JP2013189551A - Silicone elastomer composition, elastic member for medical appliance, and tube for medical use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone elastomer composition for forming a cured product having suitable hardness for a tube for medical use while having no yield point, and still showing excellent elongation property as well as strength at the time of cutting, and provide an elastic member for medical use and a tube for medical use made of this composition.SOLUTION: A silicone elastomer composition contains (A) 100 parts by weight of organopolysiloxane of a crude rubber type containing the following ingredients at a mass ratio of 10/90-95/5: (A1) organopolysiloxane that has the alkenyl group only at molecular chain terminal, (A2) organopolysiloxane that has an alkenyl group at molecular chain terminal and side chain and has a content of the alkenyl group in less than 0.10 mass%, (B) organopolysiloxane having a content of the alkenyl group in 0.50-20.0 mass%, (C) organohydrogenpolysiloxane, (D) an inorganic filler, and (E) an addition reaction catalyst. This silicone elastomer composition gives a cured product having 40 or more of hardness, 500% or more of elongation at cutting, and 7.0 MPa or more of tensile strength.

Description

The present invention relates to a novel addition-curable silicone elastomer composition that provides suitable hardness, physical strength and elongation at break particularly required for medical tubes. The present invention also relates to a molded and cured product of the silicone elastomer composition, an elastic member for a medical device comprising the same, and particularly to a medical tube. More specifically, the hardness of the cured product measured in accordance with JIS K6253 durometer hardness test type A (hereinafter sometimes referred to as “JIS-A hardness” or “hardness”) is 40 or more, and the surface tack There is no feeling, the elongation at break is 500% or more, and when it is molded into a tube shape because of excellent tensile strength and tear strength, it can form a silicone elastomer that can avoid the risk of breakage during treatment, especially for medical use The present invention relates to an addition-curable silicone elastomer composition useful for forming a catheter or a medical drain tube.

Silicone elastomers are excellent in transparency, heat resistance, cold resistance, hardness, physical strength, durability, and safety, and thus are used in a wide range of applications including medical materials (for example, Patent Documents 1 to Patents). Reference 5). In particular, a medical tube is an example of an elastic member for a medical instrument that takes advantage of these characteristics. A medical tube made of a silicone elastomer is physiologically inactive and has little reaction to a body tissue when touched by a living body. Therefore, the medical tube is used as a catheter or a drain tube used in various medical applications. For example, medical tubes are inserted into body cavities such as the thoracic cavity and abdominal cavity, luminal portions such as the digestive tract and ureter, blood vessels, etc., and used for draining body fluids and injecting infusions of medicinal solutions, nutrients, contrast agents, etc. Examples include a drainage tube of a suction device for removing drainage of blood and pus after operation, a tube for nutrient intake, and the like.

As a silicone elastomer for such a medical tube, the addition reaction curable type silicone elastomer composition does not produce a by-product due to the decomposition of the organic peroxide unlike the organic peroxide curable type type. Can be suitably applied to the above applications. However, the known addition reaction curable silicone elastomer composition (see, for example, Patent Document 6) has insufficient tensile strength, tear strength, and elongation at break at a hardness of 40 or more required for medical tubes. It is. Also, if the hardness is less than 40 in order to satisfy these physical characteristics, deformation may occur even when an elastic load is applied, and there is a risk of hindering the handling of the catheter after or during surgery. It was something that could not be done.

On the other hand, by using an organopolysiloxane resin composed of R ₃ SiO _1/2 units and SiO _4/2 units or the like (see, for example, Patent Document 3 or Patent Document 7), if the physical properties are to be improved, There is a problem that stickiness or tackiness is caused, handling properties are deteriorated, and it is difficult to suitably form the elastic member for a medical instrument such as a medical tube.

In addition, in addition reaction curable silicone elastomer compositions, it is possible to perform secondary vulcanization (post cure) after primary vulcanization in order to improve physical properties, but the cycle time required for production is also possible. There is a concern that will increase. As described above, as a medical tube, a cured product having sufficient physical properties (particularly hardness, durability, and no yield point of an elastic body) with only primary vulcanization and excellent safety can be obtained. An addition-curable silicone elastomer composition is strongly desired.

Japanese Patent Laid-Open No. 55-040508 JP 61-255664 A Japanese Unexamined Patent Publication No. 08-323857 JP 2011-162714 A JP 2012-012448 JP 2007-217713 A Japanese Unexamined Patent Publication No. 07-331079

The object of the present invention is that the JIS-A hardness is 40 or more, but there is no tackiness on the surface, the handleability is excellent, the tear strength and the tensile strength are high, and the risk of breakage can be avoided for a long time, 500% An object of the present invention is to provide a silicone elastomer composition capable of forming a silicone elastomer that does not break even when the material is stretched as described above and does not have an elastic yield point.

Furthermore, an object of the present invention is to provide a molded cured product of the silicone elastomer composition and an elastic member for a medical device using the same. In particular, it has excellent characteristics such as moldability, safety, durability, and tensile strength required for medical tubes, and the above-mentioned hardness is 40 or more, and it does not permanently deform even when an elastic load is applied. It is an object to provide a medical tube, particularly a medical catheter or a medical drain tube.

As a result of intensive studies, the inventors of the present invention are organopolysiloxanes having a raw rubber-like silicon atom-bonded alkenyl group at room temperature, having a low content of silicon atom-bonded alkenyl groups and different bonding sites for the alkenyl groups. (A1 component which is terminal alkenyl functional and (A2) component which is terminal / side chain alkenyl functional) and (B) organopolysiloxane having a high content of alkenyl groups, and inorganic filling The present inventors have found that the above problems can be solved by using an addition-curable silicone elastomer composition containing an agent and a molded cured product thereof, and have reached the present invention.

Specifically, the inventors have
(A) 100 parts by mass of an organopolysiloxane having a raw rubber-like silicon atom-bonded alkenyl group at room temperature, containing the components (A1) and (A2) in a mass ratio of 10/95 to 95/5 (A1) gel permeation chromatography An organopolysiloxane having a number average molecular weight based on a polystyrene-equivalent number average molecular weight measured by chromatography (GPC) of 2,000 or more and having an average of two or more silicon atom-bonded alkenyl groups only at the molecular chain ends;
(A2) The number average degree of polymerization based on the polystyrene-reduced number average molecular weight measured by gel permeation chromatography (GPC) is 2000 or more, and the molecular chain terminal and side chain have an average of 3 or more alkenyl groups. And an organopolysiloxane having an alkenyl group content of less than 0.10% by mass (B) and an alkenyl group content of 0.50 to 20.0% by mass 1.0-20 parts by mass ,
(C) 0.3-20 parts by mass of an organopolysiloxane having an average of 2 or more silicon-bonded hydrogen atoms in one molecule;
(D) 10 to 100 parts by mass of an inorganic filler (E) addition reaction catalyst containing a catalyst amount,
After press curing at 120 ° C for 10 minutes,
The hardness measured according to JIS K6253 durometer hardness test type A is 40 or more,
The elongation at break measured according to JIS K6251 is 500% or more,
In the tensile stress-elongation curve obtained in accordance with JIS K6251, a cured product having no maximum point of tensile stress, which is the yield point of the cured product before cutting, and having a tensile strength of 7.0 MPa or more. The present inventors have found that the above problems can be solved by the silicone elastomer composition to be provided, and have reached the present invention.

In particular, when the component (B) is a mixture of alkenyl group-containing organopolysiloxanes containing the following components (B1) and (B2) in a mass ratio of 10/90 to 90/10: The inventors have found that it can be solved better and have reached the present invention.
(B1) Organopolysiloxane having a number average degree of polymerization based on a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (GPC) of 2000 or more and an alkenyl group content of 0.50 to 5.0% by mass (B2) The number average degree of polymerization based on the number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) is 100 or less, has a silanol group at the end of the molecular chain, and has an alkenyl group content of 1 Organopolysiloxane of 0.02 to 20.0% by mass

When the inorganic filler (C) is an inorganic filler containing 50% by mass or more of fumed silica having a specific surface area by the BET method in the range of 150 to 350 m ² / g, The inventors have found that the problem can be solved well and have reached the present invention.

Furthermore, in addition to the above components (A) to (E), optionally,
(F) Dimethylpolysiloxane having a silanol group at the molecular chain terminal and having a number average degree of polymerization of 100 or less based on polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (GPC) Containing, and
(X1) Organopolysiloxane in which both ends of the molecular chain are blocked with a trialkylsilyl group (excluding those corresponding to the above component (B) or (C)), or (X2) R ¹ ₃ SiO _1/2 A unit (wherein R ¹ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms) and a SiO _4/2 unit. Organopolysiloxane resin consisting essentially of
The present inventors have found that the above problem can be better solved by a silicone elastomer composition having a sum of the contents of less than 1% by mass of the entire composition.

Further, the present inventors have found that the above problems can be solved by a molded cured product of the silicone elastomer composition, an elastic member for a medical device using the silicone elastomer composition, particularly a medical tube, and have reached the present invention.

According to the present invention, although it has a suitable hardness (JIS-A hardness of 40 or more) required for a medical tube, it has no surface tackiness, is easy to handle, and has high tear strength and tensile strength for a long time. It is possible to provide a silicone elastomer composition capable of avoiding the risk of breakage, capable of forming a silicone elastomer that does not break even when the material is stretched to 500% or more and does not have an elastic yield point.

Moreover, according to the present invention, it is possible to provide a molded cured product of the silicone elastomer composition, an elastic member for a medical device using the same, particularly a medical tube.

It is a graph (yield point: none) of the tensile stress-elongation curve in Example 1 of Table 1. It is a graph of the tensile stress-elongation curve in Example 2 of Table 1 (yield point: none). It is a graph (yield point: there) of the tensile stress-elongation curve in the comparative example 2 of Table 1. FIG. It is a graph of the tensile stress-elongation curve in Example 5 of Table 2 (yield point: none). It is a graph (yield point: none) of the tensile stress-elongation curve in Example 6 of Table 2. It is a graph (yield point: there) of the tensile stress-elongation curve in the comparative example 3 of Table 2. FIG. 6 is a graph of a tensile stress-elongation curve in Comparative Example 4 in Table 2 (yield point: present).

Hereinafter, the silicone elastomer composition of the present invention will be described in detail.
The component (A) is a main component of the silicone elastomer composition according to the present invention, and is a characteristic component in realizing its physical characteristics. Specifically, the component (A) is an organopolysiloxane having a raw rubber-like silicon atom-bonded alkenyl group at room temperature, wherein the content of silicon atom-bonded alkenyl groups is small and the bonding sites of the alkenyl groups are different. ((A1) component and (A2) component) are used together in a mass ratio of 10/95 to 95/5.

Component (A) has a number average degree of polymerization based on the number average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) (hereinafter simply referred to as “number average degree of polymerization”) of 2000 or more, and is a raw rubber at room temperature. The components ((A1) component and (A2) component) that are different from each other and have different alkenyl group bonding sites can be used. In addition, these (A) components can remove low molecular siloxane with a polymerization degree of 10 or less in advance by a known means such as stripping so that the content thereof is 1000 ppm or less, and are preferable.
R _a SiO _{(4-a) / 2}
(In the formula, R is an unsubstituted or substituted monovalent hydrocarbon group having the same or different carbon number of 1 to 10, preferably 1 to 8, and b is 1.8 to 2.5, preferably 1.9. It is a positive number in the range of ~ 2.1.)

Here, the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and pentyl. Group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, alkyl group such as decyl group, aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenylethyl group, phenylpropyl group Aralkyl groups such as aralkyl groups, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, octenyl groups, etc., and some or all of the hydrogen atoms of these groups are fluorine, Substituted by halogen atoms such as bromine and chlorine, cyano groups, etc., such as chloromethyl group, chloropropylene Group, bromoethyl group, trifluoropropyl group, but cyanoethyl group and the like, Preferably, at least 90% of all R are methyl groups.

The component (A1) is an organopolysiloxane having a number average degree of polymerization of 2000 or more and an average of 2 or more silicon atom-bonded alkenyl groups only at the molecular chain ends, and exhibits a raw rubber shape at room temperature. Due to its structure, the content of the silicon-bonded alkenyl group is determined by the degree of polymerization and the presence or absence of branching of the main chain, but the content of the alkenyl group is 0.001 to 0.050% by mass. A linear or partially branched organopolysiloxane is preferable, and a linear organopolysiloxane having an average of two silicon-bonded alkenyl groups at both ends of the molecular chain is particularly preferable.

The component (A1) has a linear structure in which the molecular chain end is blocked with a triorganosiloxy group having a silicon-bonded alkenyl group and the main chain is composed of repeating diorganosiloxane units. It may be a branched structure. Regarding the molecular weight, the number average degree of polymerization is 2000 or more (2,000 to 100,000) and a raw rubber-like one, preferably 3,000 or more (3,000 to 8,000). If the number average degree of polymerization is less than the lower limit, a sufficient rubber feeling may not be obtained, and the surface may be sticky or tacky, and even if used in combination with the component (A2), the object of the present invention cannot be achieved.

The component (A2) has a number average degree of polymerization of 2,000 or more, an average of three or more alkenyl groups at the molecular chain ends and side chains, and an alkenyl group content of 0.10 mass. It is an organopolysiloxane that is less than 50% and exhibits a raw rubber shape at room temperature. The component (A2) has a silicon atom-bonded alkenyl group at the molecular chain terminal and side chain, but the alkenyl group content must be less than 0.10% by mass, and 0.095% by mass. % Is preferable, and the range of 0.001 to 0.090% by mass is particularly preferable. Most preferably, the content of the alkenyl group of the component (A2) is in the range of 0.010 to 0.080% by mass.

The structure of the component (A2) has a linear structure in which the end of the molecular chain is blocked with a triorganosiloxy group having a silicon-bonded alkenyl group, the main chain is composed of repeating diorganosiloxane units, and One or more diorganosiloxane units having an alkenyl group in a part of the chain are contained. The component (A2) contains two or more diorganosiloxane units in which one end of the molecular chain is blocked with a triorganosiloxy group having a silicon-bonded alkenyl group and the alkenyl group is part of the main chain. It may be a linear organopolysiloxane. Further, the component (A2) may partially have a branched structure. Regarding the molecular weight, the number average degree of polymerization is 2000 or more (2,000 to 100,000) and a raw rubber-like one, preferably 3,000 or more (3,000 to 8,000). If the number average degree of polymerization is less than the lower limit, a sufficient rubber feeling may not be obtained, and the surface may become sticky or tacky, and the object of the present invention cannot be achieved even when used in combination with the component (A1).

(A) component of this invention uses said (A1) component and (A2) component together by mass ratio of 10 / 90-95 / 5, and uses (A1) component more than (A2) component. It is more preferable to do. Specifically, the mass ratio of component (A1) / component (A2) is preferably in the range of 30/70 to 90/10, more preferably 50/50 to 85/15, It is especially preferable that it is 40-80 / 20. On the other hand, when the ratio of the component (A1) or the component (A2) exceeds the upper limit or the lower limit, even when these components are used in combination, physical properties such as hardness and elongation are deteriorated, and the surface is sticky or tacky. As a result, the object of the present invention cannot be sufficiently achieved. In forming the composition, these components may be mixed in advance, but may be mixed separately with other components, and the preparation process does not adversely affect the characteristics.

In the silicone elastomer composition according to the present invention, the component (B) is a component that gives desired permanent elongation characteristics when used in combination with the component (A), and has a higher alkenyl group content than the component (A). It is characterized by. Specifically, component (B) is an organopolysiloxane having an alkenyl group content of 0.50 to 20.0% by mass, and when used in combination with component (A), realizes its physical characteristics. It is an ingredient to do. In particular, the component (B) is preferably an organopolysiloxane having an alkenyl group content of 0.50 to 15.0% by mass, and is an organopolysiloxane having two or more different degrees of polymerization. More preferred.

More specifically, the component (B) is preferably a mixture of alkenyl group-containing organopolysiloxanes containing the following components (B1) and (B2) in a mass ratio of 5/95 to 90/10.
(B1) Organopolysiloxane (B2) having a number average degree of polymerization of 2000 or more and an alkenyl group content of 0.50 to 5.0% by mass. The number average degree of polymerization is 100 or less, and silanol is present at the end of the molecular chain. Organopolysiloxane having a alkenyl group and a alkenyl group content of 1.00 to 20.0% by mass

The component (B1) is an organopolysiloxane having a number average degree of polymerization of 2,000 or more and an alkenyl group content of 0.50 to 5.0% by mass, and exhibits a raw rubber shape at room temperature. The component (B1) has a silicon atom-bonded alkenyl group at the molecular chain terminal or side chain, and preferably has an alkenyl group in the side chain, and the content of silicon atom-bonded alkenyl group is 0.50. It is -5.0 mass%, It is preferable that it is less than 0.75-3.0 mass%, and it is especially preferable that it is the range of 1.0-2.5 mass%.

The structure of the component (B1) is that the molecular chain end is blocked with a triorganosiloxy group, the main chain has a linear structure composed of repeating diorganosiloxane units, and the terminal or side chain is partly The organosiloxane unit having an alkenyl group is included in an amount such that the content of the alkenyl group is 0.50 to 5.0% by mass. The component (B1) may partially have a branched structure. Regarding the molecular weight, the number average degree of polymerization is 2000 or more (2,000 to 100,000) and a raw rubber-like one, preferably 3,000 or more (3,000 to 8,000). When the number average degree of polymerization and the alkenyl group content are in the above ranges, properties such as tensile strength, tear strength, elongation at break and the like are further improved by the combined use with the component (A).

The component (B2) has a number average degree of polymerization of 100 or less, a silicon atom-bonded hydroxyl group (silanol group) at the molecular chain terminal, and an alkenyl group content of 1.00 to 20.0% by mass. It is preferable to contain some organopolysiloxane. The component (B2) has a lower degree of polymerization than the component (B1), and has silanol groups at both ends of the molecular chain, thus causing the cured product to be sticky and tacky, and to handleability and moldability. There is an advantage that a large number of crosslinking reactive groups can be introduced into the composition without adversely affecting the composition. Such a component (B2) is represented by the following structural formula.

HO (R ² ) ₂ SiO— (R ² ₂ SiO) _n1 (R ² R ³ SiO) _n2 —Si (R ² ) ₂ OH
(In the formula, R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms having no aliphatic unsaturated bond, and preferably 90% or more thereof is a methyl group or a phenyl group. R ³ is alkenyl. A group, preferably an alkenyl group having 2 to 6 carbon atoms, particularly preferably a vinyl group or a hexenyl group, wherein (n1 + n2) is a number in the range of 0 to 98, and n1 and n2 Is a number in the range where the alkenyl group content is 1.00 to 20.0 mass%.)

The component (B) of the present invention is preferably a combination of the above components (B1) and (B2) at a mass ratio of 5/95 to 90/10, and the component (B1) as the component (A2). It is more preferable to use more. Specifically, the mass ratio of component (B1) / component (B2) is preferably in the range of 5/95 to 50/50, more preferably 5/95 to 40/60, and 10 / It is especially preferable that it is 90-30 / 70. In forming the composition, these components may be mixed in advance, but may be mixed separately with other components, and the preparation process does not adversely affect the characteristics.

In the present composition, the content of the component (B) is 1.0 to 20 parts by mass, preferably 1.5 to 15 parts by mass with respect to 100 parts by mass of the component (A). More preferably, it is 0-10 mass parts. If the usage-amount of (B) component is less than the said minimum, the hardness of hardened | cured material may become inadequate. On the other hand, when the amount of component (B) used exceeds the upper limit, the elasticity is lowered, the elongation at break is less than 500%, and sufficient tensile strength, tear strength, etc. may not be realized.

The organopolysiloxane of component (C) is a crosslinking agent of the present composition, and is an organopolysiloxane having an average of 2 or more silicon-bonded hydrogen atoms in one molecule. The bonding position of the silicon atom-bonded hydrogen atom in the component (B) is not particularly limited, and is a molecular chain end, a molecular chain side chain, or a molecular chain end and a molecular chain side chain. In addition, as silicon atom bonding groups other than hydrogen atoms in component (B), alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group; cycloalkyl such as cyclopentyl group, cyclohexyl group, etc. Group; aryl group such as phenyl group, tolyl group and xylyl group; aralkyl group such as benzyl group and phenethyl group; fat such as halogenated alkyl group such as 3,3,3-trifluoropropyl group and 3-chloropropyl group And monovalent hydrocarbon groups not containing a group unsaturated bond are exemplified, preferably an alkyl group and an aryl group, and particularly preferably a methyl group and a phenyl group.

The molecular structure of the component (C) is not limited, and examples thereof include linear, branched, partially branched linear, cyclic, dendritic (dendrimeric), and resinous. Component (C) is a single polymer having these molecular structures, a copolymer comprising these molecular structures, or a mixture thereof.

(C) Although the viscosity of a component is not limited, It is preferable that the viscosity (measured with a rotational viscometer etc.) in 25 degreeC is 1-100000 mPa * s, Furthermore, it is preferable that it is 1-10000 mPa * s, Especially Is preferably 1 to 5000 mPa · s.

Examples of such component (C) include trimethylsiloxy group-capped methylhydrogen polysiloxane with molecular chain at both ends, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer with molecular chain at both ends, and dimethylhydrogen with molecular chain at both ends. Siloxy group-blocked dimethylpolysiloxane, molecular chain both ends dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane, molecular chain both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, cyclic methylhydrogenpolysiloxane From a siloxane unit represented by the formula: (CH ₃ ) ₃ SiO _1/2 and a siloxane unit represented by the formula: (CH ₃ ) ₂ HSiO _1/2 and a siloxane unit represented by the formula: SiO _4/2 Organosiloxane, tetra Examples include (dimethylhydrogensiloxy) silane and methyltri (dimethylhydrogensiloxy) silane.

In the present composition, the content of the component (C) is 0.3 to 20 parts by mass with respect to 100 parts by mass of the component (A), and the silicon-bonded alkenyl in the component (A) and the component (B) The amount of silicon-bonded hydrogen atoms in this component is preferably from 1.0 to 20 mol, more preferably from 1.0 to 10 mol, particularly preferably from 1 mol of the group. It is the quantity used as 0.0-6 mol. If the content of this component is less than the lower limit of the above range, crosslinking will be insufficient, resulting in insufficient hardness of the cured silicone elastomer, or stickiness and tackiness on the surface. As a result, the object of the present invention cannot be sufficiently achieved. On the other hand, if the upper limit of the above range is exceeded, hydrogen gas is generated from the resulting cured silicone elastomer, and foaming may be observed in the molded product, or it may be difficult to release from the mold. . The suitable compounding quantity is 0.4-10 mass parts with respect to 100 mass parts of (A) component, Especially preferably, it is the range of 0.5-5 mass parts.

The component (D) is an inorganic filler, which is essential for giving sufficient strength to the silicone elastomer, and is not particularly limited as long as it gives the hardness and permanent elongation of the silicone elastomer described later. Two or more kinds of inorganic fillers can be used. Reinforcing fillers such as fine silica powder and fumed titanium oxide; Non-reinforcing fillers such as diatomaceous earth, aluminosilicate, iron oxide, zinc oxide, calcium carbonate; aluminum oxide, molten Thermally conductive fillers such as silica and silver powder can be used. As the silica fine powder, for example, dry silica such as fumed silica or synthetic silica such as wet silica can be used, and the specific surface area measured by the BET method is preferably 150 m ² / g or more, and 250 to 350 m ² / More preferably, it is g. The surface of the fine silica powder may be surface-treated with a silicon compound such as organoalkoxysilane, organohalosilane, or organosilazane; a cyclic diorganosiloxane oligomer such as octamethyltetrasiloxane or decamethylpentasiloxane.

In particular, from the viewpoint of improving hardness, tensile strength, and tear strength, the inorganic filler as component (D) is a fumed silica whose specific surface area by the BET method is in the range of 150 to 350 m ² / g. Preferably, the inorganic filler contains 50% by mass or more, and the use of an inorganic filler containing 90 to 100% by mass of fumed silica having a specific surface area of 150 to 350 m ² / g by the BET method is preferable. Particularly preferred. Further, the specific surface area of the fumed silica by the BET method is preferably 175 to 350 m ² / g, and the center value is particularly preferably 200 to 325 m ² / gm ² / g. In addition, it is also preferable to use an inorganic filler containing two or more fumed silicas having different center values of specific surface areas according to the BET method. If the specific surface area of the fumed silica in the inorganic filler by the BET method is smaller than the lower limit, not only the sufficient strength cannot be obtained, but the transparency of the molded product may be lowered. Further, when a large amount of silica fine powder (especially untreated fumed silica or the like) having a specific surface area by BET method of less than 150 m ² / g is blended, the hardness of the cured product may decrease.

The inorganic filler (for example, fumed silica) as the component (D) may be used as it is, but it is possible to use a pre-treated with a surface hydrophobizing agent or a surface treatment during kneading with silicone oil. It is preferable to use it by adding an agent to the treatment. As these surface treatment agents, any known ones such as alkylalkoxysilanes, alkylchlorosilanes, alkylsilazanes, silane coupling agents, titanate treatment agents and fatty acid esters may be used alone, and two or more thereof may be used simultaneously or at different timings. You may use in.

In addition, the blending amount of the (D) inorganic filler is preferably 10 to 100 parts by weight, particularly 25 to 75 parts by weight with respect to 100 parts by weight of the component (A). If the blending amount is less than the lower limit, sufficient hardness and physical strength cannot be obtained, and if the upper limit is exceeded, the elasticity is lowered, particularly the tensile strength and elongation at break are lowered, and it is used as a medical tube. May not be suitable.

The (E) component addition reaction catalyst is a catalyst for accelerating the curing of the present composition, and examples thereof include a platinum-based catalyst, a palladium-based catalyst, and a rhodium-based catalyst. In particular, a platinum group metal catalyst is preferable. As component (E), platinum fine powder, platinum black, chloroplatinic acid, platinum tetrachloride, alcohol-modified chloroplatinic acid, platinum olefin complex, platinum alkenylsiloxane complex, platinum carbonyl complex, and these platinum-based catalysts Platinum catalyst such as thermoplastic organic resin powder such as methyl methacrylate resin, polycarbonate resin, polystyrene resin, silicone resin, etc .; formula: [Rh (O ₂ CCH ₃ ) ₂ ] ₂ , Rh (O ₂ CCH ₃ ) ₃ , Rh ₂ (C ₈ H ₁₅ O ₂ ) ₄ , Rh (C ₅ H ₇ O ₂ ) ₃ , Rh (C ₅ H ₇ O ₂ ) (CO) ₂ , Rh (CO) [Ph ₃ P] (C ₅ H ₇ O ₂ ), RhX ₃ [(R) ₂ S] ₃ , (R ^′ ₃ P) ₂ Rh (CO) X, (R ² ₃ P) ₂ Rh (CO) H, Rh ₂ X ₂ Y ₄ , H _f A rhodium catalyst represented by Rh _g (En) _h Cl _i or Rh [O (CO) R] _3-j (OH) _j (wherein X is a hydrogen atom, a chlorine atom, bromine Y is an alkyl group such as a methyl group or an ethyl group, CO, C ₈ H ₁₄ , or 0.5C ₈ H ₁₂ , and R is an alkyl such as a methyl group, an ethyl group, or a propyl group A cycloalkyl group such as a cycloheptyl group and a cyclohexyl group; or an aryl group such as a phenyl group and a xylyl group, and R ^′ is an alkyl group such as a methyl group, an ethyl group, and a propyl group; a phenyl group, a tolyl group, and a xylyl group An aryl group such as a group; an alkoxy group such as a methoxy group or an ethoxy group; or an allyloxy group such as a phenoxy group; En is an olefin such as ethylene, propylene, butene, hexene; f is 0 or 1; g is 1 or 2, h is an integer from 1 to 4, i is 2, 3, or 4 and j is 0 or 1.); Formula: Ir (OOCCH ₃ ) ₃ , Ir ( An iridium catalyst represented by C ₅ H ₇ O ₂ ) ₃ , [Ir (Z) (En) ₂ ] ₂ , or [Ir (Z) (Dien)] ₂ (wherein Z is a chlorine atom, a bromine atom) And an iodine atom, or an alkoxy group such as a methoxy group and an ethoxy group, En is an olefin such as ethylene, propylene, butene, and hexene, and Dien is cyclooctadiene).

In the present composition, the content of the component (E) is a catalytic amount, but more specifically, the platinum group metal in the component is expressed by weight relative to the total amount of the component (A) and the component (B). The amount is 0.01 to 1000 ppm, and preferably 0.1 to 500 ppm. This is because when the content of this component is less than the lower limit of the above range, the resulting silicone elastomer composition will not be sufficiently cured, while the silicone elastomer obtained will be obtained even if the amount exceeds the upper limit of the above range. This is because the curing rate of the composition is not significantly improved.

The silicone elastomer composition according to the present invention essentially comprises the above components (A) to (E), but optionally (F) has a silanol group at the molecular chain terminal and has a number average degree of polymerization. It is preferable to contain 100 or less dimethylpolysiloxane. The component (F) does not have an addition reaction functional group (that is, a functional group that can participate in a hydrosilylation addition reaction consisting of an alkenyl group such as a vinyl group and a silicon atom-bonded hydrogen atom (SiH group)). Is 100 or less dimethylpolysiloxane, and is represented by the following average molecular formula.

HO (R ² ) ₂ SiO— (R ² ₂ SiO) _n —Si (R ² ) ₂ OH
(In the formula, R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms having no aliphatic unsaturated bond, and preferably 90% or more thereof is a methyl group or a phenyl group. Number in the range of 98)

The component (F) is particularly preferably used for the surface treatment of fumed silica that is the component (D). (F) A component is an arbitrary component which can be mix | blended as needed, The compounding quantity is 0.1-50 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-20 mass parts It is. When this compounding quantity exceeds 50 mass parts, there exists a possibility that the rubber | gum physical property of hardened | cured material may fall remarkably.

The silicone elastomer composition according to the present invention further has a number average degree of polymerization based on a polystyrene-equivalent number average molecular weight measured by (G) gel permeation chromatography (GPC), and exhibits a rubbery form at room temperature or higher. The degree of polymerization is 5 to 100 parts by weight, preferably 10 to 75 parts by weight of organopolysiloxane having no silicon atom-bonded alkenyl group and at least one silanol group in the molecule. . Since the component (G) is an organopolysiloxane having a silanol group and a certain chain length, an increase in the hardness of the cured product obtained when used in combination with the components (A) to (F). Is moderately suppressed, and there is an advantage that durability, tensile strength, tear strength and the like can be improved.

The structure of component (G) has no silicon atom-bonded alkenyl group in the molecule, the molecular chain end is blocked with a silanol group or a triorganosiloxy group, and the main chain is a repeating diorganosiloxane unit or silanol organosiloxane unit. However, it may be partially branched. Regarding the degree of polymerization, those having a number average degree of polymerization of 250 to a degree of polymerization that exhibits a raw rubber shape at room temperature can be used, and the number average degree of polymerization is 250 to 100,000, preferably 1,000 to 8,000. Is. In particular, those which are linear and have silanol groups at both ends of the molecular chain are preferred. In this case, the component (G) is represented by the following average molecular formula. The component (G) can be removed in advance by a known means such as stripping so that the low molecular weight siloxane having a polymerization degree of 10 or less can be 1000 ppm or less.
HO (R ² ) ₂ SiO— (R ² ₂ SiO) _m1 (R ² (OH) SiO) _m ² —Si (R ² ) ₂ OH
(In the formula, R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms having no aliphatic unsaturated bond, and preferably 90% or more thereof is a methyl group or a phenyl group. M1 + m2 is 248 or more. And m1 is a positive number and m2 is 0 or a positive number.)

The component (G) particularly preferably has a number average molecular weight of 2000 or more determined from the number average molecular weight in terms of standard polystyrene, is a raw rubber at room temperature, has no silicon-bonded alkenyl group in the molecule, An organopolysiloxane having silanol groups at both chain ends. By using the raw rubber-like organopolysiloxane having a silanol terminal in combination, the permanent elongation characteristics can be further improved, and a silicone elastomer that more suitably satisfies the required characteristics as a medical tube can be provided.

The addition-curable silicone elastomer composition according to the present invention is further selected from the group consisting of magnesium oxide (MgO), magnesium hydroxide (Mg (OH) ₂ ), and magnesium carbonate in order to improve water resistance. At least one selected magnesium compound can be blended. Examples of the magnesium carbonate include magnesium carbonate (MgCO ₃ ), basic magnesium carbonate (mMgCO ₃ .Mg (OH) ₂ .nH ₂ O, for example, 3MgCO ₃ .Mg (OH) ₂ .3H ₂ O) and the like. These magnesium compounds may be hydrates or anhydrides. Two or more kinds of magnesium compounds may be used in combination. Since the use of such a magnesium compound is also recognized by the FDA, the silicone elastomer composition of the present invention can be suitably used for beverages and foods as well as for medical use. Silicone elastomers containing these magnesium compounds are used for balloon inflation, which are harmless to the human body, such as aqueous media containing chloride ions (tap water, physiological saline, a mixture of angiographic and physiological saline, butter sugar solution, etc. Liquid, blood, bodily fluids such as gastric acid, and therapeutic liquids), even if it is in contact for a long period of time, it has the advantage of preventing or reducing the appearance or deterioration of appearance such as whitening. It can be suitably used for medical members (for example, gastric catheters, balloons or catheter balloons, artificial dialysis devices, hemodialysis devices, and implant members) that are used in contact with physiological saline, acidic washing solution, or the like.

The lower limit of the compounding amount of the magnesium compound is not particularly limited as long as it is within the range in which the above effect can be exhibited, but 0.01% based on the total weight (mass) of the curable silicone elastomer composition. It is preferable that it is -3 mass%, and the range of 0.1-0.5 mass% is especially preferable.

The shape of the magnesium compound is not particularly limited, and examples thereof include a bulk shape or a particle shape (including a true spherical shape and a substantially spherical shape), and a particulate shape is preferable. The average particle diameter of the particulate magnesium compound is generally in the range of 0.1 to 10 μm, and particularly preferably in the range of 0.5 to 5 μm. Further, such a magnesium compound may be preferably subjected to a surface treatment with a surface treatment agent such as an aluminum compound, a zinc compound, a silicon compound, or a higher fatty acid.

The addition-curable silicone elastomer composition according to the present invention may contain a curing retarder in order to adjust the curing speed or working life. Examples of the curing retarder include carbon such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, phenylbutynol, 1-ethynyl-1-cyclohexanol, and the like. Alcohol derivatives having a carbon triple bond; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; tetramethyltetravinylcyclotetrasiloxane, tetramethyltetrahexenyl Alkenyl such as methyl-tris (3-methyl-1-butyne-3-oxy) silane and vinyl-tris (3-methyl-1-butyne-3-oxy) silane Illustrative examples include silanes.

The blending amount of the curing retarder may be appropriately selected according to the usage method, molding method and the like of the hydride addition type silicone elastomer composition. The general blending amount is in the range of 0.001% to 5% by weight (mass) based on the total weight (mass) of the composition.

The addition-curable silicone elastomer composition according to the present invention may be blended with carbon black such as acetylene black, furnace black, and channel black, as long as the purpose is not adversely affected. If necessary, additives such as pigments (colorants such as bengara and various organic pigments, titanium dioxide, etc.), heat-resistant agents, flame retardants, internal mold release agents, plasticizers, and non-functional silicone oils may be blended. Good. Examples of the internal mold release agent include higher fatty acid salts such as calcium stearate. In addition, when using as a medical tube for the treatment exposed to high temperature, such as heat sterilization process and use of a thermocouple, addition of a heat-resistant agent, a flame retardant, etc. is especially preferable.

However, the addition-curable silicone elastomer composition according to the present invention includes (X1) an organopolysiloxane having both molecular chain ends blocked with a trialkylsilyl group (corresponding to component (B) or component (C)) ), (X2) R ¹ ₃ SiO _1/2 unit (wherein R ¹ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a substituted or unsubstituted group having 1 to 10 carbon atoms) And an organopolysiloxane resin consisting essentially of SiO _4/2 units. Specifically, the total content of these components is preferably less than 5% by mass of the total composition, more preferably less than 1% by mass, and most preferably substantially Is an amount that affects the properties of the cured product and is not contained in the composition (= less than 0.1% by mass).

In the addition-curable silicone elastomer composition according to the present invention, the organopolysiloxane having both ends of the molecular chain blocked with the trimethylsilyl group as the component (X1) and the organopolysiloxane resin as the component (X2) are substantially contained. If it is contained, the cured product may become sticky or tacky, handling properties may deteriorate, and it may be unable to be suitably used as an elastic member for a medical instrument such as a medical tube. In particular, when the content of the organopolysiloxane having both molecular chains blocked with the trimethylsilyl group as the component (X1) exceeds 5% by mass of the entire composition, the cured product becomes sticky or tacky, resulting in hardness or permanentness. Even if it is useful in terms of elongation characteristics, it may adversely affect handling (for example, roll workability) and formability (for example, mold release).

In the curable silicone rubber composition of the present invention, the above-mentioned components or a composition in which various additives are blended as necessary are uniformly mixed by a known kneading means such as a loss mixer, two rolls, a kneader mixer or the like. Can be easily manufactured.

The addition-curable silicone elastomer composition according to the present invention can employ a conventional method as a molding and curing method, but an injection molding method, compression molding method or extrusion molding (including hot air vulcanization) can be used as the molding method. Preferably employed. Moreover, as a curing condition, a curing temperature and a curing time are not particularly limited, and in general, it can be cured well at room temperature to 220 ° C. From the viewpoint of industrial production of elastic members for medical instruments such as medical tubes, heat treatment conditions of 80 to 230 ° C. for 3 seconds to 60 minutes, preferably 100 to 200 ° C. for about 5 seconds to 30 minutes may be employed. . As will be described later, the addition-curable silicone elastomer composition according to the present invention achieves hardness and permanent elongation characteristics suitable for an elastic member for medical instruments by press curing (compression molding) at 120 ° C. for 10 minutes. However, if desired, step vulcanization (step cure) such as further secondary vulcanization (post cure) after primary vulcanization may be performed and cured. However, in that case, the cycle time required for production may increase and productivity may decrease.

Specifically, the addition-curable silicone elastomer composition according to the present invention may be cured in one step at the above temperature. Furthermore, when the step cure which is first heated at room temperature to 150 ° C., preferably 60 to 150 ° C. and then heated at 80 to 200 ° C., preferably 100 to 180 ° C., the properties such as permanent elongation are further improved. There is. In addition, after curing is completed, secondary curing (thermal aging) is performed at 150 to 250 ° C. for about 10 minutes to 2 hours in order to remove a small amount or a small amount of volatile components and further improve properties such as permanent elongation. It is preferable.

The addition-curable silicone elastomer composition according to the present invention has a hardness measured according to JIS K6253 durometer hardness test type A after press curing at 120 ° C. for 10 minutes according to the composition of the above composition (JIS -A hardness) is characterized by giving a cured product of 40 or more. The JIS-A hardness is preferably 40 to 90, and preferably 45 to 85. In particular, the JIS-A hardness is preferably 50 or more, and is preferably in the range of 50-80. If the hardness under the above-mentioned curing conditions is outside the above range, the strength and flexibility of the cured product may be insufficient and may not be suitably used for a medical balloon.

The addition-curable silicone elastomer composition according to the present invention has an elongation at break of 500% or more measured according to JIS K6251 after press curing at 120 ° C. for 10 minutes, according to the composition of the above composition. Furthermore, the cured product does not have a yield point before cutting. Here, the cured product has a yield point. In the tensile stress-elongation curve obtained according to JIS K6251, the tensile stress of the cured product is measured after the initial tensile stress rises until the cured product is cut. There is a local maximum. That is, the addition-curable silicone elastomer composition according to the present invention conforms to JIS K6251 because the tensile stress and the elongation increase without giving a maximum value until the moment when the elongation at break is measured, that is, until the break. When drawing the tensile stress-elongation curve (SS curve), the maximum point of the tensile stress after the initial rising of the tensile stress is not observed, and if the sample is continuously stretched, the elongation at break (%) ), The sample breaks.

Further, the addition-curable silicone elastomer composition according to the present invention has a tensile strength as defined in JISK6251 from the viewpoint of handling workability at the time of molding and strength as an elastic member for medical devices. Is 7.0 MPa or more, more preferably 8.0 to 15 MPa, and particularly preferably 8.25 to 14.0 MPa.

Moreover, from the point of the intensity | strength as an elastic member for medical devices, the said hardened | cured material is 500% or more of elongation at the time of cutting | disconnection prescribed | regulated to JISK6251, and it is preferable that it is 500-1200%. The elongation at break is preferably 500 to 900% when the hardness is in the range of 60 to 80, and is 800 to 1200% when the hardness is in the range of 40 to 60. Particularly preferred.

The physical properties of not having the above-mentioned hardness, elongation at break, tensile strength, and yield point (= maximum value of tensile stress in tensile stress-elongation curve obtained in accordance with JIS K6251) are additional curing according to the present invention. This is a physical property that is directly realized from the composition of the silicone elastomer composition of the mold, in particular, by using the predetermined component (A) and the component (B) in combination. Further, the addition-curable silicone elastomer composition according to the present invention is based on JIS K 6251 after press curing at 120 ° C. for 10 minutes from the viewpoint of use as an elastic member for medical instruments such as medical tubes. The measured 100% modulus (M100) is 0.75 to 5.0 MPa, and particularly preferably 1.0 to 3.0 MPa.

Similarly, the addition-curable silicone elastomer composition according to the present invention has a tear strength measured by a crescent type in accordance with JIS K6252 from the viewpoint of strength and service life as an elastic member for a medical device. m or more is preferable, and 25.0 to 50 kN / m is particularly preferable.

The cured product comprising the silicone elastomer composition according to the present invention can be used in various applications including electrical equipment, automobiles, architecture, medical care, foods and the like. For example, rubber contacts used as rubber contacts for remote controllers, typewriters, word processors, computer terminals, musical instruments, etc .; architectural gaskets; various rolls such as copier rolls, development rolls, transfer rolls, charging rolls, paper feed rolls, etc. Anti-vibration rubber for audio equipment, etc .; Packing for compact discs used in computers, etc .; Water-related members such as valves, hoses, tubes, packing, seals or joints; Play equipment for children, tableware, cooking utensils (silicone steamers, etc.) ), Toothbrush, baby bottle nipple, infant pacifier, artificial nipple, sports equipment, diving underwater glasses, diving goggles, automobile parts, models, or artificial skin members of robots.

In particular, the cured product comprising the silicone elastomer composition according to the present invention is excellent in safety and durability, and has an appropriate hardness, permanent elongation, and other physical properties, so that it is a medical elasticity used for the treatment of humans or animals. Can be used for members. For example, it is also suitable for various medical tubes, gastric catheters, medical balloons and catheter balloons, artificial dialysis devices, hemodialysis devices, implant members, drug stoppers, and O-rings. The cured product made of the silicone elastomer composition according to the present invention is excellent in heat resistance, acid resistance, radiation resistance and the like, and has the advantage that it can be easily sterilized because the physical properties do not deteriorate.

The most suitable use of the silicone elastomer according to the present invention is a material for medical instruments such as various medical catheters and tubes, and is inserted into body cavities such as the thoracic cavity and abdominal cavity, luminal portions such as the digestive tract and ureter, and blood vessels. In addition, it can be particularly suitably used as a material for various medical tubes used for the discharge of body fluids and the infusion of medicinal solutions, nutrients, contrast agents and the like. The medical tube made of the silicone elastomer according to the present invention has the advantage that it has excellent moldability in extrusion molding and the like, has a relatively high hardness, has a large elongation at the time of cutting, is highly flexible, and is hardly permanent. Have. Furthermore, the silicone elastomer according to the present invention has high tensile strength and tear strength, and is excellent in reliability and durability. Further, by using fumed silica which is the above-mentioned suitable inorganic filler, a silicone elastomer having a transparent appearance and excellent scratch resistance can be obtained, and the contents of the tube and the liquid flow in the catheter can be obtained. In addition, the silicone elastomer according to the present invention can be easily molded, and the shape, internal structure, inner diameter, film thickness, length, etc. of the tube can be used or desired as desired. There is an advantage that an appropriate known shape or the like can be selected according to the organ to be operated.

The medical tube made of the silicone elastomer according to the present invention is a medical catheter or a medical drain tube, and is a medical catheter used for infusion drip of blood or the like, or a suction device for removing drainage such as blood or pus after operation. Examples include a drainage tube, a tube for nutrient intake after surgery such as percutaneous endoscopic gastrostomy (PEG), a tube for pharmaceuticals and preparations, and the like.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to the following Example. The viscosity (kinematic viscosity) is a measured value at 25 ° C. In the table, “parts” is parts by mass, and% is mass%.

[Measurement of number average molecular weight and average degree of polymerization]
In Examples and the like, the average degree of polymerization of organopolysiloxane is the number average degree of polymerization based on the number average molecular weight in terms of standard polystyrene determined by average molecular weight gel permeation chromatography (GPC) using the following analyzer, and measured under the following conditions: It has been done.

Measurement temperature: 40 ° C. (column oven temperature)
Sample: Organopolysiloxane used as 1 wt% toluene solution Detector: RI detector Rehabilitation curve polymer: Standard polystyrene

[Sample preparation and curing conditions]
Each component described in Table 1 (Example) and Table 2 (Comparative Example) is uniformly mixed on two rolls, and press vulcanized at 120 ° C. for 10 minutes to obtain a test piece having a thickness of 2 mm. It was.

(Examples 1-3 and Comparative Examples 1-4)
The components shown in Table 1 and Table 2 below were uniformly mixed to obtain addition curable liquid silicone elastomer compositions of Examples 1 to 3 and Comparative Examples 1 to 4.
Table 1 shows examples and comparative examples relating to silicone elastomers prepared with a hardness of 60 or more, and Table 2 shows examples and comparative examples relating to silicone elastomers having a hardness of 40 to less than 60.

About each composition of Examples 1-3 and Comparative Examples 1-4, the following characteristic was measured. The results are also shown in Table 1.

[Initial physical properties]
(1) JIS-A hardness: According to JIS K6251 (vulcanized rubber tensile test method), the hardness of a test piece of a silicone rubber cured product (using JIS type A durometer, JIS-A hardness) was measured.
(2) Tensile strength, 100% modulus: Measured using “Autograph SES-1000” manufactured by Shimadzu Corporation according to JIS K6251. Note that. The tensile stress at 100% elongation was recorded as 100% modulus.
(3) Tear strength: A crescent-type test piece described in JIS K6252 (vulcanized rubber tear test method) was punched out from the above test piece to obtain a test piece. Using this, measurement was performed using “Autograph SES-1000” manufactured by Shimadzu Corporation according to JIS K6252.
(4) Elongation at the time of cutting: Measured using “Autograph SES-1000” manufactured by Shimadzu Corporation according to JIS K6251, and the elongation when the test piece was cut was expressed as a ratio (%) to the initial value.

[Presence or absence of yield point]
In accordance with JIS K6251, the tensile stress and elongation of the test piece of silicone rubber cured product were measured with Autograph SES-1000 (manufactured by Shimadzu Corporation) until the test piece was cut (= rupture due to elongation), and tensile stress (unit: After drawing a (MPa) -elongation (%) curve (SS curve), the presence or absence of a yield point was evaluated according to the following criteria.
<Evaluation>
On the SS curve measured up to the time of cutting, when no yield point at which the maximum value of tensile stress was observed, it was determined that “no yield point”.
On the SS curve measured up to the time of cutting, when a yield point at which the maximum value of tensile stress was observed, it was evaluated that “there was a yield point”.

In Tables 1 and 2, the components used in Examples and Comparative Examples are as follows.

(A1) Organopolysiloxane 1 (gum):
Molecular chain both ends vinyldimethylsilyl group-capped dimethylsiloxane (number average degree of polymerization: 4473)
(A2) Organopolysiloxane 2 (gum-like):
Vinyldimethylsilyl group-blocked dimethylsiloxane / methylvinylsiloxane copolymer (average degree of polymerization: 4340, vinyl group content: 0.061% by mass)
(B1) Organopolysiloxane 3 (gum):
Trimethylsilyl group-blocked dimethylsiloxane / methylvinylsiloxane copolymer (number average degree of polymerization: 3764, vinyl group content: 1.420% by mass)
(B2) Organopolysiloxane 4 (20 mPa · s):
Molecular chain both ends hydroxydimethylsilyl group-capped dimethylsiloxane / methylvinylsiloxane copolymer (viscosity: 20 mPa · s, vinyl group content: 10.0% by mass)
(D1) Fumed silica:
Fumed silica with BET specific surface area of 300m2 / g (Product name "Aerosil 300", manufactured by Nippon Aerosil Co., Ltd.)
(D2) Fumed silica:
Fumed silica with a BET specific surface area of 200 m 2 / g (product name “Aerosil 200”, manufactured by Nippon Aerosil Co., Ltd.)
(F) Organopolysiloxane 5:
Molecular chain both ends hydroxydimethylsilyl group-blocked dimethylsiloxane (viscosity: 30 mPa · s, number average polymerization degree: about 11)
(C) Organohydrogenpolysiloxane:
Dimethylsiloxane / methylhydrogensiloxane copolymer blocked with trimethylsilyl groups at both ends of the molecular chain (viscosity: 15 mPa · s, Si—H content: 0.83 mass%)
(E) Addition reaction catalyst:
1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum (Platinum metal in this complex is added to each silicone elastomer composition and used in an amount of 4 ppm in mass units) did.)
(F) Curing retarder:
1-ethynyl-1-cyclohexanol

As shown in Tables 1 and 2, the compositions of Examples 1 to 6 have a hardness suitable for an elastic member for medical use (especially a medical tube) by press curing at 120 ° C. for 10 minutes, and yield point. A silicone elastomer having the characteristics of having a high elongation at break and high tensile strength.

In Comparative Example 1, there was no yield point, but the elongation at break and tear strength were insufficient.
Furthermore, in Comparative Examples 2 to 5, when drawing a tensile stress-elongation curve (SS curve) in accordance with JIS K6251, a yield point that is the maximum point of the tensile stress occurs after the rising of the tensile stress, A silicone elastomer having characteristics without a yield point could not be provided.

As described above, by using the silicone elastomer compositions of Examples 1 to 6 according to the present invention, a cured product having physical properties suitable for a medical elastic member (particularly a medical tube) can be obtained. It was. In particular, the cured products of Examples 1 to 3, Example 5, and Example 6 have particularly high tensile strength and do not have the yield point of the cured product, and therefore can be used very suitably for medical tube applications. .

Claims (9)

(A) 100 parts by mass of an organopolysiloxane having a raw rubber-like silicon atom-bonded alkenyl group at room temperature, wherein the components (A1) and (A2) are contained in a mass ratio of 10/90 to 95/5 (A1) Gel permeation chromatography An organopolysiloxane having a number average molecular weight based on a polystyrene-equivalent number average molecular weight measured by chromatography (GPC) of 2,000 or more and having an average of two or more silicon atom-bonded alkenyl groups only at the molecular chain ends;
(A2) The number average degree of polymerization based on the polystyrene-reduced number average molecular weight measured by gel permeation chromatography (GPC) is 2000 or more, and the molecular chain terminal and side chain have an average of 3 or more alkenyl groups. And an organopolysiloxane having an alkenyl group content of less than 0.10% by mass (B) and an alkenyl group content of 0.50 to 20.0% by mass 1.0-20 parts by mass ,
(C) 0.3-20 parts by mass of an organopolysiloxane having an average of 2 or more silicon-bonded hydrogen atoms in one molecule;
(D) 10 to 100 parts by mass of an inorganic filler (E) addition reaction catalyst containing a catalyst amount,
After press curing at 120 ° C for 10 minutes,
The hardness measured according to JIS K6253 durometer hardness test type A is 40 or more,
The elongation at break measured according to JIS K6251 is 500% or more,
In the tensile stress-elongation curve obtained in accordance with JIS K6251, a cured product having no maximum point of tensile stress, which is the yield point of the cured product before cutting, and having a tensile strength of 7.0 MPa or more. Give silicone elastomer composition. Further, (F) a dimethylpolysiloxane having a silanol group at the molecular chain terminal and having a number average degree of polymerization of 100 or less based on a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (GPC) 1.0 to 50 mass The silicone elastomer composition according to claim 1, comprising a part. The said (B) component is a mixture of the alkenyl group containing organopolysiloxane which contains the following (B1) and (B2) component by mass ratio of 5 / 95-90 / 10. Silicone elastomer composition.
(B1) Organopolysiloxane having a number average degree of polymerization based on a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (GPC) of 2000 or more and an alkenyl group content of 0.50 to 5.0% by mass (B2) The number average degree of polymerization based on the number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) is 100 or less, has a silanol group at the end of the molecular chain, and has an alkenyl group content of 1 Organopolysiloxane of 0.02 to 20.0% by mass The said (D) component is an inorganic filler which contains 50 mass% or more of the fumed silica whose specific surface area by the BET method is the range of 150-350 m < ² > / g. A silicone elastomer composition as described in 1. above. (X1) Organopolysiloxane in which both ends of the molecular chain are blocked with a trialkylsilyl group (excluding those corresponding to the above component (B) or (C)), or (X2) R ¹ ₃ SiO _1/2 A unit (wherein R ¹ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms) and a SiO _4/2 unit. Organopolysiloxane resin consisting essentially of
The silicone elastomer composition according to any one of claims 1 to 4, wherein the sum of the contents of is less than 1% by mass of the entire composition. A molded cured product of the silicone elastomer composition according to any one of claims 1 to 5. The elastic member for medical instruments which consists of a shaping | molding hardened | cured material of the silicone elastomer composition in any one of Claims 1-5. The medical tube which consists of a shaping | molding hardened | cured material of the silicone elastomer composition in any one of Claims 1-5. A medical catheter or a medical drain tube containing the molded cured product of the silicone elastomer composition according to any one of claims 1 to 5 in at least a part of its configuration.

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