Method for manufacturing silicone rubber molded products

Abstract

To provide a method for manufacturing a silicone rubber molded body, which can improve an adhesion strength of a coating material formed on a surface.SOLUTION: A method for manufacturing a sheath 5 that is a silicone rubber molded body includes: a first step of extruding a silicone rubber material to obtain an uncured molded body 501 with a predetermined shape; a second step of attaching a liquid coating material 502 to a surface 501a of the uncured molded body 501; and a third step of heating the uncured molded body 501 and the liquid coating material 502 to harden the uncured molded body 501 together with the liquid coating material 502.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a silicone rubber molded body.

Background Art

[0002] Conventionally, for example, silicone rubber has been used as a material for the sheath of a probe cable used in an ultrasonic imaging device. In order to suppress the stickiness of the surface of the sheath and improve the slidability, the applicant has proposed a cable in which the surface of a sheath made of silicone rubber is coated (see Patent Document 1).

[0003] The cable described in Patent Document 1 includes a plurality of coaxial cables, a shield covering the plurality of coaxial cables, and a sheath made of silicone rubber covering the shield, and a film is formed on the surface of the sheath. This film is an addition reaction type silicone rubber coating agent as the base material, and the adhesion strength with the sheath is 0.30 MPa or more.

[0004] The production of such a silicone sheath cable has been carried out by forming a sheath by extruding and heat-curing silicone rubber, then attaching a liquid thermosetting coating material to the surface of this sheath and heating it to form a cured film of the thermosetting coating material.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] For example, in silicone rubber molded bodies with a coating formed on the surface, such as the sheath of the probe cable mentioned above, high adhesion strength of the coating is desirable for improved durability. However, it has been difficult to further increase the adhesion strength of the coating by improving the material while following conventional manufacturing methods.

[0007] Therefore, the present invention aims to provide a method for manufacturing a silicone rubber molded article that can increase the adhesion strength of the coating material formed on the surface. [Means for solving the problem]

[0008] The present invention aims to solve the above problems and provides a method for manufacturing a silicone rubber molded body, comprising: a first step of extruding a silicone rubber material to obtain an uncured molded body of a predetermined shape; a second step of applying a liquid coating material to the surface of the uncured molded body; and a third step of heating the uncured molded body and the liquid coating material to cure the uncured molded body together with the liquid coating material. [Effects of the Invention]

[0009] According to the method for manufacturing a silicone rubber molded article of the present invention, it is possible to increase the adhesion strength of the coating material. [Brief explanation of the drawing]

[0010] [Figure 1] (a) is an external view showing an ultrasonic probe in which a silicone rubber molded body according to an embodiment of the present invention is used as a sheath for the probe cable. (b) is a cross-sectional view of (a) along line AA. [Figure 2] This is a schematic diagram showing the configuration of the manufacturing equipment used to produce the sheath. [Figure 3] (a) to (c) are cross-sectional views of lines BB, CC, and DD in Figure 2. [Figure 4](a) is a schematic diagram showing the silicone molecular chains of the uncured molded body and the silicone molecular chains of the liquid coating material. (b) is a schematic diagram showing the state in which the uncured molded body and the liquid coating material are crosslinked by heating, and the silicone molecular chains are bonded at multiple crosslinking points. [Figure 5] (a) is a schematic diagram of a comparative example showing a state in which a liquid coating material is applied to the surface of a substrate that has been heat-cured from an uncured molded body. (b) is a schematic diagram of a comparative example showing a state in which the liquid coating material applied to the surface of the substrate has been heat-cured. [Modes for carrying out the invention]

[0011] [Embodiment] Figure 1(a) is an external view showing an ultrasonic probe 1 in which a silicone rubber molded body according to an embodiment of the present invention is used as the sheath 5 of the probe cable 10. Figure 1(b) is a cross-sectional view taken along line AA of Figure 1(a).

[0012] The ultrasound probe 1 is used by a clinical laboratory technician to diagnose a patient and comprises a probe cable 10, a transducer 11 provided at one end of the probe cable 10, a probe connector 12 provided at the other end of the probe cable 10, and a protective boot 13 provided at the end of the probe cable 10 on the transducer 11 side. The transducer 11 has an ultrasonic transmitting and receiving wavefront 11a that is pressed against the surface of the patient's body. The probe connector 12 is connected to an image forming apparatus that performs ultrasonic image formation processing.

