NEW POLYOLS AND THEIR USE IN POLYURETHANE PREPARATION

Abstract: Polyols comprising oxybutylene groups are described, as well as prepolymers thereof and processes to prepare flexible polyurethane foams thereof.

Description: New polyols and their use in polyurethane preparation. DESCRIPTION The present invention is concerned with novel polyols, a process for making them and the use of such polyols in preparing polyurethanes. Polyurethane materials are prepared by reacting polyisocyanates and polyols. Amongst the polyols used are polyether polyols having a relatively high molecular weight, e.g. 2000-6000. Such polyether polyols conventionally are polyoxypropylene polyols and polyoxypropylene polyoxyethylene copolymer polyols which may be block copolymers or random copolymers or a combination thereof. A widely used type of polyether polyol is a polyol having a molecular weight of 3000-6000, a nominal hydroxy functionality of 3, a polyoxypropylene and a polyoxyethylene block wherein the polyoxyethylene block is at the end of the three tails of the polymer and constitutes 5-20% by weight of the weight of the polymer; see e.g. The ICI Polyurethanes Book by G. Woods, 1987, J.Wiley and sons, ISBN 0471914266, pages 35-41. Such polyols have been used to make polyurethane materials and in particular elastomers and flexible foams of good quality. However further improvements would be desirable. In particular the stability of such materials as to hydrolysis could be improved as well as resilience and compression set properties. EP-344540 discloses a blend of polypropyleneoxide polyol and polybutyleneoxide polyol, which may be a copolymer with ethylene oxide, propylene oxide and pentalene oxide. The blends are used to make a prepolymer which is used in sealant and coating compositions. The copolymers may be random or block, the amount of comonomer may be up to 60% by weight. US 4,701,520 discloses the preparation of polybutyleneoxide. US 4,465,663 discloses aqueous gels of polyoxybutylene-polyoxyethylene block copolymers having a molecular weight of at least 1200 and an oxyethylene content of 45to 85% by weight. They are used for topically applied cosmetic and pharmaceutical compositions. WO95/16721 discloses the use of non-silicone polyether surfactants in the preparation of polyurethane, polyisocyanurate and polyurea foams. It has been disclosed in wide terms that the surfactants may be used to prepare elastomers, rigid foams or flexible foams. More specifically it has been disclosed that the surfactants act as compatibilisers of polyisocyanates with the other formulation components and as foam stabilisers in insulation and rigid foams. In the examples polyisocyanurate rigid foams are made. The non-silicone polyether surfactnats are polymers comprising substantially no oxypropylene units, 10-90% by weight of oxyethylene units and 10-90% by weight of oxyalkylene units having at least 4 carbons e.g. butylene oxide. Most preferred oxyethylene / oxybutylene ratios are 1.5:2 to 2.0:1.5 w/w. The surfactants may be capped or not, may have a functionality of 2-8 and are used in an amount of 0.25-20 parts by weight per 100 parts of active hydrogen including compounds. In the examples surfactants have been used which invariably have a nominal functionality of 1 or 2. GB 1063278 discloses a process for preparing elastomers using copolymers of ethylene oxide and 1,2-, 2,3-, or iso-butylene oxide comprising 10-50 and preferably 35-50% by weight of oxyethylene units. The copolymers used are random copolymers. EP383544 discloses the use polyether polyols comprising isobutylene oxide and mono- or unsubstituted alkylene oxide. Only propylene oxide capped copolymers have been used. US4301110 discloses the use of poly(oxybutylene oxyethylene) glycols in preparing reaction injection molded elastomers for improving heat distortion and tear properties. The glycols used have random oxybutylene / oxyethylene blocks. JP57000118 discloses the use of copolymers of ethylene oxide and another 5 alkylene oxide like butylene oxide in preparing rigid polyurethane foams. The copolymers have a low equivalent weight. WO92/06846 discloses curable liquid resin compositions comprising a urethane (meth)acrylate polymer for coating materials. The polymer is made amongst others from a polyol comprising ethylene oxide and 1,2 butylene oxide. As such o polyols copolymerized diols have been used. In the Journal of the American Oil Chem. Soc,, Vol 72, No. 1 (1995) pages 89-95 non-ionic surfactants are described like butylene oxide/ ethylene oxide block copolymers having a