Environmentally friendly chewing gum bases

Chewing gum bases, and resultant chewing gums, that are environmentally friendly are provided. The chewing gum base comprises approximately 3 to about 99% by weight poly(lactic acid) copolymers selected from the group consisting of poly(lactic acid-dimer-fatty acid-oxazoline) copolymers and poly(lactic acid-diol-urethane) copolymers.

BACKGROUND OF THE INVENTION 
The present invention relates generally to chewing gum compositions and 
methods for making same. More specifically, the present invention relates 
to chewing gum compositions that are more environmentally acceptable than 
typical compositions. 
For hundreds of years, people have enjoyed chewing gum like substances. In 
the late 1800's, the predecessor to todays chewing gum compositions were 
developed. Today chewing gum is enjoyed daily by millions of people 
worldwide. 
Chewed gum is usually disposed of in the wrapper that initially houses the 
chewing gum. Likewise, chewed gum can be disposed of in other substrates 
by wrapping the substrate around the chewed gum. 
Although chewed gum can be easily disposed of without creating any 
problems, chewing gum when improperly disposed of can create environmental 
issues. In this regard, the improper disposal of chewing gum, e.g., 
expectorating the chewing gum on a sidewalk, floor, or like area can 
create a nuisance. Typically, these gum cuds are mainly composed of a 
water insoluble masticatory part which is represented by the gum base. Due 
to its formulation, these gum cuds have an adhesive like characteristic. 
Therefore, the chewed gum cuds can stick to surfaces on to which it is 
placed. This can create issues if the chewed gum cuds are improperly 
discarded. 
SUMMARY OF THE INVENTION 
The present invention provides a chewing gum base, and resultant chewing 
gum, that is environmentally friendly. As used herein the term 
"environmentally friendly" refers to a chewing gum composition that: will 
degrade; can be easily removed from indoor or outdoor surfaces; can be 
ingested after chewing; and/or will dissolve in the mouth after a period 
of chewing. 
Pursuant to the present invention environmentally friendly gum bases are 
provided that include biodegradable copolymeric elastomers based on lactic 
acid. 
To this end, the present invention provides, a chewing gum base comprising 
approximately 3 to about 99% by weight poly(lactic acid) copolymers 
selected from the group consisting of poly(lactic acid-dimer-fatty 
acid-oxazoline) copolymers and poly(lactic acid-diol-urethane) copolymers. 
In an embodiment of the present invention, the copolymers are selected from 
the group consisting of lactic acid, dimeric acids and oxazolines, diols, 
and diisocyanates. 
In an embodiment of the present invention, the poly (lactic acid) 
copolymers comprise approximately 20 to about 70% by weight of the chewing 
gum base. 
In an embodiment of the present invention, the poly (lactic acid) 
copolymers comprise approximately 10 to about 99% by weight lactic acid. 
In an embodiment of the present invention, the base includes at least one 
softener chosen from the group consisting of triglycerides of cottonseed 
oil, soybean oil, palm oil, palm kernel oil, coconut oil, safflower oil, 
tallow oil, cocoa butter oil, and medium chain triglycerides. 
In an embodiment of the present invention, the softener is hydrogenated. 
In an embodiment of the present invention, the softener is 
non-hydrogenated. 
In an embodiment of the present invention, the base includes at least one 
softener chosen from the group consisting of hydrogenated soya oil, 
glycerol monostearate, capric triglyceride, and hydrogenated cotton seed 
oil. 
In an embodiment of the present invention, the base has a melting 
temperature, as determined by DSC, of approximately 20 to about 80.degree. 
C. 
In another embodiment, the present invention provides a chewing gum base 
free of elastomers and vinyl polymers having a molecular weight greater 
than 2000. The base includes at least one poly(lactic acid) selected from 
the group consisting of poly(lactic acid-dimer-fatty acid-oxazoline) and 
poly(lactic acid-diol-urethane) copolymers. The gum base also includes a 
filler, a fat, and an emulsifier. 
In an embodiment, the gum base includes a wax. 
In an embodiment, the filler has a particle size of between approximately 3 
to about 10 microns. 
