EP0553135B1 - Paper, paperboard and cardboard internal sizing process - Google Patents

Abstract

According to a paper, paperboard and cardboard internal sizing process, resi n size is used, as well as cationic polymers containing polymerized vinylamine units as fixing agents for the resin size.

Description

The invention relates to a process for the mass sizing of paper, cardboard and cardboard using resin glue and cationic polymers which contain copolymerized vinylamine units as fixing agents.

From US-A-4 421 602 partially hydrolyzed homopolymers of N-vinylformamide are known which contain N-vinylformamide and vinylamine units. They are used as retention, drainage and flocculants in the manufacture of paper.

From EP-A-0 216 387 it is known that copolymers of 95 to 10 mol% of N-vinylformamide and 5 to 90 mol% of an ethylenically unsaturated monomer from the group vinyl acetate, vinyl propionate, the C₁ to C₄ alkyl vinyl ether , N-vinylpyrrolidone, the esters, nitriles and amides of acrylic acid and methacrylic acid in at least partially hydrolyzed form, in which up to 100 mol% of the formyl groups are split off from the copolymer, in amounts of 0.1 to 5% by weight, based on dry fibers, the paper stock before the sheet formation as a wet and dry strength agent for paper.

DE-A-32 03 189 sizing agents based on hydrophobic, cellulose-reactive sizing agents and fixing and sizing accelerating agents made of polymers are known which contain primary, secondary or tertiary amino and / or quaternary ammonium groups bound directly or via side chains. These cationic polymers also include hydrolyzed polymers of N-vinylformamide and partially hydrolyzed copolymers of N-vinyl acetamide and vinyl acetate. According to the information in DE-OS, hydrophobic, cellulose-reactive sizing agents are preferably alkyl ketene dimers, anhydrides, such as rosin anhydride and isocyanates.

The best-known bulk glue based on natural products is resin glue. These are compounds which are non-reactive with the cellulose fiber and which are deposited on the cellulose fibers in the paper stock with the addition of fixing agents. Suitable fixing agents are, for example, aluminum sulfate or, according to DE-B-10 70 916 and EP-B 0 187 666, cationic dicyandiamide resins. While the effectiveness of the cationic dicyandiamide resins is still in need of improvement, aluminum sulfate and alum have the disadvantage that they do not work with calcium carbonate as a filler in their presence can and that the papers available in this way are not sufficiently resistant to aging because of working in the acidic pH range.

The present invention is based on the object of demonstrating a process for mass sizing paper, cardboard and cardboard with resin glue, in which the sizing can be carried out in the neutral pH range and in which aging-resistant papers are obtained.

The object is achieved according to the invention with a process for the mass sizing of paper, cardboard and cardboard using resin glue and a fixing agent for fixing the resin glue on the cellulose fibers if cationic polymers are used as the fixing agent which contain copolymerized vinylamine units.

In the present context, resin glue is understood to mean the products based on natural materials that are usually used for the mass sizing of paper, e.g. Resin glue from hydrogenated rosin, tall resin glue, reinforced resin glue, dry resin glue or free resin-rich emulsions. These products are non-reactive resin glues which, when used alone in the bulk of paper, practically do not glue, but always have to be used together with a fixing agent. Suitable resin glues are described, for example, in the magazine "Papier", volume 43 (5), 188-192 (1989). As with known processes for the mass sizing of paper, resin glue is also used in the present process in an amount of approximately 1 to 4, preferably 1.5 to 3% by weight, based in each case on dry paper stock.

According to the invention, paper is sized by mass in the presence of small amounts of aluminum sulfate and / or alum using cationic polymers which contain copolymerized vinylamine units. Aluminum sulfate and alum are used in amounts of <5% by weight, preferably 2 to 3% by weight, as a precipitant for resin glue. The cationic polymers surprisingly act as fixatives for non-reactive resin glue. Polymers of this type are known, for example, from the literature references US-A-4 421 602 and EP-A-0 216 387 mentioned in the prior art. They are prepared by hydrolysis of homopolymers and copolymers containing copolymerized N-vinylamides.

in der R, R¹ = H, C₁- bis C₆-Alkyl bedeuten.Such polymers contain the following characteristic structures:

in which R, R¹ = H, C₁- to C₆-alkyl mean.

in der R = H, C₁- bis C₆-Alkyl bedeutet.For the preparation of compounds which contain only structural units of the formula I, for example, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylformamide, N-vinylpropionamide or N-vinylbutyramide are polymerized. From the compounds with structural elements of the formula I, the structure is formed by hydrolysis using acids, for example hydrochloric acid, sulfuric acid, phosphoric acid or under the action of bases, such as sodium hydroxide solution or potassium hydroxide solution, with the grouping -CO-R 1 being split off:

in which R = H, C₁ to C₆ alkyl.

