U.S. patent application number 09/788801 was filed with the patent office on 2001-07-19 for chewing gum sbr.
This patent application is currently assigned to The Goodyear Tire & Rubber Company. Invention is credited to Hill, Valerie Anne, Schulz, Gerald Owen.
Application Number | 20010008643 09/788801 |
Document ID | / |
Family ID | 23867198 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008643 |
Kind Code |
A1 |
Schulz, Gerald Owen ; et
al. |
July 19, 2001 |
Chewing gum SBR
Abstract
Conventional SBR does not have the soft and smooth chew
characteristics needed in chewing gum base for soft chew
applications. Conventional SBR typically also has undesirable odor
and taste characteristics that have generally limited its use in
chewing gum base formulations. However, there is a desire to use
SBR in such applications because it is relatively inexpensive. The
present invention also specifically discloses a process for
synthesizing styrene-butadiene rubber that is particularly useful
in manufacturing chewing gum base for soft chew applications which
comprises copolymerizing about 1 phm to about 12 phm styrene and
about 88 phm to about 99 phm of 1,3-butadiene in an aqueous
emulsion, wherein said copolymerization is conducted at a
temperature which is within the range of about 1.degree. C. to
about 20.degree. C., and wherein said copolymerization is initiated
with an initiator system which is comprised of (a) a free radical
generator, (b) a reducing agent selected from the group consisting
of ascorbic acid, isoascorbic acid, and ascorbic acid derivatives
having the structural formula: 1 wherein R is an alkyl group
containing from 1 to 30 carbon atoms, and (c) a water-soluble metal
salt of iron, copper, cobalt, nickel, tin, titanium, vanadium,
manganese, chromium or silver.
Inventors: |
Schulz, Gerald Owen; (Stow,
OH) ; Hill, Valerie Anne; (Akron, OH) |
Correspondence
Address: |
The Goodyear Tire & Rubber Company
Department 823
1144 East Market Street
Akron
OH
44316-0001
US
|
Assignee: |
The Goodyear Tire & Rubber
Company
|
Family ID: |
23867198 |
Appl. No.: |
09/788801 |
Filed: |
February 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09788801 |
Feb 19, 2001 |
|
|
|
09470336 |
Dec 22, 1999 |
|
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|
Current U.S.
Class: |
426/3 ; 426/573;
426/6; 520/1 |
Current CPC
Class: |
A23G 4/08 20130101; Y10S
526/915 20130101; A23G 4/06 20130101; A23G 4/064 20130101 |
Class at
Publication: |
426/3 ; 426/6;
426/573; 520/1 |
International
Class: |
A23G 003/30 |
Claims
What is claimed is:
1. A process for synthesizing styrene-butadiene rubber that is
particularly useful in manufacturing chewing gum which comprises
copolymerizing styrene and 1,3-butadiene in an aqueous emulsion,
wherein said copolymerization is conducted at a temperature which
is within the range of about 1.degree. C. to about 70.degree. C.,
and wherein said copolymerization is initiated with an initiator
system which is comprised of (a) a free radical generator, (b) a
reducing agent selected from the group consisting of ascorbic acid,
isoascorbic acid, and ascorbic acid derivatives having the
structural formula: 7wherein R is an alkyl group containing from 1
to 30 carbon atoms, and (c) a water-soluble metal salt of iron,
copper, cobalt, nickel, tin, titanium, vanadium, manganese,
chromium or silver.
2. A process for synthesizing styrene-butadiene rubber that is
particularly useful in manufacturing chewing gum base for soft chew
applications which comprises copolymerizing about 1 phm to about 12
phm styrene and about 88 phm to about 99 phm of 1,3-butadiene in an
aqueous emulsion, wherein said copolymerization is conducted at a
temperature which is within the range of about 1.degree. C. to
about 20.degree. C., and wherein said copolymerization is initiated
with an initiator system which is comprised of (a) a free radical
generator, (b) a reducing agent selected from the group consisting
of ascorbic acid, isoascorbic acid, and ascorbic acid derivatives
having the structural formula: 8wherein R is an alkyl group
containing from 1 to 30 carbon atoms, and (c) a water-soluble metal
salt of iron, copper, cobalt, nickel, tin, titanium, vanadium,
manganese, chromium or silver.
