Патент USA US3087910код для вставки
United States Patent 0 ’ ice 1 2 3,087,900 catalyst used and polyether reactant. As a general guide, the amounts used range from about 0.001 to 5%, pref erably about 0.01 to 1.0%, by weight, based on the total POLYETHER POLYURETHANE FOAMS STABIL IZED WITH MALIC ACID, CITRIC ACID, 0R NITRILOTRIACETIC ACID Kenneth L. Brown, Arnionk, N.Y., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed Apr. 26, 1960, Ser. No. 24,642 a 3,087,900 Patented Apr. _ 30, 1963 4 Claims. (Cl. 260-25) weight of the polyether-isocyanate reaction mixture. The polycarboxylic acids of the invention are effective stabilizers for a wide variety of polyurethane foams de rived from the reaction of polyethers and isocyanates. The term “polyether” as used herein refers to a com pound which has a molecular weight of at least about 250, This invention relates to polyurethane compositions, 10 a plurality of ether oxygens, and contains at least two and more particularly to cellular foamed polyurethanes to which improved stability and resistance to heat de terioration have been imparted by the addition of cer active hydrogens as measured and determined by the reactions of di- or polyisocyanates with active hydrogen propylene polyglycols prepared in‘ a similar manner uti Zerewitinoif method, J.A.C.S., vol. 49, p. 3181 (1927). Illustrative polyethers include polyoxyalkylene glycols such as the polyoxyethylene glycols prepared by the ad tain polycarboxylic acids. Synthetic urethane products derived from reactions in 15 dition of ethylene oxide to water, ethylene glycol or di ethylene glycol; polyoxypropylene glycols prepared by volving isocyanates with active hydrogen-containing com the addition of 1,2-propylene oxide to water, propylene pounds are rapidly becoming competitive with natural glycol or dipropylene glycol; mixed oxyethylene-oxy and synthetic rubbers. Urethane polymers formed by containing compounds, e.g., polyols, polyesters, poly 20 lizing a mixture of ethylene oxide and propylene oxide or a sequential addition of ethylene oxide and 1,2-propylcne esteramides, polyamides, water, polyalkylene ether gly oxide; polyether glycols prepared by reacting ethylene cols, etc., are readily foamed by internal development glycol, propylene oxide or mixtures thereof with mono of carbon dioxide or by means of a blowing agent which and polynuclear dihydroxy benzenes, e.g., catechol, re vaporizes at or below the temperature of the foaming mass. More recently, commercial interest has been di 25 sorcinol, hydroquinone, orcinol, 2,2-bis(p-hydroxyphen rected to polyether-based urethane foams prepared by the one-shot and prepolymer techniques in which cata lysis is effected by an organic tin compound. Organic tin catalysts offer a considerable number of advantages y1)propane, bis(p-hydroxyphenyl)methane, and the like; polyethers prepared by reacting ethylene oxide, propyl ene oxide or mixtures thereof with aliphatic polyols such as glycerol, sorbitol, trimethylolpropane, 1,2,6-hexane among which are controllable reaction rates and effec 30 triol, pentaerythritol, sucrose or glycosides, e.g., methyl, ethyl, propyl, butyl and Z-ethylhexyl arabinoside, xylo tive use in small concentrations. One of the more im portant disadvantages common to such catalysts, how side, fructoside, glucoside, rhamnoside, etc.; polyethers ever, is their tendency to promote deterioration of poly prepared by reacting ethylene oxide propylene oxide or tensile strength, compression set, elongation and load bearing properties, which thus limits the utility of the hydroxytetrahydropyran and 3,3,5,5-tetrakis(hydroxy methyl)-4-hydroxytetrahydropyran; or polyols containing sired physical properties. Although the exact mecha diarnine; benzidine; tolidine; 4,4'-methylenedianiline; 4, mixtures thereof with alicyclic polyols such as tetra ether-‘based urethane foams at elevated temperatures. This is undesirable since the deterioration results in a 35 rnethylolcyclohexanol; polyols containing a heterocyclic nucleus such as 3,3,5-tris(hydroxymethyl)-5-methyl-4 