filler

Abstract

The invention relates to a method for producing a filler for paper, comprising the steps of providing a float from a paper recycling process, wherein the float contains titanium dioxide; subjecting the float to a mechanical and / or chemical treatment; mixing the mechanically and / or chemically treated float with titanium dioxide; and a filler obtainable according to the method, a paper containing the filler and the use of such paper as decorative paper.

Description

[0001] The present invention relates to a method for producing paper fillers, the fillers obtainable by the method, paper containing the fillers, and the use of such paper as decorative paper.

[0002] Paper's main component is fibrous material, primarily derived from wood. It is classified into mechanical pulp (Holzstoff) and chemical pulp (Zellstoff) based on the method of obtaining the fibrous material. In the case of mechanical pulp, wood is mechanically processed; in the case of chemical pulp, wood is processed using chemical methods. The fibrous material can also be obtained from recycled used paper (i.e., waste paper).

[0003] Non-fibrous additives used in papermaking include fillers such as pigments. Examples of fillers used include kaolin, calcium carbonate, magnesite, and / or titanium dioxide. These fillers are particularly used to improve smoothness, printability, and to influence the whiteness and opacity of paper. Titanium dioxide is especially used as a filler.

[0004] A method for recovering fillers and coating pigments for paper, thick paper and paperboard production is known from DE 196 27 523C1.

[0005] Residual water sludge containing fillers and pigments, or residual water sludge in which the fibers have been mechanically and / or chemically separated (e.g., by flotation to obtain a slurry), is fed here.

[0006] - Mix and

[0007] -Then ground into

[0008] Pigment paste containing fresh pigments or fresh fillers as powder.

[0009] Slurry containing fresh pigments and / or

[0010] Slurry containing fresh filler.

[0011] Conventional paper machines can be supplied with titanium dioxide from various sources. Therefore, a mixture of "fresh" titanium dioxide and titanium dioxide-containing pulp from recycled paper is often used.

[0012] The problem here is that pulp from paper recycling processes typically contains titanium dioxide as flocculent titanium dioxide with an average particle size greater than 2 μm. Therefore, such pulp only introduces ash into the paper but does not affect the paper's opacity, since only titanium dioxide with an average particle size between 300 nm and 400 nm contributes to the paper's opacity.

[0013] In this context, ash typically refers to the inorganic, non-flammable components of paper. Ash can include, for example, fillers, impurities, and pigments.

[0014] The ash content, i.e., the type, content, and composition of fillers, plays a decisive role, especially in the performance, quality, and production cost of paper. In particular, the resulting opacity is significant.

[0015] The composition of ash can be high-quality and cost-intensive (e.g., high proportion of titanium dioxide) or low-quality and low-cost. On the one hand, apart from titanium dioxide, ash is generally cheaper than organic fibers; on the other hand, the addition and composition of ash can generate and improve new paper properties, as well as optimize production processes technically and energy-wise.

[0016] High ash content can also impair the performance of paper machines because the paper's breaking load is reduced, making it more prone to tearing, and the operating speed must be reduced accordingly.

[0017] Therefore, the object of the present invention is to eliminate the above-mentioned disadvantages and provide a method for producing a filler and a filler that can be obtained by the method, wherein the filler can introduce high opacity into paper, and wherein as much titanium dioxide as possible can be saved at the same time. Therefore, high ash retention is required to avoid loss of raw materials. Furthermore, such a filler in the paper should give the paper high opacity and breaking load.

[0018] This objective is achieved by the method according to claim 1, particularly by a method for producing paper fillers, the method comprising the following steps:

[0019] - Provide a pulp from a paper recycling process, wherein the pulp contains titanium dioxide.

[0020] - Mechanical and / or chemical treatment of this laitance, and

[0021] - Mix the mechanically and / or chemically treated slurry with titanium dioxide.

[0022] The present invention also relates to fillers that can be obtained by this method.

[0023] This method allows for the provision of a filler that can introduce high opacity into paper while requiring as little "fresh" titanium dioxide as possible. Therefore, titanium dioxide can be saved due to high ash retention.

[0024] Furthermore, this filler is characterized by the fact that its use causes almost no damage to the performance of the paper machine, thus allowing for economical operation.

[0025] Paper containing this filler is characterized in particular by its high opacity and favorable breaking load.

[0026] In this specification, the term "comprising" may also mean "consisting of".

[0027] The filler components include titanium dioxide-containing slurry from paper recycling, wherein the slurry is mechanically and / or chemically treated.

[0028] In paper recycling, waste paper is typically pulped with water in a pulper. The recycled fibers are then usually cleaned of coarser impurities and subsequently finely sorted. In the so-called deinking process, printing inks and fillers are further removed from the fiber mixture through flotation or washing processes.

[0029] During flotation, other particles that have separated from the fibers and are present in the material suspension after the fiber separation stage, such as colored particles or fillers, adhere to the bubbles via collector chemicals and are transported to the surface of the flotation cell. This results in a frothy mass that may contain fibers and fillers in addition to the separated colored particles. Furthermore, a small amount remains in the flotation cell, which can also be referred to as residual water sludge. The resulting froth, preferably representing pulp, is skimmed off, cleaned, and can be used as ash in papermaking. Residual water sludge can be treated or discarded by other methods, such as those described in DE 196 27 523C1.

[0030] Therefore, it is essential to distinguish the slurry from the remaining portion (residual water and sludge) in the flotation cell.

[0031] In this case, the inventors have discovered that such slurries can be used advantageously if they are further mechanically and / or chemically treated and mixed with titanium dioxide.

[0032] The titanium dioxide added here refers to "fresh" titanium dioxide, that is, titanium dioxide not obtained from paper recycling.

[0033] Suitable titanium dioxide includes rutile, preferably obtained by chloride and / or sulfate production methods, especially anatase.

[0034] Suitable titanium dioxide is known, for example, under the trade names Tiona RCL-722 titanium dioxide chloride, KRONOS2800 titanium dioxide chloride, LOMON LR-952 titanium dioxide sulfate, Cinkarna RC-87 titanium dioxide, HOMBITAN R 610L titanium dioxide sulfate, or NR 950 titanium dioxide sulfate.

[0035] A preferred feature of the method according to the invention is that the slurry is obtained by flotation, i.e., by means of compressed air supply and the addition of flocculants, particularly anionic flocculants (e.g., S-FLOCS-A21 from Servophil AG), preferably in a recovery unit (preferably from Krofta), so as to remove titanium dioxide from the sieve water (Siebwasser) and supply it for papermaking.

[0036] In addition to titanium dioxide, this pulp may contain fine powder (chemical pulp), pigments such as iron oxide, kaolin and / or silicates.

[0037] In one embodiment of the method according to the invention, only the laitance is mechanically treated.

[0038] In another embodiment of the method according to the invention, only the slurry is chemically treated.

[0039] In another preferred embodiment of the method according to the invention, the laitance is subjected to mechanical and chemical treatment.

[0040] The mechanical and chemical treatments can be performed sequentially.

[0041] The mechanical and chemical treatments can also be performed simultaneously.

[0042] Preferably, a chemical treatment is performed first, followed by a mechanical treatment, and then another chemical treatment.

[0043] In one embodiment, chemical treatment is first performed to destabilize the aggregates in the slurry, followed by mechanical treatment to crush the aggregates in the slurry, and then further chemical treatment to stabilize the powder aggregates in the slurry.

[0044] Preferably, the chemical treatment of the slurry prior to mechanical processing includes a chemical destabilization step. In this process, large anionic flocculent aggregates (after the TiO2 recovery unit (Krofta)) are strongly destabilized by adding a cationic polymer, such as cationicly charged polyacrylamide (e.g., S-FLOCS-K89 from Servophil AG) in aqueous solution or a latex-containing solution, preferably as an antiflocculator. Preferably, this reduces the attractiveness of the aggregates, allowing for more efficient subsequent mechanical processing, particularly mechanical pulverization.

[0045] The amount of cationic polymer used is preferably 0.5 to 5 ppm by weight (absolutely dry) relative to the total amount of slurry flowing through.

[0046] Alternatively, the opposite system can be applied. In this case, cationic flocculants are first generated to recover TiO2 from sieved water, and then the system is electrically charged by adding a strong anionic antiflocculator (e.g., an aqueous solution of a strong anionic polyacrylamide or a latex-containing solution, such as Servophil AG's S-FLOCS-A82 polyacrylamide).

[0047] The preferred dosage of anionic antiflocculation agent relative to the total amount of slurry flowing through is 0.5 to 5 ppm.

[0048] A further preferred feature of the method according to the invention is that the mechanical treatment of the laitance includes the use of shear forces. These shear forces are preferably generated by a complete assembly comprising a rotor and a stator.

[0049] In particular, the unit, including the corresponding complete set of components, can be directly installed in the pipeline that delivers the slurry to achieve a high shear rate.

[0050] The degree of mechanical processing can be determined by the speed or frequency of the motor and the corresponding shearing force, which is determined individually for each complete assembly.

[0051] The suitable unit known here is the "ShearMaster" from Bauer Verfahrenstechnik GmbH.

[0052] The principle here is that the slurry flows through the rotating and stationary parts of the entire set of components of the unit, which are preferably the same as those of a refiner or an entstipper.

[0053] Multiple units of a complete assembly including rotor and stator can be connected in series or in parallel.

[0054] In one implementation, multiple units (e.g., two) of a complete assembly including a rotor and a stator are connected in series.

[0055] The advantage of this arrangement is that the total residence time of the laitance in the entire assembly is longer (e.g., twice as long when using two machines) and more energy is input into the laitance.

[0056] In another implementation, multiple units (e.g., two) of a complete assembly including a rotor and a stator are connected in parallel.

[0057] The advantage of this arrangement is that it can handle a large amount of laitance in a shorter time, and the parallel complete set of components can serve as a backup for the failed complete set of components without requiring a large amount of technical effort.

[0058] Combinations of complete components, including series and parallel connections of rotor and stator, are also possible.

[0059] Furthermore, the method according to the invention preferably includes a step of chemical stabilization by adding a dispersant, preferably an anionic dispersant. This step is preferably performed for the time necessary to ensure and maintain the pulverizing effect.

[0060] The method according to the invention is further preferably characterized in that the chemical treatment of the slurry includes incubating the slurry together with a dispersant, preferably an anionic dispersant.

[0061] Suitable anionic dispersants include, for example, acrylic polymers or acrylate polymers.

[0062] Suitable anionic dispersants are known, such as Topsperse GX N from COATEX, Dispex AA 4140 from BASF, or S-DISP PA4 from Servophil AG.

[0063] The amount of dispersant, preferably anionic dispersant, is preferably 0.1 to 2.0% by weight of absolute dryness relative to the absolute dryness of titanium dioxide in the slurry.

[0064] Chemical treatment of the slurry is advantageous because it stabilizes the individual titanium dioxide particles, especially those produced during shearing, in terms of charge for a short period of time.

[0065] The advantage of mechanically and / or chemically treating the pulp in this way is that the flocculent titanium dioxide (particle size greater than 2 μm) initially contained in the pulp is treated to reduce the particle size to about 300 nm to 400 nm, and thus can increase the opacity of the paper, preferably with the same ash content.

[0066] In a preferred embodiment, the chemical and mechanical treatment of the slurry includes a first step of chemical stabilization as described above, a second step of mechanical treatment as described above, and a third step of chemical stabilization as described above.

[0067] In a preferred embodiment, the chemical and mechanical treatment of the slurry includes a first step of chemical stabilization, wherein large anionic flocculants (after reaching the TiO2 recovery unit (Krofta)) are strongly converted to electrical load by the addition of a cationic polymer, preferably used as an anti-flocculation agent, a second step of mechanical treatment using shear force, and a third step of chemical stabilization by the addition of a dispersant (preferably an anionic dispersant).

[0068] A further preferred feature of the method according to the invention is that the pulp from the paper recycling process contains 0.5% to 5% by weight of titanium dioxide. This is related to the titanium dioxide content prior to mechanical and / or chemical treatment.

[0069] The method according to the invention is further preferably characterized in that the pulp from the paper recycling process contains titanium dioxide with an average particle size greater than 2 μm.

[0070] The method according to the invention is further preferably characterized in that the mechanically and / or chemically treated slurry contains titanium dioxide with an average particle size of 300 nm to 400 nm, preferably 320 nm to 400 nm.

[0071] A particle size of 320 nm to 400 nm is particularly preferred because titanium dioxide particles of this size are especially advantageous for achieving high opacity in paper.

[0072] Average particle size can be determined by laser diffraction. The median D50 is determined as the primary measurement parameter.

[0073] The method according to the invention is further preferably characterized in that the mixing ratio of mechanically and / or chemically treated slurry to titanium dioxide is from 40 wt%:60 wt% to 60 wt%:40 wt%.

[0074] A suitable mixing ratio of mechanically and / or chemically treated slurry to titanium dioxide is, for example, 50% to 50% by weight or 56% to 44% by weight.

[0075] Such mixing ratios are particularly advantageous because they reflect the true state of the paper machine and ensure the maximum efficiency or yield coefficient of the paper machine relative to titanium dioxide consumption.

[0076] In one embodiment, the method for producing paper fillers according to the invention can be operated as a standalone method. The resulting filler can be unloaded, stored, or transported for use at another time and / or in another location.

[0077] Preferably, the method according to the invention is characterized in that it is integrated into a papermaking apparatus.

[0078] Specifically, the method according to the invention is integrated into a papermaking apparatus as follows. The entire apparatus can be installed in the pulp line between the Krofta or titanium dioxide recovery unit and the main papermaking line, before the vertical classifier, as a new / modified component.

[0079] The present invention also relates to fillers that can be obtained by the above methods.

[0080] All the definitions and preferred embodiments listed for the above methods are similarly applicable to the packings according to the present invention.

[0081] The present invention also relates to paper comprising fillers that can be obtained by the methods described above.

[0082] All the definitions and preferred embodiments listed above for the methods and fillers are similarly applicable to the paper according to the invention.

[0083] A preferred feature of the paper according to the invention is that the paper contains 10% to 50% by weight of filler relative to the total weight of the paper.

[0084] Preferably, the filler is a mixture of mechanically and / or chemically treated laitance and titanium dioxide, wherein the mixing ratio of the mechanically and / or chemically treated laitance to titanium dioxide is from 40 wt%:60 wt% to 60 wt%:40 wt%.

[0085] A suitable mixing ratio of mechanically and / or chemically treated laitance with titanium dioxide is, for example, 50 wt%:50 wt% or 56 wt%:44 wt%.

[0086] A preferred feature of the paper according to the invention is that the paper has an ash content of 10% to 50% by weight relative to the total weight of the paper.

[0087] A preferred feature of the paper according to the invention is that the paper has an ash retention rate of at least 75% when the ash content is between 39% and 42% and / or an ash retention rate of at least 85% when the ash content is between 34% and 37.5% and / or an ash retention rate of at least 85% or 87% when the ash content is between 29% and 32%.

[0088] Ash retention rate (AR) is calculated as follows:

[0089]

[0090] StWG stands for Substance-Water Mixture.

[0091] (TiO2) powder refers to "fresh" titanium dioxide.

[0092] (TiO2) refers to the total amount of titanium dioxide in paper.

[0093] (TiO2)StWG refers to the total amount of titanium dioxide in a substance-water mixture.

[0094] C (TiO2 in the slurry) refers to the proportion of titanium dioxide in the slurry.

[0095] The paper according to the invention is preferably characterized in that it has an opacity of at least 80%, at least 90%, at least 91%, at least 92%, at least 93%, and at most 99%.

[0096] The opacity is determined as follows.

[0097] First, impregnate the paper with melamine resin, dry it, and then press each sheet of paper onto a white and black background.

[0098] Then, the paper on the plate was measured using a spectrophotometer “Datacolor Spectraflash 800V”.

[0099] In each case, determine the average of the three measurements. Remove outliers before calculating the average.

[0100] CIELAB L, a, and b values ​​were measured against white and black backgrounds (sandwiches).

[0101] Opacity is determined by specific black and white y-values.

[0102] Opacity = (Y black / Y white) * 100%

[0103] These values ​​are calculated automatically by the program on the colorimeter.

[0104] A preferred feature of the paper according to the invention is that the paper has a breaking load of at least 15 N / 15 mm width, preferably at least 20 N / 15 mm width.

[0105] The breaking load was determined by the following method. First, the paper strip (15mm wide) was clamped and straightened so that it did not touch the measuring surface.

[0106] The tensile test begins in automatic mode and waits for tearing. The determined value can be read on the instrument. A suitable measuring instrument is, for example, the "Horizontal Strength Tester K465" from Messimer & Büchel.

[0107] A preferred feature of the paper according to the invention is that the paper has a wet breaking load of at least 5 N / 15 mm width, preferably at least 6 N / 15 mm width.

[0108] The wet breaking load was determined according to the following method: The paper was post-cured in a drying oven at approximately 105°C for about 3 minutes. Then, a strip of paper (15 mm wide) was placed in water in a water container for about 10 seconds or according to the appropriate quality specifications. Excess water was drained.

[0109] The paper strip (15 mm wide) is then clamped and straightened so that it does not touch the measuring surface. The tensile test begins in automatic mode and waits for the tear to occur. The determined value can be read on the instrument. A suitable measuring instrument is, for example, the "Horizontal Strength Tester K465" from Messier & Büchel.

[0110] The present invention also relates to the use of the paper defined above as decorative paper.

[0111] The definitions and preferred embodiments of the methods, fillers, and paper described above are similarly applicable to the use of the paper according to the invention.

[0112] Decorative paper is typically a special type of paper used for surface finishing (e.g., on engineered wood panels). Known decorative papers are primarily produced from hardwood chemical pulp. These papers can be used plain or printed with various patterns. For example, they are used on furniture surfaces, flooring, and panels.

[0113] The invention will now be explained in more detail with reference to some non-limiting embodiments.

[0114] Specific implementation form

[0115] Example 1

[0116] Different types of paper were produced using untreated and treated pulp, and the results were analyzed. The results are summarized in Tables 1 to 3 below.

[0117] The pulp comes from a conventional paper machine and is processed as follows.

[0118] The TiO2 content in the laitance was 2.7% by weight. The laitance was simultaneously shear-mixed and stabilized with an anionic dispersant (Topsperse GX N from COATEX) at a ratio of 0.8% by weight (absolutely dry / absolutely dry) relative to the TiO2 content. Shearing was performed over 30 seconds at a frequency of 250 Hz using an "Ultra Turrax CAT X1740". The mass of the treated laitance portion was 300 g.

[0119] The paper studied has the following key data:

[0120] FLG[gsm]:80

[0121] Mass (pages), g: 2.51

[0122] Water volume per can, in grams: 2000

[0123] Each can of chemical pulp, grams: 50

[0124] Opacity, %: 90-93

[0125] Ash content (at 900 degrees Celsius), %: 29-42

[0126] Ash retention rate, %: 74-91

[0127] Table 1:

[0128]

[0129] Table 2:

[0130]

[0131] Table 3:

[0132]

[0133] StWG: Substance-Water Mixture

[0134] ΔL: Brightness difference

[0135] EKA: Trade name for retention aid EKA NP

[0136] Opacity: The degree to which light is not transmitted.

[0137] Formation: Spatial distribution of fibers and fillers in the paper web

[0138] Ash retention rate is calculated using the following formula:

[0139]

[0140] In addition, the energy-saving potential of "fresh titanium dioxide" was analyzed.

[0141] The results are shown in Table 4 below:

[0142] Table 4:

[0143]

[0144] STD: Existing Technology

[0145] Wet opacity: The opacity of impregnated and pressed paper, as defined in the instructions above.

[0146] The paper defined in Tables 1 through 3 was analyzed, and the actual and target (potential) consumption was inferred. Table 4 summarizes the corresponding values.

[0147] Example 2:

[0148] Produce three sheets of paper according to Table 5 below and check the efficiency of possible color position shifts.

[0149] Table 5:

[0150]

[0151] ΔE: Color difference (according to the CIELab color space). Color difference can be calculated using the following formula (in automatic mode).

[0152]

[0153] Color measurements were performed on paper N1 and N2 after deducting 20%, and the resulting color difference remained within tolerance.

[0154] The results are as follows Figure 1 As shown.

[0155] Example 3:

[0156] The breaking load and wet breaking load of different papers were tested. The results are summarized in Table 6. The paper according to the present invention has higher breaking load and wet breaking load.

[0157] Table 6:

[0158]

[0159] mA, gsm: surface weight

[0160] Wet breaking load, N / 15mm strip: Static strength under wet conditions

[0161] Breaking load, N / 15mm strip: static strength

[0162] The breaking load and wet breaking load were measured as defined in the specification.

[0163] Example 4:

[0164] Some papers were examined using a scanning electron microscope. The results are as follows: Figures 3 to 6 As shown. In each case, screenshots at different magnifications are displayed.

[0165] Figure 2 The existing technology consists of 50% by weight TiO2, 50% by weight untreated laitance, 40% by weight ash, and 80 gsm.

[0166] Figure 3 V1 50 wt% TiO2, 50 wt% treated slurry, 0.1 wt% absolutely dry dispersant, relative to absolutely dry titanium dioxide in the slurry (30 s-250 Hz-batch), 40 wt% ash, 80 gsm

[0167] Figure 4 V2 50 wt% TiO2, 50 wt% treated slurry, 0.4 wt% absolutely dry dispersant, relative to absolutely dry titanium dioxide in the slurry (30 s-250 Hz-batch), 40 wt% ash, 80 gsm

[0168] Figure 5 V3 50 wt% TiO2, 50 wt% treated slurry, 0.8 wt% absolutely dry dispersant, relative to absolutely dry titanium dioxide in the slurry (30 s-250 Hz-batch), 40 wt% ash, 80 gsm

[0169] exist Figure 2In this process, a closed surface and numerous titanium dioxide aggregates are visible. Individual pigment particles, which have a major influence on good opacity, are barely visible. In this case, the slurry is either not treated in any way or is used in its natural state.

[0170] Figure 3 Scanning electron microscope images of paper produced from treated pulp are shown. Treatment was performed using an UltraTurrax rotor at a frequency of 250 Hz and a treatment time of 30 seconds, with the addition of 0.1 wt% absolutely dry anionic dispersant (Topsperse GX N from COATEX). It can be seen that although the number of titanium dioxide aggregates is reduced and individual particles are detectable, the surface remains relatively closed.

[0171] Figure 4 Scanning electron microscope images of paper produced from treated pulp are shown. Treatment was performed using an UltraTurrax rotor at a frequency of 250 Hz and a treatment time of 30 seconds, with the addition of 0.4 wt% absolutely dry anionic dispersant (Topsperse GX N from COATEX). The surface becomes more porous, which is highly advantageous for decorative paper. The chemical pulp fibers are better and more completely covered by individual titanium dioxide particles, and the individual particles are clearly and distinctly documented.

[0172] Figure 5 Scanning electron microscope images of paper produced from treated pulp are shown. Treatment was performed using an UltraTurrax rotor at a frequency of 250 Hz, a treatment time of 30 seconds, and with the addition of 0.8 wt% absolutely dry anionic dispersant (Topsperse GX N from COATEX). The surface is porous, which is highly advantageous for decorative paper. The pulp fibers are almost completely covered by individual titanium dioxide particles, and individual particles are clearly and distinctly documented. Aggregates of titanium dioxide are barely visible.

[0173] Example 5:

[0174] A system or prototype for the mechanical and chemical treatment of slurry is installed on a paper machine within the Hydromix TiO2 recovery unit production line. A schematic diagram of the production unit is shown below. Figure 6 As shown.

[0175] The two units (1) are installed in parallel in the pipeline (2) to handle the entire volumetric flow rate. The dispersant is dispensed by a container called the batching station (4) using a batching pump (5). The control of aggregates or the generation of shear force is controlled by a frequency controller (3). The volumetric flow rate of the slurry is continuously monitored, and the dosage of the dispersant is adjusted accordingly. The total volumetric flow rate of the slurry can be distributed and guided by a control valve (6).

[0176] (1) - ShearMaster or unit used to generate shear force

[0177] (2) - Floating slurry pipeline

[0178] (3) Motor control

[0179] (4) Dispersant batching station

[0180] (5) Dispersant mixing pump

[0181] (6) - Control valve / flood flow division (if required).

Claims

1. A method for producing a filler for paper, comprising the steps of: - providing a float from a paper recycling process, wherein the float contains titanium dioxide, - subjecting the float to a mechanical treatment or a mechanical and chemical treatment, and - mixing the mechanically treated or mechanically and chemically treated float with titanium dioxide, wherein the mechanical treatment of the float comprises the use of shear forces.

2. The method of claim 1, wherein, The float is obtained by feeding compressed air and adding a flocculating agent.

3. The method of claim 1, wherein, The chemical treatment of the float comprises incubating the float with a dispersing agent.

4. The method of claim 3, wherein, The dispersing agent is an anionic dispersing agent.

5. The method of claim 1, wherein, The float from the paper recycling process contains 0.5 to 5 wt.% of titanium dioxide.

6. The method of claim 1, wherein, The float from the paper recycling process comprises titanium dioxide with an average particle size of more than 2 pm.

7. The method of claim 1, wherein, The mechanically treated or mechanically and chemically treated float comprises titanium dioxide with an average particle size D50 of 300 to 400 nm.

8. The method of claim 1, wherein, The mixing ratio of the mechanically treated or mechanically and chemically treated float to titanium dioxide is 40 wt.% : 60 wt.% to 60 wt.% : 40 wt.%.

9. The method according to any one of claims 1 to 8, characterized in that, The method is integrated in a paper making device.

10. A filler for paper, obtainable by the method of any one of claims 1 to 9.

11. A paper comprising the filler of claim 10.

12. The paper according to claim 11, characterized in that, The paper contains 10 to 50 wt.% of the filler relative to the total mass of the paper.

13. The paper according to claim 11, wherein, The paper comprises an ash content of 10 to 50 wt.% relative to the total mass of the paper.

14. The paper according to any one of claims 11 to 13, characterized in that, The paper has an opacity of at least 80%.

15. Use of the paper according to any one of claims 11 to 14 as a decorative paper.

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