U.S. patent application number 14/001093 was filed with the patent office on 2013-12-12 for silicone rubber-based hardening resin composition, molded article, and medical tube.
This patent application is currently assigned to SUMITOMO BAKELITE CO., LTD.. The applicant listed for this patent is Jun Okada, Kazunobu Senoo. Invention is credited to Jun Okada, Kazunobu Senoo.
Application Number | 20130331821 14/001093 |
Document ID | / |
Family ID | 46720915 |
Filed Date | 2013-12-12 |
United States Patent
Application |
20130331821 |
Kind Code |
A1 |
Okada; Jun ; et al. |
December 12, 2013 |
SILICONE RUBBER-BASED HARDENING RESIN COMPOSITION, MOLDED ARTICLE,
AND MEDICAL TUBE
Abstract
The present invention provides a silicone rubber-based hardening
composition which can produce a silicone rubber having excellent
tensile strength and tear strength, a molded article which is made
using the silicone rubber-based hardening composition, and a
medical tube which is obtained by using the molded article, and the
silicone rubber-based hardening composition according to the
present invention contains linear organopolysiloxane having a vinyl
group (A); linear organohydrogen polysiloxane (B); and silica
filler (C) of which the surface is treated with a silane coupling
agent having a trimethylsilyl group.
Inventors: |
Okada; Jun; (Tokyo, JP)
; Senoo; Kazunobu; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Okada; Jun
Senoo; Kazunobu |
Tokyo
Tokyo |
|
JP
JP |
|
|
Assignee: |
SUMITOMO BAKELITE CO., LTD.
Shinagawa-ku, Tokyo
JP
|
Family ID: |
46720915 |
Appl. No.: |
14/001093 |
Filed: |
February 22, 2012 |
PCT Filed: |
February 22, 2012 |
PCT NO: |
PCT/JP2012/054250 |
371 Date: |
August 22, 2013 |
Current U.S.
Class: |
604/525 ;
524/188 |
Current CPC
Class: |
C08K 2201/003 20130101;
C08L 83/04 20130101; C08K 5/56 20130101; C08K 2201/006 20130101;
C08L 83/04 20130101; C08K 3/36 20130101; C08K 9/06 20130101; C08G
77/12 20130101; A61L 29/06 20130101; C08L 83/00 20130101; C08L
2203/02 20130101; A61L 29/06 20130101; A61L 29/126 20130101; C08K
3/36 20130101; A61L 29/126 20130101; C08G 77/20 20130101; C08K 9/06
20130101; C08L 83/04 20130101; C08L 83/00 20130101; C08K 5/56
20130101; C08K 9/06 20130101; C08L 83/04 20130101; C08L 83/00
20130101; C08L 83/04 20130101; C08K 3/36 20130101; C08K 3/36
20130101; C08L 83/00 20130101; C09C 1/3081 20130101; A61L 29/049
20130101; C08L 83/04 20130101 |
Class at
Publication: |
604/525 ;
524/188 |
International
Class: |
A61L 29/12 20060101
A61L029/12 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2011 |
JP |
2011-037513 |
Feb 23, 2011 |
JP |
2011-037516 |
Claims
1: A silicone rubber-based hardening composition comprising: a
linear organopolysiloxane comprising a vinyl group (A); a linear
organohydrogen polysiloxane (B); and a silica filler (C) of which
the surface is treated with a silane coupling agent comprising a
trimethylsilyl group.
2: The silicone rubber-based hardening composition according to
claim 1, wherein the silicone rubber-based hardening composition
further comprises: a silica filler (D) of which the surface is
treated with a silane coupling agent comprising an organosilyl
group comprising a vinyl group.
3: The silicone rubber-based hardening composition according to
claim 1, wherein the linear organopolysiloxane having comprising a
vinyl group (A) is represented by formula (1): ##STR00010##
wherein, in formula (1): m denotes an integer from 1 to 1,000; n
denotes an integer from 3,000 to 10,000; R.sup.1 denotes an alkyl
group, alkenyl group, aryl group, which comprises 1 to 10 carbon
atoms, and has a substituted group or no substituted group, or a
hydrocarbon group in which these groups are combined; R.sup.2
denotes an alkyl group, alkenyl group, aryl group, which comprises
1 to 10 carbon atoms, and has a substituted group or no substituted
group, or a hydrocarbon group in which these groups are combined;
R.sup.3 denotes an alkyl group, aryl group, which comprises 1 to 8
carbon atoms, and has a substituted group or no substituted group,
or a hydrocarbon group in which these groups are combined; and at
least one of plural R.sup.1 and R.sup.2 is an alkenyl group.
4: The silicone rubber-based hardening composition according to
claim 1, wherein the linear organohydrogen polysiloxane (B) is
represented by formula (2): ##STR00011## wherein, in formula (2): m
denotes an integer from 0 to 300; n denotes an integer represented
by (300-m); R.sup.4 denotes an alkyl group, alkenyl group, aryl
group, which comprises 1 to 10 carbon atoms, and has a substituted
group or no substituted group, a hydrocarbon group in which these
groups are combined, or a hydride group; R.sup.5 denotes an alkyl
group, alkenyl group, aryl group, which comprises 1 to 10 carbon
atoms, and has a substituted group or no substituted group, a
hydrocarbon group in which these groups are combined, or a hydride
group; at least two of plural R.sup.4 and R.sup.5 are a hydride
group; and R.sup.6 denotes an alkyl group, aryl group, which
comprises 1 to 8 carbon atoms, and has a substituted group or no
substituted group, or a hydrocarbon group in which these groups are
combined.
5: The silicone rubber-based hardening composition according to
claim 1, wherein the silane coupling agent comprising a
trimethylsilyl group is at least one selected from the group
consisting of silazane, chlorosilane, and alkoxysilane.
6: The silicone rubber-based hardening composition according to
claim 1, wherein the silane coupling agent comprising a
trimethylsilyl group is at least one selected from the group
consisting of hexamethyldisilazane, trimethylchlorosilane,
trimethylmethoxysilane, and trimethylethoxysilane.
7: The silicone rubber-based hardening composition according to
claim 1, wherein the silica filler (C) of which the surface is
treated with a silane coupling agent comprising a trimethylsilyl
group comprises carbon in a range of 0.1% to 7.0% by weight.
8: The silicone rubber-based hardening composition according to
claim 1, wherein the silica filler (C) of which the surface is
treated with a silane coupling agent comprising a trimethylsilyl
group has a specific surface area in a range of 30 to 500
m.sup.2/g, and an average primary particle diameter of 100 nm or
less.
9: The silicone rubber-based hardening composition according to
claim 2, wherein the silane coupling agent comprising an
organosilyl group comprising a vinyl group is at least one selected
from the group consisting of silazane, chlorosilane, and
alkoxysilane.
10: The silicone rubber-based hardening composition according to
claim 2, wherein the silane coupling agent having an organosilyl
group comprising a vinyl group is at least one selected from the
group consisting of methacryloxypropyl triethoxysilane,
methacryloxypropyl trimethoxysilane, methacryloxypropyl
methyldiethoxysilane, methacryloxypropyl methyldimethoxysilane,
divinyl tetramethyldisilane, vinyltriethoxysilane,
vinyltrimethoxysilane, and vinylmethyldimethoxysilane.
11: The silicone rubber-based hardening composition according to
claim 2, wherein the silica filler (D) of which the surface is
treated with a silane coupling agent comprising an organosilyl
group comprising a vinyl group has a specific surface area in a
range of 30 to 500 m.sup.2/g, and an average primary particle
diameter of 100 nm or less.
12: The silicone rubber-based hardening composition according to
claim 1, wherein the linear organopolysiloxane comprising a vinyl
group (A) comprises: a first linear organopolysiloxane comprising a
vinyl group (A1) comprising 0.05% to 0.2% by mole of a vinyl group;
and a second linear organopolysiloxane comprising a vinyl group
(A2) comprising 0.5% to 12% by mole of a vinyl group.
13: The silicone rubber-based hardening composition according to
claim 1, wherein the polymerization degree of the linear
organopolysiloxane comprising a vinyl group (A) is in a range of
4,000 to 8,000.
14: The silicone rubber-based hardening composition according to
claim 1, wherein the linear organohydrogen polysiloxane (B) does
not comprise a vinyl group.
15: The silicone rubber-based hardening composition according to
claim 1, wherein the silicone rubber-based hardening composition
comprises 0.1 to 5 parts by weight of the linear organohydrogen
polysiloxane (B), and 20 to 150 parts by weight of the silica
filler (C) of which the surface is treated with a silane coupling
agent comprising a trimethylsilyl group, relative to 100 parts by
weight of the linear organopolysiloxane comprising a vinyl group
(A).
16: The silicone rubber-based hardening composition according to
claim 2, wherein the silicone rubber-based hardening composition
comprises 0.1 to 5 parts by weight of the linear organohydrogen
polysiloxane (B), 20 to 150 parts by weight of the silica filler
(C) of which the surface is treated with a silane coupling agent
comprising a trimethylsilyl group, and 0.5 to 100 parts by weight
of the silica filler (D) of which the surface is treated with a
silane coupling agent comprising an organosilyl group comprising a
vinyl group, relative to 100 parts by weight of the linear
organopolysiloxane comprising a vinyl group (A).
17: The silicone rubber-based hardening composition according to
claim 1, wherein the silicone rubber-based hardening composition
further comprises a catalyst quantity of platinum or a platinum
compound.
18: A molded article, obtained by molding the silicone rubber-based
hardening composition according to claim 1.
19: A medical tube, comprising the molded article according to
claim 18.
Description
TECHNICAL FIELD
[0001] The present invention relates to a silicone rubber-based
hardening resin composition, a molded article using the silicone
rubber-based hardening resin composition, and a medical tube using
the molded article.
[0002] Priority is claimed on Japanese Patent Applications No.
2011-037513 and 2011-037516 filed Feb. 23, 2011, the contents of
which are incorporated herein by reference.
BACKGROUND ART
[0003] Since silicone rubber is excellent in heat resistance, flame
resistance, chemical stability, weather resistance, radiation
resistance, electrical properties, and the like, it has been used
for a variety of uses in a wide range of areas. In particular,
since silicone rubber is physiologically inactive and reacts little
with body tissues when the silicone rubber is in touch with a
living body, it has been used as a material for medical instruments
such as medical catheters.
[0004] The medical catheter is a tube which is inserted into a body
cavity such as a thoracic cavity and an abdominal cavity, a lumen
such as an alimentary canal and a ureter, and a blood vessel, and
used to discharge a body fluid, or injecting or dripping a drug
solution, nutrition, or a contrast medium. The medical catheter is
required to have scratch resistance (tear resistance), kink
resistance (tensile strength), transparency, flexibility (tensile
elongation properties), and the like, in addition to
biocompatibility. Specifically, the medical catheter is used as a
drainage tube of an aspirator for removing an effluent such as
blood, and pus after a surgery operation, and a tube for intaking
nutrient after a surgical operation such as percutaneous endoscopic
gastrostomy (PEG). In addition, in order to make silicone rubber
for an extremely fine tube as a catheter, the silicone rubber
composition, which is a raw material of the silicone rubber, is
required to have extrusion molding properties.
[0005] As a material for medical catheters, soft polyvinyl chloride
is also widely used in addition to silicone rubber. Compared with
polyvinyl chloride, silicone rubber is excellent in
biocompatibility and flexibility, but required to have improved
strength such as tear resistance, and tensile strength, in
particular, tear resistance. When the tear resistance is
insufficient, the catheter may be torn by the damage made by a
needle or a blade used during a surgical operation. When the
tensile strength is insufficient, the catheter may be bent and
closed (kinked), and thereby, a flow of a body fluid which should
be discharged or a drug solution which should be injected may be
stagnated.
[0006] Therefore, in order to improve the tear strength and tensile
strength of silicone rubber, various methods have been suggested
(for example, Patent Documents Nos. 1 to 8).
[0007] For example, Patent Document No. 1 discloses a hardening
silicone rubber composition which contains mainly
organopolysiloxane having high viscosity and containing a small
amount of a vinyl group (crude rubber (A)), and is added with
organopolysiloxane having low viscosity and containing a large
amount of a vinyl group (silicone oil (B)), an organopolysiloxane
copolymer containing a vinyl group (silicone resin containing a
vinyl group (C)), organo-hydrogen siloxane (crosslinking agent
(D)), platinum or a platinum compound (hardening catalyst (E)), and
fine powdered silica (filler (F)).
