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Patented 2,256,253 16, 1941 UNITED STATES PATENT ’ OFFICE 2,256,253 _ PRODUCTION OF PROTEIN-CONTAINING UBEA-FORMALDEHYDE PLASTICS Oscar Neuss, Berlin-Charlottenburg, Germany No Drawing. Application April 6, 1938, Serial No. 200,422. In Germany August 11, 1933 10 Claims. ' (Cl- 260-6) the 'same poor homogeneity as the previously described products since the albumen material is only admixed in the urea condensation prod ucts instead of being distributed in the course The object of the invention is a process for the production of albuminoid-containingplastic masses from urea or its, derivatives and formal dehyde as well as products obtained according to this process. An important feature of the 5 of the condensation. The albumen material thus invention consists in the fact that there is ob- . behaves in the pressed product as sand behaves in concrete and the result of such non-homoge tained by a relatively simple process, hardenable neous masses is non-uniform swelling by the masses which can be formed by pressing, the action of moisture and unattractive surfaces. pressed bodies obtained as products in this .way having great homogeneity, good properties as 10 Further the pressed bodies are brittle and crack on boring. Finally, it has also been proposed, regards machinability, considerable elasticity, in order to secure better removal of water from permanence and resistance against atmospheric the reaction mixture of-urea and formaldehyde I influences and water. with heating, to admix therewith or to knead It is known to impregnate natural horn meal v15 dehyde and to dry, mill and to press the same. These condensates have been producedIin neu tral media or in the presence of ‘saturated am monia solutions. The horn meal, however, is in part'attacked by the additions of alkalis and a 20 with urea or thiourea or both and with formal partial break-down of the keratin results. The hot water. 3 ‘ _ It is also known to mix horn meal with a re action product of urea and formaldehyde in molten condition. In this case, however,v the horn meal is non-plastic by reason of the heat albumen containing materials, casein or wheat gluten. When in such a process horn meal is employed as the carrier material there arises as a result of the hardening of the horn albu men by heat and the formaldehyde, a non-plas tic horn material which cannot be used in a subsequent moulding operation. This action of formaldehyde upon albumen, in particular kera products so obtained show coloration and poor characteristics in particular after contact with therewith a swelling carrier material such as tin,‘ as a coagulating and hardening agent is 25 known. Pressed bodies of horn meal for exam ple can by treatment in formaldehyde be sub- a sequently hardened. The formaldehyde forms an outer hard surface on the keratin, which how-‘ ever hinders deeper penetration into the inner and the considerable formaldehyde liberation . caused thereby and the products obtained from a0 parts of the pressed bodies. Also the use of formaldehyde-binding sub stances as additions to urea horn meal condensa tion products does not, as has been described In‘ order to avoid these dif?culties, horn meal above, give satisfactory results, since these are has been added to aminoplast subsequently as filling material in the completed urea condensa 35 only stable in weakly alkaline media, but in acid solution, however, formaldehyde splits oil.’ and tion. The subsequent admixture of horn meal keratin must be moulded in acid medium. The with aminoplast products however, does not lead pressing of horn in alkaline medium leads to a to suf?oiently homogeneous bodies. The horn darkening of the pressed bodies and renders them meal remains as an extraneous body in the aminoplast and homogeneity is lacking which is 40 of less value due to the attack upon the albumen of the keratin by alkalis; , very undesirable when for example such ?nished It has now been found that all these disad pressed bodies come into contact with water. vantages, in particular also the attack of the The individual particles swell in differing degrees alkali upon the albumen substances of the horn and the object is unutilisable. It is similarly the case in further known processes according 45 meal and the decomposition of the keratin occa-. sioned thereby, can be avoided and press masses to which the albumen material is pressed to and pressed bodies of great homogeneity and gether in the hot with urea formaldehyde con these masses crack on boring and mechanical P working and have a poor appearance. a good properties can be obtained if the manufac densation products such as methylol derivatives ture .of protein- or albuminold-containing' plas of urethane, methylolurea or methylolamides which only in the hot pressing process split of! 50 tic masses from formaldehyde and urea com pounds is carried out in such manner that the formaldehyde and thereby eil‘ect hardening. This process is always difficult