IL44072A - Production of flame retardants by chlorobromination of black liquors - Google Patents

Description

n Production of flame retardants of black liquors State of She Esther Zeigereon Rudolf Bloch The preBent Invention concerns a process flame retardants from liquors of the pulp In the paper industry pulps are produced by the decomposition of wood by either the sulfite or sulfate In either case after the separation of the pulp there is left a black liquor which in the case of the sulfite process contains sulfonate and the case of the sulfate process contains eulfurated alkali lignin also known as kraft From the black liquors kraft lignins and lignin sulfonate are reoovered commercially in the form of solid dry products by various companies and made available for various for the Crown Zellerbach Company produces a sulfonate under the trade name the Westvaoo Company produces a kraft lignin under the trade name Indulln the American Can Company produces a lignin sulfonate under the trade name and there are many In the specification of our Israel Patent cation 37812 of the 28th September and the ponding Application of 20th as well as in specifications of corresponding patent other countries we have disclosed that by the bromlnation of kraft lignin or llgnln it is possible to obtain flame retardants suitable for flame proofing of Inflammable for it poaalble to produce partiole boards with a high degree of fire resistance by Incorporating the bonding a certain amount of brominated llgnin sulfonate or brominated lignin Hitherto the production o or has been quite The starting material was in each case dry llgnin sulfonate or dry kraft any of the commercial products mentioned each of which is obtained by concentration and precipitation processes the In a secon stage dr lignin sulfonate or kraft llgnin serving as starting material is suspended in water or an electrol te solution and then brominated either or From the slurry remaining the bromination the product or as the case may is then This procedure has an adverse effect the price of the product to extent that the price stands in the way of the commercial applicability of and I therefore the of the present inventio to provide a simplified overall process the production o directly rom black Experiments conducted preparatory to present invention to black liquors directly failed inasmuch the bromine was too in one o the experiments 31 g of bromine was added to 60 g of black liquo obtained the Hudson Pulp Paper while stirring kraft lignln settled from the solution and after rinsing with water and drying at g of product was obtained which analysed as ollows Br pH The comparatively low bromine content corresponded to a bromine efficiency only Similar experiments conducted with lighin liquors such as obtained from Store and as well as with black lignln sulfonate liquors obtained from the same In accordance the invention it has surprisingly been found that the bromine efficiency in the of sulfonate or kraft lignln liquors can be appreciably increased to within the range of and even higher by a basically process comprising the steps of and Hereinafte the liquors obtained from the decomposition of wood by either the sulfite or sulfate process and sulfonated and kraft will be referred to collectively for short as ulfurated lighin the sulfurated lignln liquors serving as starting material contains lignln sulfonate e product will be referred to as sulfonate and and where the lignin serving as starting material contains kraft lignin product will be referred to as brominated lignin and for In accordance with the invention a solid brominated product is prepared from a sulfurated lignin liquor by a process which comprises introducing elemental chlorine into the l quor in an amount not exceedin of the experimentally determined then brominatlng the liquor and separatin a solid the chlo may be effected by means of chlorine and a bromide salt or by chlorine and bromine which may be added concurrently or in a operation or in the first of which steps the liquor with elemental bromine and in the second it is Where for the a mixture of chlorine and bromide used the bromide oxidized situ by chlorine into elemental bromine which reacts with the Where elemental bromine is used for this reaction the chlorine the bromide formed as a that only half the theoretically required amount of bromine needed whereby the bromine efficiency o the process is It has been that due to the preliminary chlorination in the process according to the the bromine efficiency of the process is substantially increased as compared to direct bromination of a and this may presumably ascribed to consumption of chlorine by various reducing agents present in the which consumption does not contribute to the desired final If the liquor is directly brominated without preliminary chlorination the same reducing agents consume a substantial