JPH0579225B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention has excellent functionality, economical efficiency, and processing stability.
This invention relates to rubber mats suitable for railroad track mats (so-called ballast mats, slab mats, ballast scattering prevention screen mats, etc.), pedestrian path mats, lawn protection mats, and other rubber mats suitable for protection, vibration isolation, sound insulation, and cushioning purposes, and their manufacturing method. (Prior Art) Conventionally, the following rubber mats are known. Rubber mat made by molding and vulcanizing ordinary rubber mixture into a slab shape. (Hereinafter referred to as "prior art") A rubber mat made of crushed rubber produced from waste materials such as old tires as the main raw material, mixed with a vulcanizing agent, and then compressed and heated to be molded. (hereinafter referred to as "prior art") A rubber mat disclosed in Japanese Patent Publication No. 63-51866, in which a base layer of vulcanized powdered rubber and a surface layer of kneaded rubber are superimposed and vulcanized under pressure to be integrated. (Hereinafter referred to as the prior art) (Problem to be solved by the invention) The rubber mat according to the prior art has a high degree of freedom in compounding and can be imparted with desired mechanical properties, making it possible to obtain a high-quality rubber mat. However, since the cost of raw materials is high and the number of processing steps increases, it is not possible to obtain an inexpensive rubber mat. Although the rubber mats according to the conventional technology are inexpensive,
It has many problems as described below. (a) Poor fracture characteristics and chips, cuts, and cracks are likely to occur. (b) Poor wear resistance and short life, especially when used for walking paths. (c) Poor surface smoothness. (d) Coloring is not possible. (e) There is a limit to the adjustment of hardness. (f) It is difficult to uniformly fill the mold, and density differences and spongy defects are likely to occur. Methods for improving these properties include, for example, ``desulfurization treatment of the surface of crushed rubber'' and ``use of a binder component such as rubber or thermoplastic resin,'' but sufficient improvements cannot be achieved. The rubber pine according to the prior art does not have sufficient durability against cracking from the ends, and especially when the rubber pine according to the prior art has holes, its lifespan is short, and it is not suitable for use in ballast scattering prevention screen mats, lawn protection pine, etc. Its use is limited to mats with a large number of holes, such as those with a large number of holes. The present invention has been made in view of the problems of the prior art, and its purpose is to provide a rubber mat with excellent mechanical properties, long life, and low cost, and a method for manufacturing the same. (Means for Solving the Problems) In order to solve the above problems, the gist of the present invention is to provide a rubber mat consisting of a layer made of a mixture mainly made of vulcanized powder rubber and a kneaded rubber sheet, the side surface of which is made of kneaded rubber. The first invention is a rubber mat characterized by being coated with a sulfurized rubber layer, and a mixture made of vulcanized powder rubber as a main raw material and a kneaded rubber sheet material are laminated in layers and heated integrally under pressure. A second invention is a method of manufacturing the rubber mat according to the first invention by molding, and in a rubber mat having a plurality of through holes made of a mixture mainly made of vulcanized powder rubber, all surfaces except one bottom surface And a third invention is a rubber mat characterized in that the entire surface of the through hole is covered with a vulcanized rubber layer of kneaded rubber, and a rubber mat characterized in that the entire surface of the through hole is covered with a vulcanized rubber layer of kneaded rubber, and a mixture mainly made of vulcanized powder rubber is coated with a plurality of cylindrical convexes. A method for manufacturing a rubber mat according to the third invention by filling a lower mold having a starting part, overlaying a kneaded rubber sheet material on top of the mixture, and integrally heat-forming the mixture while applying pressure with an upper mold. is the fourth invention. In order to impart fluidity to the kneaded rubber, the viscosity of the kneaded rubber at the molding temperature is ⁵
Must be less than 10 ⁶ poise. If the viscosity is higher than this, the fluidity of the kneaded rubber is insufficient, and it is not possible to obtain a rubber mat in which specific parts of the kneaded rubber are covered with a vulcanized rubber layer according to the present invention. The thickness of the kneaded rubber sheet must be 4% or more of the thickness of the rubber mat product after molding. If the thickness of the kneaded rubber sheet is thinner than this, the amount of kneaded rubber is insufficient, and it is therefore impossible to obtain a rubber mat in which specific parts of the present invention are covered with a vulcanized rubber layer of kneaded rubber. There is no particular restriction on the molding temperature as long as the viscosity of the kneaded rubber satisfies the above conditions, and the molding temperature is usually 120~
Temperatures in the range of 200°C are sufficient. Further, the molding pressure must be at least 5 kg/cm ² , and preferably 15 kg/cm ² or more.
