U.S. patent application number 12/333503 was filed with the patent office on 2009-08-06 for elastomer molding for endoscope.
This patent application is currently assigned to OLYMPUS MEDICAL SYSTEMS CORP.. Invention is credited to Hitoshi OGURA, Kenichiro SAITO, Yuuri TAKEUCHI.
Application Number | 20090198021 12/333503 |
Document ID | / |
Family ID | 40668110 |
Filed Date | 2009-08-06 |
United States Patent
Application |
20090198021 |
Kind Code |
A1 |
OGURA; Hitoshi ; et
al. |
August 6, 2009 |
ELASTOMER MOLDING FOR ENDOSCOPE
Abstract
The invention provides a flexible tube for an endoscope, which
is excellent in elasticity (impact resilience), has suitable
flexibility and also has chemical resistance. Disclosed is a
flexible tube for an endoscope including a flexible-tube material
covered thereon with a jacket, wherein the jacket contains two or
more thermoplastic polyester elastomers crosslinked therein.
Inventors: |
OGURA; Hitoshi;
(Higashiyamato-shi, JP) ; SAITO; Kenichiro;
(Hachioji-shi, JP) ; TAKEUCHI; Yuuri;
(Hachioji-shi, JP) |
Correspondence
Address: |
SCULLY SCOTT MURPHY & PRESSER, PC
400 GARDEN CITY PLAZA, SUITE 300
GARDEN CITY
NY
11530
US
|
Assignee: |
OLYMPUS MEDICAL SYSTEMS
CORP.
Tokyo
JP
|
Family ID: |
40668110 |
Appl. No.: |
12/333503 |
Filed: |
December 12, 2008 |
Current U.S.
Class: |
525/418 ;
600/140 |
Current CPC
Class: |
A61B 1/00071 20130101;
A61B 1/005 20130101; A61L 29/049 20130101 |
Class at
Publication: |
525/418 ;
600/140 |
International
Class: |
C08L 67/00 20060101
C08L067/00; A61B 1/005 20060101 A61B001/005 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2008 |
JP |
2008-026669 |
Claims
1. An elastomer molding for an endoscope, comprising two or more
thermoplastic polyester elastomers crosslinked therein.
2. The elastomer molding according to claim 1, wherein a
carbodiimide compound is contained as a crosslinking agent.
3. The elastomer molding according to claim 2, wherein an average
molecular weight of the carbodiimide compound is 30000 or more.
4. The elastomer molding according to claim 2, wherein an average
molecular weight of the carbodiimide compound is 10000 or more.
5. The elastomer molding according to claim 2, wherein an average
molecular weight of the carbodiimide compound is 15000 or more.
6. The elastomer molding according to claim 1, wherein at least one
of the thermoplastic polyester elastomers comprises a hard segment
composed of polybutylene terephthalate.
7. The elastomer molding according to claim 1, wherein the
thermoplastic polyester elastomer is chosen from a thermoplastic
polyester elastomer comprising a hard segment composed of
polybutylene naphthalate and a thermoplastic polyester elastomer
comprising a hard segment composed of polybutylene
terephthalate.
8. The elastomer molding according to claim 1, containing 5 to 25
parts by weight of a plasticizer.
9. The elastomer molding according to claim 8, wherein the
plasticizer is a compound selected from the group consisting of
fatty ester, glycol, glycerin, epoxy and polyester, or a
combination thereof.
10. The elastomer molding according to claim 1, which is formed as
a jacket for covering the surface of a flexible tube for an
endoscope.
11. A flexible tube for an endoscope, which is covered with a
jacket, wherein the jacket is made of the elastomer molding of
claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2008-026669,
filed Feb. 6, 2008, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an elastomer molding and in
particular to an elastomer molding as a flexible tube for an
endoscope.
