U.S. patent application number 11/275049 was filed with the patent office on 2006-03-30 for degradable animal chewing article possessing enhanced safety, durability, and mouth-feel.
Invention is credited to Matthew Denesuk, Donald R. Uhlmann.
Application Number | 20060067989 11/275049 |
Document ID | / |
Family ID | 26833557 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060067989 |
Kind Code |
A1 |
Denesuk; Matthew ; et
al. |
March 30, 2006 |
Degradable Animal Chewing Article Possessing Enhanced Safety,
Durability, and Mouth-Feel
Abstract
A chewable, biodegradable article for use as a pet toy comprises
a matrix made of a natural polymer, a synthetic organic polymer or
a mixture thereof, a natural or synthetic fibrous material that
comprises fibers and that is bonded chemically or physically with
the matrix material, and, optionally, includes one or more microbe
inhibiting agents that inhibit the growth of microbes in or on the
article. The presence of the fibrous material inhibits formation of
sharp edges upon breakage when the article is chewed, thereby
rendering the article safer when used by pets. Also disclosed are
processes for manufacturing the above article.
Inventors: |
Denesuk; Matthew; (San Jose,
CA) ; Uhlmann; Donald R.; (Tucson, AZ) |
Correspondence
Address: |
MCGARRY BAIR PC
171 MONROE AVENUE, N.W.
SUITE 600
GRAND RAPIDS
MI
49503
US
|
Family ID: |
26833557 |
Appl. No.: |
11/275049 |
Filed: |
December 5, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10249578 |
Apr 21, 2003 |
6972133 |
|
|
11275049 |
Dec 5, 2005 |
|
|
|
09578199 |
May 24, 2000 |
6576246 |
|
|
10249578 |
Apr 21, 2003 |
|
|
|
60135672 |
May 24, 1999 |
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Current U.S.
Class: |
424/442 |
Current CPC
Class: |
A23K 50/40 20160501;
A23K 50/42 20160501; A01K 15/026 20130101 |
Class at
Publication: |
424/442 |
International
Class: |
A23K 1/165 20060101
A23K001/165; A23K 1/17 20060101 A23K001/17 |
Claims
1. An article for chewing by pets, which comprises: (a) a matrix
comprising a starcheous or proteinaceous material in combination
with a polyolefin or a polyethylene copolymer; and (b) a fibrous
material dispensed throughout the matrix and comprising collagen
fibers, cellulose fibers, polysaccharide fibers or cotton
fibers.
2. The article of claim 1 wherein the matrix and fibrous material
are formed into a shape suitable for chewing by pets by melt
processing.
3. The article of claim 2 wherein the melt processing is extrusion
or injection molding.
4. The article of claim 1, wherein said matrix components comprise
a reactive blend.
5. The article of claim 1 and further comprising one or more
microbe-inhibiting agents.
6. The article of claim 5 wherein said microbe-inhibiting agents
are selected from the group consisting of triclosan
(2,4,4'-trichloro-2'hydroxydiphenol or ester thereof),
diiodomethyl-p-tolysulphone, tri-n-butyl tin maleate, and
3-trimethoxy-silylpropyldimethyloctadecyl ammonium chloride, or
mixtures thereof.
7. The article of claim 1 and further comprising one or more of a
compatibilizer or compatibilizers, a plasticizer or plasticizers, a
particulate material or materials, a color modifier or modifiers, a
taste agent or agents and aroma modifier or modifiers.
8. The article of claim 7 wherein said particulate material
comprises particles selected from dextran, titanium oxide, silicon
oxide, carbon, aluminum oxide, hydroxide and oxy-hydroxide, calcium
carbonate, feldspar and kaolin, and mixtures thereof.
9. The article of claim 7, wherein said taste agent is incorporated
using particulates as vehicles.
10. The article of claim 7, wherein said taste agent is derived
from plants.
11. The article of claim 1, wherein said starcheous material is
derived from potatoes, corn, wheat, rice or tapioca.
12. The article of claim 1, wherein said proteinaceous material is
derived from animal sources.
13. The article of claim 1, wherein said fibrous material has an
average fiber length between about 1 micron and 1000 microns, and
wherein the length-to-diameter ratio of said fibers is greater than
about 25.
14. The article of claim 1, wherein the weight fraction of said
fibrous material relative to the weight of the article is between
about 1 percent and about 30 percent.
15. The article of claim 1, wherein said fibrous material is
chemically or physically bonded to said matrix.
