U.S. patent application number 15/822442 was filed with the patent office on 2018-03-15 for sheet manufacturing apparatus and sheet manufacturing method.
The applicant listed for this patent is SEIKO EPSON CORPORATION. Invention is credited to Yoshihiro UENO.
Application Number | 20180072002 15/822442 |
Document ID | / |
Family ID | 55299298 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180072002 |
Kind Code |
A1 |
UENO; Yoshihiro |
March 15, 2018 |
SHEET MANUFACTURING APPARATUS AND SHEET MANUFACTURING METHOD
Abstract
A composite to be mixed with fibers for forming a sheet by heat
includes a resin particle for bonding the fibers, and inorganic
fine particles that coat at least a portion of a surface of the
resin particle.
Inventors: |
UENO; Yoshihiro; (Shiojiri,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEIKO EPSON CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
55299298 |
Appl. No.: |
15/822442 |
Filed: |
November 27, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14984100 |
Dec 30, 2015 |
9849634 |
|
|
15822442 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21B 1/021 20130101;
D21F 9/00 20130101; B29C 70/06 20130101; B29B 7/38 20130101; B29D
7/01 20130101; D21F 1/82 20130101; B29K 2001/00 20130101; B29K
2103/06 20130101; D04H 1/413 20130101; D04H 1/732 20130101 |
International
Class: |
B29C 70/06 20060101
B29C070/06; D04H 1/732 20060101 D04H001/732; D04H 1/413 20060101
D04H001/413; D21F 9/00 20060101 D21F009/00; D21B 1/02 20060101
D21B001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2015 |
JP |
2015-021829 |
Claims
1-8. (canceled)
9. A composite to be mixed with fibers for forming a sheet by heat,
the composite comprising: a resin particle for bonding the fibers;
and inorganic fine particles that coat at least a portion of a
surface of the resin particle.
10. The composite according to claim 9, wherein the inorganic fine
particles are attached to or bonded to the surface of the resin
particle.
11. The composite according to claim 9, wherein the inorganic fine
particles are encapsulated by the resin particle.
12. The composite according to claim 9, further comprising at least
one of a coloring agent and a flame retardant.
13. The composite according to claim 9, wherein an absolute value
of an average charging amount of the composite is 40 .mu.C/g or
higher.
14. The composite according to claim 9, wherein the volumetric
average particle diameter of the resin particle is 25 .mu.m or
less.
15. The composite according to claim 9, wherein the volumetric
average particle diameter of the inorganic fine particles is 40 nm
or less.
16. The composite according to claim 9, wherein the content of the
inorganic fine particles in the composite is 0.1% by weight or more
to less than 4% by weight.
Description
[0001] This application is a continuation application of U.S.
patent application Ser. No. 14/984,100, filed on Dec. 30, 2015.
This application claims priority to Japanese Patent Application No.
2015-021829 filed on Feb. 6, 2015. The entire disclosures of U.S.
patent application Ser. No. 14/984,1.00 and Japanese Patent
Application No. 2015-021829 are hereby expressly incorporated
herein by reference.
BACKGROUND
1. Technical Field
[0002] The present invention relates to a sheet manufacturing
apparatus and a sheet manufacturing method.
2. Related Art
[0003] Depositing a fiber-like material and causing a bonding force
between the deposited fibers to obtain a sheet-like or film-like
formed body has been performed for a long time. Typical examples
thereof include manufacturing paper by pulp molding (paper-forming)
using water. Even in present times, pulp molding is widely used as
an example of a method of manufacturing paper. The paper
manufactured by pulp molding generally includes a structure by
cellulose fibers derived from wood or the like being entangled with
one another, and being partially bonded to one another by a binder
(paper strengthening agent (such as a starch paste and a
water-soluble resin)).
[0004] According to the pulp molding, it is possible for the fibers
to be deposited in a state where uniformity is favorable, and, in a
case where a paper strengthening agent is used in the bonding
between fibers, it is possible for the paper strengthening agent to
be dispersed (distributed) in a state where the uniformity in the
paper surface is good. However, because the pulp molding is a wet
method, it is necessary to use large volumes of water, and the
necessity of dewatering and drying, or the like, arises after
forming the paper, and therefore the energy or time consumed is
extremely large. It is necessary to suitably process the water used
as waste water. Accordingly, it is difficult to respond to modern
demands for energy savings, environmental protection, and the like.
The apparatuses used in pulp molding frequently need large scale
utilities such as water, power, and drainage facilities, and size
reductions are difficult. From this viewpoint, there is an
expectation of methods, referred to as dry methods that use no or
almost no water as paper manufacturing methods in place of pulp
molding.
[0005] For example, in the technology disclosed in
JP-A-2011-099172, an attempt at bonding fibers to one another with
a thermal fusion-bondable resin in air-laid non-woven fabric that
includes a highly water absorbent resin is disclosed.
[0006] However, in the technology disclosed in JP-A-2011-099172,
the thermal fusion-bondable resin has the properties of a powder,
and there is a danger of detachment from between the fibers when
air-laid. Paragraph [0013] in JP-A-2011-099172 discloses that when
thermal fusion-bondable powder is too small, the powder passes
through the mesh conveyor (mesh belt) and it is difficult for the
fibers to be bonded to one another. Accordingly, JP-A-2011-099172
describes that it is favorable to use a thermal fusion bondable
resin powder of the comparatively large particle diameter (20 mesh
pass to 300 mesh on).
[0007] However, when the particle diameter of the resin is large,
the uniformity of the distribution of the resin in the manufactured
sheet may be impaired. Accordingly, it is desirable that the
particle diameter of the resin is smaller in order for the resin to
be uniformly dispersed between the fibers.
[0008] In a case of forming a web by air-laying, suctioning is
ordinarily performed from below the mesh belt. Thus, when the
particle diameter of the resin is smaller than the size of the
openings in the mesh belt, it is thought that the resin easily
detaches from between the fibers during web formation. Therefore,
even if the particle diameter of the resin is reduced, work is
necessary to make the resin difficult to detach from between the
fibers.
SUMMARY
[0009] An advantage of some aspects of the invention is to provide
a sheet manufacturing apparatus and a sheet manufacturing method
that uses a thermal fusion-bondable resin that is not easily
detached from between fibers.
[0010] The invention can be realized in the following forms or
application examples.
[0011] According to an aspect of the invention, there is provided a
sheet manufacturing apparatus including a mixing unit configured to
mix fibers and a composite in the atmosphere, and a forming unit
configured to deposit and heat a mixture mixed by the mixing unit
to form a sheet; in which the composite is resin particles with at
least a portion of a surface covered with inorganic fine particles,
and an absolute value of an average charging amount of the
composite is 40 .mu.C/g or higher.
[0012] According to the sheet manufacturing apparatus of the
application example, because the composite that is resin particles
with at least a portion of the surface is covered with the
inorganic fine particles is mixed in air with fibers, the composite
is more easily charged and attached to the fibers during mixing,
and the composite is not easily detached from the fibers during
forming of the web. Since the composite and the fibers are bonded
(fusion bonded) in this state, it is possible to manufacture a
sheet with favorable strength.
[0013] In the sheet manufacturing apparatus according to the aspect
of the invention, the volumetric average particle diameter of the
resin particles may be 25 .mu.m or less.
[0014] According to the sheet manufacturing apparatus, because the
composite is small on the order of 25 .mu.m or less, the composite
is easily mixed and easily dispersed between the fibers. The
composite particle is small and has a light weight, and thus is not
easily influenced by gravity and not easily detached from the web
or sheet.
[0015] In the sheet manufacturing apparatus according to the aspect
of the invention, the volumetric average particle diameter of the
inorganic fine particles may be 40 .mu.m or less.
[0016] When the average particle diameter of the inorganic fine
particles is 40 nm or less, it is possible for the charging amount
of the composite to be further increased.
[0017] In the sheet manufacturing apparatus of the aspect of the
invention, the composite may not be divided into the resin and the
inorganic fine particles during mixing in the mixing unit.
[0018] According to such a sheet manufacturing apparatus, since not
only are the inorganic fine particles simply attached to the resin
in a composite state, but the composite is also integrated to an
extent where the resin and the inorganic fine particles are not
divided during mixing, dropping of the inorganic fine particles
less easily occurs during mixing.
[0019] In the sheet manufacturing apparatus according to the aspect
of the invention, the forming unit may further include a
discharging unit configured to discharge the mixture, a mesh belt
configured to accumulate the mixture, and a suction unit configured
to suctions gas that includes the mixture via the mesh belt.
[0020] By performing suction via the mesh belt, although the
possibility of the composite detaching from the fibers increases,
according to the sheet manufacturing apparatus of the application
example, it is possible to suppress detachment of the composite
from the fibers even when the suction unit is included.
