| Now, in all kinds of wood adhesive, the urea-formaldehyde resin isstill a widely used adhesive due to the simple production technologyand low price. With the increasing awareness of environmentalprotection, the development of science and technology and thecontinuous appearance of new material, the use of theurea-formaldehyde adhesive will be subject to restricted. So thedevelopment of environment friendly adhesive has become theimportant development direction.The purpose of this task is to get a kind of environment friendlyadhesive. It can not only eliminate the problem of releasingformaldehyde, but also could solve the shortcoming of high cost andcomplex process of the environment friendly adhesive. Becauseisocyanate has high reactivity and curing speed, it has become a kind ofimportant raw materials in the preparation of the environment friendlyadhesive. At present isocyanate adhesive did not retain good reactivityof isocyanate, result in the strength is not good. In this paper, withisocyanate polymers as cross-linking agent, a series of wood adhesivewithout formaldehyde will be synthesized by isocyanate polymers andmany kinds of vinyl polymer. And the author study detailedly thestructure and properties of composite systems to explore the mechanismof their synergy. The main content of this paper is as followings:1. With polyvinyl alcohol (PVA) as polymeric colloid stabilizer, akind of surfactant-free copolystyrene-acrylat latex with good stable andexcellent property is successfully synthesized by reacting styrene (St),butyl acrylate (BA), N-hydroxymethyl Acrylamide (NMA) and acrylicacid (AA). The copolystyrene-acrylat latex as the main agent, silicasoland isocyanate polymers (HDI) as cross-linking agent, a kind of woodadhesive without formaldehyde is synthesized by copolystyrene-acrylatlatex, silicasol and isocyanate polymers. At the same time, the factors affecting its synthetic condition are discussed, and the synthetic processis optimized. The results show that adhesive owns excellent propertywhenω(PVA)=8%,ω(AA)=6%,ω(NMA)=4%,n(BA)/n(St)=2:1,ω(Sil)=6%,ω(HDI)=8%. The particle size of acrylic resin emulsion is168.5nm, the tensile strength, elongation at break and water absorptionof acrylic resin films respectively is 7.5Mpa, 862.19% and 16%.FTIR analysis indicates that–NCO has reacted because theabsorption peaks does not appear in the wavelength 2270 cm-1.TG analysis indicates that the polymer has two decompositionstages. The rheological measurement indicated that the viscositydecreased with increasing shear rate, all emulsions exhibitedshear-thinning behavior, and the phenomena became more pronouncedwith increasing silica sol and HDI concentration.DMA showed that the storage modulus of adhesive films isincreased with silica sol and HDI addition. However, when silica solconcentration was greater than 6 wt. %, HDI concentration was greaterthan 8 wt. %, the storage modulus decreased. It means that the rigidityof adhesive films could be improved with silica sol and HDI addition.When the resin content is 250g/m2on the application experiment,the plank bonding strength reaches 0.82Mpa, the static strength reaches20.5 Mpa and the water resistence reaches 12h. The outcome conformthe national standards.2. With dimethylformamide (DMF) as cosolvent, a kind of acrylicresin latex is successfully synthesized by reacting methyl methacrylate(MMA), butyl acrylate (BA) and dimethylaminoethylmethacrylate(DMC). The aqueous isocyanate crosslinking agent is got by acrylicresin latex and isocyanate polymers (HDI). Then the wood adhesive wasprepared via compounding carboxyl butyl benzene and the aqueousisocyanate crosslinking agent. At the same time, the factors affecting itssynthetic condition are discussed, and the synthetic process is optimized.The results show that the acrylic resin latex owns excellent propertywhenω(DMC)=30%,n(BA)/n(MMA)=1:1,ω(dodecylmercaptan)=0.4%. The tensile strength and water absorption of acrylic resin films respectively is 6.5Mpa and 16%.When m(acrylic resin)/m(HDI)=2/1, the aqueous isocyanatecrosslinking agent owns excellent property. The tensile strength andwater absorption of isocyanate crosslinking agent films respectively is7.2Mpa and 14.5%. FTIR analysis indicates that–NCO has not reacted.The crosslinking agent retains better reaction activity.TG analysis indicates that the thermal stability of adhesive isincreased with isocyanate crosslinking agent addition. The rheologicalmeasurement indicated that the viscosity decreased with increasingshear rate, all emulsions exhibited shear-thinning behavior, and thephenomena became more pronounced with increasing isocyanatecrosslinking agent concentration.DMA shows that the storage modulus of adhesive films isincreased with isocyanate crosslinking agent concentration increasedfrom 0% to 10%. However, when isocyanate crosslinking agentconcentration is 15%, the storage modulus decreased.The test of contact angle of adhesive films shows that the contactangle of carboxylbutyl benzene reach 68.5°without isocyanatecrosslinking agent addition, the contact angle of adhesive films reach88°when isocyanate crosslinking agent concentration is 10%. It meansthat the water resistance of adhesive films is improved with isocyanatecrosslinking agent addition.The experiment which adhesive is used in blockboard shows thatwhen m(isocyanate crosslinking agent)/m(carboxylbutyl benzene)=10% ,the resin content is 300g/m2and the temperature is 120℃, the plankbonding strength reaches 0.80Mpa, the static strength reaches 21.4 Mpaand the water resistence reaches 10h. The outcome conform the nationalstandards.3. The wood adhesive is prepared via compounding EVA, polyvinylalcohol (PVA) and isocyanate polymers (HDI). The factors affecting itssynthetic condition are discussed, and the synthetic process is optimized.The results show that the tensile strength, elongation at break and waterabsorption of adhesive films respectively is 7.8Mpa, 763.2% and 23%, when m(PVA)/ m(EVA)=1/3 andω(HDI)=10%.TEM photos show that the adhesive emulsion particles are regularsphericity, and the surface of the particles is clean.TG analysis indicates that the thermal stability of adhesive isincreased with HDI addition due to the cross-linking reaction betweenHDI and PVA.DMA shows that the rigidity of adhesive films is increased withm(PVA)/ m(EVA) increased. However, when m(PVA)/ m(EVA) isgreater than 1/3, the rigidity of films decreased. The rigidity ofadhesive films is increased with HDI concentration increased from 0%...
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