| 摘要 |
A process for solvent casting acrylic films having superior properties by casting a solution comprising an organic solvent and a polymer system of one or more acrylic polymers onto a carrier, removing the solvent thereby forming the film on the carrier, and stripping the film from the carrier, is disclosed. The polymer system comprises at least one polymer having the following properties: Total Elongation (%) of about 120-250; Tear Resistance of about 4.5-12.5 g/mil (which is about 177-492 mg/micron); Tensile Strength of about 4500-5000 lbs/in2 (about 317-387 kg/cm2); Molecular Weight (amu) of about 250,000-500,000; Acid Content (%) of about 0.05-5.0; and Tucon hardness (Knoop No.) of about 6-12. The acrylic film has Total Elongation, Tensile Strength, Tear Resistance, Acid Content and Tucon hardness in the aforesaid ranges, and is substantially free of reactive groups, such as hydroxy groups. The residual solvent in the film is (weight %) about 0-3. The film has dimensional stability (% shrinkage at about 130 DEG C. for films of 0.5-5.0 mils, which is about 13-127 microns) of about 0.3. The thickness of the films is generally about 0.5-5.0 mils (which is about 13-127 microns). The films have excellent flexibility and extensibility, are completely free of pinholes, gels and imperfections, and have excellent weatherability.
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