CN115768947A - Surface mineralized organic fibre and its preparing process - Google Patents
Surface mineralized organic fibre and its preparing process Download PDFInfo
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- CN115768947A CN115768947A CN202180042240.6A CN202180042240A CN115768947A CN 115768947 A CN115768947 A CN 115768947A CN 202180042240 A CN202180042240 A CN 202180042240A CN 115768947 A CN115768947 A CN 115768947A
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- 238000010438 heat treatment Methods 0.000 claims description 2
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- 230000015572 biosynthetic process Effects 0.000 abstract description 2
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- 238000003756 stirring Methods 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
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- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 3
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- 230000006872 improvement Effects 0.000 description 1
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Images
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/70—Inorganic compounds forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/32—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond
- D06M11/36—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond with oxides, hydroxides or mixed oxides; with salts derived from anions with an amphoteric element-oxygen bond
- D06M11/44—Oxides or hydroxides of elements of Groups 2 or 12 of the Periodic Table; Zincates; Cadmates
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/73—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with carbon or compounds thereof
- D06M11/76—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with carbon or compounds thereof with carbon oxides or carbonates
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/675—Oxides, hydroxides or carbonates
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
- D06M2101/02—Natural fibres, other than mineral fibres
- D06M2101/04—Vegetal fibres
- D06M2101/06—Vegetal fibres cellulosic
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Paper (AREA)
- Materials For Medical Uses (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
Abstract
A method of making mineralized fibers having a fiber core and a calcium carbonate shell may include mixing the fibers with green liquor and adding CaO to produce a causticizing reaction that results in the formation of a calcium carbonate shell coating around the fibers.
Description
Cross Reference to Related Applications
This is hereby claimed to the benefit of priority from U.S. provisional patent application No. 63/083,528, filed on 12/6/2020, and the disclosure is incorporated herein in its entirety.
Technical Field
The present disclosure relates generally to surface-mineralized organic fibers and methods for making the same, and more particularly, to organic fibers coated with calcium carbonate and methods for coating organic fibers.
Background
Cellulose-calcium carbonate composites have been used as fillers in the paper industry. Conventional cellulose-calcium carbonate materials incorporate calcium carbonate such that the basic fiber properties of the cellulose component are maintained. It is generally recognized in the art that the fibrous properties of the composite are needed to better incorporate the composite into the fibrous matrix of the paper.
WO 97/01670A1 relates to fillers used in papermaking and consisting essentially of calcium carbonate. The filler disclosed therein is a porous aggregate of calcium carbonate particles, which is precipitated on the surface of fibers, such as cellulose fibers. The described filler is based on the fact that calcium carbonate can be precipitated on very fine fibers so that it adheres to the fibers. This is due, among other things, to the great fineness of the fibres, which have a length of maximally 400 μm.
WO 98/35095 discloses a paper making process comprising mixing an aqueous slurry of mineral filler with an aqueous slurry of wood fibres, and adding a flocculating agent, wherein the major part of the filler is in the interior of the cellulose fibres. The filler and the flocculant are added to the pulp fibres independently of each other. The filler is flocculated inside the fibres and retained in the interior while the filler forms agglomerates outside the fibres. The document also does not mention the use of a binder that produces a uniform distribution of the filler on the surface of the fibers.
WO 99/14432 discloses a process for making paper by mixing together an anionic starch, carboxymethyl cellulose or other polymeric binder and a cationic inorganic or polymeric coagulant to form a dilute cellulose pulp stock, and then flocculating the suspension with an anionic swellable clay or other anionic retention aid.
Summary of the invention
Thus, many mixtures and composites are known which can be used to control certain properties of pigments and/or fillers. However, none of these documents disclose a laminate type structure in which the fibers are substantially coated and entrained by the calcium carbonate shell.
