Expanding agents containing liquid carbon dioxide

The invention relates to blowing agents containing liquid carbon dioxide, as well as their use in methods of producing foamed plastics.

The invention also relates to blowing agent compositions which are suitable for the production of one-component or multi-component polyurethane foams from pressurized containers.

The use of fluorochlorocarbons (FCKWs) as blowing agents in the production of foamed plastics has now become undesirable for environmental reasons. Hitherto also gaseous substances, e.g. carbon dioxide, have also been proposed as substitute materials. However, carbon dioxide as a physical gaseous blowing agent has the disadvantage of being difficult to dose under the production conditions of foamed plastics due to its relatively low critical temperature. Moreover, the use of carbon dioxide according to the methods known hitherto generally leads to open-pored foams with often unsatisfactory thermal insulation properties. So far, too, there have been considerable difficulties in the production of predominantly closed pore foamed plastics when using carbon dioxide as the sole blowing agent or as one of the blowing agents in admixture with other physical blowing agents.

One-component or multi-component polyurethane foams, which are fed from a pressurized container, e.g. from a spray nozzle, are mainly used to apply foam to hollow areas or between walls in building or automotive construction. In the case of the so-called of a single-component polyurethane foam (hereinafter referred to as 1K-PUR foam), a pre-blend of polyol together with an excess of diisocyanate and / or polyisocyanate, in the presence of a catalyst and possibly other auxiliaries and additives, is reacted in a pressurized container to form a prepolymer containing isocyanate groups. By actuating the spray valve in the pressurized container, the prepolymer is pressed through the blowing agent from the dispenser, whereby the prepolymer spontaneously foams. Reaction of the isocyanate groups still present in the air with the moisture in the air produces a hard foam with mostly closed pores.

In the case of two-component polyurethane foam (hereinafter referred to as 2K-PUR foam), a component containing additional hydroxyl groups, e.g. polyol, is needed to cure the prepolymer foam, which is only added immediately before the production of the foam. This polyol is usually contained in a pressurized container in a filling area separate from the rest of the components and is added by actuating the spray valve only immediately before the prepolymer component exits the pressurized container.

Most PUR foam prepolymers used from pressurized containers have a very high viscosity and therefore the blowing agents used should have good solvent properties so that they can easily foam the ingredients from the container

182 691 pressure. The use of fluorochlorocarbons (FCKW) as blowing agents for this type of application is currently undesirable for environmental reasons. Many of the replacement materials proposed so far also have technological drawbacks, such as for example providing unsatisfactory thermal insulation properties or having a too low evaporation rate.

International Patent Application WO 91/12287 discloses that liquid CO2 can be used with other blowing agents, e.g. with water or with higher boiling solvents. In this way, controlled initial or secondary expansion of the foam can be caused. In the composition used, CO2 is the main component of the blowing agent composition (more than 50%), and further components are present in a small amount in relation to the total composition.

Japanese Patent Application JP-A No. 1/254 742 discloses that polyethylene polymers can be expanded with a mixture of CO2 with a volatile organic blowing agent.

International patent application WO 91/08243 relates to the production of open-pored polyurethane foams.

Preferably liquid CO2 is used as blowing agent, which may additionally contain small amounts of water or other blowing agents, the amount of CO2 being at least 75%.

The abstract of JP-A-52117957 discusses the blowing agent. However, this publication does not indicate the amount of CO2 used in the blowing agent, nor does it provide any information on what form the blowing agent is used in and whether it can be used in liquid form at all. The disadvantage of the methods known from the prior art is, inter alia, the fact that pure CO2, which is used in large amounts, is very difficult to dose due to its relatively low critical temperature and creates irreplaceable pressure when used in pressurized containers.

The object of the invention was to develop new methods of producing foamed plastics, as well as methods of producing PUR foams from pressurized containers, which do not have the disadvantages of the prior art methods.

Another object of the present invention was to develop novel blowing agent compositions for these methods.

It has now surprisingly been found that compositions which, in addition to at least one other liquid component, contain carbon dioxide in a liquid form, are suitable as blowing agent compositions in foam plastics manufacturing processes. Blowing agent compositions that contain liquid carbon dioxide are also suitable for making PUR foams from pressurized containers.

The invention relates to blowing agent compositions which contain from 0.5 to 50% by weight of liquid CO2.

Preferred blowing agent compositions contain from 5 to 50% by weight, more preferably from 10 to 50% by weight of liquid CO2.

In addition to liquid CO2, they contain at least one other liquid component or a component liquefied under pressure. This other liquid component or the other liquid components preferably make up the remainder of up to 100% by weight of the blowing agent composition. The one or more other liquid components may be, for example, liquid or pressurized physical blowing agents and / or liquid flame retardants from the group of phosphate esters or esters of phosphonic acids. In addition, they may contain still other known additives and adjuvants, such as stabilizers or plasticizers.

Another object of the invention is a process for producing foamed plastics using blowing agents, which uses a liquid blowing agent composition containing 0.5 to 50 wt.%, Preferably 5 to 50 wt.%, More preferably 10 to 50 wt.%, And most preferably from 10 to 20% by weight of liquefied carbon dioxide.

Liquefied carbon dioxide according to the present invention can be obtained by any known method for liquefying gases, preferably by pressurized condensation.

182 691

Carbon dioxide is at room temperature and normal pressure (1.01325 · 10⁵ Pa) with a colorless gas which can be condensed into a colorless mobile liquid at a pressure of 56.5 atm (= 5.72486 · 10 Pa) at a temperature of 20 ° C. Methods for liquefying carbon dioxide under pressure are generally known.

One embodiment of the present invention is the production of foamed plastics, e.g. by casting or extrusion. Another embodiment of the present invention, which will be presented below, is particularly relevant for the production of single or two-component polyurethane foams from pressurized containers (PUR = polyurethane). The first-mentioned embodiment of the present invention will first be presented below.

As other liquid components, apart from carbon dioxide liquefied under pressure, any commonly used liquid physical post-forming agents can be used in the production of foamed plastics, namely volatile organic compounds such as ethers, e.g. diethyl ether, ketones such as acetone, hydrocarbons, such as pentane, hexane, heptane, gasoline blends, halogenated hydrocarbons or halogen containing ethers. In addition to liquefied carbon dioxide, pressurized liquefied gases, e.g. propane or butane, can also be used. Water can also be used as the liquid blowing agent.

For the production of foamed plastics, a blowing agent composition is preferably used which comprises or consists of 10 to 20 parts by weight of liquefied carbon dioxide and from 30 to 90 parts by weight of at least one liquid or pressurized physical blowing agent from the group of alcohols containing from 1 to 5 carbon atoms, aliphatic hydrocarbons containing from 2 to 12 carbon atoms, cyclic hydrocarbons containing from 3 to 12 carbon atoms, halogen-containing hydrocarbons containing 1 to 5 carbon atoms or halogen-containing ethers containing a total of 2 to 6 carbon atoms. Ethanol and isopropanol are particularly preferred as alcohols. Examples of aliphatic hydrocarbons are: pentane, hexane, heptane, and also gasoline fractions, especially light gasolines with a boiling point in the range from 15 to 80 ° C. Moreover, low-boiling fractions liquefied under pressure, such as, for example, propane and / or butane, can be used as the liquid components of the blowing agents. As examples of cyclic hydrocarbons, mention may be made of cycloaliphatic hydrocarbons, preferably cyclopropane, cyclopentane and cyclohexane. Halogen-containing hydrocarbons are considered to be hydrogen-containing fluorochlorocarbons or fluoro-hydrocarbons. The fluorochlorocarbons can be used, for example, chlorodifluoromethane (R22), trifluoromethane (R23), 1,1-dichloro-1-fluoroethane (R141b), 1-chloro-1,1-difluoroethane (R142b) or 1,3-dichloro-1,1,2,2,3, 3-hexafluoropropane (R216a). Examples of fluorocarbons are pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1,2-trifluoroethane (R143), 1,1-difluoroethane (R152a) , 1,1,1,3,3-pentafluoropropane (R245fa), octafluoropropane (R218) and also 1,1,1,3,3-pentafluorobutane (R365mfc). Halogen-containing ethers are considered to be hydrogen-containing fluorochloroethers or fluoroethers such as, for example, difluoromethoxy-2,2,2-trifluoroethane (E245).

Preferably, a blowing agent composition is used which comprises from 10 to 20 parts by weight of liquefied carbon dioxide and from 30 to 90 parts by weight of at least one halogen-containing hydrocarbon or an aliphatic hydrocarbon or halogen-containing ether, or consists of said mixture.

In the process according to the invention, it is particularly preferred to use a blowing agent composition which comprises or consists of from 10 to 20 parts by weight of liquefied carbon dioxide and from 30 to 90 parts by weight of 1,1-difluoroethane (R152a) and / or from 30 to 90 parts by weight. by weight 1,1-dichloro-1-fluoroethane (R141b). Other blowing agent compositions which are particularly advantageously used in the process according to the invention are blowing agent compositions which contain from 10 to 20 parts by weight of liquefied carbon dioxide and from 80 to 90 parts by weight of 1,1-dichloro-1-fluoroethane (R141b), and also optionally additionally from 1 to 3 parts by weight of water or consist of said mixture. Also particularly preferred is a blowing agent composition which comprises 10 to 20 parts by weight of liquefied carbon dioxide, 50 to 70 parts by weight.

182 691 parts by weight of 1,1-difluoroethane (R152a) and 20 to 35 parts by weight of ethanol or consist of such a mixture. Of the halogen-containing ether blowing agent compositions, those containing 10 to 20 parts by weight of liquefied carbon dioxide and 80 to 90 parts by weight of difluoromethoxy-2,2,2-trifluoroethane (E245) or consisting of such mixtures are particularly preferred. . Among the aliphatic hydrocarbons, n-pentane is especially preferred. The composition according to the invention containing aliphatic hydrocarbons should preferably contain from 10 to 20 parts by weight of liquefied carbon dioxide and from 80 to 90 parts by weight of n-pentane, and optionally additionally from 1 to 3 parts by weight of water, or consist of such a mixture.

With all these blowing agent compositions, the use of other blowing agents can be reduced by the use of liquid CO2. CO2 is physiologically harmless and environmentally friendly.

The inventive method for producing foamed plastics can be carried out as a casting method or an extrusion process. In the extrusion process, mixtures suitable for the production of foamed plastics are extruded directly in the form of foam plates, films, moldings, profiles or particles. It is particularly advantageous according to the invention to produce foamed thermoplastics, in particular polyethylene, polypropylene or polystyrene foams. The process according to the invention is carried out by introducing a blowing agent composition consisting of liquefied carbon dioxide and another liquid physical blowing agent into a melt of starting products suitable for the production of foamed plastics, and the polymerization of the starting products into a foam to be produced. plastic, possibly with a slight overpressure or underpressure during the foaming process. In the process according to the invention, known processing devices, e.g. extrusion devices, can be used. In the process according to the invention, it is particularly surprising that carbon dioxide can be used in an extruder, in liquefied form, also at elevated temperatures, for the purpose of foaming molten thermoplastic polymers. In contrast to the processes according to the prior art, it is possible to easily dose the carbon dioxide. The process according to the invention can, using carbon dioxide, produce foams with mostly closed pores and a very uniform, fine-porous structure. Moreover, the foamed plastics obtained by the method of the present invention are distinguished by very good thermal insulation properties.

The process according to the invention for producing foamed plastics can be carried out by using a blowing agent composition pre-prepared in a pressurized container, which has been produced in a pressurized container in the desired parts by weight of liquid or pressurized physical blowing agents and then forced into it. carbon dioxide liquefied in the desired amount by a known method. However, it is also possible to proceed with the process according to the invention so that the blowing agent composition used is not produced until just prior to foaming of the polymers or polymerizable components to be foamed. The carbon dioxide, condensed in appropriate amounts in a pressure vessel outside of the actual extrusion equipment, is then introduced into the other liquid component of the blowing agent composition under a pressure at which the carbon dioxide is liquid, and the components are largely mixed. The thus obtained homogeneous mixture of liquefied carbon dioxide with the liquid component of the blowing agent is then introduced into the extruding device through the inlet for the liquid blowing agents.

The process according to the invention is suitable for the production of both hard and soft open-pored or closed-pored foams. The method is particularly suitable for the production of polyurethane foams. Known PUR processing equipment can be used for this purpose, for example high-pressure or low-pressure mixing devices equipped with static mixers known from the state of the art.

182 691

In one variant of the process for the production of polyurethane foams, the blowing agents according to the invention, in addition to one or more liquid and / or pressurized physical blowing agents, may contain, as an additional component, other liquid additives, e.g. flame retardants. Commonly used flame retardants are, for example, phosphate esters or phosphonates. Particularly suitable are the corresponding phosphate esters, or optionally phosphono esters, which contain three lower alkyl groups, optionally three lower alkyl groups substituted with one or more halogen atoms. Lower alkyl is preferably groups containing from 1 to 4 carbon atoms. Examples include: tris (chloroisopropyl) phosphate, tris (chloroethyl) phosphate, tris (chloroethyl) phosphate, trichloroethyl phosphate, trichloropropyl phosphate, tris (chloropropyl) phosphate, triethyl phosphate, dimethylethyl phosphate, tris (dichloroisopropethyl) or dimethyl phosphate dimethyl phosphate.

If the process according to the invention is used for the production of polyurethane foams, all raw materials normally used for the production of foams, such as, for example, aliphatic, cycloaliphatic or aromatic diisocyanates or polyisocyanates, can be used. As examples of raw materials used in the production of foams, mention may be made of 2,4- and 2,6-tolylene diisocyanate, methane diphenyl diisocyanate, polymethylene polyphenyl isocyanate and mixtures thereof. It is also possible to use polyisocyanates containing carbodiimide, urethane, alphanate, isocyanurate, urea or biuret groups, which are also called "modified polyisocyanates" or "isocyanate prepolymers". In the production of polyurethane foams, it is usual to react polyisocyanates with compounds which contain at least two hydrogen atoms capable of reacting with isocyanate groups, e.g. with compounds containing hydroxyl groups, based on polyesters, polyethers and amines, and also with compounds containing amino and / or carboxyl groups and / or thiol groups. In addition, any catalysts customary in the preparation of polyurethane foams can be used, such as, for example, tertiary amines and / or organometallic compounds, such as, for example, tin salts of carboxylic acids.

If the process according to the invention is used for the production of polystyrene or polyethylene foams, any raw materials normally used for the production of such foams can be used.

Any known additives and auxiliaries, for example nucleating agents, pore size regulating substances, flame retardants, antistatic agents, stabilizers, plasticizers, crosslinkers, fillers or dyes, can be added to the polymers and / or polymerizable components in a known manner.

Another embodiment of the present invention discussed below relates to the production of single or multi-component polyurethane foams from pressurized containers. Also in this case, a blowing agent composition is used which contains from 0.5 to 50% by weight of liquefied CO₂.

A blowing agent composition is considered to be the liquid portion of the blowing agent composition contained in a pressurized container, including the gas phase contained in the pressurized container.

In this embodiment of the invention, the blowing agent composition comprises, in addition to liquid CO₂at least one other liquid component. As another liquid component it may contain a liquid or a pressurized physical blowing agent. Halogen-containing blowing agents are suitable for this, while halogen-free blowing agents are usually environmentally friendly and are therefore preferred. In a particularly preferred embodiment of the present invention, liquid CO₂ it is included as the sole blowing agent, and the other liquid component is a liquid flame retardant from the group of phosphoric acid esters or phosphonic acid esters.

As other liquid components, apart from carbon dioxide condensed under pressure, any commonly used liquid physical blowing agents can be used in the production of foamed plastics, namely volatile organic compounds such as ethers, acetone, hydrocarbons such as pentane, hexane, heptane, mixtures gasoline, halogenated hydrocarbons or halogen containing ethers. In addition to liquefied carbon dioxide, pressurized liquefied gases, e.g. propane or butane.

182 691

The blowing agent compositions according to the invention preferably contain more than 5% by weight, in particular 5 to 50% by weight, e.g. 5 or 10 to 30% by weight, of liquefied carbon dioxide.

Preferred blowing agent compositions are those which contain or consist of 10 to 50 parts by weight of liquefied carbon dioxide and from 30 to 90 parts by weight of at least one liquid or pressurized blowing agent from the group of ethers having a total of 2 to 4 carbon atoms, ketones containing from 3 to 5 carbon atoms, aliphatic hydrocarbons containing from 2 to 12 carbon atoms, halogen-containing hydrocarbons containing 1 to 5 carbon atoms or halogen-containing ethers containing a total of 2 to 6 carbon atoms. Examples of aliphatic hydrocarbons are pentane, hexane, heptane, and also gasoline fractions, especially light gasolines with a boiling point in the range from 15 to 80 ° C. Advantageously, low-boiling fractions liquefied under pressure, such as, for example, propane and / or butane, can be used as the liquid components of the blowing agents. As examples of cyclic hydrocarbons, mention may be made of cyclopropane, cyclopentane and cyclohexane. Halogenated hydrocarbons are considered to be hydrogen-containing fluorochlorocarbons or fluorocarbons. As fluorochlorocarbons there can be used, for example, chlorodifluoromethane (R22), 1,1-dichloro-1-fluoroethane (R141b), 1-chloro-1,1-difluoroethane (R142b) or 1,3-dichloro1,1,2,2,3 , 3-hexafluoropropane (R216a). Examples of fluorocarbons are: trifluoromethane (R23), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1,2-trifluoroethane (R143), 1 , 1-difluoroethane (R152a), 1,1,1,3,3-pentafluoropropane (R245fa), octafluoropropane (R218), or 1,1,1,3,3-pentafluorobutane (R365mfc). Halogenated ethers are considered to be hydrogen-containing fluorochloroethers or fluoroethers such as, for example, difluoromethoxy-2,2,2-trifluoroethane (E245). Examples of possible ethers are dimethyl ether or diethyl ether. Among the ketones, acetone is especially preferred.

The blowing agent compositions of the present invention may be free of halogenated blowing agents and may only consist of liquefied carbon dioxide as the only component of the blowing agent. Preference is given to such blends which contain or consist of liquefied carbon dioxide in an amount of 20 to 30 parts by weight and contain butane or a propane / butane mixture in an amount of 50 to 60 parts by weight and / or acetone in an amount of 5 to 15 parts by weight. . As a propane / butane mixture, a conventional mixture can be used, e.g. a mixture with a vapor pressure of approximately 3.7 bar (abs.), I.e. 3/7 × 10⁶ Bye.

Furthermore, compositions which contain or consist of 10 to 50 parts by weight of liquefied carbon dioxide and 10 to 90 parts by weight of halogen-containing hydrocarbon or halogen-containing ether are preferred. Especially preferred are blowing agent compositions which contain or consist of 10 to 30 parts by weight of liquefied carbon dioxide and from 10 to 90 parts by weight of halogenated hydrocarbons: 1,1-difluoroethane (R 152a) and / or 1,1-dichloro-1 -fluoroethane (R141b). Among the compositions according to the invention containing halogen-containing ethers, blowing agent compositions containing or consisting of 15 to 40 parts by weight of liquefied carbon dioxide and 10 to 20 parts by weight of difluoromethoxy-2,2,2-trifluoroethane (E245) are particularly preferred.

In another, particular, preferred variant, the blowing agents according to the invention, in addition to the carbon dioxide liquefied under pressure, may contain, as the liquid component, phosphate esters or phosphonates, used as conventional flame retardants. Particularly well suited for this purpose are phosphate or phosphono esters which contain three alkyl groups containing from 1 to 4 carbon atoms and which are optionally substituted with one or more halogen atoms, such as e.g. tris (chlorisopropyl) phosphate, tris (chloroethyl) phosphate, trichlorethyl phosphate, trichloropropyl phosphate, tris (chloropropyl) phosphate, triethyl phosphate, dimethylethyl phosphate, tris (dichloroisopropyl) phosphate or dimethylmethyl phosphonate. Their contents are preferably from 10 to 50 parts by weight of liquefied carbon dioxide and from 80 to 100 parts by weight of phosphoric ester or phosphonate. Preference is given to using tris (chloropropyl) phosphate. This particularly preferred composition is used

182 691 types of blowing agents do not contain other blowing agents, apart from CO2, and are therefore particularly ecologically advantageous.

The blowing agent compositions according to the invention are suitable for the production of all known PUR foams from pressurized containers, in particular for the foaming of 1K-PUR foams and 2K-PUR foams. The blowing agent compositions according to the invention can also be used to prepare multi-component PUR foams, wherein the foam-forming material is separately filled into a pressurized container containing more than one reactive component. The blowing agent compositions according to the invention can also be used for the production of so-called 1.5 K-PUR foams in which, in contrast to 2K foams, an amount of the polyol component is added to the prepolymer shortly before its exit which is insufficient to react with all isocyanate groups.

The use of blowing agent compositions has proved to be very advantageous for the production of 1K-PUR or 2K-PUR foams.

In addition to the blowing agent composition according to the invention, additional components can be present in the 1 K-PU foam blend to be foamed in known amounts, such as: polyol component, polyisocyanate component, catalyst, and optionally, as an auxiliary, flame retardant.

The polyol component in the 1 K-PUR foam blend can be, for example, glycerin, glycols or polyether polyols obtained as addition products of propylene oxide or ethylene oxide with polyhydric alcohols, water or ethylene diamine; or polyester polyols which were obtained as polycondensation products of polyols with dicarboxylic acids or with their anhydrides; or mixtures thereof. A typical polyol component can be e.g. a mixture consisting of a brominated polyether polyol (e.g. a diol or a triol) with a hydroxyl number of 200 to 350 and a polyether polyol (e.g. a diol) with a hydroxyl number of 110. In addition, modified vegetable oils with a hydroxyl number in the range of 100 to 300 can also be used , e.g. castor oil.

