Method for molding rubber composite products

Abstract

Appropriately composite-mold rubber materials with different shapes and hardnesses. [Solution] The method includes a primary molding step of vulcanizing and molding silicone rubber 2, a pre-molding step of pre-molding unfoamed and unvulcanized foamed rubber 3a into an annular shape that covers the outer circumference of the silicone rubber 2, a placement step of placing the silicone rubber 2 that has gone through the primary molding step inside the cavity 23 of a secondary molding die 20 and placing the pre-molded unfoamed and unvulcanized foamed rubber 3a around the silicone rubber 2, and a foaming step of foaming and vulcanizing the pre-molded unfoamed and unvulcanized foamed rubber 3a inside the cavity 23 after clamping, thereby molding a rubber composite product 1 in which the silicone rubber 2 that has gone through the primary molding is covered with foamed rubber 3 while suppressing deformation of the silicone rubber 2.

Description

[[TECHNICAL FIELD]]

[0001] The present invention relates to a method for molding a rubber composite article. [[BACKGROUND ART]]

[0002] Conventionally, there has been known a metering cap integrated by two-color molding as disclosed in Patent Document 1, for example, in which an opaque cap main body is subjected to primary molding and a light-transmitting member is subjected to secondary molding. [[PRIOR ART DOCUMENTS]] [[PATENT DOCUMENTS]]

[0003] [[Patent Document 1]] Japanese Patent Application Laid-Open No. 2023-176785 [[SUMMARY OF THE INVENTION]] [[PROBLEM TO BE SOLVED BY THE INVENTION]]

[0004] The intervertebral disc is cartilage located between vertebral bodies, and functions as a shock-absorbing cushion and as a joint of the spine to enable movement of the entire spine. The intervertebral disc is composed of an outer fibrous annulus fibrosus and a central gelatinous nucleus pulposus.

[0005] However, there is a problem that intervertebral discs in conventional human body models are often made of one type of material, which cannot reproduce the movement of an actual human body, and thus may not be suitable as a model.

[0006] Unlike two-color molding of resin molded articles as in Patent Document 1, when it comes to rubber composite articles, it may be difficult to mold a rubber composite article into a desired shape while maintaining the shape of the primary molded rubbers with different hardnesses.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to appropriately composite-mold rubber materials having different shapes and hardnesses. [[MEANS FOR SOLVING THE PROBLEM]]

[0008] To achieve the above objective, this invention involves encasing a primary molded product of incompressible rubber in foamed rubber.

[0009] Specifically, in the first invention, The primary molding process involves vulcanizing and shaping incompressible rubber, A pre-forming step in which unfoamed and unvulcanized foamed rubber is pre-formed into an annular shape that covers the outer circumference of the incompressible rubber, A placement step is to place the incompressible rubber that has undergone the primary molding process inside the cavity of a secondary molding die, and to place the pre-molded, unfoamed and unvulcanized foamed rubber around the incompressible rubber, The configuration includes a foaming step in which, after mold clamping, the unfoamed and unvulcanized foamed rubber after pre-molding is foamed and vulcanized inside the cavity, thereby forming a rubber composite product in which the incompressible rubber after primary molding is covered with foamed rubber while suppressing deformation of the incompressible rubber.

[0010] According to the above configuration, the foamed rubber expands and expands within the cavity of the secondary molding die, enveloping the incompressible rubber, thus preventing excessive load from being placed on the incompressible rubber. As a result, deformation of the incompressible rubber after primary molding can be suppressed, and a rubber composite product with the intended shape can be obtained.

[0011] In the second invention, in the first invention, In the aforementioned placement step, the pre-molded, unfoamed and unvulcanized foamed rubber is placed close to the inner surface forming the cavity of the secondary molding die so as to be in contact with the inner surface forming the cavity of the secondary molding die.

[0012] According to the above configuration, the foamed rubber spreads along the inner circumferential surface that forms the cavity of the secondary molding die, eventually spreading all the way around the incompressible rubber, after which the outer surface of the incompressible rubber is enveloped by the foamed rubber.

[0013] In the third invention, in the first invention, In the placing step, the unfoamed and unvulcanized foamed rubber after preforming is placed close to the outer circumferential surface of the incompressible rubber so as to be in contact with the outer circumferential surface of the incompressible rubber.

[0014] According to the above configuration, the foamed rubber expands from around the incompressible rubber, and finally expands to the inner circumferential surface forming the cavity of the secondary molding die, after which the outer circumferential surface of the incompressible rubber is covered with the foamed rubber.

[0015] In a fourth invention, in any one of the first to third inventions, the incompressible rubber is silicone rubber, the foamed rubber is chloroprene foamed rubber.

[0016] According to the above configuration, the outer periphery of silicone rubber, which has high thermal resistance, electrical insulation and chemical stability, is covered with a chloroprene rubber foam that has good weather resistance and ozone resistance, is of closed-cell structure, and has almost no water absorption and air permeability compared with open-cell structures.

Effects of the Invention

[0017] As explained above, according to the present invention, rubber materials having different shapes and hardnesses can be appropriately composite-molded.

Brief Description of Drawings

[0018] [Figure 1] It is a cross-sectional view showing a rubber composite product. [Figure 2] It is a cross-sectional view showing a molding method for incompressible rubber, in which (a) shows a clamped state and (b) shows a state after mold opening. [Figure 3A] It is a cross-sectional view showing a state where the unfoamed and unvulcanized foamed rubber after preforming is placed close to the inner circumferential surface forming the cavity of the secondary molding die. [Figure 3B] It is a cross-sectional view showing a state where the unfoamed and unvulcanized foamed rubber after preforming is placed close to the outer circumferential surface of the silicone rubber. [Figure 4] It is a cross-sectional view showing a clamped state after foaming. [Figure 5] It is a cross-sectional view showing the state before mold clamping in the method for molding a rubber composite product according to a comparative example. [Figure 6] It is a cross-sectional view showing the method for molding a rubber composite product according to a comparative example, wherein (a) shows the mold clamped state and (b) shows the state after mold opening. MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0020] -Configuration of Rubber Composite Product- Figure 1 shows a rubber composite product 1 according to an embodiment of the present invention. In this rubber composite product 1, a silicone rubber 2 having an elliptical cross-section as an incompressible rubber is positioned at the center, the outer periphery thereof is wrapped by a foamed chloroprene rubber 3, and the rubber composite product 1 has a rectangular parallelepiped shape as a whole. This rubber composite product 1 is an intervertebral disc portion of a human body model, which is composed of the foamed chloroprene rubber 3 serving as a fiber ring made of outer fibers and the silicone rubber 2 serving as a gelatinous nucleus pulposus at the center.

[0021] -Molding Method for Rubber Composite Product- Next, a method for molding the rubber composite product 1 according to the present embodiment will be described.

[0022] First, in a primary molding step, silicone rubber 2, which is an incompressible rubber, is vulcanized and molded. Specifically, for example, as shown in Figure 2(a), a preformed product 2a of silicone rubber is placed in a cavity 13 between an upper mold 11 and a lower mold 12 of a primary molding die 10, and is held for a predetermined time at a predetermined pressure and temperature to be molded. Note that the primary molding of the silicone rubber 2 is not limited to this molding method.

[0023] Next, as shown in Figure 2(b), after the mold is opened, burrs 2b are cut off, and the primary molded product of the silicone rubber 2 is completed.

[0024] Next, in the pre-molding process, the foamed chloroprene rubber 3a, which is neither foamed nor vulcanized, is pre-molded into an annular (donut-shaped) form that covers the outer circumference of the silicone rubber 2. The pre-molding method is not particularly limited, such as extrusion molding, but it is desirable that it has a hardness sufficient to be transported while maintaining its annular shape.

[0025] Next, as shown in Figure 3A, in the placement process, the silicone rubber 2 that has undergone the primary molding process is placed inside the cavity 23 formed between the upper mold 21 and the lower mold 22 of the secondary molding die 20, and pre-molded, unfoamed and unvulcanized foamed rubber 3a is placed around the silicone rubber 2.

[0026] In this placement process, for example, the pre-molded, unfoamed and unvulcanized foamed rubber 3a is placed close to the inner surface forming the cavity 23 of the secondary molding die 20 so as to be in contact with the inner surface forming the cavity 23 of the secondary molding die 20.

[0027] In the foaming process, after mold clamping, as shown in Figure 4, the pre-molded annular unfoamed and unvulcanized foamed rubber 3a is foamed and vulcanized inside the cavity 23.

[0028] At this time, the foamed rubber 3 spreads along the inner circumferential surface that forms the cavity 23 of the secondary molding die 20, and after it has spread all the way around the silicone rubber 2, the outer surface of the silicone rubber 2 is covered with the foamed rubber 3.

[0029] This allows for the molding of a rubber composite product 1 in which the silicone rubber 2 is covered with foamed rubber 3 while suppressing deformation of the silicone rubber 2 after primary molding.

[0030] In this embodiment, the foamed rubber 3 expands and expands within the cavity 23 of the secondary molding die 20, enveloping the silicone rubber 2, thus preventing excessive load from being placed on the silicone rubber 2. As a result, a rubber composite product 1 with the intended shape can be obtained.

[0031] In this embodiment, the outer periphery of the silicone rubber 2, which has high thermal resistance, electrical insulation properties, and chemical stability, is covered with foamed chloroprene rubber 3, which has good weather resistance and ozone resistance, and is closed-celled, resulting in almost no water absorption or breathability compared to open-celled rubber.

[0032] Therefore, according to the molding method for the rubber composite product 1 of this embodiment, rubber materials with different shapes and hardnesses can be appropriately composite-molded.