16. The article of claim 15, wherein said fibrous material is
chemically treated to promote bonding to said matrix.
17. The article of claim 1, wherein the article has a significant
aspect ratio and a significant portion of said fibrous material is
oriented along a long direction of the article.
18. The article of claim 1, wherein the fibrous material and the
matrix are selected to resist propagation of a clean breakage
plane, thereby inhibiting formation of sharp edges upon
breakage.
19. A process for making a composite material that is formable an
article according to claim 1 comprising combining the starcheous or
proteinaceous material and the polyolefin or a polyethylene
copolymer, the fibrous material and, optionally, the microbe
inhibiting agent, under conditions that result in a material that
does not tend to splinter or form sharp edges when formed into a
chewable article and subjected to chewing.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/249,578, Apr. 21, 2003, now U.S. Pat. No. 6,972,133,
issued Dec. 6, 2005, which is a divisional U.S. patent application
Ser. No. 09/578,199, filed May 24, 2002, now U.S. Pat. No.
6,576,246, issued Jun. 10, 2003, which claims the benefit of U.S.
provisional patent application Ser. No. 60/135,672, filed May 24,
1999.
FIELD OF THE INVENTION
[0002] The invention relates to chewable articles intended
primarily as chew toys for dogs or other domestic animals.
DESCRIPTION OF THE RELATED ART
[0003] Chewable animal articles such as artificial bones for dogs
have been made of many materials and in many configurations and
sizes. These have been made of compressed natural or food materials
with a binding agent; some are made of synthetic polymers, as
polymers mixed with protein (U.S. Pat. No. 4,681,758), nylon (U.S.
Pat. No. 3,871,334) or polyurethane (U.S. Pat. Nos. 4,557,219 and
4,513,014).
[0004] Chewable articles are frequently constructed from degradable
materials that possess at least a substantial component which
degrades or otherwise diminishes substantially in structural
integrity with usage and over time. The degradation, typically
accelerated by the chewing action of the animals, is frequently
accelerated by exposure to the moisture and/or digestive enzymes in
saliva. The durability of such articles is therefore intrinsically
limited.
[0005] If a chewable article is too soft, it is too easily ripped
apart or shredded during use. On the other hand, if the article is
too hard, it may tend to crack, shatter, or splinter. This tendency
to splinter upon breakage or when otherwise structurally damaged is
highly undesirable. Splintering leads to sharp edges that can cause
injury and lead serious health problems for the animal, especially
if sharp-edged material is swallowed. Moreover, small pieces
breaking from the articles may also be swallowed and contribute to
health problems.
[0006] Of the digestible type of mastication article, rawhide is
the most popular type of mastication article (e.g., U.S. Pat. Nos.
5,114,704; 5,310,541; 5,476,069). Simulated rawhide mastication
articles comprise oil seed protein, a polyol plasticizer, lecithin,
and water, extruded into a ribbon (U.S. Pat. No. 4,419,372).
[0007] U.S. Pat. No. 5,407,661 discloses a digestible mastication
article for a pet in which a starch, a cellulosic fibrous material
(e.g., corncob fractions), a humectant, a proteinaceous binder and
a tarter-control oral care additive. U.S. Pat. No. 5,419,283
discloses a molded mastication article comprising a starch material
and a biodegradable ethylene copolymer. Other edible materials can
be added as plasticizers or as lubricants. These materials are
mixed in the presence of water for subsequent injection molding
into desired shapes (e.g., a bone).
[0008] U.S. Pat. No. 5,477,815 discloses a molded dog mastication
article comprising water absorbing nylon in which at least a
surface layer has sugar incorporated therein.
[0009] U.S. Pat. No. 5,485,809 discloses animal chewing toys that
shave away when chewed without puncturing, cracking, splintering or
shattering, while providing satisfaction to the chewing animal. The
chewing action is said to produce a desirable roughening and
bristling of the surface that scours and cleans the animal's teeth.
Flavoring material is uniformly dispersed throughout the body of
the toy rather than just on the surface. The article is made from
an ethylene/methacrylic acid copolymer, ionically cross-linked
ionomer resin. This document discloses a desirable range of
hardness (on a "D" scale,--from 65 to 99, preferred range from 75
to 85).
[0010] U.S. Pat. No. 4,364,925 ('925) discloses chew-resistant
products made from feed particulates with supporting fibers
incorporated into the food components prior to compacting. Chew
resistance is controlled primarily by the amount of such fibers. A
multilayer article comprises at least one layer of a higher
chew-resistance than the other layer, controlled by the amount and
type of structure-supporting fibers. For example, supporting fibers
are incorporated in the base layer of dry dog food and then a
second layer is prepared without such fibers to yield a multilayer
article having an inner hard, chew-resistant layer and an
relatively soft and crumbly exterior layer. Alternatively, an inner
layer is prepared without supporting fibers and a second layer with
fibers is superimposed, leading to a hard exterior layer and soft
interior layer. By starting with a soft-core layer and alternating
the type of layers, multiple alternating harder and softer layers
are produced. Such materials can serve as chew-resistant products
that are sufficiently hard to exercise a pet's teeth and jaws and
to remove plaque and tartar.
[0011] Suitable structure-supporting fibers are said to be any
fibers that perform the function of binding the food into a
unitized chew-resistant product and are not harmful. Such fibers
may or may not be digestible by the animal. Safely digestible
fibers include collagen. Indigestible fibers include cellulosic
fibers or mixtures of animal-based digestible fibers and such
indigestible fibers. Suitable sources of digestible fibers are
animal tissue--for example, skin, muscles, tendons, intestines,
etc. The amount of animal hide material used as a source of
collagen depends upon factors such as the type and amounts of
fibers in the hide, the type of food in the product, whether
swollen or unswollen collagen or hide binders or gels are employed,
etc. As defined in this document, "collagen" includes other fibrous
protein such as elastin, reticulin, etc. The bundles of fibers are
said to be theoretically broken and realigned to form fiber
interlocks. For maximum strength the cut fibers re-interlock in the
final product so that relatively continuous fiber linkage bonds are
maintained. Useful collagen fibers include those obtained from
hides as well as those prepared by dissolving protein,
precipitating the protein from solution and aligning the molecules
to obtain a fibrous material. Protein fibers may also be derived
from soy protein, egg white, wheat gluten, etc. The fibrous form of
these proteins are spun into continuous aligned filaments to yield
food forms which simulate the fiber of natural beef. The document
cites Belgian Pat. 634,140, U.S. Pat. Nos. 3,071,477 and 3,197,310
and Cereal Chem 43 (2) 195 (1966).
[0012] According to the '925 patent, the supporting fibers are
present in amounts sufficient to render the products
chew-resistant, self-contained and unit-integral and to enable them
to remain in compacted, shaped and molded form. The percent by
weight of the indigestible fibers, or the mixture of the
indigestible and digestible fibers in a unilayer food article may
comprise up to about 50% or more, about 0.5-40%, about 1-30%, of
about 1-10%, but preferably from about 1-5%. The optimum amount
depends on factors such as the thickness, length, etc., of the
fibers and the desired chew-life.
[0013] It is noteworthy that the '925 patent does not discuss
breakage or splintering of the articles and the dangers they pose,
nor does it address the objectives of the present invention.
Rather, the '925 patent is primarily directed to pressed animal
matter with added fibers that are intended to enable the overall
material to retain a structure. Further, the processing involved in
the '925 patent is that of baking, in essence making cookies or
biscuits (wherein the added fibers provide a cohesiveness to the
overall structure). Thus, the '925 patent deals essentially with
baking of compacted animal flesh or feed incorporated with
structure-supporting fibers; in the preferred mode, the fibers
mutually interlock so that a continuous fiber network spans the
article. Regardless, the processing and nature of the materials
involved ensure that the fibers are of a static and correlated
nature, closer in function and, in fact, closer to being a second
matrix which intertwines with the first matrix.
SUMMARY OF THE INVENTION
[0014] According to the invention, a chewable, biodegradable
article for pets (as a pet toy) comprises: [0015] (a) a matrix
comprising a starcheous or proteinaceous material in combination
with a polyolefin or a polyethylene copolymer; and [0016] (b) a
fibrous material dispensed throughout the matrix and comprising
collagen fibers, cellulose fibers, polysaccharide fibers or cotton
fibers; [0017] wherein, the presence of the fibrous material
inhibits formation of sharp edges upon breakage when the article is
chewed. The invention provides composite materials for safer and
more durable chewable articles for pets.
[0018] The above article of further may further comprise one or
more of a compatibilizer, a plasticizer and an inert
particulate.
[0019] A preferred natural polymer for the matrix of the above
article is a starch-based polymer.
[0020] In the above article of, the fibers having an average length
of between about 0.1 micron and about 1200 micron, preferably
between about 1 micron and about 1000 micron, most preferably about
5-500 micron.
[0021] In the above article, the length-to-diameter ratio of the
fibers is greater than 25, and may be greater than 100. The weight
fraction of the fibrous material relative to the weight of the
article is between about 1 percent and about 30 percent, preferably
between about 2 percent and about 15 percent.
[0022] The fibrous material in the above article may be a natural
fibrous material, for example, comprising a collagen, a cellulosic,
a polysaccharides, flax, hemp, cotton, wool or a mixture thereof.
The fibrous material may also be a synthetic fibrous material, for
example, a poly(alpha-hydroxy acid), nylon, polyester, or
polyolefin, or even an inorganic oxide fiber.
[0023] In contrast to the '925 patent, the present invention
utilizes polymeric materials which are processed in radically
different way (polymer melt processing) than are the "biscuits" of
the '925 patent (baking). Processing in the present invention
involves elevated temperatures, shear rates, and pressures,
resulting in final articles with profoundly different
microstructural characteristics, such as a, relative lack of
correlation in spatial distribution of the fibers (no spanning
structures or clumping). Furthermore, the nature of the matrix in
the present invention differs fundamentally from that in the '925
patent in that it is self-supporting. Thus, the polymers of the
present chewable articles possess great cohesiveness and structural
integrity on their own (without added fibers). Fibers (and/or other
materials) are added to the articles of the present invention (1)
to affect favorably the nature of the breakage processes and (2) to
improve the "mouth-feel", all thee while without sacrificing
desirable mechanical properties and degradability.
[0024] The above article preferably comprises one or more microbe
inhibiting agents.
[0025] Also provided is a process for making a composite material
that is formable into the above article, comprising combining the
polymer or mixture of polymers, the fibrous material and,
optionally, the microbe inhibiting agent, under conditions that
result in a material that does not tend to splinter or form sharp
edges when formed into a chewable article and subjected to
chewing.
[0026] A process for manufacturing a chewable article comprises
making the above composite material and forming the material into
the article.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] The present invention provides safer chewable articles for
animals by incorporating binding material into the articles which
(a) increase durability, (b) decrease the tendency for pieces to
detach, and (c) inhibit formation of sharp edges upon breakage.
[0028] The degradable chewable articles of this invention are
comprised of natural polymers, synthetic organic polymers or
mixtures thereof.
[0029] A common class of biodegradable polymers is starch-based.
Pure starch polymers do not possess the desired properties as they
are brittle and are unduly affected by moisture. They are therefore
commonly blended and/or reacted with other polymers. U.S. Pat. No.
5,321,064 describes a class of biodegradable polymers in which
starch is reacted with synthetic polymeric material such as
polyethylene, polystyrene, polypropylene and polyvinyl chloride.
U.S. Pat. No. 5,409,973 describes a class of materials based on
starch and an ethylene copolymer. U.S. Pat. No. 5,360,830 describes
a similar material produced in expanded form. U.S. Pat. No.
5,459,258 describes a class of biodegradable materials based on the
combination of hydrophobic polysaccharides, one thermoplastic and
the other non-thermoplastic.
[0030] Biodegradable starch-based resins are available commercially
from a number of manufacturers, such as Starchtech.TM.,
Novamont.TM. and Arizona Natural Materials.TM.. Starchtech.TM.
sells a series of such polymers under the "Re-NEW.TM." trade name.
Novamont.TM. offers several classes of such polymers under the
trade name, "Mater-Bi.TM.."
[0031] A starch-based chewable article reinforced with natural
fibers as described below is a preferred embodiment of this
invention.
[0032] Biodegradable synthetic organic materials of
poly(.alpha.-hydroxy acid) class including poly(lactic acid) (PLA),
poly(glycolic acid) (PGA) resins, as well as poly lactide-glycolide
(PLGA) copolymers have numerous desirable properties. (See: Ratner,
B D et al., Eds., Biomaterials Science, Academic Press, New York,
1996, p. 64; Naitove, M., Plastics Technology, March 1995, p. 15.)
A variety of commercial grades are available from Cargill, under
the name "EcoPLA.TM.," and also from various biomedical suppliers.
Adjustment of the PGA:PLA ratio in a material can be used to
fine-tune the texture, degree of hydrophilicity and rate of
biodegradation. For example, PGA is more hydrophilic than PLA, so
that increasing the PGA content will increase the hygroscopic
property (uptake of water, saliva, or any other fluid). In
addition, although PGA is highly crystalline, which generally slows
its degradation, it becomes markedly less crystalline, and more
degradable, when blended with PLA.