PRIOR ART DOCUMENT
Patent Document
[0008] Patent Document No. 1: Japanese Unexamined Patent
Application, First Publication No. Hei 7-331079
[0009] Patent Document No. 2: Japanese Unexamined Patent
Application, First Publication No. Hei 7-228782
[0010] Patent Document No. 3: Japanese Unexamined Patent
Application, First Publication No. Hei 7-258551
[0011] Patent Document No. 4: U.S. Pat. No. 3,884,866
[0012] Patent Document No. 5: U.S. Pat. No. 4,539,357
[0013] Patent Document No. 6: U.S. Pat. No. 4,061,609
[0014] Patent Document No. 7: U.S. Pat. No. 3,671,480
[0015] Patent Document No. 8: Japanese Unexamined Patent
Application, First Publication No. 2005-68273
DISCLOSURE OF THE INVENTION
Problems to be Solved
[0016] Examples of a method for applying high tear resistance to
silicone rubber include addition of an inorganic filler such as
silica fine particles, and changing the crosslinking density
(distributing an area at which the crosslinking density is high and
an area at which the crosslinking density is low in the silicone
rubber). In a method for improving the tear strength by changing
the crosslinking density, it is believed that the area at which the
crosslinking density is high resists the tear stress.
[0017] However, the mechanical strength, in particular, the tear
strength of the silicone rubber is desired to be further
improved.
[0018] In addition, as a material for the medical catheter, the
silicone rubber is desired to have a certain level of hardness.
When the catheter made of a material having low hardness is
inserted into a target part (for example, thoracic cavity), the
catheter is easily deformed due to insertion resistance, this means
"no elasticity", and easily closed due to low kink resistance.
[0019] As explained above, the mechanical strength of the silicone
rubber is desired to be improved. In particular, the silicone
rubber excellent in tear strength and hardness is desired to be
developed.
[0020] In consideration of the above-described problems, it is an
object of the present invention is to provide a silicone
rubber-based hardening composition which can produce a silicone
rubber having excellent tear strength.
[0021] In addition, another object of the present invention is to
provide a silicone rubber-based hardening composition which can
produce a silicone rubber having excellent tensile strength, tear
strength, and hardness.
Means for Solving the Problem
[0022] The object is achieved by the following inventions (1) to
(32).
[0023] (1) A silicone rubber-based hardening composition
containing:
[0024] linear organopolysiloxane having a vinyl group (A);
[0025] linear organohydrogen polysiloxane (B); and
[0026] silica filler (C) of which the surface is treated with a
silane coupling agent having a trimethylsilyl group.
[0027] (2) The silicone rubber-based hardening composition
according to (1), wherein the linear organopolysiloxane having a
vinyl group (A) is represented by the following formula (1).
##STR00001##
[0028] (in the formula (1), m denotes an integer from 1 to 1,000; n
denotes an integer from 3,000 to 10,000; R.sup.1 denotes an alkyl
group, alkenyl group, aryl group, which contains 1 to 10 carbon
atoms, and has a substituted group or no substituted group, or a
hydrocarbon group in which these groups are combined; R.sup.2
denotes an alkyl group, alkenyl group, aryl group, which contains 1
to 10 carbon atoms, and has a substituted group or no substituted
group, or a hydrocarbon group in which these groups are combined;
R.sup.3 denotes an alkyl group, aryl group, which contains 1 to 8
carbon atoms, and has a substituted group or no substituted group,
or a hydrocarbon group in which these groups are combined; and at
least one of plural R.sup.1 and R.sup.2 is an alkenyl group.)
[0029] (3) The silicone rubber-based hardening composition
according to (1) or (2), wherein the linear organohydrogen
polysiloxane (B) is represented by the following formula (2).
##STR00002##
[0030] (in the formula (2), m denotes an integer from 0 to 300; n
denotes an integer represented by (300-m); R.sup.4 denotes an alkyl
group, alkenyl group, aryl group, which contains 1 to 10 carbon
atoms, and has a substituted group or no substituted group, a
hydrocarbon group in which these groups are combined, or a hydride
group; R.sup.5 denotes an alkyl group, alkenyl group, aryl group,
which contains 1 to 10 carbon atoms, and has a substituted group or
no substituted group, a hydrocarbon group in which these groups are
combined, or a hydride group; at least two of plural R.sup.4 and
R.sup.5 are a hydride group; and R.sup.6 denotes an alkyl group,
aryl group, which contains 1 to 8 carbon atoms, and has a
substituted group or no substituted group, or a hydrocarbon group
in which these groups are combined.)
[0031] (4) The silicone rubber-based hardening composition
according to any one of (1) to (3), wherein the silane coupling
agent having a trimethylsilyl group is at least one selected from
the group consisting of silazane, chlorosilane, and
alkoxysilane.
[0032] (5) The silicone rubber-based hardening composition
according to any one of (1) to (4), wherein the silane coupling
agent having a trimethylsilyl group is at least one selected from
the group consisting of hexamethyldisilazane,
trimethylchlorosilane, trimethylmethoxysilane, and
trimethylethoxysilane.
[0033] (6) The silicone rubber-based hardening composition
according to any one of (1) to (5), wherein the silica filler (C)
of which the surface is treated with a silane coupling agent having
a trimethylsilyl group contains carbon in a range of 0.1% by weight
to 7.0% by weight.
[0034] (7) The silicone rubber-based hardening composition
according to any one of (1) to (6), wherein the silica filler (C)
of which the surface is treated with a silane coupling agent having
a trimethylsilyl group has a specific surface area in a range of 30
m.sup.2/g to 500 m.sup.2/g, and an average primary particle
diameter of 100 nm or less.
[0035] (8) The silicone rubber-based hardening composition
according to any one of (1) to (7), wherein the linear
organopolysiloxane having a vinyl group (A) contains a first linear
organopolysiloxane having a vinyl group (A1) containing 0.05% by
mole to 0.2% by mole of a vinyl group, and a second linear
organopolysiloxane having a vinyl group (A2) containing 0.5% by
mole to 12% by mole of a vinyl group.
[0036] (9) The silicone rubber-based hardening composition
according to any one of (1) to (8), wherein the polymerization
degree of the linear organopolysiloxane having a vinyl group (A) is
in a range of 4,000 to 8,000.
[0037] (10) The silicone rubber-based hardening composition
according to any one of (1) to (9), wherein the linear
organohydrogen polysiloxane (B) does not have a vinyl group.
[0038] (11) The silicone rubber-based hardening composition
according to any one of (1) to (10), wherein the silicone
rubber-based hardening composition contains 0.1 parts by weight to
5 parts by weight of the linear organohydrogen polysiloxane (B),
and 20 parts by weight to 150 parts by weight of the silica filler
(C) of which the surface is treated with a silane coupling agent
having a trimethylsilyl group, relative to 100 parts by weight of
the linear organopolysiloxane having a vinyl group (A).
[0039] (12) The silicone rubber-based hardening composition
according to any one of (1) to (11), wherein the silicone
rubber-based hardening composition further contains a catalyst
quantity of platinum or a platinum compound.
[0040] (13) A molded article which is produced using the silicone
rubber-based hardening composition according to any one of (1) to
(12).
[0041] (14) A medical tube which is the molded article according to
(13).
[0042] (15) A silicone rubber-based hardening composition
containing:
[0043] linear organopolysiloxane having a vinyl group (A);
[0044] linear organohydrogen polysiloxane (B);
[0045] silica filler (C) of which the surface is treated with a
silane coupling agent having a trimethylsilyl group; and
[0046] silica filler (D) of which the surface is treated with a
silane coupling agent having an organosilyl group containing a
vinyl group.
[0047] (16) The silicone rubber-based hardening composition
according to (15), wherein the linear organopolysiloxane having a
vinyl group (A) is represented by the following formula (1).
##STR00003##
[0048] (in the formula (1), m denotes an integer from 1 to 1,000; n
denotes an integer from 3,000 to 10,000; R.sup.1 denotes an alkyl
group, alkenyl group, aryl group, which contains 1 to 10 carbon
atoms, and has a substituted group or no substituted group, or a
hydrocarbon group in which these groups are combined; R.sup.2
denotes an alkyl group, alkenyl group, aryl group, which contains 1
to 10 carbon atoms, and has a substituted group or no substituted
group, or a hydrocarbon group in which these groups are combined;
R.sup.3 denotes an alkyl group, aryl group, which contains 1 to 8
carbon atoms, and has a substituted group or no substituted group,
or a hydrocarbon group in which these groups are combined; and at
least one of plural R.sup.1 and R.sup.2 is an alkenyl group.)
[0049] (17) The silicone rubber-based hardening composition
according to (15) or (16), wherein the linear organohydrogen
polysiloxane (B) is represented by the following formula (2).
##STR00004##
[0050] (in the formula (2), m denotes an integer from 0 to 300; n
denotes an integer represented by (300-m); R.sup.4 denotes an alkyl
group, alkenyl group, aryl group, which contains 1 to 10 carbon
atoms, and has a substituted group or no substituted group, a
hydrocarbon group in which these groups are combined, or a hydride
group; R.sup.5 denotes an alkyl group, alkenyl group, aryl group,
which contains 1 to 10 carbon atoms, and has a substituted group or
no substituted group, a hydrocarbon group in which these groups are
combined, or a hydride group; at least two of plural R.sup.4 and
R.sup.5 are a hydride group; and R.sup.6 denotes an alkyl group,
aryl group, which contains 1 to 8 carbon atoms, and has a
substituted group or no substituted group, or a hydrocarbon group
in which these groups are combined.)
[0051] (18) The silicone rubber-based hardening composition
according to any one of (15) to (17), wherein the silane coupling
agent having a trimethylsilyl group is at least one selected from
the group consisting of silazane, chlorosilane, and
alkoxysilane.
[0052] (19) The silicone rubber-based hardening composition
according to any one of (15) to (18), wherein the silane coupling
agent having a trimethylsilyl group is at least one selected from
the group consisting of hexamethyldisilazane,
trimethylchlorosilane, trimethylmethoxysilane, and
trimethylethoxysilane.
[0053] (20) The silicone rubber-based hardening composition
according to any one of (15) to (19), wherein the silica filler (C)
of which the surface is treated with a silane coupling agent having
a trimethylsilyl group contains carbon in a range of 0.1% by weight
to 7.0% by weight.
[0054] (21) The silicone rubber-based hardening composition
according to any one of (15) to (20), wherein the silica filler (C)
of which the surface is treated with a silane coupling agent having
a trimethylsilyl group has a specific surface area in a range of 30
m.sup.2/g to 500 m.sup.2/g, and an average primary particle
diameter of 100 nm or less.
[0055] (22) The silicone rubber-based hardening composition
according to any one of (15) to (21), wherein the silane coupling
agent having an organosilyl group containing a vinyl group is at
least one selected from the group consisting of silazane,
chlorosilane, and alkoxysilane.
[0056] (23) The silicone rubber-based hardening composition
according to any one of (15) to (22), wherein the silane coupling
agent having an organosilyl group containing a vinyl group is at
least one selected from the group consisting of methacryloxypropyl
triethoxysilane, methacryloxypropyl trimethoxysilane,
methacryloxypropyl methyldiethoxysilane, methacryloxypropyl
methyldimethoxysilane, divinyl tetramethyldisilane,
vinyltriethoxysilane, vinyltrimethoxysilane, and
vinylmethyldimethoxysilane.
[0057] (24) The silicone rubber-based hardening composition
according to any one of (15) to (23), wherein the silica filler (D)
of which the surface is treated with a silane coupling agent having
an organosilyl group containing a vinyl group has a specific
surface area in a range of 30 m.sup.2/g to 500 m.sup.2/g, and an
average primary particle diameter of 100 nm or less.
[0058] (25) The silicone rubber-based hardening composition
according to any one of (15) to (24), wherein the linear
organopolysiloxane having a vinyl group (A) contains a first linear
organopolysiloxane having a vinyl group (A1) containing 0.05% by
mole to 0.2% by mole of a vinyl group, and a second linear
organopolysiloxane having a vinyl group (A2) containing 0.5% by
mole to 12% by mole of a vinyl group.
