RIGID POLYURETHANE FOAMS

Abstract: Process for preparing a rigid polyurethane or urethane-modified polyisocyanurate foam in the absence of a silicone-based surfactant wherein the polyfunctional isocyanate-reactive composition comprises an amine-initiated polyether polyol and optionally a polyether polyol of functionality 2 to 6 and number average molecular weight between 1000 and 10000 and wherein optionally the polyisocyanate composition comprises the reaction product of a stiochiometric excess of an organic polyisocyanate and a substantially fluorinated isocyanate-reactive compound.

Description: DESCRIPTION RIGID POLYURETHANE FOAMS This invention relates to rigid polyurethane or urethane-modified polyisocyanurate foams and to processes for their preparation. Rigid polyurethane and urethane-modified polyisocyanurate foams are in general prepared by reacting the appropriate polyisocyanate and lsocyanate- reactive compound (usually a polyol) in tne presence of a blowing agent. One use of such foams is as a thermal insulation medium in buildings, refrigerators and other domestic appliances Surface-active materials or foam stabilisers are essential ingredients in the manufacture of rigid polyurethane foams They serve to facilitate mixing of the components, to control the s ^ ze of the foam cells and to stabilise the rising foam. Often these surfactants are silicone baseα A major disadvantage of these materials is their cost. Therefore it is αesirable to use formulations for preparing polyurethane foam not containing silicone-based surfactants. WO 95/16721 describes the use of a specifically developed non-silicone polyether surfactant in the preparation of polyurethane foams. It is an object of the present invention to provide rigid polyurethane foams made without using silicone-based surfactants It is a further object of the preser invention to prepare rigid polyurethane foams not containing any silicone-based surfactant using ingredients known in the art for the preparation of polyurethane foams. According to the present invention rigid polyurethane and urethane-modified polyisocyanurate foams are provided, prepared by reacting a polyisocyanate composition with a polyfunctional isocyanate-reactive composition in the presence of a blowing agent and in tne absence of a silicone-based surfactant wherein the polyfunctional isocyanate-reactive composition comprises an amine-initiated polyether polvol known in the art for the production of rigid polyurethane foam. Although prepared in the absence of silicone-based surfactants the foams of the present invention have a fine uniform cell structure. Further the foams of the present invention have a more isotropic structure resulting in a much stronger foam especially m the weakest direction (in general, for free rise foam, perpendicular to the direction of rise) with improved dimensional stability and a lower minimum stable density compared to the foams of the prior art made in the presence of silicone-based surfactants. The amine-initiated polyether polyol for use in the present invention is the reaction product of alkylene oxides, for example ethylene oxide and/or propylene oxide with an amine initiator containing from 2 to 8 active hydrogen atoms per molecule. Suitable amine initiators include ethylene diamine, ethanolamine, N-methyl ethanolamine, N-ethyl ethanolamine, diethanolamine, triethanolamine, triisopropanolamine, ammonia, tolylene diamine, dia inodiphenylmethane and polymethylene polyphenylene polyamines. Aromatic amine mitiatores are preferred, particularly polymethylene polyphenylene polyamines. Co-initiators of another type can be used. The total amount of amine-initiated polyether polyols is at least 20 % by weight based on the total isocyanate-reactive compounds, preferably at least 30 s and most preferably between 40 and 80 *. Advantageously the polyfunctional isocyanate-reactive composition for use in the present invention also comprises a polyether polyol known in the art for the production of flexible polyurethane foams. Such a polyether polyol has an average nominal functionality of 2 to 6, preferably 2 to 4 and number average molecular weight of between 1000 and 10000. The OH value of such a polyether polyol is generally in the range 20 to 80, preferably 26 to 57 mg KOH/g. These polyether polyols are obtained by the polymerisation of a cyclic oxide, such as ethylene oxide and propylene oxide, in the presence of a polyfunctional initiator. Suitable initiators contain a plurality of active hydrogen atoms and include water and polyols, for example ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, cyclohexane dimethanol, resorcinol, bisphenol A, glycerol, trimethylolpropane, 