Solvent cast acrylic film.

摘要

Acrylic films having superior properties are produced by casting a solution comprising an organic solvent and a polymer system of one or more completely polymerized acryllc polymers onto a carrier, removing the solvent thereby forming the film on the carrier, and stripping the film from the carrier.

The polymer system comprises at least one polymer prepared by polymerizing monomers of the general formula (i):
<Chemistry id="chema01" num="0001"><Image id="ia01" he="15" wi="42" file="IMGA0001.TIF" imgContent="chem" imgFormat="TIFF" inline="no" /></Chemistry>wherein: R, is hydrogen or methyl; and R<Sub>2</Sub> is striaght or branched alkyl of about 1-20 carbon atoms, preferably about 1-8 carbon atoms, more preferably 1-4 carbon atoms, and most preferably 1-2 carbon atoms.

The polymers are homopolymers, mixed copolymers, and graft copolymers. They may be cross-linked.

The polymers have the following properties:
<UnorderedLists id="ula01" listStyle="none"><ListItem>Total Elongation (%) of about 120-250, preferably about 150-210, and more preferably about 170-190;</ListItem><ListItem>Tear Resistance of about 4.5-12.5 g/mil (which is about 177-492 mg/micron), preferably 6-10 g/mil (which is about 236-394 mg/micron), and more preferably about 8-9 g/mil (which is about 315-354 mg/micron);</ListItem></UnorderedLists>

Tensile Strength of about 4500-5000 Ibs/in<Sup>2</Sup> (about 317-387 kg/cm<Sup>2</Sup>), preferably about 4800-5200 Ibsi/n<Sup>2</Sup> (about 338-366 kg/cm<Sup>2</Sup>), and more preferably about 4900-5100 Ibs/in<Sup>2</Sup> (about 345-359 kg/cm<Sup>2</Sup>).

Molecular Weight (amu) of about 250,000-500,000, preferably about 300,000-400,000, and more preferably about 325,000-375,000;

Acid Content (%) of about 0.0-5.0, preferably about 0.0-2.0, and more preferably about 0.0-0.9;

Tucon hardness (Knoop No.) of about 6-12, preferably of about 7-11, and more preferably of about 8-10; and

The polymer is substantially free of reactive groups, such as hydroxy groups.

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, preferably about 0-2, and more preferably about 0.1-1.0. The film has dimensional stability (% shrinkage at about 130°C. for films of 0.5-5.0 mils, which is about 13-127 microns) of about 0-3, preferably of about 0-2, and more preferably of about 0.1-1.0. The thickness of the films is generally about 0.5-5.0 mils (which is about 13-127 microns), preferably about 0.75-3.0 mils (about 19-76 microns), and more preferably about 1.0-2.5 mils (which is about 25-63 microns). The films have excellent flexibility and extensibility. They are completely free of pinholes, gels and imperfections. The films have excellent weatherability.