part of the bromine and thereby reduce the bromine efficiency of the Since chlorine is considerably cheaper than bromine it is clearly profitable if chlorine than bromine is consumed by uiidesired side It has further surprisingly been found in ance with the invention that the total halogen content of the product is larger than in the case of pure In other the chlorine content of the product is larger tha corresponds to a mere replacement of some of the and it has surprisingly been that by this the resisting properties of the product are not inferior and some oases even superior to those of a corresponding product whic is only In other according to the invention by a combined brominatlon a flame retarding effect is achieved which at least same as by pure bromination an equivalent amount in with known This constitutes an obvious economic advantage i view of the fact that chlorine is cheaper than s d prior to the for this purpose for se or or from batch which is acidic to the formation Of some liquor starting kraft the concentration of solids by The solution preferably prior to to about order Where the rated liquor serving as starting contains the of solids is by In this it is to add some electrolytes to the liquid such or embodiment of the invention chlorination is continued for a while after completion the and precipitation of the case may whereby the product Afte completion of the reactio the produc or as the may is filtered washed and I acid components o the wet o dry products e by treatmen wit by the addition of solid basic substances such as a carbonaceous phosphate antimony an alkali metal an alkali earth metal hydroxide or an other suitable base or alkali The invention is illustrated by the following Examples and Experiments to which it is not In all the Example and all percentages compositio are by EXAMPLE 1 g of a black liquor obtained from the Hudson Pulp and Paper was diluted with 30 ml of and the slurry was to about stirring about half an hour during which time gas thereafter through a calibrated rotameter an amount of 2 g chlorine was bubbled in over minutes and was by addition of g of liquid bromine a period of 10 minutes concurrently with a further amount of g of chlorine which was bubbled into the solution during 30 A solid product precipitated which filtered off and washed with The product amounted to and contained Br and The bromine efficiency was It should be noted that efficiency depends on the escape of surplus chlorine which always entrains some o the bromine This entrained bromine can be recovered together the chlorine by a current gas absorption Since no bromine ions were found in the filtrate it follows that in production the bromine efficiency in accordance with the be increased by recovery of entrained bromine from the escaping EXAMPLE 2 The procedure was similar as in Example 1 but the elemental bromine was replaced by g of r corresponding to g of bromide The amount of chlorine required for the chlorination was g which was fed to the reaction mixture over a period of 42 The product amounted to g containing Br and The bromine efficiency was EXAMPLE 45 ml of the acidic mother liquor remaining from the process according to Example 1 were added to 30 g of a black liquor obtained from the Hudson Pulp and Paper 2 g of chlorine gas was bubbled in and thereafter g of potassium bromide corresponding to g of bromide ion was added and further g of chlorine was into the There formed a precipitate whioh was filtered washed and In this way g of a product containing Br and CI were The bromine efficiency was EXAMPLE 4 ml of an acidio mother liquor from the prooess according to Example 1 and 10 ml of water were added to 60 g of Hudson black The slurry was heated to for a period of about 15 minutes until evolution Thereafter an additional amount of 15 of water was added following which g of chlorine was bubbled in the g of potassium bromide corresponding to g of bromide ion added and g o chlorine was bubbled into the solution over a period of 23 After normal working up there was obtained g of a product containing of Br and of The bromine efficiency was EXAMPLE To a solution of g of black sulfite liquor obtained from the where was added ml of a IN After mixing for about 5 minutes g of chlorine was bubbled Thereafter 20 ml of a N solution corresponding to g of was and another 15 of was bubbled into the The reaction exothermic and in the course thereof The product was filtered rinsed with and dried at to constant weigh In this way there was obtained g of product containing of Br and of Efficiency was EXAMPLE 6 The procedure of Example 5 was repeated 2 ml of liquid bromine instead of bromide g of a dry product containing 1 of Br and of 0 was The bromine efficiency was A mixture of 30 ml o sulfite black liquor obtained the of sulfate black liquor same source was 30 ml of 30 of an acidic mother liquor om a chlorobromination