Alpha, alpha-bis-(2-hydroxyphenyl)-diisopropyl benzenes
United States Patent 11 Oertel et al.  
 [ Apr. 1, 1975 [73] Assignee: Bayer Aktiengesellschaft,  
 Leverkusen, Germany 22 Filed: June 13, 1973 21 Appl. No.: 369,507  
 Related U.S. Application Data [62] Division of Ser. No. 122,557, March 9, 1971, Pat.  
 [30] Foreign Application Priority Data Mar, 14. 1970 Germany 2012285 [52] U.S. Cl. 260/619 B, 260/619 D [51] Int. Cl. C07c 39/12 [58] Field of Search 260/619 A, 619 R, 619 B,  
 [56] References Cited UNITED STATES PATENTS Hunter et a1 260/619 A X 3,393,244 7/1968 Broderick et al. 260/619 A X 3,414,542 12/1968 Vitrone 260/619 A X 3,642,669 2/1972 Nast et a1 260/45.95  
 Primary Examiner-Bernard Helfin Assistant Examiner-Norman Morgenstein Attorney, Agent, or Firm-Plumley &amp; Tyner [5 7] ABSTRACT The invention relates to a process for stabilising polyurethanes, particularly polyurethane elastomer threads and films, against degradation and discoloration under the action of light or UV radiation, oxygen, atmospheric constituents (e.g. nitrogen oxides) and heat by the addition of bisphenols.  
 2 Claims, No Drawings A LPHA, ALPHA-BIS-(2-HYDROXYPHENYL)- DIISOPROPYL BENZENES (5H CH OH R as stabilisers, in which formula R represents a straight chain or branched C to C alkyl radical, a C to C cycloalkyl radical, if desired substituted by lower alkyl radicals, or a C to C aralkyl radical, or if desired a stabiliser mixture of the above mentioned bisphenols and UV stabilisers preferably derivatives of a 2-(2&#39;-hydroxyphenyl)-benzotria2ole.  
  Polyurethanes prepared from higher molecular weight polyhydroxyl compounds, polyisocyanates and chain lengthening agents, which polyurethanes are widely used in the form of foam resins, elastomers, coatings, films or clastomer threads, are unstable to light and to some extent also to air at elevated temperatures, the degree of instability depending to some extent on the components from which they have been prepared. As a result of this instability, their mechanical properties deteriorate and in many cases there occurs in addition a severe discoloration of the polyurethanes.  
  Many attempts have been made to protect the polyurethanes against discoloration and degradation by the addition of known antioxidants, e.g. those based on phenol, but such stabilisation is generally not sufficient.  
  Thus, for example, phenols such as 4,4&#39;-alkylidenebis-(6-tertiary butyl)-m-cresol, 2,6-ditertiary butyl-4- methyl-phenol or 4,4&#39;-methylene-bis-(2,6-ditertiary butyl phenol) have been tested for use as stabilisers but they either impart an unwanted colour to the products right from the start or fail to protect the products against discoloration under the action of light or atmospheric constituents. Polyphenols such as 1,3,5- trimethyl-2,4,6-tris-( 3,5-ditertiary butyl-4-hydroxybenzy1)-benzene have also been proposed as stabilisers (DAS No. 1,243,866). In addition, numerous phenolic compounds have been mentioned which are said to be suitable for stabilising polyurethanes if used together with hydroxybenzophenones (DAS No. 1,106,490). The effect of these phenolic stabilisers, however, is not sufficient. They are not wash-resistant and they have a colour of their own which is unacceptable, e.g. if they areused in white elastomer threads.  
  A new class of phenolic stabilisers has now been found which by virtue of their particular structure enables highly effective stabilisation of polyurethanes to be achieved. These stabilisers are themselves colourless, cause no discoloration in polyurethanes and provide substantially better protection to discoloration and degradation under the influence of visible and/or UV light and/or atmospheric constituents (such as oxygen, nitric oxide and waste gases from combustion). in addition, the substances are readily soluble in polyurethane elastomers and do not form crystalline deposits on the surface.  
  The invention also relates to the use of 0.01 to 10% by weight of bisphenols of the general formula I:  
  H n 111 H 08 R CH CH in which R represents a straight chain or branched C to C alkyl radical (preferably a C alkyl radical), a C to C cycloalkyl radical which may be substituted by lower alkyl radicals, and C to C aralkyl radicals. as stabilisers to stabilise segmented polyurethane elastomers against discoloration and deterioration of their mechanical strength.  
