Use of styrene-acrylonitrile polymer polyols containing partially alkoxylated polyoxyalkyleneamines

Abstract: Vinyl polymer polyols are produced by free radical polymer­ isation of at least one vinyl monomer (e.g. styrene, acrylonitrile, methyl methacrylate, methyl acrylate and/or butadiene) in a partially alkoxylated polyoxyalkylene amine, e.g. one having a molecular weight of 2000 to 8000. The vinyl polymer polyols react with polyisocyanates forming faster-curing flexible foams with improved loadbearing properties.

Description: This invention relates to the production of dispersions of copolymers of styrene and acrylonitrile in the presence of partially alkoxylated polyoxyalkyleneamines as dispersing media, for use as polymer polyols in the preparation of flexible high resilience polyurethane foam. Conventional polyols useful in the production of flexible polyurethane foams are usually made by the reaction of a polyhydric alcohol with an alkylene oxide, usually ethylene oxide and/or propylene oxide, to a molecular weight of 2,000 to 3,000, or higher. These polyols are then reacted with polyisocyanates, in the presence of water or other blowing agents such as fluorocarbons, to obtain polyurethane foams. Polyols have been modified in many ways to improve the properties of the polyurethanes made from them. One common method of modifying polyols involves the use of a polymeric dispersed phase. One variation available entails the polymerization of vinyl monomers, such as acrylonitrile and styrene, in a polyol medium. Another method includes the polymerization of vinyl monomers in polyol-isocyanate addition products. Another involves the preparation of polyurea polymers by the reaction of diamines with diisocyanates in a polyol medium. US-A-3008917, for example, teaches the addition of an unsaturated liquid monomer, such as styrene, to a polyester-isocyanate adduct, which itself contains vinyl unsaturation. The resulting mixture is then copolymerized through the unsaturated linkages. US-A-3304273 discloses a polymer polyol having groups reactive with the -NCO groups of an organic polyisocyanate (such as polymers of acrylic acid, allyl alcohol, styrene or butadiene), combined with a large amount of a solvent which also contains groups reactive with an isocyanate group, but which has little or no ethylenic unsaturation (such as a polyol). US-A-3383351 discloses similar polymer polyols where the dispersed polymers consist of polymerized ethylenically unsaturated monomers such as methacrylonitrile or styrene, particularly copolymers using more than one kind of unsaturated monomer. US-A-4104236 reveals a liquid polymer polyol composition containing 45 to 90 wt. % of a polyoxypropylene polyol having a molecular weight of at least 1500, and 55 to 10 wt. % of a polymer. The polymer consists of 60 to 90 wt. % of polymerized acrylonitrile and 40 to 10 wt. % of polymerized styrene. Polyurethane foams having high load-bearing properties, and solid polyurethane elastomers having a high modulus, were made from these materials. A polymer polyol consisting of 45 to 95 wt. % of a poly(oxypropyleneoxyethylene) polyol having a hydroxyl number of 20 to 60, an oxyethylene cap of 10 to 30 wt. %, an internal oxyethylene content of 5 to 60 wt. % and from 5 to 60 wt. % of a polymerized vinyl monomer (such as a copolymer of styrene and acrylonitrile) is described in US-A-4125505. Further, US-A-4148840 discloses polymer polyol compositions made by polymerizing one or more ethylenically unsaturated monomers in a polyol. High resilience urethane foams may be prepared from tolylene diisocyanate and polymer polyol compositions which were made by polymerizing acrylonitrile and vinylidene chloride monomers in polyols, as described in US-A-4214055. Foams made from the novel polymer polyols showed enhanced load-bearing properties and a decrease in flammability. US-A-4226756 teaches that polyol/vinyl polymer blends made by polymerizing acrylonitrile, styrene and/or methyl methacrylate in the presence of polyethylene-polypropylene glycols are useful in producing polyurethanes. Polymer stabilizers made by polymerizing 30:70 acrylonitrile-styrene mixtures with polypropylene glycol monobutyl ether methacrylate are disclosed in US-A-4242249 as useful stabilizers for polyolvinyl monomer reaction products. US-A-4521581 discloses a method of making polymer polyols by mixing a relatively low molecular weight liquid polymer of an ethylenically unsaturated monomer with a polyol and crosslinking it in the polyol. US-A-3325421 