functionality of 2. Copending patent application EP-781791 discloses the use of polyether polyols 5 made from butylene oxide in the preparation of elastomers, sealants and adhesives. A wide range of polyols made from butylene oxide may be used according to the description. In the examples their seems to be a trend to use either polyols having a functionality of 2 and an intermediate amount of ethylene oxide or polyols having a functionality of 3 and a low amount of ethylene oxide; 0 the polyols used invariably have an intermediate block of a mixture of butylene oxide and ethylene oxide The polyols should have an oxypropylene block between the initiator and the butylene oxide. Hereinafter the following abbreviations will be used: EO for ethylene oxide EOR for an oxyethylene group PO for 1 ,2 -propylene oxide POR for an 1 ,2-oxypropylene group BO for butylene oxide except 1,4-butylene oxide BOR for an oxybutylene group except 1 ,4- oxybutylene group 1,2-BO for 1,2-butylene oxide 2,3 -BO for 2,3 -butylene oxide iso-BO for isobutylene oxide AO for alkylene oxide having 3 or more carbon atoms and preferably 3 or 4 carbon atoms AOR for an oxyalkylene group having 3 or more carbon atoms and preferably 3 or 4 carbon atoms Surprisingly we have found that the use of a novel polyol containing BOR improves the resistance to hydrolysis of flexible polyurethane foams and their resilience and compression set properties. In addition to that the level of unsaturation in such polyols is lower than in polyols which have POR instead of BOR. Consequently the present invention is concerned with a polyether polyol having an equivalent weight of 500-10000, an average nominal hydroxyl functionality of 2-8 and having per polymer chain an AOR block and an EOR block wherein the AOR block contains BOR and optionally POR and the amount of the AOR blocks is 70-95% by weight and the amount of the EOR blocks is 5-30% by weight both calculated on the weight of the AOR blocks and the EOR blocks and wherein the EOR blocks are at the end of the polymer chains. Further the present invention is concerned with a process for preparing such polyether polyols by allowing a compound (hereinafter "initiator"), having 2-8 hydrogen atoms which are reactive with alkylene oxides, to react with BO and optionally with PO and by allowing the product so obtained to react with EO, wherein the amounts of BO, optionally PO, and EO are such that the above ranges as to equivalent weight and amounts of AOR and EOR blocks are met. In the context of the present application the following terms have the following meaning : 1) isocyanate index or NCO index or index : the ratio of NCO-groups over isocyanate-reactive hydrogen atoms present in a formulation, given as a percentage : ΓNCOIX 100 (%) [ active hydrogen] In other words the NCO-index expresses the percentage of isocyanate actually used in a formulation with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in a formulation. It should be observed that the isocyanate index as used herein is considered from the point of view of the actual foaming process involving the isocyanate ingredient and the isocyanate-reactive ingredients. Any isocyanate groups consumed in a preliminary step to produce the semi-prepolymer or other modified polyisocyanates or any active hydrogens reacted with isocyanate to produce modified polyols or polyamines, are not taken into account in the calculation of the isocyanate index. Only the free isocyanate groups and the free isocyanate-reactive hydrogens (including those of the water) present at the actual foaming stage are taken into account. 2) The expression "isocyanate-reactive hydrogen atoms" as used herein for the purpose of calculating the isocyanate index refers to the total hydroxyl and amine hydrogen atoms present in the reactive compositions in the form of polyols, polyamines and/or water; this means that for the purpose of calculating the isocyanate index at the actual foaming process one hydroxyl groups is considered 5 to comprise one reactive hydrogen and one water molecule is considered to comprise two active hydrogens. 3) Reaction system : a combination of components wherein the poly isocyanate component is kept in a container separate from the isocyanate-reactive components. 104) The expression "polyurethane foam" as used herein generally refers to cellular products as obtained by reacting polyisocyanates with isocyanate-reactive hydrogen containing compounds, using foaming agents, and in particular includes cellular products obtained with water as reactive foaming agent (involving a reaction of water with isocyanate groups yielding urea linkages and carbon 15 dioxide and producing polyurea-urethane foams). 