MXPA01006112A - Polyurethane based foam containing exfoliating graphite and the process for the preparation thereof - Google Patents

Abstract

The present invention relates to a process for the production of rigid polyurethane foams containing exfoliating graphite. In a preferred embodiment the foams of the present invention pass severe flame retardant tests such as the M1 burning test. Foams which pass the M1 burning test are produced by reacting a polyisocyanate, a polyol, a halogenated polyol, in the presence of a blowing agent, a catalyst, exfoliating graphite and additional flame retardants selected from phosphonate esters, phosphate esters, halogenated phosphate ester or a combination thereof.

Description

POLYURETHANE BASED FOAM CONTAINING EXFOLIATING GRAPHITE AND THE PROCESS FOR THE PREPARATION OF THE SAME This invention relates to rigid foam compositions and methods for the preparation of such compositions. More particularly, the present invention relates to a combination of ignition retardants to produce a rigid foam having improved flame retardancy properties. Legislation has been enacted in several countries that sets standards for flame retardancy of materials used in building construction. For example, polyurethane foams for the construction of buildings that meet the French Standard NF P 92-501, class M1 (test M1) in France and the German Standard DIN-4102 Teil 1, Mai 1 981, baustoffklasse B1 in Germany ( test B1). To provide the required level of retardation to a foam, a number of procedures have been used. One method for providing flame retardancy in rigid foams is to include melamine in relatively large amounts. U.S. Patent 4,221,875 describes rigid polyurethane foams that include melamine powder in an amount of between 20 and 100 parts per hundred parts of the polyhydroxyl compound. European Patent Publication 0239891 discloses rigid polyurethanes containing an alkylene oxide adduct of toluene diamine or diaminodiphenylmethane with an organic polyisocyanate wherein the melamine is incorporated as the sole gum retarding compound in an amount of at least 5 percent. by weight of the total composition. In the area of flexible foam, extendable graphite (exfoliating) is reported as providing the retardant properties of ignition to the foam. For example, the US Patents. 4,698,369 and 5,023,280 describe the use of graphite in flexible polyurethanes. In flexible foams, graphite is also used in combination with other ignition retardants. The U.S. Patent 5,192,81 1 describes the use of graphite together with melamine and it is reported that the combination of the ignition retardants reduces the subsequent and latent incandescence of the foam. The U.S. Patent 5, 173, 515 discloses the use of graphite in the fire retardant element that can be added to foams wherein the fire retardant element comprises graphite, one or more phospholium-containing matches, and amine salts. Despite the abundance of the processes described to obtain flame retardant foams, it continues to be a need to improve the flame retardant properties of the foams. Accordingly, it is an object of the present invention to provide a process for preparing a rigid flame retardant and / or panel foam, which offers improved performance in rigorous flame tests such as tests M1 and B1. In one aspect, the present invention is a process for the production of a rigid polyurethane foam comprising reacting (1) a polyisocyanate, (2) a polyol, and (3) a halogenated reactive compound, in the presence of (4) a blowing agent, (5) a catalyst, (6) exfoliating graphite, and (7) an ignition retardant selected from phosphonate esters, phosphate esters, halogenated phosphate esters or a combination thereof. In another aspect, the invention relates to a flame retardant polyurethane foam-forming composition comprising a polyisocyanate, a polyol, a halogenated polyol, exfoliating graphite and additional ignition retardants selected from phosphonate esters, phosphate esters, esters of halogenated phosphate or a combination thereof. In another aspect, the invention further provides a process for the production of a rigid closed cell polyurethane foam comprising reacting (1) a polyisocyanate, (2) a polyol mixture having an average molecular weight of from 200 to 1000 and a Average functionality from 2 to 5 in the presence of (3) a blowing agent, (4) a catalyst and (5) an ignition retardant comprising from 1 to 30 parts by weight, based on component (2), of exfoliating graphite. It has unexpectedly been found that the ignition retardant foams produced by the recent process are capable of passing the aforementioned M1 and B1 tests, as well as a number of other rigorous tests such as the A1 test for Italy. The flame retardant properties of the foams produced by the present process are the result of a unique