U.S. patent application number 11/795601 was filed with the patent office on 2008-05-22 for catheter and process for producing the catheter.
This patent application is currently assigned to TERUMO KABUSHIKI KAISHA. Invention is credited to Yukio Imai, Takashi Suzuki.
Application Number | 20080119825 11/795601 |
Document ID | / |
Family ID | 36692332 |
Filed Date | 2008-05-22 |
United States Patent
Application |
20080119825 |
Kind Code |
A1 |
Imai; Yukio ; et
al. |
May 22, 2008 |
Catheter and Process for Producing the Catheter
Abstract
A catheter having a catheter layer composed of a composition
containing ETFE and PTFE in a weight ratio of 99:1 to 45:55,
wherein there is got a luminal internal surface consisting of a
material that exhibits lubricity substantially identical with that
of PTFE and has a resistance to radioactive rays not had by
PTFE.
Inventors: |
Imai; Yukio; (Shizuoka,
JP) ; Suzuki; Takashi; (Shizuoka, JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
TERUMO KABUSHIKI KAISHA
TOKYO
JP
|
Family ID: |
36692332 |
Appl. No.: |
11/795601 |
Filed: |
January 20, 2006 |
PCT Filed: |
January 20, 2006 |
PCT NO: |
PCT/JP06/00805 |
371 Date: |
July 19, 2007 |
Current U.S.
Class: |
604/526 |
Current CPC
Class: |
A61L 29/041 20130101;
A61M 25/0045 20130101; A61M 25/0009 20130101; C08L 27/18 20130101;
A61M 2025/0046 20130101; A61L 29/041 20130101; A61M 2025/0047
20130101 |
Class at
Publication: |
604/526 |
International
Class: |
A61M 25/00 20060101
A61M025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 21, 2005 |
JP |
2005-014081 |
Claims
1. A catheter comprising a catheter layer composed of a composition
containing ETFE and PTFE in a mass ratio of from 99:1 to 45:55.
2. The catheter according to claim 1, wherein said mass ratio is
from 95:5 to 60:40.
3. The catheter according to claim 1, further comprising a resin
layer composed of a resin composition different from said
composition, on said catheter layer.
4. The catheter according to claim 3, further comprising a
reinforcement layer between said catheter layer and said resin
layer.
5. The catheter according to claim 4, wherein said reinforcement
layer is composed of a metallic wire material.
6. The catheter according to claim 1, wherein said catheter layer
constitutes a luminal internal surface of said catheter.
7. A catheter comprising an elongated tube, said elongated tube
having a proximal end section and a distal end section defining a
lumen and a wall, said wall having a tubular cross section
substantially uniform in thickness between said distal end section
and said proximal end section, and said wall being composed of a
composition containing ETFE and PTFE in a mass ratio of from 99:1
to 45:55.
8. A process for producing a catheter comprising the steps of:
mixing ETFE and PTFE in a mass ratio of from 99:1 to 45:55 and
forming the mixture into a tubular body; forming a reinforcement
layer and a resin layer on said tubular body obtained and forming a
catheter; sealingly packaging said catheter; and sterilizing said
packaged catheter with radioactive rays.
9. The catheter according to claim 2, further comprising a resin
layer composed of a resin composition different from said
composition, on said catheter layer.
10. The catheter according to claim 9, wherein said catheter layer
constitutes a luminal internal surface of said catheter.
11. The catheter according to claim 2, wherein said catheter layer
constitutes a luminal internal surface of said catheter.
12. The catheter according to claim 3, wherein said catheter layer
constitutes a luminal internal surface of said catheter.
13. The catheter according to claim 4, wherein said catheter layer
constitutes a luminal internal surface of said catheter.
14. The catheter according to claim 5, wherein said catheter layer
constitutes a luminal internal surface of said catheter.
Description
TECHNICAL FIELD
[0001] The present invention relates to a catheter for medical use
to be used for diagnosis or therapy by being inserted into a blood
vessel or other body lumen, and to a process for producing the
catheter.
BACKGROUND ART
[0002] In recent years, catheters have been being used in an
increasing number of diagnostic and/or therapeutic methods for
alleviating the physical and time-basis burdens on patients.
Generally, for insertion of a catheter into a living body-through a
blood vessel, ureter, trachea, esophagus or the like and bringing
the catheter accurately to a predetermined site in the living body
without damaging the blood vessel wall, organs or the like, the
catheter must meet the structural requirements for high
operationality and safety when serving as a medical device and,
simultaneously, the luminal internal surface of its tube (referred
to also as "catheter body") must exhibit lubricity.
[0003] The lubricity is necessary for externally injecting a liquid
medicine or the like to a predetermined site in the patient's body
through the lumen of the catheter body, for draining a body fluid
in the living body or the like, or for passing other therapeutic
device therethrough.