describes polyurea polymer polyols made by reacting diamines with diisocyanate using a polyol as the dispersing medium. EP-A-0177192 discloses a vinyl polymer polyol prepared by polymerizing, via a free radical reaction, a vinyl monomer component having at least one vinyl monomer in the presence of an epoxy resin modified polyol having a molecular weight of 2,000 to 7,000. The free radical-initiated polymerization of vinyl monomers using epoxy resin-modified polyols as the reaction medium gives polymer polyols which are more effective than conventional polymer polyols in increasing the load-bearing properties of flexible foams. US-A-4523025 describes polymer polyols made from partially alkoxylated polyoxyalkyleneamines reacted with an organic polyisocyanate in a polyether polyol. The art cited heretofore primarily discloses variations of the preparation of polymer polyols by a procedure using a polyol as the dispersing medium. US-A-4286074 teaches the preparation of copolymer dispersions by the in situ polymerization of an ethylenically unsaturated monomer or mixture of monomers in the presence of a free radical initiator in an amine-terminated polyoxyalkylene polyether polymer. These dispersions were found useful in the preparation of polyurethane foams which have improved tensile strength, elongation, load deflection and tear strength properties. The present invention provides the use of a polymer polyol based on styrene/acrylonitrile copolymer in the preparation of a flexible high resilience polyurethane foam to achieve improved firmness and faster curing, the polymer polyol being obtained by polymerising the styrene and acrylonitrile monomer components in a free radical initiated reaction in the presence, as dispersing medium, of a partially alkoxylated polyoxyalkylene amine containing both OH and NH₂ groups and obtainable by the alkoxylation of amino hydrogen atoms of polyoxyalkylene amine and wherein less than 90% of the amine groups in the partially alkoxylated product are tertiary amine groups. Generally, the partially alkoxylated polyoxyalkyleneamine employed in the process of this invention may be prepared by the addition of at least one alkylene oxide to an aqueous polyoxyalkyleneamine, as described in US-A-4465858. Preparation of polymer polyols by the free-radical catalyzed polymerization of vinyl monomers using polyols or amine-terminated polyethers as the dispersing medium is known. These polymer polyols have been used to improve the properties, particularly the firmness, of molded high resilience foam used in automotive seating and slab flexible foam used in carpet underlay. The partially alkoxylated polyoxyalkyleneamines employed in the process of this invention, which preferably have a molecular weight of 2,000 to 8,000, contain both -NH₂ and -OH groups, instead of either of the two singly, and have the advantages of both -NH₂ and -OH terminated materials. Incorporation of the -NH₂ group produces faster-curing foams, while offering controlled reactivity not found using purely amine-terminated materials. The dispersing material of this invention generally has a functionality of 4 to 6, allowing more opportunities for crosslinking, producing firmer foams than those prepared with the polymer polyols of the prior art. The monomer component employed in the process of this invention comprises a mixture of styrene and acrylonitrile. The preferred weight ratio of styrene to acrylonitrile is from 9:1 to 1:9. Any of the known chain transfer agents can be present, if desired. Polymerizing the monomers in the partially alkoxylated polyoxyalkyleneamine occurs in the presence of a catalytically effective amount, preferably 0.1 to 5.0 wt. % based on total feed, of a conventional free radical catalyst known to be suitable for the polymerization of ethylenically unsaturated monomers. Preferred catalysts are the azo-bis compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(isobutyronitrile), 2,2'-azobis-(2-methylbutyronitrile) and 1,1'-azobis(cyanocyclohexane). Other preferred catalysts are organic peroxides, peroxydicarbonates and peroxyesters. Illustrative catalysts are the well-known free radical type of vinyl polymerization catalysts, for example, the peroxides, persulfates, perborates, percarbonates, and azo compounds, including hydrogen peroxide, dibenzoyl peroxide, acetyl peroxide, benzoyl hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, butyryl peroxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, diacetyl peroxide, di-alpha-cumyl