There is described a substrate (S) for security documents, such as banknotes, comprising one or more paper layers (11, 12) and a polymer layer (20) which is made to adhere to a side of at least one of the paper layers (11, 12), which polymer layer (20) is substantially transparent in at least one region of the substrate (S) which is not covered by the paper layer or layers (11, 12) so as to form a substantially transparent window (W) in the substrate (S) which is formed and closed by the polymer layer (20). The polymer layer (20) exhibits in the region of the window (W) a thickness (T) which is greater than a thickness (t) of the polymer layer (20) outside of the region of the window (W). The thickness (T) of the polymer layer (20) in the region of the window (W) is substantially equal to the added thickness of the paper layer or layers (11, 12) and of the polymer layer (20) outside of the region of the window (W) so that the substrate (S) exhibits a substantially uniform and constant thickness (T). The substrate (S) further comprises a micro-optical structure (30), in particular a lens structure, which is disposed in the region of the window (W) on at least one side of the polymer layer (20).

The present invention relates to a method for manufacturing a multilayer film comprising highly refined cellulose fibers, the method comprising the steps of: a) forming a first wet web by applying a first pulp suspension comprising highly refined cellulose fibers on a first wire; b) partially dewatering the first wet web to obtain a first partially dewatered web; c) forming a second wet web by applying a second pulp suspension comprising highly refined cellulose fibers on a second wire; d) partially dewatering the second wet web to obtain a second partially dewatered web; e) applying a binder between the first and second partially dewatered web and joining the first and second partially dewatered web to obtain a multilayer web; and f) further dewatering, and optionally drying, the multilayer web to obtain a multilayer film comprising highly refined cellulose fibers.

The present invention relates to a method for manufacturing a multilayer film comprising highly refined cellulose fibers, the method comprising the steps of: a) forming a first wet web by applying a first pulp suspension comprising highly refined cellulose fibers on a first wire; b) partially dewatering the first wet web to obtain a first partially dewatered web; c) forming a second wet web by applying a second pulp suspension comprising highly refined cellulose fibers on a second wire; d) partially dewatering the second wet web to obtain a second partially dewatered web; e) applying a binder between the first and second partially dewatered web and joining the first and second partially dewatered web to obtain a multilayer web; and f) further dewatering, and optionally drying, the multilayer web to obtain a multilayer film comprising highly refined cellulose fibers.

A security paper, having a first paper ply and a second paper ply, and a plastic ply made of a thermoplastic polymer material arranged between the paper layers (1, 2), wherein a strip-shaped tear-off film is embedded between the paper layers on the inner side of the second paper layer and at least partially embedded into the plastic layer. Hidden information is arranged on the inner side of the first paper ply and is covered by the strip-shaped tear-off film or is arranged on the surface of the strip-shaped tear-off film facing the first paper ply. The hidden information can be exposed by the strip-shaped tear-off film together with a strip of the second paper ply being irreversibly torn off the multi-layer substrate.

A security paper, having a first paper ply and a second paper ply, and a plastic ply made of a thermoplastic polymer material arranged between the paper layers (1, 2), wherein a strip-shaped tear-off film is embedded between the paper layers on the inner side of the second paper layer and at least partially embedded into the plastic layer. Hidden information is arranged on the inner side of the first paper ply and is covered by the strip-shaped tear-off film or is arranged on the surface of the strip-shaped tear-off film facing the first paper ply. The hidden information can be exposed by the strip-shaped tear-off film together with a strip of the second paper ply being irreversibly torn off the multi-layer substrate.

A moisture control mechanism that allows a desired amount of moisture to evaporate out of a multiple ply paperboard structure is provided. The moisture control mechanism comprises an adhesive that adheres the multiple plies together, the adhesive comprising dextrin and an acrylic polymer. Alternately or additionally, a strength preservation mechanism that allows a strength to be maintained even when a multiple ply paperboard structure is highly wet. The strength preservation mechanism comprises an adhesive that adheres multiple plies together, the adhesive comprising dextrin and an acrylic polymer.

A moisture control mechanism that allows a desired amount of moisture to evaporate out of a multiple ply paperboard structure is provided. The moisture control mechanism comprises an adhesive that adheres the multiple plies together, the adhesive comprising dextrin and an acrylic polymer. Alternately or additionally, a strength preservation mechanism that allows a strength to be maintained even when a multiple ply paperboard structure is highly wet. The strength preservation mechanism comprises an adhesive that adheres multiple plies together, the adhesive comprising dextrin and an acrylic polymer.

A composite waterproof corrugated paper includes a stone paper medium and at least one stone liner paper. The stone paper medium has a first fluting surface and includes at least one first body layer and at least one adhesive layer which are coextruded. The first body layer includes a first surface. The adhesive layer is disposed on the first surface. The stone liner paper includes at least one second body layer and a supplementary layer which are coextruded. The supplementary layer is disposed on the second body layer and is attached to several wave crests of the first fluting surface, so that the stone paper medium adheres to the stone liner paper via the adhesive layer. A manufacturing method of the composite waterproof corrugated paper is also provided in the present invention.

A composite waterproof corrugated paper includes a stone paper medium and at least one stone liner paper. The stone paper medium has a first fluting surface and includes at least one first body layer and at least one adhesive layer which are coextruded. The first body layer includes a first surface. The adhesive layer is disposed on the first surface. The stone liner paper includes at least one second body layer and a supplementary layer which are coextruded. The supplementary layer is disposed on the second body layer and is attached to several wave crests of the first fluting surface, so that the stone paper medium adheres to the stone liner paper via the adhesive layer. A manufacturing method of the composite waterproof corrugated paper is also provided in the present invention.

The present invention relates to a method for the production of an adhesive component wherein said method comprises the following steps: providing a suspension comprising starch granules, adding a suspension comprising microfibrillated cellulose to the suspension comprising starch granules, drying the starch granules and microfibrillated cellulose suspension to a dry content above 70 wt-% to form said adhesive component. The invention also relates to an adhesive, a corrugated board, paper and paperboard comprising said adhesive and to the adhesive component produced according to the method.