The characteristics of membrane adhesive is a key factor affecting the quality of membrane products
Membrane adhesive types have a lot of, if from the molecular structure of the complex adhesive, can be divided into one-component and two-component adhesive. One-component adhesive is a single component, need not mixed with other components can play with cooperation with film adhesive, and a two-component film adhesive is made from the main agent and curing agent after two components mixture can embody the adhesive glue. At present many for polyurethane type. Polyurethane refers to the polymer molecular structure containing hydroxy group, is composed of multiple hydroxyl compounds and isocyanate reactions. Combined with isocyanate active hydrogen, has high adhesive strength. At present our country most component A as polyol, B component for isocyanate.
Other active hydrogen effect on adhesive with isocyanate NCO group is the accumulation of impurity atoms to form double bond, and - easily 噢,- COOH，- React NH2 active hydrogen atoms such as groups, such as isocyanate react with water to generate amine and gives off carbon dioxide; React with hydroxyl compounds to generate carbamic acid ester; And - NH2 groups urea reaction formation; So must pay attention to the storage and use of adhesive and curing agent, avoid curing agent contact with active hydrogen.
Polyurethane adhesive on the quality of the compound on the domestic market at present a two-component glue factory is various, quality is different, so the complex membrane manufacturers need to master certain criteria, so that to control their own purchase, use and management. Glue quality evaluation is mainly from the appearance of the adhesive, bonding strength, residual solvents and residual monomer etc for testing and evaluation. 一个。 Appearance: to observe whether clear transparent, color is colorless to pale yellow; b。 Bake: make use of the drying oven baked 2 - the glue 3 hours, 70 - 75°） Measurement of solid content; c。 Tit: solvent soak composite membrane solvent resistance test; d。 Tear; With the hand tear composite film as the bonding strength of the inspection; e. If there is a peculiar smell, smell: the smell of glue to detect whether there is residual monomer, in general, ethyl adhesive solution should only taste; f。 Measure: use a variety of instruments and chemical methods to check glue and composite membrane, get the corresponding indicators.