Title of Invention

A METHOD FOR PRODUCING AN ANTI-ADHESION MATERIAL

Abstract According to the present invention there is provided a method for producing an anti-adhesion material that is constituted of a thermally crosslinked gelatin film, and has a water content of 60 to 85% calculated by the following formula : water content (%) = [(Ws-Wd)/Ws] x 100 (%) in which Ws represents a weight (wet weight) of the anti- adhesion material immersed in a phosphate buffered saline solution at a temperature of 25°C for one hour, and wd represents a weight (dry weight) of the anti-adhesion material dried completely using a vacuum drying apparatus(1), said method comprising a step of thermal crosslinking under a reduced pressure (1Torr or less); at a temperature of 120 to 170°C; and for 30 minutes to 72 hours, of a non-crosslinked gelatin film(2), sandwiched between two sheets(3) having the same thermal conductivity.
Full Text

DESCRIPTION
ANTI-ADHESION MEMBRANE
TECHNICAL FIELD
[0001]
The present invention relates to an anti-adhesion
membrane that has no toxicity to a living body, has
flexibility allowing itself to fit an affected part as a
hydrated gel, is uniformly crosslinked, and is immediately
absorbed in a living body after maintaining its shape in
the living body for a certain period of time.
BACKGROUND ART
[0002]
After a surgical operation, living body tissues often
adhere to one another to cause a pain or a functional
disorder. Adhesion occurs as a serious problem especially
in a field such as obstetrics and gynecology, digestive
surgery, orthopedics, and cardiovascular surgery, and a
severe case requires an operation to separate the adhesion.
In addition, occurrence of an adhesion increases risk upon
a re-operation of a primary disease. As a method for
preventing the adhesion of living body tissues, there has
been proposed a method for isolating an area with a
possibility of occurrence of the adhesion using a membrane
called an anti-adhesion material.
[0003]
The anti-adhesion material is required to have
properties as follows: having flexibility that allows
itself to fit an affected part as a hydrated gel; being
immediately absorbed by a living body after maintaining its
shape in the living body for a certain period of time;
causing only slight tissue reaction; and the like. As an
anti-adhesion material satisfying the above-mentioned

properties, there has been proposed an anti-adhesion
material comprising a film containing gelatin (for example,
Patent Documents 1 to 6) . Gelatin is a polymer derived
from a living body, and has an excellent biocompatibility
and the like.
[0004]
However, gelatin films, as they are, absorb water in
a living body so as to swell greatly, or are degraded in a
very short period of time so as to be deformed. For these
reasons, there have been problems that the gelatin films
are difficult to handle and fail to produce sufficient
effects on prevention of adhesion. In order to solve the
problems, Patent Documents 1 to 6 disclose that
crosslinking of a film containing gelatin by a suitable
method allows the film to have a suitable water-containing
property and suitable degradation. For example, Patent
Documents 1, 4, 5, and 6 disclose ultraviolet-crosslinking,
and Patent Documents 2 and 3 disclose a chemical
crosslinking agent used in a combination.
However, there has been a problem that an anti-
adhesion material comprising an ultraviolet-crosslinked
gelatin film may be deformed in a living body at an early
stage of use, in spite of its high degree of crosslinking.
On the other hand, the method of using a chemical
crosslinking agent has a problem of a residue of a
crosslinking agent or generation of a by-product derived
from the crosslinking agent upon degradation in a living
body.
Patent Document 1: Japanese Kokai Publication No.
Hei-11-47258
Patent Document 2: Japanese Kokai Publication No.
Hei-11-279296
Patent Document 3: Japanese Kokai Publication No.
2000-212286
Patent Document 4: Japanese Kokai Publication No.

2003-62063
Patent Document 5: Japanese Kokai Publication No.
2004-209228
Patent Document 6: Japanese Patent No. 3517358
DISCLOSURE OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0005]
The present inventors found out that nonuniform
crosslinking formed in an anti-adhesion material comprising
an ultraviolet-crosslinked gelatin film causes early
deformation of the anti-adhesion material in a living body,
in spite of its high degree of crosslinking. That is, in
case of obtaining a crosslinked gelatin film by irradiation
with ultraviolet rays, the gelatin absorbs the ultraviolet
rays, resulting in a higher degree of crosslinking in a
part relatively closer to the surface of the gelatin film
but a lower degree of crosslinking in a part deep in the
thickness direction. Especially, in case of using gelatin
containing impurities, irradiating the impurities with
ultraviolet rays causes deterioration and discolor in a
part of gelatin, leading to absorption of more ultraviolet
rays. In case of disposing, in a living body, an anti-
adhesion material comprising the above-mentioned gelatin
film crosslinked nonuniformly in the thickness direction,
although stable appearance of its shape immediately after
an operation, degradation of a part neighboring a central
part with a low degree of crosslinking proceeds rapidly,
and subseguently the central part disappears, resulting in
failure to maintain its shape. In addition, the anti-
adhesion material comprising the gelatin film nonuniformly
crosslinked causes a problem of an inferior property such
as poor tensile strength to that of an anti-adhesion
material comprising a gelatin film uniformly crosslinked as
a whole.