corresponding loss of desired physical properties, e.g., an aromatic nucleus such as 2,2-bis(hydroxyphenyl) foam for its intended purpose. The present invention is predicated on the discovery 40 ethanol, pyrogallol, phloroglucinol, tris(hydroxyphenyl) alkanes, e.g., l,1,3-tris(hydroxyphenyl)ethanes, and 1,1, that polycarboxylic acids selected from the group of citric 3-tris(hydroxyphenyDpropanes, etc., tetrakis(hydroxy acid, malic acid and nitrilotriacetic acid are highly effec phenyl)alkanes, e.g., 1,1,3,3-tetrakis(hydroxy-3-methyl tive as stabilizers for cellular polyurethane foams pre pared from polyether-isocyanate reaction systems cata 45 phenyl) propanes, 1, 1,5 ,5 -tetrakis (hydroxyphenyl) butanes, and the like. lyzed by an organic tin catalyst. It has been found that Other suitable polyols include the ethylene oxide, pro when a minor amount of the above-described polycar pylene oxide and mixed oxide adducts of aliphatic poly boxylic acids are incorporated in a polyether-isocyanatel amines such as ethylene diamine, triethylene diamine, reaction system of the above type and the mixture sub sequently foamed by the one-shot, semiprepolymer or 50 etc.; aromatic polyamines such as 0-, m-, and p-phenyl enediamine; 2,4- and 2,6-diaminotoluene; 2,6-diamino-p prepolymer technique, improved urethane foams are ob xylene; 4,6-diamino-m-xylene; 2,4-diamino-m-xylene; 3,5 tained which elfectively resist deterioration at elevated diamino-o-xylene; 2,6-diaminopyridine; 1,4-naphthylene temperatures and exhibit a signi?cant retention of de nism of stabilization is not known, it appears that the 55 4",4"-m-ethylidynetrianiline, and the like. The molecular weight of the polyether used should deterioration of polyether-based urethane foams at ele~ range from about 250 to about 12,000 depending upon vated temperatures is due to an oxidative degradation the characteristics desired in the foamed urethane product. which results from an attack on polyether linkages by As a general rule, cellular urethane foams of maximum free radicals produced from the organic tin catalyst dur-‘ rigidity are prepared by the use of polyethers having a ing the curing cycle of the foam. The polycarboxylic molecular weight range of about 250 to 1250; for semi acids are believed to prevent the cleavage or degradation rigid foams the molecular weight of the polyether should of polyether linkages through their function as a chelat be about 800 to 1800; and for ?exible open~cell foams , ing or sequestering agent for the free radicals. the polyether should be of increased chain length and In carrying out the invention the polycarboxylic acids may be ‘added to the liquid polyether, the isocyanate, 65 have a molecular weight of about 1800 to 12,000. A variety of isocyamates may be employed for reaction or the polyether-isocyanate reaction mixture. The mix~ with the polyethers above described to provide urethane ture is then simultaneously or stepwise foamed in the foams which can be stabilized according to the invention. presence of the organo-tin catalyst by internal develop Preferred isocyanates are polyisocyanates and polyiso ment of carbon dioxide, or by means of a blowing agent which vaporizes at or below the temperature of the foam 70 thiocyanates of the general formula: ing mass. R(NCG)x ‘ The amount of polycarboxylic acid employed will vary, with such considerations as concentration, type of tin wherein G is oxygen or sulfur, x is an integer of two or 3,087,900 3 4 more and R is an alkylene, substituted alkylene, arylene or substituted arylene radical, a hydrocarbon, or sub stituted hydrocarbon containing one or more aryl --NCG between the isocyanate groups and water to form urylene links (—NHCONH—) and carbon dioxide, as well as the reaction of the urylene links so formed with unreacted iso cyanate groups to form biuret cross links. Depending upon the desired density of the urethane foam and the amount of cross linking desired, the total —NCO equiva lent to total active hydrogen equivalent should be such bonds and one or more alkyl —NCK bond. R