U.S. patent application number 10/829501 was filed with the patent office on 2004-10-21 for resin recycling system.
This patent application is currently assigned to Techno Polymer Co. Ltd.. Invention is credited to Imai, Takateru, Ishikawa, Kouji, Urabe, Kenichi.
Application Number | 20040206834 10/829501 |
Document ID | / |
Family ID | 26598516 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040206834 |
Kind Code |
A1 |
Imai, Takateru ; et
al. |
October 21, 2004 |
Resin recycling system
Abstract
A system for recycling reusable resin mold products recovered
from discarded apparatuses is disclosed. This recycling system
includes a crushing system for crushing resin mold products one
kind by one kind into crushed resinous pieces and packing the same
in a bag, a classification system for irradiating a light beam to
the resin in the bag and classifying the bags into respective kinds
of resins based on a reflected beam therefrom, a cleaning system
for separately cleaning the respective kind of crushed resinous
pieces taken out of the bag to remove foreign matters adhered onto
the surfaces of the crushed resinous pieces therefrom, and a
recovery system for recovering the cleaned crushed resinous
pieces.
Inventors: |
Imai, Takateru; (Tokyo,
JP) ; Urabe, Kenichi; (Tokyo, JP) ; Ishikawa,
Kouji; (Tokyo, JP) |
Correspondence
Address: |
FITCH EVEN TABIN AND FLANNERY
120 SOUTH LA SALLE STREET
SUITE 1600
CHICAGO
IL
60603-3406
US
|
Assignee: |
Techno Polymer Co. Ltd.
|
Family ID: |
26598516 |
Appl. No.: |
10/829501 |
Filed: |
April 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10829501 |
Apr 22, 2004 |
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09939388 |
Aug 24, 2001 |
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6742529 |
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Current U.S.
Class: |
241/68 |
Current CPC
Class: |
B03B 9/061 20130101;
B29L 2031/3425 20130101; B29K 2705/00 20130101; B29K 2105/0026
20130101; B07C 5/3422 20130101; B29B 2017/0203 20130101; B29B
2017/0279 20130101; B29B 17/0412 20130101; B29L 2031/744 20130101;
B02C 19/0006 20130101; B29L 2009/005 20130101; B29B 17/02 20130101;
B29K 2711/12 20130101; G01N 21/65 20130101; G01N 33/442 20130101;
B07C 2501/0054 20130101; B07C 5/342 20130101; B29B 2017/0241
20130101; Y02W 30/52 20150501; B02C 18/0076 20130101; Y10S 241/38
20130101; B29B 2017/0015 20130101; Y02W 30/62 20150501; B07C
2501/0036 20130101; B29K 2025/00 20130101; B29K 2105/065 20130101;
B29L 2007/00 20130101; B29B 2017/0234 20130101; B29B 2017/0289
20130101; B29K 2055/02 20130101; B29K 2069/00 20130101 |
Class at
Publication: |
241/068 |
International
Class: |
B02C 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2000 |
JP |
2000-256202 |
Feb 23, 2001 |
JP |
2001-047750 |
Claims
What is claimed is:
1. A resin recycling system-comprising: crushing means for
individually crushing resin mold products into crushed resinous
pieces in which 70% or more of the crushed resinous pieces have an
equivalent diameter in a range from 1 to 50 mm; packing means for
packing the crushed resinous pieces of the respective mold product
into a bag having a transparent portion; classification means for
irradiating a light beam to the crushed resinous pieces in the bag
through the transparent portion, identifying a kind of the crushed
resinous pieces based on a reflected beam therefrom, and
classifying the bags into respective kinds of resins; and cleaning
means for taking the crushed resinous pieces out from the bag and
cleaning the crushed resinous pieces of the respective kind to
remove foreign matters adhered on the surface thereof.
2. A resin recycling system as defined by claim 1, further
comprising: recovery means for separating foreign matters from a
mixture of the crushed resinous pieces and the foreign matters, and
recovering the crushed resinous pieces.
3. A resin recycling system as defined by claim 1, wherein said
cleaning means comprises a cleaning vessel and an agitating member
provided in the cleaning vessel, and an abrasive surface for
removing the foreign matters on the surface of the crushed resinous
pieces is provided on at least part of the inner wall of the
cleaning vessel and/or the surface of the agitating member.
4. A resin recycling system as defined by claim 2, wherein said
cleaning means comprises a cleaning vessel and an agitating member
provided in the cleaning vessel, and an abrasive surface for
removing the foreign matters on the surface of the crushed resinous
pieces is provided on at least part of the inner wall of the
cleaning vessel and/or the surface of the agitating member.
5. A resin recycling system as defined by claim 1, further
comprising: conveyor means for conveying the bag; and wherein said
classification means comprises identification means, provided in
the vicinity of a predetermined identification position on a
conveying path of said conveyor means, for irradiating a light beam
to the crushed resinous pieces in the bag through the transparent
portion of the bag passing by the identification position and
identifying the kind of the crushed resinous pieces based on a
reflected beam therefrom, and storage means for storing the
identified kind of crushed resinous pieces and an expected arrival
time at which the bag of the crushed resinous pieces would reach a
predetermined classification position on the conveying path, while
maintaining the correspondence between both the stored data, said
classification means being disposed in the vicinity of said
predetermined classification position, and operating to classify
and collect the respective bag as the crushed resinous pieces in
the bag reaching the classification position is of the kind stored
in correspondence to the expected arrival time which is the same as
the current time.
6. A crusher comprising: an endless conveyor for conveying polymer
mold products, and an opposed member having an opposed surface
confronting at least one end of said endless conveyor on a
conveying-directional side and disposed so that a distance between
the opposed surface and a conveying surface of said endless
conveyor becomes smaller in a conveying direction, wherein crushing
edges or crushing pins are provided on at least one of the
conveying surface of said endless conveyor and the opposed surface
of said opposed member, to direct toward the other, whereby the
polymer mold products transported by said endless conveyor are
pushed into a gap between the conveyor and the opposed member and
crushed with said crushing edges or pins.
7. A crusher as defined by claim 6, wherein the crushing edges or
pins are provided on the conveying surface of said endless
conveyer, and recesses or holes are provided on the opposed surface
of said opposed member for allowing tip ends of the crushed edges
or pins provided on said endless conveyor to pass through the
same.
8. A crusher as defined by claim 6, wherein said opposed member
comprises a second endless conveyor.
9. An identification device for irradiating a light beam to a
polymer product being conveyed by conveyor means, detecting the
reflected beam or the dispersed beam from the polymer product by a
sensor element, and identifying a kind of the polymer product based
on a detected result, wherein said sensor element is disposed at a
predetermined position in the vicinity of a conveying path of the
polymer product, and a distance determination mechanism is disposed
in said conveying means or in the vicinity thereof, for opposing
the polymer product passing by said sensor element to said sensor
element at a predetermined distance between the both.
10. An identification device as defined by claim 9, wherein said
conveyor means comprises an endless conveyor and said sensor
element is disposed at a predetermined position beneath the
conveying path constituted by said endless conveyor, and said
distance determination mechanism comprises a light window provided
at each of portions of said endless conveyor passing over the
predetermined position.
11. An identification device as defined by claim 9, wherein the
conveyor means comprises an endless conveyor and said sensor
element is disposed at a predetermined position on a side of the
conveying path constituted by said endless conveyor, and said
distance determination mechanism comprises a stopper member having
a light window and disposed in front of said sensor element in the
vicinity thereof and a guide for guiding the polymer product
carried on said endless conveyor so that the polymer product is
pushed against the light window of the stopper member to be able to
pass by a front of said sensor element.
12. A method for cleaning thermoplastic resinous products,
comprising the steps of: crushing the collected thermoplastic
resinous products into crushed pieces, supplying the crushed pieces
together with water into a cleaning device having a vessel and a
rotary body disposed in a rotatable manner within the vessel,
wherein at least part of the inner surface of the vessel and/or a
surface of the rotary body is roughened, rotating the rotary body
and cleaning the crushed pieces.
13. A method for cleaning thermoplastic resinous products as
defined by claim 12, wherein the roughening is carried out so that
the surface irregularity having a depth in a range from 40 to 2000
.mu.m is provided on at least part of the inner surface of the
vessel and/or the surface of the rotary body.
14. A method for cleaning thermoplastic resinous products as
defined by claim 12, wherein water is continuously supplied from a
plurality of portions of the vessel and drained so that a water
level in the cleaning device is maintained constant, while taking
care to maintain a ratio in weight of the crushed pieces to the
water constant.
15. A method for cleaning thermoplastic resinous products as
defined by claim 12, wherein the cleaning is carried out under the
condition in that the ratio in weight of the crushed pieces to the
water in the cleaning device is controlled to be 1:0.3 to 2.0;
water is continuously supplied and drained so that the interior
temperature of the cleaning device is 70.degree. C. or lower; and a
linear speed of a portion of the rotary body farthest from a rotary
shaft of the rotary body is in a range from 0.5 to 20 m/sec.
16. A device for cleaning thermoplastic resinous products
comprising a vessel and a rotary body built-in in the vessel,
wherein the vessel has an entrance port for the thermoplastic
resinous products provided in an upper area of one end thereof, an
exit port for the thermoplastic resinous products provided in a
lower area of the other end thereof, a water supply port and a
drainage port; the drainage port being connected to a drainage line
for adjusting a water level; the rotary body having a rotary shaft,
a screw blade provided on the circumference of the rotary shaft and
at least one of a plurality of cleaning plates and cleaning pins;
and at least part of the inner surface of the vessel and/or
surfaces of at least one of the cleaning plates and the cleaning
pins being roughened.
17. A device for cleaning thermoplastic resinous products
comprising a vessel and agitating blades, wherein the vessel has an
entrance port for crushed resinous pieces and a water supply port,
both provided in an upper portion thereof, and an exit port for the
crushed resinous pieces and a drainage port, both provided in a
lower portion provided thereof; a drainage line for adjusting a
water level being connected to the drainage port, and at least part
of the inner surface of the vessel and/or surfaces of the agitating
blades being roughened.
Description
[0001] This application is based on Patent Application Nos.
2000-256202 filed Aug. 25, 2000 in Japan and 2001-047750 filed Feb.
23, 2001 the content of which is incorporated hereinto by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a system for recycling
resinous materials from resin mold products recovered from
discarded apparatuses (such as home electric appliances, electronic
devices or cars), more particularly to a crushing system for
crushing polymer parts obtained by disassembling the recovered
products to reduce the volume thereof; a classifying system for
classifying the resinous materials into their kinds, preferably
into kinds of fire retardants added thereto; and a cleaning system
for removing foreign matters such as coated films, labels or seals
applied to the products or other contamination thereof.
[0004] 2. Description of the Related Art
[0005] Plastics light in weight and excellent in mechanical
strength have often been used for home electric appliances, OA
apparatuses, communication apparatuses or others as internal parts
or external casings thereof. From a point of view of the
environmental protection, the conversion from a
mass-production/mass-scrap economy in the past to a circulation
type economy is required. In such a recent trend, a full-scale
recycle of resinous products has been urgently demanded; for
example, the recycling of home electric appliances has been
obligated by law. However, regarding the material recycle in which
the resin mold products are recovered and reused as resinous
materials, it is done solely in a case wherein it is possible to
specify to some extent what kind of resin is used, because there is
a problem peculiar to the resin in that if different kinds of
resins are mixed together, functions inherent to the resin are
significantly damaged. Accordingly, a resin recycling system is
desired, which is capable of correctly classifying various kinds of
resinous products used in the discarded appliances or apparatuses
and regenerating the same as fresh resinous materials for the home
electric appliances, OA apparatuses or communication
apparatuses.
[0006] To proceed a high-quality recycling, it is necessary to
correctly identify and classify materials of resin mold products
containing various kinds of additives including fire retardant.
Regarding the identification of materials of the resin mold
products, a high-performance resin identification device has
recently been developed, and is becoming reality. This device,
however, necessitates a considerable care on the operation,
maintenance and inspection thereof as well as it is expensive in
cost. The most effective method for identifying materials of the
resin mold products solely from a point of view of the material
identification is to provide such a resin identification device in
each of the disassembly factories. This method is, however,
problematic from the economical view point or a view point of
stable operation of the system.
[0007] To operate the above-mentioned resin identification device
under the stably controlled condition, it is desirable to provide
the disassembly factory for recovering the resin mold products at a
position different from that of the resin identification device. In
such a case, it is necessary to convey the resin mold products from
the disassembly factory to the position at which the resin
identification device is provided.
[0008] However, the resin mold products obtained from the discarded
apparatuses have various shapes and sizes distributed from a small
one to an extremely large one. Therefore, if they are packed into a
box or a bag while maintaining their shapes, the physical
transportation cost becomes wasteful since a bulk specific weight
is very small to reduce a weight relative to a volume thereof.
Accordingly, it is desired to crush the resin mold products into
pieces having an economically preferable size (a size capable of
achieving a proper transportation efficiency). As a crusher used
for this purpose, it is possible to use a commercially available
crusher such as a hammer mill, a cutter mill, a two-axis crusher
and the like which is capable of crushing the resin mold products
into pieces having about 50 mm or less in size.
[0009] However, the resin mold products recovered from
disassembling appliances have various sizes as set forth above. In
order to load all of the resin mold products and crush them into
pieces having about 50 mm or less in size, it becomes necessary to
provide a very big crusher having a loading opening. Since these
equipment is costly, there is a problem that it is economically
impossible to install such expensive equipment at each of small
factories.
[0010] Further, if the resin mold products are crushed altogether
by such means, however, many of the resin mold products formed of
different kinds of resins are crushed in a mixed state, and, as a
result, it is necessary to identify crushed pieces in which many
kinds of resins exist using an identification apparatus. Although
such identification is possible in principle, industrialization
thereof is difficult in practice because it is necessary to
respectively identify kinds of resins of a large number of crushed
pieces and classify the same into the respective materials after
the identification.
[0011] In addition, to economically realize the material recycling
of high-quality resinous materials, it is necessary to classify
kinds of resins containing various additives such as fire retardant
at a high accuracy and a high speed. As a method for classifying
the kinds of resins, a technique using, for example, a near
infrared ray absorption has been known and various devices are
marketed. However, this method hardly identifies kinds of resins
with many identification errors and is unsuitable for the high
accuracy and high speed identification. Another method utilizing
intermediate infrared absorption has been also known. Although this
method is capable of identifying not only kinds of resins but also
those of additives such as fire-retardant at a high accuracy, there
is a problem in that a long time is required for the identification
and therefore unsuitable for a high speed processing.
[0012] On the other hand, the recovered resinous products may be
coated with films, applied with labels or the like or carry various
contaminants, which are liable to enter the resin during the
treatment of the resinous products to result in a problem to
significantly deteriorate the characteristic of the resin to be
reused.
[0013] Although various trials have been attempted for removing
foreign matters carried on the surface of the resinous product, for
example, by a mechanical method and the separation or removal with
a solvent, there is a problem in either cases. For instance, if the
removal of the coated film or the label is intended by using a
crusher such as a ball mill, the resin is softened due to heat
generated by the friction during the crushing operation, which
disturbs the resin removal or causes the re-adhesion of the foreign
matters once removed. Also, there is another method wherein the
foreign matters are dissolved with a solvent and then separated and
removed from the resin. This method, however, has a serious
problems in that the used solvent must be regenerated or discarded,
and also has other problems in that an apparatus used therefor is
complicated in structure and unfavorable from the economical point
of view.
[0014] There is a still further method for removing the coated film
or labels, called as a dry blast treatment, wherein an abrasive
material such as sands or metallic particles is used for scraping
off the foreign matters from the surface of the resinous product.
According to this method, however, particles of the abrasive
material may stick into the surface of the resinous product and
remain as they are as new foreign matters. Also, the resin may be
softened by heat generated due to the friction of the abrasive
material and cause the re-adhesion of the foreign matters once
removed.
SUMMARY OF THE INVENTION
[0015] The present invention has been done to solve the
above-mentioned problems, and an object of the present invention is
to provide a resin recycling system for crushing resin mold
products collected from discarded apparatuses into crushed resinous
pieces to reduce an apparent volume thereof, without identifying
that the resin mold product belongs to what kind of resin but with
taking care that a plurality of kinds of resins are not mixed with
each other; identifying a kind of the crushed resinous pieces to
classify the same to that kind for easily determining a field in
which the same is reused; and removing foreign matters from the
surface of the classified crushed resinous piece to be reusable as
resinous material.
[0016] Another object of the present invention is to provide a
crushing system for roughly crushing polymer parts (including a
large-sized ones) taken out from the collected and disassembled
apparatuses to reduce an apparent volume thereof.
[0017] A further object of the present invention is to provide an
identification system for effectively identifying a kind of crushed
resinous pieces obtained by crushing resin mold products collected
from discarded electric or electronic equipment without identifying
that the resin mold product belongs to what kind of resin but with
taking care that a plurality of kinds of resins are not mixed with
each other.
[0018] Further, the present invention is to solve the
above-mentioned problems of the prior art by providing a cleaning
system for thermoplastic resin products wherein, when the resin
products are collected and cleaned to be reusable resinous
material, foreign matters such as coated films or labels adhered on
the surface of the resin products are sufficiently removed
therefrom so that the resinous material is usable in the same field
as before.
[0019] To achieve the above objects, according to one aspect of the
present invention, a resin recycling system is provided, which
comprises crushing means for individually crushing resin mold
products into crushed resinous pieces in which 70% or more of the
crushed resinous pieces have an equivalent diameter in a range from
1 to 50 mm, packing means for packing the crushed resinous pieces
of the respective mold product into a bag having a transparent
portion, classification means for irradiating a light beam to the
crushed resinous pieces in the bag through the transparent portion,
identifying a kind of the crushed resinous pieces based on a
reflected beam therefrom, and classifying the bags into respective
kinds of resins, and cleaning means for taking the crushed resinous
pieces out from the bag and cleaning the crushed resinous pieces of
the respective kind to remove foreign matters adhered on the
surface thereof.
[0020] In the above description, the term, "equivalent diameter" is
a diameter of a circle having the same area as that of a projected
area of an object.
[0021] Here, the equivalent diameter of the crushed resinous piece
is preferably in a range from 3 to 40 mm, more preferably from 5 to
30 mm. A ratio of the crushed resinous pieces having the equivalent
diameter within these ranges is preferably 80% or more, more
preferably 90% or more.
[0022] If the equivalent diameter of the crushed resinous piece is
smaller than 1 mm, there is an inconvenience in that foreign
matters could not be removed during cleaning by the cleaning means,
because the crushed resinous piece is pulverized. For example, when
the cleaning is carried out by the abrasion, the abrasion becomes
impossible. Also, the small resinous pieces are liable to stick to
the interior of the crusher or the bag due to static
electricity.
[0023] On the other hand, if the equivalent diameter of the crushed
resinous piece exceeds 50 mm, the crushed resinous pieces may be
still three-dimensional to obstruct the sufficient volume
reduction.
[0024] The crushing may be carried out at one step. However, if the
mold product is too large in size to be introduced into an ordinary
crusher, the crushing may be carried out at two steps wherein the
mold product is roughly crushed by a rough crusher and then
introduced into the ordinary crusher.
[0025] Since one resin mold product is formed of one kind of resin,
it is possible to effectively reduce the apparent volume of the
resin mold product while preventing the finely crushed resinous
pieces from mixing with other kinds by crushing the resin mold
product separately one kind by one kind and immediately packing
into a bag. By crushing the resin mold product one by one which is
recovered from the discarded apparatus in the manual disassembly
factory and packing the crushed resinous pieces in a bag, the
conveying efficiency is enhanced
[0026] Since the crushed resinous pieces in the bag is of the same
kind of resin, it is possible to carry out the economical
classification by classifying the bags.
[0027] In this regard, to further enhance the working efficiency,
when it is apparent in advance that the mold products are formed of
the same kind of resin, they are crushed together and packed in one
bag. For example, if there are plurality of mold members of the
same shape and function (such as paper feeding trays of different
sizes of a copying machine) and it is confirmed that they are
formed of the same kind of resin, they may be crushed together and
packed in one bag. This method is favorable for facilitating the
working efficiency when there are a number of small resinous
members of a similar shape and the same kind of resin in one
discarded apparatus.
[0028] The transparent portion of the bag is necessary for the
purpose of preventing the light beam irradiated to the crushed
resinous particles or reflected therefrom from being adversely
effected by the passage thereof through the bag. Accordingly, if
the adverse effect on the detection due to the passage of light
beam through the bag is negligible, the transparent portion is not
necessarily completely transparent. In short, it is sufficient that
the bag is provided with a light-passing area (transparent portion)
which does not adversely effect the detection, and in this text,
such a light-passing area is referred to as a transparent portion.
The transparent portion may extend throughout the bag. Such a bag
may be formed, for example, of polyethylene. In this regard, a
thickness of the transparent portion is generally 100 .mu.m or
less. Other materials may be used for this purpose, such as
resinous film, resinous net or metallic net.
[0029] A method for identifying a kind of resin includes, for
example, one based on a Raman spectrum analysis, wherein a Raman
spectrum obtained from the reflected light beam from the resin to
be inspected (i.e., the crushed resinous pieces in the bag) is
sequentially compared with Raman spectra obtained from reflected
light beams from various known resins prepared in advance to find
whether or not there is the coincidence between both the spectra.
The method based on the Raman spectrum analysis is favorable
because it is less adversely effected from color tone or surface
contamination of the crushed resinous piece. One method for
identifying kind of resin based on the Raman spectrum analysis is
disclosed, for example, in paragraphs from 0011 to 0018 of Japanese
Patent Application Laid-open No. 10-38807. Alternatively, an
infrared or near infrared spectrum analysis may be used for this
purpose.
[0030] One method for classifying the bags into kinds of resins
includes the steps of storing an identified kind of crushed
resinous pieces and an expected arrival time at which the bag of
the crushed resinous pieces would reach a predetermined
classification position on a conveying path, in correspondence to
each other, and recovering the bag reaching the classification
position at the expected arrival time from the conveying path.
[0031] The predetermined classification position may be different
in accordance with kinds of resins. In such a case, the classified
recovery is carried out wherein, for example, the bag in which
resin A is packed is recovered from the conveying path at the
classification position for the resin A, and the bag in which resin
B is packed is recovered from the conveying path at the
classification position for the resin B.
[0032] The predetermined position may be a specified one
irrespective of kinds of resins. In such a case, the classified
recovery is carried out in such a manner that the bag of resin A
(the resin A is packed) reaching the classification position is
guided from the conveying path to a collecting container or the
like for the resin A, and similarly, the bag of resin B reaching
the classification position is guided from the conveying path to a
collecting container or the like for the resin B.
[0033] The expected arrival time is obtained by an identification
time, a distance between an identification position and the
classification position, and a conveying speed. While the expected
arrival time may be calculated from these data every time, it may
be determined as a time a predetermined period after an
identification time, since the above distance and the conveying
speed are constant.
[0034] The cleaning means removes foreign matters such as plated
layers, coatings, labels or contaminants adhered to the surface of
the crushed resinous piece therefrom.
[0035] The cleaning means may be a device having a cleaning vessel
and an agitator member provided in the cleaning vessel wherein at
least part of the inner wall of the cleaning vessel and/or a
surface of the agitator member has an abrasive surface (roughened
surface) for removing (scraping or scrubbing off) the foreign
matters on the surface of the crushed resinous piece. Water or an
aqueous rinsing liquid may be supplied into the vessel to enhance
the removal of foreign matters.
[0036] The abrasive surface (roughened surface) may be of any
structure, provided it could sufficiently clean the surface of the
crushed resinous piece. The abrasive surface preferably has the
irregularity having a depth in a range from 40 to 2000 .mu.m. By
the contact of crushed resinous pieces with this roughened surface
having such irregularity, foreign matters such as coated film or
label adhered onto the surface of the crushed resinous piece are
sufficiently scrubbed or scraped off and removed. If the depth of
the irregularity is less than 40 .mu.m, the foreign matters are not
sufficiently removable. Contrarily, if exceeding 2000 .mu.m, the
surface of the crushed resinous piece is excessively scraped off to
lower the resin recovery percentage. The depth of the irregularity
is preferably in a range from 50 to 1000 .mu.m, more preferably
from 60 to 500 .mu.m. If the depth is within such a range, the
foreign matters are not excessively scraped off but sufficiently
removable.
[0037] In the device for continuously cleaning the crushed resinous
pieces, the crushed resinous pieces are continuously supplied from
one end of the cleaning vessel, conveyed in one direction within
the cleaning vessel, for example, by a screw or others and
continuously collected from the other end. If water or aqueous
liquid is used in such a device, the feeding of water or aqueous
liquid is carried out in a similar manner that the water or the
aqueous liquid is also continuously fed from the one end and/or
intermediate portions of the cleaning vessel, flows in the same
direction in the cleaning vessel and is continuously drained from
the other end.
[0038] When water or aqueous liquid is used during the cleaning
operation, it functions as a lubricant between the crushed resinous
pieces and the irregularity to prevent the surface of the crushed
resinous piece from being excessively scraped off as well as to
suppress the temperature rise of the crushed resinous piece due to
the cooling operation of water whereby the softening thereof is
inhibited. Also, the foreign matters such as coated film or label
once removed are quickly discharged out of the cleaning device and
do not adhere again to the crushed resinous pieces.
[0039] The resin recycling system may have a recovery means for
separating foreign matters from a mixture of the crushed resinous
pieces cleaned by the cleaning means and the foreign matters and
recover the crushed resinous pieces. The crushed resinous pieces
and the foreign matters may be separated from each other, for
example, by wind. Also, magnet force may be used for removing
metallic material. When water or aqueous liquid is used for the
cleaning operation, it is possible to remove foreign matters
together with water or the like. In this regard, it may be so
adapted that, after removing foreign matters from water or aqueous
liquid through a filter or others, the water or aqueous liquid is
reused.
[0040] The resin mold products which can be recycled after being
crushed, classified and cleaned according to the present invention
include, for example, those used as housings or parts of various
apparatuses used in an OA and home electric appliance field, an
electric and electronic field, a sanitary field, an automobile
field or a sundries field. For example, various resinous housings,
trays or internal resinous parts used in copying machines,
printers, personal computers, TV sets, various monitors or mobile
telephones.
[0041] The resinous material recycled according to the present
invention includes, for example, various styrene type resins such
as acrylonitrile-butadiene-styrene resin, polystyrene resin or
acrylonitrile-styrene resin; polycarbonate resin; olefin type resin
such as polyethylene or polypropylene; polyamide type resin such as
PA 6, PA66, PA46 or PA12; polyester type resin such as polybutylene
terephthalate, polyethylene terephthalate or polyacrylate;
polyphenylene ether resin; polyacetal; polyvinylchcloride resin;
polysulfon; PPS; polyether sulfon; ethylene-vinylacetate copolymer;
ethylene-ethylacrylate copolymer; EVOH; polyamide type elastomer;
polyester type elastomer; and alloys in which two or more of them
are mixed. These are all identifiable by the classification means
of the inventive system.
[0042] The classification means of the inventive system can
identify additives contained in the crushed resinous pieces, such
as various fire-retardants including halogen type and phosphor
type; various fire-retardant assistants such as antimony trioxide,
antimony tetroxide, antimony pentoxide, chlorinated polyethylene or
tetrafluoroethylene polymer; inorganic filler such as glass fiber,
carbon fiber, metallic fiber or talc; anti-fungus agent,
mildewcide, plasticizer, antistatic or silicone oil. These
additives are identifiable if a considerable amount of them is
contained in the crushed resinous piece (resin mold product), for
example, 1 part by weight or more, preferably 2 parts or more in
100 parts by weight of the resin mold product.
[0043] To achieve the above objects, one aspect of the crushing
system according to the present invention comprises an endless
conveyor for conveying polymer mold products, and an opposed member
having an opposed surface confronting at least one end of the
endless conveyor on the conveying-directional side and disposed so
that a distance between the opposed surface and a conveying surface
of the endless conveyor becomes smaller in the conveying direction,
wherein crushing edges or crushing pins are provided on at least
one of the conveying surface of the endless conveyor and the
opposed surface of the opposed member, to direct toward the other,
whereby the polymer mold products transported by the endless
conveyor are pushed into a gap between the conveyor and the opposed
member and crushed with the crushing edges or pins.
[0044] The crushing edge or pin is a member having a function for
crushing the polymer mold product conveyed by the endless conveyor
and pushed into a gap between the same and the opposed member. That
is, even though shapes thereof are different from those generally
thought from the feeling of words "edge or pin", any member may be
the crushing edge or pin according to the present invention, if it
is provided on at least one of the conveying surface of the endless
conveyor and the opposed surface of the opposed member to direct
toward the other, and has the above-mentioned crushing function.
The crushing edge or pin preferably has a sharp portion to be in
contact with the polymer mold product because a larger crushing
performance is exhibited thereby.
[0045] Preferably, the crushing edges or pins are provided on the
conveying surface of the endless belt, and recesses or holes are
provided on the opposed surface of the opposed member for allowing
tip ends of the crushing edges or pins provided on the endless
conveyor to pass through the same.
[0046] The opposed member may be a second endless conveyor.
[0047] To achieve the above-mentioned objects, one aspect of the
identification system of the present invention is an identification
device for irradiating a light beam to a polymer products conveyed
by conveyor means, detect the reflected beam or the dispersed beam
from the polymer product by a sensor element, and identify a kind
of the polymer product based on the detected result, wherein the
sensor element is disposed at a predetermined position in the
vicinity of a conveying path of the polymer product, and a distance
determination mechanism is disposed in the conveying means or in
the vicinity thereof, for opposing the polymer product passing by
the sensor element to the sensor element at a distance between the
both.
[0048] Selectable polymers include, for example, rubber-like
polymer, thermoplastic elastomer and resin. Of them, resin is more
preferable. Additives in the resinous material and the selectable
polymeric material are the same as described above.
[0049] The conveyor means may be an endless conveyor and the sensor
element may be disposed at a predetermined position beneath the
conveying path constituted by the endless conveyor, and the
distance determination mechanism may be a light window provided at
each of portions of the endless conveyor passing over the
predetermined position.
[0050] According to this arrangement, the light beam is irradiated
from beneath to the polymer conveyed on the endless conveyor
through the light window, and the reflected or disperse light beam
is received by the sensor element through the light window. The
light window may be a mere slit but not be limited thereto. It may
be formed of any light-permeable material unless it disturbs the
detection of Raman disperse rays.
[0051] Alternatively, the conveyor means may be an endless conveyor
and the sensor element may be disposed at a predetermined position
on a side of the conveying path constituted by the endless
conveyor, and the distance determination mechanism comprises a
stopper member having a light window and disposed in front of the
sensor element in the vicinity thereof and a guide for guiding the
polymer product carried on the endless conveyor so that the polymer
product is pushed against the light window of the stopper member to
be able to pass by a front of the sensor element.
[0052] The stopper member has a function for limiting the
displacement (deviating from the conveying direction) of the
polymer pushed toward the stopper member by the guide while being
conveyed on the endless conveyor at the position of the stopper
member. The stopper member is provided with the light window,
behind which is located the sensor element.
[0053] According to this arrangement, the polymer conveyed on the
endless conveyor is guided by the guide to be brought into contact
with the light window of the stopper member and irradiated with a
light beam through the light window. The reflected or dispersed
beam thereof is received by the sensor element through the light
window. The light window may be a mere slit or be formed of any
light-permeable material such as transparent glass plate not
disturbing the detection of Raman disperse rays.
[0054] To achieve the above objects, one aspect of a method for
cleaning thermoplastic resinous products comprises the steps of
crushing the collected thermoplastic resinous products into crushed
pieces, supplying the crushed pieces together with water into a
cleaning device having a vessel and a rotary body disposed in a
rotatable manner within the vessel, wherein at least part of the
inner surface of the vessel and/or a surface of the rotary body to
be in contact with the crushed resinous pieces is roughened, and
rotating the rotary body to clean the crushed pieces.
[0055] According to this cleaning method, at least part of the
inner surface of the vessel and/or a surface of the rotary body is
roughened. The roughening may be carried out in any manners,
provided the resin product could be sufficiently cleaned.
Preferably, the surface irregularity has a depth in a range from 40
to 2000 .mu.m. When the roughened surface is brought into contact
with the crushed resinous pieces, foreign matters such as coated
film or label adhered on the surface of the crushed resinous piece
are sufficiently scrubbed or scraped off and removed. If the depth
of the irregularity is less than 40 .mu.m, the foreign matters are
not sufficiently removable, while if exceeding 2000 .mu.m, the
surface of the crushed resinous piece is excessively scraped off
together with resin to lower the recovery percentage of resin. The
depth of the irregularity is preferably in a range from 50 to 1000
.mu.m, more preferably from 60 to 500 .mu.m. If the depth is within
this range, the foreign matters are sufficiently removed without
excessively scraping resin off from the crushed piece.
[0056] The roughened surface in the interior of the vessel is
preferably 1% or more, preferably 5% or more, more preferably 10%
or more of a total area of the inner surface of the vessel and the
surface of the rotary body to be in contact with the crushed
resinous pieces. Degrees of the surface-roughening by the
irregularity may be approximately equal or unequal both in the
inner surface of the vessel and in the surface of the rotary body.
The degree of the irregularity may be equal or unequal throughout
the roughened inner surface of the vessel and/or the roughened
surface of the rotary body.
[0057] According to this cleaning method, water is continuously
supplied during the cleaning operation and acts as a lubricant
between the surface of the crushed resinous piece and the roughened
surface having the irregularity to prevent the surface of the
crushed resinous piece from excessively being scraped off. Also, by
the cooling action of water, the temperature rise in the crushed
resinous piece can be prevented. Foreign matters such as coated
film or label which have been once removed are quickly discharged
out of the cleaning device not to adhere again to the crushed
resinous pieces. Further, water is preferably continuously supplied
and drained so that a water level in the cleaning device is
maintained constant, while taking care to maintain a ratio in
weight of the crushed pieces to the water constant, because the
respective crushed resinous pieces continuously supplied can be
evenly cleaned.
[0058] The cleaning is preferably carried out so that the ratio in
weight of the crushed pieces to the water in the cleaning device is
controlled to be 1:0.3 to 2 and water is continuously supplied and
drained to maintain the interior temperature of the cleaning device
at 70.degree. C. or lower. If the ratio of water is less than 0.3,
the interior of the cleaning device is not sufficiently cooled,
whereby the temperature rises above 70.degree. C. to soften and
melt the crushed resinous pieces, which may disturb the cleaning
operation. On the other hand, if the ratio of water exceeds 2,
chances of contact of the crushed resinous pieces with the inner
surface of the vessel and the surface of the rotary body,
particularly those roughened to have the irregularity, becomes
fewer. Even if the contact occurs, the crushed resinous piece does
not be sufficiently pressed onto the surface, whereby the foreign
matters such as coated film or label may not be completely and
effectively removed.
[0059] Further, the rotary body has a screw blade for conveying the
crushed resinous pieces and cleaning plates or pins for cleaning
the crushed resinous pieces around a rotary shaft, and preferably
rotates so that a linear speed of a tip end of the cleaning plate
or pin is in a range from 0.5 to 20 m/sec. If the linear speed is
0.5 m/sec or less, the cleaning becomes insufficient, while if
exceeding 20 m/sec, the interior temperature of the device rises,
whereby it is difficult to maintain the temperature at 70.degree.
C. or lower.
[0060] According to the above-mentioned method, it is possible to
clean the crushed pieces of all thermoplastic resin products molded
to have predetermined shapes by various molding methods such as
compression molding, ejection molding or blow molding. These resin
mold products may be molded either using a mold or using no mold
but a mold die or others. Examples of the resin mold product
include not only housings of home electric appliances such as TV
sets or electric refrigerators or housings of OA equipment such as
personal computers or printers but also parts of these apparatuses
and/or broken ones thereof.
[0061] Although there is no limitation in kinds and shapes of the
resin products, preferably, products of different kinds of resins
are not mixed together. This is because, if different kinds of
resins are mixed together, in general, characteristics inherent to
the respective resin are largely deteriorated. Therefore, the resin
products are preferably classified to the respective kinds and
separately cleaned in advance. Also, the resin products may
preferably be classified to have the same or similar color tones,
such that products which color tones are largely different, for
example, one being pale and light gray and the other being deep and
dark gray, are not mixed together. If the products having largely
different color tones are not mixed together, color tone of resin
to be reused is easily adjustable.
[0062] Also, there is no limitation in size of the resin products,
provided they can be crushed to pieces of a suitable size.
[0063] The resin products may be coated or plated. The coated film
may be of any material usually used for coating resin. The plated
layer may be of any metal usually used for plating resin.
[0064] The resin product is cleaned after being crushed into
resinous pieces through a crushing operation in advance. The
crushing operation may be carried out by a crusher usually used for
crushing resin and capable of crushing the resin product into
pieces of a size suitable for the cleaning, such as a hammer mill
or a cutter mill. The crushing operation is preferably carried out
under the forced cooling such as air cooling so that the resin
product does not melt due to the heat generation.
[0065] The maximum length of the crushed resinous piece is
preferably in a range from 1 to 30 mm, more preferably from 2 to 20
mm, most preferably from 3 to 10 mm. If the maximum length is less
than 1 mm, micro-particles increases to dissipate the crushed
resinous pieces in a pre-treatment process. On the other hand, if
exceeding 30 mm, the cleaning becomes insufficient all over the
surface of the crushed piece. There is no limitation in shape of
the crushed resinous piece provided no problem occurs in the
handling thereof. However, an excessively elongated one is
unfavorable, and one having generally equal dimensions in all
directions in a plan view is preferable, such as circular or
square. Crushed resinous pieces of such a shape can be effectively
cleaned even if an amount thereof is large. In this regard, if
necessary, small crushed resinous pieces having the maximum length
of approximately lm or less, metallic powder or dust may be removed
after crushing by a vibratory screen or others.
[0066] To achieve the above objects, in the cleaning system
according to the present invention, a device is provided for
cleaning thermoplastic resinous products comprising a vessel and a
rotary body built-in in the vessel, wherein the vessel has an
entrance port for the thermoplastic resinous products provided in
an upper area of one end thereof, an exit port for the
thermoplastic resinous products provided in a lower area of the
other end thereof, a water supply port and a drainage port; the
drainage port being connected to a drainage line for adjusting a
water level; the rotary body having a rotary shaft, a screw blade
provided on the circumference of the rotary shaft and at least one
of a plurality of cleaning plates and cleaning pins; and at least
part of the inner surface of the vessel and/or surfaces of at least
one of the cleaning plates and the cleaning pins being
roughened.
[0067] Also, to achieve the above objects, in the cleaning system
according to the present invention, a device is provided as another
aspect for cleaning thermoplastic resinous products comprising a
vessel and agitating blades, wherein the vessel has an entrance
port for crushed resinous pieces and a water supply port, both
provided in an upper portion thereof, and an exit port for the
crushed resinous pieces and a drainage port, both provided in a
lower portion provided thereof; a drainage line for adjusting a
water level being connected to the drainage port, and at least part
of the inner surface of the vessel and/or surfaces of the agitating
blades being roughened.
[0068] According to the above-mentioned cleaning device, at least
part of surfaces to be in contact with the crushed resinous pieces
is roughened to effectively scrub or scrape off a surface portion
of the crushed resinous piece and sufficiently remove foreign
matters such as coated film, plated layer applied to the surface,
label or seal adhered to the surface or contaminants. At least part
of the inner surface of the vessel and/or a surface of at least one
of the screw blade, the cleaning plate and the cleaning pin may be
roughened. Preferably, the inner surface of the vessel and a
surface of at least one of the screw blade, the cleaning plate and
the cleaning pin are roughened. Regarding the screw blade, the
cleaning plate and the cleaning pin, a surface of at least one of
the screw blade and/or the cleaning plate is more preferably
roughened. Also, the inner surface of the vessel and at least part
of a surface of the agitator blade is preferably roughened.
[0069] If necessary, the cleaning device may be combined with a
water rinsing device, a dehydrator, a dryer, a vibratory screen, a
wind type classifier and/or a metal sensor to assuredly remove
foreign matters such as coated film, label or contaminants and
obtain pure crushed resinous pieces. Such crushed resinous pieces
may be used in any field requiring the same with no problems.
[0070] The above and other objects, effects, features and
advantages of the present invention will become more apparent from
the following description of embodiments thereof taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0071] FIG. 1 is a block diagram for schematically illustrating a
resin recycling system according to the present invention;
[0072] FIG. 2 is a schematic view of one embodiment of crushing
means and classifying means used in the present invention;
[0073] FIG. 3 is a schematic side view of one example of a crusher
used in the present invention;
[0074] FIG. 4 is an enlarged view of part of FIG. 3;
[0075] FIG. 5A is a front view of an opposite wall; FIG. 5B is a
sectional view taken along a line 5B-5B in FIG. 5A; FIG. 5C is a
plan view of a connecting plate of a chain conveyor; and 5D is a
sectional view taken along a line 5D-5D in FIG. 5C;
[0076] FIG. 6A is a schematic side view of another example of a
crusher; and FIG. 6B is a schematic side view of a still further
example thereof.
[0077] FIG. 7 is a block diagram illustrating the relationship
between inputs and outputs of a controller for the system shown in
FIG. 2;
[0078] FIG. 8 is a flow chart illustrating one example of a
procedure for controlling the identification and
classification/recovery of resins;
[0079] FIGS. 9A and 9B are a side view and a top view,
respectively, of one example of a polymer conveying mechanism
provided with an identification device;
[0080] FIG. 10 is a sectional view taken along a line 10-10 in FIG.
9A;
[0081] FIGS. 11A and 11B are a side view and a top view of another
example of a polymer conveying mechanism provided with an
identification device;
[0082] FIG. 12 is a cross-sectional view of one example of a
horizontal type continuous cleaning apparatus according to the
present invention;
[0083] FIG. 13 is an elevational sectional view of one example of a
horizontal type continuous cleaning apparatus according to the
present invention;
[0084] FIG. 14 is a sectional view illustrating a drainage line for
adjusting a water level of a cleaning apparatus;
[0085] FIG. 15 is a cross-sectional view illustrating one example
of a vertical and batch type cleaning apparatus according to the
present invention;
[0086] FIG. 16 is a block diagram illustrating one embodiment of
recovery means according to the present invention;
[0087] FIG. 17 is a table showing results obtained by the operation
of a crusher;
[0088] FIG. 18 is a table showing results obtained by the operation
of a identification device; and
[0089] FIG. 19 is a table showing results obtained by the operation
of various cleaning apparatuses.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0090] FIG. 1 illustrates one embodiment of a resin recycling
system according to the present invention.
[0091] The illustrated system includes a crushing system 200, a
classification system 400, a cleaning system 600 and a recovery
system 800. The crushing system 200 operates to crush resinous mold
products one by one into pieces so that 70% or more of the pieces
have an equivalent diameter in a range from 1 to 50 mm, and to pack
the pieces of every one mold product to one transparent bag. The
classification system 400 operates to irradiate light beams to the
crushed resinous pieces in the bag, determine a kind of the crushed
resin in accordance with the reflected beams therefrom and classify
the respective bags into the kinds of resins. The cleaning system
600 operates to clean the crushed resinous pieces taken out from
the respective bags classified by the classification system 400 to
remove foreign matters on the surface of the crushed resinous
pieces. A mechanism for taking out the crushed resinous pieces from
the bag and sending the same to a rinsing mechanism may be
provided. The recovery system 800 operates to separate the foreign
matters from a mixture thereof with the cleaned resinous pieces to
recover the crushed resinous pieces.
[0092] [1] Crushing System 200 and Classification System 400
Initially, the Crushing System 200 and the Classification System
400 will be Described with Reference to FIG. 2.
[0093] The crushing system 200 has a resin crusher 21. The resinous
pieces crushed by the resin crusher 21 are packed in a transparent
bag 25 attached at a lower position of the crusher.
[0094] As described later, the classification system 400 has a
conveyor device 49 for the bags 25, a resin identification device
(resin determination device) 41 and classified recovery devices 47a
to 47c.
[0095] The resin crusher 21 is a device for crushing the resin mold
product into pieces so that 70% or more of the pieces have an
equivalent diameter in a range from 1 to 50 mm. The resin mold
products are crushed into pieces one by one and packed in the bag
25 attached to a lower position of the resin crusher 21. While the
resin crusher 21 illustrated in the drawing is of a type carrying
out the crushing operation in one step, the operation may be
carried out in two steps if the molded product is too large to be
introduced into the ordinary size crusher. For example, a crusher
for carrying out the coarse crushing and one for crushing the
coarsely crushed pieces into smaller pieces having an equivalent
diameter in a range from 1 to 50 mm may be provided.
[0096] The bag 25 is made of transparent polyethylene and has a
size of 23 cm long, 17 cm wide and 40 .mu.m thick. The bag 25 may
be opaque and made of other material than polyethylene unless the
identification of the crushed resin is disturbed thereby in a resin
identification device 41 described later. Also, the bag may be a
non-film type.
[0097] Here, the preferred embodiment of the crusher will be
described. FIG. 3 is a schematic side view of one example of a
crusher used in the present invention; FIG. 4 is an enlarged view
of part of FIG. 3; FIG. 5A is a front view of an opposite wall;
FIG. 5B is a sectional view taken along a line 5B-5B in FIG. 5A;
FIG. 5C is a plan view of a connecting plate of a chain conveyor;
and FIG. 5D is a sectional view taken along a line 5D-5D in FIG.
5C. FIG. 6A is a schematic side view of another example of a
crusher; and FIG. 6B is a schematic side view of a still further
example thereof.
[0098] The crusher illustrated has a chain conveyor (endless
conveyor) 220 and an opposite wall (opposite member) 250. The chain
conveyor 220 transports articles carried on connecting plates 221
attached to a chain 225 driven by sprockets 227, 227, by displacing
the connecting plates 221. This chain conveyor 220 is disposed to
have a downward inclination toward the conveying direction
indicated by arrow in the drawing to transport the polymer mold
products introduced into the crusher from a material introduction
port 232 provided at an upper position of the crusher, while
carrying the mold products on the connecting plates 221. As shown
in FIG. 5C, a plurality of crushing edges 222 (in the drawing, two
rows of eighteen edges) are provided on the respective connecting
plate 221 of the chain conveyor 220 with sharp ends thereof
projecting out of the conveyor. In this regard, instead of the
crushing edges 222, crushing pins may be provided.
[0099] The opposite wall 250 extends in the vertical direction and
has an opposite surface 255 opposed to an end portion of the chain
conveyor 220 as seen in the conveying direction (a left end portion
in FIG. 3). In the vicinity of a point at which this opposite
surface 255 is closest to the chain conveyor 220 (in the vicinity
of the lower end in the drawing), a plurality of crushing edges 252
are provided while directing toward the chain conveyor 220. In this
regard, instead of the crushing edges 252, crushing pins may be
provided. As shown in FIG. 5, the crushing edges 252 on the
opposite wall 250 and the crushing edges 222 on the chain conveyor
220 are provided to have different phases from each other not to
collide with each other even though both the crushing edges most
closely approach. In the opposite wall 250, slits 256 are provided
so that tip ends of the crushing edges 222 on the chain conveyor
220 can enter the same not to collide with the opposite wall 250
when the crushing edges 222 most closely approach the opposite wall
250. FIG. 4 illustrates a manner in which the crushing edges 222 of
the chain conveyor 220 most closely approach the opposite wall 250
and the tip ends of crushing edges 222 enter the slits 256.
[0100] In the crusher thus structured, the polymer mold products
introduced from the material introduction port 232 into the crusher
and conveyed by the chain conveyor 220 are sheared by the crushing
edges 222 and 252 and roughly crushed while being compressed into a
zone in which the chain conveyor 220 and the opposite wall 250 are
close to each other.
[0101] FIG. 6A illustrates a variation of FIG. 3. The crusher shown
in FIG. 6A is provided with a guide 259 at a lower end of the
opposite wall 250. This guide 259 operates, when the mold product
conveyed by the chain conveyor 220 is of a flat-shape and oriented
in the vertical direction, to prevent the mold product from
escaping from the compression caused by the chain conveyor 220 and
the opposite wall 250 and the shearing action of the crushing edges
222, 252 and falling down while not being crushed.
[0102] In this regard, while the crushing edges are provided both
in the chain conveyor 220 and the opposite wall 250 in the
embodiments shown in FIGS. 3 and 6A, they may be provided in at
least one of the both. However, if they are provided in both of
them, the shearing action of the crushing edges is more
enhanced.
[0103] In a crusher shown in FIG. 6B, two chain conveyors 220 and
250a are provided so that a distance between the both becomes
gradually smaller in the conveying direction. According to this
crusher, the upper inclined chain conveyor 250a has a function as
the opposite member. The crushing edges 222 and 252a of the
respective conveyors 220 and 250 are provided to have different
phases from each other not to collide with each other even though
both the crushing edges most closely approach
[0104] While two chain conveyors 220, 250a have crushing edges 222,
252a, respectively, in the embodiment shown in FIG. 6B, these may
be provided on at least one of the conveyors. If the crushing edges
are provided on both the conveyors, the shearing operation of the
crushing edges can be more assuredly carried out. In the
arrangement shown in FIG. 6B, the upper chain conveyor 250a may be
replaced with a slanted opposite wall having the same inclination
as the conveyor 250a. Alternatively, rollers may be provided. That
is, it is sufficient that there is an arrangement for transporting
the polymer mold products by the conveyor means and pushing the
same into a gap between the conveyor means and the opposite member
so that the mold products are roughly crushed while being
compressed by the crushing edges or pins.
[0105] In this regard, a continuous system may be arranged from the
arrangement shown in FIG. 3 or 6 by providing a fine crusher (for
more finely crushing the coarsely crushed pieces) subsequent
thereto.
[0106] Now return to FIG. 2 wherein the conveyor device 49
transports the bags in which the crushed resinous pieces are packed
at a predetermined speed V and stops the same if necessary. If it
is expected that a more time is required for the identification of
resin, for example, because of a slow calculating speed of the
resin identification device 41 (described later), the stop of the
conveyor device will be necessary. The conveyor device 49 may
include a conveyor with trays and if an expected arrival time has
been reached, the corresponding tray is inclined to throw down the
bag carried thereon into a recovery box beneath the same. The
expected arrival time is a time instant obtained by adding a time
period necessary for a certain bag in which a resin of kind A are
packed to be conveyed to a recovery box for the resin A to a time
instant at which the resin in the bag has been identified as A. The
corresponding tray is a tray on which the certain bag is placed. In
this regard, while the crusher 21 and the conveyor device 49 (and
the resin identification device 41 or others) are provided in the
same factory in FIG. 2, the both may be provided in different
factories, respectively, such that the resinous pieces crushed by
the crusher 21 and stuffed in the bag 25 are transported to the
factory in which the conveyor device 49 or others is provided. In
other words, even in such an arrangement, it is possible to
suppress the transportation cost to a lower level because the resin
is reduced in volume.
[0107] The resin identification device 41 is a device for
identifying a kind of the crushed resinous pieces in the bag 25
based on a Raman spectrum analysis. That is, a laser beam is
irradiated to the crushed resinous pieces in the bag 25 which
passes a detection position (identification position) (or is made
to stop for a while if a time period is required for the
identification), and reflected therefrom. A Raman spectrum is
obtained from the reflected beam and sequentially compared with
Raman spectra of known resins to find the coincidence of Raman
spectra of both the resins to decide a kind of resin in the bag.
For this purpose, the resin identification device 41 stores Raman
spectra of various resins obtained in advance.
[0108] The classified recovery device 47a is for a resin A.
Similarly, the classified recovery device 47b is for a resin B, and
the classified recovery device 47c is for a resin C. If there are
four kinds of resins or more, the number of classified recovery
devices may be correspondingly increased. A distance between the
classification/recovery position of the classified recovery device
47a and the detection position of the resin identification device
41 is a; a distance between the classification/recovery position of
the classified recovery device 47b and the detection position of
the resin identification device 41 is b; and a distance between the
classification/recovery position of the classified recovery device
47c and the detection position of the resin identification device
41 is c. When a current time reaches the expected arrival time, the
classified recovery device corresponding to the kind of resin in
correspondence to that expected arrival time is operated to recover
the bag located at the classification/recovery position of that
classified recovery device into the recovery box.
[0109] The classified recovery device is not limited to the
illustrated one in which a tiltable tray of the conveyor is
inclined to throw down the bag into the recovery box disposed
beneath the conveyor. For example, a manipulator may be provided
above the conveyor and lift the bag on the conveyor to recover the
same. Alternatively, a pusher may be provided for pushing the bag
on the conveyor aside by a rod or the like. Or, the classified
recovery devices may not be individually provided in correspondence
to kinds of resins, but all the bags may be recovered by a single
recovery device, from which the bags are distributed into the
respective recovery boxes in correspondence to the kinds of
resins.
[0110] FIG. 7 is a block diagram illustrating the relationship
between inputs and outputs of a controller for the system, and FIG.
8 is a flow chart illustrating a procedure for controlling the
identification and classification/recovery of resins. The
description will be made below with reference to FIGS. 7 and 8.
[0111] First, the conveyor device 49 starts (S01).
[0112] When the identification result (a kind of resin in the bag
25 passing through the identification position or stopping in a
period necessary for the identification at the identification
position) is input from the resin identification device 41 (i.e.,
the answer is YES at S11), the expected arrival time at which the
bag (packing the identified resin) reaches the classified recovery
device (for example, the device 47a) is calculated based on a
current time obtained from a clock IC 43, a distance to the
classified recovery device determined in accordance with a kind of
the identified resin (if the identified resin is a kind A, this
distance is a to the classified recovery device 47a) and a
conveying speed V of the conveyor device 49, and stored in a memory
(not shown) within a controller 45 in correspondence to the resin
kind A (i.e., to the classified recovery device 47s) (S13). In this
regard, since the conveying speed V and the distance (a/b/c) are
known, a time period necessary for the transportation determined in
accordance with kinds of resins may be added to the current time,
instead of carrying out the above calculation.
[0113] If the current time reaches either one of the expected
arrival times stored in the memory (not shown) of the controller 45
(i.e., if the answer is YES at S21), an operation command is issued
from the controller 45 to the classified recovery device stored in
correspondence to this expected arrival time. Thereby, the
above-mentioned classified recovery device is operated to recover
the bag located at the classification/recovery position of the
classified recovery device (S23). Thereafter, the expected arrival
time and data of the classified recovery device stored in
correspondence thereto are deleted from the memory (S25).
[0114] Other preferred embodiments of the resin identification
device will be described in more detail below with reference to
FIGS. 9 to 11.
[0115] (1) First Embodiment
[0116] FIGS. 9A, 9B and 10 schematically illustrate a first
embodiment of a polymer conveying mechanism provided with an
identification device, wherein FIG. 9A is a side view, FIG. 9B is a
top view and FIG. 10 is a sectional view taken along a line 10-10
in FIG. 9A. In the drawings, reference numeral 410 denotes a
polyethylene bag (having a size of 23 cm long, 17 cm wide and 40
.mu.m thick) in which resin pieces crushed to have a suitable size
(for example, so that 70% or more of the pieces have an equivalent
diameter in a range from 1 to 50 mm) are packed, wherein the
equivalent diameter is a diameter of a circle having the same area
as a projected area of an object.
[0117] The bag 410 is conveyed on a conveyor belt 440 driven by
drive rollers 441, 441 in the arrowed direction, and irradiated
with a laser beam from a sensor element 421 in the midway of its
travel, whereby a Raman scattering can be detected. The detected
signal is fed to an identification and calculation device 420 in
which a kind of resin is identified. That is, the detected Raman
spectrum is sequentially compared with those of various known
resins stored in advance until the known resin coinciding with the
resin to be identified is found. Based on the identification
result, a timing for a dispensing operation is calculated and a
dispensing device 430 is operated at the calculated timing.
Thereby, the bag 410 is removed from the conveyor belt 440 and put
into a vessel in correspondence to a kind of the identified resin
(either one of vessels 435a, 435b and 435c). The dispensing timing
is a timing at which the bag 410 of which the Raman scattering has
been detected at a position of the sensor element 421 to identify
the kind of resin reaches the vessel (either one of vessels 435a,
435b and 435c) corresponding to the kind of resin packed in the
bag.
[0118] According to the first embodiment, as illustrated, a
plurality of slits 400S of a predetermined length used as a light
window for allowing a light beam to pass through the same (having a
size of 10 mm wide and 20 cm long) are arranged along a center
portion of the width of the conveyor belt 440 at a predetermined
pitch in the belt-running direction. The above-mentioned sensor
element 421 is disposed at a position in correspondence to the slit
position beneath the conveyor belt 440 in the vicinity of the inner
surface of the conveyor belt 440. Thus, it is possible to maintain
a distance between the light-receiving part of the sensor element
421 and the bottom surface of the bag 410 always at a predetermined
short distance (for example, approximately 10 mm) capable of
detecting the Raman scattering, irrespective of shapes of the bags
410. Thereby, the high-precision resin identification can be
carried out.
[0119] In this regard, a member for pressing the bag 410 onto the
upper surface of the conveyor belt 440 may be provided at a
position above the sensor element 421 to prevent the bottom surface
of the bag 410 from floating upward from the upper surface of the
conveyor belt 440, so that the above-mentioned distance between the
light-receiving part of the sensor element 421 and the bottom
surface of the bag 410 is maintained constant.
[0120] (2) Second Embodiment
[0121] FIG. 11 schematically illustrates a second embodiment of a
polymer conveying mechanism wherein FIG. 11A is a side view and
FIG. 11B is a top view. In the drawings, the same reference
numerals are used for denoting the same or similar parts as those
in FIG. 9, and the explanation thereof will be eliminated.
[0122] According to the second embodiment, as illustrated, a window
plate 422 having a light window for allowing a light beam to pass
through the same is disposed at a position on the lateral side of a
conveyor belt 440a, and is also used as a stopper member. A sensor
element 421 is provided at a position on a side of the window plate
422 opposite to the conveyor belt 440a so that the light receiving
part of the sensor element 421 confronts the window plate 422. At a
position opposite to the window plate 422, a plate-like curved
guide 423 is provided directly above the conveyor belt 440a, while
interposing the conveyor belt between the window plate and the
curved guide. This guide 423 operates to push the bag 410
transported on the conveyor belt 440a toward the window plate 422
and cause the bag 410 to be in contact with the window plate 422.
According to this structure, it is possible to maintain a distance
between the light-receiving part of the sensor element 421 and the
lateral surface of the bag 410 at a thickness of the window plate
422 (for example, approximately 10 mm), irrespective of shapes of
the bags 410. In other words, it is possible to maintain the
distance at a value as small as capable of detecting the Raman
scattering. Thereby, the high-precision resin identification can be
carried out.
[0123] Instead of the guide 423 formed of a curved plate as in the
illustrated embodiment, one or two rollers or more may be used for
the same purpose. In such a case, the roller may be either a freely
rotatable type or one driven to rotate in synchronism with the
conveyor belt 440a.
[0124] While an endless belt is used as a conveyor means in the
above-mentioned embodiment, the conveyor means according to the
present invention should not be limited to the endless belt,
provided it is capable of transporting the polymer to be detected
while maintaining a predetermined short distance between the
light-receiving part of the sensor element 421 and the polymer. For
example, the conveyor means may be of a type for transporting the
bag 410 carried on a tray.
[0125] [2] Rinsing System 600
[0126] Next, the cleaning system 600 will be described.
[0127] FIGS. 12 to 14 illustrate a structure of the continuous
cleaning device 600, wherein FIG. 12 is a schematic cross-sectional
view, FIG. 13 is a schematic side sectional view and FIG. 14 is a
detailed illustration of a drainage line 669 for adjusting a water
level.
[0128] The continuous cleaning device 600 has a vessel 660 and
rotary bodies 662. In FIGS. 12 and 13, the vessel 660 may be formed
of a metal such as stainless steel. An entrance port 663 for
crushed resinous pieces is provided at one end of an upper wall of
the vessel 660, and an exit port 668 for the crushed resinous
pieces is provided in a lateral wall on the opposite end side. A
water feeding port 664 is provided at at least one position of the
upper wall of the vessel 660, and a drainage port 666 is provided
at at least one position of the lower wall of the vessel 660. A
drainage line 669 for adjusting a water level is connected to the
drainage port 666.
[0129] A predetermined amount of crushed resinous pieces is
continuously introduced into the vessel 660 through the entrance
port 663, conveyed along the same and discharged from the exit port
668. In this process, preferably, the introduction speed and the
discharge speed of the crushed resinous pieces are approximately
equal to each other and maintained roughly constant. A feeding
speed of water to be supplied from the water feeding port 664 is
preferably controlled so that a water level determined by the water
level adjusting pipe 669b is maintained, while taking a draining
speed of water from an open end of the water level adjustment
drainage line 669 into account. By adjusting the introduction and
discharge speeds of the crushed resinous pieces and those of water,
constant amounts of crushed resinous pieces and water are always
conveyed through the vessel 660. Accordingly, the crushed resinous
pieces are evenly cleaned and, as a result, the surfaces of the
crushed resinous pieces are free from the foreign matters left
thereon, and prevented from being excessively scraped off.
[0130] In the drainage port 666 provided in the bottom wall or
others of the vessel 660, slits or punched plate are disposed.
Also, in the drainage port 666, the water level adjustment drainage
line 669 is connected. The water level adjustment drainage line 669
has a drainage pipe 669a connected to the drainage port 666 and
standing upward on the lateral side of the vessel 660 and a water
level adjustment pipe 669b fitted to the interior of the drainage
pipe 669a in a slidable manner. Between the inner surface of the
drainage pipe 669a and the outer surface of the water level
adjustment pipe 669b, an O-ring 669c is interposed to keep the
water-tight sealing. By moving the water level adjustment pipe 669b
upward and downward, it is possible to adjust the water level in
the cleaning device 600 and maintain a predetermined water
level.
[0131] While the water feeding port 664 and the drainage port 666
are provided at one position, respectively, in the illustrated
embodiment, they may be provided at a plurality of positions,
respectively. When the water feeding ports 664 are provided at a
plurality of positions from one end to the other end of the vessel
660, it is possible to quickly guide dust or others generated by
the cleaning operation to the drainage ports 666 and drain the same
outside through the water level adjustment line 669. Further, it is
also possible to prevent the dust or others from sticking again to
the crushed resinous pieces.
[0132] Openings provided in the drainage port 666 such as slits or
holes of a punched plate have a size to allow water or dust to pass
through the same but prevent the crushed resinous pieces from
passing. The slit is preferably of a size in a range from
approximately 0.3 to 2 mm in view of the mechanical strength. While
the drainage port 666 may be provided in either of the bottom wall
or the lateral wall, the bottom wall is preferable in view of the
adjustment of the water level. In this regard, if the drainage port
is provided in the lateral wall, the position thereof is preferably
as low as possible, of course.
[0133] An open end of the water level adjustment pipe 669b opens to
the atmosphere so that the water level in the vessel 660 is
generally equal to a height of the open end of the water level
adjustment pipe 669b. Thereby, even if the feed rate of water
varies, the water level is maintained constant and excessive water
is drained from the open end of the water level adjustment pipe
669b. The drained water may be accumulated in a tank and reused
after being pumped up and filtrated through a filter to remove dust
or others therefrom.
[0134] The rotary shaft 662 is provided with screw blades 662c for
cleaning the crushed resinous pieces while conveying the same from
the entrance port 663 to the exit port 668, and cleaning plates
662a and cleaning pins 662b for scrubbing or scraping off foreign
matters from the surface of the crushed resinous pieces while
imparting shock thereto, all of which are alternately arranged.
Either one of the cleaning plate 662a or the cleaning pin 662b may
be eliminated, although the combined use thereof is preferable.
[0135] A diameter of the screw blade 662c, a thickness of the
cleaning plate 662a and a length of the cleaning pin 662b are not
limited, provided the efficient cleaning is achievable. The screw
blades 662c may have a generally equal diameter; the cleaning
plates 662a may have generally equal diameter and thickness; and
the cleaning pins 662b may have a generally equal length. Also, the
number of screw blades 662c for cleaning the crushed resinous
pieces while conveying the same is preferably two or three per one
zone. An axial length of the screw blade 662c per one zone is
preferably 0.5 to 3 relative to a diameter. While these screw
blades 662c, the cleaning plates 662a and the cleaning pins 662b
are alternately arranged, the number thereof disposed in one zone
may be equal in all zones or different from those of other
zones.
[0136] A pitch of the screw blades 662c must be determined by
taking a rotational speed of the rotary shaft into account. Since
the rotary shaft is necessarily made to rotate at a relatively high
speed for effectively abrading and cleaning the crushed resinous
pieces, the pitch is preferably in a range from 0.3 D to 1.5 D
wherein D represents a diameter of the screw blade 662c. If the
pitch is less than 0.3 D, a gap between adjacent two screw blades
is so small that the crushed resinous pieces may be caught in the
gap and rotate together with the screw blades to disturb the
transportation or the cleaning. Also, the crushed resinous pieces
caught in the gap may melt to disable the continuation of cleaning
operation. On the other hand, if the pitch exceeds 1.5 D, the
conveying efficiency is lowered. In this regard, when the conveying
efficiency of the screw blade 662c is excessively large and thus a
dwell time of the crushed resinous pieces becomes insufficient in
the area wherein the cleaning plates 662a or the cleaning pins 662b
are provided, part of the screw blade may be cut off so that a
balance is adjustable between the conveying capacity and the
cleaning operation.
[0137] Shapes of the cleaning plate 662a are not limited. For
example, the cleaning plate may be circular or polygonal, such as
triangular or quadrangular, as seen in the axial direction of the
rotary shaft 662. The cleaning plate 662a is not necessarily
symmetric in shape with respect to the rotary shaft 662. Also, it
may be slanted to the rotary shaft 662 to have a conveying
function. The cleaning plates inclined in the conveying direction
and in the opposite direction thereto may be combined with each
other to enhance the cleaning efficiency. The same is true to the
cross-sectional shape of the cleaning pin 662b, which may be
circular or polygonal such as triangular or quadrangular. The
polygonal cross-section is favorable because the cleaning
efficiency becomes higher. The cleaning pin 662b is not necessarily
projected vertical to the circumference of the rotary shaft 662 but
may be inclined at a proper angle.
[0138] The rotational speed of the rotary shaft 662 has a proper
range variable in accordance with sizes of devices, kinds of
crushed resinous pieces or degrees of cleaning demanded. Generally,
a linear speed of a tip end of the cleaning plate 662a or the
cleaning pin 662b is preferably in a range from 0.5 to 20 m/sec,
more preferably from 1 to 10 m/sec. In the rotational speed under
which the linear speed is less than 0.5 m/sec, it is impossible to
sufficiently clean the surface of the crushed resinous piece even
if the treatment time is prolonged. Contrarily, if the linear speed
exceeds 20 m/sec, the interior temperature of the cleaning device
rises to soften and be liable to melt the crushed resinous pieces,
which is unfavorable because a large driving power is
necessary.
[0139] At least part of surfaces to be in contact with the crushed
resinous pieces; that is, the inner surface of the vessel 660 and
surfaces of the screw blade 662c, the cleaning plate 662a and the
cleaning pin 662b; is roughened to constitute an abrasive surface.
Accordingly, the foreign matters on the surface of the crushed
resinous piece can be efficiently scrubbed or scraped off. A depth
of the irregularity on the roughened surface is preferably in a
range from 40 to 2000 .mu.m, more preferably from 50 to 1000 .mu.m,
most preferably from 60 to 500 .mu.m. If the depth is less than 40
.mu.m, the foreign matters could not be sufficiently removed. On
the other hand, if exceeding 2000 .mu.m, the surface of the crushed
resinous piece is excessively scraped off to unfavorably lower the
recovery percentage of resin. A degree of the above-mentioned
surface-roughening is not necessarily constant from the entrance
port 663 to the exit port 668. The cleaning efficiency may be
adjustable, for example, by changing the roughening degree to be
coarser toward the entrance port 663 and relatively smoother toward
the exit port 668. Also, the cleaning efficiency may be enhanced,
for example, by mixing various abradants with water.
[0140] While a two-shaft type cleaning device is illustrated in the
drawing, this is merely one example and a single-shaft type or a
multi-shaft type including a three- or more shaft type may be
adopted. When the single-shaft type is adopted, however, the
movement of the crushed resinous pieces becomes monotonous in the
device to lower the cleaning efficiency. Contrarily, the device
having three shafts or more is complicated in structure and
expensive.
[0141] An interior space of the cleaning device may be suitably
designed in accordance with throughputs or others thereof. An
interior dimension of the vessel 660 in the direction vertical to
the rotary shaft 662 may be suitably selected in accordance with a
diameter of the screw shaft 662c and a necessary gap between the
inner surface of the vessel 660 and a tip end of the screw blade
662c. An axial dimension of the rotary shaft 662 is 5 to 30 times,
preferably 10 to 30 times a diameter of the screw blade 662c.
[0142] If the axial dimension is less than five times the diameter
of the screw blade 662c, the crushed resinous pieces are conveyed
to the exit port 668 with part of them being not sufficiently
cleaned, which degrades the quality of recycled resin material due
to the mixture of the insufficiently cleaned crushed resinous
pieces. If the axial dimension exceeds 30 times the diameter of the
screw blade 662c, the mechanical strength of the rotary shaft 662
must be increased or a support system thereof must be changed,
which makes it difficult to prevent the inner surface of the vessel
660 from coming in contact with the screw blade 662c or others and
increases a cost of the device to a great extent.
[0143] While the above description has been made on a continuous
type cleaning device, a batch type may be adopted. FIG. 15
illustrates a batch type cleaning device of a vertical type as one
example thereof.
[0144] A vessel 661 is preferably cylindrical and formed of a metal
such as stainless steel. An entrance port 663 for introducing
crushed resinous pieces is provided on the upper surface of the
vessel 661, and an exit port 668 for discharging the crushed
resinous pieces is provided on the bottom surface thereof. A
piston-shaped valve 621 is provided in the exit port 668, so that
the valve is flush with the bottom surface of the vessel body when
the valve is closed. After the cleaning has completed, the
piston-shaped valve 621 is opened to take the crushed resinous
pieces out of the vessel.
[0145] On the lateral surface of the vessel 661, a water supply
port 664 is provided at an upper position and a drainage port 666
is provided at a lower position. A water level adjustment drainage
line 669 shown in FIG. 14 is connected to the drainage port 666.
Alternatively, the water supply port 664 may be provided on the
upper surface of the vessel 661, and the drainage port 666 may be
provided on the lower surface of the vessel 661. While the drainage
port 666 is formed throughout a lower area of the lateral surface
of the vessel 661 in FIG. 15, it may be provided on part of the
lower area of the lateral surface. Further, there is no limitation
in positional relationship between the entrance port 663 and the
exit port 668, but they are preferably provided on a diagonal of
the cross-section of the vessel 661. If so, all the crushed
resinous pieces are evenly and efficiently cleaned.
[0146] There is no limitation in shape of an agitator blade 603,
but a paddle type blade or a lattice type blade having a large
surface area is preferably used. The agitator blades 603 are
arranged at a center of the vessel 661, and at least part of the
inner surface of the vessel 661 and the surface of the agitator
blade is roughened. A degree of this roughening, a ratio between
the crushed resinous pieces and water and a size of openings such
as slits or holes of a punched plate provided in the drainage port
666 are similar to those in the above-mentioned horizontal type
continuous cleaning device.
[0147] [3] Recovery System 800
[0148] Then, the description will be made on the recovery system
800.
[0149] The recovery system 800 operates to separate foreign matters
from a mixture of the foreign matters and crushed resinous pieces
cleaned by the cleaning system 600 and recover the crushed resinous
pieces. The recovery system 800 may include various systems; for
example, a system for removing metallic material by using magnetic
force, a system for removing foreign matters by rinsing and a
system for removing foreign matters with wind.
[0150] A device illustrated in FIG. 16 separates the crushed
resinous pieces from the foreign matters by rinsing the mixture
thereof with water, discharges the foreign matters thus separated
together with water and recovers the remaining crushed resinous
pieces.
[0151] On the surface of the crushed resinous piece cleaned by the
cleaning system 600 as described above, foreign matters (dust
derived from coated film, plated layer or label) scrubbed or
scraped off from the crushed resinous pieces by the cleaning
operation are adhered. This mixture (of the crushed resinous
particles and the foreign matters) is initially introduced into a
continuous type rinsing device 881 and rinsed with water. Most of
the foreign matters adhered to the surface of the crushed resinous
pieces are removed therefrom together with water in this process.
This water may be reused after being filtrated.
[0152] The crushed resinous pieces thus rinsed are transferred via
a pipe 882 to a centrifugal dryer 883 in which the dehydration is
carried out. The crushed resinous pieces thus dehydrated are
conveyed while vibrating on a vibratory screen 884, whereby the
residual foreign matters are removed. Thereafter, the pieces are
collected by a predetermined recovery means. In this regard,
subsequent to the vibratory screen 884, means 889 may be provided
for further removing metallic particles by using magnetic force or
foreign matters by using wind.
[0153] Thus, the recycling of resin is carried out.
EXAMPLES
[0154] Results of the crushing operation carried out by using the
above-mentioned embodiment of the crusher described above are shown
in Table 1 of FIG. 17. The specifications of this crusher are as
follows:
[0155] Size of entrance port: 300 mm.times.600 mm
[0156] Width of chain conveyor: 340 mm
[0157] Motor: 5.5 kW
[0158] Rotational speed of conveyor: 50 rpm
[0159] Number of crushing blades in connecting plate: 2
rows.times.18/a plate
[0160] Opposite member: fixing plate with slits
I-[1] Example A
[0161] Twenty resinous parts were manually extracted from discarded
copying machines. Although having various sizes and shapes, the
parts were all mold products having a plate-thickness of
approximately 2 to 3 mm. The maximum length thereof was 630 mm.
These were classified into two groups in accordance with the
criterion whether or not the product has a size in which two of a
length, a width and a height are 280 mm.times.170 mm or less.
[0162] [1-1] Five parts had a size of 280 mm.times.170 mm or less,
a total weight of which was 2.3 kg.
[0163] [1-2] Fifteen parts had a size exceeding 280 mm.times.0.170
mm, a total weight of which was 9 kg.
[0164] These mold products were crushed by the crusher shown in
FIG. 3 (the specifications of which were as described above).
[0165] Results were shown in Table 1 of FIG. 17. In Table 1, an
equivalent diameter of a projection circle in Table 1 is defined as
a diameter of a circle having the same area as a projected area of
a particle (see KAGAKU KOGAKU BINRAN, 5th edition, p. 219). In this
Example, an image of about 100 particles placed on a flat surface
while taking care not to overlap with each other was shot, from
which the number and the individual area are measured by an
image-processing technique. Then a total of the areas was divided
by the number of particles to obtain an average area, from which a
diameter of a circle having the same area is calculated.
