Valve body, process for producing the valve body, and medical instrument including the valve body

A valve body, e.g. a valve body adapted to be disposed in a connector to be connected to a catheter, has an opening/closing part which opens upon inserting a member into the opening/closing part and which closes upon withdrawing the member from the opening/closing part. The valve body includes a main body part made of a silicone rubber and a surface layer disposed on a surface of the main body part. This surface layer serves as a sliding surface which, when a guide wire has been inserted into the opening/closing part, slides on the guide wire. The surface layer is constituted mainly of silicon oxide and hence improves the sliding properties of the guide wire. Thus, the valve body is reduced in the resistance of sliding on the guide wire.

TECHNICAL FIELD

The present invention generally pertains to a valve body, a production process and an instrument embodying the valve body. More specifically, the invention relates to a valve body, having useful application in a medical instrument, a process for producing the valve body, and a medical instrument embodying the valve body.

BACKGROUND DISCUSSION

When an elongated member for medical use such as a catheter, a guide wire, etc. is to be guided into a living body, an introducer is oftentimes used.

The introducer includes a cylindrical hub (joint part), a valve body (check valve) disposed in one end portion of the hub, and a tube connected to the other end portion of the hub. An example of a valve body used in the introducer in this manner is one made of a flexible elastic material such as silicone rubber, as described in Japanese Patent Publication No. Hei 2-949.

The valve body is formed with an opening/closing (opening and/or closing) port (e.g., slit or minute hole) which opens or closes as the elongated member is inserted or pulled out. In addition, for reducing the sliding resistance (frictional resistance) on the elongated member when the elongated member is inserted, the valve body should have lubricity on its surface, particularly at the opening/closing port. To meet this requirement, a lubricating liquid such as a silicone oil is applied to the vicinity of the opening/closing port so as to reduce the sliding resistance of the valve body on the elongated member.

When the insertion and pulling-out of the elongated member through the opening/closing port is repeated, however, the lubricating liquid applied in the vicinity of the opening/closing port gradually becomes leaner. Eventually, the lubricating liquid runs out, leading to an increase in the sliding resistance of the elongated member. In the introducer having such a valve body, therefore, the presence of the lubricating liquid influences the sliding properties of the elongated member. Accordingly, the introducer may suffer a problem in that the operability of the elongated member is reduced during use.

In addition, the introducer as a medical instrument may sometimes be subjected to a sterilizing treatment by irradiation with radiant rays. However, the flexible elastic material such as silicone rubber undergoes alteration or deterioration when exposed to radiant rays. The alteration or deterioration is due to the process in which molecular chains in the silicone rubber are cut by the radiant rays and oxygen in the atmospheric air is bonded to the cut ends of the molecular chains. In this manner, the properties of the silicone rubber are changed, whereby the valve body's function is damaged. For this reason, the conventional valve bodies have a problem that it is difficult to sufficiently sterilize them by use of radiations.

SUMMARY

The valve body disclosed here exhibits characteristics such that the sliding resistance of the valve body is less liable to increase even upon increased sliding operation (increased usage). Also, the valve body possesses excellent radiation resistance and liquid-tightness performance.

The valve body disclosed here includes an opening/closing part which opens upon inserting a member into the opening/closing part and which closes upon withdrawing the member from the opening/closing part. At least the opening/closing part of the valve body has a main body part comprised of a silicone rubber, and a surface layer is provided on a surface of at least the main body part. The surface layer is comprised of silicon oxide.

Preferably, the surface layer has an average thickness of 10 nm to 100 μm.

The surface layer is also preferably composed of an aggregate of silicon oxide.

Further, the surface layer is preferably composed of an aggregate of particles of silicon oxide.

The surface layer can include plural surface layers preferably in the form of a plurality of spaced apart or discrete dots dispersed on a surface of the main body part.

Each of the dot-formed surface layers preferably projects from the surface of the main body part.

The projection height of the projected surface layers is preferably 500 nm to 50 μm.

The plurality of dot-formed surface layers can be arranged in a density of 300 to 3000 pieces/mm2.

The surface layer can also entirely cover a surface of the main body part.

In addition, the valve body preferably further includes, between the main body part and the surface layer, an intermediate layer composed of a material intermediate between a material constituting the main body part and a material constituting the surface layer.

The content of an organic component in the intermediate layer gradually decreases from the main body part side toward the surface layer side.

Further, each of the surface layer and the intermediate layer is formed through modification of the whole part or a part of the silicone rubber into silicon oxide by irradiation with a laser beam. The opening/closing part is preferably composed of at least one slit.

In addition, the valve body can be columnar or plate-like in overall shape.

Examples of the member adapted to be inserted in the valve body include a sheath, a dilator, a catheter, a guide wire or a needle.

Another aspect disclosed here involves a process for producing a valve body comprising an opening/closing part which opens upon inserting a member into the opening/closing part and which closes upon withdrawing the member from the opening/closing part. The process comprises forming a surface layer comprised of silicon oxide at least in a region that includes the opening/closing part, and the surface layer comprised of silicon oxide is formed on a surface of a base material having the opening/closing part, the base material on which is formed the surface layer comprised of silicon oxide being a silicone rubber.

In addition, the surface layer of the base material is preferably formed by irradiating at least a region of a surface of the opening/closing part with a laser beam so that the silicone rubber in the vicinity of the surface in the region is modified into silicon oxide and raised.

The laser beam has a wavelength of not more than 200 nm.

The irradiation with the laser beam is carried out through a photomask having a window part of a predetermined shape, whereby modification from the silicone rubber into silicon oxide is effected in a region, having a shape corresponding to the predetermined shape, of the surface of the opening/closing part.

The photomask is preferably composed of a mesh-shaped member or a punching metal.

In addition, the surface layer is preferably formed by forming a layer of silicon oxide at least in a region of a surface of the opening/closing part.

The surface layer can be formed by forming a silicon layer at least in a region on a surface of the opening/closing part, and thereafter subjecting the silicon layer to an oxidizing treatment so as to modify silicon into silicon oxide.

Another aspect disclosed here involves a medical instrument comprising a tubular medical instrument main body through which extends a lumen which is open at opposite ends, and a valve body positioned in the lumen of the tubular medical instrument main body. The valve body comprises an opening/closing part which opens when an elongated member is slidably inserted into the opening/closing part and which closes when the elongated member is slidably withdrawn from the opening/closing part. At least the opening/closing part of the valve body has a main body part made of a silicone rubber, and the main body possesses a surface on which is provided a surface layer that contacts the elongated member when the elongated member is slidably inserted into the opening/closing part. The surface layer which contacts the elongated member when the elongated member is slidably inserted into the opening/closing part is a material different from the main body part. The material forming the surface layer includes silicon oxide.

