DE2227640A1 - Foaming aq silicate solns - using hydrogen peroxide/ reducing agent - Google Patents

Abstract

The soln., opt. contg. other (in)org. materials, is treated with H2O2 pref. as aq. soln., and reducing agent, pref. Mg, Al, Si, Fe, S or (para) HCHO in finely-divided form. Process gives strong foaming without ecological problems of org. blowing agents, and heat of reaction may be used for simultaneous foaming of plastics to give a composite.

Description

Process for foaming aqueous silicate solutions It is known Silicate solutions - to beat with air to a foam and to harden it. According to Another suggestion is silicate solutions with hardeners and a volatile blowing agent mixed and thus foamed above the boiling point of the propellant.

In the former case, the foam no longer expands and can therefore be special Moldings can no longer penetrate or penetrate only with difficulty; in the second case, the Use of volatile organic blowing agents often poses ecological problems.

It has now been found that silicate solutions, if necessary still contain additives such as fillers, foam particularly advantageously if you add hydrogen peroxide and a reducing substance to them.

Surprisingly, it has been shown that aqueous silicate solutions, which are mixed with aqueous hydrogen peroxide solution and in general tend to foam very little (due to decomposition of the H202), immediately very strong foam and often one to evaporate part of the contained in them Water develop sufficient heat if you also add a reducing agent to them clogs.

The present invention relates to a process for foaming aqueous optionally containing inorganic and / or organic additions Silicate solutions, which is characterized in that the silicate solutions Hydrogen peroxide and a reducing agent are added.

As inorganic and / or organic admixtures are both with Fillers that do not react or react only very slowly in the silicate solution, be they inorganic or organic, compact, foam-like or still capable of foaming to understand, as well as substances that gel or gel the silicate solutions.

polymerize or be able to precipitate. Also fall under these The term also includes further diluents which are soluble or insoluble in the silicate solutions or auxiliaries such as dyes, emulsifiers, thickeners, gas additives, fragrances Catalysts e.g. for H202 decomposition, pore regulators, plasticizers. These substance groups are described, for example, in DOS 2,039,736; 2,036,842; U.S. Patent 1,944,008.

Aqueous silicate solutions are used for the process according to the invention Solutions of silicates in water or aqueous media into consideration, which both the Can have the character of real as well as colloidal solutions, e.g.

Ammonium silicate or metal silicates. Alkali silicate solutions are preferred, e.g. sodium and / or potassium silicate solutions. Also alkali stabilized Silica sols are possible. A very suitable starting material are the so-called, Water glass solutions that have been on the market for a long time Silicate does not necessarily have the formula Na20. ji - 4 SiO2 correspond to, as it is used as a basis for water glass, for example. The proportions of alkali metal oxide to SiO2, from e.g. Na4SiO4 to polysilicates of various degrees of polymerization, in which the ratio of alkali metal oxide to Si02 is less than 1: 1, e.g. 0.1: 1, vary. However, a flowable silicate solution is a prerequisite. The concentration these solutions are upward due to the necessary pourability of the solutions limited to around 60%, although more highly concentrated solutions are also available, for example Kneading units would be processable at elevated temperatures. Down is the Concentration limited by using solutions with less than 5 * solids content in general only give gels with unsatisfactory strength. Silicate solutions are preferred used with 10 - 50 wt .-% solids content.

The hydrogen peroxide is preferably in the form of its aqueous Solutions used. In principle, these solutions can be used in any concentration be used.

For reasons of effectiveness, however, it is advantageous to use concentrations over 3% and for reasons of danger it is advisable not to use concentrations over 50% to use.

The ones to be used are based on the total foaming mixture Concentrations of hydrogen peroxide between 0.05 and 30 wt .-%, preferably between 0.15 and 10 wt.

The use of substances in an aqueous medium to form are capable of hydrogen peroxide, such as persulfates, peracetates, alkali and alkaline earth peroxides, perphosphates, perborates, etc. are also true possible, however, preference is given to using hydrogen peroxide directly.

The additional use of substances that cause the decomposition of hydrogen peroxide catalyze, such as Min02, iron oxides, or organic catalysts is possible, but not necessary as a reducing agent in this process those substances are suitable which react with oxygen or hydrogen peroxide in aqueous medium at temperatures below 1000C, if necessary with the aid of special oxidation catalysts such as cerium salts, copper, chromium-vanadium, Iron, nickel-cobalt compounds are able to react.

Such reducing agents can be inorganic or organic in character to have. They can be used alone or in a mixture with one another. they are as a powder, suspension, as a colloidal or true aqueous or non-aqueous solution can be used, whereby the effectiveness increases with increasing degree of distribution.

As process-related reducing agents, for example: Metals such as Mg, Zn, Al, Sn or Fe, non-metals such as Si, P, S or J, phosphines, Phosphites, sulfides, polysulfides, CS2, sulfites, thiosulfates, metal alcoholates.

Hydrides such as sodium borohydride or silane can also be used. Primary or secondary amines or masked amines such as Hydrazine, substituted hydrazines, hydrazides or hydrazones, ethylenediamine, phenylenediamine, Schiff bases, isocyanates, amides, ureas, primary and secondary alcohols, Phenols, aldehydes or blocked aldehydes, e.g. the various sugars, Hydroquinone, Formaldehyde, paraformaldehyde, acetaldehyde, aldol, urotropin, benzaldehyde.

From the large number of those which are in principle suitable as reducing agents Substances are particularly preferred that are not based on silicate solutions alone or have a very slow precipitating or gelling effect. Among these, in turn, are to prefer those whose oxidation produces acidic compounds or bases, the gelling of the foaming silicate solution and thus stabilization of the foam formed.

Hydrazine, Mg, Al, Si, Fe, S in fine distribution, as well as formaldehyde and paraformaldehyde. The reducing agents are in amounts of 0.01 to 40, preferably 0.1 to 20% by weight, based on the foaming mixture, used.

It is an essential object of the present invention to provide silicate solutions to foam and the foam formed by an optionally known gelation process to stabilize, so that silicate foams are accessible, which in moist or in the dried state as insulating materials, construction materials, absorbents or carrier materials can be used.

Therefore, the method according to the invention can in principle serve to regardless of the hardener system or gelling agent selected, any silicate solution to be converted into a foam, the combination of hydrogen superoxide and reducing agents can in turn be chosen so that they also become a Gelation leads but on the other hand this property does not necessarily have to be must provide.

Expediently, the foaming is carried out in such a way that the Aqueous, if appropriate, inorganic and / or organic admixtures Silicate solution mixed with the reducing agent and in this mixture at the same time or then incorporated the hydrogen peroxide. Because silicate solutions that does not contain the reducing agents to be used, generally with hydrogen peroxide Foam only very weakly by comparison, you can also first use a mixture from silicate solution and hydrogen peroxide and then produce this Mix with the reducing agent, whereupon the foaming starts immediately.

Any necessary hardeners or gelling agents as well as additives Catalysts for, for example, oxidation reactions, decomposition or polymerizations can be added before or after foaming, expediently dosed they are used at the same time as the additive that triggers the foaming, i.e. either a reducing agent or hydrogen peroxide.

The foaming can take place at temperatures between approx. -10 ° C and 120 ° C can be started in advance, preferably between 50C and 35cd. After this At the start of the foaming, the reaction mixture heats up so much that this is in the system contained water partially evaporates. This strong warmth tint that not only by the decomposition of the hydrogen peroxide, but also by the running Oxidation reaction and the subsequent reactions e.g. the hardening process, neutralizations etc. is effected, can not only serve to remove the water, but can also be used to run other processes in parallel in the foaming system to run off, for example the foaming of a mixed-in blowing agent containing plastic granulate, so that multi-foam systems are obtained, e.g. good fire or heat resistance behavior with good insulating properties associate.

For this purpose, plastics containing propellants can be used, for example Homo- and copolymers of styrene, vinyl chloride or ethylene are possible.

Similarly, the strong heat tint can also be used to parallel to the foaming of the silicate solution polymerization, polycondensation or polyaddition reactions of e.g. vinyl monomers such as methyl methacrylate, mixtures of styrene and unsaturated polyesters, acrylonitrile, etc., polyepoxides, amides or isocyanates to run off, the optionally used as a reducing agent present formaldehyde, for example, also as a reactant for acetalizations, Methylolations or condensations can serve.

The available silicate foams are closed or mostly largely open-pored and can have density between approx. 0.04 and 0.95.

