JP2010507553A - Method for preparing high-strength paper - Google Patents

Abstract

The present invention provides a method for preparing an aqueous composition comprising mineral particles coated with polysilicate comprising subjecting an aqueous composition comprising a gel-like polysilicate and mineral to shearing at least 5000 rpm for at least 30 seconds. The invention also provides polysilicate-coated mineral particles obtained by this method and paper filled with these particles.

Description

  The present invention relates to polysilicate-coated mineral particles suitable as paper fillers, aqueous compositions containing these particles, methods for preparing these aqueous compositions, papers filled with these particles and methods for preparing filled paper .

  In general, fillers (usually mineral substances) are included in the paper to reduce the amount of fibers and thereby reduce costs. However, usually as the amount of filler increases, the strength of the paper decreases.

  For this reason, there is a current need for paper having high filler content and at the same time favorable paper strength.

  U.S. Pat. No. 6,623,555 describes a method for producing a composite pigment of precipitated calcium carbonate and a silicon compound, for example used as a papermaking filler or as a coating pigment. The method includes the steps of introducing a soluble silicate compound into an aqueous medium containing a calcium carbonate precipitate and precipitating an insoluble silicon compound onto the precipitated calcium carbonate by carbonation of the reaction mixture. The temperature of the reaction mixture during the precipitation of the silicon compound on the precipitated calcium carbonate is at least 50 ° C. The resulting aqueous composition containing the formed composite pigment has a low viscosity. A disadvantage of the composite pigment of US Pat. No. 6,623,555 is that when it is used as a filler, it produces a low strength filled paper.

  W000 / 26305 describes a method for preparing an aqueous composition containing partially silica-coated calcium carbonate particles suitable as a paper filler. This method comprises the steps of mixing calcium carbonate with about 3.5% by weight of soluble silicate based on the weight of calcium carbonate, and reacting the silicate gradually at room temperature without adjusting the pH, thereby providing an insoluble silica coating. Forming a process. The disadvantage of this method is that the reaction time is very long, for example, 50 hours, which makes it technically impractical from an industrial point of view. In addition, the amount of silica in the silica-coated filler is very small, and the silica-coated filler yields paper that is as strong as standard calcium carbonate-filled paper.

WO 95/03251 describes a method for preparing a mixed pigment of calcium carbonate and silica useful as a paper filler. This method comprises the steps of mixing lime milk and aqueous sodium silicate solution, raising the temperature of the mixture to 55-170 ° C., and then supplying carbon dioxide to the mixture until the pH of the mixture is 7 or less, thereby Precipitating a mixed pigment comprising calcium carbonate and silica. The ratio of silica / CaO is 3.6 / 1. Therefore, the ratio of silica / CaCO _{3 in} the obtained mixed pigment is 2/1 (or 66/33), which is very high.

  EP356406A1 describes a method for preparing calcium carbonate particles having an acid resistant coating, in which a slurry of calcium carbonate particles is a solution of zinc compound and silica containing material at a temperature of 70-95 ° C. and a pH of 8-11. Are mixed at the same time.

  U.S. Pat. No. 5,164,006 describes a method for preparing acid-resistant calcium carbonate pigments, which comprises mixing a sodium silicate solution with a calcium carbonate slurry at 75-80 ° C., adding carbon dioxide. The step of adjusting the pH to 10.2 to 10.7, the step of cooling the reaction mixture, and the step of adding zinc chloride.

  A disadvantage of the methods of EP356406A1 and US Pat. No. 5,164,006 is that these methods include an additional step of adding a zinc compound.

  It is an object of the present invention to provide a filled paper or paperboard having an improved dry strength, in particular improved tensile strength and internal bond strength, relative to the amount of filler.

  This object is solved by the method of claim 1, the composition of claim 9, the mineral particles coated with the polysilicate of claim 15, the paper of claim 16, and the method of claim 17.

  Part of the present invention is a method of preparing an aqueous composition comprising mineral particles coated with polysilicate, wherein the method comprises shearing an aqueous composition comprising gelled polysilicate and mineral at least 5000 rpm for at least 30 seconds. Including the step of attaching.

  The aqueous composition comprising the gelled polysilicate and the mineral is preferably subjected to a shear of at least 8,000 rpm, more preferably a shear in the range of 10,000 to 30,000 rpm. Preferably, the shear is applied for at least 1 minute. Shearing may be applied at any time. However, for practical reasons, shear is usually applied for up to 1 hour, preferably up to 30 minutes, more preferably up to 15 minutes.

  An aqueous composition comprising mineral particles coated with polysilicate preferably has a viscosity of at least 500 mPas (using a Brookfield viscometer with spindle 4 at 25 ° C., 100 rpm, 12 dry weight% based on the weight of the composition). Measured with mineral particles coated with a concentration of polysilicate and the results are characterized by those measured 30 seconds after the start of the test.

  The aqueous composition containing the gel-like polysilicate and the mineral can be preferably obtained by polymerization of the silicate in the presence of the mineral.

Usually, the silicate is water soluble. Preferably, the silicate is an alkaline earth metal silicate such as magnesium silicate or an alkali metal silicate such as lithium silicate, potassium silicate or sodium silicate. More preferred are alkali metal silicates; most preferred is sodium silicate. Preferred sodium silicates have a weight ratio of Na ₂ O to SiO ₂ in the range of 2: 1 to 1: 4, more preferably in the range of 1: 2 to 1: 4, most preferably 1: 2.5 to 1. : It is the range of 3.5. Preferably, the silicate is used in the form of an aqueous solution.

  Examples of minerals are titanium dioxide, trihydrated alumina, talc, mica, zeolite, clays such as kaolin and calcined clay, metal silicates such as precipitated silicates, and heavy calcium carbonate (GCC) and precipitated Calcium carbonate such as calcium carbonate (PCC). A preferred mineral is calcium carbonate. Minerals are typically not substantially water soluble under polymerization conditions. The mineral can be used in solid form or as an aqueous slurry.

  The mineral can be already present at the beginning of the silicate polymerization or can be added during the polymerization of the silicate.

  Gelation occurs during the polymerization of the silicate. Preferably, the polymerization of the silicate is carried out with stirring. When the polymerization and the resulting gelation are substantially complete, the stirring intensity is preferably increased to a relatively low viscosity, for example, less than 300 mPas (using a Brookfield viscometer with spindle 4 at 25 ° C., 100 rpm, The results are measured with mineral particles coated with a polysilicate at a concentration of 12% by dry weight based on the weight of the composition, the results being measured 30 seconds after the start of the test) gelled polysilicate and mineral containing mineral A composition is obtained.

  Silicate polymerization can be initiated by adjusting the pH to less than 10 by adding acid. Examples of acids are carbon dioxide, mineral acids such as hydrochloric acid or sulfuric acid, organic acids such as acetic acid and alkali metal borates, aluminates or stannates. Preferably carbon dioxide or mineral acid is used as the acid.

  In a first embodiment of the process, wherein the mineral is already present at the beginning of the polymerization, the polymerization of the silicate is preferably initiated using carbon dioxide and the pH is preferably between pH 5-9. The range is more preferably adjusted to about 7.

  In a second embodiment of the process, wherein the mineral is added during the polymerization of the silicate, the polymerization of the silicate is preferably initiated with a mineral acid, the pH is preferably in the range of pH 2 to 10.5, More preferably, it is adjusted to 7-9. In a second embodiment of the method, if a mineral is used, it is a mineral that can be dissolved at an acidic pH, such as calcium carbonate, preferably the pH is adjusted to a range of pH 8.5-10.

  Preferably, in both embodiments, the polymerization of the silicate is carried out at a temperature below 50 ° C. More preferably, it is carried out at a temperature in the range of 15 to 35 ° C. Most preferably, it is carried out at a temperature in the range of 20-30 ° C.

  Usually, the polymerization of the silicate is substantially completed within 12 hours after the start of the polymerization. Preferably, it is completed within 5 hours, more preferably within 2 hours, and most preferably within 1 hour.

  The amount of the mineral is preferably in the range of 5 to 20% by weight, more preferably 8 to 12% by weight, based on the weight of the aqueous composition containing the gel-like polysilicate and the mineral.

  The amount of silicate is preferably 0.01 to 10% by weight, more preferably 0.5 to 4% by weight, more preferably 1 to 3% by weight, based on the weight of the aqueous composition containing the gelled polysilicate and the mineral. Range.

  Preferably, the amount of gel-like polysilicate and mineral is 1-30 dry weight percent, more preferably 5-15 dry weight percent, most preferably 10 based on the weight of the aqueous composition comprising the gel-like polysilicate and mineral. It is in the range of -14 dry weight percent.

  Also part of the invention is an aqueous composition comprising mineral particles coated with polysilicate, which can be obtained by the method of the invention.

  Preferably, the aqueous composition comprising polysilicate-coated mineral particles is at least 500 mPas (using a Brookfield viscometer with spindle 4 at 25 ° C., 100 rpm, 12 dry weight percent concentration based on the weight of the composition). This is the case when measured with silicate-coated mineral particles, and the results are characterized by a viscosity of 30) after the start of the test.

  Preferably, the polysilicate coated mineral particles are not completely coated with polysilicate. For example, polysilicate coated calcium carbonate dissolves below pH 6.

  The amount of mineral can be 40-99% by weight, based on the weight of the mineral particles coated with the polysilicate. Preferably, it is 60 to 95% by weight, more preferably 80 to 90% by weight, and most preferably 78 to 88% by weight.

  The amount of polysilicate can be 1-60% by weight based on the weight of the mineral; preferably 5-40% by weight, more preferably 15-25% by weight.

  The particle size of the mineral particles coated with polysilicate is 1-1000 μm, preferably 8-30 μm, more preferably 10-27 μm.

  Preferably, the amount of polysilicate coated mineral particles is 1 to 30% by weight, based on the weight of the aqueous composition comprising the polysilicate coated mineral particles. More preferably, it is 10 to 15% by weight.

  Also part of the invention are polysilicate coated mineral particles obtained by removing water from the aqueous composition of the invention. Water removal can be done by any suitable method or combination of any suitable methods, such as filtration, decantation or distillation.

  Another part of the present invention is paper or paperboard filled with mineral particles coated with the polysilicate of the present invention.

  Preferably, the weight ratio of fiber / polysilicate coated mineral particles in the filled paper or filled paperboard is in the range of 90 / 10-30 / 70, preferably in the range of 80 / 20-60 / 40, more preferably 75. / 25 to 65/35.

  Another part of the present invention is a method for preparing the filled paper or filled paperboard of the present invention, in which the cellulose suspension is filtered onto a wire (punch net) formed with a mesh, and then the mesh. Prior to the step of drying the aqueous solution comprising adding polysilicate coated mineral particles or polysilicate coated mineral particles to the cellulosic suspension.

  Preferably, a filled paper is prepared.

  The polysilicate coated mineral particles of the present invention can be used in conjunction with standard wet end additives such as cationic coagulants, drying tougheners, retention agents, sizing agents and optical brighteners. Although not particularly preferred, it can also be used with other fillers such as calcium carbonate.

  Mineral particles coated with polysilicate can also be added to thick stock, thin stock or white water.

  Further part of the invention is a method for improving the tensile strength and internal bond strength of a filled paper or filled paperboard relative to the basis weight of the filled paper or filled paperboard. This method comprises an aqueous composition comprising mineral particles coated with polysilicate or mineral particles coated with polysilicate prior to the step of draining the cellulose suspension onto the meshed wire and then drying the mesh. Adding to the cellulosic suspension.

  When the mineral particles coated with the polysilicate of the present invention are used as a filler for paper, the ratio of tensile strength (breaking length) and internal bond strength (Scott bond strength) / ash content of the filled paper is improved. Has the advantage of. In other words, when a polysilicate-coated mineral is used as a filler, a filler paper with improved tensile strength and internal bond strength for a certain ash content, or for a certain tensile strength or internal bond strength, Either filled paper with low ash content can be obtained. At the same time, the paper exhibits excellent texture and excellent opacity.

FIG. 1 shows a handsheet containing Calopake® F, a handsheet containing Calopake® F and polysilicate, and a handsheet containing Calopake® F coated with polysilicate. The correlation between paper break length and handsheet ash content is shown.

FIG. 2 shows the tear lengths of handsheets containing Albacar® HO, Albacar® LO, Syncarb F0474 and Miconapaque HB, respectively, and handsheets containing each calcium carbonate coated with polysilicate. The correlation with the ash content of handsheets is shown.

FIG. 3 shows a handsheet containing Calopake® F, a handsheet containing Calopake® F and polysilicate, and a handsheet paper containing Calopake® F coated with polysilicate. The correlation between bond strength and handsheet paper ash content is shown.

FIG. 4 shows the Scott Bond strength and strength of handsheets containing Albacar® HO, Albacar® LO, Syncarb F0474 and Miconapaque HB, respectively, and each calcium carbonate coated with polysilicate. The correlation with the ash content of handsheets is shown.

Examples 1-5
Preparation of aqueous composition containing calcium carbonate particles coated with polysilicate using carbon dioxide as acid

A 100 g calcium carbonate oven dry weight (see Table 1) was taken and diluted to 930 g with deionized water. To this was added 70 g of sodium silicate (28.5% (w / v) SiO ₂ , 8.9% (w / v) Na ₂ O). Thus, the amount of calcium carbonate was 10% dry weight based on the volume of the reaction mixture and the amount of sodium silicate was 2% dry weight based on the volume of the reaction mixture. The two aqueous materials were mixed thoroughly at room temperature using a magnetic stirrer, and carbon dioxide was added using a gas diffusion tube to bring the pH to 7.0 at room temperature. In some cases, the pH did not reach 7 until the polysilicate gelled. The reaction mixture was allowed to gel at room temperature. Twenty minutes after gelation was almost complete, the gel was broken by the action of a magnetic stirrer to give a slurry containing visible particles (> 2 mm). This slurry was then sheared for 1 minute at 13500 rpm using an ultra thurrax homogenizer. The resulting aqueous composition contained calcium carbonate coated with 12% by dry weight polysilicate based on the amount of the composition.

  The calcium carbonate used is listed in Table 1 along with its particle size and the resulting polysilicate coated calcium carbonate particles. The particle size was analyzed with a Malvern MasterSizer 2000 particle size analyzer.

  Calopake® F is dry precipitated calcium carbonate, Albacar® HO, Albacar® LO and Syncarb F0474-GO are diffusion precipitated calcium carbonate, and Miconapaque HB is diffusion ground calcium carbonate. Calopake (R) F, Albacar (R) HO and Albacar (R) LO are sold by Mineral Technologies and Miconapaque HB is sold by Columbia River Carbonates.

  Aqueous compositions containing calcium carbonate coated with the polysilicates of Examples 1, 4 and 5 were measured using a Brookfield DVII-Pro viscometer, and the results were obtained 30 seconds after the start of the test.

  When an aqueous composition comprising calcium carbonate coated with the polysilicate of Examples 1-5 was to be acidified with hydrochloric acid to a pH of about 1.5, the calcium carbonate was rapidly removed before the pH reached 6. Dissolved and showed that the silica surface was not a perfect coating that would be a barrier to acid.

Comparative Example 1 Preparation of aqueous composition containing polysilicate

  An aqueous composition containing no calcium carbonate and containing only polysilicate was prepared in the same manner as in Examples 1 to 5 except that calcium carbonate was not added. The amount of sodium silicate was again 2% by weight, based on the volume of the reaction mixture. The resulting aqueous composition contained 2% by dry weight polysilicate based on the amount of the composition.

Examples 6-10
Preparation of handsheets containing calcium carbonate coated with polysilicate

  Handsheets containing silica-coated calcium carbonate were prepared as follows: containing 0.5% dry weight fiber (70% bleached cocoon fiber and 30% bleached vine fiber) based on the weight of the stock A standard laboratory fine paper stock was beaten to 47 ° SR. The stock was stirred at 1000 rpm for 5 seconds. An aqueous solution containing 0.5% (w / v) Raisamy® 50021 (cationic potato starch) was added to obtain Raisamy® 50021 at a concentration of 5 kg / t based on the dry weight of the finished paper. Stirring at 1000 rpm was continued for 30 seconds. The required amount of aqueous composition containing calcium carbonate particles coated with the polysilicates of Examples 1-5 (see Table 2) was added and stirring at 1000 rpm was continued for another 30 seconds. An aqueous solution containing 0.1% (w / v) Percol 175 (cationic polyacrylamide) was added to obtain Percol 175 having a concentration of 500 g / t based on the dry weight of the finished paper, and further at 1000 rpm for 30 seconds. Stirring was continued. Add an aqueous solution containing 0.1% (w / v) Hydrocol 2D6 (water swellable montmorillonite clay) to obtain 2000 g / t Hydrocol 2D5 based on the dry weight of the finished paper and stir at 500 rpm for 15 seconds Continued. The treated stock was formed into handsheets using a semi-automatic handsheet, pressed and dried at 95 ° C.

  The order of addition for the preparation of handsheets of Examples 6-10 is summarized in the following diagram 1:

Comparative Examples 2-8
Preparation of handsheets containing calcium carbonate but not polysilicate coated calcium carbonate

Comparative handsheets were prepared as described for the handsheets of Examples 6-10, but no calcium carbonate coated with polysilicate was added. Instead, each calcium carbonate was added before adding the starch. The order of addition for the preparation of handsheets of Comparative Examples 2-8 is summarized in the following diagram 2:

Comparative Example 9
Preparation of handsheets containing calcium carbonate and polysilicate, but not containing calcium carbonate coated with polysilicate

The handsheets of Comparative Example 9 were prepared as described for the handsheets of Examples 6-10, except that the polysilicate of Comparative Example 2 was used instead of the calcium carbonate coated with polysilicate. In addition, each calcium carbonate was added before the starch was added. The order of addition for the preparation of the handsheets of Comparative Example 9 is summarized in the following diagram 3:

Table 2 summarizes the weight ratios of the fibers used in the handsheets of Examples 6-10 and Comparative Examples 2-9, silica-coated calcium carbonate, calcium carbonate, and polysilicate.

Evaluation of handsheets of Examples 6-10 and Comparative Examples 2-9 Handsheet paper samples of Examples 6-10 and Comparative Examples 3-9 were at least 24 hours at 50% relative humidity and 23 ° C. according to Tappi test method T402. Put in condition.

  The basis weight is a function of weight and handsheet area and was calculated from the handsheet weight. Ash content was measured using a CEM microwave oven at a temperature of 525 ° C. A strip of 2 × 15 mm was taken from each handsheet, and the tensile strength (breaking length) was tested according to Tappi T494 using an EJA single column tensile tester. The internal bond strength (Scott bond strength) was measured with a Scott bond measuring instrument according to Tappi test method T569.

  The results of the handsheets of Comparative Examples 2 to 4 indicate that the breakage length and the Scott bond strength increase as the fiber content increases and the calcium carbonate content decreases. When part of the fiber was replaced with polysilicate while maintaining the amount of calcium carbonate, the tear length (see results of handsheets in Comparative Examples 4 and 9) increased.

  The correlation between the tear length and ash content of the handsheets of Example 6 and Comparative Examples 2 to 4 and 9 is shown in FIG.

  The correlation between the tear length and ash content of the handsheets of Example 6 and Comparative Example 9 is considered to behave similarly to the correlation shown for the tear length and ash content of the handsheets of Comparative Examples 2-4. . This means that a virtual line can be drawn from the point of Example 6 to the point of Comparative Example 9. This line is parallel to the line formed by the points of Comparative Examples 2-4. By doing so, a handsheet containing Calopake® F coated with polysilicate at a certain ash content (Example 6) is a handsheet containing only Calopake® F (Comparative Example). 2-4) It is also clear that a high tear length can be achieved compared to handsheets (Comparative Example 9) containing a mixture of Calopake® F and polysilicate. In other words, a handsheet containing Calopake® F coated with polysilicate contains a handsheet containing only Calopake® F and a mixture of Calopake® F and polysilicate. Compared to handsheets, the same tear length can be achieved with less ash.

  FIG. 2 shows the correlation between tear length and ash content for the handsheets of Examples 7 to 10 and Comparative Examples 5 to 8.

  FIG. 2 shows Albacar® HO (Example 7), Albacar® LO (Example 8), Syncarb F0474 (Example 9), Miconapaque HB coated with polysilicate at constant ash. Each handsheet containing (Example 10) achieves a higher tear length compared to each handsheet containing calcium carbonate (Comparative Examples 5-8) that is not coated with polysilicate. Show that you can. In other words, handsheets containing Albacar® HO, Albacar® LO, Syncarb F0474, Miconapaque HB, respectively, coated with polysilicate, are each calcium carbonate not coated with polysilicate. The same tear length can be achieved with less ash compared to handsheets containing.

  FIG. 3 shows the correlation between the Scott bond strength and ash content of the handsheets of Example 6 and Comparative Examples 2 to 4 and 9, and FIG. 3 shows the Scott bond strength and ash content of the handsheets of Examples 7 to 10 and Comparative Examples 5 to 8. FIG. 4 shows the correlation. Here, the correlation between the Scott bond strength of the handsheets of Examples 6 to 10 and Comparative Examples 5 to 9 and the ash content is also the correlation between the Scott bond strength and the ash content shown for the handsheets of Comparative Examples 2 to 4. It can be assumed that it behaves like a relationship. This also means that an imaginary line can be drawn through each example point, which is parallel to the line formed by the points of Comparative Examples 2-4. Comparing the parallel lines, the correlation between the Scott bond strength and the ash content is as follows: handsheets containing only Calopake® F (Comparative Examples 2 to 4) and Calopake® F and polysilicate The handsheets containing the mixture (Comparative Example 9) are found to be nearly identical, but for certain ash content, polysilicate coated Calopake® F (Example 6), Albacar® ) Handsheets containing HO (Example 7), Albacar® LO (Example 8), Syncarb F0474 (Example 9), Miconapaque HB (Example 10), respectively, are coated with polysilicate. It can be seen that a higher Scott bond strength can be obtained as compared with handsheets containing no calcium carbonate (Comparative Examples 5 to 8). In other words, handsheets containing calcium carbonate coated with polysilicate have the same Scott bond strength with less ash compared to handsheets containing only calcium carbonate or a mixture of calcium carbonate and polysilicate. Can be achieved.

  In summary, using polysilicate coated calcium carbonate, paper with increased tear length and Scott bond strength at the same ash, or paper with less ash content at the same tear length or Scott bond strength, i.e. fiber And / or a paper with a reduced amount of calcium carbonate is obtained. Thus, the tear length / ash ratio of the filled paper and the Scott bond strength / ash ratio of the filled paper are improved.

Example 11
Preparation of compositions containing calcium carbonate coated with aqueous polysilicate using sulfuric acid as acid

200 liters of water (standard tap water), 21 liters of sodium silicate (N (registered trademark) sodium silicate sold by PQ, 28.7% (w / v) SiO ₂ , 8.9% (w / v) Na ₂ O, concentration at 68 ° F .: 1.38 g / cm ³ ) was added. After obtaining a homogeneous mixture by stirring, a sufficient amount of concentrated sulfuric acid was added, and the pH of sodium silicate was lowered to 11.3-9.5 at room temperature. After reacting for 3 minutes with sodium silicate, 50 L of diffused heavy calcium carbonate (GCC) slurry (Hyrocarl® 90, 60 wt% GCC sold by Omya) was added. When calcium carbonate was mixed well into the slurry and 29L of water was added, the silicate began to form a solid three-dimensional matrix. The solid gel was broken by the action of a stirrer and the mixture was stirred for a further 2 hours. After this, a granular slurry having visible particles in the range of 0.5-2 mm was obtained. A 10 L sample of this material was taken and sheared at 14,000 rpm for 10 minutes using a Polytron Emulsifier to obtain calcium carbonate coated with an aqueous polysilicate having a uniform viscosity. The polysilicate-coated calcium carbonate is now ready for use.

Claims (19)

A method for preparing an aqueous composition comprising mineral particles coated with a polysilicate comprising subjecting an aqueous composition comprising a gel-like polysilicate and a mineral to shearing at least 5000 rpm for at least 30 seconds. The process according to claim 1, wherein the aqueous composition comprising the gel-like polysilicate and the mineral is obtained by polymerization of the silicate in the presence of the mineral. The process of claim 2, wherein the polymerization of the silicate is initiated by adjusting the pH to less than 10 by adding an acid. The process according to any one of claims 2 to 3, wherein the polymerization of the silicate is carried out at a temperature below 50C. The process of any one of claims 2 to 4, wherein the polymerization of the silicate is substantially completed within 12 hours. The method according to any one of claims 2 to 5, wherein the amount of the mineral is in the range of 5 to 20% by weight, based on the weight of the aqueous composition containing the gel-like polysilicate and the mineral. The method according to any one of claims 2 to 6, wherein the amount of silicate is in the range of 0.01 to 10% by weight, based on the weight of the aqueous composition comprising gelled polysilicate and mineral. The method according to any one of claims 2 to 7, wherein the amount of the gel-like polysilicate and the mineral is in the range of 1 to 30% by dry weight based on the weight of the aqueous composition containing the gel-like polysilicate and the mineral. . An aqueous composition comprising mineral particles coated with polysilicate, obtained by the method according to claim 1. At least 500 mPas (measured using a Brookfield viscometer with spindle 4 at 25 ° C. and 100 rpm with mineral particles coated with polysilicate at a concentration of 12% by dry weight based on the weight of the composition; The aqueous composition according to claim 9, characterized by a viscosity of (measured 30 seconds after the start of the test). 11. An aqueous composition according to claim 9 or 10, wherein the amount of mineral is 40-99% by weight, based on the weight of the polysilicate coated mineral particles. The aqueous composition according to any one of claims 9 to 11, wherein the amount of polysilicate is 1 to 60% by weight, based on the weight of the mineral. The aqueous composition according to any one of claims 9 to 12, wherein the particle size of the mineral particles coated with polysilicate is 1-1000 µm. The aqueous composition according to any one of claims 9 to 13, wherein the amount of mineral particles coated with polysilicate is 1 to 30% by weight, based on the weight of the aqueous composition. 15. Mineral particles coated with polysilicate obtained by removing water from the aqueous composition according to any one of claims 9-14. A paper or paperboard filled with mineral particles coated with the polysilicate according to claim 15. The cellulose suspension-coated mineral particles according to claim 15 or any one of claims 9-14 prior to the step of draining the cellulose suspension onto the wire on which the mesh is formed and then drying the mesh. 17. The method for preparing paper or paperboard of claim 16, comprising the step of adding an aqueous composition comprising polysilicate coated mineral particles to the cellulosic suspension. The mineral particles coated with the polysilicate according to claim 15 or the polysilicate according to any one of claims 9 to 14, prior to the step of draining the cellulose suspension onto the wire on which the mesh is formed and then drying the mesh. Improve the tensile strength and internal bond strength of the filled paper or paperboard relative to the basis weight of the filled paper or paperboard, comprising adding an aqueous composition comprising silicate-coated mineral particles to the cellulosic suspension. Method. Use of mineral particles coated with the polysilicate according to claim 15 as a filler for paper or paperboard.

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