Phosphate-modified polyisocyanate polyaddition polyol

Abstract

Polyisocyanate polyaddition (PIPA) dispersions are made using low equivalent weight polyols that contain phosphate groups. The phosphate group-containing polyol is combined with a base polyol, another low equivalent weight polyol that does not contain phosphate groups, and a polyisocyanate to form an agitated mixture that reacts to form the dispersion. The dispersion imparts excellent flammability performance to polyurethane foams made, often enabling the foam to pass the stringent requirements of the Italian UNI 9175:2010 Class 1M flammability standard.

Description

[0001] PHOSPHATE-MODIEIED POLYISOCYANATE POLY ADDITION POLYOL

[0002] This invention relates to a method for making dispersions of polyisocyanate polyaddition particles in a polyol, and to polyurethane foam made using those dispersions.

[0003] Polyurethane foam is frequently used in furniture and bedding applications. Many jurisdictions require those foams or articles containing those foams to pass stringent flammability tests. An example of such a test is the Italian UNI 9175:2010 Class IM flammability standard. In this test, a flame is applied at the junction of two foam pieces arranged as seat and back cushions of a chair. The flame is applied for 140 seconds. The foam pieces must self-extinguish within a certain time to obtain the Class IM rating. This rating can be difficult to pass for polyurethane foam.

[0004] One way of improving the flame performance of polyurethane foam is to incorporate phosphorus into the foam structure through the use of phosphorus-containing polyols during foam manufacture. An example of such an approach is described in US Patent No. 9,550,856. As described there, phosphorus-containing polyols are used to produce dispersions of polyisocyanate polyaddition (PIPA) particles in a base polyol (so-called “PIPA Polyols”). The phosphorus- containing polyols react with polyisocyanates to produce PIPA particles that contain phosphorus. The dispersion, when used to produce a polyurethane foam, both increases load-bearing and provides improvement on foam flammability testing. However, further improvement in flammability testing results are wanted as polyurethane foam made using the PIPA dispersions of US 9,550,856 often does not meet the UNI 9175:2010 Class IM standard.

[0005] The invention is in one aspect a process for preparing a dispersion of polyisocyanate polyaddition particles in a base polyether polyol, comprising forming an agitated mixture of i) a low equivalent weight polyol having a hydroxyl number of at least 700 mg KOH / g and which does not contain phosphate groups, ii) a phosphate group-containing polyol characterized in having at least two phosphate groups per molecule and at least two hydroxyl groups per molecule, each hydroxyl group being bonded to a carbon atom, and a number average molecular weight of 296 to 2000 g / mol, iii) one or more organic polyisocyanate compounds, and iv) a base polyether polyol having a hydroxyl number of at most 280 mg KOH / g and reacting the low equivalent weight polyol and the phosphate group-containing polyol with the one or more polyisocyanate compound(s) in the presence of the base polyether polyol to form the dispersion of polyisocyanate polyaddition particles in the base polycthcr polyol, wherein the weight ratio of i) : ii) is 2 to 4.

[0006] The dispersions are surprisingly effective in improving the performance of polyurethane foams on flammability testing. In particular, polyurethane foams made using the dispersions often meet the Class IM standard of UNI 9175:2010. Thus, in other aspects this invention is a dispersion of polyisocyanate polyaddition particles in a base polyether polyol made in accordance with the first aspect of the invention, and a polyurethane made by reacting the dispersion with a polyisocyanate.

