CN110041080A - A method of preparing near-spherical hexagonal boron nitride agglomerated particle - Google Patents
A method of preparing near-spherical hexagonal boron nitride agglomerated particle Download PDFInfo
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- CN110041080A CN110041080A CN201910437359.8A CN201910437359A CN110041080A CN 110041080 A CN110041080 A CN 110041080A CN 201910437359 A CN201910437359 A CN 201910437359A CN 110041080 A CN110041080 A CN 110041080A
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
- C04B35/583—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on boron nitride
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
Abstract
The present invention relates to the manufacturing method of a kind of near-spherical hexagonal boron nitride agglomerated particle and the agglomerated particle, further illustrate to be related to near-spherical particle made of being reunited as hexagonal boron nitride primary particle and preparation method thereof.The present invention passes through centrifugal granulating technology, it provides a kind of with good mechanical stability, density is between spray drying process and briquetting method agglomerated particle, boron nitride agglomerated particle of the intensity close to briquetting method agglomerated particle, microscopic appearance is near-spherical, and the boron nitride primary particle for constituting agglomerated particle is in the structure of the coated layer by layer different from spray drying process and briquetting method agglomerated particle.Route of the invention is easy to operate, and occupied area is small, and dust is low, compared with spray drying process, the advantage of the invention is that not needing expensive spray drying device, spray drying process is all significantly lower than to the consumption of land occupation, the energy etc., no matter all there is advantage in production capacity, maintenance and environmental protection.
Description
Technical field
The present invention relates to a kind of methods for preparing near-spherical hexagonal boron nitride agglomerated particle.
Background technique
Hexagonal boron nitride has the laminar structured of similar graphite, so that hexagonal boron nitride has good thermal conductivity, electricity
A variety of excellent in performance such as insulating properties, high temperature oxidation resisting and self-lubrication are led in high temperature lubricating, high-temperature insulation, heat conduction and heat radiation etc.
Domain is all widely used.At the same time, lamellar structure is but also hexagonal boron nitride has anisotropy.In thermally conductive field, by
In this anisotropy of hexagonal boron nitride, 400W/mK is reached in the thermal conductivity for being parallel to lamella direction but perpendicular to lamella
The thermal conductivity in direction is only 2W/mK, when hexagonal boron nitride is filled into plastics or rubber as heat-conducting insulation material, is being filled out
The direction of platelet boron nitride can be slowly consistent with the flow direction of material in process during filling, i.e. generation " orientation ",
Causing material, heating conduction is different in all directions, and obvious deterioration occurs especially on the direction perpendicular to orientation, influences
The use of material.
To this problem, a kind of current thinking is to prepare nanoscale boron nitride, reduces the generation being orientated in filling process
Degree achievees the purpose that produce the material that thermal conductivity is uniform in all directions.But common melamine-industrial at present
It is highly difficult that boric acid high-temperature sintering process is directly burnt into nanoscale boron nitride, is easily agglomerated into micron order boron nitride；If reducing firing temperature
Degree, which mitigates, reunites, then the boron nitride heating conduction generated is obviously deteriorated；If being broken into nm-class boron nitride by high temperature sintering boron nitride powder,
Equipment cost can be then greatly improved, and production capacity can be restricted by speed is crushed, and purity can decline, it is difficult to reach thermally conductive field
Requirement.
