U.S. patent application number 10/743501 was filed with the patent office on 2004-07-08 for method for continuous gum base manufacturing.
Invention is credited to Song, Joo H., Townsend, Donald.
Application Number | 20040131725 10/743501 |
Document ID | / |
Family ID | 46203360 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040131725 |
Kind Code |
A1 |
Song, Joo H. ; et
al. |
July 8, 2004 |
Method for continuous gum base manufacturing
Abstract
A process for continuously producing a chewing gum base
comprising the steps of compounding the ingredients in a single
extruder. In an embodiment, the method includes the steps of
continuously adding an elastomer, a filler, and a plasticizer into
a continuous mixer, subjecting the elastomer, filler, and
plasticizer to a highly distributive mixing operation and
continuously discharging the resulting chewing gum base from the
mixer while the adding and mixing steps are in progress.
Inventors: |
Song, Joo H.; (Northbrook,
IL) ; Townsend, Donald; (Chicago, IL) |
Correspondence
Address: |
Bell, Boyd & Lloyd LLC
P.O. Box 1135
Chicago
IL
60690-1135
US
|
Family ID: |
46203360 |
Appl. No.: |
10/743501 |
Filed: |
December 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10743501 |
Dec 22, 2003 |
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09775785 |
Feb 2, 2001 |
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09775785 |
Feb 2, 2001 |
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08793887 |
May 12, 1998 |
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6238710 |
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08793887 |
May 12, 1998 |
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08126319 |
Sep 24, 1993 |
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5562936 |
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Current U.S.
Class: |
426/3 |
Current CPC
Class: |
A23G 4/02 20130101; A23G
4/00 20130101; B01F 35/91 20220101; A23G 4/06 20130101; B01F 27/722
20220101; B01F 35/715 20220101; B01F 2035/98 20220101; A23G 4/08
20130101 |
Class at
Publication: |
426/003 |
International
Class: |
A23G 003/30 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 1995 |
WO |
PCT/US95/03008 |
Claims
We claim:
1. A process for making chewing gum comprising the steps of: using
a single continuous mixing apparatus to perform all of the addition
and compounding steps necessary to produce gum base; adding to the
single continuous mixing apparatus all of a group of components
necessary to make a chewing gum base including an elastomer and a
plasticizer, wherein the elastomer is added to the single
continuous mixing apparatus separate and apart from the
plasticizer; providing at least two mixing zones in the mixing
apparatus; producing gum base from the mixing apparatus; and mixing
the gum base with other ingredients to produce chewing gum.
2. The continuous process of claim 1 wherein the at least two
mixing zones include a distributive mixing zone and a dispersive
mixing zone.
3. The continuous process of claim 1 wherein an elastomer and a
filler are fed into the mixing apparatus before other components of
the chewing gum base.
4. The continuous process of claim 1 wherein the mixing apparatus
includes a first dispersive mixing zone.
5. The continuous process of claim 1 wherein the mixing apparatus
is a high efficiency mixer.
6. The continuous process of claim 1 wherein the mixing apparatus
includes a blade-and-pin mixer.
7. The continuous process of claim 1 wherein the process is carried
out in a counter-rotating, intermeshing twin screw extruder.
8. The continuous process of claim 1 wherein the mixing apparatus
includes a plurality of toothed elements counter-rotating with
respect to adjacent toothed elements.
9. The continuous process of claim 1 wherein the gum base
components are added to the mixing apparatus at least two spatially
separated points.
10. The continuous process of claim 1 wherein a portion of the
chewing gum base components are subjected to a highly dispersive
mixing operation prior to a highly distributive mixing
operation.
11. The continuous process of claim 1 wherein the adding and mixing
steps are controlled to operate at a steady state.
12. The continuous process of claim 1 wherein at least some of the
components are added to the mixing apparatus at different locations
in an order that approximately corresponds to a decreasing order of
viscosity.
13. A process for producing chewing gum comprising the steps of:
using a single extruder to perform all necessary addition and
compounding steps to produce gum base; adding to the single
extruder all of a group of components necessary to make a gum base
including an elastomer and a plasticizer, wherein the elastomer is
added to the extruder separate and apart from the plasticizer;
mixing the components in the single extruder; producing the gum
base using the single extruder; and adding the gum base to other
ingredients to make chewing gum.
14. The continuous process of claim 13 wherein an elastomer and a
filler are fed into the extruder before other components of the gum
base.
15. The continuous process of claim 13 wherein the extruder
includes a first dispersive mixing zone.
16. The continuous process of claim 13 wherein the extruder is a
high efficiency mixer.
17. The continuous process of claim 13 wherein the extruder
includes a blade-and-pin mixer.
18. The continuous process of claim 13 wherein the process is
carried out in a counter-rotating, intermeshing twin screw
extruder.
19. A process for making chewing gum in a continuous chewing gum
production line comprising the steps of: using a single extruder to
perform all of the addition and compounding steps necessary to
produce a gum base; adding to the single extruder components
necessary to make a gum base the components including an elastomer
and a plasticizer, wherein the elastomer is added to the single
continuous mixing apparatus separate and apart from the
plasticizer; producing gum base from the single extruder; adding
the gum base to water-soluble ingredients; and mixing the chewing
gum base and water-soluble ingredients to produce chewing gum.
20. The continuous process of claim 19 wherein an elastomer and a
filler are fed into the extruder before other components of the gum
base.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present invention is a continuation-in-part of U.S. Ser.
No. 08/126,319, filed Sep. 24, 1993 and entitled: "Continuous Gum
Base Manufacturing Using Highly Distributive Mixing," the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a continuous process for
the manufacture of chewing gum bases.
[0003] A typical chewing gum base includes one or more elastomers,
one or more fillers, one or more elastomer solvents, plasticizers
and optional plastic polymers, waxes, emulsifiers and miscellaneous
colors, flavors and antioxidants. Due primarily to the difficulty
in melting and dispersing the elastomers homogeneously among the
other gum base ingredients, gum base manufacture has typically been
a tedious and time-consuming batch process. For example, one such
conventional process uses a sigma blade batch mixer having a front
to rear blade speed ratio of about 2:1, and a mixing temperature of
about 80-120.degree. C.
[0004] In this conventional process, initial portions of elastomer,
elastomer solvent and filler are added to the heated sigma blade
mixer and blended until the elastomer is melted or smeared and
thoroughly mixed with the plasticizer and fillers. Then the
remaining portions of elastomer, elastomer solvent, plasticizer,
fillers, emulsifiers and other ingredients are added sequentially,
in a stepwise fashion, often with sufficient time for each stepwise
addition to become completely mixed before adding more ingredients.
Depending on the composition of the particular chewing gum bases
and, in particular, the amount and type of elastomer, considerable
patience may be required to insure that each ingredient becomes
thoroughly mixed. Overall, anywhere from one to four hours of
mixing time can be required to make one batch of chewing gum base
using a conventional sigma blade mixer.
[0005] After mixing, the molten gum base batch must be emptied from
the mixer into coated or lined pans, or pumped to other equipments
such as a holding tank or a filtering device, then extruded or cast
into shapes, and allowed to cool and solidify, before being ready
for use in chewing gum. This additional processing and cooling
requires even more time.
[0006] Various efforts have been undertaken to try to simplify and
reduce the time required for gum base manufacture. European Patent
Publication No. 0 273 809, in the name of General Foods France,
discloses a process for making nonadhesive chewing gum base by
blending elastomer and filler components together in a continuous
mill to form a non-adhesive premix, dividing the premix into
fragments, and blending the premix fragments and at least one other
nonadhesive gum base component together in a powder mixer.
Alternatively, the premix fragments and other base components can
be added to an extruder along with other chewing gum components to
accomplish direct manufacture of chewing gum.
[0007] French Patent Publication No. 2 635 441, also in the name of
General Foods France, discloses a process for making a gum base
concentrate using a twin screw extruder. The concentrate is
prepared by mixing high molecular weight elastomers and
plasticizers in desired proportions and feeding them into the
extruder. Mineral fillers are added to the extruder downstream of
the feed inlet of the elastomer/plasticizer blend. The resulting
gum base concentrate has a high level of elastomers. The
concentrate can then be mixed with the other gum base ingredients
to provide a complete gum base.
[0008] U.S. Pat. No. 4,968,511, issued to D'Amelia et al.,
discloses that chewing gum can be made directly in a one-step
compounding process (without making an intermediate gum base) if
certain vinyl polymers are used as the elastomer portion.
[0009] U.S. Pat. No. 4,187,320, issued to Koch et al., discloses a
two-stage process for making a chewing gum base in a mixing
kettle.
[0010] U.S. Pat. No. 4,305,962, issued to del Angel, discloses a
process for making an elastomer/resin masterbatch as a precursor to
a gum base.
[0011] U.S. Pat. No. 4,459,311, issued to DeTora et al., discloses
making gum base using three separate mixers--a high intensity mixer
for pre-plasticizing the elastomer in the presence of a filler,
followed by a medium intensity mixer for ultimately blending all
the gum base components together.
[0012] Several publications disclose that a continuous extruder can
be used to make the ultimate chewing gum product aft r a separate
process has previously been used to make the chewing gum base.
These publications include U.S. Pat. No. 5,135,760, issued to
Degady et al.; U.S. Pat. No. 5,045,325, issued to Lesko et al., and
U.S. Pat. No. 4,555,407, issued to Kramer et al.
[0013] Notwithstanding the prior efforts described above, there is
a need and desire in the chewing gum industry for a continuous
process which can effectively and efficiently be used to make a
variety of complete chewing gum bases without limiting the type or
quantity of elastomer employed, and without requiring preblending
or other pretreatment of the elastomer. It would be particularly
beneficial to be able to produce high quality chewing gum bases
that incorporate waxes, fats and/or oils as plasticizers in the gum
using a continuous process.
SUMMARY OF THE INVENTION
[0014] The present invention provides a continuous process of
making a chewing gum base using a single mixer (extruder) which is
suitable for use with any conventional gum base elastomer, in any
conventional amount, without requiring preblending or pretreatment
of the elastomer with any other ingredient. For instance, the
present invention can be used for the continuous manufacture of a
wide variety of gum bases which include many or all of the
following components, in the following percentages:
1 Component Range (% by weight) Elastomer(s) 5.0-95 Elastomer
Solvent(s) 0-50 Plasticizer(s) 0-75 Wax(es) 0-30 Emulsifier(s)
0.5-40 Filler(s) 1.0-65 Colorant(s)/flavor(s) 0-3.0
[0015] To this end, in an embodiment, a process for making chewing
gum base is provided comprising adding to a single extruder all of
the components necessary to make chewing gum base. At least two
mixing zones are provided in the extruder wherein the components
are subjected to different mixing conditions in each mixing zone.
Chewing gum base is thereby produced from the single extruder.
[0016] In an embodiment, the extruder is a high efficiency mixer.
For example, the extruder can include a blade-and-pin mixer.
[0017] In another embodiment of the method, a process for producing
chewing gum base is provided comprising the steps of: adding to a
single extruder all of the components necessary to make a chewing
gum base; mixing the components in a single extruder; and producing
the chewing gum base using the single extruder.
[0018] In another embodiment of the method, a process for providing
chewing gum is provided comprising the steps of: adding to a single
extruder all of the components necessary to make chewing gum base;
providing at least two mixing zones in the extruder wherein the
components are subjected to different mixing conditions in each
mixing zone; producing chewing gum base from the single extruder;
and mixing the chewing gum base with other ingredients to produce
chewing gum.
