TW581791B - High gloss calcium carbonate coating compositions and coated paper and paper board manufactured from same - Google Patents

Abstract

A paper coating pigment is provided which includes a blend of a first and a second discrete aragonitic precipitated calcium carbonate (PCC) particles. The first particles of the blended pigment have an average particle size (APS) of about 0.4 microns and the second particles of the blended pigment have an average particle size (APS) of about 0.5 microns. The blended pigment preferably includes a weight ratio of about 50:50 to about 80:20 with a 60:40 weight ratio being most preferred, respectively, of the first 0.4 micron particles to the second 0.5 micron particles. Also provided are a method for preparing coated paper, which includes preparing the blended aragonitic PCC pigment, adding a binder, and applying the pigment to the paper basestock in a slurry containing a binder and or additives. Preferably, blended aragonitic precipitated calcium carbonate pigment is present in an amount of from about 30 weight percent to about 85 weight percent of the mixture with about 70 weight percent to about 15 weight percent balance being clay prior to preparing the slurry.

Description

581791

The present invention relates to a mixture of calcium acid particles. MAN J3 range for producing carbon with high paper gloss coated paper

Bright background In the process of making paper, dish acid has excellent whiteness properties, so it is used for coating and application to improve the brightness of various properties. Both natural and synthetic acids are used in the paper industry. Natural carbon, or limestone, is ground before being used in paper, while synthetic carbon is produced by the Shen-Sheng reaction, called Shen Dian Suan Wu Wu (p C C). Shen Dian carbonated carbon dioxide is better than ground carbonic acid in papermaking because of its size, particle size distribution, particle size distribution, and purity can be controlled during manufacturing. Hold

When used in the paper industry, precipitated calcium carbonate is generally prepared by carbonation of carbon dioxide gas and chlorine-oxidized water-soluble slurry ("lime milk"). The precipitated calcium carbonate colorant is then coated on the paper with an aqueous slurry containing the precipitated calcium carbonate and an adhesive.

Linear calcium carbonate can be precipitated from three different crystalline forms from aqueous solutions: the vatice type of thermal instability, the most stable and most common calcite agent in nature, and the semi-stable at normal ambient temperature and pressure, but at high temperatures, it changes to vantete. Type of aragonite type. This type of aragonite has an orthorhombic shape and crystallizes into long thin needles that can be aggregated or not. This calcite pattern exists in several different shapes, the most common of which is the orthorhombic shape. Its crystals can be aggregated or unaggregated, and its scalenohedral shape crystals are generally not wonderful. All of these calcium carbonate forms can be prepared from lime milk by carbonation of the processing conditions known in the art. @ -4- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 581791

Although compared with kaolin clay containing flake particles, it has excellent whiteness and absorption of printing ink as a paper coating color, but the traditional carbonic acid m material will lack the gloss of the paper when it is coated. The use of a large amount of precipitated calcium carbonate in coating formulations, especially for single coating application operations, is due to insufficient gloss of higher kaolin-based formulations. Therefore, when the precipitated calcium carbonate particles are colored in the kaolin-based composition, the amount is not High, such as in an amount of about 25% by weight or less. Related Techniques Country X Patent No. 5,861,209 discloses aragonite precipitated calcium carbonate colorants for coating gravure printing paper, and a method for manufacturing the colorants. , Paper coated with the coating colorant, and method for preparing the paper. The comparative example of the precipitated calcium carbonate particles is from about 3: 1 to about 5: i, preferably from about 4: i to about 7: i 'and a variety of particle size distributions, which are preferably two or three styles. Preferably, the aragonite precipitated calcium carbonate accounts for about 20% to about 100% by weight of the coating pigment. The Colorants can be used in combination with titanium dioxide, talc, sintered clay, wrought white Plastic pigment, ternary aluminate, mica, or mixtures thereof J. Drechsel (1999 Coating Conference, ρρ · 413-432) in the literature nIn Search of Synergy:. Engineering Coatings for Maximum

Performance: Optimizing Pigment Blends for Maximum Performance, "Reveals the use of fine particle size kaolin and finely ground calcium carbonate in coatings to increase the print gloss of coated paper. L. Jarnstrom et al. Wochenblatt f. Papierfabrikation 17, 736-741, ( 1996), Structure of the Coating Layer and

