Title of Invention	BEADED BLACK AND A PROCESS FOR PRODUCING THE SAME
Abstract	THE INVENTION CONCERNS A BEADED BLACK CONTAINING AT LEAST ONE PELLE4TISING ADDITIVE AND AT LEAS ONE SYNTHETIC OIL.THE BEADED BLACK CAN BE PRODUCED IN A PELLETISING MACHINE AND USEDE AS A FILLER AND/OR PIGMENT IN RUBBER AND PLASTIC ARTICLES AND AS A PPIGMENT FRO THE4 PRO0DUCTION OF PRINTING INKS.

Full Text

Beaded black The present invention concerns a beaded black, a process for its production and its use. In the processing of industrial carbon blacks, pelletised products, commonly known as beaded black, are preferably-used. Two different methods are used for pelletising carbon blacks on an industrial scale: wet pelletising in a pelletising machine with subsequent drying, and dry pelletising in a pelletising drum. The two methods have markedly different process parameters, which are closely linked to the physical processes involved in agglomeration in each case and to the resulting bead properties (Ullmanns Encyklopadie der technischen Chemie, 4th Edition, Volume 14, page 639-640 (1977)). A beaded black is known from EP 0 924 2 68 which contains at least one natural and/or synthetic wax and which is obtained by pelletising a powdered starting black, whereby the content of waxes in the beaded black is 1 to less than 10 wt.%, relative to the total weight of beaded black, and the hardness of the individual beads in the beaded black is greater than 0.15 N. The disadvantage of the known beaded blacks is their poor vdispersibility at the specified bead hardness. The object of the present invention is to produce a beaded black having improved dispersibility, abrasion resistance, flow behaviour and transport stability. The invention provides a beaded black characterised in that it contains at least one pelletising additive and at least one synthetic oil. The pelletising additive content can be 0.1 to less than 10 wt.%, preferably 1 to 5 wt.%, and the oil content 1 to 12 wt.%, preferably 4 to 8 wt.%, relative to its total weight. The hardness of the individual beads in the 0.5 mm - 0.71 mm bead fraction can be greater than 2 g. The pelletising additive can be oil-soluble. The pelletising additives used to produce the carbon black can be both natural and synthetic waxes. A good overview of suitable waxes according to the invention can be found in Ullmann"s Encyclopedia of Industrial Chemistry, Vol. A28, pages 103 to 163, 1996, Karsten, Lackrohstoff-Tabellen, 9th Edition, Vincentz Verlag, Chapter 33, pages 558-569 (1992), Rompp Lexikon "Lacke und Druckfarben", Georg Thieme Verlag, pages 157-162 (1998) and "The Printing Ink Manual", Fourth Edition, VNR International, Chapter 4, Section VII "Waxes", pages 249-257 (1988). Such waxes that are conventionally used to produce the finished products into which the beaded black is to be incorporated can preferably be used. The process also permits the homogeneous application of smaller amounts of wax and hence an improved effect in comparison to the use of equal amounts of pure wax. The proportion of wax incorporated into the finished product by means of the beaded black can generally be kept lower than would be the case with conventional processing because of its homogeneous distribution on the surface of the carbon black due to its dilution with the pelletising oil. In this way the beaded black places minimal restrictions on the amount of wax contained in the finished product. A paraffin wax or a blend of refined hydrocarbon waxes can preferably be used as the wax. Resins, preferably bituminous solutions, can also be used as pelletising additives. An overview of suitable resins according to the invention can be found in Karsten, Lackrohstoff-Tabellen, 9th Edition, Vincentz Verlag, Chapters 1-32, pages 55-558 (1992), Rompp Lexikon "Lacke und Druckfarben", Georg Thieme Verlag, pages 157-162 (1998), "The Printing Ink Manual", Fourth Edition, VNR International, Chapter 4, Section IV "Resins", pages 192- 224 (1988) and Printing Materials: Science and Technology, Bob Thompson Pira International, Vehicles, Oils, Resins, pages 338-340 (1998). Mixtures of waxes.......mixtures.,of resins and mixture of waxes and resins can also be used as pelletising additives. A mineral oil, preferably naphthenic oil, can be used as the synthetic oil. An overview of suitable synthetic oils according to the invention can be found in Karsten, Lackrohstoff-Tabellen, 9th Edition, Vincentz Verlag, Chapter 37, pages 601-620 (1992), Rompp Lexikon "Lacke und Druckfarben", Georg Thieme Verlag, pages 157-162 (1998), "The Printing Ink Manual", Fourth Edition, VNR International, Chapter 4, Section III "Oils", pages 188-191 and Section V "Solvents", pages 225-243 (1988) and Printing Materials: Science and Technology, Bob Thompson Pira International, Vehicles, Oils, Resins, page 342 (1998). The total bead hardness of the beaded black according to the invention can be greater than 6 kg, preferably greater than 7 kg. The bead strength of the 0.5 mm - 0.71 mm bead fraction can be greater than 70 KPa, preferably greater than 80 KPa. The bead strength of the 0.71 mm - 1.00 mm bead fraction can be greater than 60 KPa, preferably greater than 68 KPa. The average individual bead hardness of the 0.71 - 1.00 mm bead fraction can be greater than 3 g. Lamp black, channel black, gas black or furnace black can be used as starting black. Starting blacks having a DBP adsorption of between 40 and 250 ml/100 g and a nitrogen surface area of 5 to 500 m2/g can preferably be used. Corax N 33 0, Printex 3, Printex 30, Printex 3 00 and Printex 35 from Degussa-Huls can particularly preferably be used as starting blacks. The invention also provides a process for producing a beaded black according to the invention, characterised in that powdered carbon black and the oil/pelletising additive mixture are mixed together. Mixing can be performed in a pelletising machine, a continuous or discontinuous mixer ox a mill, for example a compressed air mill or hammer mill. In one embodiment the beaded black according to the invention can be produced in a pelletising machine with a pin shaft, whereby the pelletising machine displays an intake zone, a mixing and pelletising zone and an outlet zone, by feeding powdered carbon black into the intake zone of the pelletising machine, continuously removing the carbon black from the outlet of the pelletising machine anc spraying the oil/pelletising additive mixture onto the starting black ahead of the pelletising machine or in the first third of the pelletising machine whilst it is still in powder form. The pelletising machine can be heatable. A device according to DE 19.6 23198 can be used according to the invention. To produce the beaded black according to the invention, the speed of the pin shaft can be adjusted such that the peripheral speed of the pin tips assumes values of between 1 and 30 m/s. The average retention time of the carbon black in the pelletising machine can be adjusted to a value between 2 0 and 600 seconds, preferably between 2 0 and 180 seconds. The manner in which the oil/pelletising additive mixture is added has a great influence on the quality of the finished beaded black. The desired bead hardness with a content of less than 10 wt.% of pelletising additive in the beaded black can be achieved if the oil/pelletising additive mixture is sprayed very finely over the powdered starting black with an average droplet size of less than 50 vim. The oil/pelletising additive mixture can be sprayed by first melting it by heating it to a temperature between the melting temperature and the decomposition temperature of the pelletising additive and then feeding it to a spray nozzle. Spraying the oil/pelletising additive mixture through a two-fluid nozzle can be suitable for the purposes of the invention. Average droplet sizes of around 20 mm can be obtained by spraying the oil/pelletising additive mixture by means of compressed air at 6 bar. The mixture can also be sprayed by means of pressure atomisation. In addition to the manner in which the oil/pelletising additive is sprayed, the location in which it is sprayed also has a substantial influence on the quality of the beaded black that is formed. The pelletising machine for use according to the invention can consist of a horizontal, fixed pipe (stator) in which a pin shaft (rotor) rotates. The pelletising machine has an intake zone in which the powdered starting black is fed into the pelletising machine. This zone includes a feed screw which imparts an axial motion component to the supply of carbon black. Adjacent to the intake zone is the actual mixing and pelletising zone, in which the carbon black is first coated with the oil/pelletising additive mixture and can then agglomerate at the inner wall of the stator due to the mechanical action of the rotating pins and to the rolling motion. The size of the individual zones of the pelletising machine can vary according to the design of the pelletising machine. In all cases the intake and outlet zone should be kept as small as possible to maximise the mixing and pelletising zone. In order to obtain as homogeneous as possible a distribution of the oil/pelletising additive mixture across the entire cross-section of the carbon black beads, the oil/pelletising additive mixture must be sprayed onto the carbon black ahead of the pelletising machine or in the first third of the pelletising machine. Introducing the oil/pelletising additive mixture at a later stage of bead formation leads to an inhomogeneous structure in the carbon black beads and hence to a reduced bead hardness. A further improvement in the homogeneity with which the oil/pelletising additive mixture is incorporated into the carbon black can be obtained if several spray nozzles arranged on one level perpendicular to the pin shaft around the perimeter of the stator are used for spraying. The number of nozzles can conveniently be limited to one to six. The nozzles can be arranged on one level perpendicular to the pin shaft in order to ensure a good homogeneity of incorporation. The oil and pelletising additive can be incorporated at different agglomeration stages by means of an axial adjustment. A feed screw can be used to feed the powdered carbon black into the pelletising zone of the pelletising machine. The carbon black throughput or output of the pelletising machine is therefore equal to the delivery rate of the screw and can thus be adjusted between broad limits. The capacity and retention time can be increased by raising the outlet zone in relation to the intake zone. The resulting angle between the axis of the pelletising machine and the horizontal can be adjusted between around 0 and 15°. The capacity and retention time can also be influenced by the speed of the pin shaft. If the supply of carbon black remains uniform (constant carbon black throughput), the capacity and retention time reduce proportionally to each other as the speed increases. The preferred retention times for production of the carbon black according to the invention can lie in the range between 20 and 180 seconds. Below 20 seconds the agglomeration process can be more or less incomplete. In this case the unit acts as a mixer but nevertheless delivers a certain proportion of bead seeds, which support pelletisation in the pelletising drum. Retention times above 600 seconds are usually possible only at low carbon black throughput rates because of the upper limit to the capacity. Agglomeration can conveniently be initiated by incorporating beaded black into the powdered black as agglomeration seeds (also referred to below as inoculum). Beaded black in the same grades of carbon black that are to be pelletised can preferably be used. Depending on the bead properties of the carbon black, up to 60 wt.% of beaded black can be added to it. The beaded black can preferably be added to the powdered black in a quantity of 5 to 40 wt.%. In the case of readily pelletising carbon black grades, the addition of beaded black can be omitted altogether or can be terminated shortly before the start of pelletisation. A further improvement in pelletisation can be achieved if the powdered black is compressed to bulk densities of between 150 and 350 g/1 before it is fed into the pelletising machine. Precompression can be performed by known means, using vacuum filter rolls for example. The beaded black according to the invention can advantageously be used as a filler and/or pigment in rubber and plastic articles and as a pigment for the production of printing inks. As a consequence of its excellent bead hardness it is characterised by good transportation and metering properties and yet can be readily dispersed. The improved bead hardness and bead strength can be achieved whilst retaining the good dispersibility of the pellets. In attrition mill dispersion the carbon black according to the invention displays a dispersibility that is just as good as that of the powdered black and it also has the material handling advantages of a beaded black. The beaded blacks according to the invention have a higher abrasion resistance in printing inks than comparable carbon blacks pelletised using oil or wax. The invention is illustrated in greater detail below by means of the following drawings: Figure 1: Pelletiser with pin shaft for production of the beaded black according to the invention. Figure 2: Process flow chart for production of the beaded black according to the invention. According to Figure 1 the beaded black according to the invention can be produced with a pelletising machine. Figure 1 shows a schematic view of the design of such a pelletising machine. The pelletising machine consists of a horizontal fixed pipe 1, the stator, and, positioned axially within it, a rotating pin shaft 2 with a helical arrangement of pins. The bead chamber 4 of the pelletising machine is located between the pin shaft 2 and the stator 1. The powdered black is fed into the pelletiser at the intake 5. On the pin shaft in the intake zone there is a feed screw 6, which conveys the powdered black in an axial direction towards the outlet 7. The stator 1 has a twin-wall construction and allows the temperature of the stator wall to be controlled by means of a liquid or steam 8. In the first third of the pelletising zone of the stator there are access holes through which spray nozzles 9 for adding the oil/pelletising additive mixture can be introduced. Figure 2 illustrates the process flow chart for the production of the beaded black according to the invention. The axis of the pelletising machine 10 can be inclined at an angle of 0 to 15° to the horizontal in order to adjust the retention time. To this end the outlet of the pelletising machine is raised correspondingly in relation to the intake. Powdered carbon black 11 and optionally inoculum 13 are fed to the intake 15 of the pelletising machine 10 or the pelletising drum from the collection vessels 12 and 14. The stator in the pelletising machine is adjusted to a desired temperature by means of the thermostat 16. Examples: Determining the dispersibility of oil-pelletised carbon blacks (predispersion) Equipment and reagents: - Dispermat high-speed mixer from Getzmann with a maximum speed of 20,000 rpm; - High-speed mixer disc as toothed disc with a diameter of 25 mm; - Steel cylinder as dispersion vessel with the following dimensions: d = 55 mm, H = 200 mm; - Grindometer according to DIN 53 2 03 - Bituminous solution 169 from Haltermann, - Gravex 942 from Shell Method - Composition and preparation of the test varnish The following components are weighed into a casserole and homogenised: 500.0 g bituminous solution 169 500.0 g Gravex 942 In order to check a newly prepared test varnish, reference is made to a reference sample of carbon black with a known dispersion curve. - Performing the dispersion test The following components are weighed into the dispersion vessel: 20.0 g carbon black 80.0 g varnish The carbon black is carefully incorporated into the binder and wetted by stirring slowly. The dispersion test then follows without cooling at a mixer disc speed of 15,300 rpm = approx. 20 m/s in dispersion stages of 15 min. After each dispersion stage a small sample is taken and tested with the grindometer to check the distribution state reached by the carbon black. The total dispersion time is 45 min. Results: The grindometer values measured after the individual dispersion stages are recorded as the result in order to be able to plot the dispersion curve. The grindometer value measured after a dispersion time of 45 min is taken as the measure of the dispersibility. etermining the printing efficiency of carbon blacks in a ewspaper ink (attrition mill dispersion) Laboratory balance, weighing range 0.1-5500.0 g, High-speed laboratory mixer, e.g. Pendraulik, diameter of toothed disc 60 mm, Attrition mill, which should meet the following requirements: Stirrer with 3 eccentric annular elements, each offset by 120°; Stirrer speed: 2800 rpm; Millbase vessel: —> overall capacity 500 ml, diameter 90 mm —> effective capacity 3 00 ml Steel balls as grinding medium with a diameter of 3 mm; amount of steel balls required: 1,250 g; - Grindometer according to DIN 53 203; - Macbeth RD 918 densitometer, - Newsprint 52 g/m2, - 280 u high-speed screen from Drekopf, - Albertol KP 172, phenol-modified colophony resin, Hoechst AG, - Albertol KP 111, phenol-modified colophony resin, Hoechst AG, - Gilsonite EWC 7214, asphalt resin, Worlee, - Gravex 917, mineral oil, Shell Method - Composition of the rotary offset varnish The following components are weighed into a casserole: 12 0 g Albertol KP 172 120 g Albertol KP 111 160 g Gilsonite 600 g Gravex 1000 g The liquid component Gravex is conveniently measured out first. This is followed by the addition of the solid resins Albertol KP 172, Albertol KP 111 and Gilsonite, which are dissolved at 170°C while being stirred. The mineral oil lost due to evaporation is made up. The finished varnish is passed through the screen (280 u) . The varnish is ready for use once it has cooled. - Preparing the printing ink The composition of the printing ink is as follows: 48.0 g carbon black 201.0 g varnish 51.0 g Gravex 300.0 g The varnish and Gravex are homogenised. The carbon black is added in portions. Predispersion is performed for 10 min at 4000 rpm using the high-speed mixer. Dispersion is performed in the attrition mill without cooling in dispersion stages of 15 min each. After each dispersion stage a small sample is taken in order to determine the distribution state by means of the grindometer. Dispersion is ended as soon as a grindometer value of Determining the flow behaviour of a printing ink using the flow plate The carbon black to be tested is processed to form a printing ink similar to that used in industry. A metered amount of printing ink is applied to the glass plate and the glass plate is set up in a vertical position (90°). After a predetermined time the distance over which the printing ink has run is measured in mm. This can be used as an indication of the flowability of a printing ink. The total bead hardness to ASTM D 1937-98 and the individual bead hardness to ASTM D 5230-99 are measured. The beaded black according to the invention (example 3) displays advantages over the oil-pelletised carbon blacks (comparative example 1) and the wax-pelletised carbon blacks (comparative example 2). The total bead hardness, the individual bead hardness and the bead strength of the 0.5 mm - 0.71 mm and 0.71 mm - 1.00 mm bead fractions of the beaded blacks according to the invention are clearly increased. The improvement in bead hardnesses and bead strengths in comparison to comparative examples 1 and 2 can be achieved whilst retaining the good dispersibility of the pellets. Dispersibility in attrition mill dispersion and flow behaviour are improved in comparison to the oil-pelletised and wax-pelletised reference blacks. In attrition mill dispersion the carbon black according to the invention displays a dispersibility that is just as good as the powdered black used and it also has the material handling advantages of a beaded black. Improved dispersibilities are obtained with the oil/ pelletising additive carbon blacks having the same or increased bead hardness in comparison to the prior art carbon blacks. Gravex oil Shell AG Highly refined mineral oil Protector G35 Paramelt B.V. Blend of refined hydrocarbon waxes We claim: 1. Beaded black, characterised in (hat it contains at least one pefetistog additive such as herein descrfoed and at least one synthetic oil such as herein described. 2. Beaded black as claimed in claim 1, wherein the palletising additive content is 0.1 to less than 10 wt.% and the ol content Is 1 to 12 wt.% relative to Is total weight. 3. Beaded black as claimed in claim 1, wherein the starting black displays a DBP absorption of between 40 and 250 ml/100 g and a nitrogen surface area of 5 to 500 m2/g. 4. Beaded black as claimed In claim 1, wherein the pelletisting additives are waxes. 5. Beaded black as claimed in claim 1, wherein the pelletising additives are resins. 6. Beaded black as claimed in claim 1, wherein the pelletising additives are matures of waxes, mixtures of resins or mixtures of waxes and reshs. 7. Beaded black as claimed in claim 1, wherein the synthetic oils are mineral oils. 8. Process for the production of beaded black as claimed in claim 1, wherein powdered carbon black and oil/pelletising additive mixtures are mixed together. 9. Process as claimed in claim 8, wherein the oil/pelletising additive mixture is sprayed onto the starting black ahead of the pelletising machine or In the first third of the pelletising machine whilst it is still In powder form in a pelletising machine with a pin shaft, whereby the pelletising machine displays an intake zone, a mixing and pelletising zone and an outlet zone, by feeding powdered carbon black into the intake zone of the pelletising machine and continuously removing the carbon black from the outlet of the pelletising machine. 10. Process as claimed in claim 9, wherein the oil/pelletising additive mixture is sprayed over the starting carbon black whilst it is still in powder form by means of 1 to 6 nozzles, whereby the nozzles are arranged on one level perpendicular to the axis of the pin shaft 11. Process as claimed in claim 9, wherein the retention time of the carbon black in the pelletising mixture is adjusted to a value between 20 and 600 seconds. 12. Process as claimed in claim 9, wherein up to 60 wt.% of beaded black in the same grades of carbon black is added to the powdered carbon black as an inoculum. 13. Process as claimed in claim 9, wherein the powdered carbon black is precompressed to a buk density of ISO to 350 g/l before pelletising. The invention concerns a beaded black containing at least one pelletising additive and at least one synthetic oil. The beaded black can be produced in a pelletising machine and used as a filler and/or pigment in rubber and plastic articles and as a pigment for the production of printing inks.

Documents:

00678-cal-2001-abstract.pdf

00678-cal-2001-claims.pdf

00678-cal-2001-correspondence.pdf

00678-cal-2001-description (complete).pdf

00678-cal-2001-drawings.pdf

00678-cal-2001-form 1.pdf

00678-cal-2001-form 18.pdf

00678-cal-2001-form 2.pdf

00678-cal-2001-form 3.pdf

00678-cal-2001-form 5.pdf

00678-cal-2001-gpa.pdf

00678-cal-2001-letter patent.pdf

00678-cal-2001-priority document others.pdf

00678-cal-2001-priority document.pdf