Method for producing single-layer or multi-layer paper

Patent metadata

Field	Value
Publication number	US-11293143-B2
Application number	US-201816757525-A
Country	US
Kind code	B2
Filing date	Oct 10, 2018
Priority date	Oct 18, 2017
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A method to produce dried single-layer or multi-layer paper is disclosed. The method comprises, for a single-layer paper, preparing and spraying a partially dehydrated first fibrous web with a spray solution or suspension to give a sprayed partially dehydrated first fibrous web, and dehydrating the sprayed partially dehydrated first fibrous web by applying heat to form a dried single-layer paper; or, for a multi-layer paper, preparing and spraying a partially dehydrated layer compound with a spray solution or suspension to form a sprayed layer compound, and dehydrating the sprayed layer compound by applying heat to form a dried multi-layer paper. The spray solution or suspension comprises water and at least one water-soluble polymer P, which is obtained by polymerizing: (i) a monomer of formula H2CCHNHC(0)R1, where R1 is H or C1-C6- alkyl; and (ii) one or more ethylenically unsaturated monomers different from monomer (i).

First claim

The invention claimed is:

1. A process to produce dried single-layer or multi-layer paper, comprising the steps for a single-layer paper of:
(A) dehydrating a first aqueous fibre suspension, which has a dry matter content between 0.1 wt. % and 6 wt. %, on a first sieve, whereby a first fibrous web, which has a dry matter content between 14 wt. % and 25 wt. %, arises,
(D-1) dehydrating the first fibrous web by pressing, thereby creating a partially dehydrated first fibrous web,
(E-1) spraying the partially dehydrated first fibrous web on at least one surface side with a spray solution or spray suspension, which results in a sprayed partially dehydrated first fibrous web,
(F-1) dehydrating the sprayed partially dehydrated first fibrous web by applying heat to form the dried single-layer paper;
or comprising the steps for a multi-layer paper of:
(A) dehydrating a first aqueous fibre suspension, which has a dry matter content between 0.1 wt. % and 6 wt. %, on a first sieve, whereby a first fibrous web, which has a dry matter content between 14 wt. % and 25 wt. %, arises,
(B) dehydrating a second aqueous fibre suspension, which has a dry matter content between 0.1 wt. % and 6 wt. %, on a second sieve, whereby a second fibrous web, which has a dry matter content between 14 wt. % and 25 wt. %, arises,
(C) assembling the first fibrous web to the second fibrous web such that the two fibrous webs touch each other on an entire surface side, thereby resulting in a layer compound,
(D-2) dehydrating the layer compound by pressing, whereby a partially dehydrated layer compound is formed,
(E-2) spraying the partially dehydrated layer compound on at least one surface side with a spray solution or spray suspension, whereby a sprayed layer compound is formed,
(F-2) dehydrating the sprayed layer compound by applying heat results in the dried multi-layer paper;
wherein the spray solution or spray suspension comprises
(e-a) water, and
(e-b) at least one water-soluble polymer P, obtained by polymerizing
(i) 40 to 85 mol % of a monomer of Formula I

in which R 1 =H or C 1 -C 6 -Alkyl,

(ii) 15 to 60 mol % of one or more ethylenically unsaturated monomers which are different from a monomer of the Formula I,
wherein the total amount of all monomers (i) and (ii) is 100 mol %,
and optionally by subsequent partial or complete hydrolysis of the units of the monomers of the formula (I) polymerized into the polymer P to form primary amino or amidine groups,

wherein the proportion of water is at least 75% wt., based on the spray solution or the spray suspension.

2. The process of claim 1 for the manufacture of dried multi-layer paper comprising the steps
(A) dehydrating a first aqueous fibre suspension, which has a dry matter content between 0.1 wt. % and 6 wt. %, on a first sieve, whereby a first fibrous web, which has a dry matter content between 14 wt. % and 25 wt. %, arises,
(B) dehydrating a second aqueous fibre suspension, which has a dry matter content between 0.1 wt. % and 6 wt. %, on a second sieve, whereby a second fibrous web, which has a dry matter content between 14 wt. % and 25 wt. %, arises,
(C) assembling the first fibrous web to the second fibrous web such that the two fibrous webs touch each other on an entire surface side, thereby resulting in a layer compound,
(D-2) dehydrating the layer compound by pressing, whereby a partially dehydrated layer compound is formed,
(E-2) spraying the partially dehydrated layer compound on at least one surface side with a spray solution or spray suspension, whereby a sprayed layer compound is formed,
(F-2) dehydrating the sprayed layer compound by applying heat to form the dried multi-layer paper.

