries, such as e.g. Leveling agents, adhesion promoters, etc. can be added.

The water-dispersible isocyanates I) are self-dispersing; i.e. they do not require any external emulsifiers or otherwise to disperse in water

Aids.

Of course, the manufacturing component b) can also be omitted.

Then the isocyanates thus produced must either be applied as such (possibly as a viscous liquid or melt), or in the form of a solution in an aprotic solvent and, if appropriate, in an aqueous dispersion

Use of external emulsifiers can be used.

This embodiment is naturally less preferred.

The addition of crosslinking reactants to the mixtures of components I), II) and III) according to the invention is also less preferred. these can in known polyesters and polyethers from polyurethane chemistry, however, also exist in known hydroxyl group-containing polyacrylate copolymers from the chemistry of aqueous two-component polyurethane coatings.

The mixtures of components I), II) and III) according to the invention can be applied to the surfaces to be coated using known methods. Spraying, knife coating or pouring of the aqueous dispersions according to the invention and dipping of the object to be coated are preferably suitable for this purpose. Surfaces of any kind, in particular plastic surfaces, wood, metal, paper, cardboard, cardboard or mineral surfaces can be coated with the dispersions according to the invention in an ultrahydrophobic manner. Preferably 0.05 to 2 mm of the dispersion according to the invention is applied per cm ² of surface to be coated and then dried at temperatures between 70 and 100 ° C. for several hours, preferably at least one day. The coatings produced in this way are distinguished by the fact that they are ultra-hydrophobic. This means that when it comes into contact with water or watery liquids, it will automatically roll off the surface.

Ultrahydrophobically coated surfaces in the sense of the invention are therefore characterized in that the contact angle of a drop of water or an aqueous one

Liquid. This property also has other hydrophilic substances such as Ethylene glycol, which lies on the surface, is clearly more than 90 °, in good cases close to 180 °, and the roll angle does not exceed 10 °.

Another object of the present invention is therefore the use of the mixtures according to the invention for the production of ultra-hydrophobic coatings or ultra-hydrophobic lacquers based on the mixtures according to the invention. These ultrahydrophobic coatings are characterized in particular by the fact that only aqueous dispersions are used for their production and no organic solvents are used.

Examples

Preliminary remarks

The coatings were applied using a film puller with a

Gap width of 120 μm on glass plates. After the volatile constituents had been evaporated off at room temperature, the coatings were cured in a forced-air drying cabinet.

The contact angles were measured with water drops with a volume of 10 μl, which are placed on the sample with a syringe. The static water edge angle was determined on a flat, horizontally aligned surface based on the silhouette. The roll angle is the inclination of the sample surface to the horizontal at which a water drop with a volume of 10 μl begins to move on the sample surface.

1. Water-dispersible isocyanate 1

80 parts by weight of a trimerization product of hexamethylene diisocyanate with an NCO content of 21.5% and 15 parts by weight of one

Polyethylene glycol monomethyl ether with a molecular weight of 350 and 5 parts by weight of foralkyl EOH 6N-LW (primary alcohol with a perfluorinated alkyl radical; product from Atochem; OHZ: 127 mg KOH / g). The reaction mixture is stirred at 75 ° C. until an NCO content of 15.0% is reached.

Water-dispersible isocyanate 2

83 parts by weight of a trimerization product of hexamethylene diisocyanate with an NCO content of 21.5% and 15 parts by weight of a polyethylene glycol monomethyl ether with a molecular weight of 350 and 2 parts by weight

Foralkyl EOH 6N-LW (primary alcohol with a perfluorinated alkyl radical; Product from Atochem; OHZ: 127 mg KOH / g) given. The reaction mixture is stirred at 75 ° C. until an NCO content of 16.0% is reached.

3. Water-dispersible isocyanate 3

65 parts by weight of a trimerization product of hexamethylene diisocyanate with an NCO content of 21.5% are initially charged and 20 parts by weight of a polyethylene glycol monomethyl ether with a molecular weight of 350 and 15 parts by weight of foralkyl EOH 6N-LW (primary alcohol with a perfluorinated alkyl radical; product of the company Atochem; OHZ: 127 mg KOH / g). The reaction mixture is stirred at 75 ° C. until an NCO content of 9.8% is reached.