[0019] The present invention has several different aspects, which
can be employed together, separately, or in any combination. All of
these aspects can be performed together, in sequence, using a
single continuous mixing process, for example, in a twin-screw
extruder.
[0020] In an aspect of the method, the elastomer, elastomer solvent
and filler are continuously mixed together under conditions of
highly dispersive mixing. By "highly dispersive mixing" it is meant
that the elastomer, elastomer solvent and filler are broken down
into very small particles, droplets or "domains" which readily
become dispersed among themselves and which can later be
distributed, substantially homogeneously, among the other gum base
ingredients. This dispersive mixing stage can be thought of as a
disentanglement and "breaking down" stage for the gum base
components which are the most difficult to disperse. Special mixing
elements are used for this purpose, as discussed below in the
detailed description of the presently preferred embodiments.
[0021] In an aspect of the method, the chewing gum base-ingredients
are added sequentially to the continuous extruder, at different
locations, in an order which approximately corresponds to a
decreasing order of viscosity. The relatively high viscosity
chewing gum base ingredients (for example, most elastomers) are
added to the extruder first with filler and elastomer solvent, at
an upstream location, and are mixed together. The filler and
elastomer solvent help disperse the elastomer. The intermediate
viscosity gum base ingredients (for example, polyvinyl acetate, low
molecular weight elastomers and elastomer solvents) are added to
the extruder second, at an intermediate location, and are mixed
with the high viscosity ingredients previously added. The
relatively low viscosity gum base ingredients (for example, oils,
fats and waxes) are added to the extruder third, at a downstream
location, and are mixed with the high and intermediate viscosity
ingredients previously added.
[0022] In an aspect of the method, the elastomer, elastomer
solvent, filler, any intermediate viscosity ingredients (for
example, polyvinyl acetate) and, optionally, low viscosity
ingredients (for example, fats, oils and waxes) are continuously
mixed together under conditions of highly distributive mixing. By
"highly distributive mixing" it is meant that the ingredients are
spread out or "distributed" among each other to form a
substantially homogeneous chewing gum abase blend. By way of
analogy, the "dispersive mixing" stage, described above, causes the
elastomer, using the filler as a processing aid for dispersive
mixing, to be "broken down" into very small particles, droplets or
domains. The "distributive mixing" stage, which occurs further
downstream in the continuous process, causes these very small
particles, droplets or domains to become evenly distributed among
the remaining gum base ingredients.
[0023] In an aspect of the method, volatile components of the gum
base mixture are continuously removed during the extrusion process.
These volatile components include unwanted degradation products;
for example, degraded elastomer, elastomer solvent or plasticizer,
which occur in small amounts from the mixing process. Removal of
the volatile components helps eliminate undesirable off-notes from
the flavor of the chewing gum base. This can be accomplished, for
example, by pulling a vacuum on the extruder at selected locations.
If the degradation products are not removed periodically and are
allowed to mix with the base ingredients, they may become very
difficult to remove later.
[0024] In an aspect of the method, low and/or medium viscosity
ingredients are injected in a liquid state under pressure, using a
pump. The liquid state can be achieved by premelting an ingredient
such as polyvinyl acetate or wax, or by lowering the viscosity of a
fat or oil, using one or more heated feed tanks. The injection of a
liquid under pressure facilitates more precise metering and better
mixing and distribution of the low and medium viscosity
ingredients.
[0025] The invention has numerous advantages. First, chewing gum
base is produced in a continuous process. If desired, the output
can be used to supply a continuous chewing gum production line.
Second, the average residence time for gum base ingredients is
reduced from hours to minutes. Third, all of the necessary addition
and compounding steps can be performed in sequence using a single
continuous mixing apparatus. Fourth, an embodiment provides
improved metering and mixing of intermediate and low viscosity gum
base ingredients by adding these ingredients in the liquid state
under pressure. Fifth, the invention is effective for a wide range
of gum base compositions, including different gum base elastomers
and elastomer percentages, without requiring preblending or other
pretreatment of the elastomers. Sixth, the gum base can be produced
on demand, eliminating finished base inventory. This allows maximum
flexibility to react to market demands and formula changes.
[0026] The foregoing and other features and advantages of the
invention will become further apparent from the following detailed
description of the presently preferred embodiments, read in
conjunction with the accompanying examples and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 depicts a schematic representation of a twin screw
extruder set up for use in practicing the present invention.
[0028] FIG. 2 depicts a set of shearing disks used in the extruder
of FIG. 1.
[0029] FIG. 3 depicts a set of toothed elements used in the
extruder of FIG. 1.
[0030] FIG. 4 depicts a set of kneading disks used in the extruder
of FIG. 1.
[0031] FIG. 5 depicts a plurality of kneading disks, set up in a
helical fashion, to form kneading blocks.
[0032] FIGS. 6a-e depict schematic sequential representations of
gum base ingredients during the mixing process.
DETAILED DESCRIPTION OF THE DRAWINGS AND
PREFERRED EMBODIMENTS OF THE INVENTION
[0033] Pursuant to the present invention, chewing gum base can be
made in a continuous manner in a single extruder. In a preferred
embodiment, the extruder includes at least two mixing zones.
[0034] The chewing gum base made by the process of the present
invention can thereafter be made into conventional chewing gums,
including bubble gum, by conventional methods. The details of such
chewing gums and methods of production are well known and therefore
not repeated here. Of course, specialized chewing gum, such as
nonadhesive chewing gum and bubble gum, will use specialized gum
base formulas and ingredients. However, those gum base ingredients
can be combined using the processes herein described.
[0035] In general, a chewing gum composition typically comprises a
water-soluble bulk portion, a water-insoluble chewable gum base
portion and typically water-insoluble flavoring agents. The
water-soluble portion dissipates with a portion of the flavoring
agent over a period of time during chewing. The gum base portion is
retained in the mouth throughout the chew.
