(1) Performance and application Resin containing many repeating reactive groups on the main chain is called polyurethane, or polyurethane for short. The structures of polyurethane and polyamide are very similar, except that the active group of the former has one more oxygen atom than the active group of the latter, so the properties of the two have many similarities.
Polyurethane adhesive is composed of isocyanate and polyester or polyether. It is highly polar and reactive and has good effects on various metal and non-metal materials. With good adhesion, flexible or even hard adhesive layers can be obtained by adjusting the types and proportions of the components during use. It can be cured at high temperatures or at room temperature, and is widely used.
Polyurethane adhesive has properties such as water resistance, oil resistance, solvent resistance, ozone resistance, and bacteria resistance. It has excellent bonding strength especially at low temperatures, so it is Promising low temperature adhesive.
Polyurethane adhesives work well on metal, wood, rubber, fabrics, and most plastics (especially polyvinyl chloride, which contains large amounts of plasticizers) Affinity. It is widely used in lamination of adhesive fabrics for light packaging materials, manufacturing of composite materials, electrostatic flocking, manufacturing of non-woven fabrics, shoemaking, rubber products and sealant manufacturing, etc. It is expected that there will be greater development in the future.
(2) Caprolactone polyol polyurethane adhesive This type of adhesive is obtained by the reaction of caprolactone and glycol. It is similar to ordinary polyester. It has the following advantages: ① good color; ② homogeneous structure, uniform molecular weight distribution, ③ only active hydroxyl groups at the end groups, clear number of functional groups; ④ resistance to hydrolysis, good low-temperature softness; ⑤ due to low viscosity, almost 100% It is cured and can be used with a wide range of solvents. ⑥ Compared with polyethers, its outdoor durability is particularly excellent.
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