Moreover, the method for using a chemical
crosslinking agent causes problems of a residue of the
crosslinking agent and release of a substance having a low
molecular weight due to degradation of a crosslinked part.
In light of the above-mentioned problems, an object
of the present invention is to provide an anti-adhesion
membrane that has no toxicity to a living body, has
flexibility allowing itself to fit an affected part as a
hydrated gel, is uniformly crosslinked, and is immediately
absorbed in a living body after maintaining its shape in
the living body for a certain period of time.
MEANS FOR SOLVING THE PROBLEM
[0006]
The present invention provides an anti-adhesion
material, which comprises a thermally crosslinked gelatin
film, and has a water content of 60 to 85% calculated by
the following formula (1):
water content (%) = [(Ws-Wd)/Ws] x 100 (%) (1),
in the formula (1), Ws representing a weight (wet weight)
of the anti-adhesion material immersed in a phosphate
buffered saline solution at a temperature of 25°C for one
hour, and Wd representing a weight (dry weight) of the
anti-adhesion material dried completely using a vacuum
drying apparatus.
Hereinafter, the present invention will be described
in detail.
[0007]
The present inventors has conducted further studies
and completed the present invention with the following
findings. That is, a thermally crosslinked gelatin film is
more uniformly crosslinked than an ultraviolet-crosslinked
gelatin film, and also produces no highly toxic substance
having a low molecular weight, unlike the case of a method
using a chemical crosslinking agent. Patent Documents 6

and the like contain reference of thermal crosslinking of
gelatin but no detailed description of a degree of
crosslinking or a method for crosslinking required to
obtain sufficient performance as an anti-adhesion material.
[0008]
The anti-adhesion material of the present invention
comprises a thermally crosslinked gelatin film.
A material for the gelatin film is not particularly
limited, and examples thereof include a gelatin derived
from a bone, a tendon, skin and the like from bovine, swine,
chicken, salmon and the like.
The preferable lower limit of a weight-average
molecular weight, measured by GPC, of gelatin to be used as
the material for the gelatin film is 100,000, and the
preferable upper limit thereof is 300,000. Gelatin having
a weight-average molecular weight of less than 100,000
causes a lowered tensile strength of the obtained anti-
adhesion material of the present invention. On the other
hand, the upper limit thereof is defined as 300,000, based
on a property of gelatin that never has a weight-average
molecular weight of more than 300,000. Here, the more
preferable lower limit is 150,000 and the more preferable
upper limit is 300,000.
[0009]
The preferable lower limit of a jelly strength of the
gelatin to be used as the material for the gelatin film is
150 g, and the preferable upper limit thereof is 350 g.
The reason can be explained as follows. Gelatin having a
jelly strength of less than 150 g possibly results in the
anti-adhesion material of the present invention having a
larger deformation ratio or a lower tensile strength. In
addition, production of gelatin having a jelly strength of
more than 350 g is attended with difficulties. The more
preferable lower limit is 250 g, and the more preferable
upper limit is 350 g.

Here, in this description, the jelly strength refers
to a jelly strength defined in JIS K 6503-2001, and is
measured by load required for a 4 mm depression of the
surface of a jelly by a plunger having a diameter of 12.7
mm at a speed of 1 mm/s, the jelly being prepared by
cooling a 6.67% by weight gelatin solution for 17 hours at
a temperature of 10°C.
[0010]
As the gelatin to be used as a material of the
gelatin film, alkali treated gelatin is preferably used due
to the significantly low endotoxin content and the
excellent safety, and specific examples thereof include
alkali treated gelatin derived from cattle and alkali
treated gelatin derived from swine produced by Nippi,
Incorporated, and the like.
[0011]
Into the gelatin to be used as a material of the
gelatin film, for example, glycerin, polyethylene glycol,
hyaluronic acid and the like may be added in an amount not
inhibiting the purpose of the present invention, in order
to allow the film to have flexibility. In addition, a
conventionally well-known additive such as an antimicrobial
agent and an anti-inflammatory agent may be added.
[0012]
The gelatin film can be obtained as follows: a
gelatin solution is prepared by dissolving the raw gelatin
in a suitable solvent, casted onto a water-repellent glass
plate or a water-repellent release sheet such as a sheet
(tray) made of polystyrene and a sheet (tray) made of
fluorine resin, and then dried.
That is, first, the raw gelatin is dissolved in a
solvent under heating. As the above-mentioned solvent, for
example, distilled water, dimethyl sulfoxide (DMSO) and the
like, or a mixed solution thereof may be used. Out of
these, distilled water is preferably used in terms of easy

handling.
Although an amount of the gelatin to be added is not
particularly limited, the preferable lower limit thereof is
0.1 g with respect to 100 mL of the solvent, and the
preferable upper limit thereof is 50 g. Addition of less
than 0.1 g of the gelatin may cause difficulties in forming
thereof into a film. Addition of more then 50 g of the
gelatin may cause difficulties in uniform casting thereof
due to the high viscosity. The more preferable lower limit
is 1 g, and the more preferable upper limit is 30 g.
Although a temperature for dissolving the gelatin is
not particularly limited, the preferable lower limit
thereof is 30°C, and the preferable upper limit thereof is
70°C. Dissolution of the gelatin at a temperature of less
than 30°C may require a longer time. Dissolution of the
gelatin at a temperature of more than 70°C may cause
degradation and a lowering in molecular weight of the
gelatin, leading to a decrease in the jelly strength. The
more preferable lower limit is 40°C, and the more
preferable upper limit is 60°C.
[0013]
A non-crosslinked gelatin film can be produced by
casting the obtained solution containing the dissolved
gelatin into a petri dish made of polystyrene or fluorine
resin, and the like, and drying the solution.
A method employed for the above-mentioned drying
process is not particularly limited, and for example, air
drying, drying by heating, drying under a reduced pressure
(vacuum drying), forced exhaust drying, forced circulating
convection and the like may be used.
The preferable lower limit of a temperature employed
in the above-mentioned drying process is -40°C, and the
preferable upper limit thereof is 60°C. Drying of the
gelatin film at a temperature of less than -40°C may
require an excessively long time. Drying of the gelatin

film at a temperature of more than 60°C causes degradation
and a lowering in molecular weight of the gelatin. The
more preferable lower limit is 0°C, and the more preferable
upper limit is 40°C.
[0014]
The above-mentioned series of the production
processes of the gelatin film are preferably carried out
under aseptic conditions, for example, in a clean bench or
a clean room. This is because the gelatin film should be
prevented from occurring contamination of bacterial
proliferation during operation. For this reason, a
production apparatus to be used is preferably sterilized,
for example, by an autoclave, EOG (ethylene oxide gas), dry
heat, electron rays and the like. Moreover, the gelatin
solution is also preferably sterilized, for example, by a
conventionally well-known filter filtration sterilization,
before used in the above-mentioned processes.
[0015]
The gelatin film obtained as described above is
thermal-crosslinked.
Thermal crosslinking allows the gelatin film to be
more uniformly crosslinked than ultraviolet-crosslinking,
and also produces no highly toxic substance having a low
molecular weight, unlike the case of a method using a
chemical crosslinking agent.
[0016]
Although a method employed for the above-mentioned
thermal crosslinking process is not particularly limited,
the film is preferably heated uniformly from the both faces
thereof. Heating from the both faces enables the gelatin
film to have a shape uniformly crosslinked even in the
thickness direction.
Heating is preferably carried out under a reduced
pressure of 1 Torr or less. The reduced pressure enables
suppression of thermal decomposition of the gelatin caused

by heating.
[0017]
As a method employed for the above-mentioned thermal
crosslinking process of the gelatin film, the preferable
method is that the non-crosslinked gelatin film sandwiched
between two sheets having the same thermal conductivity is
heated under a reduced pressure. A method of this kind
allows heat to be uniformly conducted to the non-
crosslinked gelatin film through the two sheets, resulting
in a uniform crosslinked shape of the gelatin film in both
of the thickness direction and the plane direction.
The method for producing an anti-adhesion material
which comprises a step of thermal-crosslinking including
heating under a reduced pressure with a non-crosslinked
gelatin film sandwiched between two sheets having the same
thermal conductivity is also one aspect of the present
invention.
[0018]
Here, in case of carrying out thermal crosslinking
simultaneously on a large number of non-crosslinked gelatin
films, the gelatin films and the sheets having the same
thermal conductivity needs to be laminated alternately to
form a shape in which each of the gelatin film is
sandwiched between the above-mentioned two sheets. However,
a large number of laminated sheets may cause nonuniform
heat distribution between a peripheral part and a central
part of a laminated part. That is, thermal conduction may
vary according to a distance from a heat source. In this
case, insertion of materials having an excellent thermal
conductivity such as an aluminum plate at a suitable
interval allows uniform thermal conduction, resulting in
prevention of nonuniformity of crosslinking in lot.
Accordingly, a more uniformly thermally crosslinking can be
carried out by carrying out thermal-crosslinking treatment
with control of thermal conductivity using a combination of

sheets each having a different thermal conductivity.
[0019]
Fig. 1 shows a schematic view of a preferable
embodiment in which thermal crosslinking is simultaneously
carried out on a large number non-crosslinked gelatin films.
In Fig. 1, in a vacuum dryer 1, non-crosslinked gelatin
films 2 and fluorine resin sheets 3 are alternately
laminated in such a manner that the gelatin film 2 is
sandwiched between the two fluorine resin sheets 3.
Moreover, an aluminum plate 4 is disposed on every five
sheets of the fluorine resin sheets 3 to allow heat to be
uniformly conducted as a whole.
The method for producing an anti-adhesion material,
which comprises a step of carrying out thermal-crosslinking
treatment with control of thermal conductivity using a
combination of sheets each having a different thermal
conductivity, is also one aspect of the present invention.
Furthermore, insertion of a sheet-shaped heat source
is also one aspect of the present invention. The above-
mentioned method allows more uniform thermal crosslinking.
[0020]
As the sheet-shaped heat source, examples thereof
include a silicone rubber heater comprising a combination
of a temperature controller and glass fiber reinforced
silicone rubber sheets holding therebetween an electric
heating nickel chrome, a silicone sheet heater, a metal
heater and the like.
Use of these sheet-shaped heat sources as they are,
uses of them alternately laminated with the above-mentioned
aluminum plates, or use of the sheet-shaped heat source
sandwiched between the aluminum plates allows the whole
face of the gelatin film to be heated more uniformly.
[0021]
The above-mentioned thermal crosslinking process is
carried out to obtain the water content calculated by the