[0033] Materials based on polyhydroxybutyrate (PHB) are also
attractive. One example, available commercially under the name
Biopol.TM. comprises a blend with 3-hydroxyvaleric acid (PHV). PHB
is generally highly crystalline, inflexible, and difficult to
process. Blending with PHV diminishes the crystallinity, resulting
in more flexible, more easily processed materials.
[0034] Polycaprolactone, either pure or blended with other
materials, is a generally attractive degradable material that has
found uses in medical applications such as sealing materials for
wounds.
[0035] Other attractive degradable materials include, the
poly(amino acids), the polyanhydrides, poly (ortho esters), and
polyphosphazenes.
[0036] The nature of the present matrix differs fundamentally from
the prior art in that it is self-supporting, meaning that it needs
no reinforcements or other aids (such as fibers) in order for it to
possess substantial structural integrity. Thus, the present matrix
materials form "respectable" materials in their own right (in
contrast to those, for example, disclosed in U.S. Pat. No.
4,364,925.
[0037] The polymer in the matrix is often combined with inert
particulates, compatibilizers, plasticizers, etc. For a general
reference, see Plastics Additives and Modifiers Handbook, J.
Edenbaum, ed., Chapman and Hall, Great Britain, 1996, which is
incorporated by reference in its entirety.
[0038] It is preferred to include one or more antimicrobial agents
to inhibit the growth of mold or other microbes in the
articles.
[0039] More durable and safer degradable chewable articles for
animals are produced by including a fibrous material, preferably a
natural fibrous material, in the article's formulation.
[0040] In preferred cases, the fibrous material forms chemical or
physical bonds with the host material (the "matrix"). Chemical
bonds are generally covalent or ionic bonds--powerful short-range
interactions. "Physical" bonds generally refer to longer range
interactions (e.g., dispersion forces) or structural interactions
such as interlocking barb-like structures, interpenetration (like
wood glue), etc. Both classes of bonding are well-known in the art
of adhesion engineering.
[0041] Such fibers resist propagation of a clean breakage plane,
thereby inhibiting formation of sharp edges upon breakage. This not
only inhibits breakage but also forces those breaks that will
necessarily occur to have a "bumpy" profile, thereby minimizing
sharp edges.
[0042] The fibrous materials can be either of natural or synthetic
origin. For formulation of articles that are relatively more (or
more rapidly) degradable, natural fibrous materials are preferred
because of their degradability upon exposure to saliva, enzymes,
and other substances with which they come in contact during the
acts of chewing and digestion. Also preferred are biodegradable
synthetic polymer fibers such as the poly(.alpha.-hydroxy acids).
In addition, presence of natural fibers may be preferred by
consumers as they are perceived as being healthier for the
animal.
[0043] In a preferred embodiment, fibers are incorporated into the
chewable articles along with an a microbe-inhibiting ("MI") agent
or compound. A MI compound is one that inhibits the growth,
proliferation, spread, of any of a number of microorganisms, most
importantly fungi (especially mold and yeast) and bacteria as well
as algae, protozoa and various microscopic parasitic organisms. The
most preferred compounds act in a manner that is not selective for
any particular organism, but rather are inhibitory to a broad
spectrum of microbial agents. The MI compound can act by any
mechanism to inhibit growth of the organisms, whether biostatic or
biocidal. The preferred compounds are not required to have a
particular inherent level or threshold of activity to be useful in
accordance with this invention. In general, the preferred MI
compounds are not the highly selective antibiotics of the type used
in human medicine. Presence of a MI agent or compound is especially
important when using a natural or otherwise biodegradable material
either as the matrix or as a binding element since such a material
is especially susceptible to microbial invasion and
degradation.
[0044] MI compounds useful in the present invention are described
in more detail in copending, commonly assigned application U.S.
Ser. No. 09/513,703 filed Feb. 25, 2000, now U.S. Pat. No.
6,566,419, which also describes formulations and processes for
incorporating these compounds. Below is a nonlimiting description
of some of these compounds.
[0045] A preferred MI compound is diiodomethyl-p-tolylsulphone
("DIMTS"). Paulus, W., Microbicides for the Protection of
Materials, Chapman & Hall, 1993, which is hereby incorporated
by reference, describes this and other biocidal and biostatic
agents. This compound possesses a broad spectrum of anti-microbial
activity, and is most active against fungi (including yeast) and
algae. DIMTS is especially preferred in articles that may be
partially or wholly digested.
