Gum adhesive based on a filled polymer dispersion
View Patent ↗A filled gum adhesive useful for producing remoistenable layers contains fillers, protective colloids, and a (co)polymer, wherein the (co)polymer is prepared by polymerizing one or more ethylenically unsaturated monomers in the presence of a dispersion of protective colloid and filler particles.
1. A gum adhesive comprising an aqueous filled polymer dispersion that comprises water, at least one inorganic filler, and at least one polymer comprising a homopolymer or copolymer of vinyl acetate, wherein the polymer was polymerized in the presence of at least one protective colloid selected from the group consisting of starch ethers, cellulose ethers and derivatives thereof and the filler, and wherein the dispersion has a viscosity below 15,000 mPas at a temperature of 25° C.
2. A gum adhesive according to claim 1 , wherein the polymer dispersion is free of polyvinyl alcohol.
3. A gum adhesive according to claim 1 , wherein the protective colloid is a non-ionic starch derivative.
4. A gum adhesive according to claim 1 , wherein the protective colloid is non-ionic.
5. A gum adhesive according to claim 1 , wherein the protective colloid is selected from the group consisting of hydroxyalkyl ether starches.
6. A gum adhesive according to claim 1 , wherein the protective colloid is selected from the group consisting of hydroxyalkyl starches and hydroxyalkyl dextrins.
7. A gum adhesive according to claim 1 , wherein one or more non-ionic starch ethers are used as the sole protective colloid in an amount of from 7 to 30 weight percent based on the polymer dispersion.
8. A gum adhesive according to claim 1 , wherein said at least one inorganic filler is selected from the group consisting of chalk, gypsum, quartz powder, silica gel, silica, titanium dioxide, talc and layered silicates.
9. A gum adhesive according to claim 1 , wherein the polymer is water-insoluble.
10. A gum adhesive according to claim 1 , wherein the at least one inorganic filler is selected from the group consisting of fillers in the form of platelets with a particle size between 0.1 and 5 μm.
11. A gum adhesive according to claim 1 , comprising inorganic filler(s) in an amount of 1 wt. % to 40 wt. % and protective colloid(s) in an amount of 3 wt. % to 30 wt. %.
12. A gum adhesive according to claim 1 , additionally comprising one or more surfactants selected from the group consisting of non-ionic surfactants and anionic surfactants.
13. A gum adhesive according to claim 1 , additionally comprising one or more plasticizers.
14. A gum adhesive according to claim 1 , additionally comprising one or more defoamers.
15. Paper coated with a gum adhesive according to claim 1 .
16. A process for manufacturing a gum adhesive according to claim 1 , comprising forming an aqueous dispersion of said at least one inorganic filler and said at least one protective colloid, combining one or more monomers and initiator with said aqueous dispersion, and polymerizing said one or more monomers in the presence of said at least one inorganic filler and said at least one protective colloid.