This site on January 10th, the function of the fence in the rubber shoes is to bond the bottom and the bottom, and the second is to protect the upper from wear. Due to the frequent bending of the fence. And the junction between the two materials is the biggest part of the deformation of the rubber shoes, especially the toe and toe area. The resistance to flexion of all the belts is critical. At the same time, due to contact with the outside world, the fence is exposed to weather and dynamic fatigue for a long time. , so its aging resistance is also particularly important.
1 rubber selection
General use of natural rubber, commonly used 1 # -3 # smoke film adhesive, bright products should consider the use of light-colored film, high-grade white wall selection Baiji films, 1 # standard rubber, the choice of synthetic rubber must be non-polluting type, such as Butadiene benzene SBR-1502 or butadiene BR9000, generally do not exceed the amount of 15 parts, with dissolved butylbenzene in 20-30 parts.
2. Vulcanization system selection
All natural rubber wrap, sulfur content control in 2.0-2.2 copies, to prevent blooming. Accelerators use AB type, such as M+XP+DM. The proportion of M and XP used has a great influence on the curing speed and product performance.
When M/XP = 1:1, the vulcanization speed is fast, but the scorch performance is poor, and the vulcanizate has high tensile strength but poor flexing resistance and aging resistance. When M/XP=3:1, the scorch properties are better, the vulcanization speed is slightly slower, the tensile strength is lower, and the flexing resistance and aging resistance are good. M/XP = 2:1 performance in between.
In systems with M/XP=2:1, the amount of DM must be increased to speed up the cure. When M/DM = 1:1, the scorch performance is the best, and the vulcanization speed is also faster. Considering the factors such as process, physical properties and adhesion, it is better to use the M/DM=1:1 system. M+XP+DM=0.85+0.4+0.85 in the black fence, and M+XP+DM=0.5+0.25+0.5 is better for the white fence. The active agent still uses zinc oxide and stearic acid.
The amount of stearic acid is generally less than 1 part to prevent ejection. If zinc oxide is used as a direct method, the content of copper and manganese is high, and the strip tends to lose luster or become sticky during the vulcanization process. In order to overcome the tarnish phenomenon, the vulcanization system must be adjusted to increase the combined use ratio of the accelerator M. During vulcanization, the hot air vulcanization time should be appropriately shortened, and the mixed gas vulcanization time should be appropriately extended to increase the amount of steam.
3. Anti-aging agent selection
Antioxidants are the main components to be considered in the adhesive strip.
The non-pollution products that are resistant to flexing fatigue and sunlight aging should be selected. The difficulty is that the non-pollution products are generally resistant to scratching and fatigue. In the case of last resort, they must be prioritized to meet the requirements of non-discoloration and non-pollution.
Dark-colored fences generally use anti-aging agent A, anti-aging agent 4010 and antioxidant H together.
Light-colored fences generally use antioxidants MB, 2246, 264, SP-C, etc., and can also be used anti-aging agents that do not change color and are resistant to flexion fatigue and sunlight aging, such as antioxidant DOD.
However, it should be noted that the accelerator M has an inhibitory effect on the anti-aging properties of the antioxidant MB, and the accelerator XP promotes the improvement. When direct zinc oxide is used as an active agent, an anti-aging agent MB is required. If used together with antioxidant SP, the effect is better, and the flex fatigue performance of the enclosure can be improved.
4. Filler selection
In order to improve the fatigue resistance, black reinforcing strips must be made of carbon black that is not very strong, and a large number of inert materials are used.
Light-colored bars are generally based on calcium carbonate and use 15-20 parts of Lithopone. Unactivated calcium carbonate has no reinforcing effect on the rubber, but its crystalline phase structure has a great influence on the physical properties of the vulcanizate. The needle-like monoclinic crystals are the best, and the diamond-shaped crystals are the best when the bending fatigue and the tensile strength are improved. Amorphous body is poor.
Activated calcium carbonate is known as Bai Yanhua and has a slight reinforcing effect on rubber. The high density of lithopone makes it possible to increase the volumetric gel content of the strip.
5 softening plasticizer selection
Dark-colored round bars are generally selected from solid Coumarone resin and industrial grease. Light-colored round bars generally use Vaseline (1-3 parts), which does not affect the gloss of the rubber material and can delay the diffusion of oxygen, thus playing an anti-aging effect.
Because petrolatum retards the diffusion of oxygen, it can also act as an anti-aging agent. Vaseline can prevent the calcium carbonate from being sprayed. Excessive amount can easily make the product lose its luster. According to the need of operation, some spindle oils, light diesel oil or calcium grease can also be used together as the processing assistant.
6. Colorant selection
With the light color of cloth shoes, the wrap is generally based on white color, red, blue, green, yellow and other bright colors, so the choice of colorant is very important. The main points selected are strong coloring, bright color, no migration of surface, high temperature resistance, steam resistance, no discoloration, resistance to sunlight, and water insolubility.
In addition, 5 to 20 parts of titanium dioxide or lithopone may be added to make the color brighter. Inorganic colorants such as chrome yellow, chrome green, red iron oxide, yellow iron oxide, etc. are stable in color but not sufficiently bright.
Organic colorants have strong coloring power and must be selected from non-removable and non-polluting types, such as LG Rubber Red, Lisol Red, Fast Yellow, Hansha Yellow, Green Green, Titanium Phthalocyanine Blue, and Phthalocyanine Green. The organic colorant is not easy to disperse evenly. In order to avoid chromatic aberration, it is better to make the colorant masterbatch.
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