Tire reclaimed rubber is made from the rubber parts of waste tires, processed through crushing, desulfurization, and refining processes. It has certain plasticity and stickiness, and can be used as a substitute raw material for raw rubber. It can be re-added to rubber products to effectively reduce rubber costs while improving processing performance. Molded sponge shock-absorbing sealing gaskets are one such example. In actual production, molded sponge shock-absorbing sealing gaskets combine sealing, cushioning, and vibration isolation functions. They require the compound to have appropriate hardness, compression rebound, tensile strength, aging resistance, and uniform foaming. What issues should be noted when producing sponge shock-absorbing sealing gaskets with tire reclaimed rubber?
1. Tips for choosing tire reclaimed rubber for molded sponge shock-absorbing sealing gaskets
When producing sponge shock-absorbing sealing gaskets using tire reclaimed rubber, it is recommended to prioritize tire reclaimed rubber with high fineness, few impurities, stable Mooney viscosity, suitable plasticity, and certain tensile strength, as it easily mixes with additives and foams evenly. Tire tread reclaimed rubber has high mechanical strength and is suitable for producing gaskets with certain requirements for load-bearing and tear resistance; When using sponge sealing gaskets requiring long-term contact with hot air, ozone, or outdoor environments, the anti-aging system design must be considered according to working conditions, and relying solely on tire reclaimed rubber cannot be relied upon.
2. The proportion of tire reclaimed rubber mixed into the molded sponge shock-absorbing sealing gasket
When tire reclaimed rubber is added to molded sponge shock-absorbing sealing gaskets, the more reclaimed rubber used, the more obvious the cost advantage of the compound material; However, if the proportion of reclaimed rubber is too high, it can E6LYY528 affect the rebound, strength, and permanent compression deformation of the foam, so the dosage ratio should be determined based on the density, hardness, compression amount, and operating temperature of the sponge shock-absorbing gasket. In ordinary molded sponge shock-absorbing sealing gasket formulations, the proportion of tire reclaimed rubber can be appropriately increased; For sponge shock-absorbing gaskets with higher sealing reliability requirements, it is recommended to mainly use natural rubber or styrene-butadiene rubber, with an appropriate amount of 20%-40% tire reclaimed rubber.
3. Foaming system and sealing performance of tire reclaimed rubber sponge shock-absorbing sealing gaskets
When using reclaimed rubber to produce molded sponge shock-absorbing sealing gaskets, the foaming agent, accelerator, sulfur, zinc oxide, stearic acid, and foaming additives must be matched, and the foaming speed and vulcanization speed must be coordinated. In actual production, if foaming is too fast and vulcanization is insufficient, bubble collapse can easily cause bubble combination, collapse, and dimensional shrinkage; Vulcanization too quickly may limit gas expansion, resulting in small pores and high density; Excessive foaming or vulcanization both affect the sealing effect of the gasket.
Tire reclaimed rubber has already undergone one one vulcanization and regeneration during production. When designing formulas, attention must be paid to the impact of residual vulcanization systems and processing history on scorching and vulcanization rates. Molded Sponge Shock-absorbing Sealing Gasket During the molding process, it is necessary to observe changes in venting, filling, and foaming pressure; For sealing gaskets, the cells should be as uniform and dense as possible to avoid through-holes; otherwise, even a flat appearance will affect the sealing effect.
4. Key Points for Molded Sponge Shock-Absorbing Sealing Gasket Manufacturing in Tire Reclaimed Rubber
(1) Key points of the mixing process for producing molded foam, shock-absorbing sealing gaskets for tire reclaimed rubber
When producing molded sponge shock-absorbing sealing gaskets mainly from tire reclaimed rubber, excessive plasticity of the compound can easily cause excessive flow during molding; Insufficient plasticity may cause difficulties in filling and localized material shortages; It is recommended to adjust the mixing degree according to equipment pressure, mold structure, and sponge shock-absorbing gasket thickness.
(2) Key points of the vulcanization process for the production of tire reclaimed rubber molded foam shock-absorbing sealing gaskets
When reclaimed tire rubber is mixed into molded sponge shock-absorbing sealing gaskets, the molding temperature cannot directly replicate the vulcanization conditions of solid rubber gaskets. Small-scale mold trials should be conducted to observe foaming ratio, density, hardness, shrinkage rate, and surface condition to determine a reasonable vulcanization time. For producing thicker sponge gaskets with tire reclaimed rubber, attention must be paid to the temperature transfer speed inside the mold to avoid issues where the surface is already set and the internal foaming is insufficient.
For molded sponge shock-absorbing sealing gaskets with strict dimensional requirements, additional parking and curing and dimensional remeasurement after demolding should be added to avoid using the instantaneous molding size as the final dimension.
5. Molded sponge shock-absorbing sealing gasket vulcanization formula produced using a combination of natural rubber and tire reclaimed rubber
Natural rubber 70 parts, tire reclaimed rubber 30 parts, zinc oxide 5 parts, stearic acid 3.5 parts, antioxidant 4010 1 part, antioxidant RD 1 part, paraffin wax 1 part, carbon black N774 20 parts, light calcium carbonate 90 parts, engine oil 15 parts, accelerator CZ 0.75 parts, sulfur 0.95 parts, foaming agent H 2.3 parts, sodium bicarbonate 4 parts; Total: 244.5 parts.
When using tire reclaimed rubber to produce molded sponge shock-absorbing sealing gaskets, it is recommended to establish pilot data based on "reclaimed rubber ratio—foaming rate—density—hardness—compression permanent deformation"; After determining the target density, adjust the filler, softener, and foaming system so that tire reclaimed rubber truly becomes an effective component for cost reduction and processability, rather than just a cheap filler. This ensures basic sealing and cushioning performance while reflecting the cost advantages of tire reclaimed rubber in the product.
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