Surface-mineralized organic fibers

Abstract

The present invention relates to surface-mineralized organic fibers comprising organic fibers having a length in the millimeter range, the surface of which is at least partially coated with finely divided alkaline earth carbonate nanoparticles by means of binders based on copolymers comprising as monomers one or more dicarboxylic acids and one or more monomers from the group of diamines, triamines, dialkanolamines or trialkanolamines and epichlorohydrin, a method for producing such surface-mineralized organic fibers, aqueous slurries thereof, their use in papermaking, in surface finishing of paper, plastic, cement and clay surfaces, in paints and varnishes and the use of the inventive binders for coating the organic fibers with nano alkaline earth carbonates.

Claims

1. An aqueous slurry comprising surface-mineralized organic fibers consisting of organic fibers coated at least partially with finely divided alkaline earth carbonate particles by means of a binder, wherein the organic fibers have a length in the millimeter range; 92 to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter of less than 200 nm; the binder is a copolymer comprising one or more dicarboxylic acids as a monomer; one or more monomers from the group of diamines, triamines, dialkanolamines or trialkanolamines; and epichlorohydrin, wherein the binder is optionally partially or completely neutralized by an anionic polymer; and wherein the organic fibers are present in an amount of 5 to 50 wt % based on the total dry weight of the organic fibers and the alkaline earth carbonate particles, the alkaline earth carbonate particles are present in an amount of 95 to 50 wt % based on the total dry weight of the organic fibers and alkaline earth carbonate particles, the binder is present in an amount of 0.3 to 10 wt % based on the total dry weight of the surface-mineralized organic fibers, the alkaline earth carbonate particles are natural ground calcium carbonate, precipitated calcium carbonate, a mixed carbonate, dolomite, or any mixture thereof, and wherein the alkaline earth carbonate particles are dispersed or milled in the presence of one or more milling aids and/or dispersants in an amount of 0.2 to 1 mg/m.sup.2 of the alkaline earth carbonate particles, and the surface-mineralized organic fibers are optionally dispersed with an added dispersing agent.

2. The aqueous slurry according to claim 1, wherein the organic fibers are sustainable organic fibers.

3. The aqueous slurry according to claim 1, wherein the organic fibers are wood fibers, cellulose fibers, cotton fibers, or any mixture thereof.

4. The aqueous slurry according to claim 1, wherein the organic fibers are wood fibers, cellulose fibers, or a mixture thereof.

5. The aqueous slurry according to claim 1, wherein the organic fibers have a length in a range of 0.1 mm to 9.9 mm.

6. The aqueous slurry according to claim 1, wherein the organic fibers have a length in a range of 0.5 mm to 7.5 mm.

7. The aqueous slurry according to claim 1, wherein the organic fibers have a length in a range of 1 mm to 5 mm.

8. The aqueous slurry according to claim 1, wherein the organic fibers have a width or thickness in a range from 10 μm to 1000 μm.

9. The aqueous slurry according to claim 1, wherein the organic fibers have a width or thickness in a range from 20 μm to 750 μm.

10. The aqueous slurry according to claim 1, wherein the organic fibers have a width or thickness in a range from 50 μm to 200 μm.

11. The aqueous slurry according to claim 1, wherein the organic fibers have a length/width ratio or length/height ratio of 1:1 to 100:1.

12. The aqueous slurry according to claim 1, wherein the organic fibers are cellulose fibers having a length/width ratio or length/height ratio of at least 25:1.

13. The aqueous slurry according to claim 1, wherein the organic fibers are cellulose fibers having a length/width ratio or length/height ratio of at least 50:1.

14. The aqueous slurry according to claim 1, wherein the organic fibers are cellulose fibers having a length/width ratio or length/height ratio of at least 75:1.

15. The aqueous slurry according to claim 1, wherein the organic fibers are cellulose fibers having a length/width ratio or length/height ratio of at least 100:1.

16. The aqueous slurry according to claim 1, wherein the organic fibers are wood pulp having a length/width ratio or length/height ratio of 2:1 to 10:1.

17. The aqueous slurry according to claim 1, wherein the alkaline earth carbonate particles are natural ground calcium carbonate selected from marble, limestone, chalk or any mixture thereof.

18. The aqueous slurry according to claim 1, wherein the alkaline earth carbonate particles are natural ground calcium carbonate and/or precipitated calcium carbonate having a vateritic, calcitic or aragonitic crystal structure.

19. The aqueous slurry according to claim 1, wherein the dolomite of the alkaline earth carbonate particles are ground natural dolomite rock containing at least 50 wt % dolomite mineral.

20. The aqueous slurry according to claim 1, wherein the dolomite of the alkaline earth carbonate particles are ground natural dolomite rock containing at least 75 wt % dolomite mineral.

21. The aqueous slurry according to claim 1, wherein the dolomite of the alkaline earth carbonate particles are ground natural dolomite rock containing at least 90 wt % dolomite mineral.

22. The aqueous slurry according to claim 1, wherein the dolomite of the alkaline earth carbonate particles are ground natural dolomite rock containing more than 98% dolomite mineral.