[0004] As a catheter which meets such structural requirements and
further has lubricity at the luminal internal surface of a catheter
body, for example Patent Document 1 describes a catheter including
a catheter body having an outer layer and an inner layer, the outer
layer having a first region and a second region located on the
proximal end side of the first region, wherein the first region is
composed of a polyester elastomer, and the second region is
composed of a polyurethane elastomer higher in hardness than the
polyester elastomer constituting the first region. This catheter is
excellent in operationality such as pushability, torque
transmitting property, following property, and anti-kinking
property. Besides, in the catheter, a material capable of reducing
the friction of an internal surface of the inner layer, for
example, a fluorinated resin such as polytetrafluoroethylene (PTFE)
is used as the material constituting the inner layer, so that the
luminal internal surface of the catheter body has lubricity.
[0005] There are many examples in which a fluorinated resin,
particularly, PTFE is thus used as the material constituting the
luminal internal surface of the catheter body.
[0006] Meanwhile, a catheter must be sterilized before used, since
it is used for a living body, like other medical devices. General
sterilization methods include the methods in which a gas or water
vapor is used. These methods, however, have problems as to the
toxicity of the gas, the long treatment time required for
sterilization, etc.
[0007] In view of these problems, the sterilizing method using
radioactive rays such as electron beams have come to be paid
attention to. According to this method, toxicity is obviated and
the treatment time required for sterilization is short.
[0008] However, the sterilization method using radioactive rays
cannot be applied to the above-mentioned catheters using PTFE.
[0009] This is because PTFE is deteriorated when irradiated with
ionizing radiations of not less than 1 kGy, and is extremely
deteriorated in mechanical properties at an absorbed dose of around
25 kGy, which is a sterilizing dose generally used in the cases of
sterilization with .gamma.-rays, electron beams and the like.
[0010] For example, when the radioactive-ray sterilization is
applied to the catheter described in Patent Document 1 in which
PTFE is used to form the inner layer, PTFE is conspicuously lowered
in breaking elongation and, therefore, mere bending of the catheter
body would result in exfoliation or cracking of the inner
layer.
[0011] Patent Document 1: Japanese Patent Laid-open No.
2001-190681
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
[0012] It is an object of the present invention to provide a
catheter including a catheter layer having a luminal internal
surface consisting of a material that has lubricity substantially
identical with that of PTFE and has a resistance to radioactive
rays not had by PTFE, and a process for producing the catheter.
Means for Solving the Problems
[0013] The above object is attained according to the present
invention which resides in the following (1) to (12).
[0014] (1) A catheter including a catheter body composed of a
composition containing ETFE (ethylene-tetrafluoroethylene
copolymer) and PTFE (polytetrafluoroethylene) in a mass ratio of
from 99:1 to 45:55.
[0015] (2) The catheter according to (1) above, wherein the mass
ratio is from 95:5 to 60:40.
[0016] (3) The catheter according to (1) or (2) above, further
including a resin layer composed of a resin composition different
from the composition, on the catheter body.
[0017] (4) The catheter according to (3) above, further including a
reinforcement layer between the catheter body and the resin
layer.
[0018] (5) A catheter including a catheter layer composed of a
composition containing ETFE (ethylene-tetrafluoroethylene
copolymer) and PTFE (polytetrafluoroethylene) in a mass ratio of
from 99:1 to 45:55.
[0019] (6) The catheter according to (5) above, wherein the mass
ratio is from 95:5 to 60:40.
[0020] (7) The catheter according to (5) or (6) above, further
including a resin layer composed of a resin composition different
from the composition, on the catheter layer.
[0021] (8) The catheter according to (7) above, further including a
reinforcement layer between the catheter layer and the resin
layer.
[0022] (9) The catheter according to (4) or (8) above, wherein the
reinforcement layer is composed of a metallic wire material.
[0023] (10) The catheter according to any of (1) to (9) above,
wherein the catheter layer constitutes a luminal internal surface
of the catheter.
[0024] (11) A catheter comprising an elongated tube, said elongated
tube having a proximal end section and a distal end section
defining a lumen and a wall, said wall having a tubular cross
section substantially uniform in thickness between said distal end
section and said proximal end section, and said wall being composed
of a composition containing ETFE and PTFE in a mass ratio of from
99:1 to 45:55.
[0025] (12) A process for producing a catheter including the steps
of:
[0026] mixing ETFE and PTFE in a mass ratio of from 99:1 to 45:55
and forming the mixture into a tubular body;
[0027] forming a reinforcement layer and a resin layer on the
tubular body obtained and forming a catheter;
[0028] sealingly packaging the catheter; and
[0029] sterilizing the packaged catheter with radioactive rays.
EFFECTS OF THE INVENTION
[0030] The luminal internal surface of the catheter according to
the present invention has a lubrication characteristic
substantially identical with that of PTFE. Therefore, the use of
the catheter according to the present invention makes it possible
to easily carry out injection externally a liquid medicine or the
like to a predetermined site in a patient's body through the lumen
of the catheter body, drainage of a body fluid or the like present
in the living body, and passage of other therapeutic devices
therethrough. In addition, the luminal internal surface of the
catheter according to the present invention is composed of a
material having a resistance to radioactive rays not had by PTFE.
Therefore, a sterilizing method using radioactive rays, which
obviates toxicity and ensures that the treatment time required for
sterilization is short, can be applied to the catheter according to
the present invention.
BRIEF DESCRIPTION OF DRAWINGS
[0031] [FIG. 1]
[0032] FIG. 1 illustrates an embodiment of overall configuration in
the case where the catheter according to the present invention is
applied to a blood vessel catheter.
[0033] [FIG. 2]
[0034] FIG. 2 is a diagram showing the relationship between PTFE
blending proportion and tensile strengths before and after
irradiation with electron beams.
[0035] [FIG. 3]
[0036] FIG. 3 is a diagram showing the relationship between PTFE
blending proportion and the retention of tensile strength before
and after irradiation with electron beams.
[0037] [FIG. 4]
[0038] FIG. 4 is a schematic illustration of a measuring instrument
for friction test of a material forming the catheter body
pertaining to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0039] Now, the catheter according to the present invention will be
described, based on preferred embodiments thereof shown in the
accompanying drawings.
[0040] FIG. 1 is a plan view showing an example of overall
configuration in the case where the catheter of the present
invention is applied to a blood vessel catheter. A tip section
which is inserted in a lumen such as a blood vessel is shown in
section. Hereinafter, the right side in FIG. 1 will be referred to
as "the proximal end", and the left side as "the distal end".
[0041] The catheter 1 shown in FIG. 1 is composed of a catheter
body 2, a hub 4 mounted to the proximal end 21 of the catheter body
2, and an anti-kinking protector 41.
[0042] The catheter body 2 is formed with a lumen (i.e., inner
cavity) 3 in the inside thereof ranging from the proximal end 21 to
the distal end 22. At the time of inserting the catheter 1 into a
blood vessel, a guide wire is inserted in the lumen 3. In addition,
the lumen 3 can be used also as a passage for a liquid medicine or
the like.
[0043] The hub 4 functions as an insertion port for inserting the
guide wire into the lumen 3, an injection port for injecting a
liquid medicine or the like into the lumen 3, and the like, and
functions also as a grip section to be gripped at the time of
operating the catheter 1.
[0044] The overall length of the catheter body, the thickness of
the tube wall and the like in the catheter according to the present
invention are not particularly limited, and can be appropriately
selected according to the purpose of use of the catheter.
[0045] For example, in the case of the catheter 1 which is a
preferable embodiment of the present invention shown in FIG. 1, the
overall length of the catheter body (tube) is 800 to 1500 mm, and
the thickness of the tube wall is 0.02 to 0.5 mm.
[0046] As for the hub 4, common hubs can be used.
[0047] In the above-mentioned catheter according to the present
invention, the catheter body has a catheter layer composed of a
composition containing ETFE and PTFE in a mass ratio of from 99:1
to 45:55 (the composition hereinafter referred to also as "the
composition in the present invention").
[0048] The ETFE used in the present invention is not particularly
limited, and may be any of those conventionally used widely in the
production of medical devices such as catheters. The ETFE can be
prepared by copolymerizing TFE (tetrafluoroethylene) with ethylene
by a conventionally known method.
[0049] The TFE/ethylene polymer composition of the ETFE used in the
present invention is not particularly limited. In addition, the
ETFE may contain a small amount of a third ingredient in such a
range as not to spoil the characteristics aimed at in the invention
in addition to TFE and ethylene in the composition.
[0050] In the ETFE generally widely utilized, the TFE/ethylene
polymer composition is from about 50/50 to 60/40 mol %, and the
ETFE is substantially an alternate copolymer. Besides, for solving
the generation of stress cracking based on its crystallinity, the
ETFE contains a third ingredient as follows. Namely, the ETFE
generally widely utilized is a ternary copolymer containing the
third ingredient. Furthermore, the ETFE has an MFR (melt flow rate:
fluidity in a molten state) of 3 to 45 g/10 min, and a density of
1.70 to 1.75 g/cm.sup.3.
[0051] In the present invention, the ETFE thus generally utilized
widely can be preferably used.
[0052] Examples of the third ingredient includes fluorinated
.alpha.-monoolefin, fluorinated vinyl ether, hydrofluorocarbon
fluorinated vinyl ether, hydrocarbon fluorinated vinyl ether
monomer, and vinyl esters.