1,2,6- hexanetriol, pentaerythritol, sorbitol and sucrose. Mixtures of initiators and/or cyclic oxides may be used. Especially useful polyether polyols known in the art for the production of flexible polyurethane foams include polyoxypropylene diols and triols and poly(oxyethylene-oxypropylene) diols and triols obtained by the simultaneous or sequential addition of ethylene and propylene oxides to di- or trifunctional initiators as fully described in the prior art. Random copolymers having oxyethylene contents of 10 to 80 *, block copolymers having oxyethylene contents of up to 25 Ϊ, and random/block copolymers having oxyethylene contents of up to 50 « , based on the total weight of oxyalkylene units may be mentioned. Mixtures of the said diols and triols can be particularly useful. Preferred diols and triols are ethylene glycol, diethylene glycol, dipropylene glycol and glycerol. The preferred polyether polyols are block copolymers having oxyethylene blocks at the termini of the polyethers. Such block copolymers are referred to as ethyleneoxide capped polyols. The oxyethylene content of these preferred ethyleneoxide capped polyols is preferably at least 7 % by weight of the total oxyalkylene units. The total amount of polyether polyol known in the art for the production of flexible polyurethane foams is between 1 and 25 %, preferably between 1 and 15 %, most preferably between 1 and 10 % by weight based on the total isocyanate-reactive components. According to a further preferred embodiment of the present invention the polyisocyanate composition for use in the present process comprises the reaction product of a stoichiometric excess of an organic polyisocyanate and (a) substantially fluorinated isocyanate-reactive compound (s) . The term substantially fluorinated isocyanate-reactive compound as used herein is to be understood to refer to any organic compound having at least one isocyanate-reactive functional group in which at least 50 % of those hydrogen atoms bonded to carbon atoms in the corresponding unfluorinated compound are replaced by fluorine atoms. Reaction products of organic polyisocyanates and substantially fluorinated isocyanate-reactive compounds to be used in the process of the present invention are described in EP-A-0605105, which is incorporated herein by reference. Particularly preferred substantially fluorinated isocyanate-reactive compounds are those of formula (I) A-(SO : -N -(CH n -OH (I) R wherein A is a substantially fluorinated or perfluorinated, straight or branched chain alkyl group containing from 2 to 10 carbon atoms, n is an integer of from 1 to 11, x is 0 or 1 and R is hydrogen or a C ι ,, alkyl group or R'-OH wherein R' is a C . alkylene group. Particular mention may be made of those compounds of formula (I) wherein n is 1 or 2, A is perfluorinated C 3 L , preferably C 6 „, straight or branched chain alkyl, R is hydrogen or C,., alkyl and R' is C A _, alkylene such as (perfluoropropyl)methanol, (perfluorobutyl(methanol, (perfluoropentyl)- methanol, perfluoro (hexyl)methanol, (perfluoroheptyl)methanol, (perfluorooctyl)methanol, (perfluorononyl)methanol, (perfluoroethyl)- ethanol, (perfluoropropyl ) ethanol , (perfluorobutyl ) ethanol, (perfluoropentyl)ethanol, (perfluorohexyl)ethanol, (perfluoroheptyl)ethanol, (perfluorooctyl) ethanol, N-ethyl-N-2-hydroxyethylperfluorooctane sulfonamide, N-methyl-N-2-hydroxyethylperfluorooctane sulfonamide, N-propyl -N-2-hydroxyethylperf luorooctane sulfonamide, N-2-hydroxyethyl- perfluorooctane sulfonamide, N-ethyl-N-2-hydroxyme thy lperf luorooctane sulfonamide, N-methyl-N-2-hydroxymethylperfluorooctane sulfonamide, N-propyl-N-2-hydroxymethylperf luorooctane sulfonamide, N-2-hydroxymethyl- perf luorooctane sulfonamide, N-methyl-N-2-hydroxyethylperf luorooctane sulfonamide and bιs-N-2-hydroxyethylperf luorooctane sulfonamide. Suitable organic polyisocyanates with which the substantially fluorinated isocyanate-reactive compound (s) may be reacted to form the reaction product for use in the process of the present invention include any of those known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams, and in particular the aromatic polyisocyanates such as diphenylmethane diisocyanate in the form of its 2,4'-, 2,2'- and 4, '-isomers and mixtures thereof, the mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof known in the art as "crude" or polymeric MDI (polymethylene polyphenylene polyisocyanates) having an isocyanate functionality of greater than 2, toluene diisocyanate in the form of its 2,4- and 2,6-ιsomers and mixtures thereof, 1, -naphthalene diisocyanate and 1, 4-dιιsocyanatobenzene . Other organic polyisocyanates which may be mentioned include