Study On Preparation Of Polyurethane-Acrylic Adhesive For Polyolefin Laminated Films

With the features of abroad source,the polyacrylic adhesive show betterwetting property, excellent initial tack and widely adhesivity.However,theacrylic adhesive has low peeling strength because of its low cohesive energywhile bonding polyole substrate.Compared to the acrylic,the polyurethane hashigh cohesive energry,because the polyurethane molecular chain contains alarge number of urethane bond and urea bond whose bond energy are huge.Butit is too difficult to attach to the surface of the material for these urethanebond have large polarity,and most of the polyolefin films are non-polar,whichresult in low peeling strength. The water-based polyurethane has low solidcontent, low productivity, high energy consumption, which can prevent thedevelopment and application of water-based polyurethane in the field ofplastic plastic adhesive. Accordingly, we can combine advantage of bothpolyurethane and acrylic from each other, using the science compoundingprocess, and then get the performance of waterborne polyurethane-acryliclaminating adhesive.In this dissertation, side vinyl polyurethane emulsion was synthesizedusing diisocyanate,oligomer polyol,bis (hydroxymethyl) propionicacid(DMPA) as main raw material, methyl hydroxypropyl acrylate (HPMA) assealing side agent,triethyl-amine(TEA) as neutralizer,trimethylolpropane(TMP), adipic acid dihydrazide (ADH), diethylenetriamine(DETA) as small molecule chain extender.The polyacrylate emulsion wassynthesized based on the pre-emulsion seeded emulsion polymerizationprocess.After that,the polyurethane-acrylic emulsion was prepared using ofdual-dropwise added process,and using the acrylic emulsion as seed, sidevinyl waterborne polyurethane was leaded into the polymer and aggregated.Finally, excellen performance of water-based laminating adhesive product wasprepared by adding various additives such as increased viscosity, wettingagents, fillers to the PUA. The polyacrylate parts such as the type and dosage of the emulsifier, theselection and proportion of the flexible monomer and hard monomer, theselection and ratio of functional monomer;the polyurethane parts such as themodification process, dosage of polyurethane, amount of HEMA,and DMPA,R value size, and small molecules amine chain extender, and the influence ofvarious additives on the performance of polymer emulsion were studied, anddescribed the process and formulation of the laminating adhesive forpolyolefin film composite with the PUA were described too.The experment showed:(1)Emulsion prepared by reactive emulsifier SR-10, had low viscosity, good water resistance, high peeling strength, and whenthe amount of2%, the peeling strength was largest;(2) As Soft monomer BAand hard monomers MMA ratio of3:1, the system had the biggest peelingstrength;(3)Adding an appropriate amount of functional monomers such asmethacrylic acid (MAA), hydroxyethyl acrylate (HEA), diacetone acrylamide(DAAM), could greatly improve the peeling strength of the system;(4)PUAwhich was prepared by the way of seeded emulsion polymerization processhas high peeling strength, water resistance, good storage stability, and whenPU/PA=1:4, The polymer had the largest peeling strength;(5)When R=1.3,amount of DMPA4.5%, amount of HEMA4%, ADH/DETA=1:4, and theprocess of first joined the ADH, then added DETA, the PUA emulsion had thebest peeling strength;(6)The wetting agent could reduce the contact angle, andimporve the peeling strength.When the amount of0.7%-0.8%of the total oflotion, the peeling strength was largest.(7)By adding a tackifying resin, couldimprove the initial viscosity of the emulsion, reduce the contact angle, andwhen the amount of15%of the total emulsion, the peeling strength of syetemwas largest.(8)Adding5%nano-silica could be used to maintain sufficientpeeling strength, and reduce the cost of the product.The synthesis of polyurethane and acrylates copolymer were confirmed usingfourier spectrometer analysis;By using thermal gravimetric and particle size testproved that the synthesis of the PUA has smaller particle size, narrow particle sizedistribution, good thermal stability.