[0053] The PTFE used in the present invention is not particularly
limited, and may be any of those conventionally used widely in the
production of medical devices such as catheters. The PTFE can be
prepared by polymerizing the TFE (tetrafluoroethylene) monomer by a
conventionally known method.
[0054] The PTFE has a melt viscosity of 5,000 to 100,000 poise, and
a density of 2.13 to 2.22 g/cm.sup.3.
[0055] The forms of the ETFE and the PTFE used in the present
invention are not particularly limited, but these materials are
each preferably in a pellet form or a powdery form (a dry powder or
a dispersion (a uniform dispersion of a fine powder in a solvent)).
It is preferable that the ETFE and/or the PTFE is in a pellet form
or a powdery form, since they can be easily mixed with each
other.
[0056] In addition, where the ETFE and/or the PTFE is in the form
of a dispersion, a further homogeneous dispersed state of finer
PTFE particles can be obtained, which is preferable from the
viewpoint of the possibility that a catheter with a smaller tube
wall thickness (1 to 40 .mu.m) can be easily obtained. Dry powdery
ETFE and PTFE are commercially available as molding powders and
fine powders, and these powders can be preferably used in the
present invention.
[0057] In the catheter layer of the catheter according to the
present invention, a composition containing the ETFE and the PTFE
in a mass ratio of from 99:1 to 45:55, preferably from 95:5 to
60:40, more preferably from 90:10 to 80:20 is applied as the
material.
[0058] The relationship between the mixing ratio of the ETFE with
the PTFE and the resistance to radioactive rays is considered to
depend on which of the ETFE and the PTFE forms the sea phase in the
sea-island structure upon mixing of the ETFE with the PTFE.
Specifically, it is considered that the resistance to radioactive
rays is exhibited with priority in the case where the ETFE having a
resistance to radioactive rays has a greater volumetric ratio than
the PTFE having a higher lubricity; it means that the ETFE forms
the sea phase.
[0059] The luminal internal surface of the catheter body produced
from the composition in the present invention containing the ETFE
and the PTFE in the above-mentioned ratio exhibits a high
resistance to radioactive rays without loosing the general
lubricity characteristic.
[0060] Therefore, the use of the catheter according to the present
invention makes it possible to easily carry out external injection
of a liquid medicine or the like to a predetermined site in a
patient's body through the lumen of the catheter body, drainage of
a humor or the like present in the living body, and passage of
other medical devices therethrough. In addition, a sterilizing
method using radioactive rays which obviates toxicity and ensures
that the treatment time required for sterilization is short can be
applied to the catheter according to the present invention.
[0061] Incidentally, the radioactive rays herein includes
.gamma.-rays, electron beams, X-rays and the like, and is not
particularly limited, insofar as the rays can be used for
sterilization of medical devices.
[0062] The irradiating temperature and the irradiation dose of the
rays are not limited, and may be at the levels which are commonly
applied in sterilization of medical devices. For example, the
atmosphere for irradiation is room temperature (about 23.degree.
C.), and the irradiation dose is 1 to 100 kGy, preferably 15 to 60
kGy.
[0063] In addition, the mass ratio of the ETFE to the PTFE is
within from 99:1 to 55:45, more preferably from 95:5 to 70:30 in
the composition in the present invention such that the composition
in the present invention has a fluidity optimal for injection
molding and extrusion molding and is excellent in
processibility.
[0064] Besides, the composition in the present invention may
contain other organic material(s), in addition to the ETFE and the
PTFE.
[0065] Examples of the organic material(s) include polystyrene,
polyethylene, polyamide, polyimide, polysulfone, polyphenylene
sulfide, polyvinyl chloride, polycarbonate, acrylonitrile-styrene
copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl,
silicone, tetrafluoroethylene-hexafluoropropylene copolymer,
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer,
polyvinylidene fluoride, polyvinyl fluoride, and
ethylene-chlorotrifluoroethylene copolymer.
[0066] The composition in the present invention may contain the
organic material(s) in a proportion of 0.1 to 10 mass % based on
the total mass of the ETFE and the PTFE.
[0067] Besides, the composition in the present invention may
contain additives, in addition to the ETFE and the PTFE.
[0068] Examples of the additives include pigments, dyes, X-rays
contrast agent (barium sulfate, tungsten, bismuth oxide or the
like), reinforcing agent (glass fiber, carbon fiber, talc, mica,
clay mineral, potassium titanate fiber, or the like), filler
(carbon black, silica, alumina, titanium oxide, metal powder, wood
flour, rice hull, or the like), thermal stabilizer,
oxidation/deterioration inhibitor, UV absorber, lubricant, mold
release agent, crystalline nucleophile, plasticizer, flame
retardant, antistatic agent, and foaming agent.