[0004] 2. Description of the Related Art
[0005] In an endoscope, a flexible elastomer molding is used as a
jacket for flexible tube. Because an endoscope is repeatedly used
and should be cleansed and sterilized every time it is used, the
jacket for a flexible tube should be impermeable to body fluids,
cleaning liquids, antiseptic solutions etc. The jacket for a
flexible tube should have such suitable flexibility and elasticity
as not to impair insertion into the body cavity.
[0006] The conventional jacket for an endoscopic flexible tube has
been formed from a mixed resin of a thermoplastic polyester
elastomer (TPC) and a thermoplastic polyurethane elastomer (TPU) or
a mixed resin of TPU and TPC compounded with soft polyvinyl
chloride (PVC).
[0007] With recent diversification of sterilization techniques,
thermal resistance is also required of the endoscope. However, TPU
is inferior to TPC in thermal resistance, and thus TPU is not
suitable for use where thermal resistance is required, and TPC is
preferably used.
[0008] This TPC is composed of a crystallized hard segment
functioning as a crosslinking site and an uncrystallized soft
segment exhibiting flexibility. TPC comprising polybutylene
naphthalate (PBN) as a hard segment is particularly excellent in
chemical resistance and also shows autoclave resistance (see, for
example, JP-A 2004-141487 [KOKAI]). However, this TPC comprising
PBN as a hard segment is rigid with low flexibility attributable to
its chemical structure and is thus not suitable for use in the tip
of a long endoscope for the large intestine.
[0009] On the other hand, TPC comprising polybutylene terephthalate
(PBT) as a hard segment has sufficient flexibility for use in the
tip of an endoscope. However, TPC comprising PBT has a problem that
it is inferior in chemical resistance to TPC comprising PBN and is
lacking autoclave resistance.
BRIEF SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a flexible
tube for an endoscope, which is excellent in elasticity (impact
resilience), has suitable flexibility and also has chemical
resistance.
[0011] For regulating flexibility and for improving chemical
resistance, the inventors have melt-mixed a thermoplastic polyester
elastomer (TPC) comprising PBN as a hard segment, with TPC
comprising PBT. However, these two TPCs are not completely
compatible with each other because of the difference in their
segments. Accordingly, the resulting mixture showed significant
deterioration in elasticity and could not be satisfactory in
resistance to various chemical solutions, for use as a jacket of a
flexible tube for an endoscope. Hence, the inventors made extensive
study, and as a result, they found that crosslinking of two or more
TPCs is effective, and the present invention was thereby
completed.
[0012] That is, the present invention provides an elastomer molding
for an endoscope, which comprises two or more thermoplastic
polyester elastomers crosslinked therein.
[0013] According to a preferable embodiment of the invention, the
two or more thermoplastic polyester elastomers are crosslinked
using a carbodiimide compound as a crosslinking agent. According to
another preferable embodiment of the invention, the average
molecular weight of the carbodiimide is 10000 or more. According to
another embodiment of the invention, the hard segment of at least
one of the thermoplastic polyester elastomers is polybutylene
terephthalate. According to another embodiment of the invention,
the jacket further contains 5 to 25 parts by weight of
plasticizer.
[0014] According to another embodiment of the invention, there is
also provided the elastomer molding for an endoscope, which is
formed as a jacket for covering the surface of a flexible tube for
an endoscope. According to still another embodiment of the
invention, there is provided a flexible tube for an endoscope,
which is covered with a jacket made of the elastomer molding
described above.
[0015] As described above, TPC comprising PBN is low in flexibility
(rigid). Thus, when TPCs comprising PBN are crosslinked with each
other, the product is made lower in flexibility. Accordingly, at
least one of TPCs is preferably one comprising PBT as a hard
segment.
[0016] TPC can be crosslinked by various methods. A method of
comprising a carbodiimide compound is particularly effective
because the compound can also functions as a hydrolysis-resistant
agent. The carbodiimide used is less liable to exhibit blooming as
the molecular weight increases, thus reducing its eluted amount.