can also include radicals such as —RZR— where Z may be a di valent moiety such as —O—, —O—R—O—, —CO~, ——CO2——, ~S——, —S-—R-—S—, —SO2——, etc. Examples of such compounds include hexamethylene diisocyanate, as to provide a ratio of 0.8 to 1.2 equivalents of —NCO l,8—diisocyanato—p-mentane, xylylene diisocyanates, per equivalent of active hydrogen and preferably a ratio 10 of about 0.9 to 1.1 equivalents. The foaming operation also can be eifected by means of a blowing agent, such as a low boiling, high molecular weight gas, which vaporizes at or below the temperature of the foaming mass. In rigid foams intended for use in the ?eld of insulation and structural reinforcement the ( OCNCH2CH2CH2OCH2 ) 2 1—methyl-2,4-diisocyanatocyclohexane, phenylene diiso cyanates, tolylene diisocyanates, ehlorophenylene diiso cyanates, diphenylmethane - 4,4’ - diisocyanate, naphtha lene 1,5 - diisocyanate, triphenylmethane-4,4’,4"-triiso cyanate, xylene-a,ot'-diisothiocyanate, and isopropylben incorporation of a gas lowers its heat conductivity. If a Zene-aA-diiSocyanate. ?uorocarbon gas such as trichloromono?uoromethane, “Ucon 11,” is used in blowing rigid foams, a lower K factor is obtained than in regid foams of equal density Further included are dimers and trimers of isocyanates and diisocyanates and polymeric diisocyanates of the gen eral formulae: 20 blown with air or carbon dioxide. The reactions that occur during this type operation include formation of the urethane linkage as well as the formation of isocyanates dimers and trimers. In addition, another reaction that can occur is the formation of ‘allophanate structures. 25 Preferred blowing agents are the ?uorocarbons such as in which x and y are two or more, as well as compounds of the general formula: Examples of this type trichloromono?uoromethane; dichlorodi?uoromethane, di chloro?uoromethane, 1,l-dichloro-l-?uoroethane; l-chlo include ethylphosphonic diisocyanate, C2H5P(O) ( NCO) 2; phenylphosphonic diisocyanate, C6H5P(NCO)2; com ro-l,l-di?uoro, 2,2-dichloroethane; and 1,1,1-tri?uoro, 2-chloro-2-?uoro, 3,3-di?uoro, 4,4,4-tri?uorobutane. The in which x is one or more and M is a monofunctional or polyfunctional atom or group. pounds containing a ESl—NCG group, isocyanates de 30 amount of blowing agent used will vary with density de rived from sulfonamides (RSO2NCO), cyanic acid, thio cyanic acid, and compounds containing a metal-NCG group such as tributyltin isocyanate. The preparation of polyether-based urethane foams sired in the foamed product. In general it may be stated that for 100 grams of resin mix containing an average NCO/ OH ratio of 1 to 1, about 0.005 to 0.3 mole of gas are used to provide densities ranging from 30 to 1 lbs. 35 per cubic foot. If desired, water may be used in conjunc can be carried out by forming a prepolymer, i.e., pre reacting molar equivalents of the polyether and isocyanate tion with the blowing agent. in the absence of water and thereafter producing a foam by the addition of excess isocyanate, tin catalyst, water Organic tin catalysts that are suitable for accelerating the polyether-isocyanate reaction are compounds having the general formula: and surfactant; by the one-shot method in which the poly ether, blowing agent, and isocyanate reactants are simul 40 (11) taneously mixed together and allowed to react in the pres ence of an organic tin catalyst; or by the semiprepolymer technique wherein the polyether reactant is partially ex tended with excess isocyanate to provide a reaction (b) (c) (d) (e) product containing a high percentage of ‘free isocyanate 45 (f) groups (20~35%) which is then foamed at a later stage (a) by reaction with additional polyether, a blowing agent and tin catalyst. The amount of isocyanate used in the preparation of ?exible, rigid or semirigid foams should be such that there 50 is more than the theoretical amount required to vform a in which R represents hydrocarbon or substituted hydro carbon radicals such as alkyl, aralkyl, aryl, alkaryl, al urethane linkage, —NHCO-—O——, in the polymer result ing from