Drawings
Fig. 1 is a photomicrograph showing free fibers at the surface of a tissue;
FIG. 2 is a graph showing the bulk score of softness as a function of free fibers on a surface as disclosed in U.S. Pat. No. 4,300,981;
FIG. 3 is a schematic diagram of the sodium and calcium loops in a kraft pulp mill;
FIG. 4 is a schematic diagram of an embodiment of a method of the present disclosure;
fig. 5 includes Scanning Electron Microscope (SEM) images of fibers before and after surface mineralization by methods according to the present disclosure;
FIG. 6 includes Scanning Electron Microscope (SEM) images of the fiber before and after precipitation of calcium carbonate on the surface of the fiber by conventional methods;
FIG. 7 is a graph comparing bulk performance as a function of the content of surface mineralized organic fibers in the tissue product;
FIG. 8A is a Scanning Electron Microscope (SEM) image of a handsheet prepared by a conventional process using a standard PCC filler as an additive;
FIG. 8B is a Scanning Electron Microscope (SEM) image of a handsheet made using a 50/50 blend of standard pulp fibers and mineralized fibers according to the present disclosure;
FIG. 9 is a graph showing the sheet bulk properties of paper made with mineralized fibers compared to the starting (unmineralized) fibers; and is
Figure 10 is a graph showing the mineralization efficiency as a function of the specific surface area of the starting fibers.
Detailed Description
Mineralized organic fibers are provided herein. The organic fibers may be coated and entrained with an outer calcium carbonate coating. The organic fibers may include cellulose fibers or may be cellulose fibers. Any pulp fiber may be included. For example, the pulp fibers may be eucalyptus fibers, birch fibers, acacia fibers, poplar fibers, pine fibers, spruce fibers, mixed tropical hardwood fibers, old corrugated cardboard recycled fibers, and combinations thereof.
The outer calcium carbonate coating is provided as a shell around the cellulose fiber core. Embodiments of the present disclosure may also include structures in which calcium carbonate penetrates into the cellulosic fiber core and into the shell. The surface strands of the fibers may be entrained or coated with calcium carbonate. The fibers may have a hollow interior. Mineralization according to the present disclosure can result in calcium carbonate penetrating into the hollow interior as well as coating the surface strands and forming a shell around the fiber core. It has been advantageously found that the entrainment of the organic fibers disclosed herein increases the bending stiffness of the fibers, which can result in improved performance in various applications, such as in papermaking (particularly paper intended for printing and hygiene applications). Such entrainment and/or penetration of calcium carbonate into the fibers is not achieved when calcium carbonate is added separately as a filler in the papermaking process. Surprisingly, it has been found that surface mineralized organic fibers can be incorporated into the fibrous paper matrix despite the increased bending stiffness, and certain properties can be enhanced. For example, in tissue paper products, incorporation of the surface-mineralized organic fibers of the present disclosure may allow for improved softness. This is contrary to conventional understanding that the fibrous properties of organic fibrous fillers are essential for proper incorporation into the fibrous matrix of paper.
Incorporating surface mineralized organic fibers according to the present disclosure into tissue paper products may improve bulk properties. Referring to fig. 7, the effect of mineralization is illustrated. It was found that 60% mineralization (i.e. 60% surface mineralized organic fibers in combination with 40% standard pulp fibers (called MinFib in fig. 7)) significantly improved bulk compared to control paper without surface mineralized organic fibers. It has been surprisingly found that the highest bulk properties are found with correspondingly high total ash levels in the paper, contrary to conventional expectations in the art. Fig. 9 illustrates the bulk improvement obtained from the mineralized fibers according to the present disclosure. The degree of mineralization was 10% and 25% compared to the fibers alone. It may be advantageous to have a degree of mineralization of greater than 12% (i.e., greater than 12% surface mineralized organic fibers based on total fiber content). For example, embodiments of the present disclosure may have tissue products manufactured with a degree of mineralization of about 20% to about 70% by surface mineralized organic fibers comprising a total fiber content of about 20% to about 70%.
It has been observed that the softness of sanitary papers such as facial and toilet tissues is largely related to the free fibers protruding from the surface of the paper. Fig. 1 shows a photomicrograph of free fibers extending from the surface of a tissue sheet. U.S. Pat. No. 4,300,981 discloses the results of a bulk test of tissue softness. The test group rated each tissue as "softer" as the number of free fibers at the surface increased.
It has been observed that the surface mineralized fibers of the present disclosure may be used to increase the number of free fibers at the tissue surface. While not wishing to be bound by any particular theory, it is believed that the enhanced stiffness of the individual mineralized fibers prevents the unmineralized fibers from forming natural hydrogen bonds and instead is provided in the form of free fibers, which impart structural integrity to the paper. Although this is counterintuitive, in this way the stiffer mineralized fibers contribute to the overall increase in softness of the bulk tissue. Referring to fig. 8A and 8B, it can be seen that increased free fiber is obtained in tissue products having surface mineralized fibers as compared to precipitated calcium carbonate added to tissue products by conventional methods. In the embodiment of fig. 8A and 8B, the fibers used are eucalyptus fibers. In the conventionally prepared sample of fig. 8A, the precipitated calcium carbonate is present in an amount of 20% and the fiber is present in an amount of 80%, based on the total weight of the composition. The conventional sample of fig. 8A has an ash content of 10.7%. In contrast, the composition according to the present disclosure (fig. 8B) comprised 50% surface mineralized fibers and 50% eucalyptus natural fibers. The surface mineralized fibers are prepared by the disclosed method to have a calcium carbonate shell around the eucalyptus fibers and calcium carbonate is infiltrated into the fibers, which are entrained with the calcium carbonate. The ash content of the composition was 32.4%.
Manufacturing method
A method of making surface-mineralized organic fibers may include mixing fibers with sodium carbonate to form a fiber slurry. In embodiments, the fiber may be an aqueous slurry and the sodium carbonate source may be green liquor. In embodiments, the sodium carbonate may be provided in the form of an aqueous solution. In an embodiment, the sodium carbonate source may be Na 2 CO 3 /Na 2 S/H 2 A mixture of O. Adding anhydrous CaO to the fiber slurry until the stoichiometric amount of CaO is less than the amount of sodium carbonate (Na) required for complete reaction of CaO with sodium carbonate 2 CO 3 ) The stoichiometric amount of (a). The resulting mixture is mixed for a sufficient time to substantially complete the causticization reaction (1). When green liquor or Na is used 2 CO 3 /Na 2 S/H 2 Other mixtures of O, the causticizing reaction is as follows.
The causticizing reaction results in the coating of the fibers with calcium carbonate (surface mineralized fibers), free calcium carbonate and NaOH/Na 2 S/H 2 O, which is the composition of white liquor. In embodiments where sodium carbonate is used instead of green liquor, naOH is a by-product. The method may further comprise separating the surface mineralized fibers from the sodium hydroxide or white liquor and excess calcium carbonate. This can be achieved, for example, by passing the resulting mixture from the causticizing reaction through a screen. The collected surface-mineralized fibers may then be washed with water to separate any remaining excess calcium carbonate. The washed surface mineralized fibers may then be collected. As detailed below, in embodiments, the method may be performed as part of a kraft process of a pulp mill, which may allow for white liquor, excess calcium carbonate, and weak wash to be recycled to the kraft process.
In embodiments, the method may further comprise scraping a portion of the calcium carbonate shell from the surface of the surface-mineralized organic fibers. Without wishing to be bound by theory, it is believed that scraping off a portion of the calcium carbonate shell may improve fiber-to-fiber bonding when used as a filler. The scraping can be performed to remove a portion of the calcium carbonate without adversely affecting the bending stiffness of the surface mineralized fibers.
