Emulsion polymerisation of chloroprene with diethylhydroxy-amines as inactivator
United States Patent 1 Mayer-Mader et al.  
 [451 Apr. 15, 1975 Hohmann, Leverkusen, both of Germany [73] Assignee: Bayer Aktiengesellschaft,  
 Leverkusen, Germany [22] Filed: Jan. 7, 1974 [21] Appl. No.: 431,345  
 [30] Foreign Application Priority Data Jan. 11, 1973 Germany 2301158 [52] US. Cl 260/923; 260/795 C; 260/855 N; 260/863 [51] Int. Cl. C08d 3/14; C08f 3/20 [58] Field of Search 260/923, 666.5  
 [56] References Cited UNITED STATES PATENTS 11/1951 Goertz ..260/92.3  
 12/1965 Demme ..260/92.3  
 Primary Examiner&#39;Joseph L. Schofer Assistant Examiner-Herbert J. Lilling Attorney, Agent, or FirmConnolly and Hutz [5 7] ABSTRACT A process for terminating the polymerisation of chloroprene and/or 2,3-dichlorobutadiene in which diethylhydroxylamine is added to the polymerisation mixture in an amount sufficient to stop polymerisation.  
 2 Claims, N0 Drawings EMULSION POLYMERISATION OF CHLOROPRENE WITH DlETHYLHYDROXY-AMINES AS INACTIVATOR Emulsion polymerization of chloroprene and/or 2,3- dichlorobutadiene has been known for a long time. Polymers produced at a low polymerisation temperature are generally used as adhesives and polymers produced at high polymerisation temperatures are used as rubbers. The molecular weight of the polymer prepared by this method of polymerization can be adjusted with mercaptans (see British Patent No. 1,048,235) or with alkyl xanthate disulphides (see British Patent No. 512,458). Polymerization may also be carried out without a molecular weight modifier if sulphur is added during polymerisation and the resulting copolymer containing sulphur is subsequently degraded with a peptising agent to reduce its viscosity (see German Offenlegungsschrift No. 2,003,147).  
  To obtain polymers with optimum properties for practical purposes, polymerization must be terminated at a monomer conversion of less than about 80 percent because at higher conversion cross-linked products will be obtained. Polymerization can be terminated by, for example, removing any unreacted monomers from the reaction mixture by steam distillation, but as this degasification takes some time, polymerisation is not terminated instantly so that the conversion rate cannot beaccurately controlled.  
  Polymerization is therefore generally terminated by adding substances which inhibit polymerization and inactivate the polymerisation catalyst. Such substances will hereinafter be referred to as stopping agents. The following are examples: phenothiazone and tert.-buty1 pyrocatechol (see U.S. Patent No. 2,576,009). These stopping agents, however, cause discoloration of the polymer, especially on exposure to light. Other stopping agents are: nitroxides (see British Patent No. 1,124,009), salts of nitric acid (see British Patent No. 900,970), nitrogen monoxide (see Dutch Offenlegungsschrift No. 6,615,549) and oxalates (see Belgian Patent No. 612,246). All these stopping agents are only very slightly effective.  
  This invention is based on the discovery that diethyl hydroxylamine reliably terminates the emulsion polymerization of chloroprene and/or 2,3- dichlorobutadiene. The polymers treated with this agent are very light in colour and do not dicolour even when exposed to light or heat. This particularly pronounced when xanthate disulphides are used as molecular weight modifiers. The effect of diethyl hydroxylamine can be enhanced by simultaneously adding water soluble amines.  
  The stopping agents hitherto known are either too weak or they discolour the polymer or adversely affect its processing properties. Thus for example bromination of poly-2,3-dichlorobutadiene becomes very difficult if phenothiazine is used as stopping agent in the preparation of the polymer. The induction period is increased and substitution of the hydrogen atom positioned at the alkyl group is prevented.  
  This invention relates to a process for terminating the emulsion polymerization of chloroprene and/or 2,3- dichlorobutadiene which comprises adding to the polymerisation mixture 0.05 to 5 parts by weight of diethylhydroxylamine and optionally 0.05 to 5 parts by weight of a water soluble amine per 100 parts by weight of originally present chloroprene and/or 2,3- dichlorobutadiene at a monomer conversion of 40 to 80 percent by weight.  