The medical instrument can be an introducer or a Y-connector.

DETAILED DESCRIPTION

A valve body, a process for producing a valve body, and a medical instrument embodying the valve body are described in more detail below.

One disclosed embodiment of the valve body, medical instrument and manufacturing process is illustrated inFIGS. 1-3. For convenience of description, the right side inFIGS. 1 and 3is referred to as the proximal, and the left side is referred to as the distal.

FIG. 1illustrates an example of a medical instrument11with which the valve body disclosed here has useful application. The medical instrument is a connector, for example a connector used in connection with a hub301of a catheter30. The connector1, in the state of being connected to the hub301, is configured to, for example, allow introduction of an elongated member (in this embodiment, a guide wire20) into the catheter30. The guide wire20is composed of, for example, a metallic material such as stainless steel.

The medical instrument1includes a tubular-shaped medical instrument main body2, which in the illustrated embodiment is a connector main body2, a lock member or lock adaptor3turnably supported on a distal portion21of the connector main body2, a cap body (cap)5turnably supported on a proximal portion22of the connector main body2, and a valve body7disposed in the connector main body2.

The connector main body2includes a lumen (hollow part)23completely penetrating or passing through the connector main body2in the longitudinal direction so that opposite ends of the connector main body are open. The lumen23is configured to include a stepped part231where the inside diameter varies (increases) abruptly. The lumen23is divided, with the stepped part231as a boundary, into a reduced diameter part232on the distal side and an enlarged diameter part233on the proximal side.

In the enlarged diameter part233, the valve body7is accommodated (disposed) with its distal end face71in abutment with the stepped part231. This fixes the position of the valve body7relative to the connector main body2. That is, the valve body7is positioned. In addition, the enlarged diameter part233is provided, on the proximal side, with a circumferentially extending inwardly projecting part234. The projecting part234helps prevent the cap body5from slipping off the main body2toward the proximal side.

The proximal portion22of the connector main body2is provided, at the outer peripheral portion, with a male screw part235. The male screw part or threaded part235meshes with a female screw part51of the cap body5as described later.

The distal portion21of the connector main body2is provided, at its outer peripheral portion, with a circumferentially extending outwardly projecting part212. The projecting part212helps prevent the lock member3from slipping off the main body2toward the distal side, and rotatably supports the lock member3.

The connector main body2has a branch part24branching from an intermediate portion of the main body. The branch part24is tubular in shape, and communicates with the reduced diameter part232(lumen part23) of the connector main body2. To the branch part24, for example, a prefilled syringe (not shown) filled with a liquid such as a drug, a radiopaque material, etc. is connected. In the example where the prefilled syringe is connected, the liquid can be supplied from the prefilled syringe into the catheter30through the branch part24(connector1).

The branch part24is inclined toward the proximal side relative to the connector main body2. That is, the centerline of the branch part24is oblique relative to the centerline of the main body2. This helps ensure that the liquid flows smoothly in the distal direction from the branch part24through the connector main body2and, hence, the liquid can be relatively assuredly supplied into the catheter30.

The lock member3is a cylindrical member which has a lumen31. The lock member3is provided, near its middle portion, with a reduced diameter part32where its inside diameter is reduced.

In the illustrated embodiment, the lumen31is divided, with the reduced diameter part32as a boundary, into a distal-side lumen part311on the distal side and a proximal-side lumen part312on the proximal side.

The inner peripheral surface of the distal-side lumen part311possesses a female screw part313. The female screw part313is configured to mesh with a male screw part on the hub301of the catheter30. The meshing engagement between these screw parts (threaded parts) securely connects the lock member3(connector1) and the catheter30to each other.

In addition, the reduced diameter part32is provided with a tubular part33projecting in a tubular shape in the distal direction from the reduced diameter part32. The tubular part33projects distally beyond the portion of the lock member3positioned radially outwardly of the tubular part33. This tubular part33is connected in a liquid-tight manner to the hub301of the catheter30when the female screw part313of the lock member3and the male screw part of the hub301mesh with each other. This helps ensure that, when a liquid is supplied into the catheter30through the connector1, leakage of the liquid is relatively reliably prevented.

The distal portion21of the connector main body2is positioned in the proximal-side lumen part312. The inner peripheral surface of the proximal-side lumen part312is formed with a recess314into which the projected part212of the distal portion21of the connector main body2is fitted. The recess314is ring-shaped or annular, extending continuously in the circumferential direction of the inner peripheral surface of the proximal-side lumen part312. With the projecting part212of the connector main body2fitted in the recess314, the lock member3can be turned or rotated relative to the connector main body2(distal portion21). As a result, the lock member3can be connected, in a meshed state, to the hub301of the catheter30.

A ring-shaped member (seal member)8having an annular shape is disposed in the proximal-side lumen part312. The ring-shaped member8is formed of an elastic material. In the connector1, the connector main body2and the lock member3are connected in a liquid-tight manner to each other through the ring-shaped member8. This helps ensure that, when a liquid is supplied into the catheter30through the connector1, the liquid can be prevented from leaking through the vicinity of the joint part between the connector main body2and the lock member3.

The cap body5has a bottomed cylindrical shape. The inner peripheral surface of the cap body5is formed with the female screw part51that meshes with a male screw part235of the connector main body2. The meshing engagement of these screw parts or threaded parts allows the cap body5to be moved along the longitudinal direction of the connector main body2while rotating relative to the connector body2.

In addition, a bottom part52of the cap body5is provided with a tubular part53projecting in a tubular shape along the distal direction. The tubular part53is positioned in the enlarged diameter part233of the connector main body2. When the cap body5is rotated (for example, rotated clockwise) in this condition (in the condition shown inFIG. 1), the tubular part53approaches the valve body7from the distal side, eventually pressing the valve body7, namely deforming the valve body7. The outer peripheral portion of the tubular part53includes a circumferentially extending projecting part531, on the distal side relative to the projecting part234of the connector main body2. The projecting part531is able to abut the projecting part234of the connector main body2from the distal side of the projecting part234to thus restrict movement of the cap body5in the proximal direction. This helps prevent the cap body5from slipping off from the connector main body2.