following formula (1) of 60 to 85%. The water content can
be used as an indicator reflecting a degree of crosslinking,
and a low water content indicates a high degree of
crosslinking.
Water content (%) = [(Ws-Wd)/Ws] x 100 (%) (1)
In the formula (1), Ws representing a weight (wet
weight) of the anti-adhesion material immersed in a
phosphate buffered saline solution at a temperature of 25°C
for one hour, and Wd representing a weight (dry weight) of
the anti-adhesion material dried completely using a vacuum
drying apparatus.
[0022]
The anti-adhesion material having a water content of
less than 60% has the rubber-like elasticity and an
excellent shape retention property, but is slowly degraded
upon disposed in a living body, possibly resulting in
lowered performance for prevention of an adhesion. The
anti-adhesion material having a water content of more than
85% has a lowered shape retention property, and is quickly
degraded upon disposed in a living body, resulting in loss
of the shape at an early stage. The preferable lower limit
is 65%, and the preferable upper limit is 80%.
In order to obtain an anti-adhesion material having
the water content within this range, conditions for thermal
crosslinking are preferably suitably set approximately as
follows: under a reduced pressure (1 Torr); at a
temperature of 120 to 170°C; and for 30 minutes to 72 hours.
Generally, heat treatment at a high temperature and
heat treatment for a longer time produce a lot of
crosslinking shapes leading to a high degree of
crosslinking. A high degree of crosslinking indicates a
low water content.
Therefore, in order to obtain desired quality,
conditions are suitably set to carry out thermal
crosslinking. Thermal crosslinking at a lower temperature

requires a longer time for crosslinking. On the other hand,
thermal crosslinking at a higher temperature tends to cause
a fragility of the film, thus leading to increased
possibility of fracture in the film.
One example of the more preferable conditions for
thermal crosslinking to obtain the anti-adhesion material
of the present invention is given as follows: at a
temperature of 120 to 150°C; and for 5 to 30 hours.
[0023]
The preferable lower limit of a tensile strength of
the anti-adhesion membrane of the present invention is 1 N,
measured by a method according to JIS L 1912-1997 after
immersion of a sample having a width of 1 cm in a phosphate
buffered saline solution at a temperature of 25°C for one
hour. Practically, an anti-adhesion membrane having a
tensile strength of less than 1 N possibly causes
difficulties in use. Although the upper limit is not
particularly limited, it is difficult to obtain an anti-
adhesion membrane having a tensile strength of more than 10
N. Although a higher degree of crosslinking leads to a
higher strength, an excessively high degree of crosslinking
leads to fragility, resulting in lowering in a degree of
elongation and strength. Moreover, since a lower degree of
crosslinking leads to a lower strength, before sufficiently
being elongated, fracture takes place in an anti-adhesion
membrane.
[0024]
In the anti-adhesion membrane of the present
invention, the preferable lower limit of a deformation
ratio calculated by the following formula (2) is 95%, and
the preferable upper limit thereof is 120%. The
deformation ratio can be used as an indicator reflecting
operationality in use. A deformation ratio deviating more
distantly from 100% indicates more negative handling.
Deformation ratio (%) = (Ss/Sd) x 100 (%) (2)

In the formula (2), Ss representing an area of the
anti-adhesion material immersed in the phosphate buffered
saline solution at a temperature of 25°C for one hour, and
Sd representing an area of the anti-adhesion material
before the immersion. An anti-adhesion material having the
deformation ratio of less than 95 % fails to maintain an
area required to cover an affected part. An anti-adhesion
material having the deformation ratio of more than 120 %
may cause difficulties in operation. (Especially an anti-
adhesion material containing a reinforcing material may
cause difficulties to handle with such as curling up.) The
more preferable lower limit is 100%, and the more
preferable upper limit is 110%.
Here, a high degree of crosslinking leads to a low
deformation ratio.
[0025]
The anti-adhesion membrane of the present invention
may be further reinforced by a reinforcing material made of
a bioabsorbable polymer. Since the reinforcing material
made of a bioabsorbable polymer is biodegraded and absorbed
in a living body, use of a reinforcing material of this
kind for reinforcing the anti-adhesion membrane of the
present invention does not need re-operation and the like,
and allows the anti-adhesion membrane to have a sufficient
strength for preventing itself from damaging due to suture
and the like.
[0026]
Although the bioabsorbable polymer is not
particularly limited, polylactic acid, lactic acid-
caprolactone copolymer, polyglycolic acid and the like are
suitably used, owing to the suitable strength and
degradation.
[0027]
An embodiment of the reinforcing material is not
particularly limited, and examples thereof include a