combination of flame retarding agents which act synergistically to give improved flame retardancy. This is particularly surprising in that a small amount of exfoliating graphite added to a polyurethane foam, containing as ignition retardants, a halogenated reactive polyol and a phosphate ester, phosphonate esters, halogenated phosphate esters or a combination thereof, produces a foam capable of passing the rigorous M1 test. This improvement in fire retardancy is obtained without an opposite effect on the foam properties. As indicated, an essential flame retardant component used in the present invention is exfoliating graphite. Exfoliating graphite is graphite that contains one or more exfoliating agents in such a way that considerable expansion occurs on exposure to heat. The exfoliating graphite is prepared by methods known in the art and generally the graphite is first modified with oxidants, such as nitrates, chromates, peroxides, or by electrolysis to open the crystalline layer and then the nitrates and sulfates are intercalated into the graphite. Based on the combination of the ignition retardants described herein, it is possible to use low levels of graphite in the foam-forming reaction mixture. Exfoliating graphite levels are chosen in such a way that the final foam will pass the M1 test. Generally the amount will be at least 0.5 percent by weight of the final foam. Advantageously, the amount of the graphite used will complete at least 1 weight percent of the final foam. Most preferred are foams containing at least 2 percent by weight graphite. There is no limit on the maximum amount of graphite that can be used, however; due to the particle nature of the graphite and the increase in the viscosity of a graphite-containing polyol, for ease of handling it is preferred that the graphite be used in an amount that completes less than ten percent by weight of the final foam. Preferably, the amount of graphite is less than 9 weight percent of the final foam. More preferably, the graphite is less than 6.5 weight percent of the final foam. Most preferred are foams containing 5 percent or less by weight of graphite. A second ignition retardant used in the present invention is a reactive halogen compound. Such compounds are referred to as reagents as they can become a generally part of the polymer. These reactive compounds generally contain portions of halogen and further contain one or more reactive groups, such as -OH or -COOH, which is capable of reacting with an isocyanate moiety. Such compounds are known in the art and are generally halogenated polyols such as phthalic acid derivatives, bisphenol A, an anhydride or an alcohol. For example, halogenated polyether polyols are described in US Patents. 4,072,638; 4, 069.91 1 and 4, 173,710. Examples of such reactive halogenated compounds include, ester diol / tetrabromophthalic anhydride diester, tetrabromobisphenol A, IXOL B251 (a halogenated polyether polyol available from Solvay SA), tetrabromobisphenol A-bis (ali ether) tetrabromobisphenol A-bis (2) -hydroxyethyl ether); tribromophenylmaleimide, tetrabromophthalate, dibromopentyl glycol, tetrabromodipentaerythritol, tetrabromophthalic anhydride, dibromopropanol, chlordenedic acid and tetrachlorophthalic anhydride. Preferably, the halogen is bromine. The amount of the reactive halogen compound used in the present invention is generally less than 50 percent of the total polyol component of the foam mixture. Preferably, the reactive halogen compound is less than 40 percent of the total polyol component and more preferably 30 weight percent or less of the total polyol component. It is generally known in the art that polyurethane foams can be produced which pass the M1 test when a halogenated polyol is used wherein the halogenated polyol comprises more than 70 percent or more of the polyol present. Since halogenated polyols are generally more expensive than conventional polyoles and are more difficult to handle during processing, the reduction in the amount of halogenated polyol required in the present invention reduces the total cost of the foam components and is easier to process. The additional ignition retardants used in the present invention are selected from phosphonate esters, phosphate esters, halogenated phosphate esters or a combination thereof. The phosphonate esters for use in the present invention can be represented by the formula RP (O) (OR ') (OR ") wherein R, R' and R" are each independently an alkane with 1 to 4 carbon atoms . Preferred members of this group are dimethyl methylphosphonate (DMMP) and diethyl ethylphosphonate (DEEP). The phosphate esters which can be used in the present invention are trialkyl phosphates, such as triethyl phosphate, and tricresyl phosphate. When used, the phosphonate or phosphate ester ignition retardants are present in the final foam at a level of 0. 