  The following are given as examples of radicals R: methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, amyl, isoamyl, hexyl, isohexyl, isooctyl, isononyl; cyclopentyl, cyclohexyl, 4- methylcyclohexyl, ot-methylcyclohexyl; benzyl. a-methylbenzyl and a,a-dimethyl benzyl.  
  The bisphenols used are preferably bisphenols of the following general formula:  
 R OH (2H H R c I I CH CH in which R represents a methyl, t-butyl, cyclopentyl or cyclohexyl group, these bisphenols being used in quantities of 0.05 to 5.0%- by weight, based on the polyurethane elastomers. 0.2 to 3% by weight of the following stabilisers, based on the polyurethane elastomers, are advantageously used:  
 an n 0H3 :5 n H CH3 CH3 1) 11 ca. ca 11 ca e 013 f i on. (In) on 0H3 s 3 3 4 OH (:H :3 OH CH CH CH CH c I 3 I 3 I I \-cc- -on (v11) cit 011 (IV) c11 ca CH CH These experiments show, among other things, that the phenols conventionally used as stabilisers, which H CH CH OH are similar in structure to the phenols represented in the above formulae but which instead of the C(CH;,) 2 n group have only a CH group between the benzene (21-1 611 rings, e.g. bisphenols or trisphenols such as:  
 . l5 0H H (7) 3\ H H 3 CH C CH C-CH 3 2 3 ca CH The a, a(-bis-(2-hydroxyphenyl)-l,4-diisopropyl benzenes used according to the invention, which will 3 (VIII) hereinafter be referred to briefly as bisphenols, are new compounds and can be prepared by the reaction of r r a,oz-dihydroxy-l,4-diisopropyl benzene with ortho- 0H substituted 4-methylphenols in the presence of acid de- A hydration catalysts, water being split off in the process; 35 3 3 e.g. according to the following reaction equation:  
  a c 011 R I I 2 4- H04: &#39;-OH --9 H on C CH  3 3 011 cn cum H.  
 OH OH lowing) when exposed to UV light and are therefore 3 unsuitable for stabilishing colourless polyurethanes. In  
  CH OH R 3 R differ from the stabilisers according to the invention in 9 2 2 40 that they themselves undergo strong discoloration (yeladdition, the bisphenols according to the invention shown better stabilisation against degradation than, for v in which formula, R has the meaning already given for example, the known phenolic stabiliser 1,3,5-trimethylformula I. 2,4,6-triu-(4-hydroxy-3,S-ditertiary butyl benzyl) ben- The substantial improvement which can be obtained zene (according to DAS No 1,243,866). A relatively by using the new bisphenols is demonstrated by comslight modification of the structure of the phenols acparison tests in which they are compared with a comcording to the invention, e.g. a shift of the alkyl radimercial mononuclear phenol 2,6-ditertiary-butyl-p- 5O cals, results in a substantial reduction in the stabilisacresol, a binuclear phenol methylene-bis-(2-hydroxy-3- tion effects and, in some cases, yellow discoloration is tertiary butyl-5-methyl phenol) and a trinuclear phenol observed (see comparison tests). 1,3,5 -trimethyl-2,4,6-tris-( 3,5-ditertiary butyl-4- The efficient stabilising effect of the special phenolic hydroxybenzyl) benzene (X). Two other examples, in compounds according to the invention, which is so sigwhich a bisphenol unsubstituted in the ortho-position nificant for polyurethane elastomers, was unexpected (VI) and a bisphenol having OH groups in the pand could not have been predicted. position (VII) (as described in Belgian Pat. Specifica- Suprisingly, the effect of the phenols is not entirely tion No. 604,516) were used, demonstrate the strict dedependent upon the presence of a tertiary alkyl radical pendence between the action and the constitution of in the ortho-position to the hydroxy group, and comthe bisphenols. pounds which have a secondary or primary alkyl radical are equally efficient.  
 The invention also relates to the use of 0.05 to 5.0%  
 on by weight of a stabiliser mixture consisting of:  
 &#39; E Z a. bisphenols according to the invention and, in addi- (71) tion 08 b. 2-(2&#39;-hydroxyphenyl)-benzotriazoles for stabilising polyurethanes.  
  3 3 Bisphenols of the following formula I are used:  
  5 on H 911 on R 0 0 l&#39; I 0H3 (m in which R has the meaning already given.  
  2-(2&#39;-Hydroxyphenyl)-benzotriazoles of the following formula are used:  
  H (II) x \n in which X represents a hydrogen atom, an alkyl group or a halogen atom,  
 Y represents a hydrogen atom, a C to C alkyl radical or an alkylene radical having hetero atoms, preferably a tertiary alkyl radical such as tertiary butyl, tertiary amyl or tertiary dodecyl, and  
 R represents hydrogen or a C to C alkyl radical, e.g. methyl, ethyl, isopropyl, tertiary butyl, tertiary amyl, tertiary octyl or tertiary dodecyl.  
  The mixture is used in proportions by weight of compound A to compound B of 1:10 to 10:1, the polyurethane elastomers thereby undergoing a synergistic stabilisation against discoloration and degradation under the action of light, heat and atomospheric constituents.  
  The use of 2-(2&#39;-hydroxyphenyl)-benzotriazoles as stabilising additives to polymers is known per se but is entirely inadequate when used as the only means of 40 OH I in which X represents a hydrogen or chlorine atom,  
 Y represents a hydrogen atom or a C to C alkyl radical, preferably a tertiary alkyl radical, such as tertiary butyl or tertiary amyl or an N-methylenephthalimido radical, and  
  R represents a hydrogen atom, a C to C alkyl radical, e.g. methyl ethyl, isopropyl, tertiary butyl or tertiary amyl radical.  
 The following compounds are given as examples of 5 light protective agents based on 2-(2&#39;-hydroxyphenyl)- butyl-S-methylphenyl butylphenyl benzotriazole,  
 2-( 2 -hydroxy-3 ,5 &#39;-ditertiary butylphenyl benzotriazole,  
 2-( 2 &#39;-hydroxy-3 ,5 -ditertiary butylphenyl )-5- chlorobenzotriazole,  
 2-(2-hydroxy-3,5&#39;-ditertiary amylphenyl)- benzotriazole,  
 2-(2 -hydroxy-3 ,5 -ditertiary amylphenyl )-5- chlorobenzotriazole,  
 2-(2 -hydroxy-3 ,5 -ditertiary octylphenyl benzotriazole,  
 2-(2&#39;-hydroxy-3&#39;,5-ditertiary chlorobenzotriazole, and  
 2-( 2 -hydroxy-3 -N-methylene-phthalimido benzotriazole.  
  Other suitable hydroxyphenyl benzotriazoles are mentioned, for example, in German Auslegeschrift No. 1,213,408; 1,213,409 and 1,213,410 and in US. Patent Specification No. 3,213,508. Known polyurethane stabilisers (see, for example, German Auslegeschrift No. 1,157,386) may also be added.  
  The elastic polyurethanes which are to be stabilised, which may be in the form of foams, can be obtained by known processes and from known starting materials. The polyurethanes are generally prepared by reacting higher molecular weight polyhydroxyl compounds (e.g. polyesters or polyethers having a molecular weight of about 500 to 5000, melting points preferably below 60C) with aliphatic, araliphatic or aromatic polyisocyanates (preferably aromatic diisocyanates such as toluylene diisocyanate or diphenylmethane-4,4&#39;- diisocyanate) and so-called chain lengthening agents, i.e. low molecular weight compounds (molecular weight e.g. 18 to 400) which have two or more groups that are reactive with isocyanate (e.g. water, low molecular weight diols, diamines, dihydrazides or similar compounds, e.g. aminoalcohols, aminohydrazides, hydroxy hydrazides, aminosemicarbazides, semicarbazido hydrazides, semicarbazido carbazic esters or mixtures of these chain lengthening agents) in a single stage or in a multi-stage process in the melt or in solvents. Numerous known processes or modifications thereof may be employed for this reaction.  