[0021] In the sheet manufacturing apparatus according to the aspect
of the invention, the content of the inorganic fine particles in
the composite may be 0.1% by weight or more to less than 4% by
weight.
[0022] According to such a sheet manufacturing apparatus, even if
the content of the inorganic fine particles in the composite is
reduced to 0.1% by weight or more to less than 4% by weight, it is
possible to sufficiently obtain the charging effect. Therefore, it
is possible for the usage amount of the inorganic fine particles to
be reduced.
[0023] In the sheet manufacturing apparatus according to the aspect
of the invention, the mixing unit may include a plurality of rotary
units having blades that rotate, and may mix the fibers and the
composite by being passed through the rotary unit.
[0024] According to such a sheet manufacturing apparatus, the
composite is more easily charged, and less easily detaches from the
fibers by the fibers and the composite being passed through the
rotary unit having blades that rotate.
[0025] According to another aspect of the invention, there is
provided a sheet manufacturing method including mixing the fibers
and the composite, in which the resin and the inorganic fine
particles are integrated, in air, and depositing, heating and
forming a mixture in which the fibers and the composite are
mixed.
[0026] According to such a sheet manufacturing method, because the
composite that is resin particles covered with the inorganic fine
particles is mixed in air with fibers, the composite is more easily
charged and attached to the fibers during mixing, the composite is
not easily detached from the fibers during forming of the web and
it is possible to manufacture a sheet with favorable uniformity of
strength or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0028] FIG. 1 is a drawing schematically showing a sheet
manufacturing apparatus according to an embodiment.
[0029] FIGS. 2A and 2B are schematic views of several examples of
cross-sections of the composite according to the embodiment.
[0030] FIG. 3 is a schematic view showing an example of a suction
device according to an example.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0031] Below, various embodiments of the invention will be
described. The embodiments described below are for describing
examples of the invention. The invention is not limited in any way
by the following embodiments, and includes various modifications
carried out in a range not departing from the gist of the
invention. Not all of the configurations explained below are
indispensable configurations in the invention.
1. Sheet Manufacturing Apparatus
[0032] The sheet manufacturing apparatus according to the
embodiment includes a mixing unit that mixes fibers and a composite
in the atmosphere, a forming unit that deposits and heats a mixture
mixed by the mixing unit to form a sheet; in which the composite is
resin particles with at least a portion of the surface covered by
inorganic fine particles, and an absolute value of an average
charging amount of the composite is 40 .mu.C/g or higher.
1.1. Configuration
[0033] First, an example of the sheet manufacturing apparatus
according to the embodiment will be described with reference to the
drawings. FIG. 1 is a drawing schematically showing a sheet
manufacturing apparatus 100 according to the embodiment.
[0034] The sheet manufacturing apparatus 100 is provided with a
supplying unit 10, a manufacturing unit 102, and a controller 140,
as shown in FIG. 1. The manufacturing unit 102 manufactures a
sheet. The manufacturing unit 102 includes a crushing unit 12, a
defibrating unit 20, a classifying unit 30, a screening unit 40, a
first web forming unit 45, a mixing unit 50, a deposition unit 60,
a second web forming unit 70, a sheet forming unit 80, and a
cutting unit 90.
[0035] The supplying unit 10 supplies raw materials to the crushing
unit 12. The supplying unit 10 is an automatic feeding unit for
continuously feeding the raw materials to the crushing unit 12. The
raw materials supplied by the supplying unit 10 include fibers such
as recycled pulp and pulp sheets.
[0036] The crushing unit 12 cuts the raw material supplied by the
supplying unit 10 into small pieces in air. The shape and size of
the small pieces is several cm squared. In the examples in the
drawings, the crushing unit 12 includes a crushing blade 14, and it
is possible for the fed raw materials to be cut by the crushing
blade 14. A shredder is used as the crushing unit 12. The raw
material cut by the crushing unit 12 is transferred (transported)
to the defibrating unit 20 via a pipe 2 once received by a hopper
1.
[0037] The defibrating unit 20 defibrates the raw material cut by
the crushing unit 12. Here, the wording "defibrates" refers to
untangling the raw material (material to be defibrated) in which a
plurality of fibers are bonded into individual fibers. The
defibrating unit 20 also has a function of causing substances such
as resin powder bonded to the raw material, ink toner, or
blur-preventing agent to be isolated from the fibers.
[0038] The material that passes through the defibrating unit 20 is
referred to as a "defibrated material". There are also cases where
resin (resin for causing a plurality of fibers to bond to one
another) powder isolated from the fibers when the fibers are
untangled, colorants such as ink and toner, and additives such as
bleeding inhibitors and paper strengthening agents are included in
the "defibrated material" in addition to the untangled defibrated
material fibers. The shape of the untangled defibrated material is
string-like or ribbon-like. The untangled defibrated material may
be present in a state of not being entangled with other untangled
fibers (independent state) or may be present in a state being
entangled with other untangled fibers to form a clump (a state of
forming a so-called "lump").
[0039] The defibrating unit 20 performs defibrating with a dry
method in the atmosphere (in air). Specifically, an impeller mill
is used as the defibrating unit 20. The defibrating unit 20 has the
function causing an airflow to be generated so as to suction the
raw material and discharge the defibrated material. In so doing, it
is possible for the defibrating unit 20 to suction the raw material
along with the airflow from an introduction port 22, perform the
defibration treatment, and transport the raw material to the exit
port 24 with the self generated airflow. The defibrated material
that passes through the defibrating unit 20 is transferred to the
classifying unit 30 via the pipe 3.
[0040] The classifying unit 30 classifies the defibrated material
passing through the defibrating unit 20. Specifically, the
classifying unit 30 isolates and removes the defibrated material
that is comparatively small or has a low density (such as resin
powder, colorant, and additive) from the defibrated material. In so
doing, it is possible to increase the proportion accounted for by
fibers that are comparatively large or have a high density from the
defibrated material.
[0041] An airflow classifier is used as the classifying unit 30.
The airflow classifier generates a swirling airflow, and performs
isolation according to differences in the centrifugal force
received due to the size and density of the classified materials,
and it is possible to adjust the classification points through
adjustment of the speed of the airflow and the centrifugal force.
Specifically, a cyclone, an elbow jet, an eddy classifier, and the
like are used as the classifying unit 30. In particular, it is
possible for the cyclone as shown in the drawings to be favorably
used as the classifying unit 30 because the structure is
simple.
[0042] The classifying unit 30 includes an introduction port 31, a
body 32 connected to the introduction port 31, a reverse conical
portion 33 positioned below the body 32 and contiguous with the
body 32, a lower exit port 34 provided in the lower center of the
reverse conical portion 33, and an upper exit port 35 provided in
the upper center of the body 32.
[0043] In the classifying unit 30, the airflow that carries along
the defibrated material introduced from the introduction port 31 is
changed to a circular motion by the body 32. In so doing,
centrifugal force is applied to the introduced defibrated material,
it is possible for the classifying unit 30 to isolate the fibers
(first classified material) with a higher density than the resin
powder or the ink powder from the defibrated material and the resin
powder with a lower density than the fibers, colorant, additives or
the like (second classified material) from the defibrated material.
The first classified material is discharged from the lower exit
port 34, and introduced to the screening unit 40 via the pipe 4.
Meanwhile, the second classified material is discharged from the
upper exit port 35 to the receiving portion 36 via the pipe 5.
[0044] The screening unit 40 introduces the first classified
material (defibrated material defibrated by the defibrating unit
20) passing through the classifying unit 30 from the introduction
port 42 and screens the material according to fiber length. A sieve
is used as the screening unit 40. The screening unit 40 includes a
mesh (filter, screen) and is able to divide fibers or particles
(first screened material passing through the mesh) that are smaller
than the size of the openings of the mesh and included and fibers,
non-defibrated pieces or lumps (second screened material not
passing through the mesh) larger than the size of the opening in
the mesh included in the first classified material. For example,
the first screened material is transferred to the mixing unit 50
via the pipe 7 once received by the hopper 6. The second screened
material is returned to the defibrating unit 20 from the exit port
44 via the pipe 8. Specifically, the screening unit 40 is a
cylindrical sieve that is able to rotate by a motor. A metal mesh,
an expanded metal in which a perforated metal plate is drawn, and a
punched metal plate in which holes are formed in a metal plate by a
pressing machine or the like are used as the mesh of the screening
unit 40.
[0045] The first web forming unit 45 transports the first screened
material passing through the screening unit 40 to the mixing unit
50. The first web forming unit 45 includes a mesh belt 46, a
tensioned roller 47, and a suction unit (suction mechanism) 48.