The methods of making surface-mineralized organic fibers disclosed herein may allow for the rapid formation of mineralized fiber composites to limit the loss of unreacted soluble ions by recycling them back into the process for reuse. As is well known in the art, the precipitation of Precipitated Calcium Carbonate (PCC) in the presence of cellulose pulp fibers is an essentially inefficient process because the viscosity of an aqueous slurry of pulp fibers is very high if the fibers are present in an amount greater than about 1 weight percent. This high viscosity disadvantageously prevents calcium (Ca) from being added to the slurry 2+ ) Ions with dissolved Carbonate (CO) 3 2- ) Ion free contact; this contact is necessary for the precipitation of calcium carbonate. This slows the kinetics of the reaction and causes the throughput in the reactor to become unacceptably low. In addition, since the amount of fiber in the reactor determines the amount of mineral that can attach to and cover its surface, the effective amount of composite material present in the reactor at the completion of the reaction is necessarily low, resulting in low product yield.
It has been advantageously found that controlling the process parameters may allow coating of calcium carbonate to form a shell structure, as opposed to conventional processes in which calcium carbonate is only attached to the surface. Conventional processes are inefficient in coating the fibers and typically result in only intermittent surface attachment of the calcium carbonate on the fibers. For conventional processes, this is generally considered acceptable, as it is believed that calcium carbonate is detrimental to affect the bending stiffness of the fibers. In contrast, it has been found that a method of increasing the calcium carbonate content to form a shell structure that stiffens the fibers may be advantageous. Embodiments of the method result in calcium carbonate forming a shell structure on the outer surface of the fiber, as well as infiltrating the inner surface of the fiber.
Embodiments of the method of the present disclosure utilize processes that are typically performed in each pulp mill utilizing a kraft process. Referring to fig. 3, in a kraft process, black liquor from a pulp digester is converted to a liquor containing a high concentration of dissolved sodium carbonate (Na) 2 CO 3 ) The green liquor. The green liquor is then converted into white liquor by causticizing the green liquor with quick lime (CaO) so that the sodium carbonate is substantially converted into sodium hydroxide (NaOH, caustic). Along with the caustic soda, calcium carbonate is also precipitated. In kraft pulp mills, this calcium carbonate is called lime mud.
The process of the present disclosure may utilize a portion of the pulp fibers taken from the pulp operation (not shown in fig. 3) after the cooking and washing steps in fig. 3 and combine it with a portion of the green liquor to form a pulp slurry in the green liquor. In an embodiment, the fibers may be refined. For example, the fibers may be taken from a pulp refining operation. For example, the fiber may be refined to a level of 20SR to 90 SR. An amount of quicklime (CaO) is added to the slurry in an amount less than the stoichiometric amount required to fully react with the sodium carbonate dissolved in the green liquor. This is done in order to ensure that the entire amount of calcium introduced together with the quicklime reacts to form calcium carbonate, which precipitates and surrounds the fibres present in the pulp. The amount of fiber introduced into the green liquor and the amount of raw lime fed into the green liquor-fiber slurry are selected so that the fibers are completely entrained in the calcium carbonate mineral. For example, quicklime may be added through a screw feeder.
After the fiber-mineral composite is formed, the composite is passed through a screen and washed with water or weak wash from a pulping operation to remove any excess green liquor and any calcium carbonate that is not bound to the fibers. After the washing step, solid calcium carbonate is separated from the lye and sent to the mud kiln shown in FIG. 3. The lye fraction is sent to the process section where it is discharged from the black liquor recovery boiler to form green liquor. Referring to fig. 4, in this manner, all of the reactants and products of the process of the present disclosure are recovered, resulting in operational efficiencies not otherwise possible.
It has been found that the specific surface area of the starting fibres influences the mineralizationEfficiency, where higher specific surface area materials can achieve higher efficiencies. As used herein, mineralization efficiency refers to the percentage of total calcium carbonate produced in the reaction that is present on or in the fibers. Calcium carbonate, absent or present in the fibers, remains loose during the reaction, can be washed away and optionally recovered. FIG. 10 illustrates the use of a specific surface area of 40m 2 Mineralization efficiency ratio caused by the starting fibres per g is 4m using a specific surface area 2 The mineralization efficiency is increased per g of starting fibres. The efficiency increased significantly from 3.3% for low specific surface area fibers to 95% for high specific surface area materials. An increase in mineralization efficiency may allow for a reduction in the amount of calcium carbonate wasted in the process. Furthermore, it was found that high efficiency results in an increased amount of calcium carbonate present on or in the fibres, which advantageously increases the bending stiffness even compared to mineralized low specific surface area fibres.
The natural fibers used in the mineralization process may have a length of about 2m 2 G to about 80m 2 G, about 2m 2 G to about 10m 2 G, about 15m 2 G to about 60m 2 A,/g, about 40m 2 G to about 80m 2 Specific surface area in g. Other suitable specific surface areas include, for example, about 2m 2 /g、4m 2 /g、6m 2 /g、8m 2 /g、10m 2 /g、12m 2 /g、14m 2 /g、16m 2 /g、18m 2 /g、20m 2 /g、22m 2 /g、24m 2 /g、26m 2 /g、28m 2 /g、30m 2 /g、32m 2 /g、34m 2 /g、36m 2 /g、38m 2 /g、40m 2 /g、42m 2 /g、44m 2 /g、46m 2 /g、48m 2 /g、50m 2 /g、52m 2 /g、54m 2 /g、56m 2 /g、58m 2 /g、60m 2 /g、62m 2 /g、64m 2 /g、66m 2 /g、68m 2 /g、70m 2 /g、72m 2 /g、74m 2 /g、76m 2 /g、78m 2 G and 80m 2 And/g and the values therebetween and ranges having endpoints defined by these values.
It has been found that the incorporation of the methods of the present disclosure does not adversely affect or otherwise disrupt the kraft pulping process. In particular, the white liquor removed after the fiber-mineral composite is formed and the weak wash produced when unbound calcium carbonate is washed from the fiber-mineral composite are substantially the same composition as the white liquor and weak wash typically present in a kraft pulping process.
Examples
Preparation of sodium carbonate (Na) 2 CO 3 ) And sodium hydroxide (NaOH). This simulated green liquor is typically found in kraft pulp mills, but sodium sulfide (Na) 2 S) sodium sulfide is a component of typical kraft green liquor, since it may generate hydrogen sulfide (H) 2 S), an extremely toxic gas, no sodium sulfide was used in the laboratory scale experiments. A simulated green liquor was prepared by combining 72g of anhydrous NaOH pellets, 207g of anhydrous technical grade sodium carbonate powder and 1375g of tap water using a mechanical stirrer until a solution was formed.
1.7g of air-dried unrefined cellulose fibers were combined with 146.1g of tap water and mixed with mechanical agitation to form a slurry. The fiber slurry and simulated green liquor solution were then combined in a 4 liter glass reactor equipped with mechanical mixing blades and an electrical heating mantle and heated to about 98 ℃ with stirring at 1,000rpm.
100g of U.S. commercial quicklime was added to the reactor over a period of 100 minutes while stirring and maintaining the temperature near 100 ℃. After addition of quicklime, stirring was continued at this temperature for 50 minutes.
There is significant evaporation throughout the quicklime addition and subsequent mixing. After the reaction was completed, 1,089g of material was recovered from the reactor as a slurry of surface mineralized fibers, white liquor and calcium carbonate. It was passed through a 230 mesh screen to recover 104g of material on the screen, and the white liquor passed through the screen was collected and stored.
The material remaining on the screen was washed with 12,180g of tap water before collection. FIG. 5 is a graphical representation of the resulting surface mineralized fibers having a fiber core and a calcium carbonate shell.
