The disclosure relates to carbon black pellets containing 10 to less than 48 weight % organic compound, formed by agglomerating a carbon black with an organic compound having specified characteristics. Also disclosed is the use of such pellets as a masterbatch or a concentrate.

This invention relates to the formation of carbon black pellets with a 
molten organic compound or mixture of organic compounds. The products can 
be used in many applications and are particularly useful for either 
producing black loaded masterbatches or for directly introducing carbon 
black into polymeric or elastomeric media. 
BACKGROUND OF THE ART 
As produced, carbon blacks are powdery materials with bulk densities 
ranging from about 0.02 to 0.1 g/cc and are termed fluffy blacks. Because 
of their low densities and large surface areas, the fluffy products are 
cohesive, have very poor conveying properties and are very dusty. They 
are, however, dispersible. Because of their poor handling properties, 
advantage of their excellent dispersibilities cannot be taken in many 
applications. For example, fluffy blacks cannot be fed in a controlled 
manner to standard dispersing devices, such as Banbury mixers, twin screw 
extruders or the like. 
To improve their handling properties, the fluffy products are densified. 
For a given grade of black, handling properties tend to improve with 
increasing degrees of densification. Dispersibility, on the other hand, is 
progressively degraded as the extent of densification is increased. Thus 
there is a tradeoff between improvement in bulk handling and degradation 
in dispersibility. For this reason, the extent and means employed to 
densify the fluffy products depend on their intended uses. 
The industry, in general, uses three basic methods to attain densification. 
These, in order of providing increased levels of densification, are: 
agitation or vacuum treatment of the fluffy product, dry pelletization and 
wet pelletization. Since the performance of carbon black in many 
applications depends on the degree of dispersion attained, the acceptable 
extent of densification achieved depends on the user's dispersion 
equipment and, especially, on the shearing stresses generated. The process 
of agitation or vacuum treatment yields a powder which cannot be bulk 
handled and is supplied only in a bagged form. Nevertheless, because this 
form of the product is much more dispersible than its more dense 
counterparts, it is used in applications where easy dispersion is 
mandatory. 
Dry pelletization is conducted in rotating drums. Industrial drums have 
diameters of 6 to 10 feet and lengths of 20 to 40 feet which are rotated 
at 5 to 20 RPM. The fluffy product is fed continuously to one end of the 
drum. Tumbling of the dry black results in the formation of small round 
pellets. The process of pellet formation is facilitated by the use of seed 
pellets, which, typically, consist of part of the product pellets which 
are recycled to the feeding end of the drum. Generally, the products 
formed in dry drums have relatively low densities and, hence, are 
relatively weak and have low attrition resistances. As a consequence, 
conveying can cause pellet breakdown which leads to a degradation in their 
bulk handling properties. Many methods are available for enhancing pellet 
strengths. These methods include addition of small quantities of oil and 
binder. 
Wet pelletizing is conducted in pin pelletizers. Such units consist of a 
cylinder which is 0.4 to 1.5 m in diameter and up to 3 to 4 m long. Along 
the axis of the unit is a rotating shaft which is fitted with a multitude 
of pins, typically, arranged in the form of helices with the pins 
extending almost to the cylinder wall. The rotational velocity of the 
shaft depends on the diameter of the unit and the intensity of pelletizing 
desired. Rotation speeds can range from 300 up to 1500 RPM. The fluffy 
black and water are continuously added to the unit. The combination of 
capillary forces generated by the water in the black-water mixture and the 
mechanical action of the pins results in the formation of spherical, wet 
pellets with diameters, mostly, in the range of 0.25 to 3 mm. The 
water/black ratio required in the pelletizing operation depends on the 
structure of the black and, in many cases, is in the range of 1:1. The wet 
pellets exiting the pelletizer are then dried in rotary driers. Because of 
the high moisture contents in the pellets, drying represents a costly unit 
operation. 
Despite the reduction in pellet dispersibilities and the attendant costs of 
drying, pin pelletizing is extensively practiced because it yields more 
dense, attrition-resistant pellets than the dry process. Further, binders, 
such as lignosulfonates, sugars or molasses as well as additives such as 
polyoxyethylene nonionic surfactants, substituted polyethylene glycol, 
etc. can be easily added to the pelletizing water. These serve to 
strengthen or, when surfactants are used, strengthen and improve the 
dispersibilities of the dried pellets. 
The industry has also attempted to improve the tradeoff between enhanced 
pellet strength and degradation in dispersibility by providing 
moisture-free, oil-containing pellets. A maximum of 8 weight % oil in the 
black can be tolerated without changing its hazard classification. Oil can 
be easily incorporated in a black by means of the dry pelletization 
process. At oil levels much above 15 weight %, the pellets have been 
characterized as being "too soft and mushy to handle well in bulk". 
Aqueous emulsions of oil have been used to form oil-containing pellets in 
various mixing devices. It can be expected that, in most cases, drying 
will result in loss of oil by steam distillation and necessitate 
additional processing steps. 
Pin pelletizing can also be accomplished with pure oil in place of 
water/oil emulsions. In such instances water removal by drying is not 
required so that loss of the oil will no longer occur. However, for pellet 
formation, the oil contents of pellets will be substantially larger than 8 
weight %, necessitating a change in their hazard classification. 
Another approach taken to improve the tradeoff between enhanced pellet 
strength and reduced dispersibility has been to pelletize carbon black 
with aqueous media containing latexes which are compatible with rubber. 
The resulting pellet compositions, after drying, were found to have 
superior handling and dispersibility properties in rubber applications. 
Other workers, as described in U.S. Pat. No. 4,569,834, have pelletized 
carbon black with aqueous dispersions of waxy polyalkalenes, such as 
polyethylene waxes, and also found that the dried pellets exhibited 
improved handling and dispersibility properties. In these cases, however, 
pelletizing is effected in the presence of water so that drying, a costly 
unit operation, has to be employed. Also, the additives must be either 
available as or formed into aqueous emulsions or dispersions. Further, 
they must be thermally stable at the maximum drying temperatures attained 
in the rotary dryers used in the industry. These factors limit the range 
of materials which can be used in the pelletizing operation. A further 
limitation is that the additive must be compatible with the medium in 
which it is used. Nevertheless, such pellet compositions, formed by pin 
pelletizing carbon black with aqueous emulsions and dispersions of various 
compounds, have utility. 
Other workers have developed an improved agglomeration process wherein an 
aqueous slurry of carbon black is mixed with an oil having a softening 
temperature in excess of about 100.degree. C. 
Mednikov et al. used up to 5 weight % of molten high density polyethylene, 
having a melt temperature of 125.degree. to 135.degree. C., to strengthen 
dry process pellets. This disclosure is found in Mednikov, M. M., V. M. 
Osipov, I. G. Zaidman, V. I. Ivanovskii, S. V. Oreklov and A. I. 
Ryabinkov, "The Use of PE in Dry Pelletization of Carbon Black," 
International Polymer Science and Technology, Vol. 9, No. 1, T/37 (1982). 
The viscosity of such polymers are high with typical values exceeding 20 
Pa.multidot.s at a shear rate of 10 s.sup.-1 at 190.degree. C. These 
workers introduced solid polyethylene into air-borne fluffy carbon black 
having a temperature of 180.degree. to 210.degree. C. It was claimed that 
the polymer melted and was then adsorbed onto the surface of the black. 
The black was subsequently dry pelletized at an unspecified temperature to 
give pellets which had mass pellet strengths which were 2 to 5 kg higher 
than those, about 8 kg, formed in the absence of the polyethylene. While 
the process of Mednikov et al. gives some enhancement in pellet strength, 
the gain in strength attained was relatively small. Further 
exemplification of the foregoing disclosure appears in East German Patent 
No. 133,442 covering this technology. It should be noted that in Example 1 
of this patent it is stated that the polyethylene used had a molecular 
weight of 2600. This is inconsistent with the stated molecular weight 
range of 15000 to 150000 said to be useful for the practice of the 
invention. Furthermore, as stated in the patent, the molten polyethylene 
serves as a site for forming agglomerates (by adhesion of the black to its 
surface). This indicates that the molten polymer is viscous. Otherwise, 
the polyethylene, being present as a minor constituent (less than 5 weight 
%) would have migrated into the intra-aggregate pores. For this reason, it 
would appear that the stated molecular weight for the polyethylene in 
Example 1 is not a correctly stated value. This contention is supported by 
the data in the present application where it is established that no 
strength enhancement is attained when using a low viscosity melt at the 
levels utilized in East German Patent 133,442. 
Another approach to form dispersible pellets with good bulk handling 
properties was taken by Wallcott in U.S. Pat. No. 3,429,958. Wallcott 
pelletized carbon black with a molten paraffin wax in a pin mixer. The 
resultant cooled pellets, containing about 50 weight % wax, were 
free-flowing and found to be more dispersible than conventional wet 
process pellets in ink media. In his work, Wallcott used HAF (DBP=102 
cc/100 g), SAF (DBP=113 cc/100 g) and ISAF (DBP=114 cc/100 g) blacks as 
examples of furnace blacks. Wallcott stated that, for furnace blacks, the 
weight ratio of carbon black to wax must be in the order of about 50:50 
and claimed that the ratio must lie between 50:50 to 30:70. Thus, the 
process requires the use of relatively high wax levels. 
The process developed by Walcott represents a considerable advance in the 
art. However, for many applications the wax levels employed by Wallcot are 
excessive. In many applications there is a preferred wax level (e.g., for 
lubricity, mold release, gloss, improved mar resistance, etc.) above which 
product performance is degraded. The preferred wax level, often, is 
smaller than the black loading. Accordingly, use of pellets containing 50% 
or more wax to attain the desired black loading will, inevitably, result 
in the addition of more than the desired wax level leading to a 
degradation in performance and increased costs. For certain applications 
it is preferred that the wax level of the pellets always be less than 48% 
by weight. Moreover, as will be further described, the process of pin 
pelletization becomes progressively more difficult as the level of liquid 
wax is increased and, for many blacks, becomes impossible at a 48% wax 
level. 
The difficulties encountered both in handling carbon black pellets and in 
pellet dispersion have resulted in the establishment of businesses which 
produce concentrated dispersions of carbon blacks in aqueous and 
non-aqueous media (often referred to as masterbatches or concentrates). 
The production of masterbatches in thermoplastic polymers is of special 
importance. In this application, pelletized black is dispersed in a 
heated, viscous thermoplastic material such as polyethylene, 
polypropylene, acrylonitrile-butadiene-styrene copolymer, ethylene vinyl 
acetate, etc. Dispersion is effected in standard dispersing equipment such 
as Banbury mixers or twin screw extruders or the like. For production of 
acceptable masterbatches, the formation of good quality dispersions is of 
critical importance. After the dispersion process is complete, the 
masterbatch is, for example, extruded and then sliced into pellets for 
shipment. 
The loading of black in the pellets is, as implied by the name 
"concentrate", quite high and will depend on the structure of the black. 
Carbon black consists of aggregates composed of partially coalesced 
primary particles. The spaces between the primary particles form the 
intra-aggregate void or pore volume. Structure has been shown to be 
related to the average number of primary particles per aggregate. This is 
found in Medalia, A. I., "Morphology of Aggregates: 6. Effective Volume of 
Aggregates of Carbon Black From Electron Microscopy: Application to 
Vehicle Absorption and to Die Swell in Filled Rubber," J. Colloid and 
Interface Science, 32, 115 (1970). A measure of this volume can be found 
by evaluating the n-dibutyl phthalate absorption, DBP, of the black by 
means of the ASTM D 2414 procedure. This value represents a measure of the 
volume of liquid required to fill the intra- and inter-aggregate pores of 
the dispersed black at the capillary state. The carbon black aggregates, 
in the black-DBP mix at the capillary state, are taken to be close to 
their maximum packing fraction. 
For economic reasons, high loadings of black in a masterbatch or 
concentrate are preferred. However, for rapid incorporation during 
let-down, the viscosity of the concentrate should not be very different 
from that of the medium in which it is being dispersed. Concentrate 
viscosity increases with pigment loading and approaches a high value as 
its solids content approaches that required for the pigment to attain its 
maximum packing fraction. Accordingly, to obtain acceptable viscosities, 
the black loading in a masterbatch will be less than that at which it 
attains its maximum packing fraction and, hence, contains little or no 
air. In other words, the black loading is less than that required to 
achieve the capillary state. 
In contrast to conventional masterbatches, the pellets of this invention 
are formed at black loadings which exceed the capillary state so that they 
contain air. As a consequence, they can appear to be much more viscous 
than conventional masterbatches. The effect of air on viscosity, however, 
is mitigated in pressure rheometers because the high pressure employed can 
reduce the volume of voids between the black aggregates. Medalia and 
Sawyer have demonstrated that carbon blacks are highly compressible. This 
is discussed in Medalia, A. I., and R. L. Sawyer, "Compressibility of 
Carbon Black, Proc. Fifth Carbon Conference, 1961," Pergammon Press, N.Y., 
1963, p. 563. The criterion that the pellets of this invention are formed 
on the "dry" side of the capillary state (i.e., they contain air) in 
agglomeration devices with molten organic compounds in the absence of 
water may be used to distinguish them from conventional masterbatches, 
such as those described in the literature and which, typically, are formed 
on the "wet" side of the capillary state (i.e., the masterbatch pellets 
are essentially void-free). The expressions "dry" side and "wet" side of 
the capillary state are used solely to indicate whether pellets comprising 
a black-organic compound mixture contain air or are air-free, 
respectively. 
The maximum black content of a conventional masterbatch will depend on the 
maximum acceptable viscosity. For reasons already discussed, the volume of 
polymer in the masterbatch is substantially larger than that required to 
attain the capillary state as measured by the black DBP value. For the 
same masterbatch viscosity and for blacks with comparable surface areas, 
the loading that Can be achieved increases with decreasing black DBP. 
Black dispersibility decreases as black surface area increases and/or its 
DBP decreases. Because of difficulties encountered in their dispersion 
(and depending on the application), blacks with low DBP values and very 
high surface areas are rarely used to form masterbatches. For example, for 
applications where jetness or UV protection is needed, the black must have 
a minimum surface area. To form acceptable concentrates with a black 
having a high surface area, a high DBP product may often be used in 
concentrate formation. Thus, practical considerations dictate that in 
masterbatch formation a compromise be struck between black loading and 
dispersion quality. For this reason, blacks with the lowest attainable DBP 
values are rarely used in the production of black masterbatches. 
In spite of their costs, the market for black concentrates or masterbatches 
is substantial because the resulting products are dust-free, easily 
conveyed and much more easily dispersed in compatible thermoplastic media 
than conventionally pelletized blacks. Surprisingly, we have found that 
carbon blacks pelletized with a molten organic compound or a mixture of 
organic compounds which are solid at ambient temperatures, can be used in 
place of concentrates without significant loss in performance. 
SUMMARY OF THE INVENTION 
The present invention concerns the formation and use of free-flowing, 
attrition resistant, dispersible carbon black pellets. By taking advantage 
of these properties, the products can be used in place of conventional 
carbon black pellets in applications such as: 
1) Forming carbon black loaded masterbatches. 
2) Attaining higher black loadings in conventional masterbatches by using 
lower structure (i.e., lower DBP) blacks without increasing their 
viscosities or degrading the state of dispersion attained with the higher 
structure (i.e., higher DBP) products. 
3) Replacing the use of conventional masterbatches for introducing carbon 
black into polymeric media. 
Accordingly, in a first embodiment the present invention provides a carbon 
black pellet comprising carbon black and 10 to less than 48% by weight of 
an organic compound or a mixture of organic compounds, said pellet having 
been formed by agglomeration at a temperature above the melting point of 
the organic compound or mixture of organic compounds in the absence of 
water, wherein the organic compound or mixture of organic compounds has 
the following characteristics: 
a) a melting point of at least 25.degree. C. and, preferably, higher than 
45.degree. C., 
b) when molten and at the agglomeration temperature employed, exhibits less 
than 5% decomposition or degradation, 
c) when molten and at the agglomeration temperature employed, exhibits a 
viscosity below 2 Pa.s at a shear rate of 10 s.sup.-1, and 
d) when molten, wets the carbon black. The agglomeration method used to 
form the pellet is preferably dry pelletization or pin pelletization. The 
organic compound or mixture of organic compounds is preferably at least 
one of a non-polymeric organic compound, an organic thermoplastic 
homopolymer, an organic thermoplastic copolymer, and a wax. 