[0046] It is possible for the suction unit 48 to suction the first
screened material dispersed in the air after passing through the
opening (opening of the mesh) of the screening unit 40 on the mesh
belt 46. The first screened material is deposited on the moving
mesh belt 46 and forms the web V. The specific configurations of
the mesh belt 46, the tensioned roller 47, and the suction unit 48
are the same as the mesh belt 72, the tensioned roller 74, and the
suction mechanism 76 of the second web forming unit 70, described
later.
[0047] The web V is formed in a state of including large volumes of
air and being softly swelled by passing through the screening unit
40 and the first web forming unit 45. The web V deposited on the
mesh belt 46 is fed to the pipe 7 and transported to the mixing
unit 50.
[0048] The mixing unit 50 mixes the first screened material (first
screened material transported by the first web forming unit 45)
passing through the screening unit 40 and the additive agent that
includes a resin. The mixing unit 50 includes an additive agent
supply unit 52 that supplies the additive agent, a pipe 54 that
transports the screened material and the additive, and a blower 56.
In the examples in the drawings, the additive agent is supplied
from the additive agent supply unit 52 to the pipe 54 via the
hopper 9. The pipe 54 is contiguous with the pipe 7.
[0049] An airflow is generated by the blower 56 in the mixing unit
50, and it is possible to transport the first screened material and
the additive agent while being mixed in the pipe 54. The mechanism
by which the first screening material and the additive agent are
mixed is not particularly limited, and may be a mechanism that
performs agitating with blades that rotate at high speed, or may be
a mechanism that uses the rotation of a container such as a V-type
mixer.
[0050] A screw feeder as shown in FIG. 1, a disk feeder, not shown,
or the like is used as the additive agent supply unit 52. The
additive agent supplied from the additive agent supply unit 52
includes a resin for causing the plurality of fibers to bond. At
the point in time at which the resin is supplied, the plurality of
fibers is not bonded. The resin is fused when passing through the
sheet forming unit 80 and the plurality of fibers is bonded.
[0051] The resin supplied from the additive agent supply unit 52 is
a thermoplastic resin or a heat-curable resin, and is an AS resin,
an ABS resin, polypropylene, polyethylene, polyvinyl chloride,
polystyrene, an acrylic resin, a polyester resin, polyethylene
terephthalate, polyphenylene ether, polybutylene terephthalate,
nylon, polyamide, polycarbonate, polyacetal, polyphenylene sulfide,
polyetherether ketone, or the like. These resins may be used
independently or mixed, as appropriate. The additive agent supplied
from the additive agent supply unit 52 may be in the form of
fibers, or may be in the form of a powder.
[0052] The additive agent supplied from the additive agent supply
unit 52 may include, according to the type of sheet manufactured,
coloring agents for coloring the fibers, coagulation inhibitors for
preventing aggregation of the fibers, and flame retardants for
making the fibers and the like more difficult to burn, in addition
to the resin that bonds the fibers. The mixture (mixture of the
first classified material and the additive agent) passing through
the mixing unit 50 is transferred to the deposition unit 60 via the
pipe 54.
[0053] The deposition unit 60 introduces the additive agent passing
through the mixing unit 50 from the introduction port 62, refines
the entangled defibrated material (fibers) and causes the
defibrated material to descend while being disperse in air. The
deposition unit 60 refines the entangled resin in a case where the
resin of the additive agent supplied from the additive agent supply
unit 52 is in the form of a fiber. In so doing, it is possible for
the deposition unit 60 to cause the mixture to be uniformly
deposited on the second web forming unit 70.
[0054] A cylindrical sieve that rotates is used as the deposition
unit 60. The deposition unit 60 includes a mesh, and causes the
fibers of particles (passing through the mesh) included in the
mixture passing through the mixing unit 50 and smaller than the
size of the mesh openings to descend. The configuration of the
deposition unit 60 is that same as the configuration of the
screening unit 40.
[0055] The "sieve" of the deposition unit 60 may have a function of
screening specified target materials. That is, the wording "sieve"
used as the deposition unit 60 signifies a sieve provided with a
mesh, and the deposition unit 60 may cause all of the mixture
introduced to the deposition unit 60 to descend.
[0056] The second web forming unit 70 accumulates the
passing-through material passing through deposition unit 60 and
forms the web W. The second web forming unit 70 includes a mesh
belt 72, a tensioned roller 74, and a suction mechanism 76.
[0057] The mesh belt 72 accumulates the passing-through material
passing through the openings (openings of the mesh) of the
deposition unit 60 while moving. The mesh belt 72 has a
configuration in which the mesh belt 72 is tensioned by the
tensioned roller 74, and air that does not easily pass through the
passing-through material passes therethrough. The mesh belt 72
moves through the tensioned roller 74 rotating. The web W is formed
on the mesh belt 72 by the passing-through material passing through
the deposition unit 60 continuously accumulating while the mesh
belt 72 continuously moves. The mesh belt 72 is made from a metal,
a resin, a fabric, a non-woven fabric or the like.
[0058] The suction mechanism 76 is provided below (opposite side to
the deposition unit 60 side) the mesh belt 72. It is possible for
the suction mechanism 76 to cause a downward moving airflow
(airflow from the deposition unit 60 to mesh belt 72) to be
generated. It is possible for the mixture dispersed in the air by
the deposition unit 60 to be suctioned onto the mesh belt 72 by the
suction mechanism 76. In so doing, it is possible for the discharge
speed from the deposition unit 60 to be increased. It is possible
to form a down flow in the dropping path of the mixture by the
suction mechanism 76, and it is possible to avoid the defibrated
material and the additive agent being entangled during
dropping.
[0059] As above, the web W is formed in a state of including large
volumes of air and being softly swelled by passing through the
deposition unit 60 and the second web forming unit 70 (web forming
step). The web W deposited on the mesh belt 72 is transported to
the sheet forming unit 80.
[0060] In the examples in the drawings, a moisture-adjusting unit
78 that adjusts the moisture of the web W is provided. It is
possible for the moisture-adjusting unit 78 to add water or water
vapor to the web W and regulate the ratio of the web W to the
water.
[0061] The sheet forming unit 80 forms the sheet S by heating the
web W deposited on the mesh belt 72. In the sheet forming unit 80,
it is possible for the plurality of fibers in the mixture to be
bonded to one another via the additive (resin) by applying heat to
the mixture of the defibrated material and the additive agent mixed
into the web W.
[0062] A heating roller (heater roller), a hot press molding
machine, a hot plate, a hot air blower, an infrared heating device,
or a flash fixing device is used as the sheet forming unit 80. In
the examples in the drawings, the sheet forming unit 80 is provided
with a first bonding unit 82 and a second bonding unit 84, and the
bonding units 82 and 84 are each provided with a pair of heating
rollers 86. It is possible to form the sheet S while continuously
transporting the web W by configuring the bonding unit 82 and 84 as
heating rollers 86, compared to a case of configuring the bonding
units 82 and 84 as a plate-like press device (plate press device).
The number of heating rollers 86 is not particularly limited.
[0063] The cutting unit 90 cut the sheet S formed by the sheet
forming unit 80. In the examples in the drawings, the cutting unit
90 includes a first cutting unit 92 that cut the sheet S in a
direction that intersects the transport direction of the sheet S
and a second cutting unit 94 that cuts the sheet S in a direction
parallel to the transport direction. The second cutting unit 94
cuts the sheet S passing through the first cutting unit 92.
[0064] As above, a cut-form sheet S with a predetermined size is
formed. The cut-form sheet S that is cut is discharged to the
discharge unit 96.
1.2. Fiber
[0065] In the sheet manufacturing apparatus 100 of the embodiment,
the raw material is not particularly limited, and it is possible
for a wide range of fiber materials to be used. Examples of the
fibers include natural fibers (animal or plant fibers) and chemical
fibers (organic, inorganic or organic-inorganic composite fibers),
and more specifically, examples include fibers made from cellulose,
silk, wool, cotton, hemp, kenaf, flax, Ramie, jute, manila hemp,
sisal hemp, softwood, and hardwood, and fibers made from rayon,
lyocell, cupra, vinylon, acrylic, nylon, aramid, polyester,
polyethylene, polypropylene, polyurethane, polyimide, carbon,
glass, and metal and these may be used independently or mixed, as
appropriate, or may be used as a regenerated fiber on which
purification or the like is performed. Although examples of the raw
material include recycled paper and recycled cloth, at least one of
these fibers may be included. The fiber may be dried or may be
contained or be impregnated with a liquid such as water or an
organic solvent. Various surface treatments may be performed. The
material of the fibers may be a pure material, or may be a material
that includes various components such as impurities, additives and
other components.
[0066] In this way, although the sheet manufacturing apparatus 100
of the embodiment can use various types of raw material, among
these, a recycled paper, pulp sheet or the like that includes
cellulose fibers has a more remarkable effect of improve the
attachment of the composite and the fibers due to the fiber,
described later, than a case of other fibers, because cellulose has
a comparatively high hydrophilicity and is less easily charged.