The polyisocyanate component used can be, for example, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, 1,6-hexane diisocyanate, and preferably 4,4'-dimethylmethane diisocyanate, or mixtures thereof.

sticky catalysts in 1 K-PUR foam mixes that can be foamed with the blowing agent composition according to the invention are organic amines, amino alcohols or amino ethers, e.g. 2-diaminomethylethyl ether, 3-dimethylaminopropyl ether, diethanolamine, dimethylcyclohexylamine, ether 2 -dimethylaminoethyl or morpholine compounds such as e.g. 2,2-dimorpholinodiethyl ether, Ν, Ν-dimethylaminoethylmorpholine, N-methylmorpholine. Morpholine compounds are preferred, especially 2,2-dimorpholinodiethyl ether.

As common flame retardants, tris (chloroisopropyl) phosphate, trichloroisopropyl phosphate, tris (chloroethyl) phosphate, tris (chloroethyl) phosphate, tris (chloropropyl) phosphate, tris (chloropropyl) phosphate, trichloropropyl phosphate, dimethyl ethyl phosphate, tris (dichloroisopropyl) phosphate, dimethyl phosphate, dimethyl phosphate, dimethyl phosphate, preferably dimethyl phosphate, can be used as common flame retardants. tris (chloropropyl) phosphate.

Suitable stabilizers are, for example, siloxane copolymers.

The 1K-PUR foam mixture for the production of foam contains, based on the mixture for foam production adopted as 100% by weight, e.g. from 20 to 30% by weight of the polyol component, from 40 to 60% by weight of the polyisocyanate component, from 0.1 to 3% by weight by weight of catalyst, optionally from 10 to 15% by weight of flame retardant, optionally from 1 to 2% by weight of a foam stabilizer, in addition to from 15 to 35% by weight of the blowing agent composition according to the invention. A typical 1K-PU foam blend, which can advantageously be expanded with the blowing agent composition according to the invention, therefore consists, for example, of about 22.5% by weight of a polyol component, e.g. a mixture of a brominated polyether polyol with a hydroxyl number of 200 to 350 with a polyether polyol having a hydroxyl number of 110, in a 1: 1 mixture ratio; about 42.5% by weight of a polyisocyanate component, e.g.

182 691 about 0.5% by weight of a catalyst material, such as, for example, 2,2-dimorpholinodiethyl ether, about 1.5% by weight of a silicone foam stabilizer; about 13% by weight of a flame retardant such as, for example, tris (chloropropyl) phosphate; and from about 20% by weight of the blowing agent composition of the invention. Such a 1K-PUR foam blend can be used to obtain a one-component foam with a uniform fine-porous structure and with a low apparent density, e.g. with an apparent density of about 23 to 25 kg / m3³.

The 1.5K- and 2K-PUR foams differ from the one-component foams in that the polyol component required for curing the foam is located in the pressurized container separately from the prepolymer composition and is added to the prepolymer only immediately before foaming. All of the abovementioned polyol components are suitable as second component. In order to obtain faster curing, the second component may additionally contain a conventional catalyst, e.g. the above-mentioned amine or morpholine compounds, as well as organometallic compounds such as, for example, tin dioctonate, cobalt naphthenate, dibutyltin dilaurate or iron acetonylacetate.

One-component or multi-component PUR foams produced using the blowing agent composition according to the invention have very good thermal insulation properties and are therefore well suited for insulation applications, e.g. in construction and housing. The blowing agent compositions of the present invention are also suitable for the preparation of polyurethane spraying adhesives.

In addition, the invention relates to a method for producing a 1K-PUR or 2K-PUR foam, in which from a pressurized container containing a mixture for the production of PUR foam composed of a polyol component, a prepolymer containing isocyanate groups, a catalyst and possibly other conventional auxiliaries, and also described above the composition of blowing agents, PUR foam is produced as a result of depressurization by means of a valve to atmospheric pressure, excess pressure present in the pressure vessel. Suitable pressurized containers as well as foaming valves are generally known.

In addition, the invention relates to compositions for producing one-component or multi-component PUR foam from pressurized containers, which contain the above-described blowing agent composition.

Another object of the invention is a process for the production of blowing agent compositions for the production of PUR foams from pressurized containers, which uses liquefied carbon dioxide as a component of the blowing agents. In the process according to the invention, a liquid or pressurized component of physical blowing agents is present in a pressurized container in the desired parts by weight, and liquefied carbon dioxide, usually pressurized liquefied, is injected in a known manner in the desired amount. The blowing agent composition prepared according to the invention can then be injected in the desired amount into the pressurized container (aerosol can) which already contains the prepolymer and optionally all other ingredients. The amount of carbon dioxide is controlled solely by means of pressure, within the limits allowed for aerosol cans (10 to 18 bar, i.e. 10⁶ to 1.8 · 10® Pa).

Thus, it is possible to produce pressurized containers containing PUR foam blends that can contain about 20 to 30 g of carbon dioxide per 1 kg can. In prior processes, which always used gaseous carbon dioxide, it was only possible to feed about 3 to 5 g of carbon dioxide per 1 kg can. It is therefore now possible to further advantageously reduce the proportion of flammable liquid or pressurized physical blowing agents during the production of PUR foams from pressurized containers. From a cost standpoint, it is very advantageous to reduce the amount of liquid or pressurized physical blowing agents that have hitherto been used. The monocomponent or multi-component PUR foam produced using the blowing agent composition of the invention has a very uniform, fine-porous structure with mostly closed pores, and also has very good thermal insulation properties. PUR foams produced at

182 As a result of using the blowing agent compositions according to the invention, they are therefore suitable for use as insulation in construction and housing.

The following examples are intended to illustrate the invention in greater detail, but do not limit its scope.

Example I. Preparation of polystyrene foam.

a) Liquefied carbon dioxide / R152a mixture as blowing agent

200 kg of polystyrene (melt index 3.0-110) was mixed with 2 kg of talc as nucleating agent, then this mixture was introduced into a conventional extrusion machine and melted. In the melt zone of the extruder, about 6% by weight of the blowing agents according to the invention, based on polystyrene, were introduced into the molten polystyrene by means of an injection nozzle. The blowing agent composition according to the invention contained 14 parts by weight of liquefied carbon dioxide and 86 parts by weight of R152a. The vapor pressure of the blowing agent composition at 20 ° C was about 14 bar (1.4 × 10⁶ Bye).

In the mixing zone, the molten polystyrene was uniformly mixed with the blowing agent composition of the invention, and the resulting mixture was extruded through a die. The result is a closed-cell foam with an even, fine-porous structure.

According to the invention, both expanded polystyrene foils and expanded polystyrene sheets were produced. The polystyrene foam film produced according to the invention has a density of about 35 kg / m3³and the polystyrene foam sheet produced according to the invention is approximately 33 kg / m 2³.

b) Liquefied carbon dioxide / R152a / ethanol mixture as blowing agent

About 8.5% by weight of the blowing agents according to the invention, based on polystyrene, were introduced into the polystyrene melt in the manner described in Example 1a). The blowing agent composition according to the invention contained 14 parts by weight of liquefied carbon dioxide, 57 parts by weight of R152a and 29 parts by weight of ethanol. The vapor pressure of these blowing agent compositions at 20 ° C was about 15 bar (1.5 · 10⁶ Bye).

The polystyrene foam film produced according to the invention has a density of about 36 kg / m3³and the polystyrene foam sheet produced according to the invention is approximately 34 kg / m 2³.

Example II. Manufacture of polyethylene foam.

a) Mixture of liquefied carbon dioxide / R152a / R141b as blowing agent

200 g of polyethylene (melt index 3.5-150) was extruded under identical conditions as described in Example 1 for polystyrene foam. About 6% by weight of the blowing agent mixture, based on the polyethylene, was introduced. The blowing agent composition according to the invention contained 14 parts by weight of liquefied carbon dioxide, 50 parts by weight of R152a and 36 parts by weight of R141b. A fine-pored polyethylene foam with low shrinkage was obtained. The polyethylene foam pipe produced according to the invention has a density of about 40 kg / m3³.

Example ΠΙ. Production of PUR foam.