The materials constituting the connector main body2, the lock member3and the cap body5are not particularly limited. Examples of materials which can be used for these components include various resins such as polyvinyl chloride, polyethylene, polypropylene, cyclic polyolefins, polystyrene, poly(4-methylpentene-1), polycarbonate, acrylic resin, acrylonitrile-butadiene-styrene copolymer, polyesters such as polyethylene terephthalate, polyethylene naphthalate, etc., butadiene-styrene copolymer, and polyamides (e.g., nylon 6, nylon 6,6, nylon 6,10, nylon 12).

The material constituting the ring-shaped member8is also not particularly limited. Examples of material which can be used here include elastic materials, for example, natural rubber, various synthetic rubbers such as isoprene rubber, silicone rubber, urethane rubber, styrene-butadiene rubber, fluororubber, acrylic rubber, etc., and various thermoplastic elastomers based on polyamide, polyester, or the like.

As shown inFIG. 2, the valve body7is a circular disc-shaped member possessing a relatively short cylindrical overall shape (outside shape). A major part of the valve body7is formed of a silicone rubber. The valve body7includes a distal end face71facing in the distal direction when mounted in the main body2and a proximal end face73facing in the proximal direction when mounted in the main body2.

The valve body7shown inFIG. 2has an opening/closing part70which, when an elongated member such as a guide wire20is inserted, opens or closes while allowing the guide wire20to slide. The opening/closing part70of the valve body7is composed of a first slit751and a second slit752which open and close as the guide wire20is inserted and pulled out.

The first slit751extends from the inside or interior of the valve body7toward one of the end faces (proximal end face)73of the valve body so that the first slit751only intersects one of the end surfaces73of the valve body7. Thus, the first slit751only opens to the proximal end face73of the valve body. In addition, the first slit751is in the shape of a straight line in plan view. As a result, the first slit751possesses a relatively simple shape (configuration) and so the first slit751(opening/closing part70) can be opened and closed relatively easily and reliably.

The first slit751is in the shape of a circular arc in side view. The first slit751is positioned so that the vertex of the circular arc of the first slit751touches or intersects the second slit752. This is beneficial from the standpoint that the guide wire20can be smoothly moved from the first slit751into the second slit752.

The second slit752extends from the inside or interior of the valve body7toward the other end face (distal end face)71of the valve body so that the second slit752only intersects one of the end surfaces71of the valve body7. Thus, the second slit752only opens to the distal end face71of the valve body. Like the first slit751, the second slit752is in the shape of a straight line in plan view. Consequently, the second slit752is relatively simple in shape (configuration) and so the second slit52(opening/closing part70) can be opened and closed relatively easily and assuredly.

Also, like the first slit751, the second slit752is in the shape of a circular arc in side view. This provides a benefit similar to that discussed above. Further, since both faces (the distal end face and the proximal end face) are the same in shape, when the valve body7is assembled into the connector1, the valve body7can be assembled without any possibility of making a mistake in recognizing the front side and the back side of the valve body7, so that the efficiency of the assembling work can be enhanced.

In addition, the first slit751and the second slit752as described above and illustrated inFIG. 2partially intersect each other in the inside or interior of the valve body7. In the illustrated configuration, the first slit751and the second slit752intersect each other at right angles. Namely, the angle of intersection of the first slit751and the second slit752is 90°. However, it is to be understood that the intersection angle is not limited to 90°.

In the connector1having the valve body7as above, when the cap body5is rotated, the tubular part53presses the valve body7, in the thickness-wise direction, from the proximal side (i.e., from the right side inFIG. 2) of the valve body. By virtue of this pressing, the valve body7might be elastically deformed to be enlarged in outside diameter. However, the outer peripheral surface74of the valve body7is restricted or constrained by the inner peripheral surface of the enlarged diameter part233and so the valve body7cannot be enlarged in outside diameter. Consequently, the inside diameter of the valve body7is reduced (changed). This ensures that the guide wire20inserted in the opening/closing part70is pressed (compressed) by the opening/closing part70in the directions of the arrows A inFIG. 1, so that the guide wire20is securely fastened or held.

In the condition where the guide wire20is thus fastened (the condition will hereinafter be referred to as “the fastened condition”), for example, the possibility of liquid flowing-out (leaking-out) from the inside of the connector main body2through the opening/closing part70of the valve body7is reliably inhibited or prevented.

In the connector1having the valve body7as described above and illustrated in the drawing figures, when the guide wire20is inserted in the opening/closing part70of the valve body7as shown inFIGS. 1 and 3, the silicone rubber in the vicinity of the opening/closing part70is curved in the manner of being pressed by the inserted guide wire20. Where an operation of moving the guide wire20in its longitudinal direction is conducted under this condition, the proximal end face73of the valve body7functions as a sliding part which slides on the outer peripheral surface (outer peripheral part)201of the guide wire20. Since the silicone rubber is elastic, a repelling force is generated in the curved portion of the valve body7. Therefore, even when the guide wire20is operated, the liquid-tightness between the proximal end face73of the valve body7and the outer peripheral surface201of the guide wire20is maintained. Accordingly, the liquid in the connector main body2is securely inhibited or prevented from leaking out through the opening/closing part70.

In the illustrated and described embodiment, the opening/closing part70of the valve body is composed of the two slits. However, the valve body is not limited to this configuration. For example, the opening/closing part70may be composed of one slit or may be composed of three or more slits.

In addition, while each of the slits is in the shape of a straight line in plan view, this configuration is not limitative. For example, the shape of each slit may be the shape of the letter, katakana character “,” letter V, letter U, or the like.

As shown inFIG. 3, the valve body7includes a main body part7acomposed of silicone rubber, and a surface layer7bprovided on an upper surface (proximal end surface73) of the main body part7a.

Of these components, the main body part7ais constituted or composed of a silicone rubber.

The silicone rubber is a rubber material in which a main chain of molecular bonds is composed of silicon-oxygen bonds (siloxane linkages). The silicone rubber is an elastic material excellent in restoration properties in response to compression and/or deformation in a wide temperature range. Therefore, when the guide wire20is inserted in the opening/closing part70of the main body part7a, the main body part7acomposed of the silicone rubber shows excellent follow-up properties to the shape of the outer periphery of the guide wire20. That is, the silicone rubber conforms quite well to the shape of the guide wire20. This helps ensure that the liquid-tightness between the opening/closing part70and the outer peripheral surface201of the guide wire20is maintained to a relatively high degree, so that flowing-out of the liquid present in the connector main body2can be relatively reliably inhibited or prevented.

On the other hand, the surface layer7bis constituted or composed of a material different from the material forming the main body part7a. More specifically, the surface layer7ais constituted or composed of silicon oxide.

With this construction, when the guide wire20is inserted in the opening/closing part70, the main body part7aand the surface layer7bin the vicinity of the opening/closing part70are curved toward the distal side while being pressed by the inserted guide wire20as shown inFIG. 3. Consequently, as shown inFIG. 3, the surface layer7bof the valve body7mainly slides on the outer peripheral surface201of the guide wire20at the time of insertion of the guide wire. Therefore, the sliding resistance exerted on the guide wire20inserted in the opening/closing part70arises mainly from a resisting force generated between the surface layer7bnear the opening/closing part70and the outer peripheral surface201of the guide wire20.

In the valve body disclosed here, the surface layer7bis constituted of silicon oxide as above-mentioned, whereby a reduction in the resistance of sliding of the surface layer7bon the guide wire20is achieved. The reason for this is presumed to be due, at least in part, to the silicon oxide constituting the surface layer7bbeing relatively low in flexibility and elasticity (lower in flexibility and elasticity than the silicone rubber forming the main body part7a) and, hence, it is restrained from a behavior in which the surface layer7btends to adhere to the guide wire20or in which the surface layer7btends to be inhibited from sliding relative to the guide wire outer surface. Therefore, with the valve body7having the surface layer7bas just-mentioned, the guide wire20can slide on the surface layer7bin a slipping-type of manner.

As a result, the valve body7can realize relatively high operability of the guide wire20inserted in the opening/closing part70, while sufficiently securing liquid-tightness between the valve body7and the guide wire20.

In addition, the surface layer7bis provided on a surface of the main body part7acomposed of the silicone rubber. Therefore, the influence of the surface layer7bon the mechanical properties of the valve body7is quite slight, and the mechanical properties of the valve body7as a whole are determined predominantly by the mechanical properties of the silicone rubber constituting the main body part7a. In other words, the valve body7exhibits relatively excellent sliding properties on the guide wire20offered by the surface layer7b, while retaining the flexibility and elasticity properties exhibited by the silicone rubber.

Furthermore, the valve body7shows sufficient sliding properties so as not to hamper the operations of the guide wire20, without the need for using a lubricating liquid (e.g., silicone oil) which has been necessary in the case of conventional valve bodies. This makes it possible to omit the use of a lubricating liquid. Therefore, it is possible to omit the work of applying a lubricating oil to the valve body7. In addition, a problem such as the gradual increase in the sliding resistance due to run-out (consumption) of a lubricating liquid attendant on operations of the guide wire20can be avoided. Therefore, the operator of the guide wire20can operate the guide wire20with a relatively fixed force even when the number of times of sliding is increased. Accordingly, the connector1having the valve body7generally promises excellent operability of the guide wire20.

Also, by avoiding the use of a lubricating liquid, there is no fear that a lubricating oil is dissolved into the liquid in contact with the valve7.

Further, silicon oxide is superior to silicone rubbers in durability against radiation. On the other hand, a silicone rubber would suffer cutting of its molecular chain when exposed to radiations. Then, oxygen in the atmospheric air would be bonded to the cut ends, whereby the silicone rubber would be oxidized. The silicone rubber thus oxidized possesses lowered intrinsic properties such as flexibility and elasticity, leading to fissuring or cracking.

On the other hand, in this embodiment, a surface (proximal end face) of the main body part7acomposed of the silicone rubber is covered with the surface layer7b. Therefore, even if the molecular chains of the silicone rubber constituting the main body part7aare cut by radiation, a gas barrier effect of the surface layer7breduces the chance for the silicone rubber to make contact with oxygen in the air. Consequently, alteration or deterioration of the silicone rubber is restrained, and generation of fissures or cracks can be inhibited or prevented.

The silicon oxide constituting the surface layer7bis not particularly limited regarding the valence of silicon; in general, however, silicon dioxide is preferably used.

In the surface layer7b, the crystal structure of silicon oxide is not particularly limited, but may be single-crystalline, polycrystalline or amorphous.

In addition, the surface layer7bis preferably composed of an aggregate of particles of silicon oxide. This helps ensure that the surface layer7bis relatively rich in flexibility. Accordingly, shape follow-up properties of the surface layer7bin relation to the main body part7aupon curving of the opening/closing part70of the valve body7will be relatively high. Consequently, the surface layer7bcan be relatively securely prevented from peeling from the main body part7a.

The diameter of the silicon oxide particles is not particularly limited, but varies depending on the thickness of the surface layer7b. Preferably, however, the particle diameter is about 1 nm to 10 μm, more preferably about 1 nm to 1 μm.

The surface layer7bpreferably has an average thickness t1of about 10 nm to 100 μm, more preferably about 50 nm to 50 μm (seeFIG. 3). When the average thickness t1of the surface layer7bis in this range, liquid-tightness of the valve body7is sufficiently secured, yet excellent sliding properties on the guide wire20are exhibited. Besides, concern about permeation of oxygen through the surface layer7bis lowered, and the silicone rubber constituting the main body part7acan be relatively securely restrained from undergoing alteration or deterioration.

If the average thickness t1of the surface layer7bis below the above-mentioned lower limit, the sliding resistance exerted on the guide wire20may be raised conspicuously. In addition, permeation of oxygen through the surface layer7bmay occur. On the other hand, if the average thickness t1of the surface layer7bexceeds the above-mentioned upper limit, the flexibility and/or elasticity of the valve body7may be undesirably lowered. Specifically, since the surface layer7bis too thick, the opening/closing part70may become difficult to curve, the guide wire20may become difficult to insert, and the liquid-tightness of the valve body7may be lowered.

In the illustrated embodiment, the surface layer7bis composed of a plurality of surface layers7bdispersed in the form of dots as shown inFIGS. 2 and 3. Each of the surface layers7bprojects (in the form of a projectingly deformed part or a protruding part) from the surface of the main body part7aas shown inFIG. 3. Therefore, when the guide wire20is inserted in the opening/closing part70, the surface layers7bpreferentially make contact with the outer peripheral surface201of the guide wire20. As a result, due to the presence of the surface layers7b, the surface area of the valve body7in sliding contact with the guide wire20is reduced, whereby the sliding resistance exerted on the guide wire20is also reduced. In addition, since the plurality of the surface layers7bare formed in a partial manner (i.e., in this embodiment, the surface layers7bexist on a portion of the surface of the valve body, but not the entire surface of the valve body), a reduction in the sliding resistance can be achieved without considerably lowering the mechanical properties such as flexibility and elasticity of the silicone rubber. Consequently, the valve body7can simultaneously show, at a high extent, both excellent sliding properties on the guide wire20and relatively high liquid-tightness.

In addition, preferably, each of the surface layers7bis hemispherical (dome-like) in shape, as shown inFIG. 2. This helps ensure that the area of contact of the surface layers7bwith the guide wire20is particularly reduced, preferably minimized. As a result, the sliding resistance exerted on the guide wire20can be particularly reduced.

Each of the surface layers7bshown inFIG. 2is so provided that it is partly embedded in the main body part7aas also shown inFIG. 3. Such surface layers7bare thus fixed in such a manner that they are held by the main body part7aand are relatively securely prevented from peeling off.

The projection height t2by which the surface layers7bproject from the surface of the main body part7ais preferably about 500 nm to 50 μm, more preferably about 800 nm to 2 μm (seeFIG. 3). When the projection height t2of the surface layer7bis within the just-mentioned range, the sliding resistance of the valve body7on the guide wire20can be lowered relatively assuredly. The size of gaps formed between the main body part7aand the guide wire20is suppressed or reduced to such a level that a liquid cannot pass through the gap. Accordingly, the liquid-tightness at the valve body7can be relatively securely prevented from being lowered.

In addition, in the illustrated embodiment shown inFIG. 2, the plurality of surface layers7bdispersed in the form of dots are distributed evenly and regularly.

The plurality of surface layers7bprovided as above are preferably formed in a formation density of about 300 to 3000 pieces/mm2, more preferably about 1000 to 1500 pieces/mm2. When the formation density is within the just-mentioned range, both the effect of the surface layers7bon lowering the sliding resistance on the guide wire20and the effect of the main body part7aon the following-up of the shape of the opening/closing part70to the outer peripheral surface201of the guide wire20can be simultaneously realized to an extremely high extent. In addition, the main body part7ais sufficiently covered with the surface layers7bso that radiation resistance of the main body part7acan be enhanced sufficiently.

If the formation density is less than the above-mentioned lower limit, the formation density of the surface layers7bis too low to sufficiently lower the sliding resistance on the guide wire20. Also, the area of exposure of the main body part7ais so large that the radiation resistance of the main body part7amay be extremely lowered. On the other hand, if the formation density exceeds the above-mentioned upper limit, the opening/closing part70is markedly lowered in flexibility and/or elasticity, so that the liquid-tightness of the valve body7may be lowered conspicuously.

In addition, the area of each of the surface layers7bdispersed in the form of dots is preferably about 10−12to 10−3mm2, more preferably about 10−10to 10−4mm2.

Both the formation density and the area of each of the surface layers7bare so set that the proportion in which the surface layers7bcover the upper surface of the main body part7awill be within the following range described below. The just-mentioned proportion of the surface layers7bis preferably about 10% to 100%, more preferably about 20% to 90%. Consequently, a valve body7can be obtained which can simultaneously show, to a relatively high extent, both a low sliding resistance on the guide wire20and excellent liquid-tightness as well as radiation resistance.

In addition, the plurality of surface layers7bmay each be formed in any shape (pattern) in plan view other than the above-mentioned dot shape, for example, a linear shape, an irregular shape or the like.

While the plurality of surface layers7bmay be distributed regularly, they may also be distributed irregularly.

Further, the formation density of the plurality of surface layers7bmay be even or uneven, over the whole part of the valve body7.

The plurality of surface layers7bdispersed in the shape of dots may be formed not only on the upper surface of the valve body7but on the whole surface inclusive of side surfaces and a lower surface of the valve body7. In this case, a radiation resistance of the valve body7as a whole can be enhanced.

In addition, as shown inFIG. 3, an intermediate layer7cis interposed between each of the surface layers7band the main body part7a. The intermediate layer7cis composed of a material which is intermediate between the material constituting the main body part7aand the material constituting the surface layers7b, specifically a material intermediate between the silicone rubber and the silicon oxide. This helps ensure that the intermediate layer7cshows relatively high adhesion to both the main body part7aand the surface layers7b. Therefore, with the intermediate layer7cthus provided between the main body part7aand the surface layers7b, the adhesion strength of the surface layers7bto the main body part7acan be enhanced. As a result, as shown inFIG. 3, even if a high load is exerted on the surface layers7bdue to sliding of the surface layers7bon the outer peripheral surface201of the guide wire20, the surface layers7bcan be relatively securely prevented from peeling off from the main body part7a.

Further, the intermediate layer7cpreferably has a graded composition such that its composition varies gradually in the thickness direction. Specifically, it is preferable that the content of an organic component in the intermediate layer7cgradually decreases from the side of the main body part7atoward the side of the surface layer7b. Thus, in the disclosed example in which the main body part is comprised of silicon rubber, the silicon rubber contains carbon, an organic component, and this organic component decreases from the side of the main body part7atoward the side of the surface layer7b. Such an intermediate layer7cshows closeness in composition to both the main body part7aand the surface layers7b, so that it exhibits a particularly high adhesion to both the main body part7aand the surface layers7b. This facilitates a further enhanced adhesion strength between the surface layers7band the main body part7a.

The ratio between the thicknesses of the surface layer7band the intermediate layer7cis not particularly limited. Specifically, the surface layer7bmay be thicker than the intermediate layer7c, as shown inFIG. 3(a); or, on the contrary, the intermediate layer7cmay be thicker than the surface layer7b, as shown inFIG. 3(b).

A process for producing the valve body7described above will be described below.

FIGS. 4(a)-4(c)schematically illustrate aspects of a process for producing the valve body shown inFIG. 3. In the following description, the upper side inFIGS. 4(a)-4(c)is referred to as “upper” and the lower side is referred to as “lower”.

The process for producing the valve body7includes: [1] preparing a base material700composed of a silicone rubber; and [2] irradiating the upper surface of the base material700with a laser beam. Hereafter, each of these aspects of the process disclosed here will be described in detail.

[1] First, as shown inFIG. 4(a), the base material700for producing the valve body7is prepared. This base material700is composed of a silicone rubber, and has the shape of the main body part7a. In this disclosed embodiment, the base material700is composed entirely of silicone rubber. Also, the base material700is a circular disc-shaped plate material provided with a first slit751and a second slit752.

[2] Next, as shown inFIG. 4(b), the upper surface of the base material700is irradiated with a laser beam. By virtue of this, the silicone rubber in the region irradiated with the laser beam, organic groups linked as side chains to a siloxane constituting a main chain are removed through light cleavage. As a result, the base material700in the region irradiated with the laser beam is modified (vitrified) into silicon oxide, to obtain the main body part7aof the valve body7mentioned above and the surface layers7bwhich are provided on the surface of the main body part7aand are constituted of silicon oxide. The outermost portion of the base material700forming the surface layers7bare, in this disclosed embodiment, composed entirely of silicon oxide.