The present invention also provides a method of using a pellet according to 
the invention as a masterbatch or a concentrate. 
Additional features and advantages of the invention are set forth in the 
detailed description which follows or may be learned by the practice of 
the invention. The objectives and advantages of the invention will be 
realized and attained by the various embodiments described in the detailed 
description and pointed out in the claims. 
DETAILED DESCRIPTION OF THE INVENTION 
The pellets of the present invention can be formed by agglomeration, either 
under conditions of violent agitation as in conventional continuous pin 
pelletizers or under much more gentle conditions as in dry drums. 
Accordingly, since the degree of agitation in most pelletizing devices, 
such as disc pelletizers, briquetting units, roll compactors, shear 
mixers, etc., are intermediate between those of dry drums and pin 
pelletizers, most agglomerating devices will be suitable, under 
appropriate conditions, for the practice of the present invention. For 
example, in the case of pin pelletizing, and as shown by Wallcott for 
paraffin wax, a molten organic compound or mixture of compounds can be 
used in place of water, traditionally employed as the cohesive fluid 
holding the wet pellets together. A liquid is regarded as wetting when its 
contact angle with the solid is less than 90.degree.. In the case of dry 
drum pelletizing, the molten organic compound or compound mixture can be 
introduced in an analogous manner to the oils currently employed. The 
contents of the drum, however, must be maintained at temperatures above 
the melting point of the meltable compound or compound mixture. 
The organic compound or compound mixture used in the pelletizing process is 
preferably chosen so that it is compatible with the medium in which the 
pelletized product is to be dispersed. A compatible compound is one which 
is soluble or miscible in the application medium at least at the level at 
which it is employed and, more preferably, has substantially greater 
solubility or miscibility than the level employed. 
The molten organic compound or mixture of organic compounds, at the 
pelletizing temperature employed, must be resistant to decomposition or 
degradation. Suitable organic compounds or mixture of organic compounds 
are those which exhibit less than 5% decomposition or degradation when 
molten and at the agglomeration temperature. 
Organic compounds or mixture of organic compounds which are suitable for 
use in forming the pelletized products of this invention must meet the 
following requirements: 
1) They are solid at temperatures normally encountered during the 
conveying/handling/transport/storage of carbon black. Thus they should be 
solid at temperatures of at least 25.degree. C. and, more preferably, 
higher than 45.degree. C. 
2) In the molten state and at the pelletizing temperature employed, they 
exhibit decomposition or degradation in an amount less than 5%. 
3) In the molten state and at the pelletizing temperature employed, they 
exhibit a relatively low viscosity, below about 2 Pa.s at a shear rate of 
10 s.sup.-1, so that they can be atomized or transformed into small 
droplets. 
4) They wet carbon black. 
Preferably, the organic compound or mixture of organic compounds is also 
compatible with the intended use application. 
Examples of suitable materials include, but are not limited to, simple 
organic compounds, polymeric materials, blends of simple organic 
compounds, thermoplastic homopolymers and copolymers, blends of homo- and 
co-polymers as well as blends of simple organic compounds with polymeric 
materials. The pelletized products, after cooling to a temperature below 
the melting point of the organic compound(s), consist of dispersible, 
free-flowing, hard, attrition resistant, non-dusting pellets which have 
excellent dispersibility characteristics. In other words, the tradeoff 
between improvement in bulk handling and degradation in dispersibility is 
substantially improved. In many instances the pelletized products of this 
invention can be used either to form concentrates or, more advantageously, 
directly in place of concentrates for introducing carbon black into 
polymeric media. 
In a preferred embodiment, the organic compound or mixture of organic 
compounds is a polymeric wax such as polyethylene wax, an ethylene vinyl 
acetate wax and the like as well as mixtures of these waxes. Such waxes 
contemplated for use are well known in the art and are supplied 
commercially by various companies including Allied Signal, under the 
tradename of A-C.RTM. polyethylenes and A-C.RTM. copolymers, BASF Corp, 
under the tradenames of LUWAX.RTM. and Morttan Waxes, and Eastman Kodak, 
under the tradename of EPOLENE waxes. The waxes are used as mold release 
agents and/or lubricants in rubber, plastics and coatings applications. In 
addition, they function as pigment dispersants and are often employed in 
conventional black masterbatch formulations. They are used sparingly 
because, at larger than optimum levels, they can adversely affect medium 
properties and/or provide over-lubrication. In most applications, after 
let-down, the black loading will be significantly larger than that of the 
wax. The organic compounds or mixtures of organic compounds are discussed 
in more detail below. 
The present invention involves the formation and use of hard, dust-free, 
attrition resistant carbon black pellets. They may be used for many 
purposes such as for forming concentrates or for use in place of 
conventional concentrates for introducing up to 5 weight percent carbon 
black into coating and thermoplastic polymeric media. The pellets of the 
present invention are formed by agglomeration, most conveniently, in 
conventional continuous pin pelletizers and dry drums using a molten 
organic compound or mixture of organic compounds as the cohesive fluid 
holding the pellets together in the absence of water. To avoid introducing 
undesired amounts of organic compound(s) in the intended use application, 
the pellets comprise carbon black and 10 to less than 50% by weight of the 
organic compound(s). 
The volume of liquid (water, oil or molten organic compound) used in pellet 
formation has a large effect on the strength of the "wet" pellets. Ayala 
et al., have distinguished several pellet states at successively 
increasing liquid levels. This is described in Ayala, R. E., P. A. Hartley 
and G. D. Parfitt, "The Relevance of Powder/Liquid Wettability to the 
Cohesiveness of Carbon Black Agglomerates," Part. Caract., 3, 26-31 
(1986). The states are: 1) the dry pellet state; 2) the pendular state 
where the voids in a pellet are partially filled with liquid which forms 
bridges between adjacent aggregates; 3) the funicular state where adjacent 
pendular rings have coalesced into a continuous network of liquid 
interspersed with pockets of air; 4) the capillary state where the liquid 
just fills all the void spaces in the pellet so that the menisci at the 
pellet surface provide the maximum capillary suction pressure; and 5) the 
slurry state where the liquid level exceeds that required for the 
capillary state. The cohesive force, provided by a liquid which wets the 
black, increases with increasing liquid level and attains its maximum 
value at the capillary state. Beyond the capillary state there is a rapid 
diminution in cohesivity with small increases in liquid level. Wet pellet 
strength increases with increasing cohesivity. 
In view of the very different nature of the compaction forces involved in 
pin and dry drum pelletization, the amounts of liquid required for pellet 
formation in the two processes may differ. The liquid requirements for 
these two operations as well as those required for other agglomeration 
devices are discussed in turn. 
Pin Pelletizing 
In pin pelletizing, the mechanical action of the rapidly moving pins serves 
to orient the black aggregates into closer proximity while the liquid 
provides the necessary cohesivity to hold the aggregates in the pellet 
together. Without the presence of a minimum amount of liquid, the force of 
the impacts of the rapidly moving pins with existing pellets would result 
in pellet fragmentation. In other words, a minimum degree of cohesivity is 
mandatory for successfully effecting pellet formation in a pin pelletizer. 
With carbon black sufficient cohesivity is attained when the liquid level 
in the pellets lies between those required to attain the pendular and 
capillary states. On the other hand, when the liquid level substantially 
exceeds that required to attain the capillary state, a wetted coherent 
mass is formed which inhibits pellet formation and product discharge from 
the pelletizer. In addition, the power level required to run the 
pelletizer increases rapidly with small increases in liquid content 
(beyond the capillary state) while the quality of the pellets discharged, 
in terms of sphericity and uniformity decreases. 
Accordingly, for pellet formation in a pin pelletizer, the volume of liquid 
added to the black must be greater than that required for the onset of 
substantial pendular bond formation and less than that required to attain 
the capillary state. Preferably, pellet formation is effected in the 
pendular and/or funicular states where the resulting pellets contain air 
voids. 
A good measure of the liquid level required to attain the capillary state 
can be obtained from the DBP value of the fluffy black (termed FDBP). This 
quantity provides a measure of the volume of DBP required to attain the 
capillary state in the black-DBP mixture and is comparable in magnitude 
with the volume of liquid required to attain the capillary state in a 
pellet. Accordingly, the weight percent liquid content of pellets exiting 
a pin pelletizer, W.sub.liq,max should be less than the quantity 
EQU W.sub.liq,max .ltoreq..rho..sub.liq [100(FDBP)]/[100+.rho..sub.liq 
(FDBP)](1) 
where FDBP is expressed in cc/100 g black and .rho..sub.liq is the density 
of the molten compound(s) in g/cc. Since for most organic compounds 
.rho..sub.liq .ltoreq.1.0 g/cc, the criterion that W.sub.liq,max is less 
than 48% is always attained when pin pelletizing blacks with FDBP values 
equal to or smaller than 92 cc/100 g. 
The onset of substantial pendular bond formation occurs when all the 
intra-aggregate pores are filled and large numbers of liquid bridges 
between the carbon black aggregates just begin to form. The aggregate is 
the smallest dispersible unit of carbon black. It is composed of coalesced 
primary particles. For non-porous primary particles, primary particle size 
is inversely proportional to black surface area. Between the primary 
particles, forming the aggregate, are voids or pores. Since the 
intra-aggregate pores are the smallest ones present in a pellet, they are 
filled first by a wetting liquid. Only after the intra-aggregate pore 
volume, also termed the occluded volume, is filled can a large number of 
cohesive, inter-aggregate pendular bonds be formed. 
Medalia has developed a procedure for estimating the occluded volume from 
DBP values. This is described in Medalia, A. I., "Effective Degree of 
Immobilization of Rubber Occluded within Carbon Black Aggregates," Rubber 
Chemistry & Technology, 45, (5), 1172 (1972). A measure of the occluded 
volume, .phi., on a cc/g carbon black basis, can be obtained using the 
relationship 
EQU .phi.=[(DBP)-21.5]/127.0 (2) 
The DBP attained during the pelletization process will depend on the 
intensity of the pelletization process and will lie somewhere between the 
FDBP and the crushed DBP, CDBP, values. The CDBP is determined by the ASTM 
D 3493-93 procedure. Typically, the CDBP value is 15 to 25%, say 20%, 
smaller than the FDBP value. Thus, a measure of the minimum occluded 
volume is obtained by using the CDBP value in place of DBP in Equation 
(2), i.e., 
EQU .phi.=[(CDBP)-21.5]/127.0 
Since pendular bonds are required to provide the cohesivity necessary to 
hold the pellets together in a pin pelletizer, the minimum percent liquid 
content, W.sub.liq,min, necessary for pin pelletization can be written as 
EQU W.sub.liq,min .ltoreq..rho..sub.liq (100.phi.)/(1+.rho..sub.liq .phi.)(3) 
Thus, for example, for a black with a FDBP value of 92 cc/100 g black, the 
minimum level of molten organic compound required for pellet formation 
(assuming .rho..sub.liq =1.0 g/cc and CDBP to be 73.6 cc/100 g carbon 
black) is computed to be 29.1%. Accordingly, for a black with a FDBP value 
of 92 cc/100 g black, the organic liquid content will be within the range 
of 29.1 to 48% and, under practical pelletizing conditions (where the 
pellets contain some voids and have a DBP which lies between the CDBP and 
the FDBP), the amount of organic compound in the pellets will be about 
38.5 weight %. Moreover, as the FDBP value is reduced, the products will 
contain smaller amounts of the organic material. 
Dry Pelletizing 
As already noted, pellets are formed in dry drum under much less severe 
conditions than in pin pelletizers. As a consequence, the decrease in the 
FDBP is small. Moreover, pellets can be formed without the presence of a 
cohesive liquid. The resulting pellets, however, have low densities and 
are weak. Strength enhancement can be attained by the addition of a 
certain minimum level of a meltable organic compound or mixture of organic 
compounds. The extent of strength enhancement attained will depend on the 
amount of organic compound or mixture of organic compounds added. At low 
melt levels, the bulk of the liquid moves to the intra-aggregate zones and 
little strength enhancement is attained. As the amount of molten organic 
compound or mixture of organic compounds added is increased, some strength 
enhancement results in spite of incomplete filling of the intra-aggregate 
pores. This strength enhancement occurs because some of the aggregates 
forming the pellet are in sufficiently close proximity to each other that 
some pendular bond formation takes place. As will be shown, some pellet 
strength enhancement can occur at molten organic addition levels as low as 
10 weight %. 
A preferred means for effecting dry pelletization is to first form a 
uniform mix of the fluffy black with the desired molten organic 
compound(s). Such mixtures can be formed, for example, by continuously 
feeding the fluffy black and the molten organic material to a grinder or 
other high intensity milling device. More preferably, when the molten 
compound(s) level is below that required to attain the pendular state, the 
fluffy black and the atomized molten material can be mixed in a 
conventional continuous pin pelletizer. Thereafter, the fluffy 
black/organic compound mixture can be fed to a heated drum together with 
recycled product pellets. 
Alternate Pelletizing Procedures 
As noted previously, alternate pelletizing procedures can be used to 
produce the products of this invention. The only limitations are that 
pelletization is effected in the absence of water and that the amount of 
molten organic material employed be more than 10 and less than 48 weight % 
of the pelletized composition. Particularly favored alternate means of 
pelletizing include the use of disc pelletizers and one of the various 
compacting devices. 
Suitable Meltable Compounds 
Organic compounds or mixture of compounds which are suitable for use in 
forming the products of this invention must have the following 
characteristics: 
1) They are solid at temperatures normally encountered during the 
conveying/handling/transport/storage of carbon black. Thus they should be 
solid at temperatures of at least 25.degree. C. and, more preferably, 
higher than 45.degree. C. 
2) In the molten state and at the pelletizing temperature employed, they 
exhibit decomposition or degradation in an amount less than 5%. 
3) In the molten state and at the pelletizing temperature employed, they 
exhibit a relatively low viscosity, below about 2 Pa.s at a shear rate of 
10 s.sup.-1, so that they can be atomized or transformed into small 
droplets. 
4) They wet carbon black. 
Preferably, the organic compound or mixture of organic compounds is also 
compatible with the intended use application. 
Examples of suitable organic compounds include simple organic compounds, 
polymeric materials, blends of simple organic compounds, thermoplastic 
homopolymers and copolymers, blends of homo- and co-polymers as well as 
blends of simple organic compounds with polymeric materials and mixtures 
thereof. Preferred polymeric compounds are: 
1) Ethylene homopolymers or copolymers with at least one of the monomers 
consisting of butene, hexene, octene, norbornene, vinyl acetate, acrylic 
acid (present as acid or ionomer), methacrylic acid (present as acid or 
ionomer), alkyl (C.sub.1 to C.sub.9) acrylate, maleic anhydride, monoester 
of maleic acid and carbon monoxide. 
2) Propylene homopolymers (atactic, isotactic and syndiotactic forms) and 
copolymers with ethylene; polynorbornene; polyoctenamer. 
3) Styrene homopolymers or copolymers with at least one of the following: 
.alpha. methyl styrene, vinyl toluene, acrylonitrile, butadiene, maleic 
anhydride, indene, coumarone and alkyl acrylates. 
4) Polyethylene glycols; ethylene oxide and propolyene oxide homopolymers 
and random or block copolymers; ethoxylated or ethoxylated/propoxylated 
phenols, alkyl phenols, aliphatic amines, aliphatic amides, polyhydric 
alcohols, polyhydric alcohol esters and polyamines. 
5) Resins produced from the esterification of wood rosin, gum rosin, tall 
oil rosin, abietic acid (or their hydrogenated derivatives) with a 
polyhydric alcohol selected from ethylene glycol, glycerol or 
pentaerythritol. 
6) Condensation products of a dimer acid with a diol or diamine; 
polycaprolactone or polycaprolactam. 
Especially preferred are the polymeric materials which have relatively low 
molecular weights so that they melt and form low viscosity liquids at 
reasonably low temperatures such as polyethylene, polyethylene-polybutene, 
ethylene-acrylic acid and ethylene-vinyl acetate waxes available 
commercially. The organic compounds may also contain small amounts of 
additives such as dispersants, UV stabilizers and anti-oxidants. The 
additives may be either solid or liquid at ambient temperatures as long as 
the total composition employed in the pelletizing operation has the 
stipulated characteristics. The potential number of organic compounds or 
mixture of compounds which satisfy the stipulated characteristics is 
large. 
Agglomerating or pelletizing can be carried out in conventional pelletizers 
or compacting devices provided that the following requirements are 
fulfilled: 
1) A means is provided for melting and introducing the desired molten 
compound or mixture of compounds into either the unit employed to 
distribute it evenly on the fluffy black or in the pelletizer. 
2) The black temperature is at or above the melting point of the organic 
compound or mixture of organic compounds. 
3) The pelletizer contents are maintained at or above the melting point of 
the organic compound or mixture of organic compounds. 
4) A means is provided for cooling the agglomerated or pelletized product 
to a temperature below the solidification temperature of the molten 
material. 
The agglomerated or pelletized product, after cooling to a temperature 
below the melting point of the organic compound or mixture of organic 
compounds, consists of dispersible, free-flowing, hard, attrition 
resistant, non-dusting pellets preferably having mean sizes in the range 
of 0.2 to 6.0 mm. Strength enhancement occurs because the pendular and 
funicular bonds have solidified and form solid inter-aggregate bridges. 
Such bridges are much stronger than the van der Waals attractive forces 
and, are rigid and, in many cases, stronger than liquid bridges present in 
oil pellets. 
The following examples are intended to illustrate, not limit, the present 
invention. 
Experimental 
Batch Pin Pelletizing 
Sample preparation was conducted in an 8-inch diameter by 8-inch long batch 
pin pelletizer. The central shaft was fitted with fourteen 0.5-inch 
diameter pins which extended almost to the cylinder wall. The shaft speed 
could be varied from 100 up to about 1700 RPM. The cylindrical wall of the 
unit could be heated electrically to temperatures up to 300.degree. C. 
Pelletizing was effected by placing a known weight of black (typically, 400 
g) in the pelletizer. Thereafter, the fluid was, generally, added while 
the rotor was turning at 50 to 100 RPM. When water was the cohesive fluid, 
it was sprayed into the pelletizer via an atomizer. When a molten organic 
compound or mixture of compounds represented the cohesive fluid, it was 
poured into the preheated pelletizer (wall temperature of 200.degree. to 
300.degree. C.) when the black temperature approached that required to 
melt the organic compound(s). It should be noted that in batch pelletizers 
the temperature of the black need not be at or above the melting 
temperature of the molten compound(s). In the presence of the compound and 
at the high pelletizer wall temperatures used here, the temperature of the 
mix rapidly rises to temperatures above the melting temperature of the 
organic compound(s). After addition of the molten material, the pelletizer 
RPM was adjusted to the desired value. Typically, pellet formation 
occurred within three minutes with the organic fluids and within 3 to 10 
minutes with water. 
Continuous Pin Pelletizing 
Hot fluffy black having a surface area of 43 m.sup.2 /g and a FDBP of 135 
cc/100 g was fed at the rate of about 180 lbs/hour to a 10-inch diameter 
61-inch long pelletizer. Molten wax, at a temperature of 175.degree. C., 
was added simultaneously via a pressure spray to the pelletizer. The walls 
of the pelletizer were maintained at a temperature of about 175.degree. C. 
The rotor, fitted with about 120 pins arranged in the form of a double 
helix, was rotated at specified RPM's. 
Dry Drum Pelletization 
Dry drum pelletization was effected in a 15.5-inch diameter by 24-inch 
length drum rotated at 20 to 35 RPM. The drum was maintained at a 
temperature of 55.degree. to 65.degree. C. The requisite amount of molten 
organic was mixed with the fluffy black in a blender. The resulting heated 
powder, containing 300 g of carbon black, was added over a period of about 
45 minutes to a 200 g bed of seed pellets in the rotating drum. The 
pelletization process was complete after about 4 hours. Initially, the 
seed pellets consisted of pellets formed in a pin pelletizer. In the 
second round of pelletization, product from the first round was used as 
seed pellets. Finally, in the third round of pelletization, product from 
the second round was used as seed. Under these conditions, the final 
product (from the third round) contains only 6.4% of the original seed 
material. 
Product Evaluation 
Pellet strength properties were evaluated by means of mass pellet strength 
(ASTM D1937-93), individual pellet crush strength (ASTM D3313-92) and 
pellet attrition (using a modification of ASTM D 4324) tests. The 
modification of the ASTM D4324 test consisted of determining the total 
amount of dust generated after shaking the sample for 5 and 20 minutes and 
not the difference in the amounts of dust generated between the two stated 
times, as required by the test. Tap densities were determined by placing a 
known weight of pellets, screened to a narrow size distribution, in a 
graduated cylinder and then tapping the sample to a constant volume. 
Dispersibility was evaluated both in plastic (ABS) and liquid media. 
Details of the procedures used are given later. 
The acrylonitrile butadiene styrene (ABS) copolymer was GPM 5600-0000 
manufactured by GE Plastics and was obtained from Polymerland Inc. The 
masterbatches for carbon blacks in ABS were compounded in a 1.6 liter 
capacity Banbury mixer at 20 to 50 weight % carbon black loadings. 
Apparent melt viscosities were measured on a Monsanto Processibility 
Tester (MPT) with a capillary having a length to diameter ratio of 20:1 
and a 1.5 mm diameter. The apparent viscosities were measured at a shear 
rate of 600 s.sup.-1 at a temperature of 230.degree. C. 
The masterbatches and wax containing pellets were letdown on a Battenfeld 
BA 500 E injection molder to a 1% loading of the black in ABS. The mass 
tone color, L* value, of the letdown was measured using a Hunter LabScan, 
(0,45) degree geometry, 10 degree observer, CIElab and D65 illuminant. The 
L* value declines as jetness (degree of blackness) increases. 
Izod impact strength was performed according to ASTM D256. The dispersion 
ratings were determined using the Cabot Dispersion Classification chart, 
"Carbon Black Dispersion," Cabot Corporation Technical Report S-131. In 
this procedure the letdown is viewed at a 100 fold magnification and the 
sizes and numbers of undispersed units are visually compared against those 
in a standard chart. The sizes of the undispersed units increase with 
increase in the value of the number rating (from 1 to 6) and their numbers 
increase progressively from A to F. 
Further experimental details are given in the Examples.

EXAMPLES 
Experiments were conducted to demonstrate that carbon blacks with differing 
structure levels (as measured by their FDBP values) and surface areas can 
be readily pelletized with a variety of molten organic compounds or 
mixtures of organic compounds which satisfy the criteria set forth above. 
These studies were conducted in the heated batch pin pelletizer. Unless 
otherwise stated, 400 g of fluffy black was used in the pelletizing 
operation. The FDBP and surface areas of the blacks employed, the 
compositions and amounts of the organic compounds used, the agglomerating 
conditions employed and the black contents of the pellets are listed 
below. 
Examples 1-6 
Preparation of Carbon Black Pellets 
In these examples the black used had a surface area of 140 m.sup.2 /g and a 
FDBP of 114 cc/100 g black. 
Example 1: The black was pelletized with 250 g AC-6 Polyethylene wax, 
melting point about 100.degree. C., at 500 RPM for 3 minutes to give 
pellets containing 61.5 weight % black. 
Example 2: The black was pelletized with 325 g AC-6 Polyethylene wax, 
melting point about 100.degree. C., at 500 RPM for 3 minutes to give 
pellets containing 55.2 weight % black. 
Example 3: The black was pelletized with a mixture of 245 g AC-6 
Polyethylene wax and 25 g of a liquid polyisobutylene succinimide 
surfactant (Lubrizol L2165), melting point about 90.degree. C., at 500 RPM 
for 3 minutes to give pellets containing 59.7 weight % black. 