[0007] Component i) is a low equivalent weight polyol having a hydroxyl number of at least 700 mg KOH / g, preferably at least 750 mg KOH / g, as measured according to ASTM D4274-2, and which does not contain phosphate groups. It preferably does not contain any phosphorus. It has 2 to 6, preferably 2 to 3, hydroxyl groups per molecule. It is preferred that it contains at least two primary hydroxyl groups (and optionally one or more secondary hydroxyl groups as well), and / or is an aminoalcohol. It preferably has low miscibility in the base polyether polyol such that, at the relative amounts used the process, the low equivalent weight polyol disperses in the base polyether polyol in the form of small droplets. Aminoalcohol compounds are preferred types. Specific examples of low equivalent weight polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propane diol, 1,2-propane diol, dipropylene glycol, tripropylene glycol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, erythritol, sucrose, sorbitol, diethanolamine, triethanolamine, triisopropanolamine, diisopropanolamine, and the like. Aminoalcohols such as diethanolamine and especially triethanolamine or a mixture of diethanolamine and triethanolamine are preferred; in particular embodiments component i) contains at least 50% by weight of triethanolamine, at least 50% by weight diethanolamine or at least 50% by weight of a mixture of diethanolamine and triethanolamine. Component i) compounds may contain, for example, 75 to 100% or 75 to 99.9% by weight triethanolamine.

[0008] Component ii) is a phosphate group-containing polyol characterized in having at least 2 phosphate groups per molecule and at least two hydroxyl groups per molecule, It may contain, for example, 2 to 16, 2 to 9 or 2 to 5 phosphate groups and may contain, for example, 2 to 6, 2 to 4 or 2 to 3 hydroxyl groups per molecule. The hydroxyl groups each are bonded to a carbon atom. It is preferred that each hydroxyl group is bonded to a different carbon atom. The phosphate group- containing polyol has a number average molecular weight of 296 to 2000 g / mol. Its number average molecular weight in some embodiments is 296 to 1000 g / mol, 350 to 1000 g / mol, 400 to 800 g / mol or 450 to 725 g / mol. Molecular weight is conveniently determined by size exclusion chromatography.

[0009] The phosphate group-containing polyol may have a hydroxyl number of 56 to 380 mg

[0010] KOH / g, 112 to 380 mg KOH / g, 112 to 320 mg KOH / g or 155 to 250 mg KOH / g, as measured according to ASTM D4274-21.

[0011] In specific embodiments, the phosphate group-containing polyol has the structure: wherein each R1is independently hydrocarbyl, each R2is independently alkylene or arylsubstituted alkylene and n is a number such that the phosphate group-containing polyol has a number average molecular weight of 296 to 2000 g / mol. Each R1may be independently alkyl having 1 to 4 carbon atoms, and each R2may be independently linear or branched alkylene having 2 to 4 carbon atoms. In some embodiments, each R1is ethyl and each R2is ethylene, n may be, for example, 1 to 15, 1 to 7, 2 to 5, 2 to 4 or 2.5 to 3.5. A particularly preferred phosphate group- containing polyol corresponds to the foregoing structure, in which each R1is ethyl, each R2is ethylene and n is 2-4, especially 2.5 to 3.5; such a material is available commercially as Exolit ™ OP550 from Clariant.

[0012] Applicant has found that the weight ratio of components i) and ii) has a significant effect on flame retardant properties of polyurethane foam made using the dispersion of the invention. This weight ratio should be at least 2 and not greater than 4.

[0013] Components i) and ii) together may constitute, for example, at least 2%, at least 5%, at least 8% or or at least 10% of the total weight of components i), ii), iii) and iv), and up to 20% or up to 17.5% of the total weight thereof.

[0014] Component iii) is an organic polyisocyanate. The organic polyisocyanate preferably has an isocyanate equivalent weight of up to 300 g / equi valent, more preferably up to 250 g / equivalent, still more preferably up to 175 g / equivalent and in some embodiments 580 to 175 g / equivalent, as measured according to ISO 14896 / 3. Examples of useful polyisocyanatcs for making the functionalized polyether include m-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6- diisocyanate, hexamethylene- 1,6-diisocyanate, tetramethylene- 1 ,4-diisocyanate, cyclohexane- 1,4-diisocyanate, hexahydrotoluene diisocyanate, naphthylene- 1,5-diisocyanate, 1,3- and / or 1,4- bis(isocyanatomethyl)cyclohexane (including cis- and / or trans isomers) methoxyphenyl-2,4- diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4’ -diisocyanate, hydrogenated diphenylmethane-4,4’-diisocyanate, hydrogenated diphenylmethane-2,4’ - diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'- dimethyl-4-4'-biphenyl diisocyanate, 3,3'-dimethyldiphenyl methane-4,4'-diisocyanate, 4, 4', 4"- triphenyl methane triisocyanate, a polymethylene polyphenylisocyanate (PMDI), toluene-2,4,6- triisocyanate and 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate. Preferably the polyisocyanate is diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, PMDI, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate or mixtures thereof. Diphenylmethane-4,4’- diisocyanate, diphenylmethane-2,4’ -diisocyanate and mixtures thereof are generically referred to as MDI, and all can be used. Toluene-2,4-diisocyanate, toluene-2,6-diisocyanate and mixtures thereof are generically referred to as TDI, and all can be used.

