TEPZZ_99_4Z B_T

(19)

(11) EP 1 991 402 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.:

of the grant of the patent: B29B 9/06 (2006.01) B29C 47/00 (2006.01)
28.12.2016 Bulletin 2016/52 C10G 73/40 (2006.01) B29B 9/12 (2006.01)
B29C 47/10 (2006.01) B29C 47/78 (2006.01)
(21) Application number: 07752630.9 B29C 47/84 (2006.01) B29K 91/00 (2006.01)

(22) Date of filing: 08.03.2007 (86) International application number:

PCT/US2007/005945

(87) International publication number:

WO 2007/103509 (13.09.2007 Gazette 2007/37)

(54) METHOD AND APPARATUS FOR PELLETIZING WAX AND WAX-LIKE MATERIALS
VERFAHREN UND VORRICHTUNG ZUR PELLETIERUNG VON WACHS- UND WACHSÄHNLICHEN
MATERIALIEN
PROCÉDÉ ET DISPOSITIF DE PASTILLAGE DE LA CIRE ET DE MATÉRIAUX ANALOGUES À LA
CIRE

(84) Designated Contracting States: • MARTIN, J. Wayne

AT BE BG CH CY CZ DE DK EE ES FI FR GB GR Buchanan, VA 24066 (US)
HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE
SI SK TR (74) Representative: Thoma, Michael et al
Lorenz Seidler Gossel
(30) Priority: 09.03.2006 US 780348 P Rechtsanwälte Patentanwälte
Partnerschaft mbB
(43) Date of publication of application: Widenmayerstraße 23
19.11.2008 Bulletin 2008/47 80538 München (DE)

(73) Proprietor: Gala Industries, Inc. (56) References cited:

Eagle Rock, VA 24085 (US) WO-A1-2007/123931 WO-A2-2007/064580
DE-A1- 3 247 406 US-A- 2 216 188
(72) Inventors: US-A- 3 288 892 US-A- 5 942 170
• THEPSIMUANG, Boonlert US-A1- 2003 000 100 US-A1- 2004 009 254
Daleville, VA 24083 (US) US-A1- 2005 056 961
EP 1 991 402 B1

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent
Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the
Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been
paid. (Art. 99(1) European Patent Convention).

Printed by Jouve, 75001 PARIS (FR)

 1 EP 1 991 402 B1 2

Description cations where the ambient temperatures are quite

high.
FIELD OF INVENTION C) Slats & Chips : This form is a result of pumping
and/or extruding the molten wax as continuous
[0001] The present invention relates generally to an 5 strand(s) onto a belt, usually a steel belt, on which
apparatus and method for the pelletization of waxes and the heat energy is absorbed by the belt from the wax
wax-like materials. More specifically, the present inven- until the wax has solidified. At the end of the belt the
tion relates to an apparatus and method for pelletizing wax strand or strip (as the strand tends to flatten out)
waxes and wax-like materials by extruding the wax or is feed into a cutter, thus shearing the strips into slats
like material through orifices in a die plate and cutting the 10 or chips. The disadvantage here again is inefficiency.
extruded strands with a rotating cutter similar to an un- As the strand falls upon the belt, the contact surface
derwater pelletizer but without water, in the nature of "hot promptly cools/solidifies. But this forms a boundary
face" or "dry face" pelletizing, and with the wax or like layer that tends to insulate the remainder of the wax
material in a solid state. above it. Thus the cooling process slows down as
15 the wax stays on the belt without any agitation or
BACKGROUND OF THE INVENTION cooling surface removal/ renewal. As a result the
steel belts which must be of a polished finish (like a
[0002] There are a number of common methods in wax mirror) can get very long and wide to have any ap-
manufacturing to get the wax into a condition or shape preciable rate of production. These precision pol-
to package, transport and utilize and/or feed in subse- 20 ished belts can be very expensive and are quite sus-
quent processes, most of which likely take place at other ceptible to damage, and require tremendous cooling
locations. The common forms are as follows. support units. The belts can take up much floor space
and in the event of rate increase (or viscosity in-
A) Bricks and Cakes: This form is probably the oldest crease), need greater and greater lengths requiring
process, and most elementary. Basically, the molten 25 aisles to be changed in plant layout or worse. In re-
wax is poured into a mold of a desired shape such gard to wax grades with higher and higher viscosi-
as circular, rectangular, etc. and let cool. The disad- ties, they tend to require the existing belt lines to
vantages to this method of manufacture include risk significantly slow down, so as to increase exposure
of spillage and splash on operators, long periods of to cooling time, thus resulting in considerable loss in
storage and much space to cool, risk of contamina- 30 production output. In addition, during humid seasons
tion during pouring and generally such technique is or in places where humidity is high, the very cold
very labor intensive. Later when using these bricks steel belts can suffer condensation build up, thus
or cakes, the total mass is great and thus takes melt making the waxes wet (and there is usually no drying
pots and time to re-melt the wax. Adding more bricks capability). To compensate, an expensive cover
to an existing container partly full of liquid wax also 35 could be installed over and around the belt process.
increases risk of splash to operators. Dosing and But this too, must be climate controlled. And without
conveying methods are not very sophisticated. such a cover, the product is exposed to dust, insects
B) Prills: Prilling involves very tall towers (and thus and other contaminates, to be imbedded in the still
buildings) with long insulated pipe runs, which basi- molten waxes. There is also increased exposure to
cally utilize certain atomizing spray nozzles. The 40 oxidation at the elevated temperature with or without
sprayed wax generally free falls in a cross-current the cover.
of cooled gas a distance necessary to cool the wax D) Pastilles: This process also utilizes a steel belt
droplets to a solid state. Depending on the wax and principle. As such, many of the disadvantages are
how things are adjusted, this method can yield fine the same as described above for the "slats & chips"
particles like powder-to-small beads-to-pellets close 45 method. One significant difference is the final wax
to 2 to 3 mm in size. This process tends to work well product shape which is more like a pellet or lens
with optimal flexibility when the waxes are of the low- shape, and the final product tends to be very uniform.
est viscosity types. However, as the viscosities in- Conversely, this process, which uses the principle
crease there is a challenge to get the spray concept of dropping "droplets" of wax onto the belt, is even
to work, as the wax would prefer to pour as a solid 50 more limited when approaching higher viscosity
stream or string. Further, since these towers are grades where the wax product would rather pour on-
quite tall, considerable space (in height and volume) to the belt instead of dripping onto the belt. Thus,
and construction work are required. Furthermore, this process tends to be limited to the low end vis-
gas cooling is not the most efficient way to process cosity range. Further "pastille" sizes can be very lim-
polymers. Thus, considerable energy is required to 55 ited; meaning it gets less efficient and practical for
do the cooling and gas circulation functions, plus the belt process to make "micro-pellet" sizes.
there is the large amount of construction insulation E) Pellets & Powder: Some prilling applications can
required for such large facilities and especially in lo- produce "near powder" sizes or make near pellet siz-