[0059] (26) The silicone rubber-based hardening composition
according to any one of (15) to (25), wherein the polymerization
degree of the linear organopolysiloxane having a vinyl group (A) is
in a range of 4,000 to 8,000.
[0060] (27) The silicone rubber-based hardening composition
according to any one of (15) to (26), wherein the linear
organohydrogen polysiloxane (B) does not have a vinyl group.
[0061] (28) The silicone rubber-based hardening composition
according to any one of (15) to (27), wherein the silicone
rubber-based hardening composition contains 0.1 parts by weight to
5 parts by weight of the linear organohydrogen polysiloxane (B), 20
parts by weight to 150 parts by weight of the silica filler (C) of
which the surface is treated with a silane coupling agent having a
trimethylsilyl group, and 0.5 parts by weight to 100 parts by
weight of the silica filler (D) of which the surface is treated
with a silane coupling agent having an organosilyl group containing
a vinyl group, relative to 100 parts by weight of the linear
organopolysiloxane having a vinyl group (A).
[0062] (29) The silicone rubber-based hardening composition
according to any one of (15) to (28), wherein the silicone
rubber-based hardening composition further contains a catalyst
quantity of platinum or a platinum compound.
[0063] (30) The silicone rubber-based hardening composition
according to any one of (15) to (29), wherein the silicone
rubber-based hardening composition produces silicone rubber having
a type A-durometer hardness after hardening according to JIS K 6253
(2006) of 55 or more.
[0064] (31) A molded article which is produced using the silicone
rubber-based hardening composition according to any one of (15) to
(30).
[0065] (32) A medical tube which is produced using the molded
article according to (31).
Effects of the Present Invention
[0066] The silicone rubber obtained by hardening the silicone
rubber-based hardening composition according to the present
invention is excellent in mechanical strength such as tensile
strength and tear strength, in particular, tear strength.
Therefore, the molded article which is obtained by using the
silicone rubber-based hardening composition and the medical tube
which is obtained by using the molded article have high mechanical
strength. In other words, according to the present invention, it is
possible to produce a medical catheter made of silicone rubber
which is excellent in scratch resistance and kink resistance, in
particular, scratch resistance.
[0067] In addition, the silicone rubber, which is obtained by
hardening the silicone rubber-based hardening composition according
to the present invention, is excellent in balance between
mechanical strength, in particular, tensile strength, tear
strength, and hardness. Therefore, the molded articles made of the
silicone rubber-based hardening composition, and the medical tube
made of the molded article have high mechanical strength, such as
tensile strength, tear strength, and hardness. In other words,
according to the present invention, it is possible to produce a
medical catheter made of silicone rubber which is excellent in kink
resistance, scratch resistance, and ease of insertion.
DESCRIPTION OF EMBODIMENTS
[0068] The silicone rubber-based hardening composition according to
the present invention contains linear organopolysiloxane having a
vinyl group (A), linear organohydrogen polysiloxane (B), and silica
filler (C) of which the surface is treated with a silane coupling
agent having a trimethylsilyl group.
[0069] In order to improve the mechanical strength, in particular,
tensile strength, of the silicone rubber, silica filler is often
added in the silicone-based hardening composition. However, as a
result of conducting diligent research by the present inventors, it
was found that the tear strength could be remarkably improved by
adding silica filler of which the surface is treated with a
specific silica coupling agent in silicone rubber containing a
specific matrix containing the linear organopolysiloxane having a
vinyl group (A), and the linear organohydrogen polysiloxane (B) as
raw material.
[0070] In other words, the present inventors found that the
mechanical strength, in particular, tear strength, of silicone
rubber could be improved by combining the linear organopolysiloxane
having a vinyl group (A), the linear organohydrogen polysiloxane
(B), and the silica filler (C) of which the surface is treated with
a silane coupling agent having a trimethylsilyl group in advance
(this may be simply denoted by "trimethylsilyl group-surface
treated silica filler (C)" below).
[0071] Specifically, it was surprisingly found that the tear
strength of the silicone rubber could be remarkably improved while
maintaining the tensile strength by combining the linear
organopolysiloxane having a vinyl group (A), the linear
organohydrogen polysiloxane (B), and the silica filler (C) of which
the surface is previously treated with a silane coupling agent
having a trimethylsilyl group, compared with a combination between
the linear organopolysiloxane having a vinyl group (A), the linear
organohydrogen polysiloxane (B), and the silica filler of which the
surface is treated with a silane coupling agent having a
methylsilyl group (dimethyl dichlorosilane). In addition, it was
also found that the elongation at breaking was remarkably increased
while maintaining the tensile strength by combining the linear
organopolysiloxane having a vinyl group (A), the linear
organohydrogen polysiloxane (B), and the trimethylsilyl
group-surface treated silica filler (C).
[0072] As explained above, the reason for improvement of the tear
strength of the silicone rubber by using silica filler as filler
which is combined between the linear organopolysiloxane having a
vinyl group (A), and the linear organohydrogen polysiloxane (B),
and treating the surface of the silica filler with a silane
coupling agent having a trimethylsilyl group in advance can be
presumed as shown below.
[0073] That is, since an increase of the amount of the silica
filler in silicone rubber which is obtained by hardening the
silicone rubber-based hardening composition containing the linear
organopolysiloxane having a vinyl group (A), and the linear
organohydrogen polysiloxane (B), causes the stiffening effects to
be increased, the silicone rubber can changed to a hard material
having high elasticity. To the contrary of this merit, there is a
demerit in that the elongation at breaking of the silicone rubber
is decreased by adding a large amount of the silica filler, and
thereby, the tear strength is decreased.
[0074] In the present invention, it can be presumed that the
hydrophobic property of the silica filler is increased by treating
the surface of the silica filler with the silane coupling agent
having a trimethylsilyl group, and the cohesive force of the silica
filler in the silicone rubber-based hardening composition
containing the linear organopolysiloxane having a vinyl group (A),
the linear organohydrogen polysiloxane (B) is decreased
(condensation due to the hydrogen bond by the silanol group is
decreased), and thereby, the dispersibility of the silica filler in
the composition is improved. In addition, it can be also presumed
that as a result of increase of the hydrophobic property of the
silica filler, when the matrix of the silicon rubber, which is
obtained by hardening the silicon rubber-based hardening
composition, is deformed, the slippage of the silica filler in the
matrix is improved. Thereby, it can be presumed that the stiffening
effects to the mechanical strength, in particular, tear strength,
of the silicone rubber are increased by improvement of the
dispersibility and slippage of the silica filler.
[0075] In addition, it can be presumed that, in particular, the
tear strength among the mechanical strength is improved for the
following reasons.
[0076] That is, the interface between the silica filler and the
rubber matrix is increased by the improvement of the dispersibility
of the silica filler, and the number of the rubber molecular
chains, which are affected by the silica filler, are increased.
Thereby, the stiffening effects due to the silica filler are
increased, and the mechanical strength is also improved. The
molecular mobility of the rubber molecular chains, which are
affected by the silica filler, is decreased by the interaction with
the silica filler. Thereby, the rubber molecular chain is hard
compared with an area having high molecular mobility. In the tear
behavior in silicone rubber, when an initial crack grows and
spreads, and tear stress is applied to the hard area, the hard area
resists the tear stress. As a result, the tear strength is
increased.
[0077] Moreover, the silane coupling agent having a dimethylsilyl
group has been known as a surface treatment agent for making an
inorganic filler hydrophobic. However, as explained above, the
silicone rubber obtained by using the silane coupling agent having
a dimethylsilyl group has remarkably lower tear strength compared
with the silicone rubber obtained by using the silane coupling
agent having a trimethylsilyl group. The reason for causing the
large difference in the tear strength can be presumed to be because
the silane coupling agent having a dimethylsilyl group has lower
cohesive-decrease effects compared with the silane coupling agent
having a trimethylsilyl group. As a result, it can be presumed that
the effects, which are obtained by using the silane coupling agent
having a trimethylsilyl group, cannot be obtained by using the
silane coupling agent having a dimethylsilyl group. In particular,
as explained below, when the amount of the silica filler is
increased, the difference in the tear strength is further increased
(see Examples and Comparative Examples).
[0078] As explained above, the silicone rubber which is obtained by
hardening the silicone rubber-based hardening composition according
to the present invention has excellent tensile strength and tear
strength. Therefore, it is possible to obtain the catheter made of
the silicone rubber which is excellent in scratch resistance and
kink resistance by using the silicone rubber-based hardening
composition according to the present invention.
[0079] Below, the components of the silicone rubber-based hardening
composition according to the present invention will be explained in
detail. The silicone rubber-based hardening composition according
to the present invention essentially contains the following
components (A) to (C).
[0080] (A) Linear Organopolysiloxane Having a Vinyl Group
[0081] The linear organopolysiloxane having a vinyl group is a main
component in the silicone rubber-based hardening composition
according to the present invention, and this is a polymer having a
linear structure. This linear organopolysiloxane has a vinyl group,
and the vinyl group becomes a crosslinking point when vulcanization
is carried out.
[0082] The amount of the vinyl group in the linear
organopolysiloxane having a vinyl group is not particularly
limited. However, the amount of the vinyl group is preferably in a
range of 0.01 to 15% by mole, and more preferably in a range of
0.05 to 12% by mole.
[0083] Moreover, the amount of the vinyl group in the linear
organopolysiloxane having a vinyl group means the molar percentage
of the siloxane unit having a vinyl group when the total unit of
the linear organopolysiloxane having a vinyl group (A) is assumed
to 100% by mole. At this time, one siloxane unit having a vinyl
group is regarded to have one vinyl group.
[0084] The polymerization degree of the linear organopolysiloxane
having a vinyl group (A) is not particularly limited. However, the
polymerization degree is generally in a range of 3,000 to 10,000,
and preferably in a range of 4,000 to 8,000.
[0085] The specific gravity of the linear organopolysiloxane having
a vinyl group (A) is generally in a range of 0.9 to 1.1.
[0086] The linear organopolysiloxane having a vinyl group (A)
preferably has a structure represented by the formula (1)
below.
##STR00005##
(in the formula (1), m denotes an integer from 1 to 1,000; n
denotes an integer from 3,000 to 10,000; R.sup.1 denotes an alkyl
group, alkenyl group, aryl group, which contains 1 to 10 carbon
atoms, and has a substituted group or no substituted group, or a
hydrocarbon group in which these groups are combined; R.sup.2
denotes an alkyl group, alkenyl group, aryl group, which contains 1
to 10 carbon atoms, and has a substituted group or no substituted
group, or a hydrocarbon group in which these groups are combined;
R.sup.3 denotes an alkyl group, aryl group, which contains 1 to 8
carbon atoms, and has a substituted group or no substituted group,
or a hydrocarbon group in which these groups are combined; and at
least one of plural R.sup.1 and R.sup.2 is an alkenyl group.)
[0087] In the formula (1), R.sup.1 denotes an alkyl group, alkenyl
group, aryl group, which contains 1 to 10 carbon atoms, and has a
substituted group or no substituted group, or a hydrocarbon group
in which these groups are combined. Examples of the alkyl group
which contains 1 to 10 carbon atoms include a methyl group, an
ethyl group, and a propyl group. Among these alkyl groups, a methyl
group is preferable. Examples of the alkenyl group which contains 1
to 10 carbon atoms include a vinyl group, an allyl group, and a
butenyl group. Among these alkenyl groups, a vinyl group is
preferable. Examples of the aryl group which contains 1 to 10
carbon atoms include a phenyl group.
[0088] R.sup.2 denotes an alkyl group, alkenyl group, aryl group,
which contains 1 to 10 carbon atoms, and has a substituted group or
no substituted group, or a hydrocarbon group in which these groups
are combined. Examples of the alkyl group which contains 1 to 10
carbon atoms include a methyl group, an ethyl group, and a propyl
group. Among these alkyl groups, a methyl group is preferable.
Examples of the alkenyl group which contains 1 to 10 carbon atoms
include a vinyl group, an allyl group, and a butenyl group.
Examples of the aryl group which contains 1 to 10 carbon atoms
include a phenyl group.
