Патент USA US2404293код для вставки
Patented July 16, 1946 " _ 2,404,293 .V. l . uNITEosTATEs2,404,293PATENT: OFFICE’. 0 REGENERATION 0F WASTE RUBBER Alexander Johnston, Edinburgh 3, Scotland, as signor to The North British Rubber Company Limited, Edinburgh, Scotland ,, No Drawing. ‘ Application November '12, ‘1942, se ‘ rial No. 465,400. In Great Britain January 30, 1942 5 Claims. (01. 260—-720) - 11 This inventionv relates to :the regeneration or reclaiming of vulcanised waste rubber and/or vulcanised waste rubber containing ?brous mate rial, so that it may be re-used for manufacturing goods or articles. The inventionmay include the rubber obtainable fromj'used motor-car and other tyres, andotherarticle's. ' 2 jected tova re-heating treatment. Thus in a rub ber motor tyre, the tread and side wall portions may be separated from‘the carcase, and the‘ dif ferent parts worked up separately, or if necessary returned for-further‘ heating. in such separated , condition’. , Y If'any ofthe portions thus treated be found ’ to‘contain appreciable quantities of incompletely One object’ of the invention. is to treat such waste rubber by heatediinert ?ue or exhaust gases decomposed ?brous material, they may be read so that high pressure conditions are not required 10 ily removed by treatment in a washing mill or and such a gas being cheap and easily obtained. The waste rubber can be heated in a stream of A further object is to regenerate waste rubber the aforesaid gases at slightly increased pressure so as to effect a considerable saving of time, power that is, at a pressure not substantially above at and expense. ' ' mospheric pressure, either in a tunnel plant or in 15 A still further object of the invention is to otherwise. , ' an oven or vessel such as a digestor. conveniently separate all-rubber portions from , i The invention may be carried into effect in various ways and ?ve examples will now “be given: other portions'comprising rubber and ?brous ma terial and so obtain different grades of rubber. . According to the invention to‘be now described " Example 1 Y the process for regenerating waste rubber com '20 The heating of fabric containing ‘waste rubber prises heating such waste rubber in and by con such as motor tyres in 'a stream of boiler ?ue tact with heatedinert ?ue or exhaust gases until gases. 7 'i Y . ’ the rubber is in a condition in which itcan be This process depends > upon the utilisation of easily, plasticised. ' 1 < ' Furthermore when treating rubber which con 25 the hot gases in the boiler ?ue at some stage disintegration or carbonisation of the ?brous ma prior to their passage up the chimney, and the combined action of heat at 450° to 550° F. and relative inertness bring about the necessary re terial within a relativelyshort time, and at the duction of the cotton to carbon, and the'rubber dition of plasticity. ily milled into a smooth sheet, and Without danger of over-oxidation. The rubber of a tyre heated tains ?brous material, the temperature of’the gases should be sufficiently high to bring about same timev reduce the rubber to the required con_ .30 to a soft plastic condition capable of being vread ' The temperature of the gas or gases used may be within av range of 300° to r700° F., but it will in this way becomes plasticised, and the ?brous material disintegratedfwithout any appreciable be found that they aregenerally most effective within a rangeof 450° to 500° F. ~ - ca. L1 The treatment is preferably carried out in such consumption of power. ‘ ‘ , ' ' ' The waste rubber, cut‘ ‘into large, segments may a manner as to control the temperature (by ther mostat or otherwise) and/or the composition of the heating gases, by suitable dilution with other be- pocked into a suitable container, where the has been completed, the mass of rubber is allowed to cool in an inert, or, relatively inert atmosphere, the temperature being maintained constant at ap proximately 475° F. during this period. It is es sential that the temperature‘iof the gases does not become ‘too high as this results in the excessive decomposition of the rubber and it is equally im portant that the temperature is not too low, otherwise the destruction of the ?brous material takes toolong. Heat must be applied equally to all parts of the material being treated, as other contents will be exposed to a stream of 'hot gases for about 2 hours, so that the heat penetrates inert vapours or gases. When the heating stage 10 uniformly to all parts of the packed material, before being exposed to air. , Should the waste rubber comprise portions or layers which are substantially free from ?brous material such as canvas, whilst other portions or layers contain a substantial proportion of ?brous material, it may be desirable to separate the lay ers or portions before mastication and further processing, or even before the heating operation 50 wise some portions are excessively'reduced and has been completed. This separation may be readily effected as by stripping or pulling apart, and should it be desir able to expose the material to the further action of the gases such portion or portions may be sub- , are di?icult to handle on the sheeting mill, while the ?brous material in other portions is insu?i ciently reduced or decomposed, so that the result- ' ant sheet is not sufficiently smooth and takes too much re?ning. After heating for the required 3 2,404,293 ' ‘period, the container is withdrawn and the con tents allowed to cool before being exposed to at mosphere, after which the products will be found to be in a suitable condition for milling and fur ther processing to give a uniform smooth sheet. injections of one minute duration each are made every 15 minutes. At the end of this period the product is cooled down by further steam injec~ tions and removed from the trays to be milled and processed to give a smooth sheet. In any one of the above examples, it will be , Example 2 seen that the treatment period is not of long du Scrap motor tyres in’ a similar condition are treated as in Example 1, except that during the‘ -_ ration, and that as the coolinghas been effected heating process, steam is injected along with the .in an inert or relatively inert atmosphere, there is no risk of ?re on exposure of the material to ?ue gases for one minute periods every 15 minutes ‘the air. throughout the heating period. This injection of: It' is to be understood that the treatment ac steam-has the effect of assisting the separation cording to the present invention does not involve of the carcase from the tread and the side walls,‘ materialponsumption of power, and that this operation being subsequently readily carried‘ 15 any the gases preferably used are readily obtainable out by hand after the product has been removed inasmuch as they are waste gases, and that no from the container. The tread and side wall high pressures are; necessary. rubber is then milled and processed separately I claim: ‘ ‘ from the carcase rubber, and both kinds of rub-. 1. In the reclamation of rubber from vulcan ber may, if desired, be washed on a washing mill. 20 ized rubber waste containing ?brous carbonizable to remove completely any residual partially de materials; the process whichrcompris'es heating composed fabric before further processing. pieces of: such a rubber waste in an atmosphere 'In this way two separate reclaim rubbers are‘ ' of ?ue gases at a pressure not substantially ex obtained,v one from the tread and sidewall por- ' seeding‘ atmospheric pressure and at a tempera tionsand one from the carcase portion. It may I25 ture varying from about 450° to 500° F; for a time be stated that the steam, which is admitted in varying from about 1 to 2 hours‘ sufficient to car termittently, may be superheated, and that the ' bonize the ?brous material While softening the use of seam induces a tendency for initiating the rubber to the plastic stage'and agitating the rub ber pieces during the heating. separation of the layers. Example 3 Scrap motor tyres in a similar condition are j treated as in Example 2, except that the heating ‘ processis interrupted after one to one and a quarter hours and the tread and side walls then 30 2. The process of claim 1 wherein the-rubber pieces are agitated by tumbling them in a rotary foraminous container. 3. In the reclamation of rubber from vulcanized rubber tire waste containing tire fabric, the proc I separated from the carcase. Usually the tread. 35 ess which comprises heating pieces of such a rub ber waste in an atmosphere of ?ue gases and ‘ and side wall portion is suf?ciently‘heated after steam at a pressure not substantially exceeding this period and may then be milled and proc atmospheric pressure and at a temperature rang ‘ essed without further heating. It is however 1 usually necessary after this shorter period of 40 ing from about 450° to 500° F. for a time period heating to subject the carcase rubber to a further 1 varying from about 1 to 2 hours su?icient to ‘ short period of heating. Example '4 loosen the carcass portion from' the tread and side wall‘ portions, the steam being introduced for periods of about 1 minute between intervals of about 15 minutes during the heating, separat Scrap gas masks either in the form of complete face piecesor the spew from moulding are packed 45 ing the carcass portion from the tread and side wall portions and separately processing the por into thecontainers and heated for a period of tions for recevery of the rubber contained‘therein. one hour at 450‘? F. At the end of this period 4. The process of claim 3 wherein the sepa ‘the product is cooled, removed from the con rated‘c'arcass portion is subjected to a further tainer and is then found to be suf?ciently plasti ‘ cised to be milled and processed into a smooth . heat treatment under the same conditions for a time suf?cient to carbonize said ?brous material sheet. Example 5 Scrap motor tyres are cut into small sections and to soften the rubber to the plastic stage. portions are washed on a washing mill to remove ‘ and packed on trays which'are placed in an oven, 55 residual partially decomposed fabric before fur I and through which oven ?ue gases at a temper ther processing. , fature of from 475° to 500° F. are passed for a period 'of two hours. During this period steam 7 '5. The process pf claim '3 wherein the separated ALEXANDER JOHNSTON.