DE102011005334A1 - Preparing hydrophobic melamine-/formaldehyde resin foam, useful e.g. in all types of vehicles on land, water and in air and space, comprises washing melamine-/formaldehyde resin foam with water, squeezing water and drying the washed foam - Google Patents

Abstract

Preparing hydrophobic melamine-/formaldehyde resin foam, comprises washing the melamine-/formaldehyde resin foam with water, squeezing water and drying the washed foam. An independent claim is included for the hydrophobic melamine-/formaldehyde resin foam, obtained by the above process.

Description

The invention relates to a process for producing hydrophobic melamine / formaldehyde resin foams.

From the U.S. Pat. No. 6,607,817 It is known that one can reduce the liquid absorption of melamine / formaldehyde resin foams by impregnation with suitable chemicals and water or oil repellent equip. The oleophobicizing agent is called fluorocarbon resin which, in addition to the oil-repellent effect, also has hydrophobic properties.

From the DE-A-100 11 388 is known as Oleophobierungsmittel use fluorocarbon resin Dipolit ^® 480 from Rotta and Dipolit ^® 480 diluted in water and applied by wet impregnation.

From the WO-A-2008/37600 It is known to use as a Oleophobierungsmittel a mixture of fluorocarbon resin and modified polyisocyanate, so that the melamine resin foam is leaching resistant over a longer period.

The aforementioned methods leave much to be desired.

The present invention was therefore based on the object to remedy the aforementioned disadvantages.

Accordingly, there has been found a process for producing hydrophobic melamine / formaldehyde resin foams, which comprises washing melamine / formaldehyde resin foams with water, squeezing out the water and drying the washed foam.

The process according to the invention can be carried out as follows:
Melamine / formaldehyde resin foams in any desired shape and size can be discontinuous or continuous at a temperature of 5 to 95 ° C, preferably 10 to 70 ° C, more preferably 15 to 50 ° C, especially 18 to 35 ° C, most preferably at Ambient temperature or room temperature and a pressure of 0.001 to 10 bar, preferably 0.1 to 2 bar, more preferably at atmospheric pressure (atmospheric pressure) with 1 to 1000 ml, preferably 2 to 100 ml, more preferably 2 to 50 ml of water per cm ³ Washed melamine / formaldehyde resin foam and pressed and then at a temperature of 20 to 200 ° C, preferably 50 to 150 ° C, more preferably 80 to 120 ° C and a pressure of 0.001 to 1 bar, preferably 0.01 to 1 bar, particularly preferably dried from 0.05 to 1 bar.

In the discontinuous mode of operation, the procedure is as follows:
Melamine / formaldehyde resin foams may be in the form of powder, flakes or as a block 1 to 1,000 times, preferably 2 to 100 times, more preferably 2 to 30 times, in particular 2 to 15 times with in each case 1 to 1000 ml, preferably 1 to 100 ml, more preferably 2 to 10 ml of water are washed per cm ^{3 of} melamine / formaldehyde resin foam. For this purpose, the melamine / formaldehyde resin foams can be immersed for example in a water bath. The specimens may be left in the water bath for several hours or removed after a few seconds. A longer residence time in the water bath favors a reduction of the cleaning cycles. After removal from the water bath, the water by mechanical compression or by vacuum filtration, z. B. with the help of a Büchnertrichters (suction) can be removed. This washing and pressing process can be carried out several times in succession. The washing with water can take place several times without squeezing the washing water, preferably the pressing is carried out at least after the last washing process, more preferably, however, the pressing takes place after all washing operations. The subsequent drying can be carried out under reduced pressure, preferably 0.001 to 1 bar, preferably 0.01 to 1 bar, particularly preferably 0.05 to 1 bar and elevated temperature, 20 to 200 ° C, preferably 50 to 150 ° C, more preferably 80 to 120 ° C, preferably to constant weight, however, the extrusion is carried out after all washing operations.

In the continuous driving, one proceeds as follows:
Melamine / formaldehyde resin foams in the form of powder, flakes or as a block can be washed continuously with 1 to 1000 ml, preferably 2 to 100 ml, particularly preferably 2 to 50 ml of water per cm ^{3 of} melamine / formaldehyde resin foam. For this purpose, the melamine / formaldehyde resin foams can for example be placed in a mold which is open at the top and bottom. The openings are preferably provided with a net to prevent falling out of the sample body in the subsequent washing process. The water flow can be from one end of the mold; the other end serves as a drain. The sample in the middle is usually continuously supplied with water, so that the water can be homogeneously distributed throughout the sample. Complete water wetting of the entire foam body is preferred in order to achieve as complete a water repellency as possible. The washing with water can preferably be carried out without squeezing the washing water. The subsequent drying can generally be carried out under reduced pressure, preferably 0.001 to 1 bar, preferably 0.01 to 1 bar, particularly preferably 0.05 to 1 bar and elevated temperature, 20 to 200 ° C, preferably 50 to 150 ° C, particularly preferably 80 to 120 ° C, preferably to constant weight.