the aliphatic diisocyanates such as isophorone diisocya ate, 1 , 6 - d I l s o c y a n a t o he x a n e and 4, '-diisocyanatodicyclohexylmethane. The above polyisocyanate composition for use in the process of the present invention may be conveniently prepared by addition of a particular substantially fluorinated isocyanate-reactive compound to the organic polyisocyanate or by addition of a mixture of several different substantially fluorinated isocyanate-reactive compounds to the organic polyisocyanate, for example under the conditions well known in the art for the preparation of isocyanate-ended prepolymers. Preferably the substantially fluorinated isocyanate-reactive compound (s) is (are) added in an amount in the range from 0.02 to 5 *, preferably 0.1 to 3 % by weight based on the weight of organic polyisocyanate. In order to improve the stability of the polyisocyanate composition it is advantageous to use the allophanate variant of the obtained fluorinated isocyanate-ended prepolymer. This allophonate variant can be prepared by reaction of the obtained fluorinated isocyanate-ended prepolymer with the organic polyisocyanate itself in the presence of a suitable catalyst. The polyisocyanate composition for use m the process of the present invention may comprise only one type of said reaction product or may comprise different types of said reaction product derived from different substantially fluorinated isocyanate-reactive compounds and/or different polyisocyanates. In a preferred embodiment of the present invention the polyisocyanate composition comprises a reaction product of an organic polyisocyanate and a substantially fluorinated isocyanate-reactive compound as described above and the polyfunctional isocyanate-reactive composition comprises a polyether polyol known for manufacturing flexible polyurethane foams as described above and an amine-initiated polyether polyol known for manufacturing rigid polyurethane foams as described above. Rigid polyurethane foams prepared by using t.ms combination of ingredients also show good thermal insulation properties Suitable organic polyisocyanates for use in tne process of the present invention include any of those known in the art for the preparation of rigid polyurethane or urethane-modified polyisocya n urate foams, and in particular the aromatic polyisocyanates such as dipnenyl ethane diisocyanate in the form of its 2,4'-, 2,2'- and 4, 4 '-isomers ana mixtures thereof, the mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof known in the art as "crude" or polymeric MDI (polymethylene polyphenylene polyisocyanates) having an isocyanate functionality of greater than 2, toluene diisocyanate in the form of its 2,4- and 2, 6-ιsomers and mixtures thereof, 1, 5-naphthalene diisocyanate and 1, -dιιsocyanatobenzene. Other organic polyisocyanates which may be mentioned include the aliphatic diisocyanates such as isophorone diisocyanate, 1, 6-dιιsocyanatohexane and 4, ' -diisocyanatodicyclohexylmethane . Further suitable polyisocyanates for use in the process of the present invention are those described in EP-A- 0320134. Further polyfunctional isocyanate-reactive compositions with which the polyisocyanate composition can be reacted to form the rigid polyurethane or urethane-modified polyisocyanurate foams cf the present invention include any of those known in the art for that purpose Of particular importance for the preparation of rigid foams are polyols and polyol mixtures having average hydroxyl numbers of from 300 to 1000, especially from 300 to 700 mg KOH/g, and hydroxyl functionalities of from 2 to 8, especially from 3 to 8. Suitable polyols have been fully described in the prior art and include reaction products of alkylene oxides, for example ethylene oxide and/or propylene oxide, with initiators containing from 2 to 8 active hydrogen atoms per molecule. Suitable initiators include: polyols, for example glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol and sucrose; and mixtures of such initiators. Other suitable polymeric polyols include polyesters (especially aromatic polyesters) obtained by the condensation of appropriate proportions of glycols and higher functionality polyols with dicarboxylic or polycarboxylic acids. Still further suitable polymeric polyols include hydroxyl terminated polythioethers, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes. The quantities of the polyisocyanate compositions and the polyfunctional isocyanate-reactive compositions to be reacted will depend upon the nature of the rigid polyurethane or urethane-modified polyisocyanurate foam to be produced and will be readily determined by those skilled in the art. The process of the present