  The following are given as examples of starting materials: polyesters of adipic acid and dialcohols containing 2 to about 10 carbon atoms, preferably those containing more than 5 carbon atoms, the dialcohols, if desired, being also used for lowering the melting points of octylphenyl)-5- the polyesters in the mixture; polyesters of caprolactone and dialcohols, polyalkylene ether diols, espccially polytetramethylene ether diols, polytrimethylene ether diols, polypropylene glycol or the corresponding copolyethers. The diisocyanates used are preferably aromatic diisocyanates, such as diphenylmethane-4,4&#39;- diisocyanate, tolylene diisocyanate, araliphatic diisocyanates such as m-xylylene diisocyanate or aliphatic diisocyanates such as hexamethylene diisocyanate and dicycloheXylmethane-4,4&#39;-diisocyanate. These starting materials are reacted together, if desired, with the addition of other dialcohols, to form NCO prepolymers which preferably have the structure indicated in Belgian Pat. Specification No. 734,194. Suitable chain lengthening agents, which may be used as mixtures or in a stepwise reaction. include water and/or dialcohols or trialchohols such as butane diol and p-xylylene glycols, trimethylol propane. aminoalcohols such as ethanolamine, diamines such as diphenylmethane-4,4- diamine, 3.3&#39;-dichloro-diphenyl-methane-4,4- diamine, but preferably aliphatic diamines such as ethylene diamine, 1,2 propylene diamine, isophorone diamine, metaxylene diamine and hydrazine or dihydrazides such as carbodihydrazide, oxalic acid dihydrazide, glutaric acid dihydrazide, pimelic acid dihydrazide, terephthalic acid dihydrazide or semicarbazidohydrazides such as B-semicarbazide alanyl hydrazide; if desired, theey may be used as mixtures of chain lengthening agents.  
  The polyurethanes to be stabilised are preferably of the type which, in addition to urethane groups, also contain NHCONH groups obtained by reacting isocyanate groups with water and/or with compounds containing NH: end groups (e.g. diamines, dihydrazides, carbodihydrazide, semicarbazido hydrazides or hydrazine) and which have a substantially linear, segmented molecular structure, are soluble in highly polar solvents such as dimethyl formamide or dimethyl acetamide before they are shaped and whose characteristic segments may be represented by the following formula:  
 which may be obtained by reacting an NCO prepolymer OCN.Y.NCO with a chain lengthening agent H N.X.NHX.NH2.  
  The radical Y of the NCO prepolymer may, for example, have the following structure:  
 or another of the usual structures (see Belgian Pat. Specification No. 734,194).  
 In the above formula R represents a divalent aliphatic, araliphatic or aromatic radical (of a diisocyanate),  
 D represents the radical ofa higher molecular weight polyhydroxyl compound having a molecular weight of 500 to 5000 and melting points below 60C without its terminal hydroxyl groups (e.g. the radical of a polyalkylene ether, polyester, polyacetal or poly- N-alkyl urethane),  
 X represents the radical ofa divalent chain lengthening agent which has terminal NHg groups but without the terminal NH groups, e.g. an aliphatic, araliphatic, aromatic or heterocyclic radical, an HN-- COalkylene-CONH radical, an NH- CONH(CH CONH radical, a bond between two N atoms. Munich,  
 The synthesis of such polyurethane (ureas) has been fully described, e.g. in German Auslegeschrift No. 1,270,276 and in Belgian Pat. Specification No. 734,194. Polyurethane foam resins can be prepared by known processes and formulations, e.g. with the addition of stabilisers to the starting components (e.g. polyethers) (see e.g. Kunststoff-Handbuch Volume Vll, Polyurethane, publishers Carl Hanser Verlag Munic, 1966, pages 440 to 457, 504 to 531).  
  The stabilisers may be incorporated in the polyurethanes by any method adapted to the technical process requirements. The simplest method consists of adding the stabilisers, if desired in the form of solutions, to solutions of the polyurethanes, e.g. their solutions in highly polar solvents such as dimethyl formamide or dimethyl sulphoxide which is in the form in which they are preferably used for spinning, coating or coagulation purposes. Alternatively, the stabilisers may be incorporated in the melts or plasticised polyurethane sheets by means of suitable mixing devices such as kneaders or rollers. In the case of elastomer threads, the stabilisers may also be applied to the surface together with the dressing.  
  Another possibility lies in adding the stabilisers to the starting materials used for the preparation of the polyurethanes and only then carrying out the polyurethane synthesis. Thus, for example, bisphenol compounds are soluble in higher molecular weight polyhydroxyl compounds (e.g. polyesters or polyethers). The polyurethane syntheses, e.g. production of foam resins or elastomers, can then be carried out with such polyesters or polyethers which already contain stabiliser. The stabilisers may also be added to the diisocyanates or to the prepolymers of higher molecular weight polyhydroxyl compounds and (excess molar quantities) of diisocyanates before the formation of polyurethane is carried out, e.g. by spinning it into aqueous diamine solutions. Discoloration of the polyurethanes can be prevented during synthesis of the polyurethanes by using the stabilisers in the reaction of NCO prepolymers with chain lengthening agents such as diamines, hydrazine, hydrazides or similar chain lengthening agents in highly polar solvents such as dimethyl formamide or dimethyl acetamide. The quantity of stabilisers added is 0.01 to 10% by weight, preferably 0.2 to 3.0% by weight.  