[0015] The polyisocyanate may constitute, for example, at least 2%, at least 5%, at least 8% or or at least 10% of the total weight of components i), ii), iii) and iv), and up to 20% or up to 17.5% of the total weight thereof. The weight ratio of component iii) to components i) and ii) combined may be, for example, 1:2 to 2:1, especially 1.5:1 to 1:1.5 or 1.25:1 to 1:1.25.

[0016] The base polyether polyol (component iv) has a nominal functionality of at least 2.0. By "nominal" functionality, it is meant the average number of oxy alkylatable hydrogens per molecule of the initiator(s) used in making the base polyether polyol. The nominal functionality preferably is at least 2.5 or at least 3.0. It may be as high as 6.0, but more preferably is no more than 4.0. The hydroxyl groups of the base polyether polyol may be primary or secondary hydroxyls, or some mixture of both.

[0017] The hydroxyl number of the base polyether polyol is at most 280 mg KOH / g, and may be as low as about 20 mg KOH / g, as measured according to ASTM 4274-16. A preferred hydroxyl number is 23 to 156 mg KOH / g, a more preferred hydroxyl number is 28 to 112 mg KOH / g and an especially preferred hydroxyl mumber is 40 to 65 mg KOH / g. If the base polyether polyol is a mixture of two or more separately made polyether polyols, each of the separately made polyols should have hydroxyl equivalent weights within these ranges.

[0018] The base polyether polyol preferably is a homopolymer of propylene oxide or copolymer of propylene oxide and ethylene oxide. A copolymer of propylene oxide and ethylene oxide may be a random and / or block copolymer that contains at most 40%, preferably at most 30% by weight oxyethylene units. A preferred base polyether polyol is a homopolymer of propylene oxide that is end-capped with 5 to 30%, by weight of the polyol, of oxyethylene groups. At least 50% or at least 70% of the hydroxyl groups of such a preferred base polyether polyol may be primary hydroxyl groups. In alternative embodiments, the base polyether polyol is a homopolymer of propylene oxide or a random copolymer of propylene oxide and ethylene oxide in which less than 50% of the hydroxyl groups are primary hydroxyl groups.

[0019] The base polyether polyol can be prepared by polymerizing the oxide or oxides in the presence of an initiator compound or mixture of initiator compounds that contain at least two oxyalkylatable hydrogen atoms. Hydroxyl groups, primary amine groups, secondary amine groups and thiol groups are examples of groups that contain oxyalkylatable hydrogen atoms. Primary amine groups each contain two oxyalkylatable hydrogens. Examples of initiator compounds are water, ethylene glycol, 1,2-propane diol, 1,3-propane diol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, cyclohexanedimethanol, methyl amine, ethyl amine glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, erythritol, sucrose, sorbitol, mannitol, diethanolamine, monoethanolamine, triethanolamine, ethylene diamine, toluene diamine, 1,2-propane diamine, and the like. Mixtures of two or more of the foregoing initiators can be used.

[0020] The base polyether polyol may also be a mixture of polyether polyols, each made separately, and each having a hydroxyl number as described above, which are then blended to form a mixture having an average functionality as described before.

