DD202295A5 - PROCESS FOR PREPARING CYCLODEXTRIN FOAM POLYMERS - Google Patents

Abstract

The invention relates to a process for the preparation of novel, rapidly swelling cyclodextrin foam polymers having a solid foam structure and a large specific surface area. According to the invention, the cyclodextrins are reacted in one step or in two steps in the presence of an alkali metal hydroxide and water or in the presence of an acid and water with room-crosslinkers and foam-forming blowing agents. Optionally, the reaction mixture may still contain nucleation-promoting nucleators, such as fine quartz powder or china clay, and surface-active substances. As the blowing agent, by acidification, gas-decomposing substances, low-boiling organic liquids, e.g. Dichloric acid or chloroform, but it is also possible to incorporate gases such as air or nitrous oxide into the polymerized mixture. The foamed polymers obtained according to the invention have a high specific surface area and are distinguished by a high water absorption capacity and good swelling capacity.

Description

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Process for the preparation of cyclodextrin foam polymers

Field of application of the invention:

The invention relates to a process for the preparation of novel, fast-swelling cyclodextrin foam polymers having a solid foam structure and a large specific surface area.

Characteristic of the known technical solutions:

It is known that from syclodextrins by Raumvernetzungspolyraerisation water-insoluble products of high molecular weight can be obtained. As the room-crosslinking agent, any two- or polyfunctional compound capable of reacting with and linking alcoholic OH groups (U.S. Patent 3,472,835) is suitable. Particularly suitable for this purpose, the epoxy compounds (NL-PS 6 505 361). For special purposes, cyclodextrin polymers in bead form can also be produced (GB Pat. No. 1,244,990), whose mechanical properties can be significantly improved by the addition of a hydrophilic polymer (HU-PA CI-1845).

27.A1I £ 1,982 * O31529

These polymers are mainly used there for the solution of cleaning and separation tasks, where individual components must be separated from solutions and concentrated. Also, some selective analytical methods are known in which the said polymers are used as a standing phase in the chromatography.

Object of the invention:

In studies with cyclodextrin polymers has now been found that in the polymers prepared according to the above literature, a portion of the cyclodextrin rings is not accessible to the guest molecules to be bound. For this reason, the capacity for binding the guest molecules is in many cases less than the calculated, the invention, it is therefore cyclodextrin polymers produce, which have a large specific surface area and therefore a large capacity for binding guest molecules.

Surprisingly, it has now been found that this goal can be achieved if the cyclodextrin polymers or their derivatives are prepared by methods known per se, but in a foamed form. In this way, a novel product with a special structure and a large specific surface is obtained.

The products according to the invention are characterized not only by a large specific surface, low density and porous (closed cellular) structure, but surprisingly also by the fact that they swell very quickly and preserve this property even if by crushing (destroying the pores ) the foam structure is destroyed and as a result the density increases.

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In accordance with the process of the present invention, the fast-swelling cyclodextrin foam polymers of high surface area are prepared by adding cyclodextrins or their derivatives substituted by polar groups (for example, carboxyl, amino, hydroxypropyl, etc.) in one step or two steps. Room-crosslinking reaction polymerized, optionally simultaneously with the polymerization and incorporating hydrophilicizing groups in the cyclodextrin molecule and the system foams simultaneously. The foaming can be carried out by any known, adapted to the conditions of the polymerization method, it is only essential that polymerization and foaming occur simultaneously, since the resulting porous structure must be fixed by the space-crosslinking reaction. This is only possible if ^ there is an equilibrium between the increase in viscosity and the formation of the gas bubbles. This condition can be met in two ways: either the blowing agent is added only when the viscosity has already risen somewhat by pre-polyerization, or else the treebimide is added at the beginning and the reaction temperature is raised to the effective temperature of the blowing agent if the viscosity is already high enough and the thin liquid lamellae formed during foaming harden quickly.

As the blowing agent substances are added to the polymerization, which are gaseous at the temperature of the reaction and thus foam the reaction mixture.

Preferred low-boiling liquids (for example chlorinated aliphatic hydrocarbons) are used as blowing agents which evaporate at higher temperatures and thus generate foam. As propellant materials can also be used by

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Heat and by the action of acid or alkali present in the reaction mixture are decomposed to form gas, for example carbonates, such as sodium carbonate and ammonium carbonate, bicarbonates, borohydrides or heat decomposing organic substances, for example azo compounds, hydrazides, azides, nitroso .. The solution can also be frothed by mixing from the outset gas, for example, air or nitric oxide. This can be done, for example, by pressurizing the reaction medium and saturating it with gas. "When the pressure is reduced, the gas evolves and forms bubbles.

To form a uniform foam structure, it is expedient to use as further auxiliaries a nucleator (initiator point for the formation of gas bubbles) and optionally a surface-active agent. The nucleator used is generally pulverulent, non-soluble, non-swelling substances, for example quartz, diatomaceous earth, calcium silicate, clay or activated carbon. The nucleator is distributed in the reaction mixture, and gas bubbles are formed on the surface of the finely divided particles. A nucleator is the more effective the smaller the gas bubbles are and the more evenly distributed they are throughout the system.

Surfactants (for example, polysiloxanes) prevent, by lowering the interfacial tension, the membrane surrounding the bubbles from becoming too thin and breaking. In addition, by reducing the interfacial tension, the work required for bubble formation becomes smaller, which is why foaming begins at lower temperatures.

The process according to the invention can be carried out in one step or in two steps.

In the preparation in one step, the space-crosslinking agent and the blowing agent are added to s6-, β- or ^ -cyclodextrin or mixtures thereof and / or their derivatives modified by polar groups (for example carboxyl, amino, hydroxypropyl, thiopropyi) and foamed Mixture during the polymerization reaction on. Optionally, additional polar groups can be introduced during the reaction by addition of further reagents.

In general, however, the two-step process is preferred. In the first stage, the cyclodextrin and / or its derivative modified by polar groups is converted to a water-soluble polymer (for example in the process known from HU-PS 1961/80). To the solution of the prepolymer then the blowing agent and the other auxiliaries are added. The mixture is homogenised by stirring (this is especially important if the blowing agent used is a low-boiling liquid immiscible with the aqueous polymer solution, which must be emulsified well in the aqueous phase), then the space-crosslinking agent is added and during the polymerization process Mixture foamed at the same time. In the first or second step of the polymerization reaction, it is possible to introduce further polar groups into the polymer by adding appropriate reagents.

After each of the procedures described above, a white or yellow fabric is obtained which, after foaming, is held for a further 10-30 minutes at the respective temperature and then cooled. The sponge-like substance is soaked for a few hours in dilute acid and then washed neutral with distilled water. Then the material is dewatered by treatment with an acetone-water gradient of increasing acetone content, dried at 105 C and then comminuted to the desired particle size.

Preferably, one starts from concentrated (20-50%) cyclodextrin solutions and uses a large (5-40 molar) excess of crosslinking agent in the interest of rapid reaction.

The pH of the reaction mixture is selected depending on the properties of the room crosslinker. When using epoxy compounds, for example, an alkaline reaction medium is required, while in the case of dialdehydes in the acidic range is used. In the latter case, the prepolymerization is essential because in the acidic region, the cyclodextrins extremely poor, but their soluble polymers dissolve extremely well.

From the propellants, the different gases (air, nitrous oxide) and the low-boiling liquids (chloroform, dichloroethane) can be used at any pH. The borohydrides are decomposed by both acids and alkalis, and the carbonates and bicarbonates can be used in the presence of acids. To produce the corresponding foam structure, the following amounts of blowing agent are required: from the low-boiling liquids 0.2-2.5 ml / g cyclodextrin, from the carbonates and bicarbonates 0.0001-0.1 g / g cyclodextrin.

As a nucleator various silicates, for example, porcelain powder or clay, and also activated carbon in a concentration of 0.01-0.1 wt .-% are used.

As surfactants, it is preferable to use, for example, sodium stearate, sodium noleate or sodium lauryl sulfate in an amount of 0.005-0.05 g / g of cyclodextrin.

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The annealing _a structure of the foam formation is determined by the properties of the blowing agent used (in the case of a low-boiling liquid whose boiling point). It is expedient to choose a higher (60-8O ⁰ C) reaction temperature at which the Rauravernetzung runs fast and the foam structure is soon stable.

The cyclodextrin foam polymers prepared according to the present invention can be made under vacuum, atmospheric pressure or a few atmospheres of overhead pressure.

The new cyclodextrin foam polymers have a 5-15 times greater specific surface area than the block polymers made with the same reagent ratios without foaming. Due to their porous, sponge-like structure, the cyclodextrin rings they contain are more accessible, and therefore the binding capacity of the foaming polymers to foreign molecules is greater. They swell 3-5 times as fast as the block polymers in water, even in their comminuted state, their refuse, i. their volume increase is 1.2-2 times that of the block poylmeres.

A particularly favorable Ouellyerhalten show the various chemically modified derivatives, for example, the carboxyl, amino or hydroxypropyl containing foam polymers. ,

The new cyclodextrin foam polymers can be used more favorably than the heretofore known cyclodextrin polymers because of their greater specific surface area, their better oil properties and their faster complex formation.

Embodiments;

The invention will be explained in more detail with reference to the following examples, but is not limited to these examples.

Example 1 '

Preparation of β-cyclodextrin foam polymer in one step; Crosslinking agent: epichlorohydrin, propellant: dichloroethane

25 g (0.022 mol.) .Beta.-cyclodextrin is dissolved at 60 ⁰ C in a mixture of 6.5 g (0.16 mol) of sodium hydroxide in 25 ml water. To the solution are added 40 ml (0.5 mol) of dichloroethane and 0.4 g of porcelain powder. The mixture is stirred at 60 ⁰ C for one hour and then reacted at 75 ⁰ C with 12.5 ml (14.8 g, 0.16 mol) of epichlorohydrin. The resulting foam has a volume of 500 ml. It is neutralized by soaking in 0.01N hydrochloric acid, then washed salt-free with distilled water, dehydrated with an acetone-water mixture of increasing acetone content and finally dried. 36 g of a white powder is obtained, which consists to 65 % of cyclodextrin.

The product is passed through a sieve with a mesh size of 2 mm, then the apparent density is determined in a pycnometer with ethanol. 0.7 g / cm.

The ether vapor adsorption isotherm of the product was used to calculate Langmuir specific surface area. The result was a specific surface

from 200m / g. The pores have,

a diameter of 100-200

from 200m / g. The pores have, measured under the microscope,

When crushed to a particle size of less than iÖÖ.um break the pores, and in the pycnometer, the

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actual density of the material, which is 1.4 g / cm. From the two density specifications, the porosity is 50 % and the pore volume 0.75

3 cm / g. ,

According to the method of Ensslin, the water absorption of the

measured for crushed white powder.

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At a pressure of 9.8 κ 10 Pa (1 kg / cm), the maximum amount of water (4.7 ml / g) is absorbed within 4 minutes, whereby the volume increases to 3.2 times. From the white powder tablets are pressed (pressing pressure

8 4 2 9.8 x 10 Pa = 10 kg / cm); these take up the maximum amount of water (4.4 ml / g) within minutes, swelling to 5.5 times.

Example 2

Preparation of β-cyclodextrin foam polymer in two stages; Crosslinking agent: EjSichlorhydrin, blowing agent: "chloroform.

25 g (0.022 mol) of β-cyclodextrin at 60 ⁰ C in a mixture of 8.8 g (0.22 mol) of sodium hydroxide and 60 ml

-x water dissolved. While stirring continuously, 17 ml (20.1 g, 0.22 mol) of epichlorohydrin are added dropwise to the solution, the metering rate being 0.2 ml / min. The mixture is allowed to cool to 40 ⁰ C and then it is mixed with 0.4 g of porcelain powder and 40 ml (0.5 mol) of chloroform. Then the mixture is stirred at 40 C for one hour. As a product of the prepolymerization, a milk-like suspension is obtained. To this one gives

► tere 40 ml (47.2 g, 0.51 mol) of epichlorohydrin and a solution of 20 g (0.5 mol) of sodium hydroxide in 16 ml of water and then the mixture is heated to 55 C with constant stirring within 2-3 minutes The resulting foam has a volume of 800 ml. After the foam structure firm

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has been removed, the chloroform is removed by distillation. Then the product is washed, dried and comminuted in the manner described in Example 1. 45 g of a yellowish-white substance are obtained, which consists of 43 % cyclodextrin.

The Ensslin measured Wasseraufnähme'der substance at 9.3 χ 10 Pa pressure in 50 seconds 3.0 ml / g, the volume increases to 2.5 times. The tablets pressed from the powder with a pressure of .9,8 χ 10 Pa take in 2,7 ral / g of water in 90 seconds, whereby their volume increases to the 3,3fache. The product was extracted with ether; in the ether, no residual chloroform was detected by gas chromatography.

Example 3

Preparation of Carboxylic Group Substituted β-Cyclodextrin Foam Polyraer in Two Steps; Crosslinking agent: epichlorohydrin, propellant: dichloroethane.

25 g (0.022 mol) of β-cyclodextrin are coropolymerized in the manner described in Example 2, with the difference that 3.0 g (0.032 mol) of monochloroacetic acid are added to the mixture. This forms from the ß-cyclodextrin the carboxy derivative. A β-cyclodextrin molecule contains on average 1-2 carboxyl groups. In contrast to Example 2 is not allowed to cool the reaction mixture, but it sets the porcelain powder and the dichloroethane at 60 ⁰ C, whereupon it is stirred for one hour. 40 ml (47.2 g, 0.51 mol) of epichlorohydrin and 20 g of sodium hydroxide in 16 ml of water are then added to the prepolymer and the mixture is heated rapidly (within 2-3 minutes) to 75 ° C. About 600 ml of foam are added get the purified as described in example 1, Ge

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is dried and ground. 47 g of product are obtained which contains 43 % cyclodextrin.

The hnsslin measured water absorption is at

9.8 χ 10 Pa pressure in 30 seconds 4.0 ml / g, with the volume growing to 2.7 times. A tablet pressed from the product with a pressure of 9.8 χ 10 Pa absorbs 3.7 ml of water in 90 seconds, its volume increases to 4.2 times.

Biepiel 4

Preparation of <j (/ - cyclodextrin foam polymer in two stages; crosslinking agent: epichlorohydrin; propellant: n-heptane in vacuo.

25 g (0.026 mol) äC cyclodextrin are prepolymerized in the manner described in Example 2 'manner, with the difference that is not cooled to 40 ⁰ C, but 0.2 g of fine Ouarzstaub and 40 ml (.0,27 mol) n-heptane at 6O ⁰ C are added. The mixture is stirred at 60 C for one hour, then added with 40 ml (47.2 g, 0.51 mol) of epichlorohydrin and 20 g (0.5 mol) of sodium hydroxide in 16 ml of water and within 2-3 minutes 70 ⁰ C heated.

Then, the pressure in the reaction vessel is reduced by connecting a water jet pump to 1700-2000 Pa until the geräisch begins to foam. 500 ml of polymer foam are obtained, which is cleaned, dried and ground as in Example 1. 47.5 g of product are obtained which contains 45 % of cyclodextrin.

The water absorption measured according to Ensslin is 4.1 ml / g in 9.8 χ 10 Pa pressure in 20 seconds, whereby the volume increases to 2.5 times. One from the ground

Foam polyraer pressed at a pressure of 9.8 χ 10 Pa

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Tablet absorbs 3.6 ml / g of water in 40 seconds, the volume increase being 3, ifache.

Example 5

Preparation of Yft-Cyclodextrin Foam Polymer in Two Stages, Crosslinking Agent: Epichlorohydrin, Propellant: Nitrous Oxide.

25 g (0.019 mol) of cyclodextrin are prepolyarated in the manner described in Example 2. To the Vorpoylmer 40 ml (47.2 g, 0.51 mol) of epichlorohydrin and 20 g (0.5 mol) of sodium hydroxide in 16 ml of water. The reaction mixture is poured cold into a pressure-resistant container (volume 2 liters). In the container 13 g (2 liters, 0.3 mol) of nitrous oxide are pressed under a pressure of about 4 χ 10 Pa. By shaking the absorption of the gas is promoted in the liquid. The expanding pressure-reducing gas foams up the solution. The mixture is placed for 5 minutes in a heated at 105 ⁰ C oven, where the higher temperature, the foam volume continues to grow. 800 ml of foam polymer are obtained, from which after washing and drying 50 g of product with a cyclodextrin content of 41 % are obtained.

The product absorbs 4.3 ml / g of water at a pressure of 9.8 χ 10 Pa within 15 seconds, increasing its volume to 2.8 times. A tablet pressed out of it at a pressure of 9.8 × 10 Pa absorbs 3.9 ml / g of water within 35 seconds and swells to 3.8 times its volume.

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Example 6

Preparation of Amino-Substituted β-Cyclodextrin Foam Polymer in Two Steps; Crosslinking agent: epichlorohydrin,! Friction agent: air.

25 g (0.022 mol) of β-cyclodextrin are prepolymerized as in Example 2, with the difference that 3.0 g (0.037 mol) of dimethylammonium hydrochloride are added to the mixture. This forms from the β-cyclodextrin the amino derivative, wherein 1 molecule of cyclodextrin contains an average of 1-2 amino groups. 40 ml (47.2 g, 0.51 mol) of epichlorohydrin and 20 g (0.5 mol) of sodium hydroxide in 16 ml of water and finally 0.2 g (0.007 mol) of sodium lauryl sulfate are added to the prepolymer. The reaction mixture is stirred in a laboratory mixer at room temperature for 15 minutes to a foam and then placed for 5 minutes in a heated to 105 ⁰ C drying oven. 400 ml of foamed polymer are obtained from which 40 g of a white product containing 44 % cyclodextrin are recovered.

The product absorbs 4.1 ral / g of water at 9.8 χ 10 Pa pressure in 25 seconds and swells to 3 times as much.

One of the powdered product with a pressure of J 8

9.8 ε 10 Pa compressed tablet takes 3.4 ml / g in 60 seconds

Water on, with their volume on the Vief Ache 'increases. Example 7

Preparation of amino-substituted β-cyclodextrin foam polymer in two stages, room-crosslinking agent: epichlorohydrin, propellant gas: air.

25 g (0.022 mol) of β-cyclodextrin are converted into a foam polymer according to the procedure described in Example 6, with the difference that the chemical modification, i.

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the introduction of the amino groups, by means of dimethylammonium hydrochloride in the second stage of the process makes.

First, the β-cyclodextrin is prepolymerized in the manner described in Example 2. The mixture is cooled to room temperature and then 40 ml (47.2 g, 0.51 mol) of epichlorohydrin, 20 g (0.5 mol) of sodium hydroxide in ml of water and 3.0 g (0.037 mol) of dimethylammonium hydrochloride are added. Air is stirred into the reaction mixture by means of a high-speed stirrer (IKA Ultra Turax T45). As a result of intensive stirring, the mixture starts spontaneously and the foam structure becomes stable within a few moments. 800 ml of foam are obtained, which is purified and dried as described above. 37 g of an easily comminuted product are obtained.

The product absorbs 4.3 ml / g of water at 9.8 χ 10 Pa pressure in 45 seconds and swells to 2.5 times.

8 A tablet pressed from the product under a pressure of 9.8 χ 10 Pa absorbs 3.6 ml / g of water in 150 seconds, increasing its volume fourfold.

Example 8

Preparation of carboxyl-substituted β-cyclodextrin foam polymer in two stages; Space-crosslinking agent: epichlorohydrin, blowing agent: sodium tetrahydroborate.

25 g (0.022 mol) of β-cyclodextrin are reacted according to the manner described in Example 3 to carboxyl-substituted ß-cyclodextrin foam polymer, with the difference that the prepolymer instead of dichloroethane 0.5 g (0.013 mol) of sodium tetrahydrobocate is added. 42 g of a white product containing 46 % cyclodextrin

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The product adopts 9.8 χ 10 Pa pressure in 15 seconds 4.5 ml / g water and swells thereby to twice its volume ^T. One from the powdered foam poly

raer under a pressure of 9.8 χ 10 Pa pressed tablet _| picks up 3.6 g / L of water in 30 seconds and swells to 3.3 times its volume.