The method according to the invention is described below by way of example (the specified parts are parts by weight, unless otherwise noted is). Example 1 The effect of a Feduktionsmittel as Accelerators for foaming goods containing hydrogen peroxide Silicate solutions are demonstrated: 200 parts of a 50% sodium silicate solution are stirred with 20 parts of an aqueous 30% hydrogen peroxide solution. the Mixture rises very slowly in a beaker to a foam. Stirred However, such a freshly prepared mixture with 8 parts of paraformaldehyde powder, violent foaming starts spontaneously with heating up to approx. 100 ° C, where a long, fine-pored foam is created, which, if it is in a thin layer of about 1 cm is applied to a substrate, there to a foam layer stiffens. This coating provides a wet or dried state effective fire protection layer.

The mixture can also be produced continuously and at a suitable rate Substrate, such as a wall or latticework, is doctored on @ which is sprayed on.

Example 2 200 parts of 43 (20% soda water glass oil, 50 Mix in the magnesium oxide powder. 6 parts of 30% strength hydrogen peroxide solution are then stirred a. This mixture only foams up very slowly. If you mix more than 15 Tle Paraformaldehy @ added, the bishang immediately foams up and the resulting very fine-pored foam solidified in several hours. After drying at room temperature, the formed one has Silicate foam @ a density of approx. 0.18 g / cm3.

Instead of MgO, red Fe2O3 can also be used with the same result will. The getro @@ nete foam has a density of 0.24 g / cm3.

Example 3 In 200 parts of approx. 40% sodium waterglass solution, 3 parts a copolymer of 70 wt. qb propylene oxide and acting as a pore former 30 wt. Ethylene oxide, molar weight. approx. 2500, as well as 50 parts silicon dust stirred in.

If you now mix in 12 parts of 20% hydrogen peroxide, it foams the mixture spontaneously under strong heating to a brownish foam, which solidifies after a few minutes and has a density of approx.

0.1 g / cm3.

Example 4 In 200 parts of 48% sodium waterglass are 40 parts of a aqueous sulfur suspension (pesticide content approx. 20% by weight), the 3 parts of alkyl sulfonate (MersolatR) as an emulsifying aid and pore stabilizer and at the same time 10 parts of 30% hydrogen peroxide solution mixed in. Starts after approx. 50 seconds to foam the mixture under intense heating. The foam formed can be in Pormen can be given or sprayed onto a substrate, where it is after a short time Solidified time.

Instead of an aqueous sulfur suspension, a 20% solution can also be used of sulfur in carbon disulfide (15 Tu) can be used.

Example 5 The procedure is as in Example 4, but used instead the aqueous sulfur suspension is a mixture of 5 parts of paraformaldehyde and 10 parts Sulfur flower.

Example 6 200 parts of 30% potassium waterglass are mixed with 10 parts of 30% aqueous formaldehyde solution and 8 parts of the above hydrogen peroxide solution. The mixture immediately begins to foam under heating. Now mix in the Foam another 15 teaspoons of sodium silicofluoride. This mixture is poured into a loaf pan filled with paper, in which the foam rises a little further and then over the course hardened in an hour. After drying, it has a density of approx. 0.12 g / cm3.

Example 7 200 parts of 48% sodium waterglass solution are mixed with 20 parts Mixed aluminum powder, then add 3 teaspoons of an addition product of 10 moles of ethylene oxide on nonylphenol as a pore regulator and stirs 5 parts 30ige Hydrogen peroxide solution. The mixture begins to foam immediately after being stirred in. The foaming mixture is poured through a slot nozzle in an approx. 2 cm thick layer Applied to a rigid polyurethane foam board and solidifies there. So you get a fire-retardant protective layer on the rigid foam board. With double-sided coating a corresponding sandwich is created.

Instead of the Al powder, you can also use a mixture of, for example, the same Use parts of Mg and Al powder.

In the same way, a mixture of equal parts of Al and Si powder or Si powder alone.

Example 8 200 parts of a 48% sodium waterglass solution that still Contains 0.5% by weight of alkyl sulfonate (Mersolat®) 5 tsp. Hydrazine hydrate stirred. Furthermore, 200 parts of the same silicate solution are stirred with 20 parts of 30% hydrogen peroxide solution.

If you stir both solutions together at room temperature, it foams Mixture spontaneously. The resulting foam can either be mixed with other hardeners, for example sec.

Magnesium phosphate (15 parts, finely powdered) or O-tosyl chloride (15 Tle) can be stirred and then gelled in molds or you can do it without Spray more hardener on walls or other surfaces, where it is caused by the C02 the air or simply drying is stabilized as a layer of silicate foam.