[0021] The PIPA dispersion is prepared by forming an agitated mixture of components i), ii), iii) and iv), and any optional ingredients such as those indicated below, and then reacting components i), i) and iii) to form polyisocyanate polyaddition (PIPA) particles dispersed in the base polyether polyol. Some or all of the base polyether polyol may react to graft the PIPA particles to polyether polyol molecules. The order of addition of components i)-iv) is generally not critical, provided that the reaction of the low equivalent polyol and the phosphate group-containing polyol with the polyisocyanate occurs in the presence of the base polyether polyol and any optional ingredients (such as catalyst, stabilizer and seed dispersion) as may be present. It is often convenient to disperse the low equivalent weight polyol and phosphate group-containing polyol into the base polyether polyol, followed by adding the polyisocyanate. In such a process, the catalyst may be added before, simultaneously with, or after the polyisocyanate is added.

[0022] It is also possible to combine the base polyether polyol simultaneously with the low equivalent weight polyol, phosphate group-containing polyol and polyisocyanate (and optional ingredients, if used), as through a mixhead.

[0023] The mixture of materials is then reacted to form polyisocyanate polyaddition (PIPA) particles dispersed in the base polyether polyol. The conditions for the reaction typically include agitation and / or turbulent flow conditions, which helps to disperse the low equivalent weight polyol into droplets until such time as it reacts with isocyanate compounds to form polymer particles. Agitation and / or turbulent flow conditions can be provided in any convenient way, using any convenient apparatus, such as various types of agitated vessels, static mixing devices, ultrasonic mixing devices or other mechanical agitation devices. In preferred embodiments, the low equivalent weight polyol is dispersed to form fine droplets, typically less than 5 pm. less than 5 pm or less than 2 pm in diameter, in the base polyether polyol.

[0024] The mixture of starting materials preferably is maintained under agitation and / or turbulent flow conditions until the low equivalent weight isocyanate-reactive compound and phosphate group-containing polyol have reacted with isocyanate groups in the base polyether polyol mixture to form polyisocyanatc poly addition particles. It is not necessary to maintain agitation or turbulent flow conditions until all isocyanate groups are consumed, provided that agitation is maintained until particles have formed. Particle formation is indicated by the appearance of a highly opaque dispersion. Typically agitation and / or turbulent flow conditions are maintained until at least 50%, preferably at least 75%, of the isocyanate groups have been consumed.

[0025] A urethane catalyst is typically present to promote the PIPA-forming reaction. The urethane catalyst is a material which catalyzes the reaction of a hydroxyl group with an isocyanate group. Suitable catalysts include, for example, including tertiary amines, cyclic amidines, tertiary phosphines, various metal chelates, acid metal salts, strong bases, various metal alcoholates and phenolates and metal salts of organic acids. Catalysts of most importance are tertiary amine catalysts, cyclic amidines, and tin catalysts. Examples of tertiary amine catalysts include trimethylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N- dimethylbenzylamine, N,N-dimethylethanolamine, N,N,N',N'-tetramethyl- 1 ,4-butanediamine, N,N-dimethylpiperazine, 1 ,4-diazobicyclo-2,2,2-octane, bis(dimethylaminoethyl)ether, triethylenediamine and dimethylalkylamines where the alkyl group contains 4 to 18 carbon atoms. Mixtures of these tertiary amine catalysts are often used.

[0026] Examples of tin catalysts are stannic chloride, stannous chloride, stannous octoate, stannous oleate, dimethyltin dilaurate, dibutyltin dilaurate, other tin compounds of the formula SnRu(0R)4-u, wherein R is alkyl or aryl and n is 0-2, and the like. Tin catalysts are generally used in conjunction with one or more tertiary amine catalysts, if used at all. Tin catalysts tend to be strong gelling catalysts, so they are preferably used in small amounts.

[0027] Catalysts are typically used in small amounts, for example, each catalyst being employed from about 0.0015 to about 5% by weight of base polyether polyol.

[0028] Another optional ingredient of the PIPA-forming reaction mixture is a stabilizer. Examples of such stabilizers are described, for example, in WO 94 / 20558, WO2012 / 154820 and WO 2015 / 038825.

[0029] Still another optional ingredient is a previously formed seed dispersion of polymer particles in a continuous polyether polyol phase, such as is described, for example, in US Patent No. 5,068,280 and WO 2015 / 038825. The seed dispersion, when used, is preferably a previously formed PIPA dispersion in a base polyether polyol as described herein, and preferably constitutes 1 to 5 percent of the total weight of all components of the dispersion-forming reaction mixture. If a previously formed seed dispersion is included in the reaction mixture, it is preferred to include enough of the previously formed seed dispersion to provide 0.05 to 20, especially 0.05 to 2 or 0.05 to 1, pails by weight of seed polymer particles per 100 parts by weight base polyether polyol.

[0030] The PIPA-forming reaction may be performed at a temperature of, for example, 0 to 100°C. An elevated temperature may be desirable to reduce reaction time, but this is often not necessary, and it may become more difficult to control the extent of reaction between the base polyether polyol and isocyanate groups if the temperature is too high, which can lead to high product viscosity. Typically, the starting components are mixed at a temperature of 0 to 100°, preferably 10 to 70°C and more preferably 20 to 60°C. The mixture is then allowed to react. This can be done without further applied heat if desired. The particle-forming reaction is exothermic and may result in a temperature increase even if no heat is applied. Cooling can be applied if necessary to prevent excessive temperature increases due to the exothermic heat of reaction.

[0031] The reaction to form polyisocyanate polyaddition particles typically requires from 30 seconds to one hour, although this depends on factors such as temperature. A more preferred time of reaction is 1 minute to 10 minutes, and in specific embodiments is 2 to 7 or 2 to 5 minutes. A somewhat longer time may be required for essentially all of the isocyanate groups to react.

[0032] The process for making the PIPA polyol can be performed batch-wise, in a semi-batch process, or continuously.

[0033] Upon completion of the reaction, the crude PIPA polyol can be stripped or otherwise treated to remove unreacted materials, volatile reaction by-products, and the like. Stripping can be performed, for example, by applying vacuum, preferably coupled with an elevated temperature. A stripping agent can be bubbled through the product to facilitate removal of these materials. The PIPA polyol may be filtered if desired to remove large particles and / or agglomerates.

[0034] The product is a dispersion of polyisocyanate polyaddition (PIPA) particles in the base polyether polyol. The dispersion may contain, for example 1 to 40%, 5 to 30%, 8 to 25% or 8 to 15% by weight of the dispersed PIPA particles. For purposes of this invention, the weight of the dispersed PIPA particles is taken to be that of the combined weight of the polyisocyanate, the low equivalent weight polyol and phosphate group-containing polyol added into the process, plus the weight of any seed polymer particles that may be used in the process.

[0035] In some embodiments, the dispersion has a viscosity of 500 to 10,000 mPa s at 20°C. In other embodiments, the viscosity at 20°C is 750 to 5000 mPa-s or 750 to 2500 mPa-s.

[0036] The hydroxyl number of the dispersion of the invention may be at most 350 mg KOH / g, and in some embodiments is 28 to 250 or 35 to 200 mg KOH / g.

[0037] A dispersion made in accordance with the invention is useful in making polyurethanes by reaction with a polyisocyanate. In particular, the dispersion is useful for making polyurethane foam in a molding or free -rise (slabstock) process, by reacting the dispersion with a polyisocyanate in the presence of a chemical and / or physical blowing agent.

[0038] Suitable polyisocyanates for use in making polyurethane foams include those described above. In the slabstock foaming process, the dispersion of the invention is combined with a polyisocyanatc and reacted in the presence of a blowing agent to form the foam. The mixed starting materials are dispensed into a region, typically a trough, in which they react and rise without constraint or under minimal constraint (such as the weight of a plastic film) and cured to form the foam. Suitable methods for making slabstock polyurethane foam are described, for example, in US Patent Nos. 5,582,840 and 4,970,243. The various ingredients of the foam formulation may be mixed at, for example 15 to 50°C and cured without additional applied heat. Exothermic heat of reaction typically produces an elevated temperature to drive the cure.