23. The aqueous slurry according to claim 1, wherein 92% to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter in a range from 20 nm to 200 nm.

24. The aqueous slurry according to claim 1, wherein 92% to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter in a range from 50 nm to 180 nm.

25. The aqueous slurry according to claim 1, wherein 92% to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter of less than 150 nm.

26. The aqueous slurry according to claim 1, wherein 92% to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter in a range from 70 nm to 150 nm.

27. The aqueous slurry according to claim 1, wherein 92% to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter of less than 100 nm.

28. The aqueous slurry according to claim 1, wherein the alkaline earth carbonate particles are obtained by dry and/or wet milling steps.

29. The aqueous slurry according to claim 1, wherein the alkaline earth carbonate particles are dispersed and/or milled in the form of an aqueous slurry having a solids content of the alkaline earth carbonate of more than 10 wt %.

30. The aqueous slurry according to claim 1, wherein the alkaline earth carbonate particles are dispersed and/or milled in the form of an aqueous slurry having a solids content of the alkaline earth carbonate of more than 50 wt %.

31. The aqueous slurry according to claim 1, wherein the alkaline earth carbonate particles are dispersed and/or milled in the form of an aqueous slurry having a solids content of the alkaline earth carbonate of more than 70 wt %.

32. The aqueous slurry according to claim 1, wherein the dispersants and/or milling aids are present in an amount of 0.3 to 0.7 mg/m.sup.2 particle surface area of the alkaline earth carbonate.

33. The aqueous slurry according to claim 1, wherein the ratio of the amount of the optionally added dispersant to the amount of binder in the surface-mineralized organic fibers, each based on the solids content, is 1:5 to 1:20.

34. The aqueous slurry according to claim 1, wherein the ratio of the amount of the optionally added dispersant to the amount of binder in the surface-mineralized organic fibers, each based on the solids content, is 1:10.

35. The aqueous slurry according to claim 1, containing from 10 to 30 wt % organic fibers, based on the total dry weight of the organic fibers and alkaline earth carbonate particles.

36. The aqueous slurry according to claim 1, containing from 17 to 27 wt % organic fibers, based on the total dry weight of the organic fibers and alkaline earth carbonate particles.

37. The aqueous slurry according to claim 1, containing from 95 wt % to 70 wt % alkaline earth carbonate particles, based on the total dry weight of the organic fibers and alkaline earth carbonate particles.

38. The aqueous slurry according to claim 1, containing from 87 wt % to 73 wt % alkaline earth carbonate particles, based on the total dry weight of the organic fibers and alkaline earth carbonate particles.

39. The aqueous slurry according to claim 1, wherein the organic fibers and the alkaline earth carbonate particles are present in a ratio of 1:20, 1:4, 1:3, 1:2, 1:1 or 1:10, based on the dry weight.

40. The aqueous slurry according to claim 1, wherein the dicarboxylic acid monomer of the binder comprises a saturated or unsaturated, branched or unbranched C.sub.2-C.sub.10 dicarboxylic acid, a C.sub.3-C.sub.9 dicarboxylic acid, a C.sub.4-C.sub.8 dicarboxylic acid, a C.sub.5-C.sub.7 dicarboxylic acid, or adipic acid.

41. The aqueous slurry according to claim 1, wherein the one or more monomers are selected from the group consisting of diamines, triamines, dialkanolamines or trialkanolamines comprises a linear or branched, substituted or unsubstituted diamine, triamine, dialkanolamine or trialkanolamine; N-(2-aminoethyl)-1,2-ethanediamine, diethanolamine; an N-alkyl-dialkanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, and triethanolamine.

42. The aqueous slurry according to 57, wherein the binder is a copolymer of adipic acid with N-(2-aminoethyl)-1,2-ethanediamine and epichlorohydrin.

43. The aqueous slurry according to claim 1, wherein the binder is cationically charged.

44. The aqueous slurry according to claim 1, wherein the binder is partially or completely neutralized by an anionic polymer.

45. The aqueous slurry according to claim 1, containing 0.5 wt % to 5 wt % binder, based on the total dry weight of the surface-mineralized organic fibers.

46. The aqueous slurry according to claim 1, containing 1 wt % to 3 wt % binder, based on the total dry weight of the surface-mineralized organic fibers.

47. A method for producing the aqueous slurry according to claim 1, comprising the steps: a) providing the organic fibers; b) providing the finely divided alkaline earth carbonate particles that are dispersed or milled in the presence of one or more milling aids and/or dispersants in an amount of 0.2 to 1 mg/m.sup.2 of the alkaline earth carbonate particles, wherein 92 to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter of less than 200 nm; c) providing the binder in aqueous form that is optionally partially or completely neutralized by an anionic polymer; d) mixing the organic fibers and the alkaline earth carbonate particles from a) and b); wherein the binder is added to the organic fibers from a) or the alkaline earth carbonate particles from b) before step d), and the resulting reaction mixture is homogenized to obtain an aqueous slurry comprising surface-mineralized organic fibers consisting of organic fibers coated at least partially with the alkaline earth carbonate particles by means of the binder, wherein the organic fibers are present in an amount of 5 to 50 wt % based on the total dry weight of the organic fibers and the alkaline earth carbonate particles, the alkaline earth carbonate particles are present in an amount of 95 to 50 wt % based on the total dry weight of the organic fibers and alkaline earth carbonate particles, the binder is present in an amount of 0.3 to 10 wt % based on the total dry weight of the surface-mineralized organic fibers, and the alkaline earth carbonate particles are natural ground calcium carbonate, precipitated calcium carbonate, a mixed carbonate, dolomite, or any mixture thereof.

48. A method for producing the aqueous slurry according to claim 1, comprising the steps: a) providing the organic fibers; b) providing the finely divided alkaline earth carbonate particles that are dispersed or milled in the presence of one or more milling aids and/or dispersants in an amount of 0.2 to 1 mg/m.sup.2 of the alkaline earth carbonate particles, wherein 92 to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter of less than 200 nm; c) providing the binder in aqueous form that is optionally partially or completely neutralized by an anionic polymer; d) mixing the organic fibers and the alkaline earth carbonate particles of a) and b); wherein the binder is added to the mixture of organic fibers from a) and the alkaline earth carbonate particles from b) after step d), and the resulting reaction mixture is homogenized to obtain an aqueous slurry comprising surface-mineralized organic fibers consisting of organic fibers coated at least partially with the alkaline earth carbonate particles by means of the binder, wherein the organic fibers are present in an amount of 5 to 50 wt % based on the total dry weight of the organic fibers and the alkaline earth carbonate particles, the alkaline earth carbonate particles are present in an amount of 95 to 50 wt % based on the total dry weight of the organic fibers and alkaline earth carbonate particles, the binder is present in an amount of 0.3 to 10 wt % based on the total dry weight of the surface-mineralized organic fibers, and the alkaline earth carbonate particles are natural ground calcium carbonate, precipitated calcium carbonate, a mixed carbonate, dolomite, or any mixture thereof.

49. A method for producing the aqueous slurry according to claim 1, comprising the steps: a) providing the organic fibers; b) providing the finely divided alkaline earth carbonate particles that are dispersed or milled in the presence of one or more milling aids and/or dispersants in an amount of 0.2 to 1 mg/m.sup.2 of the alkaline earth carbonate particles, wherein 92 to 98% of the alkaline earth carbonate particles, based on the number N of the alkaline earth carbonate particles, have a spherical equivalent diameter of less than 200 nm; c) providing the binder in aqueous form that is optionally partially or completely neutralized by an anionic polymer; wherein the binder is added first and then mixed with the organic fibers from a) and the alkaline earth carbonate particles from b), and the resulting reaction mixture is homogenized to obtain an aqueous slurry comprising surface-mineralized organic fibers consisting of organic fibers coated at least partially with the alkaline earth carbonate particles by means of the binder, wherein the organic fibers are present in an amount of 5 to 50 wt % based on the total dry weight of the organic fibers and the alkaline earth carbonate particles, the alkaline earth carbonate particles are present in an amount of 95 to 50 wt % based on the total dry weight of the organic fibers and alkaline earth carbonate particles, the binder is present in an amount of 0.3 to 10 wt % based on the total dry weight of the surface-mineralized organic fibers, and the alkaline earth carbonate particles are natural ground calcium carbonate, precipitated calcium carbonate, a mixed carbonate, dolomite, or any mixture thereof.

50. The method according to claim 47, wherein said one or more dispersants are added after combining the binder with the organic fibers from a) or the alkaline earth carbonate particles from b) or optionally the mixture from d).

51. The method according to claim 47, wherein said one or more dispersants are added before combining the binder with the organic fibers from a) or the alkaline earth carbonate particles from b) or optionally the mixture from d).

52. Surface-mineralized organic fibers in a solid, moist or dry state obtained by reducing the water content of the aqueous slurry according to claim 1.

53. Paper comprising the dried surface-mineralized organic fibers according to claim 52.

54. The paper according to claim 53, wherein the paper comprises 5 to 70 wt % of the surface-mineralized organic fibers, based on the total weight of the paper.

55. The paper according to claim 53, wherein the paper comprises 10 to 50 wt % of the surface-mineralized organic fibers, based on the total weight of the paper.

56. The paper according to claim 53, wherein the paper comprises 0.5 to 500 g/m.sup.2 of the surface-mineralized organic fibers.

57. The paper according to claim 53, wherein the paper comprises 2 to 100 g/m.sup.2 of the surface-mineralized organic fibers.

58. The paper according to claim 53, wherein the paper comprises 5 to 50 g/m.sup.2 of the surface-mineralized organic fibers.

59. Paint or spackling compound comprising the aqueous slurry according to claim 1 or surface-mineralized organic fibers in a solid, moist or dry state obtained by reducing the water content of said aqueous slurry.

