WO2011117294A1 - Process for producing molded foams from melamine/formaldehyde condensation products - Google Patents

Abstract

A process for producing molded foams from melamine/formaldehyde condensation products, by foaming melamine/formaldehyde precondensates under reduced pressure and then irradiating them.

Description

 Process for the production of molded foams from melamine / formaldehyde condensation products

description

The present invention relates to the production of molded foams from melamine / formaldehyde condensation products.

It is known from EP-37470 that melamine / formaldehyde condensation products are failed and hardened by microwave radiation. Advantageously, at reduced pressure, preferably at 400 to 900 mbar, foamed.

The thereafter available melamine / formaldehyde resin foams leave something to be desired.

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

Accordingly, a new and improved process for the production of molded foams from melamine / formaldehyde condensation products has been found, which is characterized in that melamine / formaldehyde precondensates are foamed under reduced pressure and then irradiated.

The process according to the invention can be carried out as follows:

A solution, emulsion, dispersion or suspension of melamine / formaldehyde precondensates and optionally one or more additional components (Z) may continuously, preferably batchwise at a temperature of 0 to 200 ° C, preferably 10 to 150 ° C, and a pressure of 10 to 950 mbar, preferably 50 to 900 mbar, are foamed and finally dried, wherein water and blowing agent remaining in the foam are removed.

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. Suitable melamine / formaldehyde precondensates are custom-made (see Technical Bulletins: a) W. Woebcken, Kunststoffhandbuch 10. Duroplaste, Munich, Vienna 1988, b) Encyclopaedia of Polymer Science and Technology, 3rd ed., Vol , Chap. Amino Resins, pp. 340-370, 2003 c) Ullmann's Encyclopedia of Industrial Chemistry, 6th ed., Vol. 2, chap. Amino Resins, pp. 537-565. Weinheim 2003) or commercial precondensates of the two components, melamine and formaldehyde. 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 may contain from 0 to 50% by weight, preferably from 0 to 20% by weight, of other thermoset formers and, in addition to formaldehyde, from 0 to 50% by weight, preferably from 0 to 20% by weight of other aldehydes Contains condensed. However, preference is given to an unmodified melamine / formaldehyde condensation product.

Examples of suitable thermoset-forming agents 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, Methoden der organischen Chemie, 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.

The amount of blowing agent can be varied within wide limits and usually depends on the desired density of the foam to be produced. The amount of blowing agent is generally from 1 to 40 wt .-%, preferably 1, 5 to 30 wt .-%, particularly preferably 5 to 15 wt .-% based on the melamine / formaldehyde precondensate. The hardeners can generally be used in amounts of from 0.01 to 20% by weight, preferably 0.02 to 10% by weight, particularly preferably 0.05 to 5% by weight, based on the melamine / formaldehyde precondensate become. The additives can generally be used in amounts of from 0 to 20% by weight, preferably 0 to 10% by weight, particularly preferably 0 to 5% by weight, in particular 0% by weight, based on the melamine / formaldehyde Pre-condensate can be used.

Suitable dispersants or emulsifiers are anionic, cationic, nonionic surfactants and mixtures thereof.

Examples of suitable anionic surfactants are diphenylene oxide sulfonates, alkyl and alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkyl ether sulfonates, fatty alcohol sulfates, ether sulfates, acylaminoalkanesulfonates, acylisothionates, alkylethercarboxylates, N-acylsarcosinates, alkyl and alkyl ether phosphates.

As cationic emulsifiers, e.g. Alkyltriammoniumsalze, Alkylbenzyldimethyl- ammonium salts and Alkylpyridiniumsalze be used.

Suitable nonionic surfactants are, for example, 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 alkyl polyglycosides.

Suitable blowing agents are "physical" or "chemical" blowing agents (Encyclopedia of Polymer Science and Technology, Vol. I, 3rd ed., Chapter Additives, page 203 to 218, 2003).

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.

Suitable "chemical" blowing agents are, for example, isocyanates mixed with water to release carbon dioxide as the effective blowing agent, and carbonates and bicarbonates are also suitable when mixed with acids which also produce carbon dioxide.

Acidic compounds which catalyze the further condensation of the melamine resin can be used as curing agents. 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. ren, 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. 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 burn gas toxicity or to promote the charring add.

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

As pigments, the common inorganic natural (for example chalk) or synthetic pigments (for example titanium oxides), but also organic pigments can be used. The density of the melamine resin foams which can be prepared according to the invention is generally from 3 to 50 g / l [g per liter], preferably from 4 to 20 g / l, particularly preferably from 5 to 10 g / l.

The melamine resin foams which can be prepared according to the invention can be foamed up to any shapes, preferably moldings of any shape, plates or webs, particularly preferably plates or webs, as a rule of any thickness, advantageously in layer thicknesses of 0.1 to 500 cm, preferably 0.5 to 200 cm , Particularly preferably 1 to 100 cm, in particular 3 to 80 cm, most preferably 5 to 50 cm are produced.

The melamine resin foams which can be prepared according to the invention and the hydrophobic melamine resin foams in the form of webs, sheets, moldings or another design which can be produced according to the invention can be provided or laminated on one, two, more or all sides with cover layers, for example with paper, cardboard, Glass fleece, wood, gypsum board, metal sheets or metal foils, plastic or plastic films, which may also be foamed. The cover layers can be applied during foaming or subsequently. In the case of subsequent application, it is advantageous to use an "adhesion promoter." The melamine resin foams according to the invention are used in upholstering seating surfaces, as heat, cold and / or sound insulation or insulation or insulation of buildings and parts of buildings, in particular walls, partitions . Roofs, facades, doors, ceilings and floors, of vehicles of all kinds on land, water, in the air and in space, whether for the transport of goods or passenger or such a combination in passenger cars, trucks, eg for the insulation of the engine compartment (such Bonnets) or passenger compartments, in rail wagons in goods or passenger traffic, and in locomotives, in aircraft, eg in the cabin interior, the cockpit or in the cargo hold, and in space travel in manned or unmanned flying objects such as spaceships and space gliders, space capsules or satellites Low-temperature insulation eg of cooling units, refrigerators, cold stores, tanks and containers for any liquids, in particular for oil and gas or liquid gas up to (-278) ° C, for storage and transport, for receiving and reversible or partially reversible delivery of liquids up to (- 278) ° C as "sponge", in the cleaning industry for in the cleaning of For example, in the form of sponges or soaked with detergents of all kinds, inter alia, for washing in washing (fully) machines, as shock-absorbing or shock-absorbing packaging material, for sound absorption and thermal insulation or insulation of buildings and for the production of cleaning sponges.

Such an industrially produced, elastic foam based on a melamine / formaldehyde condensate is known under the trade name BASOTECT® (BASF SE).

Examples

Example 1 to 5

75 parts by weight of the spray-dried melamine / formaldehyde precondensate from Example A (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 18 -alkanesulfate and 20% by weight of pentane, in each case based on the melamine / formaldehyde precondensate, were added to this resin solution, stirred and then poured into a cylindrical printing plate foamed from polyaryletherketone (PEEK) by irradiation of microwave energy. After foaming, it was dried for 30 minutes.

 The pressures can be adjusted variably between 0.1 mbar and 1013 mbar.

The results are summarized in Table 1.

Table 1

Example No. Pressure [mbar] Description Density [g / l] Stamp pressure F _max . [N / CN]

1 1013 elastic 8.9 12.3

 2 920 elastic 8.9 16.0

3 500 elastic 8.6 20.6 4 250 elastic 8,3 27.1

 5 50 elastic 7.5 35.9

Stamping pressure measurement (according to US Pat. No. 4,666,948) for evaluating the mechanical quality of the melamine resin foams. For this purpose, a cylindrical stamp having a diameter of 8 mm and a height of 10 cm was placed in a cylindrical sample with a diameter of 1 cm and a height of Press 5 cm in the foaming direction at an angle of 90 ° until the sample breaks. The breaking force [N / KN] provides information about the quality of the foam.

Claims

claims Process for the preparation of molded foams from melamine / formaldehyde condensation products, characterized in that melamine / - formaldehyde precondensates are foamed under reduced pressure and then irradiated. A process for the production of molded foams from melamine / formaldehyde condensation products according to claim 1, characterized in that foams at a temperature of 0 to 200 ° C. A process for the production of molded foams from melamine / formaldehyde condensation products according to claim 1 or 2, characterized in that foaming at a pressure of 10 to 950 mbar. A process for the production of molded foams from melamine / formaldehyde condensation products according to any one of claims 1 to 3, characterized in that drying is carried out after foaming. Shaped foams of melamine / formaldehyde condensation products prepared according to one of claims 1 to 4. Use of the melamine / formaldehyde condensation products according to any one of claims 1 to 5 for upholstering of seats, as heat, cold and / or sound insulation, as insulation and / or insulation of buildings and parts of buildings, of vehicles of all kinds on land, to Water, in the air and in space, in tanks and / or containers for any liquids, as a sponge, in the cleaning industry for cleaning surfaces.