[0089] R.sup.3 denotes an alkyl group, aryl group, which contains 1
to 8 carbon atoms, and has a substituted group or no substituted
group, or a hydrocarbon group in which these groups are combined.
Examples of the alkyl group which contains 1 to 8 carbon atoms
include a methyl group, an ethyl group, and a propyl group. Among
these alkyl groups, a methyl group is preferable. Examples of the
aryl group which contains 1 to 8 carbon atoms include a phenyl
group.
[0090] Examples of the substituted group in R.sup.1 and R.sup.2
which have a substituted group in the formula (1) include a methyl
group, and a vinyl group. Examples of the substituted group in
R.sup.3 which has a substituted group in the formula (1) include a
methyl group.
[0091] Moreover, in the formula (1), plural R.sup.1 are independent
to each other, and may be the same or not. Plural R.sup.2 and
R.sup.3 are independent to each other, and may be the same or not,
similar to R.sup.1.
[0092] However, at least one of plural R.sup.1 and R.sup.2 has a
vinyl group. That is, at least one of plural R.sup.1 and R.sup.2 is
an alkenyl group.
[0093] In the formula (1), m and n are the number of repeating
units that constitute the linear organopolysiloxane having a vinyl
group (A) represented by the formula (1), m is an integer from 1 to
1,000, and n is an integer from 3,000 to 10,000. m is preferably in
a range of 40 to 700, and n is preferably in a range of 3,600 to
8,000.
[0094] A specific structure of the linear organopolysiloxane having
a vinyl group (A) represented by the formula (1) includes the
following structure represented by the formula (1-1) below.
##STR00006##
[0095] In the formula (1-1), R.sup.1 and R.sup.2 are independently
a methyl group or a vinyl group, and at least one of R.sup.1 and
R.sup.2 is a vinyl group.
[0096] In the present invention, it is preferable that the linear
organopolysiloxane having a vinyl group (A) contain a first linear
organopolysiloxane having a vinyl group (A1) containing 0.05% by
mole to 0.2% by mole of a vinyl group, and a second linear
organopolysiloxane having a vinyl group (A2) containing 0.5% by
mole to 12% by mole of a vinyl group. It is possible to locally
present the vinyl group by combining the first linear
organopolysiloxane having a vinyl group (A1) which has a general
vinyl group content and the second linear organopolysiloxane having
a vinyl group (A2) which has a high vinyl group content as the
crude rubber which is the raw material of the silicone rubber.
Thereby, it is possible to effectively form sparse and dense
crosslinking density in the crosslinking network of the silicone
rubber. That is, it is possible to effectively improve the tear
strength of the silicone rubber.
[0097] Specifically, it is preferable to use the first linear
organopolysiloxane having a vinyl group (A1) containing 0.05% by
mol to 0.2% by mole of a unit including a vinyl group as R.sup.1
and/or a unit including a vinyl group as R.sup.2 in the formula
(1-1), and the second linear organopolysiloxane having a vinyl
group (A2) containing 0.5% by mol to 12% by mole of a unit
including a vinyl group as R.sup.1 and/or a unit including a vinyl
group as R.sup.2 in the formula (1-1) as the linear
organopolysiloxane having a vinyl group (A).
[0098] It is preferable that the first linear organopolysiloxane
having a vinyl group (A1) contain 0.1 to 0.15% by mole of a vinyl
group, and the second linear organopolysiloxane having a vinyl
group (A2) contain 0.8 to 8.0% by mole of a vinyl group.
[0099] When the first linear organopolysiloxane having a vinyl
group (A1) and the second linear organopolysiloxane having a vinyl
group (A2) are used in combination, the ratio between the first
linear organopolysiloxane having a vinyl group (A1) and the second
linear organopolysiloxane having a vinyl group (A2) is not
particularly limited. However, the weight ratio ((A1):(A2)) between
them is preferably in a range of 1:0.05 to 1:0.6, in particular,
1:0.08 to 1:0.5 is more preferable.
[0100] It is possible to use only one kind of the first linear
organopolysiloxane having a vinyl group (A1) and the second linear
organopolysiloxane having a vinyl group (A2) respectively. In
addition, two or more kinds of them can also be used.
[0101] (B) Linear Organohydrogen Polysiloxane
[0102] The linear organohydrogen polysiloxane (B) has a linear
structure and a structure (.ident.Si--H) in which Si is directly
connected with hydrogen. The linear organohydrogen polysiloxane (B)
causes a hydrosilylation reaction with a vinyl group in a component
added in the silicone rubber-based hardening composition to make a
crosslink, in addition to the vinyl group in the linear
organopolysiloxane having a vinyl group (A).
[0103] In the linear organohydrogen polysiloxane (B), the amount of
the hydrogen atom which is directly bonded with Si, that is, the
amount of a hydride group, is not particularly limited. In the
silicone rubber-based hardening composition, the amount of the
hydride group in the linear organohydrogen polysiloxane (B) is
preferably in a range of 0.5 to 5 moles, and more preferably in a
range of 1 to 3.5 moles relative to 1 mole of the vinyl group in
the linear organopolysiloxane having a vinyl group (A).
[0104] The molecular weight of the linear organohydrogen
polysiloxane (B) is not particularly limited. However, the weight
average molecular weight of the linear organohydrogen polysiloxane
(B) is preferably 20,000 or less, and in particular, 7,000 is more
preferable. The weight average molecular weight of the linear
organohydrogen polysiloxane (B) can be measured by using GPC (Gel
Permeation Chromatography).
[0105] In general, it is preferable that the linear organohydrogen
polysiloxane (B) do not contain a vinyl group, because there is a
possibility that the crosslinking reaction may be promoted in the
molecule thereof.
[0106] It is preferable that the linear organohydrogen polysiloxane
(B) have a structure represented by the following formula (2).
##STR00007##
[0107] (in the formula (2), m denotes an integer from 0 to 300; n
denotes an integer represented by (300-m); R.sup.4 denotes an alkyl
group, alkenyl group, aryl group, which contains 1 to 10 carbon
atoms, and has a substituted group or no substituted group, a
hydrocarbon group in which these groups are combined, or a hydride
group; R.sup.5 denotes an alkyl group, alkenyl group, aryl group,
which contains 1 to 10 carbon atoms, and has a substituted group or
no substituted group, a hydrocarbon group in which these groups are
combined, or a hydride group; at least two of plural R.sup.4 and
R.sup.5 are a hydride group; and R.sup.6 denotes an alkyl group,
aryl group, which contains 1 to 8 carbon atoms, and has a
substituted group or no substituted group, or a hydrocarbon group
in which these groups are combined.)
[0108] In the formula (2), R.sup.4 denotes an alkyl group, alkenyl
group, aryl group, which contains 1 to 10 carbon atoms, and has a
substituted group or no substituted group, a hydrocarbon group in
which these groups are combined, or a hydride group. Examples of
the alkyl group which contains 1 to 10 carbon atoms include a
methyl group, an ethyl group, and a propyl group. Among these alkyl
groups, a methyl group is preferable. Examples of the alkenyl group
which contains 1 to 10 carbon atoms include a vinyl group, an allyl
group, and a butenyl group. Among these alkenyl groups, a vinyl
group is preferable. Examples of the aryl group which contains 1 to
10 carbon atoms include a phenyl group.
[0109] In the formula (2), R.sup.5 denotes an alkyl group, alkenyl
group, aryl group, which contains 1 to 10 carbon atoms, and has a
substituted group or no substituted group, a hydrocarbon group in
which these groups are combined, or a hydride group. Examples of
the alkyl group which contains 1 to 10 carbon atoms include a
methyl group, an ethyl group, and a propyl group. Among these alkyl
groups, a methyl group is preferable. Examples of the alkenyl group
which contains 1 to 10 carbon atoms include a vinyl group, an allyl
group, and a butenyl group. Among these alkenyl groups, a vinyl
group is preferable. Examples of the aryl group which contains 1 to
10 carbon atoms include a phenyl group.
[0110] Moreover, in the formula (2), plural R.sup.4 are independent
to each other, and may be the same or not. Plural R.sup.5 are
independent to each other, and may be the same or not, similar to
R.sup.4.
[0111] However, at least two of plural R.sup.4 and R.sup.5 are a
hydride group.
[0112] In the formula (2), R.sup.6 is an alkyl group, aryl group,
which contains 1 to 8 carbon atoms, and has a substituted group or
no substituted group, or a hydrocarbon group in which these groups
are combined. Examples of the alkyl group which contains 1 to 8
carbon atoms include a methyl group, an ethyl group, and a propyl
group. Among these alkyl groups, a methyl group is preferable.
Examples of the aryl group which contains 1 to 8 carbon atoms
include a phenyl group. Plural R.sup.6 are independently, and may
be the same or not.
[0113] Examples of the substituted group in R.sup.4, R.sup.5, and
R.sup.6 which have a substituted group in the formula (2) include a
methyl group, and a vinyl group. Among these, a methyl group is
preferable because a methyl group can prevent the crosslinking
reaction in the molecule.
[0114] m and n are the number of repeating units that constitute
the linear organohydrogen polysiloxane (B) represented by the
formula (2), m is an integer from 0 to 300, and n is an integer
from (300-m). m is preferably in a range of 0 to 150, and n is
preferably in a range of (150-m).
[0115] The linear organohydrogen polysiloxane (B) may be used alone
or in combination of two or more.
[0116] (C) Trimethylsilyl Group-Surface Treated Silica Filler
(C)
[0117] The trimethylsilyl group-surface treated silica filler (C)
is silica filler of which the surface is treated with a silane
coupling agent having a trimethylsilyl group
[(CH.sub.3).sub.3--Si--] (this may be simply denoted by
"trimethylsilyl group containing coupling agent") in advance.
[0118] In the present invention, the surface treatment of the
silica filler with the silane coupling agent having a
trimethylsilyl group means a treatment in which the hydroxyl group
bonded with a silicon atom (silanol group: Si--OH) on the surface
of the silica filler is replaced with a functional group containing
a trimethylsilyl group derived from the silane coupling agent
having a trimethylsilyl group, or a treatment in which a functional
group containing a trimethylsilyl group derived from the silane
coupling agent having a trimethylsilyl group is applied on the
surface of the silica filler.
[0119] The silane coupling agent having a trimethylsilyl group has
a functional group containing a trimethylsilyl group and a
hydrolyzable group. Under conditions in which hydrolysis can be
carried out, the hydrolyzable group is hydrolyzed and a hydroxyl
group is generated. The functional group containing a
trimethylsilyl group means a trimethylsilyl group itself or a group
containing a trimethylsilyl group as a part thereof.
[0120] In the present invention, the silane coupling agent having a
trimethylsilyl group typically has a structure in which a silicon
atom in the trimethylsilyl group is bonded with the hydrolyzable
group. Under conditions in which hydrolysis can be carried out, the
hydrolyzable group is hydrolyzed and a silanol, in which the
silicon atom in the trimethylsilyl group is bonded with the
hydroxyl group, is generated.
[0121] The hydroxyl group (typically silanol), which is generated
by the hydrolysis of the hydrolyzable group in the silane coupling
agent having a trimethylsilyl group, makes a dehydration
condensation reaction with the hydroxyl group on the surface of the
silica filler. Thereby, the functional group containing a
trimethylsilyl group of the silane coupling agent is covalently
bonded with the silicon atom of the silica filler via an oxygen
atom (O). Typically, the silicon atom of the trimethylsilyl group
in the silane coupling agent and the silicon atom in the silica
filler make a covalent bond via an oxygen atom (O).
[0122] As explained above, the hydroxyl group of the silanol group
on the surface of the silica filler is replaced with the functional
group containing a trimethylsilyl group.
[0123] Examples of the silica filler of which the surface is
treated with the silane coupling agent having a trimethylsilyl
group include dried silica and wet silica. In particular, dried
silica is preferable from the viewpoint of extrusion moldability of
the silicone rubber, and fumed silica is more preferable.
[0124] Any silane coupling agent having a trimethylsilyl group can
be used as long as it has a trimethylsilyl group and generates a
hydroxyl group under conditions in which hydrolysis can be carried
out, and has a hydrolyzable group which can cause a dehydration
condensation reaction with the hydroxyl group in the silanol group
on the surface of the silica filler. Examples of the silane
coupling agent having a trimethylsilyl group include silazane,
chlorosilane and alkoxysilane.