reaction of the isocyanate with the active hydro gens of the polyether. koxy, cycloalkyl, alkenyl, cycloalkenyl, and analogous sub The amount of isocyanate em stituted hydrocarbon radicals; the R’ represents hydro ployed generaly ranges from about 1.0 to 7 equivalents, preferably 2 to 6 equivalents, per equivalent of polyether. carbon or substituted hydrocarbon radicals such as those designated by the R or hydrogen or metal ions, the X The reaction of excess diisocyanate with a polyoxy represents hydrogen, halogen, hydroxyl, amino, alkoxy, propylene glycol produces a polymer having terminal iso cyanate groups as illustrated by the equation: (I) substituted alkoxy, acyloxy, substituted acyloxy, acyl radi 60 cals or organic residues connected to tin through a sul?de Excess OCN~R—NGO + HO(C2H4O),1H ——> OCN—R[NH—O O—O—(CzHiO)n—CzHi-—O—GONHRJNCO in which R represents an aliphatic, cycloaliphatic or aro matic diisocyanate exclusive of reactive isocyanate groups (-—NCO), x is an integer greater than 1 and n is an in teger such that the molecular weight of the ether glycol is at least 250. When it is desired to form a foam, the mixture of the isocyanate-modi?ed polyether reacts 70 through the isocyanate groups with a chain extending agent containing active hydrogen, e.g., water, in the pres ence of an organic tin catalyst. This involves several re actions that proceed. simultaneously including the reaction 75 link; and the Y represents chalcogens including oxygen and sulfur. 'Among the compounds of group (a) that deserve spe cial mention are trimethyltin hydroxide, tributyltin hy droxide, trimethyltin chloride, trimethyltin bromide, tri butyltin chloride, trioctyltin chloride, triphenyltin chloride, tributyltin hydride, triphenyltin hydride, triallyltin chlo ride, tributyltin ?uoride, tributyltin acetate, and tetrabutyl tin, etc. The compounds in group (b) that deserve particular mention and are representative of the group include di methyltin diacetate, diethyltin diacetate, dibutyltin diace tate, dioctyltin diacetate, dilauryltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dimethyltin dichloride, di butyltin dichloride, dioctyltin dichloride, diphenyltin di 3,087,900 .6 chloride, diallyltin dibromide, diallyltin diiodide, bis(car nous phenoxide, and 0-, m- and p‘stannous cresoxides, (in which x is a positive integer), dibutyl-bis[O-acetyl— Either class of stannous catalysts may be substituted with hydroxy, halo and keto, etc., groups. The following examples illustrate the best mode now contemplated for carrying out the invention. EXAMPLE I A typical polyurethane foam formulation was prepared etc. boethoxymethyl)-tin diiodide, dibutyltin dimethoxide, di butyltin dibutoxide, (Cilia) 2SII[OCH2( cHaocHz) x—-1OH2O CH3] 2 acetonyl]-tin, dibutyltin-bis(thiododecoxide), and all readily prepared by hydrolysis of the corresponding di halides. Many commercially available compounds used 10 as follows. Material: [Parts by Weight vGlycerol-propylene oxide adduct, 3,000 as stabilizers for vinyl resins are also included in this group. Among the compounds that are representative of group 15 average molcular weight __________ __ Water (total) _____________________ __ Tetramethyl butanediamine __________ __ (c) are butyltin trichloride, octyltin trichloride, butyltin triacetate and octyltin tris(thiobutoxide). Dibutyltin dilaurate ________________ __ 0.20 Emulsi?er (siloxane-oxyalkylene copoly Typical among the compounds of group (cl) are di~ methyltin oxide, diethyltin oxide, dibutyltin oxide, di octyltin oxide, dilauryltin oxide, diallyltin oxide, diphenyl tin oxide, dibutyltin sul?de, [HOOC(CH2)5]2SnO, N-methyl morpholine _______________ __ 100.0 2.9 0.10 0.20 mer) __________________________ __ 20 Tolylenediisocyanate _______________ _ _ 0.80 3 8. l Additive _________________________ __ 0.01 to 0.1 Polyurethane foams, 2" x 2" x 1", prepared from the and which [‘OH3O the x’s CH2 are positive integers). 