[0067] When the fibers used in the embodiment are made one
independent fiber, the average diameter (in a case where the
cross-section is not a circle (diameter of a circle when a circle
having the greatest length from the lengths in a direction
perpendicular to the length direction or equivalent to the area of
the cross-section (equivalent circle diameter)) thereof is 1 .mu.m
or more to 1000 .mu.m or less, 2 .mu.m or more to 500 .mu.m or less
is preferable, and 3 .mu.m or more to 200 .mu.m or less is more
preferable.
[0068] Although the length of the fibers used by the sheet
manufacturing apparatus 100 of the embodiment is not particularly
limited, in one independent fiber, the length along the length
direction of the fiber is 1 .mu.m or more to 5 mm or less, 2 .mu.m
or more to 3 mm or less is preferable, and 3 .mu.m or more to 2 mm
or less is more preferable. In a case where the length of the
fibers is short, although the strength of the sheets may be
insufficient because the fibers do not easily bond with the
composite, it is possible to obtain a sufficiently strong sheet as
long as the length is within the above ranges.
[0069] The average length of the fibers, as the
length-length-weighted mean fiber length, is 20 .mu.m or more to
3600 .mu.m or less, 200 .mu.m or more to 2700 .mu.m or less is
preferable, and 300 .mu.m or more to 2300 .mu.m or less is more
preferable. The length of the fibers may have variations
(distribution), and in a case where a normal distribution in a
distribution obtained with an n of 100 or more is assumed, the
.delta. for the length of one independent fiber may be 1 .mu.m or
more to 1100 .mu.m or less, preferable 1 .mu.m or more to 900 .mu.m
or less, and more preferably 1 .mu.m or more to 600 .mu.m or
less.
[0070] It is possible to measure the thickness and length of the
fibers with various optical microscopes, scanning electron
microscopes (SEM), transmission electron microscopes, fiber
testers, or the like. In a case of microscopic observation,
cross-sectional observation and observation in a state where both
ends of the one independent fiber are stretched so as to not be cut
away, as necessary, can be performed by carrying out pretreatment,
as appropriate, on the observation sample, as necessary.
[0071] In the sheet manufacturing apparatus 100 of the embodiment,
the fibrous raw material is defibrated by the defibrating unit 20,
and transported to the mixing unit 50 as the first screened
material passing through the classifying unit 30 and the screening
unit 40. The classifying unit 30 may be omitted in cases where the
function (removal of resin powder and ink powder from the
defibrated material) of the classifying unit 30 with respect to web
V are fulfilled by the mesh belt 46 of the screening unit 40 and
the suction unit (suction mechanism) 48. In this case, the
defibrated material defibrated by the defibrating unit 20 is
introduced to the screening unit 40.
1.3. Composite
[0072] The additive agent supplied from the additive agent supply
unit 52 includes a resin for causing the plurality of fibers to
bond. At the point in time at which the resin is supplied, the
plurality of fibers is not bonded. The resin is fused when passing
through the sheet forming unit 80 and the plurality of fibers is
bonded.
[0073] In the embodiment, the additive agent supplied from the
additive agent supply unit 52 is a composite (particles) in which
at least a portion of the surface of the resin particles is covered
by inorganic fine particles. The composite may be used
independently or mixed with another substance, as appropriate.
[0074] The composite of the embodiment receives a frictional
charging action when supplied from the additive agent supply unit
52 and passes through the mixing unit 50 and the deposition unit
60. The charged composite is attached (electrostatically adsorbed)
to the fibers even in a state where attached to the fibers and
deposited with on the mesh belt 72 along with the fibers, to form
the web W.
[0075] The absolute value of the average charging amount of the
composite of the embodiment is 40 .mu.C/g or higher. The absolute
value of the average charging amount of the composite is preferably
60 .mu.C/g or more, more preferably 70 .mu.C/g or more, still more
preferably 80 .mu.C/g or more, and particularly preferably 85
.mu.C/g or more because the higher the value becomes, the more it
is possible for the composite to be strongly or more frequently
attached to the fibers.
[0076] It is possible for the charging amount of the composite to
be measured while the composite is frictionally charged. It is
possible to perform the measurement of the charging amount by
agitating (mixing) a powder, referred to as a standard carrier, and
the composite in air, and measuring the charging amount of the
powder. It is possible to use a standard carrier for a positive
polarity toner or for a negative polarity toner that is a spherical
carrier in which the ferrite core is surface treated available
(standard carrier for positive polarity of negative polarity toner,
available as "P-01" or "N-01") from the Imaging Society of Japan, a
ferrite carrier available from Powdertech Co., Ltd. or the like as
the standard carrier.
[0077] More specifically, it is possible to obtain the absolute
value of the average charging amount of the composite as shown
next. A mixed powder with 80% by weight of the carrier and 20% by
weight of the composite is fed into an acrylic container, the
container is rotated for 60 seconds at 100 rpm while being mounted
to a ball mill table, and the carrier and the composite (powder)
are mixed. It is possible to determine the absolute value
[|.mu.C/g|] of the average charging amount for the mixture in which
the composite and the carrier are mixed by measuring with a compact
draw-off charge measurement device (for example, a Model 210 HS-2,
manufactured by TREK Japan KK).
[0078] By the absolute value of the average charging amount of the
composite being 40 .mu.C/g or higher, it is possible for the
charged composite to be attached (electrostatically adsorbed) to
the fibers even in a state where attached to the fibers and
deposited on the mesh belt 72 along with the fibers, to form a web
W. Such a composite of the embodiment is realized through the
structure, materials, and the like as described below in the next
items.
[0079] It is preferable that the particle diameter of the composite
particles (volumetric average particle diameter) is 50 .mu.m or
less, 30 .mu.m or less is more preferable, 25 .mu.m or less is
still more preferable, and 20 .mu.m or less is particularly
preferable. When the average particle diameter is small, it is
possible to suppress detachment of from the fibers due to the
weight of the particles themselves because the force of gravity
acting on the composite is small, and because the air resistance is
low, it is possible to suppress separation from between the fibers
due to the airflow (wind) arising due to the suction mechanism 76
or the like and separation due to mechanical vibration. If within
the above particle diameter range, it is possible for the composite
to be made sufficiently difficult to detach from the fibers by an
average charging amount of 40 .mu.C/g or higher.
[0080] Although the opening size of the mesh belt 72 can be set, as
appropriate, because the composite attaches to the fibers, passing
through the mesh belt 72 is suppressed even in a case where the
particle diameter of the composite is smaller than the opening size
(size of hole that matter passes through) of the mesh belt 72. That
is, the composite of the embodiment obtains a more remarkable
effect in a case where the particle diameter of the composite is
smaller than the opening size of the mesh belt 72.
[0081] The lower limit of the average particle diameter of the
composite particles is not particularly limited, for example, is 10
.mu.m, and is arbitrary within a range able to be pulverized by a
method of crushing or the like. The average particle diameter of
the composite particle may have a distribution, and, as long as the
resin and the inorganic fine particles are integrated, it is
possible to obtain the effect of suppressing detachment from
between the above-described fibers.
[0082] It is possible to measure the average particle diameter of
the composite particles using a particle size distribution analyzer
in which the measurement principle is the laser diffraction
scattering method. A particle size distribution analyzer in which
the measurement principle is dynamic light scattering (for example,
the "Microtrac UPA", manufactured by Nikkiso Co., Ltd.) is an
example of the particle counter.
[0083] The composite may contain other components. Examples of the
other components include organic solvents, surfactants,
preservative and fungicide agents, antioxidants, ultraviolet
absorbing agents, and oxygen absorbing agents.
1.3.1. Structure of Composite
[0084] The composite is in a state in which inorganic fine
particles cover at least a portion of the surface of the resin
particles, and the resin particles or inorganic fine particles from
the composite are in a state of not easily breaking apart (not
easily divided) in either or both of the sheet manufacturing
apparatus 100 and in the web W or the sheet S. That is, the state
in which inorganic fine particles cover at least a portion of the
surface of the resin particles indicates at least one state of a
state in which the resin and the inorganic fine particles are
kneaded, a state in which inorganic fine particles are attached or
bonded to the surface of the resin particles, a state in which the
inorganic fine particles are structurally (mechanically) fixed to
the surface of the resin particles, and a state in which the resin
particles and the inorganic fine particles are aggregated due to
electrostatic force, Van der Waal's forces or the like. The state
in which inorganic fine particles cover at least a portion of the
surface of the resin particles may also be a state in which the
inorganic fine particles are encapsulated by the resin particles or
a state in which the inorganic fine particles are attached to the
resin. Furthermore, these states may also be present at the same
time. In the specification, the state in which inorganic fine
particles cover at least a portion of the surface of the resin
particles may be a state in which the resin particles and the
inorganic fine particles are integrally included.