[0069] The composition in the present invention may contain the
additive(s) in a proportion of 1 to 50 mass % based on the total
mass of the ETFE and the PTFE.
[0070] The catheter layer of the catheter body of the catheter
according to the present invention is produced from the
above-mentioned composition in the present invention by a method
which will be described later.
[0071] The catheter according to the present invention may have the
catheter layer serving alone as the catheter body; however, it is
preferable for the catheter to have a resin layer composed of a
resin composition different from the composition in the present
invention on the catheter layer. This ensures effectively that the
rigidity of the catheter body is enhanced, and the pushability and
torque transmitting performance of the catheter body are
enhanced.
[0072] In addition, when the catheter body in the present invention
has such as the resin layer constituting an outer layer, it is
effectively ensured that the reinforcement layer to be described
later can be firmly fixed within the catheter body.
[0073] The resin composition constituting the resin layer is not
particularly limited, but it is preferably a resin composition more
flexible than the catheter layer (i.e., inner layer). Examples of
the resin composition include polyamide resin, polybutylene
terephthalate, polyester elastomer, polyethylene terephthalate, and
mixtures and copolymers thereof. Among these resin compositions,
preferred are polyamide resin and polyester elastomer, in view of
their excellent resistance to radioactive rays and little lowering
in mechanical properties upon irradiation with radioactive
rays.
[0074] Examples of the polyamide resin include nylon 6, nylon 66,
nylon 610, nylon 46, nylon 9, nylon 11, nylon 12, and nylon 12
elastomer. Among these polyamide resins, preferred are nylon 12 and
nylon 12 elastomer, in view of their excellent flexibility and
chemical resistance.
[0075] The thickness of the resin layer is not particularly
limited. Usually, the thickness is preferably about 0.01 to 1.0 mm,
more preferably about 0.03 to 0.1 mm.
[0076] The resin layer can be formed on the catheter layer in the
present invention, by a method which will be described later.
[0077] Further, it is preferable to provide a reinforcement layer
between the catheter layer and the resin layer. This ensures
effectively that the rigidity of the catheter body is further
enhanced, and the pushability and torque transmitting performance
of the catheter body are further enhanced.
[0078] The reinforcement layer is composed, for example, a spiral
element.
[0079] The spiral element may be composed of at least one of a
metallic member and a nonmetallic member. Examples of the spiral
element include those obtained by forming a metallic wire or plate
member into a spiral shape, those obtained by forming a nonmetallic
string or plate member into a spiral shape, and those obtained by
forming a laminate of a metallic member and a nonmetallic member
into a spiral shape.
[0080] Examples of the material constituting the metallic member
include stainless steels, nickel-titanium alloys, platinum,
iridium, and tungsten, which may be used either singly or in
combination of two or more of them.
[0081] On the other hand, examples of the material constituting the
nonmetallic member include carbon, polyamide, polyethylene
terephthalate, and polybutylene terephthalate, which may be used
either singly or in combination of two or more of them.
[0082] The pitch of winding of the spiral element is not
particularly limited. For example, the pitch is preferably about 0
to 2 mm, more preferably about 0.02 to 0.5 mm. Where the pitch of
winding of the spiral element is in such a range, an appropriate
rigidity is imparted to the catheter body, and the pushability and
torque transmitting performance of the catheter body are further
enhanced.
[0083] In addition, the cross-sectional shape of the spiral element
is not limited to circle, and may be a flat shape; namely, the
spiral element may be ribbon-like (i.e., belt-like) in shape.
[0084] Where the cross-sectional shape of the spiral element is a
circle, the diameter of the circle is preferably about 0.03 to 0.06
mm, more preferably about 0.04 to 0.05 mm.
[0085] Where the spiral element is ribbon-like in shape, the width
of the ribbon-like shape is preferably about 0.1 to 1.0 mm, and the
thickness is preferably about 0.04 to 0.05 mm.
[0086] Incidentally, the reinforcement layer is not particularly
limited, insofar as it can impart an appropriate rigidity to the
catheter body. For example, the reinforcement layer may be composed
of the spiral element alone, a braided element alone, or a
combination of a braided element and the spiral element (for
example, one which is composed of a braided element on the proximal
end side and of the spiral element on the tip side, one which is a
laminate of a braided element and the spiral element, or the
like).
[0087] Where a braided element is used, the braided element may be
composed of at least one of a metallic member and a nonmetallic
member. Examples of the braided element include those obtained by
braiding metallic wires alone, those obtained by braiding
nonmetallic strings alone, and those obtained by braiding a
metallic wire with a nonmetallic string.
[0088] Examples of the material constituting the metallic wire
include stainless steels and nickel-titanium alloys, or the like,
which may be used either singly or in combination of two or more of
them.