5] 28110 Methylstannonic acid, ethylstannonic acid, butylstan nonic acid, octylstannonic acid, HOOC(CH2)5—SnOO'I-I, (CH3) 3N (CH2) 5SI1OOH above ingredients were isolated in a quart can with vented lids and heated to 140° C. The foams were removed 25 cHaOCHztcHzOcl-lz) x_1CH3SnOOH periodically and qualitatively examined for failure. Fail ure occurred when a pointed object, such as a pencil, would easily penetrate the foam. Table 1 illustrates the effectiveness of the polycarboxylic acids for imparting im proved stability and resistance to heat deterioration. 30 Table l and CH3OCH2(CH2OCH2) ,HCHZO (CH2) 5SnO0H _ . are examples of group (e) catalysts and group (j) cata Addltive lysts are represented by HOOSn(CH2),,SnOOH and 35 Concen- Time in tration, Parts by Hours at 140° C. to Weight Failure HOOSnCH2(CH2OOH2)XCHZSnOOH, the x’s being posi tive integers. Typical compounds in group (g) include compounds Malic Acid .................................. -_ 0. 05 0. 01 32 as poly(dialky1tin oxides) such as dibutyltin basic laurate Nitrilotriacetic Acid..-" 0. 05 40 Citric Acid ____________ __ 0.1 Control _____________________________________ -- 0. 00 and dibutyltin basic hexoxide. Other compounds that are efficient catalysts are those 40 8 20 3-5 of group (h), of which the organo-tin compounds used What is claimed is: as heat and light stabilizers for chlorinated polymers and 1. In a method for preparing polyurethanes wherein a available commercially for such use, are typical. polyether polyol which has a molecular weight of at least Other organic tin compounds which can be used in 45 about 250 and which contains at least 2 active hydrogens clude the divalent tin compounds selected from the group as measured and determined by the Zerewitinoft test and consisting of stannous acylates and stannous alkoxides. an organic polyisocyanate are reacted together in the Suitable stannous acylates are the divalent tin salts of presence of an organic tin catalyst and foamed by means aliphatic mono- and polycarboxylic acids which contain of a blowing agent, the improvement which comprises from 1 to 54 carbon atoms. The acids can be saturated, incorporating in the reaction mixture a stabilizing amount such as acetic acid, 2-ethylhexanoic acid, etc.; unsaturated of a polycarboxylic acid selected from the group consist such as oleic acid, linoleic acid, ricinoleic acid, and the ing of malic acid, citric acid, and nitrilotriacetic acid. like; or they may be polymerized fatty acids derived from 2. The method of claim 1 wherein the acid is citric natural oils, e.g., linseed oil, tung oil, soybean oil, dehy acid. drated castor oil, which have a molecular weight up to 55 3. The method of claim 1 wherein the acid is malic about 500. Examples of speci?c acylates include: stan acid. nous acetate, stannous propionate, stannous oxalate, stan 4. The method of claim 1 wherein the acid is nitrilo nous tartrate, stannous butyrate, stannous valerate, stan triacetic acid. nous caproate, stannous caprylate, stannous octoate, stan References Cited in the ?le of this patent nous laurate, stannous palmitate, stannous stearate, and 60 stannous oleate. Of these materials the preferred cata UNITED STATES PATENTS lysts are stannous acetate, stannous octoate and stannous oleate. The stannous alkoxides which can be used may be repre sented by the formula: 65 2,667,522 2,894,919 2,915,496 McElroy _____________ _. Jan. 26, 1954 Simon et a1. __________ __ July 14, 1959 Swart et a1. ___________ __ Dec. 1, 1959 OTHER REFERENCES in which R is a monovalent hydrocarbon radical, satu ‘Mobay: “A One Shot System for Flexible Polyether rated or unsaturated, branched chain or straight chain, Foams,” November 10, 1958. containing 1 to 18 carbon atoms, preferably 3 to ‘12. 70 Urethane Union Carbide, “One-Step Urethane Foams,” Advance Representative examples of stannous alkoxides include Technical ‘Information Sheet 11-40487, February 9, 1959. stannous methoxide, stannous isopropoxide, stannous Union Carbide, “Carbide Announces New Catalyst for butoxide, stannous t-butoxide, stannous Z-ethylhexoxide, stannous tridecanoxide, stannous heptadecanoxide, stan Polyether Urethane Foams,” November 25, 1958.