5 to 10 weight percent of the final foam. Preferably they are from 1 to 8.5 weight percent of the final foam. More preferably, they constitute from 2 to 6.5 weight percent of the final foam. The halogenated phosphate esters associated with fire retardation are known in the art and can be represented by the general formula P (O) (OR, X'n) (OR "X" n) (OR ", X '" n), wherein R ', R "and R"' are each independently an alkane with 1 to 4 carbon atoms, X ', X "and X'" are each independently a halogen and n is an integer of 1 to 3. Examples of halogenated phosphate esters include 2-chloroethanol phosphate (CßH? 2CI2O4P); 1-chloro-2-propanol phosphate [tris (1-chloro-2-propyl) phosphate] (C 9 H 18 Cl 3 O P) (TCPP); 1,3-Dichloro-2-Propanol phosphate (C9H15ClβO P) also called tris (1,3-dichloro-2-propyl) phosphate; tri (2-chloroethyl) phosphate; tri (2,2-dichloroisopropyl) phosphate; Tri (2,3-dibromopropyl) phosphate; tri (1,3-dichloropropyl) phosphate; titanium ester (2-chloroethyl) ethylene diphosphate; bis (2-chloroethyl) 2-chloroethylphosphonate; diphosphates [2-chloroethyl diphosphate]; titanium ester ethylenediphosphate (2-chloroethyl); tris- (2-c! oroethyl) -phosphate, tris- (2-chloropropyl) phosphate, tris- (2,3-dibromopropyl) phosphate, tris (1,3-dichloropropyl) phosphate ester of titanium (2-chloroethyl- ethylene disphosphate and titanium ester (2-chloroethyl) ethylenedioxyethylene diphosphate Chloromoneopentyl chloroalkyl phosphates can also be used in EP 0 735 039 having the formula [(BrCH2) 3C-CH2)] mPO (OCYHCH2CI) 3-m in where Y represents a hydrogen, an alkyl, having 1 to 3 carbon atoms, or chloroalkyl group and m is from 0.95 to 1 .15,. When used as an ignition retardant, the halogenated phosphate ester will comprise at least 1 weight percent of the final foam, preferably at least 2 weight percent of the final foam and more preferably at least 4.5 weight percent of the final foam. the final foam. The halogenated phosphate ester generally does not exceed 9 percent by weight of the final foam, preferably 8 percent or less of the final foam and more preferably less than 6.5 percent by weight of the foam. In a preferred embodiment of the present invention, the ignition retardants used to produce the rigid foams of the present invention include the use of exfoliating graphite, a halogenated reactive polyol and a combination of a phosphonate ester or phosphate ester and phosphate ester. halogenated The polyisocyanates, polyols, catalyst and blowing agent for producing the rigid foams of the present invention are those which are well known and commonly used in the art. Polyisocyanates useful in the manufacture of polyurethanes include aliphatic and cycloaliphatic and preferably aromatic polyisocyanates or combinations thereof, advantageously having an average of from 2 to 3.5, and preferably from 2.4 to 3.2 isocyanate groups per molecule. A crude polyisocyanate can also be used in the practice of this invention, such as the crude toluene diisocyanate obtained by the phosgenation of a mixture of diamine toluene or the crude diphenylmethane diisocyanate obtained by the phosgenation of crude methylene diphenylamine. Preferred polyisocyanates are aromatic polyisocyanates such as those described in the U.S. Patent. 3,215,652. Especially preferred are methylene bridge polyphenyl polyisocyanates and mixtures thereof with crude diphenylmethane diisocyanate, because of their ability to degrade polyurethane. The amount of polyisocyanate present when the polyurethane foam is prepared is such that it provides 0.6 to 3.0 isocyanate groups per reactive isocyanate atom present in the polyol (s) and any water that may be present. Preferably, the amount of isocyanate is such that it provides from 0.7 to 2 isocyanate groups per reactive isocyanate atom present in the polyol (s) and any water that may be present. More preferably, the amount of isocyanate is from 0.8 to 1.6 isocyanate groups per isocyanate reactive atom present in the polyol (s) and any water that may be present. When the same proportion is expressed as a multiple of 100 this is then called the isocyanate index. Polyols which are useful in the preparation of polyisocyanate-based cellular polymers include those materials having two or more groups containing an active hydrogen atom capable of being subjected to the reaction with an isocyanate. Preferred among such compounds are materials having at least two hydroxyl groups, primary or secondary amine, carboxylic acid, or thiol per molecule. Compounds having at least two hydroxyl groups per molecule are especially preferred because of their desirable reactivity with the polyisocyanates. Typically, polyols suitable for the preparation of rigid polyurethanes include those having an equivalent weight of 30 to 700, preferably 