3. A chewing gum base, comprising: (1) about 5 weight percent to
about 95 weight percent styrene-butadiene rubber, wherein said
styrene-butadiene rubber has a bound styrene content of about 1
weight percent to about 10 weight percent, and wherein said
styrene-butadiene rubber has a RPA t.sub.80 of at least 0.060
minutes; (2) about 0 weight percent to about 75 weight percent of
an elastomer plasticizer selected from the group consisting of
natural rosin esters and synthetic terpene resins; (3) about 1
weight percent to about 65 weight percent of a filler material; and
(4) a gum base stabilizer.
4. A chewing gum which comprises: (1) about 5 weight percent to
about 95 weight percent styrene-butadiene rubber, wherein said
styrene-butadiene rubber has a bound styrene content of about 1
weight percent to about 10 weight percent, and wherein said
styrene-butadiene rubber has a RPA t.sub.80 of at least 0.060
minutes; (2) about 0 weight percent to about 75 weight percent of
an elastomer plasticizer selected from the group consisting of
natural rosin esters and synthetic terpene resins; (3) about 1
weight percent to about 65 weight percent of a filler material; and
(4) a gum base stabilizer, (5) a sweetener, and (6) a flavor.
5. A gum base as specified in claim 3 wherein said gum base is
substantially free of sulfur containing compounds.
6. A chewing gum as specified in claim 4 wherein said chewing gum
is substantially free of sulfur containing compounds.
7. A gum base as specified in claim 5 wherein said gum base
contains from about 10 weight percent to about 70 weight percent of
the styrene-butadiene rubber.
8. A gum base as specified in claim 5 wherein said gum base
contains from about 15 weight percent to about 45 weight percent of
the styrene-butadiene rubber.
9. A gum base as specified in claim 7 wherein said gum base
contains from about 5 to about 45 weight percent of the elastomer
plasticizer.
10. A gum base as specified in claim 7 wherein said gum base
contains from about 10 to about 30 weight percent of the elastomer
plasticizer.
11. A gum base as specified in claim 10 wherein the elastomer
plasticizer is a natural rosin ester.
12. A gum base as specified in claim 10 wherein the elastomer
plasticizer is a synthetic terpene resin.
13. A gum base as specified in claim 12 wherein said gum base is
further comprised of up to 30 weight percent of a wax selected from
the group consisting of natural waxes, synthetic waxes, petroleum
waxes, and mixtures thereof.
14. A gum base as specified in claim 13 further comprising between
0.5 and 40 weight percent of a softener selected from the group
consisting of tallow, hydrogenated tallow, hydrogenated and
partially hydrogenated vegetable oils, cocoa butter, glycerol
monostearate, glycerol triacetate, lecithin, monoglycerides,
diglycerides, triglycerides, fatty acids, and mixtures thereof.
15. A gum base as specified in claim 14 wherein the filler material
comprises one or more materials selected from the group consisting
of magnesium carbonate, calcium carbonate, ground limestone,
magnesium silicate, aluminum silicate, clay, alumina, talc,
titanium oxide, monocalcium phosphate, dicalcium phosphate,
tricalcium phosphate, cellulose polymers, wood and mixtures
thereof.
16. A gum base as specified in claim 15 wherein the gum base
stabilizer is a tocopherol mixture that comprises 12-15% by weight
alpha tocopherol, 63-65% by weight gamma tocopherol and 23-26% by
weight delta tocopherol.
17. A process as specified in claim 2 wherein said copolymerization
is short-stopped by the addition of said reducing agent.
18. A process as specified in claim 17 wherein the reducing agent
is isoascorbic acid.
19. A process as specified in claim 18 wherein the ratio of the
isoascorbic acid to the free radical generator is maintained within
the range of about 0.3:1 to about 0.8:1 throughout the
copolymerization.
20. A process as specified in claim 19 wherein the polymerization
temperature is within the range of about 1.degree.C. to about
10.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] Today ordinary chewing gums and bubble gums generally
utilize as their gum base one or a combination of two or more
natural or synthetic elastomers. The gum base that is selected
provides the chewing gum with its masticatory properties. A chewing
gum base is normally admixed with sugars or synthetic sweeteners,
perfumes, flavors, plasticizers, and fillers; and then milled and
formed into sticks, sheets, or pellets. Cottonseed oil is sometimes
also added to give the gum softness. Styrene butadiene rubber (SBR)
is a synthetic elastomer that is widely used as a gum base in
chewing gums. However, SBR is not widely used in manufacturing soft
chew gums because it lacks the desired physical properties.
Polyisobutylene is widely used in manufacturing soft chew gums even
though it is much more expensive than SBR.
[0002] In any case, chewing gum compositions are typically
comprised of a water soluble bulk portion, a water insoluble
chewing 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 chewing
process.
[0003] The gum base includes a number of ingredients that are
subject to deterioration through oxidation during storage. The
insoluble gum base generally comprises elastomers, elastomer
plasticizers, waxes, fats, oils, softeners, emulsifiers, fillers,
texturizers and miscellaneous ingredients, such as antioxidants,
preservatives, colorants and whiteners. The compounds contain
carbon-carbon double bonds, such as fats, oils, unsaturated
elastomers and elastomer plasticizers, are susceptible to
oxidation. The gum base constitutes between 5-95% by weight of the
chewing gum composition, more typically 10-50% by weight of the
chewing gum, and more commonly 15-35% by weight of the chewing
gum.
[0004] Commonly used natural or artificial
antioxidants/preservatives include beta-carotenes, acidulants (e.g.
Vitamin C), propyl gallate, butylated hydroxyanisole (BHA), and
butylated hydroxytoluene (BHT). BHA and BHT are synthetic
antioxidants that most commonly used stabilize chewing gum
base.
[0005] U.S. Pat. No 4,489,099 discloses the use of Vitamin E in
combination with dilauryl thiodipropionate (DLTDP), as a stabilizer
for a styrene-butadiene rubber in chewing gum. U.S. Pat. No.
5,132,121, U.S. Pat. No. 5,200,213, and U.S. Pat. No. 5,270,060
disclose a use of 0.01-1.00% by weight of a tocopherol mixture
comprising 7-20% by weight alpha tocopherol, 45-75% by weight gamma
tocopherol and 18-32% by weight delta tocopherol to stabilize
chewing gum base.
SUMMARY OF THE INVENTION
[0006] There has been a long felt need in the chewing gum industry
for a styrene-butadiene rubber (SBR) that has the physical
properties needed for utilization in manufacturing chewing gum
having soft chew characteristics. This is because it is much less
expensive than other elastomers, such as polyisobutylene rubber,
that are normally used in such applications. However, conventional
SBR does not have the soft and smooth chew characteristics needed
in soft chew applications. Furthermore, conventional SBR typically
also has undesirable odor and taste characteristics that have
generally limited its use in chewing gum base formulations.
[0007] The present invention relates to a technique for
synthesizing SBR that can be used in manufacturing chewing gum base
for soft chew applications. This technique also improves the taste
and odor of the SBR which makes it generally more desirable for use
in all types of chewing gum. The technique used in this invention
to reduce taste and odor involves copolymerizing about 1 phm to
about 30 phm styrene and about 70 phm to about 99 phm of
1,3-butadiene in an aqueous emulsion, wherein said copolymerization
is conducted at a temperature which is within the range of about
1.degree.C. to about 70.degree. C., and wherein said
copolymerization is initiated with an initiator system which is
comprised of (a) a free radical generator, (b) a reducing agent
selected from the group consisting of ascorbic acid, isoascorbic
acid, and ascorbic acid derivatives having the structural formula:
2
[0008] wherein R is an alkyl group containing from 1 to 30 carbon
atoms, and (c) a water-soluble metal salt of iron, copper, cobalt,
nickel, tin, titanium, vanadium, manganese, chromium or silver. It
is important for this process to be conducted without utilizing
sulfur containing initiator systems.
[0009] The present invention also specifically discloses a process
for synthesizing styrene-butadiene rubber that is particularly
useful in manufacturing chewing gum base for soft chew applications
which comprises copolymerizing about 1 phm to about 12 phm styrene
and about 88 phm to about 99 phm of 1,3-butadiene in an aqueous
emulsion, wherein said copolymerization is conducted at a
temperature which is within the range of about 1.degree. C. to
about 20.degree. C., and wherein said copolymerization is initiated
with an initiator system which is comprised of (a) a free radical
generator, (b) a reducing agent selected from the group consisting
of ascorbic acid, isoascorbic acid, and ascorbic acid derivatives
having the structural formula: 3
[0010] wherein R is an alkyl group containing from 1 to 30 carbon
atoms, and (c) a water-soluble metal salt of iron, copper, cobalt,
nickel, tin, titanium, vanadium, manganese, chromium or silver.
[0011] The present invention further discloses a chewing gum base,
comprising: (1) about 5 weight percent to about 95 weight percent
styrene-butadiene rubber, wherein said styrene-butadiene rubber has
a bound styrene content of about 1 weight percent to about 10
weight percent, and wherein said styrene-butadiene rubber has a RPA
t.sub.80 of at least 0.060 minutes; (2) about 0 weight percent to
about 75 weight percent of an elastomer plasticizer selected from
the group consisting of natural rosin esters and synthetic terpene
resins; (3) about 1 weight percent to about 65 weight percent of a
filler material; and (4) a gum base stabilizer.
[0012] The present invention also reveals a chewing gum which
comprises: (1) about 5 weight percent to about 95 weight percent
styrene-butadiene rubber, wherein said styrene-butadiene rubber has
a bound styrene content of about 1 weight percent to about 10
weight percent, and wherein said styrene-butadiene rubber has a RPA
t.sub.80 of at least 0.060 minutes; (2) about 0 weight percent to
about 75 weight percent of an elastomer plasticizer selected from
the group consisting of natural rosin esters and synthetic terpene
resins; (3) about 1 weight percent to about 65 weight percent of a
filler material; and (4) a gum base stabilizer, (5) a sweetener,
and (6) a flavor. It is highly desirable for the gum base and the
chewing gum to be substantially free of sulfur containing
compounds.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The SBR of this invention is synthesized by copolymerizing
styrene and 1,3-butadiene in an aqueous emulsion. The amount of
styrene charged into the aqueous emulsion will typically range from
about 1 phm (parts by weight per hundred parts by weight of
monomer) to about 35 phm and the amount of 1,3-butadiene charged
will be within the range of about 65 phm to about 99 phm. This will
result in the SBR having a bound styrene content which is within
the range of about 1 weight percent to about 30 weight percent (a
bound butadiene content of about 70 weight percent to about 99
weight percent. In some cases, higher ratios of styrene to
butadiene are desirable. For instance, SBR for chewing gum base
used in bubble gum can have a bound styrene content of as high as
about 50 percent. However, in cases where the SBR is being made for
soft chew gum base applications the amount of styrene charged will
be within the range of about 1 phm to about 13 phm. This will
result in the SBR having a bound styrene content that is within the
range of about 1 weight percent to about 12 weight percent. It is
preferred SBR used in soft chew gum base applications to have a
bound styrene content that is within the range of about 2 weight
percent to about 8 weight percent. It is typically more preferred
SBR used in soft chew gum base applications to have a bound styrene
content that is within the range of about 2 weight percent to about
5 weight percent. To attain such lower levels of bound styrene the
amount of styrene charged will, of course, be lowered to achieve
the desired bound monomer content.
[0014] The amount of monomers charged will typically be within the
range of about 20 weight percent to about 42 weight percent, based
upon the total weight of the aqueous emulsion (monomers, water,
soap, and initiator). Lower quantities of monomers can be charged,
but the resulting latex will have a low solids content and that is
not cost effective. The amount of monomers charged will more
typically be within the range of about 30 weight percent to about
40 weight percent, based upon the total weight of the aqueous
emulsion. It is generally preferred for the amount of monomers
charged to be within the range of about 35 weight percent to about
38 weight percent, based upon the total weight of the aqueous
emulsion.
[0015] The amount of soap charged into the aqueous emulsion will
typically be within the range of about 1 phm to about 10 phm. It is
normally preferred for the soap to be used at a level of about 2
phm to about 8 phm. It is typically more preferred for the soap to
be used at a level of about 4 phm to about 6 phm.
[0016] It is important for the soap to be of food grade. For
instance, the soap can be a sodium or a potassium salt of various
animal or vegetable fats or waxes. Salts of fatty acids, such as
oleic acid, palmitic acid, steric acid, and linoleic acid are
preferred. For instance, the soap employed can be the sodium
oleate, potassium oleate, sodium palmitate, potassium palmitate,
sodium sterate, potassium sterate, sodium linoleate, potassium
linoleate, or a mixture of such salts.
[0017] Polymerization is initiated by charging an initiator system
into the aqueous emulsion polymerization medium. The initiator
system is comprised of (a) a free radical generator, (b) a reducing
agent selected from the group consisting of ascorbic acid,
isoascorbic acid, and ascorbic acid derivatives having the
structural formula: 4
[0018] wherein R is an alkyl group containing from 1 to 30 carbon
atoms, and (c) a water-soluble metal salt of iron, copper, cobalt,
nickel, tin, titanium, vanadium, manganese, chromium or silver.