Accordingly, the carbodiimide compound can be preferably used when
the elastomer molding is used for medical purposes. When the
flexibility of the elastomer molding is to be further increased
(softened), a plasticizer may be added. The elastomer molding
according to the present invention has TPC molecules chemically
bound to one another and is thus less liable to exhibit plasticizer
bleeding than a simple mixture of non-crosslinked TPCs.
[0017] The thus constituted elastomer molding of the present
invention and an endoscopic flexible tube using the same are
excellent in elasticity (impact resilience) and have appropriate
flexibility because two kinds of thermoplastic elastomers are
crosslinked with each other. Accordingly, they have an excellent
distinctive feature of excellent insertability to relieve the pain
(burden) of a patient. The elastomer molding of the present
invention and an endoscopic flexible tube using the same are not
only resistant to various cleaning liquids, antiseptic solutions
and low-temperature plasma sterilization but are also excellent in
hydrolysis resistance. Therefore, they can be autoclaved
(sterilization with steam under high pressure) which is useful in
prevention of infection, and can maintain high insertability over a
long period.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0018] FIG. 1 is a sectional view of a flexible tube for an
endoscope according to one embodiment of the present invention;
and
[0019] FIG. 2 is an enlarged view of a part of the flexible tube in
FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Hereinafter, embodiments of the invention will be described
in detail with reference to the drawings. FIG. 1 shows an
endoscopic flexible tube 1 in one embodiment of the present
invention. FIG. 2 is an enlarged view of a part of the endoscopic
flexible tube shown in FIG. 1. As shown in the figure, the
endoscopic flexible tube (hereinafter referred to as a "flexible
tube") 1 is composed of a flexible-tube material 4 and a jacket 6
for covering the periphery thereof. The flexible-tube material 4 is
composed of a spiral tube 2 and a mesh tube 3 for covering the
periphery thereof. The jacket 6 is further coated with a coating
layer 7.
[0021] As the material constituting the spiral tube 2, stainless
steel or a copper alloy can be used. The mesh tube 3 is constituted
by braiding a plurality of metallic or nonmetallic thin lines.
Stainless steel and synthetic resin can be used as materials of
metallic and nonmetallic thin lines, respectively. For improving
adhesion to the jacket, a mixture of metallic and nonmetallic thin
lines is braided in some cases.
[0022] The jacket 6 for covering the periphery of the flexible-tube
material 4 is composed of a resin having two or more TPCs
crosslinked therein. TPCs used in this resin may be various ones
known in the art, and include, for example, Hytrel (manufactured by
Du Pont-Toray Co., Ltd.), Grilux (Dainippon Ink And Chemicals,
Incorporated), Primalloy (manufactured by Mitsubishi Chemical
Corporation), Arnitel (manufactured by DSM), and Pelprene
(manufactured by Toyobo Co., Ltd.).
[0023] Crosslinking of TPCs may be conducted by any method such as
a method of heating in the presence of a crosslinking agent and a
method of irradiation with ionizing radiation such as .gamma.-rays
or an electron beam. A preferably used crosslinking agent includes,
but is not limited to, carbodiimide compounds. Also, conventionally
known crosslinking agents normally used in crosslinking of
elastomers such as epoxylated thermoplastic elastomers can be used
singly or as a combination thereof.
[0024] Many thermoplastic elastomers will, when crosslinked, lose
thermoplasticity. However, their thermoplasticity can be maintained
by appropriately regulating the degree of crosslinkage. When a
carbodiimide compound is used as the crosslinking agent, 0.5 to 5
parts by weight of the carbodiimide compound is preferably added to
TPCs.
[0025] For regulating flexibility, a plasticizer may be added to
TPCs. The plasticizer can be added in an amount of 5 to 25 parts by
weight although its amount is not limited thereto. As the
plasticizer, those known in the art, which are based on fatty
ester, glycol, glycerin, epoxy and polyester, may be used singly or
as a combination thereof.