invention is carried out in the presence of any of the blowing agents known in the art for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams. Such blowing agents include water or other carbon dioxiαe-evolvmg compounds, or inert low boiling compounds having a boiling point of above -70°C at atmospheric pressure. Where water is used as blowing agent, the amount may be selected in known manner to provide foams of the desired density, typical amounts being in the range from 0.05 to 5 * by weight based on tie total reaction system. Suitable inert blowing agents include those well known and described in the art, for example, hydrocarbons, dialkyi ethers, alkyl alkanoates, aliphatic and cycloaliphatic hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons and fluorine-containing ethers. Examples cf preferred blowing agents include n-pentane, isopentane, cyclopentane and any mixture thereof, 1, l-dιchloro-2-fluoroethane (HCFC 141b), 1, 1, l-tπfluoro-2-fluoroethane (HFC 134a), chlorodifluoromethane (HCFC 22), 1, l-dιfluoro-3, 3, 3-trif1uoropropane (HFC 245fa), 1, 1-dιfluoroethane (HFC 152a), 1, 1, 1,2, 3, 3-hexafluoropropane (HFC 236ea), 1, 1, 1, 4, 4, 4-hexafluorobutane (HFC 356mfa , 1, 1, 1,3,3-pentafluorobutane (HFC 365mfc) , difluoromethane (HFC 32) and blends thereof, including blends of hydrocarbons and hydrochlorofluorocarbons and/or hydrofluorocarbons. Particular mention may be made of blowing agent mixtures as described in PCT Patent Publication No. 96/12758, incorporated herein by reference, for manufacturing low density, dimensionally stable rigid polyurethane foams. These blowing agent mixtures generally comprise at least 3 and preferably at least 4 components of which preferably at least one is a (cyclo) alkane (preferably of 5 or 6 carbon atoms. and/or acetone. The total quantity of blowing agent to be used in a reaction system for producing cellular polymeric materials will be readily determined by those skilled in the art, but will typically be from 2 to 25 % by weight based on the total reaction system. The density of the foams of the present invention is generally in the range 15 to 70 kg/m 3 , preferably 20 to 50 kg/m 3 , most preferably 25 to 40 kg/m 3 . In addition to the polyisocyanate and polyfunctional isocyanate-reactive compositions and the blowing agent, the foam-forming reaction mixture will commonly contain one or more other auxiliaries or additives conventional to formulations for the production of rigid polyurethane and urethane-modified polyisocyanurate foams. Such optional additives include crosslinking agents, for examples low molecular weight polyols such as triethanolamine, urethane catalysts, for example tin compounαs such as stannous octoate or dibutyltin dilaurate or tertiary amines such as dimethylcyclohexylamine or triethylene diamine, and fire retardants, for example halogenated alkyl phosphates such as tris chloropropyl phosphate. The foam-forming reaction mixture may also contain foam-stabilising agents or surfactants which are not silicone-based such as acetylene based surfactants, fluorinated surfactants (e.g. as described in US 5453540, US 52S2716, US 5211873, US 5210106, US 5162385 and m Organofluorine Chemistry' by R. Banks, B. Smart, J. Tatlow, Chapters 11, 14, 17, 20, 21, 22), chlorylated or propoxylated nonyl phenols, ethoxylated or propoxylated C 6 -C 2- monols, cationic or anionic surfactants, or others as described in 'Handbook of surfactants', 1991, by Porter, Chapters 6 to 12. Addition of such surfactants may improve the thermal insulation properties of the foams of the present invention. Another additive which may be used in the process of the present invention is an insoluble fluorinated compound yielding foams having smaller cell sizes and improved thermal insulation. The term insoluble as used herein with respect to the insoluble fluorinated compound is defined as showing a solubility in either the isocyanate- reactive composition or the polyisocyanate composition with which it is to be blended of less than 500 ppm by weight at 25°C and atmospheric pressure. Insoluble fluorinated compounds for use in the process of the invention include any of those disclosed in US Patent No. 4,981,879, US Patent No. 5,034,424, US Patent No. 4,972,002, European Patent Applications Nos 0508-649 and 0498628 and PCT Patent Application No. 95/18176. It is preferred to use an insoluble, substantially fluorinated or perfluorinated compound having a boiling point of at least 20°C at atmospheric pressure. The term substantially fluorinated as used nerein with reference to the insoluble, substantially fluorinated compound used n the process of the invention is to be understood to embrace compounds in