Another thinking is to prepare the boron nitride second particle as made of the hexagonal boron nitride piece reunion in various directions, i.e.,
By about 1-10 μm of partial size of boron nitride primary particle of high―temperature nuclei, formed by the methods of chemistry, machinery tens of to hundreds of micro-
The hexagonal boron nitride agglomerate particle of rice.Since this aggregate is piled up by the platelet boron nitride in various directions,
The particle all directions heating conduction of composition is close to uniform.United States Patent (USP) US Pat.No.5898009 and US
Pat.No.6048511 uses briquetting method, by powdery boron nitride briquet, obtains boron nitride No yield point by a series of processing
Particle；United States Patent (USP) US Pat.No.6713088 uses spray drying process, and slurry is made in powdered boron nitride, water and bonding agent
Material is atomized balling-up, the boron nitride globular powder assembled with spray dryer；Mitsubishi chemical industry patent CN201610367841 will
The higher boron nitride powder of boron oxide content, surfactant, bonding agent, mixed solvent etc. are mixed into slurry, are being spray-dried
Balling-up in machine is sintered at high temperature into the boron nitride particle of aggregation later.Japanese water island alloy patent CN201380031031 is by powder
Shape boron nitride, boron carbide and bonding agent, water mixing, are granulated under spray dryer, are nitrogenized in nitriding furnace later
Boron aggregation；Hexagonal boron nitride powder, boron oxide, carbon dust are mixed and are pressed by Showa electrician's patent CN201680043477.5
Type nitrogenizes in nitriding furnace.It is broken into suitable partial size and obtains boron nitride aggregate.
Briquetting method is commonly available the biggish aggregate boron nitride of density, and intensity is higher, and microscopic appearance is usually irregular,
Boron nitride primary particle, which is showed, is mutually compressed chimeric state by high pressure effect；The boron nitride aggregate that spray drying process obtains
Density is lower, and microscopic appearance is mostly spherical, and it is primary also to will appear hemispherical, broken related pattern, the boron nitride such as spherical sometimes
Particle shows the structure that sheet is staggeredly interted, and intensity is lower, is easily broken into powder.Further, since the lamella knot of boron nitride
The binding force of structure, layer and layer is very low, therefore briquetting method needs very big pressure that could compress boron nitride, and breaking in the later period
During quick short steps are rapid, since shattering process contains grinding and peeling effect with being difficult to avoid that, the very big powder of ratio, therefore briquetting method can be generated
Overall efficiency it is not high.Although spray drying process can obtain satisfactory aggregate, equally by being accurately controlled
Equipment bulky complex is expensive under production capacity, and operation and maintenance are all very complicated, matches to the public works such as water, electricity, heat and dedusting etc. and is arranged
Standby requirement is relatively high.
Patent CN102219232A discloses a kind of efficient dense spherical agglomerated particle and preparation method thereof of Superfine Boron Powder:
It will be added in ball grinder after the processing of Superfine Boron Powder vacuum drying, add bonding agent, diluent and function additive, ball milling in proportion
Slurry is prepared, 25~80 μm tiny spherical agglomerated particle is prepared using spray-drying process method, is directly drawn after heat cure processing
Enter and serves as parent nucleus in centrifugal granulator, by constantly whitewashing and powder supply, the gradually long great achievement under the multiple actions such as centrifugation, impact force
Dense spherical macro aggregate particle.Currently there has been no the reports that centrifugal granulation prepares hexagonal boron nitride near-spherical agglomerated particle.
Summary of the invention
It is an object of the invention to by centrifugal granulating technology, providing one kind has good mechanical stability, and density is being sprayed
Between mist seasoning and briquetting method agglomerated particle, boron nitride agglomerated particle of the intensity close to briquetting method agglomerated particle, microscopic appearance
For near-spherical, the boron nitride primary particle for constituting agglomerated particle is in be different from spray drying process and briquetting method agglomerated particle layer by layer
The structure of coated.
The present invention also provides a kind of process routes for preparing such aggregate, and the route is easy to operate, and occupied area is small, powder
Dirt is low, compared with spray drying process, the advantage of the invention is that expensive spray drying device is not needed, to land occupation, energy
The consumption in source etc. is all significantly lower than spray drying process, no matter all has advantage in production capacity, maintenance and environmental protection.
The purpose of the present invention can be achieved through the following technical solutions:
A method of preparing near-spherical hexagonal boron nitride agglomerated particle, comprising the following steps:
(1) adhesive solution is prepared；
(2) powdered hexagonal boron nitride and adhesive solution are mixed in centrifugal granulator, obtains the nitridation of near-spherical
Boron agglomerate particle；
(3) obtained boron nitride agglomerate particle is dried, the boron nitride agglomerate particle after being dried；
(4) the boron nitride agglomerate particle after drying is sintered at high temperature, obtains the near-spherical boron nitride of different-grain diameter
Agglomerate mixture；
(5) obtained near-spherical boron nitride agglomerate mixture is classified, obtains the near-spherical of different grain size rank
Hexagonal boron nitride agglomerated particle obtains the near-spherical hexagonal boron nitride agglomerated particle product of different grain size rank after packing respectively；
(6) to the powdered boron nitride less than 45 μm obtained after classification, centrifugal granulator is returned to after being collected
As master batch, next group granulation is carried out.
The purity of powdered hexagonal boron nitride is 94.0~99.4% in the step (2), and partial size is 1~30 μm, compares table
Area is 1~30m2/g。
The bonding agent selection water-soluble high-molecular substance, including but not limited to polyethylene glycol 10000, gather PVP K30
Vinyl alcohol 088-20, sodium carboxymethylcellulose, the concentration of adhesive solution are 0.5~5.0%.
The running parameter of centrifugal granulator is in the step (2), and centrifugal rotational speed is 120~250rpm；It is bonded agent flux
For 5~15kg/h；Adhesive solution atomizing pressure 0.7MPa；Granulation time is (0.15~0.75) h；Air blast wind speed is constant, temperature
Degree is room temperature.
Boron nitride agglomerate particle drying temperature is 100~180 DEG C, time 12h in the step (3), the step (4)
The sintering temperature of middle boron nitride agglomerate particle is 1200~1900 DEG C, keeps the temperature 12h.
The more excellent purity of raw material used is (94.0~99.4) %, and more excellent is (96.0~99.4) %, and optimal is (98.0
~99.4) %.Except this range, hexagonal boron nitride aggregate can in sintering step later, due to the volatilization of impurity,
The transformation of boron nitride crystallographic configurations and generate hole, the intensity of obtained aggregate can be substantially reduced, in addition sintering after collapse again
Solve Cheng Fenmo.
The more excellent partial size of raw material used is (1~30) μm, and more excellent is (3~20) μm, and optimal is (5~15) μm.It is too small
Partial size generally mean that more impurity or higher cost, excessive partial size is then more readily formed in centrifugal granulating step
Biggish aggregate is more difficult to form lesser aggregate simultaneously.
The more excellent specific surface area of raw material used is (1~30) m2/ g, more excellent is (5~20) m2/ g, optimal is (8~15)
m2/g.Although the specific surface area size of raw material influences less the performance indicator of agglomerated particle, above range covers substantially
The common market demand uses boron nitride except this range as raw material, it will usually lead to poor Market Feedback.
The present invention does not have special limitation to mixing apparatus.
Substance as the bonding agent of the invention used is water-soluble high-molecular compound, and specific type is more, including
Polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose etc., solvent are water-soluble for that can dissolve
The solvent, including water, methanol, ethyl alcohol, isopropanol etc. of property high-molecular compound.
As the concentration for the adhesive solution that the present invention uses, difference due to bonding agent type used, the degree of polymerization are different.
The more excellent concentration of wiring solution-forming is (0.5~5.0) %, and more excellent is (1.0~4.0) %, and optimal is (2.0~3.0) %.Overrich
Solution is difficult to spray and be easy during centrifugal granulating plug nozzle, and the partial size of granulation is easy bigger than normal, while the content mistake of carbon
Height is easy to appear carbon residue in follow-up sintering technique, influences product purity and appearance, solution concentration is too low and is difficult to be formed biggish
Particle.
The present invention is granulated using centrifugal granulator, centrifugal granulator include for powder equipment, spray system, revolving bed,
The components such as blower system, dust pelletizing system.The raw material mixed is added to for powder equipment, while adhesive solution is pumped into spray
In liquid system, suitable revolving bed revolution is adjusted, revolution is related with centrifugal granulator processing capacity.The range of revolution is more excellent to be
(120~250) rpm, more excellent is (160~240) rpm, and optimal is (180~220) rpm.Too fast revolution will lead to raw material quilt
It is thrown in rotation bed wall, and due to hexagonal boron nitride coefficient of friction very little itself, is easy on revolving bed under high revolution
Sliding, to be difficult to obtain granular boron nitride aggregate.Revolving speed is too low, then will affect granulation speed, and easy to form
Big agglomerate.
Equally, the flow of adhesive solution is also related to the processing capacity of centrifugal granulator, and excessive flow will lead to nitrogen
Change boron agglomerate particle it is bigger than normal, while in particle bonding agent content it is higher, more carbon can be introduced, give subsequent processing band
Come difficult.Too small flow will affect granulation speed, while be unfavorable for particle growth.In the present invention, it is bonded the model of agent flux
Enclosing more excellent is (5~15) kg/h, and more excellent is (8~12) kg/h, and optimal is (9~10) kg/h.
Centrifugal granulator used in present embodiment belongs to intermittent apparatus, the view choosing per a batch of centrifugal granulating time
Depending on the specification of centrifugal granulator.The more excellent centrifugal granulating time range of every batch of is (0.15~0.75) h, more excellent to be
(0.20~0.60) h, optimal is (0.25~0.50) h.
After centrifugal granulating step, obtained near-spherical hexagonal boron nitride agglomerate particle contain a certain amount of water or other
Solvent, and intensity is lower, therefore following step is to dry agglomerate particle.It is not special to the equipment of drying
Limitation, by furnace drying method well known in the art.The more excellent temperature range of drying is (100~180) DEG C, and more excellent is (120
~160) DEG C, optimal is (140~150) DEG C.
Next the near-spherical hexagonal boron nitride agglomerate particle after drying is sintered.Bonding agent during the sintering process
Crack at high temperature, generate volatile small molecule substance and a small amount of carbon residue, the micro amount of oxygen effect in carbon residue and boron nitride and
It removes.Meanwhile the mutual phase sintering of sheet hexagonal boron nitride of boron nitride aggregate is constituted, the reticular structure interpenetrated is formed, is obtained
To the hexagonal boron nitride agglomerate particle for having some strength, the pattern of near-spherical is maintained, and high-temperature process can be with
The thermal conductivity for improving boron nitride aggregate, is more suitable for the application in thermal conductive polymer field, sintering temperature it is more excellent for (1200~
1900) DEG C, more excellent is (1400~1800) DEG C, and optimal is (1600~1700) DEG C；The atmosphere of sintering is vacuum or inert gas
Such as nitrogen, argon gas, soaking time 12h.
After sintering, due to the phenomenon that unavoidably having agglomeration, sintering crushing, sintered boron nitride
Grain has a variety of different granularities, from the powder that fragmentation is several microns to adhesion at several millimeters of soft aggregate, therefore also needs
Grading is carried out, to obtain the boron nitride aggregate of various different-grain diameter ranges.There do not have to the level interval of classification to be special
Limitation.Common level interval are as follows: partial size is greater than 830 μm (20 mesh), (425~830) μm (20~35 mesh), (120~425) μm
(35~120 mesh), (45~120) μm (120 mesh~325 mesh), and the powder less than 45 μm.To classification, equipment used does not have
Special limitation, by stage division well known in the art.Boron nitride agglomerated particle after classification is packed, can be obtained
To the near-spherical hexagonal boron nitride agglomerated particle product of different grain size rank.
To the boron nitride powder less than 45 μm obtained after classification, back to centrifugal granulator as female after being collected
Grain carries out next group granulation.
Beneficial effects of the present invention:
This agglomerated particle for synthesizing clearly had not only been able to satisfy the uniform thermal conductivity of all directions, but also had lower density and higher
Intensity can not be crushed during mechanical mixture, while not when as polymer fillers such as heat-conducting plastic, heat conductive rubbers
It is orientated, there is consistent heating conduction in all directions, there is many superiority.The ball for the agglomerated particle that the present invention obtains
Shape degree is better than the aggregate that briquetting method obtains, while lower grain density can also be with the weight of lightening material and briquetting method
It compares, it is more advantageous.It is compared with spray granulation, the present invention can obtain bigger agglomerated particles, while comparing mist projection granulating
Obtained boron nitride aggregate is more closely knit, less easily broken when mixing to plastics, rubber etc..
Specifically from technological angle, the present invention uses centrifugal granulating technology, can will be difficult to the six of directly obtained granular product
Square boron nitride processing is the hexagonal boron nitride near-spherical agglomerated particle of different particle size distribution.Obtained particle purity is high, and granularity is equal
One, good sphericity, all directions it is thermally conductive uniformly.There is good intensity again simultaneously, medium density is added to plastics, rubber etc.
When it is non-breakable, while will not excessively increase the weight of heat-conducting plastic, heat conductive rubber again.Have apparent technology excellent in this field
Gesture.
From equipment angle, the present invention uses centrifugal granulator, and granulation speed is fast, and sphericity is high, and dust is low, the use of additive
Precisely, material and energy consumption are all lower, and granulation process does not need the size tunable for heating, obtaining, uniformly for amount；To boron nitride particle into
Row high temperature sintering increases the intensity of particle while not destroying grain shape and eliminates bonding agent, improves reunion
The purity of particle obtains the aggregate of different-grain diameter after classification, be suitable for meeting the needs of different manufacturers, while can also separate back
Receive the powder peeled off after sintering.The present invention is not necessarily to expensive briquetting apparatus or spray drying device, and process is short, equipment investment
Few, occupied area is small, and repair and maintenance is convenient, and dust is low, and noise is small, environmental-friendly.
Detailed description of the invention
In order to facilitate the understanding of those skilled in the art, the present invention will be further described below with reference to the drawings.
Fig. 1 is the flow diagram of the method for the invention；
Fig. 2 is the scanning electron microscope for the hexagonal boron nitride agglomerated particle prepared using the method for the invention
(SEM) figure；
Fig. 3 is the scanning electron microscope for the single agglomerated particle of hexagonal boron nitride prepared using the method for the invention
(SEM) figure.
Specific embodiment
Embodiment 1
5.0kg hexagonal boron nitride raw material is taken, the median of raw material is 10 μm, specific surface area 10m2/ g, purity are
99.4%, by the centrifugal granulator of above-mentioned boron nitride raw feeding revolving bed diameter 1000mm in powder equipment.Adjustment centrifugation
Pelletizer revolving bed revolving speed is 180rpm.Polyvinyl alcohol 088-20 powder is dissolved under stiring in 2.5kg water, poly- second is made into
3% solution of enol, is sent in revolving bed by peristaltic pump, and adjustment peristaltic pump rate of pumping is 10kg/h, and compressed air is used in atomization
Air pressure 0.7MPa, air blast wind speed is constant, and temperature is room temperature, is granulated 0.5 hour under the above parameter.
Terminate to discharge after being granulated, is fitted into enamel tray, is dried 12 hours in 160 DEG C of baking ovens, six sides after being dried
Boron nitride agglomerate particle.
Above-mentioned aggregate is fitted into the graphite crucible coated in advance with boron nitride, is sent into heating furnace, under nitrogen protection 6
It is warming up to 1800 DEG C in hour, keeps the temperature 12 hours, naturally cools to room temperature.
Above-mentioned aggregate feeding vibrating screen is classified, obtains partial size greater than 830 μm of (20 mesh), (425~830) μm
(20~35 mesh), (120~425) μm (35~120 mesh), (45~120) μm (120 mesh~325 mesh) different stage class ball
Shape boron nitride agglomerate particle, and less than the powder of 45 μm (325 mesh), become near-spherical hexagonal boron nitride by packaging and reunite
Grain products.
Powder returns to centrifugal granulator, participates in next batch as master batch and is granulated.
Embodiment 2
5.0kg hexagonal boron nitride raw material is taken, the median of raw material is at 20 μm, and specific surface area is in 2m2/ g, purity exist
99.4%, above-mentioned boron nitride raw is sent into making in powder equipment, adjusting centrifugation for revolving bed diameter 1000mm centrifugal granulator
Grain machine revolving bed revolving speed is 220rpm；Polyvinyl alcohol 088-20 powder is dissolved under stiring in 2.0kg water, it is molten to be made into 3%
Liquid is sent in revolving bed by peristaltic pump, and adjustment peristaltic pump rate of pumping is 8kg/h, is atomized and is used compressed air air pressure 0.7MPa,
Air blast wind speed is constant, and temperature is room temperature.It is granulated 0.5 hour under the above parameter.
Terminate to discharge after being granulated, is fitted into enamel tray, is dried 12 hours in 150 DEG C of baking ovens, six sides after being dried
Boron nitride agglomerate particle.
Above-mentioned aggregate is fitted into the graphite crucible coated in advance with boron nitride, is sent into heating furnace, under nitrogen protection 6
It is warming up to 1600 DEG C in hour, keeps the temperature 12 hours, naturally cools to room temperature.
Above-mentioned aggregate feeding vibrating screen is classified, obtains partial size greater than 830 μm of (20 mesh), (425~830) μm
(20~35 mesh), (120~425) μm (35~120 mesh), (45~120) μm (120 mesh~325 mesh) different stage class ball
Shape boron nitride agglomerate particle, and less than the powder of 45 μm (325 mesh), become near-spherical hexagonal boron nitride by packaging and reunite
Grain products.
Powder returns to centrifugal granulator, participates in next batch as master batch and is granulated.
Embodiment 3
5.0kg hexagonal boron nitride raw material is taken, the median of raw material is at 4 μm, and specific surface area is in 16m2/ g, purity exist
99.0%.By above-mentioned boron nitride raw feeding revolving bed diameter 1000mm centrifugal granulator in powder equipment.Adjustment centrifugation is made
Grain machine revolving bed revolving speed is 150rpm.PVP K30 powder is dissolved under stiring in 2.5kg water, 4% solution is made into, by
Peristaltic pump is sent in revolving bed, and adjustment peristaltic pump rate of pumping is 7.5kg/h, atomization compressed air air pressure 0.7MPa, drum
Wind wind speed is constant, and temperature is room temperature.It is granulated 0.4 hour under the above parameter.
Terminate to discharge after being granulated, is fitted into enamel tray, is dried 12 hours in 120 DEG C of baking ovens, six sides after being dried
Boron nitride agglomerate particle.
Above-mentioned aggregate is fitted into the graphite crucible coated in advance with boron nitride, is sent into heating furnace, under nitrogen protection 6
It is warming up to 1800 DEG C in hour, keeps the temperature 12 hours, naturally cools to room temperature.
Above-mentioned aggregate feeding vibrating screen is classified, obtains partial size greater than 830 μm of (20 mesh), (425~830) μm
(20~35 mesh), (120~425) μm (35~120 mesh), (45~120) μm (120 mesh~325 mesh) different stage class ball
Shape boron nitride agglomerate particle, and less than the powder of 45 μm (325 mesh), become near-spherical hexagonal boron nitride by packaging and reunite
Grain products.
Powder returns to centrifugal granulator, participates in next batch as master batch and is granulated.
Embodiment 4
5.0kg hexagonal boron nitride raw material is taken, the median of raw material is at 9 μm, and specific surface area is in 18m2/ g, purity exist
95%.By above-mentioned boron nitride raw feeding revolving bed diameter 1000mm centrifugal granulator in powder equipment.Adjust centrifugal granulating
Machine revolving bed revolving speed is 180rpm.Sodium carboxymethylcellulose powder is dissolved under stiring in 2.5kg water, 2% solution is made into,
It is sent in revolving bed by peristaltic pump, adjustment peristaltic pump rate of pumping is 10kg/h, atomization compressed air air pressure 0.7MPa, drum
Wind wind speed is constant, and temperature is room temperature.It is granulated 0.5 hour under the above parameter.
Terminate to discharge after being granulated, is fitted into enamel tray, is dried 12 hours in 120 DEG C of baking ovens, six sides after being dried
Boron nitride agglomerate particle.
Above-mentioned aggregate is fitted into the graphite crucible coated in advance with boron nitride, is sent into heating furnace, under protection of argon gas 6
It is warming up to 1700 DEG C in hour, keeps the temperature 12 hours, naturally cools to room temperature.
Above-mentioned aggregate feeding vibrating screen is classified, obtains partial size greater than 830 μm of (20 mesh), (425~830) μm
(20~35 mesh), (120~425) μm (35~120 mesh), (45~120) μm (120 mesh~325 mesh) different stage class ball
Shape boron nitride agglomerate particle, and less than the powder of 45 μm (325 mesh), become near-spherical hexagonal boron nitride by packaging and reunite
Grain products.
Powder returns to centrifugal granulator, participates in next batch as master batch and is granulated.
To sum up embodiment, the application have produced near-spherical boron nitride agglomerated particle, obtained group by centrifugal granulating technology
The density (medium) of poly- particle, sphericity (middle height), the constituted mode (stratiform adherency) of surface particle are (close with spray granulation
Low, sphericity height is spent, constituted mode sheet is interspersed) and briquetting method (density is high, and sphericity is low, and constituted mode high pressure compresses)
To product have significant difference；Granulation conditions are mild (to be not necessarily to high temperature (spray granulation is at 200 DEG C or more) or high pressure (briquetting method
Need tens of megapascal high pressures)), equipment requirement and O&M requirement are low (without spray dryer and isostatic pressing machine, centrifugal granulator dimension
Shield is convenient, cheap under same production capacity).
Present invention disclosed above preferred embodiment is only intended to help to illustrate the present invention.There is no detailed for preferred embodiment
All details are described, are not limited the invention to the specific embodiments described.Obviously, according to the content of this specification,
It can make many modifications and variations.These embodiments are chosen and specifically described to this specification, is in order to better explain the present invention
Principle and practical application, so that skilled artisan be enable to better understand and utilize the present invention.The present invention is only
It is limited by claims and its full scope and equivalent.
Claims (5)
1. a kind of method for preparing near-spherical hexagonal boron nitride agglomerated particle, which comprises the following steps:
(1) adhesive solution is prepared；
(2) powdered hexagonal boron nitride and adhesive solution are mixed in centrifugal granulator, obtains the boron nitride group of near-spherical
Interpolymer particles；
(3) obtained boron nitride agglomerate particle is dried, the boron nitride agglomerate particle after being dried；
(4) the boron nitride agglomerate particle after drying is sintered at high temperature, the near-spherical boron nitride for obtaining different-grain diameter is reunited
Body mixture；
(5) obtained near-spherical boron nitride agglomerate mixture is classified, obtains six side of near-spherical of different grain size rank
Boron nitride agglomerated particle obtains the near-spherical hexagonal boron nitride agglomerated particle product of different grain size rank after packing respectively；
(6) to the powdered boron nitride less than 45 μm obtained after classification, centrifugal granulator conduct is returned to after being collected
Master batch carries out next group granulation.
2. a kind of method for preparing near-spherical hexagonal boron nitride agglomerated particle according to claim 1, which is characterized in that institute
State powdered hexagonal boron nitride in step (2) purity be 94.0~99.4%, partial size be 1~30 μm, specific surface area be 1~
30m2/g。
3. a kind of method for preparing near-spherical hexagonal boron nitride agglomerated particle according to claim 1, which is characterized in that institute
It states bonding agent and selects water-soluble high-molecular substance, including but not limited to polyethylene glycol 10000, PVP K30, polyvinyl alcohol 088-
20, sodium carboxymethylcellulose, the concentration of adhesive solution are 0.5~5.0%.
4. a kind of method for preparing near-spherical hexagonal boron nitride agglomerated particle according to claim 1, which is characterized in that institute
The running parameter for stating centrifugal granulator in step (2) is that centrifugal rotational speed is 120~250rpm；Bonding agent flux is 5~15kg/
h；Adhesive solution atomizing pressure 0.7MPa；Granulation time is (0.15~0.75) h；Air blast wind speed is constant, and temperature is room temperature.
5. a kind of method for preparing near-spherical hexagonal boron nitride agglomerated particle according to claim 1, which is characterized in that institute
Stating boron nitride agglomerate particle drying temperature in step (3) is 100~180 DEG C, time 12h, boron nitride group in the step (4)
The sintering temperature of interpolymer particles is 1200~1900 DEG C, keeps the temperature 12h.
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