  The light-protective action is enhanced by adding the stabilisers according to the invention to polyurethanes which contain 0.02 to 1 mol, preferably 0.05 to 0.3 mol, per kg of elastomer substance, of reactants which contain aliphatically substituted tertiary amino groups. Examples of such reactants are glycols, diamines, dihydrazides or polyesters or polyesters containing tertiary amino groups, e.g. N,N-bis-(B-hydroxypropyl)- methylamine, N,N-bis-(B-hydroxyethyl)-piperazine, N,N&#39;-dimethyl ethylene diamine, N,N&#39;-bis-(&#39;yaminopropyl)-ethylene diamine, N,N-bis-(&#39;yaminopropyl)-piperazine or polyethers which contain tertiary amino groups, or polyesters which contain tertiary amino groups, which compounds are prepared from dialcohols which contain tertiary amino groups.  
 Preparation of the bisphenols of the general formula 1 according to the invention Synthesis of the bisphenols may be carried out by reacting a,a-dihydroxy-l,4-diisopropyl benzene with ortho-substituted 4-methylphenols (water being split off) in the presence of acid dehydration catalysts such as p-toluene sulphonic acid, phosphoric acid, sulphuric acid, hydrochloric acid or strongly acid ion exchangers.  
  The water formed on condensation may, if desired. be removed by azeotropic distillation. Suitable solvents, c.g., are benzene, cyclohexane, cleaning petrol. toluene, xylene and chlorinated hydrocarbons such as chloroform, carbon tetrachloride and tetrachloroethylene.  
  Another process for the preparation of the bisphenols according to the invention consists in condensing a,a&#39;-dihydroxy-l,4-diisopropyl benzene with 2 molecules of p-cresol with elimination of water by the process mentioned above and then alkylating, cycloall ylating or aralkylating the free ortho-positions with suitable olefins or carbinols.  
  Processes of this type are known as such and do not constitute a subject of the present invention.  
  The following examples serve rather to explain more fully the preparation of the bisphenols according to the invention and of compounds VI and VII used for comparison tests.  
  a,oz-Bis-( 2-hydroxy-3 ,S-dimethylphenylH ,4- diisopropyl benzene (Compound II on page 4) C ,.H O Molecular weight: 402. Calculated: C. 83.58: H. 8.46: O. 7.96. Found: C. 83.9; H. 8.7; O. 7.9.  
  a,a&#39;-Bis-( 2-hydroxy-3-tertiary butyl-5-methylphenyl)-1,4-diisopropyl benzene: (Compound III on page 4) 164 g (1 mol) of 2-tertiary butyl-p-cresol, 49 g (0.25 mol) of a,a-dihydroxy-l,4-diisopropyl benzene and 2.5 g of .p-toluene sulphonic acid in 400 ml of cleaning petrol were boiled in a water separator for one hour, 9 ml of water being separated. 2 g of ammonia were introduced to neutralise the catalyst. The mixture was filtered and completely distilled under vacuum at temperatures of up to 100C. On the addition of methanol, a colourless powder precipitated. This was filtered off under suction and dried. M.p. 105C.  
 C ,,H,,.0, Molecular weight: 486. Calculated: C. 83.95; Found: C, 83.9;  
 380 g(2 mol) of 2-cyclohexyl-p-cresol, 97 g (0.5  
 mol) of a,a&#39;-dihydroxy-l,4-diisopropyl benzene and 5 g of p-toluene sulphonic acid in 600 ml of cleaning petrol were boiled in a water separator for one hour, 18 ml of water being separated. 2 g of ammonia were introduced at 50C. After filtration, 500 ml of methanol were added to the solution, colourless crystals being precipitated.  
 M.p. 204C.  
 C -;,,H.-.&#34;O Molecular weight: 538. Calculated: C. 84.76: Found: C. 84.1:  
 lulu  
 a, a-Bis-( 2-hydroxy-5-methylphenyl )-l ,4-diisopropyl benzene: (Compound V] on page 6) 216 g (2 mol) of p-cresol, 97 g (0.5 mol) of a,a&#39;-dihydroxy-l,4-diisopropyl benzene, 5 g of ptoluene sulphonic acid and 500 ml of cleaning petrol were boiled in a water separator for 1 hour. 18 ml of water being separated. The crystallised product was removed by suction filtration at 0C and recrystallised from benzene. Colourless crystals, m.p. 1830C.  
 C H o- Molecular weight: 374. Calculated: C. 83.42;  
  H. 8.02; Found: C. 83.7; H. 8.0;  
  a,a-Bis-( 4-hydroxy-3,S-dimethylphenyl l ,4- diisopropyl benzene: (Compound VII on page 6) 122 g 1 mol) of 2-hydroxy-l ,3-dimethyl benzene, 49 g (0.25 mol) of a,a-dihydroxy-l,4-diisopropyl benzene, 2.5 g of p-toluene sulphonic acid and 300 ml of cleaning petrol were boiled in a water separator for 1 hour, 9 ml of water being separated. l g of ammonia was introduced into the hot solution. After filtration and when the solution was cold, 250 ml of petroleum ether were added and the crystal paste which precipitated was removed by suction filtration at 0C and recrystallised from toluene. Colourless crystals, mp C.  
 C ,,H O Molecular weight: 402. Calculated: C, 83.58;  
  46; Found: C, 83.6; 6,  
  The following examples are to further illustrate the invention without limiting it.  
 Example 1 500 Parts of a polytetramethylene ether diol (molecular weight 1010), 104 parts of N.N-bis-(B- hydroxypropyl) -N-methylamine, 1822 parts of diphenylmethane4,4&#39;-diisocyanate and 1740 parts of chlorobenzene were heated to 60C to 68C for 68 minutes and then cooled to room temperature. 6450 Parts of this NCO prepolymer solution (2.05% NCO based on solid substance) are introduced in the course of 10 minutes with vigorous stirring into a fresh suspension prepared by the addition of 75 parts of solid carbon dioxide to a solution of 73.7 parts of ethylene diamine and 4.68 parts of l,2-propylene diamine in 13.440 parts of dimethyl formamide, a homogeneous, slightly yellowish elastomer solution being obtained which is pigmented by the addition of 4% by weight (based on light (Fadeometer) (see Table 2). Portions of these elastomer solutions are spun by the usual dry spinning process and the threads are exposed to light in a Xenon test with and without the addition of stabiliser (see Table 1). If the 2% by weight of stabiliser are not added subsequently to the finished elastomer solution but dissolved in dimethyl formamide together with diamines and the elastomer solution is then prepared from the NCO prepolymer, a colourless elastomer solution is obtained which does not undergo discoloration when exposed to air. After formation of the films and exposure of the threads to light, the stabilising effect against degradation of mechanical strength under exposure to light was found to be practically identical.  
 Example 2 The bisphenols and comparison stabilisers shown in the table are dissolved in the elastomer solution (acelastomer solid substance) of titanium dioxide (rutile). 20 cording to Example 1 in the quantities indicated. After The elastomer solution (viscosity 610 poises) is made casting of the elastomer solution and drying to produce up into films in separate portions with and without the films, the films are cut up into strips which are then exaddition of stabiliser in the usual manner and the films posed in the Fadeometer for the length of time indiare cut up into threads which are then exposed to UV cated.  
 Table 1 Loss in strength of elastomer threads produced by the dry spinning process (individual denier approx. 10 dtex. total denier approx. 220 dtex) after Xeno test exposure Before Exposure 72 Hours 145 Hours Ultimate Ultimate Ultimate tensile Elongation tensile Elongation tensile Elongation strength at break strength at break strength at break g/dtex 71 g/dtex 71 g/dtex 7: Remarks without 0.59 506 0.17 372 no longer measurable stabiliser (colourless) yellowish yellowish yellow l /r stabiliser II 0.6] 500 0.40 480 yellowish only (colourless) colourless colourless after more than 200 hours 2% stabiliser ll 0.66 510 0.52 525 yellowish only (colourless) colourless colourless after about 225 hours 1.33% stabiliser 0.66 510 0.63 510 0.60 512 synergistically 0.6771 2-(2&#39;-hydroxy-3&#39;- colourless colourless colourless active mixture. t-butyl-5&#39;-methylphenyl) Yellowish only benzotriazole after about 300 hours.  