Optical Properties of Coated Paper, reveals that when flaky kaolin is mixed with Shendian Carbonate I bow colorant for coating composition, higher opacity can be obtained. -5- This paper (standard) uses China National Standard (CNS) A4. Specifications (210X 297 mm) 581791 A7 B7___ 5. Description of the invention (3) and positive coordination effect. R. Knappich et al., PTS Coating Symposium (1999), pp. 13E to 13E-16, `` Optimized Binder Systems for Natural Calcium Carbonate Pigments with Narrow Particle Size Distribution, '' revealing natural milling with a smaller particle size distribution Shendian calcium carbonate pigment can achieve high brightness, high opacity, and excellent coverage on coated paper and cardboard. PG Drage et al. In the 1998 TAPPI Coating / Papermakers Conference, pp. 413-433 document `` Factors Governing Print Performance in Offset Printing of Matt Papers, '' discloses the use of two types of blending coarse and ultrafine components and GCC on the matte surface. When manufacturing matte pigments for low-gloss papers, the emphasis is on the coarse parts. Japanese Patent No. 10232253 discloses a multi-layer coated paper for screen printing, which has dry strength, white paper gloss, multi-color printing gloss, and resistance to bubble generation. The multilayer paper includes a coating layer with hollow or hemispherical polymer particles. Japanese Patent No. 10-340790 discloses a lithographic coated paper having a white paper gloss, which is a coating base liquid using a colorant component, which accounts for 40% to 100% by weight of the colorant component. Needle powder or columnar precipitated calcium carbonate. The Japanese Patent No. 1 1-0 6 5 7 0 3 discloses a lithographic coated paper having a printing gloss, containing mainly 60% by weight to 90% by weight of a spindle-type fishery alkali-precipitated calcium carbonate, and a Copolymer latex 'with an average particle diameter of 50 nm-80 nm and a coating layer of 30% to 50% by weight as a colorant for a glue. -6-This paper size applies Chinese national standards ((:; ^ 3) A4 size (210 X 297 mm) 581791 A7 B7 V. Description of the invention (4) Japanese Patent No. 1 1-008 162 discloses a supply Screen-printed matte coated paper, with extremely low white paper gloss. At least one side of the base paper is hammer-shaped with an aggregate weight of 75 to 85% by weight, with an average particle size of 30 to 101. 〇μπι The second-stage granular precipitated calcium carbonate and 15% by weight to 25% by weight / q average particle size of 1.0 μm to 2.0 μm kaolin composition coating. Japanese patent word 5 虎 弟 1 1-0 No. 6 9 4 2 6 discloses a light-coated paper for lithographic printing, which has blank paper gloss and printing gloss. The paper has two coating layers, each containing a colorant and an adhesive, and the upper coating layer contains 50 weight ratio to 8 5 weight ratio, calcium carbonate with an average particle size of not less than 0.2 μπι, and no less than 0,5 μιτι 'when used as a colorant, and 8 weight ratio to 15 weight ratio, 50 nm to 70 nm average particle size copolymer latex , And 50% to 70% adhesive for 100% pigment weight adhesive. Therefore, there is still a need for a paper that can produce high paper sheet gloss Improved coating and calcium carbonate pigment. Summary of the Invention The present invention relates to a paper coating pigment, which comprises a blend of first and second aragonite precipitated calcium carbonate (PCC) particles. The blended pigment is the first The average particle size (APS) of this kind of particles is about 0.4 micrometers, and the average particle size (APS) of the second blended colorant particles is about 0.5 micrometers. The colorant preferably contains about 50: 50 to about 80: The 20 weight ratio of the first 0.4 micron particles to the second 05 micron particles is preferably about 60:40 weight ratio. The present invention also relates to a method for manufacturing the coated paper, which comprises Preparation of miscellaneous blended aragonite Shendian carbonic acid coloring material, adding clay, and adding the coloring material to a paper base material containing a binder and other additive pastes. In the best case, the paper size is suitable for financial standards. (CNS) A4 specifications (210X297 public love)

Hold

^ «1791

Blended with aragonite to precipitate calcium carbonate, it is recognized that I prepare hydraulic and keel, which accounts for about 30% by weight to about 85% weight! %, And the rest of the note, 曰, ^^, 、, 70%, 1% to about 15 weight. /. Clay (mixture state exists. Check ~ ~ plastic details of the sincerity-unless otherwise stated 'The following ratios or percentages are about by weight. This invention relates to a paper coating composition containing calcium carbonate particle admixtures. A method for using the composition to increase paper gloss, and a method for producing glossy paper with a paper sheet, and a paper manufactured by the method. The carbonic acid feed is preferably Shen Dian Wenshi (ie, an orthorhombic type). When Used as a coloring agent, the calcium carbonate coloring agent of the present invention provides paper gloss improvement: especially compared with the traditional technology coating grade hard acid salt, it is particularly beneficial to the manufacture of high-gloss paper and paperboard. It is unexpected that the gloss improvement of the coated paper sheet is caused by the use of particles that have different particle size distributions with an average f from about Gi micrometers to about 0.2 micrometers. In addition, the calcium carbonate pigments of the present invention Compared with other calcium carbonate pigments, it also has advantages including easy calendering of the paper and the gloss of the paper and the printing gloss of the paper obtained by coating the paper with the colorant blend. The calcium carbonate component particles that can be mixed with the calcium carbonate coloring compound are preferably synthesized by the anti-Sk reaction of the carbon dioxide gas stone of the aqueous calcium hydroxide slurry ("lime milk") (i.e. Hall) of aragonite particles is preferred. In a preferred embodiment, the present invention is prepared by blending calcium carbonate with a mixture of particles having an average particle size of 0.40 microns and 0.50 microns, which is Minerals Technologies Inc. 'New Provided by York, New York, each number is -8- This paper size applies to China National Standard (CNS) A4 (210X297 mm)

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Line 581791 A7 _ B7__ V. Description of the invention (6) OPACARB® A40 PCC and OPACARB® A50 PCC. Specifically, OPACARB® A40 PCC and OPACARB® A50 PCC are aragonite precipitated calcium carbonate particles with an average particle diameter of about 0.4 microns and 0.5 microns, and the deviation is distributed within ± 0.02 microns of the average quality. The average particle size of the particles according to the present invention is determined by a Micromeritics Sedigraph 5 1 00 distribution meter, which is a particle size distribution meter that uses Stokes' law to measure (refer to CRC Handbook of Chemistry and Physics, 69th Edition 1988-1989, page F- 1 05), which provides the rate of fall of small spheres in a viscous fluid. From this point, it is judged that the particle size distribution and average particle size based on mass (weight) are obtained. The aragonite P C C colorant of the present invention can obtain improved coating results, either alone or in combination with any conventional coating colorant condition. When mixed with clay, the p c C component in the colorant may range from about 30% to about 85% by weight of the total coating formulation, and more preferably 60% by weight. The colorant mixture of the present invention is particularly suitable for high-gloss printing papers, and may be mixed with one or more conventional binders, thickeners and / or lubricants' as is well known in the art. The coating may also contain dilution water in an amount sufficient to achieve a final solids content of the coating of from about 50% to about 70% by weight. The specific examples of the present invention are specifically illustrated with reference to the following exemplary modes. The following non-limiting examples are only used to describe the present invention and are not intended to limit the present invention. The scope of the invention is defined by the scope of the attached patent application. The following experimental formulations. Take 40 parts of precipitated calcium carbonate color in a traditional flat-plate Cowles type mixer, and mix with 72% solids coating and clay. The clay used in all the examples below is ALPHAGLOSS® clay, Huber

Corporation. Separate and combine 〇pACARB @ A4〇 · -9- 581791 A7 B7___ V. Description of the invention (7) OPACARB® A50 PCC and ALBAGLOS® S PCC particles are used to evaluate the effect of various calcium carbonate particles. Specifically, Coating Mixtures Nos. 1 and 7 were separately formulated with ALPHAGLOSS® clay to evaluate the effect of OPACARB ⑧ A40PCC aragonite particles and OPACARB® A50 PCC aragonite particles separately. Coating Mixtures Nos. 2, 3, and 4 evaluated OPACARB® A40 PCC aragonite particles in comparison with ALBAGLOS® S PCC calcite particles traditionally used as clay-based paper coating compositions at about 40:60 to about 60: 4. 0 Effect under different weight ratio range. Coating Mixtures No. 6 and No. 5 were used to evaluate the blending of aragonite P C C colorants with OPACARB® A40 PCC aragonite particles to OPACARB® A50 PCC aragonite particles in weight proportions according to the present invention. The following table 1 shows the composition of the prepared coating mixture. The calcium carbonate particles and clay are expressed in weight%. Table 1 Colorant mixture number 1 2 3 4 5 * 6 * 7 ALBAGLOS ® S PCC (wt%) 2 5 20 15 OPACARB ® A40 PCC (% by weight) 40 15 20 2 5 2 5 20 OPACARB ® A50 PCC (% by weight) 15 2 0 40 ALPHAGLOSS® CLAY (% by weight) 60 60 60 60 60 60 60 * Calcium carbonate pigments according to the invention After the formula is mixed, each binder is added, and the mixture is also mixed by a traditional flat Cowles type mixer. Each calcium carbonate colorant formula contains the same combination-10- This paper size applies Chinese National Standard (CNS) A4 specification (210X 297 mm) 581791 A7 B7_ V. Description of the invention (8) Agent, containing 11 parts of Gencorp Corporation ( GENFLO® 5905 Acetophenone / Butadiene Latex (now Omnova Corporation), 3 parts of Penford Starch Corporation's PENFORD® 280 Gum Hydrocarbyl Vinyl Starch, and 1 part of Hard Moon Purpose Acid # 5 Lubricant. Add ADMIRAL® 3089 standard paper thickener from Hercules Corporation to each coating sample to achieve the target Brookfield viscosity of 1200 cps at 100 rpm. Generally speaking, the amount of thickener that reaches the target viscosity increases with the degree of carbonation. The colorant coating was formulated into about 60% solid content, and the solid content% and residual water characteristics were measured by the AA-GWR method (Kaltec ScientiHc, USA). Low-shear cp s viscosity was measured using Brookfield's RVT type viscosity at 10 rpm, 20 rpm, 50 rpm, and 10 rpm. High shear viscosity was measured with a Hercules High Shear Viscometer from Kaltec ScientiHp, USA. The Hercules viscosity was operated under the following conditions: E bob, 400,000 dyne-cm / cm spring constant, 0-111-4400 rpm, at room temperature. The formula data after coating test are shown in Table 2 below. Table 2 Coating No. ___ 1 2 3 4 5 * 6 * 7 Solid content,% β 60.4 60.2 60.5 60.3 60.2 60.1 60.2 AA-GWR, grams per square meter (gsm) 89 90 84 91 94 88 97 HERCULES viscosity, cps At 4400 rpm 50.0 47.9 46.5 42.5 45.1 41.0 38.9 BROOKFIELD viscosity cps at 100 rpm 1420 1100 1200 1060 1310 1310 1120 cps at 50 rpm 2560 1800 1940 1720 2090 2240 1840 cps at 20 rpm 5250 3650 3900 3500 4275 4700 3800 cps at 10 rpm 9 6600 7000 6400 76001 8600 7000 pH value (adjusted to 8.5-8.9 with NaOH) 8.5 8.5 8.5 8.5 8.5 8.5 8.5 Adding thickener 27 30 30 30 25 30 25 * The aragonite precipitated calcium carbonate pigment according to the present invention. -11-This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

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Line 581791 A7 B7 V. Description of the invention (9) After the coating is prepared, apply Cylindrical Laboratory Coater (CLC-6000) to 51.1 pounds per ream (70 grams per square meter) of paper substrate. The coating target is 3,300 square feet of cloth with 9 pounds. The coated paper was calendered at 150 degrees Fahrenheit with a roller-to-wheel pressure of 800 pounds per square inch (psi) in a laboratory grade calender. Coated paper is subjected to standard tests including paper gloss, printing gloss, brightness, and light transmission. The coated paper test data is shown in Table 3. The printing gloss value is determined by the Nancy Plowman Test Method (NPA), and the rest of the values are based on the T A PI PI test method, as known to those skilled in the art.

Table 3 Coating No. 1 1 2 3 4 5 * 6 * 7 Paper gloss,% 73.6 72.6 72.1 72.7 75.7 74.6 73.3 NPA printing gloss,% Rapida SFO Black 90.6! 92.8 92.1 91.2 91.8 91.6 92.4 Brightness TAPPI,% 86.0 85.7 86.0 85.8 86.0 85.9 85.9 Light transmittance TAPPI,% 89.6 90.2 89.7 89.9 90.1 90.0 90.0 Color HUNTER L HUNTER A HUNTER B 92.4 92.4 92.4 92.4 92.5 92.4 92.4 0.0 0.0 0.0 0.0 -0.1 -0.1 -0.1 2.3 2.3 2.3 2.3 2.4 2,4 2.4 Gurley transparent Porosity (seconds at 10 cc) 83 93 86 91 94 91 95 PPS-10 roughness 1.32 1.41 1.45 1.36 1.34 1.37 1.42 IGT Pick (cm 3.0 cm / s) 91 91 91 76 82 82 76 Solid content,% 60.4 60.2 60.5 60,3 60.2 60.1 60.2 * The aragonite precipitated calcium carbonate pigment according to the present invention. Hold

Line -12- ______ This paper size is applicable to Chinese National Standard (CNS) A4 (210X297 mm) 581791 A7 B7 __ V. Description of the invention (10) The above data shows that the paper colorant provided by the present invention provides better paper gloss, and At the same time, it shows that the calcium carbonate paint colorant can be used in combination with a large amount of clay, without reducing the printing gloss properties. When comparing the gloss of papers No. 6 and No. 5, it can be seen that the weight ratio of particles containing OPACARB⑧A40 PCC aragonite and OPACARB® A50 PCC aragonite is from about 50:50 to about 80:20, preferably In the case of about 60:40, there is a great improvement. In addition, when these particle mixtures provide improved paper gloss, there is no reduction in printing gloss that would normally occur with high levels of calcium carbonate. In particular, when using the weight ratio of OPACARB® A40 PCC particles to OPACARB® A50 PCC particles according to the present invention, 74.6% -75,7% of paper and printing gloss range and 91.6% Rapida SF Black-91.8% Rapida SF〇Black, higher than the paper and printing gloss obtained by using OPACARB® A40 PCC alone in coating number 1 (73.6%, 90.6% Rapida SFO Black), and higher than using OPACARB® A50 PCC alone in coating number 7 (73.3%, 92.4% Rapida SFO Black) paper gloss, while printing gloss is the same. In addition, the coordination effect can be seen when using a higher OPACARB® A40 PCC to OPACARB® A50 PCC ratio, as opposed to the very low printing gloss (90.6% Rapida SFO Black) obtained using OPACARB® A40 PCC and clay (Paint No. 1) alone. ), And low print gloss (92.4% Rapida SF〇Black) of OPACARB® A50 PCC and clay (Paint No. 7) alone. In contrast, when the aragonite blended coloring material of the present invention is used in combination with the aragonite mixture containing calcite particles, an improvement in paper gloss can also be seen. In particular, when using the present invention OPACARB® A40 PCC vs. OPACARB® A50 PCC particle weight -13- This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 581791 A7 B7 V. Description of the invention (11 ) Ratio (Paint No. 6 and No. 5), the paper gloss value range of the paper garden is from 74.6% to 75.7% 'significantly better than using acARB® A40 PCC aragonite particles versus ALBAGLOS® S PCC calcite particles (Paint No. Nos. 2 to 4) Weight ratio 4 0: 60 to 6 0: 4 of 72,1% -72.7% paper gloss. In addition, 'when comparing the printing gloss properties of the same grade containing the aragonite / calcite colorant mixture', the improved paper glossiness of the blended aragonite colorant is clearer. In the particle size distribution of the particles used in the compound according to the present invention, the average value varies from about 0.1 micrometers to about 0.2 micrometers. Other blends with similar differences in particle size distribution exhibit similar coordination effects on the properties of coated paper. In addition, 'salt k is outside of the aragonite / aragonite blend, and other similar red-red | bow crystal mixtures (such as calcite / calcite) that can meet the above particle size distribution conditions can also show similar properties in coated paper Coordinate effect. Although the above has been explained with specific examples and applications of the present invention, those skilled in the art will know a variety of adjustments and specific examples without departing from the concept of the present invention described above. Therefore, all adjustments and specific examples covered by the scope of the attached patent application belong to the true spirit and scope of the present invention. -14- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

Claims (1)

581791 ABCD No. 0911054 pEW? Ir ^ ~ Chinese application encirclement # 本 _- 4 月) Six, the scope of patent application a '1. A calcium carbonate product for coating composition to produce a high paper gloss surface treatment, the product includes: The first type of calcium carbonate particles having a first average first particle size distribution and the second type of calcium carbonate particles having a second average second particle size distribution, and the difference between the first and second average values is between 0 μm to 0.2 micron, the first calcium carbonate particles and the second calcium carbonate particles are provided in a weight ratio of 50:50 to 80:20. 2. The calcium carbonate product according to item 1 of the application, wherein the weight ratio of the first calcium carbonate particles to the second calcium carbonate particles is 60:40. 3. The carbonate product according to item 1 of the scope of the patent application, wherein the first calcium carbonate particles and the second calcium carbonate particles are aragonite precipitated calcium carbonate (PCC) particles. 4. The carbonic acid product according to item 1 of the patent application scope, wherein the average particle size (APS) of the first calcium carbonate particles is 0.4 micrometers, and the average particle size (APS) of the second calcium carbonate particles is 0.5 micrometers. . 5. The carbonic acid product according to item 2 of the patent application, wherein the average particle size (APS) of the first calcium carbonate particles is 0.4 micrometers, and the average particle size (APS) of the second calcium carbonate particles is 0.5 micrometers. . 6. The carbonic acid dance product according to item 4 of the application, wherein the average particle size (APS) of the first calcium carbonate particles is 0.4 micrometers, and the average particle size (APS) of the second calcium carbonate particles is 0.5 micrometers. . 7. A paper coating pigment, comprising: the first calcium carbonate particles having a first average and a first particle size distribution. The paper size is applicable to the Chinese National Standard (CNS) A4 specification (210X 297 mm). 79, and a second calcium carbonate particle having a second average and a second particle size distribution, wherein the difference between the first and second average values is between 0.1 micron and 0.2 micron away from the first calcium carbonate particle and the second carbonic acid The calcium particles are provided in a weight ratio of 50:50 to 80:20. 8. The paper coating colorant according to item 7 of the patent application scope, wherein the weight ratio of the first calcium carbonate colorant to the second calcium carbonate colorant is 60:40. 9. The paper coating colorant according to item 7 of the application, wherein the first carbonic acid colorant and the second calcium carbonate colorant are aragonite precipitated calcium carbonate (PCC) colorant. 10. The paper coating colorant according to item 7 of the application, wherein the first calcium carbonate particles have an average particle size (APS) of 0.4 micrometers and the second calcium carbonate particles have an average particle diameter (APS) of 0.5 micrometers. 11. The paper coating colorant according to item 8 of the application, wherein the first calcium carbonate particles have an average particle size (APS) of 0.4 micrometers and the second calcium carbonate particles have an average particle diameter (APS) of 0.5 micrometers. 12. The paper coating colorant according to item 9 of the patent application, wherein the average particle size (APS) of the first calcium carbonate particles is 0.4 micrometers, and the average particle size (APS) of the second calcium carbonate particles is 0.5. Microns. 13. —A method for manufacturing a paper with high paper gloss, comprising the steps of: a) providing first calcium carbonate particles having a first average first particle size distribution, and b) & supplying a first average The second carbonic acid dance particle with the second particle size distribution -2-This paper size is applicable to the Chinese National Standard (CNS) A4 specification (210 X297 mm) The difference between the first and second average values is 0.001 μm to 0.2 μm, and c) mixing the first type of calcium carbonate particles with the second type at a weight ratio of 50.50 to 80:20. Seed calcium carbonate particles to form a colorant blend, d) mixing the colorant blend with at least one binder to form a coating slurry, e) coating the paper with the coating slurry to form a coating, and f) The paper is dried and calendered to form a coated paper with high paper gloss. 14. The method according to item 13 of the scope of patent application, wherein the weight ratio of the first type of calcium carbonate particles to the second type of calcium carbonate particles is 60.0.40. 15. The method of claim 13 in the scope of patent application, wherein the first calcium carbonate particles and the second calcium carbonate particles are aragonite precipitated calcium carbonate (pcc) particles. 16. The method according to item 13 of the patent application scope, further comprising providing clay in step c), and mixing the clay and the coating mixture in an amount ranging from 15% to 70% by weight. 17. The method according to item 13 of the scope of patent application, wherein the average particle size (APS) of the first calcium carbonate particles is 0.4 m, and the average particle size (APS) of the second calcium carbonate particles is 0.5 m. 18. The method according to item 4 of the scope of patent application, wherein the average particle size (eight!) Of the first calcium carbonate particles is 0.4 micrometers, and the average particle size (APS) of the second calcium carbonate particles is 0.5 Microns. 19. The method according to item 15 of the scope of patent application, wherein the average particle size (eight 1 ^) of the first type of calcium carbonate particles is 0.4 micron, and the second type of calcium carbonate particles are 3-581791 A8 B8 C8 D8, The patent application range has an average particle size (APS) of 0.5 microns. 20. The method according to item 16 of the patent application, wherein the first calcium carbonate particles have an average particle size (APS) of 0.4 micrometers and the second calcium carbonate particles have an average particle diameter (APS) of 0.5 micrometers. 21. —A paper product manufactured by the method described in item 13 of the scope of patent application. -4-This paper size applies to China National Standard (CNS) A4 (210X297 mm)