Note: Descriptions are shown in the official language in which they were submitted.
1324787
TITLE OF THE INVENTION
SQUID CHI~IN FORMED MATERIAL
BACKGROUND OF THE INVEN~ION
Field of the Invention: :
This invention relates to a novel squid chitin
formed material, and, more particularly, to a s~uid
chitin formed material, such as a ~quid chitin sheet, a
s~uid chitin fiber, and the like. The squid chitin
formed material has excellent characteristics such a~
~uperior strength and the like.
Descri~tion of the Backqround:
Since formed materials made of chitin are fn vivo
decomposable, they are widely used as suture threads,
wound covering or protecting materials, dialysis
membranes, molecular filters, ultra-membrane filters,
and the like~ ~
According to a conventionally known method for ::.
preparing material~ formed of chitin, exoskeletons of a
crustacean or an insect are first treated with .:~
hydro~hloric acid and sodium hydroxide, and chitin - .
separated is formed into a sheet or the like (Japane~e
Patent Laid-open Nos. 53339/1986, 64256/1986,
129005/1986, and 212302/lY86).
Chitins made from oxoskeletons of crustacean or :-
insects, however, exhibit only poor dope forming
capability, resulting in form~d chitin materials having
'~ ' '''`-,
r
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inadequate characteristic~ such as in~ufficient
strength, reduced elongation, or the like. Thus,
chitins produced from conventional sources have
problems still to be solved. In an attempt to improve
the in~ufficient chitin properties, Japanese Patent
Laid-open No~. 53339/1986 and 64256/1986 propo~e to
employ a water soluble polymer as a binder. This
method, however, does not necessarily provide a
~atisfactory solution.
In view of this situation, the pre~ent inventors
have undertaken extensive studies in order to solve the
above problems, and found that ~mong chitins produced
from a number of raw materials ~quid chitins made from
squid crust possessed excellent characteristics. The
inventors have further found that among squid chitins
those produced from squid galadius of ~ol l usca,
Teutho~de~, had exceptionally superior characteristics,
and could be formed into superb chitin sheets and the
like. Such a finding has led to the completion of this
invention.
SllMNARY OF THE INVENTION
Accordingly, An ob~ect of this invention is to
provide a ~quid chitin formed material prepared from
squid chitin which iB separated from squid crust.
Other ob~ects, features and advantage~ of the
.
invention will hereinafter become more readily apparent
from the following description.
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The present invention, in one aspect, resides in a
process of preparing a squid chitin sheet comprising:
grinding squid chitin, suspending the ground squid chitin
in water, forming a gel of said squid chitin, suspending
the gel in water, submitting the suspension to ~iltration
to eliminate water, and drying the residue.
In another aspect, the present invention resides in
a process of preparing squid chitin fiber comprising:
dis~olving squid chitin in formic acid, subjecting the
solution to a freeze-defrost treatment to produce a dope,
defoaming the dope in vacuo, and extruding the defoamed
dope into a solvent to coagulate the dope.
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D~TAILED DESCRIP~ION OF THE INVENTION
AND PREF~RRED EMBODIMENTS
Any ~quid crusts can be used as a raw material for
preparing the squid chitin formed material of thi~
invention 80 long as the crusts are those from squids
belonging to the division of ~ollusca, the order of
Decapoda. Specific examples of the squid~ are those
from the suborder Sepioidea such as Spirula, Sep~a,
Sepiola, from the suborder Teuthoidea such as Loligo,
Doryteuthis, S~pioteuthis, Natasenfa, Onychoteuth~s,
Architeuthis, ~adarode~, Chiroteuth~s, Ommastraph~s,
Illex, Gon~topsis, and the like.
For preparing squid chitin from squid crust
according to this invention, squid crust i8 first
pulverized, and treated with caustic soda and
h~drochloric acid to remove proteins and ashes. More
specifically, taking the preparation of squid chitin
from squid galadius a8 an example, the pulverized s~uid
galadius is treated with sodium hydroxide solution of
about 1 N at about 90C for approximately 1 hour. The
treatMent with hydrochloric acid is performed u~ing an
aquaous hydrochloric acid ~olution of around 0.1 N
concentration at room temperature for about 1 hour.
Squid chitin 18 then obtained by drying the treated
material thus prepared.
For preparing the squid chitin sheet of this
invention squid chitin sufficiently ground as fine as
16 mesh is ~uspended into water at a concentration of 5
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to 20% by weight, ~tirred vigorously or sub~ected to a
freeze-defrost tr~atment. Through these treatments the
squid chitin absorb~ water and swells increasing it~
viscosity, and ultimately becomes a gel. The gel is
suspended into water and the suspension is submitted to
a paper-making operation; i.e., it is fed onto a filter
to eliminate water. The residue is then dried to
produce a squid chitin sheet.
If the above-mentioned procedure is applied to
crab chitin, even though it is submitted to the
stirring operation or the freeze-defrost treatment, ~ -
crab chitin does not form a gel. It is therefore
necessary to manufacture a crab chitin sheet first to
prepare crab chitin fiber and then to make the fiber
into a sheet, as will be discussed later. Accordingly,~ -
a chitin sheet made from crab chitin i8 something like
non-woven cloth, which i8 quite different from the
squid chitin sheets prepared by thi~ invention.
Squid chitin fiber can be prepared by the
following method according to this invention. The
squid chitin separated by the procedure mentioned above
is di~solved into formic acid at a concentration of 2 ~-
to 15% by weight. ( The specific squid chitin
concentration in formic ac~d may vary depending on the
purpose intended.) Freeze-defrost treatments are
performed two or three times on this solution to
di~integrate inter- or intra-molecular hydrogen bonds ;
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of squid chitin and to produce a transparent and
homogeneous dope. The dope is defoamed in vacuo and is
extruded into a ~quid chitin coagulating-solvent to
produce squid chitin fiber. An alcohol such a~
methanol, ethanol, propanol, butanol, or the like, or a
ketone such as acetone, methyl ethyl ketone, or the
like, or a mixture of two or more of these solvents can
be used a~ a ~quid chitin coagulating-solvent.
If the above procedure 16 to be applied to a chitin
from exoskeletons of crabs, for example, 20 to 30 times
freeze-defrost treatments are required. This takes a
much longer period of time for the treatment. In
addition, this long period treatment with formic acid
reduces the polymerization de~ree of chitin molecules.
This makes it impossible to produce a fiber having
sufficient strength.
Some of the characteristics of a squid chitin
aheet and a s~uid chitin fiber prepared from the squid
chitin of this invention are compared with those
produced from a conventional crab chitin.
(1) Chitin sheet
Squid chitin sheet: prepared in Example 1
Crab chitin ~heet: prepared in Reference Example 2
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Table 1
Breaking Folding
Weig~t Streng~h Endurance
(g/m ) (RPa m~/g) ~ (Times) **
Squid chitin sheet29 9.0 > 16 (1 kg) ~ -
Crab chitin sheet115 1.5 10 (500 g) :-
.:'
* Breaking Strength: The pressure (per unit weight of
chitin sheet) required to pulverize a chitin .. ~
sheet. ~.
** Folding Endurance: A chitin sheet i5 folded while
pressure is exerted on the sheet using a 500 g
or 1 kg plumb. ~Folding Endurance~ is the number . :
of timeis for which the chitin sheet is folded
before it is broken. .
(2) Chitin fiber
Squid chitin flber: prepared in Example 2
Crab chitin fiber: prepared in Reference Exzmple 1
Table 2
Strength Elongation
(g/d) * (~
. .
Squid chitin fiber 5.0 5.0
Crab chitin fiber 1.6 4.3
* Strength (Pulling strength): The force required to
break 50 ~tringis of fiber.
** Elongation: A ratio of elongation (as per the
original length) when 50 strings o~ fiber i5
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pulled and broken.
~ s demonstrated in the above test, the squid
chitin formed materials of thi3 invention have better
physical properties than conventional crab chitin
formed materials in terms of ~trength, folding
endurance, etc. Although the details are still to be
elucidated, these superior characteri~tic~ are presumed
to be a result of the more oriented nature o~ squid
chitin crystals than crab chitin crystals.
Other feature~ of the invention will become
apparent in the course of the following description of
the exemplary embodiment~ which are given for
illustration of the invention and are not intended to
be limiting thereof.
EXAMPLES
Example l
(i) One (1) kg of Tadarodes galadiuQ was ground -
by a feather mill (5 m/m screen pas~ he ground ~ -
galadius was put into a 1 N NaO~ solution, heated at
90C for 1 hour, washed with water, and dipped into a
0.1 N HCl solution at room temperature for 1 hour. The
ground material then was washed with water and again
heated nt 90C in a 1 N NaOH ~olution for 1 hour.
After washing with water, the material was dried in an
oven ~t 50C for 5 hours to produce lOO g of squid
chitin.
(ii) Ten (10) g of the ~quid chitin produced in
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: .
(i) above was pulverized by an"Osterizer"* The
pulverized chitin wa~ suspended into 400 ml of water
and vigorou~ly ~tirred to increase the viscosity. The
viscous gel-like product thus obtained was sub~ected to
a conventional water ~et fall-type paper machine, each
20 ml a batch, and the sheet produced was air-dried at
room temperature. The squid chitin sheet prepared
having a weight of 29 g/m2 had breaking strength of 9
gPa m2/g and folding endurance of at least 16 at a 1 kg
plumb weight.
Letters were printed with ink onto the s~uid
chitin sheet. The ink wa~ well attached onto the sheet
with no run or blur.
Example 2
Twenty (20) g of the squid chitin produced in
Example l(i) was pulverized by an'~sterize~'to produce a
homogeneous chitin particles. S00 ml of formic acid
was added to the chitin particles. The mixture was
stirred slowly, and allowed to qtand at room
temperature until needle-like solid materials contained therem
disappeared. After freezing at -20C, the fro~en
material was thawed, gently stirred, and wa~ again
frozen and thawed to produce a transparent and
homogeneous dope. This dope was deaerated in vacuo,
and extruded into a mixed solvent of acetone and 50%
ethanol through a nozzle with 30 holes, each hole
having a diameter of 0.09 m/m, at an extrusion pressure
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*Trade mark
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of 1.5 Rgf/cm2, and an extender having a first roller
rotating at o.1 m/sec. and a second roller rotating at
0.11 m/sec., to produce wet squid fiber. The squid
fiber was neutxalized with a 0.5 N NaOH-methanol
mixture, washed with methanol, and air-dried at room
temperature to obtain dried squid chitin fiber.
The squid chitin fiber had strength (pulling
strength) of 5.0 g/d and elongation of 5.0%. The squid
chitin fiber produced according to th~ method
po~sessed silky gloss.
Reference Example 1 (Preparation of crab chitin fiber) -
(1) One (1) kg of C~ionaecetes opilio crab shell -
~exoskeleton) was ground by a coffee grinder. The
ground crab ~hell was put into a 1 N NaOH solution,
heated at 90C for 1 hour, washed with water, dipped
into a 2 N HCl solution at room temperature for 6
hours, and then was washed with water. This ~ame
proceduxe was performed 3 times. After washing with
water, the finally obtained material was dried in an
oven at 50C for 3 hours to produce 150 g of crab
chitin.
(ii) Twenty-three (23) g of the crab chitin
produced in (i) above was pulverized by an'~sterizer"
and 490 ml of formic acid was added to the chitin
particles. The mixture was stirred slowly, and allowed
to stand at room temperature until needle-like solid
~aterials contained therein disappeared. 12 hours after
~n ~
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freezing at -20C, the frozen material was thawed at
room temperature. The thawed material was gently
stirred, and again frozen to produce a dope. ~hi~
frozing-thawing operation wa~ once more repeated. The
dope finally obtained was deaerated in vacuo, and
extruded into a mixed 301vent of ethyl acetate and
water through a nozzle with 30 hole~, each hole having
a diameter of 0.09 m/m, at an extrusion pressure of 1.3
Rgf/cm2, and extended at an ex~ension ratio of 1.29.
The crab fiber was washed in a stream of water
overnight to obtain wet crab chitin fiber.
(iii) The wet crab chitin fiber was air-dried at
room temperature to obtain dried crab chitin fiber.
Reference Example 2 (Preparation of crab chitin sheet)
The crab chitin fiber prepared in Reference
Example 2 was cut into 5 m/m length, and a prescribed
amount of the cut crab chitin fiber was suspended into
water. A conventional water ~et fall-type paper
milling was performed on the crab chitin suspension,
and a sheet produced was air-dried at room temperature ~ -
to produce a crab ch~tin sheet.
Obviously, numerous modification~ and variations
o the pre~ent Invention are pos~ible in light of the
above teachings. It is therefore to be understood that
the scope of the appended claims, the invention may be
practiced otherwise than as specifically described
herein.