[0019] The free radical generators that are utilized in the redox
initiator systems of this invention are well known to persons
skilled in the art. Some representative examples of suitable free
radical generators include the various peroxygen compounds such as
potassium persulfate, ammonium persulfate, benzoyl peroxide,
hydrogen peroxide, di-t-buty peroxide, dicumyl peroxide,
2,4-dichlorobenzoyl peroxide, decanoyl peroxide, lauroyl peroxide,
cumene hydroperoxide, p-menthane hydroperoxide, .alpha.-pinene
hydroperoxide, t-butyl hydroperoxide, acetyl acetone peroxide,
methyl ethyl ketone peroxide, succinic acid peroxide, dicetyl
peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxymaleic
acid, t-butyl peroxybenzoate, and the like; and the various alkyl
perketals, such as 2,2-bis-(t-butylperoxy)butane, ethyl
3,3-bis(t-butylperoxy)butyrate, 1,1-di-(t-butylperoxy) cyclohexane,
and the like.
[0020] The reducing agent utilized in the redox initiator systems
of this invention can be ascorbic acid or isoascorbic acid of the
structural formula: 5
[0021] or it can be an ascorbic acid derivative having the
structural formula: 6
[0022] wherein R is an alkyl group containing from 1 to 30 carbon
atoms. In most cases R will be an alkyl group containing from 10 to
20 carbon atoms. Ascorbic acid 6-palmitate is an example of such an
ascorbic acid derivative that is highly preferred. In fact, the
6-palmitate derivative of ascorbic acid is 2 to 3 times more
reactive than ascorbic acid or isoascorbic acid as a reducing agent
for lauroyl peroxide.
[0023] The water-soluble metal salt of iron, copper, cobalt,
nickel, tin, titanium, vanadium, manganese, chromium or silver can
be chosen from a wide variety of water soluble compounds. For
instance it can be copper (II) amine nitrate, copper (II)
metaborate, copper (II) bromate, copper (II) bromide, copper
perchlorate, copper (II) dichromate, copper (II) nitrate
hexahydrate, iron (II) acetate, iron (III) bromide, iron (III)
bromide hexahydrate, iron (II) perchlorate, iron (III) dichromate,
iron (III) formate, iron (III) lactate, iron (III) malate, iron
(III) nitrate, iron (II) oxalate, iron (II) sulfate pentahydrate,
cobalt (II) acetate, cobalt (II) benzoate, cobalt (II) bromide
hexahtdrate, cobalt (II) chloride, cobalt (II) fluoride
tetrahydride, nickel hypophosphite, nickel octanoate, tin tartrate,
titanium oxalate, vanadium tribromide, silver nitrate, and silver
fluosilicate. The metal can also be complexed with a compound, such
as ethylenediaminetetraacetic acid (EDTA) to make it highly soluble
in water. For instance, iron/EDTA complexes or cobalt/EDTA
complexes can be used.
[0024] The free radical generator will typically be used in an
amount that is within the range of about 0.01 phm to about 0.6 phm.
The free radical generator will more typically be used in an amount
that is within the range of about 0.05 phm to about 0.3 phm. The
free radical generator will preferably be used in an amount that is
within the range of about 0.1 phm to about 0.2 phm. The free
radical generator will more preferably be used at a level that is
within the range of about 0.14 phm to about 0.18 phm.
[0025] The reducing agent will typically be utilized in the
initiator system at a level that is within the range of about 0.01
phm to about 0.3 phm. The reducing agent will more typically be
employed at a level that is within the range of about 0.05 phm to
about 0.1 phm. The reducing agent will preferably be used at a
level that is within the range of about 0.05 phm to about 0.1
phm.
[0026] The weight ratio of reducing agent to the free radical
generator will normally be within the range of about 0.2:1 to about
0.8:1. The weight ratio of the reducing agent to the free radical
generator will preferably be within the range of about 0.3:1 to
about 0.7:1. The weight ratio of the reducing agent to the free
radical generator will most preferably be within the range of about
0.4:1 to about 0.6:1. It is critical for the weight ratio of the
reducing agent to the free radical generator to be less than 1:1
throughout the copolymerization because at levels of 1:1 and higher
the reducing agent will shortstop the copolymerization.
[0027] The water-soluble metal salt in the initiator system will
typically be present in the initiator system at a level that is
within the range of about 0.0005 phm to about 0.1 phm. The
water-soluble metal salt will more typically be present in the
initiator system at a level that is within the range of about 0.001
phm to about 0.01 phm. The water-soluble metal salt will preferably
be present in the initiator system at a level that is within the
range of about 0.002 phm to about 0.006 phm.
[0028] The copolymerization will be conducted at a temperature that
is within the range of about 1.degree. C. to about 70.degree. C.
Higher polymerization temperatures promote faster polymerization
rates and shorter polymerization times. However, lower
polymerization temperatures result in the SBR having a lower degree
of chain branching which is desirable for soft chew
characteristics. Thus, in synthesizing SBR for soft chew
applications the polymerization temperature will typically be kept
within the range of about 1.degree. C. to about 20.degree. C. In
synthesizing SBR for soft chew applications the polymerization
temperature will preferably be kept within the range of about
1.degree. C. to about 10.degree. C. In synthesizing SBR for soft
chew applications the polymerization temperature will more
preferably be kept within the range of about 2.degree. C. to about
5.degree. C.
[0029] The copolymerization can be conducted in the presence of
n-dodecyl mercaptan as a chain transfer agent to reduce the
molecular weight of the SBR. The amount of n-dodecyl mercaptan used
will depend upon the molecular weight that is desired for the SBR.
Larger quantities of n-dodecyl mercaptan cause greater reductions
in the molecular weight of the SBR. In any case, the amount of
n-dodecyl mercaptan used should be low enough that it is totally
depleted by the time the copolymerization is short-stopped.
[0030] The copolymerization will normally be short-stopped at a
monomer conversion of about 65 percent to about 70 percent. It is
preferred for the reducing agent to be used as the short-stop. The
reducing agent, for example isoascorbic acid, will act as a
short-stop when it is present at a weight ratio to the free radical
generator of at least 1:1. Thus, the copolymerization can be
short-stopped by simply adding additional reducing agent to the
aqueous emulsion.
[0031] After the polymerization has been short-stopped the SBR
latex can be coagulated using standard techniques, such as by the
addition of salt and acid to the emulsion. The SBR recovered can
then be dried using standard procedures, such as air-drying at an
elevated temperature. Then, the SBR can then be used in making
chewing gum base.
[0032] The SBR synthesized using the technique of this invention
has outstanding characteristics for use in making chewing gum base
because it is of low odor and low taste. This is by virtue of the
fact that it is essentially void of sulfur containing compounds. It
can also be made to have excellent physical characteristics for use
in making gum base for soft chew gum. This is exemplified by the
fact that such SBR has a RPA t.sub.80 of at least 0.060 minutes.
RPA t.sub.80 is the time to 80% of the final torque value as
measured on a Rubber Processing Analyzer. For soft chew gum the
longer the relaxation time the better. It is accordingly preferred
for the SBR to have a RPA t.sub.80 of at least 0.070 minutes. It is
even more preferred for the SBR to have a RPA t.sub.80 of at least
0.080 minutes.
[0033] After being recovered and dried the SBR can be used in
making chewing gum base. The chewing gum will incorporate the SBR
and, optionally, various other water-insoluble elastomeric
components that contribute to the elasticity of the chewing gum and
the longevity of the chew. This elastomeric component generally
constitute about 5 to about 95 weight percent of the gum base, more
preferably about 10 to about 70 weight percent of the gum base and
most preferably about 15 to about 45 weight percent of the gum
base. The elastomers in addition to the SBR can include synthetic
elastomers such as polyisobutylene, isobutylene-isoprene copolymer,
polyvinyl acetate, vinyl acetate-vinyl laurate copolymer, and
combinations thereof. The elastomers in addition to the SBR may
also include natural elastomers such as liquid latex, guayule,
jelutong, lechi caspi, perillo, massaranduba balata, massaranduba
chocolate, nispero, rosindinha, chicle, gutta hang kang and
combinations thereof.
[0034] In addition to the elastomers described above, the gum base
will typically include elastomer plasticizers, waxes,
softeners/emulsifiers, fillers/texturizers, colorants, a
stabilizer, and whiteners. Elastomer plasticizers constitute from
about 0 to about 75 percent by weight of the gum base, preferably 5
to 45 per cent by weight and most preferably 10 to 30 per cent by
weight. Elastomer plasticizers include natural rosin esters such as
glycerol ester of partially hydrogenated rosin, glycerol ester of
polymerized rosin, glycerol ester of partially dimerized rosin,
glycerol ester of rosin, pentaerythritol esters of partially
hydrogenated rosin, methyl and partially hydrogenated methyl esters
of rosin, pentaerythritol ester of rosin or mixtures thereof.
Elastomer plasticizers also include synthetics materials, such as
terpene resins derived from alpha-pinene, beta-pinene and/or
d-limonene.
[0035] The stabilizer included in the gum base can be BHT or any
other conventional stabilizer. It can also be a combination of
Vitamin E and dilauryl thiodipropionate as described in U.S. Pat.