2
 3 EP 1 991 402 B1 4

es (like 2 to 3mm) which can then be ground into to freeze and block until some sort of equilibrium velocity
powder. Some waxes are of a high enough viscosity, and back pressure are achieved, so to generally keep
also having enough melt strength and a wide enough any remaining unblocked holes open. This situation is
liquid to solid state temperature range to be suitably very unpredictable for the pelletizing process, and yields
pelletized, such as by means of an underwater pel- 5 non-uniform size pellets. Thus the process is very unsta-
letizing process. For such wax grades, they can be ble to continue.
sold either in pellet form (such approximately 3mm [0006] Furthermore, increasing back pressure causes
in diameter) or can be ground into a fine powder form. slipping within the upstream pumping equipment, which
can occur easily because of the very low viscosities of
[0003] However, efforts to pelletize waxes using un- 10 the wax in the molten/liquid state. The loss of rate from
derwater pelletizer and centrifugal dryer equipment has the pump to the die further complicates the issue of reach-
attained mixed results and, in many cases, the underwa- ing an equilibrium state, and thus further adds instability
ter pelletizing methodology has produced unsuccessful to the process. Additionally, the pumping equipment
results. Most waxes have very low liquid-to-solid temper- while working to create pressure and flow of the wax,
ature points, relative to the many resins, polymers, plas- 15 while suffering slip, will add more energy into the wax,
tics, and elastomer type materials and their compounds thus driving the already low viscosity, even lower, making
that can be pelletized with underwater pelletizing tech- it even more difficult to establish a stable running system
nology. What is the basic problem for underwater pel- with predictable pelletizing results.
letizing of waxes is the fact that many of these waxes go [0007] Yet another problem associated with pelletizing
from an extremely low viscosity (much lower than nor- 20 waxes is that a common property of most waxes, unlike
mally observed in the other above mentioned polymers) many of the polymers/plastics on which underwater pel-
to become a solid within a very narrow range of temper- letizers work well, is they have a very low "melt strength".
ature, typically from about 5°C to about 20°C. In contrast, For the purposes of this application, the term "melt
the band or range of temperatures for many of the other strength" is intended to define the ability of the material
polymers on which underwater pelletizing is applicable 25 to stay together upon the impact of the cutting blades at
are much wider from being in a more liquid state to a high speed, to shear the polymer or wax strand as it exits
more solid state. For the purposes of this application, the die orifice. In other words, as the strand is cooling
materials having a narrow temperature range for liq- from the influence of the process water the pellet is gain-
uid/solid state change are referred to as having a "sharp ing in strength to hold itself together to be formed into a
melt point". 30 pellet.
[0004] Materials that exhibit this sharp melt point in [0008] In the case of many waxes, the melt strength is
combination with a very low melt to solid transition tem- nearly non-existent, and as the liquid or semi-liquid wax
perature include most waxes. These properties can strand exits the die orifice, the impact of the cutter blade
cause serious problems when attempting to pelletize trying to shear the strand into a pellet actually causes an
waxes using underwater pelletizing equipment. The lead- 35 impact explosion or shattering of the pellet into many
ing problem is that as the wax passes through the die fragments. This effect produces a wax solid geometry
plate (a metal plate with a relatively concentric circle or more like shredded coconut or like fines and/or a com-
circles of extrusion orifices), the wax will have a tendency bination of the two.
to freeze-off within the extrusion orifices. This is caused [0009] Even if shredded coconut or fines-type particles
by the fact that underwater pelletizing utilizes a water 40 might be acceptable, there remain the problem of how
flow across the die plate face to act as a quenching me- to get such wax particles separated from the water and
dium for the extruded strands exiting from the die orifices, dry. Standard centrifugal dryers that typically support the
and as a conveying means once the strands are cut into underwater pelletizer cannot be used effectively. For ex-
pellets at the orifice exit point by the rotating blades of ample, with many grades of wax where suitable/normal
the pelletizer cutter. 45 pellet geometry could be achieved with an underwater
[0005] This freeze-off or freezing occurs because the pelletizer, such as a 3mm diameter cylinder, lens or
water flowing across the die face is of a normally much sphere, these wax pellets could be brittle entering the
lower temperature than the liquid or melt temperature of centrifugal dryer at the colder process water tempera-
the wax extrudate. Thus, as the wax strand passes tures, thus breaking the pellets causing waste in fines or
through the die extrusion orifice, the strand loses much 50 dust. Conversely, if the water temperature is warmed to
of its remaining internal heat energy into the surrounding reduce breakage, the higher temperature causes the pel-
die extrusion orifice wall as it approaches the exit. And lets to be softened and more likely to scrape off particles
because of its sharp melt point, the wax transitions very from the wax pellet surfaces as they pass through the
quickly into a solid state before exiting the orifice thus dryer, thus still producing fines and dust.
creating a blockage in that orifice. As a result the back 55 [0010] Another problematic issue associated with us-
pressure forcing the wax into and through the die orifices ing a centrifugal type dryer can be the pellet deformation
increases and velocity through any remaining open flow- effects inside of the dryer. This could be an issue when-
ing orifices also increases. Other orifices can continue ever the deformation temperature of the material is below

3
 5 EP 1 991 402 B1 6

the actual temperature of the material at the time it passes die plates quite easily as a solid wax material, rather than
into and through the centrifugal dryer. The most common as a conventional liquid or molten material. In fact, the
problem observed is the material getting embedded onto solid wax material as extruded through the die orifices
or into the dryer rotor screens which leads to the screens formed good strands that did not fuse easily back togeth-
getting plugged over time with the materials. This em- 5 er, at least not under their own weight.
bedding and/or plugging reduces or eventually elimi- [0018] In view of the foregoing, the equipment up-
nates the ability of the dryer to get the material dry enough stream of the die plate is therefore modified to take the
for subsequent packaging, storing or processing. hot liquid wax from a reactor or mixing vessel, or whatever
[0011] Document DE 32 47 406 A1 describes a method is used to produce or melt and/or blend the wax, and then
for manufacturing paraffin pellets, wherein liquid paraffin 10 to cool the wax down to a solid state as efficiently as
is cooled down in a scrape chiller to plastify, wherein the possible. Then with the wax in a solid but very malleable
plastified paraffin is further conveyed through a duct to condition, it can be pressurized to go through the die
a die plate where the plastified material is pressed plate in that same solid state. In accordance with the
through the die plate orifices to form into strands which present invention, the malleable condition of the solid
are then cut into pellets. 15 state wax permits a high plastic deformation of the mal-
[0012] WO 2007/064580 A2 (prior art under Art. 54 (3) leable material in compression without fracture. On the
EPC) relates to a pelletization of polymeric materials hav- pelletizer side of the die plate, with the wax already in a
ing narrow melting ranges, wherein an underwater pel- solid state, the quenching effect of the water is no longer
letizer is used. needed. Thus, the underwater pelletizer is converted to
[0013] US 3,288,892 teaches that material is molten 20 a "dry face" pelletizer. The cutter blades on the rotating
as it passes through a die, wherein with the molten ma- cutter hub shear the now solid strands as they exit from
terial, droplets are formed that fall onto a conveyor belt the die plate extrusion holes, but there is no need for
where they are cooled and scraped off. simultaneous cooling/quenching with water. Further-
[0014] US 2004/009254 is directed to an underwater more, in the solid state, the wax has sufficient melt
pelletizer where the cut material is transported away by 25 strength not to shatter apart as the cutter blades impact
cooling water flowing through the cutting chamber. it. Typical underwater pelletizer equipment useful in the
[0015] Furthermore, US 2,216,188 is directed to con- present invention is illustrated in U.S. Patents Nos.
verting wax into slabs, wherein a heating chamber is 5,059,103 and 7,033,152, also owned by the assignee
adapted to contain wax in a molten condition, a discharge of this application.
pipe extends from the bottom of said chamber to a pump 30 [0019] Since the water process is no longer used, the
and a pipe leads from said pump to one end of an elon- pellets simply fall downward by gravity, through a bottom
gated cooling chamber, wherein the plastic wax is dis- opening in the cutting chamber, after being cut by the
charged at the opposite end of said elongated chamber rotary cutter. When falling out of the cutting chamber, the
to form slabs. wax pellets preferably fall onto a conveyor, such as a belt
35 or pneumatic type, to transport the pellets away from the
SUMMARY OF THE INVENTION pelletizing equipment, to a pellet screener, cooler and/or
packaging unit.
[0016] To solve the aforementioned problems under- [0020] Again, since no water for quenching is required,
lying the present invention, the present invention pro- then the water circulation/filtration and water temperature
vides for a method and an apparatus for forming pellets 40 control system are no longer required. Also the dewater-
from a wax or wax-like material as defined in claims 1 ing and drying equipment is not required, thus a signifi-
and 10. Preferred embodiments of the invention are laid cant number of advantages can be realized. For exam-
down in the dependent claims. ple, these advantages include:
[0017] During experimental work, another property or
characteristic of waxes was observed. Specifically, upon 45 • Less capital equipment cost for the pelletizing sys-
transitioning from a distinct liquid to a distinct solid, the tem;
solid wax was still very malleable. Although it would not • Reduced energy consumption by the pelletizing sys-
flow in the sense of a liquid nor would it easily stick back tem;
together, it could easily be "cold-worked" into another • Less floor space required for the pelletizing system;
shape and would normally retain that shape. As used 50 • Since water is no longer involved, issues about the
herein, the term "cold-worked" means any form of me- consumption of and environmental concerns from
chanical deformation processing carried out on a plastic the draining of the process water are no longer a
or polymer material below its melt temperature. It was consideration;
also apparent that the malleability or cold-workability in- • Again, since no water is involved, issues about de-
creased as the solid temperature was higher and con- 55 watering and achieving a desired pellet surface
versely the malleability reduced as the solid temperature moisture level are no longer a concern; and
was reduced. Furthermore, it was found that waxes could • Plant installation of the pelletizing system is less
be extruded through conventional underwater pelletizer complex.

