MXPA99007041A - New isocyanate-terminated prepolymers - Google Patents

Abstract

Novel isocyanate-terminated prepolymers and a process for making flexible polyurethane foams thereof. The prepolymers are made from polyether polyols having a high equivalent weight.

Description

NEW PRE-POLYMERS FINISHED IN ISOCYANATE DESCRIPTION OF THE INVENTION The present invention relates to new isocyanate-terminated prepolymers made of polyols having a high molecular weight and to the preparation of flexible polyurethane foams using such prepolymers. US 4,687,851 describes the preparation of polyurethane and / or polyurea polymers which. they are the reaction product of a reaction mixture comprising a polyol and a polyether polyol having an equivalent weight of at least 2000 and a level of unsaturation of less than 0.1% by weight. The purpose of this patent is to use high molecular weight polyols that have a low level of unsaturation that leads to flexible and flexible materials that have high elasticity, excellent tensile properties and compression set and a low temperature. of glass transition. The use of polyols that have a moderate equivalent weight (250-2000) have also been described; no special directions are given as for the use of such polyols specially separated with water.

All the examples relate to the preparation of solid elastomers. EP-394487 describes the use of high molecular weight polyether polyols having low unsaturation levels to make flexible foams having a low resonant frequency; preferably such polyols are used as the matrix for polyols so-called dispersed polymers. EP-443614 describes an improvement of EP-394487: it becomes sometimes hard for satisfactory starting materials in the preparation of a polyurethane foam due to the high viscosity of the polyols; to overcome this a viscosity that reduces the compound having an unsaturated polymerizable addition group is added in EP-443614, such as for example a compound of the methacrylate type, the vinylether type compound, a compound of the vinylester type, a compound of the alkyl ether type and a compound of the alkyl ester type. EP-422811 discloses the use of a polyisocyanate to prepare flexible polyurethane foams which have good elasticity and elongation properties; Social media is a prepolymer made of polyether polyols that have a high molecular weight. The NCO content of the prepolymer used is preferably high, which medium is limited in the amount of polyol in the polymers. GB 2296499 discloses the use of the prepolymer composition to produce molded articles my cellular fiber is. Although a wide range of polyols has been described for use in the composition of the prepolymer and the side component of resin, there is no special attention given to the use of polyols having a high molecular weight and certainly not to the use of such polyols in the preparation of flexible foams blown in water, the quantities of water used are low and the products obtained are high density microcell turners. EP 420273 relates to a process for making flexible foams using prepolymer compositions to make soft foams with a low Shore A hardness. No attention is given to the problems encountered when polyols with high molecular weight were used. EP-485953 is related to improve the elongation of flexible foams by the use of prepolymers made of polyols having a high molecular weight and a relatively high content of oxy fuel. WO 95/18163 relates to the preparation of rigid polyurethane foams using a prepolymer made by the reaction of polymeric MDl and a polyol having a molecular weight of at least 2000 and a highly high content of oxyethylene glycol. . EP-392788 relates to isocyanate-terminated prepolymers and their use in the manufacture of flexible foams. The prepolymers used have been made of polyols having relatively low molecular weight and in the preparation of a flexible polyurethane foam a side resin is used which does not contain polyol. It is known that polyols having a high molecular weight have a higher viscosity than polyols having a low molecular weight. EP-443614 recognizes that such high viscosity can lead to processing difficulties; these difficulties are diminished by the addition of a compound of increased viscosity.

EP-111121, EP-344551, W095 / 34589, WO95 / 34590 and W095 / 34591 further describe the use of prepolymers to prepare flexible foams; no special directions are given as the use of polyols that have a high molecular weight. When high amounts of high molecular weight polyols are used, the processing difficulties must be more pronounced. It was found that in the preparation of MDl (diphenylmethane diisocyanate) based, the flexible polyurethane foams of blown water, the viscosity of the water mixture and the polyol increase in the same way as the viscosity of the polyol, with the increase of molecular weight. Surprisingly it has been found that the viscosity of a prepolymer does not give rise to a viscosity in proportion to the viscosity of a polyol used; the viscosity of the prepolymer containing a high amount of a polyol having a high molecular weight only rose slightly more than the viscosity of a prepolymer made of a high amount of a polyol having a low molecular weight despite the fact that the viscosity of these polyols has remarkably differed. The present invention therefore relates to such prepolymer compositions and to a process for making flexible foams by reacting such prepolymer compositions with a relative isocyanate compound or composition using water as a blowing agent. Processing is much improved, even in the absence of viscously reduced agents. The foams show very good properties, a high ball bounce and a low compression set. Accordingly, the present invention relates to an isocyanate-terminated prepolymer composition comprising 1) a urethane containing adduction of a diphenylmethane diisocyanate optionally containing oligomers thereof having an isocyanate functionally greater than 2 and a potassium hydroxide. lpo 1 i é ter 1) having an equivalent weight of 2200-10000, an oxyethylene content of 5-30% by weight and a functionally nominal hydroxyl average of 2-4, the amount of polyether portions being 35-70 % by weight and 2) 2 to 15% by weight of unreacted oligomers of diphenylmethane diisocyanates, such oligomers have an isocyanate functionally of less than 3, and / or 1 to 25% by weight of diisocyanate-of toluene, all amounts being calculated in the total weight of the composition, the composition has an NCO content. 8-22% by weight when no toluene diisocyanate is present and an NCO content of 8.5-26% by weight when the toluene diisocyanate is present. In addition, the present invention relates to a process for preparing a flexible polyurethane foam by reacting the composition of the isocyanate-terminated prepolymer with a polyol 1 (2) having an equivalent weight from 1000 to less. of 2200 and a nominal functionality of 2-4 and with water optionally using chain extenders, crosslinkers, auxiliaries and additives. The above prepolymer composition according to the invention preferably has an NCO content of 10-20% by weight when no toluene diisocyanate is present and 11-24% by weight when the toluene diisocyanate is present, and a viscosity of more than 4500 mPa.sec at 25 ° C (Brookfield). The equivalent weight of the polyol 1) is preferably 2500-8000 and more preferably 3000-7000; this functionally nominal average is more preferable than 3.

In the context of the present invention, the following terms have the following meaning: 1) isocyanate index or NCO index or index: the ratio of the NCO groups on the reactive isocyanate hydrogen atoms present in a formulation, give as a percentage : [NCO] xlOO (%) [active hydrogen] In other words the NCO index expresses the percentage of isocyanate currently used in a formulation with respect to the amount of isocyanate theoretically required to react with the amount of reactive isocyanate hydrogen used in the formulation. It should be noted that the isocyanate index as used herein is considered from the point of view of the current foaming process that envelops. the isocyanate ingredient and the ingredients. of isocyanate reactants. Any isocyanate groups consumed in a preliminary step to produce modified polyisocyanates (including prepolymers) or any active hydrogens consumed in a preliminary step (for example reacting with isocyanate to produce modified polyols or polyamines) are not taken into account in the calculation of isocyanate index. Only the free isocyanate groups and the free reactive isocyanate hydrogens (including those of the water) present in the current foaming step are taken into account. 2) The term "reactive isocyanate hydrogen atoms" as used herein for the purpose of calculating the isocyanate index referred to the total of the hydroxyl active hydrogen atoms and amine groups present in the reactive compositions this means that for the purpose of calculating the isocyanate index to the current foaming process a hydroxyl group is considered to comprise a reactive hydrogen, a primary amine group is considered to comprise a reactive hydrogen and a water molecule is considered to comprise two active hydrogens. 3) Reaction System: a combination of components in which the isocyanate components are taken in one or more separate containers of the reactive isocyanate components. 4) The term "polyurethane foam" as used herein refers to cellular products as obtained by reaction of the polyisocyanates with reactive isocyanate hydrogen containing the compounds, using foaming agents, and in particular include products Cells obtained with water as reactive foaming agents (which involve a reaction of water with isocyanate groups that produce urea and carbon dioxide bonds and which produce foams of low-grade foam) and with polyols, aminoalcaho 1 is and / or polyamines composed of reactive isocyanate. 5) The term "functionally nominal" "average hydroxyl" is used herein to indicate the functionally average number (number of hydroxyl groups per molecule) of the polyol or polyol composition on the assumption that this is the functionally average number (number of atoms of active hydrogen per molecule) of the initiator or initiators, used in its preparation although in practice it is often a little less due to some terminal unsaturation. 6) The word "average" refers to the average number unless indicated otherwise. If the words functionally, equivalent weight or molecular weight are used without the preceding words "average" or "average number" then however the value of the average number is significant. 7) The "polyether portions" refer to the part of the polyol which is remaining in the urethane which contains an adduct after this polyol and po si ly or which have a reaction to form such an adduct. The urethane containing an adduct in the composition of the prepolymer according to the invention is prepared by mixing an excessive amount of the polar polymer with the polyol 1) and allowing the mixture to react. Such a reaction is allowed to take place at 60-100 ° C and in general the use of catalysis is not necessary. The relative amount of the polyisocyanate and polyol depends on the desired NCO value, the NCO value of the polyethylene oxide and the OH value of the polyol used and can be easily calculated by those skilled in the art. The polyisocyanate used to react with the polyol 1) can be selected from diphenylmethane diisocyanate (MDl) and MDl in the mixture with its oligomers having an isocyanate functionally of at least 3 (in the art known as crude or MDl polymer). ). The diisocinato diphenylmethane (MDl) used to be the prepolymer can be selected from pure 4,4'-MDI and isomeric mixtures of 4,4 '-MDl and 2,4'-MDI and less than 10% by weight of 2, 2 '-MDl and modified variants thereof containing carbodiimide, uretonimine, isocyanurin, urethane, allophanate, urea or biuret groups. More preferably they are pure 4,4'-MDI, isomeric mixtures with 2,2'-MDI preferably containing 5-50% and more preferably 5-35% by weight of 2,4 '-MDl and uretonimine and / or modified carbodiimide MDl having an NCO content of at least 25% by weight and MDl modified urethane obtained by the excess MDl reaction and a polyol, which have a functionally nominal hydroxyl average of 2-6 and a molecular weight of the average number of 60- 999 and having an NCO content of at least 25% by weight. As indicated, mixtures of MDl with its oligomers have a functionally isocyanate of at least 3 which can also be used to prepare the urethane containing adducts. Such mixtures are known in the art as polymeric MDl or crude MDl and more generally as po 1 isomers of po 1 ime ti 1 enpo 1 i feni 1 ene that are made by the phosgenation of a mixture of polyamines obtained by condensation of aniline and formaldehyde acid. The manufacture of both of the polyamine mixtures and the mixtures of polyamines is well known. The condensation of aniline with formaldehyde in the present of strong acids such as hydrochloric acid give a reaction of the product containing diamino diphenylmethane together with polyamine of polyphenylene polyphenylene of high functionality, the precise composition depends in a known way on the deinean animal / fornal relatiip. The polyisocyanates are made by the foisgenation of the polyamine mixtures and the various proportiof diamines, triamines and high polyamines give rise to the related proportiof diisocyanates, polyisocyanates and high polyisocyanates. The relative proportiof diisocyanates, triisocyanate and. High polyisocyanates in the diisocyanate diphenylmethane compositidetermine the functional average of the compositi which is the average number of isocyanate groups per molecule. By the variation of the proportiof the starting materials, the functional average of the polyisocyanate compositican be varied from a little more than 2 to 3 or even higher. In practice, however, the average number of functionally preferred isocyanate averaged from 2.35 to 2.9. The NCO value of these polymeric MDl is at least 30% by weight and more than 33% by weight. Such compositicontain from 20 to 80 and preferably 30-70% by weight of diphenylmethane diisocyanate, the remainder being polyisocyanates of isopo- nate po 1 ime ti 1 enpo 1 if eni 1 ene, functionally at least 3 together with by-products formed in the manufacture of such polyisocyanates by phosgenation. These products being liquid, are convenient to be used according to the present invention. The MDl optionally contains oligomers having an isocyanate functionally of 3 or more preferably containing 5-50 and more preferably 5-35% by weight of 2,4 '-MDl; this is maintained by good storage stability of prepolymer and low density foams having good foam stability. The polyol ether 1) for preparing the adduct-containing urethane can be selected from the products obtained by the polymerization of ethylene oxide and another cyclic oxide, such as propylene oxide, butylene oxide or tetrahydrofuran in the presence, wherever necessary, of initiators pol i functional is. Suitably, the initiator compounds contain a plurality of active hydrogen atoms and include water, butanediol-, ethylene glycol, propylene glycol, di et ilengl icol, trie ti lengl icol, dipropi lengli col, ethanolamine, di e ta or lamina, triethanolamine, to luendi amine, diethylene oxide, phenylamide, di phenyl e tandiamine, eti lendiamine, cyclohexandia ina, cyclohexanedime t anol, resorcinol, bisphenol A, glycerol, trimethe lolpr opane, 1,2,6-hexantriol and p r ent r aeritri ol. Mixtures of initiators and / or other cyclic oxides can be used. Especially useful, the polyether polyols include diols, polyoxyethylene-polyoxypropyl 1-ene and triols obtained by the simultaneous and / or sequential addition of the ethylene oxide and propylene oxide to di- or tri-functional initiators is as fully described in US Pat. previous technique. The random copolymers, block copolymers and block copolymers that contain ethylene oxide and propylene oxide have an oxyethylene content of 5-30% by weight (all based on the total weight of the oxya 1 qui units). 1 ene) are preferred, in particular those having at least part and most preferably all of the oxyethylene groups at the end of the polymer chain, ie, so-called dotted EO polyols. The mixture of diols and triols can also be used. After the preparation of the urethane containing additional MDl adducts can be added. After the preparation of the urethane containing polymeric adducts or crude MDl it is added so that upon obtaining an isocyanate-terminated prepolymer composition according to the present invention, it contains from 2 to 15% by weight of the unreacted oligomers of MDl having an isocyanate functionality of 3 or more, calculated in the total prepolymer composition. The polymeric or crude MDl that is used is selected from those described in the foregoing. The amount of agr uented is such that the amount of unreacted or unreacted oligomers of unreacted 1-ene-1-enpo-1-ene oligomers has an isociety functionality of at least 3 is 2-15. % by weight calculated in the composition of the total finished isocyanate prepolymer. In addition to or in place of the addition of the crude or polymeric toluene diisocyanate MDl it can be added to the urethane containing adducts that the toluene diisocyanate can be 2,4-toluene diisocyanate, 2,6-toluene diisocyanate or mixtures thereof, in an amount of 1 to 25% and preferably 5-20% by weight calculated in the prepolymer composition including the addition of toluene diisocyanate. It is understood that within the limits of the isocyanate terminated prepolymer composition as the amount of the polyol 1) as the amount of the unreacted oligomers of MDl having a functionality of at least 3 and thus the amount of diisocyanate of toluene is such that the prepolymer compositions can be made having NCO content outside the ranges indicated; such compositions however do not form part of the present invention. The prepolymer compositions according to the present invention are used for flexible polyurethane foams prepared by reacting these compositions with polyether polyols having an equivalent weight from 1000 to less than 2200 and a nominal functionality from 2 to 4 and with water these Polyether polyols include products obtained by the polymerization of a cyclic oxide for example ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran in the presence, when necessary, of initiators po i i operales s. Suitable initiator compounds contain a plurality of active hydrogen atoms and include water, butanediol, ethyl glycol 1, propylene glycol, ethanolamine, di-1-amine, triethanolamine, to 1-endi amine, diethyl toluene amine, cyclohexanediamine, cyclohexandimethanol. , glycerol, trimethylolpropane and 1, 2, 6-hexan tri-ol and the other initiators mentioned above Cyclic initiator and / or mixtures mixtures can be used Polyether polyols especially include diols of po 1 io ipropi 1 Enol and triols and diols of po 1ioxie ti 1 in po 1 and oxypropylene and trioles obtainable by the simultaneous addition or sequence] of -ethylene and propylene oxides for functional di- or tri- initiators is as fully described In the prior art, random copolymers have oxyethylene contents of 10-80%, block copolymers having oxyethylene contents above 50% based on in the total weight of the oxyalkylene units can be mentioned, in particular those having at least part of the oxyethylene groups at the end of the polymer chain. The mixtures of the diols and triols can be used in particular. Other polyols that can be used as polyol 2) comprise dispersions or solutions of addition or condensation of polymers in polyols of the types described in the above. Such modified polyols, often referred to as "polyol polymer" are fully described in the prior art and include products obtained by the in situ polymerization of one or more vinyl monomers, for example styrene and / or acrylonitrile, in polymeric polyols, for example polyols of polyether or by the in situ ratio between a po I ii so as to produce an amino- and / or functional hydroxyl compound, such as triethanolamine in a polymeric polyol. The polyols of po 1 i exi to the one containing 5 to 50% by weight of dispersible polymers are particularly useful. Particle sizes of dispersed polymers less than 50 microns are preferred. More preferably, the polyolenoxy polyolioxypropylene polyols having an equivalent weight of 1100-2100, a nominal functionality of 2-3 and an ethylene oxide content of 5-30% by weight, preferably having the oxyethylene groups at the end of the polymer chain. The amount of polyol having an equivalent weight from 1000 to less than 2200 preferably is 20-90 and more preferably 35-90 parts by weight per 100 parts by weight of the prepolymer composition. The foam forming the reaction of the prepolymer composition, the polyol and the water is conducted at an isocyanate index of 40-120, preferably 50-110. The amount of water used can vary from 2 to 8 parts by weight per 100 parts. by weight of the prepolymer composition. If desired, additional blowing agents can be used, in particular inert gases such as CO2 and N2. Optionally extending chains and reticulating agents can be used having an equivalent weight of less than 1000, such as those selected from amines and polyols containing 2-8 and preferably 2-4 amine and / or hydroxy groups such as ethanolamine, di et al. 1-amine, triethanolamine, 1-glycol 1, 1-diethyl 1, tri-1 and 1-glycol 1, propylene glycol, dipropylene glycol 1, butanediol, glycerol, triamotene, propane tr i to 1, sorbitol, sucrose, po 1 ie t, engl icol and other polyethylene polyols having one of the other initiators as initiators, toluenediamine, di et il t oluendiamine, exan-diamine cyclo, f eni 1 di amine , di fylmethylamine, di-alkylated phenylmethanedi amine, and 1-endiamine. The amount of chain that spreads and the crosslinking agents, if applicable, above 25 and preferably above 10 parts by weight per 100 parts by weight of the prepolymer composition. The auxiliaries and additives can optionally be used as urea and urethane formation by increasing the catalysis as tertiary amines and tin compounds, surfactants, stabilizers, retarders, fillers and anti oxidants. Flexible polyurethane foams are prepared by combining and mixing ingredients and allow the mixing of foam. Preferably the isocyanate reactive ingredients or the auxiliaries and additives are premixed and subsequently combined in the master mix with the prepolymer composition. The ingredients of the prepolymer composition can be fed to the master mix independently of each, if desired. The process can be used to make a block storage or molded flexible foams. The foams in general have a density of 15-80 kg / m3 and can be used as cushioning material in furniture, car seats and cocks. The present invention is illustrated by the following examples.

The following polyols of 1-oxo-propyl-1-enpo-1-ene-1-ene are used to prepare finished isocyanate polymers: The prepolymers are made from these polyols, the prepolymers have an NCO value of approximately 7% by weight to allow these polyols to react with diisocyanate of 4,4'-di fimethat contain 10% by weight of 2, 4'- isomer (the weight ratio of the polyol to po 1 i is isocyanate was about 75/25) at a temperature of about 85 ° C for 2.5 hours using 10 wt% t ioni c ruro (calculated in DMI) . The prepolymers are then made having an NCO content of 12% by weight by the addition of an appropriate amount of 4,4'-diisocyanate diisocyanate containing 20% by weight of the 2,4'-isomer.

E j e p o 2 Flexible molded polyurethane foams are made of these prepolymers that have an NCO content of 12% by weight. In a number of polymeric MDl experiments (NCO = 30.7% by weight, functionally isocyanate = 2.7, diisocyanate content = 38% by weight, the remainder being polyisocyanates having an isocyanate functionality of 3 or more and having a content of 2, 4'-DMI = 2% by weight) was premixed with the prepolymer; in another number of experiments the polymeric MDl and TDI (2.4 / 2.6 p / p) were premixed with the prepolymer. 100 parts by weight of these prepolymer compositions were mixed with a polyol composition and poured into a mold and allowed the reaction. The polyol composition comprises 65 parts by weight (ppp) of 1,2 or 3 polyol; 0.5 ppp of B4113 a silicone surfactant from Goldschmidt; 0, .5 ppp of X8154, an Air Products catalyst; 0.05 ppp of Niax Al, a catalyst of Union Carbide; 3 ppp triethanolamine; 3. water ppp; and 3 ppp of ethoxylated sorbitol having a molecular weight of about 1200. Additional details are given in the following table. In addition, the demolding properties of the foams are measured; the results are in the following table also.

^ Comparative experiment Process + media: easy to mix: 'soft product spread in the mold without problem related to the flow of the reaction material. Processing - means: - difficulty to mix: sign of cleaning of the density of flow. TMS standard Toyota method.

Claims (2)

1. CLAIMS 1. The composition of the isocyanate-terminated prepolymer comprising I) a urethane containing adduct of diphenylmethane diisocyanate optionally containing oligomers having an isocyanate functionality of more than 2 and of a po Iio 1 i e t er I), which it has an equivalent weight of 2200-10000, an oxyethylene content of 5-30% by weight and a nominal hydroxyl functionality of 2-4, the amount of the polyether portions being 35-70% by weight and II) 2 a 15% by weight of unreacted oligomers of diphenylmethane diisocyanate, the oligomers; have an isocyanate functionality of at least 3, and / or 1 to 25% by weight of toluene diisocyanate, all amounts being calculated in the total weight of the composition, the composition having an NCO content of 8-22% by weight when no toluene diisocyanate is present and an NCO content of 8.5-26% by weight when the toluene diisocyanate is present.
2. 2. The composition according to claim 1, wherein the equivalent weight is 2500-8000. 8. The process according to claims 5-7, wherein the amount of water is 2-8 parts by weight per 100 parts by weight of the prepolymer composition and wherein the isocyanate number is 50-110.