5) The term "average nominal hydroxyl functionality" is used herein to indicate the number average functionality (number of hydroxyl groups per molecule) of the polyol composition on the assumption that this is the number average functionality (number of active hydrogen atoms per molecule) of the 20 initiator(s) used in their preparation although in practice it will often be somewhat less because of some terminal unsaturation. The term "equivalent weight" refers to the molecular weight per isocyanate reactive hydrogen atom in the molecule. 6) The word "average" refers to number average. Preferably the equivalent weight of the polyol according to the present invention is 500-8000 and more preferably 750-5000; the nominal functionality preferably is 3-6 and more preferably 3-4. The amount of POR in the AOR block may range from 0 to 95% by weight and preferably ranges from 20-80% by weight. The amount of AOR and EOR blocks preferably is 75-92 and 8-25% by weight 5 respectively calculated on the total weight of the AOR and EOR blocks. As is generally known in the art polyether polyols in general are made by allowing an initiator, having at least 2 hydrogen atoms which are capable of reacting with alkylene oxides, to react with such alkylene oxides. When only one alkylene oxide is used homopolymers are formed. When two or more alkylene oxides are o used copolymers are formed. Such copolymers may be block copolymers or random copolymers or combinations thereof. Block copolymers are obtained when different alkylene oxides are allowed to react in consecutive order. Random copolymers are formed when mixtures of different alkylene oxides are used. Polymerisation occurs from all reactive hydrogens bound to the initiator. Hence 5 the final polyether polyol will have a number of polymeric tails corresponding to the original number of reactive hydrogens bound to the initiator. In general such polyether polyols are prepared by charging a vessel with the required amount of initiator and optionally with a catalyst enhancing alkoxylation. Then the alkylene oxide or oxides are added, in mixed form or in consecutive order or a combination 0 thereof as discussed above, and allowed to react. The reaction generally is conducted under an inert gas blanket, at a pressure of 1-5 bar abs and a temperature of 50-130°C. The amount of alkylene oxide used will depend on the molecular weight desired. The duration of the process depends on the other process conditions such as heat exchange, the desired molecular weight and the 5 type of alkylene oxide(s) used; in general the reaction time will vary of from a few hours to a few days. The process for preparing the polyols according to the present invention does not differ materially from the above described general process. BO tends to be less reactive than PO and therefore the reaction time may be somewhat longer. If PO is used to form the AOR block this may be done in admixture with BO or in any consecutive order or combinations thereof. 5 Preferably the order of addition of BO and PO is such that a polyol is obtained which has no POR block between the initiator and the BOR, which POR block constitutes more than 20 % by weight of the weight of all oxyalkylene groups in the final polyol. Most preferably the reaction of the initiator with the alkylene oxides starts with a mixture of BO and PO followed by reaction with EO. o Initiators which may be used are those known in the art like water, butanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, ethanolamine, diethanolamine, triethanolamine, toluene diamine, diethyl toluene diamine, phenyl diamine, diphenylmethane diamine, ethylene diamine, cyclohexane diamine, cyclohexane dimethanol, resorcinol, 5 bisphenol A, glycerol, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, sorbitol and sucrose. Mixtures of initiators may be used as well. As BO 1,2-butylene oxide, 2,3-butylene oxide, isobutylene oxide or mixtures thereof may be used. Preferably BO is used which comprises at least 50% by weight of 1,2-BO and most preferably is 1,2-BO. 0 Catalysts which may be used are those known in the art to enhance alkoxylation like alkali metal hydroxides or alkoxides, e.g. LiOH, NaOH, KOH, CsOH, Ba(OH) 2 and like organometallic compounds as described in e.g. Ring opening polymerisation of K.C. Frisch and S.L. Reegen, Marcel Dekker Publishers, 1969; Ring opening polymerisation of N. Spassky, vol. 8, no. 1 RAPRA Review (1995) 5 no. 85 and