LT3423B - Polyurethane foam and process for the production them - Google Patents

Description

The present invention is directed to a polyurethane foam material (hereinafter referred to as PUR foam material) having a particularly homogeneous porous foam structure which pores are free of halogenated compounds. Such halogenated hydrocarbons, such as fully halogenated chlorofluorocarbons (ChFAs), are used in the art as foaming agents. The present invention provides processes for the production of PUR-free halogenated hydrocarbons used as foaming agents.

PUR foam materials are used in large quantities for a wide variety of applications, such as cushions used as an intermediate layer when placed under the carpet, upholstered furniture, packaging, as an insulating material in living rooms and refrigerated rooms. Industrially, PUR produces soft, semi-hard and hard foam. Soft foam is usually made from carbon dioxide using foam. Carbon dioxide is prepared as a starting compound by use of diisocyanate and its reaction with water which is added to the reaction mixture.

However, some soft foams are obtained using ChFA as foams. ChFA foams produce most of the solid foam. ChFA is used in large quantities for these purposes. Substantial amounts of foam are lost in the manufacturing process or are released when the material breaks down the pores of the PUR material. As foaming agents, ChFA delivers the desired results in many aspects. They give the FUR material a non-flammable property. The PUR materials obtained from these foams also have other desirable physical properties, such as low thermal conductivity, expressed in low lambda levels, since such materials are very necessary for the production of upholstered furniture and seats (cushions). and other buildings. The PUR materials obtained with these foams can be classified into groups with the relatively high thermal insulation required for various applications of foam materials. By adding auxiliary materials to the blend of starting components, the flame retardants, the resulting PUR foam materials can be further enhanced by their fire resistance properties to refractory grades B2 and JV. Because PUR-foam materials are made from liquid starter components, foam, the use of ChFA or water results in a very uniform porous structure with a low bulk density. This ensures easy foaming of the material in the mold or on the conveyor belt. The latter procedure is used to obtain insulating sheets from solid PUR materials used in buildings or similar structures. This method can also be used to produce PUR foam materials with a hard layer on each side of the foam sheet (either flexible or solid), thereby obtaining a sandwich type foam structure.

However, from an environmental point of view, the crucial point regarding foam material and its production is that for such materials as PUR foam solid materials, foaming agents are almost exclusively ChFA, and since ChFAs are ozone depleting substances, they are has a very negative effect on the ozone layer. Therefore, the use of such foams is undesirable and even banned in many countries. As a result, intensive research has been underway for several years to replace ChFA foams partially or even completely with regard to their undesirable ozone-depleting properties.

For example, the production of soft PUR-foams has been tested by combining the addition of water to a used isocyanate-containing foam material with other attributes such that CO ₂ is the major or auxiliary foam, reducing or even stopping unwanted release of harmful ChFA. However, such methods adversely affect the physical properties of the resulting PUR-foam materials. The early formation of CO ₂ as a foaming agent results in a large number of open pores in the PUR-foam material. In addition, the material, due to its incomplete polymerization, is completely soft and the pore walls of this material are easily broken. This pore wall injury may still be tolerable and even desirable in soft PUR foam materials, but it is completely undesirable in hard PUR foam materials which must exhibit high mechanical strength. In addition, the water used to make CO ₂ as a foaming agent adversely affects the insulating properties of the resulting PUR-foam material, whether solid or soft foam is produced. Finally, the use of water greatly facilitates the resulting PUR-foam material, since C0 ₂ as a foaming agent must react with one part of water with 16 parts of diisocyanate, that is to say, an amount of diisocyanate must be added to the mixture of starting components. The use of foamed ChFA requires a significantly lower amount of diisocyanate.

Other organic materials, volatile PUR-foam starting materials, may not be used or have the required properties in their reaction, as halogen-free organic products are often highly flammable or even form highly explosive mixtures with air oxygen. Therefore, such foams are unsuitable for technical safety and should be avoided even if the manufacturer of such materials guarantees reliable removal of organic liquid vapor from the reaction. In addition, in many of the above-mentioned applications, when using PURPU materials, their closed pores may break and organic vapors and liquids released from the pores may be hazardous. On the other hand, the use of foams is UV stable (see Jap.

side, free from was described with painted PUR-foam par. No. 57-126815). However, these materials for halogen production do not have the required low bulk density.

Further attempts to replace or reduce the amount of ChFA were carried out by mechanically mixing the air into a mixture of starting polymerization materials. There is a known method of mechanically (with the aid of blades) mixing air into an OH-containing component or a diisocyanate component, or both. However, in this case, due to the uneven density of the air-alcohol or air-isocyanate mixture, the dosage of the components is very difficult. In addition, the resulting foam material has a highly heterogeneous porous structure as desired. The smooth and fine porous structure of low density foam materials is a prerequisite for good insulation properties of the resulting foam material. However, with the foam alone, air cannot achieve the desired low bulk density of 30 g / cm ³ or less.

The possibility of replacing ChFA with partially halogenated hydrocarbons such as fluorocarbons (FA) was considered. However, such an alternative is very expensive and its long-term effects on ozone depletion have not yet been fully investigated.

It is an object of the present invention to provide a PUR-foam material which pores are free of halogenated hydrocarbons, e.g. a foam material having a low bulk density, low lambda values (i.e., low thermal conductivity, good thermal insulation properties) and good fire performance (i.e., a class of flammable products); as well as the method of preparing such PUR-foam materials which do not use foaming agents, are classified as halogenated hydrocarbons.

According to the present invention, PUR-foam materials, namely, PUR-foam, are materials having partially closed or almost completely closed pores which are free of ChFA or FA halogenated hydrocarbons and also contain low levels of foams used in the production of such PUR foam materials. the process furthermore said foams are liquid organic products selected from the group consisting of lower alkanes with 3-6 carbon atoms and mixtures of several of these lower alkanes containing 3 to 6 carbon atoms boiling at normal pressure , -10 to + 70 ° C, and this foam has a uniform porous structure and a bulk density of 30 g / cm ^{3 in a} row and less. The PUR materials made from the aforesaid foams further contain a series of additives such as catalysts, pore stabilizers, crosslinking agents, flame retardants and / or emulsifying agents. The pores of the PUR foam fabricated may contain a small amount of volatile foam up to 30% by volume. In any case, such amounts are even lower depending on the shelf life, storage temperature and pressure of the initial PUR materials produced by PUR foam materials, i.e. conditions affecting the exchange of ambient air with volatile foams during the diffusion process through the pores of these materials.

In a preferred embodiment of the present invention, the foam pores, in addition to the foam residue of the present invention and the air which diffuses into the pores during production and storage of this PUR foam material, replace the vaporized foam with additional gas such as nitrogen. it contains air, an inert gas, a mixture of nitrogen and an inert gas, or a mixture of several inert gases. The best auxiliary gas in this variant is argon.

According to the present invention, the PUR-foam material comprises one or more known liquid or solid flame retardants, most preferably phosphorous or boron containing flame retardants. According to the present invention, these flame retardants are present in an amount of from 5 to 35% by weight, preferably from 10 to 20% by weight, based on the total weight of the PUR foam material. According to the present invention, it is preferred that the PUR-foam materials contain solid flame retardants such as, for example, phosphoric acid, metaphosphoric acid, polyphosphoric acid and ammonium salts of boric acid.

In another more preferred embodiment, the PUR foam material, which is made entirely of foam or a foam and solid flame retardant, comprises a lower alkane phosphonate and a lower alkyl ester of the formula as a liquid phosphorous flame retardant.

O

II

RP - (OR ') ₂ , wherein R and R' are lower alkyl having from 1 to 4 carbon atoms, preferably methyl. It is particularly advantageous to use this special liquid flame retardant in combination with urea, namely from 10 to 20% by weight, based on the weight of the liquid phosphorus flame retardant. More preferably, the liquid phosphorus containing flame retardant contains urea dissolved in the liquid flame retardant prior to saturation of the resulting solution.

Catalysts employ basic or strongly basic catalysts in conventional amounts, for example, catalysts such as alkali metal and weak acid salts, most preferably salts of alkanoic acids such as acetic or octanoic acids. According to the preferred embodiment of the present invention, this catalyst or its residues may remain in the manufactured PUR-foam material.

According to another, more preferred embodiment of the present invention, the PUR-foam material contains a small amount of a special foam as well as a solid flame extinguisher, the ammonium salt of the aforementioned acid, as well as the most preferred liquid flame extinguisher and urea. as well as the catalyst - basic to strongly basic. Depending on the particular premix, the PUR foam material may contain up to 10% by weight of the emulsifier according to the present invention. Most preferably, according to the present invention, the PUR foam material comprises an emulsifier, saturated or unsaturated fatty acid, its ester or derivatives thereof.

The process for preparing the PUR foam material described in the present invention is characterized in that the foam employs a liquid organic agent having a halogen molecule and comprising a mixture of lower alkanes having from 3 to 6 carbon atoms and several such lower alkanes having from 3 to 6 carbon atoms, a group; in addition, said liquid foam has a boiling point under normal pressure of -10 to + 70 ° C, and the said foam is added to a mixture of the alcoholic parent component and the isocyanate parent component for the PUR foam material in the usual proportions between the indicated alcoholic parent component and an isocyanate starting component; said mixture also contains other additives, such as catalysts, pore stabilizers and flame retardants, in conventional amounts or, preferably, the said foam is finely dispersible in the alcoholic initial component for the PUR foam material, with the addition of the other additives mentioned above, followed by , this finely divided product is mixed by conventional means with an isocyanate starting component to obtain a PUR foam material, the polymerization of the mixture of said starting materials being carried out under conventional conditions, that is, at ordinary temperature.

In both cases of the above procedure, the starting materials are added to the amount of foaming agent necessary to obtain the desired density PUR-foam, i.e. to obtain the desired degree of foaming of the foam material being produced. If greater foaming is required, i.e. a lower density foam material is required, which requires the addition of a larger amount of liquid foam to the appropriate starting materials. One of ordinary skill in the art can calculate the exact amount of foam to be added to the premix based on the known volume of the foam liquid to be evaporated and the desired density of the final PUR foam material. Such calculations are also known for other foams such as ChFA. If it is necessary to take into account the boiling point of the liquid foam used, the polymerization may be effected by reducing or increasing the pressure relative to normal at the foaming stage. The manufactured PUR foam material is stored for 2 days to several months, preferably 2 to 7 days at room temperature or slightly elevated temperature (about 45 ° C) and at atmospheric or slightly lower pressure.

In a preferred embodiment, the initial emulsion comprises a liquid and / or solid fire extinguisher containing 5 to 35% by weight, preferably 10 to 20% by weight, based on the total weight of the final foam material, of phosphorus or boron derivative. The preferred flame extinguisher is the ammonium salt of the phosphorus and / or boron compound, preferably in solid, crystalline form.

According to another preferred embodiment of the present invention, a liquid flame extinguisher, an ester of phosphonic acid and a lower alkane of the formula

O

II

RP - (OR ') ₂ - wherein R is a lower alkane with 1-4 carbon atoms, namely, an ester of a lower alkanol with 1-4 carbon atoms; -OR 'is an ester group. Of this group, the preferred dimethyl ester of methylphosphonic acid is one in which R and R 'are both methyl. In another, more preferred embodiment of the present invention, the liquid phosphorus-containing flame retardant (formula above) is used in admixture with urea, preferably from 10 to 20% by weight (urea), based on the total weight of the liquid phosphorus flame retardant. According to a preferred embodiment of the present invention, urea is used in admixture with a liquid flame retardant in amounts such that the urea solution in the liquid phosphorus containing flame retardant is saturated. With this last variant, good fire performance was obtained over a long period of time, which is essential when using ready-made PUR-foam materials.

Useful are native diisocyanates or PUR-parent polymers, two free isocyanates are known. In addition, alcohols or other compounds having at least two groups in the molecule are known to the person skilled in the art and have at least two free hydroxyl groups in the molecule, such as polyether polyols and / or polyester polyols. It is also known to a person skilled in the art how these two groups of starting components and the weight ratios of the alcohol and diisocyanate compounds interact with each other to form soft, semi-solid and solid PUR foam materials.

Many German and foreign patents and patent applications can be invoked in this case, as well as other generic publications classified under IPC class C 08G, subclass 18. An example of a general publication is Riompo Chemieleksikon, 7th Edition, 1975, pp. 2774-2775. and other links there.

Suitable liquid organic compounds to be used in the process of the present invention as foaming agents are those compounds which are insoluble in the alcohol component thereof or compounds which are practically insoluble in said alcoholic component but which form emulsions with the alcohol component thereof. preferably, up to 10% by weight, based on the alcoholic component of PUR, of the initial component in the presence of an emulsifier, if necessary. Examples of suitable foaming agents are lower alkanes having from 3 to 6 carbon atoms, such as n-butane, n-pentane, isopentane, n-hexane, dimethylbutane or a mixture of several such compounds, obtained as a by-product from the distillation of mineral oil and commonly burned. For best results, and therefore the most suitable foamers are selected from the group of n-pentane and isopentane. The PUR foam material produced by these foams has a very even, porous structure with small pores that remains even after long storage of the foam material produced.