I-[2] Comparative Example A
[0166] A trial was made to treat the same resin mold products as
used in Example A with a small size crusher UG-280 (effective
aperture 280 mm.times.170 mm, 5.5 kW) manufactured by K. K. HORAI
and added with a screen of 15 mm .phi..
[0167] However, the resin mold products in the group [1-2]
(exceeding 280 mm.times.170 mm) could not be introduced into the
small size crusher UG-280 of K. K. HORAI and thus could not be
crushed.
II-[1] Example B
Regarding the Identification
[0168] The following three mold products 1. to 3. of different
kinds of resins (a box having a size of 15 cm.times.10 cm.times.10
cm and a thickness of 3 mm) were individually crushed by the
crusher UG-280 manufactured by K. K. HORAI (with a screen of 20 mm
mesh). An average size of the crushed resinous piece was
approximately 10 mm as represented by an equivalent diameter,
wherein the equivalent diameter is a diameter of a circle having
the same area as a projected area of the crushed resinous
piece.
[0169] The above crushed resinous pieces are respectively packed in
separate bags (made of polyethylene and having a size of 23 cm
long, 17 cm wide and 40 .mu.m thick). Kinds of the resins were
identified by a resin identification device (RP-1, manufactured by
Spectracode; based on the Raman spectrum analysis), upon which a
time required for the identification was measured. Results are
shown in Table 2 of FIG. 18. In Table 2, .largecircle. represents
cases wherein all the samples could be identified, and .times.
represents cases wherein there are samples not identified.
[0170] 1. Acrylonitrile-butadiene-styrene
[0171] 2. Polystyrene
[0172] 3. Polycarbonate/acrylonitrile-butadiene-styrene
II-[2] Comparative Example B
Regarding the Identification
[0173] Comparative example B was carried out in the same manner as
in Example B, except that the above-mentioned three resin mold
products 1. to 3. were crushed all together, not separately, in the
crusher and the three kinds of resinous pieces were identified as
they are by the resin identification device, respectively, without
being packed in the bag. Results are shown in Table 2 of FIG.
18.
[0174] In Table 2, the number of test samples was assumed by the
following equation:
[0175] Number of test samples=weight of resin mold product before
crushing/standard weight of crushed piece
[0176] The weight of the resin mold product before crushing was 702
g and the standard weight of the crushed piece was 0.259 g, whereby
the number of the test samples was 2700. This value is about 900
times that in Example B. In this regard, an average weight of ten
disk-like pieces having the equivalent diameter of approximately 10
mm was used as the standard weight of the crushed piece.
[0177] In Table 2, the time required for the identification was
assumed by the following equation:
[0178] Time required for identification=all weights of crushed
pieces/weight of crushed pieces which could be identified within
one minute
[0179] All the weights of the crushed pieces was 702 g and the
weight of the crushed pieces which could be identified within one
minute was 5.21 g, whereby the time required for the identification
was 135 minutes. This value is about 900 times that in Example B.
In this regard, in the crushed pieces having the equivalent
diameter of 1 mm or less, there were those difficult to be
positioned to the identification device or impossible to be
identified because the intensity of Raman spectrum becomes
weak.
[0180] Next, an example regarding the cleaning system will be
described.
[0181] OA apparatuses collected from the market were disassembled
to separate housings made of ABS resin which were then crushed by
using a marketed crusher (UG-280; manufactured by K. K. HORAI, with
a screen of 10 mm mesh) into crushed resinous pieces and subjected
to a cleaning treatment. There were paper seals on part of the
housing and many contaminants on the surface due to a long time use
or the collection, disassembly or classification operation.
Hereinafter, such crushed resinous pieces are referred to as
crushed pieces (A).
[0182] In a similar manner, housings made of ABS resin and having a
coating on the surface thereof were crushed into crushed pieces (B)
which were then cleaned.
III-[1] Example C
Regarding the Cleaning by the Horizontal Type Continuous Cleaning
Device Shown in FIGS. 12 and 13
[0183] (1) Cleaning Device Used
[0184] A diameter of a screw blade provided on a rotary shaft of
the cleaning device was 100 mm and a length of the device was 25
times the diameter of the screw blade; i.e., 2.5 m. A drainage port
had slits of 1.2 mm wide. A water level was maintained somewhat
higher than the rotary shaft by the water level adjustment pipe, so
that a weight of crushed pieces. (A) and that of rinsing water are
generally equal to each other.
[0185] Further, the screw blades and cleaning plates constituted by
semicircular disks arranged on the rotary shaft at a pitch of 40 mm
with a phase thereof being shifted at 90 degrees to each other were
alternately disposed on the rotary shaft so that a ratio of an
axial length to the diameter thereof becomes 2 to 4. Part of the
screw blade was cut off to adjust the conveying capacity. The inner
surface of the vessel and the surfaces of the screw blades and the
cleaning plates were roughened to have the irregularity of 50 to
100 .mu.m deep.
[0186] (2) Cleaning Operation
[0187] Crushed pieces (A) were introduced into the entrance port of
this cleaning device at a rate of 50 kg/hr. On the other hand,
water was fed from the entrance port at a rate of 30 kg/hr and also
from two water ports provided in the lengthwise intermediate
portion of the device. These water supply rates were regulated so
that a drainage rate from an open end of the drainage line becomes
100 kg/hr.
[0188] The cleaning operation was carried out at a rotational speed
of the rotary shaft of 400 rpm (corresponding to a linear speed of
2.1 m/sec at a tip end of the cleaning plate) to obtain a slurry in
which dust such as the paper seals blocked to pass by the slits is
mixed with the treated crushed pieces (A) from the exit port. The
slurry was dispersed on the vibratory screen of 2 mm mesh while
spraying water from above to separate and remove pieces of the
paper seals or dust therefrom. Thereafter, the crushed pieces were
dehydrated through a centrifugal dryer and dried. Then, through a
wind classifier, foreign matters having a small specific weight
which could not removed by the water spray were separated and
removed to obtain completely cleaned crushed pieces.
[0189] (3) Inspection of Foreign Matters
[0190] Crushed pieces of 10 g were compression-mold between a pair
of clean aluminum foils put in a gap between stainless steel plates
at a temperature of 220.degree. C. and a pressure of 4 MPa to
result in a sheet of approximately 200 mm diameter. Thereafter, the
aluminum foils were peeled off from this sheet, and opposite sides
of the sheet were observed by a magnifying glass to count the
number of foreign matters. Results are shown in Table 3 of FIG.
19.
III-[2] Comparative Example C
[0191] A trial was made to clean the crushed pieces (A) in the same
manner as in Example C, except that water is not used. In a short
time after beginning the introduction of crushed pieces, however,
the crushed pieces began to melt, whereby a load became large to
disable the operation.
III-[3] Comparative Example D
[0192] A rotational speed at which the crushed pieces are not
melted was studied in Comparative example C, and it was found that
such a speed is 50 rpm (corresponding to a linear speed of 0.26
m/sec at a tip end of the cleaning plate). The cleaning operation
was carried out at this rotational speed in the same manner as in
Comparative example C in which water is not used. After being
cleaned, the crushed pieces (A) discharged from the exit port were
post-treated in the same manner as in Example C to separate and
remove the foreign matters. Foreign matters left in the crushed
pieces were observed in the same manner as in Example C. Results
are shown in Table 3 of FIG. 19.
III-[4] Example D
[0193] The crushed pieces (B) were cleaned in the same manner as in
Example C except that a water supply rate from the intermediate
portion increases so that a drainage rate is regulated to 200 kg/hr
at the open end of the drainage line. After being cleaned, the
crushed pieces (B) discharged from the exit port were post-treated
in the same manner as in Example C to separate and remove foreign
matters. Foreign matters left in the crushed pieces were observed
in the same manner as in Example C. Results are shown in Table 3 of
FIG. 19.
III-[5] Comparative Example E
[0194] The cleaning was carried out in the same manner as in
Example D except that the rotational speed of the rotary shaft
decreases to 50 rpm. After being cleaned, the crushed pieces (B)
discharged from the exit port were post-treated in the same manner
as in Example C to separate and remove foreign matters. Foreign
matters left in the crushed pieces were observed in the same manner
as in Example C. Results are shown in Table 3 of FIG. 19.
III-[6] Example E
Regarding the Cleaning by the Batch Type Cleaning Device of a
Vertical Type Shown in FIG. 15
[0195] This cleaning device had a vessel having an inner diameter
of 400 mm and a height of 500 mm, in which lattice type blades
having an outer diameter of 360 mm is provided at a center. The
inner surface of the vessel and all surfaces of the lattice type
blades were roughened to have the irregularity of 200 to 300 .mu.m
deep.
[0196] The crushed pieces (A) of 22 kg and water of 20 kg were
introduced into this cleaning device, and a height of the water
level adjustment pipe is regulated to the water level at this
instant. The cleaning operation was carried out for 20 minutes by
rotating the lattice type blade at 300 rpm and supplying and
draining water at a rate of 20 l/hr. After being cleaned, the
cleaned crushed pieces (A) were taken out therefrom by opening the
piston-shaped discharge valve. The crushed pieces were post-treated
in the same manner as in Example C to separate and remove foreign
matters. Foreign matters left in the crushed pieces were observed
in the same manner as in Example C. Results are shown in Table 3 of
FIG. 19.
III-[7] Comparative Example F
[0197] The cleaning operation was carried out in the same manner as
in Example E except that a crusher in which the inner surface of
the vessel and surfaces of the agitator blades are not roughened.
After being cleaned, the cleaned crushed pieces (A) were taken out
therefrom by opening the piston-shaped discharge valve. The crushed
pieces were post-treated in the same manner as in Example C to
separate and remove foreign matters. Foreign matters left in the
crushed pieces were observed in the same manner as in Example C.
Results are shown in Table 3 of FIG. 19.
[0198] It is apparent from Table 3 of FIG. 19 that there are
extremely less foreign matters in the crushed pieces after being
cleaned by roughening part of the crusher to be in contact with the
crushed pieces. Particularly there are none of foreign matters, of
which the maximum length exceeds 0.25 mm. On the other hand, it is
also apparent that; in Comparative example C, the operation of the
crusher is impossible due to the melting of crushed pieces; in
Comparative examples D and F, particularly in D, a number of
foreign matters are left in the treated crushed pieces; and in
Comparative example E, the number of foreign matters is uncountable
because of a large amount of remnants derived from coated film. In
other words, Comparative examples are all extremely inferior.
[0199] The present invention has been described in detail with
respect to preferred embodiments, and it will now be apparent from
the foregoing to those skilled in the art that changes and
modifications may be made without departing from the invention in
its broader aspects, and it is the intention, therefore, in the
appended claims to cover all such changes and modifications as fall
within the true spirit of the invention.
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