4
 7 EP 1 991 402 B1 8

[0021] On the pelletizer and die plate equipment itself, is in a very liquid state. A low viscosity pump 3 creates
more advantages are realized, such as: enough pressure and flow to get the wax through any
necessary filtration element 4, first stage cooler 5 and on
• The number and/or size of the die holes can be in- into the beginning of the second stage cooler 8, or divert-
creased and the "rate per hole" decreased so that 5 ed off to another wax handling process or to be returned
back pressures can be better controlled or further back to the vessel or upstream equipment by diverter
reduced. In an underwater process it is normally im- valve 7.
portant to maintain a high rate or velocity per hole in [0025] The first cooling stage is basically a heat ex-
order to minimize the risk of die freeze-off. This is no changer of which there are many types that would qualify,
longer a concern in the process in accordance with 10 including plate and frame type, coil type, scrape wall type,
the present invention. U-style tube type with or without static mixers, and shell
• A smaller pelletization motor can be used and/or less and tube type with or without static mixers. The shell and
energy will be consumed by the pelletizer motor. A tube type with static mixers is preferred for the most ef-
significant portion of the amp load of an underwater ficient cooling effects. The heat exchanger can be sup-
pelletizer motor is required to just rotate the cutter 15 ported by a properly designed and dedicated hot oil or
blades in the water. Conversely the act of just spin- hot water system. Keeping in mind that the wax is enter-
ning the cutter blades in the air requires a minimum ing into the heat exchanger at or near the highest tem-
amount of energy. perature, and thus a most liquid state, if properly de-
• Nice normal size wax pellets with 2-3mm diameter signed the heat exchanger removes most the internal
can be easily produced. Even micro-pellets, such as 20 heat energy down to a known temperature point just
about 1mm in diameter, can be produced more reli- above where the wax will change state from liquid to solid.
ably and predictably. Preferably, the heat exchanger in the first stage cooler
should reduce the temperature of the wax down to ap-
BRIEF DESCRIPTION OF DRAWINGS proximately 5° C or less above the wax liquid to solid
25 transition temperature so that the wax remains liquid
[0022] enough to have good unobstructed flow into and through
the next downstream equipment. It is intended that the
Figure 1 is a schematic illustration of one embodi- heat exchanger of the first stage cooler be the most ef-
ment of equipment for carrying out the wax pelletiz- ficient cooler so that the second stage cooler has a lesser
ing process of the present invention. 30 amount of cooling work to do.
[0026] An optional flow meter 6 preferably follows the
Figure 2 is a pictorial illustration of equipment used first stage cooler so that flow rate adjustments can be
for carrying out the wax pelletizing process of the made at the pump 3 upstream to change or optimize con-
present invention. ditions downstream, such as at the pelletizer 10 or within
35 the second stage cooler 8. Diverter valve 7 can have one
Figure 3 is a pictorial illustration of equipment used or more outlets. Its primary outlet is to the inlet chamber
for conducting tests of the apparatus and method of of the second stage cooler 8. One or more other outlets
the present invention. can be to a drain container and/or serve as a dispenser
connection into another process and/or into a recircula-
Figures 4A-4H are photographs illustrating product 40 tion loop line back to the upstream process origins. The
produced during tests of the apparatus and method diverter valve 7 is synchronized with the downstream
of the present invention using the equipment illus- process equipment so that it can send liquid wax into it,
trated in Figure 3. when ready to start-up and run or stop flow when ready
to shut down, and/or serve as an emergency diverter in
DETAILED DESCRIPTION OF PREFERRED EMBOD- 45 the event flow must abruptly stop to the downstream
IMENTS equipment/process.
[0027] The second stage cooler 8 is best defined in
[0023] Turning to Figure 1, there is schematically illus- five parts. The first, inlet chamber 8a should be heat jack-
trated the equipment components for carrying out the eted to precisely control the liquid wax temperature so
wax pelletizing process of the present invention. Each of 50 as to prevent the wax from solidifying at this juncture, yet
the components of the equipment as used in accordance not to add any heat energy so as to have to remove it
with the present invention is discussed hereinafter where later. The inlet chamber allows for visual inspection by
like numerals refer to like components in Figure 1. operators, yet keeps any unwanted dust, impurities, and
[0024] The upstream equipment, such as a reactor, ambient air that could cause degradation or contamina-
mixing vessel or some kind of melting/blending type ma- 55 tion problems. It is also to contain level control with alarm
chinery for forming hot melted wax is designated by nu- functions to alert operators of any potential issues and/or
meral 1. At the discharge end 2 of reactor 1, the wax is automatically activate the upstream diverter valve 7,
at its highest melt temperature and lowest viscosity, and and/or shut down the pump 3, until service or other ad-

5
 9 EP 1 991 402 B1 10

justments can be done. [0032] Further to the second stage cooler 8, it should
[0028] Next is the cooling section 8b. As wax goes into be designed in overall length as well as in diameter to be
and through this section it is exposed to cooling temper- sufficient enough to do the cooling of the target wax or
atures well below its liquid to solid transition temperature waxes to be processed and at the rate sufficient to meet
and thus well into the solid phase temperatures. The 5 the product goals of the overall-process. The equipment
equipment cooling should be adjustable so that many currently considered suitable for the second stage cooler
various grades of wax can be run. The size and layout 8 is an extruder such as a single screw type. An extruder
of the elements within the cooling section may vary for with two or more screws is preferred, and most preferred
each wax application so that there is optimum exposure is a twin or two screw extruder that is co-rotating and
to the cooling surfaces, the cooled layers are moved 10 intermeshing.
away and interspersed with the warmer layers of wax [0033] Polymer diverter valve 9 is a common compo-
into a relatively homogenous mixture then returned to nent used ahead of an underwater pelletizer. It is useful,
the cooling surface for more heat energy reduction. This although not necessary, in the present invention to assist
process is repeated over and over again down the length the extruder to get started, with a minimum of head pres-
of the cooling equipment, all the while wiping itself clean 15 sure, and once running to allow the operator to inspect
of the "older" cooled wax to make room for incoming the wax solid and temperature condition before the wax
hot/warm "new" wax. These functions are achieved while goes on to the pelletizer. Then once the inspection deems
putting an absolute minimum of work energy into the ma- the upstream process as stable, predictable and the wax
terial so as to not heat the wax back up. appears of the optimum temperature and malleability,
[0029] As the machine focus shifts from cooling and 20 the polymer diverter valve (PDV) is then changed to send
the wax is now well into its solid state, yet very "mallea- the wax flow into the die plate and pelletizer functions. If
ble", the equipment in section 8c must now focus having there are ever any problems or issues at the pelletizer,
the optimum design to push/pressurize or pump the solid the die or even in the process equipment after the die,
wax into and through the downstream equipment, includ- then the PDV is normally the first component activated
ing a pelletizer die as a minimum. At the same time, care 25 to divert the wax flow. The operator can then make any
should be taken to keep any energy input from being quick necessary adjustments without shutting down the
converted into heat that could re-melt the wax. In addition upstream parts of the process. Or, the operator may elect
a self-cleaning feature is preferable during this part of to shut down most or all of the upstream process parts
the process, as well. until after any necessary adjustments, repair services,
[0030] It may be desirable during this second stage 30 etc. can be made.
cooling, which undergoes intensive mixing and re-mixing [0034] The pelletizer and die 10 have been explained
so as to keep the various layers of wax at various tem- herein before. The wax is now being extruded in a solid
peratures being interspersed into an eventual homoge- state; the dry face pelletizer with no water is employed.
nous solid, yet malleable product, to add or "compound However, those skilled in the art will recognize that not
in" certain desired additives as at 8d. The additives can 35 all waxes are problems for underwater pelletizing. Fur-
vary greatly, including various minerals, antioxidants, thermore, the types and amounts of additives can be of
colorants, etc, other grades of waxes, master batches or such a significant degree/level that the wax compound
concentrates in various forms, such as powders or even may attain such a higher viscosity, which might be better
liquids, either preheated or not. These additives may be pelletized in a semi-solid or semi-liquid or even a liquid
introduced into the process by liquid metering pumps, 40 state, during which an underwater type pelletizer might
screw feeders, etc., and into the inlet chamber or even then be preferred. Accordingly, it is contemplated in ac-
ahead of that, or by injecting under pressure or not, into cordance with the present invention that the pelletizer 10
the side and/or top of the cooler, anywhere along sections can be one that can easily be converted from a dry face
8b and or 8c. Finally, the second stage cooler must be pelletizer to an underwater pelletizer and vice-versa.
supported by a properly sized and reliable cooling system 45 [0035] After pelletizing the wax the pellets typically can
8e. fall onto a belt conveyor 11 to be transported away. There
[0031] In regard to the second stage cooler 8, it should might be cooling fans placed around the belt to aid in
have the ability to heat up as well as cool down the pres- removing any remaining internal heat to get the pellets
surized wax. If the machine needs to be stopped for any closer to ambient temperature before further processing
length of time, and the wax loses most or all of its heat 50 or packaging.. Optional to cooling fans, a refrigerated
energy or all of its necessary malleability to get the wax belt could be used. A further alternative to the belt con-
through the equipment, then the wax has to be re-heated veyor (many other mechanical types can be used), is an
to a liquid state or at least to a malleable condition, so air conveyor either using chilled/cooled air or any gas or
as to get the process moving again. Preferably, this ca- at ambient temperatures might be used as well. Alterna-
pability is built into each equipment component or stage 55 tively a water conveying means could also prove bene-
of the process so as to have the ability to heat up the ficial as well, depending on the circumstances. Water
equipment component at least at the beginning or as nec- conveying would certainly be a faster cooling method if
essary. the wax and/or the wax compound pellets need to be

6
 11 EP 1 991 402 B1 12

taken to much lower final temperatures and/or done so sisting the pellets out of the chamber and on to the con-
quickly. If water is used, however, then as mentioned veyor. The overall equipment and process illustrated in
before there will be a need for dewatering and drying Figure 2 is operated by a control system with remote
process functions immediately thereafter. control station 415.
[0036] After the conveyor 11, the wax pellets can un- 5 [0041] It is to be noted that all of the components
dergo a classification step 12 where certain sizes can be marked with an asterisk in Figure 2 are provided with a
segregated out as acceptable or unacceptable. "Unac- heating capability, either oil heat (one asterisk (*)) or elec-
ceptable" may refer to "unders" which may be pellets too tric heat (two asterisks (**)). This heating capability is
small in diameter or fines, and "overs" which may be pel- provided for the reasons explained in connection with the
lets too large or even clusters or agglomerates, all being 10 equipment and process of Figure 1.
removed to assure wax pellet quality in regard to size [0042] Turning now to Figure 3, there is pictorially il-
qualification, and before being moved on to storage, lustrated, equipment used for conducting tests of the ap-
packaging or subsequent steps or process(es). In addi- paratus and method of the present invention. The tests
tion to classification, there may optionally be cooling by were conducted using a polyethylene wax having the fol-
air or other gas at this stage to assure that suitable final 15 lowing properties:
pellet temperature is achieved.
[0037] Turning now to Figure 2, a pictorial illustration Softening point - 110-120° C
of equipment which might be supplied to a wax processor Density - 0.70-0.80 grams/cm3 @ liquid feeding
in accordance with the present invention is shown. Many temp.
of the equipment components illustrated in Figure 2 are 20 - 0.92-0.95 grams/cm3 @45° C (solid)
similar to those described previously in connection with Viscosity - 5-200 centipoise @ 149° C
Figure 1, and further detailed description will, therefore,
not be repeated. Typically, the wax reactor, mixing vessel [0043] The polyethylene wax was heated in the barrel
or some other kind of melting/blending machinery for heater 22 above 120°C to the density specified above.
forming the hot melted wax is provided by the wax man- 25 Once at the desired liquid state, the liquid wax was fed
ufacturer or processor and, hence, is not illustrated in to the heater tap 24 by the liquid pump 26 and into the
Figure 2. Rather, the equipment illustrated in Figure 2 entrance end of the extruder 28. The extruder 28 was a
starts with an adaptor 20 which connects the reactor, twin screw type. While in the extruder, the temperature
mixing vessel, etc. (not shown) to melt pump 3. of the polyethylene wax was reduced from above 120°C
[0038] The melt pump 3 is connected to the melt cooler 30 at the extruder entrance to about 50°C at the extruder
5 through adaptor 42. The melt cooler 5 corresponds with exit. The cooling was effected by cooling bores in the
the first stage cooler 5 of Figure 1, and is preferably a barrel of the extruder which were supported by the chiller
static mixer-type heat exchanger providing for the highest 30. At 50°C exiting from the extruder, the polyethylene
cooling efficiency. Such heat exchangers are typically wax was in a solid, malleable state. Upon exiting the ex-
supported by hot oil or hot water systems, which are pic- 35 truder, the solid polyethylene wax passed through a pellet
torially illustrated but not numbered separately in Figure diverter valve (PDV) 32 and then into a dry face pelletizer
2. 34 where solid wax strands exiting the die plate orifices
[0039] Following the melt cooler 5 is an adaptor 44 to were cut by the rotary cutter. The cut pellets were con-
connect the melt cooler 5 to the flow meter 6. Thereafter veyed out of the cutting chamber of the pelletizer 34 by
follows diverter valve 7 and adaptor 47 to connect the 40 an air stream created by the blower 36 and conveyed to
diverter valve to the hopper 48 of the extruder 8. The the cyclone 38 and then into a container.
diverter valve 7 also includes diverter valve chute 49 in [0044] It is also contemplated as a part of the present
the event the wax is to be diverted from the extruder invention that the cutting chamber of the dry face pel-
hopper and to a drain or recycled back to an earlier stage letizer as disclosed herein can be purged and/or the pel-
of the process and equipment. 45 lets conveyed using an inert gas. Some wax or wax-like
[0040] The extruder 8 includes a chiller 411 to thereby materials to be processed in accordance with the present
cool and thoroughly mix the wax to the desired pelletizing invention can negatively react and/or oxidize (degrade)
temperature so that the wax becomes a malleable ho- with exposure to ambient atmosphere. In order to mini-
mogeneous solid at the exit end of the extruder. Adaptor mize such ambient atmospheric reactions and/or to main-
413 connects the exit end of the extruder to the polymer 50 tain the desired properties of the materials being pel-
diverter valve 9 which then connects into the pelletizer letized, it is contemplated that an inert gas, instead of air,
10. A rotary cutter (not separately numbered) cuts the be used to purge the cutting chamber and convey the
extruded solid wax strands exiting the orifices of the die formed pellets. The inert gas can also be used to help
plate (also not separately numbered) in the cutting cham- further cool the pelletized materials, and the equipment
ber 16a. The cut wax pellets drop from the cutting cham- 55 immediately following the pelletizing step should be suit-
ber of pelletizer 10 onto conveyor 11 and then onto clas- ably designed to handle and maintain the presence and
sifier 12. Optionally a blower and duct 412 can be at- use of the inert gas until the pellets have been suitably
tached to the cutting chamber to aid in cooling and as- packaged for storage and/or taken further on for subse-

7
 13 EP 1 991 402 B1 14

quent processing. row temperature range of transition from the solid

[0045] Polyethylene wax pellets from test runs using state to the liquid state, in which the materials are
the above described equipment and processing are extruded through die orifices of a die plate of a pel-
shown in Figures 4A-4H. As there illustrated, the appa- letizer (10) to form strands, and the strands are cut
ratus and.process of the present invention was success- 5 into pellets,
ful in producing uniform polyethylene wax pellets having characterized in that
a diameter of about 3mm.
[0046] Waxes, individually or formulationally, which (a) a wax or wax-like material having a sharp
may be processed in accordance with the present inven- melt point is formed into a hot liquid melt, a tem-
tion, include acid waxes, beeswax, candelilla wax, car- 10 perature of said hot liquid melt being above a
nauba, ceresin wax, China wax, copolymer waxes, ester melt point of said wax or wax-like material;
waxes, Fischer-Tropsch waxes including oxidized forms, (b) the hot liquid melt material is cooled using
high density low molecular weight polyethylene or cooling surfaces of a cooling section (8b) of with-
HDLMWPE, hydroxystearamide wax, japan wax, larde- in a cooling extruder (8) to a temperature below
ceine, lignite wax, linear and branch chained waxes, 15 said melt point to cause the wax or wax-like ma-
maleated waxes, montan wax, microcrystalline wax, non- terial to change state to be in an extrudable solid
polar and polar polyethylene, polypropylene and polyole- condition in said extruder, said step of cooling
fin waxes, oxidized waxes, ozokerite, paraffin or petro- including exposing said wax or wax-like material
leum wax, polyethylene wax, polyolefin wax, rice bran to said extruder cooling surfaces to form cooled
wax, saponified and partially saponified waxes, substi- 20 layers that are moved away from the extruder
tuted amide wax, sugarcane wax, sulfonated waxes, sur- cooling surfaces and interspersed with warmer
face modified waxes and vegetable waxes including layers of wax or wax-like material into a mixture
those from bayberry, canola, coconut, corn, cottonseed, and then returning the mixture to the cooling sur-
crambe, linseed, palm, palm kernel, peanut, grape or faces for more heat energy reduction while said
soybean. 25 wax or wax-like material is in said cooling ex-
[0047] Other materials which can be pelletized accord- truder, said cooling extruder being supported by
ing to the present invention include fatty acids and esters, a cooling system (8e);
tackifiers and de-tackifiers, rosins and organic resins, vis- (c) extruding the mixture of said wax or wax-like
cosity and rheology modifiers, solid surfactants, water material in said solid state through die orifices
soluble polymers including polyethylene oxide and poly- 30 of the die plate to form strands; and
propylene oxide, tallow, lanolin and animal fats. (d) cutting the solid extruded strands with a ro-
[0048] Still more materials for which the present inven- tary cutter in a cutting chamber (16a) absent any
tion can be useful include high melt flow index materials liquid to form said wax or wax-like material into
and low molecular weight materials, waxlike organic pol- pellets.
ymers, oligomers, cyclic polymers and oligomers and or- 35
ganic compounds. 2. The method of claim 1, wherein said pellets are made
[0049] It is believed that the apparatus and process of to fall by gravity out of a bottom opening of said cut-
the present invention produce high quality pellets and ting chamber.
micro-pellets suitable for packaging or use as is or to be
ground into a fine powder. The present invention can 40 3. The method of claim 2, wherein said pellets exiting
most quickly, safely and efficiently get the wax from its said cutting chamber are directed to a conveyor (11)
hottest molten state to being cool enough to transport and are transported away by the conveyor to a pellet
and/or package while doing so in the least amount of screener, cooler and/or packaging unit.
space. Furthermore, there is optimum flexibility to proc-
ess the widest range of wax grades, weights, melt 45 4. The method of claim 1, wherein said cutting chamber
strengths, thermal properties, etc., to produce a very wide and said rotary cutter are part of a hot face pelletizer
variety of pellet sizes and to cover a very broad range of operated without water or other cooling liquid as a
production rates. In addition, the present invention is flex- dry face pelletizer.
ible enough to allow a wide variety of additives to be
blended into the wax being pelletized and also allows for 50 5. The method of claim 1, wherein said hot-melted wax
relatively easy cleaning of the equipment when switching or wax-like material is selected from the group con-
between products. sisting of acid waxes, beeswax, candelilla wax, car-
nauba, ceresin wax, China wax, copolymer waxes,
ester waxes, Fischer-Tropsch waxes including oxi-
Claims 55 dized forms, high density low molecular weight pol-
yethylene or HDLMWPE, hydroxystearamide wax,
1. A method for pelletizing materials having a sharp japan wax, lardeceine, lignite wax, linear and branch
melt point, a sharp melt point being defined as a nar- chained waxes, maleated waxes, montan wax, mi-

8
 15 EP 1 991 402 B1 16

crocrystalline wax, nonpolar and polar polyethylene, for concurrently mixing and re-mixing the wax or
polypropylene and polyolefin waxes, oxidized wax- wax-like material into a thoroughly mixed extrudable
es, ozokerite, paraffin or petroleum wax, polyethyl- solid material, said wax or wax-like material being
ene wax, polyolefin wax, rice bran wax, saponified exposed to said extruder cooling surfaces to form
and partially saponified waxes, substituted amide 5 cooled layers that are moved away from said extrud-
wax, sugarcane wax, sulfonated waxes, surface er cooling surfaces and interspersed with warmer
modified waxes and vegetable waxes including layers of wax or wax-like material into a mixture and
those from bayberry, canola, coconut, corn, cotton- then returned to the extruder cooling surfaces for
seed, crambe, linseed, palm, palm kernel, peanut, more heat energy reduction while said mixture is in
grape or soybean. 10 said extruder (8), extrudable solid material from said
extruder being extruded through the die plate with
6. The method of claim 1, wherein step (b) is carried die orifices and die face of the pelletizer (10);
out in two stages; in the first stage, the temperature a cooling system (8e) for supporting said extruder
of the wax or wax-like material is reduced to a tem- (8), wherein the cutting chamber (16a) and rotary
perature just above where the wax or wax-like ma- 15 cutter cooperate with said die face to cut said thor-
terial will change from a liquid to a solid so that the oughly mixed extrudable solid material extruded
wax or wax-like material remains liquid enough to through said die orifices into pellets in the absence
have good unobstructed flow and, in the second of liquid, preferably said cutting chamber having a
stage, the temperature of the wax or wax-like liquid bottom opening through which said pellets fall out
material is further reduced so that the wax or wax- 20 by gravity.
like material is a thoroughly mixed extrudable solid
material, the temperature of the wax or wax-like ma- 11. The apparatus of claim 10, wherein said die plate
terial in the first stage preferably being reduced to and said rotary cutter are part of a hot face pelletizer
approximately 5°C or less above said liquid to solid that includes an inlet opening and an outlet opening,
transition temperature of the wax or wax-like mate- 25 said hot face pelletizer preferably being convertible
rial. to an underwater pelletizer with liquid.

7. The method of claim 4, wherein said pellets are re- 12. The apparatus of claim 10, further comprising a con-
moved from said cutting chamber by an inert gas veyor (11) to transport away said pellets exiting from
introduced into one side of said cutting chamber 30 said cutting chamber.
which conveys the pellets out of another side of said
cutting chamber. 13. The apparatus of claim 10, further comprising a first
stage cooler (5) including a heat transfer device for
8. The method of claim 6, further comprising the step cooling the molten wax or wax-like material to a tem-
of raising the temperature of the wax or wax-like ma- 35 perature just above its melt temperature so that the
terial being pelletized while forming the wax or wax- wax or wax-like material remains liquid enough to
like material into a mixture if said material has lost have good unobstructed flow, said extruder (8) being
sufficient malleability for processing. located downstream of said first stage cooler with
respect to a direction of said flow for receiving, as a
9. The method of claim 6, wherein said second stage 40 second stage cooler, wax or wax-like material initially
is carried out in a screw-type extruder (8), preferably cooled by said first stage cooler.
with two or more screws and most preferably in a
co-rotating and inter-meshing twin or two screw ex- 14. The apparatus of claim 13, wherein said heat transfer
truder. device is a heat exchanger, including plate and frame
45 type, coil type, scrape-wall type, U-style tube type
10. An apparatus for forming pellets from a wax or wax- with or without static mixers, and shell and tube type
like material having a sharp melt point that has been with or without static mixers, preferably said shell
melted to a molten condition at a temperature above and tube type with static mixers.
a melt point of said wax or wax-like material, a sharp
melt point being defined as a narrow temperature 50 15. The apparatus of claim 13, wherein said heat transfer
range of transition from the solid state to the liquid device and said extruder include heating elements
state, the apparatus including a pelletizer (10) with to increase the temperature of the wax or wax-like
a die plate having die orifices and a die face, and a material therein if said material has lost sufficient
cutting chamber (16a) with a rotary cutter, malleability for processing.
characterized in that the apparatus further com- 55
prises cooling section (8b) of an extruder (8) having
cooling surfaces for reducing the temperature of the
wax or wax-like material below said melt point and

9
 17 EP 1 991 402 B1 18

Patentansprüche 4. Verfahren nach Anspruch 1, wobei die Schneidkam-

mer und das rotierende Messer Teil eines Heißab-
1. Verfahren zum Pelletieren von Materialien mit einem schlag-Granulators sind, der ohne Wasser oder
scharfen Schmelzpunkt, wobei ein scharfer sonstige Kühlflüssigkeit als Trocken-Granulator be-
Schmelzpunkt definiert ist als schmaler Temperatur- 5 trieben wird.
bereich des Übergangs vom festen Zustand in den
flüssigen Zustand, bei dem die Materialien durch Dü- 5. Verfahren nach Anspruch 1, wobei das heiß ge-
senöffnungen einer Düsenplatte eines Granulators schmolzene Wachs oder wachsartige Material aus
(10) extrudiert werden, um Stränge zu bilden, und der aus Säurewachsen, Bienenwachs, Candelilla-
die Stränge zu Pellets geschnitten werden, 10 wachs, Carnaubawachs, Erdwachs, Chinawachs,
dadurch gekennzeichnet, dass Copolymerwachsen, Esterwachsen, Fischer-
Tropsch-Wachsen einschließlich oxidierten For-
(a) ein Wachs oder wachsartiges Material mit men, Polyethylen hoher Dichte von niedrigem Mo-
einem scharfen Schmelzpunkt in eine heiße lekulargewicht oder HDLMWPE, Hydroxysteara-
flüssige Schmelze umgeformt wird, wobei eine 15 midwachs, Japanwachs, Lardecein, Lignitwachs,
Temperatur der heißen flüssigen Schmelze gerad- oder verzweigtkettigen Wachsen, maleinier-
über einem Schmelzpunkt des Wachses oder ten Wachsen, Montanwachs, mikrokristallinem
wachsartigen Materials liegt; Wachs, unpolaren und polaren Polyethylen-, Poly-
(b) die heiße flüssige Schmelze unter Verwen- propylen- und Polyolefinwachsen, oxidierten Wach-
dung von Kühlflächen eines Kühlteils (8b) eines 20 sen, Ozokerit, Paraffin- oder Erdölwachs, Polyethy-
Kühlextruders (8) auf eine Temperatur unter lenwachs, Polyolefinwachs, Reiskleiewachs, ver-
dem Schmelzpunkt abgekühlt wird, damit das seiften und partiell verseiften Wachsen, substituier-
Wachs oder wachsartige Material seinen Zu- tem Amidwachs, Zuckerrohrwachs, sulfonierten
stand in einen extrudierbaren festen Zustand in Wachsen, oberflächenmodifizierten Wachsen und
dem Extruder ändert, wobei bei dem Schritt des 25 pflanzlichen Wachsen einschließlich Myrtenwachs,
Kühlens das Wachs oder wachsartige Material Wachs aus Raps, Kokosnuss, Mais, Baumwollsa-
den Kühlflächen des Extruders ausgesetzt wird, men, Crambe, Leinsamen, Palmwachs, Palmkern-
um gekühlte Schichten zu bilden, die von den wachs, Erdnuss-, Trauben- oder Sojabohnenwachs
Kühlflächen des Extruders wegbewegt werden bestehenden Gruppe ausgewählt ist.
und von wärmeren Schichten aus Wachs oder 30
wachsartigem Material zu einer Mischung 6. Verfahren nach Anspruch 1, wobei Schritt (b) in zwei
durchzogen sind, und wobei dann die Mischung Stufen durchgeführt wird: in der ersten Stufe wird die
zur weiteren Verringerung der Wärmeenergie Temperatur des Wachses oder wachsartigen Mate-
zu den Kühlflächen zurückgeführt wird, während rials auf eine Temperatur knapp über der Tempera-
sich das Wachs oder wachsartige Material in 35 tur verringert, wo sich das Wachs oder wachsartige
dem Kühlextruder befindet, wobei der Kühlex- Material von fest nach flüssig ändern wird, so dass
truder auf einem Kühlsystem (8e) gelagert ist; das Wachs oder wachsartige Material flüssig genug
(c) die Mischung aus dem Wachs oder wachs- bleibt, um eine gute ungehinderte Strömung zu ha-
artigen Material in dem festen Zustand durch ben, und in der zweiten Stufe wird die Temperatur
Düsenöffnungen der Düsenplatte extrudiert 40 des Wachses oder wachsartigen Materials weiter
wird, um Stränge zu bilden; und verringert, so dass das Wachs oder wachsartige Ma-
(d) die extrudierten festen Stränge mit einem ro- terial ein gut durchmischtes, extrudierbares festes
tierenden Messer in einer Schneidkammer Material ist, wobei die Temperatur des Wachses
(16a) ohne jegliche Flüssigkeit geschnitten wer- oder wachsartigen Materials in der ersten Stufe vor-
den, um das Wachs oder wachsartige Material 45 zugsweise auf ungefähr 5°C oder weniger über der
zu Pellets zu formen. Temperatur des Übergangs des Wachses oder
wachsartigen Materials von flüssig nach fest verrin-
2. Verfahren nach Anspruch 1, wobei man die Pellets gert wird.
durch Schwerkraft aus einer unteren Öffnung der
Schneidkammer fallen lässt. 50 7. Verfahren nach Anspruch 4, wobei die Pellets aus
der Schneidkammer durch ein in eine Seite der
3. Verfahren nach Anspruch 2, wobei die aus der Schneidkammer eingeleitetes Inertgas entfernt wer-
Schneidkammer austretenden Pellets zu einem För- den, das die Pellets aus der anderen Seite der
derband (11) gelenkt werden und durch das Förder- Schneidkammer herausbefördert.
band zu einer Pelletsiebvorrichtung, einem Kühler 55
und/oder einer Verpackungseinheit abtransportiert 8. Verfahren nach Anspruch 6, ferner umfassend den
werden. Schritt des Anhebens der Temperatur des zu pelle-
tierenden Wachses oder wachsartigen Materials,

10
 19 EP 1 991 402 B1 20

während das Wachs oder wachsartige Material zu 11. Vorrichtung nach Anspruch 10, wobei die Düsenplat-
einer Mischung geformt wird, wenn das Material aus- te und das rotierende Messer Teil eines Heißab-
reichend Geschmeidigkeit für die Verarbeitung ver- schlag-Granulators sind, der eine Einlassöffnung
loren hat. und eine Auslassöffnung aufweist, wobei der
5 Heißabschlag-Granulator vorzugsweise in einen
9. Verfahren nach Anspruch 6, wobei die zweite Stufe Unterwassergranulator mit Flüssigkeit umgewandelt
in einem Schneckenextruder (8), vorzugsweise mit werden kann.
zwei oder mehr Schnecken, und am meisten bevor-
zugt in einem gleichsinnig drehenden und dichtkäm- 12. Vorrichtung nach Anspruch 10, ferner umfassend
menden Doppel- oder Zweischneckenextruder 10 ein Förderband (11), um die aus der Schneidkammer
durchgeführt wird. austretenden Pellets abzutransportieren.

10. Vorrichtung zur Bildung von Pellets aus einem 13. Vorrichtung nach Anspruch 10, ferner umfassend ei-
Wachs oder wachsartigen Material mit einem schar- nen Kühler (5) der ersten Stufe mit einer Wärmeü-
fen Schmelzpunkt, das zu einem geschmolzenen 15 bertragungsvorrichtung zum Kühlen des geschmol-
Zustand bei einer Temperatur über einem Schmelz- zenen Wachses oder wachsartigen Materials auf ei-
punkt des Wachses oder wachsartigen Materials ge- ne Temperatur knapp über seiner Schmelztempera-
schmolzen wurde, wobei ein scharfer Schmelzpunkt tur, so dass das Wachs oder wachsartige Material
definiert ist als schmaler Temperaturbereich des flüssig genug bleibt, um eine gute ungehinderte Strö-
Übergangs vom festen Zustand in den flüssigen Zu- 20 mung zu haben, wobei sich der Extruder (8) strom-
stand, wobei die Vorrichtung einen Granulator (10) abwärts von dem Kühler der ersten Stufe in Bezug
mit einer Düsenplatte mit Düsenöffnungen und einer auf eine Strömungsrichtung befindet, um als Kühler
Düsenfläche sowie eine Schneidkammer (16a) mit der zweiten Stufe Wachs oder wachsartiges Material
einem rotierenden Messer umfasst, aufzunehmen, das zunächst durch den Kühler der
dadurch gekennzeichnet, dass die Vorrichtung 25 ersten Stufe gekühlt wurde.
ferner Folgendes umfasst:
14. Vorrichtung nach Anspruch 13, wobei die Wärmeü-
ein Kühlteil (8b) eines Extruders (8) mit Kühlflä- bertragungsvorrichtung ein Wärmetauscher ist, ein-
chen zur Verringerung der Temperatur des schließlich Platten- und Rahmenwärmetauscher,
Wachses oder wachsartigen Materials unter 30 Spulenwärmetauscher, Abstreifwärmetauscher, U-
den Schmelzpunkt und zum gleichzeitigen Mi- Rohr-Wärmetauscher mit oder ohne statische
schen und erneuten Mischen des Wachses oder Mischer sowie Rohrbündelwärmetauscher mit oder
wachsartigen Material zu einem gut durch- ohne statische Mischer, vorzugsweise Rohrbündel-
mischten extrudierbaren festen Material, wobei wärmetauscher mit statischen Mischern.
das Wachs oder wachsartige Material den Kühl- 35
flächen des Extruders ausgesetzt wird, um ge- 15. Vorrichtung nach Anspruch 13, wobei die Wärmeü-
kühlte Schichten zu bilden, die von den Kühlflä- bertragungsvorrichtung und der Extruder Heizele-
chen des Extruders wegbewegt werden und von mente aufweisen, um die Temperatur des Wachses
wärmeren Schichten aus Wachs oder wachsar- oder wachsartigen Materials darin zu erhöhen, wenn
tigem Material zu einer Mischung durchzogen 40 das Material ausreichend Geschmeidigkeit für die
sind und dann zu den Kühlflächen des Extruders Verarbeitung verloren hat.
für eine weitere Verringerung der Wärmeener-
gie zurückgeführt werden, während sich die Mi-
schung in dem Extruder (8) befindet, wobei ex- Revendications
trudierbares festes Material aus dem Extruder 45
durch die Düsenplatte mit Düsenöffnungen und 1. Procédé de pastillage de matériaux possédant un
Düsenfläche des Granulators (10) extrudiert point de fusion pointu, un point de fusion pointu étant
wird; définie en tant que plage de température étroite de
ein Kühlsystem (8e) zur Lagerung des Extruders la transition de l’état solide à l’état liquide, dans le-
(8), 50 quel les matériaux sont extrudés à travers des orifi-
wobei die Schneidkammer (16a) und das rotie- ces de filière d’une plaque matrice d’un granulateur
rende Messer mit der Düsenfläche zusammen- (10) pour former des brins qui sont coupés en pas-
wirken, um das durch die Düsenöffnungen ex- tilles, caractérisé en ce que
trudierte gut durchmischte extrudierbare feste
Material ohne Flüssigkeit zu Pellets zu schnei- 55 (a) une cire ou un matériau analogue à la cire
den, wobei die Schneidkammer vorzugsweise ayant un point de fusion pointu est formé(e) dans
eine untere Öffnung besitzt, durch die die Pellets une masse fondue liquide chaude, une tempé-
aufgrund der Schwerkraft herausfallen. rature de la masse fondue liquide chaude étant

11
 21 EP 1 991 402 B1 22

plus élevée qu’un point de fusion de la cire ou HDLMWPE, la cire hydroxystéaramide, la cire japo-
du matériau analogue à la cire ; naise, la lardécéine, la cire de lignite, les cires à chaî-
(b) le matériau fondu liquide chaud est refroidi ne droite et ramifiée, les cires maléatées, la cire mon-
en utilisant des surfaces de refroidissement tanique, la cire microcristalline, les polyéthylènes
d’une section de refroidissement (8b) d’une ex- 5 non polaires et polaires, les cires de polypropylène
trudeuse de refroidissement (8) à une tempéra- et polyoléfine, les cires oxydées, l’ozokérite, la cire
ture inférieure audit point de fusion pour faire de paraffine ou de pétrole, la cire de polyéthylène,
changer d’état la cire ou le matériau analogue la cire de polyoléfine, la cire de son de riz, les cires
à la cire pour l’amener dans une condition solide saponifiées et partiellement saponifiées, la cire
extrudable dans ladite extrudeuse, l’étape de re- 10 d’amide substitué, la cire de canne à sucre, les cires
froidissement incluant le fait d’exposer la cire ou sulfonées, les cires modifiées en surface et les cires
le matériau analogue à la cire aux surfaces de végétales, y compris celles provenant du cirier, du
refroidissement de l’extrudeuse pour former des colza, de la noix de coco, du maïs, du cotonnier, du
couches refroidies qui sont éloignées des sur- chou marin, du lin, du palmier, du palmiste, de l’ara-
faces de refroidissement de l’extrudeuse et in- 15 chide, du raisin ou du soja.
tercalées avec des couches plus chaudes de
cire ou de matériau analogue à la cire pour for- 6. Procédé selon la revendication 1, dans lequel l’étape
mer un mélange et de ramener le mélange sur (b) est effectuée en deux étapes : dans la première
les surfaces de refroidissement pour réduire da- étape, la température de la cire ou du matériau ana-
vantage l’énergie de chaleur pendant que la cire 20 logue à la cire est réduite à une température juste
ou le matériau analogue à la cire est dans l’ex- au-dessus de la température à laquelle la cire ou le
trudeuse de refroidissement, ladite extrudeuse matériau analogue à la cire passe d’un état liquide
de refroidissement étant montée sur un système à un état solide de sorte que la cire ou le matériau
de refroidissement (8e), analogue à la cire reste suffisamment liquide pour
(c) le mélange de cire ou de matériau analogue 25 avoir un bon écoulement non obstrué, et dans la se-
à la cire est extrudé dans ledit état solide à tra- conde étape, la température de la cire ou de la ma-
vers des orifices de filière de la plaque matrice tière analogue à la cire est encore réduite de sorte
pour former des brins ; et que la cire ou le matériau analogue à la cire est un
(d) les brins extrudés solides sont coupés au matériau solide extrudable soigneusement mélan-
moyen d’un outil de coupe rotatif dans une 30 gé, la température de la cire ou du matériau analogue
chambre de coupe (16a) sans aucun liquide à la cire, dans la première étape, étant réduite de
pour former des pastilles à partir de la cire ou préférence à environ 5°C ou moins au-dessus de la
du matériau analogue à la cire. température de transition de l’état liquide à l’état so-
lide de la cire ou du matériau analogue à la cire.
2. Procédé selon la revendication 1, dans lequel les 35
pastilles sont amenées à tomber par gravité hors 7. Procédé selon la revendication 4, dans lequel lesdi-
d’une ouverture de fond de la chambre de coupe. tes pastilles sont retirées de ladite chambre de coupe
par un gaz inerte introduit dans un côté de ladite
3. Procédé selon la revendication 2, dans lequel les chambre de coupe, qui transporte les pastilles hors
pastilles qui sortent de la chambre de coupe sont 40 de l’autre côté de ladite chambre de coupe.
dirigées vers un convoyeur (11) et sont évacuées
par le convoyeur vers un crible à pastilles, un refroi- 8. Procédé selon la revendication 6, comprenant en
disseur et/ou une unité d’emballage. outre l’étape consistant à élever la température de
la cire ou du matériau analogue à la cire qui est pas-
4. Procédé selon la revendication 1, dans lequel la 45 tillée pendant que la cire ou le matériau analogue à
chambre de coupe et l’outil de coupe rotatif font par- la cire est transformé(e) en un mélange si ledit ma-
tie d’un granulateur à face chaude qui fonctionne tériau a perdu de malléabilité suffisante pour le trai-
sans eau ou autre liquide de refroidissement en tant tement.
que granulateur à face sèche.
50 9. Procédé selon la revendication 6, dans lequel ladite
5. Procédé selon la revendication 1, dans lequel la cire seconde étape est réalisée dans une extrudeuse (8)
ou le matériau analogue à la cire fondue à chaud est de type à vis, de préférence avec deux vis ou plus
choisie parmi le groupe constitué par les cires aci- et avec une plus grande préférence dans une extru-
des, la cire d’abeille, la cire de candelilla, le car- deuse double-vis ou à deux vis en corotation et s’en-
nauba, la cire cérésine, la cire de Chine, les cires de 55 grenant mutuellement.
copolymère, les cires d’ester, les cires Fischer-
Tropsch y compris les formes oxydées, le polyéthy- 10. Appareil pour former des pastilles à partir d’une cire
lène à haute densité et faible poids moléculaire ou ou du matériau analogue à la cire ayant un point de

12
 23 EP 1 991 402 B1 24

fusion pointu qui a été fondu dans un état fondu à froidir la cire ou le matériau analogue à la cire à une
une température supérieure à un point de fusion de température juste au-dessus de sa température de
ladite cire ou du matériau analogue à la cire, un point fusion de telle sorte que la cire ou le matériau ana-
de fusion pointu étant défini en tant qu’une plage de logue à la cire reste suffisamment liquide pour avoir
température étroite de transition de l’état solide à 5 un bon écoulement non obstrué, l’extrudeuse (8)
l’état liquide, l’appareil comprenant un granulateur étant située en aval du refroidisseur de la première
(10) avec une plaque matrice possédant des orifices étape par rapport à une direction de l’écoulement
de filière et une face de filière et une chambre de pour recevoir, en tant que refroidisseur de la deuxiè-
coupe (16a) avec un outil de coupe rotatif, me étape, de la cire ou du matériau analogue à la
caractérisé en ce que l’appareil comprend en 10 cire initialement refroidie par le refroidisseur de la
outre : première étape.

une section de refroidissement (8b) d’une extru- 14. Appareil selon la revendication 13, dans lequel ledit
deuse (8) possédant des surfaces de refroidis- dispositif de transfert de chaleur est un échangeur
sement pour réduire la température de la cire 15 de chaleur, y compris le type à plaque et à cadre, le
ou du matériau analogue à la cire en-dessous type à bobine, le type à raclage mural, le type à tube
dudit point de fusion et pour mélanger et en mê- en forme de U avec ou sans mélangeurs statiques,
me temps remélanger la cire ou le matériau ana- et le type à calandre et tube avec ou sans mélan-
logue à la cire en un matériau solide extrudable geurs statiques, le type à calandre et tube ayant de
soigneusement mélangé, la cire ou la matière 20 préférence des mélangeurs statiques.
analogue à la cire étant exposée aux surfaces
de refroidissement de l’extrudeuse pour former 15. Appareil selon la revendication 13, dans lequel le
des couches refroidies qui sont éloignées des dispositif de transfert de chaleur et l’extrudeuse com-
surfaces de refroidissement de l’extrudeuse et prennent des éléments de chauffage pour augmen-
intercalées avec des couches plus chaudes de 25 ter la température de la cire ou du matériau analogue
cire ou de matériau analogue à la cire pour for- à la cire dans celui-ci si le matériau a perdu de mal-
mer un mélange et puis ramenée sur les surfa- léabilité suffisante pour le traitement.
ces de refroidissement de l’extrudeuse pour ré-
duire davantage l’énergie de chaleur pendant
que le mélange est dans l’extrudeuse (8), la ma- 30
tière solide extrudable étant extrudée à travers
la plaque matrice avec des orifices de filière et
une face de filière du granulateur (10) ;
un système de refroidissement (8e) pour soute-
nir ladite extrudeuse (8), 35
dans lequel la chambre de coupe (16e) et l’outil
de coupe rotatif coopèrent avec ladite face de
filière pour couper la matière solide extrudable
soigneusement mélangée, extrudée à travers
les orifices de filière pour former des pastilles 40
en l’absence de liquide, la chambre de coupe
ayant de préférence une ouverture de fond à
travers laquelle les pastilles tombent par gravité.

11. Appareil selon la revendication 10, dans lequel la 45

plaque matrice et l’outil de coupe rotatifs font partie
d’un granulateur à face chaude qui comprend une
ouverture d’entrée et une ouverture de sortie, le gra-
nulateur à face chaude étant de préférence conver-
sible en un granulateur immergé avec du liquide. 50

12. Appareil selon la revendication 10, comprenant en

outre un convoyeur (11) pour évacuer les pastilles
sortant de la chambre de coupe.
55
13. Appareil selon la revendication 10, comprenant en
outre un refroidisseur de la première étape (5) com-
prenant un dispositif de transfert de chaleur pour re-

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EP 1 991 402 B1

14
EP 1 991 402 B1

15
EP 1 991 402 B1

16
EP 1 991 402 B1

17
EP 1 991 402 B1

18
EP 1 991 402 B1

19
EP 1 991 402 B1

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 EP 1 991 402 B1

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European
patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be
excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• DE 3247406 A1 [0011] • US 2216188 A [0015]

• WO 2007064580 A2 [0012] • US 5059103 A [0018]
• US 3288892 A [0013] • US 7033152 B [0018]
• US 2004009254 A [0014]

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