The compression of the washed melamine / formaldehyde resin can be carried out by all methods known to the person skilled in the art. For example, rollers, calenders, double belts or punches can be used as pressure-giving bodies. The melamine / formaldehyde resin foam is usually pressed to 1 to 80%, preferably 2 to 50%, particularly preferably 3 to 30% by volume.

As water is any water so distilled water, desalted or teilentsalztes water, spring water, tap water, river water, rain water, drinking water, industrial water, groundwater, seawater, wastewater, distilled, demineralized water or mixtures thereof, preferably distilled, demineralized water or mixtures thereof.

The temperature of the water may be 5 to 90 ° C, preferably 10 to 70 ° C, particularly preferably 15 to 50 ° C.

The melamine / formaldehyde resin foams which can be prepared according to the invention are generally not oleophobic and are therefore outstandingly suitable for receiving non-polar compounds, such as, for example, As oils, without affecting the fire safety of the foam negative. Furthermore, as a rule, the density of the foam does not rise, they are resistant to washing out and show no change in the reaction to fire.

• 1. Herstellen einer Lösung oder Dispersion enthaltend ein Vorkondensat des herzustellenden Schaumstoffs und gegebenenfalls weitere Zusatzkomponenten (Z),
• 2. Aufschäumen des Vorkondensates im Trägermaterial durch Erhitzen der Lösung oder Dispersion aus Schritt (2) auf eine Temperatur oberhalb der Siedetemperatur des Treibmittels, um einen Schaumstoff zu erhalten, sowie gegebenenfalls vorzugsweise,
• 3. Trocknung des in Schritt (2) erhaltenen Schaumstoffes,
• 4. Waschen des in Schritt (3) erhaltenen Schaumstoffes mit Wasser und anschließender Trocknung.

The foams and moldings according to the invention can be prepared as follows:

• 1. preparing a solution or dispersion comprising a precondensate of the foam to be produced and optionally further additional components (Z),
• 2. foaming the precondensate in the carrier material by heating the solution or dispersion from step (2) to a temperature above the boiling point of the propellant in order to obtain a foam, and optionally preferably,
• 3. drying of the foam obtained in step (2),
• 4. Washing the foam obtained in step (3) with water and subsequent drying.

Suitable foamable reactive resin are melamine-formaldehyde resins, more preferably melamine / formaldehyde resins, which form an open-celled foam having a density of ≦ 25 g / l, ie from 1.6 to 25 g / l, preferably from 2 to 15 g / l preferably 3 to 23 g / l, in particular 4 to 12 g / l and / or a pore size between 10 and 1000 microns, preferably 50 and 300 microns leads.

Manufacturing process for melamine / formaldehyde resins and their foams are for example WO-A-01/94436 known.

The individual process steps and the various possible variations are explained in more detail below.

The melamine-formaldehyde precondensates generally have a molar ratio of formaldehyde to melamine 5: 1 to 1.3: 1, preferably 3.5: 1 to 1.5: 1.

In addition to melamine, these melamine / formaldehyde condensation products can condense up to 50% by weight, preferably up to 20% by weight, of other thermoset formers and, in addition to formaldehyde, up to 50% by weight, preferably up to 20% by weight, of other aldehydes contain. However, preference is given to an unmodified melamine / formaldehyde condensation product.

Examples of thermoset formers which can be used are alkyl- and aryl-substituted melamine, urea, urethanes, carboxamides, dicyandiamide, guanidine, sulfurylamide, sulfonamides, aliphatic amines, glycols, phenol and derivatives thereof.

As aldehydes, for example, acetaldehyde, trimethylolacetaldehyde, acrolein, benzaldehyde, furfural, glyoxal, glutaraldehyde, phthalaldehyde and terephthalaldehyde can be used. Further details about melamine / formaldehyde condensation products can be found in Houben-Weyl, Methods of Organic Chemistry, Vol. 14/2, 1963, pages 319 to 402 ,

In a further preferred embodiment, the melamine / formaldehyde precondensate is present in the mixture in an amount of from 55 to 85% by weight, preferably from 63 to 80% by weight.