process was The materials were mixed for half an hou at until evolutio Thereafter chlorobromination was effected as in Example There was obtained g of a produc being a mixture of and It contained Br and an the bromine efficiency was In all the foregoing Examples a sharp of the colour of the slurry from dark brow to yellow was when the chlorobromination reaction was Filtration washing properties of the produot were very There now follows a short by wa example as to how the and in accordance with the invention oan be Used Experiment 1 10 g of obtained by chlorobromination of Hudso black liquor in accordance with Example 4 were dissolved in about ml of ethyl Standard size x pieces of paper board were dipped in the solution and afterwards dried at to constant A alysis the presence of by weight of Br in the paper Fire resistance tests Of the samples were conducted accordance as follows An impregnated specime having the above size was held in a metal frame and with long in a vertical to a standard test The test flame was applied for 12 seconds and then The of flaming and o the af glow was Average char length allowed is and the maximum should be no than cm The results achieved with the samples impregnated as above summed up in the followin Table Table Impregnation of paperboard by dipping alcoholic solutions Time of burning Time of with flame afterglo Char lengt Blank 75 Burned completely 1 0 0 0 2 30 The colour the was brown dark In this experimen prepared i accordance with the teachings of this was incorporated in a The binder was a starch glue obtained from the Oargal of The glue contained about t solids and was dark brown It was mixed with different amounts of and water to suitable The mixture was smeared several homogeneous layers a few times on the Each sample was dried at to constant Some of the samples were burned under standard conditions according to and the results are summed up in the following fable 2 where two sets of results and are given for each Table 2 Paperboard impregnation against by external coating Compositio of Weight Burning Bromine coating mixture increase with glow length content seconds seconds Blank 19 Burned completely Cargal glue 0 11 Additional wate 0 1 Cargal glue 0 Additional water 0 13 The following composition Obtained in accordance with the inventio Cellulose acetate Acetone The mixture was ground and then added in an amount of to a kraft paper drying and the normal piecee containing of Br were The burning experiments of a kraft paper produced in this way gave positive Experimen 4 of the same kind in Experiment 2 above was The following composition is wood chips prepolyiaerisate chunks of pressed particle board were produced from this mixture in a at with external heating to about by a The fire resistance properties of these chunks were tested by the method outlined in Sxperiment with the following Time of burning with in 0 Time of in seconds Experiment was repeated with a processed in accordance with Example 4 with the following of burning with in seconds 0 Time of in seconds insufficientOCRQuality

Claims (1)

1. Process the preparation of a solid brominated product from a liquor obtained by the decomposition of wood by either the sulfate or sulfite method and removal of the pulp lignln comprising ducing elemental chlorine into the liquo in an amount not exceedin of the experimentally determined halogen then the liquor and separating a solid product Process according to wherei a liquor containing lignln used as starting Process according to Claim wherein a containing lignln sulfonate is used as starting Process accordin to Claim wherein a mixed liquor containing kraft lignln and lignln sulfonate is used as starting Process according to any one of the preceding wherein the chlorobromination is effected by means of chlorine and a bromide Process acoording to any one of Claims 1 the chlorobromination is effected by means chlorine and according to wherein the chlorine and bromine are added according to Claim wherein the is carried Out in a operation in the first of which bromine and in the second chlorine is added to the Process according to Claim wherein the liquor contains weight of ProOess according to Claim wherein the liquor contains by weight lignin Process according to any one of Claims 2 and 4 to wherein the solution is heated prior to chlorinatiOn to expel Process according to any one of Claims 3 to 8 and wherein a least one electrolyte is added to the solution prior chlorina Process according to any one of the preceding wherein the liquor is acidified prior to Process to Claim wherein a mother liquor remaining from run is used for the Process to an one of preceding claims wherein the wet dry product is treated with an alkali for neutralization of acidic Process according to Claim wherein the is Process according to Claim wherein a solid basic substance is insufficientOCRQuality