US PATENT SUBCLASS 428 / 437
.~.~.~ Next to acetal of polymerized unsaturated alcohol (e.g., formal butyral, etc.)

Current as of: June, 1999
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428 /   HD   STOCK MATERIAL OR MISCELLANEOUS ARTICLES

411.1  DF  COMPOSITE (NONSTRUCTURAL LAMINATE) {25}
426  DF  .~ Of quartz or glass {9}
436  DF  .~.~ Next to aldehyde or ketone condensation product {1}
437.~.~.~ Next to acetal of polymerized unsaturated alcohol (e.g., formal butyral, etc.)

DEFINITION

Classification: 428/437

(under subclass 436) Product in which a layer contiguous with the quartz or glass contains the di-ether reaction product of an aldehyde with the hydroxy groups of an (addition polymer from unsaturated monomers)*, e.g., acetal of polyvinyl alcohol.

(1) Note. The usual source of polyvinyl alcohol is a hydrolyzed polyvinyl ester. Such terms as the reaction of an aldehyde with polyvinyl acetate -- or the reaction of an aldehyde with hydrolyzed polyvinyl acetate -- will be sufficient to place a patent in this subclass.