Comparative example
The conventional process for precipitating calcium carbonate on fibers is as follows. Fig. 6 illustrates the results of the conventional process. Referring to fig. 5 and 6, the calcium carbonate present in conventional fibers having calcium carbonate precipitated thereon is more discretely located along the fibers than the resulting fibers of the present disclosure, and does not form a shell structure that affects bending stiffness as does the fibers of the present disclosure.
The conventional fiber having precipitated calcium carbonate of this example was prepared by adding 65 liters of water (water temperature 21 ℃ C.) to a mortar as in the conventional process. 12.5 kg of anhydrous CaO are then added and mixing is continued for 10 minutes to form lime cream [ Ca (OH) 2 ]And (4) slurry. Mixing, adding Ca (OH) 2 The slurry was poured onto a 200 mesh screen to remove the excess non-reactive components. Ca (OH) that will pass through the sieve by titration 2 The concentration of the slurry was determined to be 0.22g/ml.
Twenty (20) liters of 45 ℃ water were added to a 100 liter reactor equipped with two stirring impellers rotating at 250 rpm. To the water in the reactor was added 699.34 grams of 27.6% solids refined eucalyptus pulp (equivalent to 192.8 air dried grams). This was 1 wt% dry fiber based on dry PCC yield, after which the impeller speed was increased to 450rpm. Using a catalyst containing 20% CO 2 Air gas mixture of (2), CO 2 The contents of the reactor were bubbled at a rate of 0.49 standard cubic feet per minute (SCFM), with a corresponding air flow rate of 1.95 SCFM. Start of CO introduction 2 After gassing, milk of lime from step 3 was added to the reactor using a peristaltic pump to maintain a conductivity of 3.5 mS/cm.
Continuously adding lime milk and CO simultaneously 2 Until all lime milk has been added. At this point, the addition of CO was continued 2 Until the pH of the reactor contents was measured to be 7.0. Then the addition of CO is stopped 2 And the contents of the reactor were screened through a 200 mesh screen to separate any free calcium carbonate from the mineralized pulp fibers.
The mineralized pulp fibers remaining on the 200 mesh screen were washed with copious amounts of water to remove any unattached calcium carbonate.
A sample of the mineralized fibers was removed from the screen. Ashing at 525 ℃ for 4 hours was used to determine that the mineralized fiber composite contained 60.3% calcium carbonate.
The technical information described herein may in some aspects exceed the disclosure of the present invention, which is limited only by the appended claims. Additional technical information is provided to place the actual invention in a broader technical context, and to illustrate possible related technical developments. Such additional technical information not falling within the scope of the appended claims is not part of the present invention.
While particular embodiments of the present invention have been shown and described in detail, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects. Therefore, it is intended to cover all such alterations and modifications that fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is to be determined by the appended claims when viewed in their proper perspective based on the prior art.
Claims (16)
1. A mineralized fiber comprising:
a fiber defining a core of a surface-mineralized fiber, and
calcium carbonate surrounding the core and impregnated into the fiber, wherein the calcium carbonate increases the bending stiffness of the fiber.
2. The mineralized fiber according to claim 1, wherein the fibers have a hollow interior, and the calcium carbonate penetrates the hollow interior.
3. The mineralized fiber according to claim 1 or 2, wherein the calcium carbonate penetrates into the fiber such that at least a portion of the surface strands of the fiber are encapsulated by calcium carbonate.
4. The mineralized fiber according to any one of claims 1 to 3, wherein the fibers have a diameter of about 2m 2 G to about 80m 2 Specific surface area in g.
5. The mineralized fibers according to any one of claims 1 to 4, wherein the fibers are pulp from one or more of eucalyptus fibers, birch fibers, acacia fibers, aspen fibers, pine fibers, spruce fibers, and old corrugated cardboard recycled fibers.
