| Polyurethane adhesives contain strong polarity, lively chemical and isocyanate groupsand ammonia ester groups which can react with lively hydrogen groups to form the finechemical bond firmly. Polyurethane adhesives have a good low temperature resistance,goodabrasion resistance, water resistance,solvent resistance,medicinal chemical resistance and hasbeen used widely.Two-component polyurethane was employed as the adhesive for polyvinyl chloride (PVC).Due to the strong polarity, the low surface energy of PVC,the adhesive was required to be ofadjusted performance, high adhesion strength and wide bond range.This article used4,4’-diphenylmethane diisocyanate (MDI), trimethylolpropane (TMP), polyether polyols asraw materials to synthesize the two part of two-component polyurethane: hydroxylcomponents (the main agent) and isocyanate components (curing agent). Through the test ofthe content of isocyanate groups,viscosity and FI-IR, effects of synthesis of two componentsreaction were studied below:the mole ratio of MDI/polyether polyols was2.5, the reactiontemperature was90℃and reaction time was3h,under that conditions good hue, properviscosity agents can be prepared;good performance, stability, good curing agent can besynthesized when pretreat raw material until its moisture content less than0.05%;polyols wasfed into MDI by many times; the mole ratio of the MDI/TMP was between3.1~3.3; elevatetemperature sectionally and heat insulating temperature was controlled at (80±5)℃, and thewhole reaction time was in two hours or so;add dibutyltion dilaurate (DBTDL) in the latepart of reaction process and the dosage was0.05‰~0.3‰;use phosphoric acid as resistanceagent and control the amount between1‰~5‰.Effects of the adhesive made from the main agent and curing agent used for PVC werestudied,through the characterization of DSC and FT-IR,it shows that the adhesive can cure in 24h in room temperature and have a good adhesive properties for PVC. |
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