One of the starting components for the production of PUR foam was a polyol mixture consisting of 40 parts by weight of polyethylene diamine / propylene oxide (hydroxyl number 480), 60 parts by weight of polyether sorbitol / glycerine / propylene oxide (hydroxyl number 490), 1 part by weight of a stabilizer foams (typ. DC 193 from Dow Corning Corporation) and 1.5 parts by weight of dimethylcyclohexylamine. As the isocyanate component, diphenylmethane diisocyanate was used in an amount greater than 10% by weight than the stoichiometric amount. PUR foams were produced on a low-pressure installation with a capacity of about 8 kg / min, which enables dosing of three components. A static mixer was used as the mixing unit.

a) Liquefied carbon dioxide // R141b / water mixture as blowing agent

The blowing agent composition according to the invention was used in an amount of 30 parts by weight. The blowing agent composition according to the invention consisted of 13.9 parts by weight of liquefied carbon dioxide, 85.1 parts by weight of R141b, and additionally

182 691 with 1 part by weight of water. Using this blowing agent composition, a fine-pored rigid PUR foam with a density of about 24 kg / m3 was obtained.

b) Liquefied carbon dioxide / n-pentane / water mixture as blowing agent

In addition, PUR foam was produced using 18 parts by weight of the blowing agent composition. This blowing agent composition according to the invention consisted of 13.9 parts by weight of liquefied carbon dioxide, 85.1 parts by weight of n-pentane, and additionally 1 part by weight of water. Using this composition of blowing agents, a fine-pored rigid PUR foam was obtained with a density of about 25.4 kg / m³.

c) Liquefied carbon dioxide / E245 mixture as blowing agent

In addition, PUR foam was produced using 35 parts by weight of the blowing agent composition. This blowing agent composition according to the invention consisted of 14 parts by weight of liquefied carbon dioxide and 85 parts by weight of E245. Using this composition of blowing agents, a fine-pored rigid PUR foam was obtained with a density of about 33.5 kg / m³.

Example IV. The mixture of liquefied carbon dioxide / propane / butane / acetone as blowing agent for the production of 1K-PUR foams.

(a) 247 g of polyol premix consisting of:

g of brominated polyether polyol (diol), hydroxyl number of about 240, g of polyether polyol (diol), hydroxyl number of about 110, g of tris (chloropropyl) phosphate, g of silicone foam stabilizer and g of dimorpholinodiethyl ether, put into an aluminum aerosol can with a volume of 1000 cm³. 356 g of 4,4-diphenylmethane diisocyanate were added and the aerosol can was closed with a foam aerosol valve. The blowing agent composition of the present invention was prepared by introducing 28 g of pressurized carbon dioxide into a pressure vessel containing 62 g of pressurized propane / butane and 10 g of acetone while stirring. 99 g of this blowing agent composition according to the invention was then injected by a conventional aerosol delivery device into an aerosol can containing foam ingredients. The aerosol can was shaken for a short time and then left for about 24 h for the formation of the prepolymer. After this time, the 1K-PUR foam blend was ready for use.

The 1K-PUR foam blend was removed from the aerosol can with the blowing agent composition of the invention. PUR foam was obtained with an apparent density of about 23 kg / m3³, with an even, small-cell structure. The shrinkage of the PUR foam after storage for 7 days at a relative air humidity of about 90% averaged about 5% of the length. B) As described in a), the polyol mixture and polyisocyanate were introduced into an aerosol can of the same volume. As the blowing agent composition according to the invention, a composition consisting of 50 g propane / butane, 7.5 g acetone and 20 g liquefied carbon dioxide was used. The production of the blowing agent composition and the filling of the aerosol can was as described under a).

The PUR foam obtained with this blowing agent composition according to the invention had an apparent density of about 25 kg / m3.³.

Example 5: Liquefied carbon dioxide / propane / butane / R141b mixture as blowing agent for the production of 1K-PUR foams.

As described in Example 4, the polyol mixture and polyisocyanate were introduced into a 1000 cm spray can³. As the blowing agent composition according to the invention, a composition consisting of 62 g propane / butane, 10 g R141b and 28 g liquefied carbon dioxide was used. The preparation of the blowing agent composition and the filling of the aerosol can was carried out as described in Example 4.

The PUR foam obtained with this blowing agent composition according to the invention had an apparent density of about 25 kg / m3.³.

Example VI. The mixture of liquefied carbon dioxide / trichloropropyl phosphate / R141b as a blowing agent for the production of 1K-PUR foams.

182 691 17

214 g of polyol mixture and 356 g of polyisocyanate were introduced as described in Example 4 into an aerosol can with a volume of 1000 cm3.³. The composition according to the invention was prepared by introducing 28 g of carbon dioxide condensed under pressure into a pressure vessel containing 100 g of tris (chloropropyl) phosphate and 10 g of R141b while stirring. 99 g of this blowing agent composition according to the invention was then introduced into an aerosol can as described in Example 4.

182 691

Publishing Department of the Polish Patent Office. Circulation of 60 copies

Price PLN 4.00.