[0026] Also, TPCs may be compounded if necessary with fillers. The
fillers that can be used include, but are not limited to, inorganic
fillers selected from the group consisting of carbon black, silica,
barium sulfate, titanium oxide, aluminum oxide, calcium carbonate,
calcium silicate, magnesium silicate and aluminum silicate, organic
fillers selected from the group consisting of
polytetrafluoroethylene resin, polyethylene resin, polypropylene
resin, phenol resin, polyimide resin, melamine resin and silicone
resin, and is arbitrary combinations thereof.
[0027] Also, TPCs may optionally be compounded with fibers. The
fibers include, but are not limited to, inorganic fibers selected
from the group consisting of glass fibers, alumina fibers and rock
wool, organic fibers selected from the group consisting of cotton,
wool, silk, hemp, nylon fibers, aramid fibers, vinylon fibers,
polyester fibers, rayon fibers, acetate fibers, phenol-formaldehyde
fibers, polyphenylene sulfide fibers, acrylic fibers, polyvinyl
chloride fibers, polyvinylidene chloride fibers, polyurethane
fibers and tetrafluoroethylene fibers, and arbitrary combinations
thereof.
[0028] Lubricants, stabilizers, weathering stabilizers, ultraviolet
absorbers and antistatic agents can also be added in such a range
that the effect of the present invention is not degraded.
[0029] The TPC of the present invention can be produced by a
variety of conventional methods. Generally, melt-kneading is
carried out with a kneading machine such as a kneader, a Banbury
mixer or a continuous kneading extruder. The kneading temperature
may be an arbitrary temperature as long as it is a temperature at
which the respective components are uniformly dispersed and which
is below the decomposition temperature of TPC and additives.
[0030] When TPCs are crosslinked by irradiation with ionizing
radiations, a co-crosslinking agent is added to two or more TPCs
which are then kneaded by the method described above. Then, the
product can be formed into a flexible tube and irradiated with
ionizing radiations.
EXAMPLES
[0031] Hereinafter, the present invention will be described in more
detail with reference to the Examples.
Examples
[0032] According to the formulation shown in Table 1, two TPCs, a
crosslinking agent, and, optionally, a plasticizer were blended and
kneaded by a continuous kneading extruder to yield an elastomer
molding. The periphery of a core material consisting of a spiral
tube covered with a mesh tube was covered with the resulting
elastomer molding to produce the flexible tube for an endoscope in
each of Examples 1 to 6.
Comparative Examples
[0033] According to the formulations shown in Table 1, the flexible
tubes for an endoscope in Comparative Examples 1 to 4 were prepared
in the same manner as in the Examples above except that no
crosslinking agent was added. In Comparative Example 1, however,
the flexible tube was produced by using TPU as it is.
TABLE-US-00001 TABLE 1 Formulation Table (unit: parts by weight)
Comparative Examples Examples 1 2 3 4 5 6 1 2 3 4 Elastomers
PBN-based TPC-ET A 50 -- -- 75 -- -- -- 50 75 -- PBN-based TPC-ET B
-- -- -- 25 -- -- -- -- 25 -- PBT-based TPC-ET C 50 50 50 -- -- --
-- 50 -- -- PBT-based TPC-ET D -- 50 -- -- -- -- -- -- -- PBT-based
TPC-ET E -- -- 50 -- -- -- -- -- -- -- PBT-based TPC-ET F -- -- --
-- 80 80 -- -- -- 80 PBT-based TPC-ET G -- -- -- -- 20 20 -- -- --
20 TPU H -- -- -- -- -- -- 100 -- -- -- Crosslinking Carbodiimide
Compound I 2 2 -- 2 -- -- -- -- -- -- agents (average molecular
weight: 15000 g/mol) Carbodiimide Compound J -- -- 2 -- 2 1 -- --
-- -- (average molecular weight: 3000 g/mol) Plasticizer Epoxylated
Soybean Oil K -- -- -- -- 15 10 -- -- -- 15 PBT: Polybutylene
terephthalate PBN: Polybutylene naphthalate TPC-ET: TPC with
polyether as soft segment TPU: Polyurethane elastomer
[0034] The flexible tubes in Examples 1 to 6 and Comparative
Examples 1 to 4 were examined for their flexibility, elasticity,
thermal resistance and chemical resistance. In a thermal resistance
test, the sample was heated to 136.degree. C. for 100 hours and
then its molten state was visually judged. In a chemical resistance
test, the sample was left in 3.7% aqueous peracetic acid at
53.degree. C. for 30 days, and then its outward appearance was
visually judged. The test results are shown in Table 2. The
meanings of the symbols in test results are as follows:
.circleincircle., very good; .largecircle., good; .DELTA.,
acceptable; and X, unacceptable.