 Table 2 Fadeometer exposure of film strips or cut threads After Fadeometer Exposure of: Before Exposure 22 Hours 44 Hours 66 Hours Ultimate Ultimate Ultimate Ultimate tensile Elongatensile Elongatensile Elongatensile V Elonga- Stabilisers strength tion strength tion strength tion strength tion added g/dtex 7r g/dtex 7r g/dtex 7c g/dtex 7:  
  without 0.56 657 0.04 no longer measurable stabiliser colourless yellow friable films, severe cracking elongation 2% 0.72 65] 0.70 652 0.62 662 0.58 653 stabiliser colourless colourless almost almost ll colourless colourless 27: UV 0.39 525 no longer absorber colourless yellowish measurable x) yellow l7r stabiliser 0.55 613 0.50 620 0.46 637 0.41 615 ll colourless colourless colourless colourless 1% triphenyl phosphite 1% stabiliser 0.46 590 0.43 630 0.40 697 0.39 678 ll colourless almost yellowish yellowish 1% triphenyl colourless phosphine +1.33% xx) XX) XX) Table 2 Continued Fadeometer exposure of film strips or cut threads After Fadeometer Exposure of: Before Exposure 22 Hours 44 Hours 66 Hours Ultimate Ultimate Ultimate Ultimate tensile Elongatensile Elonga tensile Elongatensile Elonga- Stabilisers strength tion strength tion strength tion strength tion added g/dtex 7t g/dtex /z g/dtex 7r g/dtex /1 stabiliser ll almost 0.66% UV colourless colourless colourless colourless absorber x) 2% xx) xx) XX) Stabiliser almost colourless lll colourless colourless pale yellowish pale yellowish 2% xx) xx) xx) xx) stabiliser almost colourless lV colourless colourless pale yellowish pale yellowish 2% xx) xx) xx) xx) stabiliser almost colourless almost colourless V colourless colourless pale yellowish pale yellowish Comparison tests: 2% Compound xxx) xxx) xxx) Vl colourless yellow (already from intense intense hours onwards) yellow yellow 2&#39;71 Compound xxx) xxx) xxx) Vll colourless yellow (already intense intense from l5 hours yellow yellow onwards) 271 l.3.5-trimethyl xxx) xxx) 2,4,6-tris-( almost colourless severe degradation, ditertiary colourless yellowish yellow intense yellow hutyl-4-hydroxybcnzyH-benzene (Compound X) 2% Compound Strength relatively well preserved lX almost colourless strong yellow intense yellow yellow brown x) 2-t2-hydroxy-3&#39;-tcrtiary hutyl-S&#34;methylphenyl)-5-ehlorohenzotriazole xx) strength substantially preserved. no crack formation on elongation.  
 xxx) films show severe crack formation on elongation with increasing exposure time and substantially reduced ultimate tensile strength.  
 1,6-diol and 2,2-dimethylpropane-1,3-diol containing diol in the molar proportion of 2:] (OH number 65.6) are heated to C to 51C for 100 minutes with l 1.6 parts of N,N&#39;-bis-(B-hydroxypropyl)-methylamine, 160.3 parts of diphenylmethane-4,4&#39;-diisocyanate and 192 parts of dimethyl formamide and 0.1 part of a 35% solution of so; in dioxane until the NCO content has dropped to 2.08% (based on solid NCO prepolymer).  
  Compounds VI and which differ n slightly 45 532 parts of this prepolymer solution are stirredlinto in their structure from the Stabilisers according to the a Solution of l7 15 parts of fl semicarbazido propionic invention, are substantially inferior since they undergo acid hydrazide in 34 parts of water and 1 1 19 parts of severe discoloration and their protective action is much dimethyl formamide, and 02 pan of hexane weaken f q P mPP IX of X diisocyanate and 4% by weight of titanium dioxide are are also dtstmcly inferior in their stabilising effect, the added to the elastomer Solution polyufethane elther cn tmumg to P Severe Stabilisers are dissolved in elastomer solution in the radation or preserving its strength relatively well but percentages by weight shown in Table 3 (based on solid undergomg Severe dlscoloratlon&#39; substance of elastomer), cast to form films in the usual Example 3 manner which are cut up into threads and exposed to 600 Parts of a copolyester of adipic acid, hexanethe Fadiometer.  