since the urea formaldehyde condensate added to the albumen material must previously-be made as such and urea compounds and a greater than equimolecu- ‘ ' lar proportion of formaldehyde are allowed ,to react upon each other in an aqueous ammoniacal isolated. Further ~the finished products show 55 solution reacting weakly alkaline toward litmus, 2 -, 2,256,253 without external heating (pm-condensation), and thereafter the mixture made weakly acid toward litmus (the reaction product being still in the water-soluble state) and treated with the protein or albuminous material, whereupon the condensation mixture is dried and pressed hot at temperatures above 100° C. For, in the ?eld of urea formaldehyde systems there exist partic-i ._ ular compounds that is to say condensates, which fundamentally the horn meal is thoroughly soaked through and after attaining the necessary degree of dryness is pressed; Instead of the addi tion of acid also a weakly acid horn meal that is to say horn meal bleached with S0: can be used. The faintly acid character of a horn meal bleached with $02 su?ices in some circumstances to give to the labile ammoniacal resin condensate a quite weakly'acid character without causing, can be mixed with keratin even in weakly acid 10 by a‘ too acid reaction, a precipitation and solutions without any noticeable proportions of, hardening of the mass. - The keratin does not free formaldehyde acting in a coagulating man ‘coagulate prior to the pressing and the material ner upon the pressed material but which, how can be readily formed into cakes and shows a ever, in the subsequent hot pressing process on considerable plasticity in the hot pressing the one hand lead to resin formation and on the process. The hardening of the pressed goods is other hand to the splitting-off of formaldehyde and therewith hardening of the keratin, albumen. Primarily acid or neutral urea-formaldehyde splitting o? ofvformaldehyde by the high tem perature and simultaneously the high pressure condensates are excluded in this connection as utilised. effected in the pressing process by the partial these, even at ordinary pressure and temperature 20 conditions, split o? formaldehyde and unfavour ably influence the albumen by prematurely hard- . . Instead of urea also urea derivatives, for ex ample, thiourea or mixtures of - urea with urea derivatives can be employed. Also other al bumens can be used‘ which,-as in the case of ening it.‘ Further, such urea-formaldehyde mix tures separate out solid precipitates of conden keratin, must be protected from the premature sates in a short time. On the other hand, suit 25 action of free formaldehyde prior to the pressing. able ammoniacal condensates practically do not In the present process it is thus not a question show this precipitationv even after addition of of a known mixing. process in which. all possible acid or, if they do, only after a disproportionally substances, among which keratin and albumens long period of action since they bind the free can also be included, can be distributed as ?ll formaldehyde and even after subsequent weak 30 ing materials in the aminoplast material or in acidi?cation, and this is the decisive point, even which inverted aminoplasts are admixed with with mineral acid in the cold, no precipitate re such press material. Rather it is a question of sults. Accordingly it is thus possible for the a condensation or hardening process of the production of binding and hardening materials aminoplast combined with a hardening process for keratin to commence with a weakly ammo niacal urea-formaldehyde condensation mixture 35 for the keratin, that is to say an improvement of the properties thereof by the exchange action of particular suitable labile acid, bodies of the formaldehyde urea condensation system upon the albumen material to be bound, and thus par the horn meal in the pressing process itself. In ticularly the horn meal, is intimately admixed 40 the same way the present process has nothing to .or steeped with acidi?cation, is then dried and do with. the known proposal to dissolve casein if desired milled and the ?nal binding of the in urea with or without additions of alkali then constituents is then effected only by the conclu to pour in free formaldehyde and by subsequent sion, in the hot pressing, of the previously in strong acid precipitation of the solution to obtain ' completely e?ected condensation of the pressed the solid condition. The disadvantages of this material in faintly acid condition. The main .45 method of operation are threefold, namely, the tenance of the molecular proportion on the one destruction of the albumen by the attack of hand and the hydroxyl and hydrogen ion con alkalis in the solution, the addition of free forms centrations on the other hand is always of de aldehyde whereby coagulation of the albumen cisive signi?cance as regards the labile charac cannot be avoided and ?nally the use of a solu 50 ter of the condensate to be employed for the tion which is