[0039] In a molding process, the dispersion of the invention is combined with a poly isocyanate in the presence of a blowing agent and preferably a urethane catalyst and a surfactant to form a reaction mixture that is introduced into a closed mold, where it reacts and expands to form a foam having dimensions and geometry corresponding to the interior cavity of the mold. The curing step may be performed with or without applied heat. For example, the mold may be at a temperature of 15 to 50°C when the foam formulation is introduced and cooled during the curing process to produce a compact skin. Alternatively, the mold may be preheated and / or heated during the curing process to facilitate curing.

[0040] Suitable blowing agents for making polyurethane foam include physical (endothermic) blowing agents such as various low-boiling chlorofluorocarbons, fluorocarbons, hydrocarbons, hydrofluoroolefins, and the like. Chemical (exothermic) blowing agents that decompose or react under the conditions of the polyurethane-forming reaction are also useful. By far the most preferred chemical blowing agent is water, which reacts with isocyanate groups to liberate carbon dioxide and form urea linkages. Water is preferably used as the sole blowing agent, in which case about 1 to about 7, especially from about 2.5 to about 5, parts by weight water arc typically used per 100 parts by weight of polyols (including the dispersion of this invention) having hydroxyl numbers of 350 mg KOH / g or less. Water may also be used in combination with a physical blowing agent, particularly a fluorocarbon or hydrocarbon blowing agent. In addition, a gas such as carbon dioxide, air, nitrogen or argon may be used as the blowing agent in a frothing process. Carbon dioxide can also be used as a liquid or as a supercritical fluid.

[0041] It is highly preferred to include a foam-stabilizing surfactant in a polyurethane foam formulation. The foam- stabilizing surfactant helps stabilize the gas bubbles formed by the blowing agent during the foaming process until the polymer has cured. A wide variety of silicone surfactants as are commonly used in making polyurethane foams can be used in making the foams with the polymer polyols or dispersions of this invention. Examples of such silicone surfactants are commercially available under the tradenames Tegostab™ (Th. Goldschmidt and Co.), Niax™ (GE OSi Silicones) and Dabco™ (Air Products and Chemicals).

[0042] One or more additional polyether polyols having hydroxyl numbers of 280 mg KOH / g or less may be present in the foam formulation. Such additional polyether polyol may constitute, for example, 1 to 70%, preferably 10 to 60% or 25 to 60% of the combined weight of the additional polyether polyol and the PIPA dispersion.

[0043] The dispersed PIPA particles of the dispersion of the invention may constitute, for example, at least 1%, at least 3%, at least 5% or at least 7.5% of the total weight of the foam formulation (excluding the weight of the polyisocyanate) and, for example, up to 40%, up to 30%, up to 25%, up to 25% or up to 15% thereof. The amount of phosphate group-containing polyol used in making the dispersion of the invention may correspond to, for example, 0.75 to 3.5% of the total weight of the foam formulation, excluding the weight of the polyisocyanate.

[0044] In addition to the foregoing components, the polyurethane foam formulation may contain various other optional ingredients such as other polyols, crosslinkers, chain extenders, cell openers; fillers such as melamine and calcium carbonate; pigments and / or colorants such as titanium dioxide, iron oxide, chromium oxide, azo / diazo dyes, phthalocyanines, dioxazines and carbon black; reinforcing agents such as fiber glass, carbon 1’ibers, flaked glass, mica, talc and the like; biocides; preservatives; antioxidants; flame retardants; and the like.

[0045] Polyurethane foam made in accordance with the invention is characterized in having unexpectedly good performance on flammability testing. In particular, a foam of the invention may meet the Class IM standard of UNI 9175:2010. The foam density may be, for example, 16 to 200 kg / m3 or 16 to 64 kg / m3per ISO 845.

[0046] The following examples are provided to illustrate the invention but are not intended to limit the scope thereof. All parts and percentages are by weight unless otherwise indicated.

[0047] Polyol 1 is a 4800 molecular weight, polypropylene oxide) triol having 18% by weight poly(ethylene oxide) end-groups. Its hydroxyl groups are mainly primary hydroxyl groups.

[0048] Polyol 2 is a 4800 molecular weight, poly (propylene oxide) triol having 14% by weight poly(ethylene oxide) end-groups. Its hydroxyl groups are mainly primary hydroxyl groups.

[0049] The Seed Dispersion is a dispersion of 20% by weight polyurethane particles in Polyol 1. TEOA is triethanolamine.

[0050] DEOA is diethanolamine.

[0051] The Seed Dispersion is a dispersion of PIPA particles in a nominally trifunctional, 1600 equivalent weight ethylene oxide-capped poly(propylene oxide). It contains 20% by weight dispersed PIPA particles.

[0052] 80 / 20 TDI is a mixture of 80% 2,4-toluene diisocyanate and 20% 2,6-diisocyanate.

[0053] The MDI Prepolymer is a reaction product of a mixture of 27.9 parts MDI (about 48% 2,4’- isomer and 52% 4,4’ -isomer) and 61.1 polymeric MDI (32% NCO content) with 7.95 parts of a poly ether triol having an oxyethylene content of 74% and 2 parts of a 14% ethylene oxide-capped polypropylene oxide) triol. The resulting MDI prepolymer has an NCO content of about 29%.

[0054] The Phosphate Polyol is a product sold commercially as Exolit™ OP 550 by Clariant, Ltd.

[0055] It has the structure: , where n has an average value of approximately 2.5 to 3.5, and has a hydroxyl number of approximately 170 mg KOH / g.

[0056] Fyrol™ 6 is a diethyl-N,N-bis(2-hydroxethyl)phosphonate product commercially available from ICL Industrial Products.

[0057] Catalyst 1 is zinc ricinoleate product sold by Evonik.

[0058] Catalyst 2 is a mixture of commercially available amine catalysts.

[0059] The Silicone Surfactant is commercially available flexible polyurethane foam surfactant sold by Evonik.

[0060] PIPA Polyol Process: All ingredients described in Table 1 except the 80 / 20 TDI are combined and mixed at room temperature. The 80 / 20 TDI is added to the polyol mixture at room temperature with vigorous mixing. Mixing is continued for 5 minutes after adding the 80 / 20 TDI to produce PIPA Polyol Examples 1-3 and Comparative PIPA Polyols A-D. The nominal solids content (combined weight of TEOA, Exolit™ OP550, Fyrol™6, seed particles and 80 / 20 TDI per total dispersion weight), viscosity of the dispersion and d90 particle size of the dispersed polymer particles are as reported in Table 1. Viscosity is measured at 25°C on an Anton Paar MCR 102 parallel plate viscometer with 25 mm plates and a shear rate of 5 s'1. Particle size is measured using light scattering methods.

[0061] Table 1

[0062] Polyurethane foam Examples 1-3 and Comparative Foams A, Al and B-D are made from each of PIPA Polyol Examples 1-3 and Comparative PIPA Polyols A-D, respectively, using foam formulations as set forth in Table 2. All ingredients except the MDI Prepolymer are hand mixed at room temperature. The MDI prepolymer is then added and mixed in with hand for 12 seconds. The resulting reaction mixture is poured into an 11 -liter aluminum mold preheated to 45°C, where it reacts and expands to produce a polyurethane foam. The foams are demolded after 5 minutes curing time in the mold and crushed between metal rolls to open cells.

[0063] The resulting foams are evaluated according to Italian flammability standard UNI 9175:2010 Class IM. In each case, two samples of the foam, each 400 mm x 300 mm x 75 mm, are placed onto a metal support to form a seat and seat back. A propane flame having a height of 40 mm is applied at the junction of the seat and back for 140 seconds, then removed. The foams each are tested in this manner 3-5 times. The amount of time required for the foam to self extinguish after the flame is removed is measured. A “Pass” is recorded if all the samples of a foam self-extinguish in 120 seconds or less. A “Fail” is indicated if fewer than all the samples self-extinguish in 120 seconds or less. Results of the UNI 9175 Class IM testing are as reported in Table 2.