70 to 300, and more preferably 70 to 150. Such polyols also advantageously have at least 2, preferably 3, functionality. , and up to 6, preferably up to 8, active hydrogen atoms per molecule. Representative polyols include polyether polyols, polyester polyols, polyol hydroxy terminated acetal resins, amines, and polyamines. Examples of these and other suitable isocyanate-reactive materials are more fully described in U.S. Patent 4,394,491. Preferred for the preparation of rigid foams, based on performance, availability and cost, is a polyol prepared by adding an alkylene oxide to an initiator having from 2 to 8, preferably 3 to 8, active hydrogen atoms. Exemplary of such polyols include those commercially available under the trademark designation VORANOL including VORANOL 280, VORANOL 360, VORANOL 370, VORANOL 446, VORANOL 490, VORANOL 575, VORANOL 800, all sold by The Dow Chemical Company. The other highly preferred polyols include alkylene oxide derivatives of Mannich condensed liquids, as described, for example, in US Patents. 3,297,597; 4, 1 37.265 and 4.383, 102; and polyethers initiated in aminoalkylpiperazine as described in U.S. 4,704,410 and 4,704.41 1. In a preferred embodiment of this invention, the polyol is a composition comprising a polyether polyol initiated in sugar (such as sucrose) in from 30 to 90 parts per 100 parts by total weight of the polyol composition. In addition to the sugar initiated polyether polyol, the composition may also comprise a polyol initiated in sorbitol, an initiator polyether polyol initiated in amine and a polyether polyol initiated in water, each in from 3 to 35 parts per 100 parts by total weight of the polyol composition. In a highly preferred embodiment of this invention, the polyol composition contains a polyol initiated in sugar from 30 to 90 parts; a polyol initiated in sorbitol from 3 to 35 parts, a polyether polyol initiated in amine from 3 to 35 parts; a polyol initiated in water from 5 to 35 parts; and a halogenated reactive polyol from 20 to 40 parts per 100 parts by total weight of the polyol composition. Due to the ignition retardant properties associated with aromatic initiated potols, in another preferred embodiment the polyol used contains an aromatic initiated polyether polyol in from 20 to 70 parts per 100 parts by total weight of the polyol compositions. In addition to the polyols described above, the composition may also contain an amine initiated polyether polyol in from 5 to 35 parts per 100 parts by total weight of the composition; or alternatively an aromatic polyester polyol, liquid at room temperature, in from 5 to 35 parts per 100 parts by total weight of the composition. Advantageously, the aromatic initiated polyether polyol is an alkylene oxide adduct of a phenoxy / formaldehyde resin, often referred to as a "novolac" polyol, as described in US Patents 3,470,118 and 4,046,721, or an adduct of alkylene oxide of phenol / formaldehyde / alkanolamine resin, often referred to as a "Mannich" polyol as described in US Pat. 4,883,826; 4,939,182; and 5, 120,815. When a rigid foam is prepared, a blowing agent is presented. The blowing agent is present in an amount that provides the foam with the desired total density. Typically, a density of 25 to 60, preferably from 30 to 55, and more preferably from 35 to 50 kg / m 3 is desired. Generally, as the rigid foams of this invention are predominantly closed cell, it is preferred that a halocarbon blowing agent constitutes the main proportion of the blowing agent due to the additional thermal insulation properties such as the blowing agents provided. Such blowing agents may be fully or partially halogenated aliphatic hydrocarbons and include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbons include methyl fluoride, perfluoromethane, ethyl fluoride, 1,1-difluoroethane, 1,1-trifluoroethane (HFC-143a), 1,1,1-tetrafluoroethane (HFC-134a) , pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane. Chlorocarbons and partially halogenated chlorofluorocarbons for use in this invention include methyl chloride, methylene chloride, ethyl chloride, 1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (FCFC-141 b), 1 - chlorine-1, 1, -difluoroethane (HCFC-142b), 1,1-dichloro-2,2,2-trifluoroethane (HCHC-1 23) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-) 124). Fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-1) dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-13), 1, 1 -trif luoroethane, pentaf luoroethane, dichlorotetrafluoroethane (CFC-14), chlorheptafluoropropane, and dichlorohexafluoropropane. Halocarbon blowing agents can be used in conjunction with low boiling hydrocarbons such as butane, pentane (including the isomers thereof), hexane, or cyclohexane or with water. When the water is presented as an additional blowing