  Emulsion polymerisation to produce chloroprene homopolymers and copolymers of 2,3-dichlorobutadiene polymers is known per se. Any of the usual emulsifiers may be used, e.g. water soluble salts, in particular alkali metal salts of long chain fatty acids, resinic acids, disproportioned abietic acids, aryl sulphonic acids and their formaldehyde condensation products, alkyl and aryl sulphonates or sulphates and ethoxylated alcohols or phenols.  
  The initiators used for polymerisation are the usual radical forming catalysts, e.g. hydrogen peroxide, cumene hydroperoxide, water soluble salts of peroxydisulphuric acid, 2,2&#39;-azo-bis-isobutyronitrile, salts of formamidine sulphinic acid and combinations of potassium persulphate and B-anthraquinone sulphonic acid.  
  As a general rule, the aqueous solution of catalyst is added to an aqueous emulsion which contains the monomers and emulsifying agents. Polymerization is generally carried out at pH 7-13 and at temperatures of from 0 to 60C and the monomer content of the emulsion is adjusted to 30-60 percent by weight of the whole emulsion.  
  The polymer can be adjusted to a particular molecular weight by carrying out polymerisation in the presence of modifiers such as mercaptans or dialkylxanthate disulphides.  
  The following are ethylenically unsaturated comonomers which can be copolymerised with chloroprene: acrylonitrile, methacrylonitrile, a-chloroacrylonitrile. and ethyl acrylate.  
  The process according to the invention may generally be carried out as follows:  
  At the desired monomer conversion an approximately 2.5 percent solution of diethylhydroxylamine in water is added to the polymerisation mixture and the mixture is cooled to 15C. The residual monomers are then removed from the dispersion. The polymer is then isolated from the dispersion in known manner.  
  Diethylhydroxylamine is a known compound. It may be prepared, for example, by the method described in Journal American Chemical Society 79 (1957) page 964. Water soluble amines suitable for the process are particularly those of the formula NR in which R may be identical or different and denotes hydroxyalkyl groups or alkyl groups containing 1 to 10 carbon atoms, at least two of the Rs denoting hydroxyalkyl groups. The following are examples: triethanolamine,  
 N-methyl-di-(isopropanol-amine and tri- (isopropanol )amine.  
 POLYMERlSATlON EXAMPLES EXAMPLE 1 The polymer is produced by polymerising the follow ing mixture:  
 parts by weight tetrasodium pyrophosphate Polymerisation is started at 45C with a mixture of formamidine sulphinic acid and deionised water.  
 When 65-70 percent by weight of the monomers have been polymerised, the latex is divided up into several portions. To Portion A are added 0.05 parts by I EXAMPLE 3 weight of phenothiazine, to Portion B 0.05 parts by P Produced y Polymerising the followweight of tert.-butyl pyrocatechol (TBC). to portion C g mlxtul&#39;el a combination of 0.025 parts by weight of phenothiazine and 0.025 parts by weight of tertiary-butyl pyro- 5 si gfig 8 catechol in 2 parts by weight of toluene, to Portion D deioniscd water 130 0.05 parts by weight of diethylhydroxylamine in 2 parts dispmpmiionuied Q y weight of water and to Portion E parts by sodium salt of the condensation weight of diethylhydroxylamine and 0.01 parts by product of phthalene sulp onic t 0.5 weight of tnethanolamme. l0 ggfi gggg 05 Table I shows that all the products have an efficient tetrasodium pyrophosphate 0.5 pp g action. especially if the latex is Subsequently Polymerisation is started at 45C with a mixture of pocooled to C. tassium peroxidisulphate and anthraquinone-B- Table 1 Sample stopping agents used conversion conversion conversion colour of at the end of after 1 hour after 5 hours the polymer polymerisation at l5C at 15C M 0.05% phenothiazine 65 66.2 67.5 discoloured grey brown 18 0.05% TBC 65 66.3 67.3 discoloured grey brown [C 0.025% TBC 65 66.0 67.0 discoloured 0.025% phenothiazine grey brown lD 0.05% diethyl hydroxylamine 65 66.3 67.3 clear IE 0.05% diethyl hydroxylamine 65 66.3 67.3 clear 0.01% triethanolamine After removal of the remaining monomer, the latex sulphonic acid. is worked up in the usual manner and dried in a vacuum When 65-70 percent of the monomer has been conat 70C for 48 hours. Table I shows that products D and verted to polymer, various combinations of stopping E which were stopped with diethylhydroxylamine are agents are added to the latex as in Example 1 and the light in colour. increase in conversion is followed (Table III).  