nonwoven fabric, a textile fabric, a knitted fabric, a
braided rope, a film and the like. In terms of difficulty
in being frayed when being fixed by a suture, a long-staple
nonwoven fabric, a gause fabric, a warp knitted fabric and
the like are suitably used.
[0028]
Hydrophilization treatment may be carried out on the
surface of the reinforcing material. The hydrophilized
surface of the reinforcing material is allowed to more
firmly contact the gelatin film, resulting in less
possibility of detachment of the reinforcing material from
the gelatin film. The above-mentioned hydrophilization
treatment is not particularly limited, and examples thereof
include plasma treatment, glow discharge treatment, corona
discharge treatment, ozonization, surface graft treatment,
coating treatment, chemical treatment, ultraviolet-rays
irradiation treatment and the like.
[0029]
Although an embodiment of the reinforcement by the
reinforcing material is not particularly limited, for
example, preferable examples thereof include an embodiment
in which the reinforcing material is disposed in the
surface and/or the inside of the gelatin film and united
together.
Moreover, a part to be reinforced is not particularly
limited, the whole gelatin film may be reinforced, or only
a part to be sutured and the like may be reinforced.
[0030]
A method for reinforcing by the reinforcing material
is not particularly limited, and examples thereof are given
as follows: a method in which the reinforcing material is
immersed in the gelatin solution casted into a petri dish
and the like, and the obtained reinforcing material
containing the gelatin solution inside thereof was dried
(first method); a method in which the gelatin solution

casted into a perti dish and the like is allowed to
gelatinize, and the reinforcing material is placed on the
gelatin immediately before completion of the gelatinization
and then dried after the completion of the gelatinization
(second method); a method in which a complex of the
reinforcing material and the gelatin film united together
in the second method is immersed in the gelatin solution
with the reinforcing material facing the gelatin solution
(third method); a method in which two glass plates are
preliminarily disposed facing each other to obtain an anti-
adhesion membrane having a predetermined thickness, and
allowed to hold a reinforcing material having a desired
shape therebetween, and then the gelatin solution is casted
between the glass plates, and dried after cooled for
gelatinization (forth method); and the like.
EFFECTS OF THE INVENTION
[0031]
Since the anti-adhesion material of the present
invention comprises a gelatin film that is thermally-
crosslinked to have a certain water content, the anti-
adhesion material has a uniformly degree of crosslinking as
a whole. In addition, compared with an anti-adhesion
material comprising an ultraviolet-crosslinked gelatin film,
the anti-adhesion material of the present invention has a
higher strength, and also a more excellent shape stability
in a living body. Furthermore, compared with an anti-
adhesion material comprising a gelatin film crosslinked
using a chemical crosslinking agent, the anti-adhesion
material of the present invention advantageously have no
possibility of release of a toxic substance having a low
molecular weight.
Particularly, the anti-adhesion material of the
present invention is suitably used for preventing an
adhesion of pericardium. The anti-adhesion material for a

pericardium comprising the anti-adhesion material of the
present invention is also one aspect of the present
invention.
The present invention provides an anti-adhesion
membrane that has no toxicity to a living body, has
flexibility allowing itself to fit an affected part as a
hydrated gel, is uniformly crosslinked, and is immediately
absorbed in a living body after maintaining its shape in
the living body for a certain period of time.
BEST MODE FOR CARRYING OUT THE INVENTION
[0032]
Hereinafter, the present invention will be described
in more detail by way of Examples, but the present
invention is not limited to these Examples.
[0033]
(Example 1)
Gelatin (produced by Nippi, Inc., alkali treated
product derived from swine, weight-average molecular
weight: 132,000, jelly strength: 257 g) was dissolved in
distilled water to obtain a solution containing 5% by
weight of the gelatin. An amount of 13 mL of the obtained
solution was casted into a petri dish (size: 14 cm x 10 cm)
made of polystyrene resin, and air dried as it was to
obtain a non-crosslinked gelatin film having a thickness of
approximately 40 urn.
A laminated body of the non-crosslinked gelatin films
having a thickness of 160 urn was obtained by laminating
four sheets of the non-crosslinked gelatin films. Each of
the non-crosslinked gelatin films forming the laminated
body of the non-crosslinked gelatin film was assigned one
of numbers 1, 2, 3 and 4 in a sequential order from the top.
[0034]
Fluorine resin sheets having a thickness of 1 mm were
disposed on the both faces of the obtained laminated body