If the molding pressure is less than 5 kg/cm ² , the kneaded rubber will be difficult to flow, and it will not be possible to obtain a rubber mat in which specific parts of the kneaded rubber according to the present invention are covered with a vulcanized rubber layer. (Function) The present invention configured as described above functions as follows. By laminating the mixture made of vulcanized powder rubber as the main raw material and the kneaded rubber sheet material in layers and integrally heat-molding them under pressure, the mixture made of vulcanized powder rubber as the main raw material is compressed and has fluidity. The kneaded rubber rich in rubber flows and stretches on the side surfaces of the laminate, and it is possible to obtain a rubber mat whose side surfaces are covered with a vulcanized rubber layer of the kneaded rubber. As a result, cracks from the ends can be prevented and the life of the rubber mat can be extended. In addition, in manufacturing a rubber mat having a plurality of through holes, a mixture mainly made of vulcanized powder rubber is filled into a lower mold having a plurality of cylindrical protrusions,
By overlaying the kneaded rubber sheet material on top of the mixture and integrally heat-forming it while applying pressure with the upper mold, the mixture made of vulcanized powder rubber as the main raw material is molded into the recesses excluding the protrusions in the lower mold. The highly fluid kneaded rubber flows and expands into the lower mold along the outer circumferential surface of the convex part of the lower mold and the inner circumferential surface of the lower mold. A rubber mat can be obtained in which the entire surface of the through hole is covered with a vulcanized rubber layer of kneaded rubber. Therefore, it is possible to obtain a rubber mat that not only prevents cracks from forming in the holes but also exhibits resistance to external forces comparable to that of a mat made entirely of kneaded rubber. (Example) Examples and comparative examples of the present invention will be described. First, the production of a rubber mat having a plurality of through holes will be explained based on FIGS. 1 to 5. (1) Example of the present invention A mixture 1 mainly made of vulcanized powder rubber having the composition shown in Table 1 on page 11 was prepared by forming a mixture 1 with a plurality of cylindrical protrusions 2 having a cross section as shown in FIG. A predetermined amount of the mixture was filled into the lower mold 3, and a 2 mm thick kneaded rubber sheet 4 having the composition shown in Table 2 on page 11 (Example) was laminated thereon, and the upper mold 5 was pressurized at 25 kg/ ^cm2. By heating and molding at 150°C for 30 minutes, the mixture 1 containing vulcanized powder rubber as the main raw material is compressed into the recesses 6 excluding the protrusions, and the highly fluid kneaded rubber is formed on the outer peripheral surface of the protrusions 2. 2
a and the inner circumferential surface 7 of the lower mold to flow into the lower mold 3, the mixture 1 mainly made of vulcanized powdered rubber is covered with a vulcanized rubber layer 8 of kneaded rubber, and finally It was molded into the state shown in Figure 2. FIG. 3 is a perspective view of a 25 mm thick rubber mat 9 obtained by the above molding method. As is clear from FIG. 3, the entire surface, upper surface 11 and side surface 12 of the through hole 10 are all covered with a vulcanized rubber layer 8 made of kneaded rubber. Only the lower surface opposite to the upper surface 11 is not covered with the vulcanized rubber layer of kneaded rubber. FIG. 4 is a cross-sectional view of FIG. 3 taken along line A--A. The viscosity of the kneaded rubber of this example was 2.5×10 ⁶ poise at 150° C. and γ· of 2 sec ⁻¹ . (2) Comparative Example 1 Multiple cylindrical protrusions 2 with a cross section as shown in Figure 1
Between the lower mold 3 and the upper mold 5 having As a result, a rubber mat having a thickness of 25 mm and having a plurality of through holes having a shape similar to that shown in FIG. 3 was obtained. (Not shown) (3) Comparative Example 2 A molded rubber sheet with the same shape as in Figure 3 was molded under the same conditions as in the example except that the composition of the kneaded rubber sheet was different from the example (see Table 2). Has multiple through holes
A rubber mat with a thickness of 25 mm was obtained. FIG. 5 is a sectional view of the rubber mat. As is clear from FIG. 5, only about half of the through-holes 10 of the mixture 1 mainly made of vulcanized powdered rubber are covered with the vulcanized rubber layer 8 of kneaded rubber. The viscosity of the kneaded rubber of Comparative Example 2 was ^as follows:
It was 6×10 ⁶ poise.

【table】

[Table] The viscosity of the kneaded rubber used in the rubber mat of this example is as low as 2.5×10 ⁶ poise at a molding temperature of 150°C and γ of 2 sec ^-1 . It is relatively thick at 8% (2mm/25mm) of the product thickness, and the molding pressure is sufficiently large at 25Kg/ ^cm2 .