agent, it is generally present in an amount from 0.5 to 10, preferably from 0.8 to 6 and more preferably from 1 to 4 and more preferably from 1 to 3 parts by total weight of the composition of total polyol. The water acts as a blowing agent as the water reacts with the isocyanate that leads to the production of carbon dioxide. In addition to the preceding critical components, it is often desired to employ certain other ingredients in the preparation of cellular polymers. Among these additional ingredients are catalysts, surfactants, preservatives, colorants, antioxidants, reinforcing agents, stabilizers, and fillers. In the manufacture of the polyurethane foam, it is generally highly preferred to employ a minor amount of a surfactant which stabilizes the foaming reaction mixture until it solidifies. Such surfactants advantageously comprise a liquid or solid organosilicon surfactant. Others, less preferred surfactants include polyethylene glycol ethers of long chain alcohols, alkanolamine salts or tertiary amine of long chain alkyl sulfate esters, alkyl sulfonic esters and alkyl arylsulfonic acids. Such surfactants are employed in amounts sufficient to stabilize the foaming reaction mixture against collapse and the formation of large, unequal cells. Typically, 0.2 to 3 parts of the surfactant per 100 parts by weight of polyol are sufficient for this purpose. One or more catalysts for the reaction of the polyol (and water, if present) with the polyisocyanate are advantageously used. Any suitable urethane catalyst can be used, including tertiary amine compounds and organometallic compounds. Exemplary tertiary amine compounds include triethylene diamine, N-methylmorpholine, N, N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, tetramethylethylenediamine, 1-methyl-4-dimethylaminoethylpiperazine, 3-methoxy-N-dimethylpropylamine, N-ethylmorpholine, diethylethanolamine, N-co-morpholine, N , N-dimethyl-N ', N' -di methyl isopropylpropylenediamine, N, N-diethyl-3-diethylaminopropylamine and dimethybenzylzamine. Exemplary organometallic catalysts include organomercury, organolead, organoferric and organotin catalysts, with organotin catalysts being preferred among these. Suitable tin catalysts include tin chloride, tin salts of carboxylic acids such as dibutyltin di-laurate, as well as other organometallic compounds such as those described in the U.S. Patent. 2,846,408. A catalyst for the trimerization of polyisocyanates, which results in a polyisocyanurate, such as an alkali metal alkoxide can also be optionally employed herein. Such catalysts are used in an amount that measurably increases the rate of polyurethane or polyisocyanurate formation. Typical amounts are from 0.001 to 3 parts of catalyst per 100 parts by weight of the total polyol. The rigid polyurethanes according to the present invention are easily prepared according to the procedures standard in the art, which bring together with the foaming conditions the polyisocyanate, the active hydrogen-containing material, the blowing agent and other ingredients of the invention. Foaming, including exfoliating graphite and other ignition retardants at a temperature of 10 ° C to 80 ° C. Any mixing order is acceptable, and preferably the exfoliating graphite is homogenously mixed in the foaming formulation. In a preferred embodiment, the exfoliating graphite is dispersed homogeneously in the polyol component. The dispersion of the exfoliating graphite in the polyol can be added as a concentrate in the polyol composition by a separate line to the mixing head. In general, the rigid foams are produced by continuous or discontinuous processes, including what is contemplated as the discontinuous panel process (DCPP) and the double-sided laminates (DBL), with the foaming reaction and carrying out the subsequent solidification in molds or in transporters. When the foams are used in laminates, the coating can be flexible, for example coated paper or aluminum foil, or it can be made with a rigid material such as partition plate, polyester coating or steel coating. Other processes to prepare the construction of foams are known as blocking foams or nebulizers. The rigid foam of the present invention are closed cell foam. By closed cells it is understood that at least 75 percent, preferably 80 percent or more, and more preferably 85 percent or more of the cells are closed. In a preferred embodiment, 90 percent or more of the cells are closed. Due to the closed cell structures, the rigid polyurethanes of the present invention are used for thermal application applications such as coating, coating and applications of nebulizers in situ. The following examples are given to illustrate the invention and should not be construed as limiting in any way. Unless stated otherwise, all parts and percentages are given by weight.