 Table 3 Fadeometer exposure of film strips After Fadeometer Exposure of:  
 Before Exposure 22 Hours 44 Hours 66 Hours Ultimate Ultimate Ultimate Ultimate tensile Elongatensile Elongatensile Elongatensile Elonga- Additions of strength tion strength tion strength tion strength tion Stabiliser g/dtex &#39;7: g/dtex 7! g/dtex 7t g/dtex 7:  
 without 0.60 666 0.50 620 0.27 538 no longer measurable stabiliser colourless pale yellow yellow brown yellowish brown 2% stabiliser ll 0.66 687 0.66 673 0.62 68] 0.60 680 Table 3 Continued Fadeometer exposure of film strips After Fadeometer Exposure of:  
  Before Exposure 22 Hours 44 Hours 66 Hours Ultimate Ultimate Ultimate Ultimate tensile Elongatensile Elongatensile Elongatensile Elonga- Additions of strength tion strength tion strength tion strength tion Stabiliser g/dtex g/dtcx 71 g/dtex &#39;71 g/dtex &#34;/1 colourless colourless colourless colourless 292 stahiliser lV Strength preserved, surface smooth and homogeneous when stretched colourless colourless almost colourless Comparison Examples: almost intense Compound IX 27: colourless lemon yellow lemon yellow Yellow brown 27! Compound X colourless pale pale yellowish yellowish brown yellowish brown 27: Compound Vlll colourless yellowish to yellow yellow yellow &#34;surface of the films breaks up into a large number of cracks when stretched owing to crosslinking on the surface.  
 Example 4 600 Parts of the copolyester described in Example 3 c CH on are heated to 85C in the melt for 38 minutes with R 9 i 3 R 173.4 parts of diphenylmethane-4,4-diisocyanate and c C l 1,9 parts of N.N-bis-(B-hydroxypropyl)- 5 l l l methylamine. and the resulting NCO prepolymer melt 1 3 3 f (2.76% NCO) is introduced into a solution heated to &#34;3 80C to 23.0 parts of carbodihydrazide in 243] parts of dimethyl formamide with the addition of 32 parts of TiO a highly viscous (530 P) elastomer solution being in which rm R is either a straight or branched chain alkyl group The stabilisers or comparison substances shown in containing 1 to 18 carbon atoms, a cycloalkyl Table 4 are added to this elastomer solution which in group containing 5 to 6 carbon atoms which may th en exposed to light in the Fadeometer 1n the form of be substituted by one or more lower alkyl groups, film strips. or an aralkyl group containing 7 to 9 carbon atoms.  
 Table 4 Fadeometer exposure of film strips (approx. 350 dtex) After Fadeometer Exposure of: Before Exposure 22 Hours 44 Hours 66 Hours Ultimate Ultimate Ultimate Ultimate tensile Elongatensile Elongatensile Elongatensile Elonga- Additions of strength tion strength tion strength tion strength tion Stabiliser g/dtex 71 g/dtex &#34;/2 g/dtex 71 g/dtex 7! without 0.62 550 0.43 502 0.22 385 no longer measurstabiliser yellowish yellowish able 2% stabiliser ll 0.63 58] 0.67 595 0.60 567 0.47 495 colourless colourless almost colourless What we claim is: 2. A compound as claimed in claim 1 in which R is l. A polyurethane stabilizing compound of the fora methyl, t-butyl, cyclopentyl or cyclohexyl group. mula:  
 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,875,246 DATED 1 April 1,1975 lNV ENTOR( S) Harald t l et al It is certified that error appears in the above-identified patent and that said Letters Patent I are hereby corrected as shown below:  
 Column 4, line 45, &#34;triu&#34; should be ---tris--j.  
 Column 7, line 42, Brackets should be placed around the formula.  
 Column 7, last line after. &#34;atoms.&#34; Munich should be deleted.  
 Column 8, line 8 &#34;Munic&#34; should be -L-Muni,ch--  
 Column 8, line 52, second occurrence &#39;poI estei&#39;s should be --polyethers---.  
 Column 10, line 12 after 220C..the following was left out C3 H O Molecular Weight: 510 Calculated: c 34.7.11&#34; 9.02 0 6.28!  
  Found: c 83.9 a 9.1 o 6.3 and should be inserted.  
 Column 10, line 40, &#34;1a3oc&#34; should be-ll f &#39;n Column 12, line 7, after &#34;with&#34;, insert -&#39;---t he&#39;-.  
 Colunm 13, line 39-, &#34;strenght&#34; should ---ls&#39;trength- Column 14, line 51, after &#34;in&#34; insert ---this--&#39;.&#39; 7  
 Column 14, line 55, &#34;Fadiometer&#34; should be ---Fadeometer-- Column 15, line 34, &#34;in&#34; should be --i.s  
 . Signed and. Scaled this Twent y siith Day of April 1977 [SEAL] Arrest:  
 RUTH C. MASON v C. MARSHALL DANN Arresting Officer Commissioner &#34;from&#34;: and Trademarks