4. Water-dispersible isocyanate 4

75 parts by weight of a trimerization product of hexamethylene diisocyanate with an NCO content of 21.5% are initially charged, and 15 parts by weight of a polyethylene glycol monomethyl ether with a molecular weight of 350 and 10 parts by weight of foralkyl EOH 6N-LW (primary alcohol with a perfluorinated alkyl radical; product of the company Atochem; OHZ: 127 mg KOH / g). The reaction mixture is stirred at 75 ° C. until an NCO content of 13.4% is reached.

5. Water-dispersible isocyanate 5

70 parts by weight of a trimerization product of hexamethylene diisocyanate with an NCO content of 21.5% and 20 parts by weight of one

Polyethylene glycol monomethyl ether with a molecular weight of 350 and 10 parts by weight of foralkyl EOH 6N-LW (primary alcohol with a perfluorinated alkyl radical; product from Atochem; OHZ: 127 mg KOH / g). The reaction mixture is stirred at 75 ° C. until an NCO content of 11.5% is reached. A thin film of the preparations described above, squeegee-coated on a glass plate, hardens without air bubbles in a few days when lying in the air and proves to be highly hydrophobic when water drops are applied.

The following two isocyanate prepolymers were prepared with component b) omitted:

Isocyanate prepolymer 1

100 parts by weight of a trimerization product of hexamethylene diisocyanate with an NCO content of 21.5% are initially charged and 112.9 parts by weight

Foralkyl EOH 6N-LW (primary alcohol with a perfluorinated alkyl radical; product from Atochem; OHZ: 127 mg KOH / g). The reaction mixture is stirred at 75 ° C. until an NCO content of 5.0% is reached. The reaction product is a whitish solid at room temperature, which must be melted or dissolved before use.

A thin film scraped onto a glass plate hardens in a few days due to the air humidity when exposed to air and proves to be highly hydrophobic when water drops are applied. The contact angle is 165 °, the roll angle is 3 °.

Isocyanate prepolymer 2

50 parts by weight of a mixture of the dimerization and trimerization product of hexamethylene diisocyanate in a weight ratio of 2/3 to 1/3 with an NCO content of 21.5% are initially charged and 56.5 parts by weight of Foralkyl EOH 6N - LW (product from Atochem; OHZ: 127 mg KOH / g). The

The reaction product is a whitish solid at room temperature, which must be melted or dissolved before use.

A thin film squeegee on a glass plate hardens in a few days due to the air humidity when exposed to the air and proves to be highly hydrophobic when water drops are applied. The contact angle is 169 °, the roll angle is 5 °.

Claims

claims

1. Mixtures for the production of ultraphobic coatings obtainable by

Combination :

I) water-dispersible isocyanates,

II) fine particulate materials and

III) Paint auxiliaries and water.

2. Mixtures for the production of ultraphobic coatings according to claim 1, in which water-dispersible isocyanates I) are used, which are obtainable by reaction of

a) polyisocyanates b) monofunctional polyethers c) fluorinated alcohols and d) optionally other auxiliaries and additives.

3. Water-dispersible isocyanates according to claim 1, which are obtainable by the reaction of:

a) polyisocyanates of structure (I):

Q [NCO] _n>

where n means: a number greater than or equal to 2

b) monofunctional polyethers of structure (II):

Rι- [OR ₂ ] _m -OH (II)

in which mean: Ri: an alkyl radical of one to four carbon atoms,

R ₂ : An alkyl radical of the structure: - CHX- CHY-, in which X and methyl and / or ethyl radicals or hydrogen mean with the proviso; that one of the substituents X and Y should always mean hydrogen,

m: a number between 3 and 25,

c) fluorinated alcohols of the general formula (III)

(CH _3-m F _m ) - (CH _2. _Y F _y ) _z - (CH ₂ ) _n -OH, (III),

in the

m for the number 1, 2 or 3,

y for the number 1 or 2,

z for an integer from 3 to 29, preferably 5 to 19, and

n represents 0 or the number 1, 2, 3 or 4, preferably 1 or 2,

such as

d) optionally other auxiliaries and additives.

4. Mixtures according to claim 1, characterized in that Aerosil or Ni (OH) _{2 is} used as the particulate material.

5. Use of the mixtures according to claim 1 for the production of ultrahydrophobic coatings.

6. Use according to claim 5 for the production of ultra-hydrophobic lacquer coatings on substrates.

7. Mixtures for the production of ultraphobic coatings obtainable by combination:

I) water-dispersible isocyanates,

II) fine particulate materials and

III) Paint auxiliaries and water.

8. A method for producing ultraphobic coatings according to claim 1, in which water-dispersible isocyanates I) are used, which are obtainable by reaction of: