Oil/grease resistant paper products
Oil and grease resistant paper products include a substrate and, on at least one side of the substrate, a continuous layer of a barrier coating, the barrier coating including a binder system and a pigment. The barrier coating, when applied to the substrate and dried to form a barrier layer, provides a continuous film of the binder system.
1 . A paper product comprising:
a substrate; and
on at least one side of the substrate, a continuous layer of a barrier coating, the barrier coating comprising a binder system, the binder system comprising a latex and a natural binder in a ratio of from about 5:1 to 1:1, and a pigment,
wherein the barrier coating includes from about 40 to 750 parts of the binder system per 100 parts pigment by weight;
such that when the barrier coating is applied to the substrate and dried the barrier coating forms a continuous, void-free grease and oil resistant barrier layer.
2 . The paper product of claim 1 , further comprising a topcoat disposed on the surface of the barrier layer.
3 . The paper product of claim 2 wherein the topcoat includes a pigment blend comprising ground calcium carbonate having a particle size distribution with at least 90% of the particles less than 2 μm.
4 . The paper product of claim 2 wherein the topcoat comprises a natural binder.
5 . The paper product of claim 1 wherein the natural binder comprises starch.
6 . The paper product of claim 1 wherein the paper product exhibits >99% repulpability.
7 . The paper product of claim 1 further comprising a precoat disposed between the substrate and the barrier layer.
8 . The paper product of claim 7 wherein the precoat includes a pigment blend comprising a platy pigment and a coarse pigment with an average particle size of at least about 2 μm.
9 . The paper product of claim 7 wherein the precoat is calendered.
10 . The paper product of claim 1 wherein the paper product is free of fluorocarbon-containing materials.
11 . The paper product of claim 1 wherein the binder system includes from about 2 to 250 parts of polyvinyl alcohol.
12 . The paper product of claim 1 wherein the binder system includes from about 0.01 to 2 parts of calcium stearate.
13 . The paper product of claim 1 wherein the storage modulus on the TMA (thermomechanical analysis) curve of the latex is less than 50 MPa at room temperature (25° C.).
14 . The paper product of claim 13 wherein the storage modulus on the TMA curve of the latex is less than 30 MPa at room temperature (25° C.).
15 . The paper product of claim 1 wherein the barrier coating comprises about 40 to 500 parts latex and about 25 to 250 parts starch based on 100 parts pigment.
16 . The paper product of claim 1 wherein the binder system contains a sufficient amount of the natural binder to provide the paper product with >99% repulpability.
17 . The paper product of claim 1 wherein the barrier layer has a minimum of 2 to 3 μm thickness in a thinnest part of the barrier layer.
18 . A method of making a paper product comprising:
applying, to at least one side of a substrate, a continuous layer of a barrier coating, the barrier coating comprising a binder system, the binder system comprising a latex and a natural binder in a ratio of from about 5:1 to 1:1, and a pigment, wherein the barrier coating includes from about 40 to 750 parts of the binder system per 100 parts pigment by weight; and
drying the barrier coating to form a continuous, void-free grease and oil resistant barrier layer.
19 . The method of claim 18 further comprising applying a topcoat to the barrier layer.
20 . The method of claim 19 , wherein the topcoat is a graphical topcoat.
21 . The method of claim 19 further comprising calendering the topcoat.
22 . The method of claim 18 further comprising applying a precoat to the substrate prior to applying the barrier coating, on the same side of the substrate.
23 . The method of claim 22 further comprising calendering the substrate after applying the precoat and before applying the barrier coating.
24 . The method of claim 18 wherein applying the barrier coating is performed using a non-contact coater.
25 . The method of claim 18 further comprising calendering the substrate prior to applying the barrier coating.