[0089] On the other hand, examples of the material constituting the
nonmetallic string include carbon, polyamide, polyethylene
terephthalate, and polybutylene terephthalate, which may be used
either singly or in combination of two or more of them.
[0090] The reinforcement layer composed of such a spiral element or
braided element provides a sufficient reinforcing effect even when
comparatively small in thickness. Therefore, the catheter body
having such a reinforcement layer is advantageous in adopting a
smaller diameter.
[0091] In the present invention, the catheter layer is produced by
using the composition containing the ETFE and the PTFE and,
optionally, the organic material(s) and/or the additive(s).
[0092] The process for producing the catheter layer is not
particularly limited; for example, the catheter layer is produced
by the following process.
[0093] After the pellet form or powdery form ETFE and the powdery
PTFE are mixed under stirring, the mixture is fed into a melt
extruder, and is stirred at a temperature of 230 to 280.degree. C.
The stirred mixture is extruded by the extruder onto a mandrel to
form a coating film, which is subjected to baking together with the
mandrel in a furnace. The baking temperature should be not lower
than the melting point of ETFE, namely, not lower than 220.degree.
C. In addition, the baking temperature is preferably not higher
than 330.degree. C., which is the melting point of PTFE, and is
preferably not higher than 250.degree. C.
[0094] Then, the mandrel is drawn out, whereby a round tubular
molded article can be obtained as the catheter layer in the present
invention.
[0095] Here, when a small amount of a volatile oil (kerosene or the
like) is added at the time of mixing the ETFE and the PTFE under
stirring, a lumpy composition can be obtained by compressing the
stirred composition, which is preferable since the supply of the
composition into the extruder and the coating of the mandrel with
the composition are stabilized.
[0096] The catheter layer produced by such a process as above can
be used alone as the catheter body. However, in the case where the
reinforcement layer is further formed on the catheter layer, the
above-mentioned metallic wire or nonmetallic string is wound
therearound at the above-mentioned pitch at a time after the
coating of the mandrel with the composition in the present
invention by the above-mentioned process and before the baking in a
furnace or at a time after the baking in the furnace and before the
detaching of the coating film from the mandrel. In the case where
the winding is conducted before the baking, the baking is conducted
after the winding.
[0097] In the case where the resin layer is further formed on the
catheter layer produced by the above process or on the
reinforcement layer formed as above-mentioned, the composition in
the present invention is coated on the mandrel by the
above-mentioned process, baked in a furnace, and the reinforcement
layer is formed on it. Thereafter, a resin composition as a
material for forming the resin layer is applied on the
reinforcement layer by use of a melt extruder. Incidentally, the
baking may be conducted after the reinforcement layer is formed. In
addition, the baking step may be omitted.
[0098] Alternatively, a hollow tube is preliminarily formed by
extrusion molding using the resin composition prepared as the
material for forming the resin layer. Then, the hollow tube is
covered with on the thing which composed with the mandrel coated
with the composition in the present invention by the
above-mentioned process and the reinforcement layer formed on it.
Then, a heat-shrinkable tube composed of a fluorinated resin (e.g.,
FEP) is fitted over the hollow tube, and the assembly is passed
through a heat tunnel (about 340.degree. C.) over a predetermined
time (about 10 min), whereby the catheter layer formed of the
composition in the present invention, the reinforcement layer, and
the resin layer are adhered to each other. Thereafter, the
heat-shrinkable tube is peeled off, and the mandrel is drawn out,
whereby the catheter body in the present invention having the
reinforcement layer and the resin layer can be produced.
[0099] A hub and an anti-kinking protector are attached by an
ordinary method to the catheter body produced by the
above-mentioned process, whereby the catheter according to the
present invention can be configured. Further, the catheter is
sealed with a packaging material having a barrier property with
respect to bacteria, followed by radiation sterilization
(preferably, electron-beam sterilization), to complete the
production of the catheter according to the present invention.
[0100] By use of the producing process according to the present
invention, it is possible to obtain a catheter composed of a
material which has lubricity substantially identical with that of
PTFE while having a resistance to radioactive rays not had by PTFE.
Therefore, it is possible to produce a catheter having been
subjected to a radiation sterilizing treatment which obviates
toxicity and ensures that the treatment time required for
sterilization is short.
[0101] In addition, the use of the catheter in the present
invention is not particularly limited. For example, the catheter of
the present invention can be applied to guiding catheters,
angiographic catheters, various balloon catheters for PTCA, PTA,
IABP, etc., ultrasonic catheters, atherectomy catheters, endoscopic
catheters, indwelling catheters, medical solution injection
catheters, and embolism catheters (micro catheters) introduced into
an organ such as brain, liver, etc.
EXAMPLES
[0102] Now, specific examples of the present invention and the
results of various tests will be described below.
