Yihuaping rubber is a polymer of ethylene and vinyl acetate. Its chemical name is ethylene vinyl acetate rubber, or EVM for short. Yihuaping is the registered trademark of this type of rubber produced by Alangshenko Company. The chemical composition of EVM is the same as EVA, which is a polymer of ethylene and vinyl acetate. However, due to different synthesis methods, the differences between the two are obvious. EVA is a polymer with low vinyl acetate content (mass fraction less than 0.4), low degree of branching and high crystallinity. It is a plastic and is widely used in hot melt adhesive and shoemaking industries. EVM is an amorphous polymer with high vinyl acetate content (mass fraction 0.4-0.8) and high degree of branching. It belongs to rubber. Vulcanized rubber with excellent performance can be obtained through reasonable combination.

So Yihuaping rubber is a special rubber. It is resistant to high temperature (175°C), oil resistance (equivalent to nitrile rubber with an acrylonitrile ACN content of 26-34), and weather aging resistance (second only to EPDM) and flame retardant are excellent. In recent years, it has been widely used in products such as cables, rubber rollers, household appliances, and automotive rubber accessories. It has become an irreplaceable new raw material for some special rubber products.

Ingredients:

Special rubber - EVM (EVM) performance characteristics and market applications

EVM is composed of ethylene and vinyl acetate in different proportions Made of polymers

Special rubber - EVM (Yihuaping) performance characteristics and market applications

Comparison between EVM (Yihuaping) and EVA – Thermal properties

Special rubber - EVM (Yihuaping) performance characteristics and market applications

Vinyl acetate content VA

Note: VA content less than 40 is EVA, VA Content above 40 is EVM.

Levapren? is a registered trademark of Alangxeo

Performance characteristics of EVM (Evapren)

1. Excellent heat aging resistance, can be used at 150 ℃ For long-term use, the maximum working temperature can reach 175 ℃. After aging at 175 ℃ for 70 h or even 168 h, the retention rate of strong tensile properties is quite high. 2. The heat aging resistance of EVM is better than hydrogenated nitrile rubber (HN2BR) and EPDM.

3. Excellent flame retardant performance, the oxygen index of halogen-free flame retardant EVM rubber can reach 38 to 42, and the combustion smoke is low, slightly corrosive, and the combustion gas is non-toxic.

4. The oil resistance is good, and the oil resistance is equivalent to NBR with an acrylonitrile mass fraction of 0. 26 ~ 0. 34.

5. Weather aging resistance is second only to EPDM.

The disadvantages of EVM are poor water resistance, low viscosity, easy to stick to rollers during processing, and can only be vulcanized with peroxide.

The flame retardant properties of EVM (Yihuaping) – synergistic effect with Al(OH)3

Special rubber – EVM (Yihuaping) performance characteristics and market applications

VA content

The flame retardant properties of EVM (Yihuaping) – low smoke, halogen-free, non-corrosive

Special rubber – EVM (Yihuaping) Flat) performance characteristics and market applications

The liquid resistance of EVM (Yihuaping) improves with the increase in VA content

Special rubber - EVM (Yihuaping) performance Features and market applications

VA content

1. VA helps reduce volume expansion in oil

2. Good resistance to No. 901 oil

3. Resistance to engine oil requires a VA content of more than 60

4. The volume expansion in gasoline is large

5. In ethanol, the volume expansion of high VA grades is greater

The oil resistance of EVM (Yihuaping) increases with the increase of VA content

Special rubber - EVM (Yihuaping) performance characteristics and market applications

VA content

As the VA content increases, the oil swelling gradually decreases

The aging resistance of EVM (Yihuaping)

Special rubber - EVM (Yihuaping) Ping) performance characteristics and market applications

Heat resistance 170-175℃, can withstand higher temperatures in the short term

Key points of formula design of EVM (Yihua Ping)

(1) Use peroxide vulcanization system, the dosage of vulcanizing agent DCP is 2 to 3 parts, and the dosage of assistant cross-linking agent (TAC or TAIC) is 1 to 3 parts. When the dosage of vulcanizing agent DCP and co-crosslinking agent TAIC is about 2 parts, EVM has high tensile strength, small compression permanent deformation and good overall performance.

(2) EVM has poor hydrolysis resistance and requires the addition of an anti-hydrolysis agent. An effective anti-hydrolysis agent is polycarbonate diimide, such as Rhengran P-50 of German Rheinland Chemical Company or domestic PCD. The usual dosage of anti-hydrolysis agent Rhengran P-50 is 3 parts. After EVM without anti-hydrolysis agent was immersed in hot water at 80°C for 8 hours, the 100% tensile stress decreased rapidly to only 25% of that before immersion, and the elongation at break increased rapidly, to 1.48 times that before immersion; After adding 3 parts of anti-hydrolysis agent Rhengran P-50, the tensile properties of EVM changed slightly.

(3) EVM vulcanized rubber using antioxidant RD has the best heat aging resistance. If antioxidant RD is used together with anti-hydrolysis agent RhengranP-50, EVM vulcanized rubber has both good resistance to hydrolysis and resistance to hydrolysis. Thermal aging properties.

(4) The plasticizer should be DOS (dioctyl sebacate), which can be used in both high and low temperatures. It is better to use it together with the plasticizer TOTM (trioctyl trimellitate). Polyester plasticizer can give EVM excellent heat resistance.

(5) EVM has a low viscosity and is easy to stick to the roller during mixing. Stearic acid or stearic acid/calcium stearate (or zinc stearate) should be added, and an appropriate amount should be added. of polyethylene wax.

Reference formula

Special rubber - EVM (Yihuaping) performance characteristics and market applications

Uses of EVM (Yihuaping)

1. Cable sheath: halogen-free flame retardant

2. Combined use of EPDM/EVM – improves the hot air aging resistance of EPDM and the oil resistance of the radiator hose

3 .POE/EVM is used for foam shoe materials – the hardness is reduced, the resilience is improved, and it has better anti-slip properties

4.SEBS/EVM is used for special foam products – it has extremely high damping properties

5.NBR/EVM – Improve aging resistance

6.EVM is used as pre-dispersed masterbatch carrier