Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02277695 2008-01-07
Disposable Objects Made From Corn Cob
Field of the Invention
The invention relates to disposable objects made from plant parts, and in
particular objects
made from com cob or straw, such as rice straw and wheat straw.
Background of the Invention
Disposable objects, such as utensils (e.g. forks, knives, spoons chopsticks
etc.) and
containers (e.g. bowls, plates, cups, glasses, pans, saucers, flower pots,
boxes (e.g.
detergent boxes, coolers), bottles, etc.) are in great demand. At the present
time, many
disposable products are made from foam. Foam is used because it is
inexpensive. Foam
products often emit toxic substances during the manufacturing process. When
disposed of,
the foam products will not decompose and they harm the environment. Other
materials,
such as plastic, can have the same effect on the environment.
Some products are biodegradable, such as those made from wood fibers. Wood
fiber
products will decompose naturally, but the raw materials are increasingly in
short supply and
expensive. Plant husks have been used to make biodegradable products, but
husks are also
unsatisfactory because they often do not produce a durable, well formed and
economical
product.
There is a clear need to identify other sources of raw materials for making
disposable
products. A suitable raw material has to be abundant and inexpensive. It also
must be
environmentally friendly so that the final product will naturally decompose.
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Summary of the Invention
The invention relates to disposable objects made from plant parts, and in
particular objects
made from com cob or straw, such as rice straw and wheat straw. The plant
parts are in a powder form
and held together by a non-toxic binding agent.
Preferably, wheat straw, rice straw or corn cob (or combinations of the
foregoing) is cleaned,
dried, ground and screened to obtain the grain with a size of about -10 to -
90. Other ranges such as
about -60 to -120 or +30 to -50 may also be used. Resinous agent is added and
blended with the
wheat straw, rice straw and/or corn cob. The mixture is dried to less than
about 15% moisture and
preferably less than about 10% moisture and shaped into products, preferably
utensils and containers,
such as bowls, plates, cups, chopsticks, flower pots, bottles or boxes. It is
preferably shaped in a high
pressure (about 240 ton) press at about 90 C to 1900 C for about 35 to 45
seconds. Temperature and
pressure may be varied and suitable temperatures and pressures would be
apparent to a person skilled
in the art.
In one embodiment, the composition may be folded over on itself a plurality of
times to form a
laminated sheet.
This invention preferably utilizes agricultural byproducts which are abundant
and
inexpensive. Containers of the invention are capable of holding high
temperature liquid.
They are also easily shaped without cracking. Finally, =the containers are
naturally
biodegradable and environmentally friendly.
The invention relates to a molding composition including: a) corn cob powder
or straw
powder; and b) a resinous agent; wherein the composition is capable of being
shaped into a
molded object. In one embodiment, the molding composition includes:
a resinous agent about '15% - 45% by weight
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b viscosity reducing agent about 5% - 20% by weight
c whitening or coloring agent about 1% - 15% by weight
d lubricating agent about 0.1 % - 5% by weight
e straw powder
or corn cob powder about 50% - 70% by weight by weight;
wherein the composition is capable of being shaped into a molded object.
The composition is preferably shaped by injection molding. The grain size of
the
powder is preferably about -10 to -90 (#10 - #90 HWR mesh sizes, with an
average diameter
of 0.1 mm to 0.09mm). The corn cob or straw is preferably present in about 50%
- 70% by
weight. A suitable resinous agent is urea formaldehyde resin. The resinous
agent is
preferably present in about 15-45% by weight. Suitable straw includes wheat
straw, rice
straw, canola straw, sunflower straw, cereal straw, Secale cereale straw and
plant straw.
The composition may further include a viscosity reducing agent. The viscosity
reducing
agent may be talcum powder. A lubricating agent, such as zinc stearate, may
also be used.
The composition may further include a whitening agent or a coloring agent,
such as the
whitening agent rutile titanium dioxide. The coloring agent may be food
coloring, dye, or an
edible dye.
The composition may further include a viscosity reducing agent in about 5% -
20% by
weight, a coloring agent or whitening agent in about 1%-15% by weight and a
lubricating agent
in about 0.1 %- 5% by weight.
In one aspect, the invention is molding composition including:
a Urea Formaldehyde resin about 15% - 45% by weight
b Talcum Powder about 5% - 20% by weight
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c Rutile Titanium Dioxide about 1% - 15% by weight
d Zinc Stearate about 0.1 % - 5% by weight
e wheat straw powder, rice straw powder
or corn cob powder about 50% - 70%%
the composition is capable of being shaped into a molded object.
The invention also includes a container, sheet or utensil made from a
composition of
the invention.
Another aspect of the invention is a method of producing a molding composition
from
straw or corn cob, including:
a) grinding the straw or com cob into powder;
b) mixing the powder with resinous agent to form a composition suitable for
molding.
The invention includes a composition prepared according to the method.
Another aspect of the invention is a method of producing a molded object,
including
forming a molded object from a molding composition including straw or corn cob
and
resinous agent. The invention includes a composition prepared according to the
method.
The invention also includes molded object prepared according to a method of
the invention.
The invention includes a method of producing a molded object, including
a) grinding straw or corn cob into powder;
b) mixing the powder with resinous agent to form a composition suitable for
molding and
c) forming a molded object from the composition.
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The invention also includes molded object prepared according to the method.
The molded object may be formed by shaping the composition between first and
second die members.
The method may further include subjecting the container to a second shaping
step. The
method preferably includes cooling the object.
The method may optionally include applying a surface coating to the object to
form a
protective and/or esthetic coating and drying the coating.
The composition is preferably shaped by injection molding. In the methods of
the
invention, the com cob or plant straw is preferably present in about 50% - 70%
by weight. The
resinous agent preferably comprises urea formaldehyde resin.
The resinous agent may be present in about 15% - 45% by weight. The straw is
preferably selected from the group including wheat straw, rice straw, canola
straw, sunflower
straw, cereal straw, Secale cereale straw and plant straw.
The method may further include a viscosity reducing agent, such as talcum
powder. The
method may further include a lubricating agent. The lubricating agent
preferably includes
zinc stearate. The method may also include a whitening agent or a coloring
agent. A
whitening agent is rutile titanium dioxide. A suitable coloring, dye agent is
food coloring or an
edible dye.
The method may further include adding to the composition a viscosity reducing
agent
in about 5% - 20% by weight, a coloring agent in about 1%-15% by weight and a
lubricating
agent in about 0.1 %- 5% by weight. The shaping step is preferably carried out
when the
composition is approximately 90 to 190 degrees C. The shaping is preferably
conducted at a
pressure exerted on the product of about 240 tons.
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Detailed Description of the Invention
Wheat straw, rice straw, and corn cobs are the preferred raw materials for use
in
preparation of the compositions and objects of the invention. Many other
suitable straws for
preparation of objects such as containers and boxes will be apparent to those
skilled in the
art. The objects are preferably waterproof, heat resistant, non corrosive, non-
toxic, non-
polluting, easy to decompose and not harmful to the environment. After one or
more of these
types of plant parts is cleaned, dried, ground into powder, mixed with
resinous agent and
placed in a high pressure press, it can be formed into the final product.
These products can
withstand high temperatures and water. The products are also safe to contact
food and will
decompose after they are discarded.
Part or all of the corn cob may be used. The outer part of the core, the woody
component, is preferable because it is hard and dense. The pith and chaff
components are
softer and lighter and may also be used.
The term "straw" includes all parts of the plant except the grain, seed husk,
and roots.
Thus, the invention makes use of abundant agricultural by-products which may
otherwise be
wasted.
Straw and corn cob have little fibrous material so it was previously thought
that they
were too soft to be useful for forming objects. It was considered that they
would suffer
cracking or not perform properly in the shaping process. As well, corn cob is
often
unavailable because after harvest it is broken down and used for fertilizer or
feed. Grinding
these plant parts into a fine powder was not considered which is shown by the
unavailability
of equipment to grind these products into a fine powder.
The following example uses corn cobs. The same procedures (with minor
modifications that would be apparent to a person skilled in the art) have been
applied to
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make products from wheat straw and rice straw and can also be used with other
straws and
plant parts.
The following is a detailed description of a manufacturing process:
a Collect the corn cobs (raw material).
b Clean and rinse the corn cobs.
c Dry the corn cobs (preferably in an oven)
d The corn cobs are put into a grinder and ground to about -80.
e The powder is then put through a screener to screen out larger grain.
f The resinous agent (e.g. urea formaldehyde resin) is blended into the corn
cob
powder.
g The blending must be thorough in order to obtain the optimal result.
h The blended powder is weighed to obtain the correct amount (the correct
amount is
variable according to the product desired, but can be determined by a person
skilled
in the art).
i The powder is placed into a mold preheated to 130 C (preferably from 130 to
165
C). Injection molding is preferred.
The mold is placed into a 240 ton hydraulic press for about 10 seconds.
k Pressure is released for about 8 seconds.
I Wait for about 12 seconds for the product to cool and set and then take the
product
out.
When only resinous agent (e.g. urea formaldehyde resin) and powder (e.g. wheat
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straw, rice straw or corn cob) are used, the preferred range of resinous agent
is about 10 -
45% and the preferred range of powder is about 60 - 90%.
Optionally, one or more of a viscosity reducing agent (e.g. talcum powder), a
lubricating agent to allow separation of the product from the mold (e.g. zinc
stearate) and a
coloring or whitening agent (e.g. whitening agent rutile Ti02) may be added in
step f.
Example of amounts of ingredients for preparation of 5 plates with straw
Composition - % Weight
Wheat Straw Powder 60% 60g
Resinous Agent 25% 25g
Viscosity Reducing Agent 8% 8g
Whitening Agent 4% 4g
Lubricating Agent 3% 3g
TOTAL 100% IOOG
Injection molding is preferred. This can be done by conventional injection
molding
techniques, for example by shaping the heated composition between first and
second die
members. The composition may be shaped into many molded objects including
utensils,
containers, trays and sheets.
Additional shaping steps may be taken. The final product may be finished, for
example applying a surface coating such as a coloring or a gloss. The coating
may form a
protective, waterproofing and/or esthetic coating.
The composition may be altered in order to alter the rate of decomposition.
The
formula may also be altered to make a product more or less rigid.
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Preferred agents and amounts (by weight):
a Urea Formaldehyde resin about 15% - 45%
b Talcum Powder about 5% - 20%
(preferably Mg3(Si4010)(0H2) or another talcum powder suitable for use with
humans
or other mammals. 3MgO4SiO2H2O may be used where appropriate.)
c Rutile Titanium Dioxide about 1% - 15%
d Zinc Stearate about 0.1 % - 5%
15-45% urea formaldehyde resin may also be used. The urea may be in liquid
form or
powder form.
The present invention has been described in detail and with particular
reference to the
preferred embodiments; however, it will be understood by one having ordinary
skill in the art that
changes can be made thereto without departing from the scope of the invention.
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