JP3322538B2 - Burner for producing spherical silica fine particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a burner for producing spherical silica fine particles. More specifically, the present invention relates to a burner used for producing spherical silica fine particles useful as a filler for an epoxy resin sealing agent for IC.

[0002]

2. Description of the Related Art Silica fine particles, in particular, contain substantially no chlorine, contain no more than 1.0 ppm of metal impurities other than silicon, have a specific surface area of 10 to 30 m ² / g and a particle size distribution of 10 to 30 m ² / g.
The amorphous spherical silica fine particles having a diameter of 500 nm are useful as a filler for an epoxy resin sealing agent for IC.

[0003] For the production of silica fine particles, a method is known in which a silane compound is flame-hydrolyzed using a burner. Most commonly, silicon tetrachloride (SiC
There is a method in which l ₄ ) is heated and evaporated, and this is hydrolyzed in an oxyhydrogen flame by a burner to obtain silica fine particles. However, the silica fine particles obtained by this method have a problem that a chloro component caused by SiCl ₄ as a raw material remains without being completely removed. In addition, because the particle size is very fine, the bulk density is small, and the particle shape is amorphous,
For example, when it is used as an auxiliary agent for improving the filling characteristics, particularly the flow characteristics of an epoxy resin for a plastic package of a semiconductor, there is a disadvantage that the effect is not improved.

For this reason, a method is known in which a silane compound containing no chloro component, for example, an organic silane compound such as an alkoxysilane is used as a raw material (JP-A-61-2).
95209). In this method, high-purity metal or metalloid oxide fine particles are obtained by burning and decomposing droplets of a metal or metalloid organic compound. However, the fine particles obtained by this method have a specific surface area of 3
A material having a large particle size of 0 to 40 m ² / g or more and a fine particle size and improved filling characteristics has not been obtained.

Japanese Patent Publication No. 5-732 discloses a spherical silica fine particle which solves such disadvantages and a method for producing the same.
No. 6 discloses. These spherical silica fine particles do not substantially contain chlorine, have a metal impurity content other than silicon of 1.0 ppm or less, and have a specific surface area of 10 to 30 m ² /
g, the particle size distribution is 10 to 500 nm, and when the alkoxysilane is burned and decomposed in a flame to obtain spherical silica fine particles, the amount of heat received per unit calculated from the total calorific value is 1.1. It can be obtained by setting to ~ 1.7 Kcal / g.

According to this method, spherical silica fine particles having a high specific purity and an appropriate specific surface area and particle size distribution substantially containing no chlorine, or having a metal particle content other than silicon of 1.0 ppm or less and having a particle size distribution of 10 ppm or less. Spherical silica fine particles having a thickness of about 500 nm can be obtained. At this time,
If the calorific value per unit of silica calculated from the total calorific value is in the range of 1.1 to 1.7 Kcal / g, the specific surface area of the silica particles is 10 to 30 m ² / g.
Can be controlled within the range.

[0007]

However, when producing the spherical silica fine particles, the spherical silica fine particles cannot be obtained in a dispersed state depending on the burner structure that forms the flame at this time, and the particles adhere to each other ( (Fused), and the spheroidization rate may decrease. As a result, the particle size distribution becomes sharp, and when filled in an epoxy resin for a plastic package, there arises a problem that the flow characteristics are impaired.

Accordingly, an object of the present invention is to provide a burner for producing spherical silica fine particles capable of producing spherical silica fine particles in which adhesion of particles having a broad particle size distribution (fusion) is small.

[0009]

The invention according to claim 1 of the present application comprises at least three straight pipe type nozzles arranged concentrically in cross section, and a gaseous alkoxysilane and inert gas are supplied from the innermost nozzle. A first nozzle group for ejecting a mixed gas of gases, ejecting one of oxygen, a mixed gas of oxygen and an inert gas, and an inert gas from an intermediate nozzle, and ejecting hydrogen from an outermost nozzle; A plurality of nozzles are arranged around the first nozzle group, and the center line of at least one nozzle intersects the center line of the first nozzle group at an intersection on the gas ejection side, and the center line of each nozzle and the Except for the case where the conical surface group formed with the intersection point with the center line of one nozzle group as the apex and the center line of each nozzle as a line element has the same conical surface, they intersect with each other at least in a region including each nozzle. Do not set A second nozzle group for ejecting oxygen; and an outermost shell nozzle for ejecting hydrogen disposed so as to cover the first and second nozzle groups. The particle size distribution is 0 to 3 μm
A burner for producing fine silica particles.

[0010] In the invention according to claim 2 of the present application, the second nozzle groups are arranged at equal intervals on at least one concentric circle in cross-section where each nozzle shares the center line of the first nozzle group. The present invention provides a burner for producing spherical silica fine particles according to claim 1.

According to a third aspect of the present invention, there is provided an intersection group between a center line of the first nozzle group and a center line of each nozzle of the second nozzle group, and gas of these nozzle groups is ejected. The distance from the common open surface composed of the side end surfaces is 100 to 2
A burner for producing spherical silica fine particles according to claim 1 or 2, wherein the burner is within a range of 00 mm.

The invention according to claim 4 of the present application is characterized in that the first and second nozzle groups and the outermost nozzle are made of quartz glass. A burner for producing silica fine particles.

Next, the present invention will be described in more detail.

The residence time of the silica fine particles in the flame varies depending on the length of the flame formed from the burner and the temperature distribution in the flame. The surface area is determined. The length of the flame and the temperature distribution in the flame are due to the burner structure, and the use of the burner according to the first aspect of the present invention provides good dispersibility and a particle size distribution of 0 to 3 μm.
In, spherical silica fine particles is broad is obtained.

According to the second or third aspect of the present invention, spherical silica fine particles having a broader particle size distribution with better dispersibility can be obtained. In particular, according to the third aspect of the invention, the particles are less likely to fuse with each other, and the particle diameter is 10 n.
Silica fine particles having a wide particle size distribution of about m to 500 nm can be obtained. Distance between a group of intersections between a center line of the first nozzle group and a center line of each nozzle of the second nozzle group, and a common open surface formed by an end face of the nozzle group on the side from which gas is ejected. Exceeds 200 mm, the temperature distribution in the flame becomes uniform, and fusion of particles tends to occur easily. Further, when this distance is less than 100 mm, the residence time of the silica fine particles in a uniform temperature state in the flame is shortened, so that granulation does not proceed and particles having a particle diameter of about 500 nm tend to be hardly obtained. There is.

Further, according to the present invention, generation of impurities can be suppressed, which is more preferable.

Next, a method for producing spherical silica fine particles using the burner for producing spherical silica fine particles of the present invention will be described.

The spherical silica fine particles are used in the burner of the present invention.
By combustion decomposition of alkoxysilane in flame
Is done. The alkoxysilane used here has the general formula R¹  _aSi (OR^Two)_4-a (R¹And R^TwoAre methyl, ethyl, and propyl, respectively
Monovalent hydrocarbon having 1 to 4 carbon atoms, such as
The group, a represents an integer of 0 to 4. ), Specifically
Methyltrimethoxysilane, tetramethoxysilane, d
Tyltrimethoxysilane, n-propyltriethoxy
Orchid, methyltributoxysilane, diethyldipropoxy
Exemplified by silane, trimethylbutoxysilane, etc.
Alkoxysilanes or their oligomers or poly
Is a ma. These are easily purified by operations such as distillation.
can do.

The combustion decomposition of the alkoxysilane in a flame is performed by purifying the alkoxysilane by distillation or the like.
Introduced into a flame such as an oxyhydrogen flame by a gas-flow entrainment method in which it is heated and evaporated and this is caused to flow in an inert gas such as an argon gas or a nitrogen gas, or a method in which an alkoxysilane is vaporized and supplied into the flame. What is necessary is just to make it burn and decompose in this flame. At the time of this combustion, it is preferable to add a combustible gas such as hydrogen gas or methane gas as an auxiliary gas. Any auxiliary gas can be used as long as it does not leave any residue, and there is no particular limitation.

The amount of oxygen added during the combustion is as follows:
The range is preferably 0.7 to 1.5 times the theoretical amount required for combustion, and more preferably 0.7 to 1.0 times.
In this case, the insufficient oxygen is taken in from the surrounding atmosphere, so that the raw material and the auxiliary gas completely burn. If the amount of oxygen is less than 0.7 times the stoichiometric amount required for combustion, the raw material alkoxysilane and auxiliary gas may be incompletely burned, and carbon may remain in the product. On the other hand, if it exceeds 1.5 times, an amount of oxygen exceeding the amount of oxygen necessary for combustion is supplied, which is economically disadvantageous.