[0033] -Variations- Figure 3B shows a modified example of an embodiment of the present invention, which differs from the above embodiment in that the shape of the pre-molded unfoamed and unvulcanized chloroprene rubber foam 3a' is different. In this modified example, the same reference numerals are used for parts that are the same as in Figures 1 to 3A and Figure 4, and their detailed descriptions are omitted.

[0034] In this modified example, particularly during the placement step, the pre-molded annular (smaller inner diameter than in the above embodiment) unfoamed and unvulcanized foamed rubber 3a' is placed close to the outer surface of the silicone rubber 2 so as to be in contact with the outer surface of the silicone rubber 2. The other steps are the same as in the above embodiment.

[0035] In this modified example, the foamed rubber 3a' spreads out from around the silicone rubber 2, eventually reaching the inner circumferential surface that forms the cavity 23 of the secondary molding die 20, after which the outer surface of the silicone rubber 2 is encased in the foamed rubber 3. Therefore, even in this modified example, no excessive compressive force is applied to the silicone rubber 2, and the silicone rubber 2 is molded in a stable shape and position within the chloroprene foamed rubber 3 without deforming.

[0036] -Comparative Example- Figures 5 and 6 show comparative examples of embodiments of the present invention, which differ from the above embodiments in that they involve pre-molding of incompressible rubber rather than pre-molding of foamed rubber.

[0037] In this comparative example, the primary molding of the silicone rubber 102 is the same as in the embodiment described above.

[0038] In the molding process in this comparative example, incompressible chloroprene rubber 103a is pre-molded. The incompressible chloroprene rubber 103a is pre-molded, for example, as an annular unvulcanized rubber of a size that is spaced away from the outer surface of the silicone rubber 102 and in contact with the inner surfaces of the upper mold 121 and lower mold 122 of the molding die 120.

[0039] Next, in the placement process, the pre-molded, unvulcanized chloroprene rubber 103a is placed so as to be in contact with the outer surface of the silicone rubber 102, with a gap between it and the outer surface of the silicone rubber 102.

[0040] Next, when the mold is clamped as shown in Figure 6(a), the flow of the unvulcanized chloroprene rubber 103a is uneven during the compression process, causing the silicone rubber 102 to be pushed and move within the cavity, resulting in deformation of the shape.

[0041] Finally, as shown in Figure 6(b), the mold is opened and the burrs 103b are cut off. Thus, in this comparative example, there is a problem that the silicone rubber 102 after primary molding deforms within the chloroprene rubber 103 due to the pressure applied during the compression process.

[0042] However, in the above embodiment, since the chloroprene rubber foam rubber 3 is molded to cover the silicone rubber 2, this problem does not occur.

[0043] The embodiments described above are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

[0044] For example, in the above embodiment, the rubber composite 1 is the intervertebral disc portion of a human body model, but the present invention is not limited to this, and can be applied to rubber composites in which a primary molded incompressible rubber is encased in foamed rubber. [Explanation of Symbols]

[0045] 1. Rubber composite products 2. Silicone rubber 2a Pre-molded silicone rubber part 2b Bari 3. Foamed rubber 3a, 3a' Premolded products of unfoamed and unvulcanized foamed rubber 10 Primary molding die 11 Upper mold 12 Lower mold 13 Cavity 20 Secondary molding dies 21 Upper mold 22 Lower mold 23 Cavity

Claims

1. The primary molding process involves vulcanizing and shaping incompressible rubber, A pre-forming step in which unfoamed and unvulcanized foamed rubber is pre-formed into an annular shape that covers the outer circumference of the incompressible rubber, A placement step is to place the incompressible rubber that has undergone the primary molding process inside the cavity of a secondary molding die, and to place the pre-molded, unfoamed and unvulcanized foamed rubber around the incompressible rubber, The process includes a foaming step in which, after mold clamping, the unfoamed and unvulcanized foamed rubber after pre-molding is foamed and vulcanized inside the cavity, thereby forming a rubber composite product in which the incompressible rubber after primary molding is covered with foamed rubber while suppressing deformation of the incompressible rubber. A method for molding rubber composite products characterized by the following features.

2. In the placement step, the pre-molded, unfoamed and unvulcanized foamed rubber is placed close to the inner surface forming the cavity of the secondary molding die so as to be in contact with the inner surface forming the cavity of the secondary molding die. The method for molding a rubber composite product according to feature 1.

3. In the aforementioned placement step, the pre-molded, unfoamed and unvulcanized foamed rubber is placed close to the outer surface of the incompressible rubber so as to be in contact with the outer surface of the incompressible rubber. The method for molding a rubber composite product according to feature 1.

4. The aforementioned incompressible rubber is silicone rubber, The foamed rubber is chloroprene foamed rubber. A method for molding a rubber composite product according to any one of features 1 to 3.

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