The kneaded rubber sufficiently fluidized and expanded, and as described above, all surfaces except the lower surface and the entire surface of the through hole 10 were covered with the vulcanized rubber layer 8 of the kneaded rubber. However, in Comparative Example 2, the viscosity of the kneaded rubber at the molding temperature was too high, resulting in insufficient fluidity. It is simply covered with a layer of vulcanized rubber. Next, in order to evaluate the performance of the rubber mats obtained in Examples, Comparative Examples 1 and 2, a compression fatigue test was conducted. The test conditions were: precompression 16%, amplitude ±8%, frequency 5Hz, and temperature 20°C. As a result, Comparative Example 1 consisting only of vulcanized powder rubber
The rubber mat of Comparative Example 2 developed cracks on the inner surface of the hole after 350,000 cycles, and the rubber mat of Comparative Example 2 developed cracks on the inner surface of the hole after 400,000 cycles. However, no cracks were observed in the rubber mat of this example even after 1.5 million cycles. Figures 6a to 6d show examples in which rubber mats without holes were molded by the method according to the present invention, and the molding temperature and
The molding pressure was the same as in the example described above. a~d
In all cases, the total thickness of the rubber mat is 25
mm, the thickness of the kneaded rubber sheet 4 is 2 mm, the mixture 1 containing vulcanized powder rubber as the main raw material, and the formulation of the kneaded rubber sheet 4 are the same as those in Table 1 and Table 2 (Examples), respectively. FIG. 6a is a cross-sectional view of a rubber mat 9a obtained by laminating a mixture 1 made of vulcanized powder rubber as a main raw material between kneaded rubber sheets 4 on the upper and lower surfaces in a sanderch structure, and heating and forming the mixture under pressure. Figure b is a cross-sectional view of a rubber mat 9b obtained by stacking a kneaded rubber sheet 4 on top of a mixture 1 mainly made of vulcanized powder rubber and heat-forming it under pressure, and Figure 6 c is a top view of the kneaded rubber sheet 4. Figure 6d is a cross-sectional view of a rubber mat 9c obtained by laminating the mixture 1 made of vulcanized powder rubber as the main raw material and heat-molding it under pressure. FIG. 9 is a cross-sectional view of a rubber mat 9d obtained by sandwiching the mixture 1 and laminating them in a sandwich structure and heat-forming them under pressure. The side surfaces 12a of all the rubber mats in FIGS. 6a-d are coated with a vulcanized rubber layer 8 of kneaded rubber. In addition, as shown in Fig. 6a, a rubber mat made of a mixture 1 mainly made of vulcanized powder rubber and covered entirely with a vulcanized rubber layer 8 of kneaded rubber has almost the same function as a rubber mat made entirely of kneaded rubber. able to demonstrate. Furthermore, as shown in FIG. 7, when attempting to manufacture a rubber mat having a cross section as shown in FIG. Even if it occurs,
The kneaded rubber sheet 4 flows and can eliminate spongy defects due to uneven preparation. (Effects of the Invention) The present invention configured as described above has the following effects. In the rubber mat according to the first aspect, since the side surfaces are covered with a vulcanized rubber layer of kneaded rubber, it is possible to prevent cracks from occurring from the ends. In the rubber mat according to claim 3, since all surfaces except one bottom surface and the entire surface of the through hole are covered with a vulcanized rubber layer of kneaded rubber, it has a function comparable to that of a rubber mat made entirely of kneaded rubber. , it is possible to achieve a longer life. By the manufacturing method according to claim 2 or 4, a long-life rubber mat with excellent mechanical properties can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the molded state of a rubber mat having a plurality of through holes according to the present invention, FIG. 3 is a perspective view of a rubber mat having a plurality of through holes according to the present invention, FIG. 4 is a sectional view taken along line A-A in FIG. 3, and FIG.
The figure is a cross-sectional view of the rubber mat of Comparative Example 2, Figure 6 a~
d is a sectional view of a rubber mat having no through holes according to the present invention, and FIG. 7 is a sectional view showing another embodiment related to FIG. 6b. 1...Mixture containing vulcanized powder rubber as the main raw material, 2...
Convex portion, 3... Lower mold, 4... Kneaded rubber sheet, 5...
Upper mold, 6... Recess, 7... Inner peripheral surface, 8... Vulcanized rubber layer of kneaded rubber, 9, 9a, 9b, 9c, 9d... Rubber mat, 10... Through hole, 11... Upper surface, 12, 12
a...Side surface, 13...Part where preparation was insufficient.

Claims (1)

[Scope of Claims] 1. A rubber mat comprising a layer made of a mixture of vulcanized powdered rubber as a main raw material and a kneaded rubber sheet, characterized in that the side surface is covered with a vulcanized rubber layer of kneaded rubber. 2. The method for producing a rubber mat according to claim 1, wherein the mixture containing vulcanized powder rubber as a main raw material and the kneaded rubber sheet material are laminated in layers and integrally heat-molded under pressure. 3. In a rubber mat having a plurality of through holes made of a mixture mainly made of vulcanized powder rubber, all surfaces except one bottom surface and the entire surface of the through holes are covered with a vulcanized rubber layer of kneaded rubber. A rubber mat featuring: 4 A mixture made mainly of vulcanized powder rubber is filled into a lower mold having a plurality of cylindrical protrusions, and a kneaded rubber sheet material is layered on top of the mixture and pressed together while being pressurized by an upper mold. 4. The method of manufacturing a rubber mat according to claim 3, wherein the rubber mat is heated and molded.