[0125] Any silazane can be used as long as it has a structure in
which the silicon atom in the trimethylsilyl group is bonded with a
nitrogen atom. Examples of the silazane used include
hexamethyldisilazane.
[0126] Any chlorosilane can be used as long as it has a structure
in which the silicon atom in the trimethylsilyl group is bonded
with a chlorine atom. Examples of the chlorosilane used include
trimethylchlorosilane.
[0127] Any alkoxysilane can be used as long as it has a structure
in which the silicon atom in the trimethylsilyl group is bonded
with an alkoxy group. Examples of the alkoxysilane used include
trimethylmethoxysilane, and trimethylethoxysilane.
[0128] Among these, at least one selected from the group consisting
of hexadimethyldisilazane, trimethylchlorosilane,
trimethylmethoxysilane, and trimethylethoxysilane is preferably
used.
[0129] The degree of the surface treatment of the silica filler
with the silane coupling agent having a trimethylsilyl group is not
particularly limited because a preferable degree varies depending
on the kind of the silane coupling agent used, the surface area of
the silica filler, and the like. However, the surface treatment is
preferably carried out at a certain degree so that the
trimethylsilyl group-surface treated silica filler (C) after the
surface treatment contains 0.1 to 7.0% by weight, preferably 1.0 to
4.0% by weight, and more preferably 1.5 to 3.0% by weight of carbon
atom. The carbon content in the trimethylsilyl group-surface
treated silica filler (C) is relevant to the carbon content in
organic groups derived from the silane coupling agent which is
chemically bonded with the surface of the silica filler. The carbon
content gives an indication of the surface treatment degree of the
silica filler by the silane coupling agent.
[0130] It is possible to remarkably improve the tear strength and
tensile strength, in particular, tear strength of the silicone
rubber by adjusting the carbon content of the trimethylsilyl
group-surface treated silica filler (C) in the above mentioned
range.
[0131] The carbon content of the trimethylsilyl group-surface
treated silica filler (C) can be calculated in the following
manner.
[0132] That is, the carbon content can be calculated by thermally
decomposing the trimethylsilyl group-surface treated silica filler
(C) under oxygen atmosphere at 1,000 to 1,200.degree. C. using a
trace carbon analyzer, and measuring the amount of CO.sub.2
generated.
[0133] It is preferable that all of the hydroxyl groups in the
silanol group on the surface of the trimethylsilyl group-surface
treated silica filler (C) be replaced with a functional group
containing the trimethylsilyl group derived from the silane
coupling agent having a trimethylsilyl group.
[0134] Any surface treatment methods using the silane coupling
agent having a trimethylsilyl group can be used without
limitations. For example, a method disclosed in Published Japanese
Translation No. 2007-526373 of the PCT International Publication
can be used.
[0135] Specifically, a method in which after spraying water to the
silica filler (non-treated silica filler), of which the surface is
not treated with the silane coupling agent having a trimethylsilyl
group, the silane coupling agent having a trimethylsilyl group is
also sprayed to the silica filler, and then the silica filler is
thermally treated, can be used. The water used may be acidified
(for example, pH 1 to 7) using an acid such as hydrochloric acid.
The silane coupling agent used may be dissolved in an appropriate
solvent if necessary.
[0136] The spraying of water or the silane coupling agent can be
carried out using a one-fluid nozzle, two-fluid nozzle, or
ultrasonic nozzle. It is preferable that the spraying be carried
out in a vessel provided with a mixing means while stirring the
silica filler. After spraying of water and the silane coupling
agent, if necessary, the silica filler and water and/or the silica
coupling agent may be mixed. The temperature and the time in the
thermal treatment can be adjusted, and for example, the thermal
treatment may be carried out at 20 to 400.degree. C. for 0.1 to 6
hours. The thermal treatment can also be carried out under inert
gas atmosphere such as nitrogen gas.
[0137] Otherwise, a method, in which the non-treated silica filler
is subjected to the vapor of the silane coupling agent, and then
heated (for example, 50 to 800.degree. C.), can also be used. The
thermal treatment can also be carried out under inert
atmosphere.
[0138] It is preferable that the trimethylsilyl group-surface
treated silica filler (C) have a specific surface area of 30
m.sup.2/g or more, more preferably 100 m.sup.2/g or more, and 500
m.sup.2/g or less, and more preferably 300 m.sup.2/g or less. The
specific surface area is most preferably in a range of 30 to 500
m.sup.2/g.
[0139] The specific surface area of the trimethylsilyl
group-surface treated silica filler (C) can be measured by a common
method, for example, BET specific surface area method can be
used.
[0140] In addition, it is preferable that the average primary
particle diameter of the trimethylsilyl group-surface treated
silica filler (C) be 100 nm or less, and in particular, 20 nm or
less is preferable.
[0141] The average primary particle diameter of the trimethylsilyl
group-surface treated silica filler (C) can be measured by a common
method.
[0142] The trimethylsilyl group-surface treated silica filler (C)
can be used alone or in combination of two or more. For example,
the silica fillers (C), of which the surface is treated with
different silane coupling agent having a trimethylsilyl groups, may
be combined.
[0143] The silicone rubber-based hardening composition according to
the present invention may contain components in addition to the
components (A) to (C). As the component which may be added in
addition to the components (A) to (C), platinum or a platinum
compound (E), which is explained below, can be used.
[0144] (E) Platinum or Platinum Compound
[0145] Platinum or a platinum compound (E) acts a catalyst for
vulcanization. The amount used is a catalyst amount. As the
platinum or a platinum compound (E), well-known components can be
used. Examples of the platinum or the platinum compound (E) used
include platinum black, a support in which platinum is supported on
silica or carbon black, chloroplatinic acid, an alcohol solution of
chloroplatinic acid, a complex of chloroplatinic acid and olefin,
and a complex of chloroplatinic acid and vinylsiloxane. The
platinum or a platinum compound (E), which is a catalyst component,
may be used alone or in combination of two or more.
[0146] The silicone rubber-based hardening composition according to
the present invention may contain a well-known component which is
added in the silicone rubber-based hardening composition in
addition to the components (A) to (C), and (E). Examples of the
component include diatom earth, iron oxide, zinc oxide, titanium
oxide, barium oxide, magnesium oxide, cerium oxide, calcium
carbonate, magnesium carbonate, zinc carbonate, glass-wool, and
mica. In addition, a dispersant, pigment, die, antistatic agent,
antioxidant, flame retardant, heat conduction improver. An
appropriate amount of these components can be added in the silicone
rubber-based hardening composition according to the present
invention.
[0147] In the silicone rubber-based hardening composition according
to the present invention, the content of each component is not
particularly limited. However, in general, it is preferable that
the silicone rubber-based hardening composition contain 0.1 to 5
parts by weight of the linear organohydrogen polysiloxane (B), and
20 to 150 parts by weight of the trimethylsilyl group-surface
treated silica filler (C), relative to 100 parts by weight of the
linear organopolysiloxane having a vinyl group (A). In particular,
it is preferable that the silicone rubber-based hardening
composition contain 0.1 to 2 parts by weight of the linear
organohydrogen polysiloxane (B), and 50 to 100 parts by weight of
the trimethylsilyl group-surface treated silica filler (C),
relative to 100 parts by weight of the linear organopolysiloxane
having a vinyl group (A).
[0148] The amount of platinum or the platinum compound (E) used is
a catalyst amount, and can be appropriately adjusted. However, the
content of platinum or the platinum compound (E) is preferably in a
range of 0.05 to 5 parts by weight, and more preferably in a range
of 0.1 to 1 part by weight relative to 100 parts by weight of the
linear organopolysiloxane having a vinyl group (A).
[0149] The silicone rubber-based hardening composition according to
the present invention can be obtained by uniformly mixing the
components explained above using a kneading device. Examples of the
kneading device include kneader, two-roller, Banbury mixer
(continuous kneader), and pressurized kneader.
[0150] Platinum or the platinum compound (E) which is a catalyst is
preferably dispersed in the linear organopolysiloxane having a
vinyl group (A) from the viewpoint of ease of handling.
[0151] The silicone rubber can be obtained by heating the silicone
rubber-based hardening composition according to the present
invention which is obtained as explained above at 140 to
180.degree. C. for 5 to 15 minutes (first hardening), and then
post-baking at 200.degree. C. for 4 hours (second hardening).
[0152] The silicone rubber, which is excellent in the tear strength
and tensile strength, in particular, tear strength, can be obtained
by hardening the silicone rubber-based hardening composition
according to the present invention.
[0153] In addition, the silicone rubber, which has 1,000% or more
of an elongation at breaking (strain) of a dumb-bell shaped third
test piece according to JIS K 6251 (2004), can be obtained by
hardening the silicone rubber-based hardening composition according
to the present invention.
[0154] In other words, according to the present invention, the
silicone rubber having high elongation even when the silicone
rubber contains a large amount of the silica filler can be
obtained.
[0155] In addition, the silicone rubber, which can extend at 100 mm
or more before breaking a crescent-shaped test piece according to
JIS K 6252 (2001), can be obtained.
[0156] In other words, according to the present invention, the
silicone rubber having high elongation even when the silicone
rubber contains a large amount of the silica filler can be
obtained.
[0157] In the present invention, the tensile strength and
elongation at breaking are based on JIS K 6251 (2004) except that
the thickness of the test piece which is obtained by hardening the
silicone rubber-based hardening composition is adjusted to 1
mm.
[0158] In addition, the tear strength and stroke are based on JIS K
6252 (2001) except that the thickness of the test piece which is
obtained by hardening the silicone rubber-based hardening
composition is adjusted to 1 mm.
[0159] The molded articles having excellent mechanical strength
explained above can be obtained by using the silicone rubber having
such tensile strength and tear strength. In addition, the medical
tube (for example, catheter) made of silicone rubber which is
excellent in kink resistance and scratch resistance by using the
molded article.
[0160] In another silicone rubber-based hardening composition
according to the present invention, the silicone rubber-based
hardening composition preferably further contains silica filler
(D), of which the surface is treated with a silane coupling agent
having an organosilyl group containing a vinyl group.
[0161] In order to improve the mechanical strength of the silicone
rubber, silica filler is often added in the silicone based
hardening composition. However, as a result of conducting diligent
research by the present inventors, it was found that the balance
between the tensile strength, tear strength, and hardness could be
remarkably improved by adding two kinds of silica filler in
combination of which the surface is treated with a specific silica
coupling agent in silicone rubber containing a specific matrix
containing the linear organopolysiloxane having a vinyl group (A),
and the linear organohydrogen polysiloxane (B) as raw material.
[0162] In other words, the present inventors found that the
mechanical strength, in particular, the balance between the tensile
strength, tear strength, and hardness of silicone rubber could be
improved by combining the linear organopolysiloxane having a vinyl
group (A) and the linear organohydrogen polysiloxane (B); and the
silica filler (C) (this may be simply denoted by "silicon filler
(C)" below) of which the surface is treated with a silane coupling
agent having a trimethylsilyl group in advance, and silica filler
(D) of which the surface is treated with a silane coupling agent
having an organosilyl group containing a vinyl group (this may be
simply denoted by "silicon filler (D)" below).
[0163] As explained above, the reason for improvement of the
balance between the tensile strength, tear strength, and hardness
of the silicone rubber in this embodiment can be presumed as shown
below.
[0164] That is, an increase of the amount of the silica filler in
silicone rubber which is obtained by hardening the silicone
rubber-based hardening composition containing the linear
organopolysiloxane having a vinyl group (A), and the linear
organohydrogen polysiloxane (B), causes the stiffening effects to
be increased, and the silicone rubber can changed to a hard
material having high elasticity. To the contrary of this merit,
there is a demerit in that the elongation at breaking of the
silicone rubber is decreased by adding a large amount of the silica
filler, and thereby, the tear strength is decreased.
[0165] In this embodiment, these demerits due to the silica filler
can be solved and properties of the silicone rubber can be improved
by using both of the silica filler (C) of which the surface is
treated with a silane coupling agent having a trimethylsilyl group
in advance, and the silica filler (D) of which the surface is
treated with a silane coupling agent having an organosilyl group
containing a vinyl group.
