Development of the hottest chloroprene Graft Adhes

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In recent years, cold adhesive bonding method is widely used in the interface and repair of nylon belt, canvas belt and flame retardant belt. PVC all plastic or rubber plastic flame-retardant whole core conveyor belts are widely used in underground transportation of coal mines. At present, there is no suitable PVC cold adhesive, and the cold adhesive method is rarely used for repair. The polychloroprene grafted adhesive with polymethylmethacrylate (PMMA) and antioxidant has low activation temperature, long viscosity retention time and wide adaptability. The surface free energy of the PMMA side chain of the graft adhesive is similar to that of polyvinyl chloride (PVC), which improves the compatibility between the adhesive and PVC and improves the bonding strength. In this paper, the reaction mechanism, preparation process and properties were studied

2 reaction mechanism

the graft copolymerization system of rubber (R) and monomer (m) was carried out according to the investment strategy of free radical chain reaction in 2014. The initiator (b) decomposes to produce active free radicals (I.): B → 2i 1. Initiate monomer to form monomer free radical (M.): i.+m → m.+im Continue to attack other monomers to form monomer growth chain radical (P.): m.+m → p.i. attack rubber to form rubber main chain radical (R.): i.+r → r.+ip Transfer to rubber to form (R.): p.+r → r.+p monomer grows on R to form grafted rubber (R-P): m+r. → r-pr P. Self polymerization or copolymerization produces chain termination reaction r.+p. → R-P r.+r. → r-rp.+p. → P-P

3 experiment

3.1 raw material

chloroprene rubber (CR) A-90 methyl methacrylate (MMA) industrial solvent industrial initiator BPO chemical pure polymerization inhibitor HQ chemical pure antioxidant 264 industrial grade tackifier industrial grade

3.2 process

after plastic refining, immerse neoprene in solvent to dissolve, and put it into the belt after it is completely dissolved.In the three neck bottle of the mixer device, Control the temperature of 85 ~ 95 ℃, add a certain amount of initiator BPO, continue to stir for 15 ~ 20min, drop the MMA dissolved with residual BPO, add it within 1h, carry out graft copolymerization at 90 ± 5 ℃, after reaction for 1.5 ~ 2H, add polymerization inhibitor HQ, antioxidant 264, finally add tackifier, stir and discharge evenly

4 product performance index

appearance: brownish yellow translucent viscous liquid viscosity: 1000 ~ 1500cp solid content: 18% ~ 20% peel strength (PVC-PVC): ≥ 8.0 (kg/2.5cm) storage period: more than half a year

5 results and discussion

5.1 influence of monomer concentration

in the grafting reaction system, the concentration ratio of Cr to MMA has a decisive impact on the branch reaction and the performance of the glue solution with the maturity of the technology. The experiment shows that the best cr/mma is 100/60

5.2 influence of initiator concentration

the determination of initiator dosage is the main factor to control the polymerization rate. When other conditions are certain, the polymerization rate is proportional to the square root of initiator concentration, and the initiator concentration increases, the reaction speed increases, and the viscosity of the glue increases. However, when the amount of initiator is higher than 2.4%, the molecular weight of the polymer decreases and the viscosity of the system decreases with the increase of the amount of initiator

5.3 temperature effect

the reaction temperature has a great influence on the grafting reaction. When the reaction temperature is lower than 85 ℃, the initiation rate and polymerization rate are very low. When the reaction temperature is higher than 95 ℃, the initiator initiation is too fast, which may cause explosion polymerization or premature decomposition of the initiator, and stop polymerization at the low conversion stage

5.4 effect on the adhesion of PVC leather materials

from the grafting reaction mechanism, it can be seen that the grafting polymerization reaction is complex, and the adhesion of the glue solution is not only related to the polymerization rate of the monomer, but also related to the grafting efficiency of the monomer. The results showed that when the polymerization rate of the glue solution was about 40% and the grafting efficiency was more than 50%, the adhesive force of the glue solution to PVC leather materials was better

5.5 ways to improve the grafting rate of polymerization

based on the reaction mechanism, Cr is plasticized on unequal speed rubber rolls before feeding to form a certain number of chain free radicals cr., which is undoubtedly very necessary to improve the grafting rate. The best feeding time of monomer MMA is about 15 ~ 20min after the initiator is added, and the continuous dropping method should be adopted, which can effectively reduce the formation of homopolymer PMMA and improve the grafting rate

6 conclusion

cr MMA graft adhesive has the advantages of simple process, strong adhesion and wide applicability, especially solving the PVC bonding problem of few domestic enterprises researching and developing vacuum insulation panels. It can be used as the protective rubber layer on the belt surface of the worn PVC whole core conveyor belt, so that the PVC all plastic or rubber plastic whole core conveyor belt exposed due to the wear of the rubber layer can continue to be used, so as to achieve the purpose of saving money

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