which at least 50 % of the hydrogen atoms of the unfluorinated compounds are replaced by fluorine. Suitable compounds include substantially fluorinated or perfluorinated hydrocarbons, substantially fluorinated or perfluorinated ethers, substantially fluorinated or perfluorinated tertiary amines, substantially fluorinated or perfluorinated amino-ethers and substantially fluorinated or perfluorinated sulphones. Suitable examples of substantially fluorinated or perfluorinated hydrocarbons are those containing from 1 to 15 carbon atoms, which may be either cyclic or acyclic, either aromatic or aliphatic and either saturated or unsaturated, such as substantially fluorinated and perfluorinated methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, cyclobutane, cyclooctane, cyclohexane, cyclopentane, cycloheptane, norbornadiene, decaline, dimethylcyclobutane, methylcyclohexane, 1- methyldecaline, phenanthrene, dimethylcyclobutane, and isomers thereof. Particular mention may be made of the various isomers of perfluoropentane and perfluorohexane such as perfluoro-n-pentane and perfluoro-n-hexane and of hexafluoropropene dimers and trimers such as perfluoro (4-methylpent-2- ene) . Certain insoluble fluorinated compounds suitable for use in the process of the invention may themselves act as blowing agents under the conditions pertaining to the foam-forming reaction, particularly where their boiling point is lower than the exotherm temperature achieved by the reaction mixture. For the avoidance of doubt, such materials may, partly or completely, fulfil the function of blowing agent in addition to that of insoluble fluorinated compound. The amount of the insoluble fluorinated compound used in the process of the present invention ranges from 0.05 to 10 % , preferably from 0.1 to 5 %, most preferably from 0.6 to 2.3 % by weight based on the total foam-forming composition. The insoluble fluorinated compound will usually be incorporated in the foam- forming reaction mixture in the form of an emulsion or preferably a microemulsion in one of the major components, that is to say in the isocyanate-reactive component and/or the polyisocyanate component. Such emulsions or microemulsions may be prepared using conventional techniques and suitable emulsifying agents, for example fluoro surfactants. In operating the process for making rigid foams according to the invention, the known one-shot, prepolymer or semi-prepolymer techniques may be used together with conventional mixing methods and the rigid foam may be produced in the form of slabstock, mouldings, cavity fillings, sprayed foam, frothed foam or laminates with other materials such as hardboard, plasterboard, plastics, paper or metal. The various aspects of this invention are illustrated, but not limited by the following examples in which the following ingredients are used: DALTOLAC R 180: a non-amine initiated polyether polyol available from Imperial Chemical Industries (f 4.5, OH value 440 mg KOH/g) . DALTOLAC R 260: a non-amine initiated polyether polyol available from Imperial Chemical Industries (OH value 310 mg KOH/g) . DALTOLAC R 130: a non-amine initiated polyether polyol available from Imperial Chemical Industries (OH value 460 mg KOH/g) . DALTOLAC R 200: a non-amine initiated polyether polyol available from Imperial Chemical Industries (OH value 380 mg KOH/g) . DALTOLAC R 090: a non-amine initiated polyether polyol available from Imperial Chemical Industries (OH value 540 mg KOH/g) . POLYOL X: a polyether polyol (f 3.2, OH vaiue 495 mg KOH/g) initiated by polymethylene polyphenylene polyamine. POLYOL Y: a polyether polyol (OH value 310 mg KOH/g) initiated by polymethylene polyphenylene polyamine. DALTOCEL F 455: an ethyleneoxide-capped polyether polyol available from Imperial Chemical Industries (OH value 53-57 mg KOH/g) . DALTOCEL F 428: an ethyleneoxide-capped polyether polyol available from Imperial Chemical Industries (OH value 26-30 mg KOH/g) . DALTOCEL F 430: an ethyleneoxide-capped polyether polyol available from Imperial Chemical Industries (OH value 28-32 mg KOH/g) . DALTOCEL F 436: an ethyleneoxide-capped polyether polyol available from Imperial Chemical Industries (OH value 24-38 mg KOH/g) . DALTOCEL F 452: an ethyleneoxide-capped polyether polyol available from Imperial Chemical Industries (OH value 50-54 mg KOH/g) . DALTOCEL F 448: a non-ethyleneoxide-capped polyether polyol available from Imperial Chemical Industries (OH value 46-50 mg KOH/g) . POLYOL A: a polyol blend of OH value 417 mg KOH/g comprising 60 % by weight of a polyether polyol initiated with polymetnylene polyphenylene polyamines. POLYOL B: a polyol blend of OH value 417 mg KOH/g comprising sucrose- mitiated polyether polyols. POLYOL C: a polyol blend of OH value 41 " mg KOH/g comprising sorbitol- initiated polyether polyols. PPG 425: polypropyleneglycol (MW 425) . Polycat 8: a catalyst available from Air Products. Polycat 5: a catalyst available from Air Products. NIAX Al : a catalyst available from Union Carbide. SFB: a catalyst available from Imperial Chemical Industries. L 6900: a silicone surfactant available from OSi. B 1400A: a silicone surfactant available from Goldschmidt. B 8461: a silicone surfactant available from Goldschmidt. SURFYNOL: non silicone containing surfactants available from A r Products. emulsifier: perfluorinated C f -C,. isomer mixture containing unsaturated bonds . SUPRASEC DNR: polymeric MDI available from Imperial Chemical Industries. SUPRASEC 2021: an MDI prepolymer available from Imperial Chemical Industries. PREPOLYMER: a polyisocyanate composition obtained by reacting SUPRASEC DNR with 0.1 % by weight (based on the polyisocyanate) of FC10, a perfluorooctane sulfonamide available from 3M. DALTOLAC, DALTOCEL and SUPRASEC are trademarks of Imperial Chemical Industries. EXAMPLE 1 Rigid foams were prepared from the ingredients listed below in Table 1. The reaction profile is followed in respect cf cream time, string time and end of rise time. Following properties are measured: core density (according to standard DIN 53420), initial Lambda value at 10°C (according to standard ISO 2581) and compression strength (according to standard DIN 53421) in the direction of rise and perpendicular to rise. The results are listed in Table 1. These results show that for a similar density and reaction profile foams of the present invention (Foams nos. 2 and 3) have a more isotropic structure and higher compression strengths especially in the direction perpendicular to rise than the reference foam (No. 1) containing a silicone-based surfactant. Further it is observed that Foam No. 1 shrinks while Foams Nos 2 and 3 don't shrink at all. Additional use of a fluorinated isocyanate- ended prepolymer (Foam No. 3) leads to improved thermal insulation (Lambda) . EXAMPLE 2 Rigid foams were prepared at an NCO index of 105 from the ingredients listed in Table 2. Foams 5 to 12 all collapsed while Foams 1 to 4 had a good foam structure, especially Foams 3 and 4. Table 1 Foam No. 1 2 3 POLYOL DALTOLAC R180 pbw 20 20 20 POLYOL X pbw 80 80 80 DALTOCEL F455 pbw 0 2 2 Polycat 8 pbw 1 1 1 Polycat 5 pbw 0.3 0.3 0.3 L 6900 pbw 2.5 0 0 water pbw 1.63 1.63 1.63 HCFC 141b pbw 33.5 33.5 33.5 ISOCYANATE SUPRASEC DNR pbw 155.78 155.28 0 PREPOLYMER pbw 0 0 155.57 Index 108 108 108 REACTION PROFILE Cream time sec 11 10 10 String time sec 50 50 47 End of rise time sec 130 125 130 Core density kg/m 3 26.3 26.9 27.5 Initial Lambda mW/mK 19.5 21.0 19.1 Compression strength Rise kPa 83 105 112 Perpendicular 1 kPa 65 92 115 Perpendicular 2 kPa 178 117 141 Example 3 Pigid foams were prepared from the ingredients listed below in Table 3. The results presented in Table 3 show that the presence of an amine- mitiated polyether polyol is necessary in a silicone-free formulation (Foam 15 compared to Foam 14) . Stable lower density foam can be obtained by the present invention (Foam 15 compared to Foam 13) . Table 3 Foam No. 13 14 15 POLYOL DALTOLAC R130 pbw 28.7 28.7 0 POLYCL X pbw 0 0 28.7 DALTOLAC R200 pbw 33.4 33.4 33.4 PPG 425 pbw 9.6 9.6 0 DALTOCEL F455 pbw 0 0 9.6 B 1400A pbw 1.6 0 0 NIAX Al pbw 0.18 0.18 0.18 SFB pbw 0.29 0.29 0.29 Polycat 8 pbw 0.4 0.4 1.2 water pbw 3.65 3.65 3.65 ISOCYANATE SUPRASEC DNR pbw 141.3 0 0 PREPOLYMER pbw 0 141.25 139.1 Foam quality good collaps good Density kg/m 32 29 Stability good good Example 4 Rigid polyurethane foams were prepared from the ingredients listed in Table 4. Foam properties were measured. The res-ilts are presented in Table 4. Table 4 Foam No. 16 17 POLYOL DALTOLAC R130 pbw 28.7 0 POLYOL X pbw 0 28.7 DALTOLAC R200 pbw 33.4 33.4 PPG 425 pbw 9.6 0 DALTOCEL F455 pbw 0 9.6 DALTOLAC R090 pbw 9.6 9.6 B 1400A pbw 1.6 0 NIAX Al pbw 0.18 0.18 SFB pbw 0.29 0.29 Polycat 8 pbw 0.7 0.35 water pbw 5 5.2 ISOCYANATE SUPRASEC DNR pbw 162.41 0 PREPOLYMER/SUPRASEC 2021 80/20 pbw 0 171.8 Density kg/πr 25 26 Overpack % 5 5 Compression strength Height kPa 80.4 83.5 Width kPa 66.9 112.0 Length kPa 132.4 111.4 Mean kPa 93.2 102.3 Example 5 Rigid polyurethane foams were prepared from the ingredients listed in Table 5. Foam properties were measured. The results as presented in Table 5 illustrate the improvement in thermal insulation when an additional non- silicone surfactant is being used. Table 5 Foam No. 18 19 POLYOL POLYOL X pbw 21 21 POLYOL Y pbw 38 38 DALTOLAC R180 pbw 35.4 35.4 DALTOCEL F428 pbw 2 2 NIAX Al pb« 0.3 0.3 Polycat 8 pbw 