Note: Descriptions are shown in the official language in which they were submitted.
CA 02703595 2010-05-12
PROCESS FOR PRODUCING RECYCLED PAPER
FIELD OF THE INVENTION
The present invention relates to the field of paper production, and more
particularly to a process
for producing recycled paper using waste paper and waste cotton material.
BACKGROUND OF THE INVENTION
Modern technology in present day paper mills and highly mechanised
technologies for harvesting
wood made paper a relatively cheap commodity resulting in a high level of
consumption and
waste. Worldwide consumption of paper has risen by 400% in the past 40 years
with 35% of
harvested trees being used for paper manufacture raising substantial
environmental issues. Due to
the rise of environmental awareness in the general public and government
regulations there is
now a trend towards sustainability in the pulp and paper industry.
The rise of environmental awareness is reflected in the increasing
implementation of recycling of
waste materials such as waste paper and waste clothing. An increasing amount
of waste paper
such as, for example, office paper and newspaper is collected and used in the
manufacture of new
paper.
Unfortunately, with reuse the length of the paper fibres decreases resulting
in a substantially
reduced strength of the final paper product. Typically, a small amount of
paper pulp made from
waste paper is mixed with a large amount of wood pulp made from harvested
trees in the
manufacture of higher quality paper.
Another method of making paper is the use of cotton fibres producing high
quality cotton paper
of exceptional strength which is generally used for making bank notes.
Attempts to use cotton fibres for strengthening paper made from recycled waste
paper have failed
due to problems in mixing and adhering of the waste paper and cotton fibres.
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It is desirable to provide a process capable of mixing and adhering waste
paper and cotton fibres
for producing paper.
It is also desirable to provide a process for paper manufacturing using only
waste paper and
waste cotton material.
SUMMARY OF THE INVENTION
to Accordingly, one object of the present invention is to provide a process
capable of mixing and
adhering waste paper and cotton fibres for producing paper.
Another object of the present invention is to provide a process for paper
manufacturing using
only waste paper and waste cotton material.
According to one aspect of the present invention, there is provided a method
for producing
recycled paper. Paper pulp and cotton pulp are provided. The cotton pulp is
added to the paper
pulp to produce a pulp mixture. The pulp mixture is deposited onto a wire mesh
for forming a
paper web such that a flow rate of the pulp mixture and a speed of a relative
movement between
a pulp mixture depositing device and the wire mesh is reduced compared to the
flow rate and the
speed of the relative movement used for depositing only the paper pulp.
According to another aspect of the present invention, there is further
provided a method for
producing recycled paper. Paper pulp and cotton pulp are produced from waste
paper and waste
cotton material, respectively. The cotton pulp is added to the paper pulp to
produce a pulp
mixture. The pulp mixture is deposited onto a wire mesh for forming a paper
web such that a
flow rate of the pulp mixture and a speed of a relative movement between a
pulp mixture
depositing device and the wire mesh is reduced compared to the flow rate and
the speed of the
relative movement used for depositing only the paper pulp. Furthermore, the
wire mesh has a
reduced mesh size compared to the mesh size used for depositing only the paper
pulp.
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The advantage of the present invention is that it provides a process capable
of mixing and
adhering waste paper and cotton fibres for producing paper.
A further advantage of the present invention is that it provides a process for
paper manufacturing
using only waste paper and waste cotton material.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention is described below with
reference to the
accompanying drawings, in which:
Figures la to I d are simplified flow diagrams illustrating a process for
producing recycled
paper according to a preferred embodiment of the invention; and,
Figures 2a to 2c are simplified block diagrams illustrating a preferred
implementation of
the process for producing recycled paper illustrated in Figures 1 a to 1 d.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Unless defined otherwise, all technical and scientific terms used herein have
the same meaning as
commonly understood by one of ordinary skill in the art to which the invention
belongs.
Although any methods and materials similar or equivalent to those described
herein can be used
in the practice or testing of the present invention, the preferred methods and
materials are now
described.
While embodiments of the invention will be described for implementation using
a Fourdrinier
type paper making machine, use of waste paper for producing paper pulp, and
use of waste cotton
material for producing cotton pulp for the sake of simplicity, it will become
evident to those
skilled in the art that the embodiments of the invention are not limited
thereto, but are also
applicable using different paper making machines, paper pulp made using wood,
cotton pulp
made using new cotton fibers as well as combinations with waste paper and
waste cotton
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material.
Referring to Figures 1 a to l d, a process for producing recycled paper
according to a preferred
embodiment of the invention is provided. A preferred implementation 100 of the
process for
producing recycled paper is illustrated in Figures 2a to 2c. At 1 OA and I OB,
paper pulp and
cotton pulp is provided, respectively. Preferred embodiments for providing the
paper pulp and
the cotton pulp are illustrated in Figures lb and lc, respectively.
Preferably, waste office paper
collected from various offices or elsewhere is fed into a pulper. The pulper
is mixer and grinder,
where a predetermined amount of the waste paper is mixed with a predetermined
amount of
water and ground at high speed -1 OA.1. At I OA.2, preferably four percent
aluminum sulphate
and four percent rosin are added to the paper pulp. Aluminum sulphate is added
for sizing the
stock and for making the paper blot free. Rosin is added for binding the
fibers together. As is
evident to those skilled in the art, other materials and amounts are
applicable depending, for
example, on the type of material used for producing the paper pulp and the
type of recycled paper
to be produced. At I OA.3, ferrous materials such as, for example, pins,
staples, and clips are
removed from the paper pulp. The removal of the ferrous materials is
performed, for example, by
lowering magnets into the paper pulp during the mixing and grinding process.
After termination
of the pulping the paper pulp is processed -1 OA.4 - to remove unwanted non-
ferrous material
such as, for example, pieces of plastic material. For example, the paper pulp
is passed through a
screen having a predetermined mesh size large enough for enabling transmission
of the paper
pulp fibers and small enough to prevent transmission of substantially all
unwanted materials. The
screened paper pulp is then transferred into an agitator 102 for agitating the
paper pulp - I OA.5.
A typical agitator 102 is a round well with a motor driven shaft having two or
more blades 104
mounted thereto. A slow movement of the blades 104 ensures provision of a
consistent paper
pulp 106.
Using only waste paper for producing the paper pulp does not provide recycled
paper having
sufficient strength for most types of paper. To increase the strength of the
recycled paper, cotton
fibers are added. Preferably, waste cotton materials such as, for example,
waste cotton clothes or
cuttings and trimmings from garment factories are used for providing the
cotton fibers. At I OB.1,
the waste cotton materials are sorted, for example, to sort colored cotton
materials, and extra
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fittings such as, for example, buttons and zippers are removed. For example,
only cotton
materials of a specific color are used for a specific recycled paper product
to be produced there
from. Mixed color stock is used for producing low grade packaging materials.
The cotton
material is then cut to a substantially uniform size -1 OB.2. A predetermined
amount of the cut
cotton material is then fed into a beater 108 together with a predetermined
amount of water and
beaten - 10B.3 - for approximately 5 hours using beating element 110 for
producing cotton pulp
112.
After approximately three hours of beating. preferably four percent rosin is
added to the cotton
pulp - I OB.4 - and after four hours of beating aluminum sulphate is added to
the cotton pulp -
1OB.5. Aluminum sulphate is added for sizing the stock and for making the
recycled paper blot
free. Rosin is added for binding the fibers together. As is evident to those
skilled in the art, other
materials and amounts are applicable depending, for example, on the type of
cotton material used
for producing the cotton pulp and the type of recycled paper to be produced.
The cotton pulp is
then washed -1013.6 - to remove unwanted materials.
The cotton pulp 112 is then added to the paper pulp 106 to produce a pulp
mixture - 20. For
example, the cotton pulp is slowly added to the paper pulp while the same is
agitated in the
agitator 102. The pulp mixture is agitated - 30 - to ensure provision of a
consistent pulp mixture.
Depending on the required strength of the recycled paper product a
predetermined amount of
cotton pulp is added to the paper pulp. For example, for producing recycled
paper products for
office stationary, filters, and insulation the amount of cotton pulp added is
approximately in the
range between 15% and 25% of the paper pulp. Mixing and adhering of the paper
pulp fibers and
the cotton pulp fibers is substantially improved by adding the cotton pulp to
the paper pulp.
Once the pulp mixture is consistent it is provided - 40 - to a headbox 118 of
a paper making
machine such as, for example, a Fourdrinier type paper making machine. For
example, the pulp
mixture is pumped to the headbox 118 using a conventional pulp pump. Depending
on the
thickness of the recycled paper to be manufactured the pulp mixture is diluted
with water 114.
The diluted pulp mixture 116 is then deposited - 50 - onto a conveying wire
mesh 124 forming a
paper web of the paper making machine. For example, the diluted pulp mixture
116 flows under
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gravity through nozzle 120 of the headbox 118 as indicated by arrow 122 and
onto the wire mesh
124 forming pulp layer 126. The pulp layer 126 is then conveyed via the
conveying wire mesh -
as indicated by the arrow - from the headbox 118 to further processing
stations of the paper
making machine for producing - 60 - paper therefrom, as will be described
herein below. To
ensure adherence of the paper pulp fibers and the cotton pulp fibers the
diluted pulp mixture 116
is deposited onto the wire mesh 124 such that a flow rate of the pulp mixture
and a speed of a
relative movement between the nozzle 120 the wire mesh 124 is reduced compared
to the flow
rate and the speed of the relative movement used for depositing only the paper
pulp. Preferably,
the flow rate as well as the speed of the relative movement is reduced by
approximately 25% to
t0 45%. Furthermore, the mesh size the conveying wire mesh 124 is reduced, as
illustrated in
Figures 2b and 2c. Preferably, the mesh size is reduced by approximately 20%
to 35%. As is
evident, the process for producing recycled paper is also implementable with
types of paper
making machines including paper making machines having a stationary wire mesh
and movable
headbox.
The pulp layer 126 - or paper sheet - is then processed to remove a first
portion of the water -
60.1 - followed by passing it through a plurality of rollers for further
drying and calendaring -
60.2. In the calendaring process the paper is passed between two rollers
pressing the paper. The
calendaring process further dries the paper and gives it a glazing effect.
After calendaring the
paper is, for example, rolled onto a roller - 60.3 - forming a paper roll for
further processing
such as printing or, alternatively, out into sheets and packed in a packet or
reem.
The process for producing recycled paper according to embodiments of the
invention enables
production of recycled paper in small quantities for recycling waste paper and
waste cotton
clothing in smaller communities. Furthermore, the process for producing
recycled paper is easily
implementable by modifying existing paper making machines to reduce the
relative speed
between the headbox and the wire mesh and reducing the mesh size.
The present invention has been described herein with regard to preferred
embodiments, However,
it will be obvious to persons skilled in the art that a number of variations
and modifications can
be made without departing from the scope of the invention as described herein.
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