Liquid and solid flame extinguishers used in the process of the present invention, namely flame retardants containing phosphorus or boron, as well as the most valuable ammonium salts of these compounds, are known to those skilled in the art of PURLT 3423 B foam. Examples of such useful compounds are borates, phosphates, metaphosphates, polyphosphates and the esters of lower alkanols and lower alkanephosphonic acids mentioned above. In order to obtain products of refractory class B2, flame retardant quantities used are, for example, in the order of 6000 g / m ³ and above. Particularly useful and therefore the most suitable solid flame retardants are the ammonium salts of this group. Other suitable flame extinguishers belonging to the group of best solid flame extinguishers are barium metaborate and zinc borate. Solid flame extinguishers are added to the mix without the use of a high pressure dosing pump as these products are abrasive powders. Therefore, such solid flame extinguishers are added to the premix using a spiral mixer which is plugged into the production line immediately after the liquid starting material mixing unit (PUR starting components plus foam).

Suitable emulsifiers are known to those skilled in the art. Suitable emulsifiers are saturated and unsaturated fatty acid products such as alkanolamide ethoxylate of fatty acids.

The preferred agents for cross-linking in PURPs are materials known to the expert, such as certain alkaline Mannich bases. Even small amounts of water, such as 0.5 to 2% by weight based on the initial weight of the mixture, can be used as crosslinking agents and therefore water can be added to the initial mixture. The isocyanate content must be slightly increased in this regard to maintain a correct ratio between the alcoholic parent component and the isocyanate parent component. Both types of stitching agents mentioned above can be used.

It is recommended to use an emulsifier for emulsifying liquid foam in the initial alcoholic component of the PUR foam material according to the present invention. In this case, the formation of a liquid foam emulsion and the initial alcoholic component is significantly improved. Such formation of an emulsion of the liquid foam and the initial alcoholic component is necessary in the process described in the present invention. The addition of an emulsifier later, however, promotes the exchange of evaporated liquid foam with air during the final storage period of freshly prepared foam material.

The duration of the final storage period during which the spent liquid foam is exchanged with air depends on the specific starting components used, i.e. the foam used, the ambient temperature, possibly the reduced pressure used, as well as the type and amount of solid flame extinguisher used, as well as the base catalyst and / or emulsifier used. In some cases, PUR foam materials already meeting fire class B2 requirements are obtained without storage, depending on the choice of starting mixture and amount of flame extinguishers used, as well as the catalyst used. As a rule, the holding period is from 2 to 7 days, sometimes much longer, for example up to 6 weeks, or even rarely up to 4-6 months. Usually the final storage period ends after 3-4 days. The exchange of the used foam with a non-hazardous gas such as air can be controlled by the ignition of the resulting foam material. As stated above, the ignition improves after a certain final storage period. Another criterion is a certain increase in thermal conductivity from 0.021 kkal m / hr ° C immediately after the start of storage to 0.025 kkal m / hr ° C. This thermal conductivity of 0.025 kcal m / h ° C does not change much over a period of time, suggesting that the spent organic foam has been exchanged with ambient air to the desired degree and that this exchange has virtually ceased. As stated above, depending on the choice of the various components and / or the amount and type of solid flame retardant used, PUR foam materials having class B2 properties without final storage can be obtained. The thermal conductivity from 0.025 kcal m / hr ° C can be reduced to 0.0205 kkal m / hr ° C, which was previously unavailable.

According to the present invention, the thermal conductivity of the PUR-foam material increases during storage, but here the reverse is true as regards the flammability of the resulting material. Immediately after the foaming stage, the PUR-foam material is often highly flammable. Storage of PUR foam reduces its flammability and improves daily. Holding the PUR foam material for 2-7 days, for example 4 days, achieves a flammability index corresponding to combustion class B2 or B1 in the presence of polyisocyanurate foams and high flame retardants. As mentioned above, the non-flammable stability of the PUR foam material according to the present invention is enhanced by the use of a liquid, phosphorus-containing, fire extinguisher in combination with urea.

It should be noted that both the PURPU foam material described herein and the process for preparing it are variants in which small amounts of halogenated hydrocarbons or even ChFAs are blended with the foaming agent and such a combination is used in the manufacture of a product as defined in DIN 18164. and includes only PUR foam materials obtained by foaming of halogenated hydrocarbons by chemical reaction with compounds containing acidic hydrogen. The organic liquid foam used in the present invention can be readily mixed with a small amount of halogenated hydrocarbons so that the required hydrocarbons are replaced by up to 95% or even 99% with the liquid foams described in the present invention. In addition, the use of emulsifiers in this process is not affected by small amounts of ChFA or methylene chloride. The boiling range of the latter compound was determined by the present invention (boiling at 40 ° C).

The following are illustrative examples of the present invention.

EXAMPLE

The solid PUR foam is obtained by emulsifying at 22 ° C a mixture of:

- 50 parts by weight of a polyether alcohol with a hydroxyl number of about 550 (viscosity at 25 ° C about 8000 sp) belonging to the Shell Cherine CAPADO L product group;

- 30 parts by weight of a saturated polyether having a hydroxyl number of about 500 (viscosity at 25 ° C of about 8000 to 10 000 sp);

- 20 parts by weight of an aromatic polyether alcohol with a hydroxyl number of about 500 (viscosity at 25 ° C of about 5000 sp);

- 7 parts by weight of liquid flame retardant - dimethylmethylphosphonate (DMMF) containing 26% phosphorus;

- 5 parts by weight of Henkel AG emulsifier EMULGIN;

- 2 parts by weight of silicone as a pore stabilizer;

- 28 parts by weight of solid flame retardant - ammonium polyphosphate;

- 3 parts by weight of the catalyst - alkali metal acetate;

- 18 parts by weight of n-pentane.

This emulsion is mixed with 172 parts by weight of MDI diisocyanate (diphenylmethane-4,4'-diisocyanate) in a conventional PUR foam production process. The resulting mixture is converted to foam in a conventional foam making machine at normal pressure and room temperature. The resulting PUR-foam is finally stored for 4 days at normal pressure and room temperature (20 ° C).

The resulting PUR foam material has the following properties:

Density, immediately after foaming:

30-40 g / cm ³ , Immediate pressure after foaming: approximately 1.3 kp / cm, Pressure after 4-6 weeks storage: 1.6-1.7 kp / cm ² , Ignition immediately after foam formation: short-term flammability, which is self-extinguishing, after 4 days storage: class B2.

Thermal conductivity:

immediately after foaming: approximately 0.021 20 days after foaming: 0.024-0.025 after 14-16 weeks storage: 0.022 after 4-6 months storage: 0.0205

EXAMPLE

The solid PUR foam is obtained in the following manner:

The following mixture is emulsified at room temperature:

- 50 parts by weight of a polyether alcohol having a hydroxyl number of about 550 (viscosity at 25 ° C of about 8000 sp);

- 30 parts by weight of a saturated polyether having a Mannich cross-linked base agent having a total hydroxyl number of about 500 (viscosity at 25 ° C of about 8000 to 10,000 sp);

- 20 parts by weight of an aromatic polyether having a hydroxyl number of about 500 at about 25 ° C (about 5000 sp);

of alcohol, {viscosity

- 7 parts by weight of liquid flame retardant - dimethyl methyl phosphonate;

- 5 parts by weight of Henkel AG emulsifier

EMULGIN;

- 2 parts by weight of silicone as a pore stabilizer;

- 48 parts by weight of solid flame retardant - monoammonium phosphate;

- 3 parts by weight of catalyst - potassium acetate;

- 26 parts by weight of n-pentane containing up to 5% of propane and n-butane.

the resulting emulsion is mixed with 172 parts by weight of MDI diisocyanate in a conventional PUR foam production process. The resulting mixture is foamed at normal pressure in a conventional machine with an endless conveyor belt. The resulting PUR-foam is finally stored for 4 days at normal pressure and room temperature (20 ° C).

EXAMPLE

The solid PUR foam is obtained in the following manner:

mix:

- 52 parts by weight of a polyether alcohol having a hydroxyl number of about 550 (viscosity at 25 ° C of about 8000 sp);

- 31 parts by weight of a saturated polyether having a crosslinking agent and having a hydroxyl number of about 500 (viscosity at 25 ° C of about 8000 to 10,000 sp);

- 20 parts by weight of an aromatic polyether alcohol with a hydroxyl number of about 500 (viscosity at 25 ° C of about 5000 sp);

parts by weight of liquid flame retardant DMMF containing 26% phosphorus;

- 1 part by weight of water;

- 5 parts by weight of emulsifier EMULGIN C4;

- 2 parts by weight of silicone as a pore stabilizer;

- 50 parts by weight of solid flame retardant - diammonium phosphate;

- 2 parts by weight of catalyst - potassium octoate;

- 25 parts by weight of n-pentane emulsifiable at 22 ° C.

172 parts by weight of MDI diisocyanate are added to this emulsion and the resulting mixture is foamed under normal pressure in a conventional machine with an endless conveyor belt.

The resulting PUR-foam is finally stored for 4 days at normal pressure and room temperature (20 ° C).

EXAMPLE

The solid PUR foam is obtained in the following manner:

mixture of:

- 50 parts by weight of a polyether alcohol having a hydroxyl number of about 550 (viscosity at 25 ° C of about 8000 sp);

parts by weight of a saturated polyether having a hydroxyl number of about 500 (viscosity at 25 ° C of about 8,000 to 10,000 sp);

- 20 parts by weight of an aromatic polyether alcohol with a hydroxyl number of about 500 (viscosity at 25 ° C of about 5000 sp);

parts by weight of liquid flame retardant DMMF containing 26% phosphorus;

- 5 parts by weight of EMULGIN 550 emulsifier by Henkel AG;

- 2 parts by weight of silicone as a pore stabilizer;

- 1 part by weight of water as cross-linking agent;

- 38 parts by weight of solid flame retardant - ammonium polyphosphate mixed with 5% zinc borate;

- 3 parts by weight of an alkaline-acetate catalyst;

- 27 parts by weight of n-pentane emulsified at room temperature.

172 parts by weight of MDI diisocyanate are mixed with the above emulsion and the resulting mixture is foamed under normal pressure in a conventional continuous foam making machine. The resulting PUR-foam is finally stored for 4 days at normal pressure and room temperature (20 ° C).

EXAMPLE

The solid PUR foam is obtained in the following manner:

mixture of:

- 50 parts by weight of a polyether alcohol having a hydroxyl number of about 550 (viscosity at 25 ° C about 8000 sp) belonging to the Shell Chemie CAPAI 0 I product group;

- 30 parts by weight of a saturated polyether having a cross-linking agent having a hydroxyl number of about 500 (viscosity at 25 ° C of about 8000 to 10,000 sp);

- 20 parts by weight of an aromatic polyether alcohol with a hydroxyl number of about 500 (viscosity at 25 ° C of about 5000 sp);

parts by weight of a saturated urea solution in a liquid flame extinguisher; dimethylmethylphosphonate (DMMF) containing 26% phosphorus; said solution has 1.05 parts by weight of urea to 7 parts of DMMF;

- 5 parts by weight of Henkel AG emulsifier EMULGIN;

- 2 parts by weight of silicone as a pore stabilizer;

- 28 parts by weight of solid flame retardant polyphosphate;

ammonium parts by weight of an alkali metal acetate catalyst and 18 parts by weight of n-pentane emulsified at 22 ° C.

172 parts by weight of diphenylmethane-4,4'-diisocyanate were blended with the above emulsion by conventional PUR foam production and the resulting mixture was polymerized by foaming at room temperature and normal pressure in a conventional continuous foam making machine. The resulting PUR-foam is finally stored for 4 days at normal pressure and room temperature (20 ° C).

After such storage for a further 6 weeks, the ignition was considered to meet the requirements of class B2 even when heated to moderate temperatures.

Claims (24)

