Adhesive film, partic. label for bottles - comprises release layer, adhesive layer contg. acrylate] or methacrylate] copolymer and amino-silane, and surface layer

摘要

Film (I) comprises (A) release layer, (B) adhesive layer on (A), comprising (B1) amino-contg. silane as coupling agent, (B2) (meth)acrylate copolymer as adhesive, prepd. from mixt. contg. (B2.1) 1-20 % (all pts.wt.) ethylenically unsatd. carboxylic acid deriv. (B2.2) 50-90% 4-18 C alkyl (meth)acrylate, (B2.3) 10-50 % other monomer copolymerisable with (B2.1) and (B2.2), (C) surface layer on (B). USE/ADVANTAGE - Partic. adhesive labels. Labels adhere well to glass and withstand contact with water, but are readily removed from bottle, etc. when required by 3-10 % aq. soln. of alkali, e.g., NaOH. In an example, aq. emulsified monomer mixt. of concn. 50 % was prepd., comprising 80 % 2-ethylhexyl acrylate, 5 % acrylic acid, 5 % vinyl acetate, and 10 % Me methacrylate; emulsion also contained (on total monomers) 1 % polyoxyethylene-nonylphenyl ether ammonium sulphate, 1 % polyoxyethylene-nonylphenyl ether, and 0.01 % n-dodecyl mercaptan. Aq. soln. contg. 0.5 % ammonium persulphate, on wt. monomers, was heated to 70 deg.C under N2, and one sixth of emulsified monomer mixt. was added. After 90 % had reacted, remaining emulsion was added dropwise over 3 hrs., then mixt. was kept for 2 hrs. at 80 deg.C. To 100 pts. (as solids) copolymer emulsion was added 1.5 pts. KMB 603 (TM: (II)), and mixt. was applied at 25 g/sq. m onto release layer formed by applying KS 770 (TTM: silicone release agent) at 0.5 g (dry wt.) /sq.m and drying. Commercially available coated paper (88 g/sq. m) as (C) was applied on the adhesive face to form a (I). (I) adhered well to glass and withstood immersion for 1 day in water but became completely detached within 5 minutes on immersion in 5 % aq. NaOH at 70 deg.C. If (II) were omitted, label became completely detached on immersion in water.