CN116876068A - Preparation method of calcium sulfate whisker and calcium sulfate whisker - Google Patents

Preparation method of calcium sulfate whisker and calcium sulfate whisker Download PDF

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Publication number
CN116876068A
CN116876068A CN202310667389.4A CN202310667389A CN116876068A CN 116876068 A CN116876068 A CN 116876068A CN 202310667389 A CN202310667389 A CN 202310667389A CN 116876068 A CN116876068 A CN 116876068A
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whisker
calcium sulfate
sulfate whisker
natural fiber
crystal
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罗新峰
周国华
漆鸿飞
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Jiangxi Fengzhu New Material Technology Co ltd
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Jiangxi Fengzhu New Material Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B1/00—Single-crystal growth directly from the solid state
    • C30B1/12—Single-crystal growth directly from the solid state by pressure treatment during the growth
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
    • C30B29/62—Whiskers or needles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

The invention discloses a preparation method of calcium sulfate whisker and the calcium sulfate whisker, the method comprises the following steps: preparing a soaking solution, placing natural fiber gypsum into the soaking solution, heating to a preset temperature, and soaking for a preset time; taking out the natural fiber gypsum, scattering the crystal directional growth guiding agent with the set mass ratio, putting the crystal directional growth guiding agent into an autoclave for the growth under the set conditions after the crystal directional growth guiding agent is arranged on the surface layer of the natural fiber gypsum. Timely crushing the grown natural fiber gypsum at a set temperature to form cotton wool, and collecting the cotton wool by a hot air winnowing mode to obtain initial whiskers; and (3) removing residual crystal water from the initial whisker through high-temperature calcination to obtain the high-length-diameter calcium sulfate whisker without any crystal water. The invention solves the problems of low length-diameter ratio of the calcium sulfate whisker and incomplete whisker structure in the prior art.

Description

Preparation method of calcium sulfate whisker and calcium sulfate whisker
Technical Field
The invention relates to the technical field of inorganic whisker material preparation, in particular to a preparation method of calcium sulfate whiskers and the calcium sulfate whiskers.
Background
The calcium sulfate whisker is fibrous or needle-shaped monocrystal, and has the advantages of high temperature resistance, chemical corrosion resistance, extremely high tensile strength and elastic modulus, strong affinity with polymers such as rubber, plastics and the like, strong flame retardance, no toxicity and the like. Belongs to gypsum series products with high performance and high added value. The material is widely applied to the fields of friction materials, rubber, plastics, PVC and the like, is a green environment-friendly material with excellent performance, has good application prospect in the aspects of reinforcing materials, environment materials, improving asphalt softening temperature and the like, and has huge market potential.
At present, the existing preparation methods of the calcium sulfate whisker at home and abroad mainly comprise a hydrothermal method and an ordinary pressure acidification method. As the preparation of the calcium sulfate whisker by the normal pressure acidification method is carried out in a strong acid medium, the requirements on the corrosion resistance of production equipment are high, and the environmental protection problem in the production process is solved, the report on the large-scale industrial production of the calcium sulfate whisker by the normal pressure acidification method is not yet seen at present.
The preparation method for industrially producing the calcium sulfate whisker mainly takes natural gypsum as a raw material, and adopts a hydrothermal method to prepare the calcium sulfate whisker. Water acts as a chemical component and participates in the reaction, and water is both a solvent and a bulking promoter, and can also act as a pressure transmission medium. But the solubility of the gypsum in water is extremely low, the formation and modification of whiskers are realized by virtue of physical and chemical factors of accelerating dialysis reaction and controlling process by means of a high-pressure reaction kettle, and the production cost is high. And the problems of low aspect ratio of the whisker, incomplete whisker structure and the like caused by difficult directional complete growth of the crystal are solved, and the requirements of the fields of friction materials, engineering plastics and the like on the reinforcing effect of the inorganic whisker are difficult to meet.
Disclosure of Invention
Therefore, the invention aims to solve the problems of low aspect ratio of the whisker and incomplete whisker structure in the prior art.
The embodiment of the invention is realized as follows:
a method of preparing a calcium sulfate whisker, the method comprising:
acetic acid, fatty alcohol polyoxyethylene ether, wood calcium and water are fully and uniformly stirred according to a preset mass ratio to obtain a soaking solution;
placing natural fiber gypsum crushed into massive particles with preset particle size into the soaking solution, heating to a preset temperature, and soaking for a preset time;
taking out the soaked natural fiber gypsum, scattering a crystal directional growth guiding agent with a set mass ratio, putting the crystal directional growth guiding agent into an autoclave after the surface layer of the natural fiber gypsum is formed, and carrying out growth under set conditions;
timely crushing the grown natural fiber gypsum at a set temperature to form cotton wool, lightly kneading powder in a kneading type pulverizer to depolymerize the whiskers, and collecting the whiskers by a hot air winnowing mode to obtain initial whiskers;
removing residual crystal water from the initial whisker through high-temperature calcination to obtain a high-length-diameter calcium sulfate whisker without any crystal water;
wherein, the soaking time is 20-24 h, and the set conditions are that the autoclave is pressurized to 0.8-1 MPa, heated to 150-200 ℃, the heating rate is controlled to 5-6 ℃/min, and the heat preservation and pressure maintaining are carried out for 6-8 h.
Further, in the preparation method of the calcium sulfate whisker, the natural fiber gypsum is selected, and is primarily crushed into blocky particles with the preset particle size, wherein the purity of the natural fiber gypsum is more than or equal to 99%, and the particle size is 2cm-20cm.
Further, in the preparation method of the calcium sulfate whisker, in the step of fully and uniformly stirring acetic acid, fatty alcohol-polyoxyethylene ether, wood calcium and water according to a preset mass ratio to obtain a soaking solution, the mass ratio is set to be 10:1:1:100.
further, in the preparation method of the calcium sulfate whisker, in the step of fully and uniformly stirring acetic acid, fatty alcohol-polyoxyethylene ether, wood calcium and water according to a preset mass ratio to obtain a soaking solution, the heating temperature is 60-80 ℃ and the soaking time is 20-24 hours.
Further, in the preparation method of the calcium sulfate whisker, the soaked natural fiber gypsum is taken out and sprinkled with a crystal directional growth guiding agent with a set mass ratio, and then the crystal directional growth guiding agent is put into an autoclave for a growth step with a set condition after being put on the surface layer of the natural fiber gypsum, wherein the crystal directional growth guiding agent is any one of calcium sulfate whisker, calcium carbonate whisker and silicon carbide whisker monocrystal inorganic fiber materials.
Further, according to the preparation method of the calcium sulfate whisker, the mass ratio of the crystal orientation growth guiding agent is set to be 0.1-0.5 wt%.
Further, in the preparation method of the calcium sulfate whisker, after the natural fiber gypsum after growth is timely crushed into cotton-like shape at a set temperature, the raw material is slightly kneaded in a kneading type pulverizer to depolymerize the whisker and is collected by a hot air winnowing mode to prepare the initial whisker, wherein the set temperature is 80-100 ℃, and the temperature of the hot air winnowing is 80-100 ℃.
Further, in the preparation method of the calcium sulfate whisker, the step of removing residual crystal water from the initial whisker through high-temperature calcination to obtain the calcium sulfate whisker with high length and diameter without any crystal water comprises the steps of calcining at 500-600 ℃ for 2-3 h.
Another object of the present invention is to provide a calcium sulfate whisker prepared by the preparation method of any one of the above calcium sulfate whiskers.
The invention prepares the soaking solution to soak, soften and loosen the natural fiber gypsum, guides the crystal to grow completely in a directional way under a certain temperature and pressure environment, and ensures CaSO 4 ·1/2H 2 Under the condition that the O whisker has enough flexibility, the structure of a single whisker is not damaged as much as possible by adopting a two-step-stage physical depolymerization mode, the uniform anhydrous calcium sulfate whisker with high length-diameter ratio is obtained after high-temperature calcination, the prepared calcium sulfate whisker has complete crystal structure, the size and the length-diameter ratio are obviously improved, the method and the process are simple, the operation is easy, the whisker growth can be more sufficient, and the problems of low length-diameter ratio and incomplete whisker structure in the prior art are solved.
Drawings
FIG. 1 is a flow chart of a method for preparing calcium sulfate whiskers according to an embodiment of the invention;
fig. 2 is a scanning electron microscope image of a whisker sample of a calcium sulfate whisker prepared by the preparation method of the calcium sulfate whisker according to an embodiment of the invention.
The invention will be further described in the following detailed description in conjunction with the above-described figures.
Detailed Description
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Furthermore, the term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. In the detailed description and claims, a list of items connected by the term "one of" may mean any of the listed items. For example, if items a and B are listed, the phrase "one of a and B" means either only a or only B. In another example, if items A, B and C are listed, one of the phrases "A, B and C" means only a; only B; or only C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements. In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" or "at least one of a or B" means only a; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" or "at least one of A, B or C" means only a; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
The invention provides a preparation method of calcium sulfate whisker, aiming at the problems of low aspect ratio and incomplete whisker structure of the existing whisker, wherein referring to fig. 1, the method comprises the following steps:
wherein the main component of the natural fiber gypsum is CaSO 4 ·2H 2 When the method is implemented, the purity of the natural fiber gypsum is more than or equal to 99%, the fiber lines are clear, and the natural fiber gypsum is primarily crushed into massive particles with the particle size of 2cm-20cm, so that the natural fiber gypsum can be grown and molded conveniently.
And step S10, fully and uniformly stirring acetic acid, fatty alcohol-polyoxyethylene ether, wood calcium and water according to a preset mass ratio to obtain a soaking solution.
Specifically, the preset mass ratio is 10:1:1:100, acetic acid, fatty alcohol polyoxyethylene ether, wood calcium and water are mixed according to the weight ratio of 10:1:1:100 are fully and uniformly stirred to prepare a soaking solution, and the soaking solution is used for soaking the natural fiber gypsum crushed into block-shaped particles.
Wherein the main component of the natural fiber gypsum is CaSO 4 ·2H 2 When the method is implemented, the purity of the natural fiber gypsum is more than or equal to 99%, the fiber lines are clear, and the natural fiber gypsum is primarily crushed into massive particles with the particle size of 2cm-20cm, so that the natural fiber gypsum can be grown and molded conveniently.
And S11, placing the natural fiber gypsum crushed into massive particles with the preset particle size into the soaking solution, heating to the preset temperature, and then soaking for the preset time.
Wherein the heating temperature is 60-80 ℃, such as 60 ℃, 70 ℃, 80 ℃ and the like, the soaking preset time is 20-24 h, such as 20h, 22h, 24h and the like, and the soaking enables the natural fiber gypsum to be softened and loosened, so as to prepare for the directional growth of the whisker.
And S12, taking out the soaked natural fiber gypsum, scattering a crystal directional growth guiding agent with a set mass ratio, and putting the natural fiber gypsum into an autoclave for growth under set conditions after the natural fiber gypsum is coated.
Wherein, the crystal orientation growth guiding agent can be any one of single crystal inorganic fiber materials such as calcium sulfate whisker, calcium carbonate whisker, silicon carbide whisker and the like, the mass ratio of the crystal orientation growth guiding agent is 0.1 to 0.5 weight percent, and the set condition is that the autoclave is pressurizedTo 0.8Mpa-1Mpa, e.g., 0.8Mpa, 0.9Mpa and 1Mpa, heating to 150-200 ℃, e.g., 150 ℃, 180 ℃ and 200 ℃, controlling the heating rate to 5 ℃/min-6 ℃/min, e.g., 5 ℃/min, 5.5 ℃/min and 6 ℃/min, maintaining the temperature and pressure for 6h-8h, e.g., 6h, 7h and 8h, of calcium sulfate crystals under the action of a guiding agent to complete the sufficient directional growth process and dehydrate to form CaSO 4 ·1/2H 2 O, at this time, the fiber gypsum raw material is soaked in advance to prepare CaSO 4 ·1/2H 2 O maintains good toughness.
And S13, timely crushing the grown natural fiber gypsum at a set temperature to form cotton wool, and then lightly kneading powder in a kneading type flour mill to depolymerize the whiskers and collecting the whiskers by a hot air winnowing mode to obtain the initial whiskers.
Specifically, the set temperature is 80-100deg.C, such as 80 deg.C, 90 deg.C and 100deg.C, the temperature of hot air separation is 100-120deg.C, such as 100deg.C, 110 deg.C and 120deg.C, for CaSO 4 ·1/2H 2 O is crushed into cotton-like shape at 80-100 ℃ in time, and then the cotton-like shape is lightly kneaded in a kneading type flour mill to depolymerize the whisker, and the CaSO is obtained by collecting the whisker through a hot air winnowing mode at 100-120 DEG C 4 ·1/2H 2 O whisker.
And S14, removing residual crystal water from the initial whisker through high-temperature calcination to obtain the high-length-diameter calcium sulfate whisker without any crystal water.
Wherein the calcination temperature is 500-600deg.C, the calcination time is 2-3 h, such as 500 deg.C, 550 deg.C and 600deg.C, the calcination time is 2-3 h, such as 2h, 2.5h and 3h, specifically CaSO 4 ·1/2H 2 The O crystal whisker is calcined at a high temperature (500-600 ℃) for 2-3 hours to remove the residual half crystal water, and the anhydrous calcium sulfate crystal whisker product with high length-diameter ratio and without any crystal water is obtained. Stirring is not performed in the high-temperature (500-600 ℃) calcination process.
On the other hand, the calcium sulfate whisker provided by the embodiment of the invention is prepared by the preparation method of any one of the calcium sulfate whiskers.
In summary, the preparation method of the calcium sulfate whisker and the calcium sulfate whisker provided by the embodiment of the invention are characterized in that the natural fiber gypsum is soaked, softened and loosened by preparing a soaking solution, the crystal is guided to grow completely in a directional manner under a certain temperature and pressure environment, and the structure of a single whisker is not damaged as much as possible by adopting a two-step grading physical depolymerization mode under the condition of ensuring that CaSO4.1/2H 2O whisker still has enough flexibility, and the uniform anhydrous calcium sulfate whisker with high length-diameter ratio is obtained after high-temperature calcination.
In order to facilitate an understanding of the invention, several embodiments of the invention will be presented below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Example 1
100Kg of natural fiber gypsum raw material is selected, and the main component is CaSO 4 ·2H 2 O (purity is more than or equal to 99%), and the fiber lines are clear. The mixture is primarily crushed into massive particles with the particle size of 2cm-20cm. Acetic acid, fatty alcohol polyoxyethylene ether, wood calcium and water are mixed according to the mass ratio of 10:1:1:100 Kg of soaking solution is prepared and fully and uniformly stirred. Placing the primarily crushed natural fiber gypsum blocks into a soaking solution, heating to 60-80 ℃ and soaking for 24 hours to soften and loosen natural fiber gypsum crystals. Taking out and spreading 100g of calcium sulfate whisker prepared in a laboratory on the surface layer of the gypsum block as a crystal directional growth guiding agent, putting the calcium sulfate whisker into an autoclave, pressurizing to 1Mpa, heating to 160 ℃, controlling the heating rate to 5 ℃/min-6 ℃/min, and preserving heat and pressure for 8 hours. Taking out, timely crushing at 100deg.C to obtain cotton-like material, slightly kneading in a kneading pulverizer to depolymerize whisker, and collecting with 100deg.C hot air to obtain CaSO 4 ·1/2H 2 O whisker. CaSO is carried out 4 ·1/2H 2 Calcining O crystal whisker at high temperature (550 ℃) for 2 hours to obtain the high length and diameterCompared with anhydrous calcium sulfate whisker products.
Example 2
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 20h.
Example 3
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22h.
Example 4
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22h, and the pressurizing pressure is 0.9Mpa.
Example 5
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22h, and the pressurizing pressure is 0.8Mpa.
Example 6
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22h, the pressurizing pressure is 0.8Mpa, and the heating temperature is 180 ℃.
Example 7
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22h, the pressurizing pressure is 0.8Mpa, and the heating temperature is 200 ℃.
Example 8
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22 hours, the pressurizing pressure is 0.8Mpa, the heating temperature is 200 ℃, and the heat preservation and pressure maintaining time is 7 hours.
Example 9
The present embodiment also provides a method for preparing a calcium sulfate whisker, which is substantially the same as the method for preparing a calcium sulfate whisker as set forth in embodiment 1, except that:
the soaking time is 22 hours, the pressurizing pressure is 0.8Mpa, the heating temperature is 200 ℃, and the heat preservation and pressure maintaining time is 6 hours.
Comparative example 1
The present comparative example also proposes a method for producing a calcium sulfate whisker, which is substantially the same as that of example 1, except that:
the calcium sulfate whisker is prepared by adopting a hydrothermal method in the prior art.
Referring to Table 1 below, the parameters corresponding to the above examples 1-9 and comparative example 1 of the present invention are shown in the following table:
TABLE 1
In practical application, the scanning electron microscope images of the above examples 1-9 and comparative example 1 were used to observe the scanning data shown in Table 2 below
TABLE 2
In summary, as is apparent from the data of tables 1 and 2 and FIG. 2, the present invention is to prepare soaking solution to soak, soften and loosen natural fiber gypsum, guide crystal to grow completely in certain temperature and pressure environment and ensure CaSO 4 ·1/2H 2 Under the condition that the O whisker has enough flexibility, the structure of a single whisker is not damaged as much as possible by adopting a two-step-stage physical depolymerization mode, the uniform anhydrous calcium sulfate whisker with high length-diameter ratio is obtained after high-temperature calcination, the prepared calcium sulfate whisker has complete crystal structure, the size and the length-diameter ratio are obviously improved, the method and the process are simple, the operation is easy, the whisker growth can be more sufficient, and the problems of low length-diameter ratio and incomplete whisker structure in the prior art are solved.