[0013] During the examination, the clinical laboratory technician presses the ultrasonic transmitting and receiving wavefront 11a of the transducer 11 against the subject's body surface at various angles, causing the probe cable 10 to rub against the subject's body and the clinical laboratory technician's clothing. After the examination is completed, the probe cable 10 is disinfected using disinfectant solution or ultraviolet disinfection with UVC (deep ultraviolet light with a wavelength of 200 to 280 nm). The length of the probe cable 10 is, for example, 2 to 3 meters.

[0014] As shown in Figure 1(b), the probe cable 10 comprises a cable core 20 containing a plurality of signal lines 2, a retaining tape 3 wrapped around the outer circumference of the cable core 20, a braided shield 4 covering the outer circumference of the retaining tape 3, and a sheath 5 covering the outer circumference of the braided shield 4. The signal lines 2 are coaxial cables having an inner conductor and an outer conductor, with one end connected to the ultrasonic sensor of the transducer 11 and the other end connected to the connector pin of the probe connector 12. The braided shield 4 is constructed by braiding a plurality of shield strands 41 in a grid pattern. The outer diameter of the probe cable 10 is, for example, 5 mm or more and 11 mm or less.

[0015] The sheath 5 is a silicone rubber molded body in which the outer surface of a tubular base material 51 made of silicone rubber material is covered with a covering material 52. The thickness of the base material 51 is, for example, 0.5 mm to 1.5 mm. The thickness of the covering material 52 is, for example, 20 μm to 50 μm. By covering the base material 51, the covering material 52 suppresses the stickiness of the silicone rubber, also known as tackiness, and improves the slipperiness (sliding properties) of the probe cable 10. The covering material 52 is formed around the entire circumference of the base material 51 along the entire length of the sheath 5. The static friction coefficient of the covering material 52 is, for example, 0.50 or less. In order to suppress the deterioration of the sheath 5 due to UVC irradiation, an ultraviolet absorber may be incorporated into either or both of the base material 51 and the covering material 52.

[0016] The boot 13 is made of a tubular rubber material and is bonded and fixed to the outer circumference of the covering material 52 with adhesive 14. The boot 13 prevents the probe cable 10 from being bent at a large curvature and protects the probe cable 10.

[0017] It is desirable that the covering material 52 of the sheath 5 adheres to the base material 51 with high adhesion strength so that it does not easily peel off even when rubbed against the body of the subject or the clothes of the clinical technician. Also, if the adhesion strength of the covering material 52 is low, when the boot 13 is bent, the covering material 52 is pulled by the boot 13 through the adhesive 14 and peels off from the base material 51. Therefore, from this point as well, it is required that the covering material 52 adheres to the base material 51 with high adhesion strength.

[0018] In the present embodiment, in order to meet this requirement, the sheath 5 is formed by a manufacturing method different from the conventional manufacturing method, and the adhesion strength of the covering material 52 is increased. Next, the manufacturing method of the sheath 5 will be described.

[0019] FIG. 2 is a schematic configuration diagram showing a schematic configuration example of manufacturing equipment 6 used for manufacturing the sheath 5. FIG. 3(a) is a cross-sectional view taken along line B-B of FIG. 2. FIG. 3(b) is a cross-sectional view taken along line C-C of FIG. 2. FIG. 3(c) is a cross-sectional view taken along line D-D of FIG. 2.

[0020] The manufacturing equipment 6 includes an extruder 61, a tank 62, a replenishment introduction tube 63, an electric furnace 64, a pulley 65, and a winder 66. The cable base 100 is continuously supplied to the extruder 61 from the supply drum 71. The cable base 100 is an object to be covered with the sheath 5 and has a cable core 20, a press winding tape 3, and a braided shield 4 as shown in FIG. 3(a). A winding drum 72 for winding the probe cable 10 having the sheath 5 formed on the outer periphery of the cable base 100 is set on the winder 66.

[0021] The manufacturing method of the sheath 5 includes a first step of extruding a silicone rubber material to obtain an uncured molded body 501 with a predetermined shape, a second step of attaching a liquid coating material 502 to the surface of the uncured molded body 501, and a third step of heating the uncured molded body 501 and the liquid coating material 502 to cure the uncured molded body 501 together with the liquid coating material 502. The uncured molded body 501 becomes the base material 51 by curing. The liquid coating material 502 becomes the coating material 52 by curing. In the present embodiment, the uncured molded body 501 is hollow and linear, and the liquid coating material 502 adheres to the outer surface 501a of the uncured molded body 501.

[0022] In the first step, the cable base 100 is supplied from the supply drum 71 to the extruder 61, and the silicone rubber material is extruded and formed on the outer periphery of the cable base 100 by the extruder 61. The thermosetting silicone rubber, which is the sheath material, is supplied to the extruder 61 through the material inlet 611. In the first step, the uncured molded body 501 having a length longer than the length of the probe cable 10 used for one ultrasonic probe 1 is continuously fed out from the extruder 61. The uncured molded body 501 fed out from the extruder 61 is clay-like, and its surface 501a is not cured.

[0023] In the second step, while moving the uncured molded body 501 fed out from the extruder 61 in its longitudinal direction, the liquid coating material 502 is attached to the surface 501a of the uncured molded body 501. More specifically, the uncured molded body 501 fed out from the extruder 61 is passed through the tank 62 in which the liquid coating material 502 is stored, so that the liquid coating material 502 is attached to the surface 501a of the uncured molded body 501.

[0024] In the configuration example of the manufacturing equipment 6 shown in FIG. 2, the tank 62 is arranged in the lateral direction on the outlet side of the extruder 61, and the uncured molded body 501 fed out laterally from the extruder 61 enters the tank 62 without being heated as it is. The tank 62 has an inlet portion 62a and an outlet portion 62b. The uncured molded body 501 that has entered the tank 62 from the inlet portion 62a passes through the tank 62 laterally toward the outlet portion 62b so that its longitudinal direction is horizontal.

[0025] Furthermore, a cover 621, such as a gasket or felt, is attached to the inlet 62a to cover the uncured molded body 501 and prevent leakage. At the outlet 62b, a felt material 622 with holes through which the uncured molded body 501 can pass is attached in order to adhere the liquid coating material 502 to the surface 501a of the uncured molded body 501. The liquid coating material 502 that has permeated the porous body of the felt material 622 can adhere to the surface 501a. Liquid coating material 502 is replenished into the tank 62 as needed from the replenishment introduction tube 63.

[0026] As the liquid coating material 502, for example, as described in Patent Document 1 above, a mixture of a silicone rubber coating agent containing an addition reaction type silicone rubber, silicone resin or silica fine particles, a viscosity adjusting solvent such as toluene or benzene, and a curing catalyst can be used. However, it is not limited to this, and any thermosetting material that has high adhesion to silicone rubber and high sliding properties after curing can be used as the liquid coating material 502. For example, a filler to improve sliding properties may be added to the liquid coating material 502.

[0027] In the third step, the uncured molded body 501 to which the liquid coating material 502 is attached is heated in an electric furnace 64 while being moved in its longitudinal direction, causing the silicone rubber of the uncured molded body 501 and the liquid coating material 502 to crosslink simultaneously. To promote this crosslinking, it is preferable to use a catalyst such as platinum. The uncured molded body 501 and the liquid coating material 502 are dried and cured by heating in the electric furnace 64. In the example configuration of the manufacturing equipment 6 shown in Figure 2, the electric furnace 64 is positioned laterally to the tank 62, and a pulley 65 is positioned further forward in the direction of the wire feed from the electric furnace 64. The uncured molded body 501 moves inside the electric furnace 64 so that its longitudinal direction is horizontal.

[0028] The temperature and horizontal length of the electric furnace 64 are set so that hardening progresses to a degree that prevents plastic distortion or peeling of the sheath 5 even when the probe cable 10, which has hardened from the unhardened molded body 501 and the liquid coating material 502 into a single sheath 5, is guided by the pulley 65 and wound onto the winding drum 72.

[0029] The probe cable 10, having passed through the electric furnace 64, is guided by a pulley 65, changes direction, and is wound onto a winding drum 72 located below the pulley 65. The probe cable 10 wound onto the winding drum 72 is cut to a predetermined length, terminated, and the transducer 11, probe connector 12, and boot 13 are attached to complete the ultrasonic probe 1.

[0030] Furthermore, as shown by the dashed line in Figure 2, a surface roughening step may be provided between the first and second steps to roughen the surface 501a of the uncured molded body 501. Figure 2 shows the case where the surface roughening step is performed by dry ice blasting using a dry ice blasting apparatus 68. The dry ice blasting apparatus 68 includes a dry ice blasting machine 681 that supplies dry ice pellets 680, a compressor 682 that supplies compressed air to the dry ice blasting machine 681, a transport hose 683 that transports the dry ice pellets 680 supplied from the dry ice blasting machine 681, and an injection nozzle 684 attached to the end of the transport hose 683 that sprays the dry ice pellets 680. By performing dry ice blasting on the uncured molded body 501, an anchoring effect is obtained in which the contact area between the uncured molded body 501 and the liquid coating material 502 is increased, and the adhesion strength between the base material 51 and the coating material 52 can be further increased.

[0031] Figure 4(a) is a schematic diagram showing the silicone molecular chains 81 of the uncured molded body 501 and the silicone molecular chains 82 of the liquid coating material 502 near the interface 500 (see Figure 3(c)) between the uncured molded body 501 and the liquid coating material 502. Figure 4(b) is a schematic diagram showing the state in which the uncured molded body 501 and the liquid coating material 502 are crosslinked by heating, and the silicone molecular chains 81 and 82 are bonded at multiple crosslinking points 9. In this embodiment, the liquid coating material 502 is attached to the surface 501a of the uncured molded body 501, which has many reactive groups, and the uncured molded body 501 and the liquid coating material 502 are heated and cured together. As a result, the degree to which the silicone molecular chains 81 of the uncured molded body 501 and the silicone molecular chains 82 of the liquid coating material 502 react directly is increased, and the coating material 52 adheres to the substrate 51 with high adhesion strength.

[0032] (Comparative example) Figure 5(a) is a schematic diagram showing the state in which a liquid coating material 502 is applied to the surface of a substrate 51 which has been heat-cured from an uncured molded body 501. Figure 5(b) is a schematic diagram showing the state in which the liquid coating material 502 applied to the surface of the substrate 51 has been heat-cured. In this way, when silicone coating is applied to the surface of a cured (crosslinked) substrate 51, since the crosslinking reaction of the substrate 51 has already been completed, there are only a very small number of reactive groups remaining on the surface. Therefore, even if the uncured silicone material of the liquid coating material 502 is applied to that surface and cured, it is difficult to obtain stable and high adhesion.

[0033] (Operation and Effects of the Embodiment) In the embodiments described above, the liquid coating material 502 is applied to the uncured molded body 501, and both are heated and cured together. Therefore, compared to the case where only the uncured molded body 501 is heated and cured before applying the liquid coating material 502, as shown in Figure 5, for example, there are many active bonding hands on the surface 501a of the uncured molded body 501, making it possible to increase the adhesion strength of the coating material 52 to the substrate 51.

[0034] Furthermore, in the above embodiment, the uncured molded body 501 continuously fed from the extruder 61 is moved longitudinally while the liquid coating material 502 is applied to its surface 501a, and then the uncured molded body 501 with the liquid coating material 502 applied is heated while it is moved longitudinally. As a result, the sheath 5 of the long probe cable 10 can be formed continuously in a series of steps, the manufacturing equipment 6 can be configured simply, and the time required for manufacturing can be shortened.

[0035] Furthermore, in the above embodiment, since the liquid coating material 502 is applied to the surface 501a of the uncured molded body 501 immediately after it is fed out of the extruder 61, it becomes unnecessary to provide a cleaning step between the first and second steps. In other words, for example, if only the uncured molded body 501 is heated and cured, wound onto a drum, and transferred to equipment for applying the liquid coating material 502, and the liquid coating material 502 is applied by this equipment, it is necessary to clean the body before application to prevent contamination with foreign matter. However, in the above embodiment, since the liquid coating material 502 is applied immediately after extrusion molding by the extruder 61 and then heated, the above-mentioned cleaning step becomes unnecessary.

[0036] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0037] [1] A method for manufacturing a silicone rubber molded body (sheath 5), comprising: a first step of extruding a silicone rubber material to obtain an uncured molded body (501) of a predetermined shape; a second step of applying a liquid coating material (502) to the surface (501a) of the uncured molded body (501); and a third step of heating the uncured molded body (501) and the liquid coating material (502) to cure the uncured molded body (501) together with the liquid coating material (502).

[0038] [2] A method for manufacturing a silicone rubber molded body (5) as described in [1] above, wherein the uncured molded body (501) is linear, in the first step the uncured molded body (501) is continuously fed from an extruder (61), in the second step the uncured molded body (501) fed from the extruder (61) is moved in its longitudinal direction while a liquid coating material (502) is attached to the surface (501a) of the uncured molded body (501), and in the third step the uncured molded body (501) to which the liquid coating material (502) has been attached is heated while it is moved in its longitudinal direction.

[0039] [3] A method for producing a silicone rubber molded article (5) according to [1] or [2], further comprising a surface roughening step between the first step and the second step, in which the surface (501a) of the uncured molded article (501) is roughened.

[0040] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention.

[0041] Furthermore, the present invention can be implemented with appropriate modifications without departing from its spirit. For example, in the above embodiment, the uncured molded body 501 is moved in the first to third steps so that its longitudinal direction is horizontal, but the uncured molded body 501 can also be raised or lowered in the vertical direction in the first to third steps. In this case, the thickness of the rubber material and liquid coating material 502 of the uncured molded body 501 before curing will not be uneven due to the influence of gravity, and variations in the thickness of the base material 51 and the coating material 52 can be suppressed.

[0042] Furthermore, although the above embodiment describes a case in which the liquid coating material 502 is applied to the surface 501a of the uncured molded body 501 by passing it through the tank 62, the invention is not limited to this. For example, the liquid coating material 502 may be applied to the surface 501a of the uncured molded body 501 by directly supplying the liquid coating material 502 to a felt material, or the liquid coating material 502 may be applied by a brush or sponge (porous roll). Alternatively, the liquid coating material 502 may be applied by spraying.

[0043] Furthermore, although the above embodiment described the case of manufacturing the sheath 5 of the probe cable 10 used in the ultrasonic probe 1, it is also possible to manufacture the sheath of cables other than the probe cable 10 using the manufacturing method of the present invention.

[0044] Furthermore, while the above embodiment described the manufacturing of a sheath 5 as an example of a silicone rubber molded article, the manufacturing method of the present invention is not limited to this, and can also be used to manufacture medical hollow tubes such as catheters. Moreover, the silicone rubber molded articles manufactured by the manufacturing method of the present invention are not limited to medical use; for example, vehicle wipers, electrical product casings, or pipes for circulating liquids or gases can also be manufactured using the manufacturing method of the present invention. [Explanation of symbols]

[0045] 5...Sheath (silicone rubber molded body) 51...Base material 52...Covering material 501...Uncured molded body 501a...Surface 502...Liquid coating material 6...Manufacturing equipment 61...Extruder 62... Tank 63... Electric furnace 68... Dry ice blasting device

Claims

1. A first step involves extruding a silicone rubber material to obtain a linear, uncured molded body, A second step involves applying a silicone rubber coating agent, which is a mixture of silicone resin, silica fine particles, a viscosity-adjusting solvent, and a curing catalyst, to the surface of the uncured molded body. A third step involves heating the uncured molded body and the silicone rubber coating agent to cure the uncured molded body together with the silicone rubber coating agent, thereby using the uncured molded body as a base material and the silicone rubber coating agent as a coating material for the base material. Equipped with, In the first step described above, the uncured molded body is continuously fed from the extruder, In the second step, the uncured molded body fed out of the extruder is moved in its longitudinal direction while the silicone rubber coating agent is applied to the surface of the uncured molded body. In the third step, the uncured molded body to which the silicone rubber coating agent is attached is heated while being moved in its longitudinal direction. The static friction coefficient of the coating material is 0.50 or less. A method for manufacturing a silicone rubber molded article.

2. The process further includes a surface roughening step between the first step and the second step, in which the surface of the uncured molded body is roughened. A method for producing a silicone rubber molded article according to claim 1.

Images