[0046] DIMTS can cause yellowing in the final article, and if this
is deemed unattractive, color suppressants can be added. DIMTS
melts at about 157.degree. C. It is relatively insoluble in water
(0.0001 g/L at 25.degree. C.). Acetone (350 g/L at 25.degree. C.)
and ethanol (20 g/L at 25.degree. C.) are preferred solvents. DIMTS
is generally stable over a pH range of about 4-10. A preferred form
of DIMTS is the product Ultrafresh UF-95.TM., available from Thomas
Research Associates. The concentration of UF-95.TM. in the finished
product should be between about 0.001% to 3%, preferably between
about 0.01% and 1% by weight percent. (Unless otherwise specified,
all concentrations disclosed herein are given in weight %).
[0047] Triclosan (2,4,4'-trichloro-2-hydroxydiphenylether), another
preferred MI compound, is sold by Ciba-Geigy under the trade name
Irgasan DP-300.TM.. It can be obtained as a crystalline powder or
as a liquid concentrate. It is also available from Thomas Research
Associates under the trade name Ultrafresh NM-100.TM. in a
commercial form ready for compounding. Unmodified triclosan is
insoluble in water; sparingly soluble in dilute alkali solution;
and soluble in ethanol. It melts at about 60.degree. C., and
decomposes at about 285.degree. C. It has an LD.sub.50 oral
toxicity of >5000 mg/kg for dogs. It is non-mutagenic,
non-teratogenic and has good skin compatibility. Data for
triclosan, along with that for many other MI agents, are given in
Paulus, supra.
[0048] Ultrafresh NM-100.TM., a preferred form of triclosan, is
added in quantities to achieve a final concentration in finished
product between about 0.001% and 2%, preferably between about
0.004% and 0.3% by weight.
[0049] Bacticlean.TM. (alcohol ethoxylate 5-10%, benzalkonium
chloride 1-5%, alkly dimethylamine betaine 1-5%, alkylamine
dicarboxylate sodium 1-5%) (Allied Resinous Products, Inc.
Conneaut, Ohio) is a preferred MI "cocktail," i.e., a combination
of compounds that work together to create broad-spectrum protection
against microbial growth. Bacticlean.TM. is particularly preferred
when processing with polyolefins.
[0050] Other preferred MI compounds include Vinyzene.TM. (OBPA
(10,10'-oxy-bis-phenoxarsin)); (Rohm and Haas Company)
Intercide.TM. (a tributyltin derivative); (AKZO Nobel, Inc.,
Chicago, Ill.) Fungitrol.TM. (N-(trichloromethylthio)phthalimide)
(International Speciality Products Corporation, Wayne, N.J.);
Cunilate.TM. (copper-bis-(8-hydroxyquinoline) (Rohm and Haas
Company); Vancide.TM. (zinc dimethyldithiocarbamate) (R.T.
Vanderbilt Company, Inc., Norwalk, Conn.)
(N-trichloromethylthio)-4-cyclohexene-1,2-dicarboximide);
Micro-Chek.TM. (2-N-octyl-4-isothiazolin-3-one) (Ferro Corporation,
Cleveland, Ohio); Zinc Omadine (a zinc complex of pyrithione); and
Apacider.TM. (silver hydroxyapatite) (Sangi Co., Ltd.; Sangi
America, Thousand Oak, Calif.).
[0051] In many cases, consumers may prefer articles that include or
have been treated with natural MI agents. Garlic and turmeric are
preferred sources of such materials, e.g., in the form of extracts
or concentrates, but other natural spices or additives known in the
art can be used as well.
[0052] A diffusible MI agent (such as triclosan or DIMTS) will
diffuse into the surrounding material, thereby imparting the MI
property to the material. This will generally diminish
biodegradability of the article as the MI agent neutralizes or
otherwise inhibits any of a number of biodegrading microbes, but
will generally not diminish the degradability that results from the
chewing action (e.g., the biodegradation caused by saliva,
digestive enzymes, and aqueous fluids including water). Thus, this
selective action of the MI agents can be exploited to fine-tune the
degradability and sensitivity of the present chewable articles.
[0053] In the case of a strongly bonded or relatively non-diffusing
MI (such as Dow Corning 5700), the MI property will remain only
with the fibers, which will resist biodegradation, but will not be
imparted to the rest of the article. This property is preferred
when a more biodegradable product is desired.