1.3 1.3 cyclopentane pbw 14 14 emulsifier pbw 0 3 water pbw 2.33 2.33 ISOCYANATE PREPOLYMER pbw 143 145 Density kg/r 25.8 26.8 Lambda value mW/mK 22.2 20.6 Example 6 Rigid polyurethane foams were prepared from tre ingredients listed in Table 6. Foam properties were measured. The results as presented in Table 6 illustrate the improvement in compression strength by the foams of the present invention. Table 6 Foam No. 20 21 POLYOL POLYOL X pbw 21 21 POLYOL Y pbw 38 38 DALTOLAC R180 pbw 35.4 35.4 DALTOCEL F428 pbw 0 2 B 8461 pbw 2 0 NIAX Al pbw 0.3 0.3 Polycat 8 pbw 1.3 1.3 cyclopentane pbw 14 14 water pbw 2.33 2.33 ISOCYANATE SUPRASEC DNR pbw 142.8 143.1 Density kg/m 3 25.3 24.8 Compression strength Height kPa 106.3 99.0 Width kPa 76.6 98.1 Length kPa 94.0 85.6 Mean kPa 93.1 94.4 Lambda value mW/mK 21.7 22.4 Example 7 Rigid polyurethane foams were prepared from the ingredients listed in Table 7. Foam properties were measured. The results are presented in Table 7. Table 7 Foam No. 22 23 24 25 26 POLYOL POLYOL X pbw 21 21 21 21 21 POLYOL Y pbw 38 38 38 38 38 DALTOLAC R180 pbw 35.4 35.4 35.4 35.4 35.4 DALTOCEL F428 pbw 2 2 2 2 SURFYNOL 420 pbw 0 2 0 0 0 SURFYNOL 440 pbw 0 0 2 0 0 SURFYNOL 465 pbw 0 0 0 2 0 SURFYNOL 485 pbw 0 0 0 0 2 NIAX Al pbw 0.3 0.3 0.3 0.3 0.3 Polycat 8 pbw 1.3 1.3 1.3 1.3 1.3 cyclopentane pbw 14 14 14 14 14 water pbw 2.33 2.33 2.33 2.33 2.33 ISOCYANATE SUPRASEC DNR pbw 143.1 143.1 143.1 143.1 143.1 Density kg/m 3 30.5 30.6 30.3 30.0 30.3 Compression strength Height kPa 127.9 125.4 133.4 126.6 123.8 Width kPa 111.7 119.1 107.3 105.9 106.5 Length kPa 114.2 123.4 108.8 114.4 102.8 Mean kPa 118.1 122.7 117.1 115.9 111.4 Lambda value mW/mK 22.2 22.3 21.8 22.1 23.1 Example 8 Rigid foams were prepared at an NCO index of 112 from the ingredients listed below in Table 8. The results presented in Table 8 show that more isotropic foams are obtained by using the process of the present invention. Table 8 Foam No. 27 28 29 POLYOL POLYOL X pbw 21 21 21 POLYOL Y pbw 38 38 38 DALTOLAC R180 pbw 35.4 35.4 35.4 DALTOCEL F428 pbw 0 0 2 B 8461 pbw 2 0 0 NIAX Al pbw 0.3 0.3 0.3 Polycat 8 pbw 1.3 1.3 1.3 cyclopentane pbw 12 14 14 water pbw 2 2.33 2.33 ISOCYANATE SUPRASEC DNR pbw 137.0 143.0 0 PREPOLYMER pbw 0 0 143.0 Core density kg/πr 32.6 29.9 29.7 Flow cm/g 0.30 0.33 0.34 Compression strength Rise kPa 166 132 142 Length kPa 179 139 159 Width kPa 146 132 144 Example 9 Rigid foams were prepared from the ingredients listed below in Table 9. The results presented in Table 9 show that it is beneficial to use a polyether polyol known for the preparation of flexible polyurethane foams that has an ethyleneoxide tip. Table 9 Foam No. 30 31 32 33 34 35 POLYOL POLYOL X pbw 21 21 21 21 21 21 POLYOL Y pbw 38 38 38 38 38 38 1 DALTOLAC R180 pbw 35.4 35.4 35.4 35.4 35.4 35.4 DALTOCEL F 28 pbw 2 0 0 0 0 0 DALTOCEL F430 pbw 0 2 0 0 0 0 DALTOCEL F436 pbw 0 0 - ~ 0 0 0 DALTOCEL F448 pDW 0 0 - ' 2 0 0 DALTOCEL F452 pbw 0 0 0 2 0 DALTOCEL F455 pbw 0 0 0 0 2 NIAX Al pbw 0.3 0.3 0.3 0.3 0.3 0.3 Polycat 8 pbw 1.3 1.3 1.3 1.3 1.3 1.3 cyclopentane pbw 14 14 14 14 14 14 water pbw 2.33 2.33 2.33 2.33 2.33 2.33 ISOCYANATE PREPOLYMER pbw 143.0 143.0 143.0 143.0 143.0 143.0 Foam quality good good okay coarse okay okay Example 10 Rigid foams were prepared from the ingredients listed below in Table 10. The results presented in Table 10 illustrate the effect of the amine- mitiated polyether polyol (amount thereof; . Example 11 Rigid foams were prepared from the ingredients listed below in Table 11. The results presented in Table 11 illustrate the effect of the amine- initiated polyether polyol. Example 12 Rigid foams were prepared at an NCO index of 108 from the ingredients listed below in Table 12. The results presented in Table 12 show that more stable foams (dimensional stability measured according to standard ISO 2796) at lower densities can be obtained using the process of the present invention. Also the flow is improved. Thermal insulation properties can be further improved by using a non-silicone surfactant. Table 12 Foam No. 60 61 62 POLYOL POLYOL X pbw 80 80 80 DALTOLAC R180 pbw 20 20 20 DALTOCEL F428 pbw 0 2.5 2.5 L 6900 pbw 2.5 0 0 Polycat 8 pbw 1 1 1 Polycat 5 pbw 0.3 0.3 0.3 HCFC 141b pbw 33.5 37 37 water pbw 1.63 2 2 ISOCYANATE SUPRASEC DNR pbw 155.28 161.36 0 PREPOLYMER pbw 0 0 161.36 emulsifier pbw 0 0 3.23 Overall density kg/m 3 31.8 28.5 28.5 Flow cm/g 0.31 0.35 0.36 Compression strength Rise kPa 70.5 94. " 86 Length kPa 160.3 107.4 115.8 Width kPa 86.3 106. S 105.1 Dimensional Stability 1 day -20°C -- * 6.95 0.09 0.16 1 day 70°C - 1.53 0.91 0.77 1 day 100°C Έ 2.08 1.63 1.62 1 day 70°C/100 i RH % 4.56 4.19 4.49 14 days -20°C * 17.8 0.61 0.28 14 days 70°C % 2.98 2.98 3.01 14 days 100°C r 3.88 4.23 4.32 14 days 70°C/100? RH * 6.98 3.8 7.49 Lambda value initial mW/mK 17.2 18.1 17.4 1 week/70°C mW/ K 19.5 3 weeks/70°C mW/mK 21.2 22.1 21 5 weeks/70°C mW/mK 22.3 22.9 22.2