3. The process of claim 1 , wherein the spray solution or spray suspension has a pH value of 5.5 or greater.

4. The process of claim 1 , wherein for the single-layer paper in step (D-1) the partially dewatered first fibrous web has a dry matter content between 35% wt. and 65% wt., and for the multi-layer paper in step (D-2) the partially dewatered layered compound has a dry content between 35% wt. and 65% wt.

5. The process of claim 1 , wherein for the single-layer paper in step (F-1) the dried single-layer paper has a dry matter content of at least 88% wt., and for the multi-layer paper in step (F-2) this dried multi-layer paper has a dry content of at least 88% wt.

6. The process of claim 1 , wherein the polymer P is formed by polymerizing
(i) 40 to 85 mol % of a monomer of Formula I,
(ii) 15 to 60 mol % of one or more ethylenically unsaturated monomers which are different from a monomer of the Formula I,
wherein the one or more ethylenically unsaturated monomers are selected from
(ii-1) acrylic acid or methacrylic acid or their alkali metal, alkaline earth metal or ammonium salts,
(ii-2) acrylonitrile or methacrylonitrile,
(ii-3) vinyl acetate,
(ii-4) a monoethylenically unsaturated sulfonic acid, a monoethylenically unsaturated phosphonic acid, a monoethylenically unsaturated mono- or diester of phosphoric acid or a monoethylenically unsaturated carboxylic acid with 4 to 8 carbon atoms, which is different from methacrylic acid, or their alkali metal, alkaline earth metal or ammonium salts,
(ii-5) a quaternized, monoethylenically unsaturated monomer, a monoethylenically unsaturated monomer which carries at least one secondary or tertiary amino group and whose at least one secondary or tertiary amino group is protonated at pH 7, or a diallyl-substituted amine which has exactly two ethylenic double bonds and is quaternized or at pH 7 is protonated, or its salt form,
(ii-6) a monoethylenically unsaturated monomer which carries no charge at pH 7 and which is different from acrylonitrile, methacrylonitrile and vinyl acetate, or an ethylenically unsaturated monomer whose exactly two ethylenic double bonds are conjugated and which carries no charge at pH 7,
(ii-7) 0 to 2 mol % a monomer which has at least two ethylenically unsaturated double bonds which are not conjugated, and which is different from a diallyl-substituted amine which has exactly two ethylenic double bonds,
(ii-8) 0 to 10 mol % of ethylenically unsaturated monomer which is different than monomers (ii-1) to (ii-7),
wherein the total amount of all monomers (i) and (ii-1) to (ii-8) is 100 mol % and mol % relates to the total amount of all monomers (i) and (ii-1) to (ii-8),
and optionally by a subsequent partial or complete hydrolysis of the units of the monomers of the formula (I) polymerized into the polymer P to form primary amino groups or amidine groups, where in the presence of polymerized units of vinyl acetate these also partially or completely hydrolyse.

7. The process of claim 1 , wherein in the polymerization
(i) 50 to 85 mol % of a monomer of Formula I,
(ii) 15 to 50 mol % of one or more ethylenically unsaturated monomers which are different from a monomer of the Formula I,
are used.

8. The process of claim 1 , wherein
the one or more ethylenically unsaturated monomers comprises
(ii-1) 15 to 50 mol % Acrylic acid or methacrylic acid or their alkali metal, alkaline earth metal or ammonium salts,
where mol % refers to the total number of all monomers used in the polymerization and the total number of all monomers is 100 mol %.

9. The process of claim 1 , wherein the polymer P is formed by polymerizing
50 to 85 mol % of a monomer of Formula I
(ii-1) 15 to 50 mol % acrylic acid or methacrylic acid or their alkali metal, alkaline earth metal or ammonium salts,
(ii-2) 0 to 35 mol % acrylonitrile or me

Assignees

• Solenis Technologies Cayman Lp
• Solenis Tech Lp

Inventors

• Hamers Christoph
• Esser Anton
• De Bruyn Frans
• Gray Christopher Alan
• Isermann Ralph

Classifications

• D21F11/04

  paper or board consisting on two or more layers · CPC title

• D21H25/06

  of impregnated or coated paper (D21H25/08 takes precedence) · CPC title

• D21H23/50

  Spraying or projecting (D21H23/44, D21H23/66 take precedence) · CPC title

• D21H27/30

  Multi-ply (for surface covering D21H27/18; making on paper-making machines D21F9/00, D21F11/00) · CPC title

• D21H17/34

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title