In addition, as is evident from a combination of examples 1 to 3, a reasonable soaking time has an accelerating effect on the high aspect ratio of the whiskers, since soaking softens and loosens the natural fiber gypsum crystals, prepares for whisker growth, and can make the CaSO produced 4 ·1/2H 2 O keeps good toughness, the natural fiber gypsum crystal is softened too much due to the excessively long soaking time, and the softening effect cannot be achieved due to the excessively short soaking time, wherein the soaking time is optimal for 22 hours.
It is evident from the combination of examples 3 to 5, 5 to 7 and 7 to 9 that reasonable pressurizing pressure, heating temperature and holding time promote the high aspect ratio of whisker, and that is, the crystal orientation is guided to grow completely under reasonable temperature, pressure and time environment to ensure CaSO 4 ·1/2H 2 Under the condition that the O whisker has enough flexibility, the structure of a single whisker can not be destroyed by adopting a two-step grading physical depolymerization mode, wherein the pressurizing pressure, the heating temperature and the heat preservation and pressure maintaining time are dividedThe best performance is obtained when the values are 0.8, 180 and 8 respectively.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (9)

1. A method for preparing calcium sulfate whiskers, comprising the steps of:
acetic acid, fatty alcohol polyoxyethylene ether, wood calcium and water are fully and uniformly stirred according to a preset mass ratio to obtain a soaking solution;
placing natural fiber gypsum crushed into massive particles with preset particle size into the soaking solution, heating to a preset temperature, and soaking for a preset time;
taking out the soaked natural fiber gypsum, scattering a crystal directional growth guiding agent with a set mass ratio, putting the crystal directional growth guiding agent into an autoclave after the surface layer of the natural fiber gypsum is formed, and carrying out growth under set conditions;
timely crushing the grown natural fiber gypsum at a set temperature to form cotton wool, lightly kneading powder in a kneading type pulverizer to depolymerize the whiskers, and collecting the whiskers by a hot air winnowing mode to obtain initial whiskers;
removing residual crystal water from the initial whisker through high-temperature calcination to obtain a high-length-diameter calcium sulfate whisker without any crystal water;
wherein, the soaking time is 20-24 h, and the set conditions are that the autoclave is pressurized to 0.8-1 MPa, heated to 150-200 ℃, the heating rate is controlled to 5-6 ℃/min, and the heat preservation and pressure maintaining are carried out for 6-8 h.
2. The method for preparing calcium sulfate whisker according to claim 1, wherein the purity of the natural fiber gypsum is not less than 99% and the particle size is 2cm-20cm.
3. The method for preparing calcium sulfate whisker according to claim 1, wherein in the step of fully and uniformly stirring acetic acid, fatty alcohol-polyoxyethylene ether, wood calcium and water according to a preset mass ratio to prepare a soaking solution, the mass ratio is set to be 10:1:1:100.
4. the method for preparing calcium sulfate whisker according to claim 1, wherein in the step of fully and uniformly stirring acetic acid, fatty alcohol-polyoxyethylene ether, wood calcium and water according to a preset mass ratio to prepare a soaking solution, the heating temperature is 60-80 ℃.
5. The method for preparing calcium sulfate whisker according to claim 1, wherein the crystal orientation growth guiding agent is any one of calcium sulfate whisker, calcium carbonate whisker and silicon carbide whisker monocrystal inorganic fiber material, and the crystal orientation growth guiding agent is prepared by taking out the soaked natural fiber gypsum and scattering the crystal orientation growth guiding agent with a set mass ratio, placing the crystal orientation growth guiding agent into an autoclave for setting conditions after the natural fiber gypsum is coated.
6. The method for producing a calcium sulfate whisker according to claim 1 or 5, wherein the crystal orientation growth guide is set at a mass ratio of 0.1 to 0.5wt%.
7. The method according to claim 1, wherein the initial whisker preparation step comprises the steps of crushing the natural fiber gypsum after growth into cotton-like shape at a predetermined temperature, lightly kneading the powder in a kneading mill to depolymerize the whisker, and collecting the whisker by hot air separation, wherein the predetermined temperature is 80-100 ℃, and the temperature of the hot air separation is 100-120 ℃.
8. The method according to claim 1, wherein in the step of removing the remaining crystal water from the initial whisker by high-temperature calcination to obtain the calcium sulfate whisker having a long and high diameter and containing no crystal water, the calcination temperature is 500 to 600 ℃ and the calcination time is 2 to 3 hours.
9. A calcium sulfate whisker, characterized in that the calcium sulfate whisker is prepared by the preparation method of the calcium sulfate whisker according to any one of claims 1 to 8.
CN202310667389.4A 2023-06-07 2023-06-07 Preparation method of calcium sulfate whisker and calcium sulfate whisker Pending CN116876068A (en)

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