 Table Ill 7: conversion 0 conversion conversion colour Sample stopping agents used at the end of after i h after 5 h of the polymerisation at 15C at 15C polymer III A 0.05% phenothiazine 66.8 67 68.2 discoloured grey brown Ill B 0.05% TBC 66.8 67.2 68.3 III C 0.025% phenothiazine 66.8 67 68.2  
  0.025% TBC Ill D 0.05% diethylhydroxylamine 66.8 67.] 67.9 clear III E 0.05% diethylhydroxylamine 66.8 67 68.0 clear 0.01% triethanolamine EXAMELEIZ h f H EXAMPLE 4 ThePolymer Produced y P ymensmgt e 0 The polymer was produced by polymerismg the folmg mixture: lowing mixture:  
  parts by weight ts b ht chloroprene 00 h par 5 n-dodecyl mercaptan 0.28 c lofioprene 0 N deionised water 130 a h I sodium salt of a disproportionated Y mm ate p I e abietic acid 5 deionised water 120 sodium salt of the condensation 5 5 of a d&#39;spmpomonated product of naphthalene sulphonic 5 acid and formaldehyde 0 5 eodlum Salt caustic Soda 5 of the condensation product tetrasodium pyrophosphate 0.5 offiaphlhulene sulphonic a acid and formaldehyde Polymerisation IS started at 45 C with a mixture of caustic soda 0.5 tetrasodium pyrophosphate 0.5  
 formamidine sulphuric acid and deionised water. When 65-70 percent of the monomer has been polymerised, Polymerisation is started at 45C with a mixture of povarious combinations of stopping agents are added to tassium peroxidisulphatc and anthraquinone-B- the latex as in Example 1 and the increase in percentsulphonic acidwhen -70 Pement 0f the monomer age conversion to polymer i f ll d (T bl 1[ has been converted to polymer, various combinations Table II conversion conversion conversion colour of Sample stopping agents used at the end of after 1 h after 5 h the polymer polymerisation at 15C at 15C [I A 0.05% phenothiazine 67 68 68.8 discoloured grey brown ll B 0.05% tert.-butyl pyrocatechol 67 68.2 69.0 ll C 0.025% phenothiazine 67 67.8 68.5  
 0.025% TBC ll D 0.05% diethylhydroxylamine 67 68 68.4 clear ll E 0.05% diethylhydroxylamine 67 68.1 68.3 clear 0.01% triethanolamine of stopping agents are added to the latex as in Example I EXAMPLE 6 l and the increase in conversion is followed (Table IV The Polymer Produced by polymensmg the follow ing mixture:  
 Table IV conversion conversion conversion colour Sample stopping agents used at the end of after 1 hour after 5 hours of the polymerisation at C at 15C polymer IV A 0.05% phenothiazine 64.8 65.7 67.1 discoloured grey brown [V B 0.05% TBC 64.8 65.9 67 IV C 0.025% phenothiazine 0.025% TBC 64.8 65.6 66.8 IV D 0.05% diethylhydroxylamine 64.8 66.1 66.7 clear IV E 0.05% diethyl hydroxylamine 0.01% triethanolamine 64.8 65.9 66.9  
  EXAMPLE 5 chloroprene 100 The polymer was produced by polymerising the foln-dodecylmercaptan 0.16 lowing mixture. deionised water 120 sodium salt of a disproportionated jf f f h 5 so ium sat u t e condensation sa fi z 35 product of naphthalene sulphonic p acid and formaldehyde 0.5 .3-dichlor0butad|ene-( 1.3) 5 caustic Soda 0 q 323 2 23 3 5: d&#39;sulph&#39;de 8 tetrasodium pyrophosphate 0.5 sodium salt of a disproportionated abietic acid 5 sodium salt of the condensation product of naphthalene sulphonic acid and formaldehyde 0.5  
  To hos ht Polymerisation is started at 10C with a mixture of U p p formamidine sulphonic acid in deionised water. Pol merisation is started at C with a mixture of o- When 65-70 ercent of the monomer has been con- P P tassium peroxidisulphate and anthraquinone-B- verted to polymer, various combinations of stopping sulphonic acid. agents are added to the latex as in Example 1.  
 Table VI conversion conversion conversion colour of Sample stopping agents used at the end of after 1 h after 5 h the polymer polymerisation at 10C at 10C VI A 0.05% phenothiazine 67 67.8 68.7 discoloured grey brown Vl B 0.05% TBC 67 67.9 68.9 Vl C 0.025% phenothiazine 67 67.8 68.5  
  0.025% TBC Vl D 0.05% diethylhydroxylamine 67 67.9 68.6 clear VI E 0.05% diethylhdroxylamine 67 67.9 68.7 clear 0.01% triethanolamine When 65-70 percent of the monomer has been con- EXAMPLE 7 verted to polymer, various combinations of stopping agents are added to the latex as in Example 1 and the The polymer is produced by polymerising the followincrease in conversion is followed (Table V). ing mixture:  
 Table V conversion conversion conversion colour of Sample stopping agents used at the end of after 1 h after 5 h the polymer polymerisation at 15C at 15C V A 0.05% phenothiazine 65.3 66.2 67.2 discoloured grey brown V B 0.05% TBC 65.3 66.5 67.3 V C 0.025% phenothiazine 65.3 66.0 i 67.0  
  0.05% TBC V D 0.05% diethyl hydroxylamine 65.3 66.3 67.1 clear V E 0.05% diethylhydroxylamine 65.3 66.5 67.2  
 0.01% triethanolamine parts by weight 2.3-dichlorobutadiene-( L3) I n-dodeeylmercaptan 8 deionised water I20 sodium salt of a disproportionated abietic acid sodium salt of the condensation product of naphthalene sulphonic acid and formaldehyde caustic soda tetrasodium pyrophosphate Polymerisation is started at 45C with a mixture of&#39; formamidine sulphonic acid and deionised water.  
  When 95 percent of the monomer has been converted to polymer, various combinations of stopping agents are added to the latex as in Example 1. The polymer. after having been isolated, is brominated, and the incubation time is determined. Bromination is caried out as described in US. Patent Specification No. 2.725.373.  
  12.3 g of poly-dichlorobutadiene are introduced into a three-necked flask which already contains 150 ml of tetrachloromethane. The flask is then rinsed with nitrogen and the mixture is boiled under reflex with stirring until a clear solution is obtained. Two solutions are then added dropwisc, one consisting of 7.25 g of bromine dissolved in ml of CCl and the other of 0.56 g of tert.-butyl-hydroperoxide in 5 ml of CCL The time required before evolution of hydrogen bromine sets in (induction period) is shown in Table VII.  
  The time before allyl bromination sets in various according to the stabilizer used (induction period).  
 Table v11 System of stopping agents induction period (min.)  
 Phenothiazine I20 tert.-butyl pyrocatechol l20 phenothiazine/tert.Obutyl pyrocatechol diethylhydroxylamine 0 2 diethylhydroxylamine triethanolamine 0 2 It can be seen from Table VI] that the induction period up to the onset of evolution of HBr in accordance with the following reaction scheme:  
 CH-C=C-CH I ll 2 Br C101 Br -HBr parts by weight of 2,3dichlorobutadiene, said water soluble amine being of the formula NR wherein two of the R groups are hydroxyalkyl having 1 to l0 carbon atoms and the third R group is selected from the group consisting of hydroxyl and alkyl having 1 to 10 carbon atoms.  
 2. The process of claim 1 wherein NR is triethanolamine.