U.S. patent application number 11/845886 was filed with the patent office on 2007-12-20 for corn stover blanket and method of making the same.
This patent application is currently assigned to Mat, Inc.. Invention is credited to Joseph Karpik.
Application Number | 20070292217 11/845886 |
Document ID | / |
Family ID | 38861724 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070292217 |
Kind Code |
A1 |
Karpik; Joseph |
December 20, 2007 |
CORN STOVER BLANKET AND METHOD OF MAKING THE SAME
Abstract
A revegetation blanket formed from fibers, the fibers formed
from corn stover and methods of making and using the same.
Inventors: |
Karpik; Joseph; (Floodwood,
MN) |
Correspondence
Address: |
VIDAS, ARRETT & STEINKRAUS, P.A.
SUITE 400, 6640 SHADY OAK ROAD
EDEN PRAIRIE
MN
55344
US
|
Assignee: |
Mat, Inc.
Floodwood
MN
|
Family ID: |
38861724 |
Appl. No.: |
11/845886 |
Filed: |
August 28, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11143342 |
Jun 2, 2005 |
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11845886 |
Aug 28, 2007 |
|
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60628731 |
Nov 17, 2004 |
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Current U.S.
Class: |
405/302.7 ;
162/23; 162/97 |
Current CPC
Class: |
E02D 3/00 20130101; D04H
1/04 20130101 |
Class at
Publication: |
405/302.7 ;
162/023; 162/097 |
International
Class: |
D21B 1/30 20060101
D21B001/30; D01C 1/00 20060101 D01C001/00 |
Claims
1-13. (canceled)
14. A method of making a blanket, the method comprising the steps
of: a) harvesting a corn crop to obtain corn stover material; and
b) defibrating said corn stover material to form stover fibers.
15. The method of claim 14 further comprising the step of mixing
with said corn stover fibers at least one member selected from the
group consisting of bonding fibers, adhesives, thermoplastic
resins, thermosetting resins, waxes, natural fibers, synthetic
fibers, wetting agents, colorants, perfumes, netting, fire
retardants, and mixtures thereof.
16. The method of claim 14 further comprising the step of
positioning said blanket for erosion control, revegetation,
livestock or plant retention.
17. The method of claim 16 further comprising the step of adding a
scrim or netting to said blanket.
18. The method of claim 16 the blanket comprising a bonding fiber
comprising a coating of a thermoplastic adhesive, the method
further comprising the step of heating the blanket to a temperature
sufficient to cause the hot melt adhesive to flow.
19. The method of claim 14 the corn stover material comprising
substantially corn stalk and corn leaves.
20. The method of claim 14 wherein said method is a dry method
wherein said corn stover material has a moisture content of about
10% to about 30% by weight.
21. The method of claim 14 further comprising the step of ensiling
wherein said ensiling comprises adding water, inoculants,
preservatives and mixtures thereof to said corn stover material
prior to defibrating.
22. The method of claim 14 wherein said defibrating is done
thermo-mechanically.
23. (canceled)
24. A method for controlling erosion from soil with a blanket used
as a temporary ground cover, the method comprising: providing a
degradable erosion control blanket in a roll form the degradable
erosion control blanket comprising about 25 to 99 wt-% corn stover
fibers and about 1 to 5 wt-% polymeric binder fibers, and any
remainder being selected from the group consisting of other natural
fibers and synthetic fibers and mixtures thereof; unrolling said
blanket on said soil; and securing said blanket into place.
Description
CROSS-REFERENCE TO RELATED U.S. PATENT APPLICATIONS
[0001] This application claims priority from U.S. provisional
patent application No. 60/628,731 filed Nov. 16, 2004, the entire
content of which is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to a blanket or mat made from corn
stover and/or fibers made from corn stover which can be used for a
variety of agricultural, landscaping, and livestock purposes, and
to processes of making and using the same.
BACKGROUND OF THE INVENTION
[0003] Conventional processes for producing revegetation/erosion
controlling blankets already exist. Most utilize various wood,
paper, synthetic/adhesive fibers and blends thereof. The blankets
are then reinforced with top-netting. Processes for producing a
blanket-like mat are well known in the industry.
[0004] For example, U.S. Pat. No. 4,635,576 describes a soil
erosion control blanket formed from a mat of interlocking woodwool
fibres, the mat of woodwool being retained as a coherent structure
by means of longitudinal rows of stitching giving the blanket a
quilted appearance.
[0005] U.S. Pat. No. 4,580,960 discloses a mat product applied over
soil to provide a favorable growth medium for seeds or
seedlings.
[0006] U.S. Pat. No. 4,418,031 describes a moldable fibrous mat
from which a product of predetermined shape can be molded by the
application of heat and/or pressure. The mat consists essentially
of base fibers and carrier fibers with the base fibers having a
substantially higher softening temperature, if any, than the
carrier fibers. The base and carrier fibers may be either virgin or
reclaimed. Suitable base fibers are made of materials such, for
example, as wood, jute, sisal, cotton, coconut, kapok, rayon,
acetate, triacetate, paper, graphite, glass, mineral wool, and
other synthetic and natural fibers. Fibers of cellulosic material
maybe stressed. Wood fibers constitute an example of such a
cellulosic material.
[0007] U.S. Pat. No. 4,353,946 discloses a shredded wood wool fiber
mat which is retained in a coherent structure using a biodegradable
plastic mesh.
[0008] U.S. Pat. No. 3,577,312 discloses a mat formation process
used to form the wood fiber substrate into the inventive mat prior
to thermobonding.
[0009] U.S. Pat. No. 3,010,161 describes a method of producing
fibrous webs using air suspension.
[0010] U.S. Pat. No. 2,757,150 discloses a process used to produce
wood fibers using "thermo-mechanical" defibration.
[0011] Corn stover is made from the corn plant, including the stalk
and leaves but excludes the corn kernel, tassel and cob. Corn
stover is a main waste product of the corn producing industry.
[0012] Current approaches to recycling corn waste materials are
limited and usually include being chopped, spread over the field
and tilled under to decompose or being processed and ensiled as
silage for livestock feed. The use of corn stover as a blanketing
raw material constitutes a value added product option to the grain,
specifically corn, producer.
[0013] It would be beneficial to employ corn stover in a blanket
product which can be used for livestock, erosion control,
revegetation, potting purposes, for bare root plants, and other
agricultural purposes.
SUMMARY OF THE INVENTION
[0014] The present invention relates to a corn stover blanket or
mat product and to a method of making the same.
[0015] In one embodiment, the method includes the steps of corn
stalk material, defibrating the corn stalk material to form stover
fibers, and mixing the corn stover fibers with other optional
materials such as synthetic fibers and/or other suitable natural
fibers, resins, adhesives, dyes, perfumes, etc., as desired.
[0016] Optionally, a netting may be incorporated into the blanket
or mat as well or the blanket/mat may be formed over a netting.
[0017] Suitably, the process herein is a dry process.
[0018] In another aspect, the present invention relates to a
process for producing a blanket or mat formed with corn stover, the
process including the steps of harvesting the corn stover and
thermo-mechanical defibrating the corn stover.
[0019] In one embodiment, the process is a substantially dry
process for forming a blanket-like product from corn stover and
other fibers wherein the corn stover material or corn stover fibers
never reach a moisture content greater than about 25 wt-% to about
30 wt-%. Such an embodiment therefore employs limited amounts of
water relative to other processes in which a slurry of the recycled
waste product is prepared.
[0020] The blanket/mat product can be formed into a continuous roll
and packaged for later sale.
[0021] The blanket/mat product has desirable erosion controlling
and revegetating qualities and may be formed such that it is
biodegradable.
[0022] Erosion control/revegetation blankets/mats are used as a
temporary ground cover over newly seeded areas of ground. The
blankets/mats are unrolled and stapled or staked into place on mild
slopes or flatter areas and left to degrade as the underlying seeds
germinate and vegetation grows.
[0023] Other aspects of the invention are described in the Detailed
Description and in the claims below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a flow chart illustrating an embodiment of the
process of making a blanket product according to the invention.
[0025] FIG. 2 is a side partial cut-away view of an apparatus used
to form a corn stover mat.
DETAILED DESCRIPTION OF THE INVENTION
[0026] While this invention may be embodied in many different
forms, there are described in detail herein specific embodiments of
the invention. This description is an exemplification of the
principles of the invention and is not intended to limit the
invention to the particular embodiments illustrated.
[0027] All published documents, including all US patent documents,
mentioned anywhere in this application are hereby expressly
incorporated herein by reference in their entirety. Any copending
patent applications, mentioned anywhere in this application are
also hereby expressly incorporated herein by reference in their
entirety.
[0028] The present invention relates to a blanket/mat which can be
employed for a variety of purposes such as for livestock, for
revegetation, for erosion control, for potting purposes, for bare
root plants, and other horticultural or agricultural purposes, and
to methods of making and using the same.
[0029] The invention provides a blanket/mat product and process for
making the blanket/mat product using recycled harvested corn plant
waste.
[0030] As used herein, the term "corn stover materials" shall
hereinafter be used to refer to the raw, unprocessed materials of
the corn plant including the stalk and leaves. Desirably, the corn
kernel, tassel and cob are excluded. Desirably, the stalk is cut at
a point above the ground so as to avoid contaminants from the
soil.
[0031] As used herein, the term "corn stover fibers" shall
hereinafter be used to refer to the processed materials or
defibrated corn stover material. Desirably, the corn kernel,
tassel, and cob, are excluded from the process.
[0032] The process according to the invention generally includes
the step of harvesting the corn stover material, treating the corn
stover material to produce corn stover fibers, and mixing the
stover fibers with other optional ingredients.
[0033] Suitably, the corn stover fibers are stand harvested rather
than employing the conventional baled harvest method, although any
method of harvesting may be employed, there are some advantages to
employing the stand harvest. For example, using the conventional
baled harvest method, more contaminates may be introduced into the
process. Such contaminates can result in increased wear on
machinery and refining parts. Contaminates include, for examples,
sand, rootballs, small rocks, etc. which may be abrasive to
machinery parts resulting in unnecessary wear. Thus, it may be
desirable to stand harvest the corn stover material by removing the
corn stalk at a point above the ground.
[0034] The standing corn crop may be harvested using any suitable
method. In one embodiment, the standing corn crop is harvested
using a method and apparatus as described in commonly assigned U.S.
Pat. No. 5,875,622, the entire content of which is incorporated by
reference herein. Using this method, a John Deere 7700 combine,
modified with an integrated corn stalk chopper and rear forage
blower is employed. This apparatus allows for adjustable cutting
height. Suitably, the stalks are cut so as to leave about 12 inches
to about 15 inches of stalk embedded in the soil in order to reduce
the amount of soil and other contaminants in the collected
harvest.
[0035] The chopper attachments reduce the stalks to varying
lengths. Such lengths may be from about 3 inches to about 4 inches
although this length may be varied.
[0036] Suitably, the harvested corn stover material has a corn
grain content of less than about 2 wt-% and a cob content of less
than about 25-30 wt-%. Harvests having more than about 2 wt-% corn
grain or about 30 wt-% cob content may be reseparated. While such
ranges are preferable, the numbers may vary.
[0037] The harvested corn stover material may have a moisture
content of about 20 wt-% to about 30 wt-%.
[0038] Rapid rehydration, water absorption and retention have been
found to be desirable properties of a blanket/mat according to the
invention for some applications. Thus, it may be desirable to
retain a certain moisture level in the corn stover material. If the
harvested corn stover material is too dry, it is difficult to
rehydrate.
[0039] Corn stover material has a cellular structure. If the
internal moisture of the material is lost, the cells form closed
bubbles resulting in a material which floats in water, but which
itself does not absorb water and rehydrate.
[0040] During thermal treatment of corn stover material, the
moisture in the cells of the corn stover material expands resulting
in bursting of the cell structure which results in openings in the
cells. The open cells exhibit improved absorption and rehydration
properties, and exhibit improved moisture retention as well, as
compared to a closed cell structure, which can occur if the corn
stover material does not have enough internal moisture.
[0041] Thus, in preferred embodiments of the invention, the corn
stover material retains a specific, desirable moisture content
during harvesting and processing into a final blanket/mat
product.
[0042] After harvesting, the corn stover material may be mixed with
water, preservatives and inoculants in a process referred to in the
industry as ensiling. In a preferred process, the moisture content
of the ensiled stover material is between about 30 wt-% and about
70 wt-%. Once ensiled, the corn stover material may be covered
tightly to remove any oxygen and stored in appropriate storage
facilities such as cement bunkers to await further processing.
[0043] The corn stover material may be stored prior to use in the
present invention. For such purposes, it has been found beneficial
to preserve the amount of naturally occurring moisture in the plant
cells during storage and prior to processing as discussed in some
detail above. Thus, the corn stover material may be ensiled wherein
additives including, but not limited to, water, inoculants,
preservatives, etc. may be added to the stover material for
storage.
[0044] One example of a suitable inoculant is Silamax.RTM. 50G, a
lactic acid producing bacteria.
[0045] One example of a suitable preservative is dried
molasses.
[0046] After ensiling, the corn stover material may be reduced to
corn stover fibers, mixed with optional ingredients, and formed
into a final blanket/mat product.
[0047] The process which includes the steps of forming corn stover
fibers from the corn stover material, mixing with optional
ingredients, and forming the mixture into a blanket/mat product,
may be referred to herein as a "substantially dry process" of
making a blanket/mat product.
[0048] The process employed herein, may be referred to as a
"substantially dry process" for making a fibrous blanket/mat
product. As used herein, the term substantially dry shall refer to
a process wherein the during the processing of the corn stover
material into fibers and finally into a final blanket or mat
product, there is no slurry or waste byproduct that has to be
discarded. This is in opposition to a process wherein a wet fiber
slurry of recycled waste fiber products is processed.
[0049] During processing, suitably, the corn stover fibers suitably
have a moisture content of no greater than about 25-30 wt-%, and
more suitably, the moisture content is no greater than about 15
wt-% to about 25 wt-%.
[0050] After ensiling, the corn stover material may then be reduced
to stover fibers. The corn stover materials may be reduced to
stover fibers using any method known in the art. Suitably, the
integrity of the starting stover material can be preserved during
the reducing process.
[0051] Equipment including granulators and/or refiners may be
employed to reduce the corn stover materials to stover fibers. Use
of a refiner in series with a granulator has been found to increase
the volume of stover fibers and improve efficiency. In general, a
granulator may reduce the stover materials to any desired size.
However, the volume of stover fiber that may be processed through a
granulator is typically less than the volume of corn stover that
can be processed through a refiner. Thus, for small volume products
or processes, a granulator alone can efficiently be used to reduce
the corn stover materials to fibers. For larger volume processes, a
granulator can initially reduce the size of large corn stover
materials and then the smaller corn stover materials can be reduced
to stover fibers in a refiner.
[0052] In one embodiment of the invention, the corn stover
materials are initially reduced in size using a granulator, and
then further reduced in length using a refiner.
[0053] In one embodiment, the corn stover material is reduced to
stover fibers using a thermo-mechanical defibrating process wherein
the fibers are heat treated.
[0054] It is desirable to retain as much of the length of the raw
corn stover fibers as possible. Preservation of this length not
only provides for easier processing of the fibers into a
blanket/mat product, but also provides improved properties such as
higher strength, weavability, cohesion and stability to the final
blanket/mat product.
[0055] In general, it has been found that the longer the stover
fibers, the more stable the final product because longer fibers are
more likely to intertwine with one another during processing which
results in higher blanket/mat strength and cohesiveness.
[0056] However, stover fibers which are too long may entangle with
one another and form aggregates which can clog machinery and
increase processing time.
[0057] The length of the corn stover fibers may generally range
from about 0.125 inches to about 1.0 inch in length. Reducing fiber
length below about 0.125 inches results in fibers which are too
short to produce a blanket/mat product having desirable physical
properties, such as tensile strength and durability. Fibers having
a length significantly longer than about 1.0 inch, can increase the
difficulty of processing the fibers into a final blanket/mat
product.
[0058] It is desirable that the majority of stover fibers have a
length of about 0.75 inches to about 1.0 inch as longer fibers are
easier to weave into a final blanket/mat product, and produce and
stronger more cohesive blanket/mat product.
[0059] However, it can be expected in typical process, that the
majority of stover fibers may have a length in the range of about
0.25 inches to about 0.50 inches.
[0060] Although uniform fiber length is desirable, it is difficult
to produce fibers of a uniform length, and in a typical process,
fibers having varying lengths may result. For example, some fibers
may have a length in the range of about 0.25 inches to about 0.50
inches, some may have a length of greater than 0.5 inches, and some
may have a length of less than 0.25 inches.
[0061] In a typical embodiment, it may be expected that about 50%
to about 60% of the stover fibers have a length between about 0.25
inches and about 0.50 inches.
[0062] In one embodiment, it was found that about 50% to about 60%
by weight of the fibers had a length in the range of about 0.25
inches to about 0.50 inches, about 20% to about 30% had a length in
the range of about 0.125 inches to about 0.25 inches, and about 20%
to about 30% had a length in the range of greater than 0.50
inches.
[0063] A preferred embodiment may include a mixture of stover
fibers wherein about 75 wt-% of the fibers have a length of greater
than about 0.50 inches and about 15 wt-% have length less than
about 0.25 inches.
[0064] The corn stover material may then be mixed with a variety of
optional ingredients. Optional ingredients which may be
incorporated into the blanket/mat product may include, but are not
limited to, bonding fibers, adhesive compositions, resins,
thermo-plastic resins, thermo-setting resins, hot melt adhesives,
waxes, wetting agents, colorants, perfumes, netting, inoculants,
preservatives, fire retardants, synthetic fibers, other natural
fibers, polyester and co-polymers thereof, polyamid and co-polymers
thereof, polyolefin and co-polymers thereof, acetate, rayon,
cotton, leather, wool, coconut, kanaffe and jute, and mixtures of
any of the above. One or more of these optional ingredients may be
incorporated with the corn stover fibers by blending or mixing, for
example.
[0065] Optionally, bonding fibers, adhesive compositions or other
bonding agents may be incorporated with the corn stover fibers to
improve adhesion and therefore cohesion and strength of the final
mat product. Such optional materials may be incorporated using any
suitable method known in the art such as by blending, spraying,
dipping, brushing, etc.
Bonding Fibers
[0066] Bonding fibers are those fibers that can be added to provide
adhesion to the mat product so as to adhere the corn stover fibers
together thereby providing a more cohesive, higher strength final
blanket product. These fibers may be polymeric in nature and may be
thermoplastic, for example. When heated to a temperature sufficient
for a particular fiber product, the product becomes sufficiently
fluid and when cooled, is sufficiently adhesive to adhere the
fibers together. The adhesion achieved via the bonding fibers is
sufficient to permit movement of the formed but non-cured mat.
[0067] The bonding fibers may also have an adhesive coating thereon
which when heated, becomes fluid and when cooled has sufficient
adhesion to adhere to the corn stover fibers. Such bonding fibers
are typically synthetic fibers coated with hot melt or
thermoplastic adhesive coating. Any bonding fiber that has a melt
temperature which is less than that of the stover may be employed
herein. Examples of suitable synthetic bonding fibers include, but
are not limited to, polyester fibers, polyamide fibers,
polyethylene fibers, acetate fibers and rayon fibers. Natural
cotton fibers or other natural fibers can also be employed herein.
One commercially available bonding fiber suitable for use herein is
CELLOBOND.RTM. 105 (Hoechst Celanese).
[0068] Bonding fibers may have a length of about 0.5 to about 1.5
inches, and have a denier of about 3. It is desirable that such
fibers can be uniformly dispersed with the stover fibers and other
components during the blending process.
Resins or Polymers
[0069] Resins or polymers may optionally be incorporated with the
corn stover fibers. These resins or polymers may be thermoplastic
or thermosetting in nature. Thermoplastic polymers or resins may
have melting temperatures in the range of about 85.degree. F. to
about 350.degree. F. This range is intended for illustrative
purposes only, and the melting temperature may fall outside of this
range for some materials. The resins, as the bonding fibers, may
also be added to adhere the fibers together and to therefore
increase the durability, stability and cohesion to the final
blanket/mat product. They also can be added to improve moldability,
particularly the thermoplastic resins or polymers. Resins useful in
the present invention are preferably thermoplastic, and are also
preferably recyclable. Thermoplastic resins are preferred over
thermosetting resins because it is easier to reshape and recycle
thermoplastic resins. Thermosetting resins tend to have less
flexibility. Thermoplastic resins can be heated to their molten
state during the pressing process, explained below, once
solidified, improve the cohesion of the final stover product.
[0070] The addition of thermoplastic resins or polymers to the
composition facilitates molding of the final product into
particular shapes and sizes. However, it is noted that the stover
fiber product of the invention can be obtained without use of a
resin.
[0071] Examples of suitable classes of thermoplastic resins or
polymers include, but are not limited to, polyamides,
co-polyesters, styrene co-polymers, thermoplastic urethanes and
polyurethanes, etc. Specific examples of polymers or resins useful
herein include, for example thermoplastic polyurethanes
commercially available from BASF; thermoplastic polyolefins
commercially available from Dow Plastics; styrene block co-polymers
commercially available from Dexco Polymers; and thermoplastic
polyamides and copolyesters commercially available from Elf
Atochem.
[0072] Thermosetting products are available from the H.B. Fuller
Co. in St. Paul, Minn.
[0073] Specific examples of suitable resins or polymers are
included in the table below. TABLE-US-00001 TABLE 1 Resin Type
Source City, State Aspun .RTM. 6835A TP Dow Plastics Freeport, TX
6811A 6806A 6831A 6830A Vector .RTM. 6241D TP Dexco Polymers
Houston, TX 6400D 8550D 2518D Platamid .RTM. H005 TP ELF Atochem
Philadelphia, PA H103 M548 Fulatex .RTM. PN 3408 TS HB Fuller St.
Paul, MN (TP = thermoplastic; TS = thermoset)
[0074] It is desirable that the resin is easily dispersed during a
mixing stage, for example, and that the resin flows upon heating,
such as with a thermoplastic resin, or prior to curing, such as
with a thermoplastic resin, such that the corn stover fibers obtain
a sufficient coating of the resin. It is undesirable for the resin
to coagulate or agglomerate into clumps during processing. Resins
which have been ground into a powder prior to mixing with the
stover fibers may be preferable for use herein. Resin powder is
generally readily dispersed during mixing and melts evenly and
quickly. Thus, if resin pellets are used, for example, preferably
the pellets are ground typically to not greater than 70 mesh, prior
to adding the resin to the composition.
[0075] Resin selection may vary with the end use of the stover
product. For example, if a styrene block copolymer is used, then
the amount of styrene in the copolymer can determine whether the
stover mat product is soft or hard. Too much resin can result in a
hard, brittle end product, and too little resin can result in lack
of cohesiveness in the final blanket/mat product resulting in a
blanket/mat product which is not stable. If resin is employed, an
illustrative ratio may be about 60:40 to about 90:10 fiber to
resin.
Other Additives
[0076] Other optional ingredients may also be incorporated with the
corn stover fibers, for example, to facilitate processing and
formation of the reconstituted stover product, and to help maintain
the desired appearance and physical properties. These additives
include, but are not limited to, wetting agents, colorants, fire
retardant additives, as well as other fibers for improving the
strength and woven appearance of the product.
[0077] Optionally, fibers other than the corn stover fibers or
bonding fibers described above may be incorporated into the
composition to improve the physical properties such as strength and
durability as measured by slit and stitch and/or to improve the
appearance of the final product such as the woven nature. The type
and amount of additive fiber used varies with the desired strength
and end use of the stover product.
[0078] Suitably, the optional additive fibers are long, for example
in the range of about 0.75 to about 1.50 inches, are high strength,
having a denier of about 15. Suitable additive fibers also easily
intertwine with the stover fibers and/or bonding fibers so as to
provide strength to the final product. Examples of suitable fibers
include, but are not limited to, polyester, polyamide,
polyethylene, acetate, rayon, cotton and other natural or synthetic
fibers. Additive fibers are especially useful when the corn stover
fibers and/or bonding fibers, for example, are relatively
short.
[0079] The optional fibers may be the same as or different than the
bonding fibers, but may lack the adhesive coating, in the case of
some bonding fibers.
[0080] One specific example suitable optional additive fiber
product is the Trevira.RTM. polyester fiber 103 commercially
available from Hoechst Celanese of Salsbury, N.C., of 15
denier.
[0081] Another suitable commercially available additive fiber is
Fybrel.RTM.-901 available from MiniFibers in Johnson City, Tenn.
The addition of about 10 wt-% of the polyethylene product,
Fybrel.RTM.-901 based on the total composition weight, for example,
may provide a strong product that has increased slit and stitch
values when compared with the same product having no additive
fiber.
[0082] A wetting agent can also be added during the blending
process. A wetting agent can facilitate the complete dispersion of
the resin throughout the mixture. Particular wetting agents are
used and/or sold with particular types of resins. Preferably, the
wetting agents are recyclable.
[0083] Fragrance agents and coloring agents, such as dyes, may also
be added during a blending process in order to impart desired odor
and color to the final product. Dyes and coloring agents are known
to those of skill in the art. Any suitable dyes or coloring agents
known in the art may be employed herein.
[0084] Ingredients which impart water repellency to the final
blanket/mat product, such as waxes, may also be incorporated into
the blanket/mat product herein, such as during the blending
process. Such ingredients may also be sprayed or brushed onto the
product, or the product may be dipped in such ingredients.
[0085] It is understood that any components added to the
composition should not interfere with the structural or physical
integrity of the stover fibers. Furthermore, any components added
to the composition desirably do not interfere with the bonding, of
the polymers or resins, or the bonding fibers. Suitably, each
component added to the composition is recyclable and/or
biodegradable.
[0086] The components may be added to the stover fibers using any
suitable method known in the art. One method is to blend the
ingredients together in a mixing device, for example, such as a
Waring.RTM. blender. It is desirable that the mixture be relatively
uniform throughout.
[0087] Limited amounts of water may be added during the blending
process in order to maintain the moisture level of the stover
fibers at least at about 10 wt-% to about 25 wt-% of the stover
fibers. It is most desirable to maintain a moisture content of
about 15 wt-% for optimum processing and end results. However, it
is desirable to have a minimum amount of freestanding water in the
mixing vessel; however the amount of water should not be sufficient
to permit a slurry to form. It is less economical to form a slurry
because of water removal and/or waste slurry disposal.
[0088] If the amount of moisture is greater, the time of blending
may be increased to remove more water during this step. Suitable
temperatures for use during the blending step may depend on the
melting temperature of the ingredients added. In order to ensure
evaporation of excess water, however, blending temperatures must be
at least about 100.degree. F.
[0089] It is desirable that the stover fibers form the largest part
of the total composition by weight. Such amounts will vary
depending on the end use of the stover blanket/mat product formed
herein. A minimum amount of the optional additive fibers including
the bonding fibers or synthetic fibers described above may be used
in order to ensure enough cohesion in the final blanket/mat
product.
[0090] Suitably the amount of stover fiber is about 50 wt-% to
about 80 wt-% of the final blanket/mat product. In one embodiment,
between about 55 wt-% to about 65 wt-% of the stover fibers are
employed.
[0091] Bonding fibers are suitably present in amounts of about 0
wt-% to about 20 wt-%, more suitably about 0 wt-% to about 10 wt-%
of the final blanket/mat product. In some embodiments, it may be
desirable to employ more than 20 wt-% of the bonding fibers. In one
embodiment, up to about 5 wt-% of polyester fibers having an
adhesive coating thereon are employed.
[0092] After blending, the composition may be formed into a
blanket/mat product immediately, or the composition may be stored
for a time prior to the forming process.
[0093] The composition may then be transferred to a former, for
forming into a blanket or mat. If the mixture is transferred
directly from the mixing vessel to the former, it may be done via
feeding or pre-feeding equipment, suitably metered equipment. Such
feeding or pre-feeding equipment is available from Rando Machine
Corp. in Macedon, N.Y. under the tradename of Rando Prefeeder.RTM.
and Rando Feeder.RTM..
[0094] Any suitable equipment for forming the blanket or mat
products described herein may be employed. One example is a mat or
blanket former which includes an air laid forming process. An
example of a commercially available former of this type is one
produced by Rando Machine Corp. in Macedon, N.Y.
[0095] In using the air-laid former, typically the blended mixture
is poured onto screens which are subjected to air blown against the
top of the screen. During the air-laid process, typically heavier
elements of the stover fiber mixture settle to the bottom of the
formed product, whereas lighter materials are positioned proximate
to the top.
[0096] Optionally, a netting may also be incorporated into the
blanket of the invention for further reinforcement, for example.
The netting may be formed from biodegradable materials such as from
biodegradable polymeric materials such as
polyhydroxyvalerate-hydroxybutyrate, polycaprolactone, polylactic
acid, and mixtures thereof. The blanket/mat can also be formed onto
the netting.
[0097] The resultant blended product may then be employed to form a
final blanket/mat product.
[0098] The process employed herein, while some moisture is suitably
retained in the corn stover fibers, may be referred to as a
"substantially dry process" for making a fibrous blanket product or
mat. As used herein, the term substantially dry shall refer to a
process wherein during formation of the blanket/mat product, the
corn stover fibers have a moisture content which does not exceed
about 25-30 wt-% and more suitably, the corn stover fibers have a
moisture content of no more than about 15 wt-%. A wet fiber slurry
is not typically formed using the present invention, as opposed to
other processes wherein wet fiber slurries of recycled waster fiber
products are processed.
[0099] If the fibers have a moisture content of significantly less
than about 10 wt-%, it has been found that the fibers become
brittle and inflexible, and generate significant amounts of dust.
The existence of dust and reduced moisture content for the fibers
may increase the risk of the fibers charring or spontaneously
combusting. Furthermore, dryer fibers result in blanket/mat product
which has less strength and less cohesion, and holes may develop in
the final blanket/mat product.
[0100] Stover fibers having a moisture content of significantly
greater than about 25%, result in diminished processing efficient
and increased processing costs.
[0101] Turning now to the figures, FIG. 1 illustrates generally at
10, by way of a flow chart, one embodiment of a process of making a
corn stover blanket/mat product according to the invention.
[0102] Corn stover material can be initially reduced into fibers
using any suitable means known in the art. In the embodiment shown
in FIG. 1, corn stover materials are placed in a granulator 12
which reduces the corn stover material into smaller parts for
further processing by cutting. The raw corn stover materials may be
transported in the form of enlarged bails for processing in the
granulator 12. Upon exit from the granulator, the initially reduced
corn stover material may be transported to a refiner 14 for further
reduction. The initially reduced material may be transported from
the granulator 12 to the refiner 14 using any suitable method known
in the art. In one embodiment, the stover fiber materials are
transferred by a conveyor system (not shown) from granulator 12 to
refiner 14.
[0103] Suitably, in addition to the conveyor system, if necessary,
any suitable method of imparting moisture to the initially reduced
material is also employed. Thus, prior to entry of the initially
processed stover materials into the refiner 14, the corn stover
materials may be preheated and exposed to dry steam such that the
moisture content of the corn stover material is approximately 50
wt-% to 60 wt-%. In one embodiment, the corn stover material was
heated to a temperature of about 250.degree. F.
[0104] Upon exit from granulator 12, the corn stover
material/fibers may contain less than 15% moisture. Thus, if the
conveyor system has the capability of imparting moisture to the
stover materials as they are being transported from granulator 12
to refiner 14, then, if needed, moisture can be added to the stover
fiber materials at this stage. Enough water should be added such
that the moisture of the stover fiber materials entering the
refiner 14 is at least 10% by weight.
[0105] The moisture content of a known sample stover material may
be measured using a moisture meter, such as that commercially
available from Denver Instruments as Model No. 1R-200.
[0106] Throughout the reduction process, it is desirable to retain
at least about 10 wt-% to about 25 wt-% moisture in the fiber
material. The increased moisture content and heat assists to breaks
down the stover fibers and further retards the chance of charring
or burning of the fibers in the refiner 14. Furthermore, the
moisture facilitates reduction of the fibers without creating
significant amounts of stover dust which can spontaneously combust.
However, it is not desirable to have a sufficient volume of water
to create a slurry. Creation of a slurry decreases the efficiency
of the process because excess water and slurry waste must then be
removed from the process.
[0107] Another method of transporting the material from the
granulator to the refiner is by metering through an auger and feed
system to establish a uniform weight of product prior to entering
refiner 14.
[0108] It is desirably to maintain the temperature in the refiner
between about 200.degree. F. to about 300.degree. F., and more
preferably between about 220.degree. F. and about 250.degree. F.
Temperatures of about 350.degree. F. or more, can result in a
significant amount of the stover material charring or burning in
the refiner 14.
[0109] Suitable refiners are those having metal plates wherein
stover material parts are converted to fibers by destruction of the
matrix around the fibers while maintaining fiber integrity. One
example of a suitable commercially available refiner is available
Andritz, Sprout & Bauer of Springfield, Ohio. In one
embodiment, refiner 14 has two has two opposed metal plates that
are applied to the stover material and rotated so as to tear the
stover material apart, thereby releasing the fibers. Any suitable
metal refining plates may be employed herein. Various size metal
plates can be used depending upon the desired fiber size.
[0110] One example of commercially available refiner plates having
suitable configuration are those available from Durametal
Corporation (Tualaton, Oreg.) formed of C-20 alloy and having a
#336 Circle with a 005/in. TRO taper (#30-36505-217).
[0111] Suitably, refiner 14 is operated at a temperature and mixing
speed that is sufficiently high to permit the stover materials to
be efficiently pulled apart, but the temperature and speed should
not be so high as to cause the stover materials to burn, denature,
or generate significant amounts of dust. Some water may be added to
the stover parts during refining in order to maintain, or to
insure, the moisture in the stover is maintained between about 10
wt-% and about 25 wt-%. The temperature and mixing speed in refiner
14 may be adjusted to prevent dehydration of the stover. If too
much water is added to the stover during the reduction process,
however, stover dust can agglomerate or aggregate and clog the
equipment, which may decrease the tendency for creating a uniform
product.
[0112] The refiner mixing speed varies with the volume of materials
to be processed, the size and type of equipment used and the heat
generated during mixing. Preferably, the mix speed is low enough
that the intensity and strength of the stover material is
preserved, and preferably, the mix speed is high enough so that
processing time is minimized.
[0113] Upon exiting the refiner, if the moisture content of the
stover fibers is greater than about 15 wt-% to about 25 wt-%, it
may be desirable to expose the stover fibers to a dryer immediately
upon exiting the refiner in order to reduce the moisture to a level
of about 15 wt-% or so. The dried stover fibers may then be bailed,
bagged, and/or compressed for storage for further processing, or
they may be immediately processed further. If drying is desired,
the stover fibers may be transferred to any suitable equipment such
as a heating unit and/or cyclone, to adjust the moisture level to
between about 10 wt-% to about 25 wt-%. The heating unit should not
be so warm that it burns or dehydrates the stover fiber. Any
heating unit and/or cyclone known in the art may be used.
[0114] Alternatively, if the moisture level is below about 10% by
weight, water may be added to the fibers prior further processing
of the fibers. However, there should not be so much water added
that the moisture of the stover is greater than about 25% by
weight.
[0115] The stover fibers may then be transferred to a mixer,
blender or other such suitable mixing vessel 16 for blending with
other optional ingredients as desired such as bonding fibers,
resins and optionally other additives, as discussed above. Suitable
mixing vessels include any standard high shear mixing vessel. One
example of a suitable mixing vessel which can be employed herein is
a Waring.RTM. blender. The mixing action provided by a Waring.RTM.
blender does not destroy the integrity of the stover fibers yet
provides enough mixing of the various ingredients to provide a
homogenous mixture. Speeds of about 300 rpm's have been found to be
suitable for use herein. Mixture time can vary depending on the
type of mixing vessel employed. When using a Waring.RTM. blender,
adequate mixing can be obtained in as little as about 1 minute to
about 3 minutes.
[0116] The resultant mixture is a substantially dry mixture in that
a slurry is not formed. Some water may be added during the blending
step in order to maintain a moisture content in the stover fibers
of about 10 wt-% to about 25 wt-%, but not so much that there is
standing water in the blender and not so much as to form a
slurry.
[0117] If too much water is present, the time of the blending step
may be increased so as to evaporate water. A temperature of at
least about 100.degree. F. may be required to efficiently remove
water.
[0118] After blending, the composition may be stored for later use,
or may be employed immediately to form a blanket/mat product. As
shown in FIG. 1, the composition is transported from mixing vessel
16 to a former 17. Former 17 may be optionally connected to a
hopper (not shown) into which the composition is placed prior to
entry into former 17. The blended composition may be transferred to
the former using any suitable feeding or pre-feeding equipment
known in the art. Former 17 is shown in detail in FIG. 2. In this
embodiment, former 17 forms a blanket/mat using an air-laid forming
process. One such type of air laid former is available Rando
Machine Corp., Macedon, N.Y.
[0119] Use of feeding and/or pre-feeding equipment which is metered
may insure that the constituents are evenly dispersed throughout
the mixture prior to being fed into former 17. Such types of
equipment are available as the Rando Prefeeder and
Rando-Feeder.RTM. from Rando Machine Corp. of Macedon, N.Y.
[0120] In general, the blended materials having a desired moisture
content (as discussed above), are suitably placed in the storage
container 30 which can then be emptied into the hopper 30, when
desired, to start the forming process. Alternatively, the blended
materials may be placed directly into the hopper 32 at the
discretion of an operator. In general, the mixed and/or blended
materials can be metered from the storage bin 30 or hopper 32 into
the former 17 so that the feeding equipment in former 17 may
maintain a uniform level of raw material for formation into a dry
blanket.
[0121] The materials are generally transported from the hopper 32
via a conveyor 34. A meter 36 at the top of the conveyor 34
regulates a desired amount of fibers to be processed at a forming
head 38 where the materials then start to catch and intertwine
together forming a web-like blanket or mat.
[0122] Alternatively, the amount or volume of fibers for formation
into a dry web-like blanket/mat may be regulated by doffing of the
fibers by a regulated air flow adjacent to an air bridge 40. The
flow rate of air adjacent to the air bridge 40 determines the
quantity of fibers conveyed and is governed by both the speed of
the continuous feed blanket formation on the condenser screen 42
and as regulated by the air volume control 44.
[0123] Generally the air pressure above the feed mat condenser is
below atmospheric pressure, which in turn causes air to flow
through the condenser screen and into a suction duct.
[0124] As the feed mat takes shape, the air flow is reduced due to
the resistance of the feed mat and the condenser screen proximate
to the air bridge 40. Proportionately less doffing occurs until an
equilibrium condition is achieved. At this time, sufficient tufts
of stover fibers are doffed to form a continuous uniform dry feed
mat.
[0125] The feed mat condenser drive is preferably synchronized with
the feed roll drive to maximize efficiency in the formation of the
dry feed mat. A dry feed mat is then preferably doffed onto the
feed plate 46 which then passes under the feed roll 48. The feed
roll 48 feeds the dry feed mat onto the concaved surface of the
nose bar 50 which exerts a hold action as the dry feed mat is fed
over the top of the nose bar 50 and onto the path of the lickerin
52. Loose fibers may then be separated from the dry feed mat by the
lickerin 52 and introduced into the air stream generated by a fan
54. The velocity of air from the fan 54 is controlled by a saber
56. The saber 56 may be rotated to either narrow or widen the
opening, between the saber 56 and the lickerin 52 to increase or
decrease the air velocity in a manner similar to a venturi 58.
Airborne fiber may then be carried into a duct area for
transportation to the condenser to be used in the formation of the
dry feed mat as shown in condenser area 60. Proximate to the
condenser area 60, fiber is preferably uniformly deposited on the
revolving condenser screen and is aerodynamically formed into a
continuous random fiber web structure as air passes through the
fiber into the closed duct system. The web then flows from the
condenser screen onto the take-away conveyor 62 for further
processing.
[0126] As the fiber passes the air bridge 40, the fiber is
transported by the forming head conveyor 39 to the forming head 38.
As the web passes into the lickerin 52, the web is destroyed and is
reconstituted via a vacuum-forming table. Reconstitution is
accomplished through the use of a polyester screen which has a
vacuum section below the screen for drawing tile fibers onto the
screen through the use of air pressure. The vacuum effect and air
pressure properly arrange the fibers to create a non-woven air-laid
fiber blanket/mat. Air pressure is exposed to the fibers from above
and to the polyester screen and a vacuum exists below to form the
non-woven air-laid felt blanket/mat by an essentially dry
process.
[0127] A conveyor may then be employed to transport the non-woven
air-laid felt blanket/mat into a curing oven 18 (FIG. 1) having a
vacuum below the conveyor which is a perforated screen. The
non-woven air-laid blanket/mat can be exposed to hot air from the
conveyor which can be suctioned through the mat or blanket through
the use of a vacuum for increased efficiency. The hot air is
preferably heated to a temperature of about 300.degree. F. to about
350.degree. F. which, when drawn by the vacuum, causes the
blanket/mat to dry very quickly. As the blanket or mat is dried,
the temperature for the blanket/mat begins to rise which in turn
can heat the bonding fibers to a temperature at which the adhesive
coating flows sufficiently or melts, causing the binding fibers to
become sticky and to adhere to any adjacent stover fibers. The
vacuum oven typically suitably extends over a distance of about 12
to about 18 feet for satisfactory efficiency. As the blanket/mat
exits the vacuum oven, squeeze and/or lift rollers compress the
heated blanket/mat.
[0128] The blanket/mat may then be passed to a cooling section
which consists of the take-away conveyor 62 which also includes a
vacuum positioned below the take-away conveyor 62 to draw ambient
air through the product to cool the blanket/mat to ambient or room
temperature. The product may then be cut to a desired size.
[0129] The formed blanket/mat as it emerges from the air-laid
former is then passed through a drying oven 18 wherein if an
adhesively coated bonding fiber is employed, the adhesive coating
begins to flow or ultimately melt, to initiate formation of a
cohesive blanket/mat. In one embodiment, the blanket/mat may be
passed through the oven 18 at a rate of about 10 to about 20
feet/minute, suitably about 15 feet/minute and the oven temperature
employed may be held between about 300.degree. F. and about
350.degree. F. Preferably, the oven temperature is high enough to
melt the coating on the bonding fibers and/or to begin melting any
resin which may have been added to the stover fiber composition.
Suitably, the temperature in the oven is kept below that at which
the resin melts completely. During the time in which the blanket is
in the oven 18, drying occurs and any excess moisture in the
blanket/mat product can be evaporated. The dried, formed,
reconstituted stover product exits the oven 18 in sheet form and
may be rolled up and packaged for later sale.
[0130] As the blanket/mat exits the vacuum oven, squeeze and/or
lift rollers compress the heated mat.
[0131] The blanket/mat may alternatively be formed over a netting,
and suitably, a recyclable or biodegradable netting. Biodegradable
netting may be formed from polylactic acid, polycaprolactone,
polyhydroxyvalerate-hydroxybutyrate, for example, and mixtures
thereof.
[0132] The resultant blanket/mat may have a non-woven
appearance.
[0133] The blanket/mat may be employed for revegetation, erosion
control, for livestock blankets, and in greenhouses and nurseries
for potting plants and for bare root trees, shrubs and plants, for
example.
[0134] The above disclosure is intended to be illustrative and not
exhaustive.
[0135] This description will suggest many variations and
alternatives to one of ordinary skill in this art. All these
alternatives and variations are intended to be included within the
scope of the attached claims. Those familiar with the art may
recognize other equivalents to the specific embodiments described
herein which equivalents are also intended to be encompassed by the
claims attached hereto.
[0136] While this invention may be embodied in many different
forms, there are described in detail herein specific preferred
embodiments of the invention. This description is an
exemplification of the principles of the invention and is not
intended to limit the invention to the particular embodiments
illustrated.
[0137] For the purposes of this disclosure, like reference numerals
in the figures shall refer to like features unless otherwise
indicated.
[0138] The above disclosure is intended to be illustrative and not
exhaustive. This description will suggest many variations and
alternatives to one of ordinary skill in this art. All these
alternatives and variations are intended to be included within the
scope of the claims where the term "comprising" means "including,
but not limited to". Those familiar with the art may recognize
other equivalents to the specific embodiments described herein
which equivalents are also intended to be encompassed by the
claims.
[0139] Further, the particular features presented in the dependent
claims can be combined with each other in other manners within the
scope of the invention such that the invention should be recognized
as also specifically directed to other embodiments having any other
possible combination of the features of the dependent claims. For
instance, for purposes of claim publication, any dependent claim
which follows should be taken as alternatively written in a
multiple dependent form from all prior claims which possess all
antecedents referenced in such dependent claim if such multiple
dependent format is an accepted format within the jurisdiction
(e.g. each claim depending directly from claim 1 should be
alternatively taken as depending from all previous claims). In
jurisdictions where multiple dependent claim formats are
restricted, the following dependent claims should each be also
taken as alternatively written in each singly dependent claim
format which creates a dependency from a prior
antecedent-possessing claim other than the specific claim listed in
such dependent claim below (e.g. claim 3 may be taken as
alternatively dependent from claim 2; claim 4 may be taken as
alternatively dependent on claim 2, or on claim 3; claim 6 may be
taken as alternatively dependent from claim 5; etc.).
[0140] In addition to being directed to the embodiments described
above and claimed below, the present invention is further directed
to embodiments having different combinations of the features
described above and claimed below. As such, the invention is also
directed to other embodiments having any other possible combination
of the dependent features claimed below.
[0141] The present invention may be embodied in other specific
forms without departing from the spirit or essential attributes
thereof, and it is, therefore, desired that the present embodiment
be considered in all respects as illustrative and not restrictive,
reference being made to the appended claims rather than to the
foregoing description to indicate the scope of the invention.
[0142] This completes the description of the preferred and
alternative embodiments of the invention. Those skilled in the art
may recognize other equivalents to the specific embodiment
described herein which equivalents are intended to be encompassed
by the claims attached hereto.
* * * * *