In yet another embodiment of the present invention, a chewing gum is 
provided. The chewing gum comprising a water soluble portion and a water 
insoluble base. The base includes at least one poly(lactic acid) selected 
from the group consisting of poly(lactic acid-dimer-fatty acid-oxazoline) 
copolymers and poly(lactic acid-diol-urethane) copolymers. 
In an embodiment, the insoluble base does not include any elastomers or 
vinyl polymers having a molecular weight greater than 2000. 
In an embodiment, the gum has a removability of greater than 9 in/kg and a 
peel force of less than 150 g/in. 
In an embodiment, the gum has a removability of greater than 30 in/kg and a 
peel force of less than 50 g/in. 
It is an advantage of the present invention to provide an environmentally 
friendly chewing gum base. 
Still further, it is an advantage of the present invention to provide a 
chewing gum composition made from an environmentally friendly chewing gum 
base. 
Another advantage of the present invention is to provide a degradable 
chewing gum containing an environmentally friendly chewing gum base. 
Moreover, an advantage of the present invention is to provide a chewing gum 
composition that when chewed, if improperly discarded onto a surface, can 
be easily removed therefrom. 
Additional features and advantages of the present invention are described 
in, and will be apparent from the detailed description of the presently 
preferred embodiments and from the drawings.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
The present invention provides an improved chewing gum base. Specifically, 
the present invention provides a chewing gum base that is environmentally 
friendly. In this regard, the chewing gum base includes a biodegradable 
elastomer. Additionally, improved chewing gums as well as ingredients used 
for chewing gum bases are described. 
The chewing gum base contains a biodegradable poly(lactic acid) elastomer. 
It is has been surprisingly found that gum bases formed with such a 
poly(lactic acid) elastomer are biodegradable. Not only are they readily 
biodegradable but additionally the gum cuds do not stick on common 
surfaces such as sidewalks, floors, cloth, carpeting, and like surfaces 
when improperly disposed. Additionally, the chewing gum made from such gum 
bases possess similar characteristics to conventional chewing gum. 
Lactic acid is a bifunctional non-toxic monomer. It can be extracted from 
plants, obtained through fermentation of starch, sugar, or cheese, or by 
chemical synthesis. Its homopolymer has been proven to be completely and 
rapidly biodegradable. 
Pure poly(lactic acid) however, is highly crystalline and lacks desired 
elasticity. It therefore does not offer the desirable chewing 
characteristics required by chewing gums. By copolymerizing lactic acid 
with other monomers, one can produce copolymers with desirable elasticity. 
The present invention can be used to construct a variety of chewing gums. 
In general, a chewing gum composition typically comprises a water-soluble 
bulk portion, a water-insoluble chewable gum base portion and 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. The term chewing gum refers 
to both a chewing and bubble gum type gum in its general sense. 
The insoluble portion of the gum, usually referred to as the gum cud, 
typically may contain any combination of elastomers, vinyl polymers, 
elastomer plasticizers, fillers, softeners, waxes and other optional 
ingredients such as colorants and antioxidants. 
The variety of gum base ingredients typically used provide the ability to 
modify the chewing characteristics of gums made from the gum base. 
Elastomers provide the rubbery, cohesive nature to the gum which varies 
depending on this ingredient's chemical structure and how it may be 
compounded with other ingredients. In the gum base and gum of the present 
invention the lactic acid copolymers provide rubbery, cohesive nature. 
Other optional ingredients such as antioxidants may also be used in the gum 
base. 
Antioxidants prolong shelf-life and storage of gum base, finished gum or 
their respective components including fats and flavor oils. Antioxidants 
suitable for use in gum base or gum of the present invention include 
butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), 
beta-carotenes, tocopherols, acidulants such as Vitamin C, propyl gallate, 
other synthetic and natural types of mixtures thereof. 
Preferably, the antioxidants used in the gum base are butylated 
hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tocopherols, or 
mixtures thereof. 
Petroleum waxes aid in the curing of the gum made from the gum base as well 
as improve shelf-life and texture. Wax crystal size when hard also 
improves the release of flavor. Those waxes high in iso-alkanes have a 
small crystal size than those waxes high in normal-alkanes, especially 
those with normal-alkanes of carbon numbers less than 30. The smaller 
crystal size allows slower release of flavor since there is more hindrance 
of the flavor's escape from this wax versus a wax having larger crystal 
sizes. 
The gum base and gum of the present invention may optionally employ 
petroleum waxes containing little if any normal-alkanes, or 
straight-chained alkanes as they may be called, and contain predominantly 
iso-alkanes, or branched chain alkanes, having carbon chain lengths 
greater than about 30. Formulation of some gum bases of this type may 
result in these gum bases being more homogenous and that have ingredients 
exhibiting more compatibility with each other. Again, this compatibility 
is the result of the branched nature of iso-alkanes physically 
interacting, on a molecular level, with the branched nature of the other 
gum base ingredients. 
As just mentioned, the optional waxes are those of at least 10 mm.sup.2 /s 
viscosity, greater than 600 average molecular weight and containing 
predominantly iso-alkanes, or randomly branched alkanes as they may be 
called, of carbon lengths greater than 30. Those waxes not preferred are 
those of less than 10 mm.sup.2 /s viscosity, less than 600 average 
molecular weight, containing predominantly normal-alkanes of carbon 
lengths less than and greater than 30 and some terminally branched 
iso-alkanes. Most preferred gum bases and gums that are free of wax. 
Synthetic waxes are produced by means atypical of petroleum wax production 
and thus are not considered petroleum wax. These synthetic waxes may be 
used in accordance with the present invention and may be included 
optionally in the gum base and gum. 
The synthetic waxes may include waxes containing branched alkanes and 
copolymerized with monomers such as but not limited to propylene and 
polyethylene and Fischer-Tropsch type waxes. Polyethylene wax is not in 
the same category as polyethylene, a polymer of ethylene monomers. Rather, 
polyethylene wax is a synthetic wax containing alkane units of varying 
lengths having attached thereto ethylene monomers. 
Preferably, the gum and gum base is free of petroleum waxes. 
Elastomer plasticizers vary the firmness of the gum base. Their specificity 
on elastomer inter-molecular chain breaking (plasticizing) along with 
their varying softening points cause varying degrees of finished gum 
firmness and compatibility when used in base. This may be important when 
one wishes to provide more elastomeric chain exposure to the alkanic 
chains of the waxes. 
Elastomer plasticizers optionally suitable for use in the present invention 
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, glycerol ester of tall 
oil rosin, pentaerythritol esters of partially hydrogenated rosin, 
partially hydrogenated methyl esters of rosin, pentaerythritol ester of 
rosin, synthetic elastomer plasticizers such as terpene resins derived 
from alpha-pinene, beta-pinene and/or d-limonene and mixtures thereof. 
Most preferably, the gum and gum base is free of elastomer plasticizer, 
which may tend to increase gum cud tack to surfaces. 
The elastomer plasticizers used may be of one type or of combinations of 
more than one. Typically, the ratios of one to the other are dependent on 
each respective softening point, on each effect on flavor release, and on 
each respective degree of tack they cause to the gum. Ball and ring 
softening points of the rosin ester types described above may range from 
about 45 to about 120.degree. C. Softening points of the terpene resins 
may range from about 60 to about 130.degree. C. 
Occasionally, both terpene and rosin ester resins may be used in the 
present invention. The terpene rosin ester ratios may range from about 
1:15 to about 15:1. 
Softeners modify the texture, cause the hydrophobic and hydrophilic 
components of the base to be miscible, and may further plasticize the 
synthetic elastomers of the gum base. Softeners suitable for use in the 
gum base and gum of the present invention include triglycerides of 
non-hydrogenated, partially hydrogenated and fully hydrogenated 
cottonseed, soybean, palm, palm kernel, coconut, safflower, tallow, cocoa 
butter, medium chain triglycerides and the like. 
Though optional, softeners are preferred. The preferred softeners include 
unsaturated, partially saturated or fully saturated oils that contain, as 
one or more of their constituent groups, fatty acids of carbon chain 
length of from 6 to 18, determined from the fatty acid methyl ester 
distribution by gas chromatography. 
The selection of softeners has an influence on the softness of the base and 
copolymer. The caproic, caprylic, myristic, lauric and palmitic fatty 
acids of the triglycerides tend to plasticize the synthetic elastomers 
more than triglycerides containing predominantly stearic fatty acid. As 
examples, triglycerides high in saturated lauric fatty acid more 
effectively plasticize the vinyl laurate/vinyl acetate copolymer, and 
those high in saturated palmitic fatty acid more effectively plasticize 
the polyvinyl acetate polymer, increasing the branching. 
Monoglycerides, diglycerides, acetylated monoglycerides, distilled mono- 
and diglycerides and lecithin may, from their manufacturing processing, 
contain triglyceride levels less than 2 percent by weight. Though these 
ingredients are softeners, they would not be considered as being of the 
same family as the above mentioned softeners oils and would be in a family 
of their own, if optionally used in the present invention. 
Fillers used in gum base modify the texture of the gum base and aid in 
processing. Fillers suitable for use in the gum base and gum of the 
present invention include carbonate or precipitated carbonated types such 
as magnesium and calcium carbonate, ground limestone and silicate types 
such as magnesium and aluminum silicate, clay, alumina, talc, as well as 
titanium oxide, mono-, di- and tricalcium phosphate, cellulose polymers 
such as ethyl, methyl and wood or mixtures thereof. 
Particle size has an effect on cohesiveness, density and processing 
characteristics of the gum base and its compounding. The smaller the 
particle size, the more dense and cohesive the final gum base. Also, by 
selecting fillers based on their particle size distribution, initial mass 
compounding may be varied, thus allowing alteration of the compounding 
characteristics of the initial mass during gum base processing and 
ultimately the final chew characteristics of gums made from these gum 
bases. 
Talc filler may be used in the gum base and gum of the present invention 
that may come in contact with or employ acid flavors or provide an acidic 
environment needed to prevent degradation of an artificial sweetener by 
reacting with calcium carbonate type fillers. Mean particle size for 
calcium carbonate and talc fillers typically range from about 0.1 micron 
to about 15 microns. 
Preferably, the optional fillers used in the gum base and gum of the 
present invention are calcium carbonate, ground limestone, talc, mono-, 
di- and tricalcium phosphate, zirconium silicate, or mixtures thereof. 
More preferably, the optional fillers used have a mean particle size range 
from about 0.4 to about 14 microns and are calcium carbonate and talc. 
Flavorants and colorants impart characteristics or remove or mask undesired 
characteristics. Colorants may typically include FD&C type lakes, plant 
extracts, fruit and vegetable extracts and titanium dioxide. Flavorants 
may typically include cocoa powder, heat-modified amino acids and other 
vegetable extracts. 
Preferably, the optional colorants and flavorants are FD&C lakes and cocoa 
powder respectively and are present at levels from about 0 percent to 
about 15 percent by weight. 
Gum bases are typically prepared by adding an amount of the elastomer, 
elastomer plasticizer and filler, and on occasion a vinyl polymer, to a 
heated (50-240.degree. F.) sigma blade mixer with a front to rear speed 
ratio of from about 1.2:1 to about 2:1, the higher ratio typically being 
used for chewing gum base which requires more rigorous compounding of its 
elastomers. 
The initial amounts of ingredients comprising the initial mass may be 
determined by the working capacity of the mixing kettle in order to attain 
a proper consistency and by the degree of compounding desired to break 
down the elastomer and increase chain branching. The higher the level of 
filler at the start or selection of a filler having a certain particle 
size distribution, the higher the degree of compounding and thus more of 
the elastomeric chain cross linking are broken, causing more branching of 
the elastomer thus lower viscosity bases and thus softer final gum base 
and gum made from such a base. The longer the time of compounding, the use 
of lower molecular weight or softening point gum base ingredients, the 
lower the viscosity and firmness of the final gum base. 
Compounding typically begins to be effective once the ingredients have 
massed together. Anywhere from 15 minutes to 90 minutes may be the length 
of compounding time. 
Preferably, the time of compounding is from 20 minutes to about 60 minutes. 
The amount of added elastomer plasticizer depends on the level of 
elastomer and filler present. If too much elastomer plasticizer is added, 
the initial mass becomes over plasticized and not homogenous. 
After the initial ingredients have mass homogeneously and compounded for 
the time desired, the balance of the base ingredients are added in a 
sequential manner until a completely homogenous molten mass is attained. 
Typically, any remainder of elastomer, elastomer plasticizer, vinyl 
polymer and filler, are added within 60 minutes after the initial 
compounding time. The filler and the elastomer plasticizer would typically 
be individually weighed and added in portions during this time. The 
optional waxes and the oils are typically added after the elastomer and 
elastomer plasticizers and during the next 60 minutes. Then the mass is 
allowed to become homogenous before dumping. 
Typical base processing times may vary from about one to about three hours, 
preferably from about 11/2 to 21/2 hours, depending on the formulation. 
The final mass temperature when dumped may be between 70.degree. C. and 
130.degree. C. and preferably between 100.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. Those skilled in the art will recognize that many variations 
of the above described procedure may be followed. 
Gum formulas may comprise from about 10 to about 95 weight percent a gum 
base made in accordance with the present invention in a gum formula 
typically known to those in the art. 
The water-soluble portion of the chewing gum may comprise softeners, 
sweeteners, flavoring agents and combinations thereof. The sweeteners 
often fill the role of bulking agents in the gum. The bulking agents 
generally comprise from about 5 percent to about 90 percent, preferably 
from about 20 percent to about 80 percent. 
Softeners are added to the chewing gum in order to optimize the chewability 
and mouth feel of the gum. Softeners typically constitute from about 0.5 
percent to about 25.0 percent by weight of the chewing gum. Softeners 
contemplated for use in the gum 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 bulking agents in gum. 
Sugar-free formulations are also typical. 
Sugar sweeteners generally include saccharide-containing components 
commonly known in the chewing gum art which comprise, but are not limited 
to, sucrose, dextrose, maltose, dextrin, dried invert sugar, fructose, 
levulose, galactose, corn syrup solids and the like, alone or in any 
combination. 
The sweetener for use in the present invention can also be used in 
combination with sugarless sweeteners. Generally, sugarless sweeteners 
include components with sweetening characteristics but which are devoid of 
the commonly known sugars and comprise, but are not limited to, sugar 
alcohols such as sorbitol, mannitol, xylitol, hydrogenated starch 
hydrolysates, maltitol and the like, alone or in any combination. 
Depending on the particular sweetness release profile and shelf-life 
stability needed, bulk sweeteners of the present invention can also be 
used in combination with coated or uncoated high-intensity sweeteners or 
with high-intensity sweeteners coated with other materials and by other 
techniques. 
High-intensity sweeteners, or artificial sweeteners and peptide sweeteners 
as they may be referred to, typically may include, but are not limited to, 
alitame, thaumatin, aspartame, sucralose, acesulfame, saccharin and 
dihydrochalcones. The range of these sweetener types in gum typically may 
range from about 0.02 to 0.10 weight percent for sweeteners such as 
alitame, thaumatin and dihydrochalcones, and from about 0.1 to about 0.3 
weight percent for sweeteners like aspartame, sucralose, acesulfame and 
saccharin. A flavoring agent may be present in the chewing gum in an 
amount within the range of from about 0.1 to about 10.0 weight percent and 
preferably from about 0.5 to about 3.0 weight percent of the gum. The 
flavoring agents may comprise 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, clove oil, oil of wintergreen, anise and the like. Artificial 
flavoring components are also contemplated for use in gums of the present 
invention. Those skilled in the art will recognize that natural and 
artificial flavoring agents may be combined in any sensory acceptable 
blend. All such flavors and flavor blends are contemplated for use in gums 
of the present invention. 
Optional ingredients such as colors, emulsifiers and pharmaceutical agents 
may be added to the chewing gum. 
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 initial 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, extruded into chunks or 
casting into pellets. 
Generally, the ingredients are mixed by first melting the gum base and 
adding it to the running mixer. The base may also be melted 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/sweetener. Further portions of the bulking 
agent/sweetener may then be added to the mixer. A flavoring agent is 
typically added with the final portion of the bulking agent/sweetener. A 
high-intensity sweetener is preferably added after the final portion of 
bulking agent and flavor have been added. 
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 many variations of the above described procedure 
may be followed. 
The lactic acid based polymers and the poly(lactic acid) homopolymer is 
semicrystalline and glassy. Also, high molecular weight poly(lactic acid) 
is difficult to achieve from simple thermal polycondensation. By 
polymerizing poly(lactic acid) oligomers with other monomers, fortunately, 
we can achieve both high molecular weights and desired elasticity. There 
are many approaches in this regard. In the present invention two 
copolymers based on lactic acid oligomers can be used. One is a 
poly(lactic acid-dimer fatty acid-oxazoline), and the other a poly(lactic 
acid-diol-urethane). 
The following references disclose the chemistry and process for producing 
the lactic acid based copolymers of the present invention: Linko, 
ChemTech, August 1996, p. 26 et seq; and U.S. Pat. Nos. 5,563,238; 
5,470,944; and 5,360,892. 
Examples of poly(lactic acid-dimer fatty acid-oxazoline) copolymers 
include, but are not limited to copolymers of lactic acid, C-36 dimeric 
acid and 1,3-phenylene bis-oxazoline. 
Examples of poly(lactic acid-diol-urethane) polymers include, but are not 
limited to copolymers of lactic acid, 1,4-butanediol and diisocyanate. 
The principle of making these copolymers is known in the art and typically 
involves three steps: 
(1). Synthesize poly (lactic acid) oligomers (MW-1,000 g/mol) through 
thermal polycondensation of lactic acid at about 120.degree. C.; 
(2). Prepare either --OH or --COOH terminated poly (lactic acid) oligomers 
by reacting either diols or dimer fatty acid with the poly (lactic acid) 
oligomers; 
(3)a. Achieve high molecular weight poly (lactic acid-dimer acid-oxazoline) 
copolymers (PLA-Ox) by reacting carboxyl-terminated LA oligomers with 
oxazoline, as shown in Scheme 1 below, or 
(3)b. Achieve high-molecular weight copolymers by reacting the 
hydroxyl-terminated PLA oligomers with diisocyanate to get poly(lactic 
acid-diol-urethane) elastomers (PLA-Ur), as shown in Scheme 2 below. 
##STR1## 
By way of example and not limitation examples of the present invention will 
now be given: 
GENERAL EXAMPLES 
______________________________________ 
Preferred 
Minimum 
Maximum Minimum Maximum 
______________________________________ 
CaCO3/Talc 0 65 10 40 
Softeners 
Hyd. Fats 0 40 10 20 
mono-, diglyceride 
0 15 3 10 
Capric Triglyceride 
0 10 1 5 
Waxes 0 40 5 15 
Elastomer Plasticizers 
Rosin esters 0 35 0 30 
Terpene resins 
0 35 0 30 
Poly (lactic acid) 
Elastomers 3 100 20 70 
______________________________________ 
SPECIFIC EXAMPLES 
Example 1 
To a small gum base mixer (Plastograph from Brabender Corp., Rochelle Park, 
N.J.) set at 110.degree. C., 50 grams of PLA-Oz was added, then 33 grams 
of calcium carbonate powder (mean particle=4.5-5.0 micron) was slowly 
added while mixing breaking the polymer. After 20 minutes of mixing, 12 
grams of hydrogenated Soya oil and 5 grams of glycerol monostearate were 
added. 
The PLA-Oz elastomer is a copolymer of lactic acid, Henkel.RTM. 1008 dimer 
fatty acid, and 1,3-phenylene bis-oxazoline. The reaction mechanism is 
illustrated in scheme 1 above. The elastomer possesses a Tg of -4.degree. 
C.(DSC). Gel permeation chromatograph (GPC) revealed Mn=12,900 and 
Mw=36,500 relative to polystyrene standards. 
Example 2 
The CaCO.sub.3 powder in example 1 was replaced with a coarse CaCO.sub.3 
powder (mean particle=5.0 micron). Also, 1% capric triglyceride replaced 
1% hydrogenated soya oil. 
Example 3 
In example 2, PLA-Oz was reduced to 45 grams, fine CaCO.sub.3 powder (mean 
particle=2.5-3.0 micron) was increased to 35 grams, capric triglyceride 
was increased to 2 grams, 8 grams of hydrogenated cotton seed oil replaced 
the hydrogenated soya oil, and 5 grams of paraffin wax (Tm=135.degree. C.) 
were added. 
Example 4 
Same as example 3 except that the PLA-Oz is a modified version. The main 
difference of the elastomer is that one third of the bi-functional dimer 
acid (Henkel.RTM. 1008) was replaced by a tri-functional acid 
(1,2,3-propane tricarboxylic acid) which provides the final polymers with 
more branchness. DSC showed a Tg of 13.degree. C. for this polymer. GPC 
revealed Mn=8,900 and Mw=31,900 relative to polystyrene standards. 
Example 5 
To a small gum mixer set at 50.degree. C. was adding 19.4 grams of gum base 
example 2, 59.7 grams of 6x sugar, 19.8 grams of 45Be corn syrup and mix 
them for 20 min. Then 0.5 g 99% glycerol and 0.6 grams of peppermint 
flavor was added. Additional 5 minutes of mixing was continued before 
discharging. 
Example 6 
In example 4, 1% sugar was replaced with capric triglyceride, and glycerol 
was increased to 1%. 
Example 7 
To a small gum mixer set at 50.degree. C. was adding 20.0 grams of gum base 
example 3, 58.4 grams of 6x sugar powder, and 20 grams of 45 Be corn 
syrup. After mixing for 20 minutes, 1.0 gram of glycerol and 0.6 grams of 
peppermint oil were added. Additional 5 minutes mixing was continued. The 
gum was sheeted and cut to sticks. 
Example 8 
Gum base example 4 was used. 
The rheological property of example 1 is compared with two typical, butyl 
rubber based gum bases, as shown in FIG. 1; graphically G' [dyn/cm.sup.2 ] 
versus Temperature [C.degree.] is illustrated. The tests were run on a 
Rheometrics RSA-2 rheometer at 10 R/s and 0.5% strain at a heating rate of 
28.degree. C./min. As we can see, it is very close in the temperature 
range between -30.degree. C. and 60.degree. C. 
Differential scanning calorimetry (DSC) measurements were carried out on a 
Perkin Elmer DSC-7 at a heating rate of 15.degree. C./min. FIG. 2 is a 
comparison of base examples 2 and 3 with a conventional butyl rubber based 
gum base; graphically heat flow versus temperature (C.degree.) is 
illustrated. The melting range is very similar as we can see. 
Gum cud removability is characterized by a modified peel tester 
(Instrumentors, Inc., Strongville, Ohio). First, water-soluble ingredients 
were extracted from a gum stick. Then the gum cud was rolled on a cotton 
fabric tape to provide a 0.5".times.3.0" area. Finally the sample was 
rolled on a concrete substrate with a 4.5 LB auto roller and peeled at 
room temperature (20.degree. C.). The peeling angle is 90.degree. and a 
speed of 12 inch/min was used. 
Removability is defined as: 
##EQU1## 
where R represents "removability", P.sub.a is the peeling force per inch 
wide, and C.sub.F is the fraction of residue left on the concrete 
substrate. The physical meaning of this "gum removability R" is "how many 
inches (width) of a gum cud can be completely removed with every kilogram 
applied force". 
Table 1 is a comparison of the removability of two environmentally friendly 
gums versus three conventional gums. 
TABLE 1 
______________________________________ 
Removability of Gum Cuds from 
Concrete Surface at Room Temperature 
Peel Force Residue Removability 
Gum (g/inch) (%) (inch/kg) 
______________________________________ 
Example 5 19 0 52.63 
Example 7 27 0 37.04 
Freedent .RTM. 
157 0 8.98 
Spearmint 
Trident .RTM. 
366 0 2.72 
Original 
Bazooka .RTM. 
730 5 1.46 
______________________________________ 
As we can see, the experimental gums required much less force to peel from 
concrete surface and left no visible residues, which is ideal. 
It should be understood that various changes and modifications to the 
presently preferred embodiments described herein will be apparent to those 
skilled in the art. Such changes and modifications can be made without 
departing from the spirit and scope of the present invention and without 
diminishing its intended advantages. It is therefore intended that such 
changes and modifications be covered by the attendant claims.