Example 9

Preparation of β-cyclodextrin foam polymer in two stages; Crosslinking Agent: Glutaraldehyde »Propellant: Sodium Hydrogen Carbonate«

25 g (0.022 mol) of β-cyclodextrin are prepolymerized as in Example 2. The solution of the prepolymer is acidified by adding 10 ml of η sulfuric acid (0.005 mol) and then mixed with 15 ml (16 g, 0.16 mol) of glutaraldehyde and 0.5 g (0.006 mol) Natriurahydrogencarbonat. 600 ml of foam are obtained from which 35 g of a product containing 40 % cyclodextrin are recovered.

The water absorption of the powder obtained after cleaning, drying and grinding is 4.5 ml / g at 9.8 × 10 Pa pressure in 50 seconds and is associated with an increase in volume of 3.5 times, one of this powder pressed tablet absorbs the maximum amount of water (4.2 ml / g) in 140 seconds and swells to 4.5 times its volume.

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Claims (10)

-16- ^ ~ τ υ y ν ν invention claim 1, Process for the preparation of novel, fast-swelling cyclodextrin foam polymers with a solid foam structure and high specific surface, characterized in that a) cyclodextrins with polyfunctional compounds, preferably with, based on 1 mol of cyclodextrin, 5-10 mol O epichlorohydrin at 60-75 ⁰ C and. at the same time Mixture, based on 1 mole of cyclodextrin; 0.2-23 mol of a decomposed by the action of heat and alkali propellant and 5-10 moles of an alkali metal hydroxide, preferably sodium hydroxide, further 100Θ-1200 cm water and optionally 5-20 g of a £ nucleator added, or b) cyclodextrins or their in situ produced amino or carboxy derivatives with polyfunctional compounds, preferably with, based on 1 mol of cyclodextrin, 8-12 moles of epichlorohydrin at 40-60 ⁰ C, wherein, on 1 mol of cyclodextrin, 8-12 moles of alkali metal hydroxide, K ^ J preferably sodium hydroxide, and 2200-3200 cm of water and 5-20 g mukleator be used, and that then related to the thus obtained prepolymer, based on one mole of cyclodextrin, 18-28 moles of epichlorohydrin and at 40-75 ° C in the presence of, based on 1 mole of cyclodxtrin, 18-28 moles of alkali metal hydroxide, preferably Natriurahydroxyd, and 600-900 cm of water and, if desired, in the presence of 5-10 g of a surfactant or 0.2-23 moles of a the action of caustic and heat decomposing propellant or to the prepolymer at 40-75 C in the presence of, based on 1 mole of cyclodextrin, - 17 - 0.2-0.3 mol of sulfuric acid and 400-500 cm of water, 6.5-8 mol of glutaraldehyde and at the same time 0.2-0.3 mol of a decomposed by the action of heat and acid blowing agent. 2. The method according to item 1, variant b, characterized in that one uses as starting material ^ -cyclodextrin or its in situ produced amino or carboxy derivative. 3. Process according to item 1 *, characterized in that the starting material used is β-cyclodextrin or its amino or carboxy derivative prepared in situ. 4. Method according to item 1 * variant b, characterized in that the starting material used is [> jH-cyclodextrin "or its in situ prepared amino or carboxy derivative. 5. Process according to point 1 to A _t, characterized in that the blowing agent used is a low-boiling organic liquid, preferably dichloroethane, chloroform or n-heptane, 6. The method according to item 1 to 4, characterized in that is introduced as the blowing agent gases, preferably air or nitrous oxide * in the reaction mixture. 7. The method of item 1, variant b, 2, 3 or 4, characterized in that the blowing agent is a decomposed by the action of heat and acid substance, preferably sodium bicarbonate used. 8. The method according to item 1 to 4, characterized in that the blowing agent is a decomposed by the action of Wärme.und alkali gas formation substance, preferably Natriumtetrahydroborat used. - 18 - yy % * 9. The method according to item 1 to 4, characterized in that one uses as a nucleator porcelain or Ouarzpulver, 10. The method according to item 1, variant b, 2, 3, 4 or 6, characterized in that the surface-active substance used is sodium lauryl sulfate. - 19 -