Alkylene oxides and their polymers of J.V. Koleske and F.E. Bailey, 1991, Wiley Publishers. The catalysts are used in amounts sufficient to catalyse the reaction; typical levels are 20 ppm to 10000 ppm based on final product. The present invention is further concerned with the use of the polyether polyols according to the present invention in preparing flexible polyurethane foams by reacting a polyisocyanate and a polyol according to the present invention and using a blowing agent. Processes for preparing flexible polyurethane foams are generally known in the art. Such processes involve the reaction of a polyisocyanate and a polyol having a relatively high molecular weight and the use of a blowing agent, optionally using a catalyst, a chain extender, a crosslinker and/or additives. Such processes may be used to prepare free rise moulded foam, slabstock foam and foam in a closed mould. The process may be conducted according to the so called one-shot method, the semi- or quasi-prepolymer method or the prepolymer method. According to the one-shot method all the polyols having a relatively high molecular weight, i.e. an equivalent weight of 500-10000, are combined with the polyisocyanate and allowed to react in the presence of a foaming agent. According to the semi- or quasi prepolymer process part of this polyol is prereacted with all or part of the polyisocyanate before foam formation is allowed to take place and according to the prepolymer process all this polyol is prereacted with all or part of the polyisocyanate before foam formation is allowed to take place. The polyisocyanates, isocyanate-reactive ingredients, blowing agent and additives are combined and allowed to react and foam in order to prepare the flexible foam. The isocyanate-reactive ingredients, the blowing agent and additives may be premixed. The foam forming reaction is conducted at an index of 40-120, preferably of 50-110. The process according to the present invention for making a flexible polyurethane foam may be conducted according to these known processes as long as at least 10% by weight and preferably at least 25% by weight of the conventional polyols having a relatively high equivalent weight are replaced by the polyol according to the present invention. Therefore the present invention is concerned with a process for preparing a flexible polyurethane foam by reacting a polyisocyanate and an isocyanate-reactive composition comprising a polyol according to the present invention in an amount of at least 10 % by weight (on composition) and using a blowing agent. Polyisocyanates which may be used may be selected from aliphatic, cycloaliphatic and araliphatic polyisocyanates, especially diisocyanates, like hexamethylene diisocyanate, isophorone diisocyanate, cyclohexane- 1,4-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and m- and p- tetramethylxylylene diisocyanate, and in particular aromatic polyisocyanates like tolylene diisocyanates (TDI), phenylene diisocyanates and most preferably, which MDI may be selected from pure 4,4'-MDI, isomeric mixtures of 4,4'-MDI and 2,4'-MDI and less than 10% by weight of 2,2'-MDI, crude and polymeric MDI having isocyanate functionalities above 2, and modified variants thereof containing carbodiimide, uretonimine, isocyanurate, urethane, allophanate, urea or biuret groups. Most preferred diphenylmethane diisocyanate optionally comprising homologues having an isocyanate functionality of 3 or more (MDI) are pure 4,4'-MDI, isomeric mixtures with 2,4'-MDI optionally containing up to 50% by weight of polymeric MDI and uretonimine and/or carbodiimide modified MDI having an NCO content of at least 25% by weight and urethane modified MDI obtained by reacting excess MDI and a low molecular weight polyol (MW less than 1000) and having an NCO content of at least 25% by weight. Mixtures of MDI with up to 25% by weight of other polyisocyanates mentioned above may be used if desired. The polyisocyanate may contain dispersed urea particles and/or urethane particles prepared in a conventional way, e.g. by adding a minor amount of an isophorone diamine to the polyisocyanate. The high molecular weight polyols used for preparing the flexible foams may be selected from polyesters, polyesteramides, polythioethers, polycarbonates, polyacetals, polyolefins, polysiloxanes and, especially, polyethers. Polyether polyols which may be used include products obtained by the polymerisation of ethylene oxide and/or propylene oxide in the presence, where necessary, of polyfunctional initiators. Suitable initiator compounds contain a plurality of