[0064] Table 2

[0065] ’The polyol mixture is all ingredients used in making the foam as listed in Table 2, except the MDI Prepolymer. The weight of the phosphorus containing polyols includes the total weight of Exolit™ OP550 and Fyrol™6 used in making the PIPA polyol, plus the added Exolit™ OP550 used in making Comp. Foam A 1. The phosphorus-containing polyols in each case have reacted into the PIPA particles and / or the polyurethane foam.

[0066] Comparative Foam A is a baseline case, made without any phosphate group-containing polyol. It fails to meet the Class IM standard. Adding 4 parts of the phosphate group-containing polyol into the foam formulation (rather than into the PIPA dispersion recipe), as in Comparative Foam Al, does not result in a foam that meets the standard.

[0067] Foam Examples 1-3 all meet the Class IM standard. In each case, the PIPA polyol is made using the phosphate group-containing polyol, the total amount of phosphate group-containing polyol in the foam formulation ranging from about 1.26 to 1.9% by weight of the polyol mixture used to make the foam.

[0068] Comparative Foams B and C, taken together with Foam Examples 1-3, show the effect of the ratio of component i) and ii) in making the PIPA dispersion. This ratio is about 5.6 for Comparative Dispersion B and only 1 for Comparative Dispersion C. In each case, the resulting foam is unable to meet the Class IM standard. The result for Comparative Foam C is particularly notable, as the total amount of phosphate group-containing polyol is 2.71 weight-%, which is significantly greater than Foam Examples 1-3.

[0069] Comparative Foam D shows the effect of substituting a polyol that contains phosphonate groups for one that contains phosphate groups. Comparative Foam D is unable to meet the Class IM standard despite having a content of phosphorus group-containing polyol similar to Foam Example 1.

Claims

WHAT IS CLAIMED IS:

1. A process for preparing a dispersion of polyisocyanate polyaddition particles in a base polyether polyol, comprising forming an agitated mixture of i) a low equivalent weight polyol having a hydroxyl number of at least 700 mg KOH / g and which does not contain phosphate groups, ii) a phosphate group-containing polyol characterized in having at least two phosphate groups per molecule and at least two hydroxyl groups per molecule, each hydroxyl group being bonded to a carbon atom, and a number average molecular weight of 296 to 2000 g / mol, iii) one or more organic polyisocyanate compounds, and iv) a base polyether polyol having a hydroxyl equivalent weight of at most 280 mg OK / g, and reacting the low equivalent weight polyol and the phosphate group-containing polyol with the one or more polyisocyanate compound(s) in the presence of the base polyether polyol to form the dispersion of polyisocyanate polyaddition particles in the base polyether polyol, wherein the weight ratio of i) : ii) is 2 to 4.

2. The process of claim 1 wherein the phosphate group-containing polyol has the structure:wherein each R1is independently hydrocarbyl, each R2is independently alkylene or arylsubstituted alkylene and n is a number such that the phosphate group-containing polyol has a number average molecular weight of 296 to 2000 g / mol.

3. The process of claim 2 wherein each R1is independently alkyl having 1 to 4 carbon atoms, and each R2is independently linear or branched alkylene having 2 to 4 carbon atoms.

4. The process of claim 3 wherein each R1is ethyl and each R2is ethylene.

5. The process of any of claims 2-4 wherein n is 2 to 4.

6. The process of any preceding claim wherein at least 50 weight-% of the low equivalent weight polyol having a hydroxyl number of at least 700 mg KOH / g is triethanolamine, diethanolamine or a mixture of triethanolamine and diethanolamine.

7. The process of claim 6 wherein the low equivalent weight polyol having a hydroxyl number of at least 700 mg KOH / g is triethanolamine.

8. A dispersion of polyisocyanate poly addition particles in a base polyether polyol made in accordance with the process of any of claims 1-7.

9. A polyurethane made by reacting the dispersion of claim 8 with a polyisocyanate.

10. The polyurethane of claim 9 which has a density of 16 to 200 kg / m3.

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