No. 4,489,099. The stabilizer can also be a tocopherol mixture as
described in U.S. Pat. No. 5,270,060 which comprises 7-20% by
weight alpha tocopherol, 45-75% by weight gamma tocopherol and
18-32% by weight delta tocopherol. A commercially available
tocopherol blend that can be used is COVI-OX T-50, available from
the Henkel Corporation of Cincinnati, Ohio. COVI-OX T-50 contains
about 12.5% alpha tocopherol, about 63.9% gamma tocopherol, and
about 23.6% delta tocopherol, based on total tocopherol weight, in
a soybean oil diluent (70% tocopherol in 30% soybean oil). The
teachings of U.S. Pat. No. 4,489,099 and U.S. Pat. No. 5,270,060
are incorporated herein by reference in their entirety.
[0036] Waxes include synthetic (e.g. polyethylene and
Fischer-Tropsch waxes) and natural (candelilla carnauba, beeswax,
rice bran or mixtures thereof) and petroleum (e.g. microcrystalline
and paraffin). Waxes, when used, generally constitute up to 30
weight percent of the gum base.
[0037] Softeners/emulsifiers include tallow, hydrogenated tallow,
hydrogenated and partially hydrogenated vegetable oils, cocoa
butter, glycerol monostearate, glycerol triacetate, lecithin,
mono-, diglycerides and triglycerides, acetylated glycerides and
fatty acids (e.g. stearic, palmitic, oleic, linoleic and linolenic
acids) or mixtures thereof Softeners/emulsifiers generally
constitute between 0.5 and 40 weight per cent of the gum base.
[0038] Fillers/texturizers include magnesium and calcium carbonate,
ground limestone and silicate types such as magnesium and aluminum
silicate, clay, alumina, talc as well as titanium oxide,
monocalcium phosphite, dicalcium phosphite and tricalcium
phosphate, cellulose polymers such as ethyl, methyl and wood or
mixtures thereof. Preferably, the filler comprises about 1 to about
65 percent by weight of the gum base.
[0039] Colorants and whiteners include FD&C-type dyes and
lakes, fruit and vegetable extracts, titanium dioxide or mixtures
thereof.
[0040] The gum base is typically prepared by adding an amount of
the elastomer, elastomer plasticizers and filler to a heated sigma
blade mixer with a front to rear blade speed ratio of typically
2:1. The initial amounts of ingredients are determined by the
working capacity of the mixing kettle in order to attain a proper
consistency. After the initial ingredients have massed
homogeneously, the balance of the elastomer plasticizer, filler,
softeners, etc. are added in a sequential manner until a completely
homogeneous molten mass is attained. This can usually be achieved
in about one to about four hours, depending on the formulation. The
final mass temperature can be between 60.degree. C. and 150.degree.
C., more preferably between 80.degree. C. and 120.degree. C. The
completed molten mass is emptied from the mixing kettle into coated
or lined pans, extruded or cast into any desirable shape and
allowed to cool and solidify.
[0041] The water-soluble portion of the chewing gum may comprise
softeners, 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. Softeners, also known in the
art as plasticizers or plasticizing agents, generally constitute
between about 0.5 to about 15.0 percent by weight of the chewing
gum. Softeners contemplated by the present invention include
glycerin, lecithin, and combinations thereof. Further, aqueous
sweetener solutions such as those containing sorbitol, hydrogenated
starch hydrolysates, corn syrup and combinations thereof may be
used as softeners and binding agents in gum.
[0042] Bulk sweeteners constitute between 20-80% by weight of the
chewing gum and may include both sugar and sugarless sweeteners and
components. Sugar sweeteners may include saccharide-containing
components including but not limited to sucrose, maltose, dextrin,
dried invert sugar, levulose, galactose, corn syrup solids, and the
like, alone or in combination. The sugar can also be a
monosaccharides of 5 or 6 carbon atoms, such as arabinose, xylose,
ribose, glucose, mannose, galactose, fructose, dextrose, or sorbose
or mixtures of two or more of the foregoing monosaccharides,
disaccharides, for example, sucrose such as cane or beet sugar,
lactose, maltose or cellobiose; polysaccharides, such as partially
hydrolyzed starch or dextrin.