not labile and which is caused to hardening. ~ precipitate by addition of acid. In this solidi?ca In the initially ammoniacal mixtures, for ex-, tion further free formaldehyde is split off which ample, one molecule of urea is dissolved in about can react in a coagulating manner upon the al 1.2 molecules of formaldehyde in aqueous solu bumen even before the hot pressing. According tion. Free formaldehyde is rendered non to' the process of the present invention, on the which for each molecule of urea contains more than one molecule of formaldehyde. With this ' deleterious by ammonia, that is to say, is only _ other hand, the albumen is in no case dissolved. so far neutralized that the solutionris faintly By the solution of horn in urea (possibly under alkaline and the free formaldehyde is‘ rendered pressure,_with alkalis etc.) a breakdown of the inactive by the ammonia. Hexamethylenetetra keratin occurs which results in considerable de mine is therefore not suitable. An unnecessary 60 terioration in the water resistance of the ?nished, excess of ammonia is not recommended since in pressed objects. Such pressed objects acquire the pressing operation the amines developed blemishes even by the action of cold water for thereby. unsatisfactorily in?uence the keratin. I a long time. In boiling water the surface there The solutions after standing in the cold for some of becomes rough to wholly deformed. It is thus days should no longer smell or taste of formal important in the present process that on the one hand the albumen prior to coagulation is to a for .use since the horn meal on pressing in. far reaching extent‘ protected from free formal . alkaline medium subsequently darkens, becomes I dehyde and on the other hand from the attack brown, and suffers considerably from the action of free alkaline components (urea and ammonia) of the alkali under heat and pressure. .The con 70 of the labile condensation solution by acidi?ca-‘ ,densate must therefore be slightly acidi?ed. tion. Finally the solution must be so labilethat Even the slight acidi?cation in. the cold should a mild acidi?cation under usual conditions can not give any precipitate. - With such a solution bring about no solidi?cation of the aminoplast the. horn meal‘is mixed in such proportion that 75 condensate, the polymerisation and hardening dehyde. , Such a solution is however not suitable 3 2,256,253 process taking place exclusively in the hot press product dried and, if desired after milling, sub itself. jected to the hot pressing. . . I Example 5.--50 grs. of urea and 10 grs. of thiourea are dissolved in 150 grs. of 40% formal dehyde and then neutralised with ammonia un til the solution reacts faintly alkaline towards litmus. The solution is allowed to stand for Prior to or during the condensation, ?lling materials, plasticising materials, colouring mate rials and other additions can be introduced into the reaction mass. .Also certain proportions of . phenols can be employed as components of the condensation. The horn meal can ?rst be swollen in water and then added to the components of 3 hours. Then 160 grs. of this solution which is faintly acidi?ed with phosphoric acid is mixed the aminoplast. It is possible, however, also 10 with 25 grs. of gelatine, the product dried and then, if desired after milling, subjected to the to proceed by allowing the-horn meal to swell in the solution of urea and then ‘adding the form hot pressing. aldehyde. The working up to the dried products Example 6.—50 grs. of urea and 10 grs. thiourea are dissolved in 150 grs. of 40% formal is effected in the usual manner. From the mass ' obtained after drying, ?nished products can be 15 dehyde and then neutralised with ammonia un til the solution reacts faintly alkaline towards obtained in a single operation by hot pressing. litmus. The solution is allowed to stand for 3 It is also possible, however, to proceed by ?rst hours. 160 grs. of this solution which is faintly pressing or forming into cakes at ordinary or acidi?ed with phosphoric acid is mixed with 50 moderate temperature so as not to cause thermo setting, followed by a ?nal pressing in the hot 20 grs. of commercial defatted casein powder, the press. product dried and, if desired after milling, sub- ' The process can be conducted with or jected to the hot pressing. As already indicated hereinabove, there may be employed in my improved process urea itself without the presence of ?lling materials. In the following, a number of examples are given by way of illustration. In the, hot press the press material resulting can be formed into 25 and thiourea, as well as other urea derivatives whose condensation reaction with formaldehyde is substantially equivalent to that of urea and all kinds of objects, for example knobs, umbrella handles or the like. ' ' Example 1.—60 grs. of urea are dissolved in‘ ’ thiourea. . - . 120 grs. of 30% aqueous formaldehyde solution. I claim: It is then neutralised with ammonia until the 30 1. Process for the manufacture of plasti solution shows a faint alkalinity towards litmus. The solution is allowed to'stand for 3 hours. 