60. A plastic comprising the aqueous slurry according to claim 1 or surface-mineralized organic fibers in a solid, moist or dry state obtained by reducing the water content of said aqueous slurry.

61. Filler comprising the aqueous slurry according to claim 1 or surface-mineralized organic fibers in a solid, moist or dry state obtained by reducing the water content of said aqueous slurry.

62. Pigment comprising the aqueous slurry according to claim 1 or surface-mineralized organic fibers in a solid, moist or dry state obtained by reducing the water content of said aqueous slurry.

63. Filtration aid comprising the aqueous slurry according to claim 1 or surface-mineralized organic fibers in a solid, moist or dry state obtained by reducing the water content of said aqueous slurry.

64. The aqueous slurry according to claim 44, wherein the anionic polymer is a sodium polyacrylate having an Mw of 25000 g/mol to 28000 g/mol, or a sodium polyvinyl sulfate.

Description

DESCRIPTION OF THE FIGURES

(1) Some of the figures described below are scanning electron micrographs (SEM) of various state-of-the-art mixtures and inventive surface-mineralized organic fibers. The mixtures and the inventive surface-mineralized organic fibers were adjusted to a concentration of 10 wt % in water. A few drops (about 100 mg) of each were diluted in 250 mL distilled water and filtered through a 0.2 μm pore membrane filter. The preparations obtained on the membrane filter were sputtered with gold and evaluated in the SEM.

(2) FIG. 1 shows a fiber mixture suitable for the inventive surface-mineralized organic fibers.

(3) FIG. 2 shows a fiber mixture suitable for the inventive surface-mineralized organic fibers.

(4) FIGS. 3 and 4 each show the SEM micrographs of state-of-the-art mixtures at two different magnifications.

(5) FIGS. 5 and 6 each show the SEM micrographs of a preparation of inventive surface-mineralized organic fibers consisting of fibers, nano calcium carbonate composition and binder at two different magnifications.

(6) FIGS. 7 and 8 each show the light micrographs of a preparation of inventive surface-mineralized organic fibers consisting of fibers, nano calcium carbonate composition and binder as a paint on a raw clay plate at two different magnifications.

(7) FIGS. 9 and 10 each show the SEM micrographs of a preparation of inventive surface-mineralized organic fibers consisting of fibers, nano calcium carbonate composition and binder at two different magnifications.

(8) FIG. 11 shows the SEM micrograph of a preparation of inventive surface-mineralized organic fibers consisting of fibers, nano calcium carbonate composition and binder.

(9) FIGS. 12 and 13 each show the SEM micrographs of a preparation of inventive surface-mineralized organic fibers consisting of fibers, nano calcium carbonate composition and binder at two different magnifications.

EXAMPLES

Preparation and Description of Nanoparticles Usable According to the Invention

(10) The preparation of nano alkaline earth carbonate compositions suitable for the inventive surface-mineralized organic fibers is described below:

(11) Nano alkaline earth carbonate composition 1 was continuously milled by wet milling in a vertical 160 liter attritor ball mill in two passes using limestone from the south of France dry premilled to an average spherical particle diameter of 45 μm in a conventional ball mill with iron cylpebs having a diameter of 2.5 cm, and using a total of 0.4 wt % sodium/magnesium polyacrylate having Mw=4000-8000 g/mol, based on the total dry weight of the nano alkaline earth carbonate as dispersant/milling aid at a solids content of 72 wt % to yield the following size distribution:

(12) TABLE-US-00001 Diameter Number (N) of (nm) particles in N % Wt % <200 95.6 15.2 200-400 3.2 14.0 400-600 0.7 14.1 600-800 0.2 12.2  800-1000 0.1 10.8

(13) The Brookfield viscosity of the slurry obtained after wet milling was 285 mPa.Math.s. The specific surface area, measured according to BET, was 11.2 m.sup.2/g (ISO 9277). The milling beads used were made of zirconium silicate and baddeleyite and had a size of 0.5-2 mm. Next the slurry was spray-dried (spray dryer type Mobile NIRO, model year 2005, GEA Niro A/S). The moisture content after drying was 0.13 wt %.

(14) Nano alkaline earth carbonate composition 2 was continuously milled by wet milling in a vertical 160-liter attritor ball mill in two passes using Norwegian marble premilled dry in a conventional ball mill to an average spherical particle diameter of 45 μm, and using a total of 0.55 wt % sodium/magnesium polyacrylate having an Mw of 4000-8000 g/mol, based on the total dry weight of the nano alkaline earth carbonate as the dispersant/milling aid, at a solids content of 72 wt %, to yield the following size distribution:

(15) TABLE-US-00002 Diameter Number (N) of (nm) particles in N % Wt % <200 96.3 17.8 200-400 2.8 14.2 400-600 0.5 12.6 600-800 0.2 10.7  800-1000 0.1 8.9

(16) The Brookfield viscosity of the slurry obtained after wet milling was 128 mPa.Math.s. The specific surface area, measured according to BET, was 12.6 m.sup.2/g (ISO 9277). The milling beads used were made of zirconium silicate and baddeleyite and had a size of 0.5-2 mm.