6. A method of making mineralized fibers comprising:
mixing the fiber with Na 2 CO 3 Mixing to form a fiber slurry;
adding anhydrous CaO in an amount such that the stoichiometric amount of CaO is less than the stoichiometric amount of sodium carbonate present in the fiber slurry, and mixing for a period of time sufficient to react the CaO with the sodium carbonate in a causticizing reaction, thereby forming surface mineralized fibers comprising a fiber core, wherein calcium carbonate surrounds the core and penetrates into the fibers.
7. The method according to claim 6, further comprising passing the surface mineralized fibers obtained from the mixture of anhydrous CaO and fiber slurry through a screen to separate the surface mineralized fibers from excess calcium carbonate and NaOH generated during the causticizing reaction, and washing the separated surface mineralized fibers with water to remove excess calcium carbonate.
8. The method of claim 7, wherein the screen is a 230 mesh screen.
9. The method of any one of claims 6 to 8, wherein the fibers are pulp from one or more of eucalyptus fibers, birch fibers, acacia fibers, aspen fibers, pine fibers, spruce fibers, and old corrugated cardboard recycle fibers.
10. The method of any one of claims 6 to 9, wherein the fiber is pulp from a kraft pulping process and the Na is 2 CO 3 As green liquor (Na) from kraft pulping process 2 CO 3 /Na 2 S/H 2 O) is provided.
11. The method of claim 10, further comprising passing the surface mineralized fibers obtained from the mixture of anhydrous CaO and the fiber slurry through a screen to react the surface mineralized fibers with excess calcium carbonate and NaOH/Na produced during the causticizing reaction 2 S/H 2 Separating O, washing the separated surface mineralized fibers with water to remove excess calcium carbonate, and adding NaOH/Na 2 S/H 2 The O, excess calcium carbonate and collected wash solution are recycled to the kraft pulping process.
12. The method of claim 11, wherein the screen is a 230 mesh screen.
13. The method of any one of claims 6 to 12, wherein the fibers are provided as an aqueous slurry.
14. The method of any one of claims 6 to 13, wherein the fiber and NaOH/Na are mixed 2 S/H 2 O is mixed while heating to a temperature of about 70 ℃ to about 105 ℃.
15. The method according to any one of claims 6 to 14, wherein the anhydrous CaO and the fibrous slurry are mixed while maintaining a temperature of about 70 ℃ to about 105 ℃.
16. The method of any one of claims 6 to 15, wherein the fiber is refined fiber refined to a level of 20SR to 90 SR.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US202063038528P | 2020-06-12 | 2020-06-12 | |
| US63/038,528 | 2020-06-12 | ||
| PCT/US2021/036533 WO2021252572A1 (en) | 2020-06-12 | 2021-06-09 | Surface mineralized organic fibers and methods of making the same |
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| CN115768947A true CN115768947A (en) | 2023-03-07 |
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| US (1) | US20230228036A1 (en) |
| CN (1) | CN115768947A (en) |
| BR (1) | BR112022025014A2 (en) |
| CL (1) | CL2022003500A1 (en) |
| WO (1) | WO2021252572A1 (en) |
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| WO2023192172A1 (en) | 2022-03-31 | 2023-10-05 | Specialty Minerals (Michigan) Inc. | Composite fibers and methods of making the same |
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- 2021-06-09 CN CN202180042240.6A patent/CN115768947A/en active Pending
- 2021-06-09 WO PCT/US2021/036533 patent/WO2021252572A1/en active Application Filing
- 2021-06-09 BR BR112022025014A patent/BR112022025014A2/en unknown
- 2021-06-09 US US18/007,826 patent/US20230228036A1/en active Pending
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Also Published As
| Publication number | Publication date |
|---|---|
| CL2022003500A1 (en) | 2023-07-07 |
| WO2021252572A1 (en) | 2021-12-16 |
| US20230228036A1 (en) | 2023-07-20 |
| BR112022025014A2 (en) | 2022-12-27 |
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