peroxide, dipropyl peroxide, diisopropyl peroxide, isopropyl-t-butyl peroxide, butyl-t-butyl peroxide, dilauroyl peroxide, difuroyl peroxide, ditriphenylmethyl peroxide, bis(p-methoxybenzoyl) peroxide, p-monomethoxybenzoyl peroxide, rubrene peroxide, ascaridole, t-butyl peroxybenzoate, diethyl peroxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide, n-butyl hydroperoxide, t-butyl hydroperoxide, cyclohexyl hydroperoxide, trans-decahydronaphthalene hydroperoxide, alpha-methylbenzyl hydroperoxide, alpha-methyl-alpha-ethyl benzyl hydroperoxide, tetrahydronaphthalene hydroperoxide, triphenylmethyl hydroperoxide, diphenylmethyl hydroperoxide, persuccinic acid, and diisopropyl peroxy dicarbonate. A mixture of catalysts may also be used. Especially preferred are polymerization catalysts manufactured by the E. I. duPont de Nemours and Co., such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(isobutyronitrile), 2,2'-azobis-(2-methylbutyronitrile) and 2,2'-azobis-(2-methylbutyronitrile). These products are commercially sold as VAZO (Registered Trade Mark) 52, 64, 67 and 88 respectively. Polymerization occurs using a partially alkoxylated polyoxyalkyleneamine as the dispersing medium. This material may be made by the addition of at least one alkylene oxide to an aqueous polyoxyalkyleneamine. The alkylene oxide should have 2 to 8 carbon atoms, and the polyoxyalkyleneamine should have a molecular weight of from 2,000 to 5,000. The proportion of water may be from 5 to 15 wt. %, based on the polyoxyalkyleneamine present, and the addition is generally conducted at a temperature between 75 and 85°C. The proportion of alkylene oxide used is less than that necessary to alkoxylate totally the polyoxyalkyleneamine. Subsequently, the reaction mixture is digested at a temperature at or above 75°C to give an alkoxylated polyoxyalkyleneamine product having a tertiary amine content of less than 90%. Other details about the preparation of the partially alkoxylated polyoxyalkyleneamines useful in this invention may be found in US-A-4465858. To obtain the vinyl polymer polyols of this invention, all or a portion of the partially alkoxylated polyoxyalkyleneamine is preferably added first to the reaction vessel. It is usually best that the material be heated to the reaction temperature before the next step, which is the slow or dropwise addition of a mixture of the vinyl monomer component, the free radical initiator and any remaining partially alkoxylated polyoxyalkyleneamine. After the reaction proceeds for a short time (0.25 to 1.0 hour), the reaction mixture is digested for approximately 15 minutes and volatiles are stripped off by conventional techniques to leave the vinyl polymer polyol product. The reaction temperature should be 75 to 150°C, preferably 90 to 140°C. Reaction pressures may range from atmospheric pressure to 0.8 MPa. The weight ratio of styrene to acrylonitrile should range from 9:1 to 1:9, preferably 30:70 to 70:30. The amount of polymer in the partially alkoxylated polyoxyalkyleneamine, known as polymer loading, may range from 5 to 50 wt. %, preferably from 10 to 40 wt. %. The preparation of the vinyl polymer polyols will be further illustrated by the following non-limiting Examples. The use of the vinyl polymer polyols of this invention in flexible, high resilience polyurethane foams will also be demonstrated. The advantages over foams made from conventional polymer polyols will also be shown. EXAMPLE 1 This Example will illustrate the preparation of a partially alkoxylated polyoxyalkyleneamine used as the dispersing media of this invention. For this particular illustration, the 3 mole ethylene oxide adduct of a polyoxypropylene triamine having a molecular weight of 5,000 (JEFFAMINE (Registered Trade Mark) T-5000, a product of Texaco Chemical Co.) will be prepared. JEFFAMINE T-5000 (18.16 Kg) and water (0.91 Kg) were charged into a 30 litre reactor. The reactor was then purged with pre-purified nitrogen. Ethylene oxide (.45 Kg) was then added at 85°C and the reaction mixture was digested three hours at 125°C. The reaction mixture was then stripped to a minimum pressure at 125°C, nitrogen stripped and polish filtered. The finished product had the following properties: Total acetylatables, meq/g 0.95 Total amine, meq/g 0.52 Primary amine, meq/g 0.15 Secondary amine, meq/g 0.22 Tertiary amine, meq/g 0.15 Water, wt. % 0.1 Color, Pt-Co 15 EXAMPLE 2 This Example will demonstrate the preparation of the polymer polyols of this invention. Into a 2-litre, three-necked flask equipped