Example 9 In a continuously operating mixing chamber, in the opposite a high-speed stirrer the various liquid reaction components at the same time be injected by means of high pressure pumps, while reaction mixture in the same amount leaves the mixing chamber after passing through the stirrer, the following component quantities are added every minute introduced: 200 parts of silicate solution according to Example 8, 10 parts of approx. goat aqueous formaldehyde solution, 3 parts of glycerine triacetate as an additional gelling agent, 8 parts of DOIO hydrogen peroxide solution and 12 parts of an acid-releasing compound that acts as a hardener.

The apparatus is operated at room temperature. That from the mixing chamber emerging reaction mixture begins to foam immediately and provides a fine-pored Foam that hardens all viscosity stages from flowing to plastic to hard and brittle depending on the hardener in a few seconds to several hours.

In all Palls there is the silicate foam, which comes in a box shape Foaming is brought about, after 10 hours completely hard and almost odorless. The density of the dry foams is between 0.07 and 0.14 g / cm3.

The following substances were used as hardeners: A. Pentachloroethyl isocyanide dichloride B. Mixture of equal parts of trichloromethyl isocyanide dichloride and benzotrichloride C. Butanediol bis-chloroformic acid ester D. 2,4 dichlorobenzoyl chloride E. Mixture equal parts of ethyl trichloroacetate and pyrocarbonic acid dibutyl ester F. 4-chloroisophthalyl chloride.

Example 10 200 parts of the silicate solution according to Example 8 are mixed with Mix 20 tlen silicon dust. Then mix 50 more parts of a foamable one Polystyrene bead polymer containing about 6 wt. Pentane as a blowing agent and stir the mixture carefully with 10 parts of 30% hydrogen peroxide. The mixture immediately begins to foam up and heats up so much that that too Polystyrene foams. The resulting block of material is kept for another 2 hours at 800 to complete curing and foaming. It is a composite foam which contains polystyrene foam spheres embedded in silicate foam.

A mixture of 10 parts paraformaldehyde can also be used instead of silicon dust and 10 parts of finely powdered isocyanide dichloride: Cl2CN-CCl2-NCCl2, where a colorless composite foam results. The isocyanide dichloride causes a rapid hardening of the foam. One Post-reaction with increased Temperature is not absolutely necessary in either case in this example.

Example 11 It is dissolved in 400 parts of 43% sodium waterglass solution 2 1 part alkyl sulfate (Mersolat®) as an emulsifier and pore-forming agent, as well as 10 parts hydrazine hydrate on.

At room temperature, this solution will now work well with a Stirrer 20 parts of a 30% hydrogen peroxide solution and 45 parts of methyl trichloroacetate stirred in as a hardening agent. The mixture turns an intense yellow and foams after a few seconds in a loaf pan, with the yellow coloration after about one minute disappeared and a colorless, very fine-pored foam has emerged. To After a storage time of 10 hours, the foam can be cut and dried. The wet density is 0.1 -g / cra3, in the dried state (room temperature) the foam has a density of approx. 0.05. It can be used as an insulating or decorative material with good Find fire behavior use.

The foaming can also be carried out continuously according to Example 9 be made.

Example 12 The procedure is analogous to Example 11, but uses instead of methyl trichloroacetate a solution of 6 parts of butanediol-bis-chloroformic ester in 15 parts of ethyl dichloroacetate. The resulting foam has a dry density of 0.07 g / cm3.

Example 13 The procedure is analogous to Example 11, but instead of of methyl trichloroacetate the same amount of ethyl chloroacetate.

Claims (5)

Patent claims: 1) Process for foaming aqueous, possibly inorganic, and / or Silicate solutions containing organic admixtures, characterized in that hydrogen peroxide and reducing agent are added to the silicate solutions. 2) Method according to claim 1, characterized in that one is aqueous Hydrogen peroxide solutions are used. 3) Method according to one of claims 1 to 2, characterized in that that the reducing agent Mg, A1, -Si, Fe, S, formaldehyde, paraformaldehyde or Hydrazine used in finely divided form. 4) Method according to one of claims 1 to 3, characterized in that that in addition to the foaming of the silicate solutions, gelation or hardening takes place of the resulting silicate foam. 5) Silicate foams produced by a method according to one of claims 1 to 4.