Study On Impregnation Treatment Of Fiber Based On Acrylic Resin System And Its Interfacial Adhesion Mechanism With Rubber

Fiber cord reinforced rubber composites occupy an important position in engineering fields such as metallurgical coal mines and transportation,but the surface of synthetic fibers is smooth and chemically inert,resulting in extremely weak adhesion between cords and rubber.Resorcinol-formaldehyde-latex(RFL)is mostly used in the fiber/rubber bonding system.However,resorcinol and formaldehyde(RF)in the system have serious harm to human body and environment.With the rapid advancement of the green process of raw materials,the environmentally friendly impregnation system came into being.Environmentally friendly water-based hydroxy acrylic resin(AC)contains a large number of polar groups,which can replace RF resin rich in phenolic hydroxyl and methylol groups,and by introducing amino resin(MA)containing a triazine ring structure,a rigid network can be formed like structure.Therefore,this thesis takes the hydroxy acrylic resin/amino resin system as the main research object,aiming at nylon 66 fiber(PA66,1400 dtex/2)and aramid fiber(AF,1670 dtex/2)with different surface properties,by adjusting the composition of the impregnation system,constructing different surface treatment structures,revealing the relationship between surface structure and adhesion properties,clarifying the adhesion mechanism,designing and preparing the environmentally friendly impregnation system that can effectively replace RFL.The main thesis contents include:(1)Based on the one-bath pretreatment of traditional epoxy resin/ blocked isocyanate,a two-bath environmentally friendly impregnation system of hydroxy acrylic resin/amino resin/ vinyl-pyridine latex was designed and prepared,the curing reaction mechanism of the impregnated components and the influence of the impregnation system composition on the surface treatment structure(chemical composition,surface morphology,and dip solids pickup on fiber)were analyzed,the relationship between the surface structure and the adhesion properties were clarified.The results showed that the impregnation components reacted and coated on the fiber surface;for PA66 fiber,with the increased of MA content,the dip solids pickup on fiber increased,and the adhesive properties first increased and then decreased.The damaged area was transferred from the interface to the rubber matrix;with the increased of the catalyst dosage,the uniformity and flatness of the adhesive film on the surface of the modified fiber increased,at the same time,the adhesion properties first increased and then decreased;When the AC/MA ratio was 4:0.5,and the catalyst dosage was 6% of the solid content of MA,the H pull-out force,peel force and adhesive amount after peeling of the modified PA66/rubber composites reached103.9%,100.9% and 100.7% of the RFL treatment level,respectively.For AF fiber,the influence of the impregnation system composition on the fiber surface treatment structure was the same as that of the modified PA66 fiber.When the AC/MA ratio was 4:0.8,and the catalyst dosage was 6% of the solid content of MA,the H pull-out force,peeling force and adhesive amount after peeling of modified AF/rubber composites reached 103.0%,97.8% and 99.2% of the RFL treatment level,respectively.The interfacial adhesion mechanism is that polar groups such as hydroxyl groups on the AC/MA cross-linked network can form chemical bonds with polar and functional groups on the surface of unmodified fiber or activated fiber;latex dispersed in the resin network can react with rubber to form cross-linking bonds.The test found that the treatment process and the dipping coating did not have a significant impact on the fiber strength,and the two-bath dipping solution had good stability,which has potential industrial application prospects.(2)RFL one-bath dipping is usually used to treat PA66 fiber in industry.Therefore,a new one-bath environmentally friendly dipping system was prepared by adding blocked isocyanate(CBI)on the basis of the two-bath dipping system.The curing reaction mechanism of the impregnated components was explored,the effects of CBI and AC hydroxyl content on the surface treatment structure and adhesion properties of PA66 fiber were also studied.The thesis showd that the impregnating components were coated on the fiber surface and reacted to form a resin network toughened by latex.With the increased of CBI and AC hydroxyl content,the flatness and uniformity of the adhesive film on the modified fiber surface and the dip solids pickup on fiber increased,at the same time,the adhesive properties showed a trend of first increasing and then decreasing.When the AC hydroxyl content was 3.6% and the CBI solid content was 3 wt%,the H pull-out force,peeling force and adhesive amount after peeling of the modified fiber/rubber composites reached 91.6%,80.8% and 92.6%of the RFL treatment level,respectively.The reason for the large gap between the one-bath treatment method and the two-bath method is that in the two-bath method,the fiber was first pretreated with CBI,which can better activate the fiber surface.In addition,the strength loss of the modified fiber was small,and the one-bath environmentally friendly impregnation solution showd good stability.