TABLE-US-00002 TABLE 2 Test results Flexibility Elasticity Thermal
resistance Chemical resistance Special affairs Example 1 .DELTA.
.largecircle. .circleincircle. .largecircle. Superior to
Comparative Example 2 in elasticity Example 2 .largecircle.
.largecircle. .circleincircle. .DELTA. Example 3 .largecircle.
.largecircle. .circleincircle. .DELTA. Example 4 .DELTA.
.largecircle. .circleincircle. .circleincircle. Superior to
Comparative Example 3 in elasticity Example 5 .circleincircle.
.largecircle. .DELTA. .DELTA. Example 6 .circleincircle.
.largecircle. .largecircle. .DELTA. Superior to Comparative Example
4 in elasticity, thermal resistance and chemical resistance No
plasticizer bleeding Comparative .circleincircle. .circleincircle.
X X Example 1 Comparative .DELTA. .DELTA. .circleincircle.
.largecircle. Example 2 Comparative .DELTA. X .circleincircle.
.circleincircle. Example 3 Comparative .circleincircle. .DELTA.
.DELTA. X Plasticizer bleeding Example 4
[0035] As can be seen from Table 2, Example 1 and Comparative
Example 2 are the same in elastomer composition, but Example 1
where a crosslinking agent is contained is superior to Comparative
Example 2 in elasticity. Example 4 where a crosslinking agent is
contained is superior to Comparative Example 3 in elasticity.
Example 6 is superior to Comparative Example 4 in elasticity,
thermal resistance and chemical resistance, and plasticizer
bleeding did not occur. In Comparative Example 4, on the other
hand, plasticizer bleeding occurred.
[0036] As is evident from these test results, Examples 1 to 6
showed results generally excellent in flexibility, elasticity,
thermal resistance and chemical resistance. It was found that the
elastomer molding having two TPCs crosslinked therein has
characteristics superior to those of a mixture having two TPCs
simply mixed therein. It was also demonstrated that plasticizer
bleeding is suppressed by crosslinking TPCs.
[0037] As described above, according to the present invention, an
elastomer molding for an endoscope, which is excellent in
elasticity (impact resilience), has suitable flexibility and also
has thermal resistance and chemical resistance is obtained.
[0038] The invention is not limited to the examples described
above, and can be practiced with various modifications without
departure from the gist of the invention.
[0039] (Additional Notes)
[0040] Additional Note 1: A flexible tube for an endoscope
comprising a flexible tube covered thereon with a jacket, wherein
the jacket comprises two or more thermoplastic polyester elastomers
crosslinked therein.
[0041] Additional Note 2: The flexible tube for an endoscope as
mentioned above, wherein the two or more thermoplastic polyester
elastomers are crosslinked using a carbodiimide compound as a
crosslinking agent.
[0042] Additional Note 3: The flexible tube for an endoscope as
mentioned above, wherein an average-molecular weight of the
carbodiimide is 10000 or more.
[0043] Additional Note 4: The flexible tube for an endoscope as
mentioned above, wherein a hard segment of at least one of the
thermoplastic polyester elastomers is polybutylene
terephthalate.
[0044] Additional Note 5: The flexible tube for an endoscope as
mentioned above, wherein the jacket further comprises 5 to 25 parts
by weight of a plasticizer.
[0045] Additional Note 6: A flexible-tube jacket for an endoscope,
which comprises two or more thermoplastic polyester elastomers
crosslinked therein.
[0046] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *