| 摘要 |
<p>A heat-sealable, sealing material for producing flexible containers or packaging using conventional paper making techniques, is produced by treating a cellulosic and/or synthetic support with (a) an aqs. suspension of a (co)polymer and (b) a lactic acid resisting agent (I) comprising an alkyl-betone dimer or a paraffin. The process avoids the drawbacks of prior art (e.g. use of hot paraffin baths, extrusion etc) and makes use solely of aqs. dispersion media and conventional papaer making machines e.g. horizontal, inclined or vertical table machine with size press, air or trailing blade or roll coater. Used for prodn. of containers for yogurts, ice creams, beverages and frozen foodstuffs. The support may be treated first with the (I), follower by the aqs. (co)polymer suspension opt contg. (I) Alternatively the support is treated with the aqs. (co)polymer suspension contg. (I). The suspension pref. also contains a waterproofing agent, inorganic fillers, binders and an hydrophobic lubricant, pref. a stearate. Following the treatment, the support is either polished, calendered or laminated and then heat-sealed either with itself or other material such as polystyrene, PVC or aluminium. A support comprising 100 pts. cellulose fibres contained 3 pts. of a paraffin emulsion which is pptd. on the fibres in acid medium. The support weighin 200-230 g/m2 was impregnated with a size press bath comprising 100 pts. dispersed acrylic ester copolymer, 20 pts. starch, 10 pts. emulsified paraffin and 10 pts. fillers. The uptake was 15 g/m2 (dry). One side of the support was then coated with a compsn. comprising 10-40 pts. acrylic copolymer, 60-100 pts. high mol. wt. emulsified paraffin, 1-3 pts. poyvinyl pyrrolidone. The uptake was 12-18 g/m2 (dry). The other side was coated with a compsn. comprising 100 pts. acrylic (co)polymer and 10-30 pts. fillers. The uptake was 5-10 g/m2. The support was then calendered to the desired thickness.</p> |