DEFINITION OF INVENTION 1. A polyurethane foam material comprising a catalyst, a pore stabilizing agent and / or a flame retardant, characterized in that it contains no halogenated hydrocarbon pores and contains a small amount of the foaming agent used in the manufacture of the foam material. consisting of lower alkanes having from 3 to 6 carbon atoms and mixtures of said lower alkanes, and said foaming agent having a boiling point at normal pressure of -10 to + 70 ° C. 2. The polyurethane foam material of claim 1, wherein the lower alkane is n-pentane. 3. The polyurethane foam material of claim 1, wherein the lower alkane is isopentane. Polyurethane foam material according to any one of claims 1 to 3, characterized in that its pores additionally contain gases selected from the group consisting of a higher amount of nitrogen than the amount of nitrogen in the air, inert gases and mixtures of such gases. 5. The polyurethane foam material according to claim 4, characterized in that the pores of this foam material contain an inert gas, argon. 6. The polyurethane foam material of any one of claims 1 to 5, wherein the foam material comprises a flame extinguisher selected from the group consisting of liquid flame retardants, solid flame retardants and mixtures of such liquid and solid flame retardants. 7. The polyurethane foam material of claim 6, wherein said polyurethane material comprises a flame extinguisher selected from the group consisting of phosphorus containing flame retardants, boron containing flame retardants, and a mixture of several such flame retardants. 8. The polyurethane foam material of claim 6 or 7, wherein the polyurethane material comprises a flame retardant or flame retardant in an amount of from 5 to 35% by weight based on the total weight of the final foam material. 9. The polyurethane foam material of claim 8, wherein the polyurethane material comprises a flame retardant or flame retardant in an amount of from 10 to 20 parts by weight based on the total weight of the final foam material. The polyurethane foam material according to claim 10, wherein the polyurethane material is present as a solid flame retardant. one of 6-9 in that the ammonium salt 11. The polyurethane foam material according to one of claims 6 to 9, characterized in that said polyurethane material comprises a liquid flame retardant selected from the group consisting of lower alkane esters with lower alkane phosphonates, wherein each lower alkanol and lower alkane has from 1 to 4 carbon atoms, as well as mixtures of several such flame retardants. 12. The polyurethane foam material of claim 11, wherein the lower alkane phosphonate contains from 10 to 20 parts by weight of urea based on the total weight of the lower alkane phosphonate. 13. The polyurethane foam according to claim 11 or 12, wherein the lower alkanephosphonate comprises urea to saturation. 14. A process for the production of polyurethane foam material according to one of claims 1 to 13, characterized in that the foam employs a non-halogenated organic liquid product selected from the group consisting of: lower alkanes with 3 to 6 carbon atoms and a mixture of such lower alkanes; the boiling point of said lower alkanes or mixtures of such lower alkanes at normal pressure is -10 to + 70 ° C; the foam is mixed and evenly distributed in a mixture consisting of: the initial alcoholic component and the initial isocyanate component of the final polyurethane foam in the normal ratio of alcoholic and isocyanate starting components, the mixture further comprising only conventional additives such as flame retardants, catalysts and pore stabilizers in the usual amounts, or the final alcoholic component of the final polyurethane foam material and the other conventional additives mentioned above, by adding to this evenly distributed mixture an initial isocyanate component having a ratio of the initial alcoholic component to the polyurethane foam, followed by polymerization of the polyurethane starting components under standard conditions, partially, at normal temperature and the resulting polyurethane foam. time. 15. A process according to claim 14, wherein the polymerization is carried out at a pressure slightly higher or slightly lower than normal, depending on the boiling point of the liquid foam used. 16. A process according to any one of claims 14 to 15, wherein the polyurethane foam material thus obtained is stored for 2 days to several months at room temperature or slightly higher and at normal or slightly lower pressure. 17. A process according to any one of claims 14 to 16, wherein the effervescent is emulsified in the initial alcoholic component by the addition of other conventional additives and the subsequent addition of the initial isocyanate component to this emulsion. 18. The process of claim 17, wherein emulsifying the liquid foam in the alcoholic starting component with the addition of other conventional additives is carried out continuously in a suitable mixing device, and the isocyanate component is subsequently incorporated into the resulting emulsion. 19. A process according to claim 17 or 18, wherein the effervescent is emulsified in the initial alcoholic component with the addition of other conventional additives, and only one or more emulsifiers are subsequently added. 20. The method of claim 19, wherein the amount of emulsifier or emulsifier added is up to 10% by weight based on the weight of the initial alcoholic component of the polyurethane foam material being produced. 21. A process according to claim 19 or claim 20 wherein the emulsifier or emulsifiers are fatty acid derivatives. 22. A process according to any one of claims 14 to 16, wherein the starting alcoholic component, the starting isocyanate component, the foaming agent and other common additives are mixed in the mixing head and the resulting mixture is polymerized by foam production in known manner. 23. A process according to any one of claims 14 to 22, wherein either the effervescent used or the initial mixture of the alcoholic component and the liquid effervescent is saturated with a gas selected from the group consisting of nitrogen, inert gas, a mixture of nitrogen and inert gas, and mixture of inert gases. 24. The process according to one of claims 14 to 23, characterized in that the catalyst used in the polymerization reaction is selected from the group consisting of known base catalysts for the polymerization of polyurethanes and known alkali catalysts for such reaction.