of the non-crosslinked gelatin film. In addition, aluminum
plates having a thickness of 3 mm were disposed on the both
faces of the obtained laminated body, and the resulting
laminated body was disposed on a shelf in a vacuum drying
apparatus. In this state, thermal crosslinking was carried
out under a pressure of 1 Torr or less at a temperature of
135°C for 8 hours.
[0035]
(Comparative Example 1)
A laminated body of non-crosslinked gelatin film
obtained by the same method as that of Example 1 was
irradiated with ultraviolet rays from a face of a film 1
for 10 hours at a strength of 0.25 mW/cm2 (15 W
bactericidal lamp, distance: 50 cm) to carry out
ultraviolet-crosslinking.
[0036]
(Comparative Example 2)
A laminated body of non-crosslinked gelatin film
obtained by the same method as that of Example 1 was
irradiated with ultraviolet rays from a face of a film 1 in
the same method as that of Comparative Example 1.
Subsequently, the laminated body is further irradiated with
ultraviolet rays in the same method from a face of a film 4
to carry out ultraviolet ray treatment on the both faces of
the laminated body, (each one face: 10 hours, total
irradiation: 20 hours)
[0037]
(Evaluation)
The water content was measured based on the following
method for each of four gelatin films forming the laminated
body of the gelatin film after crosslinked. That is, each
of the gelatin films was dried in a vacuum drying apparatus
under a reduced pressure of 1 Torr or less at a temperature
of 25°C for approximately 24 hours to measure the dry
weight thereof. On the other hand, each of the gelatin

film was immersed in a phosphate buffered saline solution
having a temperature of 25°C for 1 hour to measure the wet
weight.
The water content was calculated by the above-
mentioned formula (1) using the obtained dry weight and wet
weight.
Table 1 shows the results.
[0038]

[0039]
Table 1 shows that the four gelatin films thermally
crosslinked in Example 1 had almost the same water content.
However, in Comparative Example 1 in which ultraviolet-
crosslinking is carried out, the film located closer to the
face that was not subjected to the direct irradiation with
ultraviolet rays had a higher water content (that is, a low
degree of crosslinking). Furthermore, in Comparative
Example 2 in which ultraviolet-crosslinking is carried out,
the films 2 and 3 had a higher water content (that is, a
lower degree of crosslinking) than that of the films 1 and
4 that were irradiated with ultraviolet rays. In both
Comparative Examples, the obtained films were less
uniformly crosslinked than those obtained by thermal
crosslinking.
The results show distribution of the water contents
every 40 urn in the depth direction of the gelatin films
when thermal crosslink was carried out on the non-

crosslinked gelatin film having a thickness of
approximately 160 µm or ultraviolet-crosslinking was
carried out on only one face or the both faces of the non-
crosslinked gelatin film having a thickness of
approximately 160 µm. That is, thermal crosslinking allows
the gelatin film to be more uniformly crosslinked than
ultraviolet-crosslinking.
[0040]
(Example 2)
Gelatin (produced by Nippi, Inc., alkali treated
product derived from swine, weight-average molecular
weight: 191,000, jelly strength: 255 g) was dissolved in
distilled water to obtain a solution containing 5% by
weight of the gelatin. An amount of 50 mL of the obtained
solution was casted into a petri dish (size: 14 cm x 10 cm)
made of polystyrene resin, and air dried as it was. As a
result, 20 sheets of non-crosslinked gelatin films having a
thickness of approximately 160 µm were obtained.
The non-crosslinked gelatin films were allowed to
leave at rest in a manner shown in Fig. 1 in a vacuum
drying apparatus. That is, gelatin films and fluorine
resin sheets having a thickness of 1 mm were laminated
alternately to form a shape in which the non-crosslinked
gelatin film is sandwiched between two fluorine resin
sheets without failure. Furthermore, an aluminum plate
having a thickness of 3 mm was disposed on every five non-
crosslinked gelatin films.
Here, each of the non-crosslinked gelatin films was
assigned one of numbers of 1, 2, 3 ... 20 in a sequential
order from the bottom.
In this state, thermal crosslinking was carried out
under a pressure of 1 Torr or less at a temperature of
135°C for 8 hours.
[0041]
(Evaluation)

The water content was measured based on the above-
mentioned method for each of four gelatin films 3, 8, 13,
18 selected from the 20 sheets of the crosslinked gelatin
films.
Table 2 shows the results.
[0042]

[0043]
Table 2 shows that the obtained films had almost the
same water content, irrespective of positions of the films
disposed in a vacuum drying apparatus.
[0044]
(Example 3)
Gelatin (produced by Nippi, Inc., alkali treated
product derived from swine, weight-average molecular
weight: 132,000, jelly strength: 257 g) was dissolved in
distilled water to obtain a solution containing 5% by
weight of the gelatin. An amount of 50 mL of the obtained
solution was casted into a petri dish (size: 14 cm x 10 cm)
made of polystyrene resin, and air dried as it was to
obtain a non-crosslinked gelatin film having a thickness of
approximately 160 µm.
Fluorine resin sheets having a thickness of 1 mm were
disposed on the both faces of the obtained laminated body
of the non-crosslinked gelatin film. In addition, aluminum
plates having a thickness of 3 mm were disposed on the both
faces of the obtained laminated body, and the resulting
laminated body was disposed on a shelf in a vacuum drying