[0166] The silica filler (C) has high hydrophobic properties
because the surface of the silica filler (C) is previously treated
with the silane coupling agent having a trimethylsilyl group. As a
result, it can be presumed that the cohesive force of the silica
filler (C) is decreased (condensation due to the hydrogen bond by
the silanol group is decreased) in the silicone rubber-based
hardening composition containing the linear organopolysiloxane
having a vinyl group (A), and the linear organohydrogen
polysiloxane (B) is decreased, and thereby, the dispersibility of
the silica filler (C) in the composition is improved. In addition,
it can be also presumed that as a result of increase of the
hydrophobic property of the silica filler (C), when the matrix of
the silicon rubber, which is obtained by hardening the silicon
rubber-based hardening composition, is deformed, the slippage of
the silica filler (C) in the matrix is improved. Thereby, it can be
presumed that the stiffening effects to the mechanical strength
(for example, tensile strength, tear strength, and the like), in
particular, tear strength of the silicone rubber are increased by
improvement of the dispersibility and slippage of the silica
filler.
[0167] In addition, it can be presumed that, in particular, the
tear strength among the mechanical strength is improved for the
following reasons.
[0168] That is, the interface between the silica filler (C) and the
rubber matrix is increased by improving the dispersibility of the
silica filler (C), and the rubber molecular chains, which are
affected by the silica filler, are increased. Thereby, the
stiffening effects due to the silica filler are increased, and the
mechanical strength is also improved. The molecular mobility of the
rubber molecular chains, which are affected by the silica filler,
is decreased by the interaction with the silica filler. Thereby,
the rubber molecular chain is hard compared with an area having
high molecular mobility. In the tear behavior in silicone rubber,
when an initial crack grows and spreads, and tear stress is applied
to the hard area, the hard area resists the tear stress. As a
result, the tear strength is increased.
[0169] The silica filler (D) is previously subjected to a surface
treatment using a silane coupling agent having an organosilyl group
containing a vinyl group. Therefore, the surface of the silica
filler (D) has a vinyl group. The vinyl group becomes a
crosslinking point when vulcanization is carried out. In other
words, a covalent bond is generated between the silica filler (D)
and a matrix containing the linear organopolysiloxane having a
vinyl group (A) and the linear organohydrogen polysiloxane (B) in
the silicone rubber obtained by hardening the silicone rubber-based
hardening composition according to this embodiment. Because of the
reason as presumed above, the hardness can be improved while
maintaining high tear strength of the silicone rubber by forming a
rubber matrix-silica filler network in the silicone rubber.
[0170] As explained above, the silicone rubber which is obtained by
hardening the silicone rubber-based hardening composition in this
embodiment has excellent tear strength and hardness. Therefore, it
is possible to obtain the catheter made of the silicone rubber
which is excellent in kink resistance, scratch resistance, and ease
of insertion by using the silicone rubber-based hardening
composition according to this embodiment.
[0171] (D) Silica Filler of which the Surface is Treated with a
Silane Coupling Agent Having an Organosilyl Group Containing a
Vinyl Group
[0172] The surface of the silica filler (D) is treated with a
silane coupling agent having an organosilyl group containing a
vinyl group in advance.
[0173] In the present invention, the surface treatment of the
silica filler with the silane coupling agent having an organosilyl
group containing a vinyl group means a treatment in which the
hydroxyl group bonded with a silicon atom (silanol group: Si--OH)
on the surface of the silica filler is replaced with a functional
group containing an organosilyl group containing a vinyl group
derived from the silane coupling agent having an organosilyl group
containing a vinyl group, or a treatment in which an organosilyl
group containing a vinyl group derived from the silane coupling
agent having an organosilyl group containing a vinyl group is
applied on the surface of the silica filler.
[0174] The silane coupling agent having an organosilyl group
containing a vinyl group has a functional group containing an
organosilyl group containing a vinyl group and a hydrolyzable
group. Under conditions in which hydrolysis can be carried out, the
hydrolyzable group is hydrolyzed and a hydroxyl group is
generated.
[0175] The organosilyl group containing a vinyl group means a group
(CH.sub.2.dbd.CH--Si.ident.) in which at least one vinyl group is
directly bonded with a silicon atom or a group
(CH.sub.2.dbd.CH--W--Si.ident.) in which at least one vinyl group
is bonded with a silicon atom via a linking group W. Examples of
the linking group W include an alkyl group, ether group, and ester
group.
[0176] The functional group containing an organosilyl group
containing a vinyl group means an organosilyl group containing a
vinyl group itself or a group containing an organosilyl group
containing a vinyl group as a part thereof.
[0177] In this embodiment, the silane coupling agent having an
organosilyl group containing a vinyl group typically has a
structure in which a silicon atom in the organosilyl group
containing a vinyl group is bonded with at least one hydrolyzable
group. Under conditions in which hydrolysis can be carried out, the
hydrolyzable group is hydrolyzed and a silanol, in which the
silicon atom in the organosilyl group containing a vinyl group is
bonded with the at least one hydroxyl group, is generated.
[0178] The hydroxyl group (typically silanol), which is generated
by the hydrolysis of the hydrolyzable group in the silane coupling
agent having an organosilyl group containing a vinyl group, makes a
dehydration condensation reaction with the hydroxyl group on the
surface of the silica filler. Thereby, the functional group
containing the organosilyl group containing a vinyl group of the
silane coupling agent is covalently bonded with the silicon atom of
the silica filler via an oxygen atom (O). Typically, the silicon
atom of the organosilyl group containing a vinyl group in the
silane coupling agent and the silicon atom in the silica filler
make a covalent bond via an oxygen atom (O).
[0179] As explained above, the hydroxyl group of the silanol group
on the surface of the silica filler is replaced with the functional
group containing the organosilyl group containing a vinyl
group.
[0180] Examples of the silica filler of which the surface is
treated with the silane coupling agent having an organosilyl group
containing a vinyl group include dried silica and wet silica. In
particular, dried silica is preferable from the viewpoint of
extrusion moldability of the silicone rubber, and fumed silica is
more preferable.
[0181] Any silane coupling agent having an organosilyl group
containing a vinyl group can be used as long as it has an
organosilyl group containing a vinyl group and generates a hydroxyl
group under conditions in which hydrolysis can be carried out, and
has a hydrolyzable group which can cause a dehydration condensation
reaction with the hydroxyl group in the silanol group on the
surface of the silica filler. Examples of the silane coupling agent
having an organosilyl group containing a vinyl group include
silazane, chlorosilane and alkoxysilane.
[0182] Any silazane can be used as long as it has a structure in
which the silicon atom in the organosilyl group containing a vinyl
group is bonded with at least one nitrogen atom. Examples of the
silazane used include divinyltetramethyldisilazan.
[0183] Any chlorosilane can be used as long as it has a structure
in which the silicon atom in the organosilyl group containing a
vinyl group is bonded with at least one chlorine atom. Examples of
the chlorosilane used include vinyltrichlorosilane.
[0184] Any alkoxysilane can be used as long as it has a structure
in which the silicon atom in the organosilyl group containing a
vinyl group is bonded with at least one alkoxy group. Examples of
the alkoxysilane used include methacryloxypropyltriethoxysilane,
methacryloxypropyltrimethoxysilane,
methacryloxypropylmethyldiethoxysilane,
methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilanne,
vinyltrimethoxysilane, and vinylmethyldimethoxysilane.
[0185] It is preferable that all of the hydroxyl group in the
silanol group on the surface of the silica filler (D) be replaced
with the functional group containing an organosilyl group
containing a vinyl group derived from the silane coupling agent
having an organosilyl group containing a vinyl group.
[0186] Any surface treatment methods using the silane coupling
agent having an organosilyl group containing a vinyl group can be
used without limitations.
[0187] Specifically, a method in which silica filler is put in a
mixer, first, water and then the silane coupling agent having an
organosilyl group containing a vinyl group, such as
methacryloxypropyltriethoxysilane are added in the silica filler
while stirring, they are mixed at 30.degree. C. for 15 minutes,
dried in an oven at 100.degree. C. for about 1 hour, and then
cooled.
[0188] It is preferable that the silica filler (D) have a specific
surface area of 30 m.sup.2/g or more, more preferably 100 m.sup.2/g
or more, and 500 m.sup.2/g or less, and more preferably 300
m.sup.2/g or less. The specific surface area is most preferably in
a range of 30 to 500 m.sup.2/g. The specific surface area of the
silica filler (D) can be measured by a common method, for example,
BET specific surface area method can be used.
[0189] In addition, it is preferable that the average primary
particle diameter of the silica filler (D) be 100 nm or less, and
in particular, 20 nm or less is preferable.
[0190] The average primary particle diameter of the silica filler
(D) can be measured by a common method.
[0191] The silica filler (D) can be used alone or in combination of
two or more. For example, the silica fillers (D), of which the
surface is treated with a different silane coupling agent having an
organosilyl group containing a vinyl group, may be combined.
[0192] In the silicone rubber-based hardening composition in this
embodiment, the content of each component is not particularly
limited. However, in general, it is preferable that the silicone
rubber-based hardening composition contain 0.1 to 5 parts by weight
of the linear organohydrogen polysiloxane (B), 20 to 150 parts by
weight of the silica filler (C), and 0.5 to 100 parts by weight of
the silica filler (D), relative to 100 parts by weight of the
linear organopolysiloxane having a vinyl group (A). In particular,
it is preferable that the silicone rubber-based hardening
composition contain 0.1 to 2 parts by weight of the linear
organohydrogen polysiloxane (B), 40 to 100 parts by weight of the
silica filler (C), and 0.5 to 50 parts by weight of the silica
filler (D), relative to 100 parts by weight of the linear
organopolysiloxane having a vinyl group (A).
[0193] It is possible to obtain silicone rubber having a type
A-durometer hardness according to JIS K 6253 (2006) of 55 or more
by hardening the silicone rubber-based hardening composition
according to this embodiment.
[0194] The type A-durometer hardness is preferably 55 or more, and
in particular 58 or more is preferable.
[0195] A molded article having excellent mechanical strength can be
obtained by using the silicone rubber having such hardness. In
addition, the medical tube (for example, catheter) made of silicone
rubber, which is excellent in mechanical strength, such as ease of
insertion, can also be obtained by using the molded article.
[0196] In addition, the silicone rubber, which has long elongation
(strain) at break of a dumb-bell shaped third test piece according
to JIS K 6251 (2004) or long elongation (stroke) before breaking a
crescent-shaped test piece according to JIS K 6252 (2001), can be
obtained by hardening the silicone rubber-based hardening
composition according to this embodiment.
[0197] In the present invention, the tear strength and stroke are
based on JIS K 6252 (2001) except that the thickness of the test
piece which is obtained by hardening the silicone rubber-based
hardening composition is adjusted to 1 mm.
[0198] In addition, the type A durometer hardness is based on JIS K
6253 (2006), and can be measured using the test piece which is
obtained by hardening the silicone rubber-based hardening
composition.
[0199] In addition, the tensile strength and elongation at breaking
are based on JIS K 6251 (2004) except that the thickness of the
test piece which is obtained by hardening the silicone rubber-based
hardening composition in this embodiment is adjusted to 1 mm.
EXAMPLES
[0200] Below, embodiments of the silicone rubber-based hardening
composition according to the present invention will be explained
referring to Examples. However, the present invention is not
limited by Examples.
[0201] The following materials were used in Examples 1 to 5 and
Comparative Examples 1 to 4.
[0202] (A1): first linear organopolysiloxane containing a vinyl
group, the content of a vinyl group: 0.13% by mole, and this was
synthesized by the following synthesis scheme.
[0203] (A2): second linear organopolysiloxane containing a vinyl
group, the content of a vinyl group: 0.92% by mole, and this was
synthesized by the following synthesis scheme.
