CN100467380C - Spherical alumina particles and production process thereof - Google Patents

Spherical alumina particles and production process thereof Download PDF

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CN100467380C
CN100467380C CNB028019733A CN02801973A CN100467380C CN 100467380 C CN100467380 C CN 100467380C CN B028019733 A CNB028019733 A CN B028019733A CN 02801973 A CN02801973 A CN 02801973A CN 100467380 C CN100467380 C CN 100467380C
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alumina
sintered
microns
median size
fused
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CN1463250A (en
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神原英二
山田登美晴
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Resonac Holdings Corp
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Showa Denko KK
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/40—Compounds of aluminium
    • C09C1/407—Aluminium oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/021—After-treatment of oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
    • C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
    • C01F7/442—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination in presence of a calcination additive
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/02—Amorphous compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/32—Thermal properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/44—Alpha, beta or gamma radiation related properties

Abstract

A process for producing roundish alumina particles includes heating at 1,000 to 1,600 DEG C a composition containing at least one of electrofused alumina and sintered alumina having a mean particle size greater than 35 mu m, and at least one species selected from the group consisting of a halogen compound, a boron compound and an alumina hydrate; and crushing the composition.

Description

Ball-aluminium oxide particle and production method thereof
The cross reference of related application:
The application is the application of submitting to according to 35 U.S.C. § 111 (a), its application number that requires submit to June 6 calendar year 2001 according to 35 U.S.C. § 119 (e) (1) is the applying date of 60/295,617 provisional application (submitting to according to 35 U.S.C. § 111 (b)).
Technical field:
The present invention relates to the industrial economic means of round alumina particle and preparation alumina particle, this particle is specially adapted to for example sealing material of electronic component; Filler; Lappingout material and mixing gathering materials in refractory materials, glass, pottery or its matrix material, and it does not produce basically and weares and teares and have good flow characteristics.The present invention also relates to round alumina particle and the high thermal conductance rubber/plastics composite that contains this alumina particle by this method preparation.
Relevant background technology:
In recent years, the highly integrated and highdensity needs of electronic component have been increased the current consumption of every chip block.Therefore, rise in order to suppress temperature of electronic component, the heat of removing generation effectively is a critical problem.Consider above-mentioned factor, having the aluminum oxide of excellent heat conductivity, particularly silicon carbide (Alpha-alumina) has become radiating gasket, fixedly the candidate filler of base material of the insulated enclosure material of semi-conductor and semiconductor device components etc.; Improved aluminum oxide has been applied in many fields.
In this particles of silicon carbide, JP-A HEI 5-294613 discloses a kind ofly not to be had cracked and median size is 35 microns or following non-hollow spherical particles of silicon carbide, this particle is preparation like this: add aluminium hydroxide simultaneously and become known for crystalline promotor arbitrarily in ground alumina product such as fused alumina or sintered alumina, fire this mixture then.
Yet above-mentioned document is not to using median size to make clearly explanation greater than the granularity of the particles of silicon carbide of 35 microns fused alumina or sintered alumina preparation, shape etc.
Also known a kind of hot spray method, wherein will enter in high-temperature plasma or the oxygen-hydrogen flame so that fusion and quenching prepare circular granular thus by the aluminum oxide atomizing of Bayer process preparation.Though hot spray method provides the aluminum oxide coarse particles of particle diameter greater than 35 μ m, the unit energy requirment is big, so the cost height.In addition, though Zhi Bei aluminum oxide mainly contains Alpha-alumina thus, it comprises for example δ-aluminum oxide of byproduct.This alumina product is not preferred, because this product does not have the performance that aluminum oxide needs, for example thermal conductivity is low.
Ground fused alumina or sintered alumina product are also referred to as particle diameter greater than 35 microns particles of silicon carbide.Yet these particles of silicon carbide have the uncertain shape of sharp keen section, in mixing the process of rubber/plastics kneading machine, mould etc. are produced significant wearing and tearing.Therefore, from the viewpoint that reality is used, these particles of silicon carbide are not preferred.
Known that some productions have the method for the rubber/plastics composite of high heat conductance, for example: a kind ofly mix for example method of aluminium nitride, boron nitride or silicon carbide of high heat conductance filler, and a kind of method that adds quantity filler as much as possible.Yet previous method is disadvantageous economically because with mix Alpha-alumina relatively, mix the high heat conductance filler and cause cost very high.When using back one when mixing method, mix the thermal conductivity that mass filler can improve resulting mixture (composition) really.Yet the plastic fluidity of this mixture is poor, makes its difficult forming.Therefore, the quantity of filler has limitation.
Worked out another kind of method, wherein mixed the filler of various particle size range and increase the quantity of filler, to enlarge size distribution for the plastic fluidity that strengthens this mixture.Yet because the self aggregation power of particulate constituent reduces and increases along with granularity, so mobile reduction when it mixes in rubber/plastics, component forms aggregated particles in resulting rubber/plastics composite, may reduce thermal conductivity.Therefore, the use of particulate also is restricted on granularity.For the coarse particles component, in order to reach high workability, the coarse particles shape that meets the requirements should be near circular.Yet, as JP-A HEI5-294613 is disclosed, be difficult to the production median size usually greater than 35 microns and there is not the particle of chipped area.
Consider above-mentioned situation, the inventor has carried out extensive studies, and the objective of the invention is to provide a kind of filler of making by aluminum oxide by improving the method for producing circular particles of silicon carbide, its particle causes carrying out less grinding and polishing, and volume is big.
Of the present invention open:
The inventor provides a kind of production round alumina particulate method that can be used for addressing the above problem; Alumina particle by this method production; And the rubber/plastics composite that mixes the high heat conductance of this alumina particle.
Specifically, the invention provides a kind of production round alumina particulate method, be included in 1,000 to 1,600 ℃ down heating contain at least a median size greater than 35 microns fused alumina and sintered alumina and at least a composition that is selected from the material of halogen compounds, boron compound and hydrated alumina; Pulverize said composition then.
In the method, the median size of fused alumina and sintered alumina is at least 50 microns.
In the method, the median size of fused alumina and sintered alumina is greater than 35 microns and be less than or equal to 120 microns.
In above any method, add at least a halogen compounds and boron compound, add-on is 5 to 20 quality % of aluminum oxide total amount.
In above any method, halogen compounds is at least a AlF that is selected from 3, NaF, CaF 2, MgF 2And Na 3AlF 6In material.
In above any method, boron compound is at least a B of being selected from 2O 3, H 3BO 3, mNa 2OnB 2O 3The material of (wherein each m and n are integers) and fluoroborate compound.
In above any method, hydrated alumina is at least a material that is selected from the portion water compound of aluminium hydroxide, alumina gel, amorphous hydroted alumina and aluminum compound.
In above any method, the alpha-ray index of every kind of fused alumina, sintered alumina and hydrated alumina is 0.01c/cm 2Hour or following.
The present invention also provides the round alumina particle of producing by above any method.
The present invention also provides a kind of round alumina particulate high heat conductance rubber combination of being produced by this method that contains.
The present invention also provides a kind of round alumina particulate high heat conductance plastics composite of being produced by this method that contains.
Implement best mode of the present invention
Below describe the present invention in detail.
The invention provides a kind of production round alumina particulate method, be included in 1,000 to 1,600 ℃ down heating contain at least a median size greater than 35 microns fused alumina and sintered alumina, with at least a composition that is selected from the material of halogen compounds, boron compound and hydrated alumina, and pulverize said composition.
Aluminum oxide coarse particles as raw material can be the grated product of fused alumina or the grated product of sintered alumina in the present invention.Under any situation, this grated product is to produce by the method for knowing any the sixth of the twelve Earthly Branches.The median size of the grated product of fused alumina or sintered alumina is greater than 35 microns, be preferably greater than 50 microns or more than, more preferably greater than 35 microns and be less than or equal to 120 microns, preferred especially 50 to 120 microns.Median size be 35 microns or following be not preferred because be no more than 35 microns by the round alumina particulate median size of this raw material production.
In order to strengthen coarse grained circularity, in fused alumina and/or sintered alumina, add hydrated alumina as required in advance, then heating as the circularity toughener.The example that is used for hydrated alumina of the present invention comprises: aluminium hydroxide such as gibbsite, bayerite, boehmite and diaspore; Amorphous hydroted alumina such as alumina gel and plan-boehmite; And the aluminum oxide (aluminum oxide) of aluminum compound portion water compound such as surface portion hydration.In the middle of these, especially preferably have aluminium hydroxide, alumina gel and the alumina particulate of high fever reaction.From an economic point of view, the aluminium hydroxide (gibbsite) that preferred Bayer process is produced, most preferably 10 microns of median sizes or following aluminium hydroxide (gibbsite).
The inventor has observed a very surprised phenomenon: circularity toughener and other additive cited below (adding as required) synergy is on thick alumina particle, and act on (or by irregular sharp keen section absorption) on the irregular sharp keen section selectively, therefore obtain circular thick alumina particle.
Quantity to the circularity toughener does not have special restriction because this quantity according to the size distribution of the grated product of fused alumina or sintered alumina or similarly factor change.For example, when adding aluminium hydroxide, its add-on is preferably in 5 to the 300 quality % scopes of fused alumina and/or sintered alumina (calculating to be reduced into aluminum oxide).This add-on is more preferably in the scope of 50 to 150 quality %.When above-mentioned add-on during less than 5 quality %, the sticking power that gathers materials increases, and when this add-on during above 300 quality %, can discharge the excessive hydrogen aluminum oxide, and be moved in the product with alumina particulate.
Other additive for adding before thermal treatment as required can be used alone or in combination the known compound as the alpha-alumina crystals growth stimulant.Preferred crystal growth promoters is the halogen compounds of preferably being introduced by following at least a fluorine cpd: be selected from AIF 3, NaF, CaF 2, Na 3AlF 6And MgF 2, and/or at least a B that is selected from 2O 3, H3BO3, mNa 2OnB 2O 3The boron compound of (wherein each m and n are integers) and fluoroborate compound.In the middle of these compounds, special preferred fluorinated compound and boron compound, and fluoroborate combination of compounds.
When the granularity of fused alumina or sintered alumina increased, cracked rate reduced.When other content of additive that adds increases, further improved cracked rate except above-mentioned hydrated alumina.Therefore, even median size is used as raw material greater than thick fused alumina/sintered alumina (also not using so far) of 35 μ m, can produce circular thick alumina particle, it basically can be to not sneaking into it kneading machine in rubber/plastics or forming mould being produced wear problem.
Though the add-on of additive changes according to the type of Heating temperature, the residence time and the process furnace of the granularity of the sintered alumina/fused alumina that uses, process furnace, but effective add-on of this additive preferably the alumina component total amount 3 quality % or more than, preferred especially 5 quality % or more than.In addition, the preferred 20 quality % or following of add-on.When the add-on of additive during, the effect deficiency of cracked reduction, therefore increase the wearing and tearing of it being sneaked into the mould of the kneading machine of rubber/plastics or model, and from an economic point of view, volume not preferred greater than 20 quality % less than 3 quality %.
To the type of process furnace without limits, can use for example single kiln of the device of knowing the sixth of the twelve Earthly Branches, tunnel furnace and rotary kiln.Heating temperature is not had special restriction, form Alpha-alumina as long as temperature can guarantee the finished product.Heating temperature generally be 1,000 ℃ or more than, preferred 1,300 ℃ to 1,600 ℃ (containing), more preferably 1,300 ℃ to 1,500 ℃ (containing).When temperature is elevated to 1,600 ℃ or when higher, even in the presence of aluminium hydroxide, the sticking power that gathers materials also increases, and therefore suppresses to be ground into primary particles.The residence time that needs in process furnace changes according to Heating temperature, is 30 minutes or longer, and preferably approximately is 1 hour to 3 hours.
Thick alumina particle by aforesaid method can present the after polymerization particle.Therefore, by the shredding unit known the sixth of the twelve Earthly Branches for example ball mill, vibromill or jet mill pulverize one period short period of time of this particle, produce the circular particles of silicon carbide that target grain size distributes thus.
In above-mentioned production method, can be by the round alumina particle of the low alpha-ray index of for example fused alumina, sintered alumina and aluminium hydroxide material produce such as (they all contain trace-level activity element for example uranium and Thorotrast).When in the resin-sealing material of highly integrated unicircuit, large-scale integrated circuit and super large-scale integration, using this low alpha-ray index (0.01c/cm 2Hr) round alumina particle is during as filler, and this particle is particularly suitable for preventing the operating troubles (that is software error) by the caused memory storage of alpha-ray.
The round alumina that the present invention produces shows as thick particles of silicon carbide form, though keep some cracked sections, but the kneading machine or the forming mould of it being sneaked in rubber/plastics do not had wear problem, and when being used in combination, produce good fluidization characteristic with particulate constituent.
The round alumina particle that the inventive method is produced preferably mixes in rubber or the plastics, and high heat conductance rubber combination and high heat conductance plastics composite are provided thus.Particularly, this incorporation be preferably 80 quality % or more than.
In the present invention, the type of the plastics (resin) of forming above-mentioned high heat conductance plastics composite is not had special restriction, can use the resin of knowing any the sixth of the twelve Earthly Branches.Its example comprises the plain resin of unsaturated polyester resin, acrylic resin, vinyl ester resin, Resins, epoxy, xylene formal dehyde resin, guanamine resin, diaryl phthalic ester resin, resol, furane resin, polyimide resin, melmac and urea.In the middle of these examples, preferred unsaturated polyester resin, acrylic resin, vinyl ester resin and Resins, epoxy.
In the present invention, (for example: type rubber components) does not have special restriction, can use the elastomeric material of knowing any the sixth of the twelve Earthly Branches to the elastomeric material of forming above-mentioned high heat conductance rubber combination.
Describe the present invention in more detail below by embodiment, this should not be regarded as restriction the present invention.
Embodiment 1:
With 250 gram median sizes be aluminium hydroxide (product of Showa Denko K.K), 35 gram SILVER REAGENT Anhydrous Aluminium Chlorides and the 35 gram SILVER REAGENT boric acid of 1 μ m to join the commercially available median size of 500 grams be in 51 microns the ground sintered alumina product (product of Alcoa Kasei company limited) and mix, then resulting mixture is placed in the thermally resistant container of being made by alumina-ceramic.In kanthal alloy (Kanthal) electric furnace in 1,500 ℃ were heated this mixture 4 hours down, (100 grams are burnt till product and 1 by the oscillatory type ball mill then, 000 gram high density aluminum oxide matter ball milling is put into pulverizer (model SM0.6, the product of Kawasaki Ishikawajima-Harima Heavy Industries Ltd.) with ball (10 millimeters φ)) pulverized this heating products 30 minutes.Obtain the size distribution of this milling product by laser diffractometry (microtrack).
Embodiment 2:
Except the add-on of Anhydrous Aluminium Chloride and the add-on of boric acid are changed into respectively 10 grams, repeat the method for embodiment 1.
Embodiment 3:
Except using median size is 90 microns grinding the sintered alumina product, repeats the method for embodiment 1.
Comparative Examples 1
With the commercially available median size of 500 grams is that 51 microns the sintered alumina product (product of Alcoa Kasei company limited) that grinds is placed in the thermally resistant container of being made by alumina-ceramic, then in the kanthal alloy electric furnace in 1145 ℃ of heating 4 hours down.Pulverized this heating products 30 minutes by oscillatory type ball mill (100 grams are burnt till product and 1,000 gram high density aluminum oxide matter ball milling is put into pulverizer (model SM0.6, the product of Kawasaki Ishikawajima-Harima Heavy Industries Ltd.) with ball (10mm ф)).Obtain the size distribution of this milling product by laser diffractometry (microtrack).
The size distribution and the particle form of the powder that following table 1 explanation embodiment 1 to 3 and Comparative Examples 1 are produced.
Table 1
Embodiment 1 Embodiment 2 Embodiment 3 Comparative Examples 1
Median size 58μm 60μm 93μm 52μm
Particle form Circular granular Circular granular Circular granular The amorphous particle that has sharp keen section
For the particulate abradability when kneading of testing and assessing, the material formed shown in the table 2 is predefined in 105 ℃ to 115 ℃ roller by two temperature kneaded 3 minutes with resin or analogous material.Visually observe painted by the caused above-mentioned formula materials of wearing and tearing of the hard chromium of each roll surface, reference index evaluation degree of staining.
Table 2
Figure C02801973D00111
Specifically, visually judge between aluminum oxide and roll surface owing to the hard chromium bits sheets (black) that grind off enter into every kind of degree by the product (white) of prescription manufacturing.The degree of wear is divided into following a few class: 1) do not have painted, 2) faint painted, 3) slightly painted, 4) a large amount of painted and 5) painted fully.The result is presented in the following table 3.
Table 3
Embodiment 1 Embodiment 2 Comparative Examples 1
Degree of wear evaluation 2) 3) 5)
Embodiment 4:
By waving median size that round alumina particle that mixing tank produces 80 quality % embodiment 1 and the commercially available Bayer process of 20 quality % produce is that 1.7 microns low soda alumina (product of Showa Denko K.K) mixed 1 hour.
Comparative Examples 2:
With 250 gram median sizes be aluminium hydroxide (product of Showa Denko K.K), 25 gram SILVER REAGENT Anhydrous Aluminium Chlorides and the 25 gram SILVER REAGENT boric acid of 1 μ m to join the commercially available median size of 500 grams be that 13 microns, maximum particle diameter are in 48 microns the ground sintered alumina product (product of AlcoaKasei company limited), then resulting mixture is placed in the thermally resistant container of being made by alumina-ceramic.With mixture in the kanthal alloy electric furnace in 1,450 ℃ were heated 4 hours down, (100 grams are burnt till product and 1 by the oscillatory type ball mill then, 000 gram high density aluminum oxide matter ball milling is put into pulverizer (model SM0.6, the product of Kawasaki Ishikawajima-Harima Heavy Industries Ltd.) with ball (10mm Φ) and was pulverized this heating products 30 minutes.Obtain the size distribution of this milling product by laser diffractometry (microtrack).Find that the aluminum oxide of producing like this presents circular granular, and median size is 18 microns.
Comparative Examples 3:
Round alumina particle of the Comparative Examples 2 of 80 quality % being produced by swing mixing tank and the commercially available median size of 20 quality % are that the low soda alumina (product of Showa Denko K.K) that 1.7 microns Bayer process is produced mixed 1 hour.
(evaluation of mixed performance)
With quantity be 500 mass parts (one-shot measurement) and quantity be 700 mass parts (another time measurement) embodiment 1 and 4 and the alumina products that obtain of Comparative Examples 2 and 3 be incorporated into the silicone oil of 100 mass parts separately (KF 96,1,000cP (centipoise), the product of Shin-Etsu chemistry company limited) in.Use Brookfield viscometer to measure every kind of composition viscosity under 25 ℃ of preparation like this.The results are shown in the following table 4.
Find that the round alumina particle that embodiment 1 obtains is thick particles of silicon carbide, shown in embodiment 4, be used in combination, produce good fluidization characteristic with particulate constituent.
Table 4
Figure C02801973D00131
Embodiment 5:
With the alpha-ray index is 0.01c/cm 2Hour or lower industrial low alpha-ray aluminum oxide (product of Showa Denko K.K) pulverize by the blank of electric smelting preparation, abrasive dust, and make it not have classification under condition that radioelement pollutes, producing median size thus and be 60 microns and alpha-ray index is 0.005c/cm 2.hr fused alumina coarse particles.It is 0.005c/cm by the alpha-ray index that the sixth of the twelve Earthly Branches, perception method obtained that 500 gram alumina particles are joined 250 grams 2Hour and median size be in the low alpha-ray aluminium hydroxide of 5 μ m, fire resulting mixture then, and pulverize in the mode that is similar to embodiment 1, producing the alpha-ray index thus is 0.004C/cm 2Hour and median size be 67 microns round alumina particle.
Industrial applicibility:
As indicated above, the particles of silicon carbide of producing by the inventive method is circular coarse granule, and it does not have wear problem to machine and instrument basically. When thereby this particle mixes with particulate constituent when enlarging particle diameter and distributing, can produce the resin combination that contains mass filler, this former because poor fluidity and never producing.

Claims (8)

1. production round alumina particulate method comprises:
1,000 to 1,600 ℃ down heating contain fused alumina and the sintered alumina of at least a median size greater than 35 μ m, the composition of hydrated alumina and at least a material that is selected from halogen compounds and boron compound and
Pulverize said composition,
Wherein, be reduced to aluminum oxide, add hydrated alumina with 50 to 300 quality % in this at least a fused alumina and sintered alumina.
2. the process of claim 1 wherein that the median size of fused alumina and sintered alumina is at least 50 μ m.
3. the process of claim 1 wherein that the median size of fused alumina and sintered alumina is greater than 35 microns and be less than or equal to 120 microns.
4. each method of claim 1-3 wherein, based on aluminum oxide total amount meter, adds at least a halogen compounds and boron compound with 5 to 20 quality %.
5. the process of claim 1 wherein that halogen compounds is at least a AlF of being selected from 3, NaF, CaF 2, MgF 2And Na 3AlF 6Material.
6. the process of claim 1 wherein that boron compound is at least a B of being selected from 2O 3, H 3BO 3, mNa 2OnB 2O 3, wherein each m and n are the materials of integer and fluoroborate compound.
7. the process of claim 1 wherein that hydrated alumina is at least a material that is selected from aluminium hydroxide, alumina gel, unformed aluminium hydroxide and partially hydrated aluminum compound.
8. the process of claim 1 wherein that fused alumina, sintered alumina and hydrated alumina alpha-ray index separately is 0.01c/cm 2Hour or following.
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