eingesetzt, d.h. N-Vinylformamid. Partiell hydrolysierte Homopolymerisate der Verbindung III sind aus der obengenannten US-A-4 421 602 bekannt. Die Hydrolyse kann 0,1 bis 100 % betragen. Zu den bevorzugt in Betracht kommenden, Vinylamineinheiten einpolymerisiert enthaltenden Polymerisaten gehören Verbindungen, die durch Copolymerisieren von

• (a) 1 bis 99, vorzugsweise 10 bis 90 mol-% N-Vinylformamid und
• (b) 99 bis 1 mol-% monoethylenisch ungesättigten Monomeren aus der Gruppe Vinylacetat, Vinylpropionat, der C₁- bis C₄-Alkylvinylether, N-Vinylpyrrolidon, der Ester, Nitrile, Amide, N-Alkylamide und Sulfogruppen tragenden N-Alkylamide der Acrylsäure und Methacrylsäure und Mischungen dieser Monomeren

und anschließende Hydrolyse der Amidgruppen der Struktureinheiten I der Polymerisate in Aminogruppen der Struktur II erhältlich sind. Der Hydrolysegrad der einpolymerisierten N-Vinylformamideinheiten beträgt 0,1 bis 100 %, vorzugsweise mindestens 10 %.A 100% hydrolysis of all units of structure I in the polymer gives polyvinylamines. If only partial hydrolysis is carried out, the polymers prepared from the N-vinylamides contain units of structures I and II. The compound of the formula is preferably used as N-vinylamide

used, ie N-vinylformamide. Partially hydrolyzed homopolymers of the compound III are known from the above-mentioned US Pat. No. 4,421,602. The hydrolysis can be 0.1 to 100%. The preferred polymers containing copolymerized vinylamine units include compounds which are obtained by copolymerizing

• (a) 1 to 99, preferably 10 to 90 mol% of N-vinylformamide and
• (b) 99 to 1 mol% of monoethylenically unsaturated monomers from the group vinyl acetate, vinyl propionate, the C₁ to C₄ alkyl vinyl ether, N-vinylpyrrolidone, the esters, nitriles, amides, N-alkylamides and sulfo groups-bearing N-alkylamides of acrylic acid and methacrylic acid and mixtures of these monomers

and subsequent hydrolysis of the amide groups of structural units I of the polymers are obtainable in amino groups of structure II. The degree of hydrolysis of the polymerized N-vinylformamide units is 0.1 to 100%, preferably at least 10%.

Such copolymers are described in EP-A-0 216 387. In addition to N-vinylformamide, the monomer of component (a) can be e.g. Use N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinylpropionamide or N-vinylbutyramide. In the hydrolysis of copolymers of N-vinylformamide and vinyl acetate or vinyl propionate, depending on the reaction conditions, the copolymerized monomer units (b) can also be hydrolyzed, so that in the case of the latter comonomers, the copolymers are then additionally, e.g. Polymerized vinyl alcohol units included. The hydrolysis of the acetyl and / or propionyl groups from the copolymerized units (b) of the copolymers can be 0.1 to 100%.

The homopolymers and copolymers containing copolymerized vinylamine units have K values of 5 to 300, preferably 15 to 150. Polyvinylamines and hydrolyzed copolymers of N-vinylformamide with K values of 20 to 115 are particularly preferred.

The cationic polymers containing copolymerized vinylamine units are water-soluble. They are added directly to the paper stock for mass sizing or can also be added to the paper stock in the form of a mixture with the resin glue. In the case of a separate metering of polymer and resin glue, it makes no difference whether the resin glue is added to the paper stock first or the cationic polymer because the components always mix sufficiently in the paper stock. Based on 100 parts by weight of resin glue, 1 to 100, preferably 5 to 30 parts by weight of at least one cationic polymer which contains vinylamine units in copolymerized form are used.

All the usual qualities can be considered as pulps for the production of the pulps, for example wood pulp, bleached and unbleached cellulose and pulps from all annual plants. For example, wood pulp includes wood pulp, thermomechanical material (TMP), chemo-thermomechanical material (CTMP), pressure sanding, semi-pulp, high-yield pulp and refiner mechanical pulp (RMP). As pulp For example, sulfate, sulfite and sodium pulps come into consideration. The unbleached pulps, which are also referred to as unbleached kraft pulp, are preferably used. Suitable annual plants for the production of paper materials are, for example, rice, wheat, sugar cane and kenaf. Waste paper is also used to produce the pulps, either alone or in a mixture with other fibrous materials. To produce paper, cardboard and cardboard, the pulps are mixed with resin glue and at least one polymer to be used according to the invention as a fixing agent and dewatered in a known manner on a sieve of a paper machine. The pulp concentration is 0.1 to 1.5% by weight, the pulp pH up to 8. Pulps with a pH of 6 to 7.5 are preferred.

Folgende Einsatzstoffe wurden verwendet:The parts given in the examples are parts by weight. The percentages relate to the weight of the fabrics. The K values were determined according to H. Fikentscher, Cellulose-Chemie, Vol. 18, 48-64 and 71-74 (1932) in 5% aqueous saline solution at a temperature of 25 ° C. and a polymer concentration of 1% by weight . The sizing quality was determined with the aid of the Cobb value according to DIN 53 132 and the ink floating time up to a 50% breakthrough. The preparation image was also determined to characterize the sizing. For this purpose, a paper strip (80 cm x 10 cm) is drawn through a laboratory size press with a constant contact pressure and a speed of 10 m / min. Drinking water is used as the test liquid. The preparation uptake is calculated from the weight gain as follows:

The following ingredients were used:

Sizing agent 1

50% low-viscosity resin soap, made from chemically reinforced natural resins with a total resin acid number of 170, a free resin content of approx. 2% and a Brookfield viscosity at 20 ° C and 20 rpm of 1000 mPas.

Fixing agent 1

11% aqueous solution of a copolymer which contained 98% vinylamine units and 2% N-vinylformamide units and had a K value of 87. The pH of the aqueous solution was 3.5.

Fixing agent 2

12% aqueous solution (pH 3.5) of a copolymer which contained 68% vinylamine, 2% N-vinylformamide, 25% vinyl alcohol and 5% vinyl acetate units and had a K value of 105.

Fixing agent 3

17% aqueous solution of a copolymer which contained 45% vinylamine and 55% N-vinylformamide units and has a K value of 87. The pH of the aqueous solution was 3.5.

Examples

A paper fabric is made from 100% bleached birch sulfate pulp with the addition of 40% chalk. The degree of grinding is 35 ° SR (Schopper-Riegler). To this substance, based on the solids content, 1.5% by weight of the sizing agent, 3% by weight of alum and then 0.1% by weight, based on the solid, of one of the fixing agents mentioned in Tables 1 and 2 are added . The pH of the substance remains unchanged at pH 7. In all examples, 0.3% of a commercially available weakly cationic polyacrylamide with a K value of 130 was added to the paper stock as a retention agent and sheets were then formed on a Rapid-Köthen sheet former with a basis weight of 100 g / m 2. The leaves were each dried on a steam-heated drying cylinder at 90 ° C. to a residual moisture of 6 to 10%.

In all examples, the preparation uptake, the Cobb value and the ink floating time were determined immediately after drying. These results are summarized in Table 1. The leaves were then stored for one day at 23 ° C and 50% relative humidity. The preparation uptake, the Cobb value and the ink floating time were then determined. The measurement results obtained are given in Table 2.

Comparative example

Example 1 was repeated with the only exception that instead of 0.1% by weight of fixative 1, only 3% by weight of alum was used as fixative and precipitant. The pH of the pulp was 7. The results obtained are shown in Tables 1 and 2. Table 1 Immediate sizing example fixer Preparation intake (%) Cobb value 60˝ Ink Float (min) 1 1 21.1 31 > 60 2nd 2nd 22.5 51 30th 3rd 3rd 21.2 41 > 60 Comparative example 1 alum 30.3 46 5 Sizing after aging example fixer Preparation intake (%) Cobb value 60˝ Ink Float (min) 1 1 18.5 46 > 60 2nd 2nd 21.5 49 > 30 3rd 3rd 17.9 41 > 60 Comparative example 1 alum 31.2 64 1

Claims (6)

1. A process for the engine sizing of paper, board and cardboard using resin size and a fixing agent for fixing the resin size to the cellulose fibers, wherein the fixing agent used is a cationic polymer which contains polymerized vinylamine units.
2. A process as claimed in claim 1, wherein the fixing agent used is a hydrolyzed homopolymer of N-vinylformamide having a degree of hydrolysis of from 0.1 to 100%.
3. A process as claimed in claim 1, wherein the fixing agent used is a hydrolyzed copolymer of N-vinylformamide which contains, as polymerized units, not more than 99 mol % of ethylenically unsaturated monomers from the group consisting of vinyl acetate, vinyl propionate, the C₁-C₄-alkyl vinyl ethers, N-vinylpyrrolidone, the esters, nitriles and amides of acrylic acid and methacrylic acid and in which the degree of hydrolysis of the polymerized N-vinylformamide units is from 0.1 to 100%.
4. A process as claimed in claim 1 or 2 or 3, wherein the fixing agent used is a hydrolyzed polymer which is obtainable by polymerizing

   (a) from 100 to 10 mol % of N-vinylformamide and

   (b) from 0 to 90 mol % of vinyl acetate and/or vinyl propionate

   and subsequently eliminating from 0.1 to 100% of the formyl groups from the polymerized units (a) and, if required, from 0.1 to 100% of the acetyl and/or propionyl groups from the polymerized units (b) of the copolymer.
5. A process as claimed in claim 1 or 2 or 3 or 4, wherein from 10 to 300 parts by weight of one or more cationic polymers are used per 100 parts by weight of resin size.
6. Use of a cationic polymer which contains polymerized vinylamine units as a fixing agent for resin size in the engine sizing of paper, board and cardboard.