150 grs. of the solution are then mixed with 50‘ grs. of horn meal which has been treated with 4 ~ masses from a urea and formaldehyde and con taining protein material, comprising causing a. urea and a molecular excess of formaldehyde to ‘ react upon each other without external heating sulphurous acid, and the paste dried carefully 35 in an aqueous ammoniacal solution which is weakly alkaline towardlitmus, acidifying the re in the air or at moderate temperatures, the dried action mixture until it is weakly acid toward product, if desired after milling, being subjected litmus, mixing the same with a protein material, to hot pressing at temperatures above 100° C., and thereafter drying the reaction mixture. preferably at 130° C. If desired, the ground 2. Process according to claim 1, wherein the product can ?rst be subjected to a slight pressure 40 protein component is. horn meal. at relatively low temperature to form it into 2 3. Process according to claim 1, wherein the coherent, but not yet hardened cake, after which it may be shaped and hot-pressed as stated, the ?nal condensation taking place during such hot pressing. ' protein component is horn meal which has been - caused to swell in water prior to mixing with 45 the other reaction components. 4. Process according to claim 1, wherein the Example 2.—-60 grs. of urea are dissolved in reaction under acid conditions is conducted with 150 grs. of 40% aqueous formaldehyde solution cooling of the reaction'mass. and then neutralised with ammonia until the 5. Process according to claim 1, wherein the solution reacts faintly alkaline towards litmus. The solution is allowed to stand for 3 hours. 50 protein component comprises bleached horn meal containing suf?cient $02 to impart to the :Thereupon 160 grs. of this solution which, in de reaction mixture a weakly acid reaction toward pendence upon the character of the horn meal utilisedj has been acidi?ed to give an acid re 6. A thermo-setting, protein-containing mold action to litmus, is mixed with 50 grs. of horn litmus. meal, the product dried and, if desired after mill ing subjected to the ‘hot pressing process de scribed above. Emample 3.-—50 grs. of urea and 10 grs. of thiourea are dissolved in 150 grs. of 40% aqueous . - ' 55 ing composition capable of resisting the action of hot water when in the hardened condition and comprising the dried acidi?ed mixture of a pro tein material and an initial, water-soluble con densate of a urea and a greater than equimolec formaldehyde solution and then neutralised with 60 ular proportion of formaldehyde in weakly ammonia until the solution shows a faint alkaline ammoniacal solution, substantially no degrada tion of the protein material having taken place, reaction towards litmus. The solution is allowed said protein material being in the substantially to stand for three hours. 160 grs. of this solu tion which is faintly acidi?ed with phosphoric unhardened condition, said composition being acid is then mixed with 50 grs. of horn meal, 65 capable on molding at elevated temperature and pressure of causing hardening of the protein the product dried, and, if desired after milling, is subjected to the hot pressing as above. material by release of excess formaldehyde and Example 4.-—40 grs. of urea and 20 grs. of thiourea are dissolved in 150 grs. of 40% aqueous ' becoming infusible and insoluble. 7. A thermo-setting molding composition con formaldehyde, then neutralised with ammonia 70 taining keratinous material uniformly distributed therein and capable of resisting the action of hot until the solution has a faintly alkaline reaction towards litmus. The solution is allowed to stand for 3 hours. Then 160 grs. of this solution, water when in the hardened condition and com prising the dried acidi?ed mixture of horn meal and an initial, water-soluble condensate of urea which is acidi?ed faintly with phosphoric acid, is mixed with 50 grs. of defatted horn meal, the 75 and a greater than equimolecular proportion of '4 2,256,253 Iormaldehyde‘in a. weakly alkaline ammoniacal solution, the horn meal being substantially un a?’ected by the ammonia and being in the sub-‘ stantially unhardened condition, said composi tion, being capable on molding at elevated tem perature and pressure of liberating su?icient free formaldehyde to e?ect hardening of the kerati ‘ ' nous'material and becoming infusible and. in soluble. vproportion of formaldehyde to urea is approxi mately 1.2:1. 9. Process according to claim 1, vwherein the ' initial condensation of the urea and formalde- - hyde in the aqueous ammoniacal solution is con ducted‘ for about three hours. ' l l _ 10. A composition as set forth in claim 6, wherein the urea is urea itself and wherein the molecular proportion .of formaldehyde to urea 8. Process according to claim 1, wherein the '10 is approximately 1.2:1. urea is urea itself and wherein the .molecular - - OSCAR NEUss.