A coating structure for a sheet-like substrate, which includes lignocellulosic fibres is disclosed. The structure includes at least one pre-coat layer including at least 70 weight-% of a first styrene (meth)acrylate copolymer polymerised in the presence of a stabiliser, having a glass transition temperature Tg ≤20° C. preferably ≤10° C., ≤30 weight-% of inorganic platy mineral particles and 0.01-2 weight-% of at least one first thickener. The coating structure further includes a top coat layer including at least 50 weight-% of a second styrene (meth)acrylate copolymer polymerised in the presence of a stabiliser having a glass transition temperature Tg ≤20° C. preferably ≤10° C., ≤30 weight-% of inorganic mineral particles, 0.01-5 weight-% of at least one second thickener and 0.5-30 weight-% of an antiblocking agent. Further disclosed is a sheet-like product coated with the coating structure.

A paper material and a flexible packaging material using the same are provided. At least one surface of the paper material is coated with a first coating layer and a second coating layer. The paper has an air permeability greater than 45200 sec and a dyne value less than 40 dyn/cm. The first coating layer includes an inorganic filler and a first water-based heat-sealable coating, and the first water-based heat-sealable coating includes a polyolefin dispersion, an ethylene acrylic acid copolymer, or a styrene acrylate emulsion. The second coating layer includes an inorganic filler and a second water-based heat-sealable coating, and the second water-based heat-sealable coating includes a polyolefin dispersion, an ethylene acrylic acid copolymer, a styrene acrylate emulsion, or polyvinyl alcohol.

A method of producing a surface sizing composition, the method comprising: providing a metal salt having at least 3 valence electrons, wherein the metal salt is selected from the group of aluminium sulfate, aluminium chloride, aluminium nitrate, polyaluminium sulfate (PAS), polyaluminium chloride (PAC), and polyaluminium chloride sulfate (PACS), polyaluminium formiate, polyaluminium nitrate, and any combination thereof; providing an aqueous polymer dispersion, wherein the aqueous polymer dispersion is an aqueous polymer dispersion (A) and an aqueous prepolymer composition (B), wherein the aqueous polymer dispersion (A) is obtainable by free radical emulsion copolymerizing a first ethylenically unsaturated monomer blend, and wherein the aqueous prepolymer composition (B) is obtainable by free radical emulsion copolymerizing in a polymerization solvent comprising C1-6-carboxylic acid and C1-6-carboxylic acid anhydride, a second ethylenically unsaturated monomer blend; and mixing the metal salt and the aqueous polymer dispersion to provide a surface sizing composition to be used in papermaking.

A method of producing a surface sizing composition, the method comprising: providing a metal salt having at least 3 valence electrons, wherein the metal salt is selected from the group of aluminium sulfate, aluminium chloride, aluminium nitrate, polyaluminium sulfate (PAS), polyaluminium chloride (PAC), and polyaluminium chloride sulfate (PACS), polyaluminium formiate, polyaluminium nitrate, and any combination thereof; providing an aqueous polymer dispersion, wherein the aqueous polymer dispersion is an aqueous polymer dispersion (A) and an aqueous prepolymer composition (B), wherein the aqueous polymer dispersion (A) is obtainable by free radical emulsion copolymerizing a first ethylenically unsaturated monomer blend, and wherein the aqueous prepolymer composition (B) is obtainable by free radical emulsion copolymerizing in a polymerization solvent comprising C1-6-carboxylic acid and C1-6-carboxylic acid anhydride, a second ethylenically unsaturated monomer blend; and mixing the metal salt and the aqueous polymer dispersion to provide a surface sizing composition to be used in papermaking.

The present disclosure is drawn to primer compositions, which can include a binder including polyvinyl alcohol, starch nanoparticles, and a crosslinkable polyurethane dispersion. The primer competitions can also include a cationic salt and water.

Oil and grease resistant paper products are disclosed that include 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 and a pigment. The barrier coating, when applied to the substrate and dried to form a barrier layer, has a Pigment Volume Concentration (PVC) that is below a Critical Pigment Volume Concentration (CPVC) of the barrier coating, providing a continuous three-dimensional film of the binder system. In some implementations the binder system comprising a latex and a natural binder and/or the paper product further includes a topcoat disposed on a side of the barrier coating opposite the substrate.

Oil and grease resistant paper products are disclosed that include 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 and a pigment. The barrier coating, when applied to the substrate and dried to form a barrier layer, has a Pigment Volume Concentration (PVC) that is below a Critical Pigment Volume Concentration (CPVC) of the barrier coating, providing a continuous three-dimensional film of the binder system. In some implementations the binder system comprising a latex and a natural binder and/or the paper product further includes a topcoat disposed on a side of the barrier coating opposite the substrate.

A total heat exchanging element paper for use in a total heat exchanger, comprising a substrate sheet containing natural pulp, having excellent strength and gas barrier properties, and characterized in that the substrate sheet contains natural pulp having a length-weighted average fiber length of 0.7 to 1.7 mm, the natural pulp has a maximum frequency peak between 0.5 mm and 1.5 mm in the fiber length histogram, and the percentage of fibers having a fiber length of 1.0 mm or more is 20% or more.

A total heat exchanging element paper for use in a total heat exchanger, comprising a substrate sheet containing natural pulp, having excellent strength and gas barrier properties, and characterized in that the substrate sheet contains natural pulp having a length-weighted average fiber length of 0.7 to 1.7 mm, the natural pulp has a maximum frequency peak between 0.5 mm and 1.5 mm in the fiber length histogram, and the percentage of fibers having a fiber length of 1.0 mm or more is 20% or more.

The invention pertains to a cellulosic material provided with a coating comprising an oxidized carboxylated starch having a weight-average molecular weight of 0.3−10×10.sup.6 Da and a water-soluble starch extender present in a quantity of 0 to 25 wt. % based on the coating dry weight, selected from a crosslinked cationic polyalkylene amine and a zirconium carbonate, as well as to use thereof in improving the oil and grease resistance of paper. The invention furthermore pertains to a method to improve the oil and grease resistance of a cellulosic material, comprising providing a cellulosic material, coating said material on at least one side with a homogenous aqueous composition comprising an oxidized carboxylated starch having a weight-average molecular weight of 0.3−10×106 Da and 0-3 wt. % of a starch extender, selected from a crosslinked cationic polyalkylene amine and a zirconium carbonate, and drying the cellulosic material.