with a stirrer, thermometer, dropping funnel, water condenser and nitrogen source were charged 600g of the partially ethoxylated JEFFAMINE T-5000 of Example 1 (JEFFAMINE T-5000.3 ethylene oxide). A premixed blend of 200g of JEFFAMINE T-5000.3 ethylene oxide, 90g of styrene, 110g of acrylonitrile and 5.0g of 2,2'-azobis(2-methylbutyronitrile) was then added dropwise to the reaction flask at 102-110°C over a 50 minute period. The reaction mixture had turned into a white, viscous dispersion during this period. The reaction mixture was then digested for 15 minutes and stripped for 40 minutes at 665 Pa. Unreacted volatiles (7.9g) were recovered in a cold trap. This indicated a monomer conversion of 96%. The finished product had the following properties: Hydroxyl number, mg KOH/g 42.6 Water, wt. % 0.07 Viscosity, (25°C) cps 3560 Appearance White, viscous dispersion EXAMPLE 3 This example will show the utility of the polymer polyol of Example 2 in the preparation of flexible high resilience foam. It will further show the superiority of this polymer polyol as compared to JEFFAMINE T-5000 and JEFFAMINE T-5000·3 ethylene oxide in the preparation of stable open-celled foams that do not shrink. Formulation, pbw A B C D 5,000 molecular wt high reactivity triol 60 100 60 - Polymer polyol of Example 2 40 - - - Partially ethoxylated polyoxyalkylene triamine of Example 1 - - 40 - 5,000 molecular wt. polyoxyalkylene triamine - - - 60 Prior art polymer polyol - - - 40 Water 3.5 3.5 3.5 3.5 L-5309 silicone 1.5 1.5 1.5 1.5 THANCAT® TD-33 0.45 0.45 0.45 0.45 NIAX® A-I 0.08 0.08 0.08 0.08 THANCAT® DM-70 0.3 0.3 0.3 0.3 UL-1 0.01 0.01 0.01 0.01 80:20 TDI/MONDUR® MR 43.5 42.7 44 42.4 NCO/OH 1.02 1.02 1.02 1.02 Details of Preparation Cream time, sec 7-8 8 6 Too re<-> Rise time, sec 115-120 120 110-120 active Gel time, sec 195-210 240 135-150 to determine Properties Foam appearance Good Shrunk Shrunk Gelled Density, Kg/m³ 30.4 Badly Badly on Mixer Chatillon gauge reading, 25%, Kg. 1.258 - - - EXAMPLE 4 This example will compare the use of (A) the polymer polyol of Example 2 with (B) a prior art polymer polyol (NIAX® 34-28 made by Union Carbide Co.). It will further show that the polymer polyols of this invention produce faster curing foams which are 10% firmer than those made from the prior art polymer polyol. Formulation, pbw A B Polymer polyol of Example 2 40 - NIAX 34-28 - 40 THANOL SF-5505 60 60 Water 3.5 3.5 L-5309 silicone 1.5 1.5 THANCAT TD-33 0.45 0.45 NIAX A-1 0.08 0.08 THANCAT DM-70 0.3 0.3 UL-1 0.01 0.01 80:20 TDI/MONDUR MR 43.5 42.5 NCO/OH 1.02 1.02 Details of Preparation Cream time, sec 7-8 8 Rise time, sec 115-120 110 Gel time, sec 195-210 240 Properties Foam appearance Good Good Density, Kg/m³ 30.4 30.4 Chatillon gauge reading, 25%, Kg 1.258 1.144

Claims: Use of a polymer polyol based on styrene/acrylonitrile copolymer in the preparation of a flexible high resilience polyurethane foam to achieve improved firmness and faster curing, the polymer polyol being obtained by polymerising the styrene and acrylonitrile monomer components in a free radical initiated reaction in the presence, as dispersing medium, of a partially alkoxylated polyoxyalkylene amine containing both OH and NH₂ groups and obtainable by the alkoxylation of amino hydrogen atoms of polyoxyalkylene amine and wherein less than 90% of the amine groups in the partially alkoxylated product are tertiary amine groups. The use as claimed bin Claim 1 characterised in that the styrene and acrylonitrile are in a weight ratio of 9:1 to 1:9. The use as claimed in any preceding claim characterised in that the polymerisation is carried out until the polymer loading of the partially alkoxylated polyoxyalkylene amine is from 5 to 50wt%. The use as claimed in any preceding claim characterised in that the free radical initiator comprises from 0.1 to 5.0%, based on total reactants, of an organic peroxide, peroxydicarbonate, peroxyester, 2,2'azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyanocyclohexane), or a mixture thereof. The use as claimed in any preceding claim characterised in that the reaction temperature is from 75 to 150°C and the pressure is from atmospheric to 0.8 MPa. The use as claimed in any of the preceding claims characterised in that the partially alkoxylated polyoxyalkyleneamine has a molecular weight of 2,000 to 8,000.

Inventors: CUSCURINDA MICHAEL, CUSCURINDA, MICHAEL
Applicants: ARCO CHEM TECH, ARCO CHEMICAL TECHNOLOGY, L.P.
Application year: 1986
Main classification: C08F2
IPC codes: C08G18, C08F2, C08F283