Example 4: The black was pelletized with a mixture of 293 g AC-6 
Polyethylene wax and 32 g of a liquid polyisobutylene succinimide 
surfactant (Lubrizol L2165), melting point about 90.degree. C., at 500 RPM 
for 2.5 minutes to give pellets containing 55.2 weight % black. 
Example 5: The black was pelletized with 300 g of paraffin wax (Aldrich), 
melting point 53.degree. to 56.degree. C., at 500 RPM for 5 minutes to 
give pellets containing 57.1 weight % black. 
Example 6: The black was pelletized with 375 g of paraffin wax (Aldrich), 
melting point 53.degree. to 56.degree.100.degree. C., at 500 RPM for 1 
minutes to give pellets containing 51.6 weight % black. 
Examples 7-9 
Preparation of Carbon Black Pellets 
In these examples the black used had a surface area of 230 m.sup.2 /g and a 
FDBP of 70 cc/100 g black. 
Example 7: The black was pelletized with 180 g AC-6 Polyethylene wax, 
melting point about 100.degree. C., at 800 RPM for 3 minutes to give 
pellets containing 69.0 weight % black. 
Example 8: The black was pelletized with 216 g AC-6 Polyethylene wax, 
melting point about 100.degree. C., at 800 RPM for 3 minutes to give 
pellets containing 64.9 weight % black. 
Example 9: The black was pelletized with a mixture of 195 g AC-6 
Polyethylene wax and 21 g of a liquid polyisobutylene succinimide 
surfactant (Lubrizol L2165), melting point about 90.degree. C., at 500 RPM 
for 2 minutes to give pellets containing 64.9 weight % black. 
Examples 10-14 
Preparation of Carbon Black Pellets 
In these examples the black used had a surface area of 220 m.sup.2 /g and a 
FDBP of about 100 cc/100 g black. 
Example 10: The black was pelletized with 375 g CARBOWAX.RTM. polyethylene 
glycol having a molecular weight of about 1000 (PEG 1000, Union Carbide), 
melting point about 38.degree. C., at 500 RPM for 3 minutes to give 
pellets containing 51.6 weight % carbon. 
Example 11: The black was pelletized with a mixture of 135 g CARBOWAX.RTM. 
PEG 1000, a polyethylene glycol having a molecular weight of about 1000 
and 240 g of TERGITOL.RTM. XD, a surfactant based on a copolymer of 
ethylene and propylene oxides (Union Carbide), melting point above 
30.degree. C., at 500 RPM for 3 minutes to give pellets containing 51.6 
weight % carbon. 
Example 12: The black was pelletized with a mixture of 135 g CARBOWAX.RTM. 
PEG 1000, a polyethylene glycol having a molecular weight of about 1000 
and 240 g of TERGITOL.RTM. XH, a surfactant based on a copolymer of 
ethylene and propylene oxides (Union Carbide), melting point above 
30.degree. C., at 500 RPM for 3 minutes to give pellets containing 51.6 
weight % carbon. 
Example 13: The black was pelletized with a mixture of 135 g CARBOWAX.RTM. 
PEG 1000, a polyethylene glycol having a molecular weight of about 1000 
and 240 g of TERGITOL.RTM. XJ, a surfactant based on a copolymer of 
ethylene and propylene oxides (Union Carbide), melting point above 
30.degree. C., at 500 RPM for 3 minutes to give pellets containing 51.6 
weight % carbon. 
Example 14: The black was pelletized with 375 g of TERGITOL.RTM. XD, a 
surfactant based on a copolymer of ethylene and propylene oxides (Union 
Carbide), melting point above 30.degree. C., at 500 RPM for 3 minutes to 
give pellets containing 51.6 weight % carbon. 
Examples 15-16 
Preparation of Carbon Black Pellets 
In these examples the black used had a surface area of 42 m.sup.2 /g and a 
FDBP of about 124 cc/100 g black. 350 g fluffy black was placed in the 
pelletizer. 
Example 15: The black was pelletized with a mixture of 330 g polyethylene 
and polybutene waxes (15 and 85%, respectively, supplied by Allied 
Signal), melting point about 100.degree. C., at 800 RPM for a few minutes 
to give pellets containing 51.5 weight % black. 
Example 16: The black was pelletized with 348 g stearic acid, melting point 
about 71.degree. C., at 800 RPM for 6 minutes to give pellets containing 
50.1 weight % black. 
Examples 17-18 
Preparation of Carbon Black Pellets 
In these examples the black used (had a surface area of 42 m.sup.2 /g and a 
FDBP of about 124 cc/100 g black. 
Example 17: The black was pelletized with a mixture of 85 g PICCOVAR L-30 
and 85 g PICCO 6100 hydrocarbon resins, obtained from Hercules, having a 
melting point about 120.degree. C., at 500 RPM for 2 minutes to give 
pellets containing 70.2 weight % black. 
Example 18: The black was pelletized with a mixture of 100 g PICCOVAR L-30 
and 100 g PICCO 6100 hydrocarbon resins, obtained from Hercules, having a 
melting point about 120.degree. C., at 500 RPM for 1.3 minutes to give 
pellets containing 66.7 weight % black. 
As indicated by Equation (1), the pellets of the foregoing examples are all 
formed on the "dry" side of the capillary state, meaning that they contain 
air. 
Examples 19-22 
Determination of Pellet Volumes 
To further substantiate the assertion that the pellets contain air (i.e., 
voids), mercury porosimetry studies were conducted to determine the 
volumes of intra-pellet voids. The presence of such voids demonstrates 
that the pellets of the present invention contain air and, hence, are 
formed on the "dry" side of the capillary state. For these studies the 
pellets were formed in the batch pin pelletizer using either polyethylene 
(PE), Examples 19 and 20, or ethylene vinyl acetate (EVA), Examples 21 and 
22, waxes. In all cases the pellets were formed at 500 RPM using a black 
having a fluffy DBP of 74 cc/100 g and a surface area of 210 m.sup.2 /g. 
Screened pellets having sizes larger than about 300 microns were used in 
the porosimetry studies. 
A measure of the intra-pellet void volume was obtained by determining the 
volume of pores occupied by mercury at penetration pressures ranging from 
24 to 33000 psia, corresponding to a pore size range of 8900 (8.9 microns) 
to 6.5 nm. Since the pellets had sizes which were substantially larger 
than the pore size range considered and since substantial mercury 
intrusion occurred at lower penetration pressures, it is probable that the 
actual intra-pellet pore volumes are somewhat larger than the cited 
values. The volumes of black, taking its skeletal density to be 1.86 g/cc, 
wax, taking its density to be 0.92 g/cc and air in the pellets were 
computed. The results obtained are summarized in Table 1 and show that the 
pellets of the present invention are formed on the "dry" side of the 
capillary state. 
TABLE 1 
______________________________________ 
Pellet Volumes 
Example 
Wax Weight Pellet Volume, cc/g 
Volume 
Number Grade % Black Black Wax Air % Air 
______________________________________ 
19 PE 70.9 0.381 0.316 
0.105 13.1 
20 PE 69.0 0.371 0.337 
0.057 7.5 
21 EVA 70.9 0.381 0.316 
0.120 14.7 
22 EVA 69.0 0.371 0.337 
0.082 8.6 
______________________________________ 
Examples 23-26 
Continuous Pin Pelletizing 
Fluffy black with a FDBP of 140 cc/100 g and a surface area of 46 m.sup.2 
/g was pelletized with EVA wax in the continuous pelletizer at several 
rotor speeds. The samples obtained were characterized in terms of their 
wax contents (by thermogravimetric analysis), tap densities, mean size (by 
manual screening procedures), mass pellet strength, crush strength and 
attrition characteristics. The pellets were sufficiently strong that they 
exceeded the measuring capabilities of the instruments, 90 lbs for the 
mass pellet strength (MPS) test and 160 g for the pellet crush strength 
(PCS) test. The results obtained are shown in Table 2. 