[0036] The water soluble portion of the chewing gum may include
softeners, bulk sweeteners, high intensity sweeteners, flavoring
agents and combinations thereof. Softeners are added to the chewing
gum in order to optimize the chewability and mouth feel of the gum.
The softeners, which are also known as plasticizers or plasticizing
agents, generally constitute between about 0.5-15% by weight of the
chewing gum. The softeners may include glycerin, lecithin, and
combinations thereof. Aqueous sweetener solutions such as those
containing sorbitol, hydrogenated starch hydrolysates, corn syrup
and combinations thereof, may also be used as softeners and binding
agents in chewing gum.
[0037] Bulk sweeteners constitute between 5-95% by weight of the
chewing gum, more typically 20-80% by weight of the chewing gum and
most commonly 30-60% by weight of the chewing gum. Bulk sweeteners
may include both sugar and sugarless sweeteners and components.
Sugar sweeteners may include saccharide containing components
including but not limited to sucrose, dextrose, maltose, dextrin,
dried invert sugar, fructose, levulose, galactose, corn syrup
solids, and the like, alone or in combination. Sugarless sweeteners
include components with sweetening characteristics but are devoid
of the commonly known sugars. Sugarless sweeteners include but are
not limited to sugar alcohols such as sorbitol, mannitol, xylitol,
hydrogenated starch hydrolysates, maltitol, and the like, alone or
in combination.
[0038] High intensity sweeteners may also be present and are
commonly used with sugarless sweeteners. When used, high intensity
sweeteners typically constitute between 0.001-5% by weight of the
chewing gum, prefer-ably between 0.01-1% by weight of the chewing
gum. Typically, high intensity sweeteners are at least 20-times
sweeter than sucrose. These may include but are not limited to
sucralose, aspartame, salts of acesulfame, alitame, saccharin and
its salts, cyclamic acid and its salts, glycyrrhizin,
dihydrochalcones, thaumatin, monellin, and the like, alone or in
combination.
[0039] Combinations of sugar and/or sugarless sweeteners may be
used in chewing gum. The sweetener may also function in the chewing
gum in whole or in part as a water soluble bulking agent.
Additionally, the softener may also provide additional sweetness
such as with aqueous sugar or alditol solutions.
[0040] Flavoring agents should generally b present in the chewing
gum in an amount within the range of about 0.1-15% by weight of the
chewing gum, preferably between about 0.2-5% by weight of the
chewing gum, most preferably between about 0.5-3% by weight of the
chewing gum. Flavoring agents may include essential oils, synthetic
flavors or mixtures thereof including but not limited to oils
derived from plants and fruits such as citrus oils, fruit essences,
peppermint oil, spearmint oil, other mint oils, clove oil, oil of
wintergreen, anise and the like. Artificial flavoring agents and
components may also be used. Natural and artificial flavoring
agents may be combined in any sensorially acceptable fashion.
[0041] Optional ingredients such as colors, emulsifiers,
pharmaceutical agents and additional flavoring agents may also be
included in chewing gum.
[0042] The insoluble gum base generally comprises elastomers,
elastomer solvents, plasticizers, waxes, emulsifiers and inorganic
fillers. Plastic polymers, such as polyvinyl acetate, which behave
somewhat as plasticizers, are also often included. Elastomers may
include polyisobutylene, butyl rubber (isobutylene-isoprene
copolymer) and styrene butadiene rubber, as well as natural latexes
such as chicle. Elastomer solvents are often resins such as terpene
resins and ester gums. Plasticizers are typically fats and oils,
including tallow, hydrogenated and partially hydrogenated vegetable
oils, and cocoa butter. Commonly employed waxes include paraffin,
microcrystalline and natural waxes such as beeswax and
carnauba.
[0043] The gum base typically also includes a filler component. The
filler component may be calcium carbonate, magnesium carbonate,
talc, dicalcium phosphate or the like. The filler may constitute
between about 5 and about 60 percent by weight of the gum base.
Preferably, the filler comprises about 5 to about 50 percent by
weight of the gum base.
[0044] Emulsifiers, which also sometimes have plasticizing
properties, include glycerol monostearate, lecithin and glycerol
triacetate. Further, gum bases may also contain optional
ingredients such as antioxidants, colors and flavors.
[0045] The insoluble gum base may constitute between about 5 to
about 80 percent by weight of the gum. More typically the insoluble
gum base comprises between 10 and 50 percent by weight of the gum
and most often about 20 to about 35 percent by weight of the
gum.
[0046] Pursuant to the present invention, the gum base is made
using a single extruder. As noted previously, preferably, the
extruder includes at least two mixing zones. As used herein, at
least "two mixing zones" means that the gum base is subjected to at
least two different mixing conditions in the extruder, e.g.,
distributive or dispersive. A variety of extruders are believed to
be adaptable for the present invention.
[0047] In an embodiment, the present invention is carried out on a
twin screw extruder such as depicted schematically in FIG. 1. The
twin screw extruder will be set up with several different feed
inlet locations where chewing gum base ingredients can be added.
The screws inside the barrel of the extruder are equipped with
different types of elements along the length of the screws. The
different sections are some times referred to as processing
sections, and described by the type of elements employed in the
sections. Th barrel for the xtruder is typically divided into
regions that may be heated or cooled independent of other regions.
These heating regions normally coincide with processing sections,
depending on the lengths of the barrel zone sections and the
elements in the processing sections.
[0048] While different equipment manufacturers make different types
of elements, the most common types of elements include conveying
elements, compression elements, reverse elements, homogenizing
elements such as shearing disks and toothed elements, and kneading
disks and blocks. Conveying elements generally have flights
spiraling along the elements with wide gaps between the flights.
These elements are used at feed inlet sections to quickly move
material into the body of the extruder. Compression elements have
flights with a pitch that narrows as the material moves along the
flights. This results in compression and high pressure in the
forward direction, which is required to force material downstream
and through the other elements. Reverse elements have flights that
are angled opposite those of the conveying elements. The flights
rotate in a direction that would force material upstream. These
elements provide a high back pressure and slow down movement of the
material through the extruder. Of course, the extruded material
still works its way opposite the flights to move downstream through
the reverse elements. A reverse helical arrangement of kneading
blocks can accomplish a similar result.
[0049] Shearing disks, as their name implies, impart high shearing
forces on the material in the extruder, resulting in highly
dispersive mixing. In a twin screw extruder, the shearing disks
opposite one another on the two different screws have close fitting
disk/slot elements, as depicted in FIG. 2. Toothed elements, as
depicted in FIG. 3, have gear-like teeth that oppose a cylindrical
spacer shaft on the other screw. Toothed elements impart highly
distributive mixing. Often the toothed elements are made in matched
sets, with a cylindrical shaft portion and a toothed portion as one
unit. Kneading disks, as shown in FIG. 4, have an elliptical shape,
and produce a kneading action in the material passing through the
extruder. Often a plurality of kneading disks will be placed next
to each other in a helical arrangement, as shown in FIG. 5,
referred to as kneading blocks.
[0050] Highly distributive mixing can also be accomplished using
reverse conveyance elements that have portions missing from the
flights to allow flow counter to the direction of compression.
These missing portions may be arranged as a groove through the
flights cut parallel to the length of the element. Also, kneading
blocks followed by reverse conveyance elements, to build up high
back pressure, also produce highly distributive mixing.
[0051] These elements, and other elements useful in twin screw
extruders, are well known in the art and are commercially
available. The elements are often specifically designed for the
different types of commonly available twin screw extruders, which
include co-rotation, counter rotation, intermeshing and tangential
twin screw extruders. Elements intended for similar functions will
vary in design depending on the type of extruder for which they are
intended.
[0052] One specific type of element for a specific brand of
extruder is a non-intermeshing polygon element sold by the Farrel
Corporation, 25 Main Street, Ansonia, Conn. 06401, for the
Farrel-Rockstedt co-rotating twin screw extruder. It is believed
that the non-intermeshing polygons produce dispersive mixing.
[0053] In embodiments of the invention, the dispersive mixing
disentangles the elastomers with a minimum amount of degradation of
the polymer chains. Thus, while dispersive mixing will inevitably
reduce the molecular weight of the polymer, it may be preferable to
control the dispersive mixing operation to minimize this molecular
weight reduction. Preferably, the average molecular weight will not
be reduced below the average molecular weight of the same polymers
mixed into gum base using conventional processes. However, a
controlled amount of molecular weight reduction may be desirable to
optimize the chewing texture of the final product.
[0054] An adequate dispersive mixing will produce a smooth, rubbery
fluid, with no detectable lumps of rubber. If only a few lumps of
rubber are present they may be screened out or dispersed during
subsequent mixing steps. However, if the number or size of lumps is
excessive, or the processed elastomers and fillers are in the form
of an agglomeration or grainy mass, the dispersive mixing applied
is inadequate.
[0055] The distributive mixing should be sufficient to produce a
homogeneous gum base, rather than a material that appears to be
"sweating", or that has a marbled or swiss cheese texture. In the
preferred embodiment of the invention, the highly distributive
mixing is sufficient to incorporate plasticizers, particularly
fats, oils and waxes, to the same degree these plasticizers are
incorporated in conventional chewing gum base manufacturing
processes.
[0056] As shown in FIG. 1, for practicing an embodiment of the
invention, a twin screw extruder 10 is set up with a first feed
inlet location 12 adjacent a first processing section 21 fitted
with conveying elements 31, conveying and compression elements 32
and compression elements 35. The second processing section 23 is
equipped with a combination of toothed elements 33, as depicted in
FIG. 3, and several sets of shearing disks 34, as depicted in FIG.
2. At the end of the second processing section 23 the extruder 10
is equipped with a port 16 which is connected to a vacuum source
(not shown). The third processing section 24 contains additional
conveying elements 31, conveying and compression elements 32 and
compression elements 35. A second feed inlet 13 is provided in the
extruder adjacent this second set of conveying elements 31, for
feeding additional gum base ingredients into the third processing
section 24. Feed inlet 13 allows for the addition of powdered
ingredients as well as liquid ingredients from pump 41. The fourth
processing section 25 is fitted with kneading disks 36. At the
beginning of the fifth processing section 26, the twin screw
extruder 10 has another inlet 15 connected to a pump 43 and a feed
inlet 14 in the form of a port connected to a side feeder 42, which
may be a single or twin screw extruder, or even a gear pump which
can generate high pressure. The fifth processing section 26 is
fitted with conveying elements 31, conveying and compression
elements 32 and compression elements 35, which force the gum base
ingredients into the sixth and final processing section 28. Section
28 contains two sets of toothed elements 33, followed by reverse
elements 39 and shearing disks 34. After passing through the
shearing disks 34, the gum base ingredients exit the extruder
10.
[0057] It may be preferable to heat some of the ingredients, either
to melt them or lower their viscosity. As shown in FIG. 1, the
extruder 10 may be set up with heated tanks 44 and 45, connected
respectively to pumps 41 and 43, for this purpose. Other commonly
used equipment, such as equipment to monitor the temperature and
heat or cool the extruder, is not shown in FIG. 1. The equipment
will also include conventional weighing and feeding devices for
continuously adding granulated or powdered ingredients at a
controlled, monitored rate.
[0058] It will be understood that FIG. 1, as a schematic
representation, shows the various components in their respective
order from the standpoint of flow through the extruder 10.
Typically the screws are mounted in a horizontal side-to-side
position and feed inlets, especially those open to the atmosphere
like the inlet 12 and 13, are placed vertically above the
screws.
[0059] While the arrangement of FIG. 1 may be desirable for
particular gum bases outlined in the examples below, other
arrangements may be preferred for other gum bases. FIG. 1 depicts
an extruder with three general areas of ingredient addition and six
processing sections. For some gum bases, two, four or more
ingredient feeding sections may be used, with different numbers of
processing sections. FIG. 1 also depicts the use of one set each of
long conveying elements 31, conveying and compression elements 32
and compression elements 35 in the first processing section 21, a
short set of conveying and compression elements 32 in sections 24
and 26, and a short set of conveying elements 31 and compression
elements 35 in section 26. In reality, one, two or more elements of
different types and length may be used in these sections. FIG. 1
also depicts one set of toothed elements 33 and three sets of
shearing disks 34 in section 23, but different numbers of these
elements, or different elements all together, may be used. Likewise
in sections 25 and 28, different types of elements that produce
distributive mixing may be used, dependent on the gum ingredients
being mixed in those sections and the type of extruder being
used.
[0060] As has been previously noted, other extruders and methods
can be used to make gum base in a continuous manner using a single
extruder.
[0061] U.S. patent application Ser. No. 08/136,589, filed on Oct.
14, 1993 and entitled: "Continuous Gum Base Manufacturing Using a
Mixing Restriction Element," the disclosure of which is hereby
incorporated by reference, discloses extruders including mixing
restriction elements. The disclosed extruders can be used to create
gum base pursuant to the present invention.
[0062] In a preferred embodiment, a high efficiency continuous
mixer is used. A high efficiency mixer is one which is capable of
providing thorough mixing over a relatively short distance of
length of the mixer. This distance is expressed as a ratio of the
length of a particular active region of the mixer screw, which is
composed of mixing elements, divided by the maximum diameter r of
the mixer barrel in this active region. In a preferred embodiment,
the L/D is less than approximately 40 and most preferably, less
than approximately 25 L/D.
[0063] An example of a single high efficiency mixer that can be
used is a blade-and-pin mixer. The blade-and-pin mixer uses a
combination of selectively configured rotating mixer blades and
stationary barrel pins to provide efficient mixing over a
relatively short distance. A commercially available blade-and-pin
mixer is the Buss kneader, manufactured by Buss AG in Switzerland,
and available from Buss America, located in Bloomingdale, Ill.
[0064] Blade-and-pin mixers and methods of using same are disclosed
in U.S. patent application Ser. No. 08/362,254, filed on Dec. 22,
1994, and entitled: "Total Chewing Gum Manufacture Using High
Efficiency Continuous Mixing," the disclosure of which is
incorporated herein by reference. The extruders and mixers
disclosed therein can be used to create gum base pursuant to the
present invention.
[0065] FIGS. 6a-e represent the state of various gum base
ingredients as they are, in an embodiment, compounded into chewing
gum base. At the beginning, as shown in FIG. 6a, the high molecular
weight elastomer 51 and medium molecular weight elastomer 52 are
both in the form of granules or particles in which the elastomer
molecules are tightly bound together. The filler 53 is in
particulate form, but may not be homogeneously mixed with the
elastomers 51 and 52. The elastomer solvent 54 may be pr sent in
the form of droplets. As mixing begins, depicted in FIG. 6b, the
elastomer solvent 54 becomes associated with the elastomers 51 and
52. With the presence of the filler 53, elastomer solvent 54 and
heat, the granules begin to come apart into individual elastomer
molecules. Also, the filler 53 becomes more evenly distributed, and
may have its particle size reduced. As the process continues, the
elastomers 51 and 52 become disentangled, as shown in FIG. 6c. This
disentangling is the result of subjecting the elastomers 51 and 52
to highly dispersive mixing.
[0066] After this step, the lower viscosity ingredients, such as
polyvinyl acetate 55, may be added, as shown in FIG. 6d. Initially,
this material will also be in discrete particles, or droplets as it
melts. Further mixing and further ingredient additions, such as
waxes 56 and emulsifiers 57, are subjected to distributive mixing,
as depicted in FIG. 6e. Continued highly distributive mixing
produces a homogeneous chewing gum base, wherein discrete particles
or droplets are not detectable by sensory perception.
[0067] The elastomer may be added at the first feed inlet 12 along
with elastomer solvent such as resins and the filler. However,
especially lower weight elastomers may be added at least partially
at the second feed inlet 13. Portions of the filler may also be
added at the second feed inlet 13. Polyvinyl acetate may be added
via a powder feeder or the single screw extruder 42, or a twin
screw extruder or gear pump, at the feed inlet port 14, while
melted fats and waxes and oils are added at the last feed inlet 15.
This will result in the filler, elastomer and plasticizer being
subjected to highly dispersive mixing first before lower viscosity
ingredients are added. The toothed elements 38, r verse elements 39
and shearing disk 40 after f ed inlet 15 result in highly
distributive mixing of all of the low viscosity gum base
ingredients with the other gum base ingredients.
[0068] A small scale extruder that can be used is a model LM 30.34
counter-rotational, intermeshing and tangential twin screw extruder
from Leistritz, Nurenberg, Germany.
[0069] By way of example, other twin screw extruders that can be
used include the Japan Steel Works Model TEX30HSS32.5PW-2V
intermeshing co- and counter-rotating twin screw extruder, also
known as the Davis Standard D-Tex Model, distributed by Crompton
& Knowles Corporation, #1 Extrusion Dr., Pawcatuck, Conn.
06379, and the co-rotating or counter-rotating intermeshing twin
screw extruders from Werner & Pfleiderer Corporation, 663 E.
Crescent Ave., Ramsey N.J. 07446. It may be preferable to have a
long barrel length. A Werner & Pfleiderer co-rotational twin
screw extruder can extend to a length to diameter (L/D) ratio of
58. The Japan Steel Works Model TEX30HSS32.5PW-2V extruder may be
equipped to have an L/D of 48.
EXAMPLE 1
[0070] Gum base was made on a continuous basis using a Leistritz
model LSM 30.34 counter-rotational, intermeshing and tangential
extruder in intermeshing mode with a barrel diameter of 30.3 mm set
up with the following elements (given in order proceeding from
first f ed inlet to the output end of the extruder and using the
Leistritz part designation for each element):
[0071] FF-1-30-120 (conveying element)
[0072] KFD-1-30/20-120 (conveying and compression element)
[0073] FD-3-30-120 (compression element)
[0074] ZSS-2-R4 (toothed element)
[0075] ZSS-2-R4
[0076] KS (shearing disk)
[0077] KS
[0078] FF-1-30-120
[0079] KFD-1-30/20-120
[0080] FD-3-30-120
[0081] ZSS-2-R4
[0082] ZSS-2-R4
[0083] ZSS-2-R4
[0084] KS
[0085] The die at the end of the extruder had a 1 mm hole.
[0086] The extruder had two feeding zones, each one adjacent the
FF-1-30-120 conveying elements. A powder blend of ground butyl
rubber, calcium carbonate and terpene resin at a ratio of 6:23:17
was fed at a rate of 3 kg/hr in the first feed zone.
Polyisobutylene at 50-80.degree. C. was also fed at the first feed
zone at a rate of 0.39 kg/hr. A powder blend of 5 parts glycerol
monostearate, 8 parts hydrogenated cottonseed oil, 5 parts
hydrogenated soybean oil, 3 parts high molecular weight polyvinyl
acetate and 21 parts low molecular weight polyvinyl acetate was fed
into the second feeding zone at a rate of 2.74 kg/hr, along with a
blend of 3 parts partially hydrogenated soybean oil and 3 parts
lecithin heated to 30.degree. C. and fed at a rate of 0.4 kg/hr.
The temperature of the extruder housing during operation was as
follows:
2 Zone 1 2 3 4 5 6 7 Die Set 90.degree. C. 90.degree. C. 95.degree.
C. 130.degree. C. 130.degree. C. 130.degree. C. 110.degree. C.
Tempera- ture Actual 90.degree. C. 99.degree. C. 95.degree. C.
130.degree. C. 130.degree. C. 130.degree. C. 110.degree. C.
115.degree. C. Tempera- (est.) (est.) ture
[0087] The extruder was operated at a speed of 100 rpm and drew 9
amps. A chewing gum base was produced which had no rubber particles
or segregated oil. However, some of the polyvinyl acetate was not
fully incorporated. This would be incorporated as the base was used
to make chewing gum, or if desired, could be eliminated by using a
single screw extruder as a side feeder/pre-melter for the polyvinyl
acetate.
EXAMPLE 2
[0088] The same extruder set up and temperatures as used in Example
1 were used to continuously make another chewing gum base. A powder
blend of ground butyl rubber and calcium carbonate at a ratio of
15;31 was fed into the first zone at a rate of 3 kg/hr, along with
polyisobutylene heated to 50-80.degree. C. and fed at a rate of
2.08 kg/hr. A powder blend of 22 parts low molecular weight
polyvinyl acetate, 13 parts hydrogenated cottonseed oil, 3 parts
glycerol monostearate and 13 parts hydrogenated soybean oil was fed
into the second feed inlet at a rate of 6.63 kg/hr, along with
partially hydrogenated soybean oil heated to 30-60.degree. C. and
fed at a rate of 1.3 kg/hr. The extruder was operated at 100 rpm,
and drew 7-8 amps. A complete chewing gum base was prepared,
although it was not as well mixed as the base of Example 1 and
there were difficulties in material accumulating at the second feed
zone.
EXAMPLE 3
[0089] An Leistritz Model 30.34 twin screw extruder is setup as
shown in FIG. 1, with the following elements (the numbers to the
left in parenthesis represent reference numbers from FIG. 1):
[0090] (31) FF-1-30-120
[0091] (32) KFD-1-30/20-120
[0092] (35) FD-3-30-120
[0093] (33) ZSS-2-R4
[0094] (34) KS
[0095] (34) KS
[0096] (34) KS
[0097] (31) FF-1-30-120
[0098] (32) KFD-1-30/20-60
[0099] (35) FD-3-30-120
[0100] (36) 18 kneading disks, stacked in 2 sets of 2 and 4 sets of
3, with a 90.degree. set off between each set.
[0101] (31) FF-1-30-60
[0102] (32) KFD-1-30/20-60
[0103] (35) FD-3-30-30
[0104] (33) ZSS-2-R4
[0105] (33) ZSS-2-R4
[0106] (39) FF-1-30-30 (set up for reverse operation)
[0107] (34) KS
[0108] The overall length of these elements is 1060 mm, giving a
L/D for a 30.3 mm barrel of about 35.
[0109] The following ingredients are added at the following rates
to the extruder 10 at the locations specified. The rates listed are
for steady state operation.
3 FEED INLET INGREDIENTS % BY WEIGHT LOCATION Terpene resin
(123.degree. F. melting 8.390 12 point) Terpene resin (85.degree.
F. melting 8.257 12 point) Cocoa powder (<75 micron w t 0.599 12
particle size) Ground isobutylene-isoprene 8.390 12 copolymer
(120,000-150,000 MW, 2-7 mm diameter particle size) Calcium
carbonate (<12 20.908 12 micron particle size) Polyisobutylene
(12,000 5.860 13 M.W.) (heated to 100.degree. C.) Polyvinyl acetate
2.663 14 (50,000-80,000 M.W.) Polyvinyl acetate (25,000 21.309 14
M.W.) Glycerol monostearate 4.794 15 Hydrogenated soybean oil 4.528
15 Lecithin 3.329 15 Hydrogenated cottonseed oil 7.724 15 Partially
hydrogenated 3.196 15 cottonseed oil BHT 0.053 15
[0110] The total feed rate is 25 lb/hr. The temperature is
controlled so that the mixture is at about 115.degree.
C.-125.degree. C.
[0111] While the examples have been given for relatively small
scale operations, the process is readily scaled up. When using twin
screw extruders, scale up is accomplished by using a larger barrel
diameter, such as 6 inches, and a longer length, but maintaining
the same L/D ratio. For an L/D of 45, a 6 inch barrel would be 22.5
feet in length. If larger machines generate more heat than can
easily be removed, the rpm of the extruder may need to be reduced,
or cooled shafts and mixing elements could be used. Also, by
putting in some of the resin at the first feed zone, the heat
generated during mixing should be reduced.
[0112] When conducting the experiment relating to Example 1, the
polyisobutylene was originally added at the second feed inlet. This
was possible during startup, but when the blend of fats and
polyvinyl acetate were also added, the fats melted and lubricated
the screws so that they no longer drew in the polyisobutylene. This
is why the polyisobutylene is introduced at the first feed zone in
Example 1.
[0113] In Examples 1 and 2, since the butyl rubber was ground
before it was used, a portion of the filler and the ground butyl
rubber were premixed (at a ratio of filler to butyl rubber of 1:3)
to help keep the ground butyl rubber in a form that allowed it to
be fed into the extruder as a powder blend. This filler was
included in the overall ratios cited in the examples.
EXAMPLE NO. 4
[0114] A BUSS Kneader having a 100 mm barrel diameter and an
overall active mixing L/D of 15 was used to manufacture a gum base.
The mixer included an initial feed section and four mixing
sections. The sections include four possible large feed ports which
can be used to add major (e.g. solid) ingredients to the mixer. The
third mixing section is also configured with two smaller liquid
injection ports which are used to add liquid ingredients. The
liquid injection ports include special barrel pins formed with
hollow centers. Barrel pins are preferably present in most or all
of the available locations, in all three rows. The first section of
the mix r provides a dispersive mixing zone and the remaining
sections provide a distributive mixing zone.
[0115] The presently preferred configuration of the mixing screw
for most gum base products is as follows. The initial feed section
is configured with about 1-{fraction (1/3)} L/D of low shear
elements. The L/D of the initial feed section is not counted as
part of the overall active mixing L/D of 15, discussed above,
because its purpose is merely to convey ingredients into the mixing
sections.
[0116] The first mixing section is configured with two low shear
mixing elements followed by two high shear elements. The two low
shear mixing elements contribute about 1-1/3 L/D of mixing, and the
two high shear mixing elements contribute about 1-1/3 L/D of
mixing. The first mixing section has a total mixing L/D of about
3.0, including the end part covered by a 57 mm restriction ring
assembly with cooperating on-screw elements.
[0117] The restriction ring assembly with cooperating on-screw
elements straddling the end of the first mixing section and the
start of the second mixing section, have a combined L/D of about
1.0, part of which is in the second mixing section. Then, the
second section is configured with three low shear mixing elements
and 1.5 high shear mixing elements. The three low shear mixing
elements contribute about 2.0 L/D of mixing, and the 1.5 high shear
mixing elements contribute about 1.0 L/D of mixing. This section
has a total mixing L/D of about 4.0.
[0118] Straddling the end of the third mixing section and the start
of the fourth mixing section is another 60 mm restriction ring
assembly with cooperating on-screw elements having an L/D of about
1.0. Then, the remainder of the fourth mixing section is configured
with five low shear mixing elements contributing a mixing L/D of
about 3{fraction (1/3)}. This section also has a total mixing L/D
of about 4.
[0119] A mixture of 27.4% dusted ground butyl rubber (75% butyl
rubber dusted with 25% calcium carbonate), 14.1% lower softening
terpene resin (softening point=85.degree. C.), 14.4% higher
softening terpene resin (softening point=125.degree. C.) and 44.1%
calcium carbonate was fed at 24.6 lb/hr into the first large feed
port.
[0120] A mixture of 73.5% low molecular weight polyvinyl acetate,
9.2% high molecular weight polyvinyl acetate, 8.6 lower softening
terpene resin and 8.7% higher softening terpene resin was fed at
17.4 lb/hr into the second large feed port. Polyisobutylene was
also added at 3.5 lb/hr into this port.
[0121] A fat mixture, preheated to 83.degree. C., was injected into
the liquid injection ports in the third mixing zone at a total rate
of 14.5 lb/hr, with 50% of the mixture being fed through each port.
The fat mixture included 0.2% BHT, 2.5% cocoa powder, 31.9%
hydrogenated cottonseed oil, 19.8% glycerol monostearate, 18.7%
hydrogenated soybean oil, 13.7% lecithin, and 13.2% partially
hydrogenated cottonseed oil.
[0122] Mixing was continued through the fourth zone with no further
ingredient additions to yield a gum base which was used immediately
to manufacture a peppermint flavored sugar gum.
[0123] The four section temperatures were set (in .degree. F.) at
350, 350, 110 and 25, respectively. The mixing screw temperature
was set at 101.degree. F. The temperatures of product in each of
the four sections were measured at steady state (in .degree. F.) as
320, 280, 164, and 122, respectively. The screw rotation was 63
rpm.
[0124] It should be appreciated that the methods of the present
invention are capable of being incorporated in the form of a
variety of embodiments, only a few of which have been illustrated
and described above. The invention may be embodied in other forms
without departing from its spirit or essential characteristics. It
will be appreciated that the addition of some other ingredients,
process steps, materials or components not specifically included
will have an adverse impact on the present invention. The best mode
of the invention may therefore exclude ingredients, process steps,
materials or components other than those listed above for inclusion
or use in the invention. However, the described embodiments are to
be considered in all respects only as illustrative and not
restrictive, and the scope of the invention is, therefore,
indicated by the appended claims rather than by the foregoing
description. All changes which come within the meaning and range of
equivalency of the claims are to be embraced within their
scope.
* * * * *