[1]S e a r c h H O O I T OR 198509716,, ente -M-air.--22,-193Z--@- 1185Ot7l6, UNITED STATES PATENT OFFICE IT A OLD GRLY, OF AKRON, OHIO, ASSIGNOR TO THE B. P. GOODRICH C03EPANY, OF NEW YORIR@, N. Y., A CORPORATION OF NEW YORK COT"OSITION OF XATTER AND MMHOD OF PRODUCING SAME No Drawing. Original application filed July 31, 1926, Serial No. 126,341. Divided and this application lued Tune 21, 1930. This invention relates to the vulcanization of rubber and similar materials and has for a primary object to provi(le a process for the vtilcanization of rubber by the aid of accel3 erators formed by heat treatment of aldehvdes -with relatively sniall amounts of or,u@nic aliphatic imines, as ivell as ammonia. i@- furtlier object is to provide ,t new class of orcanic accelerators liavin(r t oomparatively 10 low nitro(yen content which will be relatively free from low teiiapei-ature curinu, as shown bv "air curin-" or scorchinodririna factory 'proce-sino- of the uncured rubber ii,iixes, but ivhich 'will cause r,,tpid vulcanizai tion at oi-dinary vulcanizing temperatures. It is known that.,alkalies, such as sodium or potassium h3,droxides, 117ill change acetalcleliydes to al(lol, butyric aldeliyde to parabutylaldelidi,e, and in general change alde20 hydes to -higher boiling pi-oducts. Products such as parabutyl-aldehyde have been proposed as accelerators for the vulcanization of rubber or otherwise describ2d as havino- a valuable effect on the physical properties-of the vuleanizate. I am -,ilso aware that aldehydes are known to react with the well-l@nown aldeliydeaniines, produced by the action of one mol of aldelivae on one mol of pi,imary amine, to :3( provi@le accelerators of i,ulcanizttion comprisin- ultimitelv the reaction I)rodtict of thi-ee illols of ald@hvde on tnvo mol of ainine. Such products are formed bv preparin first the originil aldehyde-amine, and then gy tl-ie aid of heat and t'ie a(ldition of more ald@hyde to cau--e a further reaction. I now find that Nvhen a small amount of an aiiiine, such as aniline, benzvlamine, n-butylaiiiine, or even imiiionii, is idded to a liqtiid aldelivde an(I the mixture is heatecl under a refltix condenser for several hours, a large ,-ti.iount of the aldehyde is condensed, pot@i-n-2rizecl, or otherwise rendei-ed high boiling an(l. afier clistillation of uncha@ged alde4,@ hyde, if any, the resultinr product is found Serial No. 462,925. to correspond to a reaction product of one mol of ainine to several mols of aldehyde. Furthermore, it has been obc-!erved that these higli-boilin(r liquid products, prepared from a large amount of aldehyde combined with 50 a small amount of aniine are not formecl by adding a previously prepared aldehyde-amine to a large excess of aldehyde. The ori-o-inal aldehyde-amine condensation produ t,tonce c forined apparently does not function the 55 same as the ori(Yinal amine. The exact nature of these products is not kno-",n, and they are therefore for convenience referred to herein as "condensation products". Furthermore, I find that the preparation of (;o tllese condensation pi@odlicts having a large aiiiouiit of aldehyde ccmbined with a small aiiiount of amine may be carried out in the pi-esence or in the absence of acids and acidic stibstances. The presence of a, small pro- o5 portion of acidic substances in the reaction mixture facilitates the condensation reaction and results ordinarily in a condensation product of somewhat higher accelerating value than these condensation products made from To aldehydes and amines without the presence of acids. Commercial aldehydes normally contain a small per cent. of free acids, rangin,-, approximately from 0.5 to 3 per cent., and it has been observed that the amount 75 of free acids normilly present in commercial al(.Ielivdes is -enei@ally stifficient to oive ccndonsation products of maxim zn um accelerating i@altie. A-Ithoii(,h a reaction mixture of aldelivdes and az-mine containing)r from 0.5 to so 3 I)er cent. of acids, based on the aldehyde, is ordinarily preferred for the preparation of these condensation products, it has been fotind that reaction mixtures containing both lo-wer and higlier percentages of acid produce 85 condensation proclucts of high accelerating val-Lie. The relative accelerating value of condensation products of an aldehyde and an amine made in the presence and in the absence of 90