[0085] FIG. 2 schematically shows several states of cross-sections
of the composite in which the resin and the inorganic fine
particles are integrally included. Examples of the specific aspects
of the composite in which the resin and the inorganic fine
particles are integrally included include, as shown in FIG. 2A, a
composite co in which the inorganic fine particles in are kneaded
into the resin re and dispersed and at least a portion of the
inorganic fine particles are exposed in the surface of the
composite co.
[0086] As shown in FIG. 2B, the inorganic fine particles in may be
arranged so as to cover the surface of the resin re. That is,
examples of the specific aspect of the composite in which the resin
and the inorganic fine particles are integrally included, as shown
in FIG. 2B, include a composite co in which the inorganic fine
particles in are embedded, bonded to and/or attached to the surface
of the resin re. The bonding and or attachment of both of the
component in the example may be based on electrostatic forces, Van
der Waal's forces, or the like.
[0087] In the structure of the composite co shown in FIGS. 2A and
2B, although the inorganic fine particles in cover a portion of the
surface of the particles of the resin re, the inorganic fine
particles in may cover the entire surface of the particles of the
resin re, or may cover the surface of the particles of the resin re
in multiple layers. A structure may be used in which the structure
shown in FIG. 2A and the structure shown in FIG. 2B are
combined.
[0088] In the examples in FIGS. 2A and 2B, although either of the
external shape of the composite and the external shape of the
inorganic fine particles are schematically shown as close to
spherical, the external shape of the composite and the inorganic
fine particles is not particularly limited, and may be a shape such
as disk-shaped, needle shaped, and an irregular shape. However, it
is more preferable that the shape of the composite approach
spherical as much as possible because of the ease of being arranged
between the fibers in the mixing unit 50.
[0089] The composite with any of the structures shown in FIGS. 2A
and 2B is also not easily divided into the resin and the inorganic
fine particles when mixed in the mixing unit 50. In the present
application, in a case where the resin and the inorganic fine
particles are not divided in the composite, although it is
desirable to be completely undivided with respect to the number of
composite particle of the powder overall, in practice, achieving a
state of being completely undivided is difficult. Therefore, the
undivided state indicates a state in which the 70% or more of the
composite particle are not divided from the resin and the inorganic
fine particles when averages with respect to number of composite
particles in the powder overall.
[0090] It is possible to verify the structure of the composite co
as shown in FIGS. 2A and 2B through various means, such as any
structural analysis method such as an electron microscope. It is
possible to evaluate whether or not the inorganic fine particles
are coated by the resin particles by measuring the angle of repose.
It this possible to measure the angle of repose in compliance with
the method of "Alumina Powder--Part 2: Determination of Physical
Properties--2: Angle of repose" in JIS R 9301-2-2:1999. With
respect to the resin particles not coated by the inorganic fine
particles, it is possible to verify that the angle of repose is
small in a composite coated by the inorganic fine particles.
1.3.2. Function of Composite
[0091] Although several aspects of the composite in which the resin
and the inorganic fine particles are integrally included are given
as examples, even in any of the aspects, the resin and the
inorganic fine particles are not easily isolated, and the composite
adsorbed on the fibers is not easily detached when receiving
various treatments in the sheet manufacturing apparatus 100 or when
the web W or the sheet S is formed.
[0092] The inorganic fine particles have the function of improving
the charging amount of the resin particles (composite) in a case of
being arranged on the surface of the resin particles compared to a
case where the inorganic fine particles are not present. Although
various inorganic fine particles can be used, in the sheet
manufacturing apparatus 100 of the embodiment, it is preferable to
use a type (may be coated (covered) or the like) arranged in the
surface of the composite because little to no water is used.
[0093] The inorganic fine particles cause an adsorptive force
(adhesive force) to arise between the composite and the fibers by
increasing the charging properties of the composite. Therefore,
when deposited as a web W on the mesh belt 72 of the second web
forming unit 70 of the sheet manufacturing apparatus 100, it is
possible to make the composite less easily detach from the fibers.
In so doing, it is possible to make the mechanical strength of the
sheet S manufactured by the sheet manufacturing apparatus 100 a
predetermined strength. That is, since the composite of the
embodiment has a sufficient adhesive force (electrostatic bonding
force) to the fibers when arranged between the fibers, the
composite is not easily detached from the fibers. It is thought the
cause for obtaining such an effect is because there is an action in
which a static electricity is generated by friction and the
composite (resin) is caused to bond to the fibers, due to being
more easily frictionally charged and the composite being mixed with
the fibers in the atmosphere in the mixing unit 50 by the inorganic
fine particles being arranged in the surface of the resin
particles.
1.3.3. Material of Composite
[0094] Although already described, examples of the type of the
resin (component of the resin particles) that is a component of the
composite include a thermoplastic resin or a heat-curable resin,
and is an AS resin, an ABS resin, polypropylene, polyethylene,
polyvinyl chloride, polystyrene, an acrylic resin, a polyester
resin, polyethylene terephthalate, polyphenylene ether,
polybutylene terephthalate, nylon, polyamide, polycarbonate,
polyacetal, polyphenylene sulfide, polyetherether ketone, or the
like. These resins may be used independently or mixed, as
appropriate.
[0095] More specifically, the type of resin (component of the resin
particles) that is a component of the composite may be either a
natural resin or a synthetic resin, and may be either a
thermoplastic resin or a heat-curable resin. In the sheet
manufacturing apparatus 100 of the embodiment, the resin that
configures the composite is preferably a solid at room temperature,
and is preferably a thermoplastic resin in consideration of bonding
the resin due to heat in the sheet forming unit 80.
[0096] Examples of the natural resin include rosin, dammar, mastic,
copal, amber, shellac, dragon's blood palm resin, sandarac, and
colophony, and these resins may be independent or mixed, as
appropriate, and may be modified as appropriate.
[0097] Examples of the heat-curable resin from the synthetic resins
include heat-curable resins such as phenol resins, epoxy resins,
melamine resins, urea resins, unsaturated polyester resins, allkyd
resins, polyurethane, and heat-curable polyimide resins.
[0098] Examples of the thermoplastic resin from the synthetic
resins include AS resins, ABS resins, polypropylene, polyethylene,
polyvinyl chloride, polystyrene, acrylic resins, polyester resins,
polyethylene terephthalate, polyphenylene ether, polybutylene
terephthalate, nylon, polyamide, polycarbonate, polyacetal,
polyphenylene sulfide, and polyetherether ketone.
[0099] Copolymerization or modification may be performed, and
examples of such systems of resin include styrene resins, acrylic
resins, styrene-acrylic copolymer resins, olefin based, polyvinyl
chloride resins, polyester resins, polyamide resins, polyurethane
resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl
resins, and styrene-butadiene resins.
[0100] Meanwhile, examples of the inorganic fine particles include
fine particles formed from inorganic materials, and it is possible
for an extremely superior charging effect to be obtained by
arranging these in the surface of the resin particles
(composite).
[0101] Specific examples of the material of the inorganic fine
particles include silica (silicon oxide), titanium oxide, aluminum
oxide, zinc oxide, cerium oxide, magnesium oxide, zirconium oxide,
strontium titanate, barium titanate, and calcium carbonate. The
inorganic fine particles arranged in the surface of the resin
particles may be a single type or may be a plurality of types.
[0102] Although not particularly limited, the volumetric average
(primary) particle diameter (volume average particle diameter) of
the inorganic fine particles is 1 nm or more to 100 nm or less,
preferably 2 nm or more to 80 nm or less, more preferably 5 nm or
more to 50 nm or less, and still more preferably 10 nm or more to
40 nm or less. Although the inorganic fine particles being primary
particles is normal in light of being close to the category of
so-called nanoparticles, and the particle diameter being small, a
plurality of primary particles may be bonded to form a higher order
particle. The inorganic fine particles of the embodiment have a
small particle diameter, the proportion of the surface area per
weight is larger, and the area when frictionally charged
accordingly is also large. Therefore, it is possible for the
particle diameter of the inorganic fine particles to obtain a
favorable charging effect if within the above ranges. If the
particle diameter of the inorganic fine particles is within the
above ranges, it is possible for the surface of the composite to be
well coated, and also on this point, it is possible to stably
contribute a sufficient charging effect.
[0103] It is possible to measure the average (primary) particle
diameter of the inorganic fine particles according to an
established method from the relationship between the specific
surface area and the density obtained by a BET method or the
like.
[0104] If the content of the inorganic fine particles in the
composite is 0.01% by weight or more to 10% by weight or less to
100% by weight of the composite, it is possible to obtain the above
effects, and from the viewpoint of further increasing the effect
and/or effectively using the inorganic fine particles (when there
are too many inorganic fine particles, even if the addition amount
is increased, the charging amount does not easily increase) or the
like, 0.05% by weight or more to 5% by weight or less to 100% by
weight of the composite is preferable, 0.1% by weight or more to 4%
by weight or less is more preferable, and 0.1% by weight or more to
3% by weight or less is still more preferable.
[0105] The method of arranging (coating) the inorganic fine
particles in the surface of the composite is not particularly
limited, and the inorganic fine particles may be arranged along
with the resin when forming the composite by melt-kneading or the
like as described above. However, if done in this way, because the
inorganic fine particles are largely arranged inside the composite,
the charging amount with respect to the addition amount of the
inorganic fine particles is reduced. It is more preferable that the
inorganic fine particles are arranged as much as possible in the
surface of the composite based on the charge generating mechanism.
Although examples of the form for arranging the inorganic fine
particles in the surface of the composite include coating and
covering, the entire surface of the composite is not necessarily
coated. Although the coverage ratio may exceed 100%, when reaching
approximately 300% or more, because there are cases where the
action of bonding the composite and the fibers is impeded, an
appropriate coverage ratio is selected according to the
situation.
[0106] Although various methods are considered as the method of
arranging the inorganic fine particles in the surface of the
composite, although it is possible to exhibit the effect by simply
mixing together both and being attached to the surface only by
electrostatic force or Van der Waal's forces, the concern of
dropping off remains. Therefore, a method of feeding and uniformly
mixing the composite and the inorganic fine particles in a mixer
that rotates at high speed is preferable. It is possible to use a
known device as such a device, and it is possible to perform mixing
using an FM mixer, a Henschel mixer, a super mixer, or the like. It
is possible to arrange the particles of the inorganic fine
particles in the surface of the composite by such a method. There
are cases where at least a portion of the inorganic fine particles
arranged by such a method are arranged in a state of biting into or
a state of being embedded into the surface of the composite, and it
is possible to make the inorganic fine particles more difficult to
detach from the composite, and it is possible to stably exhibit the
charging effect. When such a method is used, it is possible to
easily realize the above-described arrangement in a system included
little to no water content. Even if inorganic fine particles that
do not bite into the composite are present, it is possible for such
an effect to be sufficiently obtained. It is possible for the
states in which the inorganic fine particles bite into or are
embedded in the surface of the composite to be verified by various
electron microscopes.
[0107] If the proportion coved by the inorganic fine particles in
the composite surface (area ratio: in the specification, may be
referred to as the coverage ratio) is 20% or more to 100% or less,
it is possible to obtain a sufficient charging effect. It is
possible to adjust the coverage ratio by incorporating in a device
such as an FM mixer. If the specific surface area of the inorganic
fine particles and the composite is known, it is possible to
perform regulation by the weight (mass) of each component when
incorporated. It is possible to measure the coverage ratio with
various electron microscopes. In a case where the inorganic fine
particles are arranged in a form of being not easily detached from
the composite, it is possible for the inorganic fine particles to
be integrally included in the composite.
[0108] The inorganic fine particles may be subjected to surface
modification. Specifically, the surface of the inorganic fine
particles may be modified by chemically treating the surfaces
thereof with a silane compound and these may be used. Examples of
such a silane compound include alkyl silanes, such as trimethyl
silane, dimethyl silane, triethyl silane, triisopropyl silane, and
triisobutyl silane, and silane coupling agents such as
vinyltrimethoxy silane and vinyltriethoxy silane.
[0109] Because the composite includes inorganic fine particles, the
composite easily electrostatically attaches to the fibers, and it
is possible to make dropping from the fibers and dropping from the
web and sheet less easily arise. It is possible to extremely
favorably mix together the composite and the fibers due to the
agitation of the airflow or mixer. Examples of reasons therefor
include a tendency for the composite to become easier to charge
with static electricity in a case where inorganic fine particles
are arranged in the surface of the composite, and the composite
becomes easier to attach to the fibers due to the static
electricity. The composite attached to the fibers by to the static
electricity becomes less easily detached from the fibers even in
cases where a mechanical impact or the like occurs. Therefore,
mixing is quickly performed and dropping off sufficiently
suppressed without using a special unit other than for mixing the
fibers and the composite. Attachment of the composite to the fibers
after mixing is stabilized, no detachment phenomenon is observed in
the composite.
[0110] It is thought that the composite particles become more
strongly attached to the fibers by the electrostatic force than in
a case of independent resin particles. Even in a case where the
resin particles include a pigment, it is found that the effect of
the inorganic fine particles is not impeded. Although it is
ordinarily difficult for static electricity to accumulate when the
moisture is high, the adhesive force of the composite to the fibers
is improved by the presence of the inorganic fine particles even if
some measure of water content is included in a case where the
fibers are cellulose.
1.3.4. Other Components
[0111] Although it has been described that coloring agents for
coloring fibers, or flame retardants for making fibers or the like
more difficult to burn may be included in the composite, in cases
where at least one type of these is included, it is possible for
these effects to be more easily obtained by blending these into the
resin by melt-kneading. It is possible to blend the inorganic fine
particles by mixing the resin powder and the inorganic fine
particle powder with a high speed mixer or the like after forming
such as resin powder.
[0112] Although the above-described fibers and composite are mixed
together in the mixing unit 50, it is possible for the mixing ratio
thereof to be regulated, as appropriate, according to the strength,
usage, or the like of the manufactured sheet S. If the manufactured
sheet S is for a work usage, such as copy paper, the proportion of
the composite to the fibers is 5% by weight or more to 70% by
weight or less, and from the viewpoints of obtaining favorable
mixing in the mixing unit 50 and making the composite more
difficult to detach due to gravity in a case where the mixture is
formed in a sheet-shape, 5% by weight or more to 50% by weight of
less is preferable.
1.4. Mixing Unit
[0113] The mixing unit 50 provided in the sheet manufacturing
apparatus 100 of the embodiment has a function of causing the
fibers and the composite to be mixed together. At least the fibers
and the composite are mixed together in the mixing unit 50. In the
mixing unit 50, components other than the fibers and the composite
may be mixed together. The wording "the fibers and the composite
are mixed together" is defined as the composite being positioned
between the fibers in a space (system) with a fixed volume.
[0114] The process of mixing together in the mixing unit 50 of the
embodiment is a method (dry-type) in which the fibers and the
composite are introduced into the airflow and diffused together in
the airflow, and is a fluid dynamic mixing process. The wording
"dry-type" in the mixing refers to the state of being mixed
together in air rather than in water. That is, the mixing unit 50
may function in the drying state, or may function in a state where
a liquid present as an impurity or an intentionally added liquid is
present. In the case of intentionally adding the liquid, it is
preferable for the liquid to be added to an extent that the energy
and time for removing the liquid through heat or the like do not
increase excessively in later processes. In the method, this is
more preferable because the airflow in the pipe 54 or the like
being turbulent make the mixing together efficient.
[0115] The processing capacity of the mixing unit 50 is not
particularly limited as long as it is able to cause the fibers
(fibrous material) and composite to mix together, and it is
possible to regulate the design, as appropriate, according to the
manufacturing capacity (throughput) of the sheet manufacturing
apparatus 100. It is possible for the regulation of the processing
capacity of the mixing unit 50 to be performed by the flow rate of
the gas for transferring the fibers and the composite in the pipe
54, the introduction rage of the material, and the transfer rate or
the like being changed.
[0116] The mixture mixed together by the mixing unit 50 may be
further mixed by another configuration such as a sheet forming
unit. In the example in FIG. 1, although the mixing unit 50
includes a blower 56 provided in the pipe 54, a further blower, not
shown, may be included.
[0117] The blower is a mechanism in which the fibers and the
composite are mixed, and includes a rotary unit having blades that
rotate. By the blades rotating, either or both of the fibers and
the composite are rubbed by the blades or impact the blades. By the
blades rotating, any or all of the fibers and the fibers, the
fibers and the composite and the composite and the composite impact
each other and rub against one another according to the airflow
formed by the blades.
[0118] It is thought that due to such impact or rubbing, at least
the composite is charged (charged with static electricity), and an
adhesive force (electrostatic force) for attaching the composite to
the fibers is generated. The strength of such an adhesive force
depends on the properties of the fibers and the composite and the
structure (shape and the like of the rotating blades) of the
blower. Even in cases where one blower 56 is provided as shown in
FIG. 1, although it is possible to obtain a sufficient adhesive
force, there are cases where it is possible to obtain a stronger
adhesive force by further providing another blower on the
downstream side of the additive agent supply unit 52. The
increasing number of blowers is not particularly limited. In a case
of providing a plurality of blowers, the main functions of the
blowers may be divided such as providing a blower with a strong air
blowing force, a blower with a larger agitation force (capability
caused by being charged) or the like. In this way, there are cases
where it is possible for adhesive force of the composite to the
fibers to be further increased, and it is possible for detachment
of the composite from between the fibers to be further suppressed
when forming the web W.
1.5. Actions and Effects
[0119] For the sheet manufacturing apparatus 100 of the embodiment,
because the composite mixed with the fibers in the mixing unit 50
has at least a portion of the surface of the resin particles coated
by the inorganic fine particles, the composite is not easily
detached from between the fibers when the web is formed. Since the
composite and the fibers are bonded in the sheet forming unit 80,
it is possible for the dispersibility of the resin to be favorable,
and to manufacture a sheet with favorable uniformity of strength
and the like.
[0120] The composite used in the sheet manufacturing apparatus 100
of the embodiment has a much superior adhesive force with the
fibers. By the inorganic fine particles being integrally added to
the resin, the composite particles are easily charged with static
electricity, the electric charging amount as a result increases,
and the adhesive force to the fibers is improved according to the
nature of being easily charged with static electricity that the
inorganic fine particles have.
[0121] The sheet manufacturing apparatus of the embodiment
includes, in the second web forming unit 70, the mesh belt 72 and
the suction mechanism 76 that form the web W, and it is possible
for the suction mechanism 76 to be the suction unit that suctions
the mixture discharged by the deposition unit 60 via the mesh belt
72. By the suction unit performing suction via the mesh belt,
although the possibility of the composite detaching from the fibers
increases, according to the sheet manufacturing apparatus of the
embodiment, it is possible to suppress detachment of the composite
from the fibers regardless of whether a suction unit is
included.
2. Sheet Manufacturing Method
[0122] The sheet manufacturing method of the embodiment includes a
step of mixing the fibers and the composite, in which the resin and
the inorganic fine particles are integrated, in air, and a step of
depositing, heating and forming a mixture in which the fibers and
the composite are mixed. Because the fibers, the resin, the
inorganic fine particles, and the composite are the same as those
described in the above-described sheet manufacturing apparatus
item, detailed description thereof will not be provided.
[0123] The sheet manufacturing method of the embodiment may include
at least one step selected from a group composed of a step for
cutting a pulp sheet or recycled paper as a raw material in air, a
defibrating step of disentangling the raw material in air into a
fibrous form, a classifying step of classifying, in air, impurities
(toner or paper strengthening agent) and fibers (short fibers)
shortened by defibration from the defibrated material that is
defibrated, a screening step of screening, in air, long fibers and
undefibrated pieces that are insufficiently defibrated from the
defibrated material, a dispersing step of causing the mixture to
descend while being dispersed in air, a forming step of forming the
descended mixture in a web shape or the like while being deposited,
a drying step of causing the sheet to be dried as necessary, a
winding step of winding the formed sheet into a roll shape, a
cutting step of cutting the formed sheet, and a packaging step of
packaging the manufactured sheet. The details of these steps are
the same as those described in the above-described sheet
manufacturing apparatus, and thus detailed description will not be
repeated.
3. Sheet
[0124] The sheet S manufactured by the sheet manufacturing
apparatus 100 or the sheet manufacturing method of the embodiment
indicates a sheet in which at least the above-described fibers are
the raw material and formed into a sheet form. However, there is no
limitation to a sheet form, and the shape may be a board form, web
form, or a shape having concavities and convexities. The sheets in
the specification can be classified into paper and non-woven
fabric. Paper includes forms in which pulp or recycled paper as a
raw material is formed in a sheet shape, and includes recording
paper for the purpose of writing or printing, wallpaper, packaging
paper, colored paper, image paper, Kent paper and the like.
Non-woven fabric is a product thicker than paper or with low
strength, and includes ordinary non-woven fabrics, fiber boards,
tissue papers, kitchen papers, cleaners, filters, liquid absorbing
materials, sound absorbers, shock absorbers, mats, and the
like.
[0125] In the case of a non-woven fabric, the gap between fibers is
wide (density of the sheet is low). In contrast, the paper has a
narrow gap between fibers (density of the sheet is high).
Therefore, the sheet S manufactured by the sheet manufacturing
apparatus 100 or the sheet manufacturing method of the embodiment
being a paper is more able to remarkably express the action and
function of suppressing detachment of the composite from the
fibers, uniformity of strength when formed as a sheet or the
like.
4. Accommodation Container
[0126] The accommodation container of the embodiment is used while
the fibers are mixed and accommodates the above-described composite
in which the resin and the inorganic fine particles are
integrated.
[0127] The composite of the embodiment is supplied to the mixing
unit 50 according to the opening and closing of a filter or valve.
The composite of the embodiment is supplied in a powdered state in
appearance. Therefore, it is possible to configure the apparatus so
that the composite is directly supplied to the mixing unit 50
through a pipe or the like after being manufactured. However,
according to the installation location of the apparatus, it is
thought that the composite is carried along a flow path as a
commodity, and there are cases where transfer or storage is
performed after the composite is manufactured.
[0128] The accommodation container of the embodiment includes an
accommodation chamber that accommodates the composite, and it is
possible for the composite to be accommodated in the accommodation
chamber. That is, it is possible for the accommodation container of
the embodiment to be a composite cartridge, and it is possible to
easily transport and store the composite.
[0129] The shape of the accommodation container is not particularly
limited, and it is possible for the shape to be made a cartridge
shape suitable to the sheet manufacturing apparatus 100. It is
possible to form the accommodation container with an ordinary
polymer material. The accommodation container may also be a
box-like robust form, or may be a film-(bag) like flexible form. It
is preferable that the material that configures the accommodation
container is configured from a material with a high
glass-transition temperature or melting point compared to the
material of the accommodated composite.
[0130] The accommodation chamber that accommodates the container is
not particularly limited as long as it is able accommodate and hold
the composite. It is possible for the accommodation chamber to be
formed from a film, a molded body or the like. In a case where the
accommodation chamber is formed by a film, the accommodation
container may be formed including a molded body (housing) so as to
accommodate the film that forms the accommodation chamber. The
accommodation chamber may be formed by a comparatively robust
molded body.
[0131] The film or molded body that forms the accommodation chamber
may be configured from a polymer, a metal deposition film or the
like, and may have a multilayer structure. In a case where the
accommodation container is formed by a plurality of members such as
a film or molded body, fused parts or bonded parts may be formed.
In a case where the accommodated composite (powder) is influenced,
such as deterioration, due to contact with the atmosphere, it is
preferable that the film or molded body is formed from a material
with little gas permeability. It is preferable that the material of
the part that contacts the accommodated composite from the
materials of the film and molded body that configure the
accommodation chamber is stable with respect to the composite.
[0132] The shape and volume of the accommodation chamber is not
particularly limited. Although the composite is accommodated in the
accommodation chamber, an inactive solid or gas may be accommodated
in contrast thereto. The volume of the composite accommodated in
the accommodation chamber is also not particularly limited.
[0133] The accommodation chamber may include a flow port that
communicates between the interior of the accommodation chamber and
the exterior of the accommodation container, and is able to remove
the composite to the outside of the composite. The accommodation
chamber may have another flow path other than the flow port formed
therein. The other flow path may be configured by a release valve
or the like. In a case of providing the release valve in the
accommodation chamber, although the position at which the release
valve is arranged is not particularly limited, there are cases
where providing the release valve is preferable because the
composite is not easily discharged when the pressure is released to
the atmosphere in cases where pressure and the like is generated in
the accommodation chamber when arranged on the opposite side to the
direction in which gravity acts in the normal posture when
transferred, transported, and used.
5. Other Provisions
[0134] Although the sheet manufacturing method and sheet
manufacturing method of the embodiment use no or only a small
amount of water, it is possible to manufacture the sheet while
adding water, as appropriate, with the object of adjusting the
moisture or the like, through spraying or the like as
necessary.
[0135] It is preferable to use pure waters such as ion-exchange
water, ultrafiltered water, reverse osmosis water, and distilled
water or ultrapure water as the water. In particular, because water
in which these waters are subjected to sterilization treatment by
irradiation with ultraviolet rays or addition of hydrogen peroxide
is able to suppress the generation of mold and bacteria over a long
period of time, such water is preferable.
[0136] In the specification, the phrasing "uniform" indicates, in a
case of uniform dispersion or mixing, the relative positions where
one component is present with respect to the other component are
even in the entire system or are the same or substantially equal in
each part of the system to one another in a substance able to
define a component with two types or more or two phases or more.
Uniformity of coloring or uniformity of tone indicates an even
concentration without tinting of the color when the sheet is seen
in plan view.
[0137] In the specification, phrasing such as "uniform", "same",
"even intervals" and the like are used to indicate that density,
distance, measurement or the like are the same. Although it is
desirable that these are equal, because being made completely equal
is difficult, the wording includes being shifted by the cumulative
errors or variations without the values being equal.
6. EXAMPLES
[0138] Below, although the present disclosure will be further
described by the examples shown, the invention is not limited to
the examples below.
6.1. Preparation of Composite
[0139] (1) styrene-maleic acid resin (Tg: 74.degree. C., molecular
weight 6600): 1.5 kg
[0140] (2) polyester resin (Tg: 56.degree. C., molecular weight
10000): 8.0 kg
[0141] (3) copper phthalocyanine pigment (Pigment Green 36): 0.5 kg
After the above materials were mixed in the hopper, the materials
were fed to a twin screw kneading extruder and melt-kneading was
performed at 90.degree. C. to 135.degree. C. The material was
extruded by dicing to form strands, and cut into approximately 5 mm
lengths to obtain tables.
[0142] After the tablets obtained above were subjected to
processing for 30 seconds in a high speed mill and the tablets were
roughly crushed into a granular form, the material was fed to a jet
mill to obtain a powder with a particle diameter range of 1 .mu.m
to 40 .mu.m.
[0143] Powdered resin particles (Al) configured from particles with
a volumetric average particle diameter of 12 .mu.m and a particle
diameter range of 5 .mu.m to 23 .mu.m were obtained from the
obtained powder obtained using the jet mill in the classifying
device.
6.2. Example 1
[0144] (1) resin particles (A1): 100 g
[0145] (2) inorganic fine particles (M1): 1.5 g By feeding the
above materials into a tabletop blender, and agitating at a tip
speed of 30 m/s for 80 seconds, the surface of the resin particles
(A1) is coated with the inorganic fine particles (M1). The presence
of a coating was verified by observing the particle surface with an
SEM. Verification was also performed according to changes in the
angle of repose were also verified. This is determined from the
angle of repose decreasing when the coating (covering by inorganic
fine particles) is formed. The inorganic fine particles (M1) use
titanium dioxide in which the volumetric primary particle diameter
in which the surface is subjected to hydrophobizing treatment with
alkyl silane is 14 nm.
6.3. Example 2
[0146] Fine particles of silicon dioxide with a volumetric primary
particle diameter of 12 nm in which the surface is modified by
trimethyl silane are the inorganic fine particles (M2). Other than
using the inorganic fine particles (M2) instead of the inorganic
fine particles (M1) used in Example 1, Example 2 is the same as
Example 1.
6.4. Example 3
[0147] Fine particles of silicon dioxide with a volumetric primary
particle diameter of 20 nm in which the surface is modified by
trimethyl silane are the inorganic fine particles (M3). Other than
using the inorganic fine particles (M3) instead of the inorganic
fine particles (M1) used in Example 1, Example 3 is the same as
Example 1.
6.5. Example 4
[0148] Fine particles of silicon dioxide with a volumetric primary
particle diameter of 20 nm in which the surface is modified by
trimethyl silane are the inorganic fine particles (M4). Other than
using the inorganic fine particles (M4) instead of the inorganic
fine particles (M1) used in Example 1, Example 4 is the same as
Example 1.
6.6. Example 5
[0149] Resin particles (A1) without any coating on the surface were
formed.
6.7. Measurement of Charging Amount
[0150] (1) Standard Carrier N-01 (available from the Imaging
Society of Japan): 4.85 g
[0151] (2) Powder of each example (composite or resin particles):
0.15 g
[0152] The above materials were fed to an acrylic container, the
container rotated for 180 seconds at 100 rpm with the container
mounted to a ball mill table, and the carrier and particles
(powder) were mixed. The absolute value [|.mu.C/g|]of the average
charging amount of mixture in which the powder and the carrier are
mixed was obtained with a compact draw-off charge measurement
device (manufactured by TREK Japan KK, Model 210 HS-2), and
disclosed in Table 1.
6.8. Evaluation of Retention Rate of Particles to Fibers
[0153] (1) Nadelbaume Kraft Pulp (NBKP): 16 g
[0154] (2) Composite Particles (Examples 1 to 4) or resin particles
(Example 5): 4 g
[0155] (3) Particle Content Rate: 4 g/(16 g+4 g)=20% by weight The
above masses were weighed and introduced to a 520 mm.times.600
nm.times.0.030 mm transparent polyethylene bag, air was blown in
with an air gun, and pulp and the composite or resin particles were
agitated by the airflow to mix a mixture (powder of each example)
of pulp and the composite or pulp and the resin particles.
[0156] 5.0 g of each powder of each example was extracted and
gently spread equally on a 140 mesh standard sieve with tweezers.
Thereafter, the sieve was covered and set on a suction device on
the upper side of the sieve. FIG. 3 shows a schematic view of the
suction device 200. The suction device 200 used is a self composed
device, and is formed from a funnel-type funnel portion 220 on
which the sieve 210 is set, a discharge device 230, and a discharge
filter 240 with the configurations shown in FIG. 3. In the
apparatus, in a case where a sieve 210 on which nothing is mounted
is provided, the discharge speed of the discharge device 230 is
adjusted so that the air speed at the mesh surface of the sieve 210
becomes 25.+-.1 m/s. As long as the wind speed conditions are
satisfied, the form of the device may not necessarily be as shown
in FIG. 3. The value when the mass of each remaining mixed body
after suction was performed for 30 seconds with the sieve 210 set
on the suction device 200 in a state where each mixed body is
interposed by the sieve 210 is X(g).
[0157] Here, the particle retention rate RV (%) is derived
according to the formula
RV=(5.times.0.2-(5-X))/(5.times.0.2).times.100=(X-4).times.100. It
is shown that the higher the particle retention rate, the more of
the mixed body is held between the fibers of the pulp, and if the
RV=100%, particles of the mixed body do not pass through the sieve
210 due to suction, and it can be said to be ideal. The particle
retention rate of each example is disclosed in Table 1.
[0158] Although the weight of the mixed body interposed with the
sieve 210 in each example is made 5.0 g, the mass may be regulated,
as appropriate, from the testing efficiency. However, in each sieve
210 used in measurements, a volume of mixed body able to cover the
entire surface of the sieve plane. In a case where a mass of mixed
body that satisfies these conditions is selected, the value of RV
obtained tends to not depend on the mass of the mixed body.
TABLE-US-00001 TABLE 1 Particle Coating Type of Inorganic Fine
Particle Example Particles and Volume Average Charging Amount
Retention Rate No. Particle Diameter Surface Modification
[|.mu.mC/g|] [%] 1 Titanium Dioxide Particle Triisobutyl Silane 94
97 Diameter 14 nm 2 Silicon Dioxide Particle Trimethyl Silane 88 95
Diameter 12 nm 3 Silicon Dioxide Particle Trimethyl Silane 75 93
Diameter 20 nm 4 Silicon Dioxide Particle Trimethyl Silane 41 79
Diameter 40 nm 5 Not Used -- 25 59
6.9. Evaluation Result
[0159] The sample characteristics and particle retention rate for
each example are summarized in Table 1.
[0160] As in the above Table 1, it is determined that the charging
amount of the obtained powder is able to be controlled by changing
the coating state due to the inorganic fine particles of the resin
particles. It is understood that it is possible to control the
particle retention rate with respect to the pulp fibers by
controlling the charging amount. It is thought that as the charging
amount of the particles (composite) increases, the particle
retention rate tends to increase, and the particle retention rate
increasing is a state where the resin particles of the composite
are firmly attached to the pulp fibers (cellulose) and not easily
detached.
[0161] In light of Table 1, it is further found that since the
particle retention rate becomes approximately 80% or more when the
absolute value of the average charging amount is 40 .mu.C/g or
more, a level that is not damaged in sheet manufacturing in
practice is attained. It is found that when the absolute value of
the average charging amount is 80 .mu.C/g or more the particle
retention rate becomes 95% or more, and detachment from the fibers
of the resin particles (composite) becomes extremely low, and is
more favorable.
[0162] When the composite is a composite having a charging amount
in the ranges as in Examples 1 to 4, the resin component is not
easily detached from the fibers when manufacturing the sheet with a
dry method, and, as a result, a tough sheet can be manufactured
according to the design.
[0163] The present disclosure is not limited to the embodiments
described above, and further, various modifications thereof are
possible. For example, the invention includes configurations which
are substantially the same as the configurations described in the
embodiments (for example, configurations having the same function,
method, and results, or configurations having the same purpose and
effect). The invention includes configurations in which
non-essential parts of the configurations described in the
embodiments are replaced. The invention includes configurations
exhibiting the same actions and effects as the configurations
described in the embodiments or configurations capable of achieving
the same object. The invention includes configurations in which
known techniques were added to the configurations described in the
embodiments.
* * * * *