(17) Nano Alkaline earth carbonate composition 3 was fractionated using 45 kg nano alkaline earth carbonate composition 2 by means of a centrifuge. The slurry was dosed into the centrifuge (model KVT LAB-CUT LC 1000 classifier centrifuge, Krettek Verfahrenstechnik GmbH [Process Engineering, Inc.], D-41749 Viersen, Germany) using an Ismatec model GV-BES tubular squeeze pump. The dosing rate was 15-25 liters per hour. When the centrifuge was about 60% filled with centrifuge cake, the cycle was stopped and the coarse fraction was removed mechanically by means of a high-pressure cleaner. The ultrafine fraction was used further. By repeated separation of the coarse material, the desired grain fraction was produced, i.e., it was centrifuged at a low rotational speed at the beginning and the resulting fines were then centrifuged again at a higher rotational speed, etc., until achieving the desired fineness. Several batches were produced to obtain enough material.

(18) In 9 passes the centrifuge was operated at 3500 rpm. The coarse fraction was discarded. With the fine fraction, another 8 passes were performed at 5000 rpm. Finally, 4 more batches were processed at 6000 rpm. 1 kg nano alkaline earth carbonate 3 having 50 wt % solids and the following size distribution was produced.

(19) TABLE-US-00003 Diameter Number (N) of (nm) particles in N % Wt % <200 97.6 49 200-400 2.1 27.9 400-600 0.25 15.8 600-800 0.03 5.3  800-1000 0.003 1.4

(20) The Brookfield viscosity of the slurry obtained after this preparation is 150 mPa.Math.s. The specific surface area measured according to BET was 27.5 m.sup.2/g (ISO 9277).

(21) Description of Fibers Usable According to the Invention

(22) The following fibers were used for the following experiments:

(23) Fiber Mixture 1

(24) Mixture of 20 wt % pine cellulose (long fibers) and 80 wt % beech cellulose (short fibers), SR degree of 23° of the mixture from Papierfabrik Biberist, Switzerland.

(25) 85 wt % moisture.

(26) Fiber length about 0.5-3 mm

(27) Fiber width about 0.02-1 mm

(28) Fiber mixture 1 is shown in FIG. 1.

(29) Fiber Mixture 2

(30) Mixture of 10 wt % pine cellulose (long fibers), SR degree of 27° and 90 wt % wood pulp, SR degree of 79° from Papierfabrik Albbruck, Germany.

(31) 85 wt % moisture.

(32) Fiber length about 0.5-3 mm

(33) Fiber width about 0.1-0.5 mm

(34) Fiber mixture 2 is shown in FIG. 2.

(35) Production and Description of Binders Usable According to the Invention

(36) Binder 1

(37) 15±0.5 wt % aqueous solution of a copolymer of adipic acid with N-(2-aminoethyl)-1,2-ethanediamine and epichlorohydrin

(38) having the following characteristics:

(39) total chlorine content: about 1.5% organic chlorine content: <0.5% Mw>1000 g/mol Brookfield viscosity of the aqueous solution: 80±30 mPa.Math.s (Brookfield type EV-2+, disk spindle 3, 100 rpm; measured in a 250 mL low form glass beaker) pH 3.0

(40) Such products can be produced by a two-step synthesis process by a method with which those skilled in the art of organic synthesis are familiar. Production is done, e.g., by producing an intermediate product consisting of the reaction product of diethylenetriamine, monoethanolamine and adipic acid. Then in a second reaction, this intermediate product is reacted with epichlorohydrin using sulfuric acid and potassium sorbate as the catalyst to form the end product; the solids content is diluted with water to 12-20 wt % and the pH is adjusted to pH 3 with more sulfuric acid. Such polymers are sold by the company Lanxess, Germany, for example, under the brandname Nadavin, e.g., Nadavin DHN (15%), or the company Mare, Italy, under the brandname Maresin PD 125 (12.5%).

(41) Preparation and Description of State-of-the-Art Mixtures

Comparative Experiment 1: Mixture of 25 wt % Fiber Mixture 1 and 75 wt % Nano Alkaline Earth Carbonate Composition 2

(42) The fiber mixture 1 was diluted with water to 5 wt % solids content. The nano alkaline earth carbonate composition 2 was diluted with water to a solids content of 30 wt %. Then 300 g of the diluted fiber mixture 1 was mixed with 150 g of diluted alkaline earth carbonate composition 2 while stirring (500 rpm; impeller stirrer, diameter 30 mm). The resulting mixture had a solids content of about 12.6 wt %.

(43) Results

(44) a) Test for Segregation by Means of a Membrane Filter

(45) A filter test was performed to illustrate the segregation tendency of the mixture and to determine the filtration rate.

(46) 8 g of the obtained mixture were diluted with 200 mL water and this slurry was filtered using a membrane filter having a 0.2 μm pore diameter (pressure about 25 mbar, water jet pump, room temperature). The time required to filter 200 mL was measured. When segregation occurs nano alkaline earth carbonate penetrates first through and into the pores (cloudy filtrate). With time, a secondary filter cake is formed on the membrane filter and blocks the pores.

(47) Filtration time: >4 hours

(48) After 2 hours, only 130 mL filtrate were obtained. Filtration was concluded only after 4 hours and 30 minutes.

(49) The filtration time definitely shows the clogging of the filter pores due to segregation of nanoparticles and fibers.

(50) FIGS. 3 and 4 also show clearly the segregation of the nanoparticles from the fibers.

(51) b) Test for Segregation on a Screen

(52) In another segregation test, a 72 g sample of the mixture described above was diluted with water to 10 liters while stirring and filtered through a screen having a diagonal mesh of 150 μm. The resulting residue was dried at 110° C. and about 100 mbar for 5 minutes in a vacuum dryer of the same sheet-forming machine and then tested for the ash content. For this experiment a laboratory sheet-forming machine from the company of Gerd Schenkel (formerly Ernst Haage), D-45478 Mühlheim, Germany, was used.

(53) The test was performed twice with the following results:

(54) TABLE-US-00004 Residue 1 Residue 2 Average Paper weight 73.4 g/m.sup.2 65.5 g/m.sup.2 69.5 g/m.sup.2 Ash 550° C. 10.6 g/m.sup.2  9.5 g/m.sup.2 10.1 g/m.sup.2 (based on g/m.sup.2) Ash 550° C. 14.4% 14.5% 14.5% (wt % of paper weight)
Production and Description of Inventive Surface-Mineralized Organic Fibers

Experiment 2: Mixture of 22 wt % Fiber Mixture 1 and 75 wt % Nano Alkaline Earth Carbonate Composition 2 and 3 wt % Binder 1

(55) Fiber mixture 1 was diluted with water to 5 wt % solids content. 600 g of the diluted fiber mixture were mixed with 24 g binder 1 while stirring (at 500 rpm; impeller stirrer; diameter 30 mm; 5 minutes). Then 300 g of the resulting mixture was mixed with 54 g nano alkaline earth carbonate composition 2 while stirring (500 rpm; impeller stirrer; diameter 30 mm). The resulting surface-mineralized organic fiber slurry had a solids content of about 12.4 wt %.

(56) Results

(57) a) Test for Segregation by Means of a Membrane Filter

(58) A filter test was performed to illustrate the reduced segregation tendency of the surface-mineralized organic fibers and to determine the filtration rate.

(59) 8 g of the surface-mineralized organic fiber slurry were diluted with 200 mL water, and this slurry was filtered using a membrane filter having a 0.2 μm pore diameter (pressure about 25 mbar, water jet pump, room temperature). The time required to filter 200 mL was measured. When segregation occurs, nano alkaline earth carbonate penetrates first through and into the pores (cloudy filtrate). With time, a secondary filter cake is formed on the membrane filter and blocks the pores.

(60) Filtration time: 4 minutes

(61) The filtration time shows clearly that the segregation of nanoparticles and fibers was prevented.

(62) b) Test for Segregation on a Screen

(63) In another segregation test, 72 g of a sample of the slurry described above was diluted with water to 10 liters while stirring and filtered through a screen having a diagonal mesh of 150 μm. The residue thus formed was dried at 110° C. and about 100 mbar for 5 minutes in a vacuum dryer of the same sheet-forming machine and then tested for the ash content. For this experiment, a laboratory sheet-forming machine from the Gerd Schenkel company (formerly Ernst Haage), D-45478 Mühlheim, Germany was used.

(64) The test was performed twice with the following results:

(65) TABLE-US-00005 Residue 1 Residue 2 Average Paper weight 89.9 g/m.sup.2 82.0 g/m.sup.2 86.0 g/m.sup.2 Ash 550° C. 36.1 g/m.sup.2 32.3 g/m.sup.2 34.2 g/m.sup.2 (based on g/m.sup.2) Ash 550° C. 40.2% 39.4% 39.8% (wt % of paper weight)

(66) In comparison with the state-of-the-art mixtures of comparative experiment 1, this result shows clearly that the nano alkaline earth carbonate was retained 2.75× better, based on the total weight of the sheet, and that about 3.5× more nano alkaline earth carbonate was retained per square meter. Segregation was reduced drastically in comparison with comparative experiment 1.

(67) This is also confirmed by FIGS. 5 and 6, which clearly show the good coverage of fibers with nano calcium carbonate.

(68) FIGS. 7 and 8 show that the surface-mineralized organic fibers do not exhibit any significant segregation even when applied as paint to a raw clay plate.

Experiment 3: Mixture of 22 Wt % Fiber Mixture 1 and 75 Wt % Nano Alkaline Earth Carbonate Composition 2 and 3 wt % Binder 1

(69) Fiber mixture 1 was diluted with water to 5 wt % solids content. 300 g of the diluted fiber mixture were mixed with 54 g nano alkaline earth carbonate composition 2 while stirring (at 500 rpm; impeller stirrer; diameter 30 mm; 5 minutes). Then the resulting mixture was mixed with 24 g binder 1 while stirring (500 rpm; impeller stirrer; diameter 30 mm). The resulting surface-mineralized organic fiber slurry had a solids content of about 12.2 wt %.

