FI117873B - Fiber web and method of making it - Google Patents

Description

1,117,873

Fiber web and method of making it

The present invention relates to a method according to the preamble of claim 1 for producing a highformation fiber web.

Such a fiber web generally comprises a filler-containing base web optionally coated with a pigment-containing coating layer.

10 The papermaking stock consists of cellulose or lignocellulosic fibers, fines and fillers. Many of these components, especially fillers, are so small in size that they do not mechanically adhere to the wire and must be bonded to the larger fibers or flocked to one another. Flocculation uses retention chemicals that are added to the stock prior to forming the web. As retention chemicals, mention may be made of polymeric products such as polyethyleneimine, low molecular weight polyacrylamide and polyamine, as well as cationic starch, guar or polyacrylamine combined with colloidal; silica, alumina or montmorillonite. The amount of retention chemicals is generally -j at least 0.5% of the dry matter of the fiber, typically about 0.6-1% of the dry matter of the fiber.

„20 In paper making, the smoothness of the web, ie the formatting, and the retention of the components of the stock • · • 1 2 3t · Il · · '. on the wire, or retention, are usually always some compromise: when the other

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* * 1 "is improved, the other gets worse. This is logical as retention normally requires

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• · · flocculation of small particles into clusters, which reduces the smoothness (or formatting) of the paper. For this reason, the paper often has to be driven at a lower retention than desired to achieve a smooth paper, which increases the circulation solids generator to produce various problems. In addition, currently commercially available retention systems are ··. very sensitive to chemical changes in circulating water.

The object of the present invention is to eliminate the disadvantages of the prior art 2 * · 30 and to provide a completely novel solution for producing a fiber web which has both good retention and formation at the same time.

·· ····. ' «· 1 • · 3 2 117873

The invention is based on the finding that the amount of conventional retention agents can be significantly reduced by replacing at least some of the conventional mineral fillers, i.e. powdered mineral pigments, with a composite pigment containing finely dispersed light scattering material particles.

This kind of filler product is known from FI Patent Publication No. 100729. The product comprises pearl bands formed of calcium carbonate particles precipitated on the surface of a finishing agent and hyacinth fibrils. It is characteristic of this novel filler according to the patent that the calcium carbonate is precipitated on pulverulent fibrils made from cellulose fibers and / or mechanical pulp.

10 The fines fraction corresponds predominantly to fraction P100 of the screen size screen.

According to said patent, the filler can be used to increase the content of calcium carbonate in the paper, thereby reducing the basis weight of the paper without changing the "other important" properties of the paper. The filler retention is good. The results of publication 15 are based on the results of the laboratory sheets measured by SCAN-C 26:76 and SCAN-M 5:76 respectively. In laboratory sheets, 0.65% of cationic starch and 0.15% of silica pulp are used. *

In the context of the present invention, it has been surprisingly found that the composite-20 fillers described above achieve high fiber formation retention on a paper or board machine such that conventional retention agents are not required at all or substantially less than conventional substrates.

* · * • · · • f • · * • * • *

According to the invention, 10-100% of the base web filler consists of cellulosic or ligno-cellulosic fibrils deposited on light scattering material particles, and * * these coated cellulosic or lignocellulosic fibrils represent up to about 70% by weight of the base web.

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• * · • · * * * '*. Specifically, the process of the invention for producing a highformation fiber web having a * * ... 30 without loss of retention is characterized by what is stated in the characterizing part of claim 1.

· »· T * · · *» · · * · • • • * 117873 3

The process for producing the fiber web according to the invention is further characterized by what is disclosed in the characterizing part of claim 15.

The invention provides significant advantages. Thus, the invention enables the production of 5 high-quality, high-formation paper with good retention, furthermore, the circulation water is substantially purified and the need for retention agents is reduced. The invention does not require filler flocculation at all, unlike commercially available retention systems, which have a fundamental effect on the formulation and the optical power of the filler.

10 Better format results in smoother and glossier paper. If the paper is coated, the coating will have better coverage, which will allow for smaller amounts of coating. Problems related to gloss and print irregularity are also reduced.

Conventional retention agents contain no or less than 20%, preferably up to 50% less, of conventional retention agents than conventional retention aids containing conventional particulate fillers. The solution according to the invention therefore reduces the chemical cost of the fiber web and facilitates the recycling of water on a paper or board machine. According to the invention, both conventionally used nanoparticles and polymers (see above) or both can be reduced. The said 20% reduction 20 may thus be calculated separately for one or both components together. Below: [', Example 3, presented, has been able to reduce the amount of polymer component by less than 30% by weight, while the amount of nanoparticles remains unchanged.

• · · • · Φ * · · 1 2 · • 1 * 1

The invention will now be explored in more detail with the aid of a detailed description and a few application examples.

1, Figure 1 shows the formatting of the web as a function of total retention of the results of Example 2, and Figure 2 shows the formatting as a function of tap water consistency.

M · '' * fio. According to a preferred embodiment, the present invention utilizes a sealant ... ... # 30 The filler used in the examples below contains a fines moiety comprising? 12 of chemical pulp fibrils. Chemical pulp, as used herein, refers to pulp that has been treated with cooking chemicals by deligni fi cation of cellulosic fibers and from pulps made by other modern processes. In addition to chemical pulps, the invention is also suitable for fillers made from fibrils derived from chemimechanical and mechanical pulps.

Typically, the average thickness of cellulose or lignocellulosic fibrils is less than 1 µm. Fibrils are characterized by one or both of the following criteria: a. They correspond to a fraction which passes through a 50 mesh sieve; b. having an average thickness of 0.01 to 10 µm (preferably up to 5 µm) and an average length of 10 to 1500 µm.

10

The starting material for the fibrils, i.e. the cellulose or other fiber-based fines, is fibrillated by grinding it in a pulverizer. If desired, the desired fraction can be separated by a sorter, but the fines need not always be sorted. Suitable fibril fractions are the P50 -P400 screen screen fractions. Preferably, refiners with grooved blades are used.

The light scattering material particles of the filler are inorganic or organic salts which can be formed from their starting materials by precipitation in an aqueous medium. Such compounds include calcium carbonate, calcium oxalate, calcium sulfate, barium sulfate, and mixtures thereof. The particles of material are deposited on the fibrils to produce a bead-like aggregate. The amount of the inorganic salt compound is from about 0.0001 to about 95% by weight, preferably from about 0.1 to about 90% by weight, preferably from about 60 to about 80% by weight based on the amount of filler * and from about 0.1 to about 60% by weight. %, preferably about 0.5 to 50% by weight of paper.

In the following, the invention will be examined using ♦ ·. ··· according to FI Patent Publication No. 100729. 25 products by way of example, but it is understood that other products mentioned above containing various light scattering pigments may be used in the invention.

♦ · • ·· The filler is prepared by depositing a mineral pigment on the surface of a cellulosic fiberizer / fines made of mechanical pulp. Eg Calcium • ·. ···. Precipitation of the carbonate can be accomplished by feeding calcium into the fibril water slurry. an aqueous mixture of hydroxide, optionally containing solid calcium hydroxide, and at least partially soluble in water, containing carbonate ions. The aqueous phase may also • contain carbon dioxide gas which, in the presence of calcium hydroxide, produces calcium 117,673 carbonate fibrils. , i.e., beaded-like calcium carbonate aggregates held by fine strands where the calcium carbonate particles are deposited on the fine strands. The effective volume is the volume required by the pigment.

The diameter of the calcium carbonate particles in the aggregates is from about 0.1 to about 5 µm, typically from about 0.2 to about 3 µm. Fibrils that correspond predominantly (at least more than 55%) to the P50 to P400 fabric screen fractions are commonly used.

The pulp is pulverized in a manner known per se to a suitable consistency (typically about 0.1 to 1% solids) and applied to a wire. Suitably, the filler is added to the fiber stock in the headbox of a paper or board machine for about 15 minutes, generally from about 1 to about 100 weight percent of the weight of the fibers in the pulp, i.e. the amount of filler can be as high as the actual pulp. Typically, the disclosed filler constitutes at least 5% by weight, preferably 10-100% by weight of the base web filler and 10-50% by weight of the base web fibrous material, respectively. In principle, it is also possible ··, 20 to produce a base web whose entire fiber material consists of a filler • «« *, ·. fibrils, so that in general, the present filler may comprise from 1 to 100% by weight of l · · * base fiber material.

* · * * · • · · • · * ·

Part of the filler used in the stock may consist of conventional fillers such as; ***; 25 of calcium carbonate. Preferably, however, at least 80%, particularly preferably at least 90%, of the doped light-scattering pigment particles are adhered to the fibrils.

·· »· • ··! _ In a paper or board machine, the pulp is rolled to form a paper or board web. The fiber web is dried and preferably coated and, optionally, post-coated. **. 30 is processed, for example, by calendering.

• · ··· ···] ·· '. The web can be coated with, for example, calcium carbonate, gypsum, aluminum silicate, • * kaolin, aluminum hydroxide, magnesium silicate, talc, titanium dioxide, 117873 6. u barium sulfate, zinc oxide, synthetic pigment or a mixture thereof.

The light scattering material particles of the web filler occur in a substantially non-flocculated form in the web. This means that the track has quite good formatting.

Thus, at formation level 10, the web contains conventional retention agents, such as cationic starch and / or silica, up to a total of 0.40% by weight of fiber. According to a particularly preferred embodiment, the orbit is substantially or completely free of ionic retention agents.

The invention can provide coated and optionally also calendered cellulosic material webs with excellent printability, good smoothness, and high opacity and brightness. By "cellulosic material" is generally meant paper or paperboard or similar cellulosic material derived from lignocellulosic feedstock, in particular wood, or annual or perennial plants. The material in question may be wood-based or wood-free and may be made from mechanical, semi-mechanical (chemimechanical) or chemical pulp. The mechanical pulp may be bleached or unbleached. The material may also include recycled fibers, particularly recycled paper or recycled paperboard. The basis weight of the material web typically ranges from 35 to 500 g / m 2, in particular from about 50 to 450 g / m 2. . J

20 ·· • · *. Generally, the base paper has a basis weight of 20 to 250 g / m 2, preferably 30 to 80 g / m 2. By coating this type of base paper with a weight of about 50 to 70 g / m210 to 20 g • · ·. · · ·. coating / m2 / side and calendering the paper yields a product having a basis weight of 70 to about 110 g / m, a brightness of at least 90%, and an opacity of at least 90%. Particularly inexpensive product • », ···. 25 is a coated offset paper that combines high gloss with high opacity and bulk.

* · · ·

The invention is also suitable for the production of coated papers, possibly also containing mechanical pulp, and writing and printing papers.

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The following non-limiting examples illustrate the invention. • ·. ··· stated in the examples. 30 measurement results for paper properties are determined using the following standard methods * ·· *: · * · * ·· ** • ·

Surface roughness: SCAN-P76: 95 i 7 117873:

Porosity: SCAN-P60 Permeability Resistance: SCAN-M8, P19

Example 1 5 Preparation of Filler Pulp pulp

Birch sulfate pulp was milled with a Valmet JC-01 refiner to produce 10 fillers suitable for filler. The refining consistency was about 4% and the total energy consumption was 343 kWh / t and the specific edge load was 0.5 J / m.

The product characteristics are given in Table 1.

'-i 15 Table 1. Fiber properties before and after milling

Before grinding After grinding

Fiber length (length), mm 0.86 0.58 20

Fiber length (weight), mm 1.00 0.77 f * ·· SR ° 16 86 • · * • · «φ; * j *; Carbonization of Fiber Pulp Carbonation was carried out in tap water as disclosed in FI Patent No. 100729.

: *: An aqueous slurry with a solids content of 2.22% was obtained. The final product had a CaCl3 content of 69.7% and a specific surface area of 10.6 m2 / g. The PCC had a particle size of * · • * ·· 30 orders of magnitude similar to Example 1 of the Fl patent.

• · · • ♦ • · · · ♦ · *: ··; Example 2 * »· '· y- m m * · • t. The product described in Example 1 was used as a filler for coated fine papers.

• · · · 35 The following table shows the results of the * * * fine paper run on the STFI pilot machine (FEX) in Stockholm: '117873

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Table 2. Fine Paper Run Results Filler - Total Tap Water,% Concentration,% Consistency, g / l Retention,% PCC Tm 2 ^ 03 "723 1 ~ 6 ~

PCC 2UÖ 2 ^ 8 663 TO

SuperFill "Ϊ73 038" 910 Ί03

SuperFill 223 037 883 93

The PCC used in the experiments was an Albacar LO product from Specialty Minerals.

The advantage of the invention is well apparent when the properties are simultaneously considered in the same coordinate system as shown in Figures 1 and 2 below.

Of particular value to the process is that the above-mentioned characteristic combinations are achieved at the same time with improved optical properties and strengths.

10

Example 3

Factory Test Preparation of Filler Base Paper 4 15 ··· For the coating, a base paper having a basis weight of 56 ·· **: V: g / m2 was prepared under factory conditions. The stock consisted of a mixture of birch pulp (74%) and pine pulp (24%). After milling, tm ', the SR number of the pine was 32-34 ° and that of the birch 22-25 °. The SR number of the mass in the headbox *: ** was 35-40 °.

20

The paper machine's wire section had a Valmet hybrid screen (Sym-former), and the wet press head * * consisted of a Valmet Sym-Press II with a triple press and a standard drying section.

·· • ♦ v «a

Three different fillers were used in the base paper, namely the products Finntalc F 15 SL 25 (Mondo Minerals Talc), Albacar HO (Specialty Minerals PCC) and the composite filler described in Example 1 *: *, hereinafter also referred to as "SuperFill".

Talc was used as filler at 10% and 15% and PCC and SuperFill at 10%, 15% and 20%.

9 1 1 7873

The retention chemicals used were nanoparticles and cationic starch (Compozil Plus: EKA NP 780 nanoparticle and EKA PL 1510 C-PAM, supplied by EKA Chemicals). For Talc and PCC, the dosage amounts were: nanoparticle 280 g / t, polymer 5 70 g / t, and SuperFill: nanoparticle 280 g / t, polymer 50 g / t. The application rates of cationic starch and resin size were 8 kg / t and 5.2 kg / t. Alum was dosed with talc at 13 kg / t and 19 kg / t with PCC and SuperFilk.

Results 10 No significant differences were observed with the different excipients in the water conductivity, COD, pH, cation requirement or dissolved calcium concentration. The filler retention was best with SuperFill (40-50%), although the dosage of the retention polymers was significantly lower than the other fillers. The retention of filler with talc and PCC was only 30-40%. SuperFilk's good retention significantly reduces the consistency and turbidity of circulating water compared to other fillers. There were no discernible differences between fillers and filler concentrations in the beta formulation.

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Claims (19)

A method of manufacturing a high-level, non-retention-degrading fiber web comprising a base web containing a filler and optionally coated with a pigment-containing coating layer characterized by abrasion; - as the base web filler, a composite pigment comprising cellulose or lignocellulose fibrils is used, where light-scattering material particles are precipitated, the amount of composite pigment accounting for 5 - 100% of the base web filler and the remainder of the filler constituting mineral filler, and - or the lignocellulosic fibrils make up at most about 70% of the weight of the base web, with more than 20% less retention agent consisting of nano-particles and / or polymeric retention agents used in the base web than in a web of the same formation, where the filler of over 95% consists of itself known, particulate mineral fillers. 15 Process according to claim 1, characterized in that the filler used comprises cellulose or lignocellulosic fibrils made from plant fibers by grinding or sieving, the average thickness of the fibrils being less than 10 µm, preferably not more than 5 µm. • · * · · * * * · *; · j Method according to claim 2, characterized in that the light-scattering material particles are deposited on fibrils which correspond to a fraction passing through a sieve. of 50 mesh and / or the average thickness of which is 0.01 to 5 µm and average length to 10 - 1500 µm. • · • * ·. 4. A process according to any of claims 1 to 3, characterized in that the light-scattering material particles are inorganic or organic salts which can be formed from their starting materials by precipitation in an aqueous medium. • · ♦ · · ♦ · ' Process according to claim 4, characterized in that the light-scattering material particles are calcium carbonate, calcium oxalate, calcium sulphate, barium sulphate, or a mixture thereof. , 4 1 1 7873 Method according to the claims 1-5, characterized in that the material particles are deposited on fibrils to produce a bead-like filler. Process according to Claim 6, characterized in that the amount of calcium compound in relation to the amount of fiber is in the range of 0.0001 - 90% by weight. 5 Process according to any of the preceding claims, characterized in that the base web is coated with calcium carbonate, gypsum, aluminum silicate, kaolin, aluminum hydroxide, magnesium silicate, talc, titanium dioxide, barium sulphate, zinc oxide, synthetic pigment or a mixture thereof. Method according to any of the preceding claims, characterized in that the filler, comprising cellulose and lignocellulose fibrils, on which light-scattering material particles are precipitated, forms 10 - 100% by weight of the base web filler. 10. A process according to any of the preceding claims, characterized in that the filler comprising cellulose and lignocellulose fibrils, wherein light-scattering material particles are precipitated, forms 10-50% by weight of the base web fiber material. 15 11. A method according to any of the preceding claims, characterized in ·· •. because the light-scattering material particles in the web filler are present in a substantially 9 * · * non-occluded form in the fiber web. •• »I •« * · «•« · • · • · 9 Method according to any of the preceding claims, characterized in that a fiber web is manufactured which, at formation level 10, retention means in the amount of 0 - 0.40% by weight of the fiber mass. • ':,:, J 13. A method according to claim 12, characterized in that a fiber web "· · · ... ..." is produced which is essentially free frenionic retention agent. ··· • · * «* 14. A method according to any of the preceding claims, characterized. *. from the manufacture of coated fine paper or printing or writing paper. • · · • * · 25, 5 1 1 7873 A method for manufacturing a high-level fiber web, wherein a fiber web is formed into a stock, of which a web is made by means of a paper or cardboard machine, characterized by 5. As a filler, the fiber stock is supplied with a product comprising cellulose or lignocellulose fibrils. whereby light-scattering material particles are precipitated, this product forming 5 - 100% of the filler and its amount up to a maximum of 70% of the pulp of the fibrous material, and - retention agent being dosed in the stock in an amount of 0 - 0.40% by weight of the fiber. the mass of the material. Method according to Claim 15, characterized by avant-filler used, comprising cellulose or lignocellulose fibrils made from plant fibers by grinding and sieving, the average thickness of the fibrils being less than 10 µm, preferably not more than 5 µm. 15 17. A method according to claim 16, characterized in that a filler is used where the light-scattering material particles are deposited on fibrils which correspond to a fraction passing through a 50 mesh screen and / or whose average thickness is up to 0.1%. 5 pm and average length til 10 - 1500 pm. • 1 • ·· • · · • · 1 ϊ Method according to any of claims 15-17, characterized in that a filler is used, in which at least 90% of the precipitated light-scattering pigment particles are attached to the fibrils. • · * · «• ♦ * ··· 1 19. A method according to any of claims 15-18, characterized in that the base web is coated by a paper machine with a pigment-containing coating layer. • · ♦ * · · • · ·. '• »· • · • · • · ·:' * · · •« • · • 1 1 * 1 · · · · · · · · · · · ·