[0103] <Production of Catheter Body>
[0104] Catheter bodies corresponding to Examples of the present
invention and Comparative Examples were produced by the method
described below.
[0105] First, ETFE and PTFE powders were mixed for a sufficient
time in each of the mass ratios given in Table 1 below, to obtain
uniform mixtures. Thereafter, the mixed powders were supplied into
a melt extruder so that the compositions in the present invention
in a molten state are propared. The melting temperature was
250.degree. C.
[0106] A copper wire (circular in section with 0.65 mm diameter) as
a mandrel was mounted into the melt extruder, and melt extrusion at
a controlled extrusion rate was conducted, to form a 0.04 mm-thick
coating of the composition on the mandrel.
[0107] The coated mandrel with the composition was fed continuously
into a furnace (referred to a "continuous furnace"). The
temperature in the continuous furnace was controlled to 225.degree.
C. The baking time in the continuous furnace was about five
minutes.
[0108] Then, after cooling at room temperature, the mandrel was
drawn out, to obtain a catheter body composed solely of a catheter
layer in the present invention. The catheter bodies thus obtained
had an overall length of about 1,000 mm, a tubular section, an
inside diameter of 0.65 mm, and an outside diameter of 0.73 mm.
[0109] <Tensile Test>
[0110] From each of the catheter bodies having an overall length of
about 1,000 mm produced by the above method, a specimen of about 80
mm in length was carved out, and was irradiated with electron beams
by use of an electron beam irradiation system (Rhodotron T-300
model, produced by IBA located in Belgium) so that the absorbed
dose would be 33 kGy.
[0111] Thereafter, the specimens were held at room temperature
(23.+-.3.degree. C., 50% RH) for four weeks, and then they were
subjected to a tensile test (according to JIS K7113). Here, the
tensile test speed was 100 mm/min, and the chuck-to-chuck distance
was 50 mm.
[0112] The measurement results of tensile strength by the tensile
test are shown in Table 1, and the measurement results of breaking
elongation are given in Table 2. Incidentally, the results of
measurement for specimens not irradiated with electron beams are
also shown. Furthermore, the results given in Table 1 are shown
also in FIGS. 2 and 3.
TABLE-US-00001 TABLE 1 Tensile strength Tensile strength (B)
Retention ratio Composition (A) before after irradiation of tensile
(mass %) irradiation with electron beams strength (B/A) ETFE PTFE
(gf) (gf) (%) 100 0 959 872 91 90 10 557 521 94 85 15 488 452 93 80
20 358 341 95 60 40 370 311 84 50 50 420 195 47 44 56 430 187 43 40
60 480 161 34 20 80 540 122 23 0 100 634 104 16
TABLE-US-00002 TABLE 2 Breaking elongation Breaking elongation
Retention Composition (A) before (B) after irradiation ratio of
(mass %) irradiation with electron beams toughness ETFE PTFE (%)
(%) (B/A) (%) 100 0 253 261 100 90 10 439 435 99 85 15 142 150 100
80 20 58 56 97 0 100 620 4 0.6
[0113] From FIGS. 2 and 3, it is seen that where the ratio of PTFE
is not less than 40 mass %, a conspicuous difference in tensile
strength is generated between the case of irradiation with electron
beams and the case of not conducting the irradiation.
[0114] The reason is considered to be as follows. As has been
above-mentioned, where ETFE is present in an amount of not less
than 45 mass %, the ETFE forms the sea phase, whereby the
deterioration of strength by irradiation with electron beams can be
suppressed. Where ETFE is present in an amount of about 45 to 60
mass %, the effect of the present invention may partly not be
exhibited. On the other hand, where the ETFE is present in an
amount of not less than 60 mass % (namely, where PTFE is present in
an amount of less than 40 mass %), the effect on the whole is
exhibited sufficiently.
[0115] The shaft strength of the distal section was also measured
by a method similar to that for the tensile test. The shaft
strength of the distal section means the tensile strength of a
flexible part in the range of about 100 mm from the distal end of
the catheter.
[0116] Incidentally, as the catheter body, two compositions were
respectively used, one corresponding to ETFE/PTFE=80/20, and the
other corresponding to ETFE/PTFE=0/100. For each of these
compositions, a specimen irradiated with electron beams and a
non-irradiated specimen were subjected to the test, for
comparison.
[0117] The results of the test are shown in Table 3.
TABLE-US-00003 TABLE 3 Shaft strength Retention Composition of the
ratio of (mass %) Irradiation with distal section strength ETFE
PTFE electron beams (gf) (%) 80 20 Non-irradiated 517 89.2
Irradiated 461 0 100 Non-irradiated 831 23.6 Irradiated 196
[0118] The retention ratio of the shaft strength of the distal
section (the ratio of the shaft strength of the electron
beam-irradiated specimen to that of the non-irradiated specimen) in
the case of ETFE/PTFE=80/20 was about 90%, which is apparently
advantageous over the case of ETFE/PTFE=0/100.
[0119] <Accelerated Ageing Test>
[0120] In the same manner as in the above tensile test, an about 80
mm clipped specimen was got from the main body of the catheter
which produced about 1,000 mm full length by the process mentioned
above, and it was irradiated with electron beams by use of an
electron beam irradiating system (Rhodotron T-300 model, produced
by IBA located in Belgium) so that the absorbed dose would be 33
kGy.
[0121] Then, each of the specimens was put in a warm air
circulation type oven (product code: STAC P-500M, produced by
Shimadzu Corporation) for 168 hours. The temperature inside the
oven was set to 60.degree. C.
[0122] Thereafter, each of the specimens was cooled at room
temperature (23.+-.3.degree. C., 50RH) for 24 hours, and then
subjected to the same tensile test as above.
[0123] The results are shown in Table 4.
TABLE-US-00004 TABLE 4 Tensile strength Breaking elongation
Composition after irradiation after irradiation (mass %) with
electron beams with electron beams ETFE PTFE (gf) (%) 100 0 850.8
265 90 10 515.5 408 85 15 452.6 148 80 20 321.6 46
[0124] <Lubricity Test>
[0125] The catheter bodies according to the present invention
produced by the above process were subjected to measurement of
frictional resistance (i.e., coefficient of static friction and
coefficient of dynamic friction), by the following method. FIG. 4
shows a schematic illustration of the measurement.
[0126] Each of the catheter bodies having an overall length of
about 1,000 mm produced by the above-mentioned process was pressed
down in a diametral direction to form a rectangular parallelepiped
piece of about 500 mm.times.1.2 mm.times.0.08 mm, which was used as
a specimen 10.
[0127] The specimen 10 is mounted on a smooth table 12 (made of
SUS304) having a sufficiently large area and kept horizontal, a
PTFE sheet 14 (30.times.30 mm, 0.5 mm thickness) is mounted on the
specimen 10, and a 200-g weight 16 is mounted on the PTFE sheet 14.
Here, the weight 16 is put on the PTFE sheet 14 without protruding
from the area of the PTFE sheet 14, and a contact area between the
PTFE sheet 14 and the specimen 10 is about 36 mm.sup.2. In
addition, a contact area (i.e., sliding area) between the specimen
10 and the smooth table 12 is also about 36 mm.sup.2.
[0128] Then, the specimen is pulled horizontally at a fixed rate of
100 mm/min by use of a testing machine (Autograph AG-IS, produced
by Shimadzu Corporation) capable of measuring tensile load.
[0129] Here, the coefficient of static friction was calculated from
the tensile load immediately before the specimen 10 started moving.
Besides, the coefficient of dynamic friction was calculated from
the tensile load measured as a fixed value after the specimen 10
started moving.
[0130] The results of the test are shown in Table 5.
TABLE-US-00005 TABLE 5 Composition Coefficient of Coefficient of
(mass %) static friction dynamic friction ETFE PTFE (F/W) (F/W) 100
0 0.220 0.192 90 10 0.257 0.235 85 15 0.355 0.308 80 20 0.435 0.380
0 100 0.640 0.400 F: Measured load, W: Press-down load
[0131] <Internal Surface Sliding Test>
[0132] Each of the catheter bodies having an overall length of
1,000 mm produced by the above-mentioned process was fixed in a U
shape. Here, the curved portion of the U shape had an overall
length of 160 mm and a radius of curvature of 50 mm.
[0133] A diagnostic guide wire (commercial name: Radifocus
Guidewire, produced by TERUMO CORPORATION) or a spring type guide
wire (produced by ASAHI INTECC CO., LTD.) was inserted into the
lumen of the catheter body from its one end.
[0134] Then, the guide wire was fixed at its end part to a chuck of
the same tensile testing machine as used above and reciprocatory
slid. Accordingly, the internal surface sliding resistance was
measured.
[0135] The results are shown in Table 6.
TABLE-US-00006 TABLE 6 Internal surface Composition sliding
resistance (mass %) Irradiation with (gf) ETFE PTFE electron beams
vs. GW *.sup.1 vs. SW *.sup.2 80 20 Non-irradiated 4.68 5.58
Irradiated 4.80 5.38 0 100 Non-irradiated 4.76 8.12 Irradiated 5.00
12.50 *.sup.1 Diagnostic guide wire *.sup.2 Spring type guide
wire
[0136] It was found that the catheter body with ETFE/PTFE=80/20
according to the present invention has an internal surface sliding
property of comparable to or better than that of a catheter body
with ETFE/PTFE 0/100.
* * * * *