In the preparation of the melamine / formaldehyde precondensate, alcohols, for example methanol, ethanol or butanol, may be added in order to obtain partly or completely etherified condensates. The formation of the ether groups can influence the solubility of the melamine / formaldehyde precondensate and the mechanical properties of the fully cured material. As a dispersant or emulsifier anionic, cationic and nonionic surfactants and mixtures thereof can be used.

Examples of suitable anionic surfactants are diphenylene oxide sulfonates, alkane and alkylbenzenesulfonates, alkylnaphthalenesulfonates, olefinsulfonates, alkyl ether sulfonates, fatty alcohol sulfates, ether sulfates, α-sulfofatty acid esters, acylaminoalkanesulfonates, acylisothionates, alkyl ether carboxylates, N-acyl sarcosinates, alkyl and alkyl ether phosphates. As nonionic surfactants, alkylphenol polyglycol ethers, fatty alcohol polyglycol ethers, fatty acid polyglycol ethers, fatty acid alkanolamides, ethylene oxide / propylene oxide block copolymers, amine oxides, glycerol fatty acid esters, sorbitan esters and alkylpolyglycosides can be used. As cationic emulsifiers z. B. Alkyltriammoniumsalze, Alkylbenzyldimethylammoniumsalze and Alkylpyridiniumsalze be used.

The dispersants or emulsifiers can be used in amounts of 0.2 to 5 wt .-%, based on the melamine / formaldehyde precondensate.

The dispersants or emulsifiers and / or protective colloids can in principle be added to the crude dispersion at any time, but they may also already be present in the solvent upon introduction of the microcapsule dispersion.

Acidic compounds which catalyze the further condensation of the melamine resin can be used as hardeners. The amount of these hardeners is generally 0.01 to 20 wt .-%, preferably 0.05 and 5 wt .-%, each based on the precondensate. Suitable acidic compounds are inorganic and organic acids, for example selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, oxalic acid, toluenesulfonic acids, amidosulfonic acids, acid anhydrides and mixtures thereof.

Depending on the choice of melamine / formaldehyde precondensate, the mixture contains a propellant. In this case, the amount of blowing agent in the mixture usually depends on the desired density of the foam.

In principle, both physical and chemical blowing agents can be used in the process according to the invention ( Encyclopedia of Polymer Science and Technology, Vol. I, 3rd ed., Chapter Additives, pages 203 to 218, 2003 ).

Suitable blowing agents are "physical" or "chemical" blowing agents. By "physical" blowing agent is meant here volatile liquids or compressed gases which obtain their property as blowing agent by physical treatment (eg temperature, pressure). The term "chemical" blowing agent is understood here to mean those blowing agents which obtain their property as blowing agents by chemical reaction or chemical decomposition with release of gas.

Suitable "physical" blowing agents are, for example, hydrocarbons, such as pentane, hexane, halogenated, in particular chlorinated and / or fluorinated hydrocarbons, for example methylene chloride, chloroform, trichloroethane, chlorofluorohydrocarbons, hydrochlorofluorocarbons (HCFCs), alcohols, for example methanol, ethanol, n- or iso-propanol, ethers, ketones and esters, for example methyl formate, ethyl formate, methyl acetate or ethyl acetate, in liquid form or air, nitrogen and carbon dioxide as gases.

As "chemical" propellants are, for example, isocyanates in admixture with water, being released as an effective blowing agent carbon dioxide. Further, carbonates and bicarbonates are suitable in admixture with acids which also produce carbon dioxide. Also suitable are azo compounds, such as. B. azodicarbonamide.

In a preferred embodiment of the invention, the mixture additionally contains at least one propellant. This blowing agent is in the mixture in an amount of 0.5 to 60 wt .-%, preferably 1 to 40 wt .-%, particularly preferably 1.5 to 30 wt .-% based on the melamine / formaldehyde precondensate, in front. It is preferred to add a physical blowing agent having a boiling point between 0 and 80 ° C.

In a further embodiment, the mixture contains, in addition to the melamine / formaldehyde precondensate of the foam to be produced, also an emulsifier and optionally a hardener and optionally a blowing agent.

In a further embodiment, the mixture is free of further additives. For some purposes, however, it may be favorable, 0.1 to 20 wt .-%, preferably 0.1 to 10 wt .-%, based on the melamine / formaldehyde precondensate, of conventional additives, such as dyes, flame retardants, UV Stabilizers, agents to reduce the fire gas toxicity or to promote the charring add.

It is also possible to add additives to the melamine / formaldehyde precondensate. The abrasive foams contain in one embodiment at least one additive from the group of dyes, fragrances, optical brighteners, UV absorbers and pigments. This additive is preferably distributed homogeneously in the foam.

As pigments it is possible to use the customary inorganic natural (eg chalk) or synthetic pigments (eg titanium oxides), but also organic pigments.

Suitable further additives are, for example, flame retardants, such as intumescent compositions, alkali metal silicates, melamine, melamine polyphosphate, melamine cyanurate, aluminum hydroxide, magnesium hydroxide, ammonium polyphosphates, organic phosphates or even flame-retardant halogen compounds. Also suitable are plasticizers, nucleating agents, IR absorbers such as carbon black and graphite, aluminum oxide powder or Al (OH) ₃ , soluble and insoluble dyes, biocide-active substances (such as fungicides) and pigments as additives.

In process step (2), heating takes place for foaming the precondensate and optionally the support material. By heating the solution or dispersion from step (1) to a temperature above the boiling point of the blowing agent used, a foam can be obtained. The exact temperature to be used also depends on the propellant used (eg its boiling point). The heating in step (2) may, for. B. by the use of hot gases (such as air or inert gases) and / or high-frequency radiation (eg., Microwaves) done.

The energy input can preferably be effected by electromagnetic radiation, for example by high-frequency irradiation with 5 to 400 kW, preferably 5 to 200 kW, particularly preferably 9 to 120 kW per kilogram of the mixture used in a frequency range from 0.2 to 100 GHz, preferably 0.5 up to 10 GHz. As a radiation source for dielectric radiation magnetrons are suitable, with one or more magnetrons can be irradiated simultaneously.

The foams produced are finally dried, whereby remaining in the foam water and blowing agent is removed.

In process step (4), the melamine resin foams are washed several times with water and then dried. The melamine resin foam may be in the form of blocks, smaller fragments or ground.

In a preferred embodiment, the process can be carried out batchwise. The hydrophilic foam, for example, immersed in a water bath and then pressed by conventional pressing methods (press or calender). This process is repeated several times. The remaining water in the foam is then removed by drying

In a further preferred embodiment, the washing process can be carried out continuously. For this purpose, the foam is immersed, for example in a stream of water, so that a complete wetting of the entire open-cell foam structure takes place After a short time this can then be removed and then dried.

The melamine resin foams produced according to the invention generally have a density of 5 to 15 g / l, more preferably 5 to 10 g / l.

The melamine resin foams according to the invention are used in the upholstery of seats, as heat, cold and / or sound insulation or insulation or insulation of buildings and parts of buildings, especially of walls, partitions, roofs, facades, doors, ceilings and floors of vehicles of all kinds on land, at sea, in the air and in space, whether for the transport of goods or passengers or such a combination in passenger cars, lorries, z. As for the isolation of the engine compartment (such as hoods) or passenger compartments, rail transport in the wagons in goods or passenger transport and in locomotives, in aircraft z. As in the cabin interior, the cockpit or in the hold and in space travel in manned or unmanned flying objects such as spaceships and space gliders, space capsules or satellites, for cryogenic isolation z. As of refrigerators, refrigerators, cold stores, tanks and containers for any liquids, especially for oil and gas or liquefied gas to (-278) ° C, for storage and transport, for recording and reversible or partially reversible delivery of liquids to (- 273) ° C as a "sponge", in the cleaning industry for in the cleaning of surfaces z. B. in the form of sponges or soaked with detergents of all kinds u. a. for washing processes in automatic washing machines, as shock-absorbing or shock-absorbing packaging material, in hygiene applications (diapers, sanitary napkins) and in the textile sector (clothing).

Examples

Comparative Example A

Preparation of an Unmodified Melamine / Formaldehyde Foam

75 parts by weight of a spray-dried melamine / formaldehyde precondensate (molar ratio 1: 3) were dissolved in 25 parts by weight of water. 3% by weight of formic acid, 2% by weight of a Na-C ₁₂ / C ₁₄ -alkyl sulfate, 20% by weight of pentane, based in each case on the resin, were added to this resin solution. Then, it was stirred and then in a mold (for foaming) made of polypropylene Irradiation of microwave energy foams. After foaming, it was dried for 30 minutes.

example 1

Preparation of a hydrophobic melamine / formaldehyde foam (discontinuous)

75 parts by weight of a spray-dried melamine / formaldehyde precondensate (molar ratio 1: 3) were dissolved in 25 parts by weight of water. 3% by weight of formic acid, 2% by weight of a Na-C ₁₂ / C ₁₄ -alkyl sulfate, 20% by weight of pentane, based in each case on the resin, were added to this resin solution. Then, it was stirred and then foamed in a mold (foaming) of polypropylene by irradiation of microwave energy. After foaming, it was dried for 30 minutes.

From the resulting foam, 6 pieces of foam measuring 20 × 15 × 2 cm were placed in a vessel containing 5 liters of distilled water (pH 7, hardness (Ca + Mg) 0.0005 mmol / l, electrical conductivity 0.2 μS / cm ) immersed at room temperature. After removal from the water bath, the samples were mechanically compressed until no more water dripped out of them. This washing and pressing process was carried out a total of 5 times in succession. The subsequent drying was carried out at 100 mbar and 80 ° C to constant weight.

Example 2

Preparation of a hydrophobic melamine / formaldehyde foam (discontinuous)

The procedure was analogous to Example 1, but tap water (pH 7.5, hardness (Ca + Mg) 3.0 mmol / l, electrical conductivity 600 μS / cm) was used instead of distilled water. The washing and pressing process was carried out a total of 10 times in succession.

Example 3

Preparation of a hydrophobic melamine / formaldehyde foam (continuous)

75 parts by weight of a spray-dried melamine / formaldehyde precondensate (molar ratio 1: 3) were dissolved in 25 parts by weight of water. 3% by weight of formic acid, 2% by weight of a Na-C ₁₂ / C ₁₄ -alkyl sulfate, 20% by weight of pentane, based in each case on the resin, were added to this resin solution. Then, it was stirred and then foamed in a mold (foaming) of polypropylene by irradiation of microwave energy. After foaming, it was dried for 30 minutes.

A cylindrical melamine resin foam having a length of 10 cm and a diameter of 55 mm was filled at one end of a 40 cm long plastic pipe with the diameter of 55 mm. On the other side, a total of 6 liters of water are added continuously, so that the melamine resin foam is wetted with water and washed homogeneously. This was followed by a mechanical compression of the sample body until no more water dripped from them. The drying was carried out at 100 mbar and 80 ° C to constant weight.

Studies on water absorption:

The unmodified melamine resin foam from Comparative Example 1 was soaked on contact with water and submerged within seconds.

Drops of water which have been applied with a pipette to the surface of the foam, immediately wet and penetrate the unmodified melamine resin foam from Comparative Example 1.

The modified melamine resin foams of Examples 1, 2 and 3 float for days on the water.

Water droplets applied to the surface of the foam with a pipette do not penetrate into the modified melamine resin foam of Examples 1, 2 and 3.

Studies on oil absorption on water

The modified melamine resin foams of Examples 1, 2 and 3 receive oil, for example edible oil or diesel, from a water surface and continue to float on the water.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6607817 B [0002]
• DE 10011388 A [0003]
• WO 2008/37600 A [0004]
• WO 01/94436 A [0017]

Cited non-patent literature

• Houben-Weyl, Methods of Organic Chemistry, Vol. 14/2, 1963, pages 319 to 402 [0022]
• Encyclopedia of Polymer Science and Technology, Vol. I, 3rd edition, chapter Additives, pages 203 to 218, 2003. [0030]

Claims (6)

A process for the production of hydrophobic melamine / formaldehyde resin foams, characterized in that one washes melamine / formaldehyde resin foams with water, squeezing the water and drying the washed foam. Process for producing hydrophobic melamine / formaldehyde resin foams according to Claim 1, characterized in that the melamine / formaldehyde resin foams are used as powder, flakes or as a block. A process for preparing hydrophobic melamine / formaldehyde resin foams according to claim 1 or 2, characterized in that the washing is carried out batchwise or continuously with 1 to 1000 ml of water per cm ^{3 of} melamine / formaldehyde resin foam. A process for the preparation of hydrophobic melamine / formaldehyde resin foams according to any one of claims 1 to 3, characterized in that one carries out the drying at a temperature of 20 to 200 ° C and a pressure of 0.001 to 1 bar. Use of the prepared according to claim 1 to 4 hydrophobic melamine / Formaldehydharzschaumstoffe in the upholstery of seats, as heat, cold and / or sound insulation or insulation or insulation of buildings and parts of buildings, of vehicles of all kinds on land, to water, in the air and in space, for cryogenic insulation, for the absorption and reversible or partially reversible release of liquids up to (-273) ° C as "sponge", in the cleaning industry for cleaning surfaces, for washing in automatic washing machines , as shock-absorbing or shock-absorbing packaging material, in hygiene applications as well as in the textile sector. Hydrophobic melamine / formaldehyde resin foams prepared according to one of claims 1 to 4.