NO134621B - - Google Patents

Description

The invention relates to a method for producing new foam plastics, especially urethane and/or carbamide and/or amide and/or isocyanurate groups and polyoxymethylene containing foam plastics with new properties.

It has been found that at least partially open-celled foam plastics react to polymerising formaldehyde, thioformaldehyde or e.g. trioxane as matrices. Surprisingly, for example, the polymerizing formaldehyde adapts to the existing cell structure of the foam plastic and expands its cells three-dimensionally. Thereby it is. particularly surprising that the formed high molecular weight 'polyoxymethylene' does not close the cells compactly, but even to a large extent provides additional cell openings. This makes it possible for the first time to produce, for example, polyurethane or polyisocyanurate foam,

which consists of polyoxymethylenes to more than 90% by weight.

According to the state of the art, polyoxymethylene is not foamable while achieving a lower volume weight. The new method according to the invention therefore makes it possible, starting from a majority of technically interesting foam plastics with very different structures, to convert these into foam plastics which, for example, consist of polyurethanes or polyisocyanurates and high-grade tough polyoxymethylene. New foam plasters are thus formed while maintaining and increasing an open-cell pore structure with a surprisingly strong increase in volume.

US patent no. 2,921,866 relates to reducing the discoloration of a polyurethane foam when exposed to air and light, subjecting at least the surface of the foam to the influence of an organic monoisocyanate. This monoisocyanate can thereby be dissolved in an organic solvent and a tertiary base can also be added as a catalyst.

This US patent also mentions the use of formaldehyde to prevent discolouration or yellowing of polyurethane foams, although the best results according to this patent are obtained with raoisocyanates.

In contrast to what appears in this US patent, the present invention relates to a) a swelling reaction of the foam material and b) the simultaneous or subsequent polymerization of formaldehyde or formaldehyde-releasing compounds during solid formation, so that the newly formed foam volume during swelling is irreversibly fixed. An irreversible fixation of a foam volume newly formed by swelling by solid formation is not apparent from US patent no. 2,921,866. The subject matter of the present invention and the subject matter of US patent no. 2,921,866 are thus completely different methods.

The invention thus relates to a method for the production of new foam plastics by treating per se known foam plastics with formaldehyde. in that the method is characterized by at least partially open-celled foam plastic matrices, consisting preferably of polyurethane, polycarbonate, polyisocyanurate, polystyrene, polyvinyl chloride, carbamide-formaldehyde, phenol-formaldehyde, ABS-polymerisate or polyamide, swell under the influence of formaldehyde, formaldehyde-releasing compounds or thioformaldehyde, which compounds are used as a highly concentrated aqueous solution or in gaseous form, and that at the same time or afterwards a very rapid polymerization of the formaldehyde or thioformaldehyde is carried out in and at the cell wall of the foam plastic matrix in the presence of polymerization catalysts and possibly of cyclic acetals, cyclic ethers, vinyl monomers or trichloro- or trifluoroacetaldehyde, whereby the new swollen foam plastic volume is irreversibly fixed.

With the extraordinarily high polymerization rate for formaldehyde, thioformaldehyde resp. trioxane, one would expect that the polymeric resp. copolymers of the formaldehyde were to be embedded in compact form in the cells of the foam plastic. Since, as is known, polyoxymethylene has a poor adhesion to substrates of the usual type, one would further expect that the polyoxymethylene would polymerize only in a loose and easily tearable powdery form without special attachment to the foam plastic. Contrary to expectations, this is not the case, but homogeneous foam plasters are obtained instead. Also unexpected was the high stability of the cellular polymerizable polyoxymethylenes in polyurethane foam plastic matrices containing NH groups. In the new process products, one must therefore expect a high proportion of end-group stabilized polyoxymethylenes which are formed by transfer reactions, i.e. chain termination reactions with active sites, e.g. in the polyurethane plastic matrix. According to the new method, e.g. not only mixtures, but instead also chemical modifications of the starting foams.

According to a technically preferred embodiment of the new method, highly purified, anhydrous or up to 5 wt. -Print. Although it is in principle not necessary to activate the selected foam plastic matrix for the formaldehyde polymerization, for a technical implementation of the method, where one strives for a high volume-time yield and short reaction time, it has proven advantageous to subject a foam plastic used as a matrix to a pre-treatment with formaldehyde -, thioformaldehyde-resp. trioxane polymerization catalysts.

In principle, all known formaldehyde polymerization catalysts are involved, as some examples can be mentioned of formic acid, which is present in every formaldehyde gas or trioxane vapor in small amounts (0.3 - 0.005 mol?), BF-^, BP-j addition products, various oxonium salts , diazonium fluoborates, metal halides, various tertiary amines, amidines, guanidines and generally nitrogen-containing heterocyclic compounds, hexahydrotriazines, quaternary ammonium, phosphonium and sulfonium salts, phosphines, arsines, stibines, phosphoric acid ester derivatives and polyphosphoric acid, pyrophosphoric acid, metal hydrides , metal carbonyls and organometallic compounds of any type, such as alkyl metal compounds, Grignard compounds, alcoholates and mercaptides, boronic acid tris-amides, phenyl iodide chloride, alkyl substituted carbamides and thiocarbamides, N-methylol compounds of carbamides, of acid amides, their ethers and thioureas -ethers, tetramethylthiuram disulfide and colloidal, monoclinic sulphur. Also Redox system, e.g. on the basis of dibenzoxyl peroxide and various tertiary amines' are applicable. Activated aluminum or aluminum oxide, various copper, zinc, cadmium and magnesium salts of organic acids, sodium silicates and cyanides

can also be used for pre-activation of the foam plastic.

Although all the aforementioned catalysts are in principle suitable for carrying out the method according to the invention, it is however simpler and more economically advantageous to use polymerization catalysts from the class of tin (II) and tin (IV) compounds. These catalysts also polymerize contaminated and aqueous formaldehyde into very high molecular weight, crystalline polyoxymethylenes, as especially Sn-JI-catalyzed formaldehyde polymerization is based on a different polymerization mechanism.

Tin (II) salts of organic carboxylic acids or tin (IV) dibutyl dilaurate are thus particularly preferred as polymerization catalysts according to the invention.

The implementation of the method according to the invention with tin (II) or tin (IV) compounds such as tin dibutyl dilaurate or mercaptides of divalent tin as well as 1:1 mixtures or addition compounds of these catalysts, as mentioned in the German patents 1,166. 474, 1,166,475, 1,172,851,

• 1,173,650, 1,173551, 1,174,985, 1,176,859 and 1,174,987, however, are not based only on the mentioned advantages, which these catalysts have. Tin-(II) and tin-(iV) compounds which also

As is known, a number of tertiary amines and polyamines play an important role in polyurethane plastic production as accelerators, especially when foaming polyether groups containing polyols with polyisocyanates. Thus, already during the foaming process, the number of formaldehyde polymerization germs in and near the cell walls of the finished polyurethane foam plastic is increased, so that often only a small post-activation is necessary to facilitate the implementation of the method according to the invention. This not only increases the volume-time yield in the subsequent aldehyde polymerization, but also gives evenly structured foams with almost 100 µm open pores.

According to the invention, foam plastics are all at least partially open-celled foam plastics of a natural or synthetic type, preferably polyurethane, polycarbonate, polyisocyanurate, polystyrene, polyvinyl chloride, carbamide formaldehyde, phenol formaldehyde, ABS polymer or polyamide. It is particularly advantageous to use foam plastics containing urethane and/or carbamide and/or amide and/or isocyanurate groups.

All polyurethane foam plasters can be used independently

of their production and their segment structure, e.g. such from common hydroxyl compounds such as linear or branched polyethers, polyesters, polycarbonates, polythioethers, polyacetals, primary, secondary and tertiary amino group-containing polyethers, . polyester amides, polymerization resp. polyaddition products of caprolactam, as suitable starting material as well as mixtures of the aforementioned types of materials. Foam plastics containing urea, biuret, allophanate or isocyanurate groups can be used without there being in any way observed disturbances in the polymerization tendency and the cell distribution of the polymerisation

end formaldehyde, Inhibition effects in sulphur-containing polyurethane foam plasters, e.g. such on the basis of polythioethers from thiodiglycol or other polyalcohols cannot be observed during the polymerization, nor with impregnated, with differ-

equally natural or synthetic latexes or cationic and anionic polyurethane dispersions pretreated, optionally filler or bitumen and tar-containing foam plastics.

Particularly preferred polyhydroxyl compounds

within the range of polyester plasters, each such from multi-

valuable alcohols and predominantly aliphatic carboxylic acids which occur within the technique in all variations. Porous, drawn polyols from the range of polyether foams are such on

basis of propylene oxide, ethylene oxide and their copolymers,

their polyaddition products to di- and higher functional polyols, such as trimethylolpropane, glycerol, sugar alcohols, penta-erythritol, their mixtures resp. their copolymerization products, e.g. with cyclohexene oxide, styrene oxide, tetrahydrofuran, trioxane and cyclic acetals such as 1,3-dioxolane, ring acetals from di- and triethylene glycol resp. thiodiglycol. Further-

can be mentioned as segment-building components cyanoethylated mono-

and polyamines, polyketimines and aldimines, their hydroxymethylation, hydroxyalkylation and propoxylation products as well as their with a deficit of polyisocyanates produced only short-.' chain-extended reaction products (polyols, containing urethane groups and carbamide groups).

The implementation of the method according to the invention is furthermore completely independent of the type of polyisocyanates bound in the foam plastics, such as hexamethylene diisocyanate, m- and p-xylylene diisocyanate, 1,2-diisocyanato-methyl-cyclobutane, isophorone diisocyanate or biuret-polyisocyanates of these diisocyanates, resp. polyisocyanates containing urethane groups of these diisocyanates, 1-methyl-benzene-2,4-diisocyanate, 1-methyl-benzene-2,6-diisocyanate, technical mixtures of these isomers,

4,4'-diisocyanato-diphenylmethane, its isomers and polynuclear aromatic polyisocyanates obtained by phosgenation of aniline-formaldehyde condensation products, also polyisocyanates obtained by telomerization of common isocyanates with ethylenically unsaturated compounds according to the method in German patent application P I .72O.747.5 can build up the polyurethane foam plastics, as well as liquid aliphatic polyisocyanates with semicarbazide groups, e.g. such as are obtained from N,N-dimethylhydrazine and hexamethylene diisocyanate.

As starting material. for the new method, formaldehyde and/or formaldehyde-releasing compounds and/or thioformaldehyde and/or trioxane, (trioxane is used according to the invention as a formaldehyde-releasing compound), optionally in the presence of cyclic acetals, cyclic ethers, vinyl monomers or trichloro- or trifluoroacetaldehyde. As formaldehyde-releasing compounds, formaldehyde hemiacetals of mono- or polyhydroxyl compounds can be mentioned, e.g. formaldehyde hemiacetals of methanol, cyclohexanol, ethylene glycol and butanediol-(1,4). Formaldehyde-releasing compounds also include ot-polyoxymethylene and paraformaldehyde. Highly purified formaldehyde or formaldehyde gases with a water content of up to 5% are preferably used according to the invention. As far as working with tin-(II)-preactivated matrices, the CHgO gases can contain up to 6% water.

Although the use of relatively anhydrous formaldehyde is often an advantage when carrying out the method according to the invention, it is however possible to carry out the method also in the presence of relatively large amounts of water. Thus, the method can also be carried out in a high-percentage formaldehyde solution, e.g. at 70-85°C, with finely ground paraformaldehyde or high molecular weight polyoxymethylenes which are also trioxane copolymers suspended in quantities of 10-50 wt?. The foam plastics are reacted for a few hours in this mixture and then freed from monomer formaldehyde with the help of water or alcohols. Polymeric thiomethylenes, i.e. polymers of thioformaldehyde, can also be used to modify the foam plastic by feeding hydrogen sulphide, ammonium sulphate, hydrogen sulphides or alkali sulphides, possibly with suspended paraformaldehyde, into highly concentrated, aqueous formalin baths.

If you want to work with anhydrous or relatively anhydrous formaldehyde gas, you can prepare the formaldehyde gas according to what is stated in the German patents I.I83.869, 1.037.705, 1.128.139, 1.140.921, I.167.807, 1.172.850 , 1.172.851, I.166.474, I.166.475 and I.174.985, possibly also purifying the formaldehyde gas in accordance with these regulations.

According to an advantageously chosen embodiment

the method according to the invention is based on soft, relatively open-celled polyurethane foam plasters, preferably from endless lightweight plastic bands with a width of 1-3 m and a thickness of 0.5-10 cm. These are drawn continuously through an activation bath containing the formaldehyde polymerization catalyst dissolved in an indifferent, organic solvent, such as toluene, benzene, cyclohexane or methylene chloride. The activation bath can also contain smaller amounts of mono- and polyisocyanates, especially such polyisocyanates that have become important as varnish components, for example tris-(isocyanatohexyl)-biuret, biuret group-containing polyisocyanates from isophorone diisocyanate, m- and p-xylylenediisocyanate, l- methylbenzene-2,4-diisocyanate or their addition products (= 3 mol) to m mol of a low molecular weight triol such as trimethylolpropane. After a light squeeze, this activated polyurethane plastic strip passes through a reaction chamber, into which a high degree of anhydrous formaldehyde gas is continuously fed. The length of stay can be up to approx. 1-80 minutes. The tape then leaves the reaction room and is liberated in a formaldehyde-free aeration zone, e.g. by using a stream of air, nitrogen, or carbon dioxide, from gaseous formaldehyde or, if desired, in another method step, it is continuously exposed to the influence of ketene, acetic anhydride, methanol, orthoesters of formic acid or other alkylating agents, which may be allowed to act in the vapor phase . If desired, a confection-ing or overcoating or impregnation with known polyisocyanates or polyepoxides is carried out using air-drying coating or varnish or by means of known cationic or anionic aqueous polyurethane dispersions.

If desired, the foam plastics, e.g. such as already consist of approx. 70 weight? polyoxymethylene, is reactivated with suitable formaldehyde polymerization catalysts and already again subjected to the reaction according to the invention, as it is possible to obtain foam plastics with up to 95 wt. polyoxymethylene. It is also possible to convert matrix particles with a diameter of 3-20 mm in a fluidized bed by gas treatment with formaldehyde into open-cell foam plastic particles with a diameter of 4-60 mm and a polyoxymethylene content of over 90 wt?.

To reduce flammability, the process products can be treated with known flame retardants before or after conversion.

Other suitable embodiments of the discontinuous methods are explained in more detail in the design examples.

The method according to the invention also entails the advantage that the foaming can be carried out, possibly under pressure, by, for example, a cylindrical form being filled completely loosely with a polyurethane foam. By introducing, for example, gaseous formaldehyde, which is fed from a paraformaldehyde decomposition apparatus, the formation of the foam plastic already takes place, which continuously grows by a three-dimensional expansion. After approx.

50 weight? polyoxymethylene is polymerized onto the matrix

the mold completely filled under pressure, as the new foam plastic has

good cohesion and in terms of toughness it surpasses conventional polyurethane foam plastic. Thus, shaped objects and building elements can be produced, which in the form of foam plastic have a surprising. toughness, dimensional stability and heat bending strength.

The thermoplastic polyoxymethylene is known to have a very high density of approx. 1.44 g/cm^. By carrying out the method according to the invention and by optimally utilizing the matrix function of polyurethane and/or polyisocyanurate foam plastics, one can, for example, produce polyurethane plastic foam with approx. 6-10 weight? foamed-in polyoxymethylene, in which the polyoxymethylene, based on the saturation, has a density of only 0.03 g/cm^. If, according to the new method, soft foam plasters are converted into semi-hard foam plasters with high firmness by, for example, polymerizing 30-40 wt. polyoxymethylene and copolymers and graft copolymers, the polyoxymethylene is foamed on average with a density of approx. 0.05- If one increases the amount of polyoxymethylene during the production of a foam plastic, which consists for the most part only of polyoxymethylene, as a composition of 85-90 weight? polyoxymethylene is obtainable, the polyoxymethylene has an average density of 0.07-0.08 g/crn^ and such a foam plastic is thereby almost completely open-celled, i.e. the density of the foamed polyoxymethylene formed has decreased to a l8 part. The soil storage and decay resistance of the new products is especially excellent.

An advantageously applied variant of the method according to the invention further consists in carrying out end group stabilization of the polyoxymethylenes during the aldehyde polymerization at the same time in order to transfer hemiacetal end groups to acetates, ethers, etc. according to the invention can be carried out to introduce heat-stable end groups in the polyoxymethylene chain. This takes place, for example, by post-treatment with methanol, orthoformic acid esters, with ketene, acetic anhydride in the presence of tertiary amines or Na- or potassium acetate as catalyst, by subsequent reaction with monoisocyanates such as phenyl isocyanate, methyl isocyanate or methoxymethyl isocyanate, as these reactions can also be carried out in the presence of polyoxymethylene stabilizers and antioxidants. The new products can be further modified by a subsequent grafting reaction with suitable vinyl monomers, e.g. in the swollen state, in the presence of water, in an organic solvent such as in the gas phase. If the new method according to the invention is carried out with trioxane in the presence of small amounts of 1,3-dioxolane, ethylene oxide, propylene oxide or suitable monomeric vinyl compounds with the aid of Lewis acids as catalysts, copolymers and graft polymers are formed, which can be broken down to a co-monomer building block by thermal decomposition located at both ends of the polymer molecule.

The stability of, for example, a polyurethane and/or polyisocyanurate polyoxymethylene foam plastic is increased by stabilizers such as phenols, aromatic amines, carboxylic acid amides, sulfonic acid amides, hydrazines, hydrazides, semicarbazides, hydrazones, carbamides, thiocarbamides, amidine derivatives, methylol compounds of melamine and dicyandiamide, hexahydrotriazine derivative which is usually also used for the stabilization of thermoplastically processable polyoxymethylene diacetates, dimethyl ethers or copolymers of trioxane with cyclic acetals, "cyclic ethers

or sulfonyl heterocycles.

The procedure products can in connection with

their production is possibly further assembled by, for example, being shaped, pressed, welded or equipped with diluted solutions and air-drying varnishes, for example on the basis of polyisocyanates and polyhydroxyl compounds resp. NCO-one-component varnishes, further by means of amines, polyamines or polyamidoamines curable polyepoxides and natural and synthetic latexes by spraying, dipping or overcoating.

The process products have a versatile applicability. Their new properties make their use advantageous wherever improved firmness in construction elements, improved resistance to hydrolysis, biocide and bactericidal degradation, improved petrol and oil resistance within the technical sector and the construction industry is required. For rigid and semi-rigid foam plastic types, the following application areas can be mentioned, for example: laminate constructions in carriage buildings, ship buildings, railway embankments and such areas as foundation roof slab constructions, which are exposed to constantly moist and fungicidal effects. The new foam plastics can be advantageously used as chassis protection with improved petrol and oil resistance in cars.

With the help of the new foam plastics, it is also possible to have the lowest possible volume weights, e.g. for very light foam plastics, while achieving improved water resistance as well as high petrol and oil resistance.

Although foam plastics containing carbamide and/or amide and/or urethane and/or isocyanurate groups constitute preferred matrices for carrying out the method according to the invention, these materials in no way constitute an absolute limitation of the possibilities according to the invention. The invention also includes the production of foam plastics on the basis of all plastic and natural foams, which have at least partial open cell, as a cell opening can easily be achieved also by a mechanical pre-treatment, as e.g. by means of puncture pressure with a metal disc equipped with needles approx. 80-200 cylindrical cells per cm2 can be introduced into the matrix material. Examples include foam plastics from carbamide-formaldehyde resins, phenol-formaldehyde resins, aminoplast lath foam, polystyrene, ABS polymer, polyvinyl chloride, polycarbonate and natural rubber respectively. foam plastic on a synthetic rubber basis. In general, by means of the method according to the invention, these foam plastics are transferred to new foam plastics, which are distinguished by low water absorption, high rot resistance, high oil and petrol resistance,

The new method provides especially polyurethane foam plaster and formaldehyde foam plaster with new properties. Beneficial properties include, in particular, increased open cell density, low volume weight due to a high polyoxymethylene portion, improved hydrolysis resistance, especially in foam plastics based on polyester-polyurethane foam plastics, improved petrol and oil resistance, high biocide and fungicide resistance, disinfecting effect, reduced brittleness of hard foam and polyisocyanurate foam. The new materials can therefore be used with particular advantage as insulation material, where, under constant damp influence, a fungicide attack must be expected, further risk of termite attack, wall salt when insulating foundations at an increased risk of rotting, for road substructures, for shoe and insole soles .

Polyoxymethylene foam based on polyether and polyurethane foam is also of interest in the area of so-called solid fuels. Foam plaster, which for example consists of 85-90 weight? polyoxymethylene, are to a large extent open-celled, have a large surface area and, as a result of their extremely high acid content in the absence of a flame retardant, are easily ignitable and combustible, as a significant amount of heat is released. These foam plastics can therefore be used as solid primary fuels and for the production of solid fuels, possibly in a mixture with additives and elastomers of diisocyanates and polyether polyols.

A significant technical advance also lies in the fact that from soft foam plastic with a low volumetric weight with an increase in the amount of polymerized, copolymerized or graft polymerized formaldehyde can produce a scale of foam plaster with different degrees of hardness without thereby having to change the matrix material used. The desired properties of the foam plastic can therefore be set by choosing the amount of formaldehyde. By setting a variable residence time during turnover, it is therefore possible to produce very different soft to hard foam plastics with 0.5-95 weight? bound polyoxymethylene on the basis of one and the same matrix type.

In the following examples, the parts given are parts by weight if nothing else is stated.

Example 1.

The formaldehyde gas used in this example was produced in the following way: The monomeric formaldehyde is obtained in a known manner by thermal decomposition of paraformaldehyde at normal pressure, for example in o-dichlorobenzene and was mixed in the pyrolysis vessel with pure, dry nitrogen or carbon dioxide as carrier gas. The formaldehyde was then passed through an extensive cooling system with a temperature of approx. -10 to +5°C and was fed continuously into a cylindrical reaction vessel, in which was stored a polyurethane soft foam plastic sheet with dimensions 28 cm x 9 cm x 0.5 cm (=.126 cm-'), the weight of which amounted to 5 g. Before the beginning of the experiment, the polyurethane foil had been pre-activated with 0.1 parts by weight of a tin (II) salt of 2-ethyl-caproic acid in methylene chloride solution and had been freed from adhering methylene chloride in a vacuum. The polyurethane foam used was produced by 100 parts by weight of a branched polyester of diethylene glycol, trimethylolpropane and adipic acid with an OH number of 62 was mixed with 3 parts by weight of an accelerator (adipic acid ester of N-diethylethanolamine), 2 parts by weight of emulsifier (oleic acid diethylamine) and 3.6 parts by weight of va-n. To this mixture was added 42.5 parts by weight of an isomer mixture, consisting of 80 parts by weight? 2,4-tolylene diisocyanate and 20 wt? 2,6-tolylene diisocyanate. and mixed well using a high-speed mixer. It had a volume weight on it

40 kg/m<3>.

On the described foam plastic foil with the dimension

28 cm x 9 cm x 0.5 cm, 10 parts by weight of high molecular weight polyoxymethylene were added drop by drop over the course of 20 minutes, with the foam plastic film serving as a matrix, i.e. the high molecular weight polyoxymethylenes were not present as powder, but adapted to the existing cell structure .

In this way, the cells were used three-dimensionally and a significant number of closed cells were opened. A snow-white foam plastic was obtained with a yield of 15 parts by weight, which plastic consisted of 66.5 parts by weight? polyoxymethylene. The dimension of the foil obtained after the reaction was 39 cm x 11 cm x 0.7 cm (= 300.3 cm<3>). The obtained snow-white, semi-hard foam plastic had a bulk weight of 49.5 kg/m<3> although the foam plastic consisted of 66.5 weight? polyoxy-

the methylene, which as thermoplastics as known has a density of

about. 1.4 (bulk weight 1400 kg/m3). The increase in volume compared to the matrix material therefore went up to 177 cm<3>, corresponding to approx. 141 volume?.

When this foam plastic was buried 10 cm deep in moist, loose soil, after 4 months of storage and continuous watering it was still firm and stretchable and, after cleaning and flushing with water, had practically retained its initial weight, while comparable parts by weight of the original the polyurethane plastic had completely rotted away.

Example 2.

This example shows that the production of foam plastic is also possible if the reaction is carried out under reduced pressure.

One proceeds analogously to example 1, but uses a monomeric formaldehyde, which was pyrolysed at a total pressure of

150 torr and a temperature of approx. 130°C. The formed monomeric formaldehyde gas was diluted by outflow from the pyrolysis vessel with nitrogen and toluene vapor to such an extent that the formaldehyde partial pressure rose to approx. 100 torr. This gas mixture then flowed through a wash bottle tempered to 35°C which was filled with toluene and was led from there to the reaction vessel used in example 1. In the reaction vessel there was the same matrix material as in example 1 with the same weight and the same dimensions. Also if one polymerized only at a total pressure of approx. At 150 torr, the gaseous formaldehyde was simply transferred from the foam plastic matrix in the manner described in example 1 into cell form and was polymerized during further pore opening of the foam plastic matrix. A snow-white foam plastic was obtained which, according to analysis, contained approx. 60 weight? polyoxymethylene polymerized or graft polymerized. The volumetric weight of this new material was 47 kg/

J>

Example 3-

One proceeded analogously to example 1 and here too produced the gaseous formaldehyde at normal pressure. The same foam plastic was used as matrix material for the formaldehyde polymerization, but different weight amounts of polyoxymethylene were allowed to grow in cell form in the matrix material.

a) 2.8 weight?

b) 4.8 weight?

c) 10.5 weight?

d) 24.1 weight?

e) 43.8 weight?,

In case a) a snow-white, very soft foam plastic was obtained, whose initial volumetric weight of approx. 40 was practically unchanged. In case b) a volume weight of 44.5- In case c) an elastic, snow-white, somewhat harder foam plastic appeared, while in case d) a prominent elastic, hard, snow-white foam plastic was already obtained. In case e) there was a snow-white, tough, semi-hard foam plastic of high quality, the volume weight of which was approx. 47.3 kg/m<3>. All foam plasters a) - e) had increased porosity. Also the foam plastic a), which only contained 2.8 weight? high molecular weight p-lyoxymethylene cellular built-in, proved clearly superior to the normal, untreated foam plastic in a decay test in moist soil.

Example 4.

The procedure was analogous to example 1, but a polyurethane plastic was used as matrix material, which had a volume weight of 25 kg/m<3> and which was produced from 100 parts by weight of a branched propylene glycol polyether with an OH number

56 (= trimethylolpropane as starting molecule), 4 parts by weight of water,

1 part by weight of a silicone stabilizer, 0.2 parts by weight of dimethylbenzylamine as catalyst and 0.27 parts by weight of a tin (II) salt of 2-ethylcaproic acid with the same polyisocyanate mixture as in example 1.

In each case, 5 parts by weight of polyurethane foil were used as matrix material for the formaldehyde polymerization and different weight amounts of polyoxymethylene were allowed to grow in cellular form in the matrix material, namely:

a) 2.0 weight? polyformaldehyde

b) 4.1 weight? polyformaldehyde

c) 10.8 weight? polyformaldehyde

d) .24.7 weight? polyformaldehyde

e) 74.5 weight? polyformaldehyde

f) 82.3 weight? pylyformaldehyde

g) 93.0 weight? polyformaldehyde.

Completely homogeneous, snow-white foam plasters were obtained.

Example 5.

The procedure was analogous to example 1, but a soft polyurethane foam plastic was used as matrix material, which had a volume weight of approx. 35 kg/m<3>. It was produced analogously to example 1 from 100 parts by weight of a mixture of branched propylene glycol polyether, the starting molecules of which were trimethylol propane and propylene glycol and contained incorporated approx. 3 weight? ethylene oxide (OH number 47), 2.7 parts by weight of water, 0.8 parts by weight of a silicone stabilizer, 0.1 parts by weight of permethylated diethylenetriamine and 0.23 parts by weight of a tin (II) salt of 2-ethyl-caproic acid as a catalyst according to what is indicated in example 1 with the same polyisocyanate mixture.

In each case, 5 parts by weight of polyurethane foil were used as matrix material for the formaldehyde polymerization and different amounts of formaldehyde by weight were allowed to polymerize or graft polymerize in the matrix material, namely:

In the cases a) b), very soft foam plasters with high rot resistance were obtained. In cases c) and d) there were elastic, but however hard, snow-white foam plasters. Types e) and f) were semi-hard, snow-white foam plastics with high petrol and oil resistance. A surprising type was the hard foam plastic g) with 93 weight? polyoxymethylene: It was completely open-pored. The starting matrix had the dimensions 20 cm x 7 cm x 0.5 cm = 70 cm3.

In contrast, the process product g) had the dimension 31.9 cm x 9.3 cm x 0.9 cm = 296.67 cm<3>. The new off-white foam plastic had a total weight of 30.4 g, to which the matrix material contributed 2.2 g. According to this, the volume weight of the dBn practically made of polyoxymethylene foam plastic was only approx. 103 kg/m<3>, while an unfoamed polyoxymethylene thermoplastic has a volume weight of 1400 kg/m<3>. The increase in volume of the lightweight plastic compared to the matrix material went up to 227 cm<3> (= 324 volume?). Example 6.

An elastic foam plastic of a polythioether was used as matrix material, which was produced from 100 parts by weight of a polythioether from thiodiglycol and 1,4-butylene glycol with an OH number of 74 and 3 parts by weight of adipic acid ester of N-diethylethanolamine,

■ 2 parts by weight of emulsifier (oleic acid diethylamine), 1.5 parts by weight of water and 29 parts by weight of an isomer mixture, consisting of 65 parts by weight of 2,4-tolylene diisocyanate and 35 parts by weight of 2,6-tolylene diisocyanate. The density of the matrix material was 73 kg/m<3>.

Man let 30 weight? high molecular weight polyoxymethylene grew cellularly in the matrix and obtained a snow-white, open-cell '.. polythioether foam plastic, the bulk weight of which went up to only 75 kg/m<3 >and which had excellent decay resistance.

Example 7.

An elastic polyurethane foam plastic was used as matrix material, which was produced from 100 parts by weight of a polyacetal of triethylene glycol, monooxytylated 1,4-butanediol and formaldehyde (OH number 70), 2.5 parts by weight of dimethylbenzylamine, 0.2 parts by weight of tin-(IV )-dibutyl dilaurate, 2 parts by weight of oleic diethylamine and 1.5 parts by weight of water and 31 parts by weight of an isomer mixture, consisting of 65 parts by weight of 2,4-tolylene diisocyanate and 35 parts by weight of 2,6-tolylene diisocyanate. The volume weight was 68 kg/m<3>. One lot 32 weight? high molecular weight polyoxymethylene grew cellularly in the matrix and obtained a snow-white, highly open-pored foam plastic, the volume weight of which went up to only 71 kg/m<3>.

Example 8.

One proceeded analogously to example 1 and produced gaseous formaldehyde at normal pressure. However, a brittle polyurethane foam plastic with a volume weight of 27 kg/m<3> was used as matrix material. Before the start of the experiment, the polyurethane foil was pre-activated with 0.1 parts by weight of a tin (II) salt of 2-ethylcaproic acid in toluene solution. The foil was exposed to the influence of formaldehyde vapors in a toluene-moist state.

On the described hard foam plastic foil, polymerized resp. graft polymerized during approx. 25 minutes different amounts of formaldehyde by weight, namely:

All lightweight plastics a) - e) had, with increasing polyoxymethylene content, an increasing reduction in brittleness and an increase in rot resistance.

If the same brittle matrix material open cell

increased greatly by the fact that per cm 2 of the foil mechanically, e.g. by a single insertion of a metal disk equipped with needles, as it achieved approx. 80 cylindrical cells per cm of the foil, a hard foam plastic was obtained which, compared to the starting material, had a very reduced brittleness and thus had been refined to a surprising extent by means of the method according to the invention. The open cell was maintained after the formaldehyde polymerization. The volume weight was 38.5 kg/m<3>.

Example 9«

The polyester-polyurethane-soft foam plastic matrix used in example 1 (5 parts by weight) was allowed to saturate 80 parts by volume of a solution of 5 parts by weight of pure trioxane in cyclohexane, 0.3 parts by weight of 1,3-dioxolane and 0.01 parts by weight of boron trifluoride dibutyl etherate and a reaction was allowed to stand on a hot plate at 65°C in a nitrogen atmosphere for one hour. Then, in an aqueous 0.3% triethylamine solution, the catalyst was removed and the trioxane not polymerized, after which it was washed with water and the foil dried. The yield was 7.5 parts by weight. A pure, white, open-celled foam was obtained with a content of 33.3 wt? trioxane copolymer with a volume weight of 44 kg/m<3>.

Example 10.

The polyether-polyurethane-soft foam plastic matrix used in example 2 (28 parts by weight) was wrapped as foil in the form of a loose cuff in several layers around a grid stirrer with a length of 9 cm and a height of 11 cm and was stirred for 15 hours at 65 - 70oC in a cylindrical reaction vessel, which contained 1.5 liters of a 75°C hot, 65% formaldehyde solution and approx. 80 parts by weight of a finely suspended high molecular weight polyoxymethylene with an average molecular weight of approx. 20,000, after which the stirrer was lifted out of the hot solution. It was freed from formaldehyde and smaller amounts of powdered parts of polyoxymethylenes with the help of water, washed with cold acetone and then dried in a vacuum at 40°C. 42 parts by weight of a foam plastic with open pores were obtained, which contained approx. 33.3 weight? polyoxymethylene and had a volume weight of 29 kg/m<3>

In a parallel experiment, the same polyurethane foam plastic matrix was exposed at the same temperature and in the same reaction vessel to the influence of hydrogen sulphide for approx. 8 hours. It was then processed in the same way as above. A lightweight plastic was obtained which, in addition to polyoxymethylenes, contained polythiomethylenes or copolymers of thioformaldehyde and formaldehyde. It had a sulfur content of 10.4%.

Example 11.

One proceeded analogously to example 4, but carried out pre-activation of the polyetherurethane soft foam plastic matrix, which had a volume weight of 25 kg/m<3> with the following activators resp. activator mixtures: a) 0.2 parts by weight of a tin (II) salt of 2-ethyl-caproic acid, 0.1 parts by weight of a zinc salt of 2-ethyl-caproic acid, 0.6 parts by weight of tri-(isocyanatohexyl)-biuret in 80 parts by volume methylene chloride as solvent. b) 0.2 parts by weight of a tin (II) salt of 2-ethyl-caproic acid, 0.1 parts by weight of a zinc salt of 2-ethyl-caproic acid and 0.8. parts by weight of a triisocyanate, consisting of an addition product of 3 mol of 1-methylbenzene-2,4-diisocyanate to 1 mol of trimethylolpropane in 80 parts by volume of methylene chloride as solvent. c) 0.3 parts by weight of dimethylbenzylamine, 0.1 parts by weight of a zinc salt of 2-ethylcaproic acid and 0.7 parts by weight of a polyisocyanate, which consisted of a polyisocyanurate of approx. 66 weight? 1-methylbenzene-2,4-diisocyanate and approx. 34 weight? hexamethylene diisocyanate, in 80 parts by volume toluene as solvent.

d) 0.2 parts by weight of a tin-(II) salt of 2-ethyl-caproic acid,

0.7 parts by weight of a diepoxide with epoxide end groups and

2.5? secondary hydroxyl groups, which had an epoxy equivalent of 290 and were prepared from 4,4'-dihydroxydiphenyldimethylmethane and epichlorohydrin. 0.5 parts by weight of bisketimine from 1 mol of diethylenetriamine and 2 mol of cyclohexanone in 80 parts by volume of toluene as solvent.

To 5 parts by weight of the thus activated foam plastic foil, within 30 minutes approx. 10 parts by weight of high molecular weight polyoxymethylene. One got in all cases

a) - d) snow-white foam plaster with approx. 66.5 weight? polyoxymethylene deli If the products were pressed with a pressure of 130 ato at

about. At 110°C, compact plastic with high soil storage resistance was obtained.

Example 12.

In the following synthetic foam plaster (20 parts by weight), which had a high degree of closed cells, 80 cylindrical cells per cm 2. After pre-activation analogously to example 1, the sample was treated with gaseous, anhydrous formaldehyde, obtaining foam plaster, which contained approx. 35 weight? polyoxymethylene, namely the following:

a) polycarbonate foam plastic

b) polystyrene foam plastic

c) polyvinyl chloride foam plastic

d) carbamide-formaldehyde foam plastic

e) phenol-formaldehyde foam plastic

f) ABS polymer foam plastic

e) polyamide foam plastic.

All foam plasters a) - g) did not contain polyoxymethylenes in powdery loose form on the surface, but instead formed relatively homogeneous foam plasters.

Example 13.

One proceeded analogously to example 5 and applied

a soft, elastic polyurethane foam plastic with a volume weight of 35 kg/m<3> as matrix, 26 parts by weight of the foam plastic was gas treated in the form of small particles with a diameter of 5 - 8 mm in a conical glass tube with a strong formaldehyde gas flow, The matrix particles contained 300 mg of tin- (II) salt of 2-ethyl-caproic acid as polymerization catalyst in finely divided form. In the course of 90 minutes, 436 parts by weight of completely open-cell hard foam plastic particles were obtained during a strong volume increase and cross-sectional increase of the particles, which to approx. 94 weight? consisted of polyoxymethylene.

Example 14.

One worked analogously to example 5, but used as catalyst 150 mg of dibutyltin dilaurate and 300 mg of endoethylene piperazine and gas treated the matrix particles at a temperature of -18°C with a formaldehyde-chloral gas mixture (3:1). After 5 hours had 80 weight? polyoxymethylene and polychloral resp. copolymers have been bound open cell to the matrix. The material's chlorine content was 18.4%.

Example 15.

The same foam plastic particles (= 28 parts by weight) were used as in example 13, but these were, however, impregnated before the subsequent fluidized bed polymerization with

a) 20 parts by weight of a 40?-ig natural rubber latex,

b) 20 parts by weight of a 39% polychloroprene latex,

c) 20 parts by weight of a 35 µg latex of ethylene-vinyl chloride copolymer, d) 20 parts by weight of a cationic 43 µg polyurethane dispersion which was prepared according to example 1 in DAS 1,241,104, e) 20 parts by weight of an anionic 44 ?-ig polyurethane dispersion which was prepared according to example 4 in DAS 1.241.104,

f) 20 parts by weight of a 50 µg chlorine rubber solution in xylene,

g) 20 parts by weight of a 20% polyamide solution (co-polyamide

of caprolactam and adipic acid and hexamethylenediamine) in water

containing chloral hydrate (80 µg solution),

h) 20 parts by weight of a 10 µg polycarbonate solution in methylene

chloride which was prepared from 2,2-bis-(p-hydroxyphenyl)-

propane (= bisphenol A) and phosgene.

After drying the particles in vacuum at 40°C,

the formaldehyde polymerization was carried out exactly as indicated in example 13. During approx. 90-100 minutes resulted in a strong volume increase and cross-sectional enlargement of the particles in all cases a) - h). completely adhesive-free, open-cell hard foam plastic particles, with from 26-36 parts by weight of the matrix material approx. 440 parts by weight fully open cell combination foam-

plastic, which for approx. 90-92 weight? consisted of polyoxymethylene.

Claims (6)

1. Procedure for the production of new foam plastics by treating per se known foam plastics with formaldehyde hyd, characterized in that at least partially open-cell foam plastic matrices, consisting preferably of polyurethane, polycarbonate, polyisocyanurate, polystyrene, polyvinyl chloride, carbamide-formaldehyde, phenol-formaldehyde, ABS polymer or polyamide, swell when exposed to formaldehyde, formaldehyde-releasing compounds or thioformaldehyde, which compounds are used as a highly concentrated aqueous solution or in gaseous form, and that at the same time or afterwards a very rapid polymerization of the formaldehyde or thioformaldehyde is carried out in and at the cell wall of the foam plastic matrix in the presence of polymerization ion catalysts and possibly of cyclic acetals, cyclic ethers, vinyl monomers or trichloro- or trifluoroacetaldehyde, whereby the new swollen foam plastic volume is irreversibly fixed. 2. Method according to claim 1, characterized in that foam plastic containing urethane and/or carbamide and/or amide and/or isocyanurate groups is used as foam plastic matrix. 3- Method according to claim 1 or 2, characterized in that highly purified formaldehyde or formaldehyde gases with a water content of up to 5% are used 4. Process according to claim 1-3, characterized in that tin-(II) salts of organic carboxylic acids or tin-(IV)-dibutyldilaurate are used as polymerization catalyst. 5. Method according to claims 1-4, characterized in that formaldehyde is polymerized continuously over endless polyurethane foam plastic bands in a gas treatment room. 6. Method according to claims 1-4, characterized in that the polymerization with formaldehyde gas takes place in closed forms.