active hydrogen atoms and include water, butanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, ethanolamine,diethanolamine, triethanolamine, toluene diamine, diethyl toluene diamine, phenyl diamine, diphenylmethane diamine, ethylene diamine, cyclohexane diamine, cyclohexane dimethanol, resorcinol, bisphenol A, glycerol, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, sorbitol and sucrose. Mixtures of initiators may be used. Especially useful polyether polyols 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 10-80%, block copolymers having oxyethylene contents of up to 25% and random/block copolymers having oxyethylene contents of up to 50%, based on the total weight of oxyalkylene units may be mentioned, in particular those having at least part of the oxyethylene groups at the end of the polymer chain. Mixtures of the said diols and triols can be particularly useful. Polyester polyols which may be used include hydroxyl-terminated reaction products of polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, 1 ,4-butanediol, neopentyl glycol, 1 ,6-hexanediol, cyclohexane dimethanol, glycerol, trimethylolpropane, pentaerythritol or polyether polyols or mixtures of such polyhydric alcohols, and polycarboxylic acids, especially dicarboxylic acids or their ester-forming derivatives, for example succinic, glutaric and adipic acids or their dimethyl esters, sebacic acid, phthalic anhydride, tetrachlorophthalic anhydride or dimethyl terephthalate or mixtures thereof. Polyesters obtained by the polymerisation of lactones, for example caprolactone, in conjunction with a polyol, or of hydroxy carboxylic acids such as hydroxy caproic acid, may also be used. Polyesteramides may be obtained by the inclusion of aminoalcohols such as ethanolamine in polyesterification mixtures. Polythioether polyols which may be used include products obtained by condensing thiodiglycol either alone or with other glycols, alkylene oxides, dicarboxylic acids, formaldehyde, amino-alcohols or aminocarboxylic acids. Polycarbonate polyols which may be used include products obtained by reacting diols such as 1,3-propanediol, 1 ,4-butanediol, 1,6-hexanediol, diethylene glycol or tetraethylene glycol with diaryl carbonates, for examples diphenyl carbonate, or with phosgene. Polyacetal polyols which may be used include those prepared by reacting glycols such as diethylene glycol, triethylene glycol or hexanediol with formaldehyde. Suitablepolyacetals may also be prepared by polymerising cyclic acetals. Suitable polyolefin polyols include hydroxy-terminated butadiene homo- and copolymers and suitable polysiloxane polyols include polydimethylsiloxane diols and triols. The number average equivalent weight of the high molecular weight polyols preferably is 500-8000 and most preferably 750-5000; the average nominal hydroxyl functionality preferably is 2-6 and more preferably 2-4. As said at least 10% by weight of the high molecular weight polyol used should be a polyol according to the present invention; preferably this amount is at least 25% by weight. The chain-extending and cross-linking agents which optionally may be used in preparing such foams may be selected from amines and polyols containing 2-8 and preferably 2-4 amine and/or hydroxy groups like ethanolamine, diethanolamine, triethanolamine, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, glycerol, trimethylolpropane, pentaerithritol, sorbitol, sucrose, polyethylene glycol having an equivalent weight of less than 500, toluene diamine, diethyl toluene diamine, cyclohexane diamine, phenyl diamine, diphenylmethane diamine, an alkylated diphenylmethane diamine and ethylene diamine. The amount of chain-extending and cross-linking agents is, if applied, up to 25 and preferably up to 10 parts by weight per 100 parts by weight of the high molecular weight polyol. The blowing agent may be selected from physical blowing agents like chlorofluorocarbons, hydrogen chlorofluorocarbons, hydrogen fluorocarbons and preferably from chemical blowing agents, especially those which lead to CO liberation when reacted with the polyisocyanate under foam forming conditions. Most preferably water is used as blowing agent; if desirable an inert gas like CO 2 , air or N 2 may be used together with the water. The amount of water may range from 2-20 preferably from 2-15 parts by weight per 100 parts by weight of isocyanate-reactive compound having a number average equivalent weight of 500 or more. The auxiliaries and additives which amongst others may be used are formation of urea and urethane enhancing catalysts like tertiary amines, imidazoles and tin compounds, surfactants, stabilisers, flame retardants, fillers and anti-oxidants. They may be premixed with the isocyanate-reactive materials before these materials are reacted with the polyisocyanate in order to prepare the foams. The present invention is further concerned with isocyanate terminated prepolymers obtained by reacting an excessive amount of a polyisocyanate and a polyol composition comprising at least 10% by weight and preferably at least 25% by weight of a polyol according to the present invention. As polyisocyanate and polyol those may be used which have been mentioned before. The NCO content of the prepolymer may range from 2-40% by weight. If MDI or polymeric MDI is used as the polyisocyanate the NCO content preferably is 5-30% by weight. The prepolymers are made by combining and mixing the polyisocyanate and the polyol and allowing them to react at a temperature of 60-100°C; a catalyst may be used but often is not necessary. The relative amount of polyisocyanate and polyol depends on the kind of polyisocyanate and polyol used and the desired NCO content; for those skilled in the art it is routine to determine these relative 5 amounts. The flexible foams according to the present invention in general will have a density of 15-80 kg/m 3 and may be used as cushioning material, in furniture seating, car-seats and mattresses for instance. The invention is further illustrated by means of the following examples. π Example 1 2038 g of glycerol and an aqueous KOH solution (439.4 g/ 450 g KOH/water) were charged to a reactor which was flushed with nitrogen, heated to 120°C and dehydrated till the water content was 0.02% by weight. The reactor was cooled to 1 10°C and 8110 g of 1 ,2-butylene oxide was added starting from vacuum in 70 5 minutes. The batch was allowed to react for 2 hours while maintaining the temperature, at 110°C. The 8060 g of polyol (intermediate 1) was discharged. To the remainder was added 8000g of 1,2-butylene oxide starting from vacuum in 70 minutes. The batch was allowed to react for 4 1/2 hours while maintaining the temperature at 110°C. Then 7744 g of polyol was discharged (intermediate 2). 0 To the remainder 6240 g of 1,2-butylene oxide was added at 110°C starting from vacuum in 70 minutes. The batch was allowed to react for 7 1/2 hours while maintaining the temperature at 110°C and vacuum stripped at 120°C for 2 hours. Then the reactor was pressurised with N 2 to 2 bar abs. and 1571 g of ethylene oxide was added in 45 minutes at 120°C. The batch was allowed to react for 1 5 hour and vacuum stripped for 1/2 hour while maintaining the temperature at 120°C. Then the batch was cooled to 85°C, neutralized with an aqueous adipic acid solution (25.3 g / 250 g adipic acid/water) and dehydrated for 4 1/2 hours at 120°C under vacuum; to the batch 1% by weight of magnesium silicate was added followed by filtration in 1 hour at 120°C. The polyol so obtained (polyol 1) was cooled to ambient conditions. It has the physical properties given in Table 1. 5 Example 2 3080g of Intermediate 2, obtained in example 1, was added to a reactor which was flushed three times with N 2 and heated to 110°C. 5424 g of 1,2-butylene oxide was added starting from vacuum in 1 hour and allowed to react for 6 1/2 hours while maintaining the temperature at 110°C, followed by vacuum stripping at 10 120°C for 1 hour. Then the reactor was pressurised with N 2 to 2 bar abs and 1509 g of ethylene oxide was added in 60 minutes at 120°C. The batch was allowed to react for 1 hour and vacuum stipped for 1/2 hour while maintaining the temperature at 120°C. Then the batch was cooled to 85°C, neutralised with an aqueous adipic 15 acid solution (32 g/ 250 adipic acid water) and dehydrated for 6 hours at 120°C under vacuum, followed by filtration in 1 hour at 120°C. The polyol so obtained (polyol 2) was cooled to ambient conditions. It has the physical properties given in Table 1. Example 3 20 2945 g of Intermediate 2, obtained in example 1 was added to a reactor which was flushed three times with N 2 and heated to 110°C. 5185 g of 1,2-butylene oxide was added starting from vacuum in 1 hour and allowed to react for 7 hours while maintaining the temperature at 110°C, followed by vacuum stripping at 120°C for 1 hour. 25 Then the reactor was pressurised with N 2 to 2 bar abs and 1970 g of ethylene oxide was added in 90 minutes at 120°C. The batch was allowed to react for 3 hours and vacuum stipped for 1/2 hour while maintaining the temperature at 120°C. Then the batch was cooled to 85°C, neutralised