Coated hot drink cup
A cup or food container has a coating formed of a styrene acrylic copolymer emulsion. There may be one or more coating layers on the inside surface of the cup or container. Importantly, the cup or container does not have any petroleum-based paraffin or polymer material or functionally similar hydrogenated triglyceride material coated on or incorporated in the cup or container. The paper substrate onto which the styrene acrylic copolymer emulsion is coated must have adequate sizing incorporated therein so that the coating forms a relatively smooth surface. Differently-sourced paper may require different amounts of sizing according to the particular paper being used. The cup or container may have a primer coating applied thereto before the styrene acrylic copolymer is coated on. Optionally, the uncoated paper stock that forms the cup or food container is calendared between rolls before coating.
1. A repulpable, moisture resistant hot drink cup comprising:
a paper cup comprising a paper bottom and a paper sidewall and having an inside surface of the cup defined by an inside surface of the bottom and an inside surface of the sidewall,
wherein the paper that forms the bottom and the sidewall is impregnated with sizing in an amount that a 30-minute Cobb value of an uncoated paper cup formed from the paper is about 400 gm/m2 or less, and the paper does not have any petroleum-based polymer incorporated in it,
and wherein the inside surface of the cup is coated with an emulsified mixture of styrene acrylic copolymer to provide a moisture resistance to the inside of the paper cup,
and further wherein the coating contains no hydrogenated triglyceride material.
2. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the bottom and sidewall are impregnated with sizing in an amount that the 10-minute Cobb value of an uncoated paper cup is about 200 gm/m2 or less.
3. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the bottom and sidewall are impregnated with sizing in an amount that the 10-minute Cobb value of an uncoated paper cup is about 100 gm/m2 or less.
4. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the solids content of the styrene acrylic copolymer emulsion is about 30% to 70%.
5. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the solids content of the styrene acrylic copolymer emulsion is about 45% to 55%.
6. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the solids content of the styrene acrylic copolymer emulsion is about 50%.
7. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the coated cup has a 10-minute Cobb value of about 5 gm/m2 or less.
8. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the coated cup has a 10-minute Cobb value of about 4 gm/m2 or less.
9. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the coated cup has a 10-minute Cobb value of about 3 gm/m2 or less.
10. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
further comprising a primer coating on the inside surface between the inside surface of the cup and the styrene acrylic copolymer coating layer, and wherein the primer coating is an polyvinyl alcohol.
11. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the styrene acrylic copolymer has a Tg of −10 to 40 degrees.
12. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the styrene acrylic copolymer has a Tg of 0 to 10 degrees.
13. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the styrene acrylic copolymer has a Tg of about 7 degrees.
14. A repulpable, moisture resistant hot drink cup as described in claim 1 ,
wherein the paper stock that forms the bottom and the sidewall of the cup is calendared by passing between two rollers prior to being formed as the bottom and sidewall of the paper cup.