EXAMPLES A description of the raw material used in the examples is as follows: DEEP was diethyl ethyl phosphate ignition retardant additive TCPP was phosphate tris (1-chloro-2-propyl) ignition retardant additive TEGOSTAB B8462 was a surfactant a Silicone base available from Th. Goldschmidt Chemical Corporation. DMCHA was JEFFCAT DMCHA, and N, N-dimethylcyclohexy amine catalyst or available from Huntsman Corporation. Niax DMEE was an amine-based catalyst available from OSI Specialties-Witco. Curithane 52 was an organic salt catalyst available from The Dow Chemical Company. Allocimene was a UV stabilizer (light) available from Les Derives Resiniques & Terpeniques. VORANATE M220 was a polymeric isocyanate available from The Dow Chemical Company. (VORANATE is a Registered Trademark of The Dow Chemical Company). The exfoliating graphite used in the examples was S15-PU120 obtained from Ajay Metachem, India. Polyol A VORANOL * RN490, a polyoxypropylene polyether polyol initiated in sucrose / glycerin having a hydroxyl number of 490 and an equivalent weight of 14, available from The Dow Chemical Company. Polyol B VORANOL RN482, a polyether polyol of polyoxypropylene initiated in sorbitol having a hydroxyl number of 482 and an average equivalent weight of 17, available from The Dow Chemical Company. Polyol C VORANOL RA640, a polyoxypropylene polyol initiated in ethylene diamine having a hydroxyl number of 640 and an average equivalent weight of 88, available from The Dow Chemical Company. Polyol D VORANOL P 1 010, was a polyoxypropylene polyether polyol initiated in water having a hydroxyl number of 1 10 and an average equivalent weight of 51 0, available from The Dow Chemical Company. Saytex RB-79 was a diether diol of tetrabromophthalate anhydride available from Ethyl Corp. * VORANOL is a registered trademark of The Dow Chemical Company. A mixture of base polyol was prepared by mixing the following, given in parts by weight: 30.5 polyol A; 5 of polyol B; 4 of polyol C; 6.7 polyol D; 18 from Saytex RB-79; 1 0 of DEEP; 1 2.6 TCPP; 1.2 of Tegostab B 8462; 2.1 of water; 0.7 of DMCHA; 0.5 of Niax DMEE; 0.6 of Curithane 52 and 0.1 of allocimene. The base polyol, graphite and the blowing agent were added to a beaker followed by gentle agitation. The amount of the blowing agent was adjusted to correct for evaporation and then the isocyanate was added. The mixture was thus stirred for 10 seconds at 3000 rmp before pouring the mixture into a preheated mold at 60 ° C. A steel coating (30 by 40 mm) was presented in the mold in which the mixture was poured. After 45 minutes, the sample was demold. The samples were left overnight and then cut for the test. The characteristic of the foam in the presence of different amounts of graphite is given in Table I.