with an aqueous adipic acid solution (28 g/ 250 g adipic acid/water) and dehydrated for 6 hours at 120°C under vacuum, followed by filtration in 1 hour at 120°C. The polyol so obtained (polyol 3) was cooled to ambient conditions. It has the physical properties given in Table 1. TABLE 1 * = comparative, commercial polyol made from glycerol, propylene oxide and ethylene oxide (all tipped) having a molecular weight of 6000. Example 4 Prepolymers were made by reacting polyols 1-4 and 4,4'-diphenylmethane diisocyanate containing 10% by weight of the 2,4'-isomer in a relative amount of 75/25 w/w. The polyols and polyisocyanate were preheated at 50°C and the reaction was conducted for 3.5 hours at 85°C. The prepolymers had the following properties: * = comparative TABLE 2 It is to be noted that the viscosity of prepolymers 1-3 is similar to or lower than that of prepolymer 4, while for the polyols this is not the case (see Table 1). Example 5 To prepolymers 2 and 4* was added an amount of 4,4'-diphenylmethane diisocyanate containing 20% by weight of the 2,4'-isomer in order to prepare prepolymers 5 and 6* both having an NCO content of 12% by weight. The prepolymers both had a viscosity of 1300 mPas. *= comparative Example 6 Flexible polyurethane foams were made by combining the following polyisocyanate prepolymer and polyisocyanates and polyol compositions (Table 3 - the amounts are in parts by weight = pbw), all preconditioned at 45°C, in a plastic cup under vigorous stirring (3500 φm) for 6 seconds. The mix was poured into a cylindrical metal mould with diameter 195 mm in order to prepare free-rise foam and to measure reactivity. A similar foaming experiment was repeated by pouring the mix into an aluminium square mould (40x40x10 cm) which was heated at 45 °C. After 6 minutes the foams were demoulded, stored for 7 days at room temperature and subjected to physical testing (Table 4). TABLE 3 Polyisocyanate 1 : A prepolymer having an NCO content of 27.9% by weight, prepared by reacting 61.6 pbw of 4,4'-MDI containing 30% by weight of 2,4-MDI with 13.4 pbw of a glycerol initialized polyoxyethylene polyoxypropylene polyol (polyol 5) having a molecular weight of 4000 and an oxyethylene content of 75% by weight (random) and adding to this reaction product 25 pbw of a polymeric MDI (polyisocyanate 2) having an NCO content of 30.7% by weight and a diisocyanate content of 39% by weight. Polyisocyanate 2 : The above polymeric MDI Polyisocyanate 3 : The reaction product of polyisocyanate 2 and polyol 5 (above) in a weight ratio of 98:2. The NCO value was 30% by weight. Polyol 5 : The above polyol 5. Polyol 6 : A dipropylene glycol initiated polyoxyethylene polyoxypropylene polyol having an OH value of 30 mg KOH g and an oxyethylene content of 16% by weight (tipped). Polyol 7 : A sorbitol initiated polyoxyethylene polyol having an OH value of 190 mg KOH/g. D33LV : Dabco ™ catalyst from Air Products D8154 : Tegostab™ surfactant from Goldschmidt Al : Niax ™ catalyst from Witco DMEA : dimemylethanolamine DMI : 1 ,2-dimethylimidazole TABLE 4 Foam formulations 2,4 and 6 are according to the present invention, using a polyol or prepolymer containing BOR. Formulations 1, 3 and 5 are comparative examples using polyols and prepolymers containing POR instead of BOR. The 5 foams according to the invention exhibit improved resilience, creep resistance, dynamic fatigue and compression set while density, hardness and tensile properties are hardly affected. The polyols according to the present invention have a lower level of unsaturation and show an improved phase separation in polyurethane formulations, which o enhances the quality of the foam and broadens the accessible density/hardness range. Example 7 In a similar way as described in the previous examples a glycerol initiated polyol was made having an OH value of 27 mg KOH/g by allowing a 50/50 w/w mixture of propylene oxide and butylene oxide to react with the initiator, followed by reaction with an amount of ethylene oxide so as to obtain a polyol having an amount of oxyethylene groups of 14 % by weight (all tipped). 100 parts by weight of this polyol was reacted with a polymeric MDI having an NCO value of 32.6 and comprising about 25 % weight 2,4'-MDI at an index of 88 together with 0.7 pbw of D 8154, 0.1 pbw of Niax A„ 1 pbw of Tegostab™ B 4113 surfactant from Goldschmidt, 3.4 pbw of wter, 0.4 pbw of D 33 LV, 0.6 pbw of triethanol amine and 4.5 pbw of a polyol (OH value = 187 mg KOH/g; sucrose-based; 100 % EO). The foam obtained had a free rise density of 38 kg/m 3 and a hysteresis of 20 %.

Claims: CLAIMS 1. Polyether polyol having an equivalent weight of 500-10000, an average nominal hydroxyl functionality of 2-8 and having per polymer chain an AOR block and an EOR block wherein the AOR block contains BOR and optionally POR and the amount of the AOR block is 70-95% by weight and the amount of the EOR blocks is 5-30% by weight calculated on the weight of the AOR blocks and the EOR blocks and wherein the EOR blocks are at the end of the polymer chains. 2. Polyol according to claim 1 wherein the equivalent weight is 500-8000 and the nominal functionality is 3-6. 3. Polyol according to claim 2 wherein the equivalent weight is 750-5000 and the nominal functionality is 3-4. 4. Polyol according to claims 1-3 wherein the amount of AOR blocks is 75-90% by weight and the amount of EOR blocks is 10-25% by weight. 5. Polyol according to claims 1-4 wherein the AOR blocks contain 0-95% by weight of POR. 6. Polyol according to claims 1-5 wherein the AOR blocks contain 20-80% by weight of POR. 7. Polyol according to claims 1-6 wherein the oxybutylene is for at least 50% by weight derived from 1 ,2-butylene oxide. 8. Polyol accroding to claims 1-7 wherein the oxybutylene is derived from 1 ,2-butylene oxide. 9. Process for preparing polyether polyol according to claims 1-8 by allowing a compound having 2-8 hydrogen atoms which are reactive with alkylene oxides to react with BO and optionally with PO and by allowing the product so obtained to 5 react with EO, wherein, the type of BO, the amounts of BO, optionally PO, and EO are such that the ranges as to equivalent weight, amounts of AOR and EOR blocks, the amount of POR in the AOR block and the type of BOR are as in claims 1-8. 10. The use of the polyols according to claims 1-8 for preparing polyurethane 10 foams. 11. Process for preparing a flexible polyurethane foam by reacting a polyisocyanate and an isocyanate-reactive composition comprising a polyol according to claims 1-8 in an amount of at least 10% by weight and using a blowing agent. 15 12. Process according to claim 12 wherein the amount is at least 25% by weight. 13. Process according to claims 11-12 wherein the blowing agent is water or water together with an inert gas selected from CO 2 , air and N 2 14. Process according to claims 11-13 wherin the amount of water is 2-20 parts by weight per 100 parts by weight of isocyanate-reactive compounds having an 20 equivalent weight of 500 or more. 15. Isocyanate terminated prepolymer obtained by reacting an excessive amount of polyisocyanate and a polyol composition comprising at least 10% by weight of a polyol according to claims 1-8. 16. Prepolymer according to claim 15 wherein the amount is at least 25% by weight. 17. Polyols obtainable according to the process of claim 9. 18. Polyol mixture comprising a polyol according to claims 1-8.

Inventors: CHAFFANJON PIERRE GILBERT HENR, PARFONDRY ALAIN, RAMAEL DIRK RENE LEONIE, CHAFFANJON, PIERRE, GILBERT, HENRI, JEAN, PARFONDRY, ALAIN, RAMAEL, DIRK, RENE, LEONIE
Applicants: ICI PLC, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1998
Main classification: C08G18
IPC codes: C08G18, C08G65