apparatus. In this state, thermal crosslinking was carried
out under a pressure of 1 Torr or less at a temperature of
135°C for 8 hours.
[0045]
(Comparative Example 3)
A non-crosslinked gelatin film having a thickness of
approximately 160 µm was produced by the same method as
that of Example 3. The obtained non-crosslinked gelatin
film was irradiated with ultraviolet rays for 10 hours on
each faces at a strength of 0.25 mW/cm2 (15 W bactericidal
lamp, distance: 50 cm) to carry out ultraviolet-
crosslinking on the both faces.
[0046]
(Evaluation)
The evaluation was carried out based on the following
method for each of the anti-adhesion materials produced in
Example 3 and Comparative Example 3.
Table 3 shows the results.
[0047]
(1) Measurement of tensile strength
The measurement was carried out based on a method
according to JIS L 1912-1997. That is, a sample was cut
into a size having a width of 1 cm and a length of 3 cm,
and immersed in a phosphate buffered saline solution having
a temperature of 25°C for 1 hour. Subsequently, after
wiping off excessive water on the surface, the sample was
set in a tensile test machine (Instron 4302 produced by
Instron, Co., Ltd.) with a distance between clamps of 1 cm,
and pulled at a crosshead speed of 100 mm/min to obtain a
stress as the tensile strength upon fracture thereof.
[0048]
(2) Measurement of deformation ratio
A sample is cut into a size of a width of approximate
1 cm and a length of approximate 3 cm, and the sides of the
sample were accurately measured using a slide caliper to

calculate an area Sd. After the sample was immersed in a
phosphate buffered saline solution having a temperature of
25°C for 1 hour, excessive water on the surface is wiped
off, and the sides were again measured accurately using a
slide caliper to calculate an area Ss.
The deformation ratio was calculated by the above-
mentioned formula (2).
[0049]
(3) Measurement of water content
The same method as that of Example 1 was employed for
the measurement.
[0050]
(4) Evaluation of animal experiment
Each of the obtained anti-adhesion materials was cut
into a size of 1 cm x 1.5 cm, and then implanted in an
abdominal cavity of a wistar rat (five-week age). The
evaluation was carried out based on visual observation of
states of the anti-adhesion materials upon incision after a
period of 1, 2, 3, 4, 6 and 8 weeks according to the
following standard.
O: Anti-adhesion material maintained its shape till
four weeks, and disappeared completely in six weeks.
X: Anti-adhesion material lost its shape and almost
disappeared in three weeks.
[0051]

INDUSTRIAL APPLICABILITY
[0052]
The present invention provides an anti-adhesion

membrane that has no toxicity to a living body, has
flexibility allowing itself to fit an affected part as a
hydrated gel, is uniformly crosslinked, and is immediately
absorbed in a living body after maintaining its shape in
the living body for a certain period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053]
Fig. 1 is a schematic view showing a preferable
embodiment in which thermal crosslinking is carried out
simultaneously on a large number of non-crosslinked gelatin
films.
EXPLANATION OF SYMBOLS
[0054]
1 Vacuum drying apparatus
2 Non-crosslinked gelatin film
3 Fluorine resin sheet
4 Aluminum plate

WE CLAIM :
1. A method for producing an anti-adhesion material that is constituted of a thermally crosslinked
gelatin film, and has a water content of 60 to 85% calculated by the following formula :
water content (%) = [(Ws-Wd)AVs] x 100 (%)
in which Ws represents a weight (wet weight) of the anti- adhesion material immersed in a phosphate
buffered saline solution at a temperature of 25°C for one hour, and wd represents a weight (dry weight)
of the anti-adhesion material dried completely using a vacuum drying apparatus,
said method comprising a step of thermal crosslinking under a reduced pressure (1 Torr or
less); at a temperature of 120 to 170°C; and for 30 minutes to 72 hours, of a non-crosslinked gelatin
film, such as herein described, sandwiched between two sheets having the same thermal conductivity,
such as herein described.
2. The method as claimed in Claim 1, wherein the step of thermal crosslinking treatment is
carried out with control of thermal conductivity using a combination of said sheets, each having a
different thermal conductivity.
3. The method as claimed in Claim 1 or 2, wherein a sheet-shaped heat source, such as herein
described, is inserted during thermal crosslinking.
4. The method as claimed in any of the preceding claims, which produces an anti-adhesion
material having a uniform degree of crosslinking in a thickness direction thereof.



ABSTRACT


A METHOD FOR PRODUCING AN ANTI-ADHESION MATERIAL
According to the present invention there is provided a method for producing an anti-adhesion
material that is constituted of a thermally crosslinked gelatin film, and has a water content of 60 to
85% calculated by the following formula :
water content (%) = [(Ws-Wd)/Ws] x 100 (%)
in which Ws represents a weight (wet weight) of the anti- adhesion material immersed in a phosphate
buffered saline solution at a temperature of 25°C for one hour, and wd represents a weight (dry weight)
of the anti-adhesion material dried completely using a vacuum drying apparatus(1), said method
comprising a step of thermal crosslinking under a reduced pressure (1Torr or less); at a temperature of
120 to 170°C; and for 30 minutes to 72 hours, of a non-crosslinked gelatin film(2), sandwiched
between two sheets(3) having the same thermal conductivity.