[0204] (B): linear organohydrogen polysiloxane made by Momentive
Inc. trade name: TC-25D
[0205] (C1): silica filler of which the surface is treated with
hyxamethyldisilazane made of Nippon Aerosil Co., Ltd., trade name:
Aerosil.RTM. RX200, specific surface area: 200 m.sup.2/g; average
primary particle diameter: 12 nm; and carbon content: 2.5% by
weight
[0206] (C2): silica filler of which the surface is treated with
hyxamethyldisilazane made of Nippon Aerosil Co., Ltd., trade name:
Aerosil.RTM. RX300, specific surface area: 300 m.sup.2/g; average
primary particle diameter: 7 nm; and carbon content: 3.5% by
weight
[0207] (c1): silica filler of which the surface is not treated made
of Nippon Aerosil Co., Ltd., trade name: Aerosil.RTM. 200, specific
surface area: 200 m.sup.2/g; and average primary particle diameter:
12 nm
[0208] (c2): silica filler of which the surface is treated with
dimethyldichlorosilane made of Nippon Aerosil Co., Ltd., trade
name: Aerosil.RTM. R972, specific surface area: 130 m.sup.2/g; and
average primary particle diameter: 16 nm
[0209] (c3): silica filler of which the surface is treated with
dimethyldichlorosilane made of Nippon Aerosil Co., Ltd., trade
name: Aerosil.RTM. R974, specific surface area: 200 m.sup.2/g; and
average primary particle diameter: 12 nm
[0210] (E) platinum made by Momentive Inc. trade name: TC-25A
[0211] [Synthesis of First Linear Organopolysiloxane Containing a
Vinyl Group (A1)]
[0212] Based on the following formula (3), the first linear
organopolysiloxane containing a vinyl group (A1) was
synthesized.
[0213] Specifically, 74.7 g (252 mmol) of
octamethylcyclotetrasiloxana, 0.086 g (0.25 mmol) of
2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane, and 0.1 g
of potassium siliconate were put into a 300 mL-separable flask
provided with a cooling pipe, and an impeller, of which the inside
was replaced with Ar gas. Then, the temperature was raised, and the
mixture was stirred at 120.degree. C. for 30 minutes. After that,
raising of the viscosity of the mixture was confirmed.
[0214] Then, the temperature was further increased to 155.degree.
C., and stirred for 3 hours. After 3 hours, 0.1 g (0.6 mmol) of
1,3-divinyltetramethyldisiloxane was added, and the mixture was
stirred at 155.degree. C. for 4 hours.
[0215] After 4 hours, the product was diluted with 250 mL of
toluene, and washed with water 3 times. After washing, the organic
phase was reprecipitated by washing with 1.5 L of methanol several
times and purified to separate an oligomer and a polymer. The
obtained polymer was dried at 60.degree. C. under reduced pressure
overnight, and the first linear organopolysiloxane containing a
vinyl group (A1) (Mn: 277, 734; Mw: 573, 906; IV value (dl/g):
0.89) was produced.
##STR00008##
[0216] [Synthesis of Second Linear Organopolysiloxane Containing a
Vinyl Group (A2)]
[0217] The second linear organopolysiloxane containing a vinyl
group (A2) was synthesized in a manner identical to that of the
first linear organopolysiloxane containing a vinyl group (A1)
except that 0.86 g (2.5 mmol) of 2,4,6,8-tetramethyl
2,4,6,8-tetravinylcyclotetrasiloxane was used.
Example 1
[0218] (Preparation of Silicone Rubber-Based Hardening
Composition)
[0219] 50 parts by weight of the silica filler (C1) was added in
100 parts by weight of the first linear organopolysiloxane having a
vinyl group (A1), and kneaded to prepare a master batch.
[0220] Then, 0.5 parts by weight of platinum (E) was added in the
master batch obtained and kneaded until it became uniform. After
that, 0.2 parts by weight of the linear organohydrogen polysiloxane
(B) was added, and kneaded. Thereby a silicone rubber-based
hardening composition was prepared.
[0221] The weight ratio of the raw material used is shown in Table
1.
[0222] (Evaluation of Silicone Rubber-Based Hardening
Composition)
[0223] <Tear Strength and Tear Stroke>
[0224] The prepared silicone rubber-based hardening composition was
pressed at 170.degree. C. for 10 minutes with 10 mPA to mold a
sheet having a thickness of 1 mm, and primarily hardened.
[0225] Then, the obtained sheet was heated at 200.degree. C. for 4
hours, and secondarily hardened.
[0226] A crescent-shaped test piece was produced based on JIS K
6252 (2001) using the obtained silicone rubber in a sheet shape.
Then, the tear strength and the elongation (stroke) until breaking
of the crescent-shaped test piece were measured according to JIS K
6252 (2001). Moreover, the thickness of the test piece was 1 mm.
The results are shown in Table 1.
[0227] <Tensile Strength and Tensile Elongation Rate>
[0228] The prepared silicone rubber-based hardening composition was
pressed at 170.degree. C. for 10 minutes with 10 MPa to mold a
sheet having a thickness of 1 mm, and primarily hardened.
[0229] Then, the obtained sheet was heated at 200.degree. C. for 4
hours, and secondarily hardened.
[0230] A dumb-bell shaped third test piece was produced based on
JIS K 6251 (2004) using the obtained silicone rubber in a sheet
shape. Then, the tensile strength and the elongation (strain) at
break of the dumb-bell shaped third test piece were measured
according to JIS K 6251 (2004). Moreover, the thickness of the test
piece was 1 mm. The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Examples Comparative Examples 1 2 3 4 5 1 2
3 4 (A1) 100.0 100.0 80.0 100.0 80.0 100.0 100.0 100.0 100.0 (A2)
-- -- 20.0 -- 20.0 -- -- -- -- (B) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
2.0 (C1) 200 m.sup.2/g(*1) 50 70 70 -- -- -- -- -- -- 12 nm(*2)
(C2) 300 m.sup.2/g(*1) -- -- -- 70 70 -- -- -- -- 7 nm(*2) (c1) 200
m.sup.2/g(*1) -- -- -- -- -- 33 -- -- -- 12 nm(*2) (c2) 130
m.sup.2/g(*1) -- -- -- -- -- -- 50 -- -- 16 nm(*2) (c3) 200
m.sup.2/g(*1) -- -- -- -- -- -- -- 50 70 12 nm(*2) (D) 0.5 0.5 0.5
0.5 0.5 0.5 0.5 0.5 0.5 JIS Tear strength 28.3 36.3 40.3 48.0 50.2
13.7 10.9 21.3 12.4 K6252 (N/mm) Stroke 180.1 142.4 182.8 194.6
225.8 15.0 23.3 43.5 6.4 (mm) JIS Tensile strength 9.2 8.2 7.6 10.2
8.6 5.1 9.2 10.3 8.4 K6251 (MPa) Elongation at 1662.4 1255.1 1375.6
1460.3 1389.5 572.8 827.3 993.3 474.9 breaking (%) (*1)Specific
surface area of silica filler (*2)Primarily particle diameter of
silica filler
Example 2
[0231] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 1, except that the content
of the silica filler (C) was changed to 7.0 parts by weight.
[0232] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
Example 3
[0233] (Preparation of Silicone Rubber-Based Hardening
Composition)
[0234] 80 parts by weight of the first linear organopolysiloxane
containing a vinyl group (A1) and 20 parts by weight of the second
linear organopolysiloxane containing a vinyl group were mixed in
advance. Then, 70 parts by weight of the silica filler (C1) was
added in the mixture, and kneaded. Thereby, a master batch was
obtained.
[0235] Then, 0.5 parts by weight of platinum (E) was in the master
batch obtained and kneaded until it became uniform. After that, 0.2
parts by weight of the linear organohydrogen polysiloxane (B) was
added, and kneaded. Thereby a silicone rubber-based hardening
composition was prepared.
[0236] (Evaluation of Silicone Rubber-Based Hardening
Composition)
[0237] A test piece which was obtained by using the obtained
silicone rubber-based hardening composition was evaluated similar
to Example 1. The results are shown in Table 1.
Example 4
[0238] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 2, except that the silica
filler (C2) was used instead of the silica filler (C1).
[0239] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
Example 5
[0240] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 3, except that the silica
filler (C2) was used instead of the silica filler (C1).
[0241] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
Comparative Example 1
[0242] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 1, except that 33 parts by
weight of the silica filler (c1) was used instead of 50 parts by
weight of the silica filler (C1).
[0243] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
Comparative Example 2
[0244] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 1, except that the content
of the silica filler (c2) was used instead of the silica filler
(C1).
[0245] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
Comparative Example 3
[0246] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 1, except that the content
of the silica filler (c3) was used instead of the silica filler
(C1).
[0247] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
Comparative Example 4
[0248] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 1, except that 70 parts by
weight of the silica filler (c3) was used instead of 50 parts by
weight of the silica filler (C1).
[0249] In addition, evaluation of a test piece which was produced
using the obtained silicone rubber-based hardening composition was
carried out in a manner identical to that of Example 1. The results
are shown in Table 1.
[0250] [Results]
[0251] As shown in Table 1, the silicone rubber which is obtained
by hardening the silicone rubber-based hardening composition
containing the silica filler (C1) or (C2) of which the surface is
treated with the silane coupling agent having a trimethylsilyl
group has 28 N/nn or more of the tear strength, and 7.5 MPa or more
of tensile strength. The silicone rubber is excellent in the tear
strength and the tensile strength. In particular, the tear strength
of the silicone rubber obtained in Examples 1 to 5 is remarkably
improved compared with the tear strength of the silicone rubber
obtained in Comparative Examples 1 to 4 which contains the silica
filler (c1) to (c3) of which the surface is not treated with the
silane coupling agent having a trimethylsilyl group. In addition,
the stroke and the elongation at breaking of the silicone rubber in
Examples 1 to 5 are remarkably improved compared with those of the
silicone rubber in Comparative Examples 1 to 4. Thereby, it was
confirmed that the silicone rubber in Examples 1 to 5 had high
elongation even when containing a large amount of the silica
filler.
[0252] Next, it can be understood by the comparison between
Examples 1 and 2 that when the content of the silica filler (C1)
(trimethylsiliyl group-surface treated silica filler (C)) is
increased, the tear strength of the silicone rubber is increased.
In contrast, it can be understood by the comparison between
Comparative Examples 3 and 4 that when the content of the silica
filler (c3) is increased, the tear strength of the silicone rubber
is remarkably decreased. The reason for the large decrease of tear
strength is considered to be because the surface of the silica
filler (c3) is treated with dimethyldichlorosilane, and therefore,
the silica filler (c3) has higher cohesive force compared with the
silica filler (C) of which the surface is treated with the silane
coupling agent having a trimethylsilyl group. When a large amount
of the silica filler (c3) is added, the elongation of the silicone
rubber is remarkably decreased, and because of this, the silicone
rubber easily reaches a breaking point, and the tear strength is
decreased. In contrast, the surface of the silica filler (C) used
in Examples is treated with the silane coupling agent having a
trimethylsilyl group, and therefore the silica filler has lower
cohesive force. As a result, the molecular chains of the silicone
rubber easily slip. Therefore, even when a large amount of the
silica filler is added, the decrease of elongation of the silicone
rubber is small. Due to this, sufficient stiffening effects due to
the silica filler can be obtained.
[0253] In addition, it can be understood by the comparison between
Examples 2 and 4, and the comparison between Examples 3 and 5 that
when the specific surface area of the silica filler (C1) or (C2)
(trimethylsiliyl group-surface treated silica filler (C)) is
increased, not only the tear strength but also the stroke, tensile
strength, and the elongation at breaking are also improved. The
reason for the improvement is considered to be because the
interface between the silica filler and the rubber matrix is
increased by increase of the specific surface area of the silica
filler. Due to this, sufficient stiffening effects due to the
silica filler can be obtained. At the same time, it can be
understood by the comparison between Examples 2 and 4, and the
comparison between Examples 3 and 5 that when the primarily
particle diameter of the silica filler (C1) or (C2)
(trimethylsiliyl group-surface treated silica filler (C)) is
increased, not only the tear strength but also the stroke, tensile
strength, and the elongation at breaking are also improved.
[0254] In addition, it can be understood by the comparison between
Examples 2 and 3, and the comparison between Examples 4 and 5 that
the tear strength, stroke, and elongation at breaking are improved
by using the first linear organopolysiloxane containing a vinyl
group (A1) and the second first linear organopolysiloxane
containing a vinyl group (A2) as the linear organopolysiloxane
containing a vinyl group (A) compared with the case of using only
the first linear organopolysiloxane containing a vinyl group
(A1).
[0255] The following materials were used in Examples 6 to 8 and
Comparative Examples 5 to 8.
