WO2004055111A2

WO2004055111A2 - Water-repellent additive, water-repellent sheet material and a method for imparting water repellency

Info

Publication number: WO2004055111A2
Application number: PCT/EP2003/013245
Authority: WO
Inventors: Daniel Jocham; Tatjana Javor; Arthur Schwesig
Original assignee: Ami - Agrolinz Melamine International Gmbh
Priority date: 2002-12-16
Filing date: 2003-11-25
Publication date: 2004-07-01
Also published as: AU2003292111A8; AU2003292111A1; DE10260377A1; WO2004055111A3

Abstract

The invention relates to a water-repellent additive for aminoplast laminates, characterised in comprising at least one siloxane compound as an aqueous dispersed system, in particular, in the form of an emulsion or dispersion. The water-repellant laminate obtained thus has excellent properties, combining, in an advantageous manner, water-repellant properties with the positive properties of the aminoplasts such as scratch resistance, flame resistance or chemical inertness.

Description

Hydrophobing additive, hydrophobized sheet and a method for hydrophobing

The invention relates to a water repellent additive for aminoplast laminates; the invention further relates to a hydrophobized sheet and a method for producing a hydrophobized sheet for an aminoplast laminate.

Aminoplasts in the context of the present invention are those resins which contain melamine, urea, dicyandiamide, cyanamide, guanamine, sufonamide, aniline or substituted melamines and ureas or mixtures of these components as the amine component.

Aminoplast laminates in the sense of the invention are understood to mean those laminates in which one or more absorbent sheetlike structures impregnated with aqueous aminoplast precondensates are pressed to form a multilayer laminate and are thereby fully cured.

Due to their excellent chemical and mechanical properties, aminoplast laminates are ideally suited for applications in which, among other things, high demands are placed on scratch resistance, flame resistance, mechanical stability, gloss, environmental friendliness and chemical inertness. For special applications in the interior, for example in the sanitary or kitchen area, but especially for the entire area of outdoor applications, the permanently water-repellent, that is to say hydrophobized, property of the laminate surfaces is of crucial importance.

The methods known from the prior art for making aminoplast laminates resistant to the effects of temperature, moisture and light have decisive disadvantages.

DE 3630315 AI, for example, describes a method in which a protective coating of acrylic resin is applied to a paper web impregnated with a melamine-formaldehyde resin is doctored and the paper web is pressed into a laminate with the carrier after forming a closed protective layer.

Similar lacquer coatings are described, for example, in DE 1 937 758 AI, the top lacquer layer consisting of a radiation-curable mixture of melamine-formaldehyde resin and acrylate resin, and the support coated in this way is then pressed.

US-A 4801495 also describes the application of a radiation-curable acrylate lacquer layer to a support impregnated with aminoplast resin. After the lacquer layer has been formed by electron beam curing, it is pressed into the laminate.

The disadvantage of such closed lacquer coatings is that they do not have sufficient scratch resistance and furthermore do not have the required chemical inertness, for example with respect to organic solvents or cleaning agents. In addition, despite the netting, a good adhesive strength is often not achieved between the impregnated support and the topcoat layer, so that the weather-resistant layer either comes off again or is mechanically destroyed.

The most serious disadvantage, however, is that when a lacquer coating is applied to a fabric impregnated with an aminoplast, the excellent chemical and mechanical properties of the aminoplast are covered by the closed lacquer film and therefore cannot be used in the laminate.

It was therefore the task of developing a hydrophobizing agent for aminoplasts which does not have the disadvantages mentioned.

In addition, it is crucial that the systems existing in the industry for the production of laminate can be used without costly retrofitting, such as necessary for EX protection.

This means that the hydrophobizing agents can be applied easily and, when they are subsequently pressed into the laminate, do not cause any optical changes, such as clouding, discoloration or dulling of the laminate surface. A hydrophobization additive according to the invention for aminoplast laminates has unexpected properties which meets all of these requirements if it is in the form of an aqueous disperse system, in particular an emulsion or a dispersion, with at least one siloxane compound. The water repellent additive can e.g. B. by spraying onto the aminoplast sheet to be impregnated.

As the carbonyl compound, the aminoplast resins can be aldehydes of chain length Ci to Cio or mixtures of this chain length of various aldehydes, such as, for example, formaldehyde, acetaldehyde, trimethylolacetaldehyde, acrolein, benzaldehyde, furfural, glyoxal, glutaraldehyde, phthalaldehyde, terephthalaldehyde, isobutyraldehyde, acetone or ketones, for example Contain methyl ethyl ketone and diethyl ketone. In particular, formaldehyde can be used. Aminoplast resins can also be etherified, for example with methanol, it being possible for the amino resins to be partially etherified. If necessary, they can also contain modifiers such as plasticizers.

Aminoplast resins are processed further in the form of aqueous solutions, so-called aqueous aminoplast precondensates. The aqueous aminoplast precondensates usually contain additives such as hardeners, wetting agents or separating agents.

It is also possible to carry out the pressing with one or more intermediate layers such as, for example, core papers or one or more carrier materials, for example pressboard.

The aqueous aminoplast precondensate used for the impregnation of the fabric can, for. B. contain a UV additive. For example, a UV additive containing a sterically hindered nitroxyl compound which is soluble in an aqueous aminoplast precondensate and optionally additionally a non-radical, sterically hindered amine and optionally a UV absorber which is soluble in an aqueous aminoplast precondensate from the group of ortho-hydroxyphenylbenzotriazoles or a substituted 1, 3,5-triazine used. 4-Hydroxy-2,2,6,6-tetramethylpiperidinyloxy is particularly preferred as the nitroxyl compound and sodium 3- (2H-benzotriazol-2-yl -) - 5-sec-butyl-4- is particularly preferred as the UN absorber. hydroxybenzenesulfonate used.

The absorbent sheet preferably contains cellulose and / or lignocellulose and is, for example, in the form of paper, cardboard, woven or non-woven, wood veneer, wood fiber board or wood chipboard.

The embodiment of the siloxane compound according to the invention comes from the group of chain-shaped siloxane polymers of the general formula:

R R

I I

R - [Si -O] "-Si -R (I)

I I

R R

in which

R = alkyl, alkenyl, isoalkyl, cycloalkyl with 1 to 18 C atoms and / or aryl groups with 6 to 12 C atoms;

Methoxy, ethoxy, 2-methoxyethoxy and / or propoxy groups; Hydroxyl, hydroxyethoxypropyl and / or hydroxyalkyl groups; Aminopropyl functional groups of the formula (CH ₂ ) ₃ -NH ₂ -, (CH ₂ ) ₃ -NHR'- or (CH ₂ ) ₃ -NH- (CH ₂ ) ₂ -NH ₂ - or - (CH ₂ ) ₃ -NH (CH ₂ ) ₂ -NH- (CH ₂ ) ₂ -NH ₂ wherein R 'is a linear, branched or cyclic alkyl group having 1 to 18 C atoms or an aryl group having 6 to 12 C atoms;

Trifluoropropyl, aryl, tetramethylpiperidinyloxypropyl and / or hydroxyl groups

and where n = 5 to 500, preferably 10 to 100.

Silanol-terminated polydimethylsiloxanes, silanol-terminated diphenylsiloxanes, silanol-terminated polytrifluoropropylmethylsiloxanes, silanol-terminated diphenylsiloxane-dimethylsiloxane copolymers or hydroxyl-terminated polydimethylsiloxanes are particularly preferred. Also particularly preferred are aminopropyl-terminated polydimethylsiloxanes or aminopropylmethylsiloxane-dimethylsiloxane copolymers.

Cyclic siloxane compounds may optionally also be present in the water repellent additive.

If the siloxane compounds are in the form of aqueous emulsions, nonionic emulsifiers such as polyethylene glycols, polypropylene glycols or also block copolymers of PEG and PPG are preferably used as emulsifiers. The water repellent additive can optionally additionally contain dispersants.

The siloxane compound should be evenly and finely distributed in the hydrophobization additive so that when the hydrophobization additive is subsequently sprayed onto the impregnated fabric, a uniform distribution of the siloxane compound in the aminoplast precondensate is ensured.

Preferred aminoplast resins are melamine resins, urea resins or melamine-urea resins.

The amount of the siloxane compound in the hydrophobization additive is preferably 0.1 to 10% by weight, particularly preferably 0.5 to 1% by weight, based on the total amount of hydrophobization additive.

The molecular weights of the siloxane compounds contained in the water repellent additive are approximately 400 to 40,000 g / mol, preferably approximately 1000 to 4000 g / mol.

For the production of the aminoplast laminate according to the invention, a dry, absorbent sheet is impregnated with an aqueous, preferably a UV additive and optionally additives such as, for example, wetting or release agents and plasticizers, and aminoplast precondensate containing hardeners.

The impregnated fabric is dried before further processing. It is possible to soak the dried fabric again with the aqueous aminoplast precondensate and then to dry it again. After drying, the hydrophobicizing additive according to the invention is sprayed onto the surface of the impregnated fabric. The amount of siloxane compound applied is about 400-800, preferably about 500-600 mg / m ² . Spraying can be done from above using conventional spray systems in combination with laminate systems.

In a method for producing a hydrophobicized aminoplast laminate, the hydrophobicized fabric is dried after the hydrophobicizing additive has been sprayed on. The hydrophobized sheet is then pressed, for example with other sheets impregnated with aminoplast precondensate and dried, under conventional pressure and temperature conditions to form a multilayer laminate, and is fully cured in the process. The pressing can also be carried out with one or more intermediate layers, such as core papers or one or more carrier materials, such as pressboard. The aminoplast precondensate advantageously contains at least one UV additive.

The hydrophobized laminate thus obtained has excellent properties. It advantageously combines permanent water-repellent properties with the positive properties of the aminoplast, such as scratch resistance, flame resistance or chemical inertness.

The chemical incorporation of the hydrophobizing additive into the aminoplasts, which is achieved via the functional groups of the siloxane compound, is particularly advantageous and ensures excellent adhesive strength between the components.

Another advantage is that the water repellent additive according to the invention can be used in conventional laminate systems without any retrofitting effort, since it is free of organic solvents and therefore no harmful or explosive vapors are released during the pressing and drying process.

Unexpectedly, the laminate sprayed with the water repellent additive according to the invention also has the optically intact surface required for laminates, that is to say a glossy, color-fast and stain-free surface. This is unexpected, since under the pressure and temperature conditions used in the pressing, the silicon loxane must be feared from the laminate surface, which would no longer guarantee the optical properties required for decorative surfaces.

The laminate according to the invention obtained in this way can be used both for exterior and for interior applications, for example for furniture surfaces, for example in the sanitary or kitchen area, for floors or facade designs of any kind.

If the laminates are mainly used outdoors, the use of an aminoplast precondensate containing a UV additive (e.g. Weathe®dure Ruvln, Agrolinz Melamin Italia) in combination with the hydrophobic additive can result in increased weather resistance.

The effect of the water repellent additive according to the invention is illustrated using three examples:

Example 1:

waterproofing

500 g of melamine / formaldehyde resin (from Agrolinz Melamin Italia) are dissolved in 500 g of water, then 3 g of the wetting agent Melpan NUL 17 and 6 g of the hardener Melpan A462 are added. This aqueous aminoplast precondensate mixture is stirred until a clear solution is obtained.

This solution is used to impregnate a brown decorative paper (density 80 g / m ²⁾ . The impregnated decorative paper is then left in the air for one hour, then for 90 seconds at 120 ° C. in a drying cabinet to a residual moisture of about 7-8% by weight. This one-time impregnation resulted in a total resin application of approximately 140% by weight based on the mass of the dry brown decorative paper originally used.

The decorative paper impregnated and dried in this way is then sprayed with the water repellent additive, a 1% aqueous diaminopropyldimethylsiloxane dispersion, the amount of siloxane dispersion being 500-600 mg / m ² . After air drying for 10 minutes, this impregnated and sprayed decorative paper is pressed with four layers of a core paper impregnated with melamine / formaldehyde resin and a backing paper also impregnated with a melamine / formaldehyde resin to form a multilayer laminate. The following press conditions are used: press duration 2 min, press temperature 150 ° C, press pressure 80 kg / cm ² , recooling to 70 ° C.

The laminate obtained in this way has a highly glossy, transparent surface.

In comparison to a laminate produced in an analogous manner but not sprayed, neither a color difference nor a difference in the optical properties could be determined.

The size of the contact angle of water serves as a measure of the hydrophobization. The higher the contact angle, the better the water-repellent properties of a surface. The contact angle of the hydrophobized laminate thus obtained is measured in comparison to a non-sprayed laminate (Contact Angle System OCA, Dataphysics). The contact angle of the hydrophobic laminate was 110 °, while that of the non-hydrophobic laminate was 65 °.

Example 2:

weatherability

500 g of a melamine formaldehyde resin containing a UV additive (Weathe @ dure Ruvln, Agrolinz Melamin Italia) are dissolved in 500 g of water, then 3 g of the wetting agent Melpan Null7 and 6 g of the hardener Melpan A462 are added. The aqueous aminoplast precondensate mixture obtained is stirred until a clear solution is obtained.

A brown decorative paper (density 80 g / m ² ) is impregnated with this solution and then air-dried for 1 hour, then for 90 seconds at 120 ° C. in a drying cabinet to a residual moisture content of about 7-8% by weight.

The decorative paper thus obtained is sprayed with the hydrophobization additive, a 1% aqueous diaminopropyldimethylsiloxane dispersion, the amount of siloxane dispersion being 500-600 mg / m ² . After air drying for 10 minutes, this is impregnated and sprayed decorative paper with four layers of a kraft core paper impregnated with melamine / formaldehyde resin and with a counter paper also impregnated with a melamine / formaldehyde resin to form a multilayer laminate. The following press conditions are used: press duration 2 min, press temperature 150 ° C, press pressure 80 kg / cm ² , recooling to 70 ° C.

The laminate thus obtained has a highly glossy, transparent surface. In comparison to a laminate produced in an analogous, but unsprayed, laminate, neither a color difference nor a difference in the optical surface quality could be determined.

The modified, UV-stabilized and hydrophobized laminate thus obtained is artificially weathered for 2000 hours (WeatherOmeter CPS 1200). Loss of gloss and optical integrity are used as criteria for assessing the weather resistance.

The modified laminate is compared with an unmodified laminate or an only UV stabilized but not hydrophobic laminate.

A loss of gloss of 54% was observed for the unmodified laminate, while that for the UV-stabilized and hydrophobized LariKnat was only 5%. In the case of only UV stabilized but not hydrophobic laminate, the loss of gloss was 11%.

In the optical assessment, a partial lightening / chalking was found in the unmodified laminate. In contrast, no optical change could be found in the UV-stabilized and hydrophobized laminate. Example 3:

Graffiti test

If you spray an HPL laminate with a weatherproof acrylic film according to the current state of the art with the graffiti paint spray and then clean the traces of the paint with organic solvents, the acrylic surface of the laminate is destroyed.

Analogously to Example 1, a hydrophobized multilayer laminate was produced from papers impregnated with melamine / formaldehyde resin. An acrylic varnish (Motip Dupli Group) was sprayed onto this hydrophobized laminate.

A clear beading effect of the acrylic varnish was observed with the hydrophobized laminate. After an exposure time of 5 minutes or 16 hours, the traces of lacquer could be easily removed with ethanol as well as with acetone without residues or impairment of the surface appearance. In comparison, laminate covered with an acrylic film becomes matt due to the chemical attack of the acetone during the graffiti test.

Claims

claims

1. Water repellent additive for aminoplast laminates, characterized in that it contains at least one siloxane compound as an aqueous disperse system, in particular an emulsion or a dispersion.

2. Water repellent additive according to claim 1, characterized in that the at least one siloxane compound from the group of chain-shaped siloxane polymers of the general formula (I)

R R

I I

R - [Si -O] _n -Si -R (I)

I I

R R

is where

Methoxy, ethoxy, 2-methoxyethoxy and / or propoxy groups; Hydroxyl, hydroxyethoxypropyl and / or hydroxyalkyl groups; Aminopropyl functional groups of the formula (CH ₂ ) ₃ -NH ₂ -, (CH ₂ ) ₃ -NHR'- or (CH ₂ ) ₃ -NH- (CH ₂ ) ₂ -NH ₂ - or - (CH ₂ ) ₃ -NH (CH ₂ ) ₂ -NH- (CH ₂ ) ₂ -NH ₂ wherein R is a linear, branched or cyclic alkyl group with 1 to 18 C atoms or an aryl group with 6 to 12 C atoms;

Trifluoropropyl, aryl, tetramethylpiperidinyloxypropyl and / or hydroxyl groups and where n = 5 to 500, preferably 10 to 100.

3. Water-repellent additive according to claim 1 or 2, characterized in that the at least one siloxane compound is a silanol-terminated polydimethylsiloxane, a silanol-terminated diphenylsiloxane, a silanol-terminated polytrifluoropropyl-methylsiloxane, a silanol-terminated diphenylsiloxane-dimethylsiloxane a hydroxyl-terminated polydimethylsiloxen, an aminopropyl-terminated polydimethylsiloxane or an aminopropylmethylsiloxane-dimethylsiloxane copolymer.

4. Water repellent additive according to at least one of the preceding claims, characterized in that melamine resins, urea resins or melamine-urea resins serve as the aminoplast.

5. Water repellent additive according to at least one of the preceding claims, characterized in that the amount of siloxane compound contains 0.1 to 10% by weight, based on the total weight of the water repellent additive.

6. Water repellent additive according to at least one of the preceding claims, characterized in that the amount of siloxane compound contains 0.5 to 1% by weight, based on the total weight of the water repellent additive.

7. Water repellent additive according to at least one of the preceding claims, characterized in that the siloxane compound has a molecular weight of 400 to 40,000 g / mol.

8. Water repellent additive according to at least one of the preceding claims, characterized in that the siloxane compound has a molar mass of 1000 to 4000 g / mol.

9. Water repellent additive according to at least one of the preceding claims, characterized in that when the siloxane compound is present in an aqueous emulsions, nonionic emulsifiers, in particular polyethylene glycols, polypropylene glycols or also block copolymers of PEG and PPG, are used as emulsifiers; additional dispersants are used as a dispersion.

10. Hydrophobic sheet, impregnated with an aminoplast precondensate and sprayed with the hydrophobic additive according to at least one of the preceding claims and dried.

11. A hydrophobic fabric according to claim 10, characterized in that the aminoplast precondensate contains a UV additive, in particular a nitroxyl compound.

12. A hydrophobic fabric according to claim 10 or 12, characterized in that about 400-800 mg / m ^{2 of} siloxane compound are applied, in particular sprayed, to the surface of the impregnated fabric.

13. A hydrophobic fabric according to at least one of claims 10 to 12, characterized in that about 500-600 mg / m of siloxane compound are applied, in particular sprayed, to the surface of the impregnated fabric.

14. A method for hydrophobizing a fabric for producing a hydrophobized aminoplast laminate, characterized in that a fabric impregnated with an aminoplast resin is sprayed with the hydrophobizing agent according to one of the preceding claims, the fabric is dried and optionally with one or more intermediate layers and optionally one or several carrier materials are pressed and fully cured.

15. The method according to claim 14, characterized in that the aminoplast resin contains a UV additive.