[2]13850,710 acids is;illustrated by the fohowing expericondensation product-0.4 parts by weight. ment: All cures were at 2861 F. In the results tab Example l.--One mol of p-anaino-dime'hulated below, the tensile strengths (T) ar; ylaniline was caused to react with 2 mols of gii-en in pounds per square iiieh, and the n-butvric aldehyde, (a) in the abseiiee of elon(rations (E) in per cent. 5 70 acids and (b) in the presence of acictic substances havin- an acid equivalent of 2.8 per Cure in minutes cent. butyric acid based on the aldelivoe. Each of the tnvo concleiisation products . ivas Nlols aldeliyde per mol 15 30 60 aniin e 10 compounded ilito a rub]Der mix coiiil)risiiicy 75 rubber-100, zinc o-xide-10. stilfur-5. aild T F T E T E condensatioii product-0.4 parts by iveight. 13,- 0 qi3 2510 838 3520 793 re at 286' F. Iii the results tabI ---------------------------- i 31 3770 733 All cures we 1.6 ---------------------------- 1870 qSl 1 3410 ulated below, the teiisile strengths (T) are 2 ---------------------------- 1 320 88 320 ' ' 1 "40 1490 788 48 -2"5 3@8500 930 15 given in poi.ilids per zqtiare inch, and the ------------------------- ---- i 1 I so elongati,ons (E) in per cent.: Exam.ple 3.-One mol of p-aminodimeCure in minutes thvlaniline was caused to react respectivelv wfth 1. 4, 5 and 8 mols of commercial ii-bi@-4 20 Condensation product made 15 30 60 tyric aldehyde as above described. Each of 1 the four products were compounded into a T I E T E T F i,tibber mix comprisinr rubber-100. zinc oxide 10, sulfur5, and condensation prod(a) Without acid ------------ 1230 110 21- 60 110 2740 775 uct-0.5 parts bv wei(rht. All cures were 20 (b) With acid --------------- 3260 881 3621 775 4450 7@10 -iinutes at. - 287"F. 25 g o Similar improi7ed acceleratino, value of tn 1 Tensil. the acid conciensates of aldehyde-amines over @Nfols aldehyde per mol ainine @gth Elongation in per the non-acid condensates was also observed per sq. i'n. cent. for other niolecular proportions of the above@@i30 aldehyde and amine conclensation product, 1-------------- --------------------------- 3120 713 95 and also for otber aldehvde-amine coiid en_ 4 --------- --------------------------------- 4330 694 5 ------------------------------------------ 4450 719 sation products. The charac'er of the aci dic------------------------------------------ 4670 780 L substances employed in the reaction mixture seems to be of no great cons@equence. althouali 35 the oro-anic acids have been found to b(@ pr@f erable to the stroncrer mineral acids. It is also observed that the condensaticn products comprising two or more mols of aliphatic aldehyde reacted with one mol of 40 an amine excel in accelerating activity the aldehyde-amines heretofore employed as accelerators for the vulcanization of rubber, as is evidenced by shorter cures and higher tensile strengths of the vulcanizates. Start4.1 ing with the reaction product of one mol of aldehyde and ojie mol of amine and increasing the aldehvde in steps of one mol each up to 4, and in @ome cases up to 8., mols of the aldehyde, and compoundinly the products weight for ",eight in a 've@@n foniiula, it is 91 observed that whereas the nitrogen content, or content of orlo,,in-,il amine, orows propoi-tionatelv less and less in the reaction product, yet the acceleratino, effect on the reaction procluct increases as the ratio of aldehvde to amine increases. This is shown bv the two following exl)eriments. Example @?.-One mol of p-amino-dimethco ylaniline was caused to react respectively with 1, 1.6, 2 and 4 mols of commercial nbutyric aldehyde showing on analysis a free acid content equivalent to 2.8 per cent. of butyric acid. Each of the four products were 65 compounded into-a rubber mix comprising rubber-100, zinc oxide-10, sulfur-5, and Iii preparin(, products liavin(r a high ratio of alclehyde to amine. it is fi-equeiitly desir- 100 able to use an excess of aldehyde durino, the reaction -,nd to reiiiove the excess of aldehyde bv distillation, as by heating the reaction mixture to a temperature somewhat higher than the boilino, point of aldehvde employed. 105 Exafftpre 4.-As a f ur@her example of a method of preparation of these accelerators, 10T g. of commercial n-butyric aldehyde were mixed with 18 g. of n-butylamine. This is substantiallv in the ratio of 6 mols of alde- 110 hvde to 1 niol of amine. A violent reaction took place and the liquid boiled. When the reaction had subsided. the mixture was heated under a reflux condenser for from 1 to 2 hours or until the reflux of unchan,-ed al(lehvde had 115 disappeared. The mixture was then'allowed to cool and settle. The lower laier of water was i@emoved and the upper laver dried I)v -eiitle heatin(y in an open container. One half of one part bv wei(,@ht of the product in 120 the above formula' prodiiced a product havino, a tensile strength of about 4400 pounds per square inch, when cured for 15 minutes at 2870 F . in a press. 125 Other aliphatic amines may be substituted for the n-butylamine of the precediing example, such as methylamine. ethylamine. diethvlamine, ethyle'nediami'ne and - the 'like. Di-n-butylamine and tri-n-butylamine when employed in the above example exert a simi- "0
[3]260. CHEMISTRY, CARBON COMPOUNDS. 796 1,850, 716 lar effect in reaction witli a larue ainouiit of butyric aldehyde to produce a condensation product, -%vhicli products, liowever, do not ,(,ive to the N-ulcailizates prel)ared a ecordiiitr to the s,.iiiie foi-iiittla as Iii,,h teilsile sti-eiigths. 'Fliis loii-eticeeleratin(r actioii is tlso obsei-N-e(I ivitli otliet- alil)hatic altlelN-(Ies ti.-eat(-@(I witli otliet- or tei-tiii-y aiiiiiies. EX(l)@@l)le iiiot of aii'liiie was citised 10 to i-eact i-esl)eetivelv -%vitli 1, -), 'a' tn(I 6 iiiols of coiiiiii(-@i-cial I)tttyi-ic al(leliv(le. @t ,i-eater exce@@ of tld(-@Iii@(le tisc(l witli the Iii(,Iieii-atios and the excess i-eiiiove(I 1).N(ii.,tillatioii. The i-elatin-e citi-iii,, action of the fotir I)i-od13 ticts ivas sliowil by ttslii(,,- 0.5 1),,trts I)v wei(,Iit iii the foi-iiiula of Exainple 3 aiid cuiin(,, foi-)9 iiiintites at -?S7' F. and amine employed, the accelerating value dropping off sloivly from a maximum as the aldehyde-amine ratio is further increased. It is also observed that niixtures of differeiit alipliatic aldehydes react witli an organic aniine, or aiiiinonia, to foriiicoiidensation piodticts having desirable acceleratino' values for certain ptirposes. The followin(y exaiiil)le is ilIListrative of such a condensatioii pi,o(.Iuct: E.,eaiiiple 7.-Three iiiols of coiilmercial I)iitvi-ic al(leliyde (1080 parts by weit-,Iit) was iiiixe(I witli oiie iiiol of comiiiercial aldol (440 pai-ts) aiid oiie iiiol of iniline (465 parts) was added tliereto. The product -%vas stirred and then lieated under a reflux coildeiiser for - abotit ten hours. The prodtict ivas allowed to cool and then heatecl to 140' C. in the liqTensile uid, ivhereby water and soine or-aiiie liquid Nlols aldeliyde per niol amine strengtli Elongation 20 in lbs. in per cent. was distilled off, the liquid residue coiiiprisper sq. in. in(,, the condensation prodlict amotiiitin- to - ,ipproximatelyl420partsbywei(rht. @Vrtib1 ------------------------------------------- 2000 9 'o ber coinpos-tion containin(y this condensation 2 ------------------------------- ------------ :32SO 806 j t, 3 39(101 794 product and compr;sin- rubber-100 zinc 6 4270 725 I ---------------------- oxide-10, sulf ur-5, and condensation I)i-odE,v(ti??I)le O.-One mol (Si' pai-ts bv NN,ei(,Ilt) 'Ict-0.5 (parts bv weio,,ht) show the follo-@vin(r acceleratin(r action in press cures at of isoaiiivl, -imiiie ivas; tidded to 1;-) niols (1080 Ili , 0 F. 1),irt,,;) o@ I)tii-ifle(I I)iitvi-ic aldehvde aiid the iiiixttii-e lieate(i tin(ler a i,efltix coiidenser on @u Tensile the @teaiii I)ath for 20 lioiir,@, 163 I)arts bv Cure in minutes strength Elongation wei,,Iit of ivater' separ,,ited oiit ,in(I was rein lbs. per cent. per sq. in. Illove(l. The noii-aqtieotis laver was then dis'lled izp to 1,50' C. in the liqtiid whei-ebv 2 ti 30 --------------------------- ------------- 3270 750 p,,irts of ii-.itet- aiid 1,@, pai-ts of or(yanic liqiiid 60 ---------------------------------------- -- 3430 700 00 35 go 3710 688 ------------------------------------------ %vere reinoved. The i-esidtie, wei(rhiti(y 938 1).irts I)i, ii-ei(,,:Iit Nvas foiind to correspond to While the specific exaniple above given reth(, i-ea@tion prodtict of 14 mols of btitvric al- cite accelerators prepared from butyric aldedeliv(-Ie and 1 mol of isoamvlamiiie. A coiiihyde, it is to be understood that other alde40 I)osition cont-iinin(r this condensation I)rod- hydes nlay be employed. Heptaldehyde and uct and cotiil)risin@r rtibber-100, zinc oxide10, siilftir-,5 and cotidensation producto.,5 lsl_butyric aldehyde have been found to pro(parts bv iveialit) sliowed the followincr aedtice condeiisation product-s having accelerceleratiii fy -.iction iii press cures at 287o atinvalues substantially equal to these prepared froin butyric aldehyde. Cinnamie al43 Tensile deh de, croton aldehyde, and aldol may also 110 y strength Elongation be used in place of butyric aldehyde, althotigh Cure in minutes in lbs. in percent . per sq. in. saturated aliphatic aldehydes are preferred. The condensation of amines with low boil15 ----------------------------------- 85 20 ----------------------------------- '2 85 VI 82' in(y aldeliides mav be carried out under pres- iio 5 1 40 ------------------------------------------ 3810 775 stire, and this procedure may be - substitiited 60 ----------------------------------------- 3785 750 ivith respect to other al(lehydes iii place of .@ecelel-atoi-s liavin(, Iii-lier i-atios of aldeliv(le to ainine than that iiidicated above iiiav I)e obtaiiie(I I)v the process liereiiiabove di' scribed, a i,eactioii prodtict liaviiic,- an al(lelivde-,imiiie i-atio of 26 iiiols of aldehv(le t( I niol of aiiiine and I)o.,@sessin- satisfacioi,y teceleratin(r powers hai-iii(-, I)eeii pi@el)itred an(I Ci) tested. '-\Tuiiiei-otis test,@ of tlle efficacy of these acceleratol-s seeiiis to indicite that the coiiclen-,atioil 1)roducts liavin(r a ni,,ixiniiiiii acceleratin(r i-altie have an t" alclehyde-aiiiine ratio ran-inc- from 4-8 niols of aldehvde to C3 n "I 1 mol of aniine, varyiiio, with the aldeliyde the above described ti-eatment iinder a refltix -iines of the strai-lit eoiideiiser. Aliphatic aii trl or branclied cliain type as well as alipliatic 12C ainines liavin,-- cyclic groupinas are opei-ative in the prepai,ation of the accelerators of this apl)lication and the terni "aliphatic" is einployed in thi.,3 oeneric sense in the appended claims. This application is a division of my copendiiig application Serial No. 126,341, filed Jttly 31, 1926, which iii tiirn is a coiitinuation in part of my earlier application Serial No. 130 66,868, filed November 4, 1925.