[0054] Whether natural or synthetic, the fibrous materials used
herein should be in the form of fibers of discrete lengths rather
than continuous filaments. Useful fibers range in length from
fractions of a millimeter to centimeters. Preferred fiber diameters
are in the range of about 0.1-1200 micron, more preferably about
1-1000 micron most preferably about 5-500 micron. Preferred
length-to-diameter (L/D) ratios exceed 10, preferably exceed 20,
and most preferably exceed 25. Fibrous materials having L/D ratios
exceeding 100 or even 1000 are also contemplated.
[0055] The fibrous materials are usefully employed in weight
fractions (relative to the weight of the articles), ranging from 1
percent to 30 percent, preferably from 2 percent to 15 percent.
[0056] For articles having dimensions with a significant aspect
ratio, e.g., articles shaped like bones for dogs, it is preferred
that a significant portion (but not necessarily all) of the fibrous
materials be oriented along the long dimension of the article,
since this will provide resistance to crack propagation in response
to the principal stresses imparted by chewing.
[0057] A wide range of natural fibrous materials may be used in the
present invention. Preferred natural fibrous materials include
collagens, cellulosics, polysaccharides, flax, hemp, cotton, wool
or mixtures thereof. The collagen is preferably from an animal
source.
[0058] A preferred natural material is cotton fiber. Cotton fiber
may be obtained pre-compounded in commercial pellet form, e.g., in
polypropylene or polyethylene pellets, where the cotton is
typically seen as a lightweight filler. In a preferred embodiment,
cotton-loaded synthetic polymer pellets are blended with a natural
material, such as a starch-based material, and the resulting
articles are molded into a desirable shape. Other synthetic
polymers may also be included, along with compatiblizers or
coupling agents.
[0059] Cotton fibers, cut into the appropriate lengths, may also
simply be compounded with the base material as it is being
pelletized. Alternatively, the fiber may be mixed with the
compounded pellets in the hopper of an injection molding
apparatus.
[0060] Synthetic fibrous materials may also be used. Useful
synthetic fibrous materials include both organic and inorganic
fibrous materials, with organic materials preferred. Examples of
useful inorganic synthetic fibrous materials include carbon and
glass, particularly fibrous glasses that are more water soluble
than conventional fiberglass. Such as compositions based on
modified sodium silicates. Nonlimiting examples of organic
synthetic fibrous materials include nylons, polyesters and
polyolefins. Preferred synthetic organic fibrous materials are the
poly(.alpha.-hydroxy acids) such PGA, PLA and PLGA.
[0061] When using synthetic fibrous materials, a bonding agent is
preferably present to encourages at least partial physical or
chemical bonding of the fibrous materials with the matrix. The
bonding agent can be a discrete chemical species which promotes
bonding, such as a siloxane-based coupling agent, or may represent
chemical units in the fibrous materials for which there exist
complementary chemical units in the matrix or which have inherent
bonding capabilities with chemical groups in matrix materials,
e.g., the amide groups in nylon fibers.
[0062] Bonding may also be promoted by using maleated fibers (or
other discrete binding elements) and/or the maleated matrix
material.
[0063] The matrix can be wholly natural, wholly synthetic or a
blend (either reactive or non-reactive) of at least one natural
material and at least one synthetic material.
[0064] Preferred synthetic matrix components include polyolefins
(e.g., polyethylene, polypropylene, polyisoprene, polystyrene),
ethylene copolymers (e.g., poly-ethylene-vinyl alcohol,
poly-ethylene-acrylic acid), polycapralactone, PGA, PLA and PLGA
copolymers, polyurethanes, particularly polyether urethanes,
polycarbonates, polyamides, polyesters, etc.
[0065] Forms of these polymers that are rendered more reactive are
preferred in cases where the natural matrix component is not
particularly reactive or is otherwise less amenable to chemical or
physical bonding. One means of accomplish such heightened
reactivity is by forming the polymer grafted or otherwise
incorporated with maleic anhydride.
[0066] Preferred natural matrix components include starcheous
materials, proteinaceous materials, lignin and lipids. Starcheous
materials can be obtained from potatoes, corn, wheat, rice,
tapioca, etc. Preferred starcheous materials are derived from corn,
wheat, and/or potatoes.
[0067] Proteinaceous materials can be derived from a variety of
animal and vegetable sources well-known in the art. Preferred
proteinaceous materials for use as matrix components are gelatins,
casein, and collagens. Lipids can be derived from or incorporated
as nuts, a milk product, vegetable oil or animal oil.
[0068] If the matrix material possesses substantial water or saliva
sorption tendencies, it is expected that, through use, the matrix
may be torn away from the binding material (e.g., the binding
fibers) as the article expands. For this reason, when the water
sorption tendency of the matrix material is substantial, the
binding material is preferably selected from a group of materials
with comparable or otherwise compatible sorption tendencies.
[0069] When discrete fibers of relatively short lengths, e.g.,
0.05-1 mm, are employed as the binding agents, the chewable
articles can be formed by known techniques such as injection
molding, compression molding, extrusion and rotomolding.
[0070] When discrete fibers of relatively long lengths, e.g.,
multiple millimeters or more, are employed as binding agents, it is
often useful to form at least a portion of the chewable article
using techniques appropriate for long fibers, such as pultrusion.
The portion of the article thus formed are then used as inserts in
forming operations such as insert molding.
[0071] The matrix of the present chewable articles may include a
number of inorganic or organic particulate materials, generally for
the purpose of modifying and tailoring the (1) mechanical
properties (2) thee aesthetics and (3) cost of the chewable
articles. The preferred particle sizes of these particulate
materials range from about 0.01 to about 100 micron, preferably
from 0.02 to 50 micron.
[0072] A preferred organic particulate material is dextran which
can be used, inter alia, to modify the degradation rate of the
article.
[0073] Useful inorganic particulate materials include materials
that contain significant amounts of (or that consist essentially
of) titanium oxide, silicon oxide, carbon, aluminum oxide,
hydroxide and oxy-hydroxide, calcium carbonate, feldspar, and
kaolin. Because many such inorganic particulate materials are
obtainable at lower cost than the cost of the organic constituents
of the chewable articles, their use can lower the overall cost of
producing the article. In addition, they have greater stiffness
than the organic constituents, and can provide coloration and
hiding power to the articles.
[0074] Generally larger particulates may be incorporated into the
chewable articles in an effort to engineer the "mouth feel," which
is the combination of consistency and texture that create a
particular set physical sensations in the animal's mouth. For
example, dogs often favor a "bumpy" texture. Dispersing larger
particulates such as sand or other minerals throughout the article
can enhance the bumpy texture.
[0075] Also useful are materials to modify the color, taste and
aroma of the articles. Dyes, primarily food dyes, are especially
important. Taste/aroma agents include materials derived from animal
fats or animal skins as well as garlic and other vegetable
products. Salt and other spices may also be used. Sorbitol can
impart a pleasant taste in addition to serving as a plasticizer.
Taste agents may be incorporated using particulates as
vehicles.
[0076] A chewable article of any desired shape or size is formed
from the biodegradable organic polymer compositions described above
using methods well-known in the art.
[0077] Having now generally described the invention, the same will
be more readily understood through reference to the following
examples which are provided by way of illustration, and are not
intended to be limiting of the present invention, unless
specified.
EXAMPLE
[0078] 12 lbs. of wheat starch powder, 4.0 lbs of low density
polyethylene, 2.4 lbs. of sorbitol, 1 lb. of ethylene vinyl acetate
grafted with maleic anhydride, 0.2 lbs of salt, and 0.4 lbs of
fiber are blended and mixed together in a mixer. The fiber is
comprised of cotton fiber of average length .about.1 mm, and
average L/D ratio of .about.62.
[0079] The mixed batch is processed through an extruder at a
temperature of 300.degree. F. A rotating blade at the exit die of
the extruder cuts the material into pellets. The pellets are
suitable for injection molding into an appropriate shape for a
chewable article.
[0080] The references cited above are all incorporated by reference
herein, whether specifically incorporated or not.
[0081] Having now fully described this invention, it will be
appreciated by those skilled in the art that the same can be
performed within a wide range of equivalent parameters,
concentrations, and conditions without departing from the spirit
and scope of the invention and without undue experimentation.
[0082] While this invention has been described in connection with
specific embodiments thereof, it will be understood that it is
capable of further modifications. This application is intended to
cover any variations, uses, or adaptations of the invention
following, in general, the principles of the invention and
including such departures from the present disclosure as come
within known or customary practice within the art to which the
invention pertains and as may be applied to the essential features
hereinbefore set forth as follows in the scope of the appended
claims.
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