It is optional to mix and introduce an inert gas such as nitrogen gas or argon gas into the system as needed.

The alkoxysilane distilled and purified as described above is burned and decomposed in the above-described flame, and the generated silica is collected by a known method such as a bag filter or a cyclone. Spherical silica fine particles having a content of 1.0 ppm or less and a particle size distribution of 10 to 500 nm can be easily obtained.

The specific surface area of the thus-obtained spherical silica fine particles is usually about 50 m ² / g, which is insufficient as a filler for an epoxy resin for a plastic package. 30m ² / g
The specific surface area is controlled by controlling the ratio of the amounts of the alkoxysilane, oxygen gas, auxiliary gas, and inert gas as the raw material gas by a known method (for example, Japanese Patent Publication No. 5-73).
It is possible by setting according to 26).

[0024]

Next, the present invention will be described in more detail with reference to examples.

FIG. 1 is a sectional view showing an embodiment of a nozzle portion of a burner for producing spherical silica fine particles of the present invention, and FIG. 2 is a side sectional view taken along line XX of FIG. Also, FIG.
Straight tube multi-tube burner (nozzle group 2) used as a comparative example
FIG. The nozzle of the burner according to the present embodiment is composed of a nozzle group 10 provided on the innermost side, a nozzle group 20 provided around the nozzle group 10, and an outermost shell nozzle 30 including these nozzle groups 10 and 20. The nozzles are each made of quartz glass.

The nozzle group 10 is composed of three straight pipe type nozzles 11, 12 and 13 arranged concentrically in cross section and sharing the center line A. A gaseous alkoxysilane and an inert mixed gas are ejected from the innermost nozzle 11, and oxygen, a mixed gas of oxygen and an inert gas,
Inject any one of the inert gas and the outermost nozzle 13
Ejects hydrogen.

The nozzle group 20 comprises a plurality of straight pipe type nozzles 21 arranged around the nozzle group 10. The plurality of nozzles 21 are arranged at equal intervals on a concentric cross section C sharing the center line A of the nozzle group 10. In addition, it may exist on the same concentric circle further outside. Each center line B of the plurality of nozzles 21 intersects with the center line A of the nozzle group 10 at an intersection D on the gas ejection side, and the intersection D is the apex and the center line B of each nozzle 21 is a line element. They are arranged to form a conical surface.

The distance between the common open surface E (the end surface on the gas ejection side) of the nozzle and the intersection D is set to 150 mm.

As shown in FIGS. 3 and 4, the nozzle groups 20 are further arranged outside the nozzle groups 20 arranged at equal intervals on the concentric circles C, and at equal intervals on the concentric circles F as shown in FIGS. It may be composed of a plurality of nozzles which multiplex concentric circles so as to be arranged.

Next, using the burner shown in FIGS. 1 and 2, spherical silica fine particles were produced by the apparatus configuration shown in FIG. Specifically, the purified methyltrimethoxysilane is heated, and nitrogen gas is bubbled there,
Methyltrimethoxysilane is introduced into the nozzle 11 of the burner by flowing a stream of nitrogen gas into the nozzle 11 of the burner. 21
From the oxygen and hydrogen from the nozzle 30, respectively, to generate an oxyhydrogen flame in the combustion chamber 41, in this oxyhydrogen flame to decompose methyl trimethoxysilane,
The generated spherical silica fine particles were suctioned by a suction pump 44, collected through four stages of cyclones 42a to 42d, collected and filled in dust bunker 43a to 43d. The uncollected silica fine particles may be collected using a bag filter after the cyclone.

[0032]

[Table 1]

[0032]

[Table 1]

The particle size distribution of the formed spherical silica fine particles and the shape observation results of the spherical silica fine particles photographed by a transmission electron microscope at a magnification of 40,000 are shown in FIGS. 9 and 10 for FIG.
11 and 12 show comparative examples. The particle size distribution was measured using a centrifugal sedimentation type particle size distribution analyzer (trade name “SA-CP3R>” manufactured by Shimadzu Corporation).
L ").

The particle size distribution, as can be seen from FIGS. 7, 9 and 11, preferably the particle size distribution is broad Example 1 or 2 in 0～3Myuemu, that in the comparative example adhering particles (fusion) observed, it was found that also the particle size distribution <br/> from the particle size distribution measurement data is sharp.

Further, the amount of impurities contained in the obtained spherical silica fine particles was measured. Table 2 shows the results. The amount of chlorine is determined by ion chromatography, the amount of metallic impurities other than silicon is determined by polarized Zeeman flameless atomic absorption, titanium (Ti) is determined by ICP emission spectrophotometer, and uranium (U) is determined by fluorescence spectrophotometer. It was measured.

[0037]

[Table 2]

[0038]

As described above, the use of the burner of the present invention makes it possible to easily and inexpensively produce spherical silica fine particles having excellent filling characteristics, particularly excellent fluidity, which are useful as fillers for epoxy resins for plastic packages. The advantage is that it can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a gas ejection nozzle portion of a burner for producing spherical silica fine particles of the present invention.

FIG. 2 is a side sectional view showing one embodiment of a gas ejection nozzle portion of the burner for producing spherical silica fine particles of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of a gas ejection nozzle portion of the burner for producing spherical silica fine particles of the present invention.

FIG. 4 is a side sectional view showing another embodiment of a gas jet nozzle portion of the burner for producing spherical silica fine particles of the present invention.

FIG. 5 is a sectional view of a burner used as a comparative example.

FIG. 6 is a schematic configuration diagram showing an entire apparatus configuration when producing spherical silica fine particles using the burner for producing spherical silica fine particles having the nozzle structure shown in FIGS. 1 and 2.

FIG. 7 shows the particle size of spherical silica fine particles corresponding to Example 1.
It is a graph which shows cloth .

FIG. 8 is a transmission electron micrograph showing the appearance of spherical silica fine particles corresponding to Example 1.

FIG. 9 shows the particle size of spherical silica fine particles corresponding to Example 2.
It is a graph which shows cloth .

FIG. 10 is a transmission electron micrograph showing the appearance of spherical silica fine particles corresponding to Example 2.

FIG. 11 shows the particle size of spherical silica fine particles corresponding to the comparative example.
It is a graph which shows cloth .

FIG. 12 is a transmission electron micrograph showing the appearance of spherical silica fine particles corresponding to a comparative example.

Continuation of front page (56) References JP-A-7-187683 (JP, A) JP-A-7-138028 (JP, A) JP-A-62-187135 (JP, A) JP-A-7-187684 (JP, A) , A) JP 2-31010 (JP, B2) JP 5-7326 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/32 C03B 8/04 F23D 14/22

Claims (4)

(57) [Claims] 1. At least three concentrically arranged cross-sections
It consists of two straight pipe nozzles, and jets a gaseous mixture of alkoxysilane and inert gas from the innermost nozzle, and oxygen, a mixed gas of oxygen and inert gas, or an inert gas from the middle nozzle. A first nozzle group for ejecting hydrogen from the outermost nozzle; and a plurality of nozzles arranged around the first nozzle group, wherein the center line of at least one nozzle is the first nozzle group. Group of conical surfaces that intersect at the intersection of the center line of the nozzles with the gas ejection side, and whose vertex is the intersection of the center line of each nozzle and the center line of the first nozzle group, and whose center line is a line element Is provided so as not to intersect with each other at least in a region including each nozzle, except when the same conical surface is provided.
A second nozzle group for ejecting oxygen; and an outermost nozzle for ejecting hydrogen disposed so as to cover the first and second nozzle groups. , Particle size
A burner for producing spherical silica fine particles having a cloth of 0 to 3 μm . 2. The second nozzle group, wherein the nozzles are arranged at equal intervals on at least one concentric circle in cross section sharing the center line of the first nozzle group. The burner for producing spherical silica fine particles according to the above. 3. The method according to claim 2, wherein the center line of the first nozzle group and the second
The distance between a group of intersections of the nozzle groups of the nozzle groups with the center line of each nozzle and a common open surface formed by an end surface of the nozzle group on the side from which gas is ejected is in the range of 100 to 200 mm. The burner for producing spherical silica fine particles according to claim 1 or 2. 4. The burner for producing spherical silica fine particles according to claim 1, wherein the first and second nozzle groups and the outermost nozzle are made of quartz glass.