In this embodiment, as shown inFIG. 4(b), the irradiation with the laser beam is carried out by scanning a laser beam along the upper surface of the base material700through a photomask701having window parts (beam-transmitting parts) in a mesh-like pattern. This helps ensure that the regions reflecting the shapes of the window parts of the photomask701are irradiated with the laser beam. Therefore, a plurality of surface layers7bin the shape of dots (corresponding to the locations of the window parts) are obtained on the upper surface of the main body part7a.

In addition, since this modification is attended by cubical expansion, the silicone rubber is raised in hemispherical (dome-like) shapes from the upper surface of the base material700simultaneously with the change into silicon oxide. In this case, the quantity of heat applied to the silicone rubber by the laser beam is so distributed as to gradually decrease from the upper surface toward the inside of the base material700. Therefore, even if substantially full modification into silicon oxide occurs at the uppermost surface of the base material700, the quantity of heat is insufficient and hence parts not fully modified are generated on the lower side of the uppermost surface. Accordingly, areas where the silicone rubber and silicon oxide are present in a mixed manner are formed between the main body part7aand the surface layers7b. Thus, the above-mentioned intermediate layer7cis formed between the main body part7aand the surface layer7b. The intermediate layer7crepresents a transition from the surface layers7bof silicon oxide and the main body part7aof silicone rubber.

The wavelength of the laser beam with which to irradiate the base material700is preferably not more than 200 nm, more preferably not more than 180 nm, still preferably not more than 160 nm. This helps ensure that the laser beam has sufficiently high energy, whereby the side chains of the silicone rubber are more securely put into light cleavage, and oxygen molecules undergo photolysis, to produce a multiplicity of active oxygen atoms. As a result, the multiplicity of active oxygen atoms act on the silicone rubber, so that the silicone rubber is modified into silicon oxide in a short time and assuredly.

The lower limit of the wavelength of the laser beam is not particularly limited. In consideration of the laser beam generating cost and the damage to the main body part7a, however, the lower limit of the wavelength is about 100 nm. In addition, when the upper surface of the base material700is irradiated with the laser beam, the surface layers7bare raised and, simultaneously, the surface layers7bare formed also in regions on the inner side relative to the upper surface of the base material700. Accordingly, the surface layers7bare so formed as to be embedded from the upper surface into the inside of the base material700.

Examples of a laser beam source to be used include fluorine laser (F2 laser), ArF (argon fluoride) excimer laser, etc., among which the fluorine laser is preferably used.

The oscillation mode of the laser beam may be either continuous oscillation or pulsed oscillation. In the case of the pulsed oscillation, the energy density per pulse is preferably about 5 to 60 mJ/cm2. The number of pulses per second is about 5000 to 20000 pulses.

In addition, the atmosphere in which to irradiate with the laser beam is an inert gas atmosphere or a reduced pressure atmosphere.

As the photomask701, there can be used, for example, reticules which are used in semiconductor production processes. Other than the reticules, there can also be used mesh-shaped members, punching metals, and the like.

As an alternative to the use of the photomask701, irradiation with a laser beam may be conducted under programmed computer control such as to apply the laser beam only to preset regions.

In the above-mentioned manner, the valve body7including the main body part7a, the intermediate layers7cand the surface layers7bas shown inFIG. 4(c)is obtained.

FIG. 5is a perspective view of a second embodiment of the valve body disclosed here. The following description focuses primarily on the differences from the above-described embodiment. Features in this embodiment that are the same as the first embodiment are identified by common reference numerals and a detailed description of such features is not repeated.

This embodiment is the same as the above-described first embodiment except for a difference in the configuration of the surface layer of the valve body.

The valve body7A shown inFIG. 5has a configuration in which a surface layer7bentirely covers an upper surface (proximal end face73) of a main body part7a. In this case, the proportion in which the surface layer7bcovers the upper surface of the main body part7ais 100%. In this instance, the whole part of the upper surface (proximal end face73) of the main body part7ais completely covered with the surface layer7b, so that the chance of contact between the main body part7aand oxygen is very small. This makes it possible to obtain a valve body7which is particularly excellent in radiation resistance.

The average thickness t1of the surface layer7bshown inFIG. 5is the same as the average thickness of the surface layers7bin the first embodiment above.

A process for producing the valve body7A shown inFIG. 5is as follows.FIGS. 6(a)-6(c)schematically illustrate the process for producing the valve body shown inFIG. 5. In the following description, the upper side inFIG. 6is referred to as the “upper” and the lower side is referred to as the “lower.”

The process for producing the valve body7A includes: [1A] preparing a base material700composed of a silicone rubber; and [2A] forming the surface layer7bon the upper surface of the base material700. Hereafter, each of the steps will be described in detail.

The surface of the base material700on which is formed the surface layer7bas described later may be preliminarily subjected to a roughening treatment. Examples of the roughening treatment include a method of coating with a roughening treating agent for silicone resin, and a method of roughening the surface to be treated.

[2A] Next, as shown inFIG. 6(b), a film of silicon oxide is formed on the upper surface of the base material700. By this, a surface layer7bconstituted of silicon oxide as shown inFIG. 6(c)is formed on the upper surface of the main body part7a.

The method for forming the film of silicon oxide is not particularly limited. Examples of the method which can be used here include chemical vapor deposition methods such as plasma CVD method, thermal CVD method, etc., and physical vapor deposition methods such as vacuum evaporation method, sputtering method, ion plating method, etc.

In addition, a method may be adopted in which a film of silicon is once formed, and the silicon film is subjected to an oxidizing treatment to thereby form the surface layer7b.

In this case, as the method for forming the silicon film, the same method as the method of forming the silicon oxide film mentioned above can be used.

Besides, examples of the oxidizing treatment method include a method of exposing to ozone or hydrogen peroxide, a method of irradiating with UV rays, and a combination of these methods.

In addition, a film of silicon oxide may be formed through a mask. By this, a silicon oxide film is formed in each of regions in shapes corresponding to the shapes of window parts (through-holes) in the mask, resulting in that the surface layer7bin a predetermined shape is obtained.

As the mask, there can be used, for example, a mesh-shaped member, a punching metal or the like. By forming the film through such a mask provided with a multiplicity of window parts, for example, a plurality of surface layers dispersed in the shape of dots can be easily formed on the upper surface of the main body part7a.

In the second embodiment of the valve body and the medical instrument according disclosed here, the same effects as those of the first embodiment above can be obtained.

FIG. 7is a perspective view showing a third embodiment of the valve body disclosed here. The following description focuses primarily on differences between this third embodiment and embodiments of the valve body described earlier. Features in this embodiment that are the same as the embodiments described above are identified by common reference numerals and a detailed description of such features is not repeated.

This third embodiment is the same as the first embodiment described above except for a difference in the configuration of the valve body.

A valve body7B shown inFIG. 7is a circular disc-shaped member possessing a relatively short cylindrical overall shape (outside shape). The central portion of the valve body7B is provided with a through-hole72as an opening/closing part70capable of being opened and closed. The through-hole72is a hole extending from the distal end face71to the proximal end face73of the valve body7B, penetrating or passing completely through the valve body7. With a guide wire20inserted in the through-hole72, the outer peripheral surface201of the guide wire20slides on the inner peripheral surface721of the through-hole72, whereby liquid-tightness at the sliding surface is maintained.

The through-hole72is circularly shaped in plan-view. The inside diameter of the through-hole72in a natural condition (the condition shown inFIG. 7) is set to be approximately equal to or slightly larger than (in the configuration shown inFIG. 7, approximately equal to) the outside diameter of the guide wire20. This helps ensure that the guide wire20can inserted in the valve body7. Here, “natural condition” means the condition where no external force is applied to the valve body7.

In addition, as shown inFIG. 7, the valve body7B includes a main body part7acomposed of silicone rubber, and a surface layer7bon the inner peripheral surface of the main body7a. This helps ensure that the inner peripheral surface721of the through-hole72is a surface composed of silicon oxide.

Here, as mentioned above, the inner peripheral surface721of the through-hole72slides on the outer peripheral surface201of the guide wire20, and, since the inner peripheral surface721is composed of silicon oxide, the guide wire20can slide on the inner peripheral surface721in a slipping manner. This helps enable the operator of the guide wire20to efficiently operate the guide wire20without exerting a large force.

The surface layer7bpossessed by the valve body7B as described above may be a surface layer7branging over the whole part of the inner peripheral surface721of the through-hole72as shown inFIG. 7. However, the surface layer7bmay also be formed as a plurality of surface layers7bdistributed in the form of dots as in the first embodiment.

The surface layer7baccording to this embodiment may be one produced by either the producing method according to the first embodiment and the producing method according to the second embodiment.

In the third embodiment of the valve body and the medical instrument disclosed here, the same effects as those of the first embodiment above can be obtained.

While the valve body, the process for producing the valve body, and the medical instrument disclosed here have been described above based on the embodiments shown in the drawings, the invention here is not limited to these embodiments. Each of the components of the valve body and the medical instrument can be replaced by one with a different configuration which can exhibit the same function as above-mentioned. Also, components may be added to the construction described above.

In addition, the valve body and the medical instrument disclosed here may involve a combination of two or more configurations (features) according to the above-described embodiments.

While a connector has been shown in each of the above embodiments as an example of the medical instrument disclosed here, the medical instrument of the present invention is not limited to the connector, but may also be an introducer, an indwelling needle or the like.

In addition, while a guide wire has been shown in each of the above embodiments as an example of the elongated member inserted into and pulled out of the valve body, the elongated member is not limited to the guide wire, but may also be a sheath, a dilator, a catheter, a needle, a mouth part (distal projected part) projecting at a distal portion of a syringe outer cylinder, or the like.

The process for producing a valve as described above may include additional steps beyond those described above.

EXAMPLES

Now, specific examples implementing the disclosure here are described below.

1. Production of Connector

In each of the following Examples and Comparative Example, a plurality of valve bodies were produced.

First, a plate-shaped base material composed of a silicone rubber and provided with a first slit and a second slit was prepared.

Next, the upper and lower surfaces of the base material were each irradiated with a laser beam through a photomask under the following irradiation conditions.

Laser beam source: Fluorine laser

Formation density of beam-transmitting parts in photomask: 1000 pieces/mm2

Pattern of beam-transmitting parts: Grid

The valve bodies were produced in the above-mentioned manner.

Next, connectors as shown inFIG. 1fitted with these valve bodies were produced.

Then, one of the plurality of valve bodies obtained as above was cut, and the cut surface was observed under a scanning electron microscope. That is, the valve body is cut vertically relative to the illustration inFIG. 2so that a cross-section of the protrusions or hemispherically projecting parts7b,7ccan be seen.

As a result, a multiplicity of hemispherical projected parts (surface layers) projecting from the surface of the base material were observed to be present selectively and spaced apart in the regions irradiated with the laser beam. The projecting height of the projected parts was measured to be 1 μm.

Further, the cut surface was subjected to elemental analysis. It was found that the valve body had a main body part (corresponding to the main body part7ainFIG. 3) composed of a silicone rubber, and a surface layer(s) (corresponding to the surface layer(s)7binFIG. 3) provided on the surface of the main body part and composed of silicon oxide.

In addition, distributions of carbon and oxygen in the cut surface were analyzed by elemental mapping analysis. Then, the thicknesses of the surface layer and an intermediate layer (corresponding to the intermediate layer7cinFIG. 3) of the valve body were estimated, taking into account the facts that the content of carbon in the silicone rubber was high, that the content of oxygen in silicon oxide was high whereas the content of carbon was approximately zero, etc.

As a result, the thickness of the surface layer was estimated at about 1.5 μm, and the thickness of the intermediate layer at about 0.5 μm.

Valve bodies and connectors fitted with the valve bodies were produced in the same manner as in Example 1 above, except that the use of the photomask was omitted, and the upper and lower surfaces of a base material were entirely irradiated with a laser beam.

A surface layer spreading in a surface form was observed on the surfaces of the base material.

In addition, elemental mapping analysis of a cut surface was carried out in the same manner as in Example 1, whereon the presence of an intermediate layer was confirmed.

First, a plate-like base material composed of a silicone rubber and provided with a first slit and a second slit was prepared. Next, silicon oxide was vapor deposited on each of upper and lower surfaces of the base material. In this manner, valve bodies were produced.

Thereafter, connectors shown inFIG. 1fitted with the valve bodies were produced.

First, a plate-like base material composed of a silicone rubber and provided with a first slit and a second slit was prepared. Next, silicon was vapor deposited on each of the upper and lower surfaces of the base material.

Subsequently, each of the silicon films thus obtained was irradiated with UV rays in the presence of ozone. This resulted in oxidation of the silicon films and, hence, modification thereof into silicon oxide. In this manner, valve bodies were produced.

Thereafter, connectors shown inFIG. 1fitted with the valve bodies were produced.

Comparative Example

Valve bodies and connectors were produced in the same manner as in Example 1 above, except that the base material used in Example 1 was directly used as the valve body. A silicone oil was applied to the valve body as a lubricating liquid.

2.1 Evaluation of Sliding Properties

Ten connectors each obtained in each of the Examples and the Comparative Example described above were evaluated to assess the sliding properties, in the manner described below. In the following measurement of sliding resistance, measurement of the sliding resistance was carried out for each of five connectors not having been subjected to an EB sterilizing treatment and for five connectors having been subjected to the EB sterilizing treatment, and average of the measured values for the five connectors was used as an object of evaluation.

<1> First, ten connectors produced as above and guiding catheters (produced by Terumo Corporation) of 5 Fr in size were prepared.

Then, five connectors were subjected to an EB sterilizing (electron beam sterilizing) treatment, whereas the remaining five connectors were subjected to an EOG sterilizing (ethylene oxide gas sterilizing) treatment instead of being subjected to the EB sterilizing treatment. The intensity (absorption dose) of the electron beam used in the EB sterilization was 40 kGy.

<2> Next, the catheter was inserted in the valve body of the produced connectors.

<3> Subsequently, the cap body of the connector was rotated to the limit of rotating operation, thereby fastening (fixing) a tube with the valve body.

<4> Thereafter, in this condition, the sliding resistance in pulling out the catheter was measured. In measurement of the sliding resistance, the pulling-out amount of the catheter was 100 mm, and the pulling-out rate was 100 mm/min. Loads exerted on the catheter at the times of insertion and pulling-out were measured on an autograph. In this manner, an initial sliding resistance (unit: gf) was obtained.

<5> Next, a series of processes of inserting the catheter into the valve body of the connector and pulling out the catheter from the valve body of the connector was repeated 50 times in water.

<6> Then, the connector and the catheter were taken out of water, and the sliding resistance at the time of insertion and pulling-out of the catheter in relation to the connector was measured in the same manner as in <4> above. In this way, a sliding resistance value (unit: gf) after 50 reciprocal slides was obtained.

The results of the above measurements are shown in Table 1 andFIG. 8.FIG. 8does not include evaluation results for Example 4 because when it came time to test and evaluate this Example, the equipment was not available for testing purposes.

Referring to Table 1, first, in the condition where the EB irradiation was yet to be conducted, the evaluation results of each of the Examples and the evaluation results of the Comparative Example were compared.

The evaluation results show that for the connectors obtained in each of the Examples, the sliding resistance after 50 times of sliding showed a lowering rather than an increase as compared with the initial sliding resistance, notwithstanding that a lubricating liquid was not used. On the other hand, for the connectors obtained in the Comparative Example, the sliding resistance after 50 times of sliding showed a large increase as compared with the initial sliding resistance. It is thought that this may arise from a lowering in lubricity because of gradual leaning of the lubricating liquid attendant on the reciprocal sliding of the catheter. In other words, it is surmised that in the cases of the connectors obtained in each of the Examples, such a lowering in lubricity did not occur because no lubricating liquid was used.

In addition, a comparison between Example 1 and Example 2 shows that the connectors obtained in Example 1 showed a lower sliding resistance. This is considered to be due to the difference in the area of contact between the valve body of the each of connector and the catheter.

In the condition after the EB irradiation, the evaluation results of each of Examples and evaluation results of Comparative Example were compared.

The evaluation results show that the sliding resistance values of the connectors obtained in each of the Examples were lower than the sliding resistance values of the connectors obtained in the Comparative Example, both initially and after 50 times of sliding. It is thought hat this result may arise from the fact that the valve bodies obtained in each of the Examples were superior to the valve bodies obtained in Comparative Example in electron beam resistance (radiation resistance) and so the valve body was inhibited or prevented from being altered or deteriorated by EB irradiation.

Next, for the connectors obtained in each of the Examples and the Comparative Example, the evaluation results in the condition where EB irradiation was yet to be conducted and the evaluation results in the condition after the EB irradiation were compared. Here, it is seen that in the cases of the connectors obtained in each of the Examples, the increase in the amount of the initial sliding resistance attendant on the EB irradiation was suppressed to a comparatively low level respectively (see the arrows inFIG. 8). From this result, it can be seen that the connectors obtained in each of the Examples are less liable to yield an increase in sliding resistance values even when subjected to a sterilizing treatment by EB irradiation and, hence, it can be said that they are medical instruments capable of realizing relatively high operability while securing safety.

On the other hand, the connectors obtained in the Comparative Example showed a relatively large increase in sliding resistance value attendant on EB irradiation (see the arrow inFIG. 8). It is surmised that this arises from alteration and/or deterioration of the valve bodies obtained in the Comparative Example, under the influence of the EB (electron beam) sterilizing. Based on this, it can be said that the connectors obtained in the Comparative Example may yield an increase in sliding resistance value when subjected to a sterilizing treatment by EB irradiation.

The valve body disclosed here is a valve body having an opening/closing part which opens or closes while sliding on an inserted member. The valve body is characterized in that at least the opening/closing part includes a main body part composed of a silicone rubber, and a surface layer provided at least in an area on a surface of the main body part and constituted of silicon oxide. Therefore, it is possible to obtain a valve body which shows a sliding resistance exerted on the member less liable to increase even upon an increase in the number of times of sliding of the member to be inserted in the opening/closing part and which is excellent in radiation resistance and liquid-tightness, In addition, the configuration in which a plurality of surface layers in the shape of dots are dispersed on a surface of the main body part promises a reduction in sliding resistance, with little loss of mechanical characteristic properties such as flexibility and elasticity of the silicone rubber. Accordingly, the valve body can exhibit, to a relatively high extent, both excellent sliding properties on a member to be inserted and high liquid-tightness. Furthermore, the structure in which the surface layers in the form of dots are provided in the manner of projecting from the surface of the main body part reduces the area of the surface where the valve body slides on the member inserted in the valve body. This helps facilitate a further reduction in the sliding resistance exerted on the member.

The detailed description above describes embodiments of a valve body disclosed here, including processes for producing the valve body and a medical instrument embodying the valve body. It is to be understood that the invention is not limited to the precise embodiments and variations described above and illustrated in the drawing figures. Various changes, modifications and equivalents cab be implemented by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. It is expressly intended that all such changes, modifications and equivalents falling within the scope of the claims are embraced by the claims.