(70) Results

(71) a) Test for Segregation by Means of a Membrane Filter

(72) A filter test was performed to illustrate the reduced segregation tendency of the surface-mineralized organic fibers and to determine the filtration rate.

(73) 8 g of the surface-mineralized organic fiber slurry were diluted with 200 mL water, and this slurry was filtered using a membrane filter having a 0.2 μm pore diameter (pressure about 25 mbar, water jet pump, room temperature). The time required to filter 200 mL was measured. When segregation occurs, nano alkaline earth carbonate penetrates first through and into the pores (cloudy filtrate). With time, a secondary filter cake is formed on the membrane filter and blocks the pores.

(74) Filtration time: 9 minutes

(75) The filtration time shows clearly that segregation of nanoparticles and fibers was prevented.

(76) b) Test for Segregation on a Screen

(77) In another segregation test, 72 g of a sample of the slurry described above was diluted with water to 10 liters while stirring and filtered through a screen having a diagonal mesh of 150 μm. The residue thus formed was dried for 5 minutes at 110° C. and about 100 mbar in a vacuum dryer of the same sheet-forming machine and then tested for the ash content. For this experiment, a laboratory sheet-forming machine from Gerd Schenkel (formerly Ernst Haage), D-45478 Mühlheim, Germany was used.

(78) The test was performed twice with the following results:

(79) TABLE-US-00006 Residue 1 Residue 2 Average Paper weight 100.4 g/m.sup.2 93.3 g/m.sup.2 96.9 g/m.sup.2 Ash 550° C.  39.0 g/m.sup.2 37.8 g/m.sup.2 38.4 g/m.sup.2 (based on g/m.sup.2) Ash 550° C. 39.0% 39.0% 39.0% (wt % of paper weight)

(80) In comparison with the state-of-the-art mixtures of comparative experiment 1, this result shows clearly that the nano alkaline earth carbonate was retained 2.6× better, based on the total weight of the residue, and that about 3.6× more nano alkaline earth carbonate was retained per square meter. Segregation was reduced drastically in comparison with comparative experiment 1.

(81) This is also confirmed by FIGS. 9 and 10, which show clearly the good coverage of the fibers with nano calcium carbonate.

Experiment 4: Mixture of 22 Wt % Fiber Mixture 1 and 75 Wt % Nano Alkaline Earth Carbonate Composition 1 and 3 wt % Binder 1

(82) 500 g nano alkaline earth carbonate composition 1 was coated with 100 g binder 1 within 15 minutes in a plowshare mixer. Fiber mixture 1 was diluted with water to 5 wt % solids content and 300 g of the diluted fiber mixture and 45 g water were mixed with 39 g of the pretreated nano alkaline earth carbonate composition 1 while stirring (at 500 rpm; impeller stirrer; diameter 30 mm; 5 minutes). The resulting surface-mineralized organic fiber slurry had a solids content of about 12.1 wt %.

(83) Results

(84) a) Test for Segregation by Means of a Membrane Filter

(85) A filter test was performed to illustrate the reduced segregation tendency of the surface-mineralized organic fibers and to determine the filtration rate.

(86) 8 g of the surface-mineralized organic fiber slurry were diluted with 200 mL water, and this slurry was filtered using a membrane filter having a 0.2 μm pore diameter (pressure about 25 mbar, water jet pump, room temperature). The time required to filter 200 mL was measured. When segregation occurs, nano alkaline earth carbonate penetrates first through and into the pores (cloudy filtrate). With time, a secondary filter cake is formed on the membrane filter and blocks the pores.

(87) Filtration time: 4 minutes

(88) The filtration time shows clearly that segregation of nanoparticles and fibers was prevented.

(89) b) Test for Segregation on a Screen

(90) In another segregation test, 72 g of a sample of the slurry described above was diluted with water to 10 liters while stirring and filtered through a screen having a diagonal mesh of 150 μm. The residue thus formed was dried for 5 minutes at 110° C. and about 100 mbar in a vacuum dryer of the same sheet-forming machine and then tested for ash content. For this experiment, a laboratory sheet-forming machine from Gerd Schenkel (formerly Ernst Haage), D-45478 Mühlheim, Germany was used.

(91) The test was performed twice with the following results:

(92) TABLE-US-00007 Residue 1 Residue 2 Average Paper weight 83.8 g/m.sup.2 86.8 g/m.sup.2 85.3 g/m.sup.2 Ash 550° C. 23.4 g/m.sup.2 24.4 g/m.sup.2 23.9 g/m.sup.2 (based on g/m.sup.2) Ash 550° C. 27.9 28.1% 28.0 (wt % of paper weight)

(93) In comparison with the state-of-the-art mixtures of comparative experiment 1, this result shows clearly that the nano alkaline earth carbonate was retained 2× better, based on the total weight of the residue, and that about 2.4× more nano alkaline earth carbonate was retained per square meter. Segregation was drastically reduced in comparison with comparative experiment 1.

(94) This is also confirmed by FIG. 11 which shows clearly the good coverage of the fibers with nano calcium carbonate.

Experiment 5: Mixture of 22 Wt % Fiber Mixture 2 and 75 Wt % Nano Alkaline Earth Carbonate Composition 3 and 3 Wt % Binder 1

(95) Fiber mixture 2 was diluted with water to a solids content of 5 wt %. 300 g of the diluted fiber mixture were mixed with 90 g nano alkaline earth carbonate composition 3 and 700 g water while stirring (at 500 rpm; impeller stirrer; diameter 30 mm; 5 minutes). Then, 24 g binder 1 was diluted with 100 mL water while stirring (500 rpm; impeller stirrer; diameter 30 mm; 5 minutes) and mixed with the mixture also while stirring. The resulting surface-mineralized organic fiber slurry had a solids content of about 5.5 wt %.

(96) Results

(97) a) Test for Segregation by Means of a Membrane Filter

(98) A filter test was performed to illustrate the reduced segregation tendency of the surface-mineralized organic fibers and to determine the filtration rate.

(99) 8 g of the surface-mineralized organic fiber slurry were diluted with 200 mL water, and this slurry was filtered using a membrane filter having a 0.2 μm pore diameter (pressure about 25 mbar, water jet pump, room temperature). The time required to filter 200 mL was measured. When segregation occurs, nano alkaline earth carbonate penetrates first through and into the pores (cloudy filtrate). With time, a secondary filter cake is formed on the membrane filter and blocks the pores.

(100) Filtration time: 4 minutes

(101) The filtration time shows clearly that segregation of nanoparticles and fibers was prevented.

(102) This is also confirmed by FIGS. 12 and 13, which definitely show the good coverage of the fibers with nano calcium carbonate.

Experiment 6: Mixture of 24 Wt % Fiber Mixture 1 and 75 Wt % Nano Alkaline Earth Carbonate Composition 2 and 1 Wt % Binder 1

(103) Fiber mixture 1 was diluted with water to a solids content of 5 wt %. 300 g of the diluted fiber mixture were mixed with 54 g nano alkaline earth carbonate composition 2 while stirring (at 500 rpm; impeller stirrer; diameter 30 mm; 5 minutes). Then 72 g of the resulting mixture was diluted further with water to 10 liters and mixed with 0.66 g binder 1 while stirring (500 rpm; impeller stirrer; diameter 30 mm; 5 minutes). The resulting surface-mineralized organic fiber slurry had a solids content of about 0.1 wt %.

(104) b) Test for Segregation on a Screen

(105) In another segregation test, 72 g of a sample of the slurry described above was diluted with water to 10 liters while stirring and filtered through a screen having a diagonal mesh of 150 μm. The residue thus formed was dried for 5 minutes at 110° C. and about 100 mbar in a vacuum dryer of the same sheet-forming machine and then tested for ash content. A laboratory sheet-forming machine from Gerd Schenkel (formerly Ernst Haage), D-45478 Mühlheim, Germany, was used for this experiment.

(106) This test was performed twice with the following results:

(107) TABLE-US-00008 Residue 1 Residue 2 Average Paper weight 100.1 g/m.sup.2 96.9 g/m.sup.2 98.5 g/m.sup.2 Ash 550° C.  38.0 g/m.sup.2 35.6 g/m.sup.2 36.8 g/m.sup.2 (based on g/m.sup.2) Ash 550° C. 38.0% 38.2% 38.1% (wt % of paper weight)

(108) In comparison with the state-of-the-art mixtures of comparative experiment 1, this result shows clearly that the nano alkaline earth carbonate was retained 2.5× better, based on the total weight of the residue, and that about 3.6× more nano alkaline earth carbonate was retained per square meter. Segregation was drastically reduced in comparison with comparative experiment 1.

Experiment 7: Charge Neutralization of Binder 1

(109) To determine the solids content of binder 1, about 0.8-1 g was weighed accurately to 1 mg and dried for 1 hour in a circulating air-drying cabinet at 150° C.

(110) Then the solids content of a sodium polyacrylate having an Mw of 25000-28000 g/mol, such as that also used to produce the nano alkaline earth carbonate composition 3, was determined in the same way and next a 1 wt % aqueous measurement solution was prepared.

(111) 1 g, based on the solids content of binder 1, was diluted with water to 1 wt % and titrated to charge neutralization with 1 wt % sodium polyacrylate measurement solution using the Mütek PCD O.sub.2 particle charge detector (BTG Instruments GmbH, 82211 Herrsching).

(112) Result

(113) To achieve a charge-based neutralization of 100 g binder 1, 10.36 g of a 42.8 wt % sodium polyacrylate solution having an Mw 25000-28000 is needed. Based on the solids content, 29.2 g 100 wt % sodium polyacrylate having an Mw of 25000-28000 g/mol was needed for charge neutralization of 100 g 100 wt % binder 1.