Thermographic material giving good dot reproducibility etc. - has binder sub-coat contg. capsules enclosing air and thermographic coat

摘要

Thermographic material consists of (a) a substrate; either (b) a subcoat contg. capsules (I) enclosing air and a binder; or (b-1) a subcoat contg. (I) and an adhesive, covered by (b-2) an intermediate coat contg. mainly a pigment (II) and a binder; and then (c) a thermographic coat. (I) have an outside dia. of 2-20 microns. Subcoat (b) may also contain (II), which has an oil absorption of 80 ml/100g or more. USE/ADVANTAGE - Good response to heat dot reproducibility and high density, stable prints. It causes little soiling of the thermal head. Useful with thermal heads, thermal styli, laser printers etc. used for meter registers, etc. In an example (I) with an average outside dia. of 1 micron were prepd. by mixing 100 pts. 10% aq. soln. of an ethylene/maleic anhydride copolymer, 10 pts. urea, 1 pt. resorcinol and 200 pts. water, adjusting to pH 3.5 with NaOH soln., injecting air to form air bubbles with a dia. of 1 micron, then adding 2.5 pts. 37% aq.HCHO soln. and stirring 4 hrs at 55 deg.c/. paper was given a 2.0 g/m2 subcoat with a dispersion of 100 pts. (solids) of (A) (I) with a dia. of 1 micron, (B) (I) with a dia. of 25 microns, (C) styrene/acrylic hollow particle emulsion or (D) thermally expandable fine hollow particles, 24 pts. styrene/butadiene copolymer latex (50% dispersion), 60 pts. starch phosphate (10% aq. soln.) and 52 pts. water. Sample (D) was foamed by heating 1 min at 110 deg.C after drying. Samples (C,D) were controls.