A large number of adhesives are used in paint printing, the most widely used are polyacrylate copolymers, which are composed of soft monomers polybutyl acrylate and hard monomers such as acrylonitrile, styrene, acrylamide, methyl methacrylate. , Acrylic acid and self-crosslinking agent methylol acrylamide emulsion polymerization emulsion. It has good transparency, strong adhesion, medium touch, and good soaping fastness, but it has a high amount of formaldehyde released, soft enough to handle, easy to absorb dyes in the lotion and dust in the air, poor elasticity, knit fabric printing 5. The fabric has problems such as bare bottom and wet rubbing fastness when stretched.
Waterborne polyurethanes are produced by the condensation of diisocyanate with a polyether, chain extension with chain extenders (such as dimethylolpropionic acid and butanediol), and neutralization with triethylamine to form an aqueous dispersion. The diisocyanate segment is a hard segment, and the polyether is a soft segment. Their relative proportions and the length of the molecular chain determine the elasticity and flexibility of the polyurethane produced. Waterborne polyurethane has the advantages of high elasticity, good heat and cold resistance, good chemical resistance, good resistance to kogation, and exceptional softness. When used in paint printing to obtain better wet fastness, the film is smooth and not sticky, therefore, dust absorption is small. The F-knitted fabric will not be exposed by stretching, but the price is about 5 times higher than that of polyacrylate, and the transparency is not as good as polyacrylate.
In order to exert the effects of the two types of adhesives, compounding is performed at a mass ratio of m (polyacrylic ester):m (aqueous polyurethane) of 70:30. The softness, wear resistance, heat resistance, cold resistance, and resistance Chemical crystals and wet rubfastness have been improved to varying degrees, and the degree of improvement is slightly greater than the sum of the two. If the acrylate is added during the preparation of the hydrophobic polyurethane to prepare the IPN of the polyurethane/polyacrylate, the above physical and chemical properties are greatly improved, and a film with soft touch, abrasion resistance, good stretch strength and high elasticity can be obtained. After printing, the wet rub fastness can be improved to grade 3 or more, the dust-collecting property is greatly reduced, and the printed fabric of the knitted fabric will not be stretched due to stretching, thereby overcoming the defects in the use of the polyacrylate adhesive. Of course, it is also necessary to select the components of waterborne polyurethane and polyacrylate, the conditions of the preparation process, etc. to obtain the best performance of IPN paint printing adhesive.
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