Documents:

00410-kolnp-2008-abstract.pdf

00410-kolnp-2008-claims.pdf

00410-kolnp-2008-correspondence others.pdf

00410-kolnp-2008-description complete.pdf

00410-kolnp-2008-drawings.pdf

00410-kolnp-2008-form 1.pdf

00410-kolnp-2008-form 3.pdf

00410-kolnp-2008-form 5.pdf

00410-kolnp-2008-gpa.pdf

00410-kolnp-2008-international publication.pdf

00410-kolnp-2008-international search report.pdf

00410-kolnp-2008-pct priority document notification.pdf

00410-kolnp-2008-pct request form.pdf

410-KOLNP-2008-(05-06-2013)-ABSTRACT.pdf

410-KOLNP-2008-(05-06-2013)-CLAIMS.pdf

410-KOLNP-2008-(05-06-2013)-CORRESPONDENCE.pdf

410-KOLNP-2008-(05-06-2013)-DRAWINGS.pdf

410-KOLNP-2008-(05-06-2013)-FORM-1.pdf

410-KOLNP-2008-(05-06-2013)-FORM-2.pdf

410-KOLNP-2008-(05-06-2013)-OTHERS.pdf

410-KOLNP-2008-(05-06-2013)-PETITION UNDER RULE 137.pdf

410-KOLNP-2008-(13-12-2012)-CORRESPONDENCE.pdf

410-KOLNP-2008-(19-06-2012)-CORRESPONDENCE.pdf

410-KOLNP-2008-(19-06-2012)-ENGLISH TRANSLATION.pdf

410-KOLNP-2008-(19-06-2012)-FORM-3.pdf

410-KOLNP-2008-(23-09-2013)-ANNEXURE TO FORM 3.pdf

410-KOLNP-2008-(23-09-2013)-CORRESPONDENCE.pdf

410-KOLNP-2008-(30-04-2013)-ANNEXURE TO FORM 3.pdf

410-KOLNP-2008-(30-04-2013)-CORRESPONDENCE.pdf

410-KOLNP-2008-(30-04-2013)-OTHERS.pdf

410-KOLNP-2008-ANEXURE TO FORM 3.pdf

410-KOLNP-2008-ASSIGNMENT.pdf

410-KOLNP-2008-CORRESPONDENCE 1.3.pdf

410-KOLNP-2008-CORRESPONDENCE OTHERS 1.1.pdf

410-KOLNP-2008-CORRESPONDENCE-1.2.pdf

410-KOLNP-2008-CORRESPONDENCE.pdf

410-KOLNP-2008-EXAMINATION REPORT.pdf

410-KOLNP-2008-FORM 18.pdf

410-KOLNP-2008-FORM 3-1.1.pdf

410-KOLNP-2008-GPA.pdf

410-KOLNP-2008-GRANTED-ABSTRACT.pdf

410-KOLNP-2008-GRANTED-CLAIMS.pdf

410-KOLNP-2008-GRANTED-DESCRIPTION (COMPLETE).pdf

410-KOLNP-2008-GRANTED-DRAWINGS.pdf

410-KOLNP-2008-GRANTED-FORM 1.pdf

410-KOLNP-2008-GRANTED-FORM 2.pdf

410-KOLNP-2008-GRANTED-FORM 3.pdf

410-KOLNP-2008-GRANTED-FORM 5.pdf

410-KOLNP-2008-GRANTED-SPECIFICATION-COMPLETE.pdf

410-KOLNP-2008-INTERNATIONAL PUBLICATION.pdf

410-KOLNP-2008-INTERNATIONAL SEARCH REPORT & OTHERS.pdf

410-KOLNP-2008-OTHERS.pdf

410-KOLNP-2008-PETITION UNDER RULE 137.pdf

410-KOLNP-2008-REPLY TO EXAMINATION REPORT.pdf

410-KOLNP-2008-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

abstract-00410-kolnp-2008.jpg


Patent Number 257972
Indian Patent Application Number 410/KOLNP/2008
PG Journal Number 48/2013
Publication Date 29-Nov-2013
Grant Date 25-Nov-2013
Date of Filing 29-Jan-2008
Name of Patentee GUNZE LIMITED
Applicant Address 1, ZENE, AONO-CHO, AYABE-SHI KYOTO
Inventors:
# Inventor's Name Inventor's Address
1 TAIRA TSUGUYOSHI C/O GUNZE LIMITED RESEARCH & DEVELOPMENT CENTER, 1, ISHIBURO, INOKURASHINMACHI,, AYABE-SHI, KYOTO 6238512
2 MORIKAWA NORIYUKI C/O GUNZE LIMITED RESEARCH & DEVELOPMENT CENTER, 1, ISHIBURO, INOKURASHINMACHI,, AYABE-SHI, KYOTO 6238512
3 OTANI HITOSHI C/O GUNZE LIMITED RESEARCH & DEVELOPMENT CENTER, 1, ISHIBURO, INOKURASHINMACHI,, AYABE-SHI, KYOTO 6238512
4 MATSUDA SHOJIRO C/O GUNZE LIMITED RESEARCH & DEVELOPMENT CENTER, 1, ISHIBURO, INOKURASHINMACHI,, AYABE-SHI, KYOTO 6238512
PCT International Classification Number A61L 31/00
PCT International Application Number PCT/JP2006/315306
PCT International Filing date 2006-08-02
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2005-228641 2005-08-05 Japan