Claims: CLAIMS 1. Process for preparing a rigid polyurethane or urethane-modified polyisocyanurate foam comprising the step of reacting a polyisocyanate composition with a polyfunctional isocyanate-reactive composition in the absence of a silicone-based surfactant characterised n that the polyfunctional isocyanate-reactive composition comprises an amine-initiated polyether polyol. 2. Process according to claim 1 wherein the amine-initiated polyether polyol is the reaction product of alkylene oxides with an amine initiator containing from 2 to 8 active hydrogen atoms per molecule. 3. Process according to claim 2 wherein the initiator is an aromatic amine. 4. Process according to claim 3 wherein the amine initiator is polymethylene polyphenylene polyamine. 5. Process according to any one of the preceding claims wherein the amine-initiated polyether polyol has an OH value m the range 300 to 1000 mg KOH/g. 6. Process according to any one of the preceding claims wherein the amine-initiated polyether polyol is present in an amount of at least 20 - by weight based on the total isocyanate-reactive compounds. 7. Process according to any one of the preceding claims wherein the polyfunctional isocyanate-reactive composition further comprises a polyether polyol of average nominal functionality 2 to 6 and number average molecular weight between 1000 and 10000. 8. Process according to claim 7 wherein said polyether polyol has an average nominal functionality of 2 to 4. 9. Process according to claim 7 or 8 wherein said polyether polyol has an OH value of between 20 and 80 mg KOH/g. 10. Process according to claim 7, 8 or 9 wherein said polyether polyol is a polyoxypropylene diol or triol or a poly(oxyethylene-oxypropylene) diol or triol obtained by the simultaneous or sequential addition of ethylene and propylene oxides to di- or trifunctional initiators. 11. Process according to claim 10 wherein said di- or trifunctional initiators are selected from the group consisting of ethylene glycol, diethylene glycol, dipropylene glycol and glycerol. 12. Process according to claim 10 or 11 wherein said polyether polyol is an ethyleneoxide capped block copolymer with an oxyethylene content of at least 7 % by weight based on the total oxyalkylene units. 13. Process according to any one of claims 7 to 12 wherein said polyether polyol is used in amounts ranging from 1 to 25 % by weight based on the total isocyanate-reactive components 14 Process according to any one of the preceding claims wherein the polyisocyanate composition comprises t r e reaction product of a stoichiometric excess of an organ-.- polyisocyanate and (a) substantially fluorinated isocyanate-reacti j compound(s) . 15. Process according to claim 14 wherein saiα substantially fluorinated isocyanate-reactive compound corresponds to the formula (I) A- (SO -N) Λ -(CH ) -OH ( I ) R wherein A is a substantially fluorinated or perfluorinated, straight or branched chain alkyl group containing from 2 to 10 carbon atoms; n is an integer of from 1 to 11; x is 0 or 1; and R is hydrogen or a C alkyl group or ° ' -CH wherein R' is a C alkylene group. 16. Process according to claim 15 here-n n is 1 or 2, A is perfluorinated C x straight or branched chain alkyl, R is hydrogen or C, , alkyl and R' is C alkylene. 17 Process according to claim 14, 15 or ic wnerein the organic polyisocyanate with which the substantially fluorinated isocyanate- reactive compound is reacted is diphenylmethane diisocyanate in the form of its 2,4'-, 2,2'- or , 4 '-isomers or mixtures thereof or polymethylene polyphenylene polyisocyanates. 18 Process according to any one of claims 14 to 17 wherein the substantially fluorinated isocyanate-reactive compound is used in an amount in the range from 0.02 to 5 % oy weight based on the weight of the organic polyisocyanate. 19. Process according to any one of the preceding claims wherein the process is carried out in the presence of a blowing agent selected from the group comprising hydrocarbons and hydrofluorocarbons . 20. Process according to any one of the preceding claims wherein the foam forming formulation contains a surfactant which is not silicone based. 21. R igi d polyurethane or urethane-modified polyisocyanurate foam o b taina b le by the process as defined in any one of the preceding claims.

Inventors: DE VOS RIK, DE VOS, RIK
Applicants: ICI PLC, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1996
Main classification: C08G18
IPC codes: C08G18, C08G101, C08J9