TABLE I r O To pass the B2 test, a flame of less than 15 cm was required. To pass the M1, a value of less than 2.5 was required. The results show that the aggregation of 4.6 percent by weight of graphite to the total foam composition allowed the foam produced to pass both the B2 and the M1 tests. The results with the low addition of the exfoliating graphite show that the ignition retarding properties of the foam were similar to those obtained when 30 parts by weight of exfoliating graphite were added to the polyol formulation. The formulations containing the added graphite but not containing the halogenated reagent compound or the phosphonate or phosphate ester or a chlorinated phosphate ester produced a foam that failed the M1 test. It was within the skill in the art to practice this invention in numerous modifications and variations in view of the teachings above. Therefore, it was to be understood, that the various embodiments of this invention described herein may have been altered without departing from the spirit and scope of this invention as defined by the appended claims.

Claims (19)

1. CLAIMS 1. A process for the production of rigid polyurethane foam comprising reacting (1) a polyisocyanate, (2) a polyol, and (3) a halogenated reactive compound, in the presence of (4) a blowing agent, (5) a catalyst, (6) exfoliating graphite, and (7) an additional ignition retardant selected from phosphonate esters, phosphate esters, halogenated phosphate esters or a combination thereof.
2. 2. The process according to claim 1, characterized in that the foam is a closed cell rigid polyurethane foam.
3. 3. The process according to claim 2, characterized in that the halogenated reactive compound is a halogenated polyol and is less than 50 percent by weight, preferably less than 30 percent by weight, of the total polyol.
4. 4. The process according to any of the preceding claims, characterized in that the polyol (2) is a polyether polyol.
5. The process according to any of claims 1 to 3, characterized in that the polyol (2) is a polyester polyol.
6. 6. The process according to claim 4 or 5, characterized in that the polyol is an aromatic polyol.
7. 7. The process according to claim 6, characterized in that the polyol has a molecular weight of 400 to 2000 and a functionality of 2 to 8.
8. The process according to claim 1, characterized in that the additional ignition retardants (7) are presented in a amount to comprise from 1 to 20 weight percent of the final foam.
9. The process according to claim 8, characterized in that the additional ignition retardants contain at least one phosphonate ester and at least one halogenated phosphate ester.
10. The process according to claim 9, characterized in that the phosphonate ester or halogenated phosphate ester each is present in an amount comprising from 0.5 to 10 weight percent of the final foam. eleven .
11. The process according to claim 10, characterized in that the phosphonate ester is present in an amount comprising from 1 to 8.5 weight percent of the final foam and the halogenated phosphate ester is present in an amount ranging from 2 to 8. percent by weight of the final foam.
12. The process according to claim 1, characterized in that the graphite is present in an amount comprising at least 0.5 percent by weight of the final foam.
13. 13. An ignition retardant polyurethane foam-forming composition comprising a polyisocyanate, a polyol, a halogenated polyol, exfoliating graphite, and additional gum retarders selected from phosphonate esters, phosphate esters, halogenated phosphate esters or a combination thereof.
14. The composition according to claim 13, characterized in that the halogenated polyol comprises less than 50 percent of the total polyol present.
15. 15. The composition according to claim 13 or 14, characterized in that the graphite comprises at least 2 weight percent of the composition.
16. 16. The composition according to claim 15, characterized in that the composition contains from 2 to 10 weight percent of a phosphonate ester and from 2 to 10 weight percent of a halogenated phosphate ester.
17. 17. A rigid polyurethane foam formed of the composition according to claim 16.
18. 18. The rigid polyurethane foam formed by the process of any of claims 1 to 12.
19. 19. A process for the production of a rigid polyurethane foam of closed cell comprising reacting (1) a polyisocyanate, (2) a polyol of mixture having an average molecular weight of from 200 to 1000 and an average functionality of 2 to 5 in the presence of (3) a blowing agent, (4) a catalyst and (5) an ignition retardant comprising from 1 to 30 parts by weight, based on component (2), or exfoliating graphite. The process according to claim 19, characterized in that the polyol is a polyether polyol, a polyester polyol or a combination thereof.