[0043] 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. Some
additional examples of artificial sweeteners which may be employed
include sodium, calcium or ammonium saccharin salts, free saccharin
and, dihydrochalcones, dipotassium glycyrrhizin, glycyrrhizic acid
ammonium salt, L-aspartyl-L-phenylalanine methyl ester (aspartame),
the sodium or potassium salt of
3,4-dihydro-6-methyl-1,2,3-oxathiazine-4-one-2,2-dioxid- e
(Ace-sulfame-K), as well as Stevia rebaudiana (Stevioside),
Richardella dulcifica (Miracle Berry), Diascoreophyllum cumminsii
(Serendipity Berry), cyclamate salts, and the like, or mixtures of
any two or more of the above.
[0044] High intensity sweeteners can also be present. Such high
intensity sweeteners may include but are not limited to sucralose,
aspartame, salts of acesulfame, alitame, saccharin and its salts,
cyclamic acid and its salts, dihydrochalcones, thaumatin, monellin,
and the like, alone or in combination.
[0045] Combinations of sugar and/or sugarless sweeteners may be
used in the 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.
[0046] One or more flavoring agents may be present in the chewing
gum in an amount within the range of about 0.1 to about 10.0
percent and preferably from about 0.5 to about 5.0 weight percent
of the gum. The flavoring agents may comprise essential oils,
natural or 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 are also contemplated. Those
skilled in the art will recognize that natural and artificial
flavoring agents may be combined in various acceptable fashions.
Optional ingredients such as colors, emulsifiers and pharmaceutical
agents may also be added to the chewing gum.
[0047] In general, chewing GUM is manufactured by sequentially
adding the various chewing gum ingredients to a commercially
available mixer known in the art. After the ingredients have been
thoroughly mixed, the gum mass is discharged from the mixer and
shaped into the desired form such as by rolling into sheets and
cutting into sticks, extruding into chunks, or casting into
pellets.
[0048] Generally, the ingredients are mixed by first softening
(e.g. with heat) the gum base and adding it to the running mixer.
The gum base can also be softened in the mixer itself. Color or
emulsifiers may also be added at this time. A softener, such as
glycerin, may also be added at this time along with syrup and a
portion of the bulking agent. Further portions of the bulking agent
portion may then be added to the mixer. A flavoring agent is
typically added with the final portion of the bulking agent.
[0049] The entire mixing procedure typically takes from five to
fifteen minutes, but longer mixing times may sometimes be required.
Those skilled in the art will recognize that variations of the
above described procedure, or different procedures, may be
followed.
[0050] This invention is illustrated by the following example that
are merely for the purpose of illustration and are not to be
regarded as limiting the scope of the invention or the manner in
which it can be practiced. Unless specifically indicated otherwise,
parts and percentages are given by weight.
EXAMPLE
[0051] In this experiment SBR was synthesized by utilizing the
technique of this invention. In the procedure used the
copolymerization of styrene and butadiene was initiated by charging
16,700 grams of water, 40 grams of tripotassium phosphate, 1,145
grams of sodium oleate (as a 10% aqueous solution), 40 grams of an
iron/EDTA complex, 9 grams of isoascorbic acid (erythorbic acid),
70 grams of styrene, 1.5 grams of n-dodecylmercaptan, 930 grams of
1,3-butadiene, and 42.5 grams of .alpha.-pinene hydroperoxide (44%
active) into a polymerization reactor having a capacity of 10
gallons. The aqueous polymerization medium in the reactor was
maintained at a temperature of 41.degree. F. After 65-70 minutes of
polymerization time an additional 2,500 grams of 10% aqueous sodium
oleate soap solution was charged into the reactor. Then, after
waiting an additional 10 minutes an additional 630 grams of
styrene, an additional 8,370 grams of 1,3-butadiene, and an
additional 13.5 grams of n-dodecylmercaptan were charged into the
reactor. After the solids content reached 16-17% (after about 8
hours of total polymerization time) a final shot of sodium oleate
(10% aqueous solution) was charged into the reactor. Then after a
solids content of 24-25% was reached the copolymerization was
short-stopped by charging 500 grams of a 10% solution of
isoascorbic acid (pH of 10-11) into the reactor.
[0052] The SBR was recovered from the latex and dried. It was
determined to have a bound styrene content of 5%, a Mooney
viscosity of 80, and a RPA t80 of 0.082 minutes. The long
relaxation time observed is indicative of good physical properties
for use in gum base formulations for soft chew gums. It was also
noted that the SBR sample had very low odor and low taste
characteristics. Thus, the SBR made had excellent characteristics
for utilization in making gum base for soft chew gum.
[0053] While certain representative embodiments and details have
been shown for the purpose of illustrating the subject invention,
it will be apparent to those skilled in this art that various
changes and modifications can be made therein without departing
from the scope of the subject invention.
* * * * *