TABLE 2 
______________________________________ 
Properties of Continuous Pin Pelletized Samples 
Mean Tap 5 20 
Example Weight Size, Density 
Minute Minute 
Number RPM % Black mm g/cc Dust, % 
Dust, % 
______________________________________ 
23 500 50.9 1.3 0.65 0.3 0.4 
24 .about.750 
57.9 0.82 0.63 3.8 4.0 
25 .about.760 
58.0 0.90 0.68 0.5 0.5 
26 940 59.6 1.2 0.78 0.1 0.1 
______________________________________ 
The results in the table show that as rotor RPM is increased, the black 
content of the pellets and the tap density tend to increase. This 
demonstrates that the wax content and densities of the pellets can be 
varied by changing the severity of the pelletizing operation. In all cases 
strong attrition-resistant pellets (as demonstrated by the small to 
negligible increases in the dust values between 5 and 20 minutes) were 
formed. 
The results in Table 2 also show that as the rotor RPM increases, the wax 
level required to maintain the pellets in the pendular and funicular 
states decreases. When the rotor RPM was further increased to 1150 RPM 
while the wax addition rate was kept at about the same level as in Example 
26, pelletization was effected on the "wet" side of the capillary state. 
As a result, the pelletizing operation became erratic, chunks rather than 
pellet were initially discharged, motorload requirements increased and, 
finally, caused a pelletizer shut down. Thus operation of the pelletizer 
on the "wet" side of the capillary state is not feasible. 
Examples 27-32 
Drum Pelletizing 
Experiments were conducted to show that significant strength enhancement 
can be attained by pelletizing carbon black in the presence of a molten 
compound in a dry drum. For convenience, lauryl alcohol was chosen as the 
molten fluid because it has the low melting point of 25.degree. C. and, 
hence, was easily maintained in the molten state during the drum 
pelletizing operation. It was then transformed to the solid state by 
cooling the pellets in a refrigerator prior to product characterization. 
The black employed had a FDBP of 74 cc/100 g and a surface area of 210 
m.sup.2 /g. 
For a black with a FDBP of 74 cc/100 g and for a fluid with a density of 
0.82 g/cc (that of lauryl alcohol), calculations, using Equation (2) with 
DBP replaced by FDBP and Equation (3), show that the pendular state is 
attained when the pellets contain about 25 weight % lauryl alcohol. Dry 
drum studies were conducted by addition of lauryl alcohol treated fluffy 
black (300 g black plus varying amounts of alcohol) to 200 g seed pellets 
(for further details see experimental). The fluffy black contained 0, 9.1, 
16.7, 23.1 and 28.6 weight % alcohol. Since dried wet process pellets, 
containing no lauryl alcohol, were initially used as the seed material, 
the lauryl alcohol content of the pellets after three cycles through the 
drum were calculated to contain 0, 8.6, 15.9, 22.2 and 27.6 weight % 
alcohol, respectively. Thus the highest alcohol level used just exceeded 
that required to attain the pendular state. 
The resulting pellets after three pelletizing cycles were characterized in 
terms of their mean sizes, tap densities, mass pellet and individual 
pellet crush strengths. In addition, the product of the tap density and 
the fraction carbon in the pellets for each sample, termed the carbon 
density in the pellets, was computed. Finally, comparable properties for 
the pin pelletized pellets used as the initial seed material (Example 32) 
were also determined The results obtained are listed in Table 3. 
TABLE 3 
______________________________________ 
Carbon Black Dry Drum Pelletized With 
Varying Levels Of Lauryl Alcohol 
Mean Tap .sup.a Carbon 
Example 
Weight % Weight % size MPS Density 
Density 
Number Alcohol Black mm lbs g/cc g/cc 
______________________________________ 
27 0.0 100 0.34 5 0.35 0.35 
28 8.6 91.4 0.56 6 0.38 0.35 
29 15.9 84.1 0.72 9 0.43 0.36 
30 22.2 77.8 0.67 16 0.50 0.39 
31 27.6 72.4 0.69 18 0.54 0.39 
.sup. 32.sup.b 
0.0 100 0.58 11 0.47 0.47 
______________________________________ 
.sup.a Density of carbon in pellets 
.sup.b Seed pellets formed by wet pelletizing in a pin pelletizer 
The results in the table indicate that at low lauryl alcohol content, below 
about 8.6 weight %, the drum pelletized products have low pellet 
strengths. As the lauryl alcohol content of the pellets increases above 
about 10 weight % there is a progressive increase in strength. As the 
pendular state (25.3 weight % lauryl alcohol) is approached and exceeded, 
the strengths of the drum pelletized products exceed that of the wet 
pelletized product (Example 32) even though the densities of the blacks in 
the pellets, on an alcohol free basis, are smaller than that formed by pin 
pelletizing. These results demonstrate that molten material can be used to 
strengthen pellets even when less compound than that required to attain 
the pendular state is employed. 
Dispersibility Studies 
The products of Examples 27 to 32 were incorporated into a standard news 
ink formulation. In all cases the formulation compositions were adjusted 
so that they contained identical amounts of lauryl alcohol. The products 
were incorporated into the news ink by vigorous agitation for 30 minutes 
by means of a dispersator and then the amount of undispersed material out 
of 5 g of pellets, classified as material greater than 325 mesh (greater 
than 44 microns) in size, was found. The percentage of the product 
dispersed, classified as material less than 325 mesh in size, was then 
found. The results obtained are presented in Table 4. They show that the 
dense, pin pelletized product (Example 32) contains the largest amount of 
residue and, hence, is the least dispersible product. The drum pelletized 
products exhibits comparable amounts of residues. Since the residue levels 
in the drum pelletized products are comparable and since their strengths 
increase with lauryl alcohol content, the present findings demonstrate 
that a more favorable tradeoff between enhancement in pellet strength and 
degradation in dispersibility can be attained by use of molten fluids to 
enhance pellet strengths. 
TABLE 4 
______________________________________ 
Dispersibilities Of Drum Pelletized Products 
Example Weight % Lauryl 
Residue Weight 
Amount Dispersed 
Number Alcohol g % 
______________________________________ 
27 0.0 2.89 42 
28 8.6 2.70 46 
29 15.9 2.53 49 
30 22.2 2.75 45 
31 27.6 3.01 40 
32 0.0 4.88 2.4 
______________________________________ 
Comparative Examples 33-35 
Effects of Black Loading in Conventional Masterbatches 
Comparative experiments were conducted to determine the effects of black 
loading in conventional masterbatches on letdown performance. In these 
examples, a black with a FDBP of 114 cc/100 g black and a surface area of 
140 m.sup.2 /g was pelletized with water in a pin pelletizer, dried and 
then formed into masterbatches (in ABS) at black loadings of 20, 30 and 
40%. The masterbatch viscosities were evaluated. The apparent viscosity of 
the unfilled polymer was 269 Pa.s. The products were then letdown to a 1% 
black loading and the jetness, impact strength and dispersion rating of 
the resultant letdowns evaluated. The results obtained are summarized in 
Table 5 and show that masterbatch viscosity increases with carbon black 
loading. As masterbatch viscosity increases, letdown performance, 
especially at the 40% loading in terms of jetness, dispersion rating and 
impact strength, is degraded. 
TABLE 5 
______________________________________ 
Effect of Black Loading on Letdown Performance 
Example 33 
Example 34 Example 35 
______________________________________ 
.sup.a Black Loading, % 
20 30 40 
Viscosity, Pa .multidot. s 
523 821 1790 
.sup.b L* 7.6 8.8 14.9 
Izod Impact, J/m 
260 260 200 
Dispersion Rating 
1C 1B 4D 
______________________________________ 
.sup.a Masterbatch results 
.sup.b Letdown results. 
Examples 36-37 
Dispersibility Studies 
To show that the products of the present invention are dispersible, the 
dispersion quality attained with some of them was compared against the 
dispersion quality attained with a conventional masterbatch. For these 
purposes, controls were formed from wet process batch pin pelletized 
products using the same grade of black as that used in Examples 1 to 6 and 
in Examples 33 to 35. The control pellets were formed by pelletizing 400 g 
of black in the batch pin pelletizer. The following weights of fluid were 
used to form pellets: 
Example 36: 350 g water +40 g of isopropanol (added to aid wetting of the 
black). 
Example 37: 400 g water +40 g isopropanol 
The pellets of Example 36 and 37, containing 49.4 and 52.4 weight % 
water/isopropanol mixture, respectively, were dried at 150.degree. C. Each 
dried product was formed into a masterbatch containing a 20 weight % black 
loading. The resulting samples were extruded, sliced into pellets and 
labelled Examples 36a (derived from the pellets of Example 36) and 37a 
(from Example 37). These masterbatch pellets, as well as the pellets of 
Examples 1 to 6, formed with PE wax or PE wax and polyisobutylene 
succinimide or paraffin wax with the same fluffy black, were letdown in 
ABS to attain a 1% black loading. The jetness values, impact strengths and 
dispersion ratings attained are presented in Table 6. 
TABLE 6 
______________________________________ 
Comparison of Performance Properties of Letdowns Formed From 
Conventional And Pin Pelletized Concentrates. 
Example .sup.a Black Impact Strength, 
Dispersion 
No. Loading, % L* J/m Rating 
______________________________________ 
36a 20 7.5 280 2C 
37a 20 7.7 280 1B 
1 61.5 8.5 190 2D 
2 55.2 8.1 250 1A 
3 59.7 8.7 200 2C 
4 55.2 8.0 220 1A 
5 57.1 8.8 120 5D 
6 51.6 8.9 150 5C 
______________________________________ 
.sup.a Black loading (by weight) in ABS masterbatch (Examples 36a or 37a) 
or in pelletized products. 
The data in Table 6 demonstrate that the best letdown performances, in 
terms of jetness values (smallest L values) and impact strengths, were 
obtained with the conventionally formed but relatively dilute 20% black 
loaded masterbatches (Examples 36a and 37a). The results obtained are 
essentially identical with those presented in Table 5 at the same 
masterbatch loading. Accordingly, it is expected that the letdown 
performance which would be found for the more highly loaded (and more 
practical) masterbatches would follow the trends shown in Table 5. 
The performance of the letdowns with pure PE wax, especially for the more 
lightly loaded product, Example 2, approached those found with the 
conventional 20% loaded masterbatches and probably would exceed that found 
at a 30% loading (see Table 5). Further, the apparent viscosities of 
samples of Examples 1 and 2 are in excess of 2100 and 860 Pa.s, 
respectively. These results demonstrate that pellets having relatively 
large apparent viscosities (compared to conventional masterbatches--see 
Table 5) can be used for letdown applications. Thus, these results show 
that products formed on the "dry" side of the capillary state can function 
as concentrates with acceptable letdown performance properties. 
The letdown performances achieved with the combination of isobutylene 
succinimide and PE wax in the pellets, Examples 3 and 4, are quite similar 
to those found with the pure PE wax at comparable black loadings. In spite 
of the relatively large amounts of paraffin wax employed in pellet 
formation, the letdown performances of the products of Examples 5 and 6 
are inferior to those found for the other Examples. 
Example 38 
Plant produced pellets formed from a carbon black with a FDBP value of 70 
cc/100 g and a surface area of 230 m.sup.2 /g were obtained. The pellets 
were produced by continuous pin pelletization using water as the cohesive 
fluid and then dried in the plant to give a pelletized product with DBP of 
64 cc/100 g (Example 38). This product was dispersed in ABS to form a 
masterbatch containing 20 weight % black (Example 38a). 
The letdown performance of the product of Example 38a is compared against 
those of the products of Examples 7, 8 and 9 in Table 7. All products were 
formed using a comparable fluffy black as feed. 
TABLE 7 
______________________________________ 
Comparison of Letdown Performance Of A Conventional Masterbatch 
With Pelletized Products Formed With Molten Fluids 
Example Number 38a 7 8 9 
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.sup.a Black Loading, % 
20 69 64.9 64.9 
Impact Strength, J/m 
170 150 180 170 
Dispersion Rating 
3E 4B 3B 4B 
L* 5.1 6.8 5.4 6.4 
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.sup.a Loading by weight in either the masterbatch or in the pellets 
The jetness, impact strength and dispersion rating for the letdowns derived 
from the pellets of this invention approach that obtained using a lightly 
loaded, conventional masterbatch. The results in the table also suggest 
that pellet performance is enhanced as the level of PE wax used in the 
pelletizing operation is increased. 
The amounts of molten organic compound employed in the pelletizing 
operation for the blacks used in Tables 6 and 7 were less than 50 weight % 
and were within the ranges given by W.sub.liq,max and W.sub.liq,min. 
Moreover, as indicated previously and in agreement with the present 
findings, the amount of material needed for pelletization decreases with 
decreasing black structure. 
Examples 39-40 
The effects of pelletizing with water soluble molten fluids which are 
surface active agents was assessed. In these studies the dispersibilities 
of the products of Examples 10 to 14 were compared against those of the 
fluffy precursor used to make the pellets, Example 39, and the product pin 
pelletized with water, Example 40. In the latter case the wet pellets, 
containing 50 weight % moisture, were dried at 150.degree. C. 
As described above, the molten fluids employed consisted of polyethylene 
glycol and various surfactants based on copolymers of ethylene oxide and 
propylene oxide. The black employed had a fluffy DBP of about 100 and a 
surface area of about 220 m.sup.2 /g. The surfactants all melted below 
50.degree. C. and were used, mostly, as blends with the higher melting PEG 
1000 product. All blends contained 60 parts surfactant and 40 parts of PEG 
1000. The molten products formed a single phase. 
To assess dispersibility, the products of Examples 10 to 14 as well as the 
fluffy black, Example 39, and the conventionally pin pelletized black, 
Example 40, were dispersed in an aqueous medium containing surfactant and 
ethanol. Experience has shown that dispersed black is stable in this 
medium. In all cases 0.08 g of black was added to 200 ml of the aqueous 
medium. Each suspension was subjected to the same dispersing conditions by 
first stirring with a magnetic stirrer and then sonifying for 1, 5 and 15 
minutes. At each stage of dispersion, the states of dispersion in the 
suspension were assessed by evaluating their optical densities, O. D., 
after further dilution with the suspending medium. The optical densities 
of the suspensions, normalized to a constant dilution level of 0.25 parts 
suspension and 8 parts suspending medium are summarized in Table 8. 
TABLE 8 
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Optical Densities of Suspensions 
Example O.D O.D. O.D. O.D. 
No. Stirred 1' Sonified 
5' Sonified 
15' Sonified 
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10 0.032 0.231 0.428 0.596 
11 0.043 0.530 0.690 0.610 
12 0.039 0.540 0.596 0.602 
13 0.047 0.345 0.594 0.580 
14 0.100 0.600 0.610 0.602 
.sup. 39.sup.a 
0.044 0.480 0.600 0.580 
.sup. 40.sup.b 
0.022 0.135 0.350 0.592 
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.sup.a) Fluffy black 
.sup.b Pin pelletized with water 
The results in Table 8 demonstrate that after 15 minutes of sonification 
the optical densities of the suspensions have leveled out and, within the 
precision of the data, exhibit comparable values. This means that the 
samples are fully dispersed. After 5 minutes of sonification, the fluffy 
product, Example 39, as well as the surfactant containing samples, 
Examples 11, 12, 13 and 14, have similar optical densities which are 
comparable with those of the 15 minute sonified suspensions. Accordingly, 
these products are fully dispersed after 5 minutes of sonification. On the 
other hand, the water pelletized sample, Example 40, has the lowest 
optical density and, hence, is the least well dispersed product. The 
dispersibility of the sample pelletized with PEG, Example 10, is 
intermediate between the water pelletized and surfactant containing 
pellets. The optical densities at shorter dispersion times are consistent 
with the view that the dispersibility of the TERGITOL XD surfactant 
containing pellets, Example 14, is considerably better than that of the 
fluffy black, Example 39. Further, the products of Examples 11, 12 and 13 
are comparable with that of the fluffy product. These results indicate 
that with the proper selection of the pelletizing fluid, strong pellets 
with good handling properties and with dispersibility equal to or better 
than that of the fluffy product can be obtained.