Nitrile reclaimed rubber, made from waste nitrile rubber products such as used nitrile gloves, retains the basic properties of nitrile rubber. It has excellent oil resistance as well as good wear resistance, heat resistance, and air tightness, making it an ideal raw material to replace expensive nitrile rubber in the production of various rubber products. In actual production, how should nitrile reclaimed rubber be added to rubber products, and how should the formulations of nitrile reclaimed rubber products be designed?
1. Application methods of nitrile reclaimed rubber in rubber products
The main purpose of nitrile reclaimed rubber is to replace nitrile rubber to reduce the cost of rubber products. The main application methods in rubber product production are fourfold:
(1) Use nitrile reclaimed rubber exclusively to produce oil-resistant and wear-resistant rubber products to effectively reduce raw material costs.
(2) Combine nitrile reclaimed rubber with natural nitrile rubber at an appropriate ratio to lower costs, improve processing performance, and enhance the overall physical properties of the finished product.
(3) Combine nitrile reclaimed rubber with general rubbers such as natural rubber, styrene-butadiene rubber, or polybutadiene (non-polar rubber).
(4) Combine nitrile reclaimed rubber with strongly polar polymers such as chloroprene rubber, modified phenolic resin, and polyvinyl chloride, especially chlorine-containing polymers; for instance, combining nitrile reclaimed rubber with PVC can further improve processing performance and aging resistance.
2. Key points in designing formulations for nitrile reclaimed rubber products
(1) Vulcanization system design for nitrile reclaimed rubber products
When producing rubber products using nitrile reclaimed rubber as the main raw material, commonly used vulcanization systems include the conventional sulfur vulcanization system (sulfur dosage is controlled at 1-2.5 parts, combined with 1-3.5 parts of thiazole or guanidine-type accelerators; low-sulfur, high-accelerator formulations can improve heat resistance and reduce compression set), sulfur-free vulcanization systems (using thiazole-type accelerators such as TMTD or disulfide morpholine DTDM instead of sulfur; these result in low compression set but are prone to blooming), and peroxide vulcanization systems (DCP dosage is controlled at 1.5-2 parts, providing excellent heat and cold resistance and minimal compression set; however, costs are high and tear strength is poor; crosslinking aids like TAIC can be added) and the like.
(2) Design of reinforcing and filling system for nitrile reclaimed rubber products
Common reinforcing agents for nitrile reclaimed rubber products include carbon black. Using high-abrasion carbon black (40-60 parts) can effectively improve mechanical strength, while semi-reinforcing carbon black (60-100 parts) balances oil resistance and compression set. For ordinary oil-resistant rubber products, semi-reinforcing carbon black, alone or with other types, is preferred. For high strength, elongation, and wear resistance, high-reinforcing carbon black is more suitable.
Common white reinforcing agents include white carbon black, thermosetting phenolic resin, and PVC resin, providing good heat resistance, oil resistance, and mechanical strength. Hard kaolin, active magnesium oxide, and active calcium carbonate can also provide reinforcement to some extent. Calcium carbonate helps increase volume and reduce costs, while kaolin delays vulcanization, so its dosage should be controlled.
(3) Antioxidant system design for nitrile reclaimed rubber products
Using appropriate antioxidants can effectively increase service life. The dosage can range from 0.5-5 parts. Combining chemical and physical antioxidants provides good protection. Light-colored products should use non-staining antioxidants. Heat-oxidation antioxidants include types A, RD, and BLE; ozone antioxidants include 4020, 4010NA, and 3100; fatigue-aging antioxidants include type H or 4020. Non-staining antioxidants for white products include 2246, MB, or 264.
(4) Softening and plasticizing system design for nitrile reclaimed rubber products
Common plasticizers include dibutyl phthalate (DBP), dioctyl phthalate (DOP), and tricresyl phosphate (TCP). For extruded products, 5-20 parts of plasticizer can yield low-shrink, smooth-surfaced materials, but it may reduce mechanical, heat, and aging resistance. Gum rosin significantly improves adhesion.
Whether used alone or combined with natural nitrile rubber, natural rubber, PVC, or others to produce various oil-resistant and wear-resistant products,合理 designing the formulation of nitrile reclaimed rubber products can reduce raw material costs while maintaining product performance.
Exclusive original article [commercial authorization] reprint, excerpt and excerpt in any form are prohibited without written authorization. Focus on Hongyun rubber: learn the process formula and raw material technology of producing rubber products from recycled rubber to help you reduce costs and increase profits