JP2001233627A - Method and apparatus for manufacturing spherical silica powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce, in an industrial scale, spherical silica powder having excellent dispersibility fluidity, filling property and the like, and excellent as a filter to be used for preparing various resin compositions. SOLUTION: This process comprises the steps in which siliceous raw material powder is injected into high temperature flame formed by a combustible gas and a supporting gas to heat-treat the siliceous powder, subsequently the treated powder is classified, and spherical silica particles of desired particle sizes are collected, wherein cooling gas is supplied from the position higher than the top of the high temperature flame, being separated from the flame. The apparatus for manufacturing spherical silica powder is provided with a burner (2) on the upper part of the furnace body of a vertical type furnace (6), and a collecting apparatus linked to the lower part of the furnace. In the manufacturing apparatus, a partition wall (4) is placed in such a state that the high temperature flame (3) formed by the above burner is surrounded, and a feeding port (5) for a cooling gas is placed on a side wall of the furnace body so that the cooling gas can be supplied between the partition wall and the above furnace body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for producing spherical silica powder. More specifically, the present invention relates to a method and an apparatus for stably producing, on an industrial scale, high-quality spherical silica powder having excellent dispersibility, fluidity, and filling properties, and as a filler used in various resin compositions. is there.

[0002]

2. Description of the Related Art Silica of high purity, which has been melted at a high temperature and cooled, has an amorphous network structure, low expansion properties, thermal shock resistance, and low thermal conductivity. Used. In addition, the powder is chemically stable, has high insulation properties, and has a low high-frequency dielectric loss.

Conventionally, crushed silica powder has been used as a filler for a semiconductor encapsulant. However, in recent years, adoption of a surface mounting method, enhancement of device performance, and increase in size of a chip and reduction in the thickness of a package have been required. As the demand for improving the solder heat resistance of the encapsulant increases with the progress, spherical silica powder that can be highly filled and has excellent fluidity has come to be used.

However, if the ratio of the filler in the encapsulant is simply increased, the fluidity at the time of molding decreases, and the die on which the chip is mounted is displaced, and the flow or cutting of the gold wire is accompanied. There is a problem that various deterioration of the moldability is caused.

Therefore, as a technique for improving the fluidity of the sealing material so as not to impair the moldability at the time of sealing under high filling of the filler, for example, the gradient of a straight line represented by a rosin-Rammler diagram is set to 0.6 to 100%. A method of expanding the particle size distribution to 0.95 (Japanese Patent Laid-Open No. 6-80863);
A method of increasing the sphericity of particles to 1.0 or less (Japanese Patent Application Laid-Open No. 3-66151), and in order to further enhance the fluidity of the sealing material, spherical fine particles having an average particle diameter of about 0.1 to 1 μm. A method of adding and blending a small amount of powder (Japanese Patent Laid-Open No. 5-23932)
No. 1) has been proposed and has been put to practical use.

As a method for producing such a spherical silica powder, for example, a method in which a metal alcoholate is precipitated by a sol-gel method under specific conditions to form a spherical form, a method in which silicon dioxide (quartz powder, silica powder, etc.) is melted in a high-temperature flame Alternatively, there is a method of spheroidizing by softening, a method of spheroidizing metal silicon fine particles by throwing them into a flame and causing an oxidation reaction, and the like. The law is currently mainstream.

As the flame spheroidizing method, a technique using a vertical furnace having a burner on the furnace top is mainly used. For example, Japanese Utility Model Publication No. Hei 6-39785 discloses the use of a vertical furnace in which a cylindrical body surrounding a high-temperature flame formed by a spheroidizing burner is provided at the upper part of a furnace body in order to improve productivity by improving melting efficiency. Is described.

Japanese Patent Application Laid-Open No. H10-85577 discloses that a burner having a special structure is installed at the upper part of a furnace body and molten powder adheres to the furnace inner wall for the purpose of suppressing generation of lumps from the burner and the furnace. The use of a vertical furnace provided with a shut-off air introduction hole for introducing air tangentially downward so as not to disturb is described.

[0009]

However, it is possible to maintain a higher flame temperature by using a vertical furnace having a structure described in Japanese Utility Model Publication No. 6-39785. It is unavoidable that a lump of molten material (ingot shape) will be generated on the inner wall, and the growth of the lump will cause blockage in the cylinder, or the lump of molten lump will drop and block the lower part of the furnace body. With the necessity, fuel-efficient operation is possible, but there remains a problem in productivity.

Further, in the vertical furnace described in Japanese Patent Application Laid-Open No. H10-85577, adhesion of the molten powder to the furnace inner wall can be effectively prevented, but the swirling air interferes with the flame and the flame temperature becomes lower. Not only does this significantly reduce the melting rate of the powder collected by the cyclone, but also controls the particle size of the fine powder mainly composed of vapor-phase precipitated particles collected by the bag filter due to rapid cooling of the inflow air. As a result, the average particle diameter becomes significantly smaller than 0.1 μm, and a high-quality spherical silica powder having excellent fluidity cannot be obtained.

As described above, in the conventional method for producing spherical silica powder using a vertical furnace, it is difficult to stably mass-produce high-quality spherical silica powder having excellent fluidity and dispersibility. The development of new technologies has been awaited.

The present invention has been made in view of the above, and an object of the present invention is to eliminate the above-mentioned problems, and to provide a spherical powder having excellent fluidity and a high melting rate, and fumed particles obtained by vapor phase growth. An object of the present invention is to provide a method and an apparatus for producing a spherical silica powder capable of efficiently and stably producing the constituted spherical fine powder.

[Means for Solving the Problems]

That is, according to the present invention, the silica-based raw material powder is injected into a high-temperature flame formed by the combustible gas and the auxiliary combustion gas, heated, and then classified to collect spherical silica powder having a desired particle diameter. A method for producing a spherical silica powder, characterized in that a cooling gas is supplied from a position above an end portion of the high-temperature flame while being isolated from the high-temperature flame. In particular, the cooling gas amount is 10 to 15 times the combustible gas amount.
It is preferable to supply the mixture with a volume of 0 times and supplying a swirling flow to collect spherical silica powder having an average particle diameter of 0.1 to 60 μm.

Further, the present invention relates to an apparatus for producing spherical silica powder, wherein a burner (2) is installed on an upper part of a furnace body of a vertical furnace (6) and a collector is connected to a lower part of the furnace body. A partition (4) surrounding the high-temperature flame (3) formed by the above is provided, and a cooling gas supply port (5) is provided at a side of the furnace body so that a cooling gas can be supplied between the partition and the furnace body. A spherical silica powder production apparatus characterized in that the apparatus is provided. In particular, it is preferable that a cooling gas supply port (5) is provided so that a cooling gas can be supplied by giving a swirling flow.

Furthermore, the present invention provides a spherical silica powder characterized in that the silica-based raw material is subjected to heat treatment using the above-mentioned apparatus for producing a spherical silica powder, and then classified to collect a spherical silica powder having a desired particle diameter. This is a method for producing silica powder.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic view showing an example of the manufacturing method or apparatus according to the present invention, and FIG. 2 is a schematic plan view of the vertical furnace (6). FIG. 3 is a schematic diagram showing an example of a conventional example. In each case, raw material feeder (1) and vertical furnace (6)
And a trapping device (9, 10, etc.). In addition, each of the trapping devices is composed of a spherical silica powder melted in a high-temperature exhaust gas of a high-temperature flame (3) and a fine spherical powder (fumed powder component) mixed in a vapor phase,
It comprises, for example, a cyclone (9) for classification by suction by a blower (11), and a bag filter (10) for collecting fine spherical powder that could not be collected by the cyclone. (12) is a suction gas amount control damper,
(13) is a gas exhaust port, and (14) is a powder extracting device.

A major feature of the present invention is that the structure of the vertical furnace (6), particularly the upper structure of the furnace body, is provided with a partition (4) and a cooling gas suction port (5). .

The partition wall is provided at least from the end of the high-temperature flame (3) to an arbitrary position of the high-temperature flame and around the high-temperature flame in order to eliminate disturbance near the end of the high-temperature flame. is necessary. Preferably,
It is provided from near the center to the end of the hot flame, particularly preferably over the entire length of the hot flame. FIG. 1 shows an example provided over the entire length of the high-temperature flame. Partitions from the end of the hot flame to the lower method may or may not be provided.

The material of the partition wall and the furnace body is not particularly limited, such as refractory material sticking, metal, etc. However, when the furnace body itself functions as a high-temperature flame cooler, for example, SUS304 series, 31
It is preferable to be made of a metal such as stainless steel of series 6 or the like, and it is particularly preferable to have a structure that can be cooled and protected by an appropriate refrigerant. The partition is installed on the furnace body by screwing, welding, or the like.

The shape of the furnace body may be a straight body type,
In order to sufficiently secure the effect of suppressing powder adhesion to the inner wall of the furnace, the gradient 6 is set so as not to eliminate the downward velocity vector of the swirling flow.
It is preferably a cone of 0 to 85 °.

The cooling gas suction port is provided by screwing, welding, or the like on the side wall of the furnace body provided with the partition wall. As a result, the cooling gas is supplied from a position above the end of the high-temperature flame and is separated from the high-temperature flame. Preferably, the cooling gas is swirled through the furnace inner wall,
The opening of the cooling gas suction port is set at 40 to 90
The angle is set at a normal angle of °. The shape of the opening may be any of a rectangle, a circle, a polygon, an ellipse, and the like.

Conventionally, as shown in FIG. 3, since the cooling gas is supplied from a position lower than the end of the high-temperature flame without providing a partition wall, the molten powder adheres and grows on the inner wall of the furnace. By repeatedly dropping and growing, the yield was reduced, and in some cases, the grown powder layer became a lump and fell and was forced to stop operation immediately. In particular, when a swirling flow is given to the cooling gas and supplied into the furnace, the swirling flow rises and interferes with the high-temperature flame, causing the flame to twist. In such a state, conversely, not only the melting rate and the sphericity of the molten powder are reduced, but also the fumed particles are not enlarged, and a high-quality fine spherical silica powder excellent in the effect of promoting fluidity cannot be obtained.

On the other hand, a partition is provided as in the present invention,
By supplying the cooling gas preferably between the furnace inner wall and the partition wall while giving a swirling flow, interference between the cooling gas and the high-temperature flame can be reduced, and the above-described conventional problem can be solved. . As cooling gas, air, oxygen,
Argon, nitrogen and the like are used.

The cooling gas amount is 10 to 150 times the combustible gas amount.
A volume doubled volume is preferable, and the volume is 2 volumes provided at the lower part of the furnace body.
It can be adjusted by adjusting the opening of the secondary cooling gas intake valve (8). If the amount of the cooling gas is greater than 150 times the volume of the combustible gas, a part of the cooling gas rises near the partition wall and reverses and descends at the furnace top, so that it interferes with the high-temperature flame and melts the molten powder. The rate and sphericity tend to decrease, and furthermore, the vapor phase growth of fumed particles does not proceed sufficiently, and the number of particles finer than 0.1 μm increases. On the other hand, if the volume is less than 10 times the volume, the above-mentioned problem is alleviated, and more fumed particles larger than 0.1 μm can be collected. The growth tends to increase.

The burner used in the present invention is preferably of a type in which the combustible gas and the auxiliary gas are premixed and supplied, or a two-fluid nozzle type in which these are separately supplied and burned at the tip of the burner. The number is one or two or more.

As the combustible gas for forming a high-temperature flame, hydrocarbons such as acetylene, propane and butane, or a mixed gas thereof can be used. A gas containing 90% or more, particularly 99% or more oxygen, is used as the auxiliary combustion gas.

The siliceous raw material used in the present invention is not particularly limited as long as it is siliceous. The shape may be any of a spherical shape, an irregular shape, a chamfered shape obtained by grinding an edge, and the like, or a mixed powder thereof. There is no limitation on the crystal structure, and crystalline, amorphous, or a mixture thereof is used.

The average particle size of the siliceous raw material powder is as follows:
It may be 0.5 to 60 μm. When obtaining a bag filter collection powder mainly composed of fumed particles in high yield, finer is better, preferably 0.5 to 25 μm.
m, more preferably 0.5 to 10 μm.

As the carrier gas for transporting the siliceous raw material powder, the same gas as the above-mentioned auxiliary gas is used, and the mixing ratio to the raw material powder 1 is 0.1 to 3.0 kg / Nm.
It is desirable to set it to ³ .

The collecting device used in the present invention will be described. As the collecting device, an appropriate number of heavy sedimentation chambers, cyclones, classifiers having rotating blades, bag filters and the like are used. By changing the operating conditions of the collector, the acquisition rate of the target particles in each collector can be changed. The powder obtained from each classifier can be used as a product as it is, or can be appropriately mixed to obtain powders having different powder characteristics. This classification operation may be performed on another line after collective collection by a bag filter or the like,
In order to efficiently separate and recover the fumed fine powder, it is desirable to incorporate the fumed fine powder into a transportation step having excellent dispersibility.

The average particle size of the spherical silica powder produced according to the present invention is preferably 0.1 to 60 μm. If it is less than 0.1 μm, the effect of promoting fluidity is poor, and if it is more than 60 μm, chip damage (microcracks) at the time of molding occurs when the application is a filler for a sealing material. .

Usually, the spherical silica powder is produced by supplying a raw material powder into a high-temperature flame formed by a combustion reaction between a combustible gas and a supporting gas, and melting and spheroidizing the powder at a temperature higher than its melting point. The powder obtained by such a method contains a gas phase deposition component (fumed particles) having an extremely fine particle size. This is due to the fact that a part of the raw material powder evaporates in the high-temperature flame, the particles grow from the gas phase SiO, and are precipitated and solidified by rapid cooling, and pass through the furnace together with the molten spherical powder. In the present invention, by optimizing the position and amount of the cooling gas taken into the furnace, it is possible to prevent the molten powder from adhering to the furnace inner wall, which is indispensable for stable operation, and furthermore, the molten spherical powder It is possible to control the particle size of fumed particles while maintaining the melting rate at a high level. Furthermore, these spherical silica powders could be stably separated and recovered by the classification treatment.

The properties of the spherical silica powder produced according to the present invention, such as dispersibility, fluidity, and filling property, are measured by measuring a spiral flow value when filled in an epoxy resin composition represented by a sealing material. Can be evaluated.

[0035]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

Examples 1 to 3 The manufacturing apparatus shown in FIG. 1 was used. The furnace body of the vertical furnace has a diameter of 1.5 m, a length of 6 m, a cone gradient of 90 ° (straight barrel type), a material of SUS316 and a water-cooled jacket system.
In addition, a partition is refractory-pasted. Natural silica rock powder material is particle size control (average particle size 12 [mu] m) is conveyed by a carrier gas (oxygen 25 Nm ³ / Hr) to the burner, the combustible gas (propane 18 Nm ³ / Hr) and oxygen (65 nm ³ / H
Injecting into the high-temperature flame formed in r), at this time, adjusting the opening degree of the secondary cooling gas (air) and changing the flow rate of the cooling gas (air) swirled and sucked from the upper part of the furnace, various spherical shapes are obtained. Silica powder was collected from the cyclone and bag filter.

Comparative Example 1 Using the production apparatus shown in FIG. 3, spherical silica powder was produced under the conditions shown in Table 1.

Comparative Example 2 In the manufacturing apparatus shown in FIG. 1, a vertical furnace having no partition wall (4) was used.

With respect to the spherical silica powder obtained above,
The average particle diameter, the specific surface area, and the melting rate were measured, and the effect of improving the fluidity when the resin composition (sealing material) was prepared was measured as follows. In addition, the state of powder adhesion on the inner wall of the furnace during the production was measured by stopping the feed of the raw material and observing the state through a viewing window at the furnace top shown in the figure. Table 1 shows the results.

(1) Average particle diameter (D50) This is the average particle diameter determined from a mass or volume particle size distribution curve obtained from a laser diffraction type particle size analyzer. As a measuring instrument, a model “LS-230” manufactured by Coulter Inc. was used. However,
For the prototype sample having a specific surface area of more than 30 m ² / g in the collected powder, the size of the primary particles obtained by SEM observation was substituted.

(2) Specific surface area The specific surface area is determined by the BET method. A model 4-SORB manufactured by Yuasa Ionics Inc. was used.

(3) Melting rate In the measurement, X-ray diffraction using CuKα ray is performed, the crystalline content in the product is quantified based on the obtained peak area, and the residue relative to the standard sample is regarded as an amorphous component. Was defined as the melting rate. The melting rate value is a property of knowing the degree of melting when using a crystalline raw material, but a high melting rate is also a substitute property of the degree of spheroidization indicating that the particles are well melted and the sphericity is also good. .

(4) Effect of Improving Fluidity The obtained spherical silica powder was dry-blended with a mixer in a ratio shown in Table 2 with each material, and then mixed with a mixing roll having a roll surface temperature of 100 ° C. for 5 minutes. The mixture was kneaded for 5 minutes, cooled and pulverized, and the spiral flow was measured.
The measurement was performed using a spiral flow mold, and EMMI-66 was used.
(Epoxy Molding Material I
nsite; Society of Pla
(stickIndustry). The molding temperature is 175 ° C., the molding pressure is 7.5 MPa, and the molding time is 90 seconds. The fluidity improving effect is shown in the table with the improvement index assuming that the fluidity shown in Comparative Example 4 is 100.

[0044]

[Table 1]

[0045]

[Table 2]

As is clear from Table 1, the fluidity of the sealing material filled with the spherical silica powder of the present invention is improved to a high level despite the high filling area.

[0047]

According to the method and apparatus for producing a spherical silica powder of the present invention, the dispersibility, fluidity, filling property, etc. are excellent.
High quality spherical silica powder as a filler used in various resin compositions can be stably produced on an industrial scale.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a method or apparatus for producing a spherical silica powder of the present invention.

FIG. 2 is a schematic plan view of a vertical furnace.

FIG. 3 is a schematic view showing an example of a conventional method or apparatus for producing spherical silica powder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material feeder 2 Spheroidizing burner 3 High temperature flame 4 Partition wall 5 Cooling gas supply pipe 6 Vertical furnace 7 Secondary cooling gas supply pipe 8 Cooling gas supply amount adjustment valve 9 Cyclone 10 Bag filter 11 Blower 12 Suction gas amount control damper 13 Gas Exhaust port 14 Powder extraction device

Continued on front page F term (reference) 4G014 AF00 4G072 AA25 BB07 DD03 GG03 GG04 HH20 MM38 QQ20 RR30 TT01 UU07 4J002 AA001 CC052 CD041 CD051 DJ016 EX070 FA086 FD016 FD090 FD142 FD150 FD160

Claims (5)

[Claims] 1. A method for producing a high-temperature flame formed by a combustible gas and an auxiliary combustion gas, injecting and heating a siliceous raw material powder, performing classification, and collecting spherical silica powder having a desired particle diameter. A method for producing a spherical silica powder, comprising supplying a cooling gas from a position above an end of the high-temperature flame while isolating the high-temperature flame from the high-temperature flame. 2. The cooling gas amount is 10 to 150 times the combustible gas amount.
2. The method for producing spherical silica powder according to claim 1, wherein the spherical silica powder is supplied in a swirling flow in a volume doubled amount, and the spherical silica powder having an average particle diameter of 0.1 to 60 [mu] m is collected. 3. A spherical silica powder producing apparatus in which a burner (2) is installed at an upper part of a furnace body of a vertical furnace (6), and a collecting device is connected at a lower part of the furnace body. Partition wall (4) surrounding the high temperature flame (3)
And a cooling gas supply port (5) is provided in the side wall of the furnace body so that a cooling gas can be supplied between the partition wall and the furnace body. 4. The apparatus for producing spherical silica powder according to claim 3, wherein a cooling gas supply port (5) is provided so as to supply a cooling gas by giving a swirling flow. 5. A method for heating a siliceous raw material using the apparatus for producing a spherical silica powder according to claim 3 or 4, followed by classification to collect a spherical silica powder having a desired particle diameter. A method for producing a spherical silica powder, which is characterized in that: