ES2383762T3 - Paper making process - Google Patents

Abstract

The present invention relates to a process for improving the absorption rate for paper products. The process comprises treating a cellulosic fibre web comprising applying to said cellulosic fibre web at least one polymer; and colloidal particles.

Description

Papermaking process

The invention relates to a papermaking process for improving the absorption rate of, especially, tissue paper and lint paper products. In particular, the invention relates to a papermaking process which comprises applying at least one polymer and colloidal particles to a cellulose fiber network.

Background

Tissue paper and methods for manufacturing such paper are well known in the art. Typically, said paper is made by means of draining a cellulose suspension and forming a network on a wire. Normally, the cellulose suspension is contained in a head box before being deposited as a thin layer on a Fourdrinier wire to form a paper net. Typically, the paper net is then dehydrated by vacuum dehydration and subsequently dehydrated by pressing operations, in which the network is subjected to the pressure developed by opposing mechanical members, for example cylindrical rollers or a press of extended compression. The dehydrated network is subsequently pressed and dried by means of a steam drum apparatus known in the art as a Yankee cylinder. Typically, the paper fluff pulp is prepared by forming the paper sheet on a Fourdrinier wire which is subsequently pressed and dried to form bullets or rollers.

Next, the dried paper pulp is subjected to de-fibrillation using a hammer mill or a hole defibrillator to form the paper fluff. Typical products prepared from paper fluff are honeycombs and feminine hygiene products. You can also use paper fluff to generate airlaid paper products.

The absorption rate is one of the most essential properties of products made from tissue paper and paper fluff such as honeycombs, sanitary napkins, paper towels, facial and hygienic tissues, etc.

The absorption rate depends on both the surface chemistry of the fiber and the structure of the sheet.

WO 91/05108 describes a process for increasing the absorption rate of paper fluff pulp increases the specific surface area of the fibers. This is done by applying a porous layer of hydrophilic chemicals that precipitate on the fibers.

JP 2003-251928A refers to a method for coating and impregnating a paper sheet with a solution containing a water soluble polymer, colloidal silica and a sizing agent.

It is an object of the invention to provide a process that increases the rate of absorption of paper products, especially tissue paper and paper fluff products.

It is also an object of the invention to provide a process that increases the absorption rate without decreasing the wet strength of the tissue produced and the lint products of paper.

It is also an object of the invention to provide a process in which the added components are handled simply and can be supplied in high concentrations.

It is also an object of the invention to provide a process that reduces the problem of dust formation.

The invention

The present invention relates to a process for the treatment of a cellulose fiber network which comprises applying to said cellulose fiber network.

(i)

 at least one polymer, and

(ii)

 colloidal particles

in which the colloidal particles have a specific surface area of 400 to 1300 m2 / g.

It has been found that the process of the present invention confers a higher absorption rate to the paper produced.

According to one embodiment, natural and / or synthetic polymers can be used. Appropriate polymers may be of a cationic, anionic, amphoteric or non-ionic nature. The polymer may have a molecular weight of from about 2,000 to about 500,000,000, for example from about 100,000 to about 100,000,000, or from about 200.00 to about 50,000,000.

Suitably, synthetic polymers can have a molecular weight of about 2,000 to about 50,000,000, for example about 100,000 to about 10,000,000, or about 200,000 to about 1,000,000.

According to one embodiment, a cationic polymer is used. Examples of suitable cationic polymers include cationic polysaccharides, for example starches, guar gum, cellulose derivatives, chitins, chitosans, glucans, galactans, xanthan gums, pectins, mannan, dextrins. Appropriate starches include potato, corn, wheat, tapioca, rice, corn flour and barley starch. Cationic synthetic organic polymers such as cationic chain development polymers may also be used, for example, cationic vinyl addition polymers such as acrylate, acrylamide, vinylamine, vinylamine and allylamine based polymers, for example, homo-and copolymers based on diallyl alkyl ammonium halide, for example, diallyl dimethyl ammonium chloride, as well as (meth) acrylamides and (meth) acrylates. Other polymers include stepwise developmental cationic polymers, for example, cationic polyamidoamines, polyethylene imines, polyamines such as dimethylamineepichlorhydrin copolymers; and polyurethanes. Other examples of suitable cationic organic polymers include those described in WO 02/12626. According to one embodiment, the cationic polymer is chosen from the group consisting of a starch, guar gum, polydiallyldimethyl ammonium chloride, polyamidoamine and mixtures thereof.

According to one embodiment, the anionic polymer is used. Examples of anionic polymers include anionic stage development polymers, chain development polymers, polysaccharides, naturally occurring aromatic polymers and their modifications. Examples of anionic developmental polymer by appropriate steps include condensation polymers based on anionic benzene and based on naphthalene, preferably condensation polymers based on naphthalene sulfonic acid and condensation polymers based on naphthalene sulfonate; and addition polymers, that is polymers obtained by means of stepwise development addition polymerization, for example of anionic polyurethanes. Suitable examples of suitable anionic chain development polymers include anionic vinyl addition polymers, for example, acrylate and acrylamide based polymers comprising anionic or potentially anionic monomers such as (meth) acrylic acid and polystyrenesulfonic acid. Examples of suitable naturally occurring aromatic polymers and their modifications, that is, modified naturally occurring aromatic polymers include lignin-based polymers, preferably sulfonated lignins, for example lignosulfonates, kraft lignin, sulfonated kraft lignin and tannin extracts. Additional examples of other suitable anionic organic polymers include those described in WO 02/12626.

The term "chain development polymer", as used herein, refers to a polymer that is obtained by means of stage development polymerization, also called stage reaction polymer and stage reaction polymerization, respectively. . The term "chain development polymer", as used herein, refers to a polymer that is obtained by means of chain development polymerization, also called chain reaction polymer and chain reaction polymerization, respectively. .

Colloidal particles that can be used include for example inorganic colloidal compounds of silica and 6 metal oxides such as alumina, zirconia, magnesium oxide, titanium dioxide, iron oxide, zinc oxide; colloidal organic compounds, crosslinked anionic and cationic polyacrylamide and combinations thereof.

According to one embodiment, the colloidal particles have an average particle diameter ranging from about 1 to about 1000, such as from about 2 to about 100, or from about 3 to about 40 nm.

According to one embodiment, the colloidal particles are colloidal silica particles.

Colloidal silica particles, which are also called silica soles, can be produced, for example, from precipitated silica, pyrogenated silica or silica gels with sufficient purity and mixtures thereof. However, sodium silicate can also be used conventionally.

Colloidal silica particles that can be used in accordance with the invention can be modified and may contain other elements such as amines, aluminum and / or boron, which may be present in the particles and / or in the continuous phase. Boron-modified silica soles are described for example in US.

2,630,410. Suitably, the aluminum modified silica particles have an Al2O3 content of about 0.05 to about 3%, such as about 0.1 to about 2% by weight. The process of preparing aluminum-modified silica sol is described more in, for example, "The Chemistry of Silica", by Iler, K. Ralph, pages 407-409, John Wiley & Sons (1979) and in the US document. UU. 5 368 833. According to one embodiment, the colloidal silica particles are anionic colloidal silica particles.

According to one embodiment, the anionic colloidal silica particles have an average particle diameter ranging from about 1 to about 100, such as from about 2 to about 50,

or from about 3 to about 20 nm. In accordance with the present invention, the colloidal silica particles have a specific surface area of 400 to 1300, suitably from about 400 to about 900 m2 / g.

As is conventional in silica chemistry, particle size (diameter) refers to the average size (diameter) of major particles that may be aggregated or not aggregated.

According to one embodiment, cationic colloidal particles are used. According to one embodiment, a cationic polymer, an anionic polymer and cationic colloidal particles are applied in the order mentioned.

According to one embodiment, a cationic polymer is applied first after applying the anionic colloidal particles.

The term "cellulose fiber network" as used herein, includes any sheet or network prepared from cellulose fibers such as pulp sheets or paper nets.

When paper lint is prepared, the polymer and colloidal particles can be applied to the paper pulp sheet before defibrillation. The polymer and colloidal particles can be applied before or after drying of the cellulose fiber network, for example, during any stage in a conversion machine for the production of the tissue product. The cellulose fiber network may contain a variable dry content when the polymer and colloidal particles are applied. According to one embodiment, the cellulose fiber network has a dry content of about 5 to about 95, such as about 30 to about 60, or about 30 to about 50% by weight.

According to one embodiment, the polymer can be applied by immersion of the cellulose fiber network within a solution or dispersion of the polymer.

According to one embodiment, the colloidal particles can be applied by immersing the cellulose fiber network inside a dispersion comprising colloidal particles.

According to one embodiment, the polymer can be applied by spraying the polymer dispersion onto the surface of the cellulose fiber network. Appropriate polymer concentrations of the solution or dispersion depend, among others, on the type and molecular weight of the polymer. However, appropriate concentrations may be from about 0.001 to about 30, for example from about 0.01 to about 10, or from about 0.1 to about 5% by weight.

According to one embodiment, the polymer and colloidal particles are applied by spraying.

According to one embodiment, the colloidal particles can be applied by spraying once the polymer has been applied. The dispersion of the colloidal particles may have a dry content of about 0.001 to about 60, such as about 0.05 to about 10, or about 0.1 to about 5% by weight.

The polymer can be applied in an amount of about 0.01 to about 35, such as about 0.1 to about 15, or about 0.5 to about 7 kg / ton of dry cellulose fibers.

Colloidal particles can be applied in an amount of about 0.01 to about 35, such as about 0.1 to about 15, or about 0.5 to about 7 kg / ton of dry cellulose fibers.

The weight ratio of polymer applied to apply the colloidal particles may be approximately

1:50 to about 50: 1, such as from about 1: 5 to about 5: 1, or from about 0.8: 1 to about 1: 0.8.

According to one embodiment, the polymer and colloidal particles can be applied to the cellulose fiber network simultaneously, for example, in the form of pre-mixing or simultaneously at the same point of addition of the process.

According to one embodiment, the polymer and colloidal particles can be applied to the cellulose fiber network separately.

According to one embodiment, the cellulose fiber network is first applied followed by the application of colloidal particles.

The surface of the cellulose fiber network usually has a negative charge. In order to efficiently deposit negatively charged particles such as anionic colloidal silica particles, the surface of the fibers can be cationically charged. This can be done by applying a cationic polymer before the addition of anionic colloidal particles. According to one embodiment, a cationic polymer is applied to the network after which an anionic polymer is subsequently added before the application of the cationic colloidal particles.

Cellulose fiber networks may include cellulose fibers from wood pulp, for example, soft wood or hardwood pulp, including pulp such as kraft, sulphite and sulfate paper pulps, as well as mechanical paper pulps such as thermomechanical pulp of ground wood and chemically modified thermomechanical pulp (CTMP). Recycled fibers can also be used. Mixtures of chemical pulp and mechanical pulp can also be used. In addition, other cellulose fibers, such as rayon or cotton, may also be present in the tissue produced or in the paper fluff products, as part of the synthetic fibers. Tissue or lint paper products may also comprise different super absorbent materials.

According to one embodiment, conventional additives can be added to the cellulose suspension used to produce the cellulose fiber which, in turn, is processed to provide paper lint products or tissue products. Such additives include, for example, moisture resistance agents, dry strength agents, wetting agents and de-binding agents.

In the following, the invention is illustrated by means of the following examples but it is not intended that the invention be limited thereto.

Example 1

The reservation was prepared according to the standard method SCAN-M2: 64. The number of revolutions contributed by the blaster propellant was 30,000 and the concentration of the fiber suspension was 2.2% by weight, CSF = 700ml. Laboratory sheets (w = 90 g / m2) were prepared in a dynamic sheet forming device from a reserve of 0.5% by weight of HTCTMP (high temperature chemomechanical paper pulp) without the addition of chemical substances .

The sheet was cut into rectangular pieces (160x50 mm) with the longest side parallel to the crossing direction. The pieces of test paper were treated at room temperature by immersion in a polymer solution, referred to as a polyelectrolyte solution in the working examples herein (cationic, anionic or both solutions) and / or the sun dispersion of silica. A reference sample not treated with running water was treated. The concentrations of polyelectrolyte (polymer) and colloidal silica in the respective dispersions were 0.1% by weight. The immersion time was 1 min in each of the dispersions.

After immersion in the cationic polyelectrolyte dispersion, the test pieces were placed between two sheets of transfer paper and stained by means of winding in a metal cylinder (w = 10.6 kg, L = 120 mm, d = 85 mm) back and forth. Subsequently, after immersion in a silica sun, they were again stained in the same way. The untreated sample (reference mentioned herein), a sample treated only with polymer, and a sample treated only with silica sol in the same way were subjected to a stain. Paper samples placed on a perforated steel plate were stretched by fixing their ends with a paper tape or with metal bands and clamps. Plates with samples were placed in a dry box for drying (110 ° C / 60 minutes). Before the test, the absorption rate of the samples was stored overnight in a conditioning space (23 ° C / 50% RH).

The polymers, P1-P4, and the silica particles, A1-A4, used in the examples are those listed in the following list:

P1: Polydadmac Eka ATC 6140

P2: Starch-C PB 930, D.S., 0.04

P3: Guar Maypro-Bond rubber, D.S.O. 0.05

P4: Kenores XO polyamidoamine

A1: BMA 0 silica sol (500 m2 / g)

A2: Bindzil 50/50 silica sol (80 m2 / g)

A3: HDK N20 silica sol (200 m2 / g)

A4: NP590 silica sol (850 m2 / g)

The measurement of the water absorption rate was carried out in accordance with the standard method SCAN-P 62:88. The absorption rate in the three main directions is determined, that is, the machine direction, the transverse direction, and the direction perpendicular to the sheet plant. The collected values are the average values of the three measurements.

Example 2

Polymer P1 and colloidal particles A1 were used in example 2, which was carried out as described in example 1. Measurements were carried out on untreated paper (reference), paper treated only with polymer P1, asf as paper treated with both P1 polymer and A1 colloidal particles. The absorption rate in mm / s in the x, y and z directions was measured. Table 1 shows the results.

Table 1

Address

 x

Y z

Reference

1.42 4.07 1.06

P1

0.74 1.86 0.38

P1 + A1

4.95 10.71 8.27

In Table 1, it can be clearly seen that the absorption rate is considerably improved when on the one hand the polymer P1 and on the other hand the colloidal particles A1 according to the present invention are applied to the sheet in comparison with the sheet untreated (reference) or sheet treated only with polymer P1.

Example 3

Polymer P4 and colloidal particles A1 were used in example 3, which was carried out as described in Example 1. Measurements were carried out on untreated paper (reference), paper treated only with polymer P4, paper treated only with colloidal particles A1, as well as paper treated on the one hand with polymer P1 and on the other with colloidal particles A1. The absorption rate in mm / s in the x, y y directions was measured

z. Table 2 shows the results.

Table 2

Address

 x

Y z

Reference

1.23 3.25 0.89

P4

0.62 1.61 0.22

A1

1.71 4.48 1.4

P4 + A1

3.27 6.3 3.4

In Table 2, it can be clearly seen that the absorption rate is significantly improved when

20 apply both the polymer P4 and the colloidal particles A1 according to the present invention, on the sheet, in comparison with the reference sheet or the sheets treated only with the polymer or only with the polymer particles.

Example 4

Polymer P2 and colloidal particles A1 were used in example 4, which was carried out as described in

Example 1. Measurements were carried out on untreated paper (reference), paper treated only with P2 polymer, paper treated only with colloidal particles A1, as well as paper treated on one side with P2 polymer and on the other with colloidal particles A1. The absorption rate in mm / s in the x, y y directions was measured

z. Table 3 shows the results.

Table 3

Address

 x

Y z

Reference

1.48 3.83 1.18

P2

3.67 8.74 4.54

A1

1.81 4.57 1.43

P2 + A1

5.66 11.48 9.08

In Table 3 it can be clearly seen that the absorption rate is significantly improved when both the P2 polymer and the colloidal particles A1 according to the present invention are applied, on the sheet, as compared to the reference sheet or the sheets treated only with the polymer or only with the polymer particles.

Example 5

Polymer P3 and colloidal particles A1 were used in Example 5, which was carried out as described in Example 1. Measurements were carried out on untreated paper (reference), paper treated only with polymer P3, paper treated only with colloidal particles A1, as well as paper treated on the one hand with polymer P3 and on the other with colloidal particles A1. The absorption rate in mm / s in the x, y y directions was measured

z. In tests 3 and 5, the samples were treated with polyelectrolyte and silica sol dispersion according to example 1. In addition, after each immersion stage and stain press, the samples were rinsed by immersion in deionized water for 1 min followed by spotting. Table 4 shows the

15 results.

Table 4

Address

Test number

x Y z

one

Reference 1.67 4.17 1.15

2

P3 2.7 5.45 2.4

3

P3 (rinsed) 2.88 5.2 2.6

4

P3 + A1 6.6 14.5 12

5

P3 (rinsed) + A1 (rinsed) 6.98 13.4 15.8

In Table 3 it can be clearly seen that the absorption rate is significantly improved when both the polymer P3 and the colloidal particles A1 according to the present invention are applied, on the

20, compared with the sheet treated only with the polymer or only with the polymer particles.

Example 6

Polymer P1 and colloidal particles A1-A4 were used in Example 6, which was carried out as described in Example 1. Measurements were carried out on untreated paper (reference), paper treated only with

25 polymer P1 and on paper treated only with colloidal particles A1, as well as paper treated on the one hand with polymer P10 and on the other with colloidal particles A1-A4. The absorption rate in mm / s in the x, y and z directions was measured. Table 5 shows the results.

Table 5

Address

 x

Y z

Reference

1.63 3.98 1.6

P1 + A1

5.92 11.7 10.4

P1 + A2

3.27 6.2 5.2

P1 + A3

2.76 6.38 6.4

P1 + A4

5.11 11.1 17.1

In Table 5 it can be clearly seen that the absorption rate is significantly improved when colloidal particles having a large specific surface area, A1 and A4, are applied on the sheet, compared to colloidal particles having a specific surface area minor, A2 and A3.

Claims (12)

1.-A process for the treatment of a cellulose fiber network comprising applying to said cellulose fiber network, (i) at least one polymer; Y 5 (ii) colloidal particles, in which the colloidal particles have a specific surface area of 400 to 1300 m2 / g.

2.

The process according to claim 1, wherein the colloidal particles are colloidal silica particles.

3.

The process according to claim 1, in which the colloidal particles are anionic.

Four.

The process according to any one of claims 1-3, wherein the colloidal particles 10 have a specific surface area of 400 to 900 m2 / g.

5.

The process according to any one of claims 1-4, wherein the polymer is cationic.

6.

The process according to any one of claims 1-5, wherein the polymer is selected from the group consisting of starch, guar gum, polydiallyldimethyl ammonium chloride, polyamidoamine and mixtures thereof.

7.

The process according to any one of claims 1-6, wherein a cationic polymer, an anionic polymer and cationic colloidal particles are applied in the order mentioned.

8.

The process according to any one of claims 1-7, wherein the polymer is applied in an amount of 0.01 to 35 kg / ton of dry cellulose fibers.

9.

The process according to any one of claims 1-8, wherein the colloidal particles are applied in an amount of 0.01 to 35 kg / ton of dry cellulose fibers.

The process according to any one of claims 1-9, wherein the proportion by weight of polymer with respect to colloidal particles ranges from 50: 1 to 1:50. 11. The process according to any one of claims 1-10, wherein the polymer and the colloidal particles are applied by spraying. 12. The process according to any one of claims 1-11, wherein the polymer and colloidal particles are applied separately. 13. The process according to any one of claims 1-12, wherein the polymer and the colloidal particles are applied simultaneously.