[0256] (A1): first linear organopolysiloxane containing a vinyl
group, the content of a vinyl group: 0.13% by mole, and this was
synthesized by the following synthesis scheme.
[0257] (A2): second linear organopolysiloxane containing a vinyl
group, the content of a vinyl group: 0.92% by mole, and this was
synthesized by the following synthesis scheme.
[0258] (B): linear organohydrogen polysiloxane made by Momentive
Inc. trade name: TC-25D
[0259] (C1): silica filler of which the surface is treated with
hyxamethyldisilazane made of Nippon Aerosil Co., Ltd., trade name:
Aerosil.RTM. RX200, specific surface area: 200 m.sup.2/g; average
primary particle diameter: 12 nm; and carbon content: 2.5% by
weight
[0260] (C2): silica filler of which the surface is treated with
hyxamethyldisilazane made of Nippon Aerosil Co., Ltd., trade name:
Aerosil.RTM. RX300, specific surface area: 300 m.sup.2/g; average
primary particle diameter: 7 nm; and carbon content: 3.5% by
weight
[0261] (D1): silica filler of which the surface is treated with
methacryloxypropyltriethoxysilane, made of Nippon Aerosil Co.,
Ltd., trade name: Aerosil.RTM. R711, specific surface area: 200
m.sup.2/g; and average primary particle diameter: 12 nm
[0262] (D2): silica filler of which the surface is treated with
methacryloxypropyltriethoxysilane, specific surface area: 300
m.sup.2/g; and average primary particle diameter: 7 nm
[0263] (E) platinum made by Momentive Inc. trade name: TC-25A
[0264] (f) silica filler of which the surface is treated with
dimethyldichlorosilane, made of Nippon Aerosil Co., Ltd., trade
name: Aerosil.RTM. R974, specific surface area: 200 m.sup.2/g; and
average primary particle diameter: 12 nm
[0265] [Synthesis of First Linear Organopolysiloxane Containing a
Vinyl Group (A1)]
[0266] Based on the following formula (3), the first linear
organopolysiloxane containing a vinyl group (A1) was
synthesized.
[0267] Specifically, 74.7 g (252 mmol) of
octamethylcyclotetrasiloxana, 0.086 g (0.25 mmol) of
2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane, and 0.1 g
of potassium siliconate were put into a 300 mL-separable flask
provided with a cooling pipe, and an impeller, of which the inside
was replaced with Ar gas. Then, the temperature was raised, and the
mixture was stirred at 120.degree. C. for 30 minutes. After that,
raising of the viscosity of the mixture was confirmed.
[0268] Then, the temperature was further increased to 155.degree.
C., and stirred for 3 hours. After 3 hours, 0.1 g (0.6 mmol) of
1,3-divinyltetramethyldisiloxane was added, and the mixture was
stirred at 155.degree. C. for 4 hours.
[0269] After 4 hours, the product was diluted with 250 mL of
toluene, and washed with water 3 times. After washing, the organic
phase was reprecipitated by washing with 1.5 L of methanol several
times and purified to separate an oligomer and a polymer. The
obtained polymer was dried at 60.degree. C. under reduced pressure
overnight, and the first linear organopolysiloxane containing a
vinyl group (A1) (Mn: 277, 734; Mw: 573, 906; IV value (dl/g):
0.89) was produced.
##STR00009##
[0270] [Synthesis of Second Linear Organopolysiloxane Containing a
Vinyl Group (A2)]
[0271] The second linear organopolysiloxane containing a vinyl
group (A2) was synthesized in a manner identical to that of the
first linear organopolysiloxane containing a vinyl group (A1)
except that 0.86 g (2.5 mmol) of 2,4,6,8-tetramethyl
2,4,6,8-tetravinylcyclotetrasiloxane was used.
Example 6
[0272] (Preparation of Silicone Rubber-Based Hardening
Composition)
[0273] 80 parts by weight of the first linear organopolysiloxane
containing a vinyl group (A1) and 20 parts by weight of the second
linear organopolysiloxane containing a vinyl group were mixed in
advance. Then, 64.3 parts by weight of the silica filler (C1) and
5.4 parts by weight of the silica filler (D1) were added in the
mixture, and kneaded. Thereby, a master batch was obtained.
[0274] Then, 0.5 parts by weight of platinum (E) was in the master
batch obtained and kneaded until it became uniform. After that, 0.2
parts by weight of the linear organohydrogen polysiloxane (B) was
added, and kneaded. Thereby a silicone rubber-based hardening
composition was prepared.
[0275] The weight ratio of the raw materials used is shown in Table
2.
[0276] (Evaluation of Silicone Rubber-Based Hardening
Composition)
[0277] <Tear Strength and Tear Stroke>
[0278] The prepared silicone rubber-based hardening composition was
pressed at 170.degree. C. for 10 minutes with 10 MPa to mold a
sheet having a thickness of 1 mm, and primarily hardened.
[0279] Then, the obtained sheet was heated at 200.degree. C. for 4
hours, and secondarily hardened.
[0280] A crescent-shaped test piece was produced based on JIS K
6252 (2001) using the obtained silicone rubber in a sheet shape.
Then, the tear strength and the elongation (stroke) until breaking
of a crescent-shaped test piece were measured according to JIS K
6252 (2001). Moreover, the thickness of the test piece was 1 mm.
The results are shown in Table 2.
[0281] <Tensile Strength and Tensile Elongation Rate>
[0282] The prepared silicone rubber-based hardening composition was
pressed at 170.degree. C. for 10 minutes with 10 MPa to mold a
sheet having a thickness of 1 mm, and primarily hardened.
[0283] Then, the obtained sheet was heated at 200.degree. C. for 4
hours, and secondarily hardened.
[0284] A dumb-bell shaped third test piece was produced using the
obtained silicone rubber in a sheet shape according to JIS K 6251
(2004). Then, the tensile strength and the elongation (strain)
until breaking of the dumb-bell shaped third test piece were
measured according to JIS K 6251 (2004). Moreover, the thickness of
the test piece was 1 mm. The results are shown in Table 2.
[0285] <Hardness>
[0286] The prepared silicone rubber-based hardening composition was
pressed at 170.degree. C. for 10 minutes with 10 MPa to mold a
sheet having a thickness of 1 mm, and primarily hardened. Then, the
obtained sheet was heated at 200.degree. C. for 4 hours, and
secondarily hardened.
[0287] Then, the type A durometer hardness of the silicone rubber
in a sheet shape was measured based on JIS K 6253 (2006).
TABLE-US-00002 TABLE 2 Examples Comparative Examples 6 7 8 9 10 5 6
(A1) 80.0 100.0 100.0 80.0 100.0 100 100 (A2) 20.0 -- -- 20.0 -- --
-- (B) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 (C1) 200 m.sup.2/g (*1) 64.3 --
-- 70 -- -- -- 12 nm (*2) (C2) 300 m.sup.2/g (*1) -- 66 60 -- 70 --
-- 7 nm (*2) (D1) 200 m.sup.2/g (*1) 5.4 -- -- -- -- 70 12 nm (*2)
(D2) 300 m.sup.2/g (*1) -- 4.2 9.0 -- -- -- -- 7 nm (*2) (f) 200
m.sup.2/g (*1) -- -- -- -- -- -- 70 12 nm (*2) (E) 0.5 0.5 0.5 0.5
0.5 0.5 0.5 JIS Tear strength (N/mm) 38.3 42.8 42.2 40.3 41.5 11.3
12.4 K6252 Stroke (mm) 170.0 156.2 249.4 182.8 207.6 6.6 6.4 JIS
Tensile strength (MPa) 7.2 7.1 6.8 7.6 6.9 2.2 8.4 K6251 Elongation
at breaking (%) 1299.9 926.9 1043.6 1375.6 1008.2 131.2 474.9 JIS
Type A durometer hardness 58.7 61.8 63.0 49.3 54.0 74.7 80.2 K6253
(shoreA) (*1): Specific surface area of silica filler (*2):
Primarily particle diameter of silica filler
Example 7
[0288] 66 parts by weight of the silica filler (C2), and 4.2 parts
by weight of the silica filler (D2) were added in 100 parts by
weight of the first linear organopolysiloxane having a vinyl group
(A1), and kneaded to prepare a master batch.
[0289] Then, 0.5 parts by weight of platinum (E) was in the master
batch obtained and kneaded until it became uniform. After that, 0.2
parts by weight of the linear organohydrogen polysiloxane (B) was
added, and kneaded. Thereby a silicone rubber-based hardening
composition was prepared.
[0290] Similar to Example, 6, the test piece was produced using the
obtained silicone rubber-based hardening composition, and
evaluated. The results are shown in Table 2.
Example 8
[0291] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 7, except that the content
of the silica filler (C1) and the silica filler (D2) was changed to
60 parts by weight and 9 parts by weight respectively.
[0292] Similar to Example, 6, the test piece was produced using the
obtained silicone rubber-based hardening composition, and
evaluated. The results are shown in Table 2.
Example 9
[0293] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 6, except that 70 parts by
weight of the silica filler (C1) was used instead of 64.3 parts by
weight of the silica filler (C1) and 5.4 parts by weight of the
silica filler (D1).
[0294] Similar to Example, 6, the test piece was produced using the
obtained silicone rubber-based hardening composition, and
evaluated. The results are shown in Table 2.
Example 10
[0295] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 7, except that 70 parts by
weight of the silica filler (C2) was used instead of 66 parts by
weight of the silica filler (C2) and 4.2 parts by weight of the
silica filler (D2).
[0296] Similar to Example, 6, the test piece was produced using the
obtained silicone rubber-based hardening composition, and
evaluated. The results are shown in Table 2.
Comparative Example 5
[0297] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 10, except that the silica
filler (D1) was used instead of the silica filler (C2).
[0298] Similar to Example 6, the test piece was produced using the
obtained silicone rubber-based hardening composition, and
evaluated. The results are shown in Table 2.
Comparative Example 6
[0299] The silicone rubber-based hardening composition was obtained
in a manner identical to that of Example 10, except that the silica
filler (f) was used instead of the silica filler (C2).
[0300] Similar to Example 6, the test piece was produced using the
obtained silicone rubber-based hardening composition, and
evaluated. The results are shown in Table 2.
[0301] [Results]
[0302] As shown in Table 2, the silicone rubber which is obtained
by hardening the silicone rubber-based hardening composition
containing the silica filler (C1) or (C2), and the silica filler
(D1) or (D2) is excellent in the balance between the tear strength,
tensile strength, and hardness compared with the silicone rubber in
Examples 9 to 11 and Comparative Examples 5 and 6 which is obtained
by hardening the silicone rubber-based hardening composition
containing only the silica filler (C1), (C2), (D1), or (f).
[0303] Specifically, it can be understood by the comparison between
Example 6 and Example 9, and comparison between Examples 7 and 8,
and Example 10 that the silicone rubber in Examples 6 to 8 has
improved hardness compared with the silicone rubber in Examples 9
and 10 which contains only the silica filler (C1) or (C2).
[0304] In addition, it can be understood by the comparison between
Examples 7 and 8 and Comparative Example 5 that the silicone rubber
in Example 7 and 8 has remarkably improved tear strength and
tensile strength in addition to the stroke and elongation at
breaking, compared with the silicone rubber in Comparative Example
5 which contains only the silica filler (D1).
[0305] Furthermore, it is also understood by the comparison between
Example 7 and 8 and Comparative Example 6 that the silicone rubber
in Examples 7 and 8 has remarkably improved tear strength, stroke,
and elongation at breaking compared with the silicone rubber in
Comparative Example 6 which contains only the silica filler (f),
and does not contain both of the silica fillers (C) and (D).
INDUSTRIAL APPLICABILITY
[0306] The silicone rubber obtained by hardening the silicone
rubber-based hardening composition according to the present
invention is excellent in mechanical strength such as tensile
strength and tear strength, in particular, tear strength.
Therefore, the molded article which is obtained by using the
silicone rubber-based hardening composition and the medical tube
which is obtained by using the molded article have high mechanical
strength. In other words, according to the present invention, it is
possible to produce a medical catheter made of silicone rubber
